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In this paper we present the synthesis and characterization of the so far largest polycyclic aromatic hydrocarbon (PAH), containing 222 carbon atoms or 37 separate benzene units. First a suitable three‐dimensional oligophenylene precursor molecule is built up by a sequence of Diels–Alder and cyclotrimerization reactions and then planarized in the final step by oxidative cyclodehydrogenation to the corresponding hexagonal PAH. Structural proof is based on isotopically resolved MALDI‐TOF mass spectra and electronic characteristics are studied by UV/Vis spectroscopy.

Monodisperse polyphenylene dendrimers up to the fourth generation were synthesized using a divergent growth protocol. By varying the core, dendrimers with dumbbell-, tetrahedral- and propeller-like structures were synthesized. Because of the high-density packing of benzene rings within their branches, these dendrimers are stiff and thus shape persistent. To obtain these dendrimers with a globular shape, a 4-fold (A4B) dendrimer building unit was introduced. In this case, monodisperse dendrimers are obtained only up to the second generation due to the significantly increased density of benzene rings within the structure. For structure elucidation methods, like MALDI−TOF mass spectrometry, NMR spectroscopy, GPC, VPO, TGA, and DSC were used. Dendrimers of the third and fourth generations were visualized by transmission electron microscopy.

Individual polyphenylene dendrimer 1 and their self-assembled nanostructures, prepared by spincoating and solvent casting on various substrates such as mica, silanized mica, and highly oriented pyrolytic graphite (HOPG), have been investigated by noncontact atomic force microscopy. Besides globular clusters and monolayers, polyphenylene dendrimer 1 self-organizes into micrometer long nanofibers on a HOPG surface. Fibrillar nanostructures have also been visualized on a silanized mica surface, while on a mica surface the dendrimers only aggregate into globular clusters. Two possibilities for the development of dendrimer nanofibers are proposed.

Well-separated, individual polyphenylene dendrimer molecules have been prepared by spin coating on a mica surface, and subsequently imaged by noncontact atomic force microscopy (NCAFM). The observed height is in good agreement with the size of a single dendrimer molecule, as calculated by molecular dynamics simulation. By using pulsed force mode (PFM) AFM, stiffness and adhesion properties of individual polyphenylene dendrimers have been studied. They could be related to the molecular structure and the chemical nature of the outer surface of the dendrimers and the thin film of water adsorbed on mica when imaged under ambient conditions. Finally, by changing the concentration of the spin-coating solution, two different kinds of aggregates have been characterized.

Polyphenylen-Dendrimere sind monodisperse Makromoleküle, die auf Grund ihres starren Grundgerüsts stabile Hohlräume im Inneren bilden. Diese Eigenschaft unterscheidet sie von Dendrimeren, die aus flexiblen, aliphatischen Gruppen bestehen, und empfiehlt sie als attraktive Werkstoffe für die sensorische Überwachung flüchtiger Verbindungen mit Hilfe von massenempfindlichen Resonatoren, z. B. auf Basis von Quarz-Mikrowaagen (quartz microbalance, QMB). [1] Diese Form der Sensorik gewinnt in vielen Berei-durch Ionenaustausch und Affinitätschromatographie gereinigt. Das Assay-System zur Beurteilung der Hemmeigenschaften der Verbindungen basierte auf der Übertragung von radioaktiv markierter [ 3 H]Galactose vom Donor UDP-Galactose (50 mm) auf das Acceptormolekül LacNAc(CH 2 ) 8 -CO 2 CH 3 (0.36 mm) durch pa(1-3)GalT (10 mm) im Puffersystem aus 100 mm Natriumcacodylat (pH 6.5), 15 mm MnCl 2 und 50 mg mL À1 BSA (Rinderserumalbumin) bei 37 8C während 30 min. Das radioaktiv markierte Produkt [ 3 H]Gala(1-3)LacNAc(CH 2 ) 8 COOCH 3 wurde vom nichtradioaktiven Material durch Adsorption an eine SepPac-C 18 -Säule getrennt, wie in Lit.[20] beschrieben ist. Das Verhältnis von inkorporierter zu totaler Radioaktivität ist proportional zur Aktivität von pa(1-3)GalT. Es wurden Vorsichtsmaûnahmen ergriffen, um sicherzustellen, dass das Enzym limitierend ist und die Konzentrationen aller anderen Cofaktoren nahe am Sättigungswert sind. Genau genommen ist die berichtete Hemmung ein IC 50 -Wert, weil nicht mit unterschiedlichen Cofaktor-Konzentrationen geprüft wurde.

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