Exploring the Impacts of Substitution Position on Structural, Electronic, and Energetic Characteristics of Selected Chalcone Derivatives by DFT Method: A Quantum Computational Research

Chalcone derivatives are frequently utilized as a versatile scaffold in molecular design studies due to their broad-spectrum activities. Structural modification studies applied to increase their biological activities to a remarkable level reveal the importance of substitution positions on aromatic rings. In this respect, the study aimed to explore the effects of changing substitution positions on molecular properties. Herein, the effects of distinct substitution positions on thermodynamic and physicochemical parameters, reactivity descriptors, absorption characteristics, and intramolecular interactions were investigated utilizing quantum chemical methods. To this end, (Density Functional Theory) DFT-based calculations were performed using the GAUSSIAN 16 software with B3LYP/6-311++G (d, p) level on ortho-OH, meta-OH, and para-OH substituted chalcone derivatives. While the calculated dipole moment and polarizability values differ, very similar results were obtained for the ∆E (total energy), ∆H (enthalpy), and ∆G (Gibbs free energy) parameters. The highest polarizability value, 296.193 a.u., was obtained for the para- isomer. The ∆Eg values in the gas phase were calculated as: 4.013 eV (m-) > 3.898 eV (p-) > 3.832 eV (o-). Also, the effects of different solvents on the absorption spectra of the studied isomers were investigated theoretically using (Time Dependent) TD-DFT calculations. Molecular orbitals contributing to electronic transitions were determined for each phase. It is further anticipated that the research findings will offer novel insights to inform future studies on the implications of the substitution position.