Chemodosimeters for mercury(II) and methylmercury(I) based on 2,1,3-benzothiadiazole

Two novel 2,1,3-benzothiadiazole-based chemodosimeters (1a and 1b) were designed and synthesized, and their fluorescent behaviors toward various metal ions were investigated. Chemodosimeter 1a shows excellent optical properties and exclusively distinguishes Hg2+ and CH3Hg+ from other metal ions in aqueous solutions. Though the response of chemodosimeter 1b to Hg2+ and CH3Hg+ is slower than 1a, fortunately, chemodosimeter 1b becomes a promising fluorescent sensor for Hg2+ and CH3Hg+ with high selectivity. Evidences for the desulfurization mechanism were provided by UV–vis and fluorescence titration spectra and especially 1H NMR and HRMS experiments.