Construction And Properties Of Metal Complexes Based On Tetrazole Dicarboxylic Acid Ligand

Metal-organic framework compounds have received extensive attention from researchers because of their good application value in optical,electrical and magnetic.The fashion of tetrazole ligands is very flexibles such as many coordination sites and the coordination mode.The N-donor ligands with different coordination modes,lengths,and rigidness/flexibilitycanprovidecooperativecoordinationtogetherwith multifunctional carboxylate ligands to create new Coordination Polymers.Tetrazole ligands,due to their exposed N atoms,are easily coordinated with metal ions and can be used to identify harmful metal ions in water to achieve the purpose of probe function.Tetrazole bridges and carboxylic acid bridges with tetrazate bridges.The construction of mixed bridge not only makes the novel complexes structures,but also makes them have more unique magnetic and fluorescent properties.In this dissertation,a series of 1D to 3D coordination polymer were constructed by using ligands of tetrazdicarboxylic acid ligands with multiple coordination sites and coordinated with metal ions and Ln（III）ions.The 1-19 complexes were characterized by single crystal X-ray analysis,IR spectrum analysis,elemental analyses,and some of them have also been characterized by magnetic measurements.The main points are as follows:1.MagneticpropertiesofLn（III）lionscomplexesof5-（1H-tetrazol-5-yl）isophthalic5-（1-tetrazole）-isophthalic acid（H₃TZI）is a bifunctional ligand with a tetrazole group and a carboxyl group.Its ligand has a variety of coordination modes and may form a tetrazole-carboxyl-mixed bridge structure.It is conducive to the study of magnetic properties;and its ligand has a strong fluorescence to facilitate its fluorescence properties in combination with fluorescent rare earths.So we carried out its research on coordination chemistry,magnetism and fluorescence.We synthesize five compounddirectlywithLn（III）lionsDy（III）andGd（III）with5-（1-tetrazole）-isophthalic acid（H₃TZI）as ligand,two isostructural 3D MOFs based methods.The pentanuclear framework features a rare trigonal bipyramidal geometry.The magnetic studies suggest that the Gd（III）-based compound shows a significant cryogenic magnetocaloric effect(-ΔSm=41.3 J kg^-11 K^-1,ΔH=70 kOe,2.5K).However,slow magnetic relaxation behavior is observed in the Dy（III）-based compound.This work could make these MOFs available for potential applications in the field of magnetic refrigerants and molecular magnets..We used H₃TZI with Dy（III）、Gd（III）and Tb（III）metal ions to synthesize 3,4 and 5 supramolecular 3D network structures with three dinuclear units in structure different from Complex 1and Complex 2 with different solvents.X-ray single crystal diffraction analysis shows that the complexes 3,4 and 5 are isomorphous structures.The carboxyl groups on the rare earth ion and ligand are bidentate chelate coordination and bidentate coordination.One-dimensional chains are formed by ligands.The structures of complexes 3,4 and5 contain a large number of water molecules and form a three-dimensional supramolecular structure under the effect of hydrogen bonds.After magnetic tests,complexes 3-5 all exhibited antiferromagnetic behavior,in which complex 5 exhibited slower slow relaxation behavior.2.StudyonthefluorescenceofLn（III）ionscomplexesof5-（1H-tetrazol-5-yl）isophthalic acidA series of novel 3D water-stable isostructural mono/bimetallic Ln-MOFs possessing the 5-connected topology has been synthesized.The luminescent sensing studies indicate that 6-7 may be used as a multifunctional luminescent probe for detecting Fe³⁺cations,CO₃^2-,PO₄^3-,AsO₄^3-anions and acetone solvent molecules in aqueous solution.Moreover,the selective and sensitive sensing of 6-7 toward above ions and molecules in aqueous solutions is a very rare example to our knowledge.In addition,luminescent colors of 8-13 can be tuned from green to red-orange by the doping concentration of Eu³⁺ions.The luminescent properties of these materials present some potential applications in luminescent sensor and other optical display fields.3.Study on the fluorescence of transition metal ions complexes of5-（1-tetrazole）-isophthalateWe used 5-tetrazole isophthalic acid as a ligand and then added an ancillary ligand（2,2’-bpy,4,4’-bpy,phen）with different metal salts Co（II）,Cu（II）Mn（II）and Zn（II）have been synthesized by solvothermal or hydrothermal methods with six new coordination polymers with different structural features.Complex 14 showed that the one-dimensional chain formed based on tetranuclear Mn₄（μ₃-OH）₂ clusters was further expanded into a（4,8）-linked network structure.The shape of the[Mn₄（μ₃-OH）₂]cluster of the complex 14 can be described as a butterfly.[Mn4（μ₃-OH）₂]quadruplex clusters are reinforced by fourμ-syn,syn carboxylate bridges and twoμ-N,N-tetrazole bridges,adjacent[Mn₄（μ₃-OH）₂]clusters from different TZI ligands are connected in one direction to form a one-dimensional chain.One-dimensional chains extend through TZI to produce a three-dimensional network structure.Complex 15 exhibits a three-dimensional porous framework structure based on the formation of tetranuclear Cu₄（μ₃-OH）₂ clusters.The four copper atoms are further strengthened by four carboxylic acid bridges and twoμ-NN tetrazole bridges to form a rhombohedral tetranuclear cluster.Adjacent[Cu₄（μ₃-OH）₂]⁶⁺clusters are linked by a TZI ligand into a 3D frame.Complex 16 is a two-layer structure based on delta-chain formation.The[Co₃（μ₃-OH）]triangle expands along the c direction to form a bar-shapedΔ-strand.Both complex 17 and complex 18 are two-dimensional layered structures based on dual-nuclear units.In complex 17,Zn1 and Zn2 are connected by（μ-N,N-tetrazole）and（μ-OH）double bridges,and TZI ligands connect the two core units into a two-dimensional layer structure.The dinuclear units in the complex 18 are connected by a TZI ligand and are connected to a two-dimensional layer along the ab plane.The two-dimensional layer is further encapsulated into a three-dimensional framework structure byπ-πinteraction.The complex 19 is connected to the Zn₄O₄ square clusters through TZI ligands to form a（4,10）-linked three-dimensional network framework structure.Four Zn compounds are bridged by twoμ₂-OH and twoμ-syn,trans-COO bridges are connected into a rectangular[Zn₄（μ₂-OH）₂（μ-COO）₂]cluster,and the four-nuclei cluster is first The clusters are connected in a c direction by a 4,4′-bpy bridge into a one-dimensional trapezoidal chain,and the TZI ligand further connects the 1D ladder chain to a three-dimensional network structure having one-dimensional pores.Magnetic studies show that the complexes 14-16 all show antiferromagnetic coupling.Complexes 17-19 exhibit strong fluorescence with different energies.