Fc/Fc + ) for the reduction potential of 4a 2+ , which is extremely close to the value obtained for the two-electron reduction (-0.36 V vs. Fc/Fc + ). The excited-state reduction potential of 4a 2+ compares favorably with that of most known photocatalysts and it seems that only the 3-cyano-1-methylquinolinium ion, which does not absorb visible light, is a significantly stronger photooxidant. Moreover, the oxidative power of 4a 2+ is comparable to what is obtained with two-photon excitation schemes or via photoelectrochemistry systems as motivated in the introduction (Figure ).