Studies On The Coordination Polymers Of 4, 4'-bipyridine-2, 2', 6, 6'-tetracarboxylate

According to the principle of molecule assembly and crystal engineering, the coordination polymers with regular infinity network configuration can be synthesized successfully by using lanthanide,transition metal and organic ligands. The combination of both characteristics of macromolecule and coordination compound made coordination polymers possesses unique properties and potential applications, such as NLO, magnetic materials, superconductive materials, catalysts, absorption , separation, and so on.In this paper, we used the 4,4′-bipyridine-2,2′,6,6′-tetracarboxylate(H4L) as ligand, and synthesized a series of coordination polymers which are characterized by characterized by elemental analysis, Infrared (IR) spectroscopy and single-crystal X-ray diffraction. Thermogravimetry and Luminescent properties of some coordination polymers have also been investigated. The main work is listed as follows:1. 4,4′-Bipyridine-2,2′,6,6′-tetracarboxylate(H4L) was synthesized starting from 2,6-lutidine.2. Two novel coordination polymers {[Cu2(L)(H2O)2]·2H2O}n (1),{[Mn4(L)2- (H2O)10]·3H2O}n (2) have been synthesized by hydrothermal reaction. Complex (1) crystallizes in the monoclinic space group P2(1)/c with a=7.1521(9)?, b=18.198(2)?, c=6.4022(8)?,α=90°,β=107.174(2)°,γ=90°; complex (2) crystallizes in the monoclinic space group P2(1) with a=6.9019(9)?, b=12.8709(12)?, c=21.884(2)?,α=90°,β=91.718(2)°,γ=90°. In complex (1), Cu(II) coordinated in a distorted square pyramid geometry. The carboxylates of ligand L4- coordinated with Cu(II) in monodentate andμ1,1 bridging fashion, respectively. In complex (2), the coordination number of both Mn(Ⅱ) ion is seven and the coordination geometry are distorted pentagonal bipyramid, and the coordination modes of the carboxylates are monodentate,μ1,1 and(μ2:η3), respectively.3. Two novel coordination polymers {[Co(H2O)6][Co3(L)2(H2O)2]·6H2O}n (3) and {[Ni- (H2O)6][Ni3(L)2(H2O)2]·5H2O}n (4) have been synthesized by hydrothermal reaction. Complex (3) crystallizes in the monoclinic space group P2(1)/n with a=14.2451(13)?, b=10.9194(10)?, c=14.4599(13)?,α=90°,β=100.570(2)°,γ=90°. Complex (4) crystallizes in the monoclinic space group P2(1)/n with a=13.854(2)?, b=11.3592(10)?, c=13.990(3)?,α=90°,β=101.749(2)°,γ=90°. Complex (3) and (4) have similar structure with the only difference of the number of guest water molecules. In complex (3), three kinds of Co(II) ions coordinated in a distorted octahedron geometry with the coordination number of six, and the coordination modes of the carboxylates are monodentate andμ1,2 bridging coordination modes.3. Two novel coordination polymers [Cd2(L)(H2O)2]n (5), {[Cd4(phen)2(H2L)(HL)2]·2H2O}n (6) have been synthesized with CdCl2·2H2O,1,10-phenanthroline and 4,4′-bipyridine-2,2′,6,6′- tetracarboxylate(H4L) by hydrothermal process. Complex (5) crystallizes in the monoclinic space group P2(1)/c with a=11.6910(10)?, b=5.5309(6)?, c=15.188(2)?,α=90°,β=123.560(2)°,γ= 90°. Complex (6) crystallizes in the monoclinic space group C2/c with a =15.0816(14)?, b = 18.685(2)?, c=23.297(2)?,α=90°,β=107.635(2)°,γ=90°. In complex (5), the coordination number of Cd(Ⅱ) ion is seven and the coordination geometry is distorted pentagonal bipyramid, and the coordination modes of the carboxylates are monodentate,μ1,2 bridging coordination modes, respectively. In complex (6), the coordination number of Cd1(Ⅱ) ion is nine and the coordination geometry is a distorted tricapped trigonal prism, the coordination number of Cd2(Ⅱ) ion is seven and the coordination geometry is a distorted pentagonal bipyramid. The carboxylates in complex(3) have three different coordination modes which are monodentate (-COO-), monodentate(-COOH),μ1,2 bridging and (μ2 :η3) coordination modes, respecively.4. Two 3D coordination polymers {[Gd4(L)3(H2O)9]·4H2O}n (7) and {[Nd4(L)3- (H2O)8]·4H2O}n (8) have been synthesized with Gd2O3,Nd2O3 and 4,4′-bipyridine- 2,2′,6,6′-tetracarboxylate(H4L) in a hydrothermal process. Complex (7) crystallizes in the monoclinic space group C2/c with a=12.0483(17)?, b=22.256(3)?, c=21.868(2)?, a=90°,β=105.496(2)°,γ=90°; Complex (8) crystallizes in the monoclinic space group C2/c with a=11.9772(10)?, b=22.342(3)?, c=22.154(3)?, a=90°,β=105.228(2)°,γ=90°.