An ethanethioate functionalized polythiophene as an optical probe for sensitive and fast detection of water content in organic solvents

A new polythiophene-based optical probe, namely PTS, was designed and prepared for detection and quantification of the water present in organic solvents. PTS exhibited sensitive and fast absorption and fluorescence signaling response to the changes of water content in tetrahydrofuran (THF), N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMAc) due to the water-induced interpolymer-stacking aggregation as demonstrated by dynamic light scattering (DLS) analysis. The fluorescence intensity of PTS at 550 nm linearly reduced as a function of the water content in detection ranges of 0-30% (v/v) in THF, 0-10% in DMF and 0-10% in DMAc with the limit of detection (LOD) for water being 0.034% (v/v) in THF, 0.013% (v/v) in DMF, and 0.014% (v/v) in DMAc, respectively. Additionally, PTS-incorporated test paper was fabricated to successfully achieve naked-eye detection of water in DMF and DMAc. PTS was further applied to estimate the water content in real samples, convincingly demonstrating that our method was comparable with the standard Karl Fischer titration.