Solvent-free construction of self-assembled 1D nanostructures from low-molecular-weight organogelators: sublimation vs. gelation

The formation of self-assembled fibrillar networks in the absence of solvent is reported for a whole family of amino acid derived gelators containing nicotinoyl and isonicotinoyl terminal groups. Fibrillar networks can be formed easily by a sublimation process (vapor-solid method). In this work is reported an unprecedented comparison of the microfibrillar structures formed by organogelators within a solvent (acetonitrile and toluene) and in the absence of solvent. The use of different techniques such as scanning electron microscopy (SEM), wide-angle X-ray diffraction or FT-IR revealed that, for these compounds, the solvent did not influence significantly the intrinsic tendency of these molecules to form 1D nanostructures. However, SEM revealed that solvent effects were evident at higher levels of organization in connection with phenomena as fibril-fibril fusions and at the molecular level by the stabilization of different polymorphs.