We report an investigation of the complexation between a water soluble pillararene host (WP6) and a panel of hydrophobic cationic guests (G1 - G20) by a combination of 1H NMR spectroscopy and isothermal titration calorimetry in phosphate buffered saline. We find that WP6 forms 1:1 complexes with Ka values in the 104 - 109 M-1 range driven by favorable enthalpic contributions. This thermodynamic dataset serves as blinded data for the SAMPL9 challenge.