The energy-density distribution of predicted TMA crystal structures is shown in Figure . The expense of searching the crystal packing space with multiple independent, conformationally flexible molecules in the asymmetric unit limited us to predicting crystal structures with 1 and 2 molecules in the asymmetric unit (Z`= 1 and 2). Hence, our landscape of predicted structures does not contain the known Z`= 6 TMA, nor the Z`= 3 TMA structures. However, we do find hexagonal networks of hydrogen bonding, as seen in TMA and TMA, across the crystal structure landscape; predicted crystal structures containing this motif are shown as orange points (Z`= 1) and red points (Z`= 2) in Figure . The CSP results show the usual overall trend towards higher lattice energies at lower crystal density. However, we observe two clear low-energy 'spikes' of unusually stable, low density structures in the density regions around ~0.8 and 1.1 g/cm , significantly below the densities of the known  ( = 1.44 g/cm ) and  ( = 1.34 g/cm 3 ) forms. The minimum of the lower density spike, whose structure, 1, is shown in Figure , has a density of 0.85 g/cm and an energy 17.3 kJ/mol above the global minimum predicted structure, while the minimum of the higher density spike, 2, shown in Figure , is 14.8 kJ/mol above the global minimum. These 'spike' features are reminiscent of the low-energy, low-density spikes corresponding to isolable porous structures on the crystal structure landscape of triptycenetrisbenzimidazolone. The shape of the energy-density distributiuon suggests that these sets of crystal structures occupy deep, low energy regions of the lattice energy surface separated from the region of densely-packed structures by a large energy barrier. Moreover, the predicted lattice energies for 1 and 2 are both within 20 kJ/mol of the predicted global minimum structure. Given that we isolated previously polymorphs of triptycene benzimidazalone molecules that were predicted to be 49.6 kJ/mol above the global minimum but stabilized by crystallization solvent, this gave us confidence that 1 and 2 might be accessible by experiment.