Electronic Structure and Intermolecular Interactions of the Benzoic Acid–Ethanol Complex: Raman Spectroscopy, DFT, and Molecular Docking Analysis
Abstract
In this work, we investigated intermolecular interactions in benzoic acid and its ethanol solutions using Raman spectroscopy and quantum-chemical approaches. Analysis of the Raman spectra revealed that adding ethanol induces significant changes in benzoic acid's vibrational spectrum. These changes are primarily due to solvent effects and hydrogen-bond formation and are most pronounced in the vibrational modes corresponding to the carboxyl group. The near-invariance of the aromatic ring confirms the preservation of the structural integrity of the molecule. Theoretical calculations were performed at the DFT level, providing a thorough analysis of the system's electronic structure and energetic characteristics. The molecular electrostatic potential (MEP) surface was used to identify reactive sites within the molecule; the oxygen atoms of the carboxyl group emerged as the principal electron-rich nucleophilic centers, while the –OH group of ethanol played a significant role in hydrogen bond formation. HOMO–LUMO orbital analysis demonstrated a redistribution of electron density during complex formation and an increase in the reactivity of the system. Molecular docking results also confirmed benzoic acid's ability to interact with a biologically active binding site. During the calculations, the molecule adopted a stable conformation within the protein's active site, forming a complex through hydrogen bonds and other weak intermolecular interactions. These findings align with the MEP and electronic structure analyses, showing a close link between the molecule's quantum-chemical properties and its potential biological activity. The investigations reveal the mechanism of intermolecular interactions in the benzoic acid–ethanol system and provide a comprehensive explanation of how these interactions influence the molecule's vibrational properties, electronic structure, and behavior in a biological environment.
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Copyright (c) 2026 Abduvakhid Jumabaev, Hakim Hushvaktov, Ahmad Absanov, Asliddin Norkulov, Zokhid Ernazarov, Leonid Bulavin
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