Septulene: The Heptagonal Homologue of Kekulene

Kumar, B. Santhosh; Viboh, Ruth L.; Bonifacio, Margel C.; Thompson, William B.; Buttrick, Jonathan C.; Westlake, Babe C.; Kim, Min‐Soo; Zoellner, Robert W.; Varganov, Sergey A.; Mörschel, Philipp; Teteruk, Jaroslav; Schmidt, Martin; King, Benjamin T.

doi:10.1002/anie.201203266

Cited by 82 publications

(121 citation statements)

References 39 publications

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“…Clar's rule suggests that the ring currents are localized in the 6-MRs and, consequently, the inner protons should be deshielded. The latter prediction is the one that matches the experimental observation that inner protons resonate at δ > 7 ppm (Kumar et al, 2012). A remarkable validation of the model emerge from the scanning tunneling microscope (STM) images of PAHs showing patterns that resemble very much Clar aromatic sextet structures (Iyer et al, 1998; Ito et al, 2000; Samorí et al, 2001, 2002; Gutman et al, 2004; Watson et al, 2004).…”

supporting

confidence: 81%

“…In general, fully benzenoids have large HOMO-LUMO gaps (>2.1 eV) and are particularly stable (Chen and Liu, 2011). The 1 H NMR spectrum of kekulene and septulene provided another validation of Clar's aromatic sextets rule (Kumar et al, 2012). Pauling's model suggested that kekulene should behave as concentric annulenes and, therefore, the inner protons should be strongly shielded.…”

mentioning

confidence: 98%

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Forty years of Clar's aromatic π-sextet rule

2013

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In 1972 Erich Clar formulated his aromatic π-sextet rule that allows discussing qualitatively the aromatic character of benzenoid species. Now, 40 years later, Clar's aromatic π-sextet rule is still a source of inspiration for many chemists. This simple rule has been validated both experimentally and theoretically. In this review, we select some particular examples to highlight the achievement of Clar's aromatic π-sextet rule in many situations and we discuss two recent successful cases of its application.

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supporting

confidence: 81%

mentioning

confidence: 98%

Forty years of Clar's aromatic π-sextet rule

2013

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“…It is therefore not only already a fragment of a (4,4) armchair carbon nanotube, but the longstanding record holder for being the narrowest diameter carbon nanotube segment ever reported. Ring-closing metathesis (RCM) was used by Ben King in his synthesis of "septulene" (76), [61] a higher homologue of Staab's famous molecule kekulene (73). [62] Septulene (76) was synthesized by a very short metathesis-based synthetic sequence (Scheme 18) that contrasts the much longer cyclophane-based synthesis of kekulene.…”

Section: Metathesis Reactionsmentioning

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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“…8 Since the structural variation is particularly rich for nanographenes, or for the nanosized graphene family with hydrogen termination, nanographene is the most suited material for a research to find a relation between the structure and the property. [9][10][11] In this recognition, we focus on the optical properties of nanographenes. We study how the electrons and holes interact when confined in nanographene with and without defects and how the interaction is reflected in the optical properties.…”

Section: Introductionmentioning

confidence: 99%

Symmetry breaking and excitonic effects on optical properties of defective nanographenes

Noguchi

Sugino

2015

The Journal of Chemical Physics

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We investigate optical properties of the nanographene family and predict a defect induced effect by utilizing the all-electron first-principles GW+Bethe-Salpeter equation (BSE) method based on the many-body perturbation theory. As an accuracy check of the GW+BSE, photoabsorption spectra are calculated for a grossly warped nanographene (C80H30), which was very recently synthesized [Kawasumi et al., Nat. Chem. 5, 739-744 (2013)]. The calculated spectra are found to faithfully reproduce the shape, height, and position of the measured peaks. Then the method is applied to the flat nanographene without defect (C24H12 and C38H16), the curved ones with single defect (C20H10, C28H14, and C32H16), and fragments of C80H30 with double defect (C36H16 and C42H20). The existence of the defects significantly changes the optical spectra. In particular, the interaction between the defects is found to break the symmetry of the atomic geometries and enhance the excitonic effect, thereby generating the extra peaks at the lower photon energy side of the main peak. The present results might help explain the origin of the first two peaks experimentally observed for C80H30.

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Septulene: The Heptagonal Homologue of Kekulene

Cited by 82 publications

References 39 publications

Forty years of Clar's aromatic π-sextet rule

Forty years of Clar's aromatic π-sextet rule

Extraordinary Transformations to Achieve the Synthesis of Remarkable Aromatic Compounds

Symmetry breaking and excitonic effects on optical properties of defective nanographenes

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