A study on the aromaticity of [n]phenacenes and [n]helicenes (n= 3–9)

Kalam, Horigul; Kerim, Ablikim; Najmidin, Kalbinur; Abdurishit, Paruza; Tawar, Tursungul

doi:10.1016/j.cplett.2013.12.057

Cited by 15 publications

(11 citation statements)

References 36 publications

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“…One plausible explanation is that the benzene ring neighboring the outer azaborine unit is more free to resonate as compared with the one fixed between two inner azaborine rings . Consequently, the double bonds between the outer azaborine unit and the neighboring benzene ring may have larger bond resonance energy than the corresponding one in the inner azaborine rings, which thus contributes to the higher aromaticities for the two outer azaborine rings in comparison to the other inner ones . Furthermore, different NICS(1) values can be found for the corresponding azaborine rings in BNFS (−3.8 and −4.1 ppm) and BNFL (−3.6 and −4.3 ppm).…”

Section: Resultsmentioning

confidence: 99%

“…[36] Consequently,t he double bonds between the outer azaborine unit and the neighboring benzene ring may have larger bond resonance energy than the corresponding one in the inner azaborine rings, which thus contributes to the higher aromaticities for the two outer azaborine rings in comparison to the other inner ones. [37] Furthermore, different NICS(1) values can be found for the corresponding azaborine rings in BNFS (À3.8 and À4.1 ppm) and BNFL (À3.6 and À4.3 ppm). The NICS (1) values of the 1,2-azaborine rings neighboring the furan rings in both BNFS and BNFL are more negative thant he corresponding ones close to the thiophene rings.…”

Section: Theoretical Approachesmentioning

confidence: 99%

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B₂N₂‐Embedded Polycyclic Aromatic Hydrocarbons with Furan and Thiophene Derivatives Functionalized in Crossed Directions

Chen

Qiao

et al. 2019

Chemistry A European J

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A series of polycyclic aromatic hydrocarbons (PAHs), consisting of two pairs of BN units, have been designed and their synthesis has been achieved by electrophilic C−H borylation. Two conjugation extension directions can be found in these B2N2‐embedded PAHs. The B2N2‐containing backbone with shorter effective conjugation length is isoelectronic with diaryl‐fused anthracene, whereas the second derivative, with longer effective conjugation length, is isoelectronic with bis(trans‐arylvinyl)benzene. By incorporating different aryl groups, i.e., furyl, thienyl, benzo[b]furyl, and benzo[b]thienyl groups, into the two crossed directions of the B2N2‐embedded PAHs, their electronic and optical properties have been comparatively investigated by photophysical, electrochemical, and theoretical approaches. It is found that both the substituents and their conjugation extension directions have significant effects on the aromatic and photophysical properties of the B2N2‐embedded PAHs. The conjugation extension in the shorter backbone is more pronounced on the effective conjugation length than the longer backbone. Moreover, all the B2N2‐embedded PAHs behave as both Lewis acids and Lewis bases, and reversible photoluminescence switching can be observed by simply neutralizing the added Lewis acid or Lewis base.

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Section: Resultsmentioning

confidence: 99%

Section: Theoretical Approachesmentioning

confidence: 99%

B₂N₂‐Embedded Polycyclic Aromatic Hydrocarbons with Furan and Thiophene Derivatives Functionalized in Crossed Directions

Chen

Qiao

et al. 2019

Chemistry A European J

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“…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%

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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“…One plausible explanation is that the benzene ring neighboring the terminal azaborine unit is much easier to resonate as compared with the one fixed between two inner azaborine rings. Consequently, the double bonds between the terminal azaborine unit and the neighboring benzene ring may have larger bond resonance energy than the corresponding one in the inner azaborine rings, which thus contributes to the higher aromaticity for the two terminal azaborine rings in comparison to the other inner rings . Although the aromaticity of the azaborine rings in these BN‐embedded PAHs are relatively lower than the corresponding aromatic rings in the related isoelectronic carbon analogs (Figure ), on the other hand, only negligible changes can be observed for the NICS(1) values of the benzene and thiophene rings neighboring to the azaborine ring as compared with those for the C=C analogues, suggesting that the borylation has little influence on the aromaticity of the surrounded aromatic rings.…”

Section: Resultsmentioning

confidence: 92%

BN‐Embedded Polycyclic Aromatic Hydrocarbon Oligomers: Synthesis, Aromaticity, and Reactivity

Chen

Qiao

et al. 2020

Angew Chem Int Ed

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BN‐embedded oligomers with different pairs of BN units were synthesized by electrophilic borylation. Up to four pairs of BN units were incorporated in the large polycyclic aromatic hydrocarbons (PAHs). Their geometric, photophysical, electrochemical, and Lewis acidic properties were investigated by X‐ray crystallography, optical spectroscopy, and cyclic voltammetry. The B−N bonds show delocalized double‐bond characteristics and the conjugation can be extended through the trans‐orientated aromatic azaborine units. Calculations reveal the relatively lower aromaticity for the inner azaborine rings in the BN‐embedded PAH oligomers. The frontier orbitals of the longer oligomers are delocalized over the inner aromatic rings. Consequently, the inner moieties of the BN‐embedded PAH oligomers are more active than the outer parts. This is confirmed by a simple oxidation reaction, which has significant effects on the aromaticity and the intramolecular charge‐transfer interactions.

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A study on the aromaticity of [n]phenacenes and [n]helicenes (n= 3–9)

Cited by 15 publications

References 36 publications

B₂N₂‐Embedded Polycyclic Aromatic Hydrocarbons with Furan and Thiophene Derivatives Functionalized in Crossed Directions

B₂N₂‐Embedded Polycyclic Aromatic Hydrocarbons with Furan and Thiophene Derivatives Functionalized in Crossed Directions

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

BN‐Embedded Polycyclic Aromatic Hydrocarbon Oligomers: Synthesis, Aromaticity, and Reactivity

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A study on the aromaticity of [n]phenacenes and [n]helicenes (n= 3–9)

Cited by 15 publications

References 36 publications

B2N2‐Embedded Polycyclic Aromatic Hydrocarbons with Furan and Thiophene Derivatives Functionalized in Crossed Directions

B2N2‐Embedded Polycyclic Aromatic Hydrocarbons with Furan and Thiophene Derivatives Functionalized in Crossed Directions

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

BN‐Embedded Polycyclic Aromatic Hydrocarbon Oligomers: Synthesis, Aromaticity, and Reactivity

Contact Info

Product

Resources

About

B₂N₂‐Embedded Polycyclic Aromatic Hydrocarbons with Furan and Thiophene Derivatives Functionalized in Crossed Directions

B₂N₂‐Embedded Polycyclic Aromatic Hydrocarbons with Furan and Thiophene Derivatives Functionalized in Crossed Directions