Construction of diverse dimensionality in eight coordination polymers of bivalent metal ions using 5-nitroisophthalate and different linear N,N′-donor linkers

Assembly of 5-nitroisophthalate (nip(2-)) with first row transition metal salts [Mn(II), Fe(II), Zn(II)] in combination with the various neutral auxiliary N,N'-donor linkers, e.g., 2,5-bis-(4-pyridyl)-3,4-diaza-2,4-hexadiene (4-bpdh), 1,3-bis(4-pyridyl)propane (bpp) and 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene (4-bpdb), yielded eight new coordination polymers (CPs), namely {[Mn(4-bpdh)(nip)(H2O)(2)]center dot H2O}(n). (1), {[Fe(4-bpdh)(nip)(H2O)(2)]center dot H2O}(n) (2), {[Co(4-bpdh)(nip)(H2O)(2)]center dot H2O}(n) (3), {[Mn-2(bPP)(2)(niP)(2)(H2O)(2)]center dot H2O}(n) (4), {[Fe(bpp)(nip)(H2O)]center dot H2O}(n) (5), [Zn(bpp)(nip)(H2O)](n) (6), {[Fe(4-bpdb)(1.5)(niP)]center dot(4-bPdh)(0.5)}(n) (7) and {[Fe(4-bpdb)(nip)]center dot(4-bpdb)(0.5)(H2O)}(n) (8) using the slow diffusion technique at room temperature. The complexes 1-8 were characterized by single crystal X-ray diffraction analysis and were further characterized by elemental analysis, infrared spectroscopy (IR) and powder X-ray diffraction (PXRD). Complexes 1-3 are isostructural and exhibit a one-dimensional (1D) metal-carboxylate chain with pendant 4-bpdh ligands, which is further extended into a three-dimensional supramolecular structure by means of H-bonding and pi-pi interactions. Complexes 4-6 are also isomorphous, but distinctly different from the first three complexes. They exhibit a similar 2-fold interpenetrated three-dimensional (3D) net with 6(6) dia net topology. Compound 7 displays a two-dimensional (2D) grid-like structure, having 4-bpdh ligands in the crystal void, and this is further extended by means of intermolecular pi-pi interactions into a 3D supramolecular structure, whereas compound 8 possesses a different 2D grid structure containing free 4-bpdb ligands in the void spaces. The thermal stabilities and UV-Vis spectra of all the complexes and the luminescent properties of complex 6 were also studied. (C) 2015 Elsevier Ltd. All rights reserved.