We describe an example of "interpenetration isomerism" in three-dimensional hydrogen-bonded organic frameworks. By exploiting the crystallization conditions for a peripherally extended triptycene H6 PET, we can modulate the interpenetration of the assembled frameworks, yielding a two-fold interpenetrated structure PETHOF-1 and a five-fold interpenetrated structure PETHOF-2 as interpenetration isomers. In PETHOF-1, two individual nets are related by inversion symmetry and form an interwoven topology with a large guest-accessible volume of about 80 %. In PETHOF-2, five individual nets are related by translational symmetry and are stacked in an alternating fashion. The activated materials show permanent porosity with Brunauer-Emmett-Teller surface areas exceeding 1100 m2 g-1 . Synthetic control over the framework interpenetration could serve as a new strategy to construct complex supramolecular architectures from simple organic building blocks.
Keywords: crystal engineering; hydrogen-bonded organic frameworks; interpenetration isomerism; porous molecular solids; supramolecular chemistry.
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