Synthesis, crystal structure, photoluminescence and theoretical studies of a series of copper(I) compounds based on imidazole derivatives

Two mononuclear and one binuclear Cu(I) complexes that contain imidazole derivative ligands including 2-(2'-pyridyl) imidazole (L1), 2-(2'-pyridyl) benzimidazole(L2), and 2,6-bis (benzimidazol-2yl)-pyridine (L3) were synthesized. The formulas of these complexes are [CuL1(PPh3)(2)][BF4] (1), [CuL2(PPh3)(2)][BF4] (2), [Cu-2(L-3)(2)(PPh3)(2)][BF4](2) (3), respectively. The crystal structures of complexes 1-3 have been determined by single-crystal X-ray diffraction analyses. The Cu(I) ions in the complexes have a distorted tetrahedral geometry. Photophysical properties of complexes 1-3 were systematically studied. These complexes maximum emission are mainly concentrated in the 623-680 nm. An electroluminescent (EL) device using 2 as the emitter was fabricated. The device produced a red emission which matches with the PL spectrum. However, the EL device of 2 is unfavorable. The absorption properties of complexes 1 and 2 were theoretically analyzed by time-dependent density functional theory (DFT). The calculated results are in good agreement with the experimental data. (C) 2012 Elsevier B. V. All rights reserved.