Tactfully improve the antioxidant activity of 2'-hydroxychalcone with the strategy of substituent, solvent and intramolecular hydrogen bond effects

The substituent and solvent effects on the antioxidant activity of 2'-hydroxychalcone (2'Cha) were sys-tematically explored in gas and three solvent phases by designing six novel compounds (2'Cha-3'NH2, 2'Cha-4'NH2, 2'Cha-5'NH2, 2'Cha-3'CN, 2'Cha-4'CN, and 2'Cha-5'CN) based on the density functional the-ory (DFT) approach. Significant parameters involved in three primary antioxidant mechanisms, namely the hydrogen atom transfer (HAT), single electron transfer followed by proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET) were computed to confirm the thermodynamically pre-ferred reaction pathway in different media. Besides, 4'-hydroxychalcone (4'Cha) was introduced to unveil the intramolecular hydrogen bond (IHB) effect on the radical scavenging capacity of 2'Cha utilizing the DFT and 2,2-Diphenyl-1-picrylhydrazyl (DPPH) ultraviolet-visible (UV-Vis) spectroscopic methods. Energy barriers and kinetic parameters for HAT reaction of 2'Cha and 4'Cha with hydroperoxyl (HOO?) radical were calculated to further compare the radical-trapping process. The photophysical properties of 2'Cha in benzene, chlorobenzene and ethanol are in good agreement with the measured experimental data and the excited-state antiradical capacity improving mechanism was also confirmed experimentally. The current work not only provides valuable guidance for synthesizing high-efficiency antioxidants but also exploits the potential application fields for 2'Cha. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, the substituent and solvent effects on the antioxidant activity of 2'-hydroxychalcone were investigated in different phases. The results provide guidance for synthesizing high-efficiency antioxidants and explore potential application fields for 2'Cha.