1,7-Dioxa[7](2,7)pyrenophane: The Pyrene Moiety Is More Bent than That of C70

Bodwell, Graham J.; Bridson, John N.; Houghton, Tom J.; Kennedy, Jason W. J.; Mannion, Michael R.

doi:10.1002/(sici)1521-3765(19990604)5:6<1823::aid-chem1823>3.0.co;2-i

Cited by 84 publications

(73 citation statements)

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“…47,71,72 The distortion found in the benzene rings of [5]CPP is trumped, however, by those in the single phenyl ring of several paracyclophanes 73−75 and the pyrene moieties of [9](2,7)pyrenophane and 1,7-dioxa[7]-(2,7)pyreneophanes. 76,77 In addition, several other cyclophanes have been predicted computationally to have highly distorted aromatic rings, though the crystal structures of these compounds have not been obtained. 78,79 The outstanding solubility of [5]CPP compared with other cycloparaphenylenes permitted extensive solution-state characterization, providing initial insight into the newest member of the [n]CPP family.…”

Section: Accounts Of Chemical Researchmentioning

confidence: 99%

Syntheses of the Smallest Carbon Nanohoops and the Emergence of Unique Physical Phenomena

2015

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The design and construction of non-natural products have fascinated and perplexed organic chemists for years. Their assembly, akin to what has been accomplished for the total synthesis of natural products, has stretched the limits of what can be prepared in the laboratory. Unlike many natural products, however, carbon-rich structures often lack heteroatoms, further complicating their construction. Consider some of the classical molecules in this genre: cubane and dodecahedrane. While highly symmetric, their assembly is far from trivial. These fascinating hydrocarbon targets have fueled the development of carbon-carbon bond-forming reactions, as new methods are needed to access these types of compounds. Among these carbon-rich structures, polycyclic aromatics such as helicenes, fullerenes, and some fullerenes share common ground due to the distortion of one or more aromatic rings out of planarity. Recently added to this group are the [n]cycloparaphenylenes ([n]CPPs), "carbon nanohoops". Here, a linear string of benzene rings connected at the para positions is wrapped back upon itself to form a cyclic structure. Clearly a simple linear p-oligophenylene cannot be cyclized in this manner without extremely harsh reaction conditions. In order to access these structures using solution-phase organic chemistry, clever synthetic strategies that can compensate for this severe distortion are required. Although cycloparaphenylenes can be considered the smallest possible fragment of an armchair carbon nanotube (CNT), they were envisioned as synthetic targets long before CNTs were discovered in 1991. CPP synthesis was first attempted in 1934, almost 70 years before Iijima's first report on CNTs. The long-forgotten targets reemerged in 1993 with a report from Vögtle, though he ultimately was unsuccessful in achieving their synthesis. More than a decade later, in 2008, CPPs succumbed to total synthesis by Jasti and Bertozzi, allowing access to three different-sized carbon nanohoops in milligram quantities. Since then, the Jasti group has embraced the smallest CPPs as inspiring synthetic targets, challenging us to develop new methodology to construct increasingly strained macrocycles. Having recently synthesized [5]-, [6]- and [7]CPP, the three smallest nanohoops synthesized to date, we have been able to realize a variety of new physical phenomena unique to these structures. Perhaps most significantly, unlike linear p-phenylenes and inorganic quantum dots, the HOMO-LUMO gaps of the CPPs narrow with decreasing CPP size. The smallest CPPs discussed in this Account illustrate this feature exceptionally well, as their HOMO-LUMO gaps become narrower than those of even the longest p-polyphenylenes. The smaller CPPs are fascinating from a structural standpoint as well because of the high amount of distortion in each benzene ring. From the synthesis of [7]CPP (84 kcal/mol of strain energy) to that of [5]CPP (119 kcal/mol of strain energy), our laboratory has been able to test the boundaries of synthetic and physical organic chemistry. In ...

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Section: Accounts Of Chemical Researchmentioning

confidence: 99%

Syntheses of the Smallest Carbon Nanohoops and the Emergence of Unique Physical Phenomena

2015

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“…[32][33][34] Just as in the case of a fullerene, a perfect SWNT is without functional groups; therefore these quasi-1D cylindrical aromatic macromolecules are chemically inert. However, curvature-induced pyramidalization and misalignment of the π-orbitals 6,30,32,[35][36][37][38][39][40][41] of the carbon atoms induces a local strain (Figure 3), and carbon nanotubes are expected to be more reactive than a flat graphene sheet. From the standpoint of the chemistry, it is conceptually useful to divide the carbon nanotubes into two regions: the end caps and the side wall.…”

Section: Electronic Structure and Chemical Reactivitymentioning

confidence: 99%

Chemistry of Single-Walled Carbon Nanotubes

et al. 2002

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In this Account we highlight the experimental evidence in favor of our view that carbon nanotubes should be considered as a new macromolecular form of carbon with unique properties and with great potential for practical applications. We show that carbon nanotubes may take on properties that are normally associated with molecular species, such as solubility in organic solvents, solutionbased chemical transformations, chromatography, and spectroscopy. It is already clear that the nascent field of nanotube chemistry will rival that of the fullerenes.

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“…Pyrenophane 43, which was obtained from cyclophanediene 42, is the smallest member of its class to be isolated to date (Scheme 11). [36] Its pyrene system has an end-to-end bend of 109.2°in the crystal, which is greater than that of the pyrene unit on the equator of D5h C70. Extending this methodology, we have more recently reported the synthesis of a small series of [n](2,11)teropyrenophanes.…”

Section: Valence Isomerizationmentioning

confidence: 99%

Extraordinary Transformations to Achieve the Synthesis of Remarkable Aromatic Compounds

Bodwell

2014

The Chemical Record

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Note from the Editor: When we walk around a sculpture, it can speak to us in many ways, sometimes quite differently from various view points. Central to Tetsuo Nozoe and the Nozoe Autograph Book project are novel aromatic compounds. Just look at nearly any page and such compounds jump out at us. We can categorize them in many ways. Their structures. Their physical properties. Their pharmacological and toxicological properties. Their commercial utilities. Their symmetry. Their size. In this essay, Graham Bodwell brings to us his analysis of the various ways in which some of the most remarkable of these compounds have been ingeniously synthesized. We are privileged to have Bodwell's vision and his sense of organization and beauty. Tetsuo Nozoe would have beamed! —Jeffrey I. Seeman Guest Editor University of Richmond Richmond, Virginia 23173, USA E‐mail: jseeman@richmond.edu

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1,7-Dioxa[7](2,7)pyrenophane: The Pyrene Moiety Is More Bent than That of C70

Cited by 84 publications

References 3 publications

Syntheses of the Smallest Carbon Nanohoops and the Emergence of Unique Physical Phenomena

Syntheses of the Smallest Carbon Nanohoops and the Emergence of Unique Physical Phenomena

Chemistry of Single-Walled Carbon Nanotubes

Extraordinary Transformations to Achieve the Synthesis of Remarkable Aromatic Compounds

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