Next, Figure shows the equilibrium schemes of a PCET between RsvH3 (deprotonated at a: feasible rather than at 3OH (-1.9). These results show that the stilbene-double-bond with the para-OH plays a role in resonance, resulting in promotion of the PCET at 4'OH. As shown in the electrochemical results, the PCET between O2 •-and RsvH3 occurs as an intra-complex reaction via two or three HBs on two phenolic rings linked by stilbene-double-bond. Thus, these calculation results imply that PT from 4'OH with ET concertedly occurs, where the coplanarity of the two phenolic rings of the stilbene moiety plays an essential role in the successful scavenging of O2 •-.