Magnetically-induced current density investigation in carbohelicenes and azahelicenes

Cherni, Emna; Champagne, Benoı̂t; Ayadi, Sameh; Liégeois, Vincent

doi:10.1039/c9cp02071c

Cited by 14 publications

(21 citation statements)

References 58 publications

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“…The ring-current strengths in Table are those corresponding to each ring. The terminal rings have stronger total ring currents, as Cherni et al stated . However, pπ J ind of the individual rings is diatropic with very similar ring-current strengths in the range of 12.08–13.41 nA/T, suggesting that all the 6-MRs have approximately the same degree of delocalization despite stacking.…”

Section: Resultsmentioning

confidence: 80%

“…The terminal rings have stronger total ring currents, as Cherni et al stated. 60 However, pπ J ind of the individual rings is diatropic with very similar ring-current strengths in the range of 12.08−13.41 nA/ T, suggesting that all the 6-MRs have approximately the same degree of delocalization despite stacking. Therefore, the correct diagnosis of aromaticity via magnetic criteria must be carried out by considering the π-electron contributions to the ring-current strengths.…”

Section: ■ Results and Discussionmentioning

confidence: 98%

“…Since helicenes consist of several rings forming a nonplanar structure with conjugated bonds and delocalized π-electrons, evaluating their aromatic character based on studies of magnetic properties has led to different conclusions. [56][57][58][59][60] In the case of the B ind analysis, the π-contribution to B ind z has a deshielded zone along the helical axis that grows with the number of rings in the helicene, giving rise to anomalous shieldings in the individual rings. 56 This behavior is reproduced by our pπ B ind z computations.…”

Section: Fullerene and Guadienementioning

confidence: 99%

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Magnetically Induced Ring-Current Strengths of Planar and Nonplanar Molecules: New Insights from the Pseudo-π Model

Orozco‐Ic¹,

Dimitrova

Barroso³

et al. 2021

J. Phys. Chem. A

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The π-contribution to the magnetically induced current densities, ring-current strengths, and induced magnetic fields of large planar molecules (as kekulene) and three-dimensional molecules (as [10]cyclophenacene and chiral toroidal nanotubes C 2016 and C 2196 ) have been computed using the pseudo-π model with the gauge-including magnetically induced currents method. The magnetic response analysis shows that π-electrons are the main actors of the electron delocalization in carbon systems regardless of their size, suggesting that the π-component of the ring-current strengths can be used for assessing the aromatic character of this kind of molecules. Computations using the pseudo-π model yield current densities and induced magnetic fields that are not contaminated by contributions from core and σ-electrons allowing investigations of large molecular structures as polycyclic aromatic hydrocarbons and cylindrical or toroidal carbon nanotubes.File list (2) download file view on ChemRxiv pseudo_currents_main1_final_final.pdf (1.73 MiB) download file view on ChemRxiv pseudo_currents_SI.pdf (1.12 MiB)

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Section: Resultsmentioning

confidence: 80%

Section: ■ Results and Discussionmentioning

confidence: 98%

Section: Fullerene and Guadienementioning

confidence: 99%

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Magnetically Induced Ring-Current Strengths of Planar and Nonplanar Molecules: New Insights from the Pseudo-π Model

Orozco‐Ic¹,

Dimitrova

Barroso³

et al. 2021

J. Phys. Chem. A

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“…The current density is reminiscent of the one of helicenes. 16,17 We also consider the dication of [12]infinitene to study how oxidation affects the magnetic response.…”

mentioning

confidence: 99%

Non-intersecting ring currents in [12]infinitene

Orozco‐Ic

Valiev

Sundholm

2022

Phys. Chem. Chem. Phys.

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“…It is not a well-defined concept even when one considers isolated rings, and it becomes more complicated for polycyclic aromatic hydrocarbons (PAHs) and their heterocyclic analogues. Numerous computational approaches have been employed to find out whether such a molecule is aromatic as a whole and, more importantly, to investigate the aromatic character of various rings in the same polycyclic molecule. − …”

Section: Introductionmentioning

confidence: 99%

Interplay of Aromaticity and Antiaromaticity in N-Doped Nanographenes

et al. 2020

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The aromaticity of three nonplanar, fully conjugated aza-nanographenes built around a pyrrolo [3,2-b]pyrrole core is assessed through the application of two different computational proceduresGIMIC and NICS. We examine the calculated magnetically induced current densities (GIMIC) and nucleus-independent chemical shifts (NICS). The structural differences between these three apparently similar molecules lead to significantly different aromatic properties. GIMIC analysis indicates that the peripheral diatropic ring current of 3.9 nA/T for the studied bowl-shaped diaza-nanographene is the strongest, followed by the double [6]helicene which lacks seven-membered rings, and is practically nonexistent for the double [5]helicene possessing seven-membered rings. The biggest difference however is that in the two not-fully-fused molecules, the central pyrrole rings possess a significant diatropic current of about 4.1 nA/T, whereas there is no such current in the diaza-nanographene. Moreover, the antiaromaticity of the sevenmembered rings is increasing while moving from double [5]helicene to diaza-nanographene (from −2.4 to −6.0 nA/T). The induced currents derived from NICS π,zz -XY-scan analysis for all of the studied systems are in qualitative agreement with the GIMIC results. Subtle differences may originate from σ-electron currents in GIMIC or inaccuracy of NICS π,zz values due to the nonplanarity of the systems, but the general picture is similar.

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Magnetically-induced current density investigation in carbohelicenes and azahelicenes

Abstract: 3D streamline plot of the current density (left) and total induced current (right) for [6]-helicene molecule.

Cited by 14 publications

References 58 publications

Magnetically Induced Ring-Current Strengths of Planar and Nonplanar Molecules: New Insights from the Pseudo-π Model

Magnetically Induced Ring-Current Strengths of Planar and Nonplanar Molecules: New Insights from the Pseudo-π Model

Non-intersecting ring currents in [12]infinitene

Interplay of Aromaticity and Antiaromaticity in N-Doped Nanographenes

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