Specific naked eye sensing of cyanide by chromogenic host: studies on the effect of solvents

We have synthesized receptor 1, which showed high selectivity toward CN− over other competitive anions in protic solvents. In addition, it distinguished CN− from other anions by color changes. Furthermore, its detection limit is far below the WHO guidelines of drinking water. However, in aprotic solvents such as acetonitrile, the unique selectivity for CN− disappeared, and the nonselective color change was observed for strongly basic anions such as F−, AcO−, and H2PO4−. These results suggest that receptor 1 interacts with cyanide with different mechanisms depending on solvents. The interaction mechanisms between 1 and cyanide in protic and aprotic solvents were investigated.