A theoretical study of the structure–radical scavenging activity of hydroxychalcones

Abstract

The molecular structure and radical scavenging activity of six new synthesized hydroxychalcones have been explored by using density functional theory (DFT) with the B3LYP exchange correlation functional. The minimum energy conformations were obtained from the energy scan, then a further geometry optimization was performed at the B3LYP level with 6-31+G∗∗ basis set. For radicals and cations, the geometry optimizations and frequency calculations were also done at the UB3LYP/6-31+G∗∗ level. The homolytic O–H bond dissociation enthalpy (BDE) and the adiabatic ionization potential (IP) were determined both in gas phase and in solvents using PCM model. The geometry structure, radical, electron character and the frontier molecular orbital were analyzed to explore the key factors that influence the radical scavenging activity of the hydroxychalcones. Based on BDE and IP values, it was revealed that compound 3 is expected to be more efficient hydrogen atom and electron donors than others, B-ring of hydroxychalcones is the active center and the hydrogen atom transfer (HAT) appears as a major mechanism in antioxidant action. The calculated results are in good agreement with experimental values.