A highly selective and reversible fluorescence "OFF-ON-OFF" chemosensor for Hg2+ based on rhodamine-6G dyes derivative and its application as a molecular logic gate

A new rhodamine-6G-based chemosensor X was designed and synthesized for the colorimetric and fluorometric detection of Hg2+. The chemosensor X responsed to Hg2+ had good sensitivity, high selectivity and excellent reversibility in HEPES buffer (10 mM, pH 7.4)/CH3CN (40:60, V/V). The recognition mechanism of X toward Hg2+ was evaluated by Job's plot, IR and MS. Meanwhile, X-Hg2+ fluorescence lifetime was also measured. It was interesting that X displayed favorable reversibility to form an "off-on-off" type signaling behavior with the Hg2+-induced emission spectra being quenched by I-. Furthermore, it could be applied as a molecular logic gate and test strips based on X exhibited a good reversibility selectivity to Hg2+. (C) 2018 Elsevier B.V. All rights reserved.