Synthesis, Structure And Properties Of 2,4 ', 5 - Bentan Tricarboxylic Acid Complexes

The design and construction of coordination polymers (CPs) have received great attention because of their intriguing topology as well as potential applications in the areas of photoluminescence, nonlinear optics, ion exchange, gas storage, molecular separations, catalysis and magnetism. Until now, the design and synthesis of CPs with expected structures are still challenges for researchers. It is well known that the construction of CPs is mainly dependent on several factors, such as central metals, inorganic/organic anions, N-donor ligands, pH values, reaction temperatures, etc. Among these, the organic anions play crucial roles in the construction of coordination polymers.In this regard, the aromatic multicarboxylate ligands have been proven to be excellent candidates for building highly connected, self-penetrating or helical coordination frameworks due to their versatile bridging fashions. In this article, we choose biphenyl-2,4’,5-tricarboxylic acid as building blocks to construct coordination polymers. The biphenyltricarboxylic acid ligand has three carboxylic groups that may be completely or partially deprotonated, inducing various coordination modes and allowing interesting structures with higher dimensionality. In addition, the ligand can conform to the coordination geometries of the metal ions because its two phenyl rings can be rotated around the C-C single bond.Herein, for the first time, we report the syntheses and characterizations of eight coordination polymers based on the biphenyl-2,4’,5-tricarboxylic acid and N-donor ligands under solvothermal conditions, namely, [Zn(HL)(bib)]n·2nH2O (1), [Zn2(L)(μ3-OH)(H2O)]n·2nH2O (2), [Cd1.5(L)(H2O)2]n·0.5nH2O (3), [Cd1.5(L)(CH3 CN)]n·0.5nH2O (4), [Cd1.5(L)(bib)(H2O)2]n·nH2O (5), [Cd3(L)2(bibp)2 (H2O)2]n·3nH2O (6), [Mn(HL)(bibp) (H2O)]n·2nH2O (7) and [Cu(HL)(phen)]n (8). These complexes exhibit a systematic variation of architectures from the 1D line to 3D frameworks. All of the above coordination polymers have been characterized by single crystal X-ray diffraction analysis, powder X-ray diffraction (PXRD), IR spectroscopy, elemental analysis. Moreover, Photoluminescence properties of 1-6 were studied. The magnetism properties of complexes 7-8 were also studied. According to the structures of these eight complexes, we have found that the final architecture can be influenced by the coordination modes of the biphenyl-2,4’,5-tricarboxylic acid, the central metals and the auxiliary N-donor ligands.