Nanosized Molecular Propellers by Cyclodehydrogenation of Polyphenylene Dendrimers

Simpson, Christopher D.; Mattersteig, Gunter; Martin, Katrin; Gherghel, Lileta; Bauer, Roland E.; Räder, Hans Joachim; Müllen, Kläus

doi:10.1021/ja036732j

Cited by 153 publications

(105 citation statements)

References 19 publications

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“…1c. Briefly, it is based on a polymerization of pre-synthesized molecular precursors by a Ni 0 -mediated Yamamoto coupling 45 followed by a cyclodehydrogenation via a Scholl reaction using iron (III) chloride 46 to form GNRs. This synthetic approach is described in detail in the Methods section.…”

Section: Synthesis Of Gnrsmentioning

confidence: 99%

Large-scale solution synthesis of narrow graphene nanoribbons

et al. 2014

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According to theoretical studies, narrow graphene nanoribbons with atomically precise armchair edges and widths of o2 nm have a bandgap comparable to that in silicon (1.1 eV), which makes them potentially promising for logic applications. Different top-down fabrication approaches typically yield ribbons with width 410 nm and have limited control over their edge structure. Here we demonstrate a novel bottom-up approach that yields gram quantities of high-aspect-ratio graphene nanoribbons, which are only B1 nm wide and have atomically smooth armchair edges. These ribbons are shown to have a large electronic bandgap of B1.3 eV, which is significantly higher than any value reported so far in experimental studies of graphene nanoribbons prepared by top-down approaches. These synthetic ribbons could have lengths of 4100 nm and self-assemble in highly ordered few-micrometer-long 'nanobelts' that can be visualized by conventional microscopy techniques, and potentially used for the fabrication of electronic devices.

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Section: Synthesis Of Gnrsmentioning

confidence: 99%

Large-scale solution synthesis of narrow graphene nanoribbons

et al. 2014

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“…In diesen Fällen schlugen die Autoren die Entstehung dreidimensionaler propellerförmiger Strukturen vor. [150] Einige einfachere Vertreter funktionalisierter PAKs wurden auf ihr Potenzial getestet, als Vorstufenmoleküle für nanostrukturierte Kohlenstoffmaterialien zu dienen. Auf diese soll in Abschnitt 5 detailliert eingegangen werden.…”

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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“…These are grinding by mortar and pestle [4,5], ball-mill [1][2][3][4], and vortexing [6]. Analyte, matrix, and salt are added to a vessel and, in the case of the ball-mill or vortex methods, suitably sized balls are used to assist in the homogenization process.…”

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confidence: 99%

“…A significant advantage of solventfree MALDI analysis is that the method is capable of characterizing insoluble compounds such as polyfluorene [1] and is consequently routinely used for the characterization of large polycyclic aromatic hydrocarbons [2]. A recent study based on the ball-mill homogenization/loose powder transfer method revealed that solvent-free MALDI-MS simplifies the measurement and improves the result qualitatively and quantitatively [3].…”

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confidence: 99%

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Multisample preparation methods for the solvent-free MALDI-MS analysis of synthetic polymers

Trimpin

McEwen

2007

J. Am. Soc. Mass Spectrom.

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A limitation of any current approach using solvent-free MALDI mass spectrometry is that only one sample at a time can be prepared and transferred to the MALDI-plate. For this reason, multiple-sample preparation approaches for solvent-free MALDI MS analysis of synthetic polymers were developed that are simple and practical. One approach multiplexed sample preparation by simultaneously preparing multiple samples. With this approach, as many as 384 samples could be prepared by addition of analyte, matrix, salt, and 1-mm metal beads to each well of a 384-well disposable bacti plate, capping the plate with the lid and homogenizing all samples simultaneously using a common laboratory vortex device. Besides the time savings achieved by a single vortex step for multiple samples, an additional advantage of this method relative to previously reported solvent-free preparation methods is that the mixing volume per sample is reduced, which allows a reduction in the amount of analyte required. This method, however, still requires the transfer of each homogenized sample to the MALDI plate for subsequent analysis. Here we report a novel approach that combines multiple simultaneous solvent-free sample preparation with automatic sample transfer to the MALDI target plate. This approach reduces the possibility of cross-contamination, the amount of sample and matrix consumed for an analysis, and the time required for preparation of multiple samples. These methods were shown to provide high-quality mass spectra for various synthetic polymer standards with M n values to 10 kDa. The methods are efficient in that small sample amounts are required, the sample/salt/matrix ratio is not critical, and the time necessary to achieve sufficient homogenization of multiple samples is less than 5 min. . A recent study based on the ball-mill homogenization/loose powder transfer method revealed that solvent-free MALDI-MS simplifies the measurement and improves the result qualitatively and quantitatively [3]. In general, the solvent-free method gives more homogeneous analyte/matrix mixtures and higher shot-to-shot and sample-tosample reproducibility than does the solvent-based method [3,4]. Consequently, less laser power has to be applied [3,4], which yields milder MALDI conditions and thus less fragmentation [1,3]. This method, for the same reasons, also reduces background signals [3] and improves the resolution of the analyte signals [3,4].For synthetic polymer analyses, three general methods exist for homogenization. These are grinding by mortar and pestle [4,5], ball-mill [1][2][3][4], and vortexing [6]. Analyte, matrix, and salt are added to a vessel and, in the case of the ball-mill or vortex methods, suitably sized balls are used to assist in the homogenization process. For polymers having M n Յ 10 kDa ball-mill, vortex, and mortar-and-pestle approaches appear to work equally well [4,6]. Two general methods exist for the dry transfer of the homogenized powder from the vessel to the MALDI plate. In one method a pressed

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Nanosized Molecular Propellers by Cyclodehydrogenation of Polyphenylene Dendrimers

Cited by 153 publications

References 19 publications

Large-scale solution synthesis of narrow graphene nanoribbons

Large-scale solution synthesis of narrow graphene nanoribbons

Nanostrukturierte Kohlenstoffmaterialien aus molekularen Vorstufen

Multisample preparation methods for the solvent-free MALDI-MS analysis of synthetic polymers

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