SYNTHESIS AND PHYSICOCHEMICAL CHARACTERIZATION OF AN AMORPHOUS COBALT(II) COORDINATION POLYMER BASED ON 5-(4-AMINOPHENYL)-1,3,4-OXADIAZOLE-2-THIOL

Abstract

This study aimed to synthesize a metal-organic framework (Co-MOF) via a solvothermal method using 5-(4-aminophenyl)-1,3,4-oxadiazole-2-thiol as the ligand and cobalt(II) nitrate as the metal precursor. The synthesis was carried out in an autoclave at 100 °C for 24 h using a mixture of DMF, ethanol, and water in a 2:1:1 ratio. The obtained sample was washed with DMF and ethanol and subsequently activated at 100 °C for 8 h. The phase composition and crystal structure of the synthesized product were investigated by powder X-ray diffraction (PXRD). According to the PXRD results, the sample exhibited an amorphous structure, characterized by broad and weak diffraction peaks. This indicates that a long-range ordered crystal lattice was not formed between the ligand and the metal ions. The obtained amorphous material is therefore more appropriately classified as an amorphous coordination polymer or amorphous complex rather than a crystalline MOF. Further optimization of the synthesis conditions, including temperature, reaction time, and solvent composition, as well as modification of crystallization-promoting factors, such as the addition of modulators, is required. These findings demonstrate the importance of ligand structure and synthesis conditions in the formation of MOF materials based on 1,3,4-oxadiazole-2-thiol derivatives [1, 2, 5, 7].