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Synthesis and Properties of Di-azomesogenic Liquid Crystal Compounds with Terminal Substituents

말단에 치환기를 갖는 이-아조메소젠 액정화합물의 합성 및 성질

  • Park, Jong-Ryul (Division of Advanced Materials Science and Engineering, Kongju National University) ;
  • Gu, Su-Jin (Division of Advanced Materials Science and Engineering, Kongju National University) ;
  • Yoon, Doo-Soo (Dept. of Bioenvironmental & Chemical Engineering, Chosun College of Science & Technology) ;
  • Bang, Moon-Soo (Division of Advanced Materials Science and Engineering, Kongju National University) ;
  • Choi, Jae-Kon (Dept. of Biochemical & Polymer Engineering, Chosun University)
  • 박종률 (공주대학교 신소재공학부) ;
  • 구수진 (공주대학교 신소재공학부) ;
  • 윤두수 (조선이공대학교 생명환경화공과) ;
  • 방문수 (공주대학교 신소재공학부) ;
  • 최재곤 (조선대학교 생명화학고분자공학과)
  • Received : 2015.09.09
  • Accepted : 2015.11.02
  • Published : 2015.12.10

Abstract

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, $^1H-NMR$, differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and UV-visible spectrometry. P-H, P-F, and $P-OC_6H_{13}$ 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 (${\lambda}_{max}$) and the rate of photoisomerization (K).

Keywords

azobenzene;dimesogenic;liquid crystals;photoisomerization;terminal substituent

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