Preparation And Performance Test Of Heterocyclic Multidentate Carboxylic Acid Coordination Polymers

In the past few decades,MOFs have shown great potential in many areas of composite materials because they can be synthesized by selecting organic ligands containing different atoms such as O,N,P,and S,changing the central metal atom and coordination mode,and controlling other external environmental factors to adjust the network structure,shape,and properties of the complexes.In this paper,four heterocyclic polydentate carboxylic acid ligands,1,3,5-triazine-2,4,6-triamine hexaacetic acid（H₆L1）,4-（3,5-dicarboxyphenyl）-4,2’:6’,4’-terpyridine（H₂L2）,3,5-di（4H-1,2,4-triazol-4-yl）benzoic acid（HL3）and 5-（imidazol-1-yl）isophthalic acid（H₂L4）were newly synthesized by varying the solvent ratio,temperature,metal center and nitrogen-containing ligand;four known MOFs were also synthesized in this paper.After that,based on the synthesized MOF species and different central metals,their performances were tested in different fields,such as:photocatalytic CO₂ reduction,solid antibacterial and dye adsorption,and the following results were obtained:1.Four heterocyclic polydentate carboxylic acid ligands,1,3,5-triazine-2,4,6-triamine hexa-acetic acid（H₆L1）,4-（3,5-dicarboxylphenyl）-4,2’:6’,4’-terpyridine（H₂L2）,3,5-di（4H-1,2,4-triazol-4-y1）benzoic acid（HL3）and 5-（imidazole-1-yl）iso-phthalic acid（H₂L4）were selected to be used with several nitrogen-containing ligands were synthesized with transition metals under solvent heat（hydrothermal）conditions for eight complexes named{[Sr₂（L1）]（H₂O）₂（DMF）₂}_n（1）,{[Sr₄（L2）₄（H₂O）₅]}_n（2）,{[Mn（L3）₂]（H₂O）₂}_n（3）,{[Zn₄（L3）₂（bimb）（H₂O）₂]}_n（4）,{Zn₄（L3）₂（biyb）（H₂O）₁₀}_n（5）,{[Cu₂（L4）₂（Tipa）₂]（H₂O）₂}_n（6）,{[Zn（L4）]（H₂O）₂}_n（7）,{[Cu₂（L4）₂]（H₂O）₃（DMF）₂}_n（8）,by X-ray single crystal diffraction,powder X-ray diffraction,elemental analysis and thermogravimetric analysis to characterize the structure and properties of the complexes.2.The complexes[Mn（bimip）（H₂O）₂]·H₂O（9）、{[Mn₂（biip）₂（H₂O）]·Et OH₂}_n（10）、[Co（bimip）（H₂O）_0.5]·0.5H₂O（11）、{[Co₂（TZMB）₂（1,4-bib）]·（H₂O）_1.5}_n（12）were tested for photocatalytic CO₂ reduction performance.It was found that the complex 11has good photocatalytic CO₂ reduction performance.Under the optimal reaction conditions,i.e.,10 mg of complex 11,40 mg of photosensitizer[Ru],6 m L of solvent（DMF:H₂O:TEOA=4:1:1）,and a CO₂ pressure of 1 MPa,the production rate of CO,the product of photocatalytic CO₂ reduction by complex 11,was as high as 3421.59μmol·g^-1·h^-1 after 12 h of illumination,and after three cycles of the experiment,the CO The production rate was almost unchanged after three cycles.Complexes 9 and 10are two different structures of the same ligand and the central metal Mn²⁺synthesized under different conditions,and it was found that the photocatalytic CO₂ reduction performance of complex 9 was much stronger than that of complex 10 under the same conditions.Under the optimal reaction conditions,i.e.,10 mg of complex 9,30 mg of photosensitizer[Ru],6 m L of solvent（DMF:H₂O:TEOA=3:2:1）,and a CO₂ pressure of 1 MPa,the production rate of CO as a product of photocatalytic CO₂ reduction was760.65μmol·g^-1·h^-1 for complex 9 after 10 h of light exposure,while the production rate of CO as a product of photocatalytic CO₂ reduction was only 47.89μmol·g^-1·h^-1for complex 10.At the same time,it was found that complex 12 also had photocatalytic CO₂ reduction properties.Under the optimal reaction conditions,i.e.,10 mg of complex 12,30 mg of photosensitizer[Ru],6 m L of solvent（DMA:H₂O:TEOA=4:1:1）,and 1 MPa of CO₂ pressure,the production rate of CO from the photocatalytic CO₂ reduction of complex 12 was as high as 3012.54μmol·g^-1·h^-1 after 12 h of light exposure.3.Meanwhile,the synthesized complexes were tested for their solid antibacterial properties in this paper.It was found that the different complexes exhibited different degrees of antibacterial properties against Staphylococcus aureus,Escherichia coli and Candida albicans.It is worth mentioning that complex 11 showed good antibacterial effect against S.aureus and Candida albicans,while complex 12 showed good antibacterial effect against all three bacterial groups;the minimum inhibitory concentration MIC of 5 mg/m L of compounds 11 and 12 were 400μg/m L and 500μg/m L for S.aureus.5 mg/m L of 12 showed a minimum inhibitory concentration MIC of 400μg/m L and 500μg/m L for E.coli.The minimum inhibitory concentration MIC of 5 mg/m L of the complex 11 and 12 for Candida albicans was 500μg/m L and200μg/m L,and the high concentration of the complex solution could completely inhibit the growth of bacteria and fungi within 24 h.4.Both complex 11 and complex 12 showed rapid adsorption ability on CR,where complex 12 reached 99%adsorption on CR after 10 min with a maximum adsorption amount of 1194 mg·g^-1.