CRYSTAL AND MOLECULAR-STRUCTURE OF THE NEMATOGENIC COMPOUND 4'-CYANOPHENYL-4-NORMAL-PENTOXYBENZOATE

The title compound with the formula C//5H//1//1O-C//6H//4-COO-C//6H//4-CN (CPPOB) crystallizes in the orthorhombic space group Pnam with a equals 16. 465 A, b equals 13. 577 A, c equals 7. 621 A 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 C//s symmetry as a consequence of their location on crystallographic mirror symmetry planes, the benzene ring to which the cyano group is attached has a perpendicular orientation to the other ring in the plane. The molecules adopt a nearly optimal stretched form, neighboring molecules make an angle of 35. 2 degree . The results are discussed in relation to the mesomorphic behavior of CPPOB.