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 AgI12X4L6 3 ×
3 metal–organic grid-like structures, where the core AgI12X4 nanocluster is in dynamic motion,
with AgI 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 AgI ions behave in similar
ways to Ag0 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.