Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Organic Chemistry

Eight homologous series of laterally substituted three-ring azo/ester compounds (Ina-h) including the un-substituted homologues (Inc), were prepared and investigated for their mesophase formation and stability. Within each of the homologous series, namely 2-(or 3-) substituted phenyl 4-(4-alkoxy phenylazo) benzoates, the number of carbons in the terminal alkoxy group varies between 6 and 12 carbons. The lateral substituent on the other terminal ring varies between the electron-donating (CH3) and electron-withdrawing (F, Br, and CN) groups, including the hydrogen (H). The study is conducted to investigate the effect of polarity, position, size, as well as the spatial orientation of the lateral substituent, on the mesomorphic properties of the produced derivatives. Molecular formulae of all compounds prepared were confirmed via elemental analyses, IR, 1H-NMR, and MS. Their mesophase behavior were characterized by differential scanning calorimetry ( DSC), and mesophases identified by polarized light microscopy (PLM), and confirmed by miscibility with standard SmA compound. A comparative study was made between the investigated compounds and their previously prepared linearly substituted isomers, namely, 4-substituted phenyl 4- (4-alkoxy phenylazo) benzoates (Ini-k)

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