Temporally Programmed Hydrogelation of a Short Peptide Charge Transfer Complex

Creating artificial systems that emulate the dynamic behavior of living assemblies remains a central goal in supramolecular chemistry. Here, a charge transfer-driven pH clock-regulated hydrogelation process is presented, arising from the interaction between a pyrene-lysine cysteine tripeptide (PyKC) and a phenylalanine-substituted naphthalene diimide (NDIF). Spectroscopic and structural analyses confirmed the formation of a 1:1 donor-acceptor complex organized through π-π stacking and β-sheet arrangements. The resulting hydrogel forms rapidly under alkaline conditions and exhibits reversible transitions triggered by variations in temperature and pH. Coupling the system with a Tris buffer-glucono-δ-lactone pH clock produces transient hydrogelation with lifetimes precisely tunable by the activator-deactivator ratio. The hydrogel repeatedly assembles and disassembles in synchrony with pH oscillations, maintaining its structural integrity.