Photoinduced charge separation in donor–acceptor conjugates plays a pivotal role in technology breakthroughs, especially in the areas of efficient conversion of solar energy into electrical energy and fuels. Extending the lifetime of the charge separated species is a necessity for their practical utilization, and this is often achieved by following the mechanism of natural photosynthesis where the process of electron/hole migration occurs distantly separating the radical ion pairs. Here, we hypothesize and demonstrate a new mechanism to stabilize the charge separated states via the process of electron exchange among the different acceptor entities in multimodular donor–acceptor conjugates. For this, star-shaped, central triphenylamine derived, dimethylamine–tetracyanobutadiene conjugates have been newly designed and characterized. Electron exchange was witnessed upon electroreduction in conjugates having multiple numbers of electron acceptors. Using ultrafast spectroscopy, the occurrence of excited state charge separation, and the effect of electron exchange in prolonging the lifetime of charge separated states in the conjugates having multiple acceptors have been successfully demonstrated. This work constitutes the first example of stabilizing charge-separated states via the process of electron exchange.

中文翻译：

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通过电子交换稳定电荷：对称中心三苯胺衍生的二甲氨基苯基-四氰基丁二烯供体-受体结合物中的激发电荷分离

供体-受体共轭体中的光致电荷分离在技术突破中发挥着关键作用，特别是在将太阳能高效转化为电能和燃料的领域。延长电荷分离物质的寿命是其实际应用的必要条件，这通常是通过遵循自然光合作用机制来实现的，其中电子/空穴迁移过程发生在远处分离自由基离子对。在这里，我们假设并证明了一种通过以下方式稳定电荷分离状态的新机制多模块供体-受体结合物中不同受体实体之间的电子交换过程。为此，新设计和表征了星形、中心三苯胺衍生的二甲胺-四氰基丁二烯共轭物。在具有多个电子受体的缀合物中电还原时见证了电子交换。使用超快光谱，已成功证明了激发态电荷分离的发生，以及电子交换在延长具有多个受体的缀合物中电荷分离态寿命的作用。这项工作构成了通过电子交换过程稳定电荷分离态的第一个例子。