Raman Scattering Study of Homologous Series of Liquid Crystalline N-[4-(4-n-alkoxybenzoyloxy)-2-hydroxy-benzylidene]-methylamlines

Abstract

N-[4-(4-n-alkoxybenzoyloxy)-2-hydroxy-benzylidene]-methylanilines[nAHmM(n; n=l-8, m; m=2: -ortho, m=3: -meta, m=4: -para)] were newly synthesized. They exhibited a nematic phase except for 1AH3M. The temperature dependence of Raman spectra of nAHmM has been observed in the spectral range of 800-1800cm^<-1>. In a group of nAHmM, the Raman band at about 1365cm^<-1> decreased in intensity and wavenumber through the solid-nematic phase transition. In the other group, the corresponding band increased through the phase transition. The band has been assigned to the φ-N stretching vibration. Such a behavior can be explained by the molecular conformations with different twist angles of the aniline ring to the salicylaldimino part of the molecule. Some of nAHmM showed a photochromic property in the solid state.