CRYSTAL-STRUCTURE OF MESOGENIC NZYLOXYCARBONYL)-4-(4-N-OCTYLOXYBENZOYLOXY)BENZOIC ACID

The crystal and molecular structure of the title compound la has been determined by X-ray analysis. la crystallizes in space group <P(1)over bar> With two molecules in a unit cell of dimensions: a = 5.516(1), b = 13.186(4), c = 18.364(5) Angstrom, alpha = 95.82(3), beta = 92.14(2 ), gamma = 100.17(2)degrees. The structure was solved by direct method s and refined on F-2 to R values of wR(2) = 0.100 and R-1 = 0.070, res pectively, for 1739 observed unique reflections.The molecules of la ar e associated to dimers by hydrogen bonds between their carboxyl groups . The mesogenic core of the molecules shows a markedly stretched shape but surprisingly the bulky lateral substituent is oriented nearly per pendicular to it. The crystal structure is characterized by a perfect parallel alignment and an interlocked packing of the dimers. 1a exhibi ts a considerably different molecular and crystal structure from two i sostructural compounds that differ only from la by a nitro or cyano su bstituent, respectively, in the p-position of the benzene ring of the lateral substituent. (C) 1997 Elsevier Science B.V.