Photoinduced Electron Transfer in a Charge-Transfer Complex Formed between Corannulene and Li+@C60 by Concave鈥揅onvex 蟺鈥撓€ Interactions

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• 作者：Mihoko Yamada ; Kei Ohkubo ; Mitsuhiko Shionoya ; Shunichi Fukuzumi
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：September 24, 2014
• 年：2014
• 卷：136
• 期：38
• 页码：13240-13248
• 全文大小：603K
• ISSN：1520-5126

文摘

A charge-transfer (CT) complex was formed between corannulene (C₂₀H₁₀) and lithium ion-encapsulated [60]fullerene (Li⁺@C₆₀) with the binding constant K_G = 1.9 脳 10 M^鈥? by concave鈥揷onvex 蟺鈥撓€ CT interactions in benzonitrile at 298 K, exhibiting a broad CT absorption extended to the NIR region. Femotosecond laser excitation of the C₂₀H₁₀/Li⁺@C₆₀ CT complex resulted in the singlet charge-separated (CS) state, ¹(C₂₀H₁₀^鈥?/Li⁺@C₆₀^{鈥⑩€?/sup>), which decayed with the lifetime of 1.4 ns. Nanosecond laser excitation of Li+@C₆₀ resulted in intermolecular electron transfer (ET) from C₂₀H₁₀ to the triplet excited state of Li+@C₆₀ [3(Li+@C₆₀)*] to produce the triplet CS state 3(C₂₀H₁₀鈥?/Li+@C₆₀鈥⑩€?/sup>). The distance between two electron spins in the triplet CS state was estimated to be 10 脜 from the zero-field splitting pattern observed by EPR measurements at 4 K. The triplet CS state decayed to the ground state via intramolecular back electron transfer (BET). The CS lifetime was determined to be 240 渭s in benzonitrile at 298 K. The temperature dependence of the rate constant of BET afforded the reorganization energy (位 = 1.04 eV) and the electronic coupling term (V = 0.0080 cm鈥?). The long lifetime of triplet CS state results from the spin-forbidden BET process and a small V value.}