Analytical Sciences

Effects of Cyclodextrins on Intramolecular Photoinduced Electron Transfer in a Boronic Acid Fluorophore

Hiroya KANO,* Daichi TANOUE,* Hiroaki SHIMAOKA,* Kohei KATANO,** Takeshi HASHIMOTO,** Hideyuki KUNUGITA,* Shinkoh NANBU,** Takashi HAYASHITA,** and Kazuhiro EMA*

*Department of Engineering and Applied Science, Faculty of Science and Technology, Sophia University, 7-1 Kioi-cho, Chiyoda, Tokyo 102-8554, Japan
**Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioi-cho, Chiyoda, Tokyo 102-8554, Japan

An inclusion complex consisting of a boronic acid fluorophore (C1-APB) and β-cyclodextrin (β-CyD) acts as a supramolecular sugar sensor whose response mechanism is based on photoinduced electron transfer (PET) from the excited pyrene to the boronic acid. We have investigated the PET process in C1-APB/CyD complexes by using time-resolved photoluminescence (TRPL) measurements at room temperature, and have succeeded in estimating the electron-transfer time to be about 1 ns. We have also studied the effects of CyDs on the PET process by comparing two kinds of CyDs (α-CyD, β-CyD) under different water–dimethyisulfoxide (DMSO) concentration conditions. We found that the CyDs interacting with the boronic acid moiety completely inhibits PET quenching and increases the monomer fluorescence intensity.

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