Chirality control of self-assembling organogels from a lipophilic L-glutamide derivative with metal chlorides

A double-chain alkyl lipid with an isoquinoline-containing headgroup was derived from L-glutamide. This worked as an organogelator in benzene, cyclohexane, a cyclohexanes-ethanol mixture, and so forth. Transmission electron microscope observation showed that the gelation was brought about through the formation of a fibrillar network, and circular dichroism (CD) spectra indicate that the fibrillar aggregates were based on highly ordered structures. The critical aggregation concentration (cac) was estimated by detecting the enhancement of CD strength due to molecular orientation. The cac's were dependent on solvents and always lower than the critical gelation concentration. This indicates that the sol state includes supramolecular aggregates inside which the lipids are well developed. In addition, it was confirmed that the chirality and morphology of the aggregates are remarkably perturbed by chelating with metal chlorides. In the case of CuCl2 which can form a square planar coordination, the chirality enhancement was observed, but in the case Of CoCl2 and ZnCl2 which can form an octahedral coordination state, serious morphological change was observed with remarkable decrease of the chirality.