Construction And Performance Study Of Metal Organic Frameworks With Mixed Ligands

As a class of organic-inorganic hybrid porous material, metal-organic frameworks(MOFs), have received considerable attentions owing to their emerging applications in many areas, such as separation, drug delivery, ion exchange, catalysis, sensors, and so on. Their porosity, tailoring of pore size/shape and modifiability for pore surface are superior to the traditional porous materials. At largely, the structures and properties of MOFs can be easily tailored for some pre-designed applications by selecting suitable ligands. The use of mixed-ligands owing to the variation of coordinaton environments can be a good strategy for MOFs’ construction, leading to the novel framework skeleton, the excellent roubustness and potential applications.Herein, 4,8-disulfonaphthalene-2,6-dicarboxylic acid(H4L) was advisedly selected as organic ligand reacting to Zn(NO3)2·6H2O or Cd(NO3)2·4H2O in the presence of pyridyl derivatives, respectively. Finally, BUT-201 and BUT-202 were successfully synthesized and structurally characterized. BUT-201 possesses a three-dimensional(3D) pillared double-layer structure with the rhombic channels, in which disordered(CH3)2NH2+ cations accommodate. It is found that BUT-201 can rapidly adsorb cationic dyes with smaller sizes by substitution of guest(CH3)2NH2+, but has no adsorption towards the cationic dyes with lager sizes, the anionic dyes and neutral dyes, respectively. The results show that the adsorption behavior of BUT-201 relates not only to the charge but also to the size/shape of dyes. Furthermore, the adsorbed dyes can be gradually released in the methanol solution of Li NO3. BUT-202 exhibits excellect solvent-dependent photoluminescence beause of the interaction between organic ligands and metal center. BUT-202 demonstrates highly selective and sensitive detection of TNP in DMF even in the presence of competing nitro analytes. The results show that the selective fluorescence quenching is controlled by synergistic effects including electron transfer, energy transfer and hydrogen-bonding between the MOF and TNP.