الفهرس 
INTRODUCTION TO LIQUID CRYSTALSOnly 14 pages are availabe for public view
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Abstract
Six laterally methyl-substituted pyridine-based derivatives (Ia-f) of the type 4-(4’-pyridylazo-3-methylphenyl)-4”-substituted benzoates having the molecular formula 4-X-C6H4COOC6H3(3-CH3)-N=N-C5H4N, were prepared and characterized. The substituent, X, varies between CH3O, CH3, H, Cl, Br, and CN. Two groups of the 1:1 complexes between the prepared derivatives (Ia-f) and 4-substituted benzoic acids (II) were prepared to investigate the effect of terminal substituents, either on the pyridine-based derivative or on the acid component, on the extent and stability of the supramolecular liquid crystal phases induced by intermolecular hydrogen bonding. In the first series of complexes (Group A), the non-mesomorphic pyridine-based derivative is complexed with the mesomorphic benzoic acid complement that carries an alkoxy group of varying chain length. Complexes of the other series (Group B) are composed of the same pyridine-based derivatives, but the benzoic acid complement carries small compact polar groups. In group B supramolecular complexes, neither of the pyridine-based derivative nor the acid complement is mesomorphic, but the hydrogen-bonded complexes are. The complexes prepared in both series were characterized for their mesophase behavior by differential scanning calorimetry, DSC, and polarized light microscopy, PLM. Five 4-alkoxybenzoic acids (4-CnH2n+1O-C6H4COOH, II8-II16) were used in group A complexes, while seven 4-substituted benzoic acids (Y-C6H4COOH, IIa-g) were used in group B complexes; the substituent Y varies between CH3O, CH3, H, Cl, Br, CN and NO2. Smectic C mesophase of the acid is retained in group A complexes, while the nematic phase is induced in some of group B complexes.