Syntheses,Structures And Properties Of Coordination Polymers With Rigid Multicarboxylatopyridinium

The continuous study of metal-organic coordination polymers(CPs)has disclosed a series of new compounds with fascinating structures and properties.The choice of organic bridging ligands is of paramount importance for the construction of CPs.Multicarboxylatopyridinium and azide have been among the most popular ligands used to construct functional CPs with potential applications in magnetism,luminescence,adsorption and catalysis.So,azide/carboxylate compounds which consist of azide and carboxylate bridges have different influence on the magnetic properties and structures.This thesis designed and synthesized two ligands based on multicarboxylatopyridinium,and constructed a series of 1D to 3D complexes with different transition metals and rare earth metals.All the single crystal structures of them were measured,as well as the corresponding infrared characterization and element analysis.The magnetic and fluorescent properties of some compounds have also been measured.The main contents are as follows:1、Coordination compounds with 1-(3,5-dicarboxylatophenyl)-4-carboxylatopyridinium tosilate([H3L1]OTs)as ligand.Using 1-(3,5-dicarboxylatophenyl)-4-carboxylatopyridinium as ligand,solvothermal reactions of L1 and metal ions of Cu(Ⅱ),Mn(Ⅱ),Cd(Ⅱ),Zn(Ⅱ),Ln(Ⅲ)afforded coordination compounds(1-8).In all these compounds,compound 1 exhibits a 3D coordination framework containing carboxylate-and hydroxo-bridged chains.Compounds 2 and 3 are isomorphic and both contain 2D coordination layers based on carboxylate-bridged dinuclear units(Mn or Cd).Compound 4 shows a different 2D coordination layer,and extensive hydrogen bonding andπ-π stacking interactions lead to a 3D architecture with 1D channels,in which square tetraaqua clusters are captured through hydrogen bonds.The compound undergoes a structural transformation upon dehydration and the structure can be switched back through reabsorbing water.Magnetic studies demonstrated that the mixed μ-OH and μ-1,3-carboxylate bridges in 1 mediate ferromagnetic(FM)exchange owing to orbital countercomplementarity.The carboxylate briges in 2 mediate weak antiferromagnetic(AFM)interactions.Compounds 3-8 show the fluorescence characteristic of the ligand.2、Coordination compounds with 1-methylpyridinium-3,5-dicarboxylic chloride([H2L2]Cl)as ligand.Based on the Ligand L1,1-methylpyridinium-3,5-dicarboxylic(L2)ligands were designed and synthesized,by shortening the length of ligand,which makes the NaN3 easier to participate in coordination.Evaporation at room temperature of L2 and metal ions of Mn(II),Co(II)and Cu(II)afforded four coordination compounds.Magnetic studies were performed on the basis of the structural characterization of complexes 9-12.In the comypounds 9 and 10,metal ions are linked by the mixed(μ-1,3-COO)(μ-1,1-N3)double bridges and the ligand L2 to produce 1D chain or 2D coordination layers.For compound 11,the tricobalt unit with mixed(μ-1,1-N3)2(μ-1,3-COO)triply bridges are cross-linked by ligand to generate 2D coordination layer.Compound 12 also consists of 1D coordination chains in which tetracopper units are interlinked by the L2 ligand.Magnetic studies showed that the magnetic coupling through the metal ions is all antiferromagnetic in the compounds 9-10;Compound 11 is slightly complicated,the magnetic behavior of whole system is the result of single-ion magnetic effects and ferromagnetic interactions between metal ions;Compound 12 displays mixed ferromagnetic and antiferromagnetic coupling within tetranuclear cluster.In short,with the rigid organic auxiliary ligands of different charge,sodium azide and metal ions,we obtained a series of complexes with diverse structures.The flexibility of the organic ligands plays an important role in constructing diverse coordination modes and thereby inducing various magneto-structural properties.