Detection of cyanide ions in aqueous solutions using cost effective colorimetric sensor

Cyanide (CN-) is one of the most toxic material to the human and environment. It is very important to develop the diagnostic tools for the detection of CN- ions. Moreover, detection of the ions in an aqueous medium is a challenging task as water molecules interfere with the sensing mechanism. In this context, we prepared chemical sensor, S1, having anthraquinone as a signaling unit and thiourea as a binding site. This sensor exhibited distinct visual color and spectral changes in response to CN- ion over other testing anions in 50% aq. DMSO solution. However, in 20% aq. DMSO solution, S1 exhibited obvious spectral and color changes in response to CN-, fluoride (F-), acetate (Ac-) and benzoate (Bz-). Another sensor, S2, having a same signaling unit with that of S1, but a different binding site of urea group. In contrast to S1, S2 exhibited obvious spectral and color changes to F- in 2.5% aq. DMSO solution. NMR titration results suggested that the spectral and colorimetric responses were due to the formation of host-guest complex and deprotonation events. Finally, economically viable paper-based colorimetric "test stripes" of S1 were fabricated to detect the CN- ions in 100% aqueous solution. (C) 2017 Elsevier B.V. All rights reserved.