Chemical sensing and catalytic properties of water-stable metal-organic frameworks constructed from dicarboxylate ligands
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The classical MOFs developed in earlier years have attracted tremendous research attention because of their outstanding specific surface areas as well as tunable pore sizes. However, the hydrolytic stability of these MOFs was a huge challenge, as the MOF materials tend to undergo irreversible structural degradation in a water-containing environment. Therefore, the development of water-stable MOFs becomes necessary for the diverse applications of MOFs in humid conditions. The work presented in this thesis deals with the synthesis of water-stable MOF materials and their applications. The results obtained in the current thesis clearly indicate that the choice of metal ion and ligand is crucial for the physicochemical stability (air, water, acid-base, heat, etc.) of MOFs. The use of metal ions with higher oxidation states (e.g. Al(III), Zr(IV), Ce(IV)) along with carboxylic acid ligands has been demonstrated to be a successful approach for the preparation of water-stable MOFs. The high connectivity of metal clusters in the UiO and DUT type frameworks constructed with Al(III), Zr(IV) or Ce(IV) metal ion provides high thermal and chemical stability. The functional groups attached with the ligand molecules control the microenvironment of the MOF materials, which actually act as interaction sites during adsorption of gases and recognition sites during fluorescence sensing. The water-stable robust MOFs with enhanced performances will have great potentials in various industrial sectors over conventional porous materials (e.g. activated carbons, zeolites, etc.).
Supervisor: Shyam P. Biswas