Syntheses, Photoluminescent Properties, and Structural Investigation of Five Complexes based on a New T-Shaped 2-(Pyridin-3-yI)-4,6-Pyrimidine Dicarboxylic Acid Ligand: Structure Evolution from One-dimensional Chains to Three-dimensional Architectures

摘要

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) (H2ppmdc = 2-(pyridin-3-yl)-4,6-pyrimidine dicarboxylic acid) were obtained from metal salts and H2ppmdc 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 H2ppmdc ligand. Complexes 1 and 2 are ID 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 (4.82), respectively, in which the metal ions are bridged by μ3-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.