Selective assembly on a surface of supramolecular aggregates with controlled size and shape

Abstract

The realization of molecule-based miniature devices with advanced functions requires the development of new and efficient approaches for combining molecular building blocks into desired functional structures, ideally with these structures supported on suitable substrates 1-4. Supramolecular aggregation occurs spontaneously and can lead to controlled structures if selective and directional non-covalent interactions are exploited. But such selective supramolecular assembly has yielded almost exclusively crystals or dissolved structures 5; the self-assembly of absorbed molecules into larger structures 6-8, in contrast, has not yet been directed by controlling selective intermolecular interactions. Here we report the formation of surface-supported supramolecular structures whose size and aggregation pattern are rationally controlled by tuning the non-covalent interactions between individual absorbed molecules. Using low-temperature scanning tunnelling microscopy, we show that substituted porphyrin molecules adsorbed on a gold surface form monomers, trimers, tetramers or extended wire-like structures. We find that each structure corresponds in a predictable fashion to the geometric and chemical nature of the porphyrin substituents that mediate the interactions between individual adsorbed molecules. Our findings suggest that careful placement of functional groups that are able to participate in directed non-covalent interactions will allow the rational design and construction of a wide range of supramolecular architectures absorbed to surfaces.

Phase Transition of Two-Dimensional Chiral Supramolecular Nanostructure Tuned by Electrochemical Potential

“…Previous studies address that molecules with N≡Cs groups easily form dimers and trimers via weak hydrogen bonds. 28,44,45 On the basis of these literature reports and the present experimental data, the adsorption models of network I and II were tentatively suggested in Figure 5a Structural Transitions and Dynamic Processes. The steady-state STM experiments in an electrochemical environment demonstrated that depending on the substrate charge density, three types of ordered chiral supramolecular adlayers can be observed on a Au(111) surface.…”

Adsorption and Electrochemical Activity: An In Situ Electrochemical Scanning Tunneling Microscopy Study of Electrode Reactions and Potential-Induced Adsorption of Porphyrins

“…[1][2][3] Many of these applications rely on the formation of thin films of ordered structures of porphyrins and related compounds. [4][5][6][7] Intermolecular interactions such as dipole-dipole, 8 hydrogen bonding, 8 and coordination 9 in porphyrin building blocks are being used to create selfassembled structures on surfaces with increasing sophistication. Itaya et al demonstrated that the ordering of porphyrin molecules on metal surfaces can be promoted by a passivating layer of iodine, which reduces the adsorbate-substrate interaction and facilitates surface diffusion.…”

Electrochemical and Photophysical Properties of Ruthenium(II) Bipyridyl Complexes with Pendant Alkanethiol Chains in Solution and Anchored to Metal Surfaces

“…For these methods no precise positioning of the components is attainable. In order to move from disordered solid samples to organized monolayers, it is necessary to assemble the molecules, via covalent [1,2,3,4] or non-covalent interactions [5][6][7][8][9][10][11][12] on a substrate and to study their properties at this interface. Amongst the responsive molecules, those addressable with light and able to give a strong emission signal are very appealing since any type of surface can be used and no wiring is required for their activation [13,14].…”