Syntheses, structures and properties of two mononuclear copper(I) complexes with N-heterocyclic ligands

Two mononuclear Cu(I) complexes, [Cu(PBO)(PPh3)2]·PF6·CH2Cl2 (1) and [Cu(PBM)(PPh3)2]·PF6 (2) (PBO = 2-(2′-pyridyl)benzoxazole, PBM = 2-(2′-pyridyl)benzimidazole, PPh3 = triphenylphosphine), have been synthesized and characterized by elemental analyses, IR, single crystal X-ray diffraction, fluorescence spectroscopy, and cyclic voltammetry. The structural analysis revealed that in 1 and 2, the Cu(I) ions are four-coordinate and the coordination geometry around the Cu(I) is distorted tetrahedral. Photoluminescent investigation shows that 1 and 2 exhibit distinct tunable green (523 nm)-to-yellow (557 nm) photoluminescence by varying the N-heterocyclic ligands. Electrochemical properties of 1 and 2 have been investigated by cyclic voltammetry. The results suggest the frontier molecular orbits and the HOMO-LUMO energy gaps of these cuprous complexes are effectively adjusted through the introduction of different N-heterocyclic ligands.