Schiff base derived from salicylaldehyde-based azo dye as chromogenic anionic sensor and specific turn-on emission sensor for cyanide ion

A novel Schiff base has been derived from condensing 4-aminoantipyrine with diazotized salicylaldehyde. The derived compound acted as a colorimetric sensor for hazardous aqueous anions like CN-, F-, and CH3COO- among a list of anions. The colorimetric changes were further verified through absorption titrations. The detection limits were of the order of 10(-10) M, which makes the sensor significant. The interaction of the anions with the sensor was stoichiometrically 1:1 with good binding constants. The sensor turns out to be a specific turn-on emission sensor for CN- even in competitive environments. The F- ion sensing ability was extended to the determination of F- in a commercial toothpaste with good results.