Solid State Polymorphism of Some 4,4′-Disubstituted Phenylcyclohexanes

Abstract

The phase transitions and thermal properties of some mesogenic 4,4′-disubstituted phenylcyclohexanes (PCH) have been extensively studied using a differential scanning calorimeter and a polarizing microscope. The complex phase relation assumed for PCH 3 was unambiguously confirmed. Three distinct melting points of PCH 3 were observed and their conditions of individual occurrence determined. A further compound, PCH 7, showed an even more complicated melting behavior, namely four individual melting points. Their conditions of occurrence were also analyzed. The respective enthalpies of transition were determined using the DSC-method. The occurrence of solid state polymorphism and the reason for its existence are discussed for PCH 3.