Selective and Efficient Removal of Mercury from Aqueous Media with the Highly Flexible Arms of a BioMOF

A robust and water-stable metal-organic framework (MOF), featuring hexagonal channels decorated with methionine residues (1), selectively captures toxic species such as CH3Hg+ and Hg2+ from water. 1 exhibits the largest Hg2+ uptake capacity ever reported for a MOF, decreasing the [Hg2+] and [CH3Hg+] concentrations in potable water from highly hazardous 10ppm to the much safer values of 6 and 27ppb, respectively. Just like with biological systems, the high-performance metal capture also involves a molecular recognition process. Both CH3Hg+ and Hg2+ are efficiently immobilized by specific conformations adopted by the flexible thioether claws decorating the pores of 1. This leads to very stable structural conformations reminiscent of those responsible for the biological activity of the enzyme mercury reductase (MR).