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Abstract
Two series of new pyridine-based azo dyes were prepared. The first, namely 4-(3{u2032}-pyridylazophenyl)-4{u2032}{u2032}-alkoxy benzoates (In), is a homologous series that bears terminal alkoxy group with a number of carbon atoms varies between 8, 10, 12, 14, and 16 carbons, respectively. The terminal substituent, X, in the second series, Ia-e, is a compact group with certain polarity that, alternatively, changes between electron donating (CH3₃O, CH₃) and electron withdrawing (Br, NO₂), together with the unsubstituted one ( i.e., X= H). The structures of the prepared compounds were confirmed via infrared spectroscopy (IR), nuclear magnetic resonance (NMR), mass spectrometry and elemental analysis. Their mesophase behavior was investigated via differential scanning calorimetry (DSC) and polarized light microscopy (PLM). All homologues of the first series, (In), were found to be mesomorphic, while all derivatives of the latter, Ia-e, were nonmesomorphic