A highly selective wavelength-ratiometric and colorimetric probe for cysteine

Based on the nucleophilic aromatic substitution reaction mechanism, a new highly selective probe for cysteine (Cys), N-butyl-4-bromo-3-nitro-1,8-naphthalimide (1), was designed and synthesized. The probe displayed a remarkable (58 nm) red-shift in the absorption spectra and the color changes from colorless to yellow upon reaction with Cys. The probe could detect Cys quantitatively in the range of 0 -0.9 mM by both normal and ratiometric absorption spectrometry methods. Moreover, 1 could also serve as a naked-eye probe for Cys with a minimum detectable concentration of approximately 50 mu M. (C) 2011 Elsevier Ltd. All rights reserved.