Erbium hydroxide ethanedisulfonate: a cationic layered material with organic anion exchange capability.

We describe a cationic erbium-based material [Er12(OH)29(H2O)5][O3SCH2CH2SO3]3.5·5H2O. As synthesized, the material is water stable and capable of complete organic anion exchange for a variety of α,ω-alkanedicarboxylates. We chose these anions as initial examples of exchange and as an analog for pharmaceutical waste, some of which have a carboxylate functionality at neutral pH range. Free-floating and partially anchored organosulfonate anions reside between the cationic corrugated layers and allow for exchange. The structure also displays a reversible hydration event above 100 °C. Both the as-synthesized and the exchanged materials are characterized by a variety of analytical techniques.