Supramolecular Control of the Spin-Dependent Dynamics of Long-Lived Charge-Separated States at the Micellar Interface As Studiedby Magnetic Field Effect
Supramolecular Control of the Spin-Dependent Dynamics of Long-Lived Charge-Separated States at the Micellar Interface As Studiedby Magnetic Field Effect
复制标题
磁场效应研究胶束界面长寿命电荷分离态自旋相关动力学的超分子控制
DOI：
10.1021/jp401725f
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Tomoaki Miura
中科院分区：
文献类型：
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作者：
T. Omori;Y. Wakikawa;T. Miura;Y. Yamaguchi;K. Nakayama;and T. Ikoma;Tomoaki Miura
利用磁场效应研究了胶束界面长寿命电荷分离中的自旋选择性。两亲性紫精与非离子表面活性剂络合形成超分子受体笼，其大小由受体浓度控制，如动态光散射测量所证实。利用时间分辨荧光和瞬态吸收光谱研究了客体多环芳烃分子到紫精分子的光诱导电子转移。成功观察到自由基产率的负MFE，这表明通过超分子控制供体-受体（DA）距离实现了单重态长寿命自由基对的产生。的单重态前体MFE的优势是敏感的受体浓度，这可能会影响的D-A距离以及笼的大小。然而，MFE的理论分析给出了约1000的大复合率。108 s-1，这表明仍然活跃的笼内扩散产生的赝接触自由基对的自旋允许的复合的贡献。紫精浓度和烷基链长度的重组和逃逸动力学的依赖关系进行了讨论的前体自旋状态和笼中的微环境。
Spin selectivity in long-lived charge separation at the micellar interface is studied using the magnetic field effect (MFE). An amphiphilic viologen is complexed with a nonionic surfactant to form a supramolecular acceptor cage, of which the size is controlled by the acceptor concentration, as confirmed by dynamic light scattering measurement. Photoinduced electron transfer (ET) from a guest polyaromatic molecule to the viologen moiety is observed spin-dependently with time-resolved fluorescence (trFL) and transient absorption (TA). A negative MFE on the radical yield is successfully observed, which indicates generation of singlet-born long-lived radical pair that is realized by supramolecular control of the donor–acceptor (D–A) distances. The dominance of the singlet-precursor MFE is sensitive to the acceptor concentration, which presumably affects the D–A distance as well as the cage size. However, theoretical analysis of the MFE gives large recombination rates of ca. 108s–1, which indicate the contribution of spin-allowed recombination of the pseudocontact radical pair generated by still active in-cage diffusion. Dependence of the viologen concentration and alkyl chain length on the recombination and escape dynamics is discussed in terms of precursor spin states and the microenvironments in the cage.