Supramolecular Assemblies on Surfaces: Nanopatterning, Functionality, and Reactivity

Understanding how molecules interact
to form large-scale hierarchical structures on surfaces holds promise
for building designer nanoscale constructs with defined chemical and
physical properties. Here, we describe early advances in this field
and highlight upcoming opportunities and challenges. Both direct intermolecular
interactions and those that are mediated by coordinated metal centers
or substrates are discussed. These interactions can be additive, but
they can also interfere with each other, leading to new assemblies
in which electrical potentials vary at distances much larger than
those of typical chemical interactions. Earlier spectroscopic and
surface measurements have provided partial information on such interfacial
effects. In the interim, scanning probe microscopies have assumed
defining roles in the field of molecular organization on surfaces,
delivering deeper understanding of interactions, structures, and local
potentials. Self-assembly is a key strategy to form extended structures
on surfaces, advancing nanolithography into the chemical dimension
and providing simultaneous control at multiple scales. In parallel,
the emergence of graphene and the resulting impetus to explore 2D
materials have broadened the field, as surface-confined reactions
of molecular building blocks provide access to such materials as 2D
polymers and graphene nanoribbons. In this Review, we describe recent
advances and point out promising directions that will lead to even
greater and more robust capabilities to exploit designer surfaces.