Synthesis of bambusurils with perfluoroalkylthiobenzyl groups as highly potent halide receptors

Abstract

The preparation of anion receptors with ultrahigh binding affinities is an important, yet challenging, topic of supramolecular chemistry. The search for new structural motifs which would enhance the performance of anion receptors is therefore an important task. In this context, we report the synthesis of novel fluorinated bambus[6]urils that incorporate unique benzyl substituents with perfluoroalkylthio groups, aimed at enhancing their anion receptor capabilities. The synthetic strategy developed allows for the efficient preparation of these structural motifs. Ultrahigh stability of the complexes between halides and the prepared bambus[6]urils was observed and quantified using ¹⁹F NMR competition experiments. Replacing –CF₃ groups on benzylated bambus[6]urils by –SCF₃ groups increased the affinity of the macrocycles towards anions and provided the strongest iodide receptor reported with a binding affinity of 4 × 10¹³ M⁻¹ in acetonitrile.