Synthesis, Antibacterial, Antioxidant and DFT Computational Studies of Acetophenone-Based Chalcone Derivatives

Six B-ring substituted chalcone derivatives were synthesized by aldol condensation reactions of acetophenone with ortho-, meta- and para-hydroxy and their corresponding nitro group-functionalized benzaldehydes. These were used to study their spectral, anti-bacterial and anti-oxidant properties. The FT-IR and ¹H and ¹³C-NMR spectra of these derivatives, as well as in some cases from the literature, were used to confirm their structural information. A density functional theory (DFT) computational study was undertaken to investigate the changes resulting from the replacement of the electron-donating hydroxyl groups with the corresponding electron-withdrawing nitro groups and with consideration of all of their possible E/Z and s-cis/s-trans geometrical and regioisomers. The DFT computational data show that in all cases except for the B-ring ortho-nitro-substituted derivatives 5a and its regioisomer 5a′, the s-cis-(E) isomers, are thermodynamically more stable than those of the corresponding s-cis-(Z)– and s-trans-(E/Z) isomers. Furthermore, time-dependent-DFT calculations were conducted to generate vertical excitation energies, absorption wavelengths and the oscillator strengths of the chalcone derivatives. The HOMO–LUMO results and some other physicochemical parameters of the derivatives are compared with their chemical reactivities.

Synthesis, antibacterial, antioxidant and DFT computational studies of acetophenone-based chalcone derivatives