Self-assembly of enantiopure domains: The case of indigo on Cu(111)

Abstract

The adsorption of indigo molecules on Cu(111) was investigated by low temperature (5 K) scanning tunneling microscopy from the isolated single molecule regime to one monolayer. Structural optimization and image calculations demonstrate that the molecules are in a physisorbed state. Because of the reduced symmetry at the surface, single molecules acquire a chiral character upon adsorption leading to a two-dimensional (2D) chirality. They adopt two adsorption configurations, related by a mirror symmetry of the substrate, each with a distinct molecular orientation. Consequently, the 2D chirality is expressed by the orientation of the molecule. For higher coverage, molecules self-assemble by hydrogen bonding in nearly homochiral molecular chains, whose orientation is determined by the orientation taken by the isolated molecules. When the coverage approaches one monolayer, these chains pack into domains. Finally, the completion of the monolayer induces the expulsion of the molecules of the wrong chirality that are still in these domains, leading to perfect resolution in enantiopure domains.

Synthesis and Characterization of a Series of Ruthenium Tris(β‐diketonato) Complexes by an UHV‐STM Investigation and Numerical Calculations

“…[13,59] This suggests that the two forms observed in the STM images result from two different adsorption geometries due to the peculiar 3D structure of complex 1.…”

“…[12] In recent years, the investigation of the properties of isolated, individual molecules has been greatly facilitated by scanning tunnelling microscopy (STM). Thus, this technique has been used to study the adsorption site and geometry of molecules on the surfaces, [9,13] to obtain high resolution images of the intramolecular structure, [14][15][16] to investigate the electronic properties of individual molecules, [17][18][19] to detect different spin states of transition-metal complexes [20] and to observe charge localization on isolated mixed-valence com- [ anedionate ion)}. In addition, X-ray structures for complexes 1, 2, 3, 4 and 6 were determined.…”

Surface-Induced Phase of Tyrian Purple (6,6′-Dibromoindigo): Thin Film Formation and Stability

“… 9 − 12 Likewise, scientific interest has recently increased for thin films of hydrogen-bonded pigments. The film formation and crystallization at surfaces was studied for indigo 13 , 14 and quinacridone, where, in addition, the electronic structure was investigated. 15 − 20 For these systems, stronger intermolecular interactions due to hydrogen bond formation and the presence of stronger bonds toward the substrate result in lower diffusion rates and smaller crystallites.…”

Two-Dimensional Self-Assembly Monitored by Hydrogen Bonds for Triphenylene-Based Molecules: New Role for Azobenzenes

“…carbonyl or carboxyl groups directly attached to the polyaromatic part of the molecule. 22,[28][29][30][31][32][33][34] The complexity of the possible output, including frequently appearing polymorphism of self-assemblies, usually renders difficult an accurate study of the balance between hydrogen bonds and molecule-substrate interactions for the determination of the molecular networks. Moreover, besides carboxyl group -the most frequently met functional group bearing the potential for hydrogen bonding formation, there exists interactions defined as weak hydrogen bonding which may involve N atoms in particular.…”