Supramolecular assemblies of diacetylenic amphiphiles.

Abstract

Ever since the earliest studies, lipids have always been found in liposomal form. Recently, it was discovered that aqueous solutions of certain glycolipids, phospholipids, and glutamate lipids could form nonspherical morphologies such as tubules or helices when cooled below their liquid to gel phase transitions. We have developed new synthetic polymerizable lipids which form non-spheroidal morphologies when hydrated. The use of diacetylenes has several advantages which include facile incorporation into alkyl chains of amphiphiles, stabilization of assemblies, and the introduction of non-linear optical, and conducting properties into these assemblies. This research may also provide insight into the molecular basis of self-organization. Multistep synthesis of diacetylenic glycosurfactants was performed in which the headgroup was progressively varied by incorporation of different hepto, hexo, pento, and tetrose open chain sugars. The stereochemical, enantiomeric, and hydrophobic/hydrophilic balance of the lipids was investigated as a function of the supramolecular morphologies which they formed. Synthetic diacetylenic lipids based on a glutamic acid backbone were also prepared. These lipids formed liposomes which could be dehydrated under constant temperature and humidity to form cast films with properties similar to Langmuir-Blodgett films. These lipids could also be used as templates to order other compounds which do not otherwise form ordered assemblies. From the work we hope to gain some insight to the molecular components of lipids which are necessary to dictate specific supramolecular morphologies.