Trinuclear copper(I) acetylide complexes bearing carbonyl moiety: Synthesis, characterization, and photophysical properties

A series of trinuclear copper(I) acetylide complexes with carbonyl moiety, [Cu3(μ-dppm)3(μ3-η1-Ctriple bond; length of mdashCC(O)R)2](ClO4) (R = H (1), CH3 (2), OCH3 (3), NH2 (4), NEt2 (5)) (dppm = bis(diphenylphosphino)methane), have been synthesized and characterized. The crystal structures of [Cu3(μ-dppm)3(μ3-η1-Ctriple bond; length of mdashCC(O)CH3)2](ClO4) (2) and [Cu3(μ-dppm)3(μ3-η1-Ctriple bond; length of mdashCC(O)NH2)2](ClO4) (4) were determined by X-ray diffraction. The photophysical properties of complexes 1−5 have been studied. Complexes 1−5 show luminescence both in the solid state and in acetonitrile solution at 298 K, and their emission energies are in the order: 5 > 4 > 3 > 2 > 1. Density function theory (DFT) calculations at the hybrid Perdew, Burke, and Ernzerhof functional (PBE1PBE) level were performed on model complex 1 to elucidate the emission origin of complexes 1−5.