Study On Synthesis And Properties Of Metal Complexes Based On 4-(5-Mercaptotetrazole-1-yl)Benzoic Acid

In this paper,4-?5-mercapto-tetrazolium-1-yl?benzoic acid?H₂PMTZ?was used as main ligand,2,2'-bipyridine,4,4'-bipyridine,1,10-phenanthroline and 2':6',2''-terpyridine as second ligands.Herein,two?-bonded polymers with four coordination polymers were synthesized by solvothermal synthesis with transition metal Cd?II?Zn?II?by supramolecular self-assembly.The compounds was characterized by single crystal/X-ray powder diffraction?XRD/PXRD?,FT-IR spectroscopy,thermogravimetric analysis?TGA?,elemental analysis and scanning electron microscopy?SEM?.The gas Sorption and heavy metal adsorption properties of two?-?stacking framework structures were studied.?1?Four novel coordination polymers were prepared by hydrothermal synthesis that4-?5-mercaptotetrazol-1-yl?benzoic acid?H₂PMTZ?as the main ligand,4,4'-bipyridyl and2,2':6',2''-tripyridine as the second ligand,and Cd?II?Zn?II?as metal node:{[Zn?PMTZ??2,2':6',2''-Tpy?]·2H₂O}_n?1?,{[Cd?PMTZ??2,2':6',2''-Tpy?]·CH₃OH·H₂O}_n?2?,{[Zn?PMTZ??4,4'-Bpy?]·2H₂O}_n?3?and{[Cd?PMTZ??4,4'-Bpy?]·H₂O}_n?4?.The structure of the four complexes was analyzed by X-ray single crystal diffraction,in which both complex 1 and complex 2 were crystallized in the P2₁/c space group,and belongs to 1D chain.The complex 3crystallizes in the P-1 space group to form a 2D layered structure.The complex 4 crystallizes in the P2₁/n space group,and in forming a two-dimensional layered structure,the second ligand4,4'-bipyridyl connected each structural monomer.The four complexes were detected as pure phases by powder X-ray diffraction?PXRD?.The thermostability of the four complexes was studied by thermogravimetric analysis.The complexes 1,complex 2 and complex 3 show good thermal stability at 200°C,and poor thermal stability of complex 4.?2?Then introduce new second ligand 1,10-phenanthroline and 2,2'-bipyridine,two porous supramolecular frameworks([Zn?PMTZ??Phen?₂]?3CH₃OH·6H₂O??5?and{[Cd?PMTZ??Bpy?]2H₂O}_n?6?,merely stabilized by intermolecular?-?stacking interactions,are presented.The structural units within these frameworks are a mononuclear Zn?II?complex and a one-dimensional Cd?II?coordination polymer.The complex 5 crystallizes in the space group of R-3 and belongs to the triclinic system.The deprotonated carboxyl groups on the main ligand and N from the1,10-phenanthroline coordinated with Zn?II?form monuclear hexagonal coordination unit structure.It is worth noting that the monomer the monomer structure of complex 5 is independent.A total of 33?-?stacking interactions were produced between each monomer structure and the surrounding 6 monomer structures.The strong three-dimensional frame structure of complex 5 is formed only by the dense?interaction.Powder X-ray diffraction shows that the complex 5 can keep stable in all kinds of solvents,but also in aqueous solution with a broad pH range and high thermostability.Other than this,complex 5 shows excellent adsorption properties of the heavy metal Hg?II?,such as high adsorption amount of 786.67 mg·g^-1,high selectivity and cyclic adsorption were studied.The compound 6 crystallizes in C_2cc space group and belongs to monoclinic system.Three metal ions Cd?II?and two O atoms of PMTZ^2-?O1,O2?,respectively.A trinuclear six-coordinated octahedral configuration was formed by deprotonation of thiol tetrazolium sulfhydryl group with S atom and N atom?N7?and two pyridine N atoms?N5 N6?on the auxiliary ligand 2,2'-bipyridine.Each monomer is bridged by the sulfhydryl and carboxyl groups on the ligand to form 1D chain structure,while the 2,2'-bipyridine on the linked chain forms four?-?stacking to form a 3D supramolecular pore structure.Compound 6 represents a supramolecular?framework.On the other hand,it shows excellent thermal stability,solvent stability and acid-base stability.