An easy to make chemoreceptor for the selective ratiometric fluorescent detection of cyanide in aqueous solution and in food materials

A simple easy to make chemoreceptor (R) has been synthesized from commercially available starting materials by single step condensation at RT in good yield. The receptor has been characterized using H-1 and C-13 NMR and mass spectral techniques. R acts as an efficient ratiometric fluorescent probe for the selective detection of cyanide in aqueous solution (DMSO-H2O 20-80% v/v) with an instantaneous colour change from yellow-orange to green under a UV lamp in the 4-8 pH range. The detection of cyanide occurs via deprotonation of a phenolic -OH group by a cyanide ion as evidenced from a H-1 NMR titration experiment. The probe interacts with cyanide in a 1:1 stoichiometric manner with a detection limit of 0.96 M. The probe R is able to exhibit a similar fluorescence change with extracts of cyanide-containing food materials such as almond, cassava powder and potato. DFT computations well substantiate the results of spectral studies.