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Molecular spoked wheels with intraannular functionalizable pillars are synthesized in a modular approach. The functionalities at their ends are variable, and a propargyl alcohol, a [6,6]-phenyl-C61-butyrate, and a perylene monoimide are investigated. All compounds form two-dimensional crystals on highly oriented pyrolytic graphite at the solid-liquid interface. As determined by submolecularly resolved scanning tunneling microscopy, the pillars adopt equilibrium distances of 6.0 nm. The fullerene has a residual mobility, limited by the length of the flexible connector unit. The experimental results are supported and rationalized by molecular dynamics simulations. These also show that, in contrast, the more rigidly attached perylene monoimide units remain oriented along the surface normal and maintain a smallest distance of 2 nm above the graphite substrate. The robust packing concept also holds for cocrystals with molecular hexagons that expand the pillar-pillar distances by 15 % and block unspecific intercalation.

Molecular spoked wheels with an all-phenylene backbone and different alkoxy side chain substitution patterns were synthesized using a cobalt-catalyzed [2 + 2 + 2] cycloaddition and subsequent template-directed cyclization via Yamamoto coupling. The two-dimensional organization of the molecules at the solid/liquid interface was investigated by means of scanning tunneling microscopy, allowing imaging of the molecular structure with submolecular resolution. With the right proportion of the flexible alkyl corona to the rigid core, mesomorphic behavior of one compound could be observed over a wide temperature range.

Strong dipole–dipole coupling within and between π‐conjugated segments shifts electronic transitions, and modifies vibronic coupling and excited‐state lifetimes. Since J‐type coupling between monomers along the conjugated‐polymer (CP) chain and H‐type coupling of chromophores between chains of a CP compete, a superposition of the spectral modifications arising from each type of coupling emerges, making the two couplings hard to discern in the ensemble. We introduce a single‐molecule H‐type aggregate of fixed spacing and variable length of up to 10 nm. HJ‐type aggregate formation is visualized intuitively in the scatter of single‐molecule spectra., Coupling therapy: In organic electronics, J‐type coupling between monomers along the chain and H‐type coupling of chromophores between chains compete, which makes the two types of coupling hard to discern in the ensemble. A single‐molecule H‐type aggregate of fixed spacing and variable length of up to 10 nm is introduced, and HJ‐type aggregate formation is visualized intuitively in the scatter of single‐molecule spectra.

Macrocycles with quaterthiophene subunits were obtained by cyclooligomerization by direct oxidative coupling of unsubstituted dithiophene moieties. The rings were closed with high selectivity by an α,β′-connection of the thiophenes as proven by NMR spectroscopy. The reaction of the precursor with terthiophene moieties yielded the symmetric α,α′-linked macrocycle in low yield together with various differently connected isomers. Blocking of the β-position of the half-rings yielded selectively the α,α′-linked macrocycle. Selected cyclothiophenes were investigated by scanning tunneling microscopy, which displayed the formation of highly ordered 2D crystalline monolayers.

Alkoxy-substituted phenylene–ethynylene–butadiynylenes (PEBs) are connected via 1H-benzimidazole units to form H-shaped molecular scaffolds that self-assemble on graphite at the solid/liquid interface. Spacer lengths and end groups determine supramolecular tiling patterns, as shown via scanning tunneling microscopy (STM).

The modular synthesis of a defined, rigid molecular spoked wheel structure with the sum formula C1878H2682 and a diameter of about 12 nm is described. The attached 96 dodecyl side chains provide the solubility of the 25 260 Da compound in common organic solvents. At the octanoic acid/highly oriented pyrolytic graphite interface, the molecules self-assemble to form an ordered 2D lattice, which is investigated by scanning tunneling microscopy, displaying their structure with submolecular resolution.

We present the efficient synthesis of a new molecular spoked-wheel structure (MSW-3). Two derivatives with diameters of approximately 4 nm have been prepared. By highlighting the importance of pseudo-high-dilution conditions during cyclization, we were able to access the compounds on a several hundred milligram scale. In addition to the standard characterization (NMR spectroscopy, MS), we describe a detailed investigation of the optical properties of the fluorescent MSWs by comparison with appropriate model chromophores. Furthermore, a comprehensive study of the structure in solution by means of light- and X-ray scattering experiments has been conducted. Scanning tunneling microscopy (STM) revealed the two-dimensional organization of the molecules on highly oriented pyrolytic graphite and emphasized the spoked-wheel structure. The diameter of these molecules measured by small-angle X-ray scattering is in very good agreement with that obtained from STM and matches the results of molecular modeling. This confirms the rigidifying effect of the spokes, which results in highly shape-persistent nanometer-sized oblate organic compounds.

We report the stepwise assembly of supramolecular daisy chain rotaxanes (DCR) made of double‐stranded DNA: Small dsDNA macrocycles bearing an axle assemble into a pseudo‐DCR precursor that was connected to rigid DNA stoppers to form DCR with the macrocycles hybridized to the axles. In presence of release oligodeoxynucleotides (rODNs), the macrocycles are released from their respective hybridization sites on the axles, leading to stable mechanically interlocked DCRs. Besides the expected threaded DCRs, certain amounts of externally hybridized structures were observed, which dissociate into dumbbell structures in presence of rODNs. We show that the genuine DCRs have significantly higher degrees of freedom in their movement along the thread axle than the hybridized DCR precursors. Interlocking of DNA in DCRs might serve as a versatile principle for constructing functional DNA nanostructures where the movement of the subunits is restricted within precisely confined tolerance ranges.

Molecular polygons with three to six sides and binary mixtures thereof form long-range ordered patterns at the TCB/HOPG interface. This includes also the 2D crystallization of pentagons. The results provide an insight into how the symmetry of molecules is translated into periodic structures.

Seeing stars: The two-dimensional patterns of the polycyclic heteroaromatic star molecules 1 on graphite vary with the side chain length. For n=12, frustrated self-assembly leads to hierarchically organized superstructures: up to 10 molecules form triangular aggregates which pack densely into hexagonal patterns with very large (15.5 nm) lattice constants.

Rigid rod oligo(phenylene-ethynylene-butadiynylene)s (oPEBs), “half-rings” of two rigid rods connected via a molecular clamp unit, and shape-persistent macrocycles (cyclic “half-ring dimers”) are synthesized and their self-assembled monolayers (SAMs) are investigated by scanning tunneling microscopy (STM) at the interface of 1,2,4-trichlorobenzene (TCB)/highly oriented pyrolytic graphite (HOPG). The results are important for the design of molecular building blocks for two-dimensional nanoscale architectures on solid surfaces.

The aggregation of shape-persistent macrocycles with an empty cavity, an undecyldiether strand and a tetraethylene glycol strand leads in all cases to a macroscopic gelation of the solvent. However, the gelation temperatures are fine-tuned by the intraannular substituents.

A route towards phenylene-bithiophene macrocycles via oxidative thiophene coupling under pseudo-high dilution conditions is reported. This method is applied to the synthesis of a shape-persistent thiophene macrocycle with extraannularly attached perylenebisimide moieties that forms supramolecular aggregates at the solid/liquid interface.