3D crystalline order with 1 nm resolution is observed in aqueous solutions of supramolecular nanotubes at concentrations as low as 6 wt%. The nanotubes are self-assembled from ionic star-like mesogens with three oligobenzamide branches. 50 such molecules arrange radially into supramolecular rings which, in turn, stack on top of each other to form long hollow tubes with 15 nm outer diameter. Parallel nanotubes arrange on a perfect hexagonal lattice, separated by a layer of water of at least 4-10 nm thickness, depending on concentration. While the inter-axial tube distance a increases with dilution, the tube shape remains unchanged as shown by electron density maps. Unexpectedly, fiber diffraction on sheared solutions reveals numerous hkl Bragg reflections on several highly aligned layer lines. These reflections indicate longitudinal interlock between the tubes and 3D crystalline order with molecular-scale detail transferred over long distance through the aqueous suspension. The crystalline order is improved with increasing concentration, which is accompanied by a slowing dynamics of the tubes as probed by X-ray photon correlation spectroscopy; this suggests that intra-tube order is enhanced by inter-tube interlock. A molecular model of the tubes is proposed, based on X-ray diffraction and cryo-TEM, showing a non-centrosymmetric structure based on a network of hydrogen- and π-bonds. The observed high 3D order can be understood in terms of long-range attractive forces between like-charged tubes and the extremely high intra-tube correlation length. Is it necessary to include the details in the abstract? This paragraph is rather long with many details which might distract the readers’ attention from the main point.

Crystalline order propagates across thick layers of water in solutions of supramolecular nanotubes

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