Direct synthesis and catalytic activity of oxazole derivative copper II complex encapsulated in zeolite from rice husk

Abstract

Several copper (II) complexes derived from organic ligands [benzo[b]oxazole] acetonitrile] within the intracrystalline structure of ZSM-5 (Si/Al = 38) through direct synthesis under autogenous pressure are reported. Cu^II-BOA/ZSM-5 complexes were characterized by elemental analysis, XRD, FT-IR, UV–Vis, DTA/TGA, and N₂ adsorption. XRD patterns of the encapsulated complexes suggest that the zeolite framework has not collapsed during encapsulation. Until the crystallinity reaches 0.05 Cu^II-BOA/Z, the crystallinity rises monotonically, followed by a decrease as the complex concentration increases. Additionally, the encapsulated copper (II) complex reduced both its surface area and pore volume relative to the parent zeolite, suggesting that the Cu^II-BOA complex is encapsulated inside it. Among the catalysts examined, encapsulated-0.05Cu^II-BOA/Z showed maximum conversion (26%) and selectivity (90%) toward phenol. Density functional theory (B3LYP-6-31G(d)) was performed to study the effect of the interaction mode of complex with zeolite. The NLOs manners were elucidated via 1st and 2nd hyper polarizabilities. The charge transport mechanism was anticipated using ionization potential (IP) and bond dissociation enthalpy (BDE), which were subsequently employed to examine the autoxidation characteristics.