Phenanthroline-based fluorescence sensors for Eu<sup>3+</sup> ion and subsequent enantioselective discriminating of malate

<p>A pair of novel chiral fluorescent and colorimetric sensors <b>L1</b> and <b>D1</b> had been designed and synthesized, which were based on phenanthroline as the fluorophore and mandelohydrazide as the binding site. They showed selective recognition toward Eu<sup>3+</sup> ion as ‘turn-off’ mode in DMSO-H<sub>2</sub>O solution (v/v = 1:5, 10 mM HEPES, pH = 7.4). The fluorescence discrimination towards chiral carboxylate anions had been studied for <b>L1</b>-Eu<sup>3+</sup> and <b>D1</b>-Eu<sup>3+</sup> complex and they showed good enantioselective recognition ability towards malate as ‘turn-on’ mode. The interaction of sensor <b>L1, D1</b> with Eu<sup>3+</sup> and <b>L1</b>-Eu<sup>3+</sup>, <b>D1</b>-Eu<sup>3+</sup> towards malate caused different color changes in the naked eye.</p>