A dual-function fluorescence 'turn-on' probe that allows Zn (II) bioimaging and quantification of water in the organic solvent.

[Display omitted] • FLHE , a eugenol derivative-based fluorescence turn-on probe for detecting Zn2+ was introduced. • FLHE demonstrates the CHEF effect, making it an excellent fluorescence "turn-on" probe for Zn2+ detection. • FLHE showed a high sensitivity for the Zn2+ detection (LOD = 31.8 nM) in live cells and environmental samples. • FLHE -based paper strip (FLHE-PS) assay allows Zn2+ detection (LOD = 63.2 nM) in aqueous solutions. • FLHE -based paper strip (FLHE-PS) assay allows quantification of water (LOD of 0.14%) in the organic solvent. Herein, a Eugenol-derived fluorescence 'turn-on' probe FLHE was synthesized by condensing 2-((3-(trifluoromethyl)phenyl)amino)benzohydrazide with 5-allyl-2-hydroxy-3-methoxybenzaldehyde. FLHE demonstrated very low fluorescence in the studied organic solvents of varying polarities. However, upon titration with Zn2+ in HEPES buffer (pH = 7.4, 50% ACN, v/v), FLHE showed 40-fold higher fluorescence signals indicating the formation of the FLHE–Zn2+ complex. The fluorescence turn-on phenomenon upon FLHE–Zn2+ complex formation results from a chelation-enhanced fluorescence (CHEF) effect. The FLHE–Zn2+ complexation demonstrated a stokes shift of 156 nm (λ ex = 350 nm, λ em = 506 nm) and an about 33-fold increase in the quantum yield (FLHE , Φ = 0.007; FLHE–Zn2+ complex, Φ = 0.23). The binding constant (K a) determined by the Benesi-Hildebrand plot for interaction between FLHE and Zn2+ was 5.33 × 103 M−1. FLHE demonstrated a LOD of 31.8 nM for detecting Zn2+ in the environmental samples without interference from other cations and anions. FLHE -based paper strip (FLHE-PS) assay was developed to quantify the Zn2+ ions in water and the water content of organic solvent. FLHE-PS allows the detection of Zn2+ in aqueous solutions with a LOD of 63.2 nM and quantifying water in acetonitrile with a LOD of 0.14%. These results indicate that the FLHE has high applicability for detecting Zn2+ in living cells and environmental samples and detecting the presence of water in the organic solvents. [ABSTRACT FROM AUTHOR]