Single-crystal diffraction (SCXRD) studies of these materials, discussed in Section 2 of the Supplementary Information, reveal that the FSPA acetone and ethanol solvates are isostructural. Fourier difference maps revealed electron density that is separate from the FS and PA framework, which is assumed to correspond to the solvent, but the geometry could not be refined for either solvent molecule. Having confirmed the presence of solvent using solidstate NMR (cf. Fig. ), the SCXRD structures were solved with the PLATON SQUEEZE approach. As illustrated in Figure , the unit cell contains two pairs of symmetryequivalent FS and PA molecules and a void at an inversion centre in which the additional electron density resides, suggestive of a channel solvate. The sulfonamide group is refined with disorder over two positions with (fixed) equal occupancies.