X-Ray Studies on the Mesogen 4′-n-Pentyloxy-4-Biphenylcarbonitrile(5OCB) in the Solid Crystalline State

Abstract

The crystal and molecular structure of nematogen 4′-n-Pentyloxy-4-Biphenylcarbonitrile has been determined by direct methods. The crystals belong to the monoclinic system with space group P2₁/n. a = 21.378(5), b = 5.695(3), c = 12.789(2) Å, β = 106.074(17)° with four molecules per unit cell. Least-squares refinement leads to R = 0.050 (Rw = 0.038) for 1773 observed reflections. The molecules are in their most extended conformation, the rigid part lies parallel to a-axis while the chain part is inclined to it. Rigid part is also highly planar and is almost parallel to ab-plane. The molecules are stacked along c-axis. The molecules associate in pairs about the centre of inversion. In the unit cell the adjacent molecules are antiparallel to each other. The structure is of a common type for nematogens and could transform to the nematic state by means of a simple displacive transition.