Alkylglycosides with an lsoprenoid-type hydrophobic chain can afford greater control of aqueous phase structures at low temperatures

We have proposed novel alkylglycosides, AGs, that consist of an isoprenoid-type hydrophobic chain, the 3,7,11,15-tetramethylhexadecyl (phytanyl) group. One notable feature of the proposed AGs lies in the fact that their Krafft eutectic temperatures, T-K, are well below room temperature although the total number of carbon atoms in the hydrophobic chain is as large as 20. As compared to the conventional AGs with straight and saturated alkyl chains, their low TK values significantly expand our freedom to control their aqueous phase structures at low temperatures. The aqueous phase structures are controlled by modification of the headgroup: an H-II phase for the glycerol headgroup, a cubic phase with crystallographic space group Pn3m/Pn3 at low temperatures and an HII phase at higher temperatures for a xylose headgroup, and an L-alpha phase for a glucose and a maltose headgroup.