Shape Controllable Preparation of Submicronic Cadmium Tetrazole-Based Metal-Organic Frameworks via Solvothermal or Microwave-Assisted Methods and Their Photocatalytic Studies
Résumé
The paper describes the experiments conducted to create shape controllable preparations of submicronic cadmium tetrazole-based MOFs. In order to prepare the submicron sized blocks and tubes of bis[5-(2-pyridyltetrazolato)]diaquacadmium(II) [(2-PTZ)(2)Cd(H2O)(2)] MOFs both solvothermal and microwave augmented reaction procedures have been followed. Cadmium nitrate tetrahydrate, cyanopyridine and sodium azide were used as reactants in both the conditions without any surfactants or modulators. Subsequently, IR spectroscopy and single-crystal X-ray crystallographic studies were performed on the prepared MOFs. Examinations using scanning electron microscopy and X-ray powder diffraction of the products made by the microwave method showed formation of bundles of regular submicrotubes, as opposed to the submicron-sized irregular blocks of the Cd-MOF obtained through the solvothermal method. The fluorescence peak of the sub-microtube MOF was found at 460 nm while the irregular-blocks emitted at 442 nm indicating a red shift for the former. In addition, the relative intensity of the peak at 460 nm was higher in the former, indicating a decrease in the crystallite size. Band gaps of the MOFs calculated by using the Tauc plots were 2.87 and 2.73 eV, respectively. Their photocatalytic performances using methylene blue under UV-vis irradiation have been investigated.