Thermotropic Compounds with Two Terminal Mesogenic Units and a Central Spacer. 51. Homologous Series of Polymethylene-α, ω-Bis (p-Oxybenzylidene Aniline)

Two series of new thermotropic compounds with two terminal mesogenic units, p-oxybenzylidene-p-substituted anilines, attached to both ends of a central polymethylene spacer were prepared. The first series of compounds has central polymethylene spacers of varying length, while the second has different substituents on the aniline moiety of the mesogenic groups which are bracketing the central decamethylene spacer. The mesomorphic properties of the compounds were investigated by differential scanning calorimetry and on the hot-stage of a polarizing microscope. A thermodynamic analysis of the phase transitions of the compounds was made and the results are explained in relation to their structure.