Magnetically Induced Current Densities in Toroidal Carbon Nanotubes

Reiter, Kevin; Weigend, Florian; Wirz, Lukas N.; Dimitrova, Maria; Sundholm, Dage

doi:10.1021/acs.jpcc.9b03769

Cited by 23 publications

(30 citation statements)

References 109 publications

(201 reference statements)

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“…In the previous GIMIC studies, we successfully used the M06-2X functional in calculations on aromatic and antiaromatic porphyrinoids. 53 − 55 However, generally, the M06-2X functional exaggerates the diatropic contribution to the ring current, 55 , 56 which we actually also observe for C 60 –C 100 . The strength of the ring current gradually increases from 0.7 nA T –1 for C 44 to 2.4 nA T –1 for C 100 ( Figure 3 ).…”

Section: Resultssupporting

confidence: 68%

Aromaticity of Even-Number Cyclo[n]carbons (n = 6–100)

et al. 2020

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The recently synthesized cyclo[18]carbon molecule has been characterized in a number of studies by calculating electronic, spectroscopic, and mechanical properties. However, cyclo[18]carbon is only one member of the class of cyclo[ n ]carbons—standalone carbon allotrope representatives. Many of the larger members of this class of molecules have not been thoroughly investigated. In this work, we calculate the magnetically induced current density of cyclo[ n ]carbons in order to elucidate how electron delocalization and aromatic properties change with the size of the molecular ring ( n ), where n is an even number between 6 and 100. We find that the Hückel rules for aromaticity (4 k + 2) and antiaromaticity (4 k ) become degenerate for large C n rings ( n > 50), which can be understood as a transition from a delocalized electronic structure to a nonaromatic structure with localized current density fluxes in the triple bonds. Actually, the calculations suggest that cyclo[ n ]carbons with n > 50 are nonaromatic cyclic polyalkynes. The influence of the amount of nonlocal exchange and the asymptotic behavior of the exchange–correlation potential of the employed density functionals on the strength of the magnetically induced ring current and the aromatic character of the large cyclo[ n ]carbons is also discussed.

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Section: Resultssupporting

confidence: 68%

Aromaticity of Even-Number Cyclo[n]carbons (n = 6–100)

et al. 2020

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“…The ringcurrent strengths were calculated at the B3LYP level and the TPSS for comparison with results obtained in previous studies. 72 The inner and outer J ind fluxes have the same tropicity, when the external magnetic field is oriented along the torus symmetry axis. The inner J ind flux is though somewhat weaker than that outside the surface.…”

Section: Toroidal Nanotube C2016mentioning

confidence: 98%

“…16,86 When the external magnetic field is perpendicular to the CNT, the current density is diatropic inside and outside. Recently, Reiter et al 72 calculated the magnetically induced current densities of a family of toroidal carbon nanotubes (TCNT) using the GIMIC method. When the external field is applied along the torus symmetry axis, they found that TCNTs with HOMO-LUMO gaps larger than 0.2 eV generally sustain weak global ring currents and that the ring-current strength increases with increasing TCNT size.…”

Section: Toroidal Nanotube C2016mentioning

confidence: 99%

“…The inner J ind flux is though somewhat weaker than that outside the surface. The total ring-current strength around the TCNT produces a global strong diatropic current of 232.3 nA/T at the TPSS level, 72 while B3LYP leads to 37.35 nA/T (see Table 2). pπ J ind supports that the π-electrons are responsible for the ring current since the ring-current strength is 416.7 nA/T and 210.43 nA/T at the TPSS and B3LYP levels, respectively.…”

Section: Toroidal Nanotube C2016mentioning

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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“…47 Calculations of the magnetic-field-induced current densities in organic molecules have been widely used to characterize ring currents 48 and aromaticity in large organic systems 32,49 including toroidal carbon nanotubes. 50 The magnetizability χ can also be defined as the secondorder derivative of the total energy E of the system with regard to B…”

Section: Theory and Calculation Of Diamagnetismmentioning

confidence: 99%

Calculation of Diamagnetic Susceptibility Tensors of Organic Crystals: From Coronene to Pharmaceutical Polymorphs

et al. 2020

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Understanding why crystallization in strong magnetic fields can lead to new polymorphs requires methods to calculate the diamagnetic response of organic molecular crystals. We develop the calculation of the macroscopic diamagnetic susceptibility tensor, χ cryst , for organic molecular crystals using periodic density functional methods. The crystal magnetic susceptibility tensor, χ cryst , for all experimentally known polymorphs, and its molecular counterpart, χ mol , are calculated for flexible pharmaceuticals such as carbamazepine, flufenamic acid, and chalcones, and rigid molecules, such as benzene, pyridine, acridine, anthracene, and coronene, whose molecular magnetic properties have been traditionally studied. A tensor addition method is developed to approximate the crystal diamagnetic susceptibility tensor, χ cryst , from the molecular one, χ mol , giving good agreement with those calculated directly using the more costly periodic density functional method for χ cryst . The response of pharmaceutical molecules and crystals to magnetic fields, as embodied by χ cryst , is largely determined by the packing in the crystal, as well as the molecular conformation. The anisotropy of χ cryst can vary considerably between polymorphs though the isotropic terms are fairly constant. The implications for developing a computational method for predicting whether crystallization in a magnetic field could produce a novel or different polymorph are discussed.

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Magnetically Induced Current Densities in Toroidal Carbon Nanotubes

Cited by 23 publications

References 109 publications

Aromaticity of Even-Number Cyclo[n]carbons (n = 6–100)

Aromaticity of Even-Number Cyclo[n]carbons (n = 6–100)

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

Calculation of Diamagnetic Susceptibility Tensors of Organic Crystals: From Coronene to Pharmaceutical Polymorphs

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