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 Ca(2+) -coordinated metallogel CaG with strong aggregation-induced emission (AIE). Doping of CaG with Cu(2+) results in AIE quenching of CaG and formation of Ca(2+) - and Cu(2+) -based metallogel CaCuG. CaCuG could fluorescently detect CN(-) with specific selectivity through the competitive coordination of CN(-) with the Cu(2+) and the coordination of Ca(2+) with G2 again. This approach may open up routes to novel stimuli-responsive supramolecular materials.