Rigid anthraquinone based sensor for dual and differential colorimetric detection of Cu2+ and Ni2+ ions: Mimicking different molecular logic systems

Abstract

A rigid colorimetric chemosensor, AQPD, based on anthraquinone as signaling unit, has been synthesized in a simple one-step procedure. The target sensor AQPD detected Cu2+ and Ni2+ ions in the aqueous methanol solution with naked eye color change from yellow to dark pink and light purplish blue, respectively and red shift of the absorption peak under a wide pH range from 4.0–10.0. The appearance of different colors with different amounts of Cu2+/Ni2+ ions suggested the potentiability of AQPD in on-site water quality monitoring application without any spectroscopic instrumentation. Absorption studies along with DFT theoretical calculations revealed the metal ion (Cu2+/Ni2+) induced deproptonation of NH of rigid electron rich binding sites at 1 position of anthraquinone. The real-time application of Cu2+/Ni2+ detection has been demonstrated in solution as well as solid state detection, constructing the molecular logic gate, quantifying Cu2+/Ni2+ in water samples as well as their color detection by means of smartphone application ‘Color detector App.