A Simple Strategy to Obtain Synthetic Ca2+‐Dependent Lectin Mimics

Abstract

AbstractMany lectins require a Ca2+ ion as structure directing co‐factor to function as carbohydrate binders. Such lectins are implicated in various important biological processes such as inflammation and infection, yet a simple strategy to mimic their function is lacking. Herein, a very simple dipyridyl ligand (6) is reported that can organize around a Pd2+ ion to form the ring‐like complexes [PdCl26] and [Pd62]2+. In CD2Cl2 with 5 % dmso‐d6, ligand 6 does not associate with glycosides, while its Pd2+ complexes selectively bind to β‐n‐octyl‐glycosides over α‐n‐octyl‐glycosides. The highest affinity (Ka1:1≈116 M−1) was found between the dicationic [Pd62]2+ and n‐octyl‐β‐D‐galactoside. Molecular modelling suggests a common binding motif with an important role of C−H⋅⋅⋅π interactions and two charge assisted bifurcated [N−H/C−H]+⋅⋅⋅O hydrogen bonds. Ligand 6 and its metal complexes thus provide a proof‐of‐concept for a very simple strategy to mimicking Ca2+‐dependent lectins.