C─H···πinteraction induced H-aggregates for wide range water content detection in organic solvents

J-aggregation and H-aggregation are identified as two classical models of function-ally oriented non-covalent interactions,and significant attention has been drawn by researchers.However,due to the scarcity of single-crystal examples of H-aggregation,a comprehensive understanding of the relationship between its stacking mode and optical behaviour has been hindered.In recent studies,two polyaromatic Schiff base compounds,Cl-Salmphen and H-Salmphen,were successfully synthe-sized,and both were found to exhibit H-aggregation.In thefindings,H-Salmphen was shown to display typical C─H···πinteractions,characteristic of Aggregation-Induced Emission(AIE)active molecules,whereas its halogenated counterpart was identified as behaving similar to Aggregation-Caused Quenching(ACQ)active molecules.These types of results suggest that identical intermolecular interactions can produce differing optical behaviours.Light was shed,at least in part,on the for-mation mechanisms of H-type aggregates and their luminescence properties from these observations.Additionally,the high optical signal-to-noise ratio inherent to H-aggregates was utilized for the exploration of water content detection.As an outcome,a high-performancefluorescentfilter paper was developed,enabling easy real-time detection using a smartphone.