Layered Insulator/Molecule/Metal Heterostructures with Molecular Functionality through Porphyrin Intercalation

Intercalation
of molecules into layered materials is actively researched
in materials science, chemistry, and nanotechnology, holding promise
for the synthesis of van der Waals heterostructures and encapsulated
nanoreactors. However, the intercalation of organic molecules that
exhibit physical or chemical functionality remains a key challenge
to date. In this work, we present the synthesis of heterostructures
consisting of porphines sandwiched between a Cu(111) substrate and
an insulating hexagonal boron nitride (h-BN) monolayer.
We investigated the energetics of the intercalation, as well as the
influence of the capping h-BN layer on the behavior
of the intercalated molecules using scanning probe microscopy and
density functional theory calculations. While the self-assembly of
the molecules is altered upon intercalation, we show that the intrinsic
functionalities, such as switching between different porphine tautomers,
are preserved. Such insulator/molecule/metal structures provide opportunities
to protect organic materials from deleterious effects of atmospheric
environment, can be used to control chemical reactions through spatial
confinement, and give access to layered materials based on the ample
availability of synthesis protocols provided by organic chemistry.