A simple salicylaldehyde-bearing pyrazine as a turn-on fluorescent chemosensor for Al3+ and Zn2+ recognition and its applications

A simple fluorescent chemosensor, 5-(diethylamino)-2-((2-(pyrazin-2-yl) hydrazono)methyl)phenol, has been synthesized by Schiff-base condensation reaction. The chemosensor exhibited highly selective and sensitive "off-on" fluorescent responses toward Al3+ and Zn2+ but the signal of fluorescence emission varies. The detection limits were found to be 2.33 x 10(-7) M for Al3+ and 1.68 x 10(-7) M for Zn2+, respectively. The binding mechanisms between chemosensor and Al3+ or Zn2+ ions were supported by Job ' s, H-1 NMR, Fourier transform infrared spectra, and MS experiments. The sensing behavior was also studied with molecular logic functions of OR, AND, and NOT gates. In addition, the chemosensor was able to detect Al3+ and Zn2+ by producing distinct color changes observed by the naked eye on sensor-coated swabs. Moreover, the chemosensor was successfully applied to effectively detect Al3+ and Zn2+ in actual water and drug samples.