Crystal and Molecular Structure of the Nematogenic Compound 4′-Cyanophenyl-4-n-Pentoxybenzoate

The title compound with the formula C5H11O-C6H4-COO-C6H4-CN (CPPOB) crystallizes in the orthorhombic space group Pnam with a = 16.465 Å, b = 13.577 Å, c = 7. 621 Å and four molecules per unit cell. The structure has been solved by direct methods and refined to a final R value of 0.050. The CPPOB molecules have exact Cs symmetry as a consequence of their location on crystallographic mirror symmetry planes, the benzene ring to which the cyano group is attatched has a perpendicular orientation to the other ring in the plane. The molecules adopt a nearly optimal stretched form, neighbouring molecules make an angle of 35.2°. The results are discussed in relation to the mesomorphic behaviour of CPPOB.