shows the energy profile (ΔG°, kJ mol -1 ) of the IRC involving the steps (i-iii), where the obtained TS indicates a low activation energy (Ea = 48.6 kJ mol -1 ) of the 2PCET. Similarly, an energy profile with a TS (Ea = 39.4 kJ mol -1 ) was obtained using the TPSSh functional (Supporting Information, Figure ). in the spin density distributions on the electron-donor side (PiceH4) and the electron-acceptor side (O2 •-). In addition, the TS was electronically characterized by the delocalization of πelectrons over the HB complex (most of the spins were distributed in O2 superior process in agreement with the electrochemical result. Moreover, the initial PT occurred at 3′OH, forming an intermediate complex (PiceH3 --HO2 • ); further, the second PT occurred at 4′OH (para OH) along the 2PCET without dissociation of the HBs. Herein, we compared Figure (a) with the IRC of 2PCET from catechol to O2 •-to elucidate the role of the stilbene moiety of PiceH4. A similar IRC was obtained with a TS for catechol (step ii) using both functionals (Figure ), where the Ea for PiceH4 (B3LYP: 48.6, TPSSh: 39.4) was lower than that for catechol (52.5, 41.4). Thus, this Ea comparison revealed the kinetically superior O2 •--scavenging ability of PiceH4 compared with that of catechol, implying that the stilbene double bond promotes the 2PCET reaction via the catechol moiety.