Functionalized bis-cyclometalated alkynylgold(III) complexes: synthesis, characterization, electrochemistry, photophysics, photochemistry, and electroluminescence studies.

A series of luminescent alkynylgold(III) complexes containing various tridentate bis-cyclometalating ligands derived from 2,6-diphenylpyridine (R-C(^)N(^)C), [Au(R-C(^)N(^)C)(C≡C-C6H4-R')] has been successfully synthesized and characterized. Complexes 1 and 6 have been determined by X-ray crystallography. Electrochemical studies show a ligand-centered reduction that originated from the tridentate R-C(^)N(^)C pincer ligands and an alkynyl-centered oxidation. The photophysical properties of the complexes have been studied in detail by electronic absorption and emission studies. Tunable photoluminescence behaviors have been observed, with the emission maxima spanning through the visible region from 476 to 669 nm in dichloromethane at room temperature, and the complexes were also found to be emissive in various media at both room and low temperatures. Transient absorption studies have been conducted to investigate the excited state properties of the complexes. Furthermore, selected complexes have been incorporated into the emissive layer (EML) of organic light-emitting devices (OLEDs) and have demonstrated interesting electroluminescence.