Extended Data Fig. 2: Comparison of the buPDI-1P COF structures when loaded with different solvents.
(a) Comparison of the XRD patterns of the solvent-loaded buPDI-1P COF. While the peak intensities vary depending on the respective solvent (structure factors differ considerably depending on the solvent in the pores), the peak positions are almost identical. Only the position of the 110 reflection around 4.5° (marked with a dashed line) shifts slightly, whereas the position of the 020 reflection at 4.0° remains constant. This indicates a small variation in the a axis length ranging from 28.0 Å (heptane) to 29.8 Å for the bulkier mesitylene and 1,2-dichlorobenzene. The XRD pattern of the toluene-loaded COF was recorded with synchrotron radiation under a controlled atmosphere and converted to Cu Kα angles for comparison. (b) Comparison of the XRD patterns of the buPDI-1P COF at intermediate solvent loading (achieved by slow drying of the solvent-loaded sample in air, except for toluene). The XRD pattern of the toluene-loaded COF was recorded with synchrotron radiation under a controlled atmosphere and converted to Cu Kα angles for comparison. To our surprise, we observe two different intermediate pore phases (denoted as ip and ip*), depending on the solvent. For all solvents, the respective intermediate phase forms from the op phase and converts to the cp phase when the solvent is further removed. No phase transformations between these two intermediate phases are observed. (c) The less bulky heptane, isopropanol, toluene and cyclohexane produce a fairly contracted ip phase where the butyl chains adopt a side-by-side configuration with maximal overlap. (d) The very bulky mesitylene and 1,2-dichlorobenzene enforce a different ip* phase where the butyl chains are in a side-by-side configuration, but with less overlap. This phase is more expanded and hence provides a larger accessible porosity (Connolly surface is shown in light blue). (e) Change of selected unit cell parameters during the phase transformations. The expansion is mostly along the projection of the a axis perpendicular to the pores, that is, a · sin(β), while the b axis remains nearly constant. Filled symbols: toluene, empty symbols: mesitylene. While the op phases are virtually the same, the ip* phase of the mesitylene-filled COF has a substantially larger a axis and unit cell volume.
