Modification of self-assembled nanotubes by click chemistry generates new nanotubes by an out-of equilibrium process

Abstract

An aromatic diamide compound self-assembles in non-polar solvents to form nanotubes with diameters of 27 nm. We have synthesized different analogues of this compound and we found that the ones bearing an alkyne or an azide group are still able to form nanotubes with diameters of the same order. The functional groups offered the possibility to perform copper catalyzed alkyne and azide cycloadditions (CuAACs), which were achieved directly on the self-assembled tubes. The reaction yielded new nanotubes with similar dimensions to the starting ones, as shown by freeze fracture electron microscopy and SAXS. Chemical analysis of those tubes shows that they are composed mainly of the reacted molecules. When these new nanotubes are dissociated by heat they cannot be re-assembled from their constituting molecules, which shows that they do not result from a conventional reversible self-assembly at equilibrium.