Phase behaviour of binary mixtures of 4-substituted phenyl 4′-n-alkoxybenzoates

Five homologous series 1a-e, of the title compounds have been prepared and investigated for their mesophase behaviour in binary mixtures. Each series differs from the other by a substituent X, which changes between CH3O, CH3, Cl, CN, and NO2. The number of carbons in the terminal alkoxy group, within a homologous series, varies between 6, 8, 14, and 16. All possible binary combinations, made from any two components bearing an alkoxy group of the same chain length but two different substituents X, were prepared and similarly characterized for their phase behaviour. Transition temperatures of the mixtures were measured by differential scanning calorimetry and identified by polarizing optical microscopy. Phase diagrams were constructed for the various binary systems and discussed in terms of electronic effects.