Computational Insights into the Structural, Spectroscopic, Biological, and Topological Properties of Chloro- and Fluoro-Substituted Quinolone Carboxylic Acids

In this study, the quinolone derivatives (RS)-1-ethyl-5,6,8-trichloro-7-(3-methylpiperazin-1-yl)-4-oxoquinoline-3-carboxylic acid (ECMPQC) and (RS)-1-ethyl-5,6,8-trifluoro-7-(3-methylpiperazin-1-yl)-4-oxoquinoline-3-carboxylic acid (EFMPQC) were theoretically investigated using density functional theory (DFT) at the B3LYP/6-31G(d,p) level to determine their structural and spectroscopic properties. Time-dependent density functional theory (TD-DFT) was employed to analyse the frontier molecular orbitals (FMOs) and simulate the UV-Vis spectra of the quinolone derivatives in the gas phase. Natural bond orbital (NBO) and molecular electrostatic potential (MEP) analyses were carried out to elucidate intra- and intermolecular interactions as well as charge distribution characteristics. Topological analysis indicated the presence of both localized and delocalized electronic regions within the molecular frameworks. Furthermore, molecular docking studies were conducted to assess the potential biological interactions of these derivatives with viral proteins that play crucial roles in viral replication, disease progression, host mortality, and overall health outcomes.