Conformational barrier for fullerene-porphyrin-fullerene triad.

A recent study (J. Phys. Chem. B 2006, 110, 5337) proposed that fullerene-porphyrin-fullerene triad (C60PC60) could be utilized as a photoinduced switch due to the difference in electron transfer directionality for the cis and trans conformer. It is found that the rotational barrier between the SS and AA conformers of C60PC60 is about 3-5 kcal/mol, which can be facilely controllable in experiment. The rotational energy barrier for the anion system is slightly higher than the neutral C60PC60, whereas the total energy of the neutral triad is decreased by about 60 kcal/mol upon electron attachment. The corresponding reorganization energy is very small. These results reveal that the C60PC60 is a potential candidate for electrochemical machinery and energy storage material.