With HSPs, each molecule is associated with three polarity scales describing the energy density of dispersion forces (𝛿𝑑), dipolar intermolecular forces (𝛿𝑝), and hydrogen bonds (𝛿ℎ). Solubility is then assessed by comparing the HSPs of the molecules of interest -the focal tenet being that molecules with similar HSPs are more likely to form a soluble mixture. To use HSPs in a predicVve manner, we needed to determine the HSPs of the scrambled 3 3 :13 3 -R POC mixture; this is accomplished using the HSPiP sobware package. The solute parameters for the 3 3 :13 3 -R POC mixture are: 𝛿𝑑 = 22.3 MPa ½ indicaVng a large dispersion contribuVon due to the large size of the cage molecules; 𝛿𝑝 = 0.1 MPa ½ indicaVng there is no overall dipole across the cage molecule; and 𝛿ℎ = 12.5 MPa ½ indicaVng the cage molecule would form effecVve soluVons with polar and hydrogen-bonding solutes. These parameters indicate that a non-polar solvent, with no permanent overall dipole but sVll polarisable, is preferenVal -this is represented by a high 𝛿𝑑 parameter and a low 𝛿𝑝 parameter. Halogenated solvents, and aromaVc solvents to a lesser extent, provide this combinaVon of polarity acributes, which agrees with the iniVal size-excluded solvents found to form highly concentrated PLs with 3 3 :13 -R (Figure ).