A new type of two-dimensional carbon crystal prepared from 1,3,5-trihydroxybenzene

Abstract

A new two-dimensional (2D) carbon crystal, different from graphene, has been prepared from 1,3,5-trihydroxybenzene, consisting of 4-carbon and 6-carbon rings in 1:1 ratio, named 4-6 carbophene by authors, in which all carbon atoms possess sp 2 hybrid orbitals with some distortion, forming an extensive conjugated π-bonding planar structure. The angles between the three σ-bonds of the carbon sp 2 orbitals are roughly 120°, 90°, and 150°. Each of the three non-adjacent sides of a 6C-ring is shared with a 4C-ring; and each of the two opposite sides of a 4C-ring is shared with a 6C-ring. Dodecagonal holes with a diameter of approximate 5.8 Å are regularly located throughout the 2D carbon crystal. Even though the bond energies in 4-6 carbophene are weaker than those in the graphene, the new planar crystal is quite stable in ambient conditions. The 4-6 carbophene can be synthetized from 1,3,5-trihydroxybenzene or other benzene derivatives through dehydration and polymerization reactions, and may possess several possible patterns that form a family of 2D carbon crystals. A possible side reaction involving 1,3,5-trihydroxybenzene is also discussed, which may produce a carbon-oxygen two dimensional crystal.Graphene 1,2 is an allotrope of elemental carbon in the form of an atomic-scale, two-dimensional, honey-comb lattice, in which all carbon atoms are in sp 2 electron configuration, resulting in an extensive conjugated π -system. Graphene is the basic structural element of several other carbon allotropes, including graphite 3,4 , carbon nanotubes 5 and fullerenes (C 60 ) 6 . Graphene is an excellent material possessing many outstanding physical and chemical properties, such as high electrical and thermal conductivity 7 , huge specific surface area 8 , good optical transparency 2 , and excellent mechanical strength 9,10 . Therefore, graphene is expected to have many applications in broad areas 11,12 .From material science and structural chemistry viewpoints, graphene is a two-dimensional (2D) crystal and a 2D carbon material 13 . Since the first 2D carbon crystal graphene was found in 2004 1,2 , several other 2D crystals and materials of carbon have emerged 14,15 . In recent years the 2D crystals and materials become a booming research field. A comprehensive review on this field can be found in a review article by Peng et al. 16 . Chemically, a sheet of graphene is a large aromatic molecule consisting of hexagonal planar structural units 17,18 that are similar to anthracene and phenanthrene. In graphene, all carbon atoms are in standard sp 2 electronic configuration so that the angles between the three σ -bonds of carbon sp 2 orbitals are 120°, 120°, and 120°, just as they are in the carbon atoms in benzene and other aromatic molecules 19,20 .Actually, the orbitals in carbon atoms can also be in a distorted sp 2 hybrid form, resulting in planar structural units other than hexagons [21][22][23][24] . This possibility raises an interesting question: "Are there other two-dimensional carbon crystals that are different from gra...

2D Octagon-Structure Carbon and Its Polarization Resolved Raman Spectra

“…In recent years, people found many 2D materials from allotropes of carbon and from group V elements. Some of them have potential application in optoelectronic, nano electronic devices and hydrogen storage, because of their unique electronic and mechanical properties [ 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. In 2018, Cao et al found the twisted bilayer graphene is able to be an insulator or superconductor [ 11 , 12 ].…”

Porous graphene and graphenylene nanotubes: Electronic structure and strain effects

“…One of these combinations is the so called graphenylene, which has a small band gap and delocalized frontier orbitals [28][29][30]. A possible route to the synthesis of graphenylene was proposed elsewhere [28] and its experimental realization, although obtained through a different route, was reported recently [31,32]. Further, Schlütter et al reported recently that they were able to synthesize octafunctionalized biphenylene GNRs [33].…”

N-Carbophenes: two-dimensional covalent organic frameworks derived from linear N-phenylenes

“…We concluded that a carbophene would be the more likely candidate for what Du et al produced. [16,17] Du et al reported that their synthesized material contained oxygen, thus to better fit this condition, future work should replace hydrogen atoms with oxygen-containing functional groups.…”

“…[12,16] Some of the results that Du et al reported suggest that they had not synthesized graphenylene but, instead, a 2D hydrocarbon material based on linear 3-phenylene. [17] To the best of our knowledge, no experimental followup has determined which material Du et al synthesized. Nor has the 2D hydrocarbon (denoted here as 3-carbophene) been theoretically examined before now.…”