The Chemical Structure of Carbon Nanothreads Analyzed by Advanced Solid-State NMR

Pu Duan, Xiang Li, Tao Wang, Bo Chen, Stephen J. Juhl, Daniel Koeplinger, Vincent Henry Crespi, John V. Badding, Klaus Schmidt-Rohr

Research output: Contribution to journalArticle

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Abstract

Carbon nanothreads are a new type of one-dimensional sp3-carbon nanomaterial formed by slow compression and decompression of benzene. We report characterization of the chemical structure of 13C-enriched nanothreads by advanced quantitative, selective, and two-dimensional solid-state nuclear magnetic resonance (NMR) experiments complemented by infrared (IR) spectroscopy. The width of the NMR spectral peaks suggests that the nanothread reaction products are much more organized than amorphous carbon. In addition, there is no evidence from NMR of a second phase such as amorphous mixed sp2/sp3-carbon. Spectral editing reveals that almost all carbon atoms are bonded to one hydrogen atom, unlike in amorphous carbon but as is expected for enumerated nanothread structures. Characterization of the local bonding structure confirms the presence of pure fully saturated "degree-6" carbon nanothreads previously deduced on the basis of crystal packing considerations from diffraction and transmission electron microscopy. These fully saturated threads comprise between 20% and 45% of the sample. Furthermore, 13C-13C spin exchange experiments indicate that the length of the fully saturated regions of the threads exceeds 2.5 nm. Two-dimensional 13C-13C NMR spectra showing bonding between chemically nonequivalent sites rule out enumerated single-site thread structures such as polytwistane or tube (3,0) but are consistent with multisite degree-6 nanothreads. Approximately a third of the carbon is in "degree-4" nanothreads with isolated double bonds. The presence of doubly unsaturated degree-2 benzene polymers can be ruled out on the basis of 13C-13C NMR with spin exchange rate constants tuned by rotational resonance and 1H decoupling. A small fraction of the sample consists of aromatic rings within the threads that link sections with mostly saturated bonding. NMR provides the detailed bonding information necessary to refine solid-state organic synthesis techniques to produce pure degree-6 or degree-4 carbon nanothreads.

Original languageEnglish (US)
Pages (from-to)7658-7666
Number of pages9
JournalJournal of the American Chemical Society
Volume140
Issue number24
DOIs
StatePublished - Jun 20 2018

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Magnetic Resonance Spectroscopy
Carbon
Nuclear magnetic resonance
Amorphous carbon
Benzene
Atoms
Synthetic Chemistry Techniques
Reaction products
Nanostructured materials
Nanostructures
Hydrogen
Infrared spectroscopy
Rate constants
Polymers
Compaction
Decompression
Transmission Electron Microscopy
Diffraction
Experiments
Transmission electron microscopy

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Duan, Pu ; Li, Xiang ; Wang, Tao ; Chen, Bo ; Juhl, Stephen J. ; Koeplinger, Daniel ; Crespi, Vincent Henry ; Badding, John V. ; Schmidt-Rohr, Klaus. / The Chemical Structure of Carbon Nanothreads Analyzed by Advanced Solid-State NMR. In: Journal of the American Chemical Society. 2018 ; Vol. 140, No. 24. pp. 7658-7666.
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Duan, P, Li, X, Wang, T, Chen, B, Juhl, SJ, Koeplinger, D, Crespi, VH, Badding, JV & Schmidt-Rohr, K 2018, 'The Chemical Structure of Carbon Nanothreads Analyzed by Advanced Solid-State NMR', Journal of the American Chemical Society, vol. 140, no. 24, pp. 7658-7666. https://doi.org/10.1021/jacs.8b03733

The Chemical Structure of Carbon Nanothreads Analyzed by Advanced Solid-State NMR. / Duan, Pu; Li, Xiang; Wang, Tao; Chen, Bo; Juhl, Stephen J.; Koeplinger, Daniel; Crespi, Vincent Henry; Badding, John V.; Schmidt-Rohr, Klaus.

In: Journal of the American Chemical Society, Vol. 140, No. 24, 20.06.2018, p. 7658-7666.

Research output: Contribution to journalArticle

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T1 - The Chemical Structure of Carbon Nanothreads Analyzed by Advanced Solid-State NMR

AU - Duan, Pu

AU - Li, Xiang

AU - Wang, Tao

AU - Chen, Bo

AU - Juhl, Stephen J.

AU - Koeplinger, Daniel

AU - Crespi, Vincent Henry

AU - Badding, John V.

AU - Schmidt-Rohr, Klaus

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N2 - Carbon nanothreads are a new type of one-dimensional sp3-carbon nanomaterial formed by slow compression and decompression of benzene. We report characterization of the chemical structure of 13C-enriched nanothreads by advanced quantitative, selective, and two-dimensional solid-state nuclear magnetic resonance (NMR) experiments complemented by infrared (IR) spectroscopy. The width of the NMR spectral peaks suggests that the nanothread reaction products are much more organized than amorphous carbon. In addition, there is no evidence from NMR of a second phase such as amorphous mixed sp2/sp3-carbon. Spectral editing reveals that almost all carbon atoms are bonded to one hydrogen atom, unlike in amorphous carbon but as is expected for enumerated nanothread structures. Characterization of the local bonding structure confirms the presence of pure fully saturated "degree-6" carbon nanothreads previously deduced on the basis of crystal packing considerations from diffraction and transmission electron microscopy. These fully saturated threads comprise between 20% and 45% of the sample. Furthermore, 13C-13C spin exchange experiments indicate that the length of the fully saturated regions of the threads exceeds 2.5 nm. Two-dimensional 13C-13C NMR spectra showing bonding between chemically nonequivalent sites rule out enumerated single-site thread structures such as polytwistane or tube (3,0) but are consistent with multisite degree-6 nanothreads. Approximately a third of the carbon is in "degree-4" nanothreads with isolated double bonds. The presence of doubly unsaturated degree-2 benzene polymers can be ruled out on the basis of 13C-13C NMR with spin exchange rate constants tuned by rotational resonance and 1H decoupling. A small fraction of the sample consists of aromatic rings within the threads that link sections with mostly saturated bonding. NMR provides the detailed bonding information necessary to refine solid-state organic synthesis techniques to produce pure degree-6 or degree-4 carbon nanothreads.

AB - Carbon nanothreads are a new type of one-dimensional sp3-carbon nanomaterial formed by slow compression and decompression of benzene. We report characterization of the chemical structure of 13C-enriched nanothreads by advanced quantitative, selective, and two-dimensional solid-state nuclear magnetic resonance (NMR) experiments complemented by infrared (IR) spectroscopy. The width of the NMR spectral peaks suggests that the nanothread reaction products are much more organized than amorphous carbon. In addition, there is no evidence from NMR of a second phase such as amorphous mixed sp2/sp3-carbon. Spectral editing reveals that almost all carbon atoms are bonded to one hydrogen atom, unlike in amorphous carbon but as is expected for enumerated nanothread structures. Characterization of the local bonding structure confirms the presence of pure fully saturated "degree-6" carbon nanothreads previously deduced on the basis of crystal packing considerations from diffraction and transmission electron microscopy. These fully saturated threads comprise between 20% and 45% of the sample. Furthermore, 13C-13C spin exchange experiments indicate that the length of the fully saturated regions of the threads exceeds 2.5 nm. Two-dimensional 13C-13C NMR spectra showing bonding between chemically nonequivalent sites rule out enumerated single-site thread structures such as polytwistane or tube (3,0) but are consistent with multisite degree-6 nanothreads. Approximately a third of the carbon is in "degree-4" nanothreads with isolated double bonds. The presence of doubly unsaturated degree-2 benzene polymers can be ruled out on the basis of 13C-13C NMR with spin exchange rate constants tuned by rotational resonance and 1H decoupling. A small fraction of the sample consists of aromatic rings within the threads that link sections with mostly saturated bonding. NMR provides the detailed bonding information necessary to refine solid-state organic synthesis techniques to produce pure degree-6 or degree-4 carbon nanothreads.

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