Anomalous crystal packing of iptycene secondary diamides leading to novel chain and channel networks

The crystal structures of triptycene and pentiptycene secondary diamides 1 and 2 grown from methanol solutions are reported. In addition, the crystal structure of 1 from a toluene–methanol mixed solution was also determined. The molecular structures of 1 in both crystals are folded, and an anomalous hydrogen-bonding chain motif is generated. On the other hand, the pentiptycene diamide 2 adopts an extended conformation, and the amide groups do not participate in any known amide–amide hydrogen-bonding patterns. Instead, interdigitated molecular stacking results in grid-like channels having a void volume of ca. 25–30% of the crystal. The potential of iptycene-derived building blocks in the design of new organic crystalline materials is thus demonstrated.