Z-Isomers of 3,3′-disubstituted azobenzenes highly compatible with liquid crystals

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Christian Ruslim and Kunihiro Ichimura


Abstract

It is known that mesophase changes can be induced by E-Z photoisomerization of azobenzenes doped in liquid crystals. Novel azobenzenes have been designed on the basis of Molecular Mechanics and Molecular Orbital calculation, aimed at exploiting novel photoresponsive guest-host liquid crystalline systems exhibiting no mesophase change despite the drastic structural alteration of the guest molecules. It was found that the introduction of alkanoyloxy groups at both the 3- and 3′-positions of azobenzene leads to phase stability of nematic systems upon the E-Z photoisomerization even at a dopant concentration as high as 20 wt%. However phase separation was brought about when 3,3′-dialkoxyazobenzenes and 4,4′-dialkoxyazobenzenes were employed as guest molecules. The relation between the conformational structures of the guests in their E- and Z-isomers and their compatibility with nematic hosts was examined thermodynamically. Experimental results were compared in some details with the simulations. It was shown that 3,3′-dialkanoyloxyazobenzene prefers a rod-like structure in both E- and Z-isomers.


References

  1. M. W. Gibbons, T. Kosa, P. P. Murohay and P. J. Shannon, Nature, 1995, 377, 43 CAS.
  2. T. Sasaki, T. Ikeda and K. Ichimura, Macromolecules, 1992, 25, 3807 CrossRef CAS.
  3. R. H. Berg, S. Hvilsted and P. S. Ramanujam, Nature, 1996, 383, 505 CrossRef CAS.
  4. K. Ichimura, in Photochromism; Molecules and Systems, ed. H. Dürr and H. Bouas-Laurent, Elsevier, Amsterdam, 1990, p. 903 Search PubMed.
  5. W. W. Haas, K. F. Nelson, J. E. Adams and G. A. Dir, J. Electrochem. Soc., 1974, 121, 1667 CrossRef CAS.
  6. S. Tazuke, S. Kurihara and T. Ikeda, Chem. Lett., 1987, 911 CAS.
  7. E. Sackmann, J. Am. Chem. Soc., 1971, 93, 7088 CrossRef CAS.
  8. G. Heppke, H. Marschall, P. Nurnberg, F. Oestreicher and G. Scherowsky, Chem. Ber., 1981, 114, 2501 CAS.
  9. D. S. Hermann, P. Rudquist, K. Ichimura, K. Kudo, L. Komitov and S. T. Lagerwall, Phys. Rev. E, 1997, 55, 2857 CrossRef CAS.
  10. D. Bauman, Mol. Cryst. Liq. Cryst., 1988, 159, 197 CAS.
  11. A. C. de Kock, Z. Phys. Chem., 1904, 48, 129 CAS.
  12. B. M. Bogoslovskii, J. Gen. Chem. USSR, 1946, 16, 193 Search PubMed.
  13. P. J. Collings and M. Hird, in Introduction to Liquid Crystals; Chemistry and Physics, Taylor and Francis, London, 1997 Search PubMed.
  14. Cache Reference, ver. 3.0, CaChe Scientific Inc., USA, 1992 Search PubMed.
  15. P. Ruggli and M. Hinovker, Helv. Chim. Acta, 1934, 17, 411.
  16. R. F. Nystrom and W. G. Brown, J. Am. Chem. Soc., 1948, 70, 3738 CrossRef CAS.
  17. N. Grant, V. Perlog and R. P. A. Sneedan, Helv. Chim. Acta, 1963, 46, 415 CrossRef.
  18. S. R. Sandler and W. Karo, in Organic Functional Group Preparations, 2nd edn., Academic Press Inc., 1986, ch. 14 Search PubMed.
  19. B. Kronberg and D. Patterson, J. Chem. Soc., Faraday Trans. II, 1976, 72, 1687 Search PubMed; B. Kronberg, D. F. R. Gilson and D. Patterson, J. Chem. Soc., Faraday Trans. II, 1976, 72, 1673 RSC.
  20. G. R. Luckhurst and G. W. Gray, in The Molecular Physics of Liquid Crystals, Academic Press, London, 1979, ch. 10 and 11 Search PubMed.
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