A multichannel thiacalix[4]arene-based fluorescent chemosensor for Zn<sup>2+</sup>, F<sup>−</sup> ions and imaging of living cells

<p>The fluorescent sensor (<b>3</b>) based on the 1,3-alternate conformation of the thiacalix[4]arene bearing the coumarin fluorophore, appended via an imino group, has been synthesised. Sensing properties were evaluated in terms of a colorimetric and fluorescence sensor for Zn<sup>2+</sup> and F<sup>−</sup>. High selectivity and excellent sensitivity were exhibited, and ‘off-on’ optical behaviour in different media was observed. All changes were visible to the naked eye, whilst the presence of the Zn<sup>2+</sup> and F<sup>−</sup> induces fluorescence enhancement and the formation of a 1:1 complex with <b>3</b>. In addition, <b>3</b> exhibits low cytotoxicity and good cell permeability and can readily be employed for assessing the change of intracellular levels of Zn<sup>2+</sup> and F<sup>−</sup>.</p>