ChemInform Abstract: Elements for a Rational Polymer Approach Towards Carbon Nanostructures

École Polytechnique Fédérale de Lausanne, Institute of Materials, EPFL - STI - IMX - LMOM, MXG 037, Station 12, 1015 Lausanne, Switzerland.
Angewandte Chemie International Edition (Impact Factor: 11.26). 07/2012; 51(27):6569-71. DOI: 10.1002/anie.201201423
Source: PubMed

ABSTRACT Growth spurt: A recent series of publications promises to pave the way for a polymer approach towards well-defined carbon nanostructures by combining the stepwise organic synthesis of carbon nanotube (CNT) end caps and their use as templates for CNT growth by Diels-Alder addition of nitroethylene as a masked acetylene derivative.

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    The Journal of Organic Chemistry 11/2012; 77(23). DOI:10.1021/jo302186h · 4.64 Impact Factor
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    ABSTRACT: Two novel arene-bridged cycloparaphenylene dimers (1 and 2) were prepared using a functionalized precursor, bromo-substituted macrocycle 7. The preferred conformations of these dimeric structures were evaluated computationally in the solid-state, as well as in the gas and solution phases. In the solid-state, the "trans" configuration of 1 is preferred by 34 kcal/mol due to the denser crystal packing structure that is achieved. In contrast, in the gas phase and in solution, the "cis" conformation is favored by 7 kcal/mol (dimer 1) and 10 kcal/mol (dimer 2), with a "cis" to "trans" activation barrier of 20 kcal/mol. The stabilization seen in the "cis" conformations is attributed to the increased van der Waals interactions between the two cycloparaphenylene rings. These calculations indicate that that the "cis" conformation is accessible in solution, which is promising for future efforts towards the synthesis of short carbon nanotubes (CNTs) via cycloparaphenylene monomers. In addition, the optoelectronic properties of these dimeric cycloparaphenylenes were characterized both experimentally and computationally for the first time.
    Journal of the American Chemical Society 11/2012; 134(48). DOI:10.1021/ja307373r · 11.44 Impact Factor
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    ABSTRACT: Conjugated macrocycles can be equipped with interesting functions by having polycyclic aromatic hydrocarbon (PAH) building blocks that are larger than benzene. The building block explored herein is phenanthrene, which is connected with varied linkers leading to new trimeric conjugated macrocycles (1-4). The coronal macrocycle 1, whose pi-backbone is a new segment of [6,6]-carbon nanotube, is synthesized from the flat macrocycle 2 by Lewis acid-catalyzed [4 + 2] benzannulation. This suggests a new strategy to synthesize p-extended nanorings from conjugated macrocycles that are more easily accessed. As found from a comparative study with focus on self-assembly and organic semiconductor behavior, flat or nearly flat conjugated macrocycles 2-4 function as p-type organic semiconductors in solution-processed thin film transistors. Their field effect mobility as measured from as-cast films is dependent on their ability of self-aggregation in solution.
    Chemical Science 01/2013; 4(12):4525-4531. DOI:10.1039/C3SC52077C · 8.60 Impact Factor
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