Five copper(II) metal-organic coordination complexes with micro-channels based on flexible bis(imidazole) and carboxybenzaldehyde ligands; structural influence of experimental conditions on their frameworks

Five new copper(II) metal-organic coordination complexes, [Cu-2(1,2-bix)(2)(L)(4)] (1), [Cu(1,3-bix)(L)(2)](n)center dot nCH(3)OH center dot 3H(2)O (2), [Cu(1,3-bix)(L)(2)](n)center dot nH(2)O (3), [Cu-5(1,3-bix)(2)(L)(6)(NO3)(2)(H2O)(2)(OH)(2)]center dot 2H(2)O (4) and [Cu(1,4-bix)(L)(2)](n) (5), have been synthesized using 4-carboxybenzaldehyde (HL) and 1,n-bis(imidazol-l-yl-methyl) benzene (1, n-bix; n = 2, 3, 4) as ligands. These complexes were structurally characterized by single-crystal X-ray crystallography and further characterized by FT-IR spectroscopy and thermogravimetric analysis (TGA). Complex 1 is a symmetrical binuclear structure, and in compound 2 the 1D ladders are entangled through pi-pi stacking interactions to generate a 3D network with one-dimensional micro channel. A 3D coordination framework 2 converted to network 3 by just increasing the reaction temperature. Metal-organic polymer 3 is comprised of 1D corrugated double chains structure. Complex 4 has a pentanuclear (Cu-5) cluster structure and compound 5 shows a 1D zigzag chain. The magnetic properties of the complexes 1 and 3 are reported briefly.