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

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'-diethyny1-2,2'-bipyridine (HC=CbpyC=CH), 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 FIRMS results suggest that the [Cu(diimine)(bdpp)1 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, it pi center dot center dot center dot pi and C-H center dot center dot center dot pi interactions widely exist, among which 4 center dot CH2Cl2 shows the most striking example. The triple it pi center dot center dot center dot pi it interactions within the cation dimer and the rich C-H. pi center dot center dot center dot pi it 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. (C) 2012 Elsevier Ltd. All rights reserved.