Three Indole Derived Azo-Azomethine Dyes as Effective Chemosensors for F− Ion and Trace Water Detection

Abstract

Abstract Three new dyes 1–3 derived from indol-carbohydrazide and azo-azomethine for the optical detection of F− ion have been developed. Dye 1 was found to be an effective colorimetric sensor for F− ion response with over 250 nm red-shift. Moreover, the resultant dye⋯HF2− complex (dye-F) could be successfully used as a secondary sensor for analyzing trace water in aprotic organic solvents especially in acetonitrile with a low limit of detection. In addition to detection of low-level water content in solution, test paper incorporated with 1-F complex or 2-F complex was well developed for naked-eye detection of water content in four organic solvents as mentioned above. Importantly, the test paper prepared by introducing 1-F complex or 2-F complex could be developed to prepare an ink-free rewritable paper by using water as the sole trigger. Furthermore, the same test paper could still work for many cycles without obvious loss in color quality.