Two multi-mode Hg(II) sensors, L-MethBQA and L-CysBQA, were obtained by fusing methionine or S-methyl cystein, into bis-quinolyl amine based chiral podand scaffold. Quinolyl groups serve as the fluorophore and provide chelating N-atoms. Upon exposure to Hg2+ or Zn2+ these sensors show signal enhancement in fluorescence. However, Cu2+ quenches their fluorescence in 30:70 acetontrile/water. The S-methyl cystein based sensor L-CysBQA complexes with Hg2+, producing an exciton-coupled circular dichroism spectrum with the opposite sign to the one that is produced by Cu2+or Zn2+ complexation. L-CysBQA binds Hg2+ more strongly than Zn2+. These chiroptical fluorescent sensors differentiate Hg2+ from other metal ions, such as Zn2+, Cu2+, Ni2+and Pb2+, exceptionally well. These results suggest that the synergy obtained by combination of mercury-loving sulfur atom(s) and stereochemical engineering through chiral ligand scaffolds results in high sensitivity and selectivity forHg2+.

Multimode selective detection of mercury by chiroptical fluorescent sensors based on methionine/cystein

242nd National Meeting (2011)

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