Such a reduction of the GB cavity radius increases the atom's interaction with the solvent, as observed for the HFEs, but also weakens the electrostatic interactions of polar solute atoms. Since the HG-based optimization is mainly driven by the excessively strong electrostatic interactions between the host and guest in the cucurbit[n]uril complexes, ForceBalance decreased the nitrogen radius to a very small value to reduce the large negative ∆G b . This, however, comes at the cost of increasing the hydration of nitrogen atoms, thus giving the excessively favorable ∆G solv observed here.