A Dynamic Silver(I) Nanocluster Holds Together a 3 × 3 Self-Assembled Grid.

Metal ions with well-defined coordination geometries can serve as fixed joints within self-assembled architectures, defining the relative orientations of ligands within higher-order superstructures. The exchange of ligands and metal ions between different positions is slow, involving disruption or distortion. Here we report a series of AgXL 3 × 3 metal-organic grid-like structures, where the core AgX nanocluster is in dynamic motion, with Ag ions moving between different binding sites, with concomitant conformational changes of the organic ligands, which continue to occupy well-defined positions nevertheless. The identity of the incorporated halide anion governs the activation barrier for silver ion exchange, thus enabling rate control in response to two distinct stimuli: by changing the temperature, and by exchanging one halide for another. The dynamic nanocluster within these grids thus provides a new mode of using metal ions in coordination-driven self-assembly, establishing that the mobile Ag ions behave in similar ways to Ag atoms in surface-bound clusters and in silver nanoparticles. The kinetic parameters determined in this work, and the techniques developed to measure them, could serve the scientific community to provide additional insight into dynamic metal nanoclusters.