Title

Hybrid Rod-Like and Bent-Core Liquid Crystal Dimers Exhibiting Biaxial Smectic a and Nematic Phases

Publication Title

Journal of Materials Chemistry

Publication Date

2012

Document Type

Article

DOI

10.1039/c2jm34315k

Keywords

Dielectric Inversion Frequency, Banana Calamitic Dimers, Mesophase Behavior, Homologous Series, Molecular Design, Polar Order, Mesogens, Transition, Field, Unit

Disciplines

Physics

Abstract

Liquid crystal hybrid dimers involving bent-core units and rod-like units were designed, synthesized and investigated by a combination of polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction studies. All the four unsymmetrical dimers 1–4 exhibited stable nematic phases over a wide temperature range. Moreover, dimer 1exhibited the biaxial smectic A (SmA) phase and dimer 2 exhibited a highly ordered mesophase below the nematic (N) phase. Two rod-like and bent-core nematogenic units were covalently linked in dimers 3 and 4 to furnish exclusively the nematic phase. The observation of the biaxial SmA phase underlying the nematic phase in one of the bent-core–rod dimers 1 would be a significant step forward towards achieving the biaxial nematic phase and resolving controversies related to the presence of cybotactic groups.

Comments

Available on publisher's site at http://dx.doi.org/10.1039/c2jm34315k.

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