Analytical Sciences

Abstract − Analytical Sciences, 22(5), 659 (2006).

The “Off-On” Fluorescence Detection of Alkaline Earth Metal Ions by Using 1-Naphthylacetanilide Derivatives: New Cation Sensors Based on Oligo-ethylene Oxides Connecting 1-Naphthylacetanilide at Its Terminals
Tatsuya MOROZUMI,* Hiroya HAMA,** and Hiroshi NAKAMURA*
*Section of Materials Science, Research Faculty of Environmental Earth Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
**Division of Environmental Material Science, Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
New fluorescent ionophores containing the 1-naphthylacetanilide moiety based on oligo-ethylene oxide (14 and 15) have been synthesized, and their photochemical behaviors have been studied. In the absence of a metal ion, the 1-naphthylacetanilide moiety showed a weak fluorescence emission (fluorescence “off state”). However, complexation with Ca2+ induced a large enhancement effect on the fluorescence intensity of 14 and 15 from the naphthalene ring (fluorescence “on” state). This behavior can be explained in terms of a similar twisted intramolecular charge-transfer relaxation mechanism. Such “off-on” fluorescence responses of 14 and 15 provide the digital detection of alkaline earth metal ions.