Fujimura Takuya, Ramasamy Elamparuthi, Ishida Yohei, Shimada Tetsuya, Takagi Shinsuke, Ramamurthy Vaidhyanathan
Department of Physics and Materials Science, Interdisciplinary Graduate School of Science and Engineering, Shimane University, 1060 Nishi-kawatsu-cho, Matsue, Shimane 690-8504, Japan and Department of Applied Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-osawa, Hachioji, Tokyo 192-0397, Japan.
Department of Chemistry, University of Miami, Coral Gables, Florida 33146-0431, USA.
Phys Chem Chem Phys. 2016 Feb 21;18(7):5404-11. doi: 10.1039/c5cp06984j.
To achieve the goal of energy transfer and subsequent electron transfer across three molecules, a phenomenon often utilized in artificial light harvesting systems, we have assembled a light absorber (that also serves as an energy donor), an energy acceptor (that also serves as an electron donor) and an electron acceptor on the surface of an anionic clay nanosheet. Since neutral organic molecules have no tendency to adsorb onto the anionic surface of clay, a positively charged water-soluble organic capsule was used to hold neutral light absorbers on the above surface. A three-component assembly was prepared by the co-adsorption of a cationic bipyridinium derivative, cationic zinc porphyrin and cationic octaamine encapsulated 2-acetylanthracene on an exfoliated anionic clay surface in water. Energy and electron transfer phenomena were monitored by steady state fluorescence and picosecond time resolved fluorescence decay. The excitation of 2-acetylanthracene in the three-component system resulted in energy transfer from 2-acetylanthracene to zinc porphyrin with 71% efficiency. Very little loss due to electron transfer from 2-acetylanthracene in the cavitand to the bipyridinium derivative was noticed. Energy transfer was followed by electron transfer from the zinc porphyrin to the cationic bipyridinium derivative with 81% efficiency. Analyses of fluorescence decay profiles confirmed the occurrence of energy transfer and subsequent electron transfer. Merging the concepts of supramolecular chemistry and surface chemistry we realized sequential energy and electron transfer between three hydrophobic molecules in water. Exfoliated transparent saponite clay served as a matrix to align the three photoactive molecules at a close distance in aqueous solutions.
为了实现能量转移以及随后跨越三个分子的电子转移这一目标（这一现象常用于人工光捕获系统），我们在阴离子型黏土纳米片表面组装了一个光吸收体（同时也作为能量供体）、一个能量受体（同时也作为电子供体）以及一个电子受体。由于中性有机分子没有吸附到黏土阴离子表面的倾向，因此使用带正电荷的水溶性有机胶囊将中性光吸收体固定在上述表面上。通过在水中将阳离子联吡啶衍生物、阳离子锌卟啉和阳离子八胺封装的2-乙酰蒽共吸附在剥离的阴离子黏土表面上，制备了一种三组分组装体。通过稳态荧光和皮秒时间分辨荧光衰减监测能量和电子转移现象。在三组分体系中对2-乙酰蒽的激发导致能量以71%的效率从2-乙酰蒽转移到锌卟啉。注意到从穴状配体中的2-乙酰蒽到联吡啶衍生物的电子转移造成的损失非常小。能量转移之后是电子从锌卟啉转移到阳离子联吡啶衍生物，效率为81%。荧光衰减曲线分析证实了能量转移和随后的电子转移的发生。融合超分子化学和表面化学的概念，我们实现了水中三个疏水分子之间的连续能量和电子转移。剥离的透明皂石黏土作为基质，使三种光活性分子在水溶液中近距离排列。
