Scope and selection of crystal structures. We have used hypothetical porous crystal structures generated by CSP. The prediction of porous crystal structures of oand mfluorophenol has been reported in a previous article . We have also obtained CSP results of resorcinol and TTBI from previous works . From the CSP structure sets we selected plausible clathrate host structures. The structure selection was based on the pore size and dimensionality as calculated with PLATON or (for TTBI) ZEO++ . The porosity calculations are performed by placing a probe at every point in a 0.2 Å lattice spanning the unit cell and testing whether the probe is within the van der Waals radius + probe radius (1.2 Å) of any atom . For this study, we selected structures with (essentially) discrete pores or narrow channels, see Fig 2 . For the sake of traceability, we keep the original structure names from the CSP studies. Some names originally contained structural information, such as Z or space group symbols, but here the structure names are arbitrary labels only. In total, 118 porous host structures were considered, but some were excluded for various reasons. Some could not adsorb any guest molecule without structurally collapsing, some had persistent imaginary phonon frequencies, and some converged to the same structure during geometry-optimization. For example, oF0_1258, oF0_R-3_6 and oF0_R-3_39 all converged to the structure oF00_P-1_14655. Only the latter is included in the final set of results, which contains 84 host structures and their 206 clathrates that appear to be stable and successfully completed all calculations. The crystal structures studied here, with and without guest molecules, are included in the supplementary information (ESI) as one CIF file containing all 290 crystal structures.