Chemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram 695 019, India.
Academy of Scientific and Innovative Research (AcSIR), New Delhi 110001, India.
J Phys Chem B. 2020 Oct 29;124(43):9546-9555. doi: 10.1021/acs.jpcb.0c05410. Epub 2020 Oct 15.
Efficiencies of artificial photosynthetic and photocatalytic systems depend on their ability to generate long-lived charge-separated (CS) states in photoinduced electron transfer (PET) reactions. PET, in most cases, is followed by an ultrafast back electron transfer, which severely reduces lifetime and quantum yield of CS states. Generation of a long-lived CS state is an important goal in the study of PET reactions. Herein, we report that this goal is achieved using a hierarchically self-assembled anthracene-methyl viologen donor-acceptor system. Anthracene linked to two β-cyclodextrin molecules (CD-AN-CD) and methyl viologen linked to two adamantane units (AD-MV-AD) form an inclusion complex in water, which further self-assembled into well-defined toroidal nanostructures. The fluorescence of anthracene is highly quenched in the self-assembled system because of PET from anthracene to methyl viologen. Irradiation of the aqueous toroidal solution led to formation of a long-lived CS state. Rational mechanisms for the formation of the toroidal nanostructures and long-lived photoinduced charge separation are presented in the paper.
人工光合作用和光催化系统的效率取决于它们在光诱导电子转移 (PET) 反应中产生长寿命电荷分离 (CS) 态的能力。在大多数情况下，PET 之后会发生超快的反向电子转移，这严重降低了 CS 态的寿命和量子产率。生成长寿命的 CS 态是 PET 反应研究中的一个重要目标。在此，我们报告使用分级自组装蒽-甲基紫精给体-受体体系实现了这一目标。蒽通过两个 β-环糊精分子（CD-AN-CD）连接，甲基紫精通过两个金刚烷单元（AD-MV-AD）连接，在水中形成包合物，进一步自组装成具有良好定义的环形纳米结构。由于蒽到甲基紫精的 PET，蒽的荧光在自组装体系中被高度猝灭。环形水溶液的辐照导致长寿命 CS 态的形成。本文提出了形成环形纳米结构和长寿命光致电荷分离的合理机制。
