Syntheses, Structures And Properties Of Coordination Polymers Based On Sulfur-containing Aromatic Carboxylic Acid Ligands

The sulfur-containing Aromatic carboxylic acid ligands have been attracted by chemists owing to the coordinative selectivity of S atoms and the rigidity of aromatic rings. In addition, the thiols can be oxygenated to a longer and more flexible disulfide ligand by the dissolved oxygen at the suitable condition. In our work,14 coordination polymers were synthesized in hydrothermal or solvothermal conditions by reacting Cd+, Ln+, Bi3+ salts with 2-mercapto benzoic acid, or 2-mercapto nicotinic acid and auxiliary ligands, respectively. The compounds with different dimensional structures are obtained by incorporating the different second ligands. X-rays signal-crystal diffraction, elemental analysis, XRD and FTIR were used to determin the compounds’structures; and TG,2D IR with temperature perturbation, the IR at high temperature were applied to study their thermal stability; and 2D IR correlation spectroscopy with magnetic perturbation, luminescent spectroscopy were applied to characterize their magnetic and luminescent properties. The primary contents of our work are described as follows:1) Compounds 1 and 2 were obtained by reacting 2-H2mba (as the main liagnd), 2,2’-bpy (the second auxiliary ligand) and Cd2+ under the hydrothermal condition. They were synthesized from the same raw materials but different pH levels and different reaction temperature, and the situ S-S function reaction occurred in 2, which can be considered that thiols are oxygenated by the dissolved oxygen at the suitable condition with Cd(II) cations mediating the in situ reaction as the catalysts traditionally. Complexes 1 and 2 are both 1D chains, but the difference lies in the linkage of the ligands. The successful synthses of 1 and 2 indicate that the experimental approaches and experimental conditions have great effects on the structure on the final products.2) Eleven Ln-2,2’-dtba compounds were prepared under hydrothermal condition by assembling 2-H2mba and Ln2O3 with the different second ligands. In these complexes, the 2,2’-H2dtba ligand came from the in situ S-S function reaction of 2-H2mba under the hydrothermal conditions. It is found that the second ligand plays an important role in this reaction and strongly affects the structure of the final products. For compounds 4-10, the chelating biimidazole was selected as a second ligand, the flexible 2,2’-H2dtba ligand link [Ln(biim)]3+ units to form 1D chain. In compounds 11 and 12, the bridging 4,4’-bipyridine linked the 1D Ln(2,2’-dtba) double chains to a 2D layer. The volume monodentate ethanol is so small that it nearly has no effect on the dimension of the compounds. The successful syntheses of these lanthanide complexes fill the gap left by the absence of lanthanide-organic frameworks based on 2,2’-H2dtba.3) Under the solvothermal condition, it is the first time to obtained the bismuth complex of 2-Mercaptonicotinic acid by reacting by 2-H2mna and Bi3+ in DMF, which decomposed into dimethylamine cation and formic acid. The dimethylamine cation plays an important role in balancing the charge and templating the framework. Chelated by S, N atoms and bridged by the O of carboxyl group in 2-mna2-, the Bi(III) cations are linked by 2-mna2- ligands to a 3D structure with diamond-type topology, The quantum chemistry calculation show that it may be used as photocatalysis material with its semiconductor property.