Construction And Properties Of Metal Complexes Based On Triazolate Carboxylate Ligand

MOFs are composed of metal centers and organic ligands.They are widely used in fluorescence recognition and catalysis because of their diverse structural components,adjustable size,high porosity and functional sites.Nevertheless,it is still a challenge to design and synthesize the expected structure because there are many different factors influence the final structures,for instance,the metal centers,organic ligands and experimental conditions.Among these factors,organic ligands have proven to be most important for the composition of MOFs.Multifunctional ligands are widely used because they can be used to construct MOFs materials through a variety of coordination modes,Among them,bifunctional organic ligands including tetrazole and carboxylate groups,have been more widely utilized in the construction versatile coordination networks.This paper is dedicated to construct metal azole carboxylic acid framework materials and their applications in fluorescence recognition and catalysis.In the second chapter,Synthesis of ten crystalline materials with different structures by utilizing 5-（4-（tetrazol-5-yl）phenyl）isophthalic acid ligand with rare earth or transition metal ions,and the preparation process,crystal structure,PXRD,thermogravimetry and solid fluorescence of the synthesized materials were analyzed in detail.In the third chapter,we have studied the fluorescence recognition properties of crystalline materials 1-3 for antibiotics,anions,cations and nitroaromatic compounds,and the results show that Compound 1 recognized NMs（MDZ,ODZ and RDZ）.Compound 2shows good selectivity recognition and high sensitivity to NFs（FZD,NFZ and NFT）,Cu²⁺and Cr₂O₇^2-ions.The quenching constants(K_sv)are 2.78×10⁴M^-1,3.21×10⁴M^-1,2.54×10⁴M^-1,3.09×10⁴M^-1 and 2.42×10⁴M^-1 for FZD,NFZ,NFT,Cu²⁺and Cr₂O₇^2-ions,respectively.The corresponding detection limits are 7.38×10^-7M,6.38×10^-7M,8.06×10^-7M,6.63×10^-7M and 8.46×10^-7M.However,Compound 3 identified RDZ and 4-NP.It is calculated that the quenching constants are 1.5x10⁴M^-1 and 2.97x10⁴M^-1 for RDZ and 4-NP,and the detection limits are 1.86x10^-6M and 1.35x10^-6M.Moreover,the principle of fluorescence recognition of the above three compounds was discussed.Finally,it is concluded that the transfer or the competitive absorption of energy occurs between the crystalline material and the analyte.In the fourth chapter,we have explored the application of Compound 4-8 and their composites with other materials in catalysis.The data of the pure Compound 4,5 and 8 in the electrocatalytic hydrogen evolution performance（HER）show that 4 has optimal data compared with 5 and 8,and its initial overpotential is about 140 m V（vs.RHE）,η₁₀ is 230m V and Tafel is 89m V dec^-1.It is speculated the possible reason is that the catalytic performance of the Co-based material is better than the Ni-based material,and when the same Co-base material,the structure of Compound 4 is more favorable for the electron transport.Therefore,it has the best performance.The HER performance of Compound 6 and 7,which integrate with acetylene black,respectively.The result showed that addition of acetylene black can improve the electrocatalytic performance,and the performance can be optimized as long as the proportion is appropriate.At the same time,we prepared the composite Ag@Co/Ni-MOFs by using Compound 4 and 5 as carrier-loaded noble Ag NPs.The composites were used for reduction of o-,m-,p-nitrophenol（2-NP,3-NP and 4-NP）.The results showed that Ag@Co-MOFs can completely reduce 4-NP in three minutes,while Ag@Ni-MOFs taked eight minutes to achieve the same effect,which may be caused by the uneven distribution of Ag NPs on the two supports,or possibly due to difference in the rate of diffusion of the reactants in the catalyst.