Syntheses, crystal structures, properties of metal coordination polymers based on a novel semi-rigid aromatic carboxylate ligand

A set of new metal coordination polymers constructed from a novel semi-rigid aromatic carboxylate ligand, namely, [M(L)(4PBI)(H2O)]n (M = Ni, Co and Cu for 1, 2 and 3, respectively) and [Cd(L)(4PBI)]n (4) (H2L = 3-(1-carboxyethyl) benzoic acid; 4PBI = 2-(pyridin-4-yl)-(1H)-benzoimidazole), have been synthesized by the hydrothermal reaction, which were characterized by element analyses, FT-IR, UV–Vis diffuse reflection spectra, X-ray single-crystal diffraction, powder X-ray diffraction, and thermogravimetric analyses (TGA). Complexes 1, 2 and 3 are iso-structural. They form a one-dimensional (1D) linear chain structure connected by semi-rigid aromatic anion and further assemble into a three-dimensional (3D) supramolecular framework by π⋯π stacking and hydrogen bonding interactions. Complex 4 possesses two bi-nuclear units and displays two-dimensional (2D) layer which can further extend to a 3D supramolecular architecture via hydrogen bonding and weak packing interactions. Moreover, the luminescent property of complex 4 was investigated in the solid state at room temperature.