Absorption Properties Of Complexes Research Articles

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 623–680nm. 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.

Chemistry of bridging phosphanes: PdI dimers bearing 2,5-dipyridylphosphole ligands.

Two synthetic routes to Pd(I) dimers that feature a bridging 1-phenyl- and 1-cyclohexyl-2,5-di(2-pyridyl)phosphole ligand, 3 a and 3 b, respectively, are described. The first involves a conproportionation process between Pd(II) and Pd(0) complexes, while the second involves ligand displacement from a preformed Pd(I) dimer. Both routes are operable for 1-phenylphosphole 1 a, whereas the former failed with 1-cyclohexylphosphole 1 b. A mechanistic study revealed that the conproportionation pathway implies a reversible oxidative addition of the P-C(phenyl) bond of Pd(II)-coordinated 1 a to Pd(0) leading to a bimetallic Pd(II) complex 5. The structures of complexes 3 a and 3 b were studied by means of X-ray diffraction. The similarity of these solid-state structures suggests that the bridging mode of the P atom is due to mu-1kappaN:1,2kappaP:2kappaN coordination of ligands 1 a, b. The electrochemical behaviour and UV/Vis absorption properties of complexes 3 a, b are reported. Complex 3 a is inert towards CO, PPh(3) and 1,3-dipoles. It reacted with dimethylacetylene dicarboxylate to give complex 6 as a result of insertion of the alkyne into the Pd-Pd bond. X-ray diffraction studies of complexes 5 and 6 are also presented.