A novel strategy for the design of smart supramolecular gels: controlling stimuli-response properties through competitive coordination of two different metal ions

By rationally introducing Ca2+ and Fe3+ into a supramolecular gel, a bimetal-gel CaFeG was prepared. CaFeG could reversibly turn-on'' its fluorescence upon sensing H2PO4- with specific selectivity under gel-gel states through the competitive coordination of Ca2+ and Fe3+ with gelators and H2PO4-. Thus, CaFeG could act as a H2PO4- test kit and could be utilised in rewritable security display materials.