Paper-based sensor based on lead-free manganese halide for the determination of water content in organic solvents.

A highly stable and luminescent lead-free manganese(II) halide hybrid MnBr4(TMN)2 (C34H42Br4MnN4) was designed and synthesized by introducing a large cationic organic spacer. The MnBr4(TMN)2 displays high luminescence with quantum yields up to 77% and possesses turn-off fluorescence behavior (Ex/Em=365/546 nm) for water. These properties make the MnBr4(TMN)2 a promising candidate as an alternative indicator for the detection of water with potential applications for the fabrication of LEDs. Herein, a paper-based sensor based on MnBr4(TMN)2 is described for the determination of water content in organic solvents. The mechanism of water sensing can be tentatively explained by fluorescence quenching originating from the destruction of water due to the Mn–Br bonds of MnBr4(TMN)2. The MnBr4(TMN)2-based paper sensor exhibits an excellent discrimination ability of water content in the range 0–25.0% with a detection limit of 0.27%. Satisfactory recoveries (94.91±4.09% to 103.23±2.38%) are obtained in spiked ethanol solvent samples, which demonstrate that the MnBr4(TMN)2-based paper sensor is capable of detecting water content in real ethanol solvent samples. [ABSTRACT FROM AUTHOR]