View PDF Version
 
DOI: 10.1039/A800866C (Paper) Reference Section for: J. Chem. Soc., Faraday Trans., 1998, 94, 1753-1760

Odd–even effects at the nematic–isotropic and intercalated smectic A–nematic transitions of the non-symmetric α-(4′-cyanobiphenyl-4-yloxy)-ω-(4-alkylanilinebenzylidene-4′-oxy) alkane dimers An experimental study

(Note: The full text of this document is currently only available in the PDF Version )

P. J. Le Masurier and G. R. Luckhurst

Abstract

Liquid crystal dimers, in which two mesogenic groups are linked by a flexible spacer, exhibit a rich smectic polymorphism for both symmetric and non-symmetric dimers with their differing mesogenic groups. For example, dimers with smectic phases having monolayer, interdigitated and intercalated structures have been discovered. We have used DSC to determine the smectic A–nematic transition entropies for non-symmetric dimers having intercalated phases. In addition we have employed EPR and 2H NMR spectroscopy to investigate the orientational order of the nematic and intercalated smectic phases. We have observed a marked reduction in the odd–even effect at the intercalated smectic A–nematic phase transition. This is revealed by an unexpectedly large change in the entropy and increase in the orientational order for the odd spacer dimers at the transition, after allowance is made for the length of the preceding nematic range.

References

  1. G. R. Luckhurst, Macromol. Symp., 1995, 96, 1 CAS.
  2. J. L. Hogan, C. T. Imrie and G. R. Luckhurst, Liq. Cryst., 1988, 3, 645 CAS.
  3. G. S. Attard, R. W. Date, C. T. Imrie, G. R. Luckhurst, S. J. Roskilly, J. M. Seddon and L. Taylor, Liq. Cryst., 1994, 16, 529 CrossRef CAS.
  4. J. Watanabe, H. Komura and T. Niori, Liq. Cryst., 1993, 13, 455 CrossRef CAS.
  5. R. W. Date, C. T. Imrie, G. R. Luckhurst and J. M. Seddon, Liq. Cryst., 1992, 12, 203 CAS.
  6. P. J. Barnes, A. G. Douglass, S. K. Heeks and G. R. Luckhurst, Liq. Cryst., 1993, 13, 203.
  7. A. P. J. Emerson and G. R. Luckhurst, Liq. Cryst., 1991, 10, 861 CAS.
  8. T. Kimura, H. Toriumi and H. Watanabe, Preprints 14th Liquid Crystal Conference Japan, 1988, 14, 238 Search PubMed.
  9. H. Toriumi, D. J. Photinos and E. T. Samulski, First Pacific Conference Preprints, 1989, 1, 185 Search PubMed.
  10. S. K. Heeks and G. R. Luckhurst, J. Chem. Soc., Faraday Trans., 1993, 89, 3289 RSC.
  11. G. S. Attard, C. T. Imrie and F. E. Karasz, Chem. Mater., 1992, 4, 1246 CrossRef CAS.
  12. H. Zimmerman, Liq. Cryst., 1989, 4, 591.
  13. W. L. McMillan, Phys. Rev. A., 1971, 4, 1238 CrossRef; 1972, 6, 936.
  14. A. T. M. Marcelis, A. Koudijis and E. J. R. Sudholter, Liq. Cryst., 1995, 18, 843 CAS.
  15. A. T. M. Marcelis, A. Koudijis and E. J. R. Sudholter, Recl. Trav. Chim. Pays-Bas., 1994, 113, 524 CAS.
  16. A. E. Blatch, I. D. Fletcher and G. R. Luckhurst, Liq. Cryst., 1995, 18, 801 CAS.
  17. G. F. Kventsel, G. R. Luckhurst and H. B. Zewdie, Mol. Phys., 1985, 56, 589 CAS.
  18. G. R. Luckhurst, Liquid Crystals and Plastic Crystals, ed. G. W. Gray and P. A. Windsor, Ellis Horwood Ltd, Chichester, 1974, vol. 2, ch. 7 Search PubMed.
  19. B. J. Gaffney, Spin Labelling. Theory and Application, ed., L. J. Berliner, Academic Press Inc, London, 1976, ch. 5 Search PubMed.
  20. P. J. Le Masurier and G. R. Luckhurst, J. Chem. Soc., Faraday Trans, 1988, 94, 1593 Search PubMed.
  21. G. R. Luckhurst, The Molecular Physics of Liquid Crystals, ed. G. R. Luckhurst and G. W. Gray, Academic Press Inc.London, 1979, ch. 4 Search PubMed.
  22. H. Gunther, NMR Spectroscopy, John Wiley and Sons Ltd, New York, 1995 Search PubMed.
  23. NMR of Liquid Crystals, ed. J. W. Emsley, Reidel, Dordrecht, 1985 Search PubMed.
  24. J. W. Emsley, G. R. Luckhurst and G. N. Shilstone, Mol. Phys., 1984, 53, 1023 CAS.
Click here to see how this site uses Cookies. View our privacy policy here.