Dicarboxylic Acid Bipyridine Ligand Of The Metal Coordination Polymer Synthesis, Structure And Nature Of The Study

The design and synthesis of metal-organic coordination polymer is the focus field of coordination chemistry. Via molecular assembly and crystal engineering, the use of different metal ions and organic ligands can obtain new kind of complexes with special functions and structures. With variety of fascinating topologies and potential applications and prospects in the fields of optics, electricity, magnetism, adsorption, and catalysis, it had great significance on the research and development of supramolecular chemistry and materials chemistry. In this paper, a series of transition metal and rare earth metal coordination polymer was synthesized with 2,2'-bipyridine-4,4'-dicarboxylic acid (H2bpdc) as primary ligand. All complexes were characterized by methods of IR, elemental analysis, UV and X-ray diffraction, and their crystal structure, fluorescence properties, thermal stabilities and magnetic properties have also been systematically studied as follows:1. Five transition metal coordination polymers, [Mn(bpdc)(H2O)2]n (1),{Ni[(bpdc)(H2O)2]·2H2O}n (2), [Ni(bpdc)(H2O)2]n (3), [Cu(bpdc)H2O)]n (4), {Zn[(bpdc)(H2O)3]·3H2O}n(5) were obtained by hydrothermal synthetic method. Complex 1 is a three-dimensional coordination polymer, with srs as its topological configuration; Complex 2 and 4 are two-dimensional coordination polymer, and a three-dimensional structure is formed by intermolecular hydrogen bonds between two dimensional planes; Complex 3 is three dimensional with interspersed structure, and its topology configuration is twt; Complex 5 is a one-dimensional chain coordination polymer, with intermolecular hydrogen bonds forming a three-dimensional structure. The crystal structural analysis showed that the pyridine nitrogen atoms of 2,2'-bipyridine-4,4'-dicarboxylic acid ligand adopted the chelating form in these 5 complexes. In addition, the thermal stabilities of all five complexes and the fluorescence property of complex 5 were also studied.2. Five rare earth metal coordination polymers,{Ln2[(bpdc)3(H2O)3]·H2O}n (Ln=La (6),Ce (7),Pr(8),Nd(9),Gd(10)) were obtained by hydrothermal synthetic method, in which 6-9 were four isomorphic heteronuclear coordination polymers. Complex 10 is a three dimensional coordination polymer, possessing a novel (3,4,8)-connected topology. The structural analysis indicated that the ligand 2,2'-bipyridine-4,4'-dicarboxylic acid with the carboxyl oxygen in addition to metal ions, the nitrogen atoms of pyridine ring has also taken two modes in complex 6-9:one was located in form of chelating coordination metal ions, another was the pyridine ring occurs through the carbon-carbon single bond rotation, two nitrogen atoms did not participate in the coordination of trans form. In Complex 10 the nitrogen atoms only took the second coordination mode. In addition, five coordination polymers were tested by thermal stability analysis, and the fluorescence and magnetic property of complex 10 were also investigated.