Detailed Quantum Mechanical Studies on Three Bioactive Benzimidazole Derivatives and Their Raman Enhancement on Adsorption over Graphene Sheets

Benzimidazole derivatives flubendazole (FD1) and similar derivatives, mebendazole (MD2) and ricobendazole (RD3) have been studied by using various computational tools to analyze their geometry and spectral characteristics. The various reactive descriptors obtained from the FMO analysis predict the reactive nature of the compound. The various lone pair/sigma to pi conjugation was analyzed using NBO formalism, which provides valuable information about intra-molecular electron transfer which is vital in predicting the inherent stability of the molecule. Nucleophilic and electrophilic regions of the molecules are identified using MESP, which adds to the reactivity information. The compounds were found to interact with graphene monolayer results show that there is enhancement in various physicochemical descriptors and surface-enhanced Raman spectra (SERS). Prediction of Activity Spectra provide activities, glutathione peroxidase inhibitor, general pump inhibitor, membrane permeability inhibitor for FD1, glutathione peroxidase inhibitor, antihelmintic, antiparasitic for MD2 and antihelmintic, antiparasitic, catalase inhibitor for RD3. Compounds form a stable complex on docking with the receptors. Results also indicate that the ligands adsorbed over graphene also form stable complexes with the receptors as indicated by the high binding affinity energy values.