Synthesis, Photophysical and Electrochemical Study of Luminescent Bis-Cyclometalated Alkynylgold(III) Complexes

Abstract

A series of bis-cyclometalated alkynylgold(III) complexes, [Au(^tBuC^N^C^tBu){C≡C–C6H4–N(C6H4R-4)2-4}] (R = OMe, Me, ^tBu and CF3), has been designed and synthesized. The substituent effects on their photophysical and electrochemical properties have been examined. The complexes with electron-donating substituents on the diarylamino moiety are observed to exhibit intense structureless emission band at ca. 647–691 nm in dichloromethane at room temperature, of which the origin is assigned to be the ligand-to-ligand charge transfer (LLCT) excited state, as supported by computational studies. It is demonstrated that the photophysical and electrochemical properties of the complexes can be readily tuned upon the variation of electronic effect of the substituents on the alkynyl ligands, providing insights into the structure-property relationship of bis-cyclometalated alkynylgold(III) complexes.