Regular Two-Dimensional Arrays of Surface-Mounted Molecular Switches: Switching Monitored by UV–vis and NMR Spectroscopy

Using solid-state 15N
NMR spectroscopy, the cis/trans isomerization
in a two-dimensional
(2-D) array of surface-mounted azobenzene-based switches was detected
for the first time. In order to achieve this, a new class of rod-shaped
molecular switches, suitable for formation of 2-D regular arrays on
large facets of tris­(o-phenylenedioxy)­cyclotriphosphazene
(TPP) nanocrystals, was synthesized. A mechanochemical approach was
used to prepare corresponding host–guest surface inclusions
in a TPP matrix. Comparison of thermal steps in solution and supramolecular
surface inclusions revealed that switching of individual molecules
is not compromised by the close proximity of neighbors.