Syntheses, Crystal Structures and Theoretical Calculations of Two Nickel, Zinc Coordination Polymers with 4-Nitrophthalic Acid and Bis(imidazol) Ligands

Two new complexes [Ni(4-nph)(bix)(H2O)]n(1) and [Zn(4-nph)(mbix)]n·nH2O (2) (4-H2nph = 4-nitrophthalic acid, bix = 1,4-bis(imidazol-1-yl)-benzene, mbix = 1,3-bis(imidazol-1-yl)-benzene) have been hydrothermally synthesized and structurally characterized by elemental analysis, IR spectroscopy, TG, fluorescence spectroscopy, single-crystal and powder X-ray diffraction. Complex 1 exhibits two dimensional (2D) network structure contain 42-number ring and complex 2 shows one-dimensional ribbon, which were further extended into three-dimensional supramolecular structure through hydrogen bonds and π–π stacking interactions. Moreover, we analyzed the natural bond orbital using the PBE0/LANL2DZ method in the Gaussian 03 program of complexes 1 and 2. The calculation results indicated the obvious covalent interactions between the coordinated atoms and the NiII, ZnII ion respectively.