Diffusion of single molecules in nanoporous mesostructured materials

Single-molecule methods play a growing role in materials science
because they can reveal structural and dynamic features which are
obscured by ensemble averaging in conventional spectroscopic
techniques. In this work, such methods were used to study the
dynamics of single dye molecules (guests) within different
surrounding porous matrices (hosts) using wide-field microscopy and
single-molecule tracking. A significant amount of tracking data was
collected and sophisticated methods to analyse the data according
to diffusion theory were developed. A method was established to
directly correlate the diffusion information that is provided by
single-molecule trajectories with the images of the porous host
systems obtained by transmission electron microscopy (TEM).
Furthermore, the results from single-molecule tracking experiments
were compared with diffusion measurements using pulsed-field
gradient NMR in the same samples. The data presented in this thesis
thus provide for the first time a detailed picture of the real
mesoporous structure and its effects on the dynamic behavior of dye
molecules at the nanometre to micron scale, e.g.~information about
pore connectivity and accessibility. The methodology established
here is expected to provide detailed insights into the dynamics of
other important host-guest systems, such as bioactive molecules in
porous materials for drug delivery or reactants in porous
catalysts.