Lanthanide Discrimination with Hydroxyl-Decorated\nFlexible Metal–Organic Frameworks

Abstract

We report two new\nhighly crystalline metal–organic frameworks (MOFs), derived\nfrom the natural amino acids serine (<b>1</b>) and threonine\n(<b>2</b>), featuring hexagonal channels densely decorated with\nhydroxyl groups belonging to the amino acid residues. Both <b>1</b> and <b>2</b> are capable of discriminating, via solid-phase\nextraction, a mixture of selected chloride salts of lanthanides on\nthe basis of their size, chemical affinity, and/or the flexibility\nof the network. In addition, this discrimination follows a completely\ndifferent trend for <b>1</b> and <b>2</b> because of the\ndifferent locations of the hydroxyl groups in each compound, which\nis evocative of steric complementarity between the substrate and receptor.\nLast but not least, the crystal structures of selected adsorbates\ncould be resolved, offering unprecedented snapshots on the capture\nprocess and enabling structural correlations with the separation mechanism.