The Structure And Properties Of Coordination Polymers Research Based On Pyridine Carboxylic Acid Ligands

Coordination polymers (CPs) is a kind of crystalline materials which built through coordination bond by inorganic nodes (metal ions or metal-ion clusters) and organic bridging ligands containing more than one match site to form the infinite extension of 1D and 2D or 3 D network structures. This kind of materials has become one of the most rapidly developing areas in the current material chemistry owing to its attractive structure and great application value in optical, electrical, magnetic, gas storage/adsorption fields. But challenges coexists with development, because of too many factors affected complex during the building process and the unpredictability of the structure, so how to construct complexes with target structure and specific functions has become a great challenge for scientists in the process of research. To master each factor's influence on the structure will be great significance. Based on these considerations above, we held in-depth discussions about the organic ligands, solvents and coordination modes'influence to the structure and performance based on controlling variable method.In this context, we have selected three bipyridy-carboxylate ligands for bridging linkers which containing a carboxylic acid, dicarboxylic acid, tricarboxylic acid. Under different conditions, twelve CPs were obtained:[Cd(L1)2]n(1), [Cd(L1)2]n·2H2O(2), [Cd(Ll)2]n(3), [Cd2(L1)2(tpa)(H2O)2]n·(nH2O)(nCH30H)(4), [Zn(Ll)2]n(5), [Zn(L1)2]n·CH3CN (6), [Zn(L1)(tpa)0.s]n·NMP(7), [Co(HL2)2(H2O)2]n·4H2O(8), [Eu(L2)(HL2)(H2O)]n(9), [Pb(L2)]n·5H2O(10), [Zn(HL3)(H2O)]n(11), [Zn3(L3)2(H2O)2]n·nH2O(12). Among them, complexes 1-7 are constructed by a carboxylic acid pyridine ligand,8-10 by dicarboxylic acid pyridine ligands,11-12 by tricarboxylic acid pyridine ligands. The structures of all the CPs have been confirmed by X-ray single crystal diffraction, elemental analysis, infrared spectra, thermogravimetric analysis, etc., and further discussed the influences of the main ligands, second ligands, solvents to the CPs. The fluorescent properties of the Zn2+ and Cd2+ have been tested. The adsorptive capability of CPs 7 and 10 has also been investigated.