Properties And Luminescence Sensing Properties Of Metal-Organic Frameworks Based On Benzothiadiazole Carboxylic Acid

Metal-organic frameworks（MOFs）are inorganic-organic hybrid materials with intramolecular pores formed by the self-assembly of organic ligands and metal ions/clusters through coordination bonds.The high porosity and specific surface area in the structures endow MOFs with excellent physical and chemical properties,so MOF materials are widely used in various fields.In this thesis,4,4’-benzothiadiazol-4,7-dibenzoic acid（H₂BTDB）was used as the organic ligand to construct five lanthanide MOFs（Ln-MOFs）and three transition MOFs.In addition,a new ligand namely 4,4’-（benzo[c][1,2,5]thiadiazole-4,7-diyl）diphthalic acid（H₄BTDA）was synthesized.H₄BTDA ligand and the targeted MOFs were fully characterized and analyzed,and the fluorescence sensing performance was studied.The main contents are as follows:（1）Five Ln-MOFs were constructed under solvothermal conditions by changing the controllable factors（such as solvent,temperature,p H and so on）in the reaction system.Fluorescence sensing experiment shows that Ln-MOF 1 can be used as a fluorescence sensor toward benzaldehyde and salicylaldehyde.Ln-MOF 2 shows a sensing response to the biomarker dipicolinic acid（DPA）.Ln-MOF 4 can specifically identify H₂PO₄^-through fluorescence enhancement and blue shift,and the test strips designed based on Ln-MOF 4 can quickly detect H₂PO₄^-.Ln-MOF 5 has fluorescence quenching response to Fe³⁺,and the mixed matrix membrane combined with sodium alginate can directly identify Fe³⁺in DMF solution.（2）Using 3,5-BBIP and 2,6-BBIP as auxiliary ligands,three transition MOFs were constructed empolying mixed-ligand strategies.Fluorescence sensing experiment shows 6 can be used as a dual response sensor of H₂PO₄^-/OCN^-.6 shows different color transformation after identifying substance due to the existence of different shift effect.In addition,capturing RGB values from mobile applications is conducive to visual detection of identifiers.This operation realizes the quantitative analysis of the concentration of the identifier.Two Zn^II based MOFs 7 and 8 with different structures were obtained by changing the ratio of ligands to metal ions,and their structures and properties were analyzed and compared.（3）A novel H₄BTDA ligand was designed.Fluorescence sensing experiment shows that H₄BTDA has specific recognition of ethylenediamine among amine compounds,and the color transformation is obvious under UV lamp due to the presence of blue shift effect.Ethylenediamine vapor sensing can be achieved using luminescent mixed matrix films prepared by mixing H₄BTDA and polymethyl methacrylate.Using H₄BTDA as the organic ligand and Co（NO₃）₂·6H₂O as the metal ions source,a Co^IIbased complex 9 was synthesized with the auxiliary coordination of phenanthroline.