Syntheses, structures and photophysical properties of a series of luminescent copper(I) mixed-ligand complexes

Abstract

The reaction of [Cu(NCCH3)4]ClO4 with a chelating diimine ligand and 1,2-bis(diphenylphosphane)benzene (bdpp) in dichloromethane solution gives good yields of a series of mixed-ligand copper(I) complexes [Cu(diimine)(bdpp)]ClO4, where the diimine ligands are 2,2′-bipyridine (bpy), 5,5′-dibromo-2,2′-bipyridine (BrbpyBr), 5,5′-diethynyl-2,2′-bipyridine (HCCbpyCCH), 1,10-phenanthroline (phen) and 3,8-dibromo-1,10-phenanthroline (BrphenBr) in complexes 1–5, respectively. All the structures are confirmed by single crystal X-ray structure analysis. A study of the HRMS results suggest that the [Cu(diimine)(bdpp)]+ cations for complexes 1–5 are kinetically stable products, and [Cu(bdpp)2]+ is the thermodynamically stable product in DCM solution. In the crystal structures of complexes 1–5, π⋯π and C–H⋯π interactions widely exist, among which 4·CH2Cl2 shows the most striking example. The triple π⋯π interactions within the cation dimer and the rich C–H⋯π interactions among the cation dimers are suggested to be the main reasons of the high emissive quantum yield of 18.33% in the solid state under air for complex 4.