Syntheses, structures and third-order nonlinear optical properties of three coordination polymers based on bis(imidazol-1-yl-methyl)benzene and aromatic dicarboxylic ligands

Three novel Zn(II) and Ni(II) coordination polymers, {Zn(BDA)(1,4-bib)}(n) (1), {Ni(BDA)(1,4-bib)}(n) (2) and {[Ni(H2O)(2)(1,2-bib)(2)](HBDA)(2)}(n) (3) (H(2)BDA = 1,2-benzenedicarboxylate; 1,4-bib = 1,4-bis(imidazol-1-yl-methyl)benzene; 1,2-bib = 1,2-bis(imidazol-1-yl-methyl)benzene), have been synthesized and characterized by X-ray diffraction. Compound 1 exhibits a 4-connected 3D framework with a 66 topology, which is comprised of Zn(II) ions, 1,4-bib and BOA ligands. Compound 2 possesses a 2D framework with a 63 topology, which contains 26-membered metallocyclic rings. In 3, each Ni(II) ion is coordinated by four 1,2-bib ligands, resulting in 2D grid sheets. Two symmetry-related HBDA-ions are located in the grids in a head-to-head fashion. Their third-order nonlinear optical (NLO) properties were determined by the Z-scan technique in DMSO solution. Compounds 1, 2 and 3 show NLO absorption with absorptive coefficients, beta(MKS), of 3.55 x 10(-11), 9.38 x 10(-11) and 1.14 x 10(-16) m W-1. Compound 1 exhibits a strong self-focusing effect with a refractive index, gamma(MKS), of 6.54 x 10(-18) m(2) W-1. The third-order NLO susceptibility chi((3)) of the three compounds were calculated to be 0.95 x 10(-11), 2.06 x 10(-11) and 2.51 x 10(-11) esu, respectively. The hyperpolarizability gamma' is 1.43 x 10(-29) for 1, 2.63 x 10(-29) for 2 and 7.58 x 10(-29) esu for 3. (C) 2014 Elsevier Ltd. All rights reserved.