Histidine–dialkoxyanthracene dyad for selective and sensitive detection of mercury ions

Histidine-dialkoxyanthracene (HDA) was synthesised as a turn off type fluorescent sensor for fast and sensitive detection of mercury ions (Hg$^{2+}$) in aqueous media. The two histidine moieties act as ‘claws’ to selectively complex Hg$^{2+}$. The binding ratio of HDA to Hg$^{2+}$ was 1:1 (metal-to-ligand ratio). The association constant for Hg$^{2+}$ towards the receptor HDA obtained from Benesi–Hildebrand plot was found to be 3.22 × 10$^{4}$ M$^{−1}$ with detection limit as low as 4.7 nM (0.94 μg/L).