A novel fluoride selective optical chemosensor based on internal charge transfer signaling

A new internal charge transfer probe, NAPH-1, synthesized by incorporating photoemitive naphthalimide core with an acidic imidazolium ring, offers highly selective colorimetric and ratiometric 'off-on' signaling for targeting F-, while Cl-, Br-, I-, HSO4-, SCN-, AcO-, and NO3- do not appreciably perturb the photophysical properties of the probe even at relatively higher concentrations than the F-. Deprotonation of the imidazolium ring, supported by the H-1 NMR and theoritical studies, seems to cause the spectral modulations. (C) 2009 Elsevier Ltd. All rights reserved.