Rational design of push-pull fluorescent probe with extraordinary polarity sensitivity for VOCs chromic sensing and trace water detection

Abstract

Developing fluorescent probes with excellent polarity sensitivity is still meaningful, but faces some challenges. Different from previous studies, this work focusses on modifying the π-bridge to improve the polarity-sensitivity, and found that taking quinoline with electron-deficient structure as π-bridge can significantly promote the intramolecular charge transfer from the electron-donor to electron-acceptor. Such modification on π-bridge endows fluorescent probe DQN with brilliant fluorescence which is highly sensitive to changes in environmental polarity. Based on it, the DQN-based test strips have been made for fast, visual, and reversible discrimination of four volatile organic compounds with varied polarities. Moreover, 92#, 95#, and 98# gasolines can be directly discriminated with DQN, showing completely different fluorescent colors under UV lamp. In addition, trace water in organic solvents can also be accurately detected, and their limits of detection are as low as 28 ppm (1,4-dioxane) and 16 ppm (tetrahydrofuran). In short, this work provides an inspirational perspective for the rational design of fluorescent probes with excellent polarity sensitivity for multifunctional applications.