Explicit ab initio current-density maps contradict the annulene-within-an-annulene model of [n]circulenes: in both coronene and corannulene the expected diamagnetic current on the perimeter is opposed by the central, paramagnetic ring current.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1002/1521-3773(20010119)40:2<362::AID-ANIE362>3.0.CO;2-Z | DOI Listing |
Chemphyschem
September 2024
Dipartimento di Chimica e Biologia "A. Zambelli", University of Salerno, Fisciano, 84084, Italy.
Some years ago, Jishan Wu reported the synthesis of 8MC and 10MC, two homologues of the cyclopenta-ring-fused oligo(m-phenylene) macrocycles mMC, each behaving as an annulene-within-an-annulene (AWA). This was a surprising result as the AWA behavior is rare. Both molecules have a partial polyradical character, enforced by the quest for restoring some aromatic character of benzene rings.
View Article and Find Full Text PDFChem Sci
January 2024
Institut für Organische Chemie, Universität Würzburg Am Hubland 97074 Würzburg Germany
Corannulene is known to undergo a fast bowl-to-bowl inversion at r.t. a planar transition structure (TS).
View Article and Find Full Text PDFNat Commun
February 2023
School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore, Singapore.
While the synthesis of nanographenes has advanced greatly in the past few years, development of their atomically precise functionalization strategies remains rare. The ability to modify the carbon scaffold translates to controlling, adjusting, and adapting molecular properties. Towards this end, here, we show that mechanochemistry is capable of transforming graphitization precursors directly into chlorinated curved nanographenes through a Scholl reaction.
View Article and Find Full Text PDFJ Phys Chem A
December 2021
Peterhouse, Cambridge CB2 1RD, England, United Kingdom.
In previous studies, the Hückel-London-Pople-McWeeny (HLPM) method was used to calculate the "topological" ring currents and bond currents that are associated with the mono-, and the doubly and triply iterated , of corannulene and coronene and their respective dianions. This gave rise to some intriguing patterns in these currents, which were partially rationalized by a detailed examination of the lone nonbonding orbitals that each of these structures possesses. In the present work, the same HLPM approach is used to investigate whether analogous changes in bond-current patterns are observed when going from the neutral species to the dianions of the iterated derived from some other, simpler, "parents" having molecular graphs with a nullity of zero.
View Article and Find Full Text PDFJ Phys Chem A
November 2021
Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy.
In this work, we investigate a particular class of carbon nanocones, which we name graphannulenes, and present a generalized Hückel rule (GHR) that predicts the character of their ground state based on simply the three topological indices that uniquely define them. Importantly, this rule applies to both flat and curved systems, encompassing a wide variety of known structures that do not satisfy the "classic" 4 + 2 rule such as coronene, corannulene, and Kekulene. We test this rule at the Hückel level of theory for a large number of systems, including structures that are convex and flat, with a saddle-like geometry, and at the CASSCF level of theory for a selected representative subset.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!