A Water Soluble Pd2L4 Cage for Selective Binding of Neu5Ac. Issue 55 (6th September 2021)

• Record Type: Journal Article
• Authors: Schaapkens, Xander; van Sluis, Roy N.; Bobylev, Eduard O.; Reek, Joost N. H.; Mooibroek, Tiddo J.
• Is Part Of: Chemistry. Volume 27:Issue 55(2021)
• Page Start: 13719
• Page End: 13724
• Publication Date: 2021-09-06
• Subjects: carbohydrate recognition -- host-guest systems -- molecular recognition -- sialic acids -- self-assembly; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202102176
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The sialic acid N ‐acetylneuraminic acid (Neu5Ac) and its derivatives are involved in many biological processes including cell‐cell recognition and infection by influenza. Molecules that can recognize Neu5Ac might thus be exploited to intervene in or monitor such events. A key obstacle in this development is the sparse availability of easily prepared molecules that bind to this carbohydrate in its natural solvent; water. Here, we report that the carbohydrate binding pocket of an organic soluble [Pd2 L4 ] 4+ cage could be equipped with guanidinium‐terminating dendrons to give the water soluble [Pd2 L4 ][NO3 ]16 cage 7 . It was shown by means of NMR spectroscopy that 7 binds selectively to anionic monosaccharides and strongest to Neu5Ac with K a =24 M −1 . The cage had low to no affinity for the thirteen neutral saccharides studied. Aided by molecular modeling, the selectivity for anionic carbohydrates such as Neu5Ac could be rationalized by the presence of charge assisted hydrogen bonds and/or the presence of a salt bridge with a guanidinium solubilizing arm of 7 . Establishing that a simple coordination cage such as 7 can already selectively bind to Neu5Ac in water paves the way to improve the stability, affinity and/or selectivity properties of M2 L4 cages for carbohydrates and other small molecules. Abstract : The carbohydrate binding pocket of an organic soluble [Pd2 L4 ] 4+ cage could be equipped with guanidinium‐terminating dendrons to give the water soluble [Pd2 L4 ][NO3 ]16 cage. It was shown by means of NMR spectroscopy that the cage binds selectively to anionic monosaccharides and strongest to Neu5Ac with K a =24 M −1 . The cage had low to no affinity for the thirteen neutral saccharides studied.