Properties of the liquid crystals formed by certain azomethines containing terminal cycloalkyl ring systems

Fifty-six compounds containing cyclopropyl, cycloheptyl, or cyclooctyl ring systems, members of six homologous series of azomethines related to the nO.m series, have been prepared and their liquid crystal behavior investigated. These series show less extensive smectic polymorphism than the analogous cyclopentyl and cyclohexyl derivatives, previously reported. The effect on nematic thermal stability of an increase in the size of the cycloalkyl group present in related azomethines is discussed. Azomethines containing cyclopropyl, cycloheptyl and cyclooctyl rings have lower nematic thermal stability than their cyclopentyl and cyclohexyl homologues.