Detection of cyanide ions using chemosensing ensembles under indicator displacement assays

Abstract

Anion recognition is an attractive area of research in recent decades as anions play an important role in a wide range of chemical, biological, and environmental processes. This dissertation reports three projects dedicated to anion recognition with applications in fluoride and cyanide sensing.

The first project of the dissertation describes the chemistry of two novel anthracene derivatives bearing one and two dimesitylboryl substituents (compounds 1 and 2, respectively) for the complexation of anions. All investigations provide insights into the electronic structure and effect of fluoride and cyanide binding. The results demonstrate that these boranes have a high affinity for fluoride and cyanide anions which form a 1 : 1 guest-host complex and display differences in UV-vis and fluorescence response due to their unique electronic structures.

Chemosensing ensemble approach is one of the main strategies gained considerable interest for anion sensing. Utilizing this approach to detect the toxic cyanide anion is the subject of the research discussed in the second and third projects. In the second project, colorimetric detection of cyanide is accomplished using dinuclear copper(II) complex of anthracene containing two tripodal tetramine moieties (Cu2L1) as a receptor, and pyrogallol red (PGR) as an indicator. The Cu2L1–PGR ensemble is able to detect cyanide selectively with limit of detection of 0.029 ppm. TD/DFT calculations indicate that the most stable Cu2L1–2PGR–2CN- complex is the dominant species in the equilibrium mixtures of the solution.

Finally, the last project focuses on the development of fluorometric and colorimetric sensing system, which is simple, rapid and cost-effective. Many emsembles using alizarin red S (ARS) as indicator and derivatives of phenyl boronic acid as receptor are tested. The best detection of cyanide is achieved by displacing the indicator in the ensemble of ARS indicator and 3-nitrophenyl boronic acid (NPBA) receptor. The optimum condition for the determination of cyanide ion by this sensing system is 1 : 4 ARS−NPBA complex in 0.01 M PBS pH 8.0.