Selective and sensitive colorimetric detection of Hg(II) in aqueous solution by quinone-diimidazole ensemble with mimicking YES-OR-INHIBIT logic gate operation

• Quinone-diimidazole ensemble senses Hg(II) selectively in 90% aq. DMF solution.
• The mechanism of sensing involves formation of Hg(II)-ligand complex.
• YES-OR-INHIBIT combinational logic circuit was simulated and verified successfully.

A quinone-diimidazole ensemble (R1) has been prepared and characterized. The receptor exhibits a striking colour change from brown to blue instantaneously with Hg(II) ion in DMF:Water (1:9 v/v) selectively and sensitively. Electronic, fluorescence and 1H NMR titration experiments show that the mechanism of sensing involves the formation of [Hg(R1)2Cl2] complex having binding constant 6.31 × 105 M−1. The product of the reaction is characterized using LCMS and FT-IR spectroscopy which suggests the coordination of R1 to Hg(II) ion through imidazole N-atom. The addition of Hg(II) to R1 leads to fluorescence quenching with limits of detection 10 nM. The concatenation of YES-OR-INHIBIT combinational logic circuit has also been simulated and its truth table is verified successfully.

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