Stereochemical effect of even-odd connecting links on supramolecular assemblies made of 1-glucosamide bolaamphiphiles

Bolaamphiphiles with a 1-glucosamide-head group at each end, N,N'-bis(beta-D-glucopyranosyl)alkane-1, n-dicarboxamide [Glc-NC(n)CN-Glc, n=6, 9, 10, 11, 12, 13, and 14], have been synthesized. Self-assembled supramolecular structures in water strongly depend on whether a is even or odd, which respectively give rise to fibrous assemblies or planar platelets as well as amorphous solids. In connection with this even-odd effect of the hydrocarbon links, internal molecular arrangements of the solid fibers were investigated using FT-IR spectroscopy, X-ray diffraction and crystal analyses, and transmission electron microscopy. The oligomethylene groups of the Glc-NC(12)CN-Glc pack in a monoclinic or an orthorhombic mode in the fiber. We propose a possible self-assembled model based on a monolayer sheet, which is stabilized by hydrogen-bond networks via sugar-head and amide groups.