| Autor: |
Ewing, D. F., Goodby, J. W., Haley, J. A., Kelly, S. M., Letellier, P., Mackenzie, G. |
| Předmět: |
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| Zdroj: |
Liquid Crystals; Nov97, Vol. 23 Issue 5, p759-769, 11p |
| Abstrakt: |
A variety of N -acyl- beta -D-glucopyranosylamines, N -acyl- beta -D-mannopyranosylamines and 2-alkylamido-2-deoxy- alpha / beta -D-glucoses has been prepared regiospecifically and in good yield in a one step reaction of the appropriate acid chloride with D-mannosylamine, 2-amino-2-deoxyD-glucopyranose (prepared in one step from glucose and mannose according to literature methods) and D-glucosamine liberated in situ from the commercially available hydrochloride. The dependence of the liquid crystal transition temperatures and mesophase formation on the degree and nature of intermolecular hydrogen bonding has been studied by choosing two different carbohydrate cores and by attaching aliphatic terminal chains via an amide linkage in two different positions. Comparison is made with related compounds reported in the literature. Whereas the N -acyl- beta -D-mannopyranosylamines and N -acyl- beta-D-glucopyranosylamines possess wide-range smectic A* phases, the corresponding 2-alkylamido-2-deoxy- beta-Dglucopyranoses do not exhibit observable mesomorphism. Although some homologues of the compounds synthesized have already been reported in the literature, their liquid crystalline behaviour was not reported. These investigations confirm the general view that it is the number and type of hydrogen bonding groups on the carbohydrate moiety and the aliphatic chain length that primarily determine thermotropic mesophase behaviour, as well as the absolute values of the transition temperatures. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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