How to synthesize covalent lattices

Abstract

Multilayer γ-graphene, an intrinsically semiconducting sp of carbon, via crystallization-assisted irreversible cross-coupling polymerization 2 / sp 1 Methods for synthesizing allotropes.

Description

[Technical Field]

[0001] Related Applications This application claims priority to U.S. Provisional Patent Application No. 63 / 397,416, filed August 12, 2022, the contents of which are incorporated herein by reference in their entirety.

[0002] government funding This invention was made with government support under DE-SC0022100 awarded by the Department of Energy. The government has certain rights in this invention. [Background technology]

[0003] γ-graphene is the most symmetrical sp 2 / sp 1 It is an allotrope and can be thought of as graphene uniformly extended by the insertion of two-carbon acetylene units. To date, bulk γ-graphene has remained synthetically elusive. Monolayer γ-graphene is predicted to be a semiconductor with a moderate band gap, ultrafast charge carrier mobility comparable to that of graphene, high thermal conductivity, and exceptional strength. Due to these properties, γ-graphene could form the basis for next-generation carbon-based electronics, photonics, and solar cells. Graphene-based devices could be ultrathin, flexible, and operate at speeds unachievable by silicon chips. γ-graphene oligomers containing up to four dehydrobenzo

[12] annulene (12-DBA) repeat units have been prepared by multistep organic synthesis, but an extended crystal lattice has remained elusive to date.

[0004] Commonly used pyrolysis and vapor deposition methods for the controlled synthesis of benzenoid allotropes of carbon are sp 1This is not suitable for structures containing γ-graphene, because acetylene readily converts to graphene or amorphous carbon at high temperatures. Graphdyne and graphdyne-graphene heterostructures have been synthesized by templated solution-phase 2D polymerization, but a similar approach has not previously been attempted for γ-graphene. The reported graphdyne synthesis was reported by Graesser-Hey sp. 1 -sp 1 The synthesis of γ-graphene relies on the polymerization of high-energy hexaethynylbenzene by coupling, which can be conveniently localized at the metal surface. 1 and sp 2 Coupling between carbons or de novo formation of three acetylene bonds per each 12-DBA repeat unit would be required. 1 -sp 2 The most common and general method for CC coupling is the Sonogashira reaction. The mechanism of this reaction, like all other Pd-catalyzed cross-couplings, is homogeneous Pd 0 A catalytic cycle is thought to be involved. Therefore, attempting to restrict this chemistry to the surface of a template would be difficult. Furthermore, previously reported γ-graphene oligomers are distorted from planarity due to steric hindrance introduced by the terminal functional groups. This unavoidable distortion of the oligomer, as well as its typically poor solubility, limits stepwise expansion of the lattice beyond 3–4 12-DBA units.

[0005] In "Synthesis of γ-Graphyne Using Dynamic Covalent Chemistry," Nat. Synth 1, 449–454 (2022), Hu et al. claim the synthesis of γ-graphyne in bulk via reversible alkyne metathesis. However, this method is not scalable because the key precursors, 1,2,3,4,5,6-hexakis[2-(4-hexylphenyl)ethynyl]benzene (HHEB) and 1,2,3,4,5,6-hexapropynylbenzene (HPB), are both unstable and extremely difficult to synthesize. These compounds are closely related to hexaethynylbenzene, which is notoriously explosive on contact and, for this reason, are never isolated or handled in pure form. The γ-graphyne described by Hu et al. always features n-hexyl edge groups, which are undesirable for further edge refinement or for use in devices. Furthermore, the Hu manuscript indicates that only reversible reactions can be used to produce this class of materials. The presence of a catalyst in the later stages of such reversible reactions can introduce undesirable defects in the material, such as, but not limited to, intersheet crosslinks. Summary of the Invention

[0006] Embodiments described herein relate to methods for synthesizing covalent lattices based on irreversible bond-forming reactions that favor complete substitution on multifunctional substrates, in particular multilayer γ-graphene, a carbon sp-based lattice, via crystallization-assisted irreversible cross-coupling polymerization. 2 / sp 1We have found that under appropriately tuned Sonogashira coupling conditions, polyfunctional 1,3,5-trihalo-2,4,6-triethynylbenzene monomers can polymerize to extended γ-graphene. The key idea guiding our work is that an effective route to graphene and similar rigid 2D polymers can proceed via reactions that form multiple bonds in a single step or through a series of kinetically coupled rapid steps. Such a mechanism would avoid the kinetic dead-end of partially linked intermediates that limits all previously described syntheses. Furthermore, this type of multisite polymerization would be self-repairing. Defects in the growing lattice would become the most reactive sites due to local strain and distortion, which could be alleviated by multisite reactions with monomers.

[0007] In some embodiments, the bond-forming reaction that favors complete reactivity on multifunctional substrates is the Sonogashira cross-coupling reaction between a terminal alkyne and an aryl halide.

[0008] In some embodiments, the reactant for synthesizing the covalent lattice can be any of the possible 1,3,5-trihalo-2,4,6-triethynylbenzenes (either symmetrical or unsymmetrical), where the halogen is either Cl, Br, or I.

[0009] In other embodiments, the reactant for synthesizing the covalent lattice can be any of the possible ((2,4,6-trihalobenzene-1,3,5-triyl)tris(ethyne-2,1-diyl))tris(trimethylsilane)s (either symmetrical or asymmetrical), where the halogen is either Cl, Br, or I.

[0010] The Sonogashira cross-coupling reaction is carried out using a palladium catalyst. The palladium source can be selected from the following: palladium black, palladium on carbon, palladium (π-cinnamyl) chloride dimer, bis(triphenylphosphine)palladium(II) dichloride, bis(benzonitrile)palladium(II) chloride, bis(triphenylphosphine)palladium(II) diacetate, tetrakis(triphenylphosphine)palladium(0), bis(dibenzylideneacetone)palladium(0), tris(dibenzylideneacetone)dipalladium(0), dichlorobis(tricyclohexylphosphine)palladium(II), dichlorobis(tri-o-tolylphosphine)palladium(II), allylpalladium(II) chloride. The compound is either a dichloromethane, (2-methylallyl)palladium(II) chloride dimer, (1,3-bis(2,6-diisopropylphenyl)imidazolidene)(3-chloropyridyl)palladium(II) dichloride, (1,3-bis(2,6-dimethylphenyl)imidazolidene)(3-chloropyridyl)palladium(II) dichloride, [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene](3-chloropyridyl)palladium(II) dichloride, palladium(II) 2,4-pentanedionate, or a possible alkali metal salt of tris(3,3',3"-phosphinidinetris(benzenesulfonato)palladium(0).

[0011] The Sonogashira cross-coupling reaction can also be carried out using a copper co-catalyst, which can be selected from the following: copper(I) iodide, copper(I) chloride, copper(I) bromide, tetrakis(acetonitrile)copper(I) hexafluorophosphate, tetrakisacetonitrilecopper(I) triflate, copper(0) foil or turnings in combination with pyridine, copper(0) foil or turnings in combination with any aliphatic tertiary amine, or copper(II) sulfate in combination with sodium ascorbate.

[0012] In some embodiments, the reactants, palladium catalyst, and copper co-catalyst are provided in a solvent, which can be selected from pyridine, tetrahydrofuran, a mixture of tetrahydrofuran and N,N-diisopropylethylamine, toluene, benzene, water, a mixture thereof, or a biphasic mixture of water and an immiscible organic solvent.

[0013] In some embodiments, the loading of the Pd catalyst can be from 0.5 mol % to 120 mol % relative to the reactant, for example, 1,3,5-trihalo-2,4,6-triethynylbenzene.

[0014] In other embodiments, the Cu co-catalyst loading can be, for example, 0.1 mol % to 10 mol % reactant relative to the 1,3,5-trihalo-2,4,6-triethynylbenzene.

[0015] In some embodiments, the reaction is carried out at a reaction temperature of from about 60°C to about 130°C.

[0016] In some embodiments, the reaction is carried out in the presence of a soluble fluoride salt.

[0017] In some embodiments, ordered two-dimensional polymerization occurs without a substrate or added template.

[0018] In some embodiments, the synthesis results in multilayer γ-graphene with crystalline domains having linear sizes ranging from 10 nanometers to 500 micrometers.

[0019] In other embodiments, the synthesis yields few layer (eg, 1-25 layer) γ-graphene with crystalline flake linear sizes ranging from 10 nanometers to 500 micrometers. [Brief explanation of the drawings]

[0020] [Figure 1]Figure 1 (AE). Carbon allotropes. (A) Graphite, graphene, zigzag nanotubes, and buckminsterfullerene C60. (B) Biphenylene network. (C) x,y,z-graphene, 12,12,12-graphene, and 6,6,12-graphene. (D) Graphene-n (graphyne for n = 2). (E) Graphene (or γ-graphene). [Figure 2] Figure 2 (AG). Two-dimensional polymerization of TBETB. (A) Overview of selected reaction conditions. (BD) Representative bright-field TEM, SAED, and SEM of carbon flakes obtained from the Pd(PPh3)4 / Cu foil reaction. (EG) Representative bright-field TEM, SAED, and SEM of carbon flakes obtained via the Pd(PPh3)4 / CuI protocol. [Figure 3] Figure 3 (A-D). High-resolution XPS data for the C1s peak region. (A) Carbon flakes obtained by the Pd(PPh3)4 / CuI protocol. (B) Carbon flakes obtained by the Pd(PPh3)4 / Cu foil protocol. (C) Control experiment using only Pd(PPh3)4. (D) Control experiment without catalyst. [Figure 4] 13C NMR spectrum of 1,3,5-tribromo-2,4,6-triiodobenzene in DMSO-d6. [Figure 5] 1H NMR spectrum of ((2,4,6-tribromobenzene-1,3,5-triyl)tris(ethyne-2,1-diyl))tris-(trimethylsilane) in CDCl. [Figure 6] 13C NMR spectrum of ((2,4,6-tribromobenzene-1,3,5-triyl)tris(ethyne-2,1-diyl))tri(trimethylsilane) in CDCl. [Figure 7] 1H NMR spectrum of 1,3,5-tribromo-2,4,6-triethynylbenzene, TBTEB, in DMSO-d6. [Figure 8] 13C NMR spectrum of 1,3,5-tribromo-2,4,6-triethynylbenzene, TBTEB, in DMSO-d6. [Figure 9] Figure 1 shows the FTIR of 1,3,5-tribromo-2,4,6-triiodobenzene (ATR-FTIR on diamond). [Figure 10] FTIR of ((2,4,6-tribromobenzene-1,3,5-triyl)tris(ethyne-2,1-diyl))tris(trimethylsilane) (ATR-FTIR on germanium). [Figure 11] FTIR of 1,3,5-tribromo-2,4,6-triethynylbenzene, TBTEB (ATR-FTIR on germanium). [Figure 12] Table 1 shows the XPS study corresponding to entry 1 (TBTEB and Pd(PPh3)4 / CuI in pyridine). [Figure 13] Table 1, entry 2 shows the corresponding XPS study (TBTEB and Pd(PPh3)4 / Cu foil in pyridine). [Figure 14] Table 1, entry 3 shows the corresponding XPS study (TBTEB and Pd(PPh3)4 in pyridine without Cu). [Figure 15] Table 1 shows the XPS study corresponding to entry 4 (thermal decomposition of TBTEB in refluxing pyridine). [Figure 16] Figure 16 (AD). High-resolution XPS data for the C1s peak region. (A) Table 1, entry 1 (TBTEB and Pd(PPh3)4 / CuI in pyridine). (B) Table 1, entry 2 (TBTEB and Pd(PPh3)4 / Cu foil in pyridine). (C) Table 1, entry 3 (control experiment using TBTEB and Pd(PPh3)4 in pyridine without Cu). (D) Table 1, entry 4 (control experiment without catalyst). [Figure 17]Figure 17 (AD) shows high-resolution Br3d region XPS spectra of selected carbon material samples. (A) Table 1, entry 1 (TBTEB and Pd(PPh3)4 / CuI in pyridine). (B) Table 1, entry 2 (TBTEB and Pd(PPh3)4 / Cu foil in pyridine). (C) Table 1, entry 3 (control experiment using TBTEB and Pd(PPh3)4 in pyridine without Cu). (D) Table 1, entry 4 (control experiment without catalyst). [Figure 18] Figure 18 (AB) shows: (A) Photograph of the carbon material corresponding to Table 1, entry 1 (TBTEB and Pd(PPh3)4 / CuI in pyridine). (B) Photograph of the carbon material corresponding to Table 1, entry 2 (TBTEB and Pd(PPh3)4 / Cu foil in pyridine). [Figure 19] Figure 19 (AD) shows representative bright-field TEM images of the carbon product corresponding to Table 1, entry 1 (TBTEB and Pd(PPh3)4 / CuI in pyridine). [Figure 20] Figure 20 (AF) shows a representative bright-field TEM image of the carbon product corresponding to Table 1, entry 2 (TBTEB in pyridine and Pd(PPh3)4 / Cu foil). (EF) Representative SAED ring pattern for the same material. [Figure 21] Figure 21(A-C) shows representative bright-field TEM images of the carbon product corresponding to Table 1, entry 3 (control experiment using TBTEB and Pd(PPh) in pyridine without Cu). [Figure 22] Figure 22(A-C) shows representative bright-field TEM images of carbon products corresponding to Table 1, entry 4 (thermal decomposition of TBTEB in refluxing pyridine). [Figure 23] Figure 23(AB) shows representative SEM images of the carbon product corresponding to Table 1, entry 2 (TBTEB in pyridine and Pd(PPh3)4 / Cu foil). [Figure 24]Figure 24 (A-H) shows the possible stacking modes and simulated SAED patterns of γ-graphene sheets in the c-orientation (sheets perpendicular to the incident beam). The interatomic distances are obtained from DFT calculations. [Figure 25] Figure 25(A-H) shows the possible stacking modes of γ-graphene sheets and their simulated SAED patterns (matching the experimental diffraction pattern rotated 45° to the (0001) polarity). The interatomic distances are obtained from DFT calculations. [Figure 26] Figure 26(A-H). Possible stacking modes of γ-graphene sheets in the b-orientation and their simulated SAED patterns are shown (sheets parallel to the incident beam). The interatomic distances are obtained from DFT calculations. [Figure 27] Figure 1 shows the DFT-generated potential energy surface for the binding of TBTEB monomer to a γ-graphine monolayer. DETAILED DESCRIPTION OF THE INVENTION

[0021] All scientific and technical terms used in this application have meanings commonly used in the art unless otherwise specified. The definitions provided here are intended to facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of this application.

[0022] The articles "a" and "an" are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, "an element" means one element or more than one element.

[0023] The term "about" will be understood by those of ordinary skill in the art and will vary to some extent depending on the context in which it is used.

[0024] When a moiety "comprises" a certain component, it means that the moiety may further comprise, and does not exclude, other components, unless otherwise disclosed.

[0025] The term "combination thereof" included in a Markush form expression means a mixture or combination of one or more selected from the group of components described in the Markush form expression, and means including at least one selected from the group of components.

[0026] The term "A and / or B" means "A or B, or A and B."

[0027] Throughout this disclosure, various aspects of the invention may be presented in a range format. It should be understood that the description in range format is for convenience and brevity only and should not be construed as an inflexible limitation on the scope of the invention. Thus, the description of a range should be considered to have all possible subranges specifically disclosed, as well as individual numerical values ​​within that range. For example, the description of a range such as 1 to 6 should be considered to have specifically disclosed subranges, such as 1 to 3, 1 to 4, 1 to 5, 2 to 4, 2 to 6, 3 to 6, etc., as well as individual and partial numerical values ​​within that range, such as 1, 2, 3, 4, 5, 5.5, and 6. This is true regardless of the breadth of the range.

[0028] Embodiments described herein relate to methods for synthesizing covalent lattices based on irreversible bond-forming reactions that favor complete substitution on multifunctional substrates, in particular multilayer γ-graphene, a carbon sp-based lattice, via crystallization-assisted irreversible cross-coupling polymerization. 2 / sp 1We have recently reported on methods for preparing or synthesizing allotropes. We have found that under appropriately tuned Sonogashira coupling conditions, polyfunctional 1,3,5-trihalo-2,4,6-triethynylbenzene monomers can polymerize to extended γ-graphenes. The key idea guiding our work is that an effective route to graphenes and similar rigid 2D polymers could proceed via reactions that generate multiple bonds in a single step or through a series of kinetically coupled, rapid steps. Such a mechanism would avoid the kinetic dead-end of partially linked intermediates that limits all previously described syntheses. Furthermore, this type of multisite polymerization would be self-repairing. Defects in the growing lattice would become the most reactive sites due to local strain and distortion, which could be alleviated by multisite reactions with monomers.

[0029] In some embodiments, the bond-forming reaction is a Sonogashira cross-coupling reaction between a terminal alkyne and an aryl halide. Each of the terminal alkyne groups can be cross-coupled with a halogen group of an aryl halide via a Sonogashira cross-coupling reaction, thereby forming a network of such reactants linked by acetylene groups. γ-Graphene can be composed of triple-bonded (sp) and double-bonded (sp2) carbon atoms arranged in a crystal lattice of benzene rings linked by acetylene bonds, and has a planar structure with atomic thickness.

[0030] In some embodiments, the reactants for synthesizing the covalent lattice can be any of the possible 1,3,5-trihalo-2,4,6-triethynylbenzenes (either symmetrical or asymmetrical), where the halogen is either Cl, Br, or I. For example, the trihalotriethynylbenzene can be 1,3,5-tribromo-2,4,6-triethynylbenzene or 1,3,5-tribromo-2,4,6-triethynylbenzene.

[0031] In other embodiments, the reactant for synthesizing the covalent lattice can be any of the possible ((trihalobenzenetriyl)tris(ethyne))tris(trimethylsilane)s (either symmetric or asymmetric), where the halogen is either Cl, Br, or I. For example, the ((trihalobenzenetriyl)tris(ethynediyl))tris(trimethylsilane) can be ((2,4,6-tribromobenzene-1,3,5-triyl)tris(ethyne-2,1-diyl))tris(trimethylsilane).

[0032] In some embodiments, the catalyst can be a compound of palladium. The palladium source can be selected from the following: palladium black, palladium on carbon, palladium (π-cinnamyl) chloride dimer, bis(triphenylphosphine)palladium(II) dichloride, bis(benzonitrile)palladium(II) chloride, bis(triphenylphosphine)palladium(II) diacetate, tetrakis(triphenylphosphine)palladium(0), bis(dibenzylideneacetone)palladium(0), tris(dibenzylideneacetone)dipalladium(0), dichlorobis(tricyclohexylphosphine)palladium(II), dichlorobis(tri-o-tolylphosphine)palladium(II), allylpalladium(II) chloride. The compound is either a dichloromethane, (2-methylallyl)palladium(II) chloride dimer, (1,3-bis(2,6-diisopropylphenyl)imidazolidene)(3-chloropyridyl)palladium(II) dichloride, (1,3-bis(2,6-dimethylphenyl)imidazolidene)(3-chloropyridyl)palladium(II) dichloride, [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene](3-chloropyridyl)palladium(II) dichloride, palladium(II) 2,4-pentanedionate, or a possible alkali metal salt of tris(3,3',3"-phosphinidinetris(benzenesulfonato)palladium(0).

[0033] In other embodiments, the catalyst can include a copper co-catalyst, which can be selected from the following: copper(I) iodide, copper(I) chloride, copper(I) bromide, tetrakis(acetonitrile)copper(I) hexafluorophosphate, tetrakisacetonitrilecopper(I) triflate, copper(0) foil or turnings in combination with pyridine, copper(0) foil or turnings in combination with any aliphatic tertiary amine, or copper(II) sulfate in combination with sodium ascorbate.

[0034] In some embodiments, the reactants, palladium catalyst, and copper co-catalyst are provided in a solvent, which can be selected from pyridine, tetrahydrofuran, a mixture of tetrahydrofuran and N,N-diisopropylethylamine, toluene, benzene, water, combinations thereof, or a biphasic mixture of water and an immiscible organic solvent.

[0035] In one example, the Sonogashira cross-coupling reaction can be carried out in a solution or mixture containing the reactants, a palladium catalyst, and a copper co-catalyst. In some embodiments, the palladium catalyst is Pd(PPh3)4 and the copper co-catalyst is CuI. Such a solution can be prepared by dissolving solid Pd(PPh3)4 and CuI in a solvent mixture. The solvent mixture can include an amine base and an organic solvent. For example, the amine base can include pyridine or triethylamine, and the organic solvent can include toluene.

[0036] In some embodiments, the reaction can also be carried out in the presence of a soluble fluoride salt.

[0037] In some embodiments, the loading of the Pd catalyst in the reaction mixture can be from about 0.5 mol% to about 120 mol% relative to the reactants, e.g., 1,3,5-trihalo-2,4,6-triethynylbenzene. For example, the Pd catalyst can be from about 25 mol% to about 115 mol%, from about 50 mol% to about 110 mol%, or from about 75 mol% to about 105 mol% (e.g., about 100 mol%) relative to the reactants.

[0038] In other embodiments, the Cu cocatalyst loading in the reaction mixture can be from about 0.1 mol% to about 10 mol% relative to the reactant, e.g., 1,3,5-trihalo-2,4,6-triethynylbenzene. For example, the Cu cocatalyst can be from about 1 mol% to about 8 mol%, from about 2 mol% to about 7 mol%, or from about 3 mol% to about 6 mol% (e.g., about 4 mol%) relative to the reactant.

[0039] In some embodiments, a reaction solution or mixture containing reactants, palladium catalyst, copper co-catalyst, solvent, and optional soluble fluoride salt can be heated to a temperature and for a period of time effective to produce a covalent lattice and / or multilayer γ-graphene. In some embodiments, the reaction is carried out in an evacuated inert atmosphere at a reaction temperature of about 60°C to about 130°C, and the period can be at least about 1 hour, at least about 12 hours, at least about 24 hours, at least about 48 hours, or at least about 72 hours (e.g., 72 hours).

[0040] In some embodiments, ordered two-dimensional polymerization occurs without a physical substrate or added template that includes a surface on which two-dimensional polymerization can occur. Such physical substrates can include metal foils, fibers, or particles that define a surface on which polymerization can occur.

[0041] The as-synthesized covalent lattice and / or multilayer γ-graphene can be isolated and / or removed from the reaction solution and rinsed several times (e.g., five times) with a solvent such as ethanol to remove any residue remaining on the surface of the as-synthesized covalent lattice and / or multilayer γ-graphene material.

[0042] In some embodiments, the synthesized graphene can have substantially perfect crystalline uniformity and / or substantially perfect hexagonal symmetry, with few defects. Graphene can also be found in crystalline materials, where sp 1 vs. SP 2It may have a 1:1 ratio of carbon.

[0043] In some embodiments, the synthesis results in multilayer γ-graphene having a crystalline domain linear size ranging from about 10 nanometers to about 500 micrometers. For example, the crystalline domain linear size can be from about 10 nanometers to about 500 micrometers, from about 50 nanometers to about 100 micrometers, from about 100 nanometers to about 50 micrometers, or from about 500 nanometers to about 10 micrometers.

[0044] In other embodiments, the synthesis yields few layer (eg, 1-25 layer) γ-graphene with crystalline flake linear sizes ranging from 10 nanometers to 500 micrometers.

[0045] Yet another embodiment relates to γ-graphene having a linear size of the crystalline domains ranging from 10 nanometers to 500 micrometers.

[0046] In some embodiments, the γ-graphene may include multifunctional reactive groups on the edges of the γ-graphene. The multifunctional reactive groups may be selected from alkyne and halo groups.

[0047] Other embodiments described herein relate to graphene prepared by the processes described herein.

[0048] γ-graphene materials can be used in a variety of applications, including energy, environmental, and biomedical applications. For example, γ-graphene materials can be used in the adsorption, capture, and separation of carbon dioxide, carbon monoxide, ammonia, sulfur dioxide, and other gases; in the adsorption of polymer chains and acrolein and other organic substances; in the selective filtration and purification of water; in seawater separation and desalination as single-atom catalytic substrates for precious metals and stable precious metal catalysis; and in the detection of toxic and harmful substances such as hydrogen peroxide, carbon monoxide, and toxic gases. Biomedical applications include amino acid detection, calmodulin structure and performance control, and promoting cholesterol extraction from proteins. Energy applications can include electrochemical energy storage, hydrogen storage, high-density magnetic storage as thermoelectrics, fabrication of electronic and / or photonic devices (e.g., nonlinear optics), rechargeable batteries, or organic solar cells. Still other applications can include use in ultra-strong composites and in catalysis. Furthermore, γ-graphene materials can be used in solar cells, lithium batteries, photocatalysis, oxygen reduction, field emission performance, and real-time detection of DNA.

[0049] For example, due to its ordered porous structure and unique electronic properties, the nanopores of γ-graphene can be used to accommodate ions for energy storage, and the highly π-conjugated, electron-rich framework can provide d-π interactions with transition metals to prepare single-atom catalysts.

[0050] Hydrogen storage is another potential application of γ-graphene materials. The Kubas interaction is due to the σ / σ interaction between the d orbitals and the H molecule. *It is known that orbital hybridization enhances the binding energy of H2. Calcium ions can also induce Kubas interactions with H2 molecules. γ-Graphene can be used as a support material to disperse Ca ions, and it has previously been found to effectively inhibit the aggregation or clustering of these ions, which is essential for maintaining H2 storage capacity. Lu, Na, and Ti atoms can also be supported on γ-graphene to provide enhanced hydrogen storage capacity.

[0051] Due to the strong d-π interactions between γ-graphene and metal atoms, γ-graphene can be used in γ-graphene-supported transition / noble metal (NM) single atom catalysts. The binding energy of a noble metal single atom on γ-graphene is much larger than that on graphene because of the triple bond p / p * This is because the orbitals can point directly toward the metal atom. γ-Graphene-supported Fe single-atom catalysts exhibit high catalytic activity for CO oxidation, which proceeds via the Eley-Rideal mechanism with a low energy barrier. In acidic media, γ-graphene-supported Fe and Co single-atom catalysts can catalyze the oxygen reduction reaction via an efficient four-electron reduction mechanism. γ-Graphene-supported Cu single-atom catalysts exhibit catalytic efficiency for CO electroreduction and hydrogen evolution reactions. Similarly, Ru-decorated γ-graphene can efficiently catalyze the CO reduction reaction via the Langmuir-Hinshelwood pathway.

[0052] The following examples are for illustrative purposes only and are not intended to limit the scope of the appended claims.

[0053] Example In this example, we show that under appropriately tuned Sonogashira coupling conditions, the A3B3-type monomer, 1,3,5-tribromo-2,4,6-triethynylbenzene (TBTEB, Figure 2), can be polymerized to extended γ-graphene.

[0054] material and method material All reagents and solvents were obtained from commercial sources (Acros Organics, Sigma-Adrich, TCI Chemicals, Fisher Scientific, Oakwood Chemical, and VWR International) and used without further purification unless otherwise noted. Tetrahydrofuran (THF) was distilled over Na / benzophenone. Triethylamine (TEA) was distilled over CaH. Anhydrous pyridine (Py) was purchased from Acros in AcroSeal packaging and used without further purification. Copper foil, 1.0 mm thick Puratronic 99.999% (metal basis) with lateral dimensions of 25 × 50 mm, was purchased from Alfa Aesar and cut into 5 × 10 mm pieces. These pieces were then sonicated sequentially for 20 minutes in 3 M HCl, water, ethanol, and acetone, dried under high vacuum at ambient temperature, and used immediately.

[0055] Synthesis method Reactions were monitored by thin-layer chromatography (TLC) performed on 0.25 mm MilliporeSigma aluminum-backed silica gel plates (60F-254). Plates were visualized using 254 nm UV light and basic potassium permanganate stain (1.5 g KMnO, 0.5 g NaOH, and 10 g KCO in 150 ml water; terminal alkynes stain yellow). Flash chromatography was performed on Luknova SuperSep™ (230-400 mesh) silica gel. Reactions requiring anhydrous or air-free conditions were performed under a positive pressure of N or Ar using standard Schlenk line techniques.

[0056] Nuclear magnetic resonance (NMR) analysis method NMR spectrum was 500.24( 1 H), 125.79( 13 C), or 99.37( 29NMR spectra were recorded on a Bruker Avance III HD 500 spectrometer operating at 1000 MHz and equipped with a Bruker Ascend 500 MHz US Narrow Bore Magnet and a Broadband Prodigy TCI CryoProbe. 1 H, 13 C. 29 Si) or residual solvent peak. Chemical shifts (δ) are reported in parts per million (ppm).

[0057] Gas chromatography-mass spectrometry GC-MS analysis was performed on an Agilent 5977B GC / MSD instrument equipped with an Agilent 7890B automatic liquid sampler. Prior to sample injection, a 10 μL syringe was cleaned with acetone and ethyl acetate (3 × 10 μL each). 1 μL of sample was then automatically injected into the instrument. The method used a 3-minute solvent delay. The oven was initially set to 60°C and maintained at this temperature for 2.25 minutes, after which the temperature was increased to 225°C at a rate of 35°C / minute. Data analysis was performed using Agilent MassHunter Qualitative Analysis Navigator.

[0058] Infrared spectroscopy Routine small molecule FTIR spectra were collected on an Agilent Cary 630 FTIR instrument equipped with a single-reflection germanium or diamond attenuated total reflectance (ATR) module. The instrument was calibrated against a freshly cleaned (acetone) and dried crystal surface before sampling. Solid samples were placed directly on the crystal and fixed in place with a needle press. 4000–550 cm -1 32 scans of the sample were recorded. A background was collected for each sample (512 scans).

[0059] Melting point Melting points were determined using a Mettler Toledo MP50 Melting Point System.

[0060] Preparation of exfoliation samples Analyte dispersions (1 mg / mL) in water were prepared by sonication using a Branson SFX550 Sonifier. A 1 / 8" double-step microtip (Branson p / n 101-063-212) was used. Samples were processed for 15 minutes at 50% amplitude.

[0061] Scanning Electron Microscopy (SEM) The SEM images in Figures 2G and 23 were acquired on an FEI Apreo 2 SEM operating at 5 kV and an FEI Inspect F-50 operating at 30 kV, respectively. For these images, the dry material was applied to carbon tape, mounted on an SEM sample stand, and sputtered with a thin layer of gold.

[0062] Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) The exfoliated samples were analyzed by TEM. Prior to sample preparation, 200-Cu CB grids were plasma-treated for 30 seconds using an Emitech K100x glow discharger. 3 μL of sample dispersion was added to the grid and allowed to absorb for 5 minutes, after which excess solvent was removed. The grid was then transferred to a single-tilt specimen holder and imaged on an FEI Tecnai 20 TEM operating at 200 kV in low-dose mode. Images were recorded on a Tvips F416. Data were collected using SerialEM software. Tilts were performed using an attached alpha rotation goniometer.

[0063] SAED patterns were recorded on an FEI Tecnai 20 TEM with and without a 40 μm selected-area aperture. The acquired patterns were calibrated against the (111) plane of evaporated aluminum (interplanar spacing 0.2338 nm) on a 3 mm grid. The calibration sample was purchased from Electron Microscopy Sciences (EMSp / n80044).

[0064] X-ray photoelectron spectroscopy (XPS) Samples were spread on double-sided copper tape for XPS analysis. Surveys and high-resolution spectra were taken on a PHI VersaProbe II Scanning XPS Microprobe using monochromated Al X-rays at 1000 nm. -10 ~10 -7 The data were acquired at a pressure of 100 Torr. The data were smoothed using the Savitzky-Golay method with a smoothing width of 5 and analyzed using CasaXPS software.

[0065] A Tougaard background was applied to each peak before deconvolution. All peak fits used a generalized Voigt-like peak shape, as this function is most suitable for fitting asymmetric XPS signals. CasaXPS provides a generalized Voigt function described as Lorentzian Finite: LF(α, β, w, n, m), where the first three parameters (α, β, w) affect the Lorentzian line shape and its asymmetry, and the last two (n, m) change the width of the Gaussian function and the number of convolutions the Lorentzian component undergoes. Symmetric peak parameters for the LF line shape were used: LF(1, 1, 255, 360, 6), values ​​derived from the default symmetric peak shape settings for CasaXPS. All subpeak widths were limited to a full width at half maximum (FWHM) of 1.6 eV or less. The subpeak was at 283.7 eV (terminal alkyne sp). 1 ), 284.6eV (aromatic sp 2 ), 285.3 eV (internal alkyne sp 1 ), 286.9 eV (aromatic C-Br), and 288.5 eV (carbonyl C=O). All peaks were allowed ±0.2 eV padding for peak positions.

[0066] Calculations and Modeling Density functional theory (DFT) calculations All DFT calculations were performed via the RIPER module in TURBOMOLE / 7.5 using 2D periodic boundary conditions. In all cases, a PBE density functional with D3 dispersion correction and Becke-Johnson damping was used. All computational geometries were in broad agreement with previous computational studies of γ-graphene.

[0067] The potential energy surfaces for both γ-graphene bilayers and individual molecule / graphene supercells were calculated as a function of the horizontal offset of the upper γ-graphene layer or molecule relative to the lower layer, with the interlayer distance fixed at 3.35 Å. The binding energy for each structure was calculated as the adsorption energy (EE binding =EE bilayer -EE separated) A 9 × 9 k-point grid was used for the γ-graphene bilayer structure. Monomer / graphene supercells were constructed using a 3 × 3 γ-graphene monolayer, ensuring 1 nm spacing between adjacent periodic images of the monomer. Due to the resulting repeatability of these supercells, a coarser 3 × 3 k-point grid was used throughout the potential energy surface scan calculations. The def2-SVP basis set was used throughout.

[0068] The bilayer minima identified from the potential energy surface were refined by geometry optimization using the def2-TZVP basis set and a 9 × 9 k-point grid. Similarly, selected binding site supercell structures were optimized using def2-SVP and a 9 × 9 k-point grid. Final binding energies for all structures were calculated, also using def2-TZVP, with a finer 17 × 17 k-point grid.

[0069] SAED Simulation Lattice parameters and bond lengths were obtained from DFT calculations (see above) and previously published computational studies. SAED and PXRD simulations were performed using the CrystalMaker software suite. A model of a single γ-graphene sheet was constructed in CrystalMaker using a hexagonal P6 lattice with parameters a and c set to 6.86 Å and 3.4 Å, respectively. The asymmetric unit contained four atoms positioned at 0.208, 0.412, 0.589, and 0.795 along the hexagonal P6 x axis. Basic models corresponding to various sheet stacking modes were constructed using Vesta.

[0070] small molecule synthesis 1,3,5-tribromo-2,4,6-triiodobenzene [ka] The synthetic procedure for 1,3,5-tribromo-2,4,6-triiodobenzene was adapted from the literature. Periodic acid (41.03 g, 180 mmol) was added in small portions over 15 min to concentrated H2SO4 (500 mL) at room temperature. After dissolution of the periodic acid, ground KI (89.64 g, 540 mmol) was added in small portions over 1 h at 0 °C. To the resulting deep purple solution was added 1,3,5-tribromobenzene (18.89 g, 60.0 mmol) in small portions over 25 min at 0 °C. After stirring the solution at room temperature for 72 h, the resulting thick mixture was poured onto ice. The resulting precipitate was filtered and washed with HO (5 × 200 mL) and then MeOH (5 × 200 mL). The product was recrystallized twice from pyridine / EtOH 1:4 (1000 mL) to give a solid. The solid was dried under high vacuum for 1 day to give 1,3,5-tribromo-2,4,6-triiodobenzene 2 (28 g, 67%) as a pale yellow solid. Mp > 300 °C (decomposition); FTIR (neat) v = 1488, 1354, 1262, 1227, 1147, 1002, 858, 771, 739, 554, 508 cm -1 . 13C NMR (126 MHz, DMSO-d) δ 138.61 (CBr), 108.23 (CI). EI-MS fragmentation: m / z 695.5, 693.5, 691.5, 689.5, 567.6, 566.6, 565.6, 564.6, 439.7, 437.6. UV / vis (CHCl, C = 6.874 × 10 -5 M):λmax(ε)=227(5000), 248(27700), 283(5600M -1 cm -1 ).

[0071] ((2,4,6-tribromobenzene-1,3,5-triyl)tris(ethyne-2,1-diyl))tris(trimethylsilane) [ka] 1,3,5-Tribromo-2,4,6-triiodobenzene 2 (346 mg, 0.5 mmol), [PdCl(PPh)] (105 mg, 0.15 mmol, 30 mol%), CuI (19 mg, 0.1 mmol, 20 mol%), EtN (50 mL), and THF (40 mL) were added to a dry three-neck flask. Ethynyltrimethylsilane (736.7 mg, 1.07 mL, 7.5 mmol) and PhP (52 mg, 0.2 mmol, 40 mol%) were added to the mixture. The mixture was stirred at 80 °C for 48 h under argon. After removing the solvent on a rotary evaporator, DCM (100 mL) was added to the residue and filtered through Celite. The mixture was washed with water (20 mL) and NaCl(aq) (20 mL), dried over anhydrous NaSO, and the solvent was removed under reduced pressure. The residue was further purified by flash chromatography using n-hexane as the eluent to give ((2,4,6-tribromobenzene-1,3,5-triyl)tris(ethyne-2,1-diyl))tris(trimethylsilane) 3 as a white solid (175 mg, 0.29 mmol, 58% yield). Rf (hexane) = 0.3. Mp = 110-111 °C; FTIR (neat) ν = 2958, 2160, 1376, 1340, 1245, 1019, 834, 758, 708, 658, 633, 539 cm. -1 . 1H NMR (500MHz, CDCl3): δ=0.29ppm[s, 27H, Si(CH3)3]. 13 C NMR (126MHz, CDCl3): d 129.09(CBr), 127.49(C6C≡C), 106.79(C≡CSi), 101.83(C6C≡C), -0.23[Si(CH3)3]ppm. 29 Si NMR (99 MHz, CDCl3) δ -15.87 ppm. EI-MS fragmentation: m / z 603.9, 602, 601.9, 590.9, 589.9, 588.9, 588.9, 587.9, 586.9, 584.9. UV / vis (CHCl3, C = 5.436 × 10 -5 M):λmax(ε)=260(45700), 271(44600), 289(39600M -1 cm -1 ).

[0072] 1,3,5-tribromo-2,4,6-triethynylbenzene, TBTEB [ka] To a solution of ((2,4,6-tribromobenzene-1,3,5-triyl)tris(ethyne-2,1-diyl))tris(trimethylsilane) (151 mg, 0.25 mmol) in THF (15 mL) was added 0.55 mL of TBAF (75% aqueous solution, 1.5 mmol) and stirred at 0 °C for 15 min. The solution was then diluted with ethyl acetate, washed with distilled water, and dried over anhydrous Na2SO4. The solvent was removed on a rotary evaporator. The residue was further purified by flash chromatography using n-hexane as the eluent to give TBTEB as a white solid (84 mg, 0.216 mmol, yield: 87%). Rf (hexane) = 0.2. FTIR (neat) ν = 3275, 2922, 2112, 1519, 1368, 1336, 965, 736, 681, 634 cm -1 . 1 H NMR (500MHz, CDCl3): δ=5.16(s, 3H(C≡CH)ppm. 13C NMR (126 MHz, CDCl3): 129.90 (CBr), 126.33 (CC≡CH), 91.87 (C≡CH), 80.97 (CC≡CH) ppm. EI-MS fragmentation: m / z 390.8, 389.9, 388.8, 387.8, 386.8, 385.8, 384.8, 383.8. UV / vis (CHCl3, C = 4.136 × 10 -5 M):λmax(ε)=212(7100), 218(8300), 260(58100), 278nm(33500M -1 cm -1 ).

[0073] Synthesis of carbon materials [Table 1]

[0074] General synthetic procedures for carbon materials In a typical procedure, TBTEB, Pd(PPh3)4, and Cu were placed in a Schlenk tube under an argon atmosphere and solvent was added. The tube was sealed, and the contents were degassed by three freeze-pump-thaw cycles. The reaction mixture was stirred under an argon atmosphere and heated for 72 hours. The reaction mixture was concentrated on a rotary evaporator. The solid product was washed with methanol, ethanol, isopropanol, toluene, hexane, ethyl acetate, and acetone. The washing procedure involved dispersing the material in the corresponding solvent by gentle sonication, followed by centrifugation. Conditions for selected experiments from Table 1 are detailed below.

[0075] Table 1, entry 1 TBTEB (116 mg, 0.3 mmol), Pd(PPh3)4 (347 mg, 0.3 mmol), and CuI (4.6 mg, 0.024 mmol) were reacted in anhydrous pyridine (50 mL) using the general procedure. After centrifugation and drying at low vacuum (1-2 Torr) for 10 hours, the typical crude product mass was approximately 90% of the monomer mass (104 mg relative to the scale). After extensive drying at high vacuum (10 mTorr) and / or heating to 100 °C for 72 hours, the mass was reduced to approximately 60% of the original monomer mass (68 mg relative to the scale). TLC indicated quantitative monomer conversion.

[0076] Table 1, entry 2 TBTEB (116 mg, 0.3 mmol), Pd(PPh3)4 (347 mg, 0.3 mmol) and several pieces of copper foil were reacted in a mixture of anhydrous pyridine (50 mL) using the general procedure.

[0077] Table 1, entry 3 TBTEB (116 mg, 0.3 mmol) and Pd(PPh3)4 (347 mg, 0.3 mmol) were reacted in pyridine (50 mL) using the general procedure. No Cu was used.

[0078] Table 1, entry 4 TBTEB (116 mg, 0.3 mmol) was refluxed in pyridine (50 mL). Neither Pd(PPh3)4 nor copper was used.

[0079] TBTEB was synthesized according to a reported procedure. Its reactivity was then screened under various conditions (Table 1). In the absence of a catalyst, TBTEB decomposed in refluxing pyridine with a half-life of approximately 24 h, yielding an amorphous carbonaceous material (Figure 22). X-ray photoelectron spectroscopy (XPS) studies showed moderate loss of Br due to spontaneous hydrodebromination (Figures 15 and 17D). In the presence of Pd(PPh3)4 (Figure 21), a similar featureless carbon was produced, albeit with a larger loss of Br (Figures 14 and 17C).

[0080] Experiments performed in the presence of both Pd and Cu yielded results dependent on the state of the metals. The Pd(II) precatalyst, PEPPSI®-IPr, which we selected for its propensity for multisite coupling, yielded amorphous carbon broadly comparable to the control product. However, with stoichiometric loading of Pd(PPh3)4 in the presence of Cu foil, we obtained a shiny black material (Figure 18B). Transmission electron microscopy (TEM) images of this material revealed flakes consisting of stacks of planar sheets (Figure 20). The layered morphology was confirmed by scanning electron microscopy (SEM) images of the flakes (Figure 24). Despite well-defined layers, no Moire pattern was observed in the TEM. Selected-area electron diffraction (SAED) experiments produced a dotted ring pattern (Figures 20E–F), indicating submicron crystalline domains with random orientation.

[0081] A more crystalline product was obtained with the optimized homogeneous Pd(PPh3)4 / CuI protocol, which allowed for efficient removal of contaminants. XPS investigation of this product showed levels of Pd and P contamination that were below the detection limit of the technique (Figure 12). We acquired high-resolution XPS data for the C1s region of this material (Figure 2D), as well as for three controls: the Cu foil synthesis, the product of the Pd-only reaction, and the thermal reaction product (Figure 12). The C1s peak corresponds to the C-H (terminal alkyne sp 1 ), C≡C(internal alkyne sp 1 ), C=C(aromatic sp 2 The peaks can be deconvoluted into five subpeaks corresponding to the aromatic C-Br, C=O, and C=O carbons. The C=O contribution is negligible in all samples, indicating little to no oxidation under reducing / anaerobic reaction conditions. 1 Without the contribution of the subpeaks, none of the fits converge, which strongly supports the presence of acetylene bonds in all products. XPS revealed that sp 1 vs. SP 2The π-π ratio at 290 eV is consistent with γ-graphene. This ratio is much higher than the control sample (Figure 16B-D), due to extensive side reactions and contamination by aromatic impurities. * The "shake-up" peak is commonly observed in the XPS of graphitic carbon and graphene, as well as small aromatic molecules. Notably, this peak does not appear in the XPS of graphite dyes. The "shake-up" feature is negligible in the product of the homogeneous Cu protocol (Figure 2D), strongly suggesting that this material is not graphitic. The peak is prominent in the P-contaminated control product (Figures 13, 14, and 16C-D), indicating that it may be related to adsorbed PPh3.

[0082] We further investigated the structure and symmetry of the crystals using electron diffraction. The spot SAED patterns of the products obtained with the Pd(PPh3)4 / CuI protocol were remarkably clear and consistent across different regions of the sample, independent of the size or presence of a selected-area aperture. The near-perfect uniformity of the patterns indicated that the material was composed of crystalline domains large enough to span the entire illuminated area of ​​our typical imaging frame of 2 × 2 μm (Figures 2B and 19), indicating a crystalline domain size of at least 1–3 μm. The diffraction pattern observed from a flat area of ​​the sample had perfect hexagonal symmetry (Figure 3B). Using interatomic distances calculated by DFT, we constructed models for several plausible stacking modes of γ-graphene. Using these models, we simulated electron diffraction for c-, b-, and intermediate crystal orientations up to approximately 45° relative to the (0001) pole (Figure 25). The simulated c-orientation pattern is related only to spacing in the basal plane (Figures 24C and 24D). The first and second order reflections in the experimental diffraction pattern correspond to d-spacings of 5.96 Å and 3.44 Å, which are in perfect agreement with the theoretically calculated spacings for the (10 0) and (11 0) plane sets of γ-graphene (Figures 3B and 3D). Both of these distances are partially determined by the length of the acetylene bond. Some of the more symmetric space groups, such as Cmcm and R3m, are expected to produce diffraction patterns with systematic defects. Since the observed diffraction patterns did not have such systematic defects, these space groups could be conclusively eliminated.

[0083] Additional SAED patterns were acquired at different sample orientations. The initial stage position was chosen to obtain the most symmetric spot intensity distribution, corresponding to a beam perpendicular to the basal plane and aligned with the a-axis. The sample was then rotated around the b-axis. As the sample rotation reached approximately 45°, diffraction patterns related to z-spacing began to emerge. The experimental diffractogram at this orientation provided a group of closely spaced spots (Figure 3C), suggesting layer stacking defects. Such defects did not appear in the c-orientation diffractogram, because stacking modes only affect reflections related to z-spacing (Figure 26). The symmetry of the pattern is consistent with our simulations for this intermediate orientation (Figures 25E, 25F, and 25H). Since no systematic defects were observed, we can rule out some of the more symmetric space groups, most notably the P63mc space group. The experimental diffraction patterns were most consistent with either less symmetric stacking modes, such as P3112 (Figure 25E), or aperiodic superlattices. It is important to note that despite their multi-spot nature, the observed diffractograms do not exhibit turbostratic stacking, which would produce a ring pattern. Shape factor effects alter the geometry of the diffracted beam, which introduces errors into the determination of the spot center. However, modeling indicates that the alternating sample orientation diffractograms are consistent with an interlayer spacing of approximately 3.5 Å.

[0084] Our data indicate that the material we synthesized is multilayer γ-graphene. Contrary to expectations, we found that an external template was not necessary to synthesize highly crystalline γ-graphene. Even in our reactions performed using Cu foils, there is no experimental evidence that polymerization occurs on the surface. The lower crystallinity of the Cu foil product is likely due to the reduced concentration of catalytic Cu species in solution. This results in a slower Sonogashira coupling and a higher degree of side reactions compared to the homogeneous Pd(PPh3)4 / CuI protocol.

[0085] We sought to understand why TBTEB preferentially polymerizes into multilayer γ-graphene flakes, as opposed to amorphous branched structures. Because polymerization appears to be self-templating, we hypothesized the existence of attractive supramolecular interactions between TBTEB and the γ-graphene lattice. Self-assembly by solvophobically driven π-stacking has been demonstrated for several phenylene ethynylene oligomers and macrocycles structurally related to graphene. To investigate possible supramolecular interactions in our system, we used DFT to calculate the structure and potential energy surface for a single TBTEB molecule bound to a γ-graphene monolayer. Our calculations predict that TBTEB associates with the graphene surface at two types of binding sites (around the aromatic ring and on the 12-DBA ring) with binding energies exceeding 20 kcal / mol (Figure 27). The monomer species outcompetes toluene, whose binding energy we estimate to be approximately 11 kcal / mol. If all TBTEB species were to react while bound on the γ-graphine underlayer, one of many local energy minimum stackings, or a mixture of stackings, would result.

[0086] To our knowledge, our synthesis of γ-graphene is the first example of a naturally formed, ordered covalent lattice under purely kinetic control. Typical covalent organic frameworks and metal-organic frameworks are held together through reversible bonds. This reversibility is thought to be important for continuous error correction during the reaction / crystallization process. Conventional thinking predicts that irreversible polymerization of A3B3-type monomers would not impose strict geometric constraints on reactivity and would only yield irregularly branched structures. However, because we routinely observe micron-scale γ-graphene crystallites, crystallization-assisted 2D polymerization must currently be kinetically favored over random 3D growth. Furthermore, the initial nucleation of flat graphene sheets appears to be a high-probability event. The high fidelity of the resulting lattice indicates that the system is capable of error correction, despite the irreversibility of the Sonogashira coupling. At a minimum, the reaction must proceed equally well at both the lattice edges and at internal defect sites. Because the "patching" of a single internal defect requires the formation of six new chemical bonds, these bond-forming steps are likely kinetically coupled. The apparent ability to correct for errors, as well as the strong dependence of product structure on the nature of the Pd precatalyst, strongly support our original hypothesis of a multisite coupling mechanism.

[0087] From the above description of the invention, those skilled in the art will perceive improvements, changes, and modifications. Such improvements, changes, and modifications within the scope of the art are intended to be covered by the appended claims. All references, publications, and patents cited in this application are hereby incorporated by reference in their entirety.

Claims

1. A method comprising synthesizing a covalent lattice based on an irreversible bond-forming reaction that favors complete substitution on a multifunctional substrate.

2. 2. The method of claim 1, wherein the bond-forming reaction is a Sonogashira cross-coupling reaction between a terminal alkyne and an aryl halide.

3. 3. The method of claim 2, wherein the reactant is any of the possible 1,3,5-trihalo-2,4,6-triethynylbenzenes (either symmetrical or unsymmetrical) and the halogen is either Cl, Br, or I.

4. 3. The method of claim 2, wherein the reactant is any of the possible ((2,4,6-trihalobenzene-1,3,5-triyl)tris(ethyne-2,1-diyl))tris(trimethylsilane)s (either symmetrical or unsymmetrical) and the halogen is either Cl, Br, or I.

5. The method according to any one of claims 2 to 4, wherein the Sonogashira cross-coupling reaction is carried out using a palladium catalyst, and the type of palladium source is selected from the following: palladium on black, palladium on carbon, palladium (π-cinnamyl) chloride dimer, bis(triphenylphosphine)palladium(II) dichloride, bis(benzonitrile)palladium(II) chloride, bis(triphenylphosphine)palladium(II) diacetate, tetrakis(triphenylphosphine)palladium(0), bis(dibenzylideneacetone)palladium(0), tris(dibenzylideneacetone)dipalladium(0), dichlorobis(tricyclohexylphosphine)palladium(II), dichlorobis(tri-o-tolyl ... (1,3-bis(2,6-diisopropylphenyl)imidazolidene)(3-chloropyridyl)palladium(II) dichloride, (1,3-bis(2,6-dimethylphenyl)imidazolidene)(3-chloropyridyl)palladium(II) dichloride, [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene](3-chloropyridyl)palladium(II) dichloride, palladium(II) 2,4-pentanedionate, or any of the possible alkali metal salts of tris(3,3',3"-phosphinidinetris(benzenesulfonato)palladium(0).

6. The method of any of claims 2 to 5, wherein the Sonogashira cross-coupling reaction is carried out using a copper co-catalyst, and the copper co-catalyst is selected from the following: copper(I) iodide, copper(I) chloride, copper(I) bromide, tetrakis(acetonitrile)copper(I) hexafluorophosphate, tetrakisacetonitrilecopper(I) triflate, copper(0) foil or turnings in combination with pyridine, copper(0) foil or turnings in combination with any aliphatic tertiary amine, or copper(II) sulfate in combination with sodium ascorbate.

7. 7. The method of claim 6, wherein the reactants, palladium catalyst, and copper co-catalyst are provided in a solvent, the solvent being selected from pyridine, tetrahydrofuran, a mixture of tetrahydrofuran and N,N-diisopropylethylamine, toluene, benzene, water, or a biphasic mixture of water and an immiscible organic solvent.

8. 8. The method of claim 7, wherein the loading of the Pd catalyst is 0.5 mol% to 120 mol% relative to the 1,3,5-trihalo-2,4,6-triethynylbenzene monomer.

9. The method according to claim 7 or 8, wherein the loading of the Cu co-catalyst is 0.1 mol% to 10 mol% relative to the 1,3,5-trihalo-2,4,6-triethynylbenzene monomer.

10. The method according to any one of claims 1 to 9, wherein the reaction temperature is from 60°C to 130°C.

11. 11. The method of claim 4, wherein the reaction conditions are any of those listed in claims 5 to 10, and the reaction is carried out in the presence of a soluble fluoride salt.

12. The method of any of claims 1 to 11, wherein the ordered two-dimensional polymerization occurs without a physical substrate or added template.

13. The covalent bond lattice is carbon sp ２ / sp １ The method of any one of claims 1 to 12, comprising allotropes.

14. The method of any preceding claim, wherein the covalent lattice comprises graphene.

15. The method of any preceding claim, wherein the covalent lattice comprises γ-graphene.

16. The method according to any of claims 1 to 15, wherein a multilayer γ-graphene is obtained in which the linear size of the crystalline domains ranges from 10 nanometers to 500 micrometers.

17. The method according to any of claims 1 to 16, wherein few layer (1-25 layers) gamma-graphene is obtained with the linear size of the crystalline flakes ranging from 10 nanometers to 500 micrometers.

18. The method involves synthesizing covalent lattices based on irreversible bond-forming reactions that favor complete substitution on multifunctional substrates, where ordered two-dimensional polymerization occurs without a physical substrate or added template.

19. 19. The method of claim 18, wherein the bond-forming reaction is a Sonogashira cross-coupling reaction between a terminal alkyne and an aryl halide.

20. 20. The method of claim 19, wherein the reactant is any of the possible 1,3,5-trihalo-2,4,6-triethynylbenzenes (either symmetrical or unsymmetrical) and the halogen is either Cl, Br, or I.

21. 20. The method of claim 19, wherein the reactant is any of the possible ((2,4,6-trihalobenzene-1,3,5-triyl)tris(ethyne-2,1-diyl))tris(trimethylsilane)s (either symmetrical or unsymmetrical) and the halogen is either Cl, Br, or I.

22. The method according to any one of claims 19 to 21, wherein the Sonogashira cross-coupling reaction is carried out using a palladium catalyst, and the type of palladium source is selected from the following: palladium on black, palladium on carbon, palladium (π-cinnamyl) chloride dimer, bis(triphenylphosphine)palladium(II) dichloride, bis(benzonitrile)palladium(II) chloride, bis(triphenylphosphine)palladium(II) diacetate, tetrakis(triphenylphosphine)palladium(0), bis(dibenzylideneacetone)palladium(0), tris(dibenzylideneacetone)dipalladium(0), dichlorobis(tricyclohexylphosphine)palladium(II), dichlorobis(tri-o-tolylphosphine), (1,3-bis(2,6-diisopropylphenyl)imidazolidene)(3-chloropyridyl)palladium(II) dichloride, (1,3-bis(2,6-dimethylphenyl)imidazolidene)(3-chloropyridyl)palladium(II) dichloride, [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene](3-chloropyridyl)palladium(II) dichloride, palladium(II) 2,4-pentanedionate, or any of the possible alkali metal salts of tris(3,3',3"-phosphinidinetris(benzenesulfonato)palladium(0).

23. 23. The method of any of claims 19 to 22, wherein the Sonogashira cross-coupling reaction is carried out using a copper co-catalyst, the copper co-catalyst being selected from copper(I) iodide, copper(I) chloride, copper(I) bromide, tetrakis(acetonitrile)copper(I) hexafluorophosphate, tetrakisacetonitrilecopper(I) triflate, copper(0) foil or turnings in combination with pyridine, copper(0) foil or turnings in combination with any aliphatic tertiary amine, or copper(II) sulfate in combination with sodium ascorbate.

24. 24. The method of claim 23, wherein the reactants, palladium catalyst, and copper co-catalyst are provided in a solvent, the solvent being selected from pyridine, tetrahydrofuran, a mixture of tetrahydrofuran and N,N-diisopropylethylamine, toluene, benzene, water, or a biphasic mixture of water and an immiscible organic solvent.

25. 25. The method of claim 24, wherein the loading of the Pd catalyst is 0.5 mol% to 120 mol% relative to the 1,3,5-trihalo-2,4,6-triethynylbenzene monomer.

26. 26. The method of claim 24 or 25, wherein the loading of the Cu co-catalyst is 0.1 mol% to 10 mol% relative to the 1,3,5-trihalo-2,4,6-triethynylbenzene monomer.

27. The method according to any one of claims 18 to 26, wherein the reaction temperature is from 60°C to 130°C.

28. 22. The method of claim 21, wherein the reaction conditions are any of those recited in claims 22 to 27, and the reaction is carried out in the presence of a soluble fluoride salt.

29. The covalent bond lattice is carbon sp ２ / sp １ 30. The method of any one of claims 18 to 29, comprising an allotrope.

30. The method of any of claims 18 to 30, wherein the covalent lattice comprises graphene.

31. The method of any of claims 18 to 30, wherein the covalent lattice comprises γ-graphene.

32. The method according to any of claims 18 to 31, wherein a multilayer γ-graphene is obtained in which the linear size of the crystalline domains ranges from 10 nanometers to 500 micrometers.

33. A method according to any of claims 18 to 32, wherein few layer (1-25 layer) gamma-graphene is obtained, with the linear size of the crystalline flakes ranging from 10 nanometers to 500 micrometers.

34. Graphene prepared by the process of any of claims 1 to 33.

35. 35. The graphene of claim 34, having substantially perfect crystalline uniformity and / or substantially perfect hexagonal symmetry.

36. 36. The graphene of claim 35, having minimal or no crystalline defects.

37. In the crystalline material, sp １ vs sp ２ 36. The graphene of claim 35 having a 1:1 ratio of carbon to silicon.

38. γ-graphene, in which the linear size of the crystalline domains ranges from 10 nanometers to 500 micrometers.

39. 39. The γ-graphene of claim 38, comprising multifunctional reactive groups on the edges of the γ-graphene.

40. γ-graphene according to claim 38, wherein the multifunctional reactive groups are selected from alkyne and halo groups.

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