Structure and reactivity of baicalein radical cation

Abstract

Neutral baicalein, corresponding radical cation, and three possible radicals obtained by proton removal from the radical cation were investigated using density functional theory. The structure and UV spectrum of baicalein were very well reproduced by the B3LYP/6-311+G(2df,p) level of theory. The results showed that the loss of an electron from baicalein molecule induced the transfer of H4 to O5. The reasons for this rearrangement were pointed out. It was found that delocalization of spin density is most pronounced in the thermodynamically most stable C6-OH radical. It was supposed that this radical plays a significant role in the antioxidant activity of baicalein within the single-electron transfer-proton transfer mechanism. © 2011 Wiley Periodicals, Inc.