Although it appears difficult to significantly influence the interfacial orientation by tuning fluid-fluid interaction strength within the realm of reasonable OSC parameters while the bulk fluid remains in an isotropic liquid phase, the energetic component of the free energy difference does have a strong dependence on the strength of the fluid-substrate interactions. Switching from a strongly (e.g. graphite) to weakly (e.g. silica) interacting substrate has been shown experimentally and computationally to influence the orientation at the solid interface for a range of OSCs. Fig. highlights the relative importance of the fluid-substrate interactions: the difference in energy on switching from a strongly to weakly interacting substrate (e.g. graphene to silicon) is comparable to changing the interaction anisotropy from values close to those representative of benzene to perylene (a significant structural change), and is sufficient to switch the free energy from favouring face-on to side-on orientation in some cases.