Flexible Phenanthracene Nanotubes for Explosive Detection.

Phenanthracene nanotubes with arylene-ethynylene-butadiynylene rims and phenanthracene walls are synthesized in a modular bottom-up approach. One of the rims carries hexadecyloxy side chains, mediating the affinity to highly oriented pyrolytic graphite. Molecular dynamics simulations show that the nanotubes are much more flexible than their structural formulas suggest: In , the phenanthracene units act as hinges that flip the two macrocycles relative to each other to one of two possible sites, as quantum mechanical models suggest and scanning tunneling microscopy investigations prove.

Modular Bicyclophane-Based Molecular Platforms.

The modular synthesis of a series of nanoscale phenylene bicyclophanes with an intraannular orthogonal pillar is described. The compounds are obtained by a Suzuki cross-coupling condensation and are characterized by mass spectrometry and NMR spectroscopy as well as in situ scanning tunneling microscopy at the solid/liquid interface of highly ordered pyrolytic graphite. In addition, their structures and conformations are supported by quantum chemical calculations, also after adsorption to the substrate.

Influence of Different Substitution Patterns on the 2D Crystalline Aggregation of Small Molecules on HOPG Surfaces.

A series of benzoic and terephthalic acid derivatives and their corresponding ethyl esters have been synthesized. These are decorated with dendritic units carrying alkoxy chains that differ in the number of alkoxy groups and/or their substitution pattern. These molecules were deposited from solution on highly oriented pyrolytic graphite, and the resulting supramolecular surface patterns have been studied by scanning tunneling microscopy at the solid/liquid interface.

Nanopatterns of molecular spoked wheels as giant homologues of benzene tricarboxylic acids.

Molecular spoked wheels with and symmetry are synthesized by Vollhardt trimerization of -symmetric dumbbell structures with central acetylene units and subsequent intramolecular ring closure. Scanning tunneling microscopy of the -symmetric species at the solid/liquid interface on graphite reveals triporous chiral honeycomb nanopatterns in which the alkoxy side chains dominate the packing over the carboxylic acid groups, which remain unpaired. In contrast, -symmetric isomers partially allow for pairing of the carboxylic acids, which therefore act as a probe for the reduced alkoxy chain nanopattern stabilization.

Highly Strained Nanoscale Bicyclophane Monolayers Entering the Third Dimension: A Combined Synthetic and Scanning Tunneling Microscopy Investigation.

Invited for this month's cover are the collaborating groups of Prof. Dr. Sigurd Höger and Dr.

Highly Strained Nanoscale Bicyclophane Monolayers Entering the Third Dimension: A Combined Synthetic and Scanning Tunneling Microscopy Investigation.

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.

Nanopatterns of arylene-alkynylene squares on graphite: self-sorting and intercalation.

Supramolecular nanopatterns of arylene-alkynylene squares with side chains of different lengths are investigated by scanning tunneling microscopy at the solid/liquid interface of highly oriented pyrolytic graphite and 1,2,4-trichlorobenzene. Self-sorting leads to the intermolecular interdigitation of alkoxy side chains of identical length. Voids inside and between the squares are occupied by intercalated solvent molecules, which numbers depend on the sizes and shapes of the nanopores.