2H NMR Spectroscopic Investigation of para-Nitroazobenzene Liquid Crystals  

作　　者：LI Min LUCKHURST Geoffrey R. TIMIMI Bakir A. QIU Hong Jin CHEN Xin fang 

机构地区：[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,sO171BJ,UK

出　　处：《Chemical Research in Chinese Universities》2001年第1期108-114,共7页高等学校化学研究(英文版)

基　　金：SupportedbytheNationalNaturalScienceFoundationofChina(No .2 96 0 40 0 2 )andChineseScholarshipCounci

摘　　要：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 d 18 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) ( P 2=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.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 d 18 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) ( P 2=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.

关 键 词：H NMR para Nitroazobenzene liquid crystal Orientational parameter 

分 类 号：O657.2[理学—分析化学]