A new AIE and TICT-active tetraphenylethene-based thiazole compound: Synthesis, structure, photophysical properties and application for water detection in organic solvents

A new thiazole derivative 2-(4-nitropheny1)-6-(1,2,2-triphenylvinyl)benzo[d]thiazole (TBTNO2) based on tetraphenylethene (TPE) was designed and synthesized. The structure has been fully characterized by NMR, MS, elemental analysis and single crystal X-ray diffraction analysis, and its properties were analyzed by spectroscopy and theoretical study. Under the combined action of twisted intramolecular charge transfer (TICT) and aggregation-induced emission (AM), TBTNO2 exhibits extraordinary "on-off-on" optical switching property accompanied by changes of the emission color with the addition of water into its tetrahydrofuran (THF) and dioxane (Diox) solution. Interestingly, TBTNO2 is highly sensitive to trace water in organic solvents such as THF, Diox, ethyl acetate (EA) and diethyl ether (DEE), making TBTNO2 be a highly sensitive fluorescent sensor for water detection with a detection limit of 0.019% for THF, 0.076% for Diox, 0.092% for EA and 0.103% for DEE (v/v), respectively. The measuring results of trace water in real samples using TBTNO2 as the sensor are well consistent with those of the Karl Fischer method. TBTNO2 can be employed as a sensitive indicator to monitor trace water during the drying process for organic solvents conveniently. In addition, compound TBTNO2 exhibits large Stokes shift and significant solvatochromic effect. (C) 2018 Elsevier B.V. All rights reserved.