Syntheses,Structures,Proton Conduction,Luminescence And Second-harmonic Generation Responses Of Coordination Complexes Constructed From Benzoate-based Ligands

Coordination polymers are a kind of coordination complexes with multi-dimensional network structures formed by metal ions or metal clusters and organic ligands through coordination bonds.By selecting different metal ion centers and organic ligands,coordination polymers with distinctive structural features can be obtained.Due to the diversity of the coordination modes and strong coordination ability with metal centers of the carboxylate group,as well as unique rigid structure of benzoate ligands,the robust coordination polymers can be formed.By introducing different functional groups and heteroatoms into benzoate-based ligands,various novel structures with special properties of coordination polymers can be obtained.In this paper,benzoate-based ligands with different structures were used for construction of the coordination polymers.Seven coordination polymers with different structures constructed from these ligands and the metal ions such as UO₂²⁺and Zn²⁺ions were synthesized under solvothermal conditions.Their structures and properties have been studied and the structure-activity relationship is disclosed.According to the different metal ion centers,it is divided into two parts to elaborate:The first part,the structures and properties of uranyl-based coordination polymers are presented.Reactions of biphenyl-3,3'-disulfonyl-4,4'-dicarboxylic acid dipotassium salt?K₂H₂BPDSDC?or 4'-?3,5-dicarboxyphenyl?-2,2',6',2"-terpyridine?H₂-DCPTP?with nitrate uranyl led to four novel coordination polymers under solvothermal conditions.Compounds 1-3 are three-dimensional frameworks constructed from biphenyl-3,3'-disulfonyl-4,4'-dicarboxylate ligand.Due to the extremely low yield of compound 3,the physical property of compound 3 is not carried out.Studies on fluorescence and proton conductivity demonstrate that compounds 1 and 2 both show temperature-dependent uranyl luminescence,and temperature-and humidity-dependent proton conductivity.Compound 2 exhibits an excellent proton conductivity with the highest conductivity of 1.07×10^-33 S cm^?1.Compound 4 is 2D framework constructed with 4'-?3,5-dicarboxyphenyl?-2,2',6',2"-terpyridine?H₂-DCPTP?ligand,which links the UO₂²⁺units to give a 2D layer.This work shows rarely observed three3D and one 2D uranyl coordination polymers with their fluorescence and proton conduction behavior.The second part,three novel compounds constructed from nitrogen-containing benzoate ligand of 4,4',4''-nitrilotribenzoate?H₃-ntb?and Zn²⁺ion.compound 5 is a 3D noncentrosymmetric structure constructed from 4,4',4''-nitrilotribenzoate lignds bridge the Zn²⁺ions.Compound 6 is a 2-fold interpenetrating 3D structure.The Zn²⁺ions are connected by the 4,4',4''-nitrilotribenzoate ligands to give a 2D layer,which is further linked by the acetate ligands to form 2-fold interpenetrating 3D structure.Compound 7contains dinuclear[Zn₂?COO?₆]units.The dinuclear[Zn₂?COO?₆]units are linked by the 4,4',4''-nitrilotribenzoate ligands to give 2D layer.In this part of the work,three coordination polymers with different structures based on zinc ions were demonstrated,and the second-order nonlinear optical effect properties of compound 5,the fluorescence properties of compound 6 and compound 7 were studied.