Analytical Sciences

Abstract − Analytical Sciences, 22(3), 465 (2006).

Visual Detection of Anions by a Novel Isothiourea-based Chromophore
Ryo KATO,* Eriko TUBOUCHI,** and Toshiaki HATTORI**
*Cooperative Research Facility Center, Toyohashi University of Technology, Toyohashi 441-8580, Japan
**Department of Materials Science, Toyohashi University of Technology, Toyohashi 441-8580, Japan
S-Methyl-N-methyl-N′-(4-(N″,N″-dimethylamino)phenyl)isothiourea, a novel isothiourea-based chromoionophore for anions, was synthesized. The reactivity for several anions was estimated by a visual method and UV-vis spectroscopy. By the addition of acetate ion, a blue shift in the absorption spectrum was observed in CHCl3, and the solvent color changed from yellow to colorless. These changes indicated that bound acetate ion interfered with the intramolecular charge transfer from the nitrogen atom of the diethylamino group to the isothiourea moiety. The addition of chloride ion caused a red shift of the chromophore and solvent color remained yellow. By the addition of dihydrogenphosphate ion, the precipitate was formed immediately. These anion-dependent natures of the chromoionophore allowed us to detect acetate and phosphate ions easily.