Conformational stability, quantum computational (DFT), vibrational, electronic and non-covalent interactions (QTAIM, RDG and IGM) of antibacterial compound N-(1-naphthyl)ethylenediamine dihydrochloride

Abstract

Naphthalene derivatives are heterocyclic compounds with significant applications in the pharmaceutical and biomedical industries. Several spectroscopy methods, including FT-IR, FT-Raman, and UV–Vis, were used in this study to examine the molecular structure of N-(1-Naphthyl) ethylenediamine dihydrochloride (NEDD). By employing DFT through the WB97XD with the level of 6–311++G(d, p) as the basis set, the optimized geometrical characteristics and full vibrational allocations of frequencies by the potential energy distribution were generated and matched to the experimental data. The delocalization of charge caused by intermolecular connections becomes apparent in the natural bond orbital (NBO) study. Additionally, frontier molecular orbital bandgap energy and electron excitation analyses were acquired to provide a deeper understanding of the structural characteristics of NEDD. Frontier molecular orbital energies revealed an energy band gap of 5.505 eV, demonstrating the existence of charge transfer within the molecule. Electronic transitions seen in the experimentally recorded UV–visible spectra were assigned using the TD-DFT method whereas transition density matrix (TDM) plots showed the ability to transmit charges. Considering wave function-derived parameters like the Laplacian of electron density (LED), local information entropy (LIE), the average localized ionization energy (ALIE) as well as non-covalent interactions, provides essential insights into the reactivity and stability traits of molecular systems. Local reactivity descriptions aided in understanding the interactions of physiologically relevant molecular systems, thereby facilitating the discovery of potential pharmaceutical compounds. Drug-likeness and ADMET assessment were achieved to assess biological properties of NEDD. Antibacterial assay confirmed its effectiveness against bacterial strains, while molecular docking studies. The stability of the best docked protein has been investigated using 70 ns molecular dynamics simulation followed by effective free energy calculation using MMPBSA.