Quantum Chemical Investigations on the Hydrogen-Bonded Interactions of Bioactive Molecule N²-(4-Methoxysalicylidene) Arginine Hemihydrate

Abstract

The geometry optimization, natural bond orbital analysis, and vibrational analysis of a Schiff base compound N²-(4-Methoxysalicylidene) Arginine Hemihydrate (4MSAH) were carried out using the density functional B3PW91 method with the 6–31 G (d,p) basis set. Natural Bond Orbital (NBO) analysis is carried out to examine the various intra and inter molecular interactions of molecular system. Normal coordinate analysis was carried out to elucidate the vibrational modes and the assignments were made on the potential energy distribution. From the vibrational analysis, it is endorsed that the stretching wave number of hydrogen bond donor COO^- and hydrogen bond acceptor NH₂⁺ is shifted due to the interaction. MO (Molecular Orbital) analysis was accomplished to propose the biological activity of the molecule and the impact of the transition of electrons from n→π* was studied using the UV transmittance spectrum. The molecular orbital contributions are studied by using DOS spectral analysis. Topological studies of 4MSAH were conducted utilizing the Electron Localization Function (ELF) and the Local orbital locator (LOL). Hirshfeld surface analysis and reduced density gradient analysis were conducted to investigate distinct covalent and non-covalent interactions. Molecular docking was employed on antifungal proteins to explore protein-ligand interactions and verify the compound’s bioactivity.

Keywords:

• Interaction
• density of states
• reduced density gradient
• Hirshfield
• docking

Acknowledgment

The Authors thank Dr. I. Hubert Joe, Associate Professor of Department of Physics, Kerala University for granting us permission to do computational works in their Research Lab.

Disclosure statement

No potential conflict of interest was reported by the author(s).