Computational Study of 13C NMR Chemical Shift Anisotropy Patterns in C20H10 and [C20H10]4-. Insights into Their Variation upon Planarization and Formation of Concentric Aromatic Species in the Smaller Isolated-Pentagon Structural Motif

Alvaro Muñoz-Castro, Wilson Caimanque-Aguilar, Cesar Morales-Verdejo

Resultado de la investigación: Article

7 Citas (Scopus)

Resumen

Corannulene, C20H10, exhibits a concave surface in the ground state that is able to experience a bowl-to-bowl inversion through a planar conformation. Such a structure is the smaller example resembling an isolated-pentagon motif, as a relevant fragment in fullerene chemistry. Here, we explored the differences between bowl and planar conformations involving both energetic and 13C NMR properties, for the neutral and tetraanionic species by using density functional theory (DFT) methods. This allows us to understand the variation of the chemical environment at the carbon atoms upon planarization of this representive motif. Our results reveal that the variation of the chemical shift comes about from the variation of different main components of the shielding tensor, according to the relative position of the carbon atoms in the structure (i.e., rim, hub, and protonated), which is more relevant for both hub and protonated sites, in contrast to the rim carbon remaining almost unshifted. Interestingly, the planar transition state exhibits a more favorable bonding situation than the bowl-shaped conformation; however, the higher strain is enough to overcome this extra stabilization. Upon reduction to the tetraanionic counterpart (C20H10 4-), a lesser strain in the planar conformation is observed, decreasing the inversion barrier. In addition, the formation of the concentric aromatic ring systems in C20H10 4-, results in a more axially symmetric chemical shift anisotropy (CSA) tensor for the hub carbons, accounting in a local manner, for the concentric aromatic behavior in such structure in contrast to the neutral parent. These observations can be useful to evaluate the aromatic behavior of teh isolated-pentagon rule (IPR) motif in fullerene cages.

Idioma originalEnglish
Páginas (desde-hasta)2698-2703
Número de páginas6
PublicaciónJournal of Physical Chemistry A
Volumen121
N.º13
DOI
EstadoPublished - 6 abr 2017
Publicado de forma externa

Huella dactilar

Chemical shift
hubs
chemical equilibrium
Conformations
Anisotropy
Carbon
Nuclear magnetic resonance
Fullerenes
nuclear magnetic resonance
anisotropy
carbon
rims
fullerenes
Tensors
tensors
inversions
Atoms
Shielding
Ground state
Density functional theory

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Citar esto

@article{b9fece26a1a04687a647825eedd6c447,
title = "Computational Study of 13C NMR Chemical Shift Anisotropy Patterns in C20H10 and [C20H10]4-. Insights into Their Variation upon Planarization and Formation of Concentric Aromatic Species in the Smaller Isolated-Pentagon Structural Motif",
abstract = "Corannulene, C20H10, exhibits a concave surface in the ground state that is able to experience a bowl-to-bowl inversion through a planar conformation. Such a structure is the smaller example resembling an isolated-pentagon motif, as a relevant fragment in fullerene chemistry. Here, we explored the differences between bowl and planar conformations involving both energetic and 13C NMR properties, for the neutral and tetraanionic species by using density functional theory (DFT) methods. This allows us to understand the variation of the chemical environment at the carbon atoms upon planarization of this representive motif. Our results reveal that the variation of the chemical shift comes about from the variation of different main components of the shielding tensor, according to the relative position of the carbon atoms in the structure (i.e., rim, hub, and protonated), which is more relevant for both hub and protonated sites, in contrast to the rim carbon remaining almost unshifted. Interestingly, the planar transition state exhibits a more favorable bonding situation than the bowl-shaped conformation; however, the higher strain is enough to overcome this extra stabilization. Upon reduction to the tetraanionic counterpart (C20H10 4-), a lesser strain in the planar conformation is observed, decreasing the inversion barrier. In addition, the formation of the concentric aromatic ring systems in C20H10 4-, results in a more axially symmetric chemical shift anisotropy (CSA) tensor for the hub carbons, accounting in a local manner, for the concentric aromatic behavior in such structure in contrast to the neutral parent. These observations can be useful to evaluate the aromatic behavior of teh isolated-pentagon rule (IPR) motif in fullerene cages.",
author = "Alvaro Mu{\~n}oz-Castro and Wilson Caimanque-Aguilar and Cesar Morales-Verdejo",
year = "2017",
month = "4",
day = "6",
doi = "10.1021/acs.jpca.7b01477",
language = "English",
volume = "121",
pages = "2698--2703",
journal = "Journal of Physical Chemistry A",
issn = "1089-5639",
publisher = "American Chemical Society",
number = "13",

}

TY - JOUR

T1 - Computational Study of 13C NMR Chemical Shift Anisotropy Patterns in C20H10 and [C20H10]4-. Insights into Their Variation upon Planarization and Formation of Concentric Aromatic Species in the Smaller Isolated-Pentagon Structural Motif

AU - Muñoz-Castro, Alvaro

AU - Caimanque-Aguilar, Wilson

AU - Morales-Verdejo, Cesar

PY - 2017/4/6

Y1 - 2017/4/6

N2 - Corannulene, C20H10, exhibits a concave surface in the ground state that is able to experience a bowl-to-bowl inversion through a planar conformation. Such a structure is the smaller example resembling an isolated-pentagon motif, as a relevant fragment in fullerene chemistry. Here, we explored the differences between bowl and planar conformations involving both energetic and 13C NMR properties, for the neutral and tetraanionic species by using density functional theory (DFT) methods. This allows us to understand the variation of the chemical environment at the carbon atoms upon planarization of this representive motif. Our results reveal that the variation of the chemical shift comes about from the variation of different main components of the shielding tensor, according to the relative position of the carbon atoms in the structure (i.e., rim, hub, and protonated), which is more relevant for both hub and protonated sites, in contrast to the rim carbon remaining almost unshifted. Interestingly, the planar transition state exhibits a more favorable bonding situation than the bowl-shaped conformation; however, the higher strain is enough to overcome this extra stabilization. Upon reduction to the tetraanionic counterpart (C20H10 4-), a lesser strain in the planar conformation is observed, decreasing the inversion barrier. In addition, the formation of the concentric aromatic ring systems in C20H10 4-, results in a more axially symmetric chemical shift anisotropy (CSA) tensor for the hub carbons, accounting in a local manner, for the concentric aromatic behavior in such structure in contrast to the neutral parent. These observations can be useful to evaluate the aromatic behavior of teh isolated-pentagon rule (IPR) motif in fullerene cages.

AB - Corannulene, C20H10, exhibits a concave surface in the ground state that is able to experience a bowl-to-bowl inversion through a planar conformation. Such a structure is the smaller example resembling an isolated-pentagon motif, as a relevant fragment in fullerene chemistry. Here, we explored the differences between bowl and planar conformations involving both energetic and 13C NMR properties, for the neutral and tetraanionic species by using density functional theory (DFT) methods. This allows us to understand the variation of the chemical environment at the carbon atoms upon planarization of this representive motif. Our results reveal that the variation of the chemical shift comes about from the variation of different main components of the shielding tensor, according to the relative position of the carbon atoms in the structure (i.e., rim, hub, and protonated), which is more relevant for both hub and protonated sites, in contrast to the rim carbon remaining almost unshifted. Interestingly, the planar transition state exhibits a more favorable bonding situation than the bowl-shaped conformation; however, the higher strain is enough to overcome this extra stabilization. Upon reduction to the tetraanionic counterpart (C20H10 4-), a lesser strain in the planar conformation is observed, decreasing the inversion barrier. In addition, the formation of the concentric aromatic ring systems in C20H10 4-, results in a more axially symmetric chemical shift anisotropy (CSA) tensor for the hub carbons, accounting in a local manner, for the concentric aromatic behavior in such structure in contrast to the neutral parent. These observations can be useful to evaluate the aromatic behavior of teh isolated-pentagon rule (IPR) motif in fullerene cages.

UR - http://www.scopus.com/inward/record.url?scp=85019578884&partnerID=8YFLogxK

U2 - 10.1021/acs.jpca.7b01477

DO - 10.1021/acs.jpca.7b01477

M3 - Article

AN - SCOPUS:85019578884

VL - 121

SP - 2698

EP - 2703

JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

SN - 1089-5639

IS - 13

ER -