Synthesis, luminescence, and cyclic voltammetric studies of novel binuclear ruthenium(II) complexes prepared from β-diketonate derivatives

摘要

Two bis-(β-diketonate) ligands [H2L1 = 3,6-bis-(4,4,4-trifluorobutane-1,3-dione)-9-butyl-carbazole and H2L2 = 3,6-bis-(4,4,4-trifluorobutane-1,3-dione)-9-hexyl-carbazole] were synthesized, and their corresponding dinuclear ruthenium(II) complexes [Ru2(bpy)4(L1)](PF6)2 (1) and [Ru2(bpy)4(L2)](PF6)2 (2) (bpy = 2,2′-bipyridine)] were prepared by the reaction of Ru(bpy)2Cl2 · 2H2O with H2L1 and H2L2 in ethanol, respectively. The structure of the ligand H2L2 was determined by single-crystal X-ray diffraction. The spectral properties of the ligands and their complexes have been studied. The absorption spectra of the complexes exhibit intense ligand-centered bands in the UV region and metal-to-ligand charge-transfer bands in the visible region. The two-photon absorption (TPA) coefficient β and TPA cross-section σ were determined by the Z-scan technique, which revealed that the two complexes exhibit strong TPA due to electronic extensive delocalization. The complexes undergo a reversible or quasi-reversible one-electron metal-centered redox process at E 1/2 = +0.93 V and E 1/2 = +0.92 V, respectively.