A dual-site controlled fluorescent sensor for the facile and fast detection of H2O in D2O by two turn-on emission signals

Currently, the fluorescent sensors for the detection of H2O in D2O are still quite rare. Herein, we present a dual-site controlled fluorescent sensor (CF-D2O) for the H2O detection in D2O. As the H2O content in D2O decreases (namely, the purity of D2O increases), the sensor CF-D2O provides two turn-on fluorescent signals. The response mechanism of the sensor CF-D2O to H2O is on the basis of the deprotonation of the two hydroxyl groups, as well as the FRET process between coumarin and xanthene units.