Investigation of quantum chemical studies of niclosamide in different solvents using DFT calculations.

CONTEXT: The electronic distribution, aromatic properties, spectroscopic properties, and thermodynamic behaviors of the niclosamide compound, which has antiviral, antiparasitic, and anticancer potential properties, were interpreted in different environments.

METHODS: All quantum chemical calculations were performed using density functional theory (DFT) with the B3LYP functional and 6-311++G(2d,2p) basis set with Gaussian 09 software in various phases. Thermodynamic parameters such as heat capacity, enthalpy, entropy, and Gibbs free energy of the nucleosamide molecule were calculated in various phases in the temperature range of 200-1000 K. Molecular surface analyses were performed to investigate the reactivity properties. The aromaticity of the benzene rings of the nucleosamide molecule was evaluated in various phases using HOMA indices. Orbital composition analysis with Mulliken partition was performed to determine the percentage contribution of atomic orbitals to HOMO and LUMO. Additionally, UV-Vis absorption spectra were examined in various phases to investigate the effects of solvent and environment on electronic transitions.