Polyphenylene Dendrimers: From Three‐Dimensional to Two‐Dimensional Structures

Morgenroth, F.; Reuther, Erik; Müllen, Kläus

doi:10.1002/anie.199706311

Cited by 204 publications

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“…[2] Since 2,2'-bipyridine has no known reactivity under Diels-Alder conditions, it offers the opportunity to either grow the dendrimer divergently or to synthesize the polyphenylene dendrons first and then build the dendrimer by metal complexation in the final step ("convergent" approach).…”

Section: Dedicated To Professor Klaus Hafner On the Occasion Of His 8mentioning

confidence: 99%

“…Polyphenylene dendrimers with poly(pentaphenylbenzene) [1,2] branches (PPDs) are special within dendrimer chemistry because of their stiff, mostly radial arms that do not allow backfolding, thus rendering the molecules shapepersistent. [3] As a result, their overall shapes are defined by the geometry of the particular core unit, and different cores (Figure 1 a-c) have been proven to generate structural diversity.…”

Section: Dedicated To Professor Klaus Hafner On the Occasion Of His 8mentioning

confidence: 99%

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Tris(2,2′‐bipyridyl)ruthenium(II) with Branched Polyphenylene Shells: A Family of Charged Shape‐Persistent Nanoparticles

et al. 2008

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Cores for thought: Dendrimers based on an octahedral symmetry and with a central positively charged transition‐metal complex have been prepared up to the third generation (see schematic representation). The shape‐persistent dendrimers with a high density of aromatic rings are accessible by either a partly convergent synthesis or a divergent strategy in which the metal complex proved to be stable to high‐temperature Diels–Alder reactions.

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Section: Dedicated To Professor Klaus Hafner On the Occasion Of His 8mentioning

confidence: 99%

Section: Dedicated To Professor Klaus Hafner On the Occasion Of His 8mentioning

confidence: 99%

Tris(2,2′‐bipyridyl)ruthenium(II) with Branched Polyphenylene Shells: A Family of Charged Shape‐Persistent Nanoparticles

et al. 2008

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“…[140,141] Dieser Ansatz ermöglichte die Synthese riesiger Dendrimere, deren Größe mit Rasterkraftmikroskopie auf bis zu 5 nm ermittelt wurde. Diese Verbindungen stellen an und für sich schon monodisperse kohlenstoffreiche Nanostrukturen dar.…”

Section: Schema 2 Synthese Eines [N]-paraphenylen-makrocyclus Durchunclassified

Nanostrukturierte Kohlenstoffmaterialien aus molekularen Vorstufen

et al. 2010

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Nanostrukturierte Kohlenstoffmaterialien, also Kohlenstoffe, die eine charakteristische Größe im Nanometerbereich sowie eine eventuell funktionalisierte Oberfläche aufweisen, spielen eine zentrale Rolle in vielen wissenschaftlichen Disziplinen. Erste Anwendungen finden derartige Materialien dabei unter anderem in Bereichen wie der Erforschung alternativer Energiequellen, leistungsfähiger Energiespeichermaterialien, nachhaltiger chemischer Technologien oder auch im Gebiet der organisch‐elektronischen Materialien. Des Weiteren könnten diese Materialien mögliche Ansätze und Lösungen bieten, um dem voranschreitenden Verbrauch fossiler Brennstoffe und somit dem Klimawandel entgegenzusteuern. Ferner könnten nanostrukturierte Kohlenstoffmaterialien auch auf dem Gebiet der Mikroelektronik einen Durchbruch herbeiführen. Allerdings ist die Entwicklung neuer Herstellungsverfahren für kohlenstoffreiche Materialien unabdingbar, die unter anderem Kontrolle über die Oberflächenchemie, die mesoskopische Struktur und die Mikrostruktur ermöglichen. Ein vielversprechender Ansatz ist dabei die Synthese dieser Materialien aus wohldefinierten molekularen Vorstufen.

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“…In order to get access to substances with a defined substitution pattern it is therefore mandatory to introduce the desired functional groups into smaller building blocks and use these precursors to establish the synthesis of the p-quaterphenylene scaffold. In the past this was achieved by cyclotrimerisations of acetylenes [93][94][95][96][97], Diels-Alder reactions of cyclopentadienones and subsequent aromatisation [98][99][100][101][102][103][104], Wittig reactions of cinnamaldehydes followed by Diels-Alder reactions with acetylenic dicarboxylates and subsequent aromatisation [105], addition of Grignard reagents to arines [106][107][108][109], Grignard reactions with p-quinones and subsequent dehydratisation [110,111], or Ullmann-type coupling reactions [112]. Modern transition metal catalysed homo-and cross-coupling reactions have become more and more popular over the last 30 years [113][114][115][116].…”

Section: Fig 12mentioning

confidence: 99%

Organic Molecular Nanotechnology

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Zur Homepage der Dissertation AbstractFormation of needle-like crystals from inorganic as well as from organic semiconductors such as para-phenylenes, α-thiophenes and phenyl-thiophene co-oligomers on dielectric surfaces has attracted increasing interest within the last years. The para-hexaphenylene has proven to be a versatile building block for generating long, parallely aligned organic nanofibers by a self-assembly process on a muscovite mica substrate via sublimation in high vacuum. These nanofibers possess outstanding optical properties like strong, polarised blue fluorescence in high quantum yields after unpolarised excitation with UV light, waveguiding and lasing features. Furthermore, they are chemically and thermically stable and can be easily detached from the growth substrate to serve as key elements in next generation optoelectronic and nanophotonic devices. Owing to their typical height and width on a nanometer scale and length up to one millimeter, the fibers bridge the gap between microscopic and macroscopic dimensions. The morphology of the nanofibers (length, height, width, aspect ratio, bending into rings) is susceptable to process parameters and pretreatment of the substrate. But chemically functionalisation of the molecular building block as key step of this thesis widens the scope of possibilities: Nanoaggregates with tailored morphology and optical properties are generated from designed functionalised molecular building blocks. Functional groups have been implemented at the 1,4´´´-para-positions of p-quaterphenylenes using a non-trivial Suzuki cross-coupling strategy. Symmetrically as well as non-symmetrically functionalised oligomers have been achieved in excellent yields and high purity. Additionally, the synthesis of phenyl-thiophene cooligomers and their acceptability for the nanofiber growth on muscovite mica via organic molecule deposition in high vacuum are presented. The fluorescence peak emission frequency of the nanostructures from the substituted p-quaterphenylenes shifts within the blue depending on the functionalisation. While dimensions are still influenced by the growth parameters, the overall shape (i.e. cross-section) of the aggregates alters significantly with the functional group. Even new properties like nonlinear optical activity are accessible. Due to intrinsic nonzero hyperpolarisability of push-pull functionalised oligomers, the respective nanofibers act as frequency doublers and emit strong second harmonic light after excitation with near infrared femtosecond laser pulses. Note that this design approach is possible while conserving the concept of highly crystalline nanofibers. Thus, a new route of bottom-up nanotechnology is presented starting from organic molecular synthesis towards generating of tailormade organic nanofibers opening new prospects for future nanotechnology. 3 ZusammenfassungDie Bildung von nadelförmigen Kristallen aus anorganischen und organischen Halbleitermolekülen wie zum Beispiel para-Phenylenen, α-Thiophenen und Phenylthiophen Co-oligomeren fa...

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Polyphenylene Dendrimers: From Three‐Dimensional to Two‐Dimensional Structures

Cited by 204 publications

References 29 publications

Tris(2,2′‐bipyridyl)ruthenium(II) with Branched Polyphenylene Shells: A Family of Charged Shape‐Persistent Nanoparticles

Tris(2,2′‐bipyridyl)ruthenium(II) with Branched Polyphenylene Shells: A Family of Charged Shape‐Persistent Nanoparticles

Nanostrukturierte Kohlenstoffmaterialien aus molekularen Vorstufen

Organic Molecular Nanotechnology

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