Expedient Decagram-Scale Synthesis of Robust Organic Cages That Bind Sulfate Strongly and Selectively in Water
Émer M. Foyle, Rosemary J. Goodwin, C. Cox, Bailee R. Smith, Annie L. Colebatch, Nicholas G. White
Abstract
Selective anion recognition remains a key challenge in supramolecular chemistry: only a very small number of systems that can function in water are known, and these nearly always preferentially bind hydrophobic anions. In this work, we report three robust hexa-cationic cages that can be prepared on scales up to 14 g in two simple and high-yielding steps from commercially available materials. One of these cages displays unusually strong sulfate binding in water ( K a = 12,000 M –1 ), and demonstrates high selectivity for this anion over H 2 PO 4 – /HPO 4 2– in DMSO/buffer mixtures. These results demonstrate that relatively large, three-dimensional supramolecular hosts can be prepared in high yields and on large scales, and can be highly potent receptors.