CRYSTAL AND MOLECULAR-STRUCTURE OF THE LATERALLY BRANCHED NEMATOGENICCOMPOUND 2-N-NONYL-1,4-PHENYLENE BIS(4-N-OCTYLOXYBENZOATE)

The crystal and molecular structure of the nematogenic compound 2-n-no nyl-1,4-phenylene bis(4-noctyloxybenzoate) (NPOB) has been determined at - 100 degrees C and at room temperature by X-ray analysis. NPOB cry stallizes in space group P (1) over bar with two molecules in a unit c ell of dimensions (values of the room temperature investigation are gi ven in brackets) a = 9.878(2) [10.165(4)], b = 12.700(3) [12.863(5)], c = 17.830(4) [17.940(6)] Angstrom, alpha = 71.83(2) [69.65(2)], beta = 84.58(2) [85.23(2)], gamma = 76.11(2) [75.43(2)]degrees. The structu re was solved by direct methods and refined to an R value of 0.056 [0. 1O8]. The most striking features of the molecular structure are the al l-trans-conformation of the laterally branched nonyl group and the nea rly parallel alignment of all three alkyl substituents. The crystal st ructure is characterized by a parallel arrangement and an interlocked packing of the molecules.