UBC Theses and Dissertations
Sulfur-bridged chromophores : polymers, copolymers and ligands for metal complexes Caron, Élise
The impact of the incorporation of sulfur bridges and their oxidation on the electronic and photophysical properties of macromolecules was investigated through the synthesis of oligomers, short polymers and copolymers. In oligomers, the energies of the frontier orbitals and the band gap can be modulated with the oxidation state of the bridge along with the length of the molecule. The sulfone containing oligomers are emissive in solution and in a polymer matrix while the compounds with sulfide bridges are non-emissive. Polymers containing sulfide groups exhibit conjugated-like behavior where the length of the polymers influences the maximum absorption and emission wavelengths. The photophysical and electronic properties of the sulfone-bridged polymers do not depend on their molecular weight and behave like distinct chromophores. Incorporation of sulfur bridges in copolymers containing electron rich or electron poor comonomers influences the energies of the frontier orbitals and the photophysical behavior. Sulfide containing copolymers have smaller band gaps while the sulfone containing copolymers are more emissive. Incorporating monomers containing a N^N bidentate motif, the copolymers coordinate metal ions and the emission of the polymer decreases. Sulfur-bridged thiazoles containing a N^N bidentate motif are used as ligands for metal complexes. Homoleptic and heteroleptic complexes incorporating sulfide or sulfone N^N ligands were obtained with ruthenium(II) and copper(I) metal centers. Their structures were elucidated using NMR spectroscopy and single crystal X-ray diffraction. The ruthenium(II) heteroleptic complexes were found to undergo photoejection when irradiated in coordinating solvent with UV light. The complexes were found to be nonemissive in fluid solution at room temperature and are emissive in the solid state and at low temperature.
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