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 (H2iip) in the presence of the flexible 1,4-bis(1H-imidazol-1-yl)butane (bimb) auxiliary ligand, namely poly[μ2-1,4-bis(1H-imidazol-1-yl)butane-κ(2)N(3):N(3')cobalt(II)], [Co(C8H3IO4)(C10H14N4)]n or [Co(iip)(bimb)]n, (1), and poly[[μ2-1,4-bis(1H-imidazol-1-yl)butane-κ(2)N(3):N(3')zinc(II)] trihydrate], {[Zn(C8H3IO4)(C10H14N4)]·3H2O}n or {[Zn(iip)(bimb)]·3H2O}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 (κ(1),κ(1)-μ2)(κ(1), κ(1)-μ1)-μ3 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 α-Po network is formed. Complex (2) exhibits a two-dimensional (4,4) topological network architecture in which the iip(2-) ligand shows the (κ(1))(κ(1))-μ2 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.