Analysis on the charge transfer and intermolecular interaction of the synthesized biological molecule bis(benzimidazolium) maleate: a comprehensive DFT approach

The FT-IR, FT-Raman, and UV–Vis spectra of bis(benzimidazolium) maleate (BM) were analysed. Quantum computations with the DFT methodology were used for finding the stable conformer and structural optimization deploying the Gaussian '09 software. An X-ray diffraction study on a single crystal revealed that the grown crystal is an orthorhombic system with a space group. To examine the numerous intra- and intermolecular interactions in a molecular system, natural bond orbital (NBO) analysis is performed. After completing normal coordinate analysis to identify the vibrational modes, PED assignments were established. According to vibrational analysis, the stretching wavenumber of hydrogen bond donor NH and hydrogen bond acceptor CO₂ is red-shifted due to interaction. DOS spectral analysis is used to investigate the molecular orbital contributions. The HOMO–LUMO analysis is used to determine the studied compound’s conductivity, reactivity, and stability. The COO⁻ groups are vulnerable to electrophilic attack, whereas the NH group in the benzimidazolium ring is probably nucleophilic, according to the MEP plot, Fukui function, and natural population analysis. The Kirby-Bauer disc diffusion technique was used to determine the antifungal activity of the BM against Candida albicans and Aspergillus niger fungal pathogens. Molecular docking studies were used to elucidate the interaction between ligands and proteins. According to ADME parameter analysis and the Lipinski rule for the BM molecule, the chemical possesses good drug-like qualities and could eventually be developed into an antifungal medication.