Acidic microenvironment triggered release of a Cys probe from the cavity of a water-soluble pillar[5]arene

A Cys probe is prepared. It can be included into the cavity of a water-soluble pillar[5]arene. This WP5⊃probe complex shows no response toward Cys under neutral conditions in water, while the release of the Cys probe can be realized in an acidic microenvironment.