Balan Bijitha, Gopidas Karical R
Photosciences and Photonics Section, Chemical Sciences and Technology Division, Regional Research Laboratory (CSIR), Trivandrum--695019, India.
Chemistry. 2006 Aug 25;12(25):6701-10. doi: 10.1002/chem.200501548.
Photoinduced electron transfer (PET) between alpha-cyclodextrin-appended pyrene (PYCD) and a few acceptor molecules was studied in aqueous solutions. The pyrene moiety in PYCD is located above the narrower rim of the alpha-CD and is fully exposed to water. The acceptors are monocyclic organic molecules and, upon dissolution in water in the presence of PYCD, a fraction of the donor-acceptor systems is present as supramolecular dyads and the remaining fraction as free molecules. Free-energy-dependence studies showed that electron transfer in the supramolecular dyads follows the Marcus equation. The donor-acceptor coupling and the reorganization energy were determined from fits of the data to the Marcus equation. The electronic coupling was found to be similar to those reported for hydrogen-bonded systems. It appears that the actual lambdaout values are somewhat lower than values calculated with the continuum model. The experimental design has also allowed, for the first time, a visual demonstration of the inverted region on the basis of the raw fluorescence lifetime data.
在水溶液中研究了α-环糊精连接芘（PYCD）与几种受体分子之间的光致电子转移（PET）。PYCD中的芘部分位于α-环糊精较窄边缘上方，完全暴露于水中。受体是单环有机分子，在PYCD存在下溶解于水中时，一部分供体-受体体系以超分子二元体形式存在，其余部分以自由分子形式存在。自由能依赖性研究表明，超分子二元体中的电子转移遵循Marcus方程。通过将数据拟合到Marcus方程来确定供体-受体耦合和重组能。发现电子耦合与报道的氢键体系相似。似乎实际的λout值略低于用连续介质模型计算的值。该实验设计还首次基于原始荧光寿命数据直观展示了反转区域。
