Supramolecular 4- -(Ω-Hydroxyalkyloxy)-4’-Cyanoazoxybenzenes

Research Article
Sofya A. Kuvshinova., Vladimir A. Burmistrov., Igor V. Novikov Viktor V.Alexandriysky and Oskar I. Koifman
DOI: 
xxx-xxxxx-xxxx
Subject: 
science
KeyWords: 
mesogen, azoxybenzene, hydrogen bond, position isomerism, NMR spectroscopy, nematic phase, supramolecule, dielectric anisotropy, double refraction, sorbent, structural selectivity.
Abstract: 

Herein we discuss physical properties of 4-(ω-hydroxyalkoxy)-4’-cyanoazoxybenzene homologs.1D and 2D correlation NMR spectroscopy (in particular,1Н, 15 N-HMBC experiment) have allowed elucidation of structure of the prepared rod-like supramolecular cyanoazoxybenzenes. Mesomorphic properties of the compounds have been studied by means of polarization thermomicroscopy and differential scanning calorimetry. All the studied cyanoazoxybenzenes have revealed enantiotropic nematic mesomorphism over wide temperature range. Nematic mesophase of the eighth homolog has possessed large positive dielectric anisotropy. Introduction of small amounts of the prepared cyanoazoxybenzenes as additive has stabilized the mesophase and has increased the dielectric anisotropy of 4-pentyloxy-4’-cyanobiphenyl. Gas- liquid chromatography studies have shown that sorbents based on 4-(2-hydroxyethyloxy)-4’-cyanoazoxybenzene are highly selective towards various structural isomers; that cannot be achieved using conventional nematic liquid crystals. Thermodynamic evidence of specific interactions between the mesogen and the non-mesomorphic sorbate has been discovered.