A water-soluble colorimetric two-photon probe for discrimination of different palladium species and its application in bioimaging.

A novel water-soluble colorimetric and fluorescent palladium probe with excellent selectivity and sensitivity has been designed. Notably, based on a palladium triggered terminal allyl ether cleavage reaction, the probe could detect and discriminate Pd(0) and Pd(2+)/Pd(4+) in about 2.5 min at room temperature with a low detection limit (0.29 ppb) and significant colour change (from light yellow to pink). The probe could serve as an excellent "naked-eye" colorimetric probe for selective and quantitative determination of palladium in aqueous solutions. Moreover, it could be used as a two-photon palladium probe for in vitro/vivo and three-dimensional imaging with low cytotoxicity and autofluorescence.