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Three-Dimensional Carbon Allotropes Comprising Phenyl Rings and Acetylenic Chains in sp+sp(2) Hybrid Networks.

Wang JT, Chen C, Li HD, Mizuseki H, Kawazoe Y - Sci Rep (2016)

Bottom Line: These structures are constructed by inserting acetylenic or diacetylenic bonds into an all sp(2)-hybridized rhombohedral polybenzene lattice, and the resulting 3D phenylacetylene and phenyldiacetylene nets comprise a 12-atom and 18-atom rhombohedral primitive unit cells in the symmetry, which are characterized as the 3D chiral crystalline modification of 2D graphyne and graphdiyne, respectively.Simulated phonon spectra reveal that these structures are dynamically stable.The present results establish a new type of carbon phases and offer insights into their outstanding structural and electronic properties.

View Article: PubMed Central - PubMed

Affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.

ABSTRACT
We here identify by ab initio calculations a new type of three-dimensional (3D) carbon allotropes that consist of phenyl rings connected by linear acetylenic chains in sp+sp(2) bonding networks. These structures are constructed by inserting acetylenic or diacetylenic bonds into an all sp(2)-hybridized rhombohedral polybenzene lattice, and the resulting 3D phenylacetylene and phenyldiacetylene nets comprise a 12-atom and 18-atom rhombohedral primitive unit cells in the symmetry, which are characterized as the 3D chiral crystalline modification of 2D graphyne and graphdiyne, respectively. Simulated phonon spectra reveal that these structures are dynamically stable. Electronic band calculations indicate that phenylacetylene is metallic, while phenyldiacetylene is a semiconductor with an indirect band gap of 0.58 eV. The present results establish a new type of carbon phases and offer insights into their outstanding structural and electronic properties.

No MeSH data available.


Related in: MedlinePlus

Electron density difference and electron localization function maps.(a,b) The electron density difference (EDD) for rh12 carbon (a) and rh18 carbon (b) with an isodensity of 0.1 e/Å3. The blue colour denotes a gain and the yellow colour a loss of electron density. (c,d) The electron localization function (ELF) for rh12 carbon (c) and rh18 carbon (d) with an isosurface level of 0.75.
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f5: Electron density difference and electron localization function maps.(a,b) The electron density difference (EDD) for rh12 carbon (a) and rh18 carbon (b) with an isodensity of 0.1 e/Å3. The blue colour denotes a gain and the yellow colour a loss of electron density. (c,d) The electron localization function (ELF) for rh12 carbon (c) and rh18 carbon (d) with an isosurface level of 0.75.

Mentions: To understand the bonding nature of electrons in both rh12 and rh18 carbon, the electron density difference (EDD) and electron localization function (ELF) maps are illustrated in Fig. 5. The EDD maps represent the variation of electron density in terms of chemical bonding. One can make an EDD plot by subtracting the overlapping atomic electron density from the self-consistent electron density of a crystal. The ELF maps can give a clear and quantitative description on the basic chemical bond (high ELF values 1 > ELF > 0.5 indicate the formation of covalent bonds)444546, which was initially proposed by Becke and Edgecombe45 based on Hartree-Fock theory, and generalized by Savin et al.46 based on density functional theory. From the EDD maps shown in Fig. 5a,b, we can be seen that there is a larger gain of electron density between triple bonded carbons. Meanwhile, from the ELF maps shown in Fig. 5c,d, we can see that the electrons are well localized along the carbon chain, and the enhanced localization between triple bonded carbons can be seen clearly, which is more than the localization between the single and aromatic bonded carbons. These results show the strong triple bonding nature in the sp+sp2 hybrid networks. Furthermore, to understand the aromaticity in the phenyl rings, the nuclear-independent chemical shift NICS(0) at the center of the phenyl rings are calculated using the gauge-including atomic orbital (GIAO) method at the B3LYP/6-311 + G(d,p) level47. The NICS(0) values are estimated to be −8.16 ppm for benzene, −5.23 ppm for rh12 carbon, and −6.57 ppm for rh18 carbon. These results show that the aromaticity in phenyl rings of rh12 and rh18 carbon are smaller than the aromaticity in benzene.


Three-Dimensional Carbon Allotropes Comprising Phenyl Rings and Acetylenic Chains in sp+sp(2) Hybrid Networks.

Wang JT, Chen C, Li HD, Mizuseki H, Kawazoe Y - Sci Rep (2016)

Electron density difference and electron localization function maps.(a,b) The electron density difference (EDD) for rh12 carbon (a) and rh18 carbon (b) with an isodensity of 0.1 e/Å3. The blue colour denotes a gain and the yellow colour a loss of electron density. (c,d) The electron localization function (ELF) for rh12 carbon (c) and rh18 carbon (d) with an isosurface level of 0.75.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4834540&req=5

f5: Electron density difference and electron localization function maps.(a,b) The electron density difference (EDD) for rh12 carbon (a) and rh18 carbon (b) with an isodensity of 0.1 e/Å3. The blue colour denotes a gain and the yellow colour a loss of electron density. (c,d) The electron localization function (ELF) for rh12 carbon (c) and rh18 carbon (d) with an isosurface level of 0.75.
Mentions: To understand the bonding nature of electrons in both rh12 and rh18 carbon, the electron density difference (EDD) and electron localization function (ELF) maps are illustrated in Fig. 5. The EDD maps represent the variation of electron density in terms of chemical bonding. One can make an EDD plot by subtracting the overlapping atomic electron density from the self-consistent electron density of a crystal. The ELF maps can give a clear and quantitative description on the basic chemical bond (high ELF values 1 > ELF > 0.5 indicate the formation of covalent bonds)444546, which was initially proposed by Becke and Edgecombe45 based on Hartree-Fock theory, and generalized by Savin et al.46 based on density functional theory. From the EDD maps shown in Fig. 5a,b, we can be seen that there is a larger gain of electron density between triple bonded carbons. Meanwhile, from the ELF maps shown in Fig. 5c,d, we can see that the electrons are well localized along the carbon chain, and the enhanced localization between triple bonded carbons can be seen clearly, which is more than the localization between the single and aromatic bonded carbons. These results show the strong triple bonding nature in the sp+sp2 hybrid networks. Furthermore, to understand the aromaticity in the phenyl rings, the nuclear-independent chemical shift NICS(0) at the center of the phenyl rings are calculated using the gauge-including atomic orbital (GIAO) method at the B3LYP/6-311 + G(d,p) level47. The NICS(0) values are estimated to be −8.16 ppm for benzene, −5.23 ppm for rh12 carbon, and −6.57 ppm for rh18 carbon. These results show that the aromaticity in phenyl rings of rh12 and rh18 carbon are smaller than the aromaticity in benzene.

Bottom Line: These structures are constructed by inserting acetylenic or diacetylenic bonds into an all sp(2)-hybridized rhombohedral polybenzene lattice, and the resulting 3D phenylacetylene and phenyldiacetylene nets comprise a 12-atom and 18-atom rhombohedral primitive unit cells in the symmetry, which are characterized as the 3D chiral crystalline modification of 2D graphyne and graphdiyne, respectively.Simulated phonon spectra reveal that these structures are dynamically stable.The present results establish a new type of carbon phases and offer insights into their outstanding structural and electronic properties.

View Article: PubMed Central - PubMed

Affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.

ABSTRACT
We here identify by ab initio calculations a new type of three-dimensional (3D) carbon allotropes that consist of phenyl rings connected by linear acetylenic chains in sp+sp(2) bonding networks. These structures are constructed by inserting acetylenic or diacetylenic bonds into an all sp(2)-hybridized rhombohedral polybenzene lattice, and the resulting 3D phenylacetylene and phenyldiacetylene nets comprise a 12-atom and 18-atom rhombohedral primitive unit cells in the symmetry, which are characterized as the 3D chiral crystalline modification of 2D graphyne and graphdiyne, respectively. Simulated phonon spectra reveal that these structures are dynamically stable. Electronic band calculations indicate that phenylacetylene is metallic, while phenyldiacetylene is a semiconductor with an indirect band gap of 0.58 eV. The present results establish a new type of carbon phases and offer insights into their outstanding structural and electronic properties.

No MeSH data available.


Related in: MedlinePlus