EFFECT OF MOLECULAR-STRUCTURE ON THE PHASE-BEHAVIOR OF SOME LIQUID-CRYSTALLINE COMPOUNDS AND THEIR BINARY-MIXTURES .2. 4-HEXADECLOXYPHENYL ARYLATES AND ARYL 4-HEXADECYLOXY BENZOATES

4-Hexadecyloxyphenyl-4'-substituted benzoates, Ia-d, and 4-substituted phenyl-4'-hexadecyloxy benzoates, IIa-d, with the substituents CH3O, Cl, CN, and NO2, respectively, were prepared and characterized by infr ared spectroscopy and the apparent solution dipole moment measured usi ng cyclohexane as a solvent. Smectic A mesophase stability was investi gated by differential scanning calorimetry and polarized light microsc opy. The effects of structural changes on phase transitions in these t wo series of compounds are discussed in terms of dipole and mesomeric effects.