Selectively Deuterated Liquid Crystalline Cyanoazobenzene Side-Chain Polyesters. 1. Preparation and Characterization of Precursors and Diols
作者:
Claudia Hendann,
HeinzW. Siesler,
Fulvio Andruzzi,
Christian Kulinna,
Søren Hvilsted,
期刊:
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals
(Taylor Available online 1998)
卷期:
Volume 319,
issue 1
页码: 207-230
ISSN:1058-725X
年代: 1998
DOI:10.1080/10587259808045660
出版商: Taylor & Francis Group
关键词: Deuterated liquid crystals;cyanoazobenzene liquid crystals;side-chain polyesters;diols;spectroscopy of liquid crystals
数据来源: Taylor
摘要:
Diphenyl perdeuterated adipate and tetradecanedioate, and three different, selectively deuterium labeled 2-[6-[4-[(4-cyanophenyl)azo]phenoxy]hexyl]-1,3-propanediols have been prepared by exchange and reduction techniques.1H and2H NMR spectroscopic investigations have revealed the deuterium exchange in the esters to be higher than 93% and evenly distributed. Similarly, a varying but high deuterium exchange was detected in the selectively labeled diols. All deuterated samples were additionally characterized in detail by13C NMR spectroscopy; the deuterium isotope effect conclusively assisted some of the shift assignments. No isotope effect could be detected by visible spectroscopy in any of the deuterated diols. On the other hand, FTIR in all deuterated compounds reveals a substantial frequency shift of all carbon-deuteron vibrations as compared to the corresponding carbon-hydrogen vibrations. Polarizing optical microscopic and differential scanning calorimetric investigations have identified all the deuterium labeled diols as monotropic liquid crystals with both nematic and smectic A phases.
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