Two molecular triads consisting of a porphyrin (P) covalently linked to a fullerene electron acceptor (C60) and a Ï-extended tetrathiafulvalene electron donor (TTF) have been synthesized. Time resolved spectroscopic investigations of the triad featuring a free base porphyrin moiety (TTFâP2HâC60) show that in 2-methyltetrahydrofuran solution, excitation of the porphyrin leads to formation of a TTFâP2HË+âC60Ëâ charge-separated state in 25 ps. Electron transfer from the TTF generates a final TTFË+âP2HâC60Ëâstate with an overall yield of 0.87. This species decays to the ground state in 1.07 µs. Similar experiments on the zinc analog, TTFâPZnâC60, show formation of TTFâPZnË+âC60Ëâ
in 1.5 ps, followed by generation of TTFË+âPZnâC60Ëâ with a yield of 0.09. This charge-separated state also decays to the ground state in 1.07 µs. Comparison of these results with those for previously reported triads with different donor moieties reveals differences in electron transfer rate constants that can be qualitatively understood in the framework of the MarcusâHush electron transfer formalism.
我们合成了两种分子三元体,它们由与
富勒烯电子受体(C60)共价连接的
卟啉(P)和Ï-扩展的四
噻吩电子供体(
TTF)组成。对以游离基
卟啉分子(
TTFâP2HâC60)为特征的三元组进行的时间分辨光谱研究表明,在
2-甲基四氢呋喃溶液中,
卟啉受激发后会在 25 ps 内形成
TTFâP2HË+âC60Ëâ 电荷分离态。电子从
TTF转移到最终的
TTFË+âP2HâC60Ëâ态,总产率为0.87。这种物质在 1.07 μs 内衰变到基态。在
锌类似物
TTFâ
PZnâC60上进行的类似实验显示,
TTFâ
PZnË+âC60Ëâ在1.5 ps内形成,随后生成
TTFË+â
PZnâC60Ëâ,产率为0.09。这种电荷分离态也在 1.07 μs 内衰减到基态。将这些结果与之前报道的具有不同供体分子的三元组的结果进行比较,发现了电子转移速率常数的差异,这些差异可以在马库斯-胡什电子转移形式主义的框架内得到定性的理解。