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

Three mononuclear Cu(I) complexes, namely, [Cu(2-PBO)(PPh3)(2)]center dot ClO4 center dot 2CH(2)Cl(2) (1), [Cu(3-PBO)(PPh3)(2)(ClO4)center dot CH2Cl2 (2) and [Cu(PBM)(PPh3)(2)]center dot ClO4 (3) (2-PBO = 2-(2'-Pyridyl)benzoxazole, 3-PBO = 2-(3'-Pyridyl)benzoxazole, PPh3 = 2-(2'-Pyridyl)benzimidazole, PPh3 = triphenylphosphine) have been synthesized and characterized by elemental analyses, IR, H-1 NMR, C-13 NMR, X-ray single crystal diffraction and thermal analysis. Photoluminescent investigation shows that complexes 1-3 exhibit distinct tunable light green (512 nm)-toyellow (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 (lambda(ex) = 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 HOMOLUMO 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. (C) 2018 Elsevier B.V. All rights reserved.