Cu(I) complexes regulated by N-heterocyclic ligands: Syntheses, structures, fluorescence and electrochemical properties

Abstract

Three mononuclear Cu(I) complexes, namely, [Cu(2-PBO)(PPh3)2]·ClO4·2CH2Cl2 (1), [Cu(3-PBO)(PPh3)2(ClO4)]·CH2Cl2 (2) and [Cu(PBM)(PPh3)2]·ClO4 (3) (2-PBO = 2-(2′-Pyridyl)benzoxazole, 3-PBO = 2-(3′-Pyridyl)benzoxazole, PBM = 2-(2′-Pyridyl)benzimidazole, PPh3 = triphenylphosphine) have been synthesized and characterized by elemental analyses, IR, 1H NMR, 13C NMR, X-ray single crystal diffraction and thermal analysis. Photoluminescent investigation shows that complexes 1–3 exhibit distinct tunable light green (512 nm)-to-yellow (557 nm) photoluminescence by varying the N-heterocyclic ligands. Three complexes show intense 2-PBO-based yellow, 3-PBO-based light green and intense PBM-based bright green luminescence upon irradiation with a standard UV lamp (λex = 254 nm) at room temperature. Moreover, the electrochemical properties of 1–3 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, thus achieving the selective luminescence of the cuprous complexes.