Properties of the liquid crystals formed by certain 4-alkoxy-N-(9-oxofluoren-2-ylmethylene)anilines

Abstract

The liquid crystal transition temperatures of 13 4-alkoxy-N-(9-oxofluoren-2-ylmethylene)anilines are reported and discussed. The series gives a transition temperature plot of a similar type to that of the 2-p-alkoxybenzylideneaminofluorenones (in which the –CHN– linkage is reversed), the N–I transition temperatures showing minima then maxima for the early homologues, but smectic properties do not occur until a late stage in the homologous series. Differences in liquid crystal thermal stability between the two series of azomethines of 9-oxofluorene are compared with the corresponding values for the 9,10-dihydrophenanthrene and biphenyl derivatives.