With the approach presented herein, a large aromatic pi-system is synthesized, which shows extraordinarily high solubility and an effective suppression of aggregation. This was due to a distortion of the aromatic core by bulky tert-butyl groups and the solubilizing effects of alkyl chains in the corona of the aromatic core. Therefore not only the processing and cleaning of the materials with standard laboratory techniques became possible, but moreover the first structure-rich UV/vis and a resolved (1)H NMR spectra for an aromatic system two times larger than hexa-peri-hexabenzocoronene were recorded. The bulk properties in an extruded fiber as well as on the surface showed a columnar self-assembly including a phase in which a homeotropic alignment on a substrate was observed, which turns the material into an interesting candidate for future applications in electronic devices.

Films comprising Au nanoparticles and polyphenylene dendrimers (first and second generation) are deposited onto transducer substrates via layer‐by‐layer self‐assembly and characterized by atomic force microscopy and X‐ray photoelectron spectroscopy. Their sorption behavior is studied by measuring the uptake of solvents from the vapor phase with quartz crystal microbalances (QCMs). The resistance of the films is simultaneously monitored. Both sensor types, QCMs and chemiresistors, give qualitatively very similar response isotherms that are consistent with a combination of Henry‐ and Langmuir‐type sorption processes. The sorption‐induced increase in relative differential resistance scales linearly with the amount of analyte accumulated in the films. This result is in general agreement with an activated tunneling process for charge transport, if little swelling and only small changes in the permittivity of the film occur during analyte sorption (a first‐order approximation). The relative sensitivity of the films to different solvents decreases in the order toluene ≈ tetrachloroethylene > 1‐propanol ≫ water. Films containing the larger second‐generation dendrimers show higher sensitivity than films containing first‐generation dendrimers.

A novel homologous series of five monodisperse ribbon-type polyphenylenes, with rigid dibenzo[e,l]pyrene cores in the repeat units, are synthesized by a microwave-assisted Diels-Alder reaction. The size of the obtained polyphenylene ribbons ranges from 132 to 372 carbon atoms in the aromatic backbone which incorporates up to six dibenzo[e,l]pyrene units, thus showing quite different aspect ratios. Because of the flexibility of the backbone and the peripheral substitution with dodecyl chains, the polyphenylene ribbons are well soluble in organic solvents and can be fully characterized by standard analytical techniques. Their unique structure is especially designed to produce a series of giant ribbon-type polycyclic aromatic hydrocarbons (PAHs) in a single further reaction step by cyclodehydrogenation. Therefore, the incorporated dibenzo[e,l]pyrene cores are an important feature because they facilitate the dehydrogenation and improve the reaction yields. The smallest representative of the completely dehydrogenated planarized (2D) PAH ribbons, prepared from the polyphenylene ribbon with 132 aromatic carbon atoms, is still sufficiently soluble and shows a λ max value of 644 nm. Most importantly, these graphitic molecules self-organize into 2D columns when adsorbed on highly oriented pyrolytic graphite (HOPG), thus rendering them attractive candidates for future applications in organic electronic devices such as e.g. field effect transistors. A deeper insight into possible conformations of the sterically demanding side chains and their influence on the packing behavior of such giant PAHs into columnar arrangements is additionally obtained by molecular dynamics simulations. Using Marcus theory for a nonadiabatic temperature-activated charge transfer, we discuss the advantages of an extended, anisotropic in shape, π-system as compared to traditional one-dimensional molecular arrangements of typical discotics.

The selective oxidation of the perimeter of an extended polycyclic aromatic hydrocarbon (PAH), namely a six-fold tert-butylated tetrabenzo[bc,ef,hi,uv]ovalene, led to the formation of an alpha-diketone. The newly installed carbonyl centers allowed this building block to be converted into the largest known heteroatom-containing PAHs (up to 224 atoms in the aromatic core) by way of the quinoxaline ring condensation reaction. The tert-butyl substituents caused a distortion of the usually planar aromatic frameworks, which hampered the aggregation tendency of the extended aromatic pi-systems and led to extraordinarily high solubilities. All of the systems described here, even the giant phthalocyanine, could thus be purified using standard chromatographic techniques and characterized using typical spectroscopic methods. For the first time, fully resolved 1H NMR spectra of soluble, diamagnetic, 98- and 104-atom-containing aromatic systems are presented. The computed and experimental UV/vis spectra emphasize the dependence of the characteristic alpha-, p-, and beta-bands upon the size of the PAHs. It was also possible to obtain the largest known ligand to yet be complexed around a ruthenium center. A quadrupolar solvatochromic effect was observed when two donating PAH moieties were fused to an accepting quinoxaline center, in which case the photoluminescence spanned a range of about 80 nm. Electrochemical properties of the new nanographenes were investigated using cyclic voltammetry, and this showed quasi-reversible reductions.