Post-Synthetic Modification of UiO66 and its Application in Knoevenagel Condensation Reactions

UiO66 is a new MOFs material that attracts the most attention. Its unique characteristics lead to its good thermal stability. In this paper, as for the Knoevenagel reaction, UiO66 and other UiO series MOFs were synthesized and modified. UiO66 particles were prepared by one-pot method. 2-aminopyridine, 3-aminopyridine and 4-aminopyridine were used to prepare UiO66-2Py, UiO66-3Py and UiO66-4Py particles. UiO66-2Py, UiO66-3Py and UiO66-4Py particles were modified by activated arginine, lysine and glycine to synthesize UiO66-2Py-Arg, UiO66-3Py-Lys and UiO66-4Py-Gly. Finally, the obtained samples were used for the Knoevenagel catalytic condensation reactions of benzaldehyde and ethyl cyanoacetate. In this process, the prepared samples and their intermediates were characterized by infrared spectroscopy (IR) and X-Ray diffraction (XRD), which showed that the modification of UiO66 was successful. UiO66-3Py-Lys and UiO66-4Py-Gly showed high catalytic activity in the supernatant determined by fluorescence spectrophotometer, and UiO66-4Py-Gly showed the best catalytic effects at the volume of 0.4 mL benzaldehyde.