Synthesis, Crystal Structure, Photophysical and Redox Properties of a Novel Ru(Ⅱ) Complex with Carbazole-grafted 2-(2-Pyridyl)benzimidazole

摘要

A novel Ru(Ⅱ) complex [(bpy)2Ru(PBC)](PF6)2 (PBC = N-[4-(9-carbazole)butyl]-2-(2-pyridyl)benzimidazole) has been synthesized and verified by 1H NMR, elemental analysis and X-ray crystallography. The crystal (C48H40F12N8P2Ru, Mr = 1119.89) belongs to the triclinic system, space group P1, with a = 13.128(4), b = 13.814(4), c = 14.184(4) , α = 84.112(6), β = 88.473(6), γ = 78.196(6)°, Z = 2, V = 2504.6(13) 3, Dc = 1.485 g/cm3, F(000) = 1132, R = 0.0750 and wR = 0.1896. The Ru atom adopts a distorted-octahedral coordination geometry with the bond distances and bond angles falling in normal ranges. The complex shows an intense metal-to-ligand charge transfer (1MLCT) (dπ(Ru) →π*(L)) transition (ε ~1.2×104 dm3mol-1cm-1) at 457 nm in the UV-Vis absorption spectrum and a strong red phosphorescence at 632 nm in the CH3CN solution at ambient temperature. An efficient intramolecular energy transfer process from the carbazole unit to the [(bpy)2Ru(PB)]2+ emissive center exists by selective optical-simulation. Its electrochemical behavior shows multiplicate redox processes based on the metal center, the grafting carbazole moiety and the 2-(2-pyridyl)benzimidazole unit.