Project

Discipline

Cyanid; Corrinoide; Sensor; Kinetik

Lead
Lay summary
Goal of the research project: The development of colorimetric chemosensors for the highly selective and sensitive recognition of toxic cyanide in water is still a challenge in analytical chemistry. In this project we intend to design novel B12 derivatives with improved properties for cyanide sensing. Context and relevance of the project: Cyanide is highly toxic to humans and almost all other forms of life because of the binding to cytocrome oxidase that inhibits the mitochondrial electron transport chain. However, cyanide is produced in large quantities for different industrial applications like the production of synthetic fibres, gold mining or electroplating. Contrariwise cyanide is relatively common in nature, e.g. in the form of cyanogenic glycosides in plants like almonds, flax seed, bamboo shoots and cassava. The latter one is the staple food for about 600 million people in the tropical belt. The contents of cyanide in common foods can cause acute and chronic intoxication, a health problem that is still observed in the developing countries. A simple and cheep optical test for cyanide sensing could represent a useful analytical tool in resource limited areas. Scientific frame and methods: Various methods of cyanide detection based on electrometric, fluorometric and chromatographic techniques have already been developed, but drawbacks are the sensitivity and selectivity of the systems, the use of toxic reagents and the necessity of expensive analytical equipment. Based on our previous studies, we intend to develop improved metal based chemosensors that for the visual detection of cyanide. This effort will be supported by kinetic and mechanistic studies in order to elucidate the binding mechanism of cyanide to this class of receptors.

Direct link to Lay Summary

Last update: 21.02.2013

We communicated a class of corrinoids which allow the optical detection of µM of cyanide in a simple and highly specific system. This is one of the rare examples which work in pure water. The side chains of these sensors play an important role in respect of sensitivity and selectivity. In order to develop novel corrinoids with improved properties further kinetic and mechanistic studies are necessary. Furthermore, we intend to apply imidazole modified B12 derivatives as novel catalysts for cyanide detection. After cyanide induced decoordination of the imidazole catalyst from the Co centre the catalytic hydrolysis of esters results in a visible signal. The mode of operation is already predetermined by the structure of vitamin B12 and is related to the function of cobalamines as molecular switches in biological systems. At the beginning, the catalyst is inactive while the nucleobase base is protected by coordination to the metal centre.