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Abstract

The synthesis and characterization of late transition metal complexes combined with the β-substituted 3ʹ-(diphenylphosphino)-2,2ʹ:5ʹ,2ʺ-terthiophene (PT₃) to yield metal-oligothiophene hybrid complexes are reported. These new complexes (shown on the following page) were studied with absorption, emission, and transient absorption spectroscopies, electrochemistry and X-ray crystallography. Ru(II) and Os(II) bis(diimine) complexes (52-53 and 54-55, respectively) containing PT₃ in two different coordination modes (PS and PC bound) are reported. The binding mode is shown to affect the structural, photophysical and electronic properties of the complexes. Transient absorption spectra and lifetimes were obtained for all the complexes, and support a PT₃ ligand-based lowest excited state in the case of the PS bound complexes, and a charge separated lowest excited state in the PC bound complexes. The DFT calculations and experimental results agree well. Cyclometalated iridium (III) complexes (58-63) were synthesized using microwave irradiation. In addition to the PS and PC coordination modes observed in the group 8 complexes, a third, monodentate, coordination mode was observed (P). The lowest energy absorption band and emission band shift based on the PT₃ coordination mode. The nature of the excited state lifetimes did not change with coordination mode; all were assigned as a PT3 ligand-based excited state, however, the excited state lifetimes are influenced by the coordination mode. Heteroleptic Cu(I) complexes (75-76) were synthesized and yielded three and four coordinate complexes. The electrochemical and photophysical properties of these complexes vary with solvent. Minor changes are observed in the absorption spectra when obtained in different solvents, but interesting differences are observed in the electrochemical reversibility, excited state lifetimes, and profiles of the emission and transient absorption spectra.