Extremely Long Lived Localized Singlet Diradicals in a Macrocyclic Structure: A Case Study on the Stretch Effect
Extremely Long Lived Localized Singlet Diradicals in a Macrocyclic Structure: A Case Study on the Stretch Effect
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大环结构中寿命极长的局域单线态双自由基：拉伸效应的案例研究
DOI：
10.1002/chem.201803076
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Abe Manabu
中科院分区：
文献类型：
--
作者：
Harada Yuta;Wang Zhe;Kumashiro Shunsuke;Hatano Sayaka;Abe Manabu
定域单重态双自由基不仅在键均裂化学领域，而且在非线性光学材料领域都引起了广泛的关注。在这项研究中，通过使用一种新的分子设计策略获得了一种寿命极长的定域单线态双自由基，其中通过大环增加相应σ键合化合物的分子应变来动力学稳定它。值得注意的是，该双自由基的寿命（14 μs）比没有大环结构的标准单重态双自由基的寿命（10.2 μs）在293 K时长两个数量级。 该物种在100 K以下是持久的。 除了单重态双自由基的动力学稳定之外，其相应的闭环化合物在298 K下的自发氧化在大气条件下产生含氧产物。 显然，由大环结构引起的“拉伸效应”在延长局域单线态双自由基的寿命和增加其相应的σ键合化合物的反应性方面起着至关重要的作用。
Localized singlet diradicals have attracted much attention, not only in the field of bond‐homolysis chemistry, but also in nonlinear optical materials. In this study, an extremely long lived localized singlet diradical was obtained by using a new molecular design strategy in which it is kinetically stabilized by means of a macrocycle that increases the molecular strain of the corresponding σ‐bonded compound. Notably, the lifetime of this diradical (14 μs) is two orders of magnitude longer than that of a standard singlet diradical without a macrocyclic structure (≈0.2 μs) at 293 K. The species is persistent below a temperature of 100 K. In addition to the kinetic stabilization of the singlet diradical, the spontaneous oxidation of its corresponding ring‐closed compound at 298 K produced oxygenated products under atmospheric conditions. Apparently, the “stretch effect” induced by the macrocyclic structure plays a crucial role in extending the lifetime of localized singlet diradicals and increasing the reactivity of their corresponding σ‐bonded compounds.