Analytical Sciences

Abstract − Analytical Sciences, 30(11), 1045 (2014).

Solvent Effect on the Fluorescence Response of Hydroxycoumarin Bearing a Dipicolylamine Binding Site to Metal Ions
Hiroyuki KOBAYASHI, Kohei KATANO, Takeshi HASHIMOTO, and Takashi HAYASHITA
Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioi-cho, Chiyoda, Tokyo 102-8554, Japan
The fluorescence behavior of a probe dpa-HC, which has a coumarin derivative that acts as a fluorophore and a dipicolylamine (DPA) unit that functions as a metal ion-recognition site, was investigated with various metal ions in aqueous and several non-aqueous solvents. In aqueous solution, the fluorescence of dpa-HC was enhanced by Zn2+ and Cd2+, but was quenched by other metal ions. On the other hand, in an acetonitrile solution, only Mg2+ enhanced the fluorescence, and the addition of a small amount of water quenched this fluorescence. This dramatic selectivity change is explained by stabilization of a metal-dpa-HC complex due to acetonitrile coordination and ON-OFF switching of the intramolecular photoinduced electron transfer (PET) from the nitrogen lone pair of DPA to the coumarin derivative.