Levo vs. Dextro. Effect of the headgroup chirality on nanoassemblies

Surfactants that bear chiral headgroups form a variety of interesting supra self-assembled nanostructures and can be used for different applications. In particular, ascorbic acid possesses two chiral centers, a rigid planar ring, a powerful redox active moiety, two acidic –OH residues, and a primary –OH group (Figure 1). Here we report our studies on the nanoassemblies produced by D-(-)-isoascorbyl-alkanoates (D-ASCn, with n = 8, 10, 12), carried out through DSC, SAXS, XRD, surface tension, and conductivity experiments. The results suggest that the different configuration of the headgroups induces relevant changes in the structural and physico-chemical properties of the aggregates, due to the different hydration of the two epimers L-ascorbic and D-isoascorbic acid (Figure 1 and 4, respectively). The D-ASC12 and L-ASC12 surfactants produce interesting phase diagrams. The results suggest the formation of a 1 :1 compound, and of two eutectic points.