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New U-shaped Liquid Crystals Azobenzene Derived from Catechol for Photoswitching Properties

Lutfor, M. R. and Biswas, Tapan Kumar and Sarkar, Shaheen M. and M. M., Yusoff and Muhammad Nor Fazli, Abd Malek and Tschierske, Carsten (2015) New U-shaped Liquid Crystals Azobenzene Derived from Catechol for Photoswitching Properties. Journal of Molecular Liquids, 202. pp. 125-133. ISSN 0167-7322

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Abstract

A new series of liquid crystals whose molecular structure consists of a U-shaped unit as a central core and two rod-like azobenzenes as the peripheral units are synthesized. The mesomorphic properties were investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction. The existence of nematic and smectic A phase was confirmed by textures and X-ray diffraction. The trans-form of azo compounds showed a strong band in the UV region at ~365 nm for the π–π* transition, and a weak band in the visible region at ~450 nm due to the n–π* transition. These molecules exhibit a strong photoisomerization behavior in which trans–cis take 50 and 55 s for compounds L4/5 and L4/6, respectively, whereas cis–trans take place almost 29 and 30 h, respectively. Long thermal back relaxation allows us to realize that optical storage devices with these materials which need longer periods.

Item Type: Article
Uncontrolled Keywords: Azobenzene; U-shaped; Smectic phase; Isomerisation; Photoswitching
Subjects: Q Science > QD Chemistry
Faculty/Division: Faculty of Industrial Sciences And Technology
Depositing User: PM. Dr. Md. Lutfor Rahman
Date Deposited: 09 Jan 2015 02:36
Last Modified: 14 Feb 2018 07:17
URI: http://umpir.ump.edu.my/id/eprint/8118
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