Syntheses, Crystal Structures And Properties Of Metal-Organic Coordination Polymers

Metal-Organic coordination polymer is formed by self-assembly through coordination bond between bidentate or multbentate organic ligand and central metal ion. The central ion, in general, is transition metal ion with a definite coordination model, acting as template and Organic ligand with many coordination sites, acting as building block. In coordination polymers, bidentate or multibentate ligands coordinate with one metal ion or two different metal ions to construct 0-D, 1-D, 2-D or 3-D covalent frameworks, between which hydrogen bonds may be formed to build up hydrogen-bonding network. Diversified structures of the coordination polymers result in unusual properties of the novel materials. In this paper, according to principles of molecular design, Cu(Ⅰ),Ag(Ⅰ), Cu(Ⅱ),Fe(Ⅱ), Ni(Ⅱ), Mn(Ⅱ), and Co(Ⅱ) were selected as templates, 8,8'-Dithiodiquinoline(dtdq),4-cyanopyridine(cypy),2,2'-Bipyridyl-3,3'-dicarboxylic acid(bpdc), 4,4'-bipyridine(bpy) as building blocks. The new coordination polymers were synthesized under solvothermal conditions and the crystal structures were determined, of which electrical and thermal properties were also investigated.The major contributions from the paper as follows:1. Five novel coordination polymers are synthesized (1) 1-D chain Cupro-8-thioquioline Coordination Polymer, [CuI(C9H6NS)]n was synthesized by the reaction of CuCl and dtdq in a methano-thermal reaction, where dtdq was decomposed into 8-thioquioline under high temperature and pressure condition. (2) The novel 1-D coordination polymers, [M(μ2-bpdc)(H2O)2]n (M=Co2+, Fe2+, Mn2+) were assembled with CoCl2, FeSO4 and MnCl2·4H2O, respectively, and bpdc under hydrothermal conditions.(3) A novel 3-D network inorganic-organic hybrid material, [Mn2O(OH)(C5H4NCOO)SO4 ] was formed by a hydrothermal reaction of MnCl2·4H2O, 8,8'-dithiodiquinoline and 4-cyanopyridine. 2. Characterizations of the crystal structuressingle Crystal structures of the new coordination polymers were determined by using X-ray diffraction.[CuI(C9H6NS)]n has a 1-D chains structure, belonging to monoclinic crystal system, space group P21/c with cell parameters a= 0.8043(1), b = 1.8949(3), c = 1.1048(1) nm, β = 110.109(4)°, V = 1.5810(4) nm3, Z=4.[M(μ2-bpdc)(H2O)2]n (M=Co2+,Fe2+,Mn2+), three crystal structures have the same structure type with 1-D covalent chains and 2-D hydrogen-bond network in monoclinic crystal system, space group C21/c, with cell parameters a = 1.1373(2), b = 0.78632(16), c = 1.3162(3) nm, β = 100.92(3)°, V = 1.1558(4) nm3, Z=2.[Mn2O(OH)(C5H4NCOO)SO4] has a 3-D covalent framework, which is built up with inorganic cationic layers [Mn2O(OH)SO4]+ and organic anionic ligands (C5H4NCOO)- via coordination bonds, belonging tomonoclinic crystal system, space group P21, with cell parameters a = 0.74922(5), b = 0.66587(6) , c = 1.06427(7) nm, β = 90.317(3)°, and Z = 2. 3. Physical Properties (1)Crystal energy gaps. Crystal energy gap (Eg) was determined by UV-VIS-NIR reflectance spectrum. The energy gaps of [CuI(C9H6NS)]n, [Mn2O(OH)(C5H4NCOO)SO4 ] and [Co(μ2-bpdc)(H2O)2]n are 2.0, 2.5 and 2.7eV, respectively, which all are to semiconductors. (2)Thermal stabilities. [CuI(C9H6NS)]n, [Mn2O(OH)(C5H4NCOO)SO4] and [Co(μ2-bpdc)(H2O)2]n are thermally stable up to 300℃, 300℃and 250℃, respectively, shown as their TG-DTA curves.