• Symmetrical trimeric star-shaped mesogens based on 1,3,5-trisubstituted benzene incorporating Schiff base and azobenzene fragments as the peripheral units: Synthesis and mesomorphic properties

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    • Keywords

       

      Star-shaped liquid crystals; symmetrical; terminal substituent; Schiff base and azobenzene moieties; comparative study.

    • Abstract

       

      Two series of symmetrical three-armed star-shaped mesogens based on 1,3,5-trihydroxybenzene as a core unit, interconnecting three Schiff base or azobenzene moieties via oxymethylene spacers have been synthesized and characterized by spectroscopic techniques. Every member in these series possesses either chlorine (Cl) or bromine (Br) terminal atom, with different alkyl spacer length (C$_n$H$_{2n}$ whereby 𝑛 ranging from 3 to 6). Their thermal stability and mesomorphic properties are investigated by employing DSC and POM. The dependence of phase transition in relation to the alkyl spacer length is shown by both series. These star-shaped mesogens exhibit only nematic and smectic phases. The difference between the two series lies on the structure of linking group in the peripheral units (-CH=N- for series PSB-X-𝑛 and -N=N- for series PAZ-X-n). Therefore, a comparison study of the mesomorphic properties between these two series of star-shaped mesogens is discussed whereby the azobenzene-basedmesogens are thermally more stable than the Schiff base counterpart. In addition, soft crystalline phase is observed for the azobenzene-based star-shaped mesogens possessing hexyl alkyl spacer.

    • Author Affiliations

       

      Guan-Yeow Yeap1 Yew-Hong Ooi1 Nozomi Uchida2 Masato M Ito2

      1. Liquid Crystal Research Laboratory, School of Chemical Sciences, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia
      2. Department of Environmental Engineering for Symbiosis, Faculty of Engineering, Soka University, Hachioji, Tokyo 192-8577, Japan
    • Dates

       
  • Journal of Chemical Sciences | News

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