Synthesis, structure and characterization of two new metal-organic coordination polymers based on the ligand 5-iodobenzene-1,3-dicarboxylate

Two new coordination polymers (CPs) formed from 5-iodobenzene-1,3-dicarboxylic acid (H(2)iip) in the presence of the flexible 1,4-bis(1H-imidazol-1-yl)butane (bimb) auxiliary ligand, namely poly[[mu(2)-1,4-bis(1H-imidazol-1-yl)butane-kappa N-2(3):N-3'](mu(3)-5-iodobenzene-1,3-dicarboxylato-kappa O-4(1),O-1':O-3:O-3')cobalt(II)], [Co(C8H3IO4)(C10H14N4)](n) or [Co(iip)(bimb)](n), (1), and poly[[[mu(2)-1,4-bis(1H-imidazol-1-yl)butane-kappa N-2(3):N-3'](mu(2)-5-iodobenzene-1,3-dicarboxylato-kappa O-2(1):O-3)zinc(II)] trihydrate], {[Zn(C8H3IO4)(C10H14N4)]center dot 3H(2)O}(n) or {[Zn(iip)(bimb)]center dot 3H(2)O}(n), (2), were synthesized and characterized by FT-IR spectroscopy, thermogravimetric analysis (TGA), solid-state UV-Vis spectroscopy, single-crystal X-ray diffraction analysis and powder X-ray diffraction analysis (PXRD). The iip(2-) ligand in (1) adopts the (kappa(1),kappa(1)-mu(2))(kappa(1),kappa(1)-mu(1))-mu(3) coordination mode, linking adjacent secondary building units into a ladder-like chain. These chains are further connected by the flexible bimb ligand in a trans-trans-trans conformation. As a result, a twofold three-dimensional interpenetrating alpha-Po network is formed. Complex (2) exhibits a two-dimensional (4,4) topological network architecture in which the iip(2-) ligand shows the (kappa(1))(kappa(1))-mu(2) coordination mode. The solid-state UV-Vis spectra of (1) and (2) were investigated, together with the fluorescence properties of (2) in the solid state.