Computational and spectroscopic investigation of the interaction of mefenamic acid with phenothiazine and promazine
Project no. 29672 · Status: Kapanmış · 2023
Summary
<p>Light-sensitive molecules play a significant role in drug development and materials science by enabling the design of photoresponsive systems that can be precisely controlled using light. This study combines computational and experimental approaches to investigate the intermolecular interactions of mefenamic acid–phenothiazine (MEF–PHENO) and mefenamic acid–promazine (MEF–PRO) complexes. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were employed to determine stable conformers, simulate UV–Vis absorption spectra, calculate complexation energies, and explore electronic properties including HOMO–LUMO gaps and reactivity descriptors. Non-covalent interactions such as π–π stacking, hydrogen bonding, and van der Waals forces were analyzed, with natural bond orbital analysis providing detailed insights into hydrogen bonding. Excited-state optimizations elucidated photophysical structural changes. Complementary experimental UV–Vis absorption and fluorescence spectroscopy were performed on mefenamic acid, phenothiazine, and promazine hydrochloride using distilled water as solvent, validating computational predictions. Upon excitation, the donor–acceptor hydrogen bond distance decreases from 2.22 Å to 2.02 Å in the MEF–PHENO complex, whereas it increases from 2.52 Å to 2.56 Å in the MEF–PRO complex, reflecting different changes in intermolecular interactions. The HOMO–LUMO energy gaps are calculated as 3.49 eV for MEF–PHENO and 3.68 eV for MEF–PRO. These findings indicate that MEF–PHENO exhibits more favorable conditions for charge transfer, attributed to its shorter interaction distance and lower energy gap. The integrated results contribute to a deeper understanding of the stability, electronic behavior, and photophysical properties of these pharmacologically relevant donor–acceptor complexes.</p>