Study On The Construction And Properties Of The Ligand-based Complex Of Nitroformaldehyde And Benzoic Acid

Nitrogen heterocyclic benzoic acid ligands have flexible coordination modes due to the inclusion of N and O.The complexes formed by self-assembly with metal ions have been widely used in magnetism,adsorption,photocatalytic materials,and fluorescent probes.In this paper,8 novel structures with 1-（4-carboxyphenyl）-3-（pyrazin-2-yl）pyrazole（Hcapp）or4-（4-carboxyphenyl）picolinic acid（H₂cppc）as organic ligands with transition metal salts such as Co（II）,Ni（II）,Zn（II）,Cd（II）,Mn（II）and earth rear metal salts such as Eu（III）were synthesized.The structure of the complexs was determined by single crystal x-ray diffraction,and the structure of the synthesized complex was characterized by IR,thermogravimetric analysis and PXRD,and the magnetic and fluorescent properties of the new complex were studied.The specific content is as follows:1.Select 1-（4-carboxyphenyl）-3-（pyrazin-2-yl）pyrazole（Hcapp）as an organic ligand,and synthesize it with transition metal ions and rare earth metal ions under hydrothermal or solvothermal conditions Seven new types of complexes 1-7,complexes 1-6 were characterized by PXRD,infrared,and thermogravimetric properties.Single crystal X-ray diffraction test showed that the complex[Co（capp）₂（H₂O）₂]·3H₂O}_n（1）,{[Ni（capp）₂（H₂O）₂]·3H₂O}_n（2）,{[Zn（capp）₂（H₂O）₂]·3H₂O}_n（4）,{[Cd（capp）₂（H₂O）₂]·3H₂O}_n（5）,{[Mn（capp）₂（H₂O）₂]·3H₂O}_n（6）is a two-dimensional structure and a new type of isostructural heteronuclear complex;the complex[Zn（capp）₂]_n（3）is a one-dimensional chain structure through theπbetween the ligandsπ-πinteraction forms a two-dimensional structure and complex{[Eu（capp）（H₂O）₂（NO₃）₂]·2H₂O}_n（7）is a zero-dimensional dinuclear complex formed by the co-coordination of Hcapp and europium nitrate.The magnetic test results of 1show that the complex 1 has antiferromagnetic interaction.The solid-state fluorescence tests of complexes 3,4,and 5 show that they have strong emission peaks under ultraviolet light.Complexes 3 and 4 can quench aniline,Fe³⁺,Cr O₄^2-and Cr₂O₇^2-,and can be identified by the naked eye.Its quenching constant(K_SV)for 3:K_sv-aniline=4.94×10⁴,K_sv-Fe³⁺=7.74×10⁴M^-1,K_sv-Cr O₄^2-=2.99×10⁵M^-1,R²-Cr O₄^2-=0.99,K_sv-Cr₂O₇^2-=3.98×10⁵M^-1,R²-Cr₂O₇^2-=0.98;for 4:K_sv-aniline=1.58×10³M^-1,K_sv-Fe³⁺=1.22×10⁴M^-1,K_sv-Cr O₄^2-=5.43×10⁴M^-1,K_sv-Cr₂O₇^2-=2.46×10⁴M^-1.Fluorescence analysis shows that the quenching mechanism is the energy absorption competition between the complex and the analyte.2.Select 4-（4-carboxyphenyl）picolinic acid（H₂cppc）as ligand and metal ions Co（II）and Ce（III）to synthesize a transition metal-lanthanide element（3d-4f）Heterometallic coordination polymer under solvothermal conditions,in which Co（II）and Ce（III）are connected through the O in the carboxyl group of the H₂cppc ligand to form a two-dimensional 12-membered ring composed of Co（II）-Ce（III）.The network structure forms a three-dimensional structure by connecting O and N in the ligand.The structure of complex 8was confirmed by single crystal X-ray diffraction test,and a series of characterizations such as infrared spectroscopy,PXRD spectroscopy and thermogravimetric analysis of complex 8were carried out.The magnetic properties of complex 8 indicate that there is an antiferromagnetic interaction as a whole.