Search for: All records

Abstract We report the synthesis and characterization of sulfated pillar[5]arene hosts (P5S₂‐P5S₁₀) that differ in the number of sulfate substituents. All fiveP5S_nhosts display high solubility in water (73–131 mM) and do not undergo significant self‐association according to¹H NMR dilution experiments. The x‐ray crystal structures ofP5S₆,P5S₆ ⋅ Me₆HDA,P5S₈ ⋅ Me₆HDA, andP5S₁₀ ⋅ Me₆HDAreveal one intracavity molecule ofMe₆HDAand several external molecules ofMe₆HDAwhich form a network of close methonium ⋅ ⋅ ⋅ sulfate interactions. The thermodynamic parameters of complexation betweenP5S_nand the panel of guests was measured by direct or competitive isothermal titration calorimetry. We find that the binding free energy toward a guest becomes more negative as the number of sulfate substituents increase. Conversely, the binding free energy of a specific sulfated pillar[5]arene toward a homologous series of guests becomes more negative as the number of NMe groups increases. The ability to tune the host ⋅ guest affinity by changing the number of sulfate substituents will be valuable in supramolecular polymers, separation materials, and latching applications.