Double Metal Ions Competitively Control the Guest-Sensing Process: A Facile Approach to Stimuli-Responsive Supramolecular Gels

A facile approach to the design of stimuli‐responsive supramolecular gels (SRSGs) termed double‐metal‐ion competitive coordination control is reported. By this means, the fluorescence signals and guest‐selective responsiveness of the SRSGs are controlled by the competitive coordination of two different metal ions with the gelators and the target guest. To demonstrate this approach, a gelator G2 based on multiple self‐assembly driving forces was synthesized. G2 could form Ca2+‐coordinated metallogel CaG with strong aggregation‐induced emission (AIE). Doping of CaG with Cu2+ results in AIE quenching of CaG and formation of Ca2+‐ and Cu2+‐based metallogel CaCuG. CaCuG could fluorescently detect CN− with specific selectivity through the competitive coordination of CN− with the Cu2+ and the coordination of Ca2+ with G2 again. This approach may open up routes to novel stimuli‐responsive supramolecular materials. Competitive coordination control: The stimuli‐response properties of a supramolecular gel can be controlled by competitive coordination of two different metal ions. Doping of a Ca2+‐coordinated metallogel (CaG) with Cu2+ resulted in aggregation‐induced emission (AIE) quenching and formation of a Ca2+‐ and Cu2+‐based metallogel (CaCuG), which could fluorescently detect CN− with specific selectivity through competitive coordination of CN− with Cu2+ and recoordination of Ca2+ (see figure).