A three-dimensional ZnII coordination network based on 5,5′-methylenebis(2,4,6-trimethylisophthalic acid) and 2,7-bis(1H-imidazol-1-yl)fluorene: synthesis, structure and luminescence properties

In recent years, coordination polymers constructed from multidentate carboxylate ligands and N-containing ligands have attracted much attention since these ligands can adopt a rich variety of coordination modes which can lead to crystalline products with intriguing structures and interesting properties. A new coordination polymer, namely poly[[diaqua[mu-2,7-bis(1H-imidazol-1-yl)fluorene-kappa N-2(3):N-3'][mu-5,5'-methylenebis(3-carboxy-2,4,6-trimethylbenzoato)-kappa O-2(1):O-1']-zinc(II)]hemihydrate], {[Zn(C23H22O8)(C19H14N4)(H2O)(2)]center dot 0.5H(2)O}(n), 1, was prepared by the self-assembly of Zn(NO3)(2)center dot 6H(2)O with 5,5'-methylenebis(2,4,6-trimethylisophthalic acid) (H(4)BTMIPA) and 2,7-bis(1H-imidazol-1-yl)fluorene (BIF) under solvothermal conditions. The structure of 1 was determined by elemental analysis, single-crystal X-ray crystallography, powder X-ray diffraction, IR spectroscopy and thermogravimetric analysis. Each Zn-II ion is sixcoordinated by two O atoms from two H(2)BTMIPA 2(-) ligands, by two N atoms from two BIF ligands and by two water molecules, forming a distorted octahedral ZnN2O4 coordination geometry. Adjacent Zn II ions are linked by H(2)BTMIPA 2(-) ligands and BIF ligands, leading to the formation of a two-dimensional (2D) (4,4)-sql network, and intermolecular hydrogen-bonding interactions connect the 2D layer structure into the three-dimensional (3D) supramolecular structure. Each 2D layer contains two kinds of helices with the same direction, which are opposite in adjacent layers. The luminescence properties of complex 1 in the solid state have also been investigated.