Discrete Self-Assembly and Functionality of Guest Molecules in an Organic Framework

In
this study, the fundamental issue of “how various functional
molecules can be homogeneously and densely arrayed in a solid material”
is addressed using discrete self-assembly of guest molecules with
an orthogonal architecture (1) comprising hydrogen bonds;
this method has become a new paradigm for constructing functional
materials. The serendipitous finding of cocrystallization in 1 was prompted by its unexpectedly tight but transmutable
inclusion of guest molecules. Notably, the self-assembly of 1 with imidazole molecules produced a water-durable, heat-resistant,
one-dimensional (1D) anhydrous proton-conducting channel with proton-transfer
sites in very close proximity (N–N distance, 2.481 Å).
The close sites lead to faster proton transfer when compared with
pure imidazole; this advantage via the close sites is attributable
to wobbling rather than rotational motion. These results suggest that
discrete self-assembly can enable the development of new design concepts
for functional materials.