[1,2′]Biindenylidene-3,1′-3′-trion(bindone): Colorimetric detection of volatile organic compounds(VOCs) ethylamine using highly selective Hg2+ chemosensor in aqueous solution

• [1,2′]Biindenylidene-3,1′-3′-trion(bindone) ion (BD) exhibited high selectivity for Hg2+.
• BD-Hg2+ complex was used to sense the VOC EtNH2.
• EtNH2 gas sensing system shows fast color change.

A colorimetric chemosensor based on [1,2′]biindenylidene-3,1′-3′-trion(bindone) ion (BD) has been investigated for high selectivity and sensitivity toward Hg2+ in HEPES buffer solution. Interestingly, the colorless solution of the BD-Hg2+ complex could be recovered after addition of VOC EtNH2. Sensing mechanism was confirmed by 1H NMR studies. We have investigated ability of complex formation based on the association constant, Kass; the binding ability for the complex formation of BD-Hg2+ and EtNH2 is greater (Kass = 8.6 × 104 M−1) than that of the BD with Hg2+ (Kass = 8.0 × 103 M−1). EtNH2 gas test strip was made by adsorbing BD-Hg2+ on to the test paper. The test strip was exposed to EtNH2 gas. And the resulting color changing properties were clearly demonstrated.