Development of fluorescent sensing of anions under excited-state intermolecular proton transfer signaling mechanism

[GRAPHICS] A substantially red-shifted fluorescence emission in 3-hydroxyl-2-naphthanilide in acetonitrile was developed and drastically enhanced upon addition of anions such as F-, AcO-, and H2PO4-, with the enhancement depending on anion basicity. Excited-state intermolecular proton transfer in the sensor-anion hydrogen-bonding complex was suggested to be the signaling mechanism.