Open Pentiptycene Networks Assembled through Charge-Assisted Hydrogen Bonds

A series of hydrogen-bonded networks was prepared incorporating ditopic, tritopic, or tetratopic polyamidinium tectons and linear pentiptycene dicarboxylates. The ditopic amidinium forms a 1D hydrogen bonded chain when combined with the pentiptycene tecton, while the tritopic trigonal planar amidinium tecton forms a 2D honeycomb network. A tetratopic amidinium tecton forms a 3D diamondoid network, which is 32-fold interpenetrated, tied for the highest degree of interpenetration observed for a hydrogen bonded network. The bulky pentiptycene functionality prohibits the polymers from packing efficiently, leading to voids within each structure. These frameworks were envisaged as potential molecular motors, but unfortunately, a lack of stability to solvent removal precluded an investigation of these properties.