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), [Cu2(L3)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.

Graphical abstractWe present herein the synthetic route of complex 1which is capable of producing MLCT phosphorescent emission.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The crystal structures of complexes 1–3 are good. ► Complex 3 is a novel binuclear in Cu(I) complexes. ► These complexes have phosphorescent properties. ► These complexes have electroluminescent properties.