Non-Amphiphilic Carbohydrate Liquid Crystals Containing an Intact Monosaccharide Moiety
摘要:
A chiral rigid moiety which forms the basis of a new class of non-amphiphilic carbohydrate liquid crystals has been developed. This moiety contains a fully intact glucopyranose ring embedded in a trans-decalin structure. The original carbohydrate is substituted so that only two hydroxyl groups are left, resulting in derivatives with reduced hydrophilicity. The substituents R and X-R' on the 4,6-O-ylidene beta-D-glucopyranoside are in the equatorial position and can be varied extensively, using straightforward synthetic procedures. Investigations as to the requirements for R and X-R' for inducing liquid-crystalline behavior have shown that at least one of the substituents should contain a large, polarizable aromatic moiety. An aromatic Schiff base fulfils this requirement.
The perfluorohexyl-aryl-thioethers 3 and 4, building blocks for the synthesis of the chiral target mesogens 12-15, were prepared by dithionite-mediated S-perfluoroalkylation of the p-substituted thiophenols 1 and 2. The phenolic HO- group of 3 was O-glucosylated with pentaacetyl-D-glucopyranose to 5 followed by deacetylation forming the tetrol 6 and by acetalizing with 4-(4-perfluorohexylsulfanylbenzoyloxy)-benzaldehyde-dimethylacetal (8) generating the dihydroxy-intermediate 9. The latter contains two perfluorohexylthio chains. Alternatively, the dimethylacetal 8 was linked to p-octylphenyl-beta-(D)-glucopyranoside (10) giving the mixed octyl/perfluorohexyl substituted p-octylphenyl-4,6-O-[4'-(4"-perfluorohexylsulfanyl)-benzoyloxy]-benzylidene-beta-(D)-glucopyranoside (11). Compound 8 was obtained via esterification of 4 with p-hydroxy-benzaldehyde to 4-(4-perfluorohexylsulfanyl-benzoyloxy)-benzaldehyde (7). Finally, the diols 9 and 11 were dehydroxylated to 12 and 13 followed by hydrogenation yielding 14 and 15, respectively. Tetrol 6, diols 9, 11 and the non-amphiphilic compounds 7, 12-15 are thermotropic liquid crystals. (C) 2002 Elsevier Science B.V. All rights reserved.
Non-Amphiphilic Carbohydrate Liquid Crystals Containing an Intact Monosaccharide Moiety
作者:E. Smits、J. B.F.N. Engberts、R. M. Kellogg、H. A. Van Doren
DOI:10.1080/10587259508038691
日期:1995.2
A chiral rigid moiety which forms the basis of a new class of non-amphiphilic carbohydrate liquid crystals has been developed. This moiety contains a fully intact glucopyranose ring embedded in a trans-decalin structure. The original carbohydrate is substituted so that only two hydroxyl groups are left, resulting in derivatives with reduced hydrophilicity. The substituents R and X-R' on the 4,6-O-ylidene beta-D-glucopyranoside are in the equatorial position and can be varied extensively, using straightforward synthetic procedures. Investigations as to the requirements for R and X-R' for inducing liquid-crystalline behavior have shown that at least one of the substituents should contain a large, polarizable aromatic moiety. An aromatic Schiff base fulfils this requirement.
Rational design of reversible inhibitors for trehalose 6-phosphate phosphatases
作者:Chunliang Liu、Debra Dunaway-Mariano、Patrick S. Mariano
DOI:10.1016/j.ejmech.2017.02.001
日期:2017.3
ortholog is 5.3 ± 0.6 μM, 70-fold smaller than the substrate Michaelis constant. The bindingspecificity of 9a was demonstrated using several representative sugar phosphate phosphatases from the HAD enzyme superfamily, the T6PP protein fold family of origin. Lastly, correlations drawn between T6PP active site structure, inhibitorstructure and inhibitorbinding affinity suggest that the aryl d-glucopyranoside