Facile CeO₂ Nanoparticles Catalysed the Synthesis of a Series of 2,4,5-Trisubstituted Imidazole Derivatives and their DFT Studies for NLO Application

Cerium oxide nanoparticles have demonstrated their effectiveness as recyclable and efficient catalysts in synthesising 2,4,5 trisubstituted imidazole derivatives. Several approaches, such as IR, <sup>1</sup>H‑NMR, <sup>13</sup>C-NMR, and mass spectrometry techniques, characterize the structures of the obtained compounds. This synthetic method incorporates several merits, including easy operational conditions, moderate time requirements, cost-effectiveness, absence of by-products, and high yield. In this study, the optimal yield was achieved with a cerium oxide concentration of 10 mol% in an ethanol medium maintained at a temperature of 80 °C for 120 to 180 minutes. To describe the molecular geometry, global reactive descriptors, MEP, and computational analyses were carried out by the DFT method with a basis set of B3LYP/ 6–31 G (d, p). It was observed that compound 4c was found to possess a larger energy gap due to a low degree of electronic conjugation compared to the other synthesised compounds. Based on the results obtained from the study of NLO properties, it was evident that compound 4d manifested first-order hyperpolarizability 11 times more significant than the standard urea. NBO analysis confirmed that in all compounds, greater stability was achieved due to intramolecular charge transfer.