Amine-incorporated quinoxaline based fluorescent sensor for detection of trace water: Solvent influenced...

Polarity is a complex parameter, with important effect in chemistry and biology. In recent years, polarity exploration attracted more and more attention hence, it's of great importance to exploit new methods for polarity determination. A novel class of long, coplanar, and amine incorporated electron-rich quinoxaline scaffold(L₁) furnished maximum solvatochromic effect and large Stokes shift and was chosen to determine water content in organic solvents e.g. acetonitrile, THF, DMF, and methanol through fluorescence spectroscopy. Moreover, the probe was found to perform as an effective fluorescent sensor for the quantitative detection of low-level moisture content in four commonly-used organic solvents with low detection limits (0.018%, 0.027%, 0.012%, and 0.43% respectively). This study also describes the morphological transformation of L₁ form a fibrous network to spherical aggregates upon increasing water content in several organic solvents. Real-life implementation of the probe was successfully employed for the detection of moisture content in commercial food products and building materials such as cement, sand, limestone, salt, wheat, and detergent powder. Furthermore, probe L₁-immersed easy-to-prepare test strips provide a reliable approach for qualitative monitoring of water content in organic solvents by a simple color-changing method under UV irradiation via smartphone-assisted RGB analysis.