Side chains of cobalt corrinoids control the sensitivity and selectivity in the colorimetric detection of cyanide.

Substitution of Co(III)-bound water by cyanide allows the rapid colorimetric detection of micromolar amounts of cyanide with cobalt corrinoids. Negatively charged side chains at the periphery of these metal-based sensors increase the selectivity of cyanide versus thiocyanate, the most disturbing anion, by a factor of 30 through additional supramolecular interactions in water.