Mechanochemically driven covalent self-assembly of a chiral mono-biotinylated hemicucurbit[8]uril

Abstract

Solution-based synthesis of complex molecules with high efficiency leverages supramolecular control over covalent bond formation. Herein, we present the mechanosynthesis of chiral mono-biotinylated hemicucurbit[8]urils (mixHC[8]s) via the condensation of D-biotin, (R,R)- or (S,S)-cyclohexa-1,2-diylurea, and paraformaldehyde. The selectivity of self-assembly is enhanced through mechanochemistry and by fostering non-covalent interactions, achieved by eliminating solvents and conducting the reaction in the solid state. Rigorous analysis of intermediates reveals key processes and chemical parameters influencing dynamic covalent chemistry. The library of ca. 50,000 theoretically predicted intermediates and products leads to covalent self-assembly of chiral hemicucurbiturils. Mechanochemically prepared diastereomeric (−)- and (+)-mixHC[8]s are suitable for anion binding and derivatization. Immobilization of the macrocycles on aminated silica produces a functional material capable of selective capture of anions, as demonstrated by efficient perchlorate removal from a spiked mineral matrix.