Visible Raman spectroscopy is a useful technique that can provide insights into changes arising with self-assembly (Fig. ). Microscopy image mapping of the fibers was possible only using the most intense Raman signal of the aromatic ring of Phe at ~ 1003 cm -1 (yellow in the insets) that was uniformly distributed along the fibers. Analysis with visible light of the powder and of the xerogels revealed the rising of specific signals (blue asterisks in Fig. ) with self-assembly, except for compound 1 that displayed them already in the powder form (black asterisks in Fig. ).