The ITC experiment was carried out at 25 °C in aqueous solution. In a typical experiment, the solution of 2C-WP5A in a 0.250 mL syringe was sequentially injected with stirring at 300 rpm into a solution of G in the sample cell (1.4227 mL). A control experiment to determine the heat of dilution was carried out by performing the same number of injections with the same concentration of host compound into ultrapure water. The dilution enthalpies determined in control experiments were subtracted from the enthalpies measured in the titration experiments to obtain the net reaction heat. All thermodynamic parameters reported in this work were obtained by using the “one set of binding sites” model. Two titration experiments were independently performed to give the averaged values with standard error (see Supplementary Fig. S23).