FT-far IR spectroscopy and microtextural polarization analysis of complexes: nematics with hydrogen-bonded dimers of 4,n-alkyloxybenzoic acids with 4-hydroxypyridine

A new class of mixtures: 4,n-alkyloxybenzoic acids (n-OBA) and 4-hydroxypyridine (HOPY) are investigated using FT-Far IR spectroscopy and polarisation microscopy. The macroscopic (chirality and structure phase transition induced by the mixture) and the spectroscopic (dynamic of the OH-bond deformation vibrations) characteristics of the complexes built through the bonding of both kinds of molecules are discussed. A weight ratio n-OBA:HOPY about 20 is predicted to be the most effective for realisation of a consistence with suitable chiral and anisotropic properties. The influence of the hydrophilic (polyvinylalcohol) and hydrophobic (polyimide) orienting surface on the spectral and textural properties of the complex is considered. A pronounced liquid crystal (characterized with fluid chains)–gel (rigid chains) transition was observed. An aggregation mechanism of the complex realization is suggested. q 2004 Elsevier B.V. All rights reserved.