1,3-Bis(pyren-1-yliminomethyl)calix[4]arene as a selective fluorescent turn-on sensor for mercury(II) ion

<p>A novel calixarene-based diimine, 1,3-bis(pyren-1-yliminomethyl)calix[4]arene (<b>5</b>), serves as a turn-on-type fluorescent sensor, which selectively detects Hg<sup>2+</sup> in THF/H<sub>2</sub>O (99:1, v/v) in the presence of various other metal ions. Such selectivity is not seen with half salen <b>1</b> derived from salicylaldehyde and 1-aminopyrene. <sup>1</sup>H NMR analysis reveals that it is a chemodosimetric sensor based on its hydrolysis mediated by Hg<sup>2+</sup> to release 1-aminopyrene molecules as fluorescent chromophores.</p>