Supramolecular Surface Photochemistry: Supramolecular Assembly Organized on a Clay Surface Facilitates Energy Transfer Between an Encapsulated Donor and a Free Acceptor
Supramolecular Surface Photochemistry: Supramolecular Assembly Organized on a Clay Surface Facilitates Energy Transfer Between an Encapsulated Donor and a Free Acceptor
复制标题
超分子表面光化学：粘土表面组织的超分子组装促进封装的供体和自由受体之间的能量转移
作者：
Ishida;Y.; Kulasekharan;R.; Shimada;T.; Ramamurthy;V.; Takagi;S.
我们报道了一种新型的由阴离子粘土纳米片、阳离子卟啉和包裹在阳离子有机空穴中的中性芳香族分子组成的新型主客体组装中发生的有效的能量转移反应。超分子组装是通过阳离子有机空穴中的四阳离子锌卟啉(受体)和2-乙酰基菲(给体)在阴离子粘土纳米片上的共吸附(质子化的辛胺)而制备的。在客体间距为2.4 nm的情况下，获得了近100%的单线态-单线态能量转移效率。详细的时间分辨荧光测量表明，能量转移速率常数可归因于单一组分(1.9×109s-1)。这有力地表明，卟啉和空穴的吸附分布是比较均匀的，而不是分离的。这是我们之前研究的一个进展，涉及到两个被包裹的中性分子之间的能量转移。本研究使用锌-卟啉作为能量受体，使得能量转移系统能够以与自然光合作用系统相同的方式连接到电荷分离过程，而且，两个空穴之间的能量转移反应的效率从以前的85%提高到近100%。
We report the occurrence of efficient energy transfer reaction in a novel host–guest assembly composed of an anionic clay nanosheet, cationic porphyrin, and neutral aromatic molecule encapsulated within a cationic organic cavitand. The supramolecular assembly was prepared by the coadsorption of tetracationic Zn–porphyrin (acceptor) and 2-acetylanthracene (donor) enclosed within cationic organic cavitand (octaamine in its protonated form) on anionic clay nanosheets. In this arrangement under the interguest distance of 2.4 nm, almost 100% efficiency of singlet–singlet energy transfer was achieved. Detailed time-resolved fluorescence measurements revealed that the energy transfer rate constant could be attributed to a single component (1.9 × 109s–1). This strongly suggests that the adsorption distribution of porphyrin and cavitand is rather uniform, not segregated. This is a progress from our previous study that involves energy transfer between two encapsulated neutral molecules. The use of Zn–porphyrin as an energy acceptor in this study enables to connect this energy transfer system to charge separation processes in the same manner as natural photosynthetic systems do; moreover, the efficiency of energy transfer reaction improved to almost 100% from 85% in the previous system between two cavitands.