Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Organic Chemistry

Two homologous series of the three-ring azo/ester compounds 2-(or1-) naphthyl 4'-(4''-alkoxy phenylazo) benzoates (Ina and IIna) were synthesized and characterized for their thermal behavior in order to investigate the effect of orientation of the naphthyl group on the mesophase behavior. A lateral methyl group was introduced into different positions of the alkoxy phenyl moiety, in position-2 to give series Inb and IInb and in position-3 to give series Inc and IInc to study the effect of insertion of a lateral substituent on the mesomorphic behavior of the synthesized compounds. Molecular structures of all of the prepared compounds were characterized via elemental analyses, fourier-transform infrared spectroscopy and 1H-NMR sspectra.Their mesophase characteristics were investigated by differential scanning calorimetry (DSC) and their phases identified via polarized light microscopy (PLM).Transition temperatures were correlated with the alkoxychain length (n), that varies between 6, 8, 10, 12, 14, and 16 carbons

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