| Abstract
| - A family of mono- and binuclear Cy3P-supported gold(I) complexes containing variousπ-conjugated linear arylacetylide ligands, including the two homologous series (Cy3P)Au(C⋮CC6H4)n-1(C⋮CPh)and (Cy3P)Au(C⋮CC6H4)nC⋮CAu(PCy3) (n = 1−4), have been prepared. X-ray crystal analyses revealedno intermolecular aurophilic interactions in their crystal lattice. The lowest-energy singlet transitions arepredominately intraligand in nature and exhibit both phenyl and acetylenic 1(ππ*) character. Strongphotoluminescence is detected in solid and solution states under ambient conditions, with lifetimes in themicrosecond regime. For complexes with a single arylacetylide group, only phosphorescence from thearylacetylide 3(ππ*) state is observed. Vibrational spacings in the solid-state emission spectra can beattributed to a combination of phenyl ring deformation and symmetric phenyl ring and C⋮C stretches.Additional delayed-fluorescence emission is recorded for complexes with multiple p-arylacetylide units,and this is attributed to a triplet−triplet annihilation process. The phosphorescence energy of thesecomplexes are readily modified by altering the length of the conjugated arylacetylide system, while theintensity of phosphorescence relative to fluorescence decreases when the p-arylacetylide chain is elongated.Information regarding the nature and relative energies of arylacetylide singlet and triplet excited states hasbeen derived from the two homologous series and extrapolated to polymeric arylacetylide species. The3(ππ*) excited-state reduction potentials E° [Au+/Au*] (Au = 1a, 2, and 4) are estimated to be −1.80,−1.28, and −1.17 V versus SSCE, respectively.
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