Aromaticity and Extrusion of Benzenoids Linked to [<i>o</i>‐COSAN]<sup>−</sup>: Clar Has the Answer

Poater, Jordi; Viñas, Clara; Olid, David; Solà, Miquel; Teixidor, Francesc

doi:10.1002/anie.202200672

Cited by 18 publications

(5 citation statements)

References 48 publications

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“… 4 In the last few years, the similarities and differences of 3D aromatic systems to their π-aromatic analogues have been highlighted in several pioneering studies. 5 Moreover, the existence of planar carborane systems with combined σ- and π-aromatic ring currents was predicted 6 and they were synthesized, 7 further strengthening the close relationship between the two types of aromaticity. If the statement of Teixidor and Solà is true, and π- and 3D aromaticity are two sides of the same coin, 5 b then the question arises whether noticeable conjugation can be achieved between them.…”

Section: Introductionmentioning

confidence: 88%

Conjugation between 3D and 2D aromaticity: does it really exist? The case of carborane-fused heterocycles

et al. 2022

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Section: Introductionmentioning

confidence: 88%

Conjugation between 3D and 2D aromaticity: does it really exist? The case of carborane-fused heterocycles

et al. 2022

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“…Thus, the hypothesized 2D−3D global aromaticity of these compounds does not take place but aromaticity is localized on the 3D carborane and on the 2D pyridyl ring, not on the intermediate-fused six-membered ring. 12,14,92 Then, what is the reason for the distinct NMR properties of these systems? In particular, what is the origin of the unprecedented 1 H NMR chemical shift of 7.46 ppm for the H atom of the fused six-membered ring δ(H*) of 3c?…”

Section: Theoretical Calculations For Boron Cluster-coredmentioning

confidence: 99%

Facile Construction of New Hybrid Conjugation via Boron Cage Extension

et al. 2023

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Aromatic polycyclic systems have been extensively utilized as structural subunits for the preparation of various functional molecules. Currently, aromatics-based polycyclic systems are predominantly generated from the extension of two-dimensional (2D) aromatic rings. In contrast, polycyclic compounds based on the extension of three-dimensional (3D) aromatics such as boron clusters are less studied. Here, we report three types of boron cluster-cored tricyclic molecular systems, which are constructed from a 2D aromatic ring, a 3D aromatic nido-carborane, and an alkyne. These new tricyclic compounds can be facilely accessed by Pd-catalyzed B–H activation and the subsequent cascade heteroannulation of carborane and pyridine with an alkyne in an isolated yield of up to 85% under mild conditions without any additives. Computational results indicate that the newly generated ring from the fusion of the 3D carborane, the 2D pyridyl ring, and an alkyne is non-aromatic. However, such fusion not only leads to a 1H chemical shift considerably downfield shifted owing to the strong diatropic ring current of the embedded carborane but also devotes to new/improved physicochemical properties including increased thermal stability, the emergence of a new absorption band, and a largely red-shifted emission band and enhanced emission efficiency. Besides, a number of bright, color-tunable solid emitters spanning over all visible light are obtained with absolute luminescence efficiency of up to 61%, in contrast to aggregation-caused emission quenching of, e.g., Rhodamine B containing a 2D-aromatics-fused structure. This work demonstrates that the new hybrid conjugated tricyclic systems might be promising structural scaffolds for the construction of functional molecules.

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“…Cobalt bis(dicarbollide) is a low-spin diamagnetic (d 6 ) anionic complex composed of a Co(III) atom at its center, coordinated to two [C 2 B 9 H 11 ] 2− ligands. The electrons are fully delocalized in the inner bonding orbitals, and the ion is considered an aromatic species [50][51][52][53]. While two known isomeric forms exist, [(1,2-C 2 B 9 H 11 ) 2 -3,3 -Co(III)] − and [(1,7-C 2 B 9 H 11 ) 2 -2,2 -Co(III)] − , the number of potential isomers can reach 45 [9].…”

Section: General Properties Of the Cobalt Bis(dicarbollide) Ionmentioning

confidence: 99%

Chemistry of Carbon-Substituted Derivatives of Cobalt Bis(dicarbollide)(1−) Ion and Recent Progress in Boron Substitution

Pazderová,

Tüzün,

Bavol

et al. 2023

Molecules

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The cobalt bis(dicarbollide)(1−) anion (1−), [(1,2-C2B9H11)2-3,3′-Co(III)](1−), plays an increasingly important role in material science and medicine due to its high chemical stability, 3D shape, aromaticity, diamagnetic character, ability to penetrate cells, and low cytotoxicity. A key factor enabling the incorporation of this ion into larger organic molecules, biomolecules, and materials, as well as its capacity for “tuning” interactions with therapeutic targets, is the availability of synthetic routes that enable easy modifications with a wide selection of functional groups. Regarding the modification of the dicarbollide cage, syntheses leading to substitutions on boron atoms are better established. These methods primarily involve ring cleavage of the ether rings in species containing an oxonium oxygen atom connected to the B(8) site. These pathways are accessible with a broad range of nucleophiles. In contrast, the chemistry on carbon vertices has remained less elaborated over the previous decades due to a lack of reliable methods that permit direct and straightforward cage modifications. In this review, we present a survey of methods based on metalation reactions on the acidic C-H vertices, followed by reactions with electrophiles, which have gained importance in only the last decade. These methods now represent the primary trends in the modifications of cage carbon atoms. We discuss the scope of currently available approaches, along with the stereochemistry of reactions, chirality of some products, available types of functional groups, and their applications in designing unconventional drugs. This content is complemented with a report of the progress in physicochemical and biological studies on the parent cobalt bis(dicarbollide) ion and also includes an overview of recent syntheses and emerging applications of boron-substituted compounds.

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Aromaticity and Extrusion of Benzenoids Linked to [o‐COSAN]⁻: Clar Has the Answer

Cited by 18 publications

References 48 publications

Conjugation between 3D and 2D aromaticity: does it really exist? The case of carborane-fused heterocycles

Conjugation between 3D and 2D aromaticity: does it really exist? The case of carborane-fused heterocycles

Facile Construction of New Hybrid Conjugation via Boron Cage Extension

Chemistry of Carbon-Substituted Derivatives of Cobalt Bis(dicarbollide)(1−) Ion and Recent Progress in Boron Substitution

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Aromaticity and Extrusion of Benzenoids Linked to [o‐COSAN]−: Clar Has the Answer

Cited by 18 publications

References 48 publications

Conjugation between 3D and 2D aromaticity: does it really exist? The case of carborane-fused heterocycles

Conjugation between 3D and 2D aromaticity: does it really exist? The case of carborane-fused heterocycles

Facile Construction of New Hybrid Conjugation via Boron Cage Extension

Chemistry of Carbon-Substituted Derivatives of Cobalt Bis(dicarbollide)(1−) Ion and Recent Progress in Boron Substitution

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Product

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Aromaticity and Extrusion of Benzenoids Linked to [o‐COSAN]⁻: Clar Has the Answer