ISSN:
1435-1536
Schlagwort(e):
Saccharide-based amphiphiles
;
4-alkyl-semicarbazones
;
gelation of saccharide-amphiphiles
;
self-organization
;
supramolecular organization
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
,
Maschinenbau
Notizen:
Abstract The synthesis of 4-alkyl-semicarbazones derived from reducing sugars and semicarbazides is presented as a convenient route for the preparation of amphiphilic saccharides. This semicarbazone route allows to employ a large variety of reducing sugars as hydrophilic building block for saccharide tensides. The preparation of two series of amphiphiles based on D-maltose with non-methylated and mono-N-methylated semicarbazone units is described. Then-alkyl chains were varied fromn-octyl ton-hexadecyl. Various maltotriose derivatives have also been prepared. Critical micelle concentration (CMC) as well as critical gel concentration of the derivatives were studied in dependence of then-alkyl chain length. Both values decreased with increasing length of then-alkyl chain. Self-organization of the gels was studied by transmission electron microscopy of freeze-fractured samples. Due to the supramolecular organization of the amphiphiles, the gels consisted of twisted rope-like molecular assemblies with the same helical twist sense. The helical pitch depended on the hydrophilic/lipophilic balance. In contrast to gels onn-alkylgluconamides, the gels were formed in dilute aqueous solution and exhibited striking longevity without additional stabilization by surfactants. In the solid, the amphiphiles exhibited thermotropic transitions to partially disordered mesophases.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00652259
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