Cu ²⁺ ‐Induced Gelation of Guanosine: Supramolecular Transition From G ₂ ·(Cu ²⁺ ) ₂ to G ₄ ·Cu ⁺ Assemblies in Gel

Guanosine (G) self‐assembles into metal‐stabilized architectures such as G‐quartets (G 4 ·M n+ ) with metal ions, including Na⁺, K⁺, Rb + and Cu⁺, and G‐dimers G 2 ·(M n+ ) 2 with Ag⁺. Here, we show that Cu 2+ forms a stable G 2 ·(Cu 2+ ) 2 dimer‐based gel at elevated temperatures. This gel exhibits self‐healing and time‐dependent syneresis behavior. In situ reduction of Cu 2+ to Cu + by ascorbic acid converts the G 2 ·(Cu 2+ ) 2 dimeric gel to a G 4 ·Cu + G‐quadruplex gel, enabling a redox‐controlled gel‐to‐gel transformation. The G 2 ·(Cu 2+ ) 2 gel is mechanically stronger but dilution‐sensitive, whereas the G 4 ·Cu + gel is weaker yet more dilution‐tolerant. These results establish copper oxidation states as determinants of G‐based assembly and demonstrate a redox‐triggered route to adaptive, stimuli‐responsive soft materials.