Anionic chromogenic chemosensors highly selective for cyanide based on the interaction of phenyl boronic acid and solvatochromic dyes

- Solutions of two solvatochromic dyes are colored in acetonitrile.
- Solutions are colorless when a boronic acid (PBA) is added: dye-PBA species is formed.
- F− and CN− displace the dye leaving group, causing the reappearance of the color.
- The system becomes highly selective toward CN− on addition of small amounts of water.
- Water strongly solvates F−, but CN− is suitably naked to react with dye-PBA species.