Functional (Supra)Molecular Nanostructures - ruben-group

3. Introduction
Habilitation Dr. Mario Ruben
ULP Strasbourg
The function of a material depends both on the nature of its constituents and their mutual
interactions and arrangement. The controlled fabrication, manipulation and implementation of
nano-sized functional chemical entities into complex molecular architectures might provide a
wide range of applications with great value for science and technology. The properties of
nanostructured materials follow a bottom-up scale change from the nano- to the macrolevel
with increasing structural and functional integration. The supramolecular self-organization
approach enables a high degree of molecule-instructed structural organization within the
nanoregime. Reversible noncovalent bonds mediate the controlled assembly and hierarchical
growth of instructed, fully integrated and connected operational systems. Using such an
approach, an impressive variety of structural motifs employing various self-assembly
protocols has already been designed, e.g., helicates, catenates, grids, cages, dendrimers,
rosettes, chains, ladders, rotaxanes etc. [1]
The objective of the research studies concluded within this habilitation consists of the
investigation and deliberate use of supramolecular self-organization and self-assembly of
molecular systems (i) in solution with subsequent studies of the bulk properties as well as
(ii) at well-defined surfaces and substrates. Both approaches are directed towards the long-
term goal of controlled fabrication and manipulation of functional nanostructures and
devices. The bottom-up self-assembly of supramolecular nanostructures relies pivotally on
non-covalent interactions (metal coordination, hydrogen bonding, donor–acceptor π-
interactions, van-der-Waals and electrostatic), which can be designed and investigated in
molecular ensembles or, in some cases, directly at the single-molecule level. Furthermore,
beyond one-step self-assembly concepts, the access to hierarchically organized functional
nanostructures based on the modular construction of appropriately designed building blocks
along self-assembly protocols containing multilevel-instructions was explored.
One possible way to address (supra)molecular nanostructures at the single-molecule
level consists of organizing molecular systems at surfaces, where they could be approached
and investigated by e.g. scanning probe or break junction techniques. Beside solution-based
bulk self-assembly, three main concepts were used within this work to steer the construction
of molecular nanostructures directly on surfaces: (A) A two-step approach starting with
solution-based self-assembly of supramolecules followed by subsequent surface deposition.
(B) The one-step surface-assisted self-assembly of hydrogen-bonded organic nanostructures
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