Ferroelectric liquid crystals derived from isoleucine II. Orientational ordering by carbon-13 separated local field spectroscopy
| Autor: | Edward T. Samulski, Chi-Duen Poon, Aidi Chen, Theo J. Dingemans |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Biphenyl
Materials science Carbon-13 General Chemistry Nuclear magnetic resonance spectroscopy Condensed Matter Physics Ferroelectricity Crystallography chemistry.chemical_compound chemistry Liquid crystal Organic chemistry General Materials Science Spectroscopy Local field Magnetic dipole–dipole interaction |
| Zdroj: | Liquid Crystals. 24:255-262 |
| ISSN: | 1366-5855 0267-8292 |
| DOI: | 10.1080/026782998207433 |
| Popis: | The orientational ordering of a series of ferroelectric liquid crystals 4'-[(2S, 3S)-3-methyl- 2-halopentanoyloxy]-4-hexyloxybiphenyls (3M2XPHOB, X=F for fluorine, C for chlorine, B for bromine) and their racemates have been studied by two-dimensional carbon-13 separated local field spectroscopy combined with off-magic-angle spinning. All carbons are well-resolved in the carbon-13 NMR spectrum so that carbon-proton dipolar coupling constants for all carbons in the liquid crystal molecule can be determined, giving detailed segmental orienta- tional ordering information. (The order parameters of the biphenyl core segments and each carbon-proton bond in the aliphatic chains were measured as a function of temperature.) The results show that the substitution of different halogens on the chiral chain affects the carbon- proton bond orientational ordering of the entire chiral chain, while the orientational ordering of the rest of the liquid crystal molecule (core and achiral chain) remains unchanged. For the flu... |
| Databáze: | OpenAIRE |
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