Subphthalocyanines as Light-Harvesting Electron Donor and Electron Acceptor in Artificial Photosynthetic Systems

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• 作者：Mohamed E. El-Khouly ; Jong-Hyung Kim ; Jung-Hoon Kim ; Kwang-Yol Kay ; Shunichi Fukuzumi
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：September 20, 2012
• 年：2012
• 卷：116
• 期：37
• 页码：19709-19717
• 全文大小：534K
• 年卷期：v.116,no.37(September 20, 2012)
• ISSN：1932-7455

文摘

Light-harvesting subphthalocyanine鈥揻errocenophane (SubPc鈥揊c; 1) and subphthalocyanine鈥搉aphthalenediimide (SubPc鈥揘DI; 2) dyads have been synthesized, characterized, and probed by femtosecond laser photolysis. In dyads 1 and 2, both the electron-donating ferrocenophane and the electron-accepting naphthalenediimide are axially linked with the functional O鈥揚h groups (at the para position) in the axial positions of SubPc. Electrochemical data show that the SubPcs can act as both electron donors and electron acceptors. The geometric and electronic structures of dyads 1 and 2 were calculated by ab initio B3LYP/6-311G methods. The optimized structures showed that the Fc and NDI entities are separated from SubPc by 8.32 脜 (for dyad 1) and 8.85 脜 (For dyad 2). The distribution of HOMOs and LUMOs suggests the formation of SubPc^{鈥⑩€?/sup>鈥揊c+ and SubPc鈥?鈥揘DI鈥⑩€?/sup> as charge-separated states for dyads 1 and 2, respectively. Upon photoexcitation of the subphthalocyanine unit, these arrays undergo photoinduced electron transfer to form the corresponding charge-separated species, SubPc鈥⑩€?/sup>鈥揊c+ and SubPc鈥? 鈭扤DI鈥⑩€?/sup>, in which SubPc acts as an electron acceptor and an electron donor, respectively, as expected from their redox potentials determined by cyclic voltammetry. Femtosecond transient spectroscopic studies have revealed that a fast charge separation (10111012 s鈥?) occurs for dyads 1 and 2. From the kinetic studies, the rate of charge recombination and the lifetime of the charge-separated state (SubPc鈥?鈥揘DI鈥⑩€?/sup>) were found to be 2.9 脳 109 s鈥? and 345 ps, respectively.}