Simple and effective detection of water in hygroscopic organic solvents using smartphone-based device with dithiophene-conjugated benzothiazole

A dithiophene-bearing benzothiazole derivative (DTBz) was synthesized as a moisture-sensitive fluorescent probe for the detection of water in hygroscopic solvents. In a mixture of water and organic solvents, such as THF, 1,4-dioxane, MeOH, and EtOH, the fluorescence intensity of DTBz showed ratiometric changes in response to the content of water in the organic solvents. Moreover, the emission color of DTBz changed drastically from blue to red, which facilitated the development of the smartphone-assisted fluorometric device using image analysis. The custom smartphone-based device allowed water detection over the range of 0–60% with a resolution of 0.1% in the range of 0–1%. The detection sensitivity was as low as 0.05%. The total assay time was estimated to be approximately 6 min. The custom device would be very useful for determining the water content of various hygroscopic organic solvents over a wide range. [Display omitted] •An efficient moisture-sensitive fluorescent probe was designed.•The probe exhibited emission change over a wide range of water contents in hygroscopic solvents.•A smartphone-based custom device was designed for simple and effective detection of water.