Reporting the release of caged species by a combination of two sequential photoreactions, a molecular switch, and one color of light.

In the right light: UV light triggers bond breaking, liberates a caged carboxylic acid, and generates the central C=C double bond in the photoresponsive hexatriene molecule of a dithienylethene molecular switch. Light of the same wavelength converts the colorless isomer into its colored counterpart in a visually convenient method to report on the success of the release event.