Abstract
A homologous series of N-[4-(4-n-alkoxybenzoyloxy)-2-hydroxybenzylidene]-3-chloroanilines [AHC(n; n= 1-8)] was synthesized. AHC(1-3) exhibited a monotropic nematic phase and AHC(4-8) a nematic phase. The temperature dependence of infrared(IR) spectra of ABCs has been observed in the spectral range of 1800-600 cm-1. Some of the IR bands changed in intensity and wavenumber as AHCs undergo the phase-transition. Their changes can be explained by the change of the molecular conformation through the phase-transition. AHC(1-5, 7, 8) were yellow when freshly prepared and deepened to pale-orange by ultra-violet irradiation. At room temperature, the colored species thermally faded in the dark with time. The kinetics analysis of the thermal fading exhibited a good fit to a double-exponential equation, consisting of a two-state transient decay (rate constants: k1 and k2).
