Molecular Orientation and Odd-Even Effect in Nematogenic Homologous Series of 4-Cyanophenyl-4′-N-Alkylbenzoate

Abstract

The orientational behavior of liquid crystals from homologous series of 4-cyanophenyl-4′-n-alkylbenzoate (C_nH_2n+1PhCOOPhCN) doped with dichroic dyes was investigated by means of optical spectroscopy methods: electronic absorption and fluorescence. The absorption and emission spectra of linearly polarized light were recorded as a function of temperature in whole range of the mesophase. The second- and fourth-rank order parameters (<P₂>, <P₄>) and molecular distribution function were determined.The odd-even effect for the order parameter, explained as the alternation of interaction between alkyl chains, was observed. An influence of the dye molecular structure on the orientational order of the liquid crystal/dye mixture was reported.

Keywords:

• Dichroic dye
• electronic absorption
• fluorescence
• liquid crystal
• odd-even effect
• order parameter

Acknowledgment

This work was supported by Poznań University of Technology Research Project No 64-001/2010.

Notes

() – monotropic phase.