Excited state electron transfer after visible light absorption by the Co(Ⅰ) state of vitamin B_(12)

摘要

The first example of excited state electron transfer from cob(Ⅰ)alamin is reported herein. Vitamin B_(12) was anchored to a mesoporous TiO_2 thin film and electrochemically reduced to the cob(Ⅰ)alamin form. Pulsed laser excitation resulted in rapid excited state electron transfer, k_(et) ＞ 10~8 s~(-1), followed by microsecond interfadal charge recombination to re-form cob(Ⅰ)alamin. The supernucleophilic cob(Ⅰ)alamin was found to be a potent photoreductant. The yield of excited state electron transfer was found to be excitation wavelength dependent. The implications of this dependence are discussed.