Sequential nested assembly at the liquid/solid interface.

Studying the stepwise assembly of a four component hybrid structure on Au(111)/mica, the pores of a hydrogen bonded bimolecular network of 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) and 1,3,5-triazine-2,4,6-triamine (melamine) were partitioned by three and four-armed molecules based on oligo([biphenyl]-4-ylethynyl)benzene, followed by the templated adsorption of either C60 fullerene or adamantane thiol molecules. The characterisation by ambient scanning tunneling microscopy (STM) reveals that the pore modifiers exhibit dynamics which pronouncedly depend on the molecular structure. The three-armed molecule 1,3,5-tris([1,1'-biphenyl]-4-ylethynyl)benzene (3BPEB) switches between two symmetry equivalent configurations on a time scale fast compared to the temporal resolution of the STM. Derivatisation of 3BPEB by hydroxyl groups substantially reduces the switching rate. For the four-armed molecule configurational changes are observed only occasionally. The observation of isolated fullerenes and small clusters of adamantane thiol molecules, which are arranged in a characteristic fashion, reveals the templating effect of the trimolecular supramolecular network. However, the fraction of compartments filled by guest molecules is significantly below one for both the thermodynamically controlled adsorption of C60 and the kinetically controlled adsorption of the thiol with the latter causing partial removal of the pore modifier. The experiments, on the one hand, demonstrate the feasibility of templating by nested assembly but, on the other hand, also pinpoint the requirement for the energy landscape to be tolerant to variations in the assembly process.

Bestowing structure upon the pores of a supramolecular network.

Trigonal molecules compartmentalise the pores of a honeycomb network of 3,4:9,10-tetracarboxylic diimide (PTCDI) and 1,3,5-triazine-2,4,6-triamine (melamine). Extending the 1,3,5-tri(phenylene-ethynylene)benzene core by a phenyl group allows for a well-defined accommodation of the molecule into two symmetry equivalent positions in the pore. The corresponding styryl or phenylene-ethynylene derivatives exceed the pore size and, thus, impede pore modification.

Nanopatterning by molecular self-assembly on surfaces.

The ability to pattern surfaces down to the nanoscale is of increasing importance in nanoscience research. The use of supramolecular chemistry to drive the formation of self-assembled networks allows for a bottom-up approach to achieve nanopatterned surfaces. This short review highlights some of the recent breakthroughs in achieving long-range order in such molecular based systems, complemented with examples from our own work. The tuning of molecular architectures can exert control on the emergent properties and function of molecules at interfaces. In particular the formation of porous honeycomb networks allows the rational design of highly ordered patterned surface domains and the investigation of molecular dynamics, chirality and templating effects on surfaces.