Fluorescence probe with AIE properties for ratiometric/turn off detecting of water in organic solvents and solid state

Efficient detection of trace water was important before use in water-sensitive reactions. Herein, a fluorescence sensor 1,4-bis((E)-(2-(benzo[d]thiazol-2-yl)hydrazineylidene)methyl)benzene (DHB) was designed and synthesised by a simple one-step reaction using 2-hydrazinobenzothiazole and terephthalaldehyde as raw materials. DHB showed aggregation-induced emission characteristics in solid state and 1,4-dioxane/H2O mixture. In addition, the fluorescent colour changes in IPA and fluorescence quenching in N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), dimethyl sulphoxide (DMSO), glycerine (GI), and 1,3-propanediol (1,3-PDO) were obviously observed with increasing water content, making DHB a highly sensitive fluorescent sensor for water detection with a detection limit of 0.174% for IPA, 0.040% for DMSO, 0.067% for DMF, 0.039% for DMA, 0.069% for 1,3-PDO, and 0.013% for GI, respectively. Further, DHB displayed fluorescence colorimetric response to water in solid state. H-1 NMR titration indicated that the sensing mechanism for the detection of trace water was form hydrogen bonds between H2O molecule and amino group of DHB.