Mesomorphism induced by hydrogen bonding between complementary components. Crystal and molecular structure of the adduct between 4-phenylbenzoic acid and 4-cyano-4'-stilbazole

Hydrogen-bonded complexes were formed between complementary, proton-donating and accepting components. Symmetric (two-to-one) complexes of 4-substituted benzoic acids and 4,4'-bipyridine and structurally unsymmetric (one-to-one) complexes of benzoic acid derivatives with either il-cyano or 4-nitro-4'-stilbazole, were studied. Despite the fact that none of the components was particularly mesogenic, nor contained an alkyl chain, many of the resultant mixtures displayed nematic mesomorphism. In some cases the clearing temperature was above 220 degrees C. The crystal and molecular structure of one of these liquid-crystalline complexes, 2c (4-phenylbenzoic acid/4-cyano-4'-stilbazole) is described.