Dual-response and color-changing fluorescent sensor for N2H4 and Zn2+

N2H4 is an important chemical material and Zn2+ is an essential trace element for human life and health. The rapid, simple and in-situ detecting method for N2H4 and Zn2+ was always expected in industry and daily life. In this work, a novel color-changing fluorescent sensor for N2H4 and Zn2+ was developed based on a diaminocyclohexane-bridged bis-tetraphenylimidazole (Bis-TAM). Bis-TAM was prepared by “1 + 2” condensation of a tetraphenylimidazole-salicylaldehyde derivative with (1R, 2R)-1,2-diaminocyclohexane in 96 % yield. Bis-TAM possessed pale fluorescence (535 nm) in aqueous solution, which became strong red fluorescence (591 nm) on sensing N2H4 and blue fluorescence (465 nm) on sensing Zn2+. The good sensing selectivity for N2H4 and Zn2+ among various amines and metallic ions was confirmed. The detecting limitations were as low as 1.14 × 10-7 M for N2H4 and 1.03 × 10-7 M for Zn2+, respectively. The 1:1 sensing mechanism was confirmed by the fluorescence Job’s plot, binding MS spectrum and binding 1H NMR spectrum. Bis-TAM was successfully applied on detecting N2H4 in the test papers, the examination of smartphone, the analysis of simulated hydrazine explosives and the real water samples, suggesting the good application prospect on rapid, simple and in-situ detecting N2H4 and Zn2+ in real environment.