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http://dx.doi.org/10.14478/ace.2015.1024

Synthesis and Properties of Unsymmetric Dimesogenic Liquid Crystal Compounds Containing Lateral Substituent  

Park, Jong-Ryul (Division of Advanced Materials Science and Engineering, Kongju National University)
Cho, Kuk Young (Division of Advanced Materials Science and Engineering, Kongju National University)
Bang, Moon-Soo (Division of Advanced Materials Science and Engineering, Kongju National University)
Publication Information
Applied Chemistry for Engineering / v.26, no.3, 2015 , pp. 280-286 More about this Journal
Abstract
Two series of unsymmetric dimesogenic compounds containing a butylene or pentamethylene group as the flexible spacer were synthesized and their thermal and mesomorphic properties were studied. Mesogenic groups of the synthesized compounds consisted of a cholesteryl and an azobenzene group with lateral substituent. Chemical structures and mesomorphic properties of the synthesized compounds were investigated by FT-IR, $^1H$-NMR, differential scanning calorimeter (DSC), and polarizing optical microscope (POM). All synthesized compounds, apart from $D5-OCH_3$, showed enantiotropic liquid crystal phases. Compounds having an even number of carbon atoms in the flexible spacer exhibited wide mesophase temperature ranges and high isotropic transition temperatures. Regarding the effect of lateral substituents, compounds with bulky substituents exhibited decreased mesophase temperature ranges and isotropic transition temperatures, while those with polar substituents showed the increased thermal stability of the smectic phase.
Keywords
azobenzene; cholesteryl; dimesogenic liquid crystal; lateral substituents; unsymmetric;
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