Cyanide detection using a benzimidazole derivative in aqueous media

•Receptor S1 shows highly sensitive fluorescence turn on response for CN−.•Sensor S1 demonstrates specifically selective fluorescence recognition to CN−.•Test strips of S1 were prepared and convenient and rapidly detected CN−.•The probe S1 responded with CN− in aqueous solution system.•Chemosensor S1 was designed with ease of synthesis.

A novel cyanide selective fluorescent chemosensor S1 based on benzimidazole group and naphthalene group as the fluorescence signal group had been designed and synthesized. The receptor could instantly detect CN− anion over other anions such as F−, Cl−, Br−, I−, AcO−, H2PO4−, HSO4−, SCN− and ClO4− by fluorescence spectroscopy changes in aqueous solution (H2O/DMSO, 8:2, v/v) with specific selectivity and high sensitivity. The fluorescence color of the solution containing sensor S1 induced a remarkable color change from pale blue to mazarine only after the addition of CN− in aqueous solution while other anions did not cause obvious color change. Moreover, further study demonstrates the detection limit on fluorescence response of the sensor to CN− is down to 8.8 × 10−8 M, which is far lower than the WHO guideline of 1.9 × 10−6 M. Test strips based on S1 were fabricated, which could act as a convenient and efficient CN− test kit to detect CN− in pure water for “in-the-field” measurement. Thus, the probe should be potential applications in an aqueous environment for the monitoring of cyanide.

Graphical abstractA novel cyanide specifically selective and highly sensitive fluorescent enhanced chemosensor S1 based on benzimidazole group and naphthalene group was designed and synthesized.Figure optionsDownload full-size imageDownload as PowerPoint slide