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Synthesis and Properties of Di-azomesogenic Liquid Crystal Compounds with Terminal Substituents
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  • Journal title : Applied Chemistry for Engineering
  • Volume 26, Issue 6,  2015, pp.698-705
  • Publisher : The Korean Society of Industrial and Engineering Chemistry
  • DOI : 10.14478/ace.2015.1100
 Title & Authors
Synthesis and Properties of Di-azomesogenic Liquid Crystal Compounds with Terminal Substituents
Park, Jong-Ryul; Gu, Su-Jin; Yoon, Doo-Soo; Bang, Moon-Soo; Choi, Jae-Kon;
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Two series of symmetric dimesogenic compounds containing a butylene or 1-methylbutylene spacer as a flexible group were synthesized. The mesogenic groups of synthesized compounds consist of an azobenzene group with a terminal substituent. Chemical structures as well as, thermal, mesomorphic, and photochemical properties of the synthesized compounds were investigated using FT-IR, , differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and UV-visible spectrometry. P-H, P-F, and showed monotropic liquid crystal phases, whereas the others showed enantiotropic liquid crystal phases. Compounds with butylene group as a flexible spacer exhibited wider mesophase temperature ranges and higher thermal transition temperatures than compounds containing a 1-methylbutylene group. Compounds with a high absolute value of the Hammett substituent constant exhibited high thermal transition temperatures and improved stability in the liquid crystal phase. Furthermore, in the absence or presence of UV light illumination, terminal substituents of the azomesogenic group were important factors in deciding the maximum absorbance wavelength () and the rate of photoisomerization (K).
azobenzene;dimesogenic;liquid crystals;photoisomerization;terminal substituent;
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