Macrocyclic Polyradicaloids with Unusual Super-ring Structure and Global Aromaticity

Abstract

Wu and colleagues describe the challenging synthesis and physical characterization of a macrocyclic octaradicaloid and decaradicaloid. They exhibit the long-sought-after ''annulene-within-an-annulene'' super-ring structure and unusual global aromaticity with individual inner and outer rings following Hü ckel's rule in the singlet state and Baird's rule in the triplet state, respectively.

Topological Ring Currents and Bond Currents in Some Neutral and Anionic Altans and Iterated Altans of Corannulene and Coronene

“…Synthetic work in this area has also very recently been forthcoming. 12 The above-mentioned authors then used the ab initio ipsocentric formalism [1][2][3][4]13 to calculate pictorial current-density maps for these structures and, in some cases, quantitative integrated current densities, which are the equivalent (in the ipso-centric approach) of individual bond-current intensities. The present authors have previously been concerned with how well these calculated magnetic properties, obtained via this sophisticated ab initio approach, are mimicked by the much more rudimentary Huckel 14 −London 15 −Pople 16 −McWeeny 17 (HLPM) method, a topological, quasi graph-theoretical approach 18,19 that ostensibly relies on no parameters whatsoever and whose predictions depend only on a knowledge of the molecular graph 20 of the conjugated system under study, as well as on the areas of its constituent rings.…”

Enumeration of Pentahexagonal Annuli in the Plane

“…Some problems related to symmetry of benzenoid systems and fullerenes are discussed in [58][59][60][61][62]. Synthesis and aromaticity of certain annuli with high symmetry are described in [25,26]. We have determined how many annuli possess symmetry (without detailed classifications).…”

“…In addition, synonyms of the word 'corannulenes' in organic chemistry are circulenes and primitive (catacondensed) coronoids [24]. Coronoids are regarded by us as substances of potential use to nanotechnology fields (e.g., due to their unique electronic properties; see [25,26] and bibl.). Avoiding the detailed motivation of this statement, we offer here only a few possible examples.…”

Bulky Substituent Effect on Reactivity of Localized Singlet Cyclopentane‐1,3‐diyls with π‐Single Bonding (C‐π‐C) Character

“…The results prompted us to investigate the effect of more rigid and bulkier substituents (R′), such as mesityl (Mes) and triisopropylphenyl (Tip) groups, at the meta position of the phenyl ring, on the reactivity of singlet diradicals S‐ DR2 ‐ 4 (Figure ), which have π‐single bonding character between the radical centers . The bulky substituents are well known to kinetically stabilize the low‐valent species and open‐shell molecules . The effect of R′ groups on the reactivity of the singlet diradicals was assessed by theoretical calculations, transient absorption spectroscopic analysis, and product analysis of S‐ DR2 ‐ 4 .…”

“…[a] R. Akisaka, Prof. M. Abe Department of Chemistry Graduate School of Scienece Hiroshima University netically stabilize the low-valent species [9] and open-shell molecules. [28][29][30][31] The effect of R' groups on ther eactivity of the singlet diradicals was assessedb yt heoretical calculations, transient absorption spectroscopic analysis,a nd product analysiso f S-DR2-4.…”