Studies On Metal Coordination Polymers Constructed From Oxalate Acid And Malonic Acid

Coordination compounds, especial coordination polymers have received extensively attention in recent years, not only because of their various intriguing topological structures but also because of their potential applications as new functional materials in host-guest chemistry, molecular recognition, ion exchange, heterogeneous catalysis, non-linear optical (NOL) and so on.In this paper, 10 new coordination polymers have been designed and synthesized with oxalate (ox) and malonate (mal) dicarboxylic acid by means of conventional solution reaction. The structures of the coordination compounds have also been characterized by IR, X-ray diffraction and the thermo-gravimetric (TG) analysis were also done. The main research in this paper includes:1. Five oxalate coordination polymers: {[Mn(ox)(H₂O)₂]H₂O}_n (1);[Fe(phen)₃] -[Li(H₂O)₂Fe^â…¢(ox)₃]-7H₂O (2);[Fe(phen)₃][NaFe^â…¢(ox)₃]-4H₂O (3);[Ni(bipy)₃]-[KCr(ox)₃]H₂O (4);[Ni(phen)₃][KAl(ox)₃]-H₂O (5). In 1, the Mn^â…¡ ion is linked by two bidentate bridging oxalate ligands forming a ID zigzag chains;in 2, each Fe^â…¢ ion is coordinated by three oxalate ligands, adopting a distor -ted octahedral geometry and each Li^â…  ion is coordinated by two aqua ligands and two momodentate oxalate ligands to form a tetrahedral geometry. The Fe^â…¢ and Li^â…  ions are alternately linked by oxalate ligands to form a 1D chain. The structures of 3, 4 and 5 are similar, every M^â…¢(Fe^â…¢, Cr^â…¢ and Al^â…¢) and M^â…  (Li^â… ,Na^â…  and K^â… ) ions are octahedrally linked by oxalate ligands formi ng hetero-bimetallic [M^â… M^â…¢(ox)₃]_n^2n- 3D networks which contain cavities;andt he cations occpy the cavities through electrostatic interactions and hydrogen bond interactions.2. Five malonate coordination polymers: [Zn₂(Him)(μ-Im)₂(μ-mal)]_n(6);[Cd₂(μ4-mal)₂(H₂O)₄]_n (7);[CaCo(μ₃-mal)₂(H₂O)₄]_n (8);[CaZn(μ₃-mal)₂(H₂O)₄]_n (9);[CaCu(μ₃-mal)₂(H₂O)₄]_n (10). In 6, the Zn^â…¡ center is tetrahedron coordinated co mposed of three nitrogen atoms from one imidazole unit and two imidazolateio -ns, and one oxygen atom from the malonate anion, the whole structure formsa 2D network possessing polygonal channels along ac plane;in 7, malonate ligands act as monodentate, chelating bidentate and trisdent-ate bridging ligands link Cdn ions to form a 2D network and two different Cdn environments are observed;in 8, 9, 10, malonate ligands are in multi-coordination modes to form 2D hetero-bimetallic polymers. The polymers have two metal centers and form 3D networks through hydrogen bond interactions.3. The TG analysis of polymers 1-10 reveals that all these polymers are stabile in room temperature and more stabile than discrete monomers. In polymers 1-5, the stability are depend on dimensions of their structures and in polymers 6-10, the stability are different due to different metal ions in polymers.