Inter- or intramolecular coupling processes between chromophores such as excimer formation or H- and J-aggregation are crucial to describing the photophysics of closely packed films of conjugated polymers. Such coupling is highly distance dependent and should be sensitive to both fluctuations in the spacing between chromophores as well as the actual position on the chromophore where the exciton localizes. Single-molecule spectroscopy reveals these intrinsic fluctuations in well-defined bichromophoric model systems of cofacial oligomers. Signatures of interchromophoric interactions in the excited state--spectral red shifting and broadening and a slowing of photoluminescence decay--correlate with each other but scatter strongly between single molecules, implying an extraordinary distribution in coupling strengths. Furthermore, these excimer-like spectral fingerprints vary with time, revealing intrinsic dynamics in the coupling strength within one single dimer molecule, which constitutes the starting point for describing a molecular solid. Such spectral sensitivity to sub-Ångström molecular dynamics could prove complementary to conventional FRET-based molecular rulers.

Tetrabromo aromatics can be synthesized by the Fischer-Zimmermann condensation of appropriate pyrylium salts with arylene dicarboxylic acid salts. Their cyclization by intramolecular Yamamoto coupling yields strained bicyclophanes with adjustable sizes and different intraannular bridges. All compounds adsorb at the solid/liquid interface on highly oriented pyrolytic graphite (HOPG) and are investigated by scanning tunneling microscopy (STM) with submolecular resolution. The observed two-dimensional (2D) supramolecular nanopatterns depend only on the sizes and alkoxy periphery of the cyclophanes and are independent of the specific structures of the intraannular bridges. Since the central arylene moieties of the smaller species are oriented perpendicular to the planes of the bicyclophanes, their substituents protrude from the surface by up to 1.6 nm after adsorption. Therefore, these molecules are attractive platforms for addressing the volume phase above the graphite surface.

The present work is the result of aj oint approach of two research groups. Prof. Hçger'sg roup works in the field of organic synthesis of complex shape-persistent molecules, while Dr.J ester'sg roup works in the field of surface science with af ocus on scanning probe microscopy.O ur collaborative work usually begins with a design phase that considers synthetic accessibility on the one hand, as well as the ability to form supramolecular nanopatterns on graphite with certain parameters on the other hand. The diameter and vertical height of one of our molecular structures are shown next to as pace-filling model. The periodic bright areas in the background of the graphics represent backbone regions of the monolayer observed by scanning tunneling microscopy,a nd as tylized honeycomb pattern of graphite is added.

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The Front Cover shows that the degrees of freedom of the central unit are sterically restricted in the alkoxy‐substituted arylene bicyclophane with a backbone diameter of 0.8 nm. Self‐assembled monolayers form at the interface of graphite and the compound in 1‐phenyloctane. Therein, the molecules arrange in stripes, with the aromatic and topographically extended units appearing bright in the STM image. According to their adsorption geometry, these molecules are attractive platforms for addressing the liquid phase above the solid surface. More information can be found in the Full Paper by S.‐S. Jester, S. Höger, and co‐workers.