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http://dx.doi.org/10.14478/ace.2019.1009

Synthesis and Characterization of Reactive Liquid Crystalline Compounds with Azo-mesogenic Groups at the 4-, 3,5-, or 3,4,5-Positions of Phenyl Ring  

Park, Jong-Ryul (Division of Advanced Materials Science and Engineering, Kongju National University)
Yoon, Doo-Soo (Department of Bioenvironmental & Chemical Engineering, Chosun College of Science & Technology)
Bang, Moon-Soo (Division of Advanced Materials Science and Engineering, Kongju National University)
Publication Information
Applied Chemistry for Engineering / v.30, no.2, 2019 , pp. 247-253 More about this Journal
Abstract
In this study, compounds with azo-mesogenic groups at 4-, 3,5-, or 3,4,5-positions of one phenyl ring were synthesized, and their liquid crystallinity and photochemistry were investigated. The compounds in the Azo1 and Azo2 series had linear and planar geometries, respectively, while those in the Azo3 series had relatively bulky structures. Compounds of BA-Azo2 and BA-Azo3 did not show any liquid crystallinity. Compounds of BE-Azo1 and BE-Azo2 exhibited a monotropic liquid crystallinity, while the other compounds showed an enantiotropic liquid crystallinity. The liquid crystalline behavior was imparted by the azo-mesogenic groups, and most of the liquid crystalline compounds formed a smectic phase. All the RM-AzoX compounds exhibited photoisomerism because of the presence of the azo groups in the molecule. The rate of photoisomerization followed the order of RM-Azo3 < RM-Azo1 < RM-Azo2 and was considered to depend on the steric hindrance around the azobenzene groups in the molecule. These results suggest that the liquid crystallinity and photochemical property of the compounds are affected by the position or the number of azo-mesogenic groups phenyl ring of the molecule.
Keywords
Azobenzene; Paired mesogenic; Photoisomerization; Reactive liquid crystal;
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