Selective colorimetric sensing of Co(II) in aqueous media with a spiropyran-amide-dipicolylamine linkage under UV irradiation.

A spiropyran-amide-dipicolylamine linkage behaves as a colorimetric receptor for selective Co(2+) sensing in aqueous media under UV irradiation. This is promoted by strong coordination of Co(2+) with amide oxygens of the receptors and efficient photoisomerization of the spiropyran moieties.