Selective and sensitive dual colorimetric cyanide and fluorescent azide probe

IR-780 is aheptamethine cyanine dye that exhibits strong absorbance in the near infrared region. Herein, we are reporting the use of IR-780 dye as a dual sensor for chromogenic detection of cyanide and fluorogenic sensing of azide in acetonitrile. Cyanide causes instant, dramatic color change of the dye solution from green to yellow, in addition to dramatic spectral changes in the UV-Vis spectrum. Interaction of cyanide with the dye caused a dramatic decrease in the intensity of the strong absorption band at 780 nm and a concomitant appearance of a band at 435nm. Other monovalent ions including fluoride, chloride, bromide, iodide, dihydrogen phosphate, thiocyanate, and acetate caused no significant color or spectral changes. UV-Vis studies showed that the IR-780 dyeis very sensitive and selective to cyanide. The limit of detection for cyanide in acetonitrile was 0.39 µM. Interestingly, the IR-780 dyeexhibited strong fluorescence at 535nm upon interaction with azide while its initial emi...