Syntheses, Photoluminescent Properties, And Structural Investigation Of Five Complexes Based On A New T-Shaped 2-(Pyridin-3-Yl)-4,6-Pyrimidine Dicarboxylic Acid Ligand: Structure Evolution From One-Dimensional Chains To Three-Dimensional Architectures

A series of structurally diverse coordination polymers, [Mn(ppmdc)(H2O)(2)](n) (1), [Cu(ppmdc)(H2O)(2)](n) (2), {[Co(ppmdc)][Co(ppmdc)(H2O)]}(n) (3), [Zn(ppmdc)(H2O)](n) (4), and [Cd(ppmdc)](n) (5) (H(2)ppmdc=2-(pyridin-3-yl)-4,6-pyrimidine dicarboxylic acid) were obtained from metal salts and H(2)ppmdc under hydrothermal conditions. Single crystal X-ray structural analysis reveals that complexes 1-5 have different structures, ranging from one- to three-dimensions, which are mainly due to the different metal ions, and especially the coordination mode of the H(2)ppmdc ligand. Complexes 1 and 2 are 1D coordination polymers, in which the ppmdc(2-) ligand adopts a bis-(bidentate) mode to link metal ions. Complexes 3 and 4 feature a 2D metal-organic framework with Schlafli topologies of (4.6(2)) (4(2).6(2).8(2)) and (4.8(2)), respectively, in which the metal ions are bridged by (3)-ppmdc(2-) ligands. Complex 5 possesses a 3D nanotubular metal-organic framework with a point symbol of (4(9).6(6)) topology built up from the 6-connected ppmdc(2-) ligands and Cd(ii) ions. The thermal properties of complexes 1-5 have been determined. Moreover, investigation of photoluminescent properties reveals that the configuration of ppmdc(2-) resulting from metal-directed coordination has a profound effect on the fluorescence emissions of complexes 4 and 5.