Synthesis, Structure And Properties Of Coordination Polymers Constructed By Flexible And Rigid Carboxylic Acid

With its unique and rich characteristics, carboxylic acid ligands has an important position in the choice of ligands to synthesis of metal-organic coordination polymeres.Use the carboxylic acid ligands to design and synthesis of coordination polymers is more and more attention and attraction by many scholars. It is not only because of their novel topological structures and potential applications.but also for their huge potential applications in the optics.gas storage.catalysis and magnetism fields.In this paper, twelve new coordination polymers have been synthesized under solvothermal conditions based on flexible ligand 5-(4’-carboxyl phenoxy) nicotinic acid (H2CPNA) and rigid rigand 3.3’,5,5’-biphenyl tetracarboxylic acid (H4BTEA) respectively.formulated as [Ni(HCPNA)2]n(1)-[Cu(HCPNA)2]n(2), [Mn2(CPNA)2(DMF)2(H2O)]n(3)-[Co(CPNA)(H2O)2]n(4) {[Zn5(BTEA)3]·2(Me2NH2)·4DMF}n(5),{[Zn(H2BTEA)]·3H2O}n(6) {[Zn2(BTEA)(DMF)2(H:O)]·DMF·2H2O}n(7),{[Cd(HBTEA)]·Me2NH2}n(8), {[Co3(H2BTEA)2(HCOO)2(H2O)2]·DMF·2H2O·HCOOH}n(9).All complexes have been characterized by single-crystal X-ray diffraction,elemental analysis,1R spectroscopy, thermogravimetric analysis and powder X-ray diffraction measurements. Their crystal structures and properties have been orderly studied as below:(1) Complex 1 and 2 are isomorphic coordination polymers,both belong to monoclinic, space group P2(1)/nå'ŒP2(1)/c, and all metal ions are six-coordinated in a distorted octahedron. Both the two complexes are three-dimensional coordination polymers with a (3,6)-connected topology framework.Complex 3 belongs to monoclinic, space group C2/c.It is a three-dimensional complex which composed of infinite 1D desymmetrical helical chains.Complex 4 belongs to triclinic, space group P-1,each Cd (â…¡) ion is six-coordinated with a distorted octahedral geometry.It exhibits a 3D framework based on infinite zigzag chains.The thermogravimetric analysis result shows that the complexesl-4 have good thermal stability.(2) Complex 5 belongs to monoclinic, space group C2/c,and it is composed of pentanuclear cluster [Zn5(COO)8] to form a three-dimensional structure with a the approximate circular microporous network.Complex 6 belongs to tetragonal, space group â… -42d, and each Zn(â…¡) ion is four-coordinated possessing a distorted tetrahedral geometry.It give a 3D (4,4)-connected framework with countless 1D desymmetrical helical chains.Complex 7 belongs to monoclinic, space group P2(1)/n.In 7 binuclear Zn are extended by the ligands linke to construct a 3D structure.Complex 8 belongs to orthohombic, space group Ibca,each Cd(â…¡) ion is eight-coordinated exhibits a distorted dodecahedral geometry.It present a 3D structure with a larger solvent accessible volume,and the effective free volume of 8 was calculated by PLATON analysis as 68.8% of the crystal volume.Complex 9 belongs to orthohombic, space group Ibca C222(1), it shows a 3D structure which constructs with infinite One dimensional spiral Co(â…¡) chains. The thermogravimetric analysis result shows that the complexes 5,7 and 8 have good thermal stability. The fluorescence properties at room temperature in the solid state indicated that these complexes have significantly enhanced fluorescence to the ligand. The adsorption property of complex 5 have also been tested and investigated, and the gas adsorption test of N2, H2, CO2 and CH4 show that the complex has a certain gas adsorption property.