Photoinduced energy transfer and electron transfer processes via the triplet state of 5,6-open-azaC60 (2) were compared with those of 6,6-closed-azaC60 (3) on the basis of kinetic data obtained by means of the transient absorption spectra. In nonpolar solvents such as toluene, energy transfer predominantly took place from the triplet states of 2 (T2*) and 3 (T3*) to retinol and β-carotene. The rate constant for energy transfer (kent) from T2* to retinol was significant different from that of T3*. Furthermore, on the addition of methanol, the kent value of T2* for retinol was decreased, while no change was observed for that of T3*. These findings suggest that retinol is connected with T2* via the hydrogen-bond, but not with T3*. The decrease of the kent value of T2* by the addition of methanol suggests that retinol was replaced with methanol. In polar solvents such as benzonitrile, electron transfer took place from T2*/T3*; however, the difference in the electron transfer rate between T2* and T3* was not observed for retinol. This finding implies that the hydrogen-bond between T2* and retinol was not formed in benzonitrile, since retinol was strongly solvated by the solvent molecules.
|Number of pages||8|
|Journal||Journal of Photochemistry and Photobiology A: Chemistry|
|Publication status||Published - May 10 2001|
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Physics and Astronomy(all)