Visual detection of fluoride based on supramolecular aggregates of perylene diimide in 100% aqueous media.

A water-soluble perylene imide derivative (PDI-Glu) was synthesized and their supramolecular aggregates composed of PDI-Glu and Al3+ were prepared as a "turn on" fluorometric probe to monitor F- in a purely aqueous system. Based on an "indicator displacement assay" (IDA) approach, the sensing performance and mechanism of PDI-Glu/Al3+ complex toward F- were investigated by absorption and emission spectra. It was suggested that disassembly of PDI-Glu/Al3+ aggregates was promoted by addition of F- through the competitive binding between Al3+ and F-. The detection limit is 240 nmol/L. This method featured simple preparation, excellent water solubility, adjustable self-assembly performance, ease of observation and operation, and high selectivity and sensitivity. It was used for monitoring F- in toothpaste and tap water samples with excellent accuracy and recovery. To the best of our knowledge, this is the first water-soluble perylene diimide-based probe for F- detection in 100% aqueous media. We believe this work could not only extend the sensing scope of water-soluble perylene diimide, but also bring some useful information for the rapid detection of anionic analytes  in aqueous media. The disassembly of supramolecular aggregates of PDI-Glu/Al3+ along with significant fluorescence recovery enable a rapid and visual detection of F- based on an "indicator displacement assay" strategy.