Unique Dynamic Electron-Spin Polarization and Spin Dynamics in the Photoexcited Quartet High-Spin State of an Acceptor-Donor-Radical
Unique Dynamic Electron-Spin Polarization and Spin Dynamics in the Photoexcited Quartet High-Spin State of an Acceptor-Donor-Radical
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受体-供体-自由基光激发四重高自旋态中独特的动态电子自旋极化和自旋动力学
DOI：
10.1002/cphc.201000709
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发表时间：
2011
期刊：
影响因子：
2.9
通讯作者：
Y. Takemoto and Y. Teki
中科院分区：
文献类型：
--
作者：
Y.Funasako;K.Abe;T.Mochida;佐藤宏美・HAYAT AZWAR・SHYAM SUDHIR PANDEY・尾込裕平・早瀬修二;Y. Takemoto and Y. Teki
有机自由基中通过p-共轭的分子内自旋排列、光诱导电子转移（PET）、能量转移（EnT）和自旋动力学是有机分子自旋电子学[1，2]以及有机磁性光控中非常重要的过程。[3]利用动力学过程研究自旋操纵在分子磁学[1]和分子自旋电子学领域具有重要意义。[1，2]为了阐明分子内自旋排列与PET或EnT之间的关系，我们研究了图1所示的p-共轭自旋系统1（ADR），其中萘酰亚胺电子受体（A）通过作为供体（D）的蒽光敏部分共价连接到Verdazyl自由基（R）。在下文中，我们将苯基蒽-verdazyl自由基（DR）称为母体自由基3 [4c]（参见辅助信息的图S1）。从有机分子自旋电子学和材料科学的角度来看，这种p-共轭自旋系统具有以下优点：[4，5] 1）p-共轭自旋系统具有较强的交换耦合，与其他三重态/自由基对系统（s-键合系统[6]和配位络合物[7]）相比，这导致了稳健的自旋对齐。2)在p-共轭体系中，通过考虑p-电子网络的拓扑结构（p-拓扑结构），可以很好地设计具有所需自旋状态的分子。3)一个增强的系统间交叉（ISC）机制，由于自由基物种的附件是可用的。[4b强交换耦合和增强的ISC所开辟的新途径对于自旋转移的磁控制是重要的，这是分子自旋电子学的一个基本问题。动态的多功能自旋系统，如与定域自旋耦合的巡游电子，是自旋电子学的一个研究热点。[2]在光激发态，PET和EnT是最常见的动力学过程。因此，我们的系统是研究动力学过程和自旋排列的合适模型系统。[4d]在我们以前的论文中，[5]我们使用了具有bodipy [9]组分（1D* 的着名能量受体[9]）的三元组系统2，我们报道了光激发四重态中独特的动态电子极化的第一个证据。因此，在先前的工作中，
Intramolecular spin alignment, photoinduced electron transfer (PET), energy transfer (EnT), and spin dynamics via p-conjugation in organic radicals are quite important processes in organic molecular spintronics [1, 2] as well as for the photocontrol of organic magnetism.[3] Studies of spin manipulation using a dynamic process are significantly important in the fields of molecular magnetism [1] and molecular spintronics.[1, 2] To clarify the relationship between the intramolecular spin alignment and PET or EnT, we investigated a p-conjugated spin system 1 (ADR) shown in Figure 1, in which a naphtalimide electron acceptor (A) is covalently linked via an anthracene photosensitive moiety as donor (D) to the verdazyl radical (R). Hereafter, we refer to the phenylanthracene-verdazyl radical (DR) as the parent radical 3 [4c](see Figure S1 of the Supporting Information). Such p-conjugated spin systems have the following advantages in the view of forthcoming organic molecular spintronics and materials science:[4, 5] 1) p-Conjugated spin systems have a strong exchange coupling that leads to a robust spin alignment compared to other triplet/radical-pair systems (s-bonded systems [6] and coordination complexes [7]). 2) In p-conjugated systems, molecules with the desired spin state can be well-designed by taking the topology of the p-electron network (p-topology) into account. 3) An enhanced intersystem crossing (ISC) mechanism due to the attachment of the radical species is available.[4b, 8] The strong exchange coupling and the new pathway opened by the enhanced ISC are important to the magnetic control of the spin transfer, which is a fundamental issue of molecular spintronics. Dynamic multifunctional spin systems, such as itinerant electrons coupled to a localized spin, are a current topic of the spintronics.[2] In the photoexcited state, PET and EnT are the most common dynamic processes. Therefore, our systems are suitable model systems to study the dynamic processes and spin alignment.[4d]In our previous papers,[5] in which we used a triad system 2 with a bodipy [9] component (a well-known energy acceptor [9] for 1D*), we reported the first evidence of a unique dynamic electron polarization in the photoexcited quartet state. Thus, in that previous work, the