Regulating intermolecular hydrogen bonding to construct solvation-induced emission shift quinoline derivatives for real-time monitoring of water content in organic solvents

Water constitutes the most prevalent impurity in organic solvents, exerting significant influence on chemical reactions and potentially leading to fires and explosions, even in minute quantities. Thus, the development of convenient, rapid, and cost effective fluorescent probes for real-time monitoring of water content in organic solvents is imperative. Although some fluorescent materials have been synthesized for this purpose, most suffer from laborious preparation processes and poor cycling performance, constraining their practical application. This study investigates the impact of hydrogen bonding on the aggregation-induced emission (AIE) properties of quinoline derivatives, leveraging quinoline as the foundational scaffold and its nitrogen atom as the hydrogen bond acceptor. Research findings elucidate that intermolecular hydrogen bonding of quinoline is the primary determinant of their AIE behaviors. By harnessing the phenomenon of water molecules forming intermolecular hydrogen bonds with quinoline nitrogen atoms, we devised a straightforward and rapid method to fabricate a fluorescent test paper for real-time monitoring of water content in organic solvents. Experimental results demonstrate that even minute changes in water content, down to concentrations as low as 0.5 % by volume in organic solvents, can induce fluorescence changes in the test paper, which also exhibits favorable cycling performance. This study not only explores the influence of hydrogen bonds on the AIE properties of quinoline derivatives but also pioneers the development of a cost-effective, rapid, and recyclable test paper for real-time monitoring of water content fluctuations in organic solvents.