An Efficient Molecular Scaffold Exhibiting Fluorescence “Turn–On” Response for Cyanide and HCN

The present work describes design and synthesis of a biphenylaldimine derivative, probe 2 as an efficient molecular scaffold. The probe 2 showed good photophysical behavior and upon interaction with anions and gases showed high selectivity and sensitivity for CN ‐ anion and HCN gas through a reaction based chemodosimeter approach with limit of detection 24 ppb and 7 ppm, respectively. The change in optical behavior of the probe is attributed to intramolecular charge transfer (ICT) mechanism. Probe 2 displayed enhanced emission, “ turn‐on ” due to the formation of a new biphenyl oxazole derivative 4 in the medium along with change in color of the medium which was sensitive to the naked‐eyes. The mechanism of interaction between probe and cyanide anion have been confirmed by the 1 H NMR, 13 C NMR and HRMS spectral data analysis. The molecular probe 2 has been successfully utilized to detect cyanide (CN ‐ ) and HCN gas in solution and on test paper strips.