A near-infrared fluoride sensor based on a substituted naphthalenediimide-anthraquinone conjugate

The synthesis and characterization of a highly selective fluoride receptor based on a naphthalene diimide substituted with an anthraquinone (NDI-AQ) moiety is described. In CHCl3, the receptor was shown to be highly selective for fluoride (K-a similar to 10(3) M-1) over other anions (AcO-, HSO4-, Br-, Cl-, I-, ClO4-, H2PO4-, and NO3-) with pronounced changes in absorption characteristics, that is, red-shift of the absorption band to 790 nm (NIR). The visual color change, NIR shift in absorption, emission spectroscopy, and electrochemistry thus support an intramolecular charge transfer (ICT) effect upon fluoride binding to the NDI-AQ receptor. (C) 2015 Elsevier Ltd. All rights reserved.