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Five homologous series of the four-ring 4-substituted phenylazo phenyl 4ʹ-(4ʹ-alkoxy phenylazo) benzoates (Ina-e) were prepared and their mesophase behaviour investigated by differential scanning calorimetry (DSC) and phases identified by polarised light microscopy (PLM). Compounds prepared were structurally characterised via infrared, 1H-NMR, mass spectroscopy, thermogravimetric and elemental analysis. Transition temperatures were first correlated with the alkoxy-chain length (n, that varies between 6, 8, 10, 14, and 16 carbons) within each homologous series, and again with the polarisability anisotropy (ΔαX) of the Ar-X bond, where X changes between CH3O, CH3, H, Br, and CN groups. Comparative studies were made to investigate the effect of introducing the extra phenyl azo moiety into the previously investigated three-ring compounds, 4-substituted phenyl 4′-(4″-alkoxyphenylazo) benzoates (IIna-e), 4-substituted phenylazo 4′-(4″- alkoxy phenyl) benzoates (IIIna-e), and 4-(4′-alkoxy phenylazo) phenyl 4″-substituted benzoates (IVna-e), each bear the same polar group, X, and the alkoxy group, n. [ABSTRACT FROM AUTHOR]