Three New Co-ordination Polymers of Zinc(II) and Cadmium(II) with Dicarboxylate and Bipyridine Ligands: Synthesis, Structure and Luminescence Study

Three coordination polymers of zinc(II) and cadmium(II) of formula {[Zn(bipy)(NIPH)]0.15H2O}n(1), {[Cd2(bipy)2(NIPH)2]2H2O}n (2) and {[Cd2(bipy)4 (BDAC)(NO3)](NO3)6H2O}n (3) (NIPH = 5-nitro-isophthalic acid, H2BDAC = 1,4-benzenediacrylic acid and bipy = 2,20-bipyridine) have been synthesized and structurally characterized by X-ray single crystal diffraction analysis. All the complexes display 1D coordination polymers where M(bipy) units are connected by dicarboxylate anions(and also by nitrate in 3)acting as bridging ligands. While in 1 and 3 a zig–zag chain is generated, in case of 2 a double linear chain is formed by the two crystallographic distinct Cd atoms. In solid state all the complexes expand the dimensionality to 3D by means of p–p interactions among p rings and H-bonds generated by lattice water molecules. The fluorescence study indicates intraligand p–p* charge transfer is the reason for emission in all the complexes.