CRCU

Chemical Research in Chinese Universities ›› 2001, Vol. 17 ›› Issue (1): 108-114.

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2H NMR Spectroscopic Investigation of para-Nitroazobenzene Liquid Crystals

LI Min1,2, LUCKHURST Geoffrey R.2, TIMIMI Bakir A.2, QIU Hong-Jin1, CHEN Xin-fang1   

  1. 1. Department of Materials Sciences, Jilin University, Changchun 130021, P. R. China;
    2. Department of Chemistry and Southampton Institute of Liquid Crystals, University of Southampton, Highfield, Southampton, SO17 1BJ, UK
  • Received:1999-10-23 Online:2001-01-24 Published:2011-08-04
  • Supported by:

    Supported by the National Natural Science Foundation of China(No.29604002)and Chinese Scholarship Council.

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Abstract: The orientational order of two liquid crystals , namely, 6-［4-(4-nitrophenylazo)phenyloxy］ hexyl diethanolamines(C6) and 10-1-bromo［4-(nitrophenylazo)phenyloxy］ alkane(B10) was studied by means of 2H NMR spectroscopy with hexamethylbenzene-d18 as the probe molecule. The results show that the directors in the smectic A phase of C6 and the nematic phase of B10 could be aligned, which was parallel to the magnetic field. The orientational order parameter of the solute molecules in C6 was about 0.2, while it is only 0.1 in B10, which is expected because the more ordered smectic phase tends to align solute molecules to a high level. Compared to the orientational order parameter of the solute in the SmC phase of 4［3,4,5-tris(4-dodecyloxybenzyloxy)-benzoyloxy］-4-(4′-dodecyloxybenzoyloxy)biphenyl (Ⅰ) (P2=0.14 ), it is larger in SmA phase of C6. The relatively higher orientational order parameter of the solute in C6 is attributed to the formation of intermolecular H-bonds in the SmA phase of C6.

Key words: 2H NMR, para Nitroazobenzene liquid crystal, Orientational parameter