Ratiometric fluorescent sensing of ethanol based on copper nanoclusters with tunable dual emission.

Copper nanoclusters (Cu NCs) have attracted a surge of interest in fluorescent sensors as their outstanding physicochemical and optical properties. However, most of the reports have focused on single-signal fluorescent sensors, which are susceptible to background interferences and affect accuracy of the results. Herein, we constructed a facile ratiometric fluorescent sensor for monitoring ethanol based on Cu NCs with tunable dual emission. Polyvinylpyrrolidone (PVP)-modified Cu NCs were simply prepared in water, which exhibit ratiometric dual emission, including a strong green emission at 520 nm and a weak blue emission at 450 nm. The PVP-Cu NCs in water with strong green emission display monodisperse state due to the formation of hydration shell around Cu NCs. In ethanol where the hydration shell is destructed, Cu NCs tend to aggregate and show strong blue emission. This emission shift might attribute to the enhancement of Cu–Cu metallophilic interaction with the aggregation of Cu NCs, which induces the excited-state level increasing. Thus, a ratiometric fluorescent probe for ethanol based on the PVP-Cu NCs is fabricated, which possesses rapid response (<1 min), and realize full-range detection from 0 to 100%. In addition, this ratiometric probe is successfully applied to determine the alcohol strength of alcohol beverages, demonstrating the great potential in practical application. A facile and label-free ratiometric fluorescent probe for sensing ethanol contents in water was proposed based on the PVP-Cu NCs with unique ethanol-induced blue shift of emission property. [Display omitted] • The PVP-Cu NCs were prepared with ratiometric dual emission. • A facile ratiometric fluorescent probe was designed for sensing ethanol in water. • This probe has rapid response rate (<1 min) and full detection range from 0 to 100%. • This probe has great anti-interference capacity, and was successfully used in real sample. [ABSTRACT FROM AUTHOR]