Crisscrossing coordination networks: ligand doping to control the chemomechanical properties of stimuli-responsive metallogels

Metallogels respond to external stimuli by changing their mechanical properties. To gain a fine control over this phase-shifting event, we have designed and introduced intentional structural mismatches into the otherwise tightly knit metal–organic networks. Built using biphenolate-derived multidirectional/multidentate ligands, these soft materials display markedly different rheological properties depending on the level of “ligand doping”, as well as the type of metal ion serving as a key structural support. A zinc metallogel optimized through this process responds to acids, both in the gas stream and liquid phase, by a rapid gel–sol transition and visually discernible colour change.