Abstract: | We describe an example of “interpenetration isomerism” in three‐dimensional hydrogen‐bonded organic frameworks. By exploiting the crystallization conditions for a peripherally extended triptycene H6PET, 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. |