A novel oligothiophene-based colorimetric and fluorescent “turn on” sensor for highly selective and sensitive detection of cyanide in aqueous media and its practical applications in water and food samples

[Display omitted] •A new oligothiophene-based naked-eye colorimetric and fluorescent turn-on sensor 3TT was developed.•3TT exhibited high selectivity and sensitivity for rapid detection of CN−.•The low detection limit of sensor 3TT for CN− is 39.9nM.•3TT-based test strips were used to efficiently detect CN− in water by naked eyes.•3TT was successfully applied to detect trace CN− in water and food samples. A novel oligothiophene-based naked-eye colorimetric and fluorescent turn-on sensor 3TT with a typical donor-π-acceptor structure has been successfully developed, which displayed excellent selectivity and sensitivity for the dual-channel detection of toxic cyanide (CN−) in 70% aqueous THF media due to the nucleophilic addition of CN− to the β-conjugated position of the barbituric acid moiety of the sensor 3TT by hampering intramolecular charge transfer (ICT) process. The cyanide sensing mechanism was confirmed by optical spectral studies, FT-IR spectra, 1H NMR titration, HRMS spectra and DFT calculations. Sensor 3TT for the naked-eye detection of CN− in aqueous media exhibited high anti-interference ability, immediate response (20s), extremely low detection limit (39.9nM) as well as wide pH response range. Moreover, sensor 3TT displays excellent sensing performance in the solid state, and the 3TT-based test filter papers strips were used to conveniently and efficiently detect CN− in water by naked eyes. Furthermore, the sensor 3TT was successfully applied to the rapid detection of cyanide in real water samples, bitter seeds and food samples, demonstrating its great potential for practical applications in our daily life and environment.