A highly sensitive and selective fluorescent "off-on-off" relay chemosensor based on a new bis(salamo)-type tetraoxime for detecting Zn2+ and CN.

A new naphthalenediol-based bis(salamo)-type fluorescent probe H4L for Zn2+ and CN- was reported. Probe H4L showed a highly selective fluorescence enhancement toward Zn2+ over other metal ions including Cd2+, and obtained the L-Zn2+complex can only detect CN- in various anions. Their recognition mechanisms were explained by Job plots, fluorescent and UV-vis titrations, and theoretical calculations. The L-Zn2+complex has been synthesized and structurally characterized using Hirshfeld surface analysis, elemental analyses, IR, UV-Vis and fluorescent spectra. Additionally, the relay probe with the wide adaptability of pH range and excellent stability showed highly selectivity for CN- recognition.