Influence of the ester chain length on the mesogenic behavior and optical anisotropy of 4-[[4-(butoxy)phenyl]diazenyl]phenyl alkanoates. (2nd April 2016)

• Record Type: Journal Article
• Authors: Niezgoda, Izabela; Szypszak, Ewelina; Dardas, Dorota; Galewski, Zbigniew
• Is Part Of: Phase transitions. Volume 89:Number 4(2016)
• Page Start: 393
• Page End: 402
• Publication Date: 2016-04-02
• Subjects: liquid crystals -- azobenzene -- DSC -- optical anisotropy -- birefringence; Phase transformations (Statistical physics) -- Periodicals; 530.47405
• DOI: 10.1080/01411594.2015.1127921
• Languages: English
• ISSNs: 0141-1594

Abstract

Abstract : In this manuscript, we report synthesis and physico-chemical characterization of 4-[[4-(butoxy)phenyl]diazenyl]phenyl alkanoates homologous series. For the first time, nineteen derivatives are described here. The enantiotropic nematic phase is typically observed among all members of this series. However, in the case of 4-[[4-(butoxy)phenyl]diazenyl]phenyl stearate, the nematic phase shows a monotropic character. In addition to liquid-crystalline polymorphism, a second crystalline form was observed in some homologs. Furthermore, using a photoelastic modulator, the optical anisotropy in the nematic phase was determined in the first nine compounds of this series. Temperature dependence of optical anisotropy at significantly lower values of reduced temperature is relatively weak. In contrast, optical anisotropy shows a strong temperature effect near isotropization. Moreover, the influence of the ester chain elongation on liquid crystalline and optical properties was established.