Chemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram 695 019, India.
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 200 002, India.
J Phys Chem B. 2021 Aug 5;125(30):8539-8549. doi: 10.1021/acs.jpcb.1c04417. Epub 2021 Jul 27.
This paper reports the self-assembly of a donor-acceptor system into nanoscopic structures and the photo processes taking place within these structures. The donor employed is pyrene linked to two β-cyclodextrin molecules (CD-PY-CD), and adamantane-linked methyl viologen attached to the three arms of mesitylene (Ms-(MV-AD)) is the acceptor. CD-PY-CD and Ms-(MV-AD) when dissolved in water self-assembled into vesicles, which joined together to give long fibers. The self-assembly was studied using spectroscopic and microscopic techniques. Fluorescence of the pyrene chromophore was quenched within the self-assembled system due to efficient photoinduced electron transfer to methyl viologen. Photoinduced electron transfer within the assembly is confirmed through identification of product radical ions in flash photolysis experiments. Steady-state irradiation of the self-assembled system in an optical bench led to the formation of methyl viologen radical cation, which was stable for a few hours. Longevity of the radical cation was attributed to the fast reaction of pyrene radical cation with adjacent pyrene to give an unstable adduct, which slows down the back electron transfer process.
本文报道了供体-受体体系自组装成纳米结构以及这些结构内发生的光过程。所采用的供体是连接到两个β-环糊精分子的芘（CD-PY-CD），而连接到均三甲苯三个臂上的金刚烷联吡啶甲基盐（Ms-（MV-AD））是受体。CD-PY-CD 和 Ms-（MV-AD）在水中自组装成囊泡，这些囊泡相互连接形成长纤维。自组装使用光谱和显微镜技术进行了研究。由于芘发色团与甲基紫精之间发生有效的光诱导电子转移，因此在自组装体系中芘发色团的荧光被猝灭。通过在闪光光解实验中鉴定产物自由基离子，证实了在组装体内部的光诱导电子转移。在光学台架上对自组装体系进行稳态辐照导致甲基紫精自由基阳离子的形成，其稳定数小时。自由基阳离子的寿命归因于与相邻芘发生快速反应，生成不稳定的加合物，从而减缓了反向电子转移过程。
