Synthesis, crystal structure, and second-order nonlinear optical properties of ruthenium(II) complexes with substituted bipyridine and phenylpyridine ligands

Two new ruthenium(II) complexes of formula [Ru(bpy)(2)(L-1)][PF6] and [Ru(bpy)(2)(L-2)][PF6](2) are reported. HL1 is a (nitrophenyl)ethenyl-substituted phenylpyridine ligand, and L 2 is the bipyridine analogue of HL1. The X-ray crystal structure of [Ru(bpy)(2)(L-1)][PF6] has been solved, and the compound is found to crystallize in the monoclinic C2/c space group. The electronic spectrum of the cyclometalated derivative [Ru(bpy)(2)(L-1)][PF6] exhibits a low-lying transition that is red-shifted from 454 to 546 nm relative to that of the parent bipyridine-based complex, which reveals an important charge-transfer character. To support this assumption, the nonlinear optical properties were investigated by the hyper-Rayleigh scattering technique and indicate a molecular static hyperpolarizability (beta(0)) equal to 230 x 10(-30) cm(5) esu(-1). ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 6945] Weinheim, Germany, 2006).