Cyanide Sensing with Organic Dyes: Studies in Solution and on Nanostructured Al₂O₃ Surfaces

Abstract

The synthesis of two new azo phenyl thiourea compounds and their optical response to different anions is reported herein. Solution studies in methanol indicate that cyanide induces a colour change in these dyes (whereas no changes are observed in the presence of other anions, such as F(-), Cl(-), Br(-), CH(3)COO(-), H(2)PO(4) (-), HSO(4) (-)). Interestingly, in DMSO these dyes are responsive not only to cyanide, but also to fluoride, acetate and dihydrogen phosphate. Each of these anions induces a different colour change. In the second part of the paper, we report the attachment of one of these dyes onto nanostructured TiO(2) and Al(2)O(3) films. The stability of these sensitised films to pH was studied and we concluded that the sensitised Al(2)O(3) films are more robust, and hence, better than the TiO(2) for anion sensing. The dye-sensitised Al(2)O(3) films were immersed in solutions of different anions and their response studied. The films can detect cyanide down to 3 ppm in aqueous solution with relatively good selectivity over other anions.

Bicinchoninic acid-based colorimetric chemosensor for detection of low concentrations of cyanide

“…Moreover, many of the methods require expensive instruments and chemicals that are not easily portable, cost-effective, or accessible. Thus, efforts have been devoted worldwide to design various chemosensors for detection of cyanide, via the formation of cyanide complexes with transition metals [25][26][27], nucleophilic addition reactions to carbonyl groups [28], displacement reactions [29], hydrogen-bonding interactions [30], and deprotonation [31]. However, many of these cyanide chemosensors also suffer from several drawbacks such as poor selectivity, demanding high temperature or basic media to work, functioning only in an organic environment, and requiring complicated synthesis [25,[32][33][34].…”

Fluorescent and chromogenic probes bearing salicylaldehyde hydrazone functionality for cyanide detection in aqueous solution

“…Several strategies have been developed to detect cyanide, including the formation of cyanide complexes with transition metals [7][8][9], boron derivatives [10,11] and CdSe quantum dots [12], hydrogen-bonding interactions [13,14], deprotonation [15], luminescence lifetime measurement [16] and nucleophilic addition reactions [17][18][19][20][21][22][23][24][25][26][27][28][29][30]. We are especially interested in nucleophilic reaction-based receptors, because this type of sensing system takes advantage of the particular feature of the cyanide ion: its nucleophilic character, and enables the recognition system with some characteristic features such as analyte-specific response and little competition from the aqueous media, which are highly desirable features for an efficient recognition and detection system.…”

TDDFT Study on Different Sensing Mechanisms of Similar Cyanide Sensors Based on Michael Addition Reaction

“…: +86-411-84379692. FAX: +86-411-84675584 thesized two new azophenyl thiourea sensors [6] to detect cyanide based on the hydrogen-bond interaction, and they showed good selectivity over other anions in both solution and supported onto Al 2 O 3 nanostructured films. Ganesh et al used the Cu-complex as the cyanide sensor system to design an SAM-modified gold electrode [7], in which the copper ions could be removed by cyanide anions.…”