A colorimetric and ratiometric fluorescent probe for detection of palladium in the red light region

Developing probes for selective and sensitive detection of palladium in living organisms is of great importance. In this work, we synthesized a colorimetric and ratiometric fluorescent probe (Probe 1) with red light emission (lambda(em) = 643 nm) by employing an isophorone based fluorescent dye as the fluorophore and an allylcarbamate group as the response unit. Based on the Pd-0-triggered cleavage reaction, Probe 1 showed high response speed, selectivity, and sensitivity towards palladium species. Upon addition of palladium, the absorption and emission spectra of Probe 1 exhibited obvious red-shifts, which can be easily discriminated by the naked eye. In terms of palladium, the detection limit is as low as 24.2 nM and the signal-to-noise ratio in fluorescence intensity can reach 85-fold. As a red emitting ratiometric sensor, Probe 1 can be potentially used for quantitative detection of palladium in living organisms.