Heterogeneous Single-Molecule Diffusion in One-, Two-, and Three-Dimensional Microporous Coordination Polymers: Directional, Trapped, and Immobile Guests

The diffusion of individual Nile red molecules in three
different
crystalline microporous coordination polymers (MCPs) is visualized
with single-molecule fluorescence microscopy. By localizing molecules
with high spatial resolution, the trajectories of the diffusing dyes
are reconstructed with nanometer-scale precision. A detailed analysis
of these tracks reveals different dynamics and guest–host interactions
in each crystal as well as distinct motion types within the same system,
suggesting the presence of structural heterogeneities in local environments.