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Poly(methylenephosphine)s : homo- and copolymers bearing conjugated substituents Chun, Cindy Patricia 2009

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POLY(METHYLENEPHOSPHINE)S: HOMO- AND COPOLYMERS BEARING CONJUGATED SUBSTITUENTS  by Cindy Patricia Chun  Hon. B.Sc., The University of Toronto, 2006  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE  in  THE FACULTY OF GRADUATE STUDIES  (Chemistry)  THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) March 2009  © Cindy Patricia Chun, 2009  11  Abstract New P-Mes (Mes  =  2,4,6-trimethyiphenyl) phosphaalkenes bearing conjugated C  substituents have been prepared: MesP=C(Naph)(Ph) (Naph = 1-naphthyl) (la), MesP=C(Phen)(Ph) (Phen = 9-phenanthrenyl) (ib), and MesP=C(C S)(Ph) (C 3 H 4 S 3 H 4  =  2-  thienyl) (lc). Compounds la and ic were prepared by the base-catalyzed phospha-Peterson reaction, whereas lb was prepared via the standard phospha-Peterson route. Anionic polymerization of la and lb afforded [MesP—C(Naph)(Ph)] (2a) and [MesP—C(Phen)(Ph)] (2b), respectively. The anionic polymerization of ic was attempted, but there was no polymer formation. Poly(methylenephosphine)s 2a and 2b were chemically functionalized at the phosphorus 3 moeities. The electronic properties of la, ib, 2a, centres by oxidation and coordination to BH 2b, and the functionalized polymers were investigated by UV/Vis and fluorescence spectroscopy. The results showed that naphthyl-derivatized phosphaalkene la and poly(methylenephosphine) 2a were non-emissive, whereas the functionalized naphthyl derivatized polymers emitted in the UV region when excited at 288 nm. Similarly, for the phenanthrenyl-derivatized species, phosphaalkene lb and phosphine polymer 2b were observed to be weakly fluorescent in comparison to the more emissive functionalized polymers. These results are consistent with the sensory behavior exhibited by “turn-on” chemical sensors. The phosphaalkene monomer, MesP=CPh 2 (3) was copolymerized with styrene (Sty) using radical initiator 1,1 ‘-azobis(cyclohexanecarbonitrile) over a range of monomer feed ratios to afford poly(methylenephosphine)-co-polystyrene (PMP-co-PS) copolymers. The compositions of these copolymers were evaluated using inverse gated proton decoupled 13 C NMR spectroscopy. An adaptation of the Tidwell-Mortimer experimental approach was  111  employed to calculate reactivity ratios for the PMP-co-PS system. The first step of the approach involved a preliminary estimation of the reactivity ratios by the Fineman-Ross linearization and the Mayo-Lewis intersection method. Using the preliminary estimates, the Tidwell-Mortimer heuristic rules were applied to determine optimal feed compositions for further experimentation. Lastly, a nonlinear least squares regression was performed to provide the best estimates of the reactivity ratios  (rpA  =  0.11 and rs  =  0.24). Based on these r values, Q-e  reactivity parameters  of phosphaalkene 3 were computed and the microstructure of PMP-co-PS was examined which revealed an alternating pattern of phosphaalkene and styrene units in the copolymer backbone.  iv  Table of Contents Abstract  .  Table of Contents  ii  iv  List of Tables  viii  List of Figures  ix  List of Charts  xi  List of Abbreviations  xii  Acknowledgements  xviii  Dedication  xix  Statement of Co-authorship  xx  Chapter One 1.1  Introduction  Phosphorus-Containing Polymers 1.1.1  Polyphosphazenes and Derivatives  1.1.2  Polymers with Phosphorus and Other Inorganic  1.1.3  1 1 2  Elements in the Backbone  4  n-Conjugated Polymers containing Phosphorus in the Main Chain  6  1.1.3.1 Phosphole-Based n-Conjugated Polymers  6  1.1.3.2 Poly(arylphosphine)s  11  1.1.3.3 Phosphorus Analogues of PPV  12  1.1.4  Unconjugated Phosphorus-Carbon Polymers  16  1.2  Brief History of Poly(methylenephosphine)s  17  1.3  Research Objectives  21  1.4  Contributions by Other Researchers to This Work  23  V  1.5  References  Chapter Two  .24  Synthesis and Polymerization Studies of New Phosphaalkenes Bearing Conjugated Substituents  29  2.1  Introduction  29  2.2  Results and discussion  31  2.2.1  Synthesis of Phosphaalkene 2.1  31  2.2.2  Synthesis of Phosphaalkene 2.2  34  2.2.3  Synthesis of Phosphaalkene 2.3  36  2.2.4  X-ray Crystallographic Analysis of Phasphaalkenes 2.1 —2.3  38  2.2.5  Polymerization Studies of Phosphaalkene Monomers 2.1  46  —  2.3  2.3  Summary  53  2.4  Experimental Section  53  2.5  2.4.1  Preparation of MesPC(Naph)(Ph) (2.1)  54  2.4.2  Preparation of MesP=C(C S)(Ph) (2.2) 3 H 4  55  2.4.3  Preparation of MesP=C(Phen)(Ph) (2.3)  55  2.4.4  Preparation of [MesP—C(Naph)(Ph)] (2.4)  56  2.4.5  Attempted preparation of [MesP—C(C S)(Ph)] 3 H 4  57  2.4.6  Preparation of [MesP—C(Phen)(Ph)] (2.5)  57  2.4.7  X-ray crystallography  58  References  Chapter Three  Chemical Modification of Poly(methylenephosphine)s with Conjugated Substituents Accompanied by Changes in Electronic Properties  3.1  59  Introduction  62 62  vi 3.2  Results and discussion  .64  3.2.1  Oxidation of 3.2a and 3.2b  64  3.2.2  Boronation of 3.2a and 3.2b  67  3.2.3  UV/Vis and Fluorescence Measurements of 3.la  3.2.4  UV/Vis and Fluorescence Measurements of 3.lb  —  —  3.4a  69  3.4b  74  3.3  Summary  78  3.4  Experimental section  79  3.4.1  Characterization of MesPC(Naph)(Ph) (3.la)  80  3.4.2  Characterization of MesPC(Phen)(Ph) (3.lb)  80  3.4.3  Characterization of [MesP—C(Naph)(Ph)J (3.2a)  80  3.4.4  Characterization of [MesP—C(Phen)(Ph)] (3.2b)  80  3.4.5  Preparation of [MesP(O)—C(Naph)(Ph)] (3.3a)  81  3.4.6  Preparation of [MesP(O)—C(Phen)(Ph)] (3.3b)  81  3.4.7  Preparation of 1 )—C(Naph)(Ph)J (3.4a) 3 [MesP(BH  82  3.4.8  Preparation of {MesP(BH )—C(Phen)(Ph)] (3.4b) 3  82  3.4.9  General procedure for preparing solution samples for UV/Vis and fluorescence measurements  3.5  References  Chapter Four  83 84  Radical Copolymerization of P=C and C=C Bonds: Reactivity Ratios of Phosphaalkene-Styrene Copolymers  86  4.1  Introduction  86  4.2  Results and discussion  89  vii 4.2.1  Analysis of Copolymer Composition by Inverse Gated Proton Decoupled ‘ C NMR Spectroscopy 3  89  4.2.2  Experimental Design and Preliminary Estimation of rPA and  92  4.2.3  Application of Heuristic Rules  96  4.2.4  Determination of  98  4.2.5  Q-e values of PA and the Microstructure of PMP-co-PS  and  by Nonlinear Least Squares Regression  99  4.3  Summary  102  4.4  Experimental section  102  4.4.1  General procedure for synthesis of PMP-co-PS  4.4.2  General procedure for processing ‘ C NMR spectra and determining 3 copolymer composition  4.5  References  Chapter Five  Overall Conclusions and Future Work  104  104 106 109  5.1  Summary of Thesis Work  109  5.2  Future Work  113  5.2.1  Towards Poly(methylenephosphine)-Based Chemical Sensors  113  5.2.2  Copolymerization of Phosphaalkenes  113  5.3  Closing Remarks  114  5.4  References  115  viii  List of Tables Table 1.1  Summary of selected characterization data for 1.5, 1.7a-c, 1.10— 1.13  Table 1.2  Summary of selected characterization data for 1.16a-d and 1.17  14  Table 2.1  X-ray crystallographic data for E-2.1, 2.2 (E/Z mixture), and Z-2.3  42  Table 2.2  Important metrical parameters for E-2.1, E-2.2, Z-2.2, Z-2.3, 2 and MesPCPh  7  43  Table 3.1  Summary of UV/Vis absorption bands and assignments of 3.la  Table 3.2  Summary of emission measurements on 3.la  Table 3.3  Summary of UV/Vis absorption bands and assignments of 3.lb —3.4b  75  Table 3.4  Summary of emission measurements on 3.lb  77  Table 4.1  Comparison of copolymer compositions measured by inverse gated  —  —  —  3.4a  3.4a  3.4b  69 72  proton decoupled ‘ C NMR spectroscopy and elemental analyses 3  91  Table 4.2  Summary of copolymerization experimental data  93  Table 4.3  Approximation of rpA and  95  Table 4.4  Summary of experimental data from copolymerizations according to optimal conditions  Table 4.5  97  Average sequence length of monomers units (lmonomer) and run number (R) of PMP-co-PS copolymers  101  ix  List of Figures Figure 2.1  P NMR spectrum (THF, 122 MHz) of 2.1 (E/Zmixture) formed 31 after 2 weeks  32  Figure 2.2  , 400 MHz) of E-2.1 3 ‘H NMR spectrum (CDC1  33  Figure 2.3  ’P NMR spectra (THF, 122 MHz) of 2.2 (E/Zmixture) after 5 d 3  35  Figure 2.4  ‘H NMR spectrum (C , 400 MHz) of 2.2 (E/Z mixture) D 6  35  Figure 2.5  P NMR spectrum (THF, 122 MHz) of 2.3 (E/Z mixture) formed 31 10 minutes after the addition of ketone to silyl phosphide  37  Figure 2.6  ‘H NMR spectrum (C , 400 MHz) of 2.3 D 6  38  Figure 2.7  Molecular structure E-MesPC(Naph)(Ph) (E-2.1)  39  Figure 2.8  Molecular structure of MesPC(C S)(Ph) (2.2) 3 H 4  40  Figure 2.9  Molecular structure Z-MesPC(Phen)(Ph) (Z-2.3)  41  Figure 2.10  The crystal packing of Z-2.3  45  Figure 2.11  P NMR spectrum (THF, 122 MHz) of isolated polymer 2.4 31  47  Figure 2.12  GPC trace of 2.4  48  Figure 2.13  P NMR spectrum (THF, 122 MHz) of isolated polymer 2.5 31  49  Figure 2.14  GPC trace of 2.5  50  Figure 2.15  NMR spectra (THF, 122 MHz) of aliquots removed from the reaction between 2.3 and one equivalent of MeLi  52  Figure 3.1  ’P NMR spectra (THF, 122 MHz) of 3.3a 3  65  Figure 3.2  ’P NMR spectra (THF, 122 MHz) of 3.3b 3  66  Figure 3.3  ’P NMR spectra (THF, 122 MHz) of 3.4a 3  68  Figure 3.4  P NMR spectra (THF, 122 MHz) of 3.4b 31  68  x Figure 3.5  UV/Vis spectra (THF) of 3.la  Figure 3.6  Emission spectra (THF) of 3.la  Figure 3.7  Orbital energy diagram illustrating the process of the photoinduced  —  3.4a —  3.4a  .70 72  electron transport mechanism and the resulting effect on fluorescence of a fluorophore  73  Figure 3.8  UV/Vis spectra (THF) of 3.lb  Figure 3.9  Emission spectra (THF) of 3.lb  Figure 4.1  Inverse gated proton decoupled ‘ C NMR spectrum (CDC1 3 , 101 MHz) 3  —  3.4b —  3.4b  of a PMP-co-PS Figure 4.2  90  t  Figure 4.5  92  Fineman-Ross plot of G versus F for PA/Sty copolymerization experiments  Figure 4.4  76  Monomer conversions of copolymerization experiments carried through different  Figure 4.3  74  94  PA/Sty copolymerization data plotted according to the Mayo-Lewis intersection method  96  Nonlinear least squares curving fitting of copolymerization data  98  xi  List of Charts Chart 4.1  Flowchart illustrating the Tidwell—Mortimer approach to determining reactivity ratios  89  xii  List of Abbreviations Anal.  analysis  aq.  aqueous  Ar  aryl  a.u.  arbitrary units  A Wp  atomic mass of phosphorus  br  broad (spectra)  Bu  butyl  n-Bu  n-butyl  i-Bu  iso-butyl  sec-Bu  sec-butyl  C  Celsius  ca.  circa  Calcd  calculated  CAr  integration value of the chemical shift assigned to aryl carbons  cat.  catalytic  CD  circular dichroism  CMe  integration value of the chemical shift assigned to methyl carbons  COD  1 ,5-cyclooctadiene  Cp  cyclopentadienyl  d  day doublet (spectra)  dba  dibenzylideneacetone  xlii  dn/dc  refractive index increment  DP  degree of polymerization  DSC  differential scanning calorimetry  DVDS  divinyltetramethyldisiloxane  e  polarity parameter according to Aifrey-Price Q-e scheme  E  electrophile energy  E  entgegen (configuration)  EA  elemental analysis  e.g.  for example  El  electron impact  epA  polarity parameter of mesityldiphenylphosphaalkene according to Aifrey-Price e scheme  eq  equation  equiv  equivalent(s)  , 5 e  polarity parameter of styrene according to Alfrey-Price Q-e scheme  Et  ethyl  et al.  and others  exp  exponential function  FW  formula weight  FWPA  formula weight (or molar mass) of phosphaalkene  1 FWs  formula weight (or molar mass) of styrene  GOF  goodness of fit (crystallography)  Q  xiv GPC  gel permeation chromatography  h  hour  HOMO  highest occupied molecular orbital  HPLC  high-performance liquid chromatography  I  ipso  i.e.  that is  ‘PL  intensity of photo luminescence  JR  infrared  k  rate constant  K  kelvin wavelength  A2  red shift  em 2  wavelength of emission  ex  wavelength of excitation  umax  absorption maximum  ‘PA  average sequence length of consecutive phosphaalkene units  ‘sty  average sequence length of consecutive styrene units  LLS  laser light scattering  LUMO  lowest unoccupied molecular orbital  m  multiplet (spectra)  M  molecular ion  Me  methyl  Mes  mesityl; 2,4,6-trimethylphenyl  xv  MHz  megahertz  mm  minute number average molecular weight  mol  mole  mpA  mole fraction of phosphaalkene in the copolymer composition  MPA  mole fraction of phosphaalkene in the monomer feed  MS  mass spectrometry  53 m ,  mole fraction of styrene in the copolymer composition  Ms  mole fraction of styrene in the monomer feed weight average molecular weight  m/z  mass-to-charge ratio  Naph  1 -naphthyl  NMR  nuclear magnetic resonance  o  ortho  OTf  trifluoromethanesulfonate; CF 3 503  OLED  organic light emitting diode  PPL  quantum yield of photoluminescence  p  para  PA  mesityldiphenylphosphaalkene  PDI  polydispersity index  %FEA  percent of phosphorus detected by elemental analysis  Ph  phenyl  Phen  9-phenanthrenyl  xvi  PLED  polymer-based light emitting diode  PMP  poly(methylenephosphine)  PMP-co-PS  poly(methylenephosphine)-co-polystyrene  ppm  parts per million  PPV  poly(p-phenylenevinylene)  PS  polystyrene  Q  reactivity parameter from Aifrey-Price Q-e scheme  QPA  reactivity parameter of mesityldiphenylphosphaalkene from Aifrey-Price Q-e scheme  Qsty  reactivity parameter of styrene from Aifrey-Price Q-e scheme  r  reactivity ratio  R  average number of sequences per 100 units, also known as run number  R or R’  side group  ref.  reference  RMSE  root mean squared error  ROP  ring-opening polymerization  rpA  monomer reactivity ratio of mesityldiphenylphosphaalkene monomer reactivity ratio of styrene  RT  room temperature  s  second singlet (spectra)  sh  shoulder  Sty  styrene  xvii t  time  1 T  spin lattice relaxation  Temp  temperature  Tg  glass transition  THF  tetrahydrofuran  TMEDA  N, N, N N’-tetramethylethylenediamine  UV  ultraviolet  UV/Vis  ultraviolet/visible  VAZO 88  1,1 ‘-azobis(cyclohexanecarbonitrile)  vs.  versus  X  monomer conversion  XPA  monomer conversion of mesityldiphenylphosphaalkene  Xs  monomer conversion of styrene  Z  zusammen (configuration)  xviii  Acknowledgements Professor Derek P. Gates For advice (scientific and non-scientific), patience, encouragement, and reference letters Dr. Mandy Yam, Dr. Bronwyn Gillon, Dr. Kevin Noonan, Dr. Vittorio Cappello, Josh Bates, Julien Dugal-Tessier, Paul Siu, Line Christiansen, and former and present undergrads For help in the lab and good times Mario Ulises Delgado Jaime, Matt Roberts, Tim Kelly, Derrick Lee, and Fergus Chung For assistance with certain components of this work (MATLAB, instrumentation, statistics, and collaboration) Professor Mark MacLachlan and Professor Ed Grant For reference letters Staff in Department of Chemistry (UBC) For their assistance, and technical and administrative support NSERC, UBC, and Department of Chemistry (UBC) For financial support Steph Lee, Insun Yu, Joseph Hui, and my karaoke buddies For fun times, yummy food, tvb soaps, and for passing the mic Mommy, Dad,  ,  and  For unconditional love and support Michael, Lily, Andrew, and Sarah For being a good brother/sister Neal Yonson For assistance, support, encouragement, patience, and love  xix  Dedication  To my mother  xx  Statement of Co-authorship The results presented in Chapters 2 and 3 will be submitted for publication in due course. A version of Chapter 4 has been prepared as a manuscript to be submitted for publication shortly. A detailed account of contributions by other researchers is stated below and included in Section 1.4 (Page 23). Some of the work in this thesis was achieved in collaboration with other researchers. For Chapter 2, all of the synthetic work was done by myself with the exception of the synthesis and S)(Ph) (C 3 H 4 recrystallization of MesP=C(C S 3 H 4  =  2-thienyl), which was a collaborative effort  between myself and Fergus Chung. Fergus was an undergraduate researcher under my supervision. All crystallographic data were obtained primarily by Josh Bates with some assistance from Paul Siu using the departmental X-ray diffractometer. The solution and refinement of the molecular structures of MesP=C(Naph)(Ph) (Naph  =  1 -naphthyl) and  S)(Ph) were completed by Josh. The solution and refinement of the molecular 3 H 4 MesP=C(C structure of MesP=C(Phen)(Ph) (Phen  =  9-phenanthrenyl) were performed by Paul. All of the  work presented in Chapters 3 and 4 was completed by myself.  1  Chapter One Introduction  1.1 Phosphorus-Containing Polymers Since the discovery of “inorganic rubber” by Stokes in the 1 89Os,1 history has witnessed an exciting evolution of inorganic polymers with phosphorus atoms in the main chain. 59 “Inorganic rubber”, which is actually a crosslinked form of poly(dichlorophosphazene), was first prepared by the thermal ring-opening polymerization (ROP) of hexachiorocyclotriphosphazene (Scheme 1.1, Route A). The resulting material was insoluble and hydrolytically unstable. Due to its intractability, “inorganic rubber” remained a chemical curiosity until the 1 960s. That was when Allcock and Kugel showed that the carefully controlled ROP of sublimed hexachlorocyclotriphosphazene afforded uncrosslinked poly(dichlorophosphazene) (1.1 a) which was soluble in organic solvents (Scheme 1.1, Route  Nearly half a century after this  discovery, research on polyphosphazene-based materials continues to grow.” 2 Route A “inorganic rubber”  heat  Route B  ci  Cl  sublime  250 °C  60-65 °C  in vacuo  CI  [  ,  1.la Scheme 1.1 The discovery of polyphosphazenes has also inspired the development of other polymers with phosphorus atoms in the main chain. ” The synthesis of phosphorus-containing polymers, 59 like that of other inorganic macromolecules, is challenging but offers the potential of accessing new materials with useful and interesting properties.’ 3 This introduction will feature some  References begin on page 24  Chapter One  2  examples of phosphorus-containing polymers to demonstrate their uniqueness and highlight the strategies employed to overcome synthetic obstacles.  1.1.1 Polyphosphazenes and Derivatives  Polyphosphazenes comprise the most heavily studied class of main group polymers.” 2 As mentioned in the introduction, the preparation of poly(dichlorophosphazene) (1.la) via thermal ROP of pure hexachiorocyclotriphosphazene affords a material that is soluble in organic solvents. However, 1.la is unstable due to its hydrolytically sensitive P—Cl bonds. This reactive polymeric species can be treated with nucleophiles in a macromolecular substitution approach, allowing replacement of the chlorine groups by alkoxide, aryloxide, or amino groups to afford a wide range of hydrolytically stable polyphosphazenes (1.lb) (Scheme Macromolecular substitution  1  91 -I-P=N--I-  [  1 ia  Polycondensation  1  2 NaR or HR  R  =  heat  -1—P=N±  [  2 NaCI or HCI  —  l.2).b0h114  alkoxide, aryloxide, NHR or NR’R”  j  —  OCH 3 SiMe C 2 F  S1NP-OCH 3 Me C 2 F  1.lb-c b: R  =  R  =  C:  alkoxide, aryloxide, NHR’ or NR’R” alkyl or aryl  Scheme 1.2  There are other methods to prepare polyphosphazenes. A polycondensation method was developed in the mid-1980s by Neilson and Wisian-Neilson and their co-workers to afford 1.lc, which has alkyl or aryl side groups (Scheme 1.2). 15,16 The number average molecular weight (Ma) of these polymers ranged between 29,000 g moi’ and 94,500 g mol’, and the polydispersity index (PDI) of 1.lc ranged between 1.7 and 2.2.  References begin on page 24  Chapter One  3  In 1995, Honeyman et al. reported an ambient temperature route using PCi 5 (Scheme 1 3),17 affording poly(dicholorophosphazene) 1.la of controllable molecular weights and low polydispersity (PDI  =  1.04), a feat that was unprecedented for polyphosphazenes. While the  original polymer prepared by Alicock and Kugel contained about 370 PN units in the backbone,’° the average number of PN units in the poly(dicholorophosphazene) prepared by Honeyman et al. was 55 units. There are many other methods reported for the preparation of polyphosphazenes,” however it is beyond the scope of this introduction to describe each one.  r  P=NSiMe CI 3  —f-P=N  [ci 1.la Scheme 1.3 With over 300 known examples,” the wide structural diversity of polyphosphazenes gives rise to materials with unique properties including: flame-resistance, hydrophilicity or hydrophobicity, amorphous or microcrystalline structure, or with nonlinear optical, liquid crystalline or photochromic properties. Important applications of polyphosphazenes include dental liners, fuel liners, and flame-retardant materials. 2 ” 11 Similar to polyphosphazenes are poly(thionylphosphazene)s (1.2), which have phosphorus, nitrogen and sulfur atoms in the backbone.’ ’ Polymers of 1.2 containing 82  [(9)  ‘  tN=N [R R’ 1.2  hydrolytically sensitive sulfur(IV)—nitrogen bonds were first reported by Allcock and co-workers in 1990.18 In 1991, Liang and Manners reported the preparation of the more stable sulfur(VI) 19 Both groups had prepared 1.2 analogue by ROP of a cyclic thionyiphosphazene at 165 oC.  References begin on page 24  Chapter One bearing chlorine substituents (i.e R = R’  4 =  Cl), which could be replaced by aryloxy or amino  groups via macromolecular substitution. Turner and co-workers extended the work on poly(thionylphosphazene)s by synthesizing polymers in which the substituents are alkyl group s. 20 Remarkable properties of poly(aminothionylphosphazene)s, derivatives of 1.2 (R = R’  =  amino groups), include high free volume in the material, as demonstrated by studies of gas 22 Some of these polymers have glass transitions, permeability, high solubility and processability. Tg’s, below —10 °C, an important characteristic that allows for large-scale conformational  motions for effective gas diffusion. 24 Block copolymers, poly(aminothionylphosphazene)-b ’ 23 poly(tetrahydrofuran) have found application as matrices for fluorescent dyes which are very effective as photoluminescent oxygen sensors for pressure-sensing composite ’ 22 technology. 2 5 6  1.1.2 Polymers with Phosphorus and Other Inorganic Elements in the Backbone A rare example of a phosphorus-containing polymer is poly(ferrocenylphosphine) (1.3) because the backbone includes not only phosphorus atoms but also the transition metal iron. 2729 These polymers were first prepared by Seyferth and co-workers in 1982 by a condensation polymerization involving dilithioferrocene, N, N, N N’-tetramethylethylenediamine (TMEDA) 27 In 1996, Manners and co-workers discovered that and PhPC1 2 (Scheme 1.4, Route A). phosphorus-bridged ferrocenophanes could undergo thermal ROP to afford  1.3.28  Shortly  thereafter, they reported that the ROP could also proceed in a living fashion by an anionic method at room temperature provided that the starting monomers were of high purity (Scheme 1.4, Route B). 29  References begin on page 24  Chapter One  5  Me 2 —Li N Fe N  )  Route A +  Ph i4  2 PhPCI  Fe  j  2) H 0 2  Fe  P—Ph  1.3  Scheme 1.4 The living route allowed access to well-defined architectures such as block copolymers of poly(ferrocenylphenylphosphine)-b-poly(dimethylsiloxane) and poly(ferrocenylphenylphosphine)-b-poly(ferrocenyldimethylsilane) 29 In addition to opening the door to the construction of specially designed macromolecular architectures, living polymerization in general allows one to access polymers of narrow polydispersities and to control their molecular weights by varying the monomer:initiator ratio. Another interesting class of phosphorus-containing polymers is polyphosphinoboranes (1.4), which are composed alternating four-coordinate boron and phosphorus atoms in the skeleton chain. 3 Cyclic phosphinoboranes have been known since the 1950s. ’ 30 32 There is limited documentation of polyphosphinoboranes from that time, and product characterization was only partially reported or not reported at all. 34 In 2000, the preparation of ’ 33 polyphosphinoboranes 1.4 was reported by Manners and co-workers which involved a rhodiumcatalyzed dehydrocoupling of 3 BH (Scheme l.5).° Interestingly, 1.4 is air and water stable 2 RPH in the solid state, but has low thermal stability.  •BH 2 RPH 3  [Rh] 100-120°C 2 H  ER I I 2 -j-P—BH [H  —  R  =  n  1.4 Ph, i-Bu, p-n-BuC , 4 H 6 or p-dodecylC 4 H 6  Scheme 1.5 References begin on page 24  Chapter One  6  1.1.3 it-Conjugated Polymers containing Phosphorus in the Main Chain 1.1.3.1 Phosphole-Based it-Conjugated Polymers  Inorganic materials based on polypyrrole and polythiophene architectures are widely known and have been extensively studied with regard to their synthesis, conductivity, and photochemical properties. Phosphole, the phosphorus analogue of pyrrole and thiophene, has also recently been investigated for incorporation into extended it-conjugated structures. 35 8 ’ 6 Phosphole-containing it-conjugated polymers are interesting candidates for applications involving organic or polymer-based light emitting diodes (OLED5/PLED5) and chemical 3638 Due to the versatile reactivity of trivalent three-coordinate phosphorus (i.e. sensors. complexation to Lewis acids or transition metals, oxidation), ° electronic tuning of phosphole 4 ’ 39 containing it-conjugated materials should be feasible, giving a diversity of properties and 35 Table 1.1 summarizes the key physical and electronic properties of the 7 6 functions. 4 ’ phosphole-based polymers which will be discussed in this section. The first report of phospholes being integrated into it-conjugated systems occurred in 1990 when Mathey and co-workers reported their work on oligomers containing two phosphole and four thiophene units. 42 In 1997, Mao and Tilley synthesized the first it-conjugated polymer containing phosphole moieties in the backbone. 43 The synthesis of the biphenyl-bridged phosphole polymer (1.5) was achieved using a zirconocene-coupling method (Scheme 1.6). The different regiochemistry in 1.5 originated from its precursor and was confirmed by 111 ‘ C, and 3 P NMR spectroscopy. Interestingly, 1.5 exhibited photoluminescence in the visible blue-green 31 region  =  470 nm). Its Stokes shift of 157 nm is large in comparison to the range of Stokes  shifts reported for other phosphole-containing it-conjugated polymers (Table 1.1). Analysis of 1.5 by gel permeation chromatography (GPC) suggested that it exhibited an M value of 6,200 g  References begin on page 24  Chapter One  7  Table 1.1 Summary of selected characterization data for 1.5, 1.7a-c, 1.10  1.5  (nm) 308  Ar (nm) 62  / [X] (nm) 470 / [313]  Stokes shift (nm) 157  1.7a  410  56  490/[410]  1.7b  414  60  1.7c  382  1.10 1.11  polymer  ‘rnax  1.12  b  1.13. PDI  ref.  0.092  11 (g moE’) / M [DP] 6,200 / [17]  2.58  43  80  0.09  10,200/[15]  1.5  45  487/[410]  77  0.14  10,000/{121  1.4  45  28  435 / [390]  45  0.08  6,800 / [7]  1.3  45  378  21  460/[378]  82  0.562  8,000/[15]  3.1  46  353 (sh), 393 456 (sh), 502 345, 485  10  459 / [393]  66  0.566  10,000 / [20]  3.2  46  123  555 / [502]  53  -  -  -  ?‘.em  4PL  0.47 24 509, 540 / 5,800 / [9] [485] polymer compared to the of max of model compounds (i.e. red shift). 2 max 2 = quantum yield of photoluminescence. 1.13  a  —  LN:J n  109  37 47  1.7  ZrCI 2 Cp , 2 Zr 2 Cp R  O.8n  2n  —  PhPCI  RR  Ph  \  A  O.8n  / “O.2n_  1.5 A  =  CH 4 ) 2 (CH 3  Scheme 1.6  References begin on page 24  Chapter One  8  mol’, which translates to approximately 17 repeat units. While this number of repeat units seems rather low, it is similar to the degree of polymerization (DP) for other phosphole-based polymers listed in Table 1.1. A common synthetic challenge shared by researchers in this field is increasing the DP values. Another convenient method to access phosphole-containing n-conjugated polymers was reported by the Réau group which involved the electropolymerization of a protected 2,5-bis(2thienyl)phosphole followed by deprotection (Scheme 1  7)38.44  This resulted in a material that  was insoluble in common organic solvents, and thus no GPC data were reported. Remarkably, the phosphorus centres in 1.6 were strongly coupled to the conjugated system along the backbone, and could act as receptor sites for elemental chalcogenides in chemical sensing 38 The sensor properties were evaluated by using optical and electrochemical experiments. responses measured by UV/Vis spectroscopy and cyclic voltammetry. In the presence of Sg or Se, bathochromic shifts were observed in the UV/Vis spectra and positive shifts of the oxidation current offset were observed in the cyclic voltammograms.  PPh  Ogfl  AucI  AucI  Scheme 1.7 More phosphole-containing n-conjugated polymers (1.7a-c) were prepared by Chujo and co-workers via the Heck-Sonogashira reaction. 45 The palladium-catalyzed coupling of bis(p bromophenyl)phosphole with diethynylarenes (Scheme 1.8) afforded 1.7a-c, which have extended n-conjugation. The extension of the n-conjugation was supported by UV/Vis data: the absorption bands of the polymers were red-shifted compared to the absorption band of the  References begin on page 24  Chapter One  9  Heck-Sonagashira coupling  Ph +  Ar 1.7a-c  -Ar-  =  _1çj.[.  25 H 12 0C  15 C 2 H 0 2  25 H 12 0C  13 H 6 0C  or 15 C 2 H 0 2  13 H 6 C 0 a  b  c  Scheme 1.8 phosphole compound, 1.8. Interestingly, 1.7a (M 10,000 g mol’; PDI g mol’; PDI  =  =  10,200 g mol’; PDI  =  1.5) and 1.7b (M  1.4) were green emitters when irradiated at 410 nm, and 1.7c (M 11  =  =  6,800  1.3) emitted blue light when excited at 390 nm (see Table 1.1). In this sense,  electronic properties of 1.7 can be tuned by varying the conjugated spacer in the main chain.  There are also polymers based on dithienophosphole (1.9), originating from the research group of ’ 37 Baumgartner. 4 6 The advantage offered by the annelated ring system is 7 maximization of the it-overlap by forcing a coplanar geometry.  Ph 1.9  References begin on page 24  Chapter One  10  Using PtDVDS (DVDS  =  divinyltetramethyl disiloxane), Baumgartner and co-worker  synthesized polymers 1.10 and 1.11 (Scheme 1.9) with M values up to 8000 g mof’ and 10,000 46 Compared to other phosphole-containing polymers, 1.10 and 1.11 have g mol’, respectively. relatively high PDI values (Table 1.1). The absorption and emission properties of 1.10 and 1.11 are very similar to those of their respective model compounds, suggesting a nearly localized it system. This is not surprising since it is expected that the —SiMe — moieties would inhibit it 2 delocalization from one dithienophosphole unit to the next.  1.10 SiSiMe HMe H 2  Ph’O  n 1.11  Scheme 1.9 Dithienophosphole-based it-conjugated polymers, 1.12 and 1.13, were obtained via a Stille coupling and Suzuki-Miyaura coupling, respectively (Scheme  The absorption  and emission properties of 1.12 and 1.13 were strongly red-shifted compared to those of the corresponding monomers  2 . 1 (A?. i  =  123 nm; A?. 13 . 4  =  109 nm; see Table 1.1). These data suggest  significant iu-delocalization along the conjugated backbone. Both polymers fluoresce in the yellow-green region of the visible spectrum. Despite having long alkoxy chains, 1.12 exhibits poor solubility in THF, and thus the investigators have been unable to analyze 1.12 by GPC. The Stokes shift reported for 1.13 is small compared to those of other phosphole-based polymers (see  References begin on page 24  Chapter One  11  R +  A  Stille coupling  1*1  1.12  A  +  Ph  =  0C 1 H 8 7  B—-B(oH) 2 (HO)  Me  13 H 6 C  13 H 6 C  Ph’ Me  13 H 6 C  13 H 6 C  1.13  Scheme 1.10  Table 1.1), which was attributed to rigidity in the main chain. In addition to the extended t conjugation, the ionic nature of 1.13 makes this material a promising candidate for conjugated 47 polyelectrolyte applications.  1.1.3.2 Poly(arylphosphine)s Poly(arylphosphine)s (1.14) comprise a class of polymers developed by Lucht and co ° In 2000, Lucht and St. Onge reported the synthesis of poly(p-phenylenephosphine)s 485 workers. (1.14a) by a palladium-catalyzed carbon-phosphorus bond formation (Scheme 1.1 1).48 The M 11 of 1.14a varied between 1,300 g mol’ and 3,100 g mo[ , depending on the R substituent (isobutyl, 1  phenyl or 2,4,4-trimethylpentyl) on the phosphorus centre. The number of repeat units ranged between 7 to 14 units. The intriguing feature of 1.14a was the spectroscopic evidence for electronic delocalization along the backbone which must formally pass through the phosphorus atoms. The extended ar-conjugation was supported by red shifted optical absorptions (Az. nm for 1.14a R  30  Ph) and lower oxidation potentials of the polymers compared to model  References begin on page 24  Chapter One  12  compounds. These results are puzzling because the type and degree of overlap between the lone pair on phosphorus and the adjacent aromatic groups are unclear. 4 ) 3 Pd(PPh I—Ar—I  +  2 RPH  F  1  2 Ni(COD)  —--Ar_P-j-  —  I  —  Br—---P—-(—Br  ‘  1 .14a-b a:  —Ar—  =  b:  —Ar—  =  —--——-  ,  R  =  i-Bu, Ph, or 2,4,4-trimethylpentyl  ,  R  =  2,4,4-trimethylpentyl  Scheme 1.11  In 2002, Lucht and Jin reported an extension of their work that employed palladium and nickel mediated coupling, as shown in Scheme 1.11, to prepare poly(arylphosphine)s in which the aryl group was biphenyl. 49 The M value of 1.14b was 3,100 g mol’, which suggested approximately 10 repeat units. The low molecular weights and low number of repeat units in 1.14a and 1.14b were attributed to poor solubility, consequently precipitating out of the reaction  mixture before higher molecular weight polymers could be attained. In 2005, Lucht and Jin prepared poly(p-phenylenephosphine)-co-polyaniline. ° Like 5 1.14a, characterization of the copolymer obtained by UV/Vis spectroscopy and cyclic  voltammetry provided the spectroscopic evidence for extended n-conjugation through the copolymer backbone, which must formally pass through the trivalent phosphorus centres. More interestingly, oxidation of the phosphorus centres to phosphine oxides inhibited the electronic delocalization, suggesting participation from the phosphorus lone pair in the conjugated system when phosphorus was in the trivalent state.  1.1.3.3. Phosphorus Analogues of PPV  Poly(p-phenylenephosphaalkene)s 155 comprise a very interesting class of conjugated 5  References begin on page 24  Chapter One  13  phosphorus-containing polymers because they represent the phosphorus analogues of poiy(p phenylenevinylene) (PPV), a luminescent organic macromolecule. The first example, 1.15a, was reported in 2002 by Wright and Gates and was achieved by thermolysis of tetramethylterephthaloyl chloride and 3 P (SiMe 4 H 6 , 2 ) P(SiMe -C eliminating 3 SiMe C l (Scheme 1.12).’  P—Ar—P(SiMe (SiMe 2 ) 3  85°C  I?  +  C—Ar—C  ci  bi  —  23 SIMe C I  1.15a—b a:  —Ar—  =  b:  —Ar—  =  —;::D----  and —Ar’—  and  —Ar’—  =  =  Scheme 1.12 P NMR spectroscopic analysis of 1.15a suggested that the polymer was comprised of E 31 and Z-P=C units (i.e. a mixture of cis and trans arylene moieties). The M 11 value of 1.15a was estimated to be 10,500 g mol’ using end group analysis, while a degree of polymerization equal to 21 was considered to be moderate and not unusual for a step-growth reaction. Polymer 1.15a was studied by UV/Vis spectroscopy, which showed a broad absorption  (?.rnax  =  338  1UTL)  slightly  red shifted compared to the absorption band of the model compound for 1.15a. The red shift is small (ca. 28 nm) in comparison to the red shift exhibited by organic counterparts  (Ca.  125 nm  for trans-PPV vs. trans-stilbene), and is possibly due to the mixture of isomers present (E and 2) in 1.15a.  References begin on page 24  Chapter One  14  A very similar derivative, 1.15b, was reported in 2006 (Scheme 1.1 2).52 In contrast to the mixture of E- and Z-P=C units along the backbone of 1.15a, the main chain of 1.15b consisted of solely Z-P=C moieties (i.e. trans arylene moieties). This polymer was isolated as a brittle solid that was insoluble in common organic solvents, thus the molecular weight of 1.15b could not be obtained. The absorption maximum exhibited by 1.15b  (?max  =  338 nm) is red shifted compared  to that of a mono(phosphaalkene) model compound (A3.= 70 nm), giving strong evidence of t conjugation along the main chain. The Protasiewicz group found that poly(p-phenylenephosphaalkene)s could also be prepared by a phospha-Wittig reaction provided that substituents were bulky enough to protect the P=C bond (Scheme 1.1 3)5354 Using the phospha-Wittig methodology, they obtained (E) poly(p-phenylenephosphaalkene)s (1.16a-d). Polymer 1.16a was moderately fluorescent, with fluorescence intensity per P=C unit measured to be about 8% that of E-stilbene. 53 On the other hand, fluorescence intensities of 1.16b-d were approximately equal to that of E-stilbene (see Table 1  The molecular weights (Me) of 1.16a-d ranged between 5,000 g mol’ to 7,300 g  mol’, and each polymer chain consisted of approximately 4 to 6 repeat units. Although these numbers seem low, the total number of aromatic units in the chains ranges from 18 to 26 units, resulting in an extended ir-delocalized system.  Table 1.2 Summary of selected characterization data for 1.16a-d and 1.17. polymer 1.16a  ?max (fliT’)  445  (rim) 545  1.16b  435  1.16c  (%)a  8  M (g mol’) / [DPI 6,500/[6]  PDI N/A  ref. 53  481  80  5,000/[4]  2.3  54  427  486  130  7,200 / [6]  2.2  54  1.16d  416,473(sh)  481  110  7,300/[6]  1.9  54  1.17  435,481  none  0  5,900/[6]  2.1  54  ‘PL  =  2.em  ‘PL  intensity of photoluminescence compared to E-stilbene References begin on page 24  Chapter One  15 3 ,,PMe ,P—Ar—P P’ 3 Me  stir overnight  +  HO—Ar P—Ar—F”  —2 Me P=0 3 0  0  I,  1.16a—d H  —Ar—  H  for a  =  —Ar—  forb—d  —Ar—  b:  =  13 H 6 0C a:  —Ar  —  C:  —Ar—  =  d:  —Ar—  =  -—c--  =  13 H 6 0  Scheme 1.13 The Protasiewicz group also synthesized a diphosphene analogue of PPV. 54 Polymer 1.17 was prepared by thermolysis or photolysis of 3 P=P—Ar—P=PMe eliminating two equivalents Me , of PMe 3 (Scheme 1.14). Remarkably, 1.17 (M  =  5,900 g mo1 ; DP 1  =  6; PDI  =  2.1) is the first  polymer with multiple bonds between two heavier main group elements in the main chain. Although structurally interesting, 1.17 does not exhibit fluorescence, which may be due to quenching by the phosphorus lone pairs.  3 /,PMe P-Ar—P P” 3 Me  heat or hv 3 —2 PMe  FI  p-i//  TArP  —Ar—  =  in  1.17  Scheme 1.14  References begin on page 24  Chapter One  16  A common strategy used by the research groups of Gates and Protasiewicz is the employment of bulky groups to protect the heavy-element multiple bond (i.e. P=C or P=P) and prevent dimerization and/or cyclooligomerization. This strategy is in fact commonly used to stabilize exotic multiply bonded inorganic molecules and monomers for polymerization. 5659 ’ 13  1.1.4 Unconjugated Phosphorus-Carbon Polymers  Recently, a new class of phosphorus-containing polymers was developed by Vanderark et al. via the anionic ring-opening polymerization of a strained phosphirene (Scheme 1.1 5)60 This synthetic route led to polyvinylenephosphine (1.18). High molecular weight 1.18 (M 11 mol’; DP  =  111; PDI  =  =  18,000 g  1.23) was obtained. However, properties and potential applications of  1.18 have not been reported.  Ph  Ph 7800  Me Me  25°C 14 h :35 065 MMe  1 18  Scheme 1.15  In 2007, Chujo and co-workers reported the synthesis of polymers containing chiral phosphorus atoms in the backbone (1.19).61 This was achieved by using chiral biphosphine borane adducts and a,a’-dibromoxylene as building blocks (Scheme 1.16). Polymers 1.19 were studied by circular dichroism (CD) spectroscopy and differential scanning calorimetry (DSC) experiments. The results from CD spectroscopy suggested that the polymers derived from meta xylene and para-xylene exhibited optically active higher-ordered structures, such as helical  References begin on page 24  Chapter One chains. On the other hand, the polymer derived from ortho-xylene displayed an unresponsive CD spectrum, suggesting the absence of a higher-ordered structure. Potential applications for 1.19 include heavy-metal sensors and transition-metal catalysts for asymmetric reactions, however no studies have been reported thus far to demonstrate this possibility. 1) 2 equiv sec-BuLi, (-)-sparteine 3 BH  2) BrJ/Br  3 BH t-Bu  Me  1.19  Scheme 1.16 Poly(methylenephosphine)s are polymers composed of alternating phosphorus and 62 Since the work on these polymers was conducted by the Gates carbon atoms in the main chain. group and builds the foundation for virtually all of the work presented in this thesis, a brief history of poly(methylenephosphine)s demands a section of its own.  1.2 Brief History of PoIy(methylenephosphine)s  In 2003, Chi-Wing Tsang and Mandy Yam of the Gates group discovered the first addition polymerization of a phosphaalkene (1.20) to afford poly(methylenephosphine) (1.21).62 The discovery of 1.21 occurred after the purification of 1.20 by vacuum distillation at 150 °C. Through GPC and NMR spectroscopic analysis, Tsang and Yam showed that the gummy, palebrown residue that remained after distillation contained poly(methylenephosphine) (M g moi’; DP  =  36; PDI  =  =  11,500  1.25). It was slightly surprising that the polymerization occuned so  readily with just heat alone. Subsequently, it was shown that the polymerization could be achieved using a radical initiator such as 1,1 ‘-azobis(cyclohexanecarbonitrile) (VAZO 88), or  References begin on page 24  Chapter One  18  using an anionic initiator such as MeLi or n-BuLi (Scheme 1.17). These methods afforded 1.21 with M values ranging between 5,400 g mol’ and 6,600 g mol’ (DP between 1.10 and  =  17 to 21) and PDI values  1.55.62  10% VAZO 88 Ph  _—00°-..  E  Mes= Phi  Mes’Ph 24h,150°C 5% MeLi or 5% n-BuLi  1 21  Scheme 1.17 The development by Tsang and Yam is an incredible feat for two reasons. Firstly, their development introduced a new method to access inorganic polymers. Although addition polymerization is well-established for olefins, 63 prior to Tsang and Yam’s development addition polymerization had not been generalized to heavy-element multiple bonds. Most synthetic methods to access inorganic polymers involve a ROP process, polycondensation or a coupling strategy, all of which were shown as examples in section 1.1. Secondly, it has been observed that phosphaalkenes share some of the same reactivities as olefins, such as 1,2-addition of polar molecules (i.e. HX), the Diels-Alder reaction, epoxidation, metal complexation and hydrogenation (Scheme 1.1 8).39566465 Tsang and Yam’s development is significant because it expands the analogy between P=C and C=C bonds to polymer science. 55  References begin on page 24  Chapter One  19  1,2 Addition XH I I —P—C—  HX I —P—C—  I  /P=C\  Compxation  or  Diels-Alder  Hydrogenation —P—C—  I  initiator  P—C”  Epoxidation  -  Addition Polymerization  Scheme 1.18  In 2004, the Gates group reported their work on the radical copolymerization of phosphaalkene 1.20 and styrene to afford random copolymers (1.22) (Scheme 1.19).66  H  Ph  P=C  Mes’  +  Ph  H CzC Ph H’  1%VAZO 100 C  1.20 1.22  Scheme 1.19  The new hybrid inorganic-organic macromolecule, 1.22, was tested as a ligand for the Suzuki cross-coupling of bromobenzene and phenylboronic acid to form biphenyl. Results showed that in the presence 3 (dba) (dba 2 [Pd ]  = dibenzylideneacetone), CsF, and copolymer 1.22,  the cross-coupling proceeded and biphenyl was isolated in 90% yield. However, when the crosscoupling reaction was attempted using ] 3 ( 2 [Pd dba) , CsF and homopolymer 1.21, the yield was  References begin on page 24  Chapter One  20  the same as that in the absence of any ligand (yield  =  25%). Thus, the study provided evidence  for the potential of copolymer 1.22 for use in polymer-supported catalysis. In 2006, Kevin Noonan of the Gates group showed that the anionic polymerization of phosphaalkene 1.20 could proceed at ambient temperature and in a living fashion using substoichiometric quantities of n-BuLi. 67 This allowed for control over the molecular weight of the poly(methylenephosphine) with M values up to 29,600 g mof’ (DP low polydispersities (PDI  =  1.0  —  =  94) and polymers of  1.1). Furthermore, the living polymerization of 1.20 permitted  the preparation of block copolymers, such as polystyrene-b-poly(methylenephosphine) (1.23) (Scheme 1.20).67 H CC Ph H’  1)1 mol% n-BuLi, toluene 2) m 1.20, glyme 3)MeOH  FH I I  H I  II [H  I Ph  Ph 1 I PC I I MesPh m 1.23  Scheme 1.20  The chemical functionality of poly(methylenephosphine) 1.21 has also been investigated. Like most three-coordinate trivalent phosphines, the phosphine moieties in 1.21 can be oxidized using 02, H 0 or S 2 8 (Scheme 1.21).62 Similar to phosphine ligands, the phosphine moieties can also be coordinated to transition metals. 68 Additionally, 1.21 can be chemically modified by coordinating the phosphorus atoms to BR 3 moieties to form phosphine-borane adducts along the backbone, or by reacting with MeOTf to afford methylphosphonium ionomers. 69  References begin on page 24  Chapter One  21  I  S Ii  Phi I  -t--% [Mes Ph S4  _L0PhJ.  02orH202  [MS h]  LPhJ  Cs-AucI,,  L-1_ [MS Phj  [MS hJ 1.21  MeO,y  E x=50%  IL Mes Ph In  y=50% Scheme 1.21  Although there have been more studies on poly(methylenephosphine) 1.21 and derivatives thereof, 7074 brevity limits me and I have discussed the founding developments that lead to my research objectives.  1.3 Research Objectives  It is clear that the polymerization of phosphaalkenes is a convenient method to prepare polymers with alternating phosphorus and carbon atoms in the main chain. 67 It has also been ’ 62 shown by previous members in the Gates group that the chemical functionalization of phosphorus centres in poly(methylenephosphine) 1.21 can be easily achieved via oxidation reactions, or complexation to transition metals or Lewis ’ 62 acids. 6 8 When I joined the Gates 9 group, my first goal was to prepare poly(methylenephosphine)s bearing fluorescent side groups, and my second objective was to study the changes in electronic properties upon chemical  References begin on page 24  Chapter One  22  modification. The synthetic work will be discussed in Chapter 2, whereas the chemical functionalization of the new polymers and the concomitant changes in electronic properties will be covered in Chapter 3. The long-term goal behind the work presented in Chapters 2 and 3 is to develop a chemical sensor based on poly(methylenephosphine). This would require further studies, such as experiments examining their selectivity and sensitivity, which have not been conducted to this date. Thus, the results included in Chapters 2 and 3 represent the ground work towards the long-term goal of poly(methlyenephosphine)-based chemosensors. While Chapters 2 and 3 focus on homopolymers, sensory behaviors may also be realized by random copolymers derived from phosphaalkenes since it may not be necessary to have phosphorus at every other atomic site in the backbone. As mentioned in section 1.2, some promising work had been achieved on the radical copolymerization of phosphaalkene 1.20 and styrene, affording poly(methylenephosphine)-co-polystyrene 1.22  66  However, little information  was known about the microstructure of 1.22, such as the monomer distribution along the copolymer chain. To model the microstructure of a random copolymer formed by radical copolymerization, one would need to calculate the associated reactivity ratios. 75 In addition to modeling the microstructure of 1.22, the reactivity ratios of phosphaalkene 1.20 and styrene would also be key synthetic parameters for future designs of tailored copolymers using phosphaalkenes and other monomers, 76 such as copolymers for chemical sensory applications. Thus my third goal was to calculate the reactivity ratios of phosphaalkene 1.20 and styrene. More information about reactivity ratios and the experiments conducted to achieve my third goal will be included in Chapter 4. Lastly, Chapter 5 summarizes the findings of this thesis and proposes some future directions for this work. This thesis has been written following the style of  References begin on page 24  Chapter One  23  a manuscript-based thesis. Each chapter is essentially self-contained with its own introduction, results and discussion, summary, experimental section and references.  1.4 Contributions by Other Researchers to This Work  Some of the work in this thesis was achieved in collaboration with other researchers. For Chapter 2, all of the synthetic work was done by myself with the exception of the synthesis and recrystallization of MesP=C(C S)(Ph) (C 3 H 4 S 3 H 4  =  2-thienyl), which was a collaborative effort  between myself and Fergus Chung. Fergus was an undergraduate researcher under my supervision. All crystallographic data were obtained primarily by Josh Bates with some assistance from Paul Siu using the departmental X-ray diffractometer. The solution and refinement of the molecular structures of MesPC(Naph)(Ph) (Naph = 1 -naphthyl) and S)(Ph) were completed by Josh. The solution and refinement of the molecular 3 H 4 MesPC(C structure of MesP=C(Phen)(Ph) (Phen  9-phenanthrenyl) were performed by Paul. All of the  work presented in Chapters 3 and 4 was completed by myself.  References begin on page 24  Chapter One  24  1.5 References (1)  Stokes, H. N. Am. Chem. 1 1895, 17, 275-290.  (2)  Stokes, H. N. Am. Chem. 1 1896, 18, 629-663.  (3)  Stokes, H. N. Am. Chem. 1 1897, 19, 782-796.  (4)  Stokes, H. N. Am. Chem. 1 1898, 20, 740-760.  (5)  McWilliams, A. R.; Dorn, H.; Manners, I. Top. Curr. Chem. 2002, 220, 141-167.  (6)  Baumgartner, T.; Réau, R. Chem. Rev. 2006, 106, 4681-4727.  (7)  Hissler, M.; Dyer, P. W.; Réau, R. Coord. Chem. Rev. 2003, 244, 1-44.  (8)  Crassous, J.; Réau, R. Dalton Trans. 2008, 6865-6876.  (9)  Noonan, K. J. T.; Gates, D. P. Annu. Rep. Frog. Chem., Sect. A: Inorg. Chem. 2008, 104, 394-4 13.  (10)  Alicock, H. R.; Kugel, R. L. I Am. Chem. Soc. 1965, 87, 42 16-4217.  (11)  Ailcock, H. R. Chemistry and Applications ofPolyphosphazenes; Wiley-Interscience: New York, 2003.  (12)  Mark, J. E.; Ailcock, H. R.; West, R. Inorganic Polymers; 2nd ed.; Oxford University Press, 2005. Chapter 3.  (13)  Manners, I. I Polym. Sd., Part A: Polym Chem. 2002, 40, 179-191.  (14)  Alicock, H. R.; Kugel, R. L.; Valan, K. J. Inorg. Chem. 1966, 5, 1709-1715.  (15)  Neilson, R. H.; Hani, R.; Wisian-Neilson, P.; Meister, J. J.; Roy, A. K.; Hagnauer, G. L. Macromolecules 1987, 20, 910-916.  (16)  Neilson, R. H.; Wisian-Neilson, P. Chem. Rev. 1988, 88, 541-562.  (17)  Honeyman, C. H.; Manners, I.; Morrissey, C. T.; Alicock, H. R. I Am. Chem. Soc. 1995, 117, 7035-7036.  References begin on page 24  Chapter One (18)  25  Dodge, J. A.; Manners, I.; Alicock, H. R.; Renner, G.; Nuyken, 0. J. Am. Chem. Soc. 1990, 112, 1268-1269.  (19)  Liang, M.; Manners, I. J Am. Chem. Soc. 1991, 113, 4044-4045.  (20)  Chunechom, V.; Vidal, T. E.; Adams, H.; Turner, M. L. Angew. Chem.,  mt. Ed.  1998, 37,  1928-1930. (21)  Gates, D. P.; Manners, I. J Chem. Soc., Dalton Trans. 1997, 2525-2532.  (22)  Masoumi, Z.; Stoeva, V.; Yekta, A.; Pang, Z.; Manners, I.; Wmnnik, M. A. Chem. Phys. Lett. 1996, 261, 55 1-557.  (23)  Ni, Y. Z.; Stammer, A.; Liang, M.; Massey, J.; Vancso, G. J.; Manners, I. Macromolecules 1992, 25, 7119-7125.  (24)  Ni, Y. Z.; Park, P.; Liang, M.; Massey, J.; Waddling, C.; Manners, I. Macromolecules 1996, 29, 340 1-3408.  (25)  Pang, Z.; Gu, X. H.; Yekta, A.; Masoumi, Z.; Coll, J. B.; Wmnnik, M. A.; Manners, I. Adv. Mater. 1996, 8, 768-&.  (26)  Ruffolo, R.; Evans, C. E. B.; Liu, X. H.; Ni, Y. Z.; Pang, Z.; Park, P.; McWilliams, A. R.; Gu, X. J.; Lu, X.; Yekta, A.; Wmnnik, M. A.; Manners, I. Anal. Chem. 2000, 72, 18941904.  (27)  Withers, H. P.; Seyferth, D.; Fellmann, J. D.; Garrou, P. E.; Martin, S. Organometallics 1982, 1, 1283-1288.  (28)  Honeyman, C. H.; Peckham, T. J.; Massey, J. A.; Manners, I. Chem. Commun. 1996, 2589-2590.  (29)  Peckham, T. J.; Massey, J. A.; Honeyman, C. H.; Manners, I. Macromolecules 1999, 32, 2830-2837.  References begin on page 24  Chapter One (30)  26  Dorn, H.; Singh, R. A.; Massey, J. A.; Nelson, J. M.; Jaska, C. A.; Lough, A. J.; Manners, I. J Am. Chem. Soc. 2000, 122, 6669-6678.  (31)  Dorn, H.; Rodezno, J. M.; Brunnhofer, B.; Rivard, E.; Massey, J. A.; Manners, I. Macromolecules 2003, 36, 291-297.  (32)  Burg, A. B.; Wagner, R. I. J Am. Chem. Soc. 1953, 75, 3872-3877.  (33)  Burg, A. B. J. Inorg. Nucl. Chem. 1959, 11, 258.  (34)  Wagner, R. I.; Caseiro, F. F. J Inorg. Nucl. Chem. 1959, 11, 259.  (35)  Hobbs, M. G.; Baumgartner, T. Eur. J Inorg. Chem. 2007, 3611-3628.  (36)  Skotheim, T. A.; Elsenbaumer, R. L.; Reynolds, J. R. Handbook ofConducting Polymers; Marcel Dekker: New York, 1998.  (37)  Baumgartner, T.; Bergmans, W.; Kárpáti, T.; Neumann, T.; Nieger, M.; Nyulászi, L. Chem.—Eur. 1 2005, 11, 4687-4699.  (38)  Sebastian, M.; Hissler, M.; Fave, C.; Rault-Berthelot, J.; Odin, C.; Réau, R. Angew. Chem.,  (39)  mt.  Ed. 2006, 45, 6152-6155.  Mathey, F.; Nixon, J. F.; Dillon, K. B. Phosphorus: The Carbon Copy; Wiley-VCH: Weinheim, 1997.  (40)  Mathey, F. Phosphorus-Carbon Heterocyclic Chemistry: The Rise ofa New Domain; Elsevier Science: Oxford, 2001.  (41)  Hissler, M.; Dyer, P. W.; Réau, R. Top. Curr. Chem. 2005, 250, 127-163.  (42)  Bevierre, M. 0.; Mercier, F.; Ricard, L.; Mathey, F. Angew. Chem.,  mt.  Ed. Engi. 1990,  29, 655-657.  (43)  Mao, S. S. H.; Tilley, T. D. Macromolecules 1997, 30, 5566-5569.  References begin on page 24  Chapter One (44)  27  Hay, C.; Fischmeister, C.; Hissler, M.; Toupet, L.; Réau, R. Angew. Chem.,  mt. Ed.  2000,  39, 1812-1815. (45)  Morisaki, Y.; Aiki, Y.; Chujo, Y. Macromolecules 2003, 36, 2594-2597.  (46)  Baumgartner, T.; Wilk, W. Org. Lett. 2006, 8, 503-506.  (47)  Durben, S.; Dienes, Y.; Baumgartner, T. Org. Lett. 2006, 8, 5893-5896.  (48)  Lucht, B. L.; St. Onge, N. 0. Chem. Commun. 2000, 2097-2098.  (49)  Jin, Z.; Lucht, B. L. J Organomet. Chem. 2002, 653, 167-176.  (50)  Jin, Z.; Lucht, B. L. J Am. Chem. Soc. 2005, 127, 5586-5595.  (51)  Wright, V. A.; Gates, D. P. Angew. Chem.,  (52)  Wright, V. A.; Patrick, B. 0.; Schneider, C.; Gates, D. P. 1 Am. Chem. Soc. 2006, 128,  mt. Ed  2002, 4], 2389-2392.  8836-8844. (53)  Smith, R. C.; Chen, X. F.; Protasiewicz, J. D. Inorg. Chem. 2003, 42, 5468-5470.  (54)  Smith, R. C.; Protasiewicz, J. D. I Am. Chem. Soc. 2004, 126, 2268-2269.  (55)  Gates, D. P. Top. Curr. Chem. 2005, 250, 107-126.  (56)  Regitz, M.; Scherer, 0. J. Multiple Bonds and Low Coordination in Phosphorus Chemistry; Thieme: New York, 1990.  (57)  Romanenko, V. D.; Sanchez, M. Coord Chem. Rev. 1997, 158, 275-324.  (58)  Niecke, B.; Gudat, D. Angew. Chem.,  (59)  Rivard, E.; Power, P. P. Inorg. Chem. 2007, 46, 10047-10064.  (60)  Vanderark, L. A.; Clark, T. J.; Rivard, B.; Manners, I.; Slootweg, J. C.; Lammertsma, K.  mt. Ed. Engi.  1991, 30, 2 17-237.  Chem. Commun. 2006, 3332-3333. (61)  Morisaki, Y.; Ouchi, Y.; Tsurui, K.; Chujo, Y. I Polym. Sci., Part A: Polym. Chem. 2007, 45, 866-872.  References begin on page 24  Chapter One  28  (62)  Tsang, C. W.; Yam, M.; Gates, D. P. J Am. Chem. Soc. 2003, 125, 1480-148 1.  (63)  Odian, G. Principles ofPolymerization; 3rd ed.; Wiley-Interscience: New York, 1991.  (64)  Mathey, F. Acc. Chem. Res. 1992, 25, 90-96.  (65)  Mathey, F. Angew. Chem.,  (66)  Tsang, C. W.; Baharloo, B.; Riendi, D.; Yam, M.; Gates, D. P. Angew. Chem.,  mt. Ed.  2003, 42, 1578-1604.  mt. Ed.  2004, 43, 5682-5685.  mt. Ed.  (67)  Noonan, K. J. T.; Gates, D. P. Angew. Chem.,  2006, 45, 727 1-7274.  (68)  Gillon, B. H.; Patrick, B. 0.; Gates, D. P. Chem. Commun. 2008, 2161-2163.  (69)  Noonan, K. J. T.; Feldscher, B.; Bates, J. I.; Kingsley, J. J.; Yam, M.; Gates, D. P. Dalton Trans. 2008, 445 1-4457.  (70)  Gillon, B. H.; Gates, D. P. Chem. Commun. 2004, 1868-1869.  (71)  Noonan, K. J. T.; Patrick, B. 0.; Gates, D. P. Chem. Commun. 2007, 3658-3660.  (72)  Gillon, B. H.; Noonan, K. J. T.; Feldscher, B.; Wissenz, J. M.; Kam, Z. M.; Hsieh, T.; Kingsley, J. J.; Bates, J. I.; Gates, D. P. Can. J. Chem. 2007, 85, 1045-1052.  (73)  Noonan, K. J. T.; Gillon, B. H.; Cappello, V.; Gates, D. P. 1 Am. Chem. Soc. 2008, 130, 12876-12877.  (74)  Noonan, K. J. T.; Gates, D. P. Macromolecules 2008, 41, 196 1-1965.  (75)  Tidwell, P. W.; Mortimer, G. A. I Polym. Sd., Part A: Gen. Pap. 1965, 3, 369-387.  (76)  Aifrey, T.; Bobrer, J. J.; Mark, H. Copolymerization; Interscience Publishers, Inc.: New York, 1952.  References begin on page 24  29  Chapter Two Synthesis and Polymerization Studies of New Phosphaalkenes Bearing Conjugated Substituents*  2.1 Introduction As mentioned in Chapter 1, the first goal of this thesis work is to synthesize poly(methylenephosphine)s bearing conjugated substituents. The motivation behind this work is to develop poly(methylenephosphine)-based chemical sensors. Thus far, the field of phosphoruscontaining macromolecular chemosensors is dominated by phosphole-based polymers. 16 The changes in electronic properties upon chemical modification of poly(methylenephosphine)s with conjugated substituents are of interest and expected to give a sensor-like behavior. Chemical modification of these new polymers should be feasible given the demonstrated functionalization of phosphorus centres in [MesP—CPh 1 by oxidation and coordination to electrophiles (e.g. ] 2 transition metals and boranes). 79 The purpose of the conjugated groups is to facilitate the detection of changes in electronic responses upon functionalization at phosphorus. Although the long-term goal of this project is to develop a polymeric chemosensor, this thesis discusses only the synthesis and functionalization of these polymers and the concomitant changes in their electronic properties. This chapter relates to the synthetic work involved in preparing the new poly(methylenephosphine)s for the project described above. To access these polymers, it is necessary to first synthesize phosphaalkene monomers 2.1  *A  —  2.3 (Scheme 2.1).  version of this chapter will be submitted for publication. Chun, C. P., Chung, F. and Gates, D. P. Synthesis and Polymerization of New Phosphaalkenes Bearing Conjugated Sub stituents.  Chapter Two  30  R pd Mes  2.1 R =  FR  polymerization  Ph  LMes Ph  EIEIJ  Mes  =  1 -naphthyl (Naph)  mesityl 2.2 R  =  2-thienyl (C S) 3 H 4  2.3 R =  9-phenanthrenyl (Phen)  Scheme 2.1 A convenient method that has been commonly used to prepare P-mesityl phosphaalkenes 8 a phosphorus analogue of the Peterson olefination is the phospha-Peterson reaction,’°’ 9 This synthetic route involves the reaction between a silyl phosphide and a ketone or reaction.’ an aldehyde to yield a phosphaalkene provided that sufficiently bulky substituents are employed to protect the P=C bond (Scheme 2.2). SiMe Mes-F 3 SiMe /  MeLi heat  /  Li  Mes-P  3 SiMe  RC(O)R’ CI 3 SiMe LiCI 0 2 ) 3 (SiMe -  -  R PC Mes’  R’  Scheme 2.2 Similar to the phospha-Peterson reaction is the base-catalyzed phospha-Peterson 2 In this analogous reaction, a bis(trimethylsilyl)phosphine is mixed with one ’ 20 reaction. equivalent of a ketone and a catalytic amount (0.5 mol%) of anhydrous base (i.e. KOH or NaOH) to afford P-mesityl phosphaalkenes with a variety of aromatic C-substituents (Scheme 2.3).22  References begin on page 59  Chapter Two  31  )f 3 Presumably, a catalytic amount of base facilitates the in situ generation of the [MesP(SiMe anion. The byproduct, hexamethyldisiloxane, is a volatile nonpolar liquid that can be easily removed in vacuo. In short, the base-catalyzed phospha-Peterson reaction is attractive because it is a simple one-step method to access P-mesityl phosphaalkenes bearing aromatic C-substituents. Both the standard phospha-Peterson reaction and the base-catalyzed phospha-Peterson approach were employed to prepare the target phosphaalkenes 2.1 3 SiMe Mes-P 3 “SiMe  R +  o=c  —  KOH or NaOH (cat.) .  R’  2.3.  -  0 2 ) 3 (SIMe  ,R PC Me R’  Scheme 2.3 As discussed in Chapter 1, the polymerization of phosphaalkenes can be achieved using a radical initiator such as 1,1 ‘-azobis(cyclohexanecarbonitrile) (VAZO 88) or using an anionic 23 The anionic method was chosen for the work presented in this ’ 7 initiator such as n-BuLi. chapter as it is less laborious. Herein, the syntheses and structures of phosphaalkenes 2.1  —  2.3  are reported, followed by a discussion on the polymerization studies of these phosphaalkene monomers.  2.2 Results and Discussion 2.2.1 Synthesis of Phosphaalkene 2.1  Given the simplicity of the base-catalyzed phospha-Peterson reaction, 2 this method ’ 20 was employed to prepare MesPC(Naph)(Ph) (2.1) (Naph = 1-naphthyl). The precursors to 2.1, 24 were prepared following modified literature ° and 1 -benzoylnaphthalene, 2 ) 3 MesP(SiMe 2 was mixed with one equivalent of 1) 3 procedures. To prepare compound 2.1, MesP(SiMe benzoylnaphthalene in the presence of a catalytic quantity of KOH (Scheme 2.4). The reaction mixture turned yellow within five minutes of being stirred. References begin on page 59  Chapter Two  32 Si Me 3 Mes-Fç 3 SiMe  Naph +  0=0  KOH (cat.) 55°C,THF 0 2 ) 3 (SiMe  Ph  ,Naph P =G\ Met Ph  -  2.1  Scheme 2.4  P NMR The reaction progress was rather slow and was monitored over 2 weeks by 31 spectroscopy (Figure 2.1). The spectra revealed that the signal assigned to MesP(SiMe 2 ) 3  (3p  =  —16 1; Figure 2.la) was gradually depleted and replaced by signals assigned to phosphaalkene 2.1 (&lp  =  251 and 239, E/Z mixture; Figure 2.lb). There were two unidentifiable impurities in the  reaction mixture, labeled A and B on the 31 P NMR spectrum in Figure 2. lb. The minor impurity labeled C is MesPH 25 and the signal labeled D is residual MesP(SiMe , 2 . 2 ) 3  -161 ppm  (a) 251 ppm  239 ppm  (b)  —  50 ppm  200  10  100  50  0  -50  -100  -150  Figure 2.1. 31 P NMR spectra (THF, 122 MHz) of(a) MesP(SiMe 2 and (b) 2.1 (E/Zmixture) ) 3 formed after 2 weeks. Minor impurities are labeled A C. The identities of A and B are unknown, and C is MesPH . The signal labeled D is residual MesP(SiMe 2 . 2 ) 3 —  The product, C-naphthyl-.substituted phosphaalkene 2.1, was purified by vacuum distillation followed by multiple recrystallizations from hexanes, and isolated as yellow crystals  References begin on page 59  Chapter Two  33  in 25% yield. X-ray diffraction analysis of the yellow crystals showed 2.1 in the E configuration.* The 31 P NMR spectrum of the yellow crystals showed one signal at 239 ppm, hence this chemical shift was assigned to E-2.1. However, over time (i.e. 24 h), 31 P NMR spectroscopic analysis of the same sample showed two signals at 251 ppm and 239 ppm, suggesting the occurrence of E/Z isomerization in solution. The isomerization of 2 2 before.” 2 628 2 This process can occur in as short as 30 mm phosphaalkenes has been studied ’ 22 when irradiated with UV light, 24 h when exposed to sunlight, and 48 h in the absence of light. 3 (Figure 2.2) exhibits the characteristic upfield The ‘H NMR spectrum of E-2.1 in CDC1 signal assigned to the ortho-CH 3 that has double the intensity of the signal assigned to the para  9-CH3 3 o-CH C><P01) 3 H CH H 30  E-2.1 C 2 H P 6 3  p-C H 3 14 Ar-H  Figure 2.2. ‘H NMR spectrum (CDCI , 400 MHz) of E-2.1. Residual CHC1 3 3 (*) Silicone grease  (t).  *  The molecular structure and X-ray crystallographic analysis of E-2. 1 will be presented in section 2.2.4. References begin on page 59  Chapter Two  34  3 of the mesityl ring. Integration of the ‘H NMR spectrum accounts for 9 methyl hydrogens CH (‘H  =  2.4 and 2.3 ppm) and 14 aromatic hydrogens  (1H  =  7.9  —  6.8 ppm). Compound 2.1 was  also characterized by ‘ C { ‘H }NMR spectroscopy (see Experimental). 3  2.2.2 Synthesis of Phosphaalkene 2.2  Similar to the preparation of 2.1, the synthesis of MesP=C(C 5)(Ph) (2.2) (C 3 H 4 S 3 H 4  =  2-  thienyl) was achieved via the base-catalyzed phospha-Peterson route (Scheme 2.5). The ketone precursor to 2.2, 2-benzoylthiophene, was prepared via a Friedel-Crafts acylation following an 29 The reaction between 2-benzoylthiophene and MesP(SiMe adapted literature procedure. 2 ) 3 =  (31p  —161) in THF with a catalytic amount of KOH afforded 2.2 as a mixture of E- and Z- isomers  (3ip  227 and 220) over 5 days (Figure 2.3).  3 SiMe Mes—R 3 SiMe  +  KOH (cat.)  O=C Ph -  THE 0 2 ) 3 (SiMe  P=C\ Met Ph 2.2  Scheme 2.5  The C-thienyl-substituted phosphaalkene, 2.2, was purified by vacuum distillation, resulting in a yellow viscous oil (yield = 60%). Recrystallization of 2.2 in hexanes afforded bright yellow crystalline needles. The 3 ’P NMR spectrum of the needles showed the same two signals  (&ip  227, 58%;  ip  =  220, 42%) as observed during the course of the reaction. The ‘H  NMR spectrum of 2.2 dissolved in C D is displayed in Figure 2.4. There are four signals in the 6 upfield region due to the presence of two isomers. Based on integration, the more intense signal of the pair of chemicals shifts assigned to the ortho-CH 3 and the more intense signal of chemical shifts assigned to the para-CH 3 were attributed to the same isomer. The remaining two signals  References begin on page 59  Chapter Two  35 -161 ppm  (a) 227 ppm  220 ppm  (b) ppm  200  150  100  50  0  -50  -ibo  -io  2 and (b) 2.2 (E/Z mixture) ) 3 Figure 2.3. 31 P NMR spectra (THF, 122 MHz) of(a) MesP(SiMe (after 5 d).  P were assigned to the other isomer. The ratio of isomers (5 8:42) based on integration of the 31 NMR spectrum agrees with that based on integration of the methyl protons in the ‘H NMR spectrum. Integration of the benzylic region relative to the aromatic region gives 9 methyl C{’H} NMR 3 hydrogens and 10 aromatic hydrogens. Compound 2.2 was also characterized by ‘ spectroscopy (see Experimental).  3 9-CH  3 H Ph 10 Ar-H  3 CH  ---3 o-CH  N  2.2 QH 2 C PS 19  Figure 2.4. ‘H NMR spectrum (C , 400 MHz) of 2.2 (E/Z mixture). Residual C D 6 H (*)• 5 D 6 References begin on page 59  Chapter Two  36  2.2.3 Synthesis of Phosphaalkene 2.3 The synthesis of MesPC(Phen)(Ph) (2.3) (Phen  =  9-phenanthrenyl) via the base-  catalyzed phospha-Peterson reaction was attempted. The ketone precursor, 9benzoylphenanthrene, was prepared from benzoyl chloride and 9-bromophenanthrene according to modified literature procedures following a copper(I) coupling and using LiC1 as an 30 Unfortunately, the preparation of 2.3 via the base-catalyzed route required ’ 24 additive. extremely long reaction times (over 1 month), even at elevated temperatures (i.e. 50 °C), and afforded a mixture of products. For these reasons, the preparation of 2.3 was attempted via the standard phospha-Peterson reaction described in the introduction of this chapter. By this method, one equivalent of a silyl phosphide (prepared in situ,  31p  =  —187, Figure 2.5 a) was treated with 9-benzoylphenanthrene in  THF at —78 °C (Scheme 2.6).  MesP’ 3 )IIvIe  MeLi THF,65°C overni ht  1) PhenC(O)Ph, -78 2) SIMe CI, -78 00 3  MesP”  c  10 mm  ,Phen  I  IC”  3 ,Iivie  Mes  -  -  0 2 ) 3 (S1Me  ‘  Ph  2.3  Scheme 2.6 An aliquot was removed from the dark green reaction mixture and analyzed by 31 P NMR P NMR spectroscopic analysis suggested a spectroscopy. As shown in Figure 2.5b, the 31 quantitative conversion of Li[MesP(SiMe )] to the desired product 2.3 3  (31p  =  252 and 238; E/Z  mixture). Upon quenching of the presumed byproduct LiOSiMe 3 with Me 3 SiCl, the reaction mixture instantaneously turned red. A red oil remained after the removal of solvent in vacuo, and was admixed with hexanes. Insoluble salts were removed by filtering the mixture through Celite. Phosphaalkene 2.3 was isolated as yellow crystals from recrystallization in hexanes.  References begin on page 59  Chapter Two  37 -187 ppm  (a) 252 ppm 238 ppm  (b)_ I  250 ppm  I  I  I  I  I  I  200  150  100  50  0  -50  I  -100  -150  Figure 2.5. 31 P NMR spectra (THF, 122 MHz) of(a) Li[MesP(SiMe )] (generated in situ) and 3 (b) 2.3 (E/Z mixture) formed 10 minutes after the addition of ketone to silyl phosphide.  The 31 P NMR spectrum of the yellow crystals dissolved in C D showed one signal at 6 252 ppm. The X-ray diffraction analysis of the yellow crystals showed 2.3 in the Z  stereochemistry, hence the 31 P NMR signal at 252 ppm was assigned to Z2.3.t The ‘H NMR spectrum of 2.3 dissolved in C , shown in Figure 2.6, exhibits broad D 6 resonances in the aromatic region  (ölH  6.5 and 6.0) and the allylic region  (ólH  =  2.5 and 2.0).  The multiple broad signals are likely to be due to restricted rotation of the mesityl ring. As indicated on the ‘H NMR spectrum in Figure 2.6, the broad resonances at 6.5 ppm and 6.0 ppm are assigned to Mes-H, while the broad resonances at 2.5 ppm and 2.0 ppm are assigned to the . Integration of the spectrum agrees with this assignment and accounts for the 3 ortho-CH remaining hydrogens in the molecule. A variable-temperature NMR experiment showed that the two pairs of broad signals  (1H  =  6.5 and 6.0;  1H  =  2.5 and 2.0) eventually coalesced upon  heating at 45 °C, giving one broad signal at 6.3 ppm and one broad signal at 2.3 ppm.  The molecular structure and X-ray crystallographic analysis of Z-2.3 will be presented in section 2.2.4. References begin on page 59  ___  Chapter Two  38 *  3 3p-CH  Z-2.3 35 C 2 H P 0  14 Ar-H  I  III  ii lilA  2 Mes-H I  3 6 opH t  I  LJJLJ ppm8765  43210  Figure 2.6. ‘H NMR spectrum (C , 400 MHz) of 2.3. The multiple broad signals are likely to D 6 H (*)• Silicon grease (t). 5 D 6 be due to restricted rotation of the mesityl ring. Residual C 2.2.4 X-ray Crystallographic Analysis of Phosphaalkenes 2.1 —2.3  In all three cases, crystals suitable for X-ray diffraction were successfully grown from concentrated hexanes solutions at room temperature. Under these conditions, 2.1 crystallizes as the E isomer, 2.2 crystallizes as a mixture of E/Z isomers, and 2.3 surprisingly crystallizes as the Z-isomer, as opposed to the expected E configuration based on sterics. This surprising result may be due to a conjugation or crystal packing effect, both discussed towards the end of this section. The molecular structures of E-2.1, 2.2, and Z-2.3 are displayed in Figures 2.7, 2.8, and 2.9, respectively. The solution and refinement of these molecular structures were completed by Josh Bates and Paul Siu.  References begin on page 59  Chapter Two  39  C17 P1  ClO cli  Cl  Figure 2.7. Molecular structure E-MesPC(Naph)(Ph) (E-2.1). Ellipsoids are drawn at 50% probability level, hydrogen atoms are omitted for clarity. Selected bond lengths (A) and angles (°): P(1)—C(1) 1.8307(16), P(1)—C(10) 1.6876(14), C(10)—C(l 1)1.4821(18), C(10)—C(17) 1.4933(19), C(1)—P(1)—C(10) 108.36(7), P(1)—C(10)—C(1 1)129.23(10), P(l)—C(10)—C(17) 114.15(10), C(17)—C(10)—C(11) 116.56(12).  References begin on page 59  Chapter Two  40  Sla  Cl  E-2.2  Z-2.2  Figure 2.8. Molecular structure of MesP=C(C S)(Ph) (2.2). Ellipsoids are drawn at 50% 3 H 4 probability, hydrogens are omitted for clarity, and overlapping atoms are omitted in respective isomers. Selected bond lengths (A) and angles (°): P(1)—C(1) 1.827(3), P(1)—C(l0) 1.687(3), C(10)—C(l la) 1.484(10), C(l0)—C(15a) 1.458(8), C(l0)—C(1 ib) 1.49(2), C(10)—C(15b) 1.44(2), C(l)—P(l)—C(10) 107.39(12), P(l)—C(l0)—C(l la) 116.2(4), P(l)—C(l0)—C(15a) 127.5(3), C(l la)—C(10)—C(15a) 116.3(5), P(1)—.C(10)—C(15b) 115.2(10), P(1)—C(10)—C(1 ib) 129.9(9), C(1 lb)—C(10)—C(15b) 114.8(13).  A summary of cell constants and refinement parameters is displayed in Table 2.1. Important metrical parameters of phosphaalkenes 2.1 —2.3 are presented in Table 2.2, and for comparison, metrical parameters of MesP=CPh , reported by the Bickeihaupt and Becker groups 2 31 independentl 3 ’ 2 y, are also included. Before proceeding to a discussion of the metrical parameters of the new phosphaalkenes, the evident disorder in the refined structure of 2.2 (Figure 2.8) demands an explanation. The elongated and enlarged ellipsoids of a few atoms are attributed to disorder in the C-substituents. Disorder in the aromatic C-substituents of asymmetric phosphaalkenes has been observed in previous work in our lab. The solution and refinement process of the molecular structures of 2.2  References begin on page 59  Chapter Two  41  P1  ClO  11  Figure 2.9. Molecular structure Z-MesP=C(Phen)(Ph) (Z-2.3). Ellipsoids are drawn at 50% probability level, hydrogen atoms are omitted for clarity. Selected bond lengths (A) and angles (°): P(l)—C(l) 1.8273(18), P(1)—C(10) 1.6926(16), C(10)—C(1 1)1.483(2), C(10)—C(17) 1.483(2), C(1)—P(1)—C(lO) 105.76(8), P(1)—C(10)—C(1 1)117.74(12), P(1)—C(10)—C(l7) 123.89(12), C(17)—C(10)—C(11) 118.14(13).  proved to be challenging due to the overlapping electron densities from both isomers. Considering the challenge and difficulties in modeling the molecular structure of 2.2, the hard work in accomplishing this task is credited to Josh Bates despite the disorder. To overcome this challenge during the solution and refinement process, the metrical parameters of the phenyl and thienyl rings of the dominant isomer (i.e. E-2.2) were used to give relative positions of atoms in the rings of the other isomer. The reason why there is an elongated ellipsoid for C(20a) is due to the influence of the electron density from the sulfur atom in the other isomer (i.e. S( 1 b)). Other enlarged or elongated ellipsoids observed in the molecular structure of 2.2 can be similarly explained by the influence of overlapping electron densities. Due to this disorder, only the  References begin on page 59  Chapter Two  42  metrical parameters that do not involve the phenyl and thienyl rings in 2.2 can be discussed with confidence, whereas the metrical parameters involving these rings are reported for completion and must be taken with caution.  Table 2.1. X-ray crystallographic data for E-2.1, 2.2 (E/Z mixture), and Z-2.3 compound Formula  E-2.1 P C 2 H 6 3  2.2 (E/Z mixture) 29 C 1 H PS 0  Z-2.3 35 C 2 H P 0  FW  366.41  322.38  416.47  monoclinic  monoclinic  monoclinic  space group  P 2/n  /c 1 P2  C 2/c  color  yellow  yellow  yellow  a(A)  12.0535(4)  11.4651(14)  19.514(2)  b(A)  9.2978(3)  6.1645(9)  13.3010(14)  c(A)  18.7237(6)  24.1496(28)  20.028(2)  a (°)  90.0  90.0  90.0  /3(0)  99.3480(10)  90.952(6)  119.5190(10)  y(°)  90.0  90.0  90.0  4  4  8  173  173  173  1 [I>2a(I)] R  0.0412  0.0620  0.0433  wR2(alldata)  0.1043  0.1948  0.1372  1.009  1.016  1.054  crystal system  Z Temp (K)  GOF  References begin on page 59  Chapter Two  43  Table 2.2. Important metrical parameters for E-2.1, E-2.2, Z-2.2, Z-2.3, and MesP=CPh . 2  compound  E-2.1  E-2.2  Z-2.2  Z-2.3  2 MesP=CPh  2 MesPCPh  PC  1.6876(14)  1.687(3)a  1.687(3)a  1.6926(16)  1.692(3)  1.693(2)  PCMes  1.8307(16)  I.827(3)a  1.827(3)a  1.8273(18)  1.828(3)  1.830(2)  CCtrans  1.4933(19)  1.484(10)  1.44(2)  1.483(2)  1.491(5)  1.491(5)  C—Cm,  1.4821(18)  1.458(8)  1.49(2)  1.483(2)  1.487(4)  1.489(2)  LCMesPC  108.36(7)  107.39(12)a  107.39(12)a  105.76(8)  107.5(2)  107.6(2)  LP=C—C,  114.15(10)  116.2(4)  115.2(10)  117.74(12)  116.2(2)  118.0(2)  LPCCcic  129.23(10)  127.5(3)  129.9(9)  123.89(12)  127.2(2)  124.8(2)  LCtrancCCciv  116.56(12)  116.3(5)  114.8(13)  118.14(13)  116.6(2)  1 17.1(3)  59.3  34  43  20.6  36.6  21.4  41.8  44  51  63.2  42.9  59.2  64.8  737a  737a  85.3  71  72.2  This work  This work  This work  This work  31  32  Bond lengths (A)  Bond Angles (°)  Angles between planes Ar,rans  Mes Reference  (o)b  a  The bond lengths reported for the P=C bond of E-2.2 and Z-2.2 are actually measured between the same atoms (i.e. P(1) and C(10)), and thus explains why the values are exactly the same. Analogous arguments explains the cases for the PCMeS bond, the LCMesP=C angle, and the angle between best planes of the Mes ring and the PC bond. b The angle between the mean plane of the atoms that comprise the aromatic substituent and the mean plane defined by CipsoPC(Cgrans)(Ccjs) atoms.  Now that the disorder in 2.2 has been discussed, the discussion on the metrical parameters of 2.1  —  2.3 shall begin here, starting with the P=C bond lengths. The P( 1 )—C( 10)  References begin on page 59  Chapter Two  44  bond lengths in E-2.1, 2.2, and Z-2.3 (Ca. 1.69  A) are indicative of phosphorus-carbon double  bonds. They are clearly shorter than the typical P—C single bond (1.83  A 1.90 A) 33 and are in —  the range of P=C bond lengths of related C-substituted phosphaalkenes (1.61  A—  1.71  34 The A).  P=C bond lengths exhibited by E-2.1, 2.2, and Z-2.3 are in the long end of this range, which is characteristic of P-mesityl phosphaalkenes with aromatic C-substituents, such as 22 . 2 MesP=CPh ’ 3 1 The P—CMeS bond lengths exhibited by 2.1 —2.3 (Ca. 1.83 with the average PCAr bond length (1.836 and Z-2.3 (ca. 1.48  A) are consistent  33 The CCgrans and C—C A). 1 bond lengths in E-2.1  A 1.49 A) are shorter than the average C—C single bond length (1.54 A), 33 —  but agree with the typical CSp CAr bond lengths (1.483 2  33 It is noticeable in Table 2.2 that the A).  C—C bond length of E-2.2 appear to be comparatively CCirans bond length of Z-2.2 and the 1 short (ca. 1.44  A  —  1.45  A). These are the bonds between C(10) and the ipso carbon of the  thienyl substituent. The molecular structure of 2-benzoylthiophene shows a similar shortening effect of the analogous bond. 35 The bond length between the carbonyl carbon and the ipso carbon of the thienyl substituent measures 1.459  A, and the bond length between the carbonyl carbon  and the ipso carbon of the phenyl group is 1.482  A.  The geometry of the carbon atom in the Pr=C bond is essentially planar (sum of angles 360°) in 2.1  —  2.3. All of the LPC—C 1 angles in E-2.1, E-2.2, Z-2.2, and Z-2.3 are greater than  the LPCCtrans angles  (  1230  —  129° vs. —1 140  —  117°) implying that the Ar rings are bent  further away from the P=C bond than the Arirans rings. This is most likely an impact of steric repulsion between the Ar 1 and the mesityl rings. However, it is interesting that the angles LCMesPC and LP=C—C 1 in Z-2.3 are smaller than the analogous angles in the other  phosphaalkenes reported in Table 2.2, indicating that the mesityl and the phenanthrenyl rings surprisingly bend closer towards each other. This may be an effect of the crystal packing of Z  References begin on page 59  Chapter Two  45  2.3. As shown in Figure 2.10, the crystal packing of Z-2.3 exhibits Jt—3t interactions (3.4  A)  between the carbons along the edges of the phenanthrenyl moieties of adjacent phosphaalkene molecules. These interactions are very similar to the  Jt—3t  interactions in the crystal packing of  phenanthrene molecules reported by Professor Trotter of this department in 1963.36 The phenanthrene rings in Trotter’s report were oriented in the same fashion, respective to each other, as shown in Figure 2.10. And remarkably, the  t—t  interactions existed between the same carbons  of the phenanthrenyl ring.  Figure 2.10. The crystal packing of Z-2.3. Green dotted lines represent the  3t-3t  interactions (3.4  A). The angle between the best planes of the P=C bond and the aromatic P- and C substituents in the phosphaalkenes can indicate the degree of n-conjugation present in the  References begin on page 59  Chapter Two  46  molecule. A larger angle would suggest minimal it-conjugation, whereas a smaller angle would suggest a larger degree of it-conjugation between the P=C bond and the respective aromatic moiety. In the molecular structure of Z-2.3, the angle between the best planes of the mesityl ring and the P=C bond is 85.3°, indicating little or no conjugation between these moieties. On the other hand, the angle between the P=C bond and the best plane of the phenyl ring is 20.6°, suggesting that the P=C bond is more likely to be conjugated with the phenyl ring than the mesityl ring. In E-2.1, the angle between planes of the naphthyl ring and the P=C bond is 59.3°, and the angle between planes of the phenyl ring and the PC bond is 41.8°. The data suggest that the existence of it-conjugation among the naphthyl ring, phenyl ring, and the P=C bond in E-2.1 is unlikely.  2.2.5 Polymerization Studies of Phosphaaikene Monomers 2.1  We aimed to polymerize phosphaalkenes 2.1  —  —  2.3  2.3 by anionic polymerization. The  polymerization of 2.1 and 2.3 was successfully achieved by treating a THF solution of the monomer with n-BuLi (2 mol%) at room temperature (Scheme 2.7). The polymerization of 2.2 was attempted, but no evidence of polymer formation was observed. This observation will be discussed later in this section. 2moI%n-BuLi  p=c Ph  Met 2.1 R 2.3 R  = =  THF, RT  Naph Phen  F  1  n-Bu+-P—C-+H [Mes Phj 2.4 R 2.5 R  = =  Naph Phen  Scheme 2.7  The addition of the anionic initiator n-BuLi (2 mol%) to a yellow solution of 2.1 resulted in an instantaneous color change to dark green. The progress of the anionic polymerization was  References begin on page 59  Chapter Two  47  monitored by 31 P NMR spectroscopy. As the polymerization advanced, the 31 P NMR signals of 2.1  31p = 6 (  251 and 239, E/Z mixtures) gradually decreased in relative intensity and were  replaced by a broad signal  31p = 6 (  —9 ppm). This broad signal was assigned to [MesP—  C(Naph)(Ph)] 2.4 and is similar to the broad ‘ ] 2 P NMR chemical shift of [MesP—CPh 3  31p = 8 (  —10 ppm). 7 After 14 days, the color of the reaction mixture was brown-green. Analysis of the 31 P NMR spectrum of an aliquot removed from the reaction mixture suggested very little advancement in the polymerization. Integration of the 31 P NMR spectrum showed 73% conversion of monomer 2.1 to polymer 2.4 (Figure 2.11 a). Since there was little advancement in the polymerization thereafter, 2.4 was isolated by addition of methanol to quench any remaining lithiates, followed by repeated precipitations using hexanes (yield  =  40%). A 31 P NMR spectrum  of the isolated polymer is shown in Figure 2.llb.  251 ppm  239 ppm  -9ppm (br)  (a)  (b)  flfla ppm  I  I  200  100  •  I  I  0  -100  I  I  -200  Figure 2.11. 31 P NMR spectra (THF, 122 MHz) of (a) an aliquot removed from polymerization of phosphaalkene 2.1 to form polymer 2.4 (after 14 d); (b) isolated polymer 2.4. References begin on page 59  Chapter Two  48  Analysis of 2.4 by triple detection gel permeation chromatography (GPC) showed that the polymer had an absolute number average molecular weight (Me) of 40,100 g mol’ and a polydispersity index (PDI) of 1.42. GPC traces of 2.4 from the laser light scattering signal and the refractive index signal are presented in Figure 2.12. The anticipated molecular weight of the polymer based on the monomer feed and initiator feed is 18,300 g mo1 . Although the goal of 1 this project was to simply prepare poly(methylenephosphine) bearing the specified substituents, an explanation is required for the difference between the anticipated molecular weight and M measured by GPC.  1.2  0.8 U  (a,  0.4  0  -0.4 0  10  20  30  40  time (mm)  Figure 2.12. GPC trace of 2.4; M 40,100 g moP , PDI 1 scattering signal, blue trace refractive index signal.)  =  1.42. (Red trace  —  laser light  —  The higher than anticipated M value is mostly likely due to a fair amount of quenching of reactive chain ends during the polymerization by minor impurities, and there is evidence of impurities in the ‘H NMR spectrum of 2.1 (Figure 2.2). The quenching would result in shorter chains of the quenched species and higher molecular weights for the remaining polymer chains. Most of the shorter chains were probably removed from the isolated product during the work-up,  References begin on page 59  Chapter Two  49  explaining why the measured M of the isolated polymer was so much higher than the anticipated molecular weight. The polymerization of 2.1 was repeated a number of times and gave similar results. Similar to the polymerization of 2.1, the same color change from yellow to dark green was observed when a solution of C-phenantbrenyl-substituted phosphaalkene 2.3 was treated with n-BuLi (2 mol%). As the polymerization moved forward, the conversion of monomer 2.3 31p 5 (  =  252 and 238, E/Zmixtures) to polymer 2.5  31p 6 (  —10, broad) was monitored by 31 P  NMR spectroscopy (Figure 2.1 3a). After 8 days, the conversion of monomer to polymer was 60%, and the reaction mixture was brown-green in color. At this point, there was very little progress in the polymerization, and thus methanol was added to the reaction mixture to quench any remaining lithiates. Polymer 2.5 was isolated in the same manner as described for the P NMR spectrum of 2.5 is shown in Figure 2.13b. isolation of 2.4 with a 32% yield. The 31  252 ppm 238 ppm  -10 ppm (br)  (a)  —  ppm  —  200  .—  .  100  j-.a—’’””.ernv. -.——tr-_jJln,kIrsw-  0  -100  .J—JAaPt-_--V- -: L.a  -200  Figure 2.13. 31 P NMR spectra (TFIF, 122 MHz) of(a) an aliquot removed from the reaction mixture of the polymerization of phosphaalkene 2.3 to form polymer 2.5 (after 8 d); (b) isolated polymer 2.5.  References begin on page 59  Chapter Two  50  According to the data analysis of 2.5 by triple detection GPC, the polymer had an M of 27,100 g mo1 1 and a PDI of 1.39. The GPC traces of 2.5 are displayed in Figure 2.14. The analyzed M is greater than the anticipated molecular weight (20,900 g mol’). This difference alludes to the event of quenching by impurities in solution during the polymerization progress, which was previously discussed. It is puzzling and unclear why the elemental analysis of polymers 2.4 and 2.5 showed a lower carbon content than expected; this may be a sign of inorganic impurities or fragmentation of—C(R)(Ph) chain ends (R = Naph or Phen).  1.2  0.8  a  -0.4 0  10  20  40  30  time (mm)  Figure 2.14. GPC trace of 2.5; M = 27,100 g moF , PDI 1 scattering signal, blue trace refractive index signal.)  =  1.39. (Red trace  —  laser light  —  As mentioned earlier in this section, the polymerization of C-thienyl-substituted phosphaalkene 2.2 was attempted, but there was no polymer formation. The polymerization was first attempted using 2 mol% n-BuLi at room temperature. Upon the addition of the anionic initiator to a THF solution of 2.2, a change of coloration from yellow to dark red was observed. The polymerization was monitored over 7 days by removing aliquots from the reaction mixture, then analyzing the aliquots by 31 P NMR spectroscopy. No change was observed in the 31 P NMR  References begin on page 59  Chapter Two  51  spectra of the aliquots. More specifically, only signals assigned to phosphaalkene 2.2  (31p  =  227  and 220, E/Z mixture) were observed and there was no broad signal that would be characteristic of phosphine moieties in poly(methylenephosphine). The polymerization of 2.2 was further attempted with a higher initiator loading (up to 5 mol%) and at elevated temperatures (45 °C). Again, reactions were monitored by 31 P NMR spectroscopy and there was no evidence of polymer growth. There are several possible reasons to account for the absence of polymerization activity: 1. The initiated species, 4 Li[Mes(n-Bu)P—C(C S 3 H )(Ph)], did not form. However, reactivity was observed in an NMR-scale experiment in which 2.2 was treated with one equivalent of MeLi at —78 °C in THF. 31 P NMR analysis of the red reaction mixture showed two signals at —32 ppm and —44 ppm (Figure 2.15a). It was speculated that both signals are representative of the lithiated species, whereby one was assigned to Li[Mes(Me)P— S)(Ph)], and the other signal was assigned to 4 3 H 4 C(C Mes(Me)PCH(Ph)(C S 2 H Li) (lithium at the ct-position of the thienyl ring). As a reference, Li[Mes(Me)P—CPh ] has a 2 P chemical shift of—42 ppm in THF. 31 37 When the reaction mixture was quenched with MeOH, there was one singlet at —18 ppm in the 31 P NMR spectrum of the quenched reaction mixture, suggesting the formation of Mes(Me)P—CH(C S)(Ph) (Figure 2.15b). 3 H 4 For comparison, the phosphine, Mes(Me)P—CHPh , has a 31 2 P chemical shift of—24 37 The species at —18 ppm was not isolated as this was a test reaction at NMR-scale. ppm. 2. Assuming that the formation of the initiated species was successful, then it is possible that the initiated species did not attack any monomers in solution to initiate the propagation step for forming a growing chain. The lack of propagation could be due to the stability of the carbanion, thereby not being reactive enough to attack a monomer. In  References begin on page 59  Chapter Two  52 -44 ppm  -32  (a) -18 ppm  (b)  ppm  120 100  80  60  40  20  0  -20 -40  -60  -80 -100 -120 -140  Figure 2.15. 31 P NMR spectra (THF, 122 MHz) of aliquots removed from the reaction between 2.3 and one equivalent of MeLi. (a) 31 P NMR spectrum of an aliquot removed from reaction mixture after lithiation; (b) 31 P NMR spectrum of reaction mixture after quenching with MeOH.  order for propagation to occur, the carbanion must be relatively unstable thereby giving a driving force for the addition to a monomer. 3. It has been shown the anionic polymerization of phosphaalkenes requires conditions of high purity. 23 It is possible that the samples of 2.2 used in the polymerization experiments were not pure enough as there is evidence of minor impurities in the ‘H NMR spectrum of 2.2 (Figure 2.4). Initiated species could be quenched by impurities present in solution.  I speculate that the absence of polymerization is likely due to a lack of propagation. The NMR-scale experiment suggests that a lithiated species can form. However, it is possible that this species does not actually add to another monomer to propagate chain growth. Likewise, the lithiated species could be quenched by impurities in solution, consequently inhibiting polymer formation.  References begin on page 59  Chapter Two  53  2.3 Summary  New phosphaalkenes 2.1 and 2.2 were successfully prepared via the base-catalyzed phospha-Peterson reaction, whereas the synthesis of 2.3 was achieved via the standard phospha Peterson route. The molecular structures of these new phosphaalkenes were studied by X-ray diffraction analysis. Anionic polymerization of 2.1 and 2.3 afforded new polymers, 2.4 and 2.5. Attempted polymerization of 2.2 resulted in no polymer formation. The electronic properties of phosphaalkenes 2.1 and 2.3 and polymers 2.4 and 2.5, as well as the chemical functionalization of these polymers, will be discussed in Chapter 3.  2.4 Experimental section  General procedures. All manipulations of air and/or water sensitive compounds were performed under a nitrogen atmosphere using standard Schlenk techniques or in a glovebox. Hexanes and dichloromethane were deoxygenated with nitrogen and dried by passing through a column containing activated alumina. THF was freshly distilled from sodium/benzophenone ketyl. KOH and NaOH were made anhydrous by following a literature procedure (recrystallization from EtOH and subsequent heating in vacuo). 38 CDC1 3 and C D were dried 6 25 l-benzoylnaphthalene, , 2 ) 3 over molecular sieves prior to use. MesP(SiMe 24 29-benzoylphenantbrene were prepared following modified literature ° 3 ’ 29 and 24 benzoylthiophene, procedures. n-BuLi (1.6 M in hexanes) and MeLi (1.6 M in diethyl ether) were purchased from Aldrich and were titrated prior to use to determine the concentration. 39 Equipment. ‘H, 31 P, and ‘ C{’H} NMR spectra were recorded on Bruker Avance 300 MHz or 3  400 MI-Iz spectrometers. Chemical shifts are reported relative to: residual CHC1 3 (5 = 7.26 for H (5 = 7.15 for ‘H); 85% 4 5 D 6 P0 as an external standard (.5 = 0.0 for 31 3 H ‘H); C 3 (.5= P); CDC1  References begin on page 59  Chapter Two  54  77.16 for ‘ C { ‘H}). Molecular weights were estimated by triple detection gel permeation 3 chromatography (GPC-LLS) using a Waters liquid chromatograph equipped with a Waters 515 HPLC pump, Waters 717 plus autosampler, Waters Styragel columns (4.6 x 300 mm) HR2, HR4, and HR5E, and a Waters 2410 differential refractometer (refractive index detector A. = 940 nm), Wyatt tristar miniDAWN (laser light scattering detector operating at A.  690 nm) and a  Wyatt ViscoStar viscometer. A flow rate of 0.5 mL min 1 was used, and samples were dissolved in THF (ca. 2 mg mL ). The dn/dc for each sample was determined using the software. 1 Elemental analyses were performed in the UBC-.chemistry Microanalysis Facility. Mass Spectra were recorded on a Kratos MS 50 instrument in El mode (70 eV).  2.4.1 Preparation of MesP=C(Naph)(Ph) (2.1). MesP(SiMe 2 (8.6 g, 0.029 mol) dissolved in ) 3  THF (15 mL) was treated with 1-benzoylnaphthalene (6.7 g, 0.029 mol) dissolved in minimal THF and a catalytic amount of KOH (4 mg, 0.07 mmol). The yellow mixture was stirred and the P NMR spectroscopy. After being stirred for 2 weeks at 55 reaction progress was monitored by 31 °C, 80% of MesP(SiMe 2 had converted to the desired product (31p ) 3  =  251, 239; E/Z mixture),  and the solvent was removed in vacuo. The crude product was purified by vacuum distillation at 210 °C (0.01 mmHg). Recrystallization of the distillate in hexanes at room temperature afforded yellow crystals suitable for X-ray diffraction. Yield: 2.56 g (25%). P NMR (CDC1 31 , 162 MHz): 3  251 (Z-isomer), 239 (E-isomer); 1 H NMR (CDC1 , 400 MHz) 3  (E-isomer): ó 7.9—6.8 (m, 14H, Ar), 2.4 (s, 6H, 3 o-CH ) , 2.3 (s, 3 3H,p-CH ) C{ 3 ‘ H } NMR ; 1 , 101 MHz): ö 191.1 (d, 3 (CDcl Hz), 140.5 (d,  Jp  =  ‘Jcp  =  44Hz, PC), 143.3 (d,  7 Hz), 138.9 (s), 136.7 (d,  Jcp 1  =  Jcp  =  15 Hz), 141.7 (d, Jcp  40 Hz, i-Mes), 134.1  (s),  132.0 (d,  =  27  Jcp  Hz), 129.4— 124.8 (m), 22.2 (d, 3 Jcp = 9 Hz, 3 o-CI-1 ) , 21.3 3 (s,p-CH ) ; MS (El, 70eV): m/z  9  [%]  References begin on page 59  Chapter Two  55  368,367,366 [2,21,91;Mj;365 [100;M—H];246 [21;M—H—Mes]; 119[8;M—H—Mes —  Naph].  S)(Ph) (2.2). MesP(SiMe 3 H 4 2 (7.89 g, 0.027 mol), 2) 3 2.4.2 Preparation of MesP=C(C  benzoylthiophene (5.01 g, 0.027 mol), and anhydrous KOH (4 mg, 0.07 mmol) were mixed and dissolved in THF (15 mL). The reaction mixture was stirred, and the reaction progress was monitored by 31 P NMR spectroscopy. After 5 days, MesPC(C S)(Ph) was formed 3 H 4 quantitatively  (&ip  =  227, 220; E/Z mixture). The solvent was removed in vacuo, resulting in a  dark amber oil. The crude product was purified by vacuum distillation at 195 °C (0.01 mmHg). Yellow crystals suitable for X-ray diffraction were obtained from slow evaporation of a hexanes solution. Yield = 5.19 g (60 %). P NMR (CDC1 31 , 162 MHz) (E/Zmixture): 3 mixture):  227, 220. ‘H NMR (C , 400 MHz) (E/Z D 6  7.6—6.4 (m, 1OH, Ar), 2.39, 2.27 (s, 6H, 3 o-CH ) , 2.14, 1.94 (s, 3H,p-CH ). ‘ 3 C{’H} 3  NMR (CDC1 , 101 MHz) (E/Zmixture): 3 PC), 149.5 (d, Jcp Hz), 141.2 (d,  Jcp  =  184.8 (d,  28 Hz), 146.2 (d, Jcp 7 Hz), 140.7 (d,  Jcp  =  =  Jcp 1  =  40 Hz, P=C), 181.3 (d,  20 Hz), 144.4 (d,  7 Hz), 136.2 (d,  ‘Jcp  26 Hz), 142.5 (d,  Jcp  =  Jcp 3  [5; M— H  —  Jcp= 3  Mes]; 161 [8; M— H  —  S 3 H 4 C  —  —  H  —  45 Hz,  Jcp  Ph]; 238 [73; M— H  Ph]; 119 [8; M— H  —  S 3 H 4 C  —  =  13  ‘Jcp  9Hz, 3 o-CH ) ,  [%] 324, 323,  8 Hz, 3 o-CH ) , 21.4 3 (s,p-CH ) , 21.2 3 (s,p-CH ) . MS (El, 70eV): m/z  322 [6, 24, 100; Mj; 321 [15; M— H]; 244 [29; M  =  46 Hz, i-Mes), 135.5 (d,  40Hz, i-Mes), 129.4— 127.7 (m), 127.5 (s), 126.6— 126.1 (m), 22.5 (d, 21.9 (d,  Jcp  —  S]; 202 3 H 4 C  Mes].  2.4.3 Preparation of MesPC(Phen)(Ph) (2.3). A stirred solution of MesP(SiMe 2 (2.38 g, 8 ) 3 mmol) in THF was treated with MeLi in Et 0 (5.35 mL, 1.5 M, 8 mmol) at 25 °C. After heating 2  References begin on page 59  Chapter Two  56  the reaction mixture at 65 °C for 12 h, analysis of an aliquot removed from the reaction by 31 P NMR spectroscopy suggested the complete lithiation of the starting material to 3 MesP(SiMe ) Li (31p =  —187). To this reaction mixture was added 9-benzoylphenanthrene (2.27 g, 8 mmol)  dissolved in THF at —78 °C. After the reaction mixture was stirred for 10 mm at —78 °C, 31 P NMR spectroscopic analysis of an aliquot removed from the reaction mixture suggested quantitative formation of 2.3  (ö i 3 p =  252, 238; E/Zmixture). The reaction mixture was then  SiC1 (1.0 mL, 8 mmol) to quench LiOSiMe 3 treated with Me . After the removal of solvent, the 3 crude oil was extracted with hexanes (3 x 40 mL) and filtered through Celite. The solvent was removed in vacuo leaving a red oil. Yellow crystals suitable for X-ray diffraction were obtained from slow evaporation of a hexanes solution. Yield: 0.50 g (15%). P NMR (CDC1 31 , 162 MHz): 3 isomer):  252 (Z-isomer), 238 (E-isomer); ‘H NMR (C , 400 MHz) (Z D 6  8.3 —7.0 (m, 14H, Ar-fl), 6.7—5.8 (br, 2H, Mes-fl), 2.8  3H,p-CH ) 3 ; ‘ C{’H} NMR (CDC1 3 , 101 MHz) (E!Zmixture): 3 191.0 (d,  Jcp 1  Hz), 140.1 (d,  =  44 Hz, P=C), 144.2 (d,  Jp  7 Hz), 136.6 (d,  =  Jcp 1  (br, 3 o-CH ) , 22.6 (d,  28 Hz), 138.9 =  (s),  Jp =  138.1  24 Hz), 142.7 (d, (s),  40 Hz, i-Mes), 135.9 (d,  Jcp 3  138.0 Jcp 1  =  (s),  —  1.8 (br, 6H, 3 o-CH ) , 1.6  193.7 (d, Jcp  =  136.6 (d,  Jcp 1  44Hz, P=C),  15 Hz), 140.5 (d, Jcp  =  Jcp  =  6  7 Hz), 140.7 (d, Jcp  41 Hz, i-Mes), 131.6  —  (s,  122.5  (m),  =  22.6  ), 21.3 (s,p-CH 3 ), 21.0 3 3 9 Hz, o-Cl-1 (s,p-CH ) . MS (El, 70eV): m/z  [%] 418, 417, 416 [3, 29, 98; Mj; 415 [100; M—H]; 296 [29; M— H— Mes]; 220 [5; M— Mes —  Phen]; 119 [13; M— H —Mes  —  Phen]. Anal. Calcd for H P: 3 C 2 0 C, 86.51; H, 6.05. Found: 5  C, 86.15; H, 6.09.  2.4.4 Preparation of [MesP—C(Naph)(Ph)] (2.4). The polymerization of 2.1 was carried out  inside a glovebox. To a stirred solution of 2.1 (0.84 g, 2.3 mmol) dissolved in THF (6 mL) was  References begin on page 59  Chapter Two  57  added n-BuLi (1.2 M, 38 iL, 0.05 mmol). The reaction mixture was stirred at room temperature and monitored by  31  NMR spectroscopy, which showed an increase in intensity of a broad  signal over 2 weeks. Thereafter, the reaction mixture was removed from the glovebox and quenched using methanol (3 drops). After the removal of solvent in vacuo, the polymer was isolated via hexanes precipitation (3 x 100 mL), then dried in a vacuum oven at 65 °C for 24 h. Yield —  327 mg (40%). 31 P NMR (CDC1 , 122 MHz): ö —9 (br). ‘H NMR (CDC1 3 , 300 MHz): 3  5 (br, Ar-H), 3.5  —  0.5 (br, CH ). GPC-LLS (THF): M 3  =  40,100, PDI  =  9  1.42. Anal. Calcd for  23 C, 85.22; H, 6.33. Found: C, 83.38; H, 6.45. H 26 (C P):  2.4.5 Attempted preparation of IMesP—C(C S)(Ph)] 3 H 4  .  The polymerization of 2.2 was  attempted a number of times using different monomer:initiator ratios and different temperatures inside a glovebox. The following procedure describes an attempt using 2 mol% initiator at room temperature: To a stirred solution of 2.2 (0.47 g, 1.5 mmol) dissolved in THF (3 mL) was added n-BuLi (1.2 M, 24.6 L, 0.03 mmol). The reaction mixture was stirred at room temperature and monitored by 3 ’P NMR spectroscopy for 7 days by removing aliquots from the reaction mixture. The 3 ’P NMR spectra of the aliquots showed two signals that were assigned to 2.2  (31p =  227,  220); there was no broad signal that would be characteristic of polymer formation.  2.4.6 Preparation of [MesP—C(Phen)(Ph)] (2.5). The polymerization of 2.3 was performed inside a glovebox. A stirred solution of 2.3 (0.39 g, 1.3 mmol) dissolved in THF (3 mL) was treated with n-BuLi (1.2 M, 16 tL, 0.02 mmol). The reaction mixture was stirred at room temperature and monitored by 31 P NMR spectroscopy, which showed the gradual increase in intensity of a broad signal over 8 days. The reaction mixture was subsequently removed from  References begin on page 59  Chapter Two  58  the glovebox and quenched with methanol (3 drops). The solvent was removed in vacuo, leaving an orange oil. The polymer was isolated by hexanes precipitation (3 x 100 mL), then dried in a vacuum oven at 65 °C for 24 h. Yield = 124 mg (32%). 31 P NMR (CDC1 , 122 MHz): 3  —10 (br).  ‘H NMR (CDC1 , 300 MHz): 3  =  27,100, PDI  9  —  5 (br, Ar), 3.5  —  0.5 (br, 3 CH ) . GPC-LLS (THF): M 11  oH C, 86.51; H, 6.05. Found: C, 85.12; H, 6.06. 3 (C P): 1.39. Anal. Calcd for 25  2.4.7 X-ray crystallography. All single crystals were immersed in oil and were mounted on a  glass fiber. Data were collected on a Bruker X8 APEX II diffractometer with graphite Mo Ka radiation. All structures were solved by direct methods and subsequent Fourier difference techniques and refined anisotropically for all non-hydrogen atoms. All data sets were corrected for Lorentz and polarization effects. Refinements were performed using the SHELXTL ° 4 crystallographic software program of Bruker-AXS.  References begin on page 59  Chapter Two  59  2.5 References (1)  Hissler, M.; Dyer, P. W.; Réau, R. Coord. Chem. Rev. 2003, 244, 1-44.  (2)  Hissler, M.; Dyer, P. W.; Réau, R. Top. Curr. Chem. 2005, 250, 127-163.  (3)  Sebastian, M.; Hissler, M.; Fave, C.; Rault-Berthelot, J.; Odin, C.; Réau, R. Angew. Chem.,  mt.  Ed. 2006, 45, 6152-6155.  (4)  Baumgartner, T.; Réau, R. Chem. Rev. 2006, 106, 4681-4727.  (5)  Hobbs, M. G.; Baumgartner, T. Eur. .J Inorg. Chem. 2007, 3611-3628.  (6)  Crassous, J.; Réau, R. Dalton Trans. 2008, 6865-6876.  (7)  Tsang, C. W.; Yam, M.; Gates, D. P. 1 Am. Chem. Soc. 2003, 125, 1480-148 1.  (8)  Noonan, K. J. T.; Feldscher, B.; Bates, J. I.; Kingsley, J. J.; Yam, M.; Gates, D. P. Dalton Trans. 2008, 445 1-4457.  (9)  Gillon, B. H.; Patrick, B. 0.; Gates, D. P. Chem. Commun. 2008, 2161-2163.  (10)  Becker, G.; Mundt, 0. Z Anorg. Allg. Chem. 1980, 462, 130-142.  (11)  Yoshifuji, M.; Toyota, K.; Inamoto, N. Tetrahedron Lett. 1985, 26, 1727-1730.  (12)  Van der Does, T.; Bickelhaupt, F. Phosphorus, Sulfur Silicon Relat. Elem. 1987, 30, 515518.  (13)  Jouaiti, A.; Geoffroy, M.; Bernardinelli, G. Tetrahedron Lett. 1992, 33, 507 1-5074.  (14)  Jouaiti, A.; Geoffroy, M.; Bernardinelli, G. Tetrahedron Lett. 1993, 34, 3413-3416.  (15)  Jouaiti, A.; Geoffroy, M.; Bernardinelli, G. Chem. Commun. 1996, 437-438.  (16)  Kawanami, H.; Toyota, K.; Yoshifuji, M. I Organomet. Chem. 1997, 535, 1-5.  (17)  lonkin, A. S.; Marshall, W. J. Heteroat. Chem. 2002, 13, 662-666.  (18)  Termaten, A.; van der Sluis, M.; Bickeihaupt, F. Eur. I. Org. Chem. 2003, 2049-2055.  (19)  van Staden, L. F.; Gravestock, D.; Ager, D. J. Chem. Soc. Rev. 2002, 3], 195-200.  References begin on page 59  Chapter Two  60  (20)  Becker, G.; Uhi, W.; Wessely, H. J. Z. Anorg. Aug. Chem. 1981, 479, 4 1-56.  (21)  Becker, G.; Becker, W.; Mundt, 0. Phosphorus, Sulfur Silicon Relat. Elem. 1983, 14, 267-283.  (22)  Yam, M.; Chong, J. H.; Tsang, C. W.; Patrick, B. 0.; Lam, A. E.; Gates, D. P. Inorg. Chem. 2006, 45, 5225-5234.  mt.  (23)  Noonan, K. J. T.; Gates, D. P. Angew. Chem.,  (24)  Dubois, J. E.; Boussu, M. Tetrahedron Lett. 1970, 2523-2526.  (25)  Becker, G.; Mundt, 0.; Rossler, M.; Schneider, E. Z. Anorg. Alig. Chem. 1978, 443, 42-  Ed. 2006, 45, 7271-7274.  52.  mt.  (26)  Appel, R.; Knoll, F.; Ruppert, I. Angew. Chem.,  (27)  Yoshifuji, M.; Toyota, K.; Inamoto, N.; Hirotsu, K.; Higuchi, T. Tetrahedron Lett. 1985,  Ed. Engi. 1981, 20, 73 1-744.  26, 6443-6446. (28)  Gudimetla, V. B.; Rheingold, A. L.; Payton, J. L.; Peng, H. L.; Simpson, M. C.; Protasiewicz, J. D. Inorg. Chem. 2006, 45, 4895-4901.  (29)  Arnold, D. R.; Birtwell, R. J. J Am. Chem. Soc. 1973, 95, 4599-4606.  (30)  Krasovskiy, A.; Knochel, P. Angew. Chem.,  (31)  Van Der Knaap, T. A.; Kiebach, T. C.; Visser, F.; Bickeihaupt, F.; Ros, P.; Baerends, E.  mt.  Ed. 2004, 43, 3333-3336.  J.; Stam, C. H.; Konijn, M. Tetrahedron 1984, 40, 765-776. (32)  Mundt, 0.; Becker, G.; Uhi, W.; Massa, W.; Birkhahn, M. Z. Anorg. Aug. Chem. 1986, 541, 319-335.  (33)  CRC Handbook of Chemistry and Physics; 84 ed.; CRC Press: Boca Raton, Florida, 2003.  References begin on page 59  Chapter Two (34)  61  Regitz, M.; Scherer, 0. J. Multiple Bonds and Low Coordination in Phosphorus Chemistry; Thieme: New York, 1990.  (35)  Bai, C.; Fu, H.; Zhang, M. Huaxue Tongbao 1983,3, 14-15.  (36)  Trotter, J. Acta Crystallogr. 1963, 16, 605-609.  (37)  Gillon, B. H.; Noonan, K. J. T.; Feldscher, B.; Wissenz, J. M.; Kam, Z. M.; Hsieh, T.; Kingsley, J. J.; Bates, J. I.; Gates, D. P. Can. J. Chem. 2007, 85, 1045-1052.  (38)  Armarego, W. L. F.; Perrin, D. D. Purflcation ofLaboratory Chemicals; 4th ed.; Butterworth Heinemann Press: Oxford, 1998.  (39)  Burchat, A. F.; Chong, J. M.; Nielsen, N. J Organomet. Chem. 1997, 542, 28 1-283.  (40)  SHELXTL Version 5.1. Bruker AXS Inc., Madison, Wisconsin, USA, 1997.  References begin on page 59  62  Chapter Three Chemical Modification of Poly(methylenephosphine)s with Conjugated Substituents Accompanied by Changes in Electronic Properties*  3.1 Introduction As discussed in Chapter 2, new poly(methylenephosphine)s bearing naphthyl and phenanthrenyl substituents were successfully prepared by anionic polymerization of phosphaalkenes. The chemical equation for the reaction is shown in Scheme 3.1. 2 mol% n-BuLl  P=c  Ph  Met  THF, RT  F  1  n-Bu-f---P—C----I-H  -  Mes =  [MS Phj  -  mesityl 3.la R 3.lb R  = =  Naph Phen  3.2a R 3.2b A  = =  Naph Phen Naph= —  —  1 -naphthyl  Phen =  9-phenanthrenyl  Scheme 3.1 Due to the Lewis basicity and unique reactivity of phosphorus (III) (e.g. oxidation and 2 the chemical modification of the phosphine centres in [MesP—C(Naph)(Ph)J coordination),” (3.2a) and [MesP—C(Phen)(Ph)] (3.2b) should be feasible. In this sense, the phosphorus atoms may act as receptor sites for analytes, possibly leading to a change in the electronic structure to give a sensor-like behavior. Following the preparation of macromolecules 3.2a and 3.2b, the *A version of this chapter will be submitted for publication. Chun, C. P. and Gates, D. P. Chemical Modification of Poly(methylenephosphine)s Bearing Conjugated Substituents Accompanied By Changes in Electronic Properties.  Chapter Three  63  next goal was to chemically modify the polymers and examine the concomitant changes in the electronic properties. Based on literature precedent, 4 we expect that the presence of the phosphorus lone pair ’ 3 in 3.2a and 3.2b would lead to a fluorescence quenching effect on the polymer, resulting in weaker fluorescence intensity or no fluorescence at all. The lone pair on phosphaalkenes, 3.la and 3.lb, is expected to invoke a similar quenching effect. We hypothesize that coordination of the phosphorus lone pairs in poly(methylenephosphine)s 3.2a and 3.2b to an electrophilic analyte (E) will eliminate the quenching effect and allow fluorescence to occur (Scheme 3.2).  E  nBuf_H Mes Ph Weak fluorescence or no fluorescence due to lone pair quenching effect  nBuf_H MesPh Coordination of lone pair to E allows fluorescence to occur  Scheme 3.2 This chapter describes experiments undertaken to test the hypothesis that chemical functionalization of phosphine polymers 3.2a and 3.2b would lead to fluorescence. More specifically, this discussion entails the post-polymerization functionalization of 3.2a and 3.2b via oxidation and coordination to borane moieties. In addition, this chapter includes preliminary results from the investigation of the electronic properties of phosphaalkenes 3.1 a and 3. ib, poly(methlyenephosphine)s 3.2a and 3.2b, and the new chemically functionalized polymers.  References begin on page 84  Chapter Three  64  3.2 Results and Discussion 3.2.1 Oxidation of 3.2a and 3.2b  Previous work in the Gates lab showed that [MesP—CPh 1 can be easily oxidized using ] 2 11202  or by exposing a solution of the polymer to air for four days. 5 In this thesis work, the  oxidation of poly(methylenephosphine)s 3.2a and 3.2b was investigated. According to 31 P NMR spectroscopic analysis, a solution of naphthyl-derivatized polymer 3.2a did not show any evidence of oxidation after being exposed to air for one week, suggesting that 3.2a was quite air stable. Nonetheless, the oxidation of 3.2a was achieved by treating a 2 C1 solution of 3.2a CH with aqueous 30% H 0 (Scheme 3.3). The oxidation progress was monitored by 31 2 P NMR spectroscopy. The complete oxidation of 3.2a required an excess of H 0 (2.6 equiv) and the 2 reaction mixture was stirred overnight. The 31 P NMR spectrum of the oxidized polymer [MesP(0)—C(Naph)(Ph)] (3.3a) is shown in Figure 3.1, and for comparison the 31 P NMR spectrum of 3.2a is also included. The 31 P chemical shift of 3.3a (47 ppm) is the same as that of ]. 2 [MesP(0)—CPh 5  F  Naphi n-Bu-I—P—C—j-H LMes Ph  30% H 0 (aq.) 2 CH2CI2  3.2a  F  0 Naphi  [MS Ph  3.3a Scheme 3.3  References begin on page 84  Chapter Three  65  E  Naph  n-Bu fe—c [Mes PhJ  -9 ppm  —FH  (a)4/  E ONaPh]—t  -Bu ----P C [Mes Ph —  47 ppm  H  (b’ ppm  100  150  50  0  -50  -100  -150  Figure 3.1. 31 P NMR spectra (THF, 122 MHz) of(a) 3.2a and (b) 3.3a.  In contrast to the naphthyl-derivatized phosphine polymer 3.2a, the phenanthrenyl derivatized poly(methylenephosphine) 3.2b oxidizes more readily in air when dissolved in THF (Scheme 3.4). After 3 hours of exposure to air, the 31 P NMR spectrum of a THF solution of 3.2b showed the appearance of a new broad signal at 49 ppm (Figure 3 .2b). The broad resonance at 10 ppm is assigned to unoxidized phosphorus centres in the polymer, which is consistent with the P NMR chemical shift of 3.2b (Figure 3.2a). After 1 week, 3.2b was completely oxidized to 31 give [MesP(O)—C(Phen)(Ph)] (3.3b)  r  (&lp  =  49) (Figure 3.2c).  Pheni  n-Bu-l---P—C—j-H [MS Ph  j  air THE 1 week  3.2b  r  Pheni  H 4 n-Bu-l——C-[MS Ph 3.3b  Scheme 3.4 Oxidized polymers 3.3a and 3.3b were isolated as white solids after the removal of solvent in vacuo. Analysis of 3.3a and 3.3b by triple detection gel permeation chromatography (GPC) showed that 3.3a exhibited an absolute number average molecular weight (Ma) of 43,500  References begin on page 84  Chapter Three  66  Pheni F n-Bu -f-- P C —f H  10 ppm  —  [Mes Ph 3.2b  (a)  49ppm  lOppm  F 0 Pheni  n-Bu-j—-P—C—-I-H 49 ppm  [Mes Phi  (C)4 ppm  io  100  50  -50  -100  -150  Figure 3.2. 31 P NMR spectra (THF, 122 MHz) of(a) 3.2b; (b) an aliquot from the THF solution of 3.2b exposed to air for 3 h; (c) an aliquot from the same solution exposed to air for 7 d to form 3.3b.  g mol’ and 3.3b exhibited an M value of 31,300 g mof’. Both oxidized macromolecules have slightly higher M values than their parent unoxidized polymers (3.2a: M 3.2b: M  =  =  42,160 g mol’;  27,000 g moij, which is expected. According to the GPC analysis, the polydispersity  index (PDI) of 3.3a is 1.16, while that of 3.3b is 1.46. Oddly, the two oxidized macromolecules 3.3a and 3.3b have narrower PDI values than their parent unoxidized polymers (3.2a: PDI 1.40; 3.2b: PDI  =  1.49). This may be due to interaction of the phosphine moieties in the  unfunctionalized poly(methylenephosphine)s with the GPC columns, which has been reported for phosphine polymers in the past. 7 For example, the PDI of ] ’ 6 2 ) 3 [MesP(BH —CPh (M  =  4.13  x i0 g moF ) was reported to be 1.26, slightly lower than that of the parent unfunctionalized 1 ] (M 2 [MesP—CPh  =  3.89 x i0 4 g mol’; PDI  =  1.34).  References begin on page 84  Chapter Three  67  3.2.2 Boronation of 3.2a and 3.2b  Chemical functionalization of poly(methylenephosphine)s 3.2a and 3.2b can also be accomplished by using BH 3 moieties to form phosphine-borane adducts along the main chain. This was achieved by treating the polymers dissolved in THF with BHySMe 2 (1.3 equiv) at —78 °C, then allowing the reaction mixtures to warm slowly to room temperature. Reaction progress P NMR spectroscopy, which suggested that the phosphine moieties in 3.2a was monitored by 31 and 3.2b were only partially complexed with borane moieties after the first addition of SMe (1.3 equiv) was added to each reaction 3 BH SMe (1.3 equiv). Hence, additional 2 3 BH 2 mixture at —78 °C. 31 P NMR spectroscopic analysis suggested that 70% of the phosphorus atoms in naphthyl-derivatized polymer 3.2a were functionalized with borane moieties, giving a partially functionalized phosphine-borane polymer (3.4a) (Scheme 3.5). On the other hand, 31 P NMR analysis revealed that 3.2b was completely functionalized to give [MesP(BH )— 3 C(Phen)(Ph)] (3.4b) (Scheme 3.6). Surprisingly, it appears that phenanthrenyl-derivatized poly(methylenephosphine) 3.2b is more reactive than naphthyl-derivatized polymer 3.2a. This may be due to an effect whereby the phenanthrenyl side groups are oriented in such a way that allows easier access to the phosphorus centres and the naphthyl substituents are oriented in such a way that hinders access.  F  Naphi H 4 n-Bu--I—P—CLMes Ph  ’SMe (excess), —78 C 3 BH 2 warm slowly to RT, 12 h  [7  /7  BHNaph\  Naph\  H n-Bu-I-(—P-——C /-(—-—c [\Ms PhJ / \Mes Ph1 07 03  3.2a  3.4a Scheme 3.5  F Pheni n-Buf_ _ 9 -[H LMes Ph j  SMe (excess), 3 BH 2  7800  THE warmslowlytoRT, 12h  3.2b  F  BH P 3 henl n-Bu-—P-—C-----H [Mes Ph] 3.4b  Scheme 3.6  References begin on page 84  Chapter Three  68  Figures 3.3 and 3.4 show 31 P NMR spectra of new borane-phosphine adduct polymers 3.4a and 3.4b, and for comparison, 31 P NMR spectra of the unfunctionalized macromolecules are also included. The 31 P chemical shift of 3.4b 3.4a  (31p  =  (31p  =  28) and the downfield 31 P chemical shift of  27) are similar to the 31 P chemical shift of 2 )—CPh 3 [MesP(BH 1  =  26.8).  Naph  E  n-Bu -I— p  -9 ppm  (31p  —  C—i-H  [MS Phi  (a)  [4 9 nBu.f[Iç_f__  BHNaph\  27 ppm  Naph\\  /1/f  )  /19  )  H  0.3n n  (b)  ppm  150  100  50  0  -50  -100  -150  Figure 3.3. 31 P NMR spectra (THF, 122 MHz) of(a) 3.2a and (b) 3.4a.  E n-Bu  10 ppm  Phen  -f—P—C—-f-H  [Mes Ph 3.2b  (a)  BH P 3 henf n-B u-f—P-—c —f-H  E  [Mes  Ph]  3.4 b  (b) ppm’  100  ‘  so  ‘  -so  ‘  -100  -150  Figure 3.4. 31 P NMR spectra (THF, 122 MHz) of(a) 3.2b and (b) 3.4b.  References begin on page 84  Chapter Three  69  Boronated polymers 3.4a and 3.4b were isolated as off-white solids after removal of solvent in vacuo, and were analyzed by triple detection GPC. According to the analysis, the M 11 values of 3.4a and 3.4b were 24,700 g mol’ and 27,900 g mol’, respectively. These values are slightly higher than the M values of their parent unfunctionalized polymers (3.2a: M mol’; 3.2b: M  =  =  22,900 g  27,000 g mol’). Similar to the case observed for the oxidized polymers, the  PDI values of 3.4a (PDI  1.33) and 3.4b (PDI  parent poly(methylenephosphine) (3.2a: PDI  =  =  1.32) are lower than the PDI values of their  1.39; 3.2b: PDI  =  1.49). This effect may be  attributed to interaction of the phosphine moieties in 3.2a and 3.2b with the GPC columns, as discussed previously.  3.2.3 UV/Vis and Fluorescence Measurements of 3.la  —  3.4a  The UV/Vis spectra of the naphthyl-derivatized phosphaalkene 3.la, the unfunctionalized naphthyl-derivatized poly(methylenephosphine) 3.2a, and the functionalized naphthyl derivatized polymers 3.3a and 3.4a are shown in Figure 3.5. THF was used as a solvent for all absorption spectra. A summary of the absorption bands and their assignments is tabulated in Table 3.1.  Table 3.1. Summary of UV/Vis absorption bands and assignments of 3.la  (nm) 296 316 (shoulder) 290 ?max  3.la 3.2a 3.3a 3.4a  272 288 288  (M’cm’) 1.6x 10 1.5 x 1 0 1.5x 10 4.4 x i0 3 7.6x 10 1.Ox 10  3.4a.  —  assignment tit*(Naph) * (P=C) rt_t*(Naph) —  —  3t*  (Naph)  3t_n*(Naph)  References begin on page 84  Chapter Three  70  0  300  350  400  450  Wavelength (nm)  Figure 3.5. UV/Vis spectra (THF) of 3.la (3.1 x 10 M), 3.2a (3.1 x 10 5 M), 3.3a (4.3 x 10 5 M), 5 and 3.4a (4.2 x i0 M).  A common absorption band shared by the naphthyl-derivatized monomer and polymers 3.la  —  3.4a occurs around 290 nm. Since these absorption bands around 290 nm nearly align  with the band assigned to one of the  2t  —  3t*  absorptions around 290 nm are assigned to  transitions of naphthalene it  —  (?max  =  286 nm), 8 these  transitions of the naphthyl substituent.  References begin on page 84  Chapter Three  71  Naphthalene exhibits three absorptions in the UV region assigned to  t  —  transitions which  include transitions that are symmetry-allowed and spin-forbidden but occur due to vibronic 9 The oxidized polymer, 3.3a, shows an additional shoulder at 272 nm. Since the coupling. wavelength of this absorption is very similar to another band of naphthalene assigned to a n transition  Qrnax  =  276 nm), 8 the shoulder is assigned to a t  —  it  —  transition of the naphthyl  substituent. A shoulder is also observed in the spectrum of phosphaalkene monomer 3.la at 316 nm. This shoulder is assigned to the n observed for MesP=CPh 2  (?max  After obtaining the properties of 3.la  —  ?max  =  —  transition of the P=C bond, and is similar to that  324 nm).’°  values of 3.la  —  3.4a by UV/Vis spectroscopy, the emissive  3.4a were examined. Dilute solutions of 3.la  were excited at their  ’max 2  —  3.4a in THF (ca. i0 M)  values. The wavelength and intensity of their emissions were recorded  and these spectra are displayed in Figure 3.6. As illustrated in the spectra, naphthyl-derivatized phosphaalkene 3.1 a and unfunctionalized poly(methylenephosphine) 3.2a showed no fluorescence when excited at 296 nm and 290 nm, respectively. However, oxidized polymer 3.3a and boronated polymer 3.4a were fluorescent when irradiated at 288 nm. The wavelengths of their emission bands were 329 nm and 312 nm, respectively, both in the UV region. A summary of these fluorescence measurements is presented in Table 3.2, including the values of the Stokes shifts. The Stokes shifts exhibited by 3.3a and 3.4a are 41 nm and 24 nm, respectively. The small Stokes shift exhibited by 3.4a, in comparison to the range of Stokes shifts reported in the literature, can be a sign of rigidity in the main chain.  References begin on page 84  Chapter Three  72  z C 0 U) U)  E  UI  300  350  400  450  Wavelength (nm)  Figure 3.6. Emission spectra (THF) of 3.la (3.1 x i0M), 3.2a (3.1 x 10 M), 3.3a 5 (4.3 x i0 M), and 3.4a (4.2 x i0 M).  Table 3.2. Summary of emission measurements on 3.la  —  3.4a.  3.la  296  (nm) none  3.2a  290  none  3.3a  288  329  41  3.4a  288  312  24  ?ex (iuti)  ?em  Stokes shift (nm) —  —  We have shown that the complexation of the phosphorus lone pairs in non-emissive poly(methylenephosphine) 3.2a resulted in fluorescence in the UV region. The lack of fluorescence in the 3.2a is consistent with our expectation that the unfunctionalized phosphine polymer would be non-emissive or weakly emissive, as discussed in the introduction of this chapter. The fact that 3.2a is non-emissive is likely due to a quenching effect from the lone pair electrons on phosphorus, while coordination of these lone pair electrons leads to emission. A possible mechanism to account for these observations is the photoinduced electron transport  References begin on page 84  Chapter Three  73  process, a mechanism that is commonly reported for “turn-on” chemosensors.’ 126 In this process, there exists a relatively high-energy nonbonding electron pair that quenches the fluorescence of the fluorophore in the absence of an analyte (Figure 37)  11,21,24,25  The quenching occurs by a  rapid intramolecular electron transfer from the lone pair orbital to the HOMO of the fluorophore. However, coordination of the electron pair to another functionality lowers the energy of the lone pair, thus allowing fluorescence to occur from the excited fluorophore. Figure 3.7 shows a simplified depiction of the electronic processes involved in relaxation to ground state. In addition to fluorescence, relaxation to the ground state also includes internal conversion and vibrational relaxation.  In the absence of analyte:  F  Upon coordination of lone pair to another functionality:  F LUMO HOMO  LUMO  1  HOMO  1 ‘pI  Fluorophore  Nonbonding Lone Pair  Non-emissive or weakly fluorescent  Fluorophore  Coordinated Lone Pair  Fluorescent  Figure 3.7. Orbital energy diagram illustrating the process of the photoinduced electron transport mechanism and the resulting effect on fluorescence of a ’ 21 fluorophore.” 2 4 This orbital 5 diagram carries a simplified depiction of the electronic processes involved in the relaxation to the ground state. In reality, relaxation includes internal conversion, vibrational relaxation, and fluorescence.  References begin on page 84  Chapter Three  74  3.2.4 UVIVis and Fluorescence Measurements of 3.lb  —  3.4b  The UV/Vis spectra of the phenanthrenyl-derivatized phosphaalkene monomer and polymers, 3.lb  —  3.4b, dissolved in THF, are shown in Figure 3.8. A summary of the absorption  bands and their assignments is presented in Table 3.3.  U C 0 .0  Wavelength (nm)  Figure 3.8. UV/Vis spectra (THF) of 3.lb (3.8 x 10 M), 3.2b (3.3 x 10 5 M), 3.3b (3.7 x l0 5 M), and 3.4b (3.0 x 10 M). 5  References begin on page 84  Chapter Three  75  Table 3.3. Summary of UV/Vis absorption bands and assignments of 3.lb (nm) 252 (strong) 300 (weak) 254 (strong) 301 (weak) 256 (strong) 301 (weak) 254 (strong) 288 (weak) 301 (weak) max 2  3.lb 3.2b 3.3b 3.4b  (M’cm’) 5.9 x i0 4 2.3 x i0 4 4.4 x i0 9.5 x 3.7 x i0 8.0 x 2.4 x 5.5 x iü 5.1 x 1 ü  —  3.4b.  assignment u’ (Phen) * (Phen and P=C) t (Phen) it (Phen) (Phen) rt (Phen) rt (Phen) t—t (Phen) * (Phen) —  —  —  —  —  —  —  —  The strong absorption bands that are observed in the spectra of the phenanthrenyl derivatized monomer and polymers, 3.lb  —  3.4b, near 250 nm are assigned to  rt  —  3t*  transitions  of the phenanthrenyl moieties because the wavelength and strength of these bands are very similar to the  t  transition of phenanthrene at 252 nm. 27 Like naphthalene, phenanthrene ’ 8  —  exhibits a number of ‘r  —  n’ transitions in the UV region, some of which are symmetry-allowed  and some of which are spin-forbidden but made possible due to vibronic coupling. 9 The UV/Vis spectra of 3.lb assigned to  3t  —  —  3.4b also show weak absorption bands around 300 nm. These bands are also  it  transitions of the phenanthrenyl substitent, and are similar to the weak band  observed in the UV/Vis spectrum of phenanthrene  (?qnax  =  293 nm). 27 The UV/Vis spectrum of ’ 8  boronated phenanthrenyl-derivatized polymer 3.4b exhibits an additional band at 288 nm that is similar to a side band observed in the UVIVis spectrum of phenanthrene the band at 288 nm is tentatively assigned to a t  —  it’  (?‘max  =  283 nm). Hence  transition of the phenanthrenyl moiety.  Unlike the UV/Vis spectrum of naphthyl-derivatized phosphaalkene 3.la, the UV/Vis spectrum of phenanthrenyl-derivatized phosphaalkene 3.lb does not show a separate shoulder attributed to the  t  —  it  transition of the PC bond. This transition may be completely obscured  by the bands already present in the spectrum. On the other hand, its absence may suggest that the  References begin on page 84  Chapter Three  76  PC bond is more delocalized with the aromatic C-substituents in phenanthrenyl-derivatized phosphaalkene 3.lb than in naphthyl-derivatized phosphaalkene 3.la. Support for the latter can be obtained by comparing the angles between the best planes of the aromatic C-substituents and the P=C bond (discussed in section 2.2.4, Chapter 2). The molecular structure of 3.la shows that the phenyl and naphthyl rings are twisted out of the plane of the P=C bond by  400  and 60°,  respectively. The molecular structure of 3.lb shows that the phenanthrenyl ring is twisted out of plane of the P=C bond by 60°, but the phenyl ring is twisted only by 20°. These data suggest that there is a greater degree oft-conjugation present in 3.lb than 3.la, at least in the solid state. Following the UV/Vis measurements discussed above, the emissive properties of phenanthrenyl-derivatized monomer and polymers 3.lb solutions of 3.lb  —  —  3.4b were investigated. Dilute  3.4b in THF (ca. i0 M) were excited at the wavelengths of their  Maximum emission was observed when 3.lb was excited at 300 nni, and when 3.2b excited at 301 mm The emission spectra of 3.lb  —  values. —  3.4b were  3.4b are presented in Figure 3.9 and a  summary of the data is tabulated in Table 3.4.  C 0  E  Ui  325  350  375  400  425  450  Wavelength (nm)  Figure 3.9. Emission spectra (THF) of 3.lb (3.8 x 10 M), 3.2b (3.3 x 10 3 M), 3.3b (3.7 x i0 5 M), and 3.4b (3.0 x i0 M).  References begin on page 84  Chapter Three  77  Table 3.4. Summary of emission measurements on 3.lb  3.lb  (nm) 300  3.2b  301  3.3b 3.4b  ex  —  (nm) 367  ?ern  3.4b.  Stokes shift (nm) 67  301  357 374 367  56 73 66  301  367  66  In contrast to naphthyl-derivatized phosphaalkene 3.la and poly(methylenephosphine) 3.2a which are non-emissive, the spectra of 3.lb and 3.2b show that the phenanthrenyl derivatized phosphaalkene and poly(methylenephosphine) are emissive. The difference in emissive properties between the analogous species is probably due to the extra conjugation in the phenanthrenyl substituent. As shown in Figure 3.9, phenanthrenyl-derivatized phosphaalkene 3.lb, oxidized polymer 3.3b, and boronated polymer 3.4b exhibit maximum emission at 367 nm,  which is the same wavelength reported for the maximum emission of phenanthrene )27  (em  =  367  Phenanthrene also exhibits emission bands of lower intensity at 345 nm and 385 nm, and  interestingly, the emission spectrum of phenanthrenyl-derivatized poly(methylenephosphine) 3.2b shows two bands at 357 nm and 374 nm, close to those of phenanthrene. The Stokes shifts exhibited by 3.lb  —  3.4b range between 56 nm and 73 nm (Table 3.4) and are within normal  range compared to Stokes shifts reported in the literature. Comparison between the spectra in Figure 3.9 shows that the fluorescence intensities of phosphaalkene monomer 3.lb and unfunctionalized poly(methylenephosphine) 3.2b are weaker than the fluorescence intensities of the functionalized polymers 3.3b and 3.4b. This observation is consistent with our hypothesis that the phosphalkenes and unfunctionalized poly(methylenephosphine)s would be non-emissive or weakly emissive while the functionalized References begin on page 84  Chapter Three  78  polymers would be more emissive. The weaker fluorescence intensities of phosphaalkene monomer 3.lb and unfunctionalized poly(methylenephosphine) 3.2b are most likely due to a quenching effect from the phosphorus lone pairs. Due to the structural similarity between naphthyl-derivatized polymers 3.2a the photoinduced electron transport  —  3.4a and phenanthrenyl-derivatized polymers 3.2b 1212425  —  3.4b,  (discussed in the section 3.2.3) can again be  invoked to account for the emissive behaviors of 3.2b  —  3.4b. To confirm the relative strengths  of the fluorescence emissions, the quantum yields of 3.lb  —  3.4b must be determined. This is  considered as future work.  3.3 Summary Poly(methylenephosphine)s 3.2a and 3.2b were chemically functionalized by oxidation and boronation of the phosphorus centres to afford oxidized macromolecules 3.3a and 3.3b, and boronated polymers 3.4a and 3.4b, respectively. The electronic properties of the unfunctionalized and functionalized polymers, as well as those of phosphaalkenes 3.la and 3db, were investigated by UV/Vis and fluorescence spectroscopy. For the naphthyl-derivatized species, the results showed that phosphaalkene 3.la and unfunctionalized poly(methylenephosphine) 3.2a were non-emissive while oxidized polymer 3.3a and boronated polymer 3.4a exhibited emissions in the UV region when irradiated at 288 rim. Similarly, for the phenanthrenyl-derivatized species, the emission intensities of phosphaalkene 3. lb and unfunctionalized poly(methylenephosphine) 3.2b were observed to be lower than those of oxidized polymer 3.3b and boronated polymer 3.4b. These results are consistent with our hypothesis that the chemical functionalization of the phosphorus lone pair in naphthyl-derivatized poly(methylenephosphine) 3.2a and phenanthrenyl  References begin on page 84  Chapter Three  79  derivatized poly(methylenephosphine) 3.2b would prevent quenching of the fluorophore by the lone pair electrons and therefore allow fluorescence to occur. However, further studies are required using other phosphine polymers and different chemical modifications, in addition to measurements of quantum yields, to further generalize and test the hypothesis. Based on the preliminary results presented in this chapter, 3.2a appears to be a better candidate as a sensor than 3.2b because 3.2a is non-emissive whereas 3.2b demonstrates an emissive behavior. It is only upon complexation of the phosphorus lone pairs in 3.2a that fluorescence occurs from this polymer. Consequently, using non-emissive 3.2a instead of 3.2b as a sensor should give a lower probability of false positive results.  3.4 Experimental section  General procedures. All manipulations of air and/or water sensitive compounds were performed under a nitrogen atmosphere using standard Schlenk techniques or in a glovebox. Dichloromethane was deoxygenated with nitrogen and dried by passing through a column containing activated alumina. THF was freshly distilled from sodium/benzophenone ketyl. 3 was dried over molecular sieves prior to use. H CDC1 0 and 2 2 SMe were purchased from 3 BH Aldrich and used as received. Equipment. ‘H, 31 C{’H} NMR spectra were recorded at room temperature on Bruker 3 P, and ‘  Avance 300 MHz or 400 MHz spectrometers. Chemical shifts are reported relative to: residual PO 3 H a s an external standard (5= 0.0 for 3 (ô= 7.26 for ‘H); 85% 4 3 CHC1 ’P); CDCI (5= 77.16 3 for ‘ C{’H}). Molecular weights were estimated by triple detection gel permeation 3 chromatography (GPC-LLS) using a Waters liquid chromatograph equipped with a Waters 515 HPLC pump, Waters 717 plus autosampler, Waters Styragel columns (4.6 x 300 mm) HR2,  References begin on page 84  Chapter Three  80  HR4, and HR5E, and a Waters 2410 differential refractometer (refractive index detector ?. = 940 nm), Wyatt tristar miniDAWN (laser light scattering detector operating at ?  =  690 nm) and a  Wyatt ViscoStar viscometer. A flow rate of 0.5 mL min’ was used, and samples were dissolved in THF (Ca. 2 mg mL’). The dn/dc for each sample was determined using the software. Solution absorption spectra were obtained in THF on a Varian Cary 5000 UV-vis-near-IR spectrophotometer using a 1 cm quartz cuvette. Fluorescence spectra were obtained in THF on a Photon Technology International QuantaMaster fluorimeter using a 1 cm quartz cuvette.  3.4.1 Characterization of MesP=C(Naph)(Ph) (3.la) Experimental procedures, yield, and spectroscopic data were reported in Chapter Two (Section 2.4.1, Page 54). UV/Vis (THF): Xmax/nm  (E/M’ cm’)  296 (1.6 x 10), 216 (1.5 x 10k).  3.4.2 Characterization of MesP=C(Phen)(Ph) (3.lb) Experimental procedures, yield, and spectroscopic data were reported in Chapter Two (Section 2.4.3, Page 55). UV/Vis (THF): ?max/nm  (E/M’ cm’)  =  252 (5.9 x 10), 300 (2.3 x 10).  3.4.3 Characterization of [MesP—C(Naph)(Ph)] (3.2a) Experimental procedures, yield, spectroscopic data, and GPC data were reported in Chapter Two (Section 2.4.4, Page 56). UV/Vis (THF):  Xmax/nm  (E/M’ cm’)  =  290 (1.5 x 10).  3.4.4 Characterization of jMesP—C(Phen)(Ph)] (3.2b) Experimental procedures, yield, spectroscopic data, and GPC data were reported in Chapter Two (Section 2.4.5, Page 57). UV/Vis (THF): ?‘max/nm (E/M’ cm’)  =  254 (4.4 x 10), 301 (9.5 x 10).  References begin on page 84  Chapter Three  81  3.4.5 Preparation of [MesP(O)—C(Naph)(Ph)] 11 (3.3a) To a solution of polymer 3.2a (0.075g, 0.20 mmol, M  =  42,160 g moF’) in 2 CI (5 mL) was added 30% H CH 0 in water (1.5 mL). 2  The reaction mixture was stirred vigorously for 3 h.  NMR spectroscopic analysis of an  aliquot of the reaction mixture showed a partially oxidized polymer  (&ip  =  47, 40%;  &,p  =  —9,  60%). The reaction mixture was treated with another 1.5 mL of 30% H 0 in water. The reaction 2 mixture was stirred overnight. Analysis of the reaction mixture by 31 P NMR spectroscopy suggested complete oxidation of the polymer (31p = 47). The layers were separated and aqueous layer was extracted with 2 C1 (2 x 3 mL). The organic layers were combined and washed CH with H 0 (3 x 5 mL). The organic layer was dried over MgSO 2 . After evaporation of the solvent 4 in vacuo, a white solid was obtained then dried in a vacuum oven at 65 °C. Yield = 24 mg (3 2%). P NMR (CDCI 31 , 162 MHz): 3  47 (br); ‘H NMR (CDCI , 400 MHz): 3  0.5 (br, 3 —CH ) ;‘ C NMR (CDC1 3 , 101 MHz): 3 (THF): M  =  43,500 g mol , PDI 1  =  9.0—5.0 (br, Ar-H), 3.3—  148—123 (br, Ar-C), 30—17 (br, CH ), GPC-LLS 3  1.16. UV/Vis (THF):  ?‘max/nm  (E/M’ cm’)  =  272 (4.4 x 10),  288 (7.6 x 10).  3.4.6 Preparation of [MesP(O)—C(Phen)(Ph)] (3.3b) A THF (2 mL) solution of 3.2b (0.05 g, 0.12 mmol, M  =  27,000 g mol’) was left in air for oxidation of the phosphorus atoms. The  oxidation progress was monitored by 31 P NMR spectroscopy, and THF was added when there was significant solvent evaporation. After 1 week, a 31 P NMR spectrum of the solution showed a broad signal at 49 ppm. The solvent was allowed to evaporate in air. An off-white solid remained and was dried in a vacuum oven at 65 °C for 12 hours. Yield = 0.04 g (82 %).  References begin on page 84  Chapter Three  82  P NMR (CDCI 31 , 162 MHz): 3  49 (br); ‘H NMR (CDC1 , 400 MHz): 3  1.5 (br, 3 CH ) ; GPC-LLS (THF): M cm’)  =  31,300 g mo[’, PDI  8.5—65 (br, Ar-H), 3.0—  1.46. UV/Vis (THF):  =  max/nm  (E/M  256 (3.7 x 10), 301 (8.0 x 10).  )—C(Naph)(Ph)] (3.4a) To a THF solution of 3.2a (0.30 g, 3 3.4.7 Preparation of jMesP(BH  0.82 mmol, M  =  22,900 g mol’) was added BHySMe 2 (0.55 mL, 2 M, 1.17 mmol) at  —  78 °C.  The reaction mixture was allowed to warm slowly to room temperature. 31 P NMR spectrum of the reaction mixture showed the presence of a new broad signal the broad chemical shift of the starting material  (b3lp=  —  (&Ip  =  27, 50%) in addition to  9, 50%). The reaction mixture was  treated with more 2 SMe (0.55 mL, 2 M, 1.17 mmol) at 3 BH  —  78°C and allowed to warm slowly  to room temperature and stir overnight. After removal of solvent in vacuo, a white solid was obtained. Yield  0.26 g (83%).  P NMR (CDCI 31 , 162 MHz): 3  27 (br), -9 (br); 1 H NMR (CDCL , 400 MHz): ó 9.0—6.0 (br, Ar 3  if), 3.0—0.5 (br, CH , BH 3 ); ‘ 3 , 101 MHz): 3 C NMR (CDC1 3 CH ) 3 , GPC-LLS (THF): M  =  137—122 (br, Ar-C), 28—18 (br,  24,700 g mol’, PDI = 1.33. UV/Vis (THF):  ?max/nm  (E/M’ cm ) 1  =288 (1.Ox 10).  3.4.8 Preparation of [MesP(BH )—C(Phen)(Ph)] (3.4b) A THF solution of 3.2b (0.04 g, 0.09 3  mmol, M  =  27,000 g mo[’) was treated with 2 SMe (0.06 mL, 2 M, 0.12 mmol) at 3 BH  —  78 °C.  The reaction mixture was allowed to warm slowly to room temperature. An aliquot was removed from the reaction mixture and analyzed by 31 P NMR spectroscopy. The spectrum showed the presence of a new broad signal material  ip= 3 (ö  (&ip  =  28) in addition to the broad chemical shift of the starting  —10). The reaction mixture was treated with more BH 2 S 3 Me (0.06 mL, 2 M, 0.12  References begin on page 84  Chapter Three mmol) at  —  83  78 °C and was allowed to warm slowly to room temperature and stir overnight. After  removal of solvent in vacuo, a white solid was obtained. Yield = 0.03 g (78 %). p NMR (CDC1 31 , 122 MHz): S 28 (br); ‘H NMR (CDCI 3 , 400 MHz): 9.0—6.5 (br, Ar-H), 3.0— 3 1.0 (br, CH , BH 3 ); GPC-LLS (THF): M 3 (E/M’  cm’)  =  =  27,900 g mol’, PDI  =  1.32. UV/Vis (THF):  ?max/nm  254 (2.4 x l0), 288 (5.5 x 10), 301 (5.1 x 10).  3.4.9 General procedure for preparing solution samples for UV/Vis and fluorescence measurements Solution samples were prepared inside a glovebox, except for 3.3a, 3.3b, 3.4a, and 3.4b. The procedure for preparing a solution sample of 3.la is described in the following as an example: THF was added to 3.la (7 mg, 0.02 mmol) in a 25.0 mL volumetric flask and diluted to the mark. The volumetric flask was inverted 20 times to ensure proper mixing. Using a volumetric pipette, 1.00 mL of this solution was transferred to another 25.0 mL volumetric flask, and THF was added to dilute to the mark. Again the volumetric flask was inverted 20 times before transferring a small amount of the solution to a 1 cm quartz cuvette.  References begin on page 84  Chapter Three  84  3.5 References (1)  Mathey, F.; Nixon, J. F.; Dillon, K. B. Phosphorus: The Carbon Copy; Wiley-VCH: Weinheim, 1997.  (2)  Mathey, F. Phosphorus-Carbon Heterocyclic Chemistry. The Rise ofa New Domain; Elsevier Science: Oxford, 2001.  (3)  Smith, R. C.; Protasiewicz, J. D. J. Am. Chem. Soc. 2004, 126, 2268-2269.  (4)  Wright, V. A.; Patrick, B. 0.; Schneider, C.; Gates, D. P. J Am. Chem. Soc. 2006, 128, 8836-8844.  (5)  Tsang, C. W.; Yam, M.; Gates, D. P. J Am. Chem. Soc. 2003, 125, 1480-1481.  (6)  Honeyman, C. H.; Foucher, D. A.; Dahmen, F. Y.; Rulkens, R.; Lough, A. J.; Manners, I. Organometallics 1995, 14, 5503-55 12.  (7)  Noonan, K. J. T.; Feldscher, B.; Bates, J. I.; Kingsley, J. J.; Yam, M.; Gates, D. P. Dalton Trans. 2008, 445 1-4457.  (8)  Friedel, R. A.; Orchin, M. Ultraviolet Spectra ofAromatic Compounds; John Wiley and Sons, mc: New York, 1951.  (9)  Sathyanarayana, D. N. Electronic Absorption Spectroscopy and Related Techniques; University Press: India, 2001. Page 363.  (10)  Kiebach, T. C.; Lourens, R.; Bickeihaupt, F. J Am. Chem. Soc. 1978, 100, 4886-4888.  (11)  Bissell, R. A.; Desilva, A. P.; Gunaratne, H.  Q. N.; Lynch, P. L. M.; Maguire, G. E. M.;  McCoy, C. P.; Sandanayake, K. Top. Curr. Chem. 1993, 168, 223-264. (12)  James, T. D.; Sandanayake, K.; Iguchi, R.; Shinkai, S. J Am. Chem. Soc. 1995, 117, 8982-8987.  References begin on page 84  Chapter Three (13)  85  Kijima, H.; Takeuchi, M.; Robertson, A.; Shinkai, S.; Cooper, C.; James, T. D. Chem. Commun. 1999, 2011-2012.  (14)  McQuade, D. T.; Hegedus, A. H.; Swager, T. M. J Am. Chem. Soc. 2000, 122, 1238912390.  (15)  Gunnlaugsson, T.; Davis, A. P.; Glynn, M. Chem. Commun. 2001, 2556-2557.  (16)  Gunnlaugsson, T.; Bichell, B.; Nolan, C. Tetrahedron Lett. 2002, 43, 4989-4992.  (17)  Gunnlaugsson, T.; Lee, T. C.; Parkesh, R. Org. Biomol. Chem. 2003, 1, 3265-3267.  (18)  He, H. R.; Mortellaro, M. A.; Leiner, M. J. P.; Young, S. T.; Fraatz, R. J.; Tusa, J. K. Anal. Chem. 2003, 75, 549-555.  (19)  Nolan, E. M.; Lippard, S. J. J Am. Chem. Soc. 2003, 125, 14270-14271.  (20)  Gunnlaugsson, T.; Au, H. D. P.; Glynn, M.; Kruger, P. E.; Hussey, G. M.; Pfeffer, F. M.; dos Santos, C. M. G.; Tierney, J. J. Fluoresc. 2005, 15, 287-299.  (21)  Fan, L. J.; Zhang, Y.; Jones, W. E. Macromolecules 2005, 38, 2844-2849.  (22)  Tal, S.; Sahman, H.; Abraham, Y.; Botoshansky, M.; Eichen, Y. Chem.—Eur. J. 2006, 12, 4858-4864.  (23)  Kulatilleke, C. P.; de Silva, S. A.; Eliav, Y. Polyhedron 2006, 25, 2593-2596.  (24)  Fan, L. J.; Jones, W. E. J Am. Chem. Soc. 2006, 128, 6784-6785.  (25)  Fan, L. J.; Jones, W. E. J Phys. Chem. B 2006, 110, 7777-7782.  (26)  Schwarze, T.; Muller, H.; Dosche, C.; Klamroth, T.; Mickler, W.; Kelling, A.; Lohmannsroben, H. G.; Saalfrank, P.; Holdt, H. J. Angew. Chem.,  mt.  Ed. 2007, 46,  1671-1674. (27)  Skoog, D. A.; Holler, F. J.; Nieman, T. A. Principles ofinstrumentalAnalysis; 5th ed.; Saunders College Publishing: Orlando, 1998. Page 365.  References begin on page 84  86  Chapter Four Radical Copolymerization of P=C and CC Bonds: Reactivity Ratios of Phosphaalkene-Styrene Copolymers*  4.1 Introduction Although synthetically challenging, the incorporation of inorganic functionalities into macromolecules is attractive because it often leads to materials with unique properties that 2 Lately, the incorporation of phosphorus atoms cannot be attained using organic counterparts.” into polymers has captured considerable attention and resulted in materials with interesting properties and important potential applications, such as chemosensors, polymer-based light emitting diodes (PLED5), and flame-retardant materials. ’ In 2003, the Gates group reported the 3 2 (PA) (Mes addition polymerization of a phosphaalkene, MesP=CPh  2,4,6-trimethyiphenyl) to  4 This is the first addition polymerization of a heavy-element afford poly(methylenephosphine).’ multiple bond and represents an important step forward in the field of inorganic polymers. 15 Our group Previously, addition polymerization had primarily been limited to olefins. subsequently reported the copolymerization of PA with styrene (Sty) to afford new hybrid inorganic-organic copolymers.’ 7 The copolymerization can be achieved via a radical method ” 6 using the radical initiator 1,1 ‘-azobis(cyclohexanecarbonitrile) (VAZO 88) to yield a random (PMP-co-PS),’ or the reaction can copolymer poly(methylenephosphine)-co-polystyrene 6 7 The focus of this chapter proceed via an anionic route using n-BuLi to give block copolymers.’ will be on the random copolymer PMP-co-PS. This hybrid inorganic-organic macromolecule is particularly attractive for its potential application in polymer-supported catalysis. 16 Our group *A version of this chapter will be submitted for publication. Chun, C. P. and Gates, D. P. Radical Copolymerization of P=C and C=C Bonds: Reactivity Ratios of Phosphaalkene-Styrene Copolymers.  Chapter Four  87  (dba) (dba = 2 [Pd ] showed that PMP-co-PS could be used as a ligand in the presence of 3 dibenzylideneacetone) and CsF to execute a Suzuki cross-coupling of bromobenzene and phenylboronic acid to form biphenyl with 90% yield.’ 6 On the other hand, when the cross(dba) 2 [Pd ] , CsF and a homopolymer of PA, the yield was coupling reaction was attempted using 3 (dba) and CsF (yield = 25%). 2 [Pd ] the same as that in the reaction using only 3 To better understand the microstructure of PMP-co-PS, which has not been reported, we decided to further examine the PA/Sty copolymerization system at 100 °C using VAZO 88 as the radical initiator (Scheme 4.1). The elucidation of the PMP-co-PS microstructure would require the determination of the reactivity ratios of PA  (rpA)  and of Sty (rs). Reactivity ratios describe  the relative tendency of the growing chain to add to a particular monomer. More specifically, reactivity ratios are defined as a ratio of rate constants as shown in Scheme 4.2 using  rpA  and rs  as examples. Starting in the 1 940s, reactivity ratios have played an important role for the copolymerization of olefins to develop commercial products.’ 8 They are crucial synthetic parameters in predicting predilections of a specific monomer to copolymerize with certain other 20 To that end, we believe that ’ 19 monomers.  rpA  and r , may have a long term impact to the 5  sensing work discussed in Chapters 2 and 3 if chemosensors could be realized by random copolymers derived from phosphaalkenes. It may be possible that a sensory behavior does not necessitate phosphorus at every other atomic position in the main chain. ,Ph MePh  PA  VAZO88 +  Ph/t  \  //  100C  Sty  PMP-co-PS  Scheme 4.1  References begin on page 106  Chapter Four  88  “PA  +  PA  u111PA.  +  Sty  kpp  kp  ‘‘PA-PA  “PA-Sty  “Sty  +  Sty  +  PA  kss  ksp  ““Sty-Sty  ““Sty-PA  5 k rpA=  rSty=  5 kp  sp  Scheme 4.2  Herein we describe our investigation on the reactivity ratios of PA and of Sty in the PMP co-PS copolymerization system by following an adaptation of the Tidwell-Mortimer experimental approach, ’ illustrated in Chart 4.1. The first step requires data, such as copolymer 2 compositions, from several copolymerization experiments over a broad range of monomer feed ratios. These data are necessary for the preliminary estimation of the r values by one or more 22 and the Mayo-Lewis intersection method linear methods. The Fineman-Ross linearization 23 were used in this study. The second step of the experimental approach requires the input of the preliminary r values for the application of the heuristic rules introduced by Tidwell and Mortimer. These rules approximate the optimal feed compositions for further copolymerization experiments. Lastly, further experiments are performed at the optimal feed compositions, and the data are fitted to the copolymer composition equation (eq I) by nonlinear least squares regression to provide the best estimates of the reactivity ratios. =  rMPA  +  MpAMs  (I)  + MPAMSIY  where:  mmonomer represents the molar fraction of PA or Sty in the copolymer; Mmonomer represents the molar fraction of PA or Sty in the monomer feed.  Based on the best estimates of rpA and  the microstructure of PMP-co-PS was examined and  Q-e reactivity parameters of PA were computed.  References begin on page 106  Chapter Four  89  Chart 4.1. Flowchart illustrating the Tidwell-Mortimer approach to determining reactivity ratios. data from copolymerization experiments  Step I Preliminary estimation of rvalues by linear methods Fineman-Ross Linearization Mayo-Lewis Intersection Method -  -  preliminary rvalues  Step 2 Application of Tidwell and Mortimers heuristic rules using preliminary rvalues to determine optimal feed compositions for further copolymerization experiments  optimal feed compositions  V  copolymerization experiments based on optimal feed compositions and obtain data  Step 3 Determination of rvalues by nonlinear least squares fitting of data to the copolymer composition equation  *  best estimates of rvalues  4.2 Results and Discussion 4.2.1 Analysis of Copolymer Composition by Inverse Gated Proton Decoupled ‘ C NMR 3 Spectroscopy  Since our investigation of reactivity ratios required analysis of many copolymer samples, a simple and rapid method to analyze copolymer compositions was desired. NMR spectroscopy is commonly used for the analysis of copolymer compositions. ’ Unfortunately, ‘H NMR 243 References begin on page 106  Chapter Four  90  spectroscopy was not a feasible option in our investigation because the technique could not differentiate changes in the copolymer composition of PMP-co-PS. Thus, we considered using another technique, ‘ C NMR spectroscopy, which is a common method for the analysis of 3 22 2527 microstructures. 3 9 Since T,s for macromolecules are 0 copolymer compositions and ’ usually very short (10-s to is), 33 inverse gated proton decoupled ‘ C NMR spectroscopy may be a 3 viable method to measure compositions of PMP-co-PS in a quantitative fashion. In this method, the decoupler is off during the relaxation delay and on during acquisition, thereby eliminating the Nuclear Overhauser Effect from the protons, resulting in more quantitative integrations than the typical ‘ C {H} experiment. To further ensure that the ‘ 3 C NMR experiment yields results as 3 quantitative as possible, a 90° pulse can be used. A ‘ C NMR spectrum of a sample of PMP-co 3 PS, obtained via the method described above, is shown in Figure 4.1. The signals for the aromatic carbons resonate between 155 ppm and 120 ppm, whereas the signals for the methyl carbons resonate around 25 ppm. To evaluate the accuracy of inverse gated proton decoupled ‘ C NMR spectroscopy as a 3 method to analyze PMP-co-PS samples, compositions of four different samples of PMP-co-PS,  /  I I  Ph\  I P—c I I  /H  H  \H  Ph  i/i I  I I/I c—c 1/ I I  \ MesPh/x  Y *  Ar-C  backbone Cs \ -CH 3  PPm18O 160• 140120  100  80  60  20  0  Figure 4.1. Inverse gated proton decoupled ‘ , 101 MHz) of a PMP-co 3 C NMR spectrum (CDc1 3 (*) PS. CDC1 3 References begin on page 106  Chapter Four  91  prepared under conditions specified in Table 4.1, were estimated using the ‘ C NMR 3 spectroscopic technique described above. These estimations were compared to compositions analyzed by elemental analysis (EA) which include phosphorus analysis, which is a service available only outside of our department (see Table 4.1). The copolymer compositions, determined by both methods, agreed within 0.05. The estimations by 31 C NMR and EA for entry 3 differed by only 0.01. The maximum difference was observed in entry 2 in which the estimations differed by 0.05. Encouraged by these results and the convenience of the ‘ C NMR 3 spectroscopic technique to deliver results rapidly, 13 C NMR spectroscopy with inverse gated proton decoupling was chosen as the method for determining PMP-co-PS compositions.  Table 4.1. Comparison of copolymer compositions measured by inverse gated proton decoupled 1 3C NMR spectroscopy and elemental analyses. monomer feed copolymer composition GPC  EAC entry  t  (h)  MPA  Msty  mpA  ms  mpA  5 m  (10 g moi’)  PDI  1  2  0.2  0.8  0.55  0.45  0.57  0.43  14.7  1.17  2  10  0.4  0.6  0.36  0.64  0.41  0.59  9.6  1.20  3  16  0.4  0.6  0.44  0.56  0.43  0.57  8.8  1.29  4  24  0.4  0.6  0.35  0.65  0.38  0.62  10.4  1.25  a The duration of each copolymerization experiment conducted at 100 °C is represented by b See Experimental section. m PA  (FWSY )(EA )(0.0 1) =  100xAW  —(FWPA  —FWStY)(%PEA)  and m 8ly  =  t.  1—  FW is the molar mass of styrene; where: 51 %PEA is the percent of phosphorus detected by elemental analysis; A Wp is the atomic mass of phosphorus; FWPA is the molar mass of phosphaalkene PA.  References begin on page 106  ______ ___  Chapter Four  92  4.2.2 Experimental Design and Preliminary Estimation of rpA and r 5  All copolymerization experiments were performed by heating PA and  Sty in a vacuum-  sealed glass tube at 100 °C. It is critical to minimize monomer drift in studies of reactivity ratios, thus we aimed to carry all experiments to low monomer conversion (X  10%). To determine the  number of hours of heating at 100 °C (t) that would minimize X, several copolymerization experiments were performed with variable t. In these experiments, we used a monomer feed ratio of MPA= 0.40 and M 51  =  0.60. Figure 4.2 plots the conversion of each copolymerization.  Monomer conversion (X) was calculated based on the number of moles of each monomer in the copolymer divided by the number of moles of each monomer in the monomer feed. As illustrated in the plot, longer heating durations led to higher monomer conversions. Allowing a copolymerization experiment to proceed at 100 °C for 2 h resulted in XPA  =  3% and X 5  =  2%.*  According to Figure 4.2, t equal to 4 h also resulted in monomer conversions below 10%. However, t of 2 h was chosen to keep monomer conversion to a minimum in order to reach more reliable results in our later calculations of rpA and rg. 50 45 40 35 30  X (%)  25 20 15  PA  10  •Sty  5  U U  0  2  4  6  8  10  12  14  16  18  20  22  24  t (h)  Figure 4.2. Monomer conversions of copolymerization experiments carried through different t. = 0.60. Conversion was calculated by Xmonomer = (moles of monomer in the MPA = 0.40; copolymer)/(moles of monomer in the monomer feed). *  Heating a reaction mixture at 100°C for 1 hour (i.e. t = 1 h) led to very little copolymer formation thereby rendering product isolation and analysis difficult. References begin on page 106  Chapter Four  93  To obtain data for the first step in calculating reactivity ratios (Chart 4.1), eight different copolymerization experiments, with heating for 2 h, over a range of monomer feed ratios were conducted. Table 4.2 summarizes the data from the eight experiments. According to the data, as the monomer feed of PA (i.e. (i.e.  mpA)  MPA)  increased, the mole fraction of PA in the isolated copolymer  increased. This is logical and the same pattern is observed for Sty. The copolymers in  Table 4.2 have M values ranging from 7,700 g mol’ to 16,200 g mol’. In general, copolymers with higher M values were found to have more PA in their compositions; this makes sense since the molecular weight of PA is greater than that of Sty. The GPC traces of the copolymer samples were unimodal, which gave support to the presence of PMP-co-PS, and not a polyblend of homopolymers and copolymers. The PDI values of the copolymers range between 1.11 and 1.20.  Table 4.2. Summary of copolymerization experimental data.  monomer feed  PMP-co-PS composition  GPC  monomer conversion a  -“PA  v a -“Sty  v  1V1  mpA  msty  (%)  (%)  0.80  0.36  0.64  5  2  8.0  1.11  0.20  0.80  0.39  0.61  3  1  7.7  1.17  3  0.40  0.60  0.44  0.56  4  3  10.5  1.13  4  0.40  0.60  0.44  0.56  2  2  11.6  1.15  5  0.60  0.40  0.46  0.54  4  8  14.1  1.16  6  0.60  0.40  0.52  0.48  4  6  11.4  1.18  7  0.80  0.20  0.55  0.45  3  10  14.7  1.17  8  0.80  0.20  0.56  0.44  3  10  16.2  1.20  entry  MPA  1  0.20  2  a Conversion is calculated by Xmonomer monomer in the monomer feed).  (1  g  moF’)  PDI  (moles of monomer in the copolymer)/(moles of  References begin on page 106  Chapter Four  94  Following the first step in the Tidwell-Mortimer approach (Chart 4.l),21 the Fineman Ross linearization 22 was employed to obtain preliminary estimates of rpA and r . In this method, 5 the copolymer composition equation (eq I) is rearranged to a linear form (eq II): G  where: G=  F  =  (II)  FrPA + r 1  MPA(mSIY —mPA) 4 M mp 1  —  mYMPA  mPA ‘SIy  Hence by plotting G versus F, the line of best fit has a slope represented by  rpA  and a y-intercept  represented by rs. Figure 4.3 shows the Fineman-Ross plot generated from the data presented in Table 4.2. From the equation of the regression line (R-squared values obtained are  rpA  =  0.07±0.02 and rs  =  0.9 172), the reactivity ratio  =  O.2l±O.l2. The results of the Fineman-Ross  linearization are tabulated in Table 4.3, which summarizes the r values calculated in this study.  0.4 0.2 0.0 -0.2  G -0.4 r,  rPA  -0.6  G  -0.8  =  0.07F 0.21 -  -1.0 -15  -13  -11  -9  -7  -5  -3  -1  1  F  Figure 4.3. Fineman-Ross plot of G versus F for PA/Sty copolymerization experiments. The linear least-squares function (G = 0.07F 0.21) has an R-squared value of 0.9 172. —  The errors reported are the 95% confidence intervals that were calculated based on the standard deviation of the slope and y-intercept of the regression function shown in the Fineman-Ross plot. References begin on page 106  Chapter Four  95  Table 4.3. Approximation of rpA and  Method  rpA  Fineman-Ross Linearizationa  0.07±0.02  0.21±0.12  Mayo-Lewis Intersection Methodb  0.06±0.18  0.17±0.04  Average of Preliminary Estimates  0.065  0.19  0.11±0.01  0.24±0. 12  Nonlinear Least-Squares Regressiona a  Errors are the 95% confidence intervals associated with the respective r value. Errors are determined the dividing the difference between the maximum and minimum values of the intersection by two. b  For comparison, we also estimated the r values by the Mayo-Lewis intersection method. 23 In this method, the copolymer composition equation (eq I) is rearranged to eq III: rPA  where:  =  =  SrSI}, +  I  (III)  m]AMS,Y  mS(YMPA  1= MPA  Each copolymerization experiment is represented by a straight line with a slope and y-intercept , 5 defined by S and J, respectively, on a r  rpA  plane. This is shown in Figure 4.4 using the data  summarized in Table 4.2. There are eight straight lines, one for each copolymerization experiment. Lines representing entries 3 and 4 overlap. The r values, obtained by the intersection method, are the coordinates of the centroid in the area of common intersection shown in the plot. Therefore by this method,  rpA  =  0.06±0.18 and r 5  =  0.17±0.04 (Table 4.3). The error in  rpA is  quite large, which is typical of r values calculated by this method.  The errors are determined by dividing the difference between the maximum and minimum values of the intersection area by two. References begin on page 106  Chapter Four  96  1.0 0.8 0.6 0.4 0.2 rPA  0.0 -0.2 -0.4 -0.6 -0 8 -1.0 0  0.05  0.10 0.15  0.20 0.25  0.30  0.35  0.40 0.45  0.50  Figure 4.4. PA/Sty copolymerization data plotted according to the Mayo-Lewis intersection method. (rs, rpA) = (0.17, 0.06) are the coordinates of the centroid in the area of common intersection among all the lines.  The averages of the reactivity ratios calculated from both methods (i.e. Fineman-Ross linearization and Mayo-Lewis intersection method) were taken as the preliminary estimates, giving  rpA  =  5 0.065 and r  =  0.19 (Table 4.3). These r values were used in the second step of the  Tidwell-Mortimer approach (see Chart 4.1) which is described in the next section.  4.2.3 Application of Heuristic Rules  It has been shown and recognized that not all experimental conditions serve equally well in the determination of reactivity ratios and there are some conditions that reveal more 2 For this reason, Tidwell and Mortimer developed heuristic ’ 9 information about the r values.’ rules (eq IV and eq V) that approximate the two sets of monomer feed conditions, referred to as the optimal monomer feed compositions, that lead to more accurate estimates of r values. ’ 2  References begin on page 106  Chapter Four  97  M PA ‘  (IV) +  2  (V)  2+ rPA  where:  is the optimal monomer feed of PA for the first experiment; MPA” is the optimal monomer feed of PA for the second experiment; and rpA are the preliminary estimates obtained by linear approximations MPA’  Given the preliminary estimates  (rpA  0.065 and rs  0.19), the second step of the  experimental approach involved the application of heuristic rules (eq IV and eq V). This resulted in the following set of conditions for further work in our study: 1)  MPA  0.09, Ms  2) MPA  0.97, Ms  =  0.91; and 0.03.  Two additional runs were conducted at each of these conditions and their data are summarized in Table 4.4.  Table 4.4. Summary of experimental data from copolymerizations according to optimal monomer feed compositions.  monomer feed  PMP-co-PS composition  monomer conversion v a -“PA  -‘i-Sty  v-  GPC a  JVI  entry  MPA  5 M  mpA  5 m  (%)  (%)  (10 gmol’)  PDI  1  0.09  0.91  0.24  0.76  10  3  7.8  1.07  2  0.09  0.91  0.20  0.80  9  3  7.0  1.08  3  0.97  0.03  0.82  0.18  2  10  13.4  1.16  4  0.97  0.03  0.85  0.15  2  10  16.7  1.17  a Conversion is calculated by Xmonomer monomer in the monomer feed).  =  (moles of monomer in the copolymer)/(moles of  References begin on page 106  Chapter Four  98  4.2.4 Determination of rpA and rsty by Nonlinear Least Squares Regression  To provide the best estimates of rpA and rst , and minimize the error associated with the 3 solutions, nonlinear least squares regression (Step 3, Chart 4.1) was performed on both sets of data: the data presented in Table 4.2 and the data found in Table 4.4. A substitution was made to simplify the curve-fitting procedure. Since M 5  =  1  —  the right hand side of the copolymer  MPA,  composition equation (eq I) was expressed in terms of one variable as shown in eq VI: PA 1  =  rPAMPA  +  MPA(l  r(Y(lMPA)  Using the data specified, a plot of mpA/ms versus  —  MPA)  (VI)  +MPA(l—MPA) MPA was  constructed (Figure 4.5). A line of  best fit, following the form of the eq VI, was obtained by using a nonlinear least squares curvefitting tool in the MATLAB software. This function correlates well with the data points (RMSE =  0.1358). The plot shows that when MPA is greater than 0.8, there is a drastic increase of PA in  the copolymer composition. From the equation of this line (shown in Figure 4.5), the best estimates of the reactivity ratios are rpA  =  0.11±0.01 and r ,= 0.24±0.12 (Table 4.3). 8  6 rPA  4 (1 + Mp —  —  MPA)  MPA  Figure 4.5. Nonlinear least squares curving fitting of copolymerization data. RMSE §  0.1353.  The errors are the 95% confidence intervals associated with the respective r value. References begin on page 106  Chapter Four  99  4.2.5 Q-e values of PA and the Microstructure of PMP-co-PS To compare the reactivity of PA to the reactivity of other monomers, it would be helpful to first assign reactivity parameters to PA following the well-known Aifrey-Price Q-e scheme. 34 According to this framework, the  Q value describes the specific reactivity of the monomer, and  the e value represents the polarity of the radical adduct. Styrene was chosen as a universal standard for this scheme and hence was arbitrarily assigned the —0.8. To determine the  Q value of 1.0 and an e value of  Q and e values of PA, we used the Alfrey-Price formulas: rPArstY = exp[—(en,ononeri  rmonomer I  monomerl  —  —  exPL  enlonomer2)l  (VII)  e 1 ‘ monomerl  VIII  —  e monomerl  emoflomer2  monomer 2  Using eq VII, eq VIII, and the Q-e values of styrene, we arrived to QPA 1.1. The  QPA  0.9 and epA  =  value being less than the Qsty value is consistent with our observations of a lower  reactivity of PA when compared to the reactivity of Sty during polymerization. The lower reactivity of the PA monomer can be attributed to a higher degree of conjugation in PA compared to Sty thus allowing for greater radical stabilization of the PA radical adduct. It has been demonstrated that monomers with e values of opposite signs, which signifies opposite polarities, have a tendency to alternate upon ’ 9 copolymerization.’ 3 5 Price rationalized this 6 behavior by explaining that a radical species with a negative character exhibits a preference for a monomer with a positively charged double bond and vice versa. 36 The fact that PA and Sty ’ 35 have e values of opposite signs (es  =  —0.8; epA  =  1.1) suggests that the PAJSty system would  exhibit an alternating behavior upon copolymerization. This suggestion coincides with our expectation based on the r values. Referring back to the definition of rpA and r 5 (Scheme 4.2), rpA  =  =  0.11 indicates that the radical of a growing chain with a terminal PA unit is more  likely to attack a Sty monomer. Similarly,  =  =  0.24 suggests that the radical on a  References begin on page 106  Chapter Four  100  growing chain with a terminal Sty unit is more likely to add to a PA monomer. As a result, this should give rise to alternating PA and Sty monomers along the copolymer chain. In addition to being important in kinetic aspects of copolymerization and in the determination of Q-e reactivity parameters, reactivity ratios are also key parameters to revealing monomer distribution and heterogeneity in the main chain. The microstructure of a copolymer can be deduced by formulas that are well-known and found in general polymer science ° The average sequence length (1) of PA or Sty units linked consecutively is defined 2 ’ 9 textbooks.’ by eq IX: 20 1 monomerl  — —  1 + rmonomerl  Mmonomeri lvi  ix  monomer 2  Using eq IX, we computed the mean sequence length of consecutive PA and Sty monomers in PMP-co-PS samples synthesized from various monomer feed ratios in this study (see Table 4.5). In entries 3—5 of Table 4.5, the copolymers have ‘PA and ‘sty values slightly greater than one unit, therefore these copolymers most likely consist of alternating PA and Sty units. In the case of entry 2, the average sequence length of consecutive PA units is about 1 unit, and that of Sty is about 2 units. This would render a copolymer with a backbone of mostly repeating PA-Sty-Sty triads. In copolymers prepared from a large excess of one monomer in the monomer feed (i.e. entries 1 and 6), there is a tendency to form blocks of the monomer in excess. Inevitably, the number of monomers in a sequence is related to the number of sequences in a given length of a copolymer chain. For example, longer sequences results in fewer sequences in a given chain length. The average number of sequences per 100 units, also known as the run number (R), can be obtained via eq X: 20 R=  200  (X)  ‘PA + ‘Sty  References begin on page 106  Chapter Four  101  Table 4.5. Average sequence length of monomers units (imonomer) and run number (R) of PMP co-PS copolymers prepared from various monomer feed ratios in this study. t = 2 h. entry 1  MPA  0.09  2  ‘PA  Sty 1  0.91  1.01  3.43  R 45.07  0.20  0.80  1.03  1.96  66.95  3  0.40  0.60  1.07  1.36  82.19  4  0.60  0.40  1.17  1.16  86.02  5  0.80  0.20  1.44  1.06  80.00  6  0.97  0.03  4.56  1.01  35.94  Not surprisingly, copolymers of PMP-co-PS prepared from a large excess of one monomer have fewer sequences in a given chain length, which appears to be the case for entries 1 (R  45.07) and 6 (R  =  35.94) in Table 4.5. In other instances, PMP-co-PS contains about 67 to  86 sequences per 100 units, suggesting a large degree of heterogeneity along the copolymer backbone. From our study, it is apparent that PMP-co-PS generally has a highly alternating PA I Sty microstructure unless prepared under monomer feed conditions of greater than 8:2. An alternating pattern leads to more open space around the phosphorus atoms in comparison to the phosphorus atoms in a homopolymer of PA. This is because phosphorus atoms in the copolymer would be preceded by CHPh moieties whereas the phosphorus atoms in the latter case would be preceded by CPh 2 moieties. Returning to the observations from previously reported Suzuki cross-coupling reactions using PMP-co-PS,’ 6 the open space probably facilitated the coordination of phosphorus atoms in PMP-co-PS to Pd thereby promoting coupling activity.  References begin on page 106  Chapter Four  102  4.3 Summary  In conclusion, we calculated the reactivity ratios of PA and Sty via nonlinear least squares regression and the values obtained are  rpA  =  0.11±0.01 and rs  =  0.24±0.12. These r  values led us to assign Q-e reactivity parameters to PA, which will enable reactivity comparison of PA to other monomers, and also evaluate their compatibility for copolymerization. The PMP co-PS microstructure analysis revealed that under feed compositions of less than 8:2 an alternating pattern predominates along the copolymer chain, which allows for more open space around the phosphorus atoms in comparison to the more hindered spatial environments around the phosphorus centres in poly(methylenephosphine). This insight provides an explanation to our previously reported success of Suzuki cross-coupling reactions using PMP-co-PS.’ 6 We have demonstrated the utility of reactivity ratios in modeling compositional heterogeneity and monomer sequence distribution along the backbone of PMP-co-PS. The architectures of PMP co-PS ultimately influence the behavior and physical attributes of the resulting material, which will be investigated in future studies. Results from this study, particularly the Q-e values of PA, will undoubtedly play a crucial role in the future design of copolymers composed of PA and in the evaluation of the specific applications for these tailored materials.  4.4 Experimental Section  General procedures. All manipulations of air and/or water sensitive compounds were performed under a nitrogen atmosphere using standard Schlenk techniques or in an Innovative Technology Inc. glovebox. Hexanes and dichloromethane were deoxygenated with nitrogen and dried by passing through a column containing activated alumina. THF was distilled from sodium/benzophenone ketyl. Styrene (Aldrich) was stirred with CaR 2 for 24 h, distilled twice  References begin on page 106  Chapter Four  103  under partial vacuum and used immediately after distillation. 1,1’azobis(cyclohexanecarbonitrile) (VAZO 88) (Aldrich) was recrystallized twice from ethanol MesPz=CPh was prepared following (99%) and dried for at least 24 h under vacuum. Monomer 2 37 previously reported procedures. Equipment. 1 H, 31 P NMR and ‘ C spectra were recorded at 298 K on Bruker Avance 300 MHz 3  or 400 MHz spectrometers. Chemical shifts are reported relative to 85% 4 P0 as an external 3 H standard (5= 0.0 for 31 P) and residual CHC1 3 (5= 7.26 for ‘H and 77.16 for ‘ C). Samples for 3 C NMR spectroscopy were prepared by dissolving 40 mg of PMP-co-PS samples in 0.4 mL 3 ‘ . For ‘ 3 CDC1 C experiments with inverse gated proton decoupling, pulse program zgig was 3 used. The relaxation delay (dl) was set to 3 s, and approximately 2048 scans were used for each experiment.** Molecular weights were determined by triple detection GPC using a Waters liquid chromatograph equipped with a Waters 515 HPLC pump, Waters 717 plus autosampler, Waters Styragel columns (4.6x300mm), HR2 x 2 and HR4, Waters 2410 differential refractometer (refractive index detector, ? =  940 urn), Wyatt tristar miniDAWN (laser light scattering detector,  690 nm) and a Wyatt ViscoStar viscometer. A flow rate of 0.5 mL min 1 was used and  samples were dissolved in THF (ca. 2 mg/mL). The dn/dc for each sample was determined using the software. Elemental analyses were performed by the Canadian Microanalytical Service Ltd. Calculations and plots for preliminary estimates of the reactivity ratios were obtained using Microsoft Excel. Nonlinear least squares regression was performed using MATLAB V.7.0.4 R14.  **  Increasing the relaxation delay to 1 Os and/or the number of scans does not change the relative integration of signals in the spectra, and therefore did not affect the estimations of copolymer compositions. References begin on page 106  Chapter Four  104  4.4.1 General procedure for synthesis of PMP-co-PS. The experimental procedure for PMP co-PS (entry 1, Table 4.2) is described in the following as an example: A pyrex tube was charged with phosphaalkene (1.14 g, 3.6 mmol), VAZO 88 (0.044 g, 0.18 mmol) and styrene (1.55 g, 14.4 mmol). The tube was flame sealed in vacuo, then heated at 100 °C in an oven equipped with a rocking tray. After 2 hours of being heated, the tube was broken. Precipitation of the copolymer was achieved by adding hexanes (100 mL) to a viscous solution of the tube’s contents dissolved in THF or 2 C1 Precipitation was repeated three times. The product, a white CH . powder, was redissolved in THF (3 mL), then filtered through glass wool into a small vial. The solvent was allowed to evaporate, leaving the copolymer as a white solid, which was then dried in a vacuum oven at 60 °C for 24 hours. Yield  =  0.08 g (3%).  P NMR (CDC1 31 , 162 MHz): ô = 4, —9 (br). ‘H NMR (CDC1 3 , 400 MHz): ô 3 II), 2.5  —  1.0 (CH , CH 3 , Cl]). ‘ 2 C NMR (CDC1 3 , 101 MHz): 5 3  (br, CR, CR ), 25 (br, CH 2 ). GPC-LLS (THF): M 3  =  7.5  —  6.3 (br, Ar  155— 120 (br, Ar-C), 50,35  8.0 x iü g moF’, PDI  =  1.11.  4.4.2 General procedure for processing 13 C NMR spectra and determining copolymer composition. The raw data, obtained via the inverse gated proton decoupled ‘ C NMR technique 3 described above, were processed using the Bruker software, XWINNMR. A line-broadening setting of 25 was used, the spectrum was manually phased in zero-order and first-order, and a baseline correction was applied. The broad signals for the aromatic carbons and the methyl carbons were integrated. Each integral was phased and their values were used to calculate the copolymer composition according to the following equations:  References begin on page 106  Chapter Four  105  600CMe  =  mPA  where:  3  —  12 CM  and m =1—rn PA  CMe represent integration value of the chemical shift assigned to methyl carbons; CAr represent integration value of the chemical shift assigned to aryl carbons  References begin on page 106  Chapter Four  106  4.5 References (1)  Mark, J. E.; Alicock, H. R.; West, R. Inorganic Polymers; 2nd ed.; Oxford University Press, 2005.  (2)  Manners, I. J Polym. Sci., Part A: Polym Chem. 2002, 40, 179-191.  (3)  McWilliams, A. R.; Dorn, H.; Manners, I. Top. Curr. Chem. 2002, 220, 141-167.  (4)  Hay, C.; Fischmeister, C.; Hissler, M.; Toupet, L.; Réau, R. Angew. Chem.,  mt. Ed.  2000,  39, 1812-1815. (5)  Hissler, M.; Dyer, P. W.; Réau, R. Coord. Chem. Rev. 2003, 244, 1-44.  (6)  Hissler, M.; Dyer, P. W.; Réau, R. Top. Curr. Chem. 2005, 250, 127-163.  (7)  Sebastian, M.; Hissler, M.; Fave, C.; Rault-Berthelot, J.; Odin, C.; Réau, R. Angew. Chem.,  mt.  Ed. 2006, 45, 6152-6155.  (8)  Baumgartner, T.; Réau, R. Chem. Rev. 2006, 106, 468 1-4727.  (9)  Hobbs, M. G.; Baumgartner, T. Eur. I Inorg. Chem. 2007, 3611-3628.  (10)  Durben, S.; Dienes, Y.; Baumgartner, T. Org. Lett. 2006, 8, 5893-5896.  (11)  Crassous, J.; Réau, R. Dalton Trans. 2008, 6865-6876.  (12)  Morisaki, Y.; Aiki, Y.; Chujo, Y. Macromolecules 2003, 36, 2594-2597.  (13)  Morisaki, Y.; Ouchi, Y.; Tsurui, K.; Chujo, Y. I Polym. Sci., Part A: Polym Chem. 2007, 45, 866-872.  (14)  Tsang, C. W.; Yam, M.; Gates, D. P. 1 Am. Chem. Soc. 2003, 125, 1480-1481.  (15)  Odian, G. Principles ofPolymerization; 3rd ed.; Wiley-Interscience: New York, 1991.  (16)  Tsang, C. W.; Baharloo, B.; Riendi, D.; Yam, M.; Gates, D. P. Angew. Chem.,  mt.  Ed.  2004, 43, 5682-5685. (17)  Noonan, K. J. T.; Gates, D. P. Angew. Chem.,  mt.  Ed. 2006, 45, 7271-7274.  References begin on page 106  Chapter Four (18)  107  Aifrey, T.; Bohrer, J. J.; Mark, H. Copolymerization; Interscience Publishers, Inc.: New York, 1952. Chapter 1.  (19)  Aifrey, T.; Bohrer, J. J.; Mark, H. Copolymerization; Interscience Publishers, Inc.: New York, 1952.  (20)  Alicock, H. R.; Lampe, F. W.; Mark, J. E. Contemporary Polymer Chemistry, 3rd ed.; Prentice Hall: New Jersey, 2003.  (21)  Tidwell, P. W.; Mortimer, G. A. I Polym. Sci., Part A. Gen. Pap. 1965, 3, 369-387.  (22)  Fineman, M.; Ross, S. D. I Polymer Sci. 1950, 5, 259-262.  (23)  Mayo, F. R.; Lewis, F. M. J. Am. Chem. Soc. 1944, 66, 1594-1601.  (24)  Brar, A. S.; Hooda, S.; Goyal, A. K. I Mol. Struct. 2007, 828, 25-37.  (25)  Brar, A. S.; Charan, S. I Appl. Polym. Sci. 1994, 51, 669-674.  (26)  Cheetham, P. F.; Huckerby, T. N.; Tabner, B. J. Eur. Polym. 1 1994, 30, 581-587.  (27)  Corno, C.; Roggero, A.; Salvatori, T.; Mazzei, A. Eur. Polym. I 1977, 13, 77-82.  (28)  Duc, S.; Petit, A. Polymer 1999, 40, 589-597.  (29)  Gan, L. M.; Lee, K. C.; Chew, C. H.; Ng, S. C.; Gan, L. H. Macromolecules 1994, 27, 6335-6340.  (30)  Pazhanisamy, P.; Sulochana, P.; Anwaruddin,  Q.; Ariff, M. I Polym. Sci. Part A: Polym.  Chem. 1997, 35, 193-195. (31)  Shaaban, A. F.; Khalil, A. A.; Messiha, N. N. I Appi. Polym. Sci. 1989, 37, 205 1-2058.  (32)  Brar, A. S.; Dutta, K. Macromol. Chem. Phys. 1998, 199, 2005-20 15.  (33)  Abraham, R. J.; Loftus, P. Proton and Carbon-13 NMR Spectroscopy: An Integrated Approach; Heydon & Son Ltd: London, 1978.  (34)  Aifrey, T.; Price, C. C. I Polymer Sd. 1947, 2, 101-106.  References begin on page 106  Chapter Four  108  (35)  Price, C. C. J. Polymer Sci. 1946, 1, 83-89.  (36)  Price, C. C. J. Polymer Sci. 1948, 3, 772-775.  (37)  Becker, G.; Uhi, W.; Wessely, H. J. Z. Anorg. Aug. Chem. 1981, 479, 41-56.  References begin on page 106  109  Chapter Five Overall Conclusions and Future Work  5.1 Summary of Thesis Work Before I joined the Gates lab, former members had discovered the first addition polymerization of a phosphaalkene (5.1) to afford poly(methylenephosphine) (5.2).’ This can be achieved via a radical route using 1,1’-azobis(cyclohexanecarbonitrile) (VAZO 88), or via an anionic approach using an anionic initiator such as n-BuLi or MeLi. (Scheme 10% VAZO 88  Ph MePh  f  5.1).12  Mes= Phi  or2%nuLi 5.2  Scheme 5.1 It has also been demonstrated by previous members of the Gates group that the phosphine centres in 5.2 can be chemically modified via oxidation reactions,’ or coordination to Lewis 3 or transition metals. acids 4 One of the major objectives in this thesis was to synthesize new poly(methylenephosphine)s that would manifest fluorescence upon chemical modification. We have now successfully prepared new phosphaalkenes MesPC(Naph)(Ph) (Naph  =  1-  naphthyl) (5.3a), MesP=C(Phen)(Ph) (Phen = 9-phenanthrenyl) (5.3b), and MesP=C(C S)(Ph) 3 H 4 S 3 H 4 (C  =  2-thienyl) (5.3b). The syntheses of 5.3a and 5.3c were achieved by the base-catalyzed  phospha-Peterson reaction (Scheme 5.2), whereas the synthesis of 5.3b was realized via the standard phospha-Peterson route (Scheme 5.3). Crystals suitable for X-ray diffraction analysis were obtained for 5.3a-c.  References begin on page 113  Chapter Five  110 3 SiMe  Mes-P  +  3 SiMe  R P=C Me( Ph  KOH (cat.)  OC Ph  -  0 2 ) 3 (SiMe  5.3a R 5.3c R  = =  Naph C S 3 H 4  Scheme 5.2  3 ,SiMe Mes—P\ 3 SIMe  1) PhenC(O)Ph,-78°C,lOmin 2”/ SiMe Cl -78 0  ,Li Mes—P\ 3 S1Me  MeLi ° -‘  overnight  ,rhOfl  ‘  L1CI (SiMe 0 2 ) 3  Mes  -  -  Ph 5.3b  Scheme 5.3 Anionic polymerization of 5.3a and 5.3b afforded new poly(methylenephosphine)s 5.4a and 5.4b, respectively (Scheme 5.4). The attempted polymerization of 5.3c did not yield any polymer, presumably due to an inhibition of chain propagation. All of the synthetic work described above is presented in Chapter 2. R  p=c Ph Me(  5.3a R  =  5.3b R  =  2 mol% n-BuLi  THE, RT  Naph Phen  F  1  n-Bu-I---P—C-+H [Mes Phj 5.4a R 5.4b R  =  Naph  =  Phen  Scheme 5.4 Based on literature precedent, 6 we had expected that phosphaalkenes 5.3a and 5.3b and ’ 5 poly(methylenephosphine)s 5.4a and 5.4b would be either weakly fluorescent or non-emissive due to a quenching effect from the phosphorus lone pair. Thus, we hypothesized that the chemical functionalization of phosphine centres in polymers 5.4a and 5.4b would result in an increase in fluorescence. In Chapter 3, we discussed the chemical modification of 5.4a and 5.4b. This was achieved by oxidation of the phosphine centres and coordination to borane moieties to afford functionalized macromolecules 5.5a, 5.5b, 5.6a, and 5.6b (Scheme 5.5). We studied the electronic properties of 5.3a  —  5.6a and 5.3b  —  5.6b by UV/Vis and fluorescence spectroscopy.  References begin on page 113  Chapter Five  111  F ¶j NPh1  30% H 0 (aq.) 2  n-Bu-f--P—C-—-f-H [Mes Ph j  CI 12 h CH , 2  r  Naph]  n-Bu-j---P—C—4H [Mes Ph]  5.5a  —  5.4a  SMe (excess), —78 °C 3 BH 2 THE warm slowly to RT, 12 h  Naph’\ 3 BH Ft n-Bufl—P——C [\Mes  /4  Naph\  ) /t’903 ) / \Mes Ph/ 07 Ph/  H ,,  5.6a  EoPhenl I I II n-Bu-f—P—C---f-H  air THF,7d  E Pheni I I n-BufP—C—-fH [Mes Ph 5.4b  [MS Phi 5.5b  —  SMe (excess), —78 3 BH 2  °c  THE warm slowly to RT, 12 h  Phen1 3 FH  n-Bu-j—P——C---j-H [Mes Ph] fl  5.6b  Scheme 5.5 The results showed that the naphthyl-derivatized phosphaalkene 5.3a and poly(methylenephosphine) 5.4a were non-emissive, while functionalized polymers 5.5a and 5.6a fluoresced in the UV region when irradiated at 288 nm. Similarly, for the phenanthrenyl derivatized species, the emission intensities of phosphaalkene 5.3b and poly(methylenephosphine) 5.4b were observed to be lower than those of the functionalized macromolecules 5.5b and 5.6b. These results support our hypothesis that chemical functionalization of the phosphorus centres in poly(methylenephosphine)s 5.4a and 5.4b would prevent quenching from the phosphorus lone pair and give rise to fluorescent behaviors. The long-term goal behind the work presented in Chapters 2 and 3 is to develop a poly(methylenephosphine)-based chemical sensor. The results obtained thus far builds a foundation for further work towards this ultimate goal. References begin on page 113  Chapter Five  112  While Chapters 2 and 3 focus on homopolymers with conjugated substituents, it is possible to envision analogous copolymers designed for the same sensory purpose since it may not be necessary to have phosphorus at every other atomic position in the main chain. Former members of the Gates group had studied the radical copolymerization of phosphaalkene 5.1 and styrene (Sty) to form poly(methylenephosphine)-co-polystyrene (PMP-co-PS) (Scheme 5.6). ,Ph MePh  /  VAZO88 +  100C  Ph”  1esPiPhlJ  Sty  5.1  //  Ph  PMP-co-PS  Scheme 5.6 We wanted to know more about the microstructure of PMP-co-PS, thus another objective of my work was to calculate the reactivity ratios of phosphaalkene 5.1  (rpA)  and of styrene (rs,) to  model the microstructure of PMP-co-PS. Using data from a number of copolymerization experiments, we calculated  rpA  and rs by following the Tidwell-Mortimer approach. 8 According  to a nonlinear least squares regression of the data, the best estimates of the reactivity ratios are rpA  =  0.11 and  =  0.24. Using these r values, we modeled the microstructure of PMP-co-PS  and showed that an alternating pattern predominates in the backbone unless the copolymer was prepared from a monomer feed ratio of greater than 8:2. We also computed the reactivity parameters of phosphaalkene 5.1 according to the widely used Alfrey-Price Q-e scheme. ”° The 9 reactivity parameters of 5.1 will enable  us  to predict compatibility of 5.1 (and other  phosphaalkenes that are structurally and electronically similar) with other monomers for future copolymerization projects.  References begin on page 113  Chapter Five  113  5.2 Future Work 5.2.1 Towards Poly(methylenephosphine)-Based Chemical Sensors  While our studies have provided spectroscopic evidence to support our hypothesis that chemical functionalization of phosphorus atoms in poly(methylenephosphine)s 5.4a and 5.4b would lead to fluorescence, further studies are required to generalize and confirm this hypothesis for poly(methylenephosphine)s bearing other fluorescent groups. Future directions include: •  Prepare poly(methylenephosphine)s with fluorescent groups other than naphthyl and phenanthrenyl, preferably moieties that would emit in the visible region to give fluorescent responses that are observable to the human eye.  •  Measure the quantum yield of fluorescent polymers to confirm strength of emission.  As mentioned previously, a chemosensor based on poly(methylenephosphine) may not need phosphorus at every other atomic position in the main chain. In fact, sensing behaviors may be realized by random copolymers. To this end, future work includes: •  Copolymerize phosphaalkenes bearing fluorescent groups with vinyl monomers.  •  Study the electronic properties of copolymers by UV/Vis and fluorescence spectroscopy.  To evaluate the potential of new materials for sensing applications, one would need to: •  Perform studies to test sensitivity and selectivity.  5.2.2 Copolymerization of Phosphaaikenes  Using the Q-e reactivity parameters of phosphaalkene 5.1, we can predict the  References begin on page 113  Chapter Five  114  predilections of 5.1 (and of structurally and electronically similar phosphaalkenes) to copolymerize with certain other monomers. It is possible to predict the microstructures prior to carrying out the copolymerization experiment. Copolymerization of phosphaalkenes with olefins offers the potential of adding new dimensions to materials available today. A few of the goals in our research include the development of water-soluble materials, macromolecular chemical sensors, and materials for polymer-supported asymmetric catalysis. Some of our targeted materials may be realized by copolymerization of phosphaalkenes with vinyl monomers. Future work involving copolymerization of 5.1 (and derivatives thereof) will be greatly aided by using the Q-e reactivity parameters of 5.1 to screen monomers for tailored applications.  5.3 Closing remarks The preparation and chemical functionalization of new poly(methylenephosphines)s bearing fluorescent substituents was accomplished. An investigation of the electronic properties showed that chemical functionalization of the phosphorus centres in the new poly(methylenephosphines)s resulted in enhanced fluorescent properties. We also modeled the microstructure of PMP-co-PS by calculating the reactivity ratios of phosphaalkene 5.1 and of styrene. The architecture of PMP-co-PS is important as it ultimately influences the behavior, physical attributes, and function of the material. The results obtained by these studies represent the foundation towards chemical sensors based on homo- or copolymers derived from phosphaalkenes. Future development of new materials from the (co)polymerization of phosphaalkenes is an exciting and expanding area of research, and thus the story of poly(methylenephosphine)s is to be continued.  References begin on page 113  Chapter Five  115  5.4 References (1)  Tsang, C. W.; Yam, M.; Gates, D. P. J Am. Chem. Soc. 2003, 125, 1480-1481.  (2)  Noonan, K. J. T.; Gates, D. P. Angew. Chem.,  (3)  Noonan, K. J. T.; Feldscher, B.; Bates, J. I.; Kingsley, J. J.; Yam, M.; Gates, D. P. Dalton  mt. Ed.  2006, 45, 727 1-7274.  Trans. 2008, 445 1-4457. (4)  Gillon, B. H.; Patrick, B. 0.; Gates, D. P. Chem. Commun. 2008, 2161-2163.  (5)  Smith, R. C.; Protasiewicz, J. D. J Am. Chem. Soc. 2004, 126, 2268-2269.  (6)  Wright, V. A.; Patrick, B. 0.; Schneider, C.; Gates, D. P. J Am. Chem. Soc. 2006, 128, 8836-8844.  (7)  Tsang, C. W.; Baharloo, B.; Riendi, D.; Yam, M.; Gates, D. P. Angew. Chem.,  mt. Ed.  2004, 43, 5682-5685. (8)  Tidwell, P. W.; Mortimer, G. A. I Polym. Sci., Part A: Gen. Pap. 1965, 3, 369-387.  (9)  Aifrey, T.; Price, C. C. I Polymer Sci. 1947, 2, 101-106.  (10)  Aifrey, T.; Bohrer, J. J.; Mark, H. Copolymerization; Interscience Publishers, Inc.: New York, 1952.  References begin on page 113  

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