Fluoride Induced Dual Mode Moisture Detection in Organic Solvents, Food, and Agricultural Materials Using Benzothiazole Based Azo Dye Sensor

Moisture detection through naked eye is important in various fields, including pharmaceuticals, fuels, materials, and agriculture. In this study, we demonstrate the use of a strategically designed organic molecule, 2AMBP, for the detection of moisture in organic solvents and real-life samples. The principle behind this sensory system involves fluoride-induced deprotonation followed by water-induced re-protonation. The deprotonated form of 2AMBP displays a color-changing response (yellow to pink) even in trace amounts of water (LOD: 0.0207 % by spectrophotometric analysis), making it a highly sensitive probe for detecting moisture. We show that the anionic receptor moieties of 2AMBP can be employed for the quantification of water impurity in various real-life samples, and we develop inexpensive, reusable, dye-coated paper sensor for quick onsite moisture detection and quantification. Interestingly, a smart phone camera can be used to provide relative RGB values that directly correlate to the amount of moisture present in the sample. The 2AMBP-F- exhibits significant changes in fluorescence properties in the presence and absence of water, which makes it an effective fluorescent switch for detecting moisture. Overall, 2AMBP is a highly sensitive, sustainable material that can be conveniently used by laymen for moisture detection without the need for specific instruments or expertise.