A naphthalene-based colorimetric and fluorometric dual-channel chemodosimeter for sensing cyanide in a wide pH range

Abstract

A novel α-ethoxynaphthalene-dicyanovinyl conjugate 1 with an intramolecular charge transfer (ICT) characteristic was synthesized for the highly selective and reactive detection of CN− in a wide pH range of 3–10. The colorimetric and fluorometric response of the sensor to CN− is attributable to the addition of CN− to the β-conjugated position of the dicyanovinyl group of 1, which blocks ICT. The sensing mechanism is supported by 1H NMR titration experiments and density functional theory (DFT) calculations. Moreover, chemodosimeter 1 shows strong yellow fluorescence in the solid-state, and 1-based test strips can be easily prepared at low-cost and can be used in practical and efficient test kits for CN− detection. The results provide the proof of concept that the ICT-based colorimetric and fluorometric cyanide-selective chemodosimeter can be created based on a simple alkoxy-substituted small molecule.