TURN-ON FLUORESCENT SENSORS FROM INDOLIUM SALT FOR CYANIDE DETECTION

Abstract

A highly sensitive turn-on fluorescent sensor for cyanide was developed based on benzylidenes containing methylindolium group. Three benzylidene derivatives were synthesized from the condensations of three benzaldehyde derivatives and methyleneindoline. Only the longest conjugated system of these three derivatives showed strong blue fluorescent response selectively to CN- which was clearly observed in submicromolar range as the result of the cyanide addition to the indolium group. The detection of cyanide with this compound was optimized in aqueous media using nonionic surfactant and sonication method to give very low limit of detection in subnanomolar range which nonorganic solvent in sensing system. The compound is also developed into a paper-based and gel-based sensing kits for on–site naked eye detection of cyanide in micromolar range under a common black light (360 nm) illumination.