Zinc Oxide Nanoparticles Synthesized from Zinc(II)-2-Acetylpyrazine-4-Methylthiosemicarbazone Complex and Coffea Liberica Extract: Catalysis Study

The increasing demand for sustainable catalysts is a significant challenge in the industrial sector. Traditional catalytic processes often rely on harmful chemicals and high-energy inputs, contributing to environmental pollution. In this work, we investigate the catalytic activity of chemically synthesized zinc oxide nanoparticles (ZnO NPs) derived from zinc(II) 2-acetylpyrazine-4-methylthiosemicarbazone as a precursor (ZnOSB), and green synthesized ZnO NPs derived from three different concentrations of leaf extracts of Coffea liberica leaf extract (ZnO-1, ZnO-5, and ZnO-10). ZnO-5 has been shown to exhibit a rodlike structure and highly porous morphology, while ZnO-1, ZnO-10, and ZnO-SB exhibit irregular and spherical structures with less porous morphology. FTIR spectra shows that the medium intense bands of Zn-O stretching were observed at approximately 400 cm-1 for ZnO-SB, ZnO-1, ZnO-10, and ZnO-C, while 409 cm-1 for ZnO-5. All the synthesized ZnO NPs were investigated as a catalyst in the acylation of phenol and it was shown that the green synthesized ZnO NPs are more favorable, specifically ZnO-5. A reusability test for ZnO-5 observed that this catalyst can be reused many times without significant loss in its activity. X-ray diffraction of ZnO NP shows that it crystallizes in hexagonal wurtzite phase and the average particle sizes of ZnO-1, ZnO-5, ZnO-10, and ZnO-SB were 42.18 nm, 40.56 nm, 34.34 nm, and 51.80 nm, respectively. This study shows that green synthesized ZnO NPs are potential catalysts in organic reactions. The results also show that the green synthesized ZnO NPs are more porous than chemically synthesized ZnO NPs. The synthesized ligand (L) and its zinc(II) complex (ZnL2) were characterized by FTIR, UV-Vis, and MS spectroscopic techniques.