Construction And Properties Of Semi-rigid Aromatic Polycarboxylic Acid Ligand-metal Complexes

In this paper,we prepared three semi-rigid aromatic polycarboxylic acid ligands respectively,which are:H₃cbca（4?-（1-carboxyethoxy）-[1,1?-biphenyl]-3,5-dicarboxylic acid）,Hcmtna（4-（carboxymethoxy）-6-methyl-1-（p-tolyl）-2-naphthoic acid）and H₂cmna（6-（carboxymethoxy）-2-naphthoic acid）,Different metal coordination polymers were prepared by solvothermal method,and the structure and properties of the complexes were studied as follows:[Co₂（OH）（H₂O）₂（cbca）₂H₂O]_n（CP 1）was synthesized by organic carboxylic acid ligand H₃cbca and Co Cl₂·6H₂O by solvothermal method,the X-ray single crystal diffraction test proved the three-dimensional skeleton structure of CP 1.At the same time,the X-ray powder diffraction,infrared spectroscopy,ultraviolet absorption spectra and thermal weight loss of CP 1 were tested to further analyze the structural features of CP 1.The fluorescence recognition performance and mechanism of CP 1 for antibiotics,pesticides（2,6-dichloro-4-nitroaniline）,Fe³⁺and nitroaromatic compounds were explored.Four complexes were constructed with organic carboxylic acid ligand Hcmtna,named Co（H₂O）₄（Hcmtna）₂（Co-cmtna）,[Cd（H₂O）（cmtna）]n（CP 2）,[Eu（H₂O）₂（cmtna）（Hcmtna）]n（CP 3）,[Sm（H₂O）₂（cmtna）₂]n（CP 4）,respectively.It was found that Co-cmtna shows high sensitivity and low detection limit when identifying antibiotics,pesticides and Fe³⁺.In addition,studied the interaction of ligands Hcmtna and Co-cmtna with human serum albumin,the interaction of analytes and human serum albumin（HSA）was analyzed by ultraviolet-visible（UV-Vis）absorption,fluorescence,synchronous fluorescence,three-dimensional fluorescence,circular dichroism（CD）spectroscopy and molecular docking.The results indicate that the mechanism of the interaction between the analyte and HSA is static quenching.The number of binding sites,binding constants and binding distance（r）of analytes interacting with HSA can be known through research and calculation,and the interaction process is spontaneous.The two analytes are mainly combined with HSA through electrostatic force,considering the quenching relationship between Fe³⁺and Co-cmtna,the effects of Fe³⁺on the interaction between Co-cmtna and HSA have been studied,which will help to understand the absorption and metabolism of the analyte in vivo and provide a basis for the design of naphthalene-containing drugs.The ligand H₂cmna（6-（carboxymethoxy）-2-naphthoic acid）was used to construct 6complexes,named Co（H₂O）₄（Hcmna）₂（Co-cmna）,[Zn（cmna）H₂O]n（CP 5）,[Cd（cmna）H₂O]n（CP 6）,[Sm（cmna）H₂O]n（CP 7）,[Eu₂（H₂O）₄（cmna）₃]n（CP 8）,[Tm₂（cmna）₃（H₂O）₃]n（CP 9）.It was found that these six complexes had two different types of space groups,and complexes with different dimensional structures were constructed.In addition,elemental analysis,infrared spectroscopy,powder X-ray diffraction,thermal stability analysis,etc.were used to further characterize the complexes.