It is known that cyanobiphenyl leads to antiparallel pairing through dipole-dipole interactions, increasing the effective length-to-breadth ratio (i.e. aspect ratio) and leading to interdigitated smectic phases. To determine if this is a steric effect we devised compound 11, a structural homologue of 9 however with an increased dipole moment (at the DFT(B3LYP/6-31G(d)) level: 9 = 7.2 Debye, 11 = 7.6 Debye) that might be expected to alter the degree of antiparallel pairing and so lead to a change in layer spacing. If the effect is purely steric then the layer spacings should be unchanged. The transition temperatures and associated enthalpies of transition of 9 and 11 are given in Table .