To identify any trends between π stacking interactions and lattice energy, we computed the Pearson correlation coefficients for each chain length (Fig. ). The results revealed a direct, but weak, relationship between π -π stacking interactions and crystal lattice energy for most values of n. Therefore, π -π stacking interactions are predominantly observed across higher-energy crystals, and less frequently observed for low-energy crystals. However, on increasing chain length for naphthalene up to [6]helicene, π -π stacking becomes less unfavourable, to the point where there is no discernible correlation between the lattice energy and π -π stacking interactions, after which the correlation increases again, becoming maximally unfavourable for [8]helicene (Fig. ). The correlation between π -π interactions and lattice energy then decreases as n increases, reaching a local minima for [11]helicene.