Abstract
Racemic and optically active double chained cationic amphiphiles, (2 RS) -and (2 S) -N, N, N, N', N'-pentamethyl-N'- (2, 3-diacyloxypropyl) ethylenediammonium diiodides, were prepared and studied so as to clarify the influence of optical isomerism on surface and colloidal properties, such as surface tension, surface pressure and phase transition temperature.
The morphologies of the aggregates in dilute aqueous solution were investigated by electron microscopy. Well developed multilamella vesicles (MLV) and small unilamella vesicles (SUV) were readily formed from the amphiphiles, depending the conditions of sample preparation.
Phase transition temperature (Tc) of the amphiphile was examined by differential scanning calorimetry. In an amphiphile/water mixed system, optically active sinister homologs showed higher Tc than the corresponding racemates, regardless of amphiphile content.
Surface pressure measurements of amphiphiles at the air/water interface indicated the optically active isomers to always have higher surface pressure than the recemate for the same area/molecule.
The properties of aggregate in aqueous solution thus appear to be highly dependent on stereospecific orientation that is influenced by amphiphile chirality.
