Spectroscopic and theoretical investigations of the self-assembly of a particular 1,3,5-benzene trisamide-based low molecular weight hydrogelator are described. This trisamide is pH-sensitive, and surprisingly forms a photoluminescent supramolecular hydrogel. Controlled gel formation in combination with the luminescence properties allows studying the self-assembly process in detail. The experimental results are confirmed by Density Functional Theory (DFT) calculations, revealing that the photoluminescence originates from the formation of a supramolecular chromophore.

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Hydrogels have many applications in biomedical surface modification and tissue engineering. However, the structuring of hydrogels after their formation represents still a major challenge, in particular due to their softness. Here, a novel approach is presented that is based on the combination of atomic force microscopy (AFM) and nanofluidics, also referred to as FluidFM technology. Its applicability is demonstrated for supramolecular hydrogel films that are prepared from low-molecular weight hydrogelators, such as derivates of 1,3,5-benzene tricarboxamides (BTAs). BTA films can be dissolved selectively by ejecting alkaline solution through the aperture of a hollow AFM-cantilever connected to a nanofluidic controller. The AFM-based force control is essential in preventing mechanical destruction of the hydrogels. The resulting "chemical writing" process is studied in detail and the influence of various parameters, such as applied pressure and time, is validated. It is demonstrated that the achievable structuring precision is primarily limited by diffusion and the aperture dimensions. Recently, various additive techniques have been presented to pattern hydrogels. The here-presented subtractive approach can not only be applied to structure hydrogels from the large class of reversibly formed gels with superior resolution but would also allow for the selective loading of the hydrogels with active substances or nanoparticles.

The amide-group containing amphiphile 4-N-octanoyl-aminobenzoic acid sodium salt is able to thermoreversibly form supramolecular hydrogels in aqueous solutions of alkanine sodium salts. The supramolecular assemblies can be transferred without destruction by a mold-casting/drying process into self-supporting macroscopic supramolecular nanofiber mats. These mats are thermally and mechanically stable, resistant to a large variety of organic solvents and therefore interesting for potential applications such as templating of inorganic materials and filtration. The nanotubular multiwalled morphology of the underlying supramolecular assemblies was revealed using field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray scattering (XRD) and Fourier-Transform infrared spectroscopy (FT-IR).