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UBC Theses and Dissertations

Synthesis and characterization of new π-conjugated molecules and polymers containing phosphorus Wright, Vincent Arthur

Abstract

In this thesis, the synthesis and characterization of a new class of π-conjugated polymers is reported. In these new macromolecules, poly(p-phenylenephosphaalkene)s, the main chain consists of alternating aromatic rings and P=C groups. Several model compounds (Ph-P=C(OSiMe₃)-Mes, Ph-P=C(OSiMe₃)-C₆Me₄-C(OSiMe₃)=P-Ph, Mes-C(OSiMe₃)=P-C₆H₄-P=C(OSiMe₃)-Mes) are reported for comparison to the polymer. This comparison illustrates that the polymer exhibits a degree of extended π-conjugation throughout the backbone of the material. The effects of using thiophene (Tp) as an aromatic spacer in a poly(p-thienylenephosphaalkene) are investigated, and reveal an increase in the UV/Vis maximum absorbance compared to phenylene systems. Two compounds (Tp-P=C(OSiMe₃)-Mes, Mes-C(OSiMe₃)=P-Tp-P=C(OSiMe₃)-Mes) are described as model compounds for the polymer. Mes-P=C(OSiMe₃)-Tp shows a significant increase in the UV/Vis maximum absorance wavelength compared to the conformational isomer discussed above. If the sterically demanding substituent resides on the phosphorus atom of the phosphaalkene bond in phenylene systems, a single isomer of the phosphaalkene forms selectively. Solid state structures of Mes-P=C(OSiMe₃)-Ph, Mes-P=C(OSiMe₃)-C₆H₄-C(OSiMe₃)=P-Mes, and Ph-C(OSiMe₃)=P-C₆Me₄-P=C(OSiMe₃)-Ph were determined. The corresponding polymer was synthesized and characterized. Due to the synthetic route to the P=C bond which forms a siloxy group, these compounds are quite sensitive to protonolysis. Preliminary results towards preparing more robust poly(p-phenylenephosphaalkene)s are discussed.

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