13C NMR patterns of C36H2x fullerene hydrides

Corminbœuf, Clémence; Fowler, Patrick W.; Heine, Thomas

doi:10.1016/s0009-2614(02)00986-7

Cited by 10 publications

(3 citation statements)

References 28 publications

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“…Ref. 38 reported a detailed analysis of the trends in the carbon‐13 NMR spectra of various‐size fullerenes that were produced experimentally. In a similar vein, calculations can help to understand properties that depend on the finite size of the GQDs as well as their boundary structure.…”

Section: Introductionmentioning

confidence: 99%

Characteristic Spectral Patterns in the Carbon‐13 Nuclear Magnetic Resonance Spectra of Hexagonal and Crenellated Graphene Fragments

et al. 2014

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Nuclear magnetic resonance (NMR) spectroscopy is an important molecular characterisation method that may aid the synthesis and production of graphenes, especially the molecular-scale graphene nanoislands that have gathered significant attention due to their potential electronic and optical applications. Herein, carbon-13 NMR chemical shifts were calculated using density functional theory methods for finite, increasing-size fragments of graphene, hydrogenated graphene (graphane) and fluorinated graphene (fluorographene). Both concentric hexagon-shaped (zigzag boundary) and crenellated (armchair) fragments were investigated to gain information on the effect of different types of flake boundaries. Convergence trends of the (13)C chemical shift with respect to increasing fragment size and the boundary effects were found and rationalised in terms of low-lying electronically excited states. The results predict characteristic behaviour in the (13)C NMR spectra. Particular attention was paid to the features of the signals arising from the central carbon atoms of the fragments, for graphene and crenellated graphene on the one hand and graphane and fluorographene on the other hand, to aid the interpretation of the overall spectral characteristics. In graphene, the central nuclei become more shielded as the system size increases whereas the opposite behaviour is observed for graphane and fluorographene. The (13)C signals from some of the perimeter nuclei of the crenellated fragments obtain smaller and larger chemical shift values than central nuclei for graphene and graphane/fluorographene, respectively. The diameter of the graphenic quantum dots with zigzag boundary correlates well with the predicted carbon-13 chemical shift range, thus enabling estimation of the size of the system by NMR spectroscopy. The results provide data of predictive quality for future NMR analysis of the graphene nanoflake materials.

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Section: Introductionmentioning

confidence: 99%

Characteristic Spectral Patterns in the Carbon‐13 Nuclear Magnetic Resonance Spectra of Hexagonal and Crenellated Graphene Fragments

et al. 2014

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“…The first theoretical study on C 36 has been reported by Grossman and co-workers, which revealed that the energetically most favorable structures of C 36 fullerene are associated with D 6 h and D 2 d symmetry using density functional calculation with local density approximation (LDA) and generalized gradient approximation (GGA) methods. Subsequently, a considerable amount of theoretical work has been published in the literature dealing with the C 36 fullerene system. − Depending on the method of calculation, the ground-state structure of C 36 cage is found to be either D 2 d or D 6 h ; however, in most of the reports it is clearly stated that the D 2 d singlet state, D 6 h singlet state, and D 6 h triplet state are almost isoenergetic. ,,,, Apart from U@C 36 , which is detected in FT-ICR mass spectrum, there is no experimental evidence available for any other endohedral C 36 derivative. Even for the U@C 36 system, no further theoretical or experimental information is available on its structure and characterization.…”

Section: Introductionmentioning

confidence: 99%

Enhancement in the Stability of 36-Atom Fullerene through Encapsulation of a Uranium Atom

Manna

Ghanty

2013

J. Phys. Chem. C

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With an objective to rationalize the experimentally observed intense U@C 36 peak in the mass spectrum of U@C 2n metallofullerene, structural, stability, and spectroscopic aspects of the uranium doped C 36 fullerene have been studied in a unified and systematic way using density functional theory (DFT) and its time-dependent variant. Relativistic effects have been taken into account within the framework of zeroth-order regular approximation using scalar and spin− orbit-based approaches. Among all of the 15 possible classical isomers reported for the C 36 fullerene cage system, singlet D 2d and triplet D 6h structures are found to be isoenergetic and most stable. Encapsulation of uranium atom into various C 36 cages leads to 15 distinct isomers with considerable energy differences. It has also been shown that this encapsulation process results in significant gain in thermodynamic stability. The most stable U@C 36 isomer is found to be associated with C 6v symmetry and closed-shell electronic configuration, derived from the open-shell D 6h structure of C 36 . The next stable isomer is associated with C s symmetry and obtained from the corresponding singlet D 2d structure of the C 36 cage. Distinct changes have also been found in the calculated vibrational and UV−visible spectra of the U@C 36 cluster as compared to the corresponding bare C 36 cage. All of the calculated quantities reported here suggest that the stability of the U@C 36 cluster is high enough for possible formation of cluster-assembled material leading to synthesis of this metallofullerene experimentally.

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“…CS tensors which are reproduced reliably by performing high-level quantum chemical calculations provide highly valuable information about electrostatic environment around the nucleus, which feels subtle changes by any perturbations [30]. The calculations of NMR parameters using ab initio techniques have found the ability of quickly evaluating and correlating the magnitude of CS tensors with variations in bond angles, bond lengths, and the nearest neighboring interactions, which has increased the significance of utilizing these parameters in exploring molecular structures [31,32].…”

Section: Introductionmentioning

confidence: 99%

A computational investigation of 11B and 15N chemical shielding tensors as well as local aromaticity based on NICS characterization in the N/B doped triangular graphene quantum dots

Anafcheh

Ghafouri

2013

Superlattices and Microstructures

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13C NMR patterns of C36H2x fullerene hydrides

Cited by 10 publications

References 28 publications

Characteristic Spectral Patterns in the Carbon‐13 Nuclear Magnetic Resonance Spectra of Hexagonal and Crenellated Graphene Fragments

Characteristic Spectral Patterns in the Carbon‐13 Nuclear Magnetic Resonance Spectra of Hexagonal and Crenellated Graphene Fragments

Enhancement in the Stability of 36-Atom Fullerene through Encapsulation of a Uranium Atom

A computational investigation of 11B and 15N chemical shielding tensors as well as local aromaticity based on NICS characterization in the N/B doped triangular graphene quantum dots

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