Synthesis and characterization of Manganese(II), Cobalt(II) and Copper(II) coordination polymers with a flexible zwitterionic based ligand

Abstract

Four new coordination polymers, formulated as {[MnCl(µ-bipna)](NO3)⋅2H2O}n (1), {[CoCl2(µ-bipna)]⋅2H2O}n (2), {[CuCl(µ4-bipna)]BF4⋅2H2O}n (3) and {[CuCl(µ4-bipna)]ClO4⋅2H2O}n (4) where H2bipnaBr2 = 1,1′-(1,1′-biphenyl-4,4′-diylbis(methylene))bis(3-carboxypyridin-1-ium) bromide, were synthesized under solvothermal conditions. Their structures have been characterized by single crystal and powder X-ray diffraction analyses, infrared spectra (IR) and elemental analyses. Complexes 1, 3 and 4 are isostructural and display 3-fold interpenetrated 2D → 2D structures with sql topology and the point symbol 44.62. Complex 2 exhibits a 1D coordination polymer structure, which becomes a stacked 3D supramolecular structure by hydrogen bonding and π⋅⋅⋅π interactions. The structural diversity of the compounds could be due to the conformation of the flexible zwitterionic ligands. In 2, the bipna ligand displays a cis-conformation, while in the other compounds the ligand shows a trans-conformation. The thermal and optical properties of the compounds were investigated.