A dual-emission samarium-macrocycle complex and its high-efficient fluorescence detection of water

The development of highly selective and convenient fluorescence detection techniques to monitor water (H 2 O) remains a major challenge in various domains. In this article, a novel fluorescence sensing molecule Sm-1 f [Sm(HL1 f )(NO 3 ) 2 ] is rationally designed and synthesized, and Sm-1 f consists of a samarium ion, one deprotonated [1 + 1] Schiff-base macrocycle HL1 f − and two nitrates. This complex Sm-1 f then served as a solvent-response candidate in view of its dual-emission fluorescence and reversible structure. As a result, Sm-1 f shows the fast, selective and quantitative detection abilities for H 2 O among 13 common solvents. After the systematic statistical analysis for fluorescence signals of two channels, Sm-1 f also demonstrates excellent discrimination of 11 solvents and several pairs of solvent analogues, especially the H 2 O and D 2 O. Mechanistic studies confirm that the H 2 O-induced imine bond cleavage disrupts the sensitization effect of Schiff-base macrocycle which finally leads to a remarkable reduction of emission intensity. Furthermore, the smartphone-based RGB analytical technique enables the real-time and convenient detection of H 2 O without any complicated apparatuses. This work not only provides a powerful fluorescence probe and convenient technique for H 2 O detection but also expands the application of luminescent lanthanide materials.