Phosphate-Triggered Self-Assembly of N-[(Uracil-5-yl)methyl]urea: A Minimalistic Urea-Derived Hydrogelator

N‐[(Uracil‐5‐yl)methyl]urea is reported as a minimalistic low‐molecular‐weight hydrogelator (LMWHG). The unusual phosphate‐induced assembly of this compound has been thoroughly investigated by IR, UV/Vis, and NMR spectroscopy, electron microscopy, and rheological experiments. This rare example of an anion‐triggered urea‐based LMWHG is the first example of a pyrimidine‐ and urea‐containing molecule that can be forced into self‐assembly in aqueous solution without additional aromatic or lipophilic groups. The gelator/phosphate ratio within the hydrogel was successfully determined by 31P MAS NMR spectroscopy. The hydrogel exhibits a very fast and repeatable self‐healing property, and remarkable G′ values. The viscoelastic properties of the hydrogel can easily be tuned by variation of the phosphate ratio. Minimalistic hydrogel: N‐[(Uracil‐5‐yl)methyl]urea is reported as a minimalist low‐molecular‐weight hydrogelator (LMWHG), its assembly being induced by phosphate anions (see scheme). It is the first example of a pyrimidine‐ and urea‐containing molecule that can be forced into self‐assembly in aqueous solution without additional aromatic or lipophilic groups. The viscoelastic properties of the hydrogel can easily be tuned by variation of the phosphate ratio.