Gamma-graphyne and methods of fabrication

Abstract

A method includes synthesizing covalently bonded lattices based on irreversible bond-making reactions which favor exhaustive substitution on multi-functional substrates, wherein the irreversible bond-making reactions include ordered two-dimensional interfacial polymerizations of a monomer at a liquid / liquid interface, liquid-solid interface, or liquid-gas interface.

Description

y-GRAPHYNE ND METHODS OF F BRICATIONRELATED APPLICATION

[0001] This application claims priority from U.S. Provisional Application No. 63 / 509,957, filed June 23, 2023 and 63 / 511,220, filed June 30, 2023, the subject matter of which are incorporated herein by reference in their entirety.GOVERNMENT FUNDING

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

[0003] The discovery and development of new materials have the potential of developing entirely new subfields of science. Since the stability of individual sheets of graphene has been established in 2004, research efforts on 2D carbon materials have grown exponentially due to the fascinating mechanical and electronic properties of these materials. Most of the efforts have been focused on carbon structures comprised of sp2-hybridized tricoordinate carbon atoms. However, there has been growing interest in the synthesis of carbon allotropes containing sp1-hybridized acetylenic carbons, such as graphdiyne and y- graphyne. y-Graphyne can be described as graphene uniformly expanded through insertion of two-carbon acetylenic units between all the aromatic rings.

[0004] This material was first predicted by Baughman et al. in 1987, and first experimentally obtained in 2022 (Baughman et al. Structure -property predictions for new planar forms of carbon: Layered phases containing sp2 and sp atoms. J. Chem. Phys. 1987, 87 (11), 6687-6699). However, this synthetic method used a homogenous approach to synthesize graphyne, which causes a number of issues: (1) relying on self-association of the monomer to a small y-graphyne subunit to template the lateral growth of the material can result in inconsistencies of the material quality and yield between reactions; (2) the thickness and sheet size is difficult to control; (3) significant palladium loading leads to contamination and difficult to fully remove from the resulting material; and (4) high temperature and long reaction times can lead to side reactions and degradation of the resulting material as seen with the reported thermolytic control.SUMMARY

[0005] Embodiments described herein relate to a method of synthesizing covalently bonded lattices based on irreversible bond-making reactions which favor exhaustive substitution on multi-functional substrates and, particularly, relate to a method of preparing multilayer y-graphync, a sp2 / sp1allotrope of carbon.

[0006] In some embodiments, the method of synthesizing covalently bonded lattices based on irreversible bond-making reactions can include ordered two-dimensional interfacial polymerizations of a monomer at a liquid / liquid interface, liquid-solid interface, or liquid-gas interface.

[0007] In some embodiments, the ordered two-dimensional interfacial polymerizations occur in the absence of a physical substrate or added template.

[0008] In some embodiments, the interfacial polymerization can include a Sonogashira cross-coupling reaction between a terminal alkyne and an aryl halide.

[0009] In some embodiments, the monomer is a l,3,5-trihalo-2,4,6-triethynylbenzene monomer, either symmetric or unsymmetric, dissolved in an organic solvent.

[0010] In some embodiments, the Sonogashira cross-coupling reaction can be performed using a palladium precatalyst, which is soluble in an organic phase and insoluble in an aqueous phase. The precatalyst can be selected from tetrakis(tripheny Iphosphine)palladium(O) , bis(dibenzylideneacetone)palladium(0) , tris(dibenzylideneacetone)dipalladium(0), dichlorobis(tricyclohexylphosphine)palladium(ll), dichlorobis(tri-o-tolylphosphine)palladium(II), (l,3-bis(2,6-diisopropylphenyl)imidazolidene) ( 3 -chloropyridyl) palladium(II) dichloride, (l,3-bis(2,6-dimethylphenyl)imidazolidene) ( 3- chloropyridyl) palladium(II) dichloride, or [l,3-bis(2,6-diisopropylphenyl)imidazol-2- ylidene](3-chloropyridyl)palladium(II) dichloride.

[0011] In other embodiments, the Sonogashira cross-coupling reaction is performed using a palladium precatalyst which is soluble in the aqueous phase and insoluble in the organic phase. The precatalyst can be selected from any of the possible alkali metal salts of sulfonated phosphine complexes of palladium (0), where the sulfonated phosphine ligand is any of Ttriphenylphosphine-3,3',3''-trisulfonate, bis(p-sulfonatophenyl)phenylphosphine, (p- sulfonatophenyl)diphenylphosphine or the ligands can be any of (2-di-t-butylphospinoethyl)trimethylammonium chloride or 4-(di-t-butylphospino)-N,N- dimethylpiperidinium chloride.

[0012] In some embodiments, the Sonogashira cross-coupling reaction can be performed using a copper co-catalyst. The copper co-catalyst can be selected from copper(I) iodide, copper(I) chloride, copper(I) bromide, tetrakis(acetonitrile)copper(l) hexafluorophosphate, tetrakis acetonitrile copper(I) triflate, copper(O) foil or shavings combined with pyridine, copper(O) foil or shavings combined with any aliphatic tertiary amine or acetonitrile, or copper(II) sulfate combined with sodium ascorbate.

[0013] In some embodiments, the copper co-catalyst is soluble in the aqueous phase and insoluble in the organic phase.

[0014] In other embodiments, the monomer can be provided in the organic phase and a water soluble palladium catalyst and water soluble copper co-catalyst can be provided in the aqueous phase. The organic phase can overly the aqueous phase during interfacial polymerization of the monomer.

[0015] In some embodiments, the organic phase includes the monomer dissolved in hexane, and the aqueous phase includes a mixture of water soluble palladium catalyst, water soluble copper co-catalyst, water, and optionally acetonitrile or pyridine.

[0016] In some embodiments, the covalently bonded lattices include sp2 / sp1allotropes of carbon.

[0017] In some embodiments, monomer concentration and optionally separation of catalysts from the monomer during the two-dimensional interfacial polymerizations is effective to synthesize substantially crystalline covalently bonded lattices with minimal to no defects.

[0018] In other embodiments, the covalently bonded lattices include y-graphyne.

[0019] In some embodiments, the method yields multilayer y-graphyne with linear size of crystalline domains in the range of about 10 nanometers to about 10 millimeters.

[0020] In other embodiments, the method yields few-layer (1-30 layers) y-graphyne with linear size of crystalline flakes in the range of about 10 nanometers to about 10 millimeters.

[0021] Other embodiments described herein relate to y-graphyne formed by interfacial polymerization.

[0022] In some embodiments, the y-graphyne is formed by interfacial polymerization of a first mixture of a l,3,5-trihalo-2,4,6-triethynylbenzene monomer, either symmetric or unsymmetric, dissolved in an organic phase and a second mixture of a water soluble copper catalyst and optionally a water soluble palladium catalyst in an aqueous phase.

[0023] In some embodiments, the interfacial polymerization can include a Sonogashira cross-coupling reaction.

[0024] In some embodiments, the y-graphyne can have linear size crystalline domains in the range of about 10 nanometers to about 10 millimeters.

[0025] In other embodiments, the y-graphyne can have few-layer (1-30 layers) with linear size crystalline flakes in the range of about 10 nanometers to about 10 millimeters.

[0026] Still other embodiments described herein relate to a method of exfoliating y-graphyne layers from a y-graphyne multilayer flake. The method includes chemically modifying sheet edges of a y-graphyne multilayer flake to introduce terminal groups on the sheet edges that enhance dispersibility and / or solubility of the y-graphyne sheets in a solvent. The chemically modified y-graphyne multilayer flake can then be added to the solvent. The chemically modified y-graphyne multilayer flake added to the solvent can be agitated to exfoliate individual the y-graphyne layers from the chemically modified y-graphyne multilayer flake.

[0027] In some embodiments, the sheet edges of the y-graphyne multilayer flake prior to chemical modification include terminal halide and / or alkyne groups. The terminal halide groups and / or alkyne groups can be chemically modified to organic groups that enhance the dispersibility and / or solubility of the y-graphyne multilayer flake.

[0028] In some embodiments, the terminal halide groups can be chemically modified to the organic groups by a Sonogashira coupling reaction. For example, the terminal halide groups can be chemically modified to phenylethynyl groups, 2-ethynyl-6- methoxynaphthalene groups, alkylethynyl groups with the number of saturated carbons between about 4 and about 20, or prop-2-yn-l-yloxy-(poly(ethylene glycol)) groups with the number of ethylene glycol repeat units between about 5 and about 250, by a Sonogashira coupling reaction.

[0029] In other embodiments, the terminal alkyne groups can be chemically modified to 1,4-disubstituted 1,2,3-triazole groups by a copper-catalyzed azide alkyne cycloaddition reaction. The substituent on the 4-position of the 1,2,3-triazole group can be any of: alkylwith a number of saturated carbons between about 8 and about 20; phenyl or substituted phenyl; naphthyl or substituted naphthyls; benzyl or benzyl with substitution on the aromatic ring; or poly (ethylene glycol) with the number of ethylene glycol repeat units between 5 and 250.

[0030] In some embodiments, the solvent can include hexane, benzene, toluene, xylene, dimethylformamide, N-methylpyrrolidone, methanol, ethanol, n-propanol, isopropanol, acetone, water, or mixtures thereof.

[0031] In some embodiments, the chemically modified y-graphyne multilayer flake can be mechanically agitated in the solvent to exfoliate the y-graphyne layers. The mechanical agitation can include, for example, ultrasound, magnetic stirring, or direct mechanical mixing.

[0032] In some embodiments, the exfoliated y-graphyne layers have a thickness less than about 10 nm, preferably less than about 1 nm.

[0033] Still other embodiments relate to a method for dispersing multilayer y-graphyne synthesized by the methods described herein. The dispersant solvent can be any of N,N- dimethylformamide or N-methylpyrrolidone, and the dispersion is achieved either by ultrasonic processing or mechanical mixing.BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Fig. 1 illustrates a schematic showing liquid / liquid interfacial-assisted Sonogashira polymerization of an A3B3-type monomer, l,3,5-tribromo-2,4,6- triethynylbenzene (TBTEB) results in extended thin layers of y-graphyne.

[0035] Figs. 2(A-D) illustrate: (A) a schematic showing liquid / liquid interfacial-assisted Sonogashira polymerization with an upper organic layer consisting of n-hexanes, TBTEB, and tetrakis-(triphenylphosphine) palladium(O) and a lower aqueous layer consisting of a mixture of distilled water, triethylamine, and Cui; (B) images of a film formed at the interface; and (C-D) scanning electron microscopy (SEM) images of the film.

[0036] Figs. 3(A-F) illustrate: (A-E) TEM images of film of Fig. 2 and (F) a schematic of y-graphyne structure.

[0037] Figs. 4(A-D) illustrate: (A) a schematic showing liquid / liquid interfacial-assisted Sonogashira polymerization with an upper organic layer consisting of n-hexanes and TBTEB, and a lower aqueous layer consisting of mixture of palladium(O) 3, 3', 3"- phosphanetriyltris(benzenesulfonic acid) trisodium salt (Pd(O)TPPTS), acetonitrile / distilled water, and Cui; (B- C) TEM images of a film generated by the polymerization; and (D) a schematic of y- graphyne structure.

[0038] Figs. 5(A-B) illustrate the synthesis and derivatization of y-graphyne. (A) Synthesis of Br-edge y-graphyne (GY-Br) through 2D polymerization of TBTEB. (B) Elaboration of GY-Br sheet edges through the CuAAC and Sonogashira reactions.

[0039] Figs. 6(A-B) illustrate IR signatures and dispersibility of functionalized graphynes. (A) ATR-FTIR spectra of each powder (Ge crystal). The internal alkyne signal at 2200 cm'1(grey dotted line) is retained after edge modification. (B) Dispersions of each of the functionalized graphynes in n-heptane.

[0040] Figs. 7(A-D) illustrate TEM images and electron diffraction of edge- functionalized y-graphyne materials. (A) GY-C18 after 2 minutes of sonication at low power in hexanes. (B) The same GY-C18 after an additional 30 min of sonication. Only amorphous carbon is visible. (C) A multilayer flake of GY-Ph. (D) SAED pattern for the flake in D (white) overlaid with the simulated diffraction pattern (red) for R3m-stacked y-graphyne. “+” signs indicate systematic absences.

[0041] Figs. 8(A-F) illustrate atomic force microscopy of exfoliated flakes of y- graphyne. (A) Phase and (B) height micrographs of GY-C18N3. (C) Height profile along the white line in B. (D) Phase and (E) Height micrographs of GY-Ph. (F) Height profile along the white line in E. Phase and height profiles of the highlighted region show that the flakes are harder than mica and have a height under 1 nm.DETAILED DESCRIPTION

[0042] All scientific and technical terms used in this application have meanings commonly used in the art unless otherwise specified. The definitions provided herein are to facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of the application.

[0043] 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.

[0044] As used herein, the verb “comprise” as is used in this description and in the claims and its conjugations are used in its non-limiting sense to mean that items following theword are included, but items not specifically mentioned are not excluded. The present invention may suitably “comprise”, “consist of’, or “consist essentially of’, the steps, elements, and / or reagents described in the claims.

[0045] Throughout the description, where compositions are described as having, including, or comprising, specific components, it is contemplated that compositions also consist essentially of, or consist of, the recited components. Similarly, where methods or processes are described as having, including, or comprising specific process steps, the processes also consist essentially of, or consist of, the recited processing steps. Further, it should be understood that the order of steps or order for performing certain actions is immaterial so long as the compositions and methods described herein remains operable. Moreover, two or more steps or actions can be conducted simultaneously.

[0046] The term “A and / or B” means “A or B, or A and B”.

[0047] As used herein, the term "about" or "approximately" refers to a quantity, level, value, number, frequency, percentage, dimension, size, amount, weight or length that varies by as much as 15%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2% or 1% to a reference quantity, level, value, number, frequency, percentage, dimension, size, amount, weight or length. In one embodiment, the term "about" or "approximately" refers a range of quantity, level, value, number, frequency, percentage, dimension, size, amount, weight or length + 15%, + 10%, + 9%, ± 8%, ± 7%, ± 6%, ± 5%, ± 4%, ± 3%, ± 2%, or + 1% about a reference quantity, level, value, number, frequency, percentage, dimension, size, amount, weight or length.

[0048] Throughout this disclosure, various aspects of this invention can be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual and partial numbers within that range, for example, 1, 2, 3, 4, 5, 5.5 and 6. This applies regardless of the breadth of the range.

[0049] Embodiments described herein relate to a method of synthesizing covalently bonded lattices based on irreversible bond-making reactions which favor exhaustive substitution on multi-functional substrates and, particularly, relate to a method of preparingmultilayer y-graphyne, a sp2 / sp' allotrope of carbon. We found that under appropriate conditions a multifunctional l,3,5-trihalo-2,4,6-triethynylbenzene monomer (TBTEB) can be polymerized by liquid / liquid interfacial-assisted Sonogashira polymerization to thin, crystalline, and extended y-graphyne sheets as large as >10 pm and as thin as a few nanometers. Two immiscible liquids can be used to separate catalysts and / or monomer used for a Sonogashira coupling reaction and drive the reaction to primarily occur at a liquid / liquid interface. By way of example, an aqueous phase containing a catalyst can be charged into a round-bottom flask, which is then charged with an organic phase including TBTEB and optionally another catalyst to form the organic / aqueous interface. The mixture can then be heated for a duration of time effective to produce y-graphyne at the interface.Advantageously, the reaction conditions we employed favored exhaustive coupling of the multifunctional TBTEB to better template and control the growth of y-graphyne to a larger and more extended structure than what has previously been obtained.

[0050] Accordingly, a method of synthesizing covalently bonded lattices based on irreversible bond-making reactions can include ordered two-dimensional interfacial polymerizations of a monomer at a liquid / liquid interface, liquid-solid interface, or liquid-gas interface.

[0051] In some embodiments, the ordered two-dimensional interfacial polymerizations occur in the absence of a physical substrate or added template. Such a physical substrate or added template could potentially include a metal foil, fiber, or particle that defines a surface on which polymerization could occur.

[0052] In some embodiments, the interfacial polymerization can include a Sonogashira cross-coupling reaction between a terminal alkyne and an aryl halide of the monomer. Each of the terminal alkyne groups is capable of cross-coupling via the Sonogashira cross-coupling reaction with a halogen group of the aryl halide, thereby forming a network of such reactants linked by acetylene groups.

[0053] In some embodiments, the monomer can be a l,3,5-trihalo-2,4,6- triethynylbenzene monomer, either symmetric or unsymmetric, dissolved in an organic solvent. The halogen can include, for example, Cl, Br, or I. For example, the trihalotriethynylbenzene can be l,3,5-tribromo-2,4,6-triethynylbenzene.

[0054] In other embodiments, the monomer for synthesizing the covalently bonded lattice can be any of the possible ((trihalobenzenetriyl)tris(ethynediyl))tris(trimethylsilanes),either symmetric or unsymmetric, where the halogen is any of 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).

[0055] In some embodiments, the Sonogashira cross-coupling reaction can be performed using a palladium precatalyst that is soluble in the organic phase and insoluble in the aqueous phase. The precatalyst can be selected from tetrakis(triphenylphosphine)palladium(0) , bis(dibenzylideneacetone)palladium(0) , tris(dibenzylideneacetone)dipalladium(0), dichlorobis(tricyclohexylphosphine)palladium(II), dichlorobis(tri-o-tolylphosphine)palladium(II), (l,3-bis(2,6-diisopropylphenyl)imidazolidene) ( 3 -chloropyridyl) palladium(II) dichloride, (l,3-bis(2,6-dimethylphenyl)imidazolidene) ( 3- chloropyridyl) palladium(II) dichloride, or [l,3-bis(2,6-diisopropylphenyl)imidazol-2- y lidene] (3 -chloropyridyl)palladium(II) dichloride.

[0056] In other embodiments, the Sonogashira cross-coupling reaction can be performed using a palladium precatalyst that is soluble in the aqueous phase and insoluble in the organic phase. The precatalyst can be selected from any of the possible alkali metal salts of sulfonated phosphine complexes of palladium (0), where the sulfonated phosphine ligand is any of triphenylphosphine-3,3',3''-trisulfonate, bis(p-sulfonatophenyl)phenylphosphine, (p- sulfonatophenyl)diphenylphosphine or the ligands can be any of (2-di-t- butylphospinoethyl)trimethylammonium chloride or 4-(di-t-butylphospino)-N,N- dimethylpiperidinium chloride.

[0057] In some embodiments, the Sonogashira cross-coupling reaction can be performed using a copper co-catalyst. The copper co-catalyst can be selected from copper(I) iodide, copper(I) chloride, copper(I) bromide, tetrakis(acetonitrile)copper(I) hexafluorophosphate, tetrakis acetonitrile copper(I) triflate, copper(0) foil or shavings combined with pyridine, copper(0) foil or shavings combined with any aliphatic tertiary amine or acetonitrile, or copper(II) sulfate combined with sodium ascorbate.

[0058] In some embodiments, the copper co-catalyst is soluble in the aqueous phase and insoluble in the organic phase.

[0059] In other embodiments, the monomer can be provided in the organic phase and a water soluble palladium catalyst and water soluble copper co-catalyst can provided in the aqueous phase. The organic phase can overly the aqueous phase during interfacialpolymerization of the monomer so that catalysts in the aqueous phase settle to the bottom of the aqueous phase and not on top of the material formed at the interface.

[0060] In some embodiments, the organic phase includes the monomer dissolved in hexane and the aqueous phase includes a mixture of water soluble palladium catalyst, water soluble copper co-catalyst, water, and optionally acetonitrile or pyridine.

[0061] In some embodiments, monomer concentration and optionally separation of catalysts from the monomer during the two-dimensional interfacial polymerizations is effective to synthesize substantially crystalline covalently bonded lattices with minimal to no defects.

[0062] In some embodiments, loading of the Pd catalyst in the organic phase or aqueous phase can be between about 0.5 mol % and about 120 mol % relative to the monomer, e.g., l,3,5-trihalo-2,4,6-triethynylbenzene.

[0063] In other embodiments, loading of the Cu co-catalyst in the aqueous can be between about 0.1 mol % and about 10 mol % relative to the monomer, e.g., 1,3,5-trihalo- 2,4,6-triethynylbenzene in the organic phase.

[0064] In some embodiments, a reaction vessel, such as a round bottom flask, containing the organic and the aqueous phase can be heated to temperature and duration of time effective to produce the covalently bonded lattices and / or multilayer y-graphyne. In some embodiments, the reaction is performed at a reaction temperature of about 60°C to about 130°C and the duration time 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).

[0065] In some embodiments, the covalently bonded lattices include sp2 / sp1allotropes of carbon.

[0066] In other embodiments, the covalently bonded lattices include y-graphyne.

[0067] The as synthesized covalently bonded lattices and / or multilayer y-graphyne may be rinsed with suitable solvent such as ethanol for several times (e.g., 5 times) to remove any residuals left on the surface of the material.

[0068] In some embodiments, the method yields multilayer y-graphyne with linear size of crystalline domains in the range of about 10 nanometers to about 10 millimeters.

[0069] In other embodiments, the method yields few-layer (1-30 layers) y-graphyne with linear size of crystalline flakes in the range of about 10 nanometers to about 10 millimeters.

[0070] In some embodiments, the y-graphyne material may be applied in various applications, such as in electrochemical energy storage, manufacturing of electronic and / or photonic devices, rechargeable batteries, organic solar cells, extreme- strength composites, and catalysis.

[0071] Other embodiments described herein relate to y-graphyne formed by interfacial polymerization.

[0072] In some embodiments, the graphyne prepared by the interfacial polymerization can have substantially perfect crystal uniformity and / or substantially perfect hexagonal crystal symmetry with minimal to no defects.

[0073] In some embodiments, the graphyne can have a 1: 1 ratio of sp1to sp2carbons in the crystalline material.

[0074] In some embodiments, the y-graphyne is formed by interfacial polymerization of a first mixture of a l,3,5-trihalo-2,4,6-triethynylbenzene monomer, either symmetric or unsymmetric, dissolved in an organic phase and a second mixture of a water soluble copper catalyst and optionally a water soluble palladium catalyst in an aqueous phase.

[0075] In some embodiments, the interfacial polymerization can include a Sonogashira cross-coupling reaction.

[0076] In some embodiments, the y-graphyne can have linear size crystalline domains in the range of about 10 nanometers to about 10 millimeters.

[0077] In other embodiments, the y-graphyne can have few-layer (1-30 layers) with linear size crystalline flakes in the range of about 10 nanometers to about 10 millimeters.

[0078] Still other embodiments described herein relate to a method of exfoliating y- graphyne layers from a y-graphyne multilayer flake. The method includes chemically modifying sheet edges of a y-graphyne multilayer flake to introduce terminal groups on the sheet edges that enhance dispersibility and / or solubility of the y-graphyne sheets in a solvent. The chemically modified y-graphyne multilayer flake can then be added to the solvent. The chemically modified y-graphyne multilayer flake added to the solvent can be agitated to exfoliate individual y-graphyne layers from the chemically modified y-graphyne multilayer flake.

[0079] In some embodiments, the sheet edges of the y-graphyne multilayer flake prior to chemical modification include terminal halide and / or alkyne groups. The terminal halidegroups and / or alkyne groups can be chemically modified to organic groups that enhance the dispersibility and / or solubility of the y-graphyne multilayer flake.

[0080] In some embodiments, the terminal halide groups can be chemically modified to the organic groups by a Sonogashira coupling reaction. For example, the terminal halide groups can be chemically modified to phenylethynyl groups, 2-ethynyl-6- methoxynaphthalene groups, alkylethynyl groups with the number of saturated carbons between about 4 and about 20, prop-2-yn-l-yloxy-(poly(ethylene glycol)) groups with the number of ethylene glycol repeat units between about 5 and about 250, by a Sonogashira coupling reaction.

[0081] In other embodiments, the terminal alkyne groups can be chemically modified to 1,4-disubstituted 1,2,3-triazole groups by a copper-catalyzed azide alkyne cycloaddition reaction. The substituent on the 4-position of the 1,2,3-triazole group can be any of: alkyl with a number of saturated carbons between 8 and 20; phenyl or substituted phenyl; naphthyl or substituted naphthyls; benzyl or benzyl with substitution on the aromatic ring; or poly(ethylene glycol) with the number of ethylene glycol repeat units between 5 and 250.

[0082] In some embodiments, the solvent can include hexane, benzene, toluene, xylene, dimethylformamide, N-methylpyrrolidone, methanol, ethanol, n-propanol, isopropanol, acetone, water, or mixtures thereof.

[0083] In some embodiments, the chemically modified y-graphyne multilayer flake can be mechanically agitated in the solvent to exfoliate the y-graphyne layers. The mechanical agitation can include, for example, ultrasound, magnetic stirring, or direct mechanical mixing.

[0084] In some embodiments, the exfoliated y-graphyne layers have a thickness less than about 10 nm, preferably less than about 1 nm.

[0085] Still other embodiments relate to a method for dispersing multilayer y-graphyne synthesized by the methods described herein. The dispersant solvent can be any of N,N- dimethylformamide or N-methylpyrrolidone, and the dispersion is achieved either by ultrasonic processing or mechanical mixing.

[0086] The invention is further illustrated by the following examples, which are not intended to limit the scope of the claims.Example 1

[0087] This example describes the use of a liquid / liquid interface for the synthesis of thin crystalline sheets of y-graphyne. We found liquid / liquid interfacial-assisted Sonogashira polymerization can generate thin, crystalline, and extended y-graphyne sheets greater than 10 pm and as thin as a few nanometers.

[0088] We demonstrate that utilization of phase assisted templating for Sonogashira cross-coupling of an A3B3-type monomer, l,3,5-tribromo-2,4,6-triethynylbenzene (TBTEB), Fig. 1, resulted in extended thin layers of y-graphyne. An interface between two immiscible liquids to separate the catalysts used for Sonogashira was used to drive the reaction to primarily occur at the liquid interface. An aqueous phase containing a catalyst was charged into a round-bottom flask, which was then charged with an organic phase consisting of TBTEB and another catalyst to form the organic / aqueous interface. The sample mixture was then heated for 24 hours in order to produce y-graphyne at the interface.

[0089] We used established reaction conditions that favor exhaustive coupling of the multifunctional TBTEB to find a way to better template and control the growth of y-graphyne to a larger and more extended structure than what has previously been obtained. An immiscible phase boundary forms from combining an organic phase that consists of the monomer along with catalyst A and an aqueous layer with catalyst B. Because the monomer and catalyst A are typically chosen to be insoluble in the aqueous phase, they both precipitate at the organic / aqueous interface through the differences in solubility of the materials. There at the interface, the monomers begin to couple through cross-coupling with the help of neighboring catalysts in both the aqueous and organic phase.

[0090] As the monomers link together and the film grows, it is neither soluble in the aqueous nor the organic phase. This causes the film to be constrained to the interface and more monomer is available for the film to grow at the interface. This resistance between the two phases thus prevents the overgrowth of the film from generating a three-dimensional material.

[0091] The A3B3-type monomer, TBTEB, was synthesized via a known procedure which was previously used to synthesize y-graphyne. We used an upper organic layer consisting of n-hexanes (10 mL), TBTEB (1 mg), and tetrakis-(triphenylphosphine) palladium(O) (20 eq, 600 mg). A lower aqueous layer was made consisting of a mixture of 5mL of distilled water filtered through a Milli-Q benchtop water purification system, triethylamine (2 mL), and Cui (lOeq, 50 mg) (Fig. 2A). The aqueous layer and organic layer were purged separately and then the organic phase was cannula transferred to overlay the aqueous layer. This allowed the liquid / liquid phase to remain still while the solution was purged and added to one another. While under argon, the reaction was sealed and left to react for twenty-four hours at 72°C.

[0092] After twenty-four hours, a black film formed at the reaction interface (Fig. 2B Left). Carefully, the organic layer was removed and replaced with clean hexanes (10 mL) ten times in order to wash residual palladium from the surface of the film. Using a syringe, the aqueous layer was removed and replaced with distilled water ten times. Once the phases have been replaced, the above organic layer was removed and the film on the surface remained intact. This film was insoluble in organic solvents.

[0093] The film was then transferred to a silicon modified with a 50 nm coating of gold on the surface. Optical microscopy of the film showed that the material consisted of extended two-dimensional structures with a black material on the material's surface (Fig. 2B Right). Further analysis via scanning electron microscopy (SEM) agreed with the results from optical microscopy and showed that the extended structures span up to about 100 pm (Fig. 2C-D). Additionally, changing from the secondary electron detector to the in-lens detector (Tl) allows for better contrast between both elemental composition and contrast between the thin layers and the underlying gold substrate (Fig. 2D).

[0094] In this back-scattering electron (BSE) mode, it is seen that the black material seen in optical microscopy consisted of higher atomic number elements, likely consisting of palladium nanoparticles that formed in solution and settled on top of the film. These palladium nanoparticles were unsuccessfully removed from the material surface via solvent exchange of the organic layer with clean solvent. Within SEM, an energy-dispersive detector (EDS) was used to characterize the elemental composition of the material obtained from the reaction.

[0095] EDS analysis of the films shows that the films primarily consist of carbon with a small contribution from bromine. The bromine is likely due to incomplete cross- coupling within the film, showing that small non-exhaustive substitution defects are present within the film. Additionally, there is a substantial amount of silicon and gold appearing in the spectrum. EDS, at high electron acceleration voltages, has a high penetration depth withinsamples. Meaning that the electrons are passing through the films and releasing X-rays from beneath the sample. At 20 keV, the penetration depth of EDS, is ~2pm, indicating that the thickness of the film obtained from the interface is <2pm thick. Analysis of the black material that sits on top of the material obtained from the interface shows that it contains a significantly higher concentration of Pd and phosphorous. Further analysis shows that these are spherical materials, ranging from 1-5 pm in diameter, which are likely palladium nanoparticles.

[0096] From the material interface, a TEM grid was dip coated and a small amount of material was deposited onto the grid. Analysis in TEM shows that this is a polycrystalline multilayered material (Fig. 3B Inset). The analyzed multilayered flake span ~20pm (Fig. 3A). From the bright-field image, there is some dark field contribution due to the crystallinity of the material and required use of an objective aperture (Fig. 3D). Selected Area Electron Diffraction (SAED) of the sample showed that the sample was polycrystalline due to the presence of circular rings. These two inner most rings were 3.4 A and 2 A, respectively (Fig. 3E).

[0097] Using reported models of y-graphyne, simulated patterns (Fig. 3F) can be used to relate the spacings from the rings to d spacings present within the models. Because the first ring shown within the pattern has a distance of 3.4 A, this suggests that this material has a different stacking mode than that of previously reported experimentally obtained y- graphyne. The stacking mode of this material is likely ABC with R3m space group due to the presence of systematic absences in the polycrystalline pattern. This suggests that the stacking mode of the material obtained in the reported homogeneous synthetic approach is likely not the thermodynamically favored stacking mode, but potentially the kinetically favored mode.

[0098] Placing the objective lens on the outer rings of the pattern allows for dark field image collection. This dark field image shows what objects in the original image contribute to that region of the diffraction pattern. Objects that have diffracting planes within that region of the pattern appear white in the dark field image. As shown in the dark field image, the entire 20 pm flake analyzed in TEM is contributing to the diffraction pattern. This indicates that this flake mostly consists of multilayer polycrystalline ABC stacking y- graphyne.

[0099] The reason a multilayered material was obtained from this synthetic approach is likely due to the solubility of copper acetylides. When a copper acetylide forms at theinterface, it is not entirely constrained at the liquid / liquid interface. This leads to a less well- defined interface and could potentially lead to Sonogashira cross-couplings occurring within the organic phase. In efforts to prevent this, the palladium catalyst must be removed from the organic layer and moved to the aqueous layer. This way, two things are accomplished: (1) Palladium nanoparticles that form will settle to the bottom of the round-bottom flask and not on-top of the material formed at the interface; (2) the monomer is insoluble in the aqueous, thus entirely separating the catalysts needed for Sonogashira cross-coupling from the monomer to force the reaction to only occur at the organic / aqueous interface.

[0100] A range of water soluble palladium catalysts are available, however, palladium(O) 3, 3', 3"- phosphanetriyltris (benzenesulfonic acid) trisodium salt (Pd(O)TPPTS) is among the most popular in literature due to its commercial availability, despite its low catalyst activity (Fig. 4A). This catalyst was used in place of tetrakis-(triphenylphosphine) palladium(O) and used within the aqueous phase. Additionally, cross-coupling in an aqueous environment is well-documented in literature. It is shown that using a 60% acetonitrile / 40% distilled water leads to higher coupling yields. This aqueous mixture can be used with hexanes as the organic layer, as both water and acetonitrile are insoluble in hexanes. Also, this mixture further improves the solubility of the Cui. This reaction was performed similarly to the previously described reaction.

[0101] Briefly, water (4 mL) and acetonitrile (6 mL) were degassed by stirring under house vacuum. Then, water, acetonitrile, and pyridine (500 pL) were measured into a vial and sparged with argon for 20 minutes. 10 mL of hexanes was degassed by freeze-pump-thaw then sparged for 10 minutes to prepare for syringe transfer to the monomer. Catalysts, Pd(0)TPPTS (20 mg) and Cui (2 mg) were weighed into a 40 mL vial and placed under argon atmosphere, then the aqueous solvent mixture was added via a syringe under argon. TBTEB (0.5 mg-4 mg) was weighed into a vial and placed under argon atmosphere. Phases were in separate flasks, purged with argon, and the organic layer was cannula transferred on to the top of the aqueous layer and left to react for twenty-four hours at 75 °C.

[0102] After the reaction was left for 24 hours, no clearly visible film was present at the interface. After solvent exchange was performed for both phases, the top organic layer was removed, and a TEM grid was dip coated. The grid was then allowed to dry and transferred to a TEM for analysis. The material appeared to be a thin film with thicker pieces. In addition to the film and thicker pieces, very low contrast hexagonal units were formed in thesample (Fig. 4B). Because of the low contrast, the hexagonal pieces are likely crystalline graphyne monolayers. Switching to diffraction mode, a faint hexagonal pattern appears. Using dark field imaging, it is seen that a large amount of the contribution of the diffraction pattern comes from the larger film itself with little contribution from the thin hexagonal films (Fig. 4C). This is likely due to the higher scattering coming from the thicker film as a thinner film, such as the hexagonal monolayers, produce less scattering intensity. The distances seen from this diffraction pattern matches that of the stacking models with first order systematic absences, further suggesting that the interfacial reaction leads to a different stacking mode that is more thermodynamically stable than that obtained from the homogeneous phase synthesis.

[0103] In conclusion, it is shown that utilization of a well-defined reaction interface for Sonogashira cross-coupling of a multi-functional monomer, such as TBTEB, can produce extended crystalline y-graphyne structures. By lowering the concentration of the monomer and completely separating the catalysts from the reactant resulted in a more crystalline and potentially less defective material than that obtained from the previously homogeneous reactions. Additionally, by keeping the catalyst separated from the reactant, Pd nanoparticles that form settle to the bottom of the reaction flask. This leads to y-graphyne that contains less impurities. By fine tuning the reaction conditions and material loading, larger area y- graphyne can be achieved.Example 2

[0104] We previously described the synthesis of y-graphyne from an A3B3-type monomer. This method yields crystals comprised of multiple layers of y-graphyne of several microns in lateral size. The sheet edges contain alternating bromide and terminal alkyne groups. The material is difficult to disperse into organic solvents because of the size of the sheets combined with poor solvent interactions of the bromide groups.

[0105] The preparation of single-layer and few-layer graphene films by mechanical exfoliation has paved the way for graphene-based devices. The ability to isolate atomically thin sheets while retaining a defect-free material allows for investigation of the 2D material’s electronic, thermal, and mechanical properties. Solvents that have strong surface interaction with graphene have been shown to exfoliate sheets from bulk graphite in solution with no other chemical modification. We found that N,N-dimethylfromamide (DMF) and N-methylpyrrolidone (NMP) can likewise exfoliate graphyne without chemical modification. However, we also found that chemical modification of the sheet edges of graphyne can enable its exfoliation into arbitrary solvents.Materials and Methods

[0106] All reagents and solvents were acquired from commercial suppliers (Acres Organics, Sigma- Adrich, TCI Chemicals, Fisher Scientific, VWR International, and Strem) and used without further purification, unless otherwise noted. THF was distilled over Na / benzophenone. Triethylamine (TEA) was distilled over CaH2. Anhydrous pyridine was purchased from Acres in AcroSeal packaging and used without further purification.Synthetic Methods

[0107] Reactions were monitored by thin-layer chromatography carried out 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 KMnO4, 0.5 g NaOH, and 10 g K2CO3 in 150 ml water; terminal alkynes stain yellow). Flash chromatography was performed on Luknova SuperSepTM (230-400 mesh) silica gel. Reactions requiring anhydrous or air-free conditions were performed under positive pressure of Ar using standard Schlenk line techniques.NMR Spectrometry

[0108] Routine NMR spectra were recorded on a Bruker Avance III HD 500 spectrometer operating at 500.24 (1H ) . 125.79 (13C) MHz and equipped with Bruker Ascend 500 MHz US Narrow Bore Magnet and Broadband Prodigy TCI CryoProbe. NMR spectra were referenced to TMS (]H,13C) or residual solvent peaks. Chemical shifts (5) are reported in parts per million (ppm).Gas Chromatography and Mass Spectrometry

[0109] GC-MS and EI-MS analyses were performed on an Agilent 7890B / 5977B GC / MSD instrument equipped with an Agilent 7890B automatic liquid sampler, Agilent G4381A Thermal Separation Probe (TSP), and a 30 m x 0.25 mm DB-5MS capillary column (25 pm film thickness). Liquid samples (typically 1 pL) were introduced to the column via split mode injection with a 50:1 split ratio. The set temperatures were 220°Cfor the GCinjection port, 280°C for the MSD transfer line, 230°C for the MS source, and 150°C for the MS quad. The energy of the El source was set to 69.9 eV. For GC analyses, the oven temperature was set at an initial temperature of 60°C for 2.25 min, then ramped to 225 °C at 3 °C min1and held at this final temperature for 3 min. The system used Helium flowing at a rate of 3.0 mL min-1as the mobile phase. The method used a 3-minute solvent delay. Solid samples were introduced into the instrument using the TSP. After the TSP was pre-heated to the set temperature, the sample carrier was inserted into the probe, which was connected directly to the MSD transfer line by a deactivated quartz capillary. Helium flowing at a rate of 3.0 mL min1was used as carrier. Data analysis was performed using Agilent MassHunter Qualitative Analysis Navigator.Infrared Spectroscopy

[0110] Routine small molecule FTIR spectra were collected on an Agilent Cary 630 FTIR instrument equipped with a single-reflection germanium attenuated total reflectance (ATR) module. The instrument was calibrated before sampling against a newly cleaned (acetone) and dried crystal surface. Solid samples were placed directly on the crystal and secured with a needle press. 512 scans from 4000 to 600 cm1were recorded. A background was collected for each sample (512 scans).Melting PointsMelting points were determined with a Mettler Toledo MP50 Melting Point System. The samples were placed in capillary tubes, which were inserted into the heating block. The heating block was then heated at 1°C min1.Transmission Electron Microscopy

[0111] Analyte dispersions were prepared by sonicating in a Branson CPX58OOH ultrasonic bath. Prior to sample preparation, 200-Cu C-B grids or pure carbon film grids were plasma-treated for 30 seconds using an Emitech KlOOx glow discharger. 5 pL of sample dispersion was added to the grid and allowed to absorb for 5 minutes before the excess solvent was wicked.

[0112] The grid was then transferred to a single-tilt sample holder and imaged on an FEI Tecnai 20 TEM operating at 200 kV. Images were recorded on a Tvips F416. Data was collected using SerialEM software. Tilting was performed with the equipped alpha-rotationgoniometer. SAED patterns were recorded on an FEI Tecnai 20 TEM using a 40 pm aperture. The obtained patterns were calibrated against the (111) planes of evaporated aluminum (plane spacing .2338 nm) on a 3 mm grid. The calibration sample was purchased from Electron Microscopy Sciences (EMS p / n 80044).Atomic Force Microscopy

[0113] AFM images were obtained on a Veeco Dimension 3100 atomic force microscope in tapping mode using NanoScope Analysis software or a Park Systems NX10 system. Silicon cantilevers were obtained from Broker (NCHV-A, k = 40 N / m; fO = 320 kHz). The samples were prepared by drop casting -0.01 mg / mL solution in hexanes onto a mica disc, then wicking away the excess. The mica disks were then allowed to dry at room temperature for 24 hours. Gwyddion 2.60 was used for data analysis and visualization of AFM images.X-ray Photoelectron Spectroscopy

[0114] Samples were spread onto double-sided copper tape for XPS analysis. Surveys and high- resolution spectra were acquired on a PHI VersaProbe II Scanning XPS Microprobe using a monochromatic Al X-ray at pressures of 1010to 10'7Torr. The data was smoothed by using the Savitzky-Golay method, with a smoothing width of five, and analyzed using CasaXPS.

[0115] For the analysis of high resolution data, a Tougaard background was applied to each peak before deconvolution. All peak fits used generalized Voigt-like peak shapes, as this function is most appropriate for fitting asymmetric XPS signals. CasaXPS provides a generalized Voigt function described as Lorentzian Finite: LF(a, p, w, n, m), where the first three parameters (a, p, w) affect the Lorentzian line shape and its asymmetry and the final two (n, m) change the width of the Gaussian function and the number of times convolution with the Lorentzian component occurs. Symmetrical peak parameters for the LF line shape were used: LF(1, 1, 255, 360, 6), values derived from default symmetric peak shape settings for CasaXPS. All sub-peak widths were constrained to full width at half maximum (FWHM) of 1.6 eV or less. The residual Br 3d peaks were deconvolved to two distinctive species: Br covalently bonded to sp2carbon (71.4, 70.5 eV), corresponding to partially unreacted sites, and weakly coordinated / anionic Br (67.5-69.5 eV) trapped within the carbon matrix or on theedges or surfaces of y-graphyne sheets. All peaks were allowed a ± 0.2 eV padding to the peak position.SAED Simulation

[0116] The lattice parameters and bond lengths of y-graphyne were obtained from previously published studies. SAED simulations were performed using the CrystalMaker software suite. A model of a single y-graphyne sheet was built in CrystalMaker using a hexagonal P6 lattice with parameters a and c set to 6.86 A and 3.4 A, respectively. The asymmetric unit comprised four atoms placed at 0.208, 0.412, 0.589, 0.795 along the hexagonal P6 x axis. The basic models corresponding to various sheet stacking modes were constructed and visualized using Vesta.Synthesis of small molecules l,3,5-tribromo-2,4,6-triiodobenzene

[0117] To concentrated H2SO4 (500 mL) at room temperature was added periodic acid (41.03 g, 180 mmol) in small portions over 15 min. After dissolution of the periodic acid, crushed KI (89.64 g, 540 mmol) was added in small portions at 0°C over 1 h. To the resulting deep purple solution at 0°C was added 1,3,5-tribromobenzene (18.89 g, 60.0 mmol) in small portions over 25 min. After the solution was stirred at room temperature for 5 days, the resulting thick mixture was poured onto ice. The resulting precipitate was filtered and washed with H2O (5 x 400 mL) and then MeOH (5 x 400 mL) to give l,3,5-tribromo-2,4,6- triiodobenzene (42 g) as a light cream solid. The substance was dissolved in V-methy 1-2- pyrrolidone (250 mL) under heating to 50°C, after which ethanol was added slowly until solids began to precipitate. The mixture was left at room temperature overnight, then the solids were filtered and washed with ethanol (3 x 100 mL). The solid was dried under high vacuum for 3 days to give l,3,5-tribromo-2,4,6-triiodobenzene (30 g, 72%) as a pale-yellow solid. FTIR (neat) vmax = 1488, 1354, 1262, 1227, 1147, 1002, 858, 771, 739, 554, 508 cm'’H NMR (500 MHz, DMSO-d6) no signal.13C NMR (126 MHz, DMSO-d6) 5 138.61(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.((2,4,6-tribromobenzene-L3,5-triyl)tris(ethvne-2,l-diyl))tris(trimethylsilane)

[0118] l,3,5-tribromo-2,4,6-triiodobenzene (6.92 g, 10 mmol), [PdC12(PPh3)2] (2.81 g, 4 mmol, 40 mol%), Cui (381 mg, 2 mmol, 20 mol%), TEA (500 mL) and THE (400 mL) were added to a dry three-necked flask. Ethynyltrimethylsilane (14.73 g, 21.4 mL, 150 mmol) and Ph3P (1.31 g, 5 mmol, 50 mol%) were added to the mixture. The mixture was stirred at 80°C for 4 h under argon. After the removal of solvent on a rotary evaporator, DCM (300 mL) was added to the residue and filtered through Celite. The mixture was washed with water (2 x 100 mL) dried over anhydrous Na2SC>4, filtered through pad of silica gel and the solvent was removed under reduced pressure. The residue was further purified by flash chromatography using n-hexane as the eluent to yield the product as a yellow solid (2.64 g, 4.38 mmol, yield: 44%). The product was then recrystallized from acetonitrile to yield ((2,4,6-tribromobenzene-l,3,5-triyl)tris(ethyne-2,l- diyl))tris(trimethylsilane) as a white solid (1.9 g, 3.15 mmol, yield: 32%). Rf (hexanes) = 0.16. Mp = 141.9°C (after recrystallization from acetonitrile). FTIR (neat) vmax = 2958, 2160, 1376, 1340, 1245, 1019, 834, 758, 708, 658, 633, 539 cm1. 'H NMR (500 MHz, CDC13): d = 0.29 [s, 27H Si(CH3)3] ppm.13C NMR (126 MHz, CDCh): 5129.09 (CBr), 127.49 (C6C=C), 106.79 (C=CSi), 101.83 (C6C=C), -0.23 [Si(CH3)3] ppm.29Si NMR (99 MHz, CDC13) 5 -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.

[0119] To a solution of ((2,4,6-tribromobenzene-l,3,5-triyl)tris(ethyne-2,l- diyl))tris(trimethylsilane) (1.81 g, 3 mmol) in THF (40 mL) was added 6.58 mL TBAF (75% solution in water, 18 mmol) and stirred at 0°C for 15 min. The solution was then diluted with ethyl acetate and washed with distilled water and dried with 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 (950 mg, 2.46 mmol, yield: 82%). Rf (hexanes) = 0.17. Mp = decomposition after 150 °C. FTIR (neat) vmax = 3275, 2922, 2112, 1519, 1368, 1336, 965, 736, 681, 634 cm1. H NMR (500 MHz, CDC13): 8 = 5.16 (s, 3H, (C=CH) ppm.13C NMR (126 MHz, CDCh): 8129.89 (CBr), 126.33 (CeCCH), 91.85 (CCH), 80.96 (C6C=CH) ppm. EI-MS fragmentation: m / z 390.8, 389.9, 388.8, 387.8, 386.8, 385,8, 384,8, 383.8.Methyl 2-phenylhydrazine- 1-carbodithioate

[0120] The synthetic procedure of methyl 2-phenylhydrazine- 1-carbodithioate was adapted from literature. Ethanol (750 mL) was placed in a 2-liter three-necked round-bottom flask. Phenylhydrazine (43.3 g, 39.4 mL, 400 mmol) was added, and the solution was stirred under argon. Carbon disulfide (34.1 g, 27.6 mL, 450 mmol) was added dropwise over 15 minutes. A thick, colorless precipitate formed. After the mixture had been stirred for an additional 30 minutes, potassium hydroxide (30.4 g, 460 mmol) in ethanol (200 mL) was added. The precipitate dissolved, and the color changed to orange. The solution was stirred for an additional 30 minutes. Methyl iodide (65.3 g, 28.6 mL, 460 mmol) was added, and a nearly white solid (KI) was formed. The solution was stirred for an additional 30 minutes. The solvent was removed by evaporation. The resulting substance was dissolved indichloromethane (DCM, 400 mL) and washed with water (3 x 100 mL), then dried with Na2SO4 and evaporated. A red oil was obtained. The product was dissolved in DCM (100 mL), and hexanes (I L) were added to the solution. The resulting white solid was filtered and dried under vacuum for 1 day to yield methyl 2-phenylhydrazine-l- carbodithioate (42.3 g, 213 mmol, 53% yield).JH NMR (500 MHz, CDCh) 5 8.88 (s,1H. NH- C(S)), 7.31 (t, J = 7.8 Hz, 2H CHaryl), 7.01 (t, J = 7.4 Hz,!H, CHaryl), 6.85 (d, J = 8.0 Hz, 2H, CHaryl), 6.07 (s, 1H, PhNH), 2.59 (s, 3H, SCH3).13C NMR (126 MHz, CDCh) 5 208.39 (C(S)S), 145.31 (Cq. aryl), 129.65 (CHaryl), 122.35 (CHaryl), 113.36 (CHaryl), 17.60 (CH3). N-Diethylphenylazothioformamide

[0121] The synthetic procedure of MDiethy Ipheny lazothioformam ide was adapted from literature and the substance was purified using the literature method. Methyl 2- phenylhydrazine-1- carbodithioate (41.6 g, 210 mmol) was placed in a 1 -liter three-necked round-bottom flask. To this flask, diethylamine (200 mL) was added. The resulting solution was refluxed for 18 hours under an argon atmosphere. After 18 hours, the reaction was terminated as confirmed by1H NMR analysis, which indicated complete conversion to 4,4- diethyl-1 -phenylthiosemicarbazide. *H NMR (500 MHz, CDCh) 5 7.28 (dd, J = 8.6, 7.4 Hz, ’H, CHaryl), 6.98 - 6.90 (m, 3H, CHaryl), 3.70 (q, J = 7.2 Hz, 4H, CH2), 1.28 (t, 7 = 7.1 Hz, 6H, CH3).

[0122] After the completion of the reflux step, the solution was exposed to oxygen in the form of air at room temperature for 3 hours. The progress of the reaction was monitored using NMR analysis. Subsequently, the solution was concentrated to obtain a dense red oil (yield 100%). To purify the oil, recrystallization was performed using 20: 1 heptane: ethyl acetate (2 L). The recrystallization process was carried out in a dry ice acetone bath. As a result, red crystals (38.9 g, yield 84%) were obtained. The second crystallization process produced orange crystals of N,N- diethylphenylazothioformamide (30.6 g, yield 66%). Mp = 56.4°C. FTIR (neat) vmax = 2978, 2950, 1554, 1498, 1470, 1392, 1169, 812 cm1. H NMR (500 MHz, CDCh) 87.90 (dd, J = 8.0, 1.8 Hz,!H, CHaryl), 7.57 - 7.50 (m, 3H, CHaryl), 4.03 (q, J = 7.1 Hz, 2H, CH2), 3.52 (q, J = 7.2 Hz, 2H, CH2), 1.41 (t, 7 = 7.2 Hz, 3H, CH3),1.19 (t, J = 6.4 Hz, 3H, CH3).13C NMR (126 MHz, CDCh) 5 194.17 (C(S)), 151.84 (Cq. aryl), 132.77 (CHaryl), 129.36 (2C, CHaryl), 123.66 (2C, CHaryl), 47.87 (CH2), 45.20 (CH2), 13.81 (CH3), 11.52 (CH3).Synthesis of Carbon MaterialsGeneral Synthetic Procedure for y-Graphyne (GY-Br)

[0123] l,3,5-Tribromo-2,4,6-triethynylbenzene (96.7 mg, 0.25 mmol), Pd(PPh3)4 (289 mg, 0.25 mmol) and Cui (3.8 mg, 0.02 mmol) were placed in a Schlenk flask under argon atmosphere and pyridine (50 mb) was added. The tube was sealed, and the contents degassed by three freeze-pump thaw cycles. The reaction mixture was stirred under argon atmosphere at 110°C for 72 h. The reaction mixture was concentrated by a rotary evaporator. Solution of A',Y-dielhyl-2-phenyldiazene- l - carbothioamide in toluene (50 mL, 0.3% mass, 150 mg of 7V,jV-diethyl-2-phenyldiazene- 1 - carbothioamide) was added to the mixture and then was stirring for 3 hours. Then the solid was filtrated. The solid product was washed with toluene, ethyl acetate, water, isopropanol, ethanol, methanol and acetone (each 200 ml). Then the residue was dried under high vacuum for 1 day to give the black solid.

[0124] It must be emphasized that the quality of tetrakis(triphenylphospine)palladium(0) catalyst has a significant impact on the success of the polymerization of TBTEB. The catalyst must be golden- yellow in coloration. Dark orange, brown, or greenish batches of the catalyst result in incomplete polymerization, which can be diagnosed through observing an intense IR peak for the unreacted terminal alkynes at 2100 cm1.Edge Functionalization of GY-Br in One Pot by Sonogashira Coupling

[0125] l,3,5-Tribromo-2,4,6-triethynylbenzene (58 mg, 0.15 mmol), Pd(PPh3)4 (173 mg, 0.15 mmol) and Cui (2.3 mg, 0.012 mmol) were placed in a Schlenk flask under argon atmosphere and pyridine (30 mL) was added. The tube was sealed, and the contents degassed by three freeze-pump thaw cycles. The reaction mixture was stirred under argon atmosphere at 80°C for 24 h. After 24 hours phenylacetylene (92 mg, 0.1 mL, 0.9 mmol) was added to the reaction mixture. The reaction mixture was stirred under argon atmosphere at 80°C for 24 h. The solid product was washed with toluene, ethyl acetate, water, isopropanol, ethanol, methanol and acetone (each 100 ml). Then the residue was dried under high vacuum for 1day to give the black solid. In some cases, the mixture was further washed to remove palladium: 7V,A-diethyl-2-phenyldiazene-l -carbothioamide (100 mg, 0.45 mmol, 3 equivalents) was added to the mixture and stirred for 3 hours. Then the reaction mixture was evaporated and the solid was filtered. The solid was then washed with acetone, methanol, and toluene 6 times.Edge Functionalization of GY -Br by CuAAC Click Chemistry

[0126] Br-edge y-graphyne (50 mg), Cui (30 mg), and 1 -octadecyl azide (50 mg) were added to a 2-neck flask under argon. Dry THF (40 mL) and DIPEA (5 mL) was added to the flask under argon flow. The reaction mixture was stirred for 48 hours at room temperature. The product was then filtered and washed by water (3x40 mL) and acetone (3x40 mL) and dried under high vacuum for 24 hours to give the black material (41 mg).Results

[0127] In this example, we demonstrate four methods for the functionalization of y- graphyne edges. These methods improve the dispersibility of the material in organic solvents by removing the bromide edge groups and by introducing more soluble alkyne chains onto each sheet. As a result, few-layer graphyne sheets separate from the crystal in solution.Here, we describe the synthesis and liquid-phase exfoliation of y-graphyne films with diameters up to several microns. After modification by each of these methods, the graphyne sheets are more dispersible in organic solvents. Additionally, the increased solubility of the edge groups makes exfoliation more favorable for the entire graphyne sheet. Few-layer sheets of 1-3 pm in diameter have been exfoliated in solution using each of these methods.

[0128] In general, solvents or other components that have strong interaction with groups at graphyne edges enable exfoliation.

[0129] The Pd / Cu-catalyzed polymerization of 1,3,5-tribromo- 2,4,6-triethynylbenzene (TBTEB) yields multilayer y- graphyne with unreacted terminal alkyne and aryl bromide groups at sheet edges (Fig. 5A). Here we will designate this material as GY-Br. Elaboration of the terminal alkynes of GY - Br can be achieved through either Glaser-type homocoupling chemistry or copper-catalyzed azide-alkyne cycloaddition (CuAAC), while the aryl bromides can undergo further Pd- catalyzed cross-coupling reactions. We opted for the CuAAC route to modify the terminal alkynes and tandem Sonogashira coupling for the aryl bromides(Fig. 5B) due to the accessibility of the reagents (alkyl azides and terminal alkynes respetively). For the CuAAC functionalizations, GY-Br was initially isolated and purified as we previously described. In contrast, functionalization through Sonogashira coupling could be carried out in one pot. Excess terminal alkyne was added once the TBTEB polymerization was complete, and the reactions were allowed to proceed for an additional 72 hours before workup. Successful functionalization was confirmed by IR spectroscopy, with spectra of all functionalized graphynes exhibiting characteristic bands for the newly installed functionalities, such as the C-H stretch bands at -2900 cm- 1 (Fig. 6A). We designated the resulting edge-functionalized graphynes as GY- Ph, GY-MeONaph, GY-C18, and GY- C18N3, based on the nature of the edge groups.

[0130] In contrast to GY-Br, which tends to form large aggregates and requires prolonged sonication at high power to achieve dispersion, the flakes of the edge- functionalized materials readily dispersed into hexanes or heptane upon processing in a low- power bath sonicator for just 30 seconds or vortexing. The relative efficiency of different edge groups in the exfoliation and stabilization of graphyne could be directly estimated from visual observation of the treated dispersions upon standing. We found that the C18 chains were the most effective at stabilizing a dispersion of sheets at equilibrium (Fig. 6B). Dispersions of GY-Ph and GY-MeONaph precipitated as thin powders within minutes.

[0131] We used X-ray photoelectron spectroscopy (XPS) to examine the surface composition of the edge-functionalized graphynes. Since XPS is a surface-biased technique with a maximum penetration depth of approximately 5 nm in carbon materials, we expect it to overestimate the content of edge groups. Consequently, XPS is not suitable for precisely quantifying the edge group content relative to the bulk material but serves as a useful measure for studying the transformations of these groups. The XPS survey revealed that GY- C18 retained about half of the bromine signal intensity relative to GY-Br, displaying the lowest apparent reduction in bromine content among all modified graphynes.

[0132] The relatively low reactivity of the aliphatic alkyne towards the Cu co-catalyst and steric repulsion between the bulky C18 chains likely contributed to the low efficiency of the Sonogashira coupling in this case. In contrast, the other two materials functionalized by the one-pot method retained 12% (GY-Ph) and 6% (GY-MeONaph) of bromine signal intensity, suggesting that phenylacetylene and especially 2-ethynyl-6- methoxynaphthalene couple more readily. The bromine signal intensity for GY-C18N3 appeared to beanomalously low. Based on its high dispersibility (Fig. 6B) as well as mass spectrometric evidence, it is evident that GY-C18N3 contains a significant amount of alkyl edge groups. It is likely that only the volume of hydrocarbon chains on the surface of the crystal is accessible to XPS, and the remaining bromides are shielded. Notably, XPS analysis for the two alkyl- functionalized materials suggest that dispersibility is mostly dependent on the nature of edge groups, and less so on the degree of grafting.

[0133] Transmission electron microscopy (TEM) analysis of samples spotted from dispersions in acetone prepared by sonication for 2-3 minutes in a standard cleaning bath revealed successful exfoliation of very thin flakes with lateral sizes around 1-2 pm (Fig. 7A). However, after 30 minutes of moderate power ultrasonic processing of the GY-C18 dispersion (110 W, 40 kHz), we observed only amorphous carbon clusters (Fig. 7B). Graphene has been shown to break down under sonication in a similar way.

[0134] The exfoliated samples of GY-Ph, prepared through brief low-power bath sonication or vortexing, revealed thicker flakes when observed by TEM (Fig. 7C). This allowed us to obtain a selected area electron diffraction (SAED) pattern (Fig. 7D). Previously, we acquired multiple SAED patterns for GY-Br, which indicated low- symmetry / aperiodic stacking. However, the SAED patterns for thin GY-Ph flakes consistently displayed systematic absences consistent with the more symmetric R3m space group (Fig. 7D). This new stacking mode could have emerged through either the sliding of the sheets within the flake or through the exfoliation and subsequent re-stacking into a local thermodynamic minimum. It is important to note that the symmetry of y-graphyne allows for multiple possible stackings of two sheets, which are expected to be very close in energy. Therefore, the number of possible regular structures for multilayer y-graphyne is practically unlimited, and bulk GY-Ph is likely to feature numerous stacking faults, akin to rhombohedral graphite.

[0135] We further investigated the flakes of edge-functionalized graphynes by atomic force microscopy (AFM). Dispersions of each material at approximately 0.01 mg / mL in hexanes were subjected to low-power ultrasound and then cast onto the surface of mica. The flakes of GY-C18N3 exhibited lateral dimensions consistent with TEM imaging (Fig. 7A), and height profiles under 1 nm (Fig. 8A, C). Typically, the AFM height profile of singlelayer graphene is around 0.7 nm, owing to the contrast between phases and possible surface adsorption of solvents or ambient air. Each subsequent layer adds 0.3-0.4 nm in height,broadly consistent with the interlayer distance in graphite. This indicates that the ~0.8 nm height we measured corresponds to a single layer of y-graphyne. In contrast, GY-Ph dispersed and deposited on mica using the same protocol yielded thicker stacks of about 5 nm in height. Many of these flakes retained their hexagonal shape (Fig. 8D, E). The apparent absence of this hexagonal symmetry in the exfoliated single-layer sheets of GY-C18N3 led us to conclude that the ultrasonic processing used to separate layers can destroy thin y-graphyne sheets, as has been previously observed for solution-phase exfoliation of graphene.

[0136] 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 skill of the art are intended to be covered by the appended claims. All references, publications, and patents cited in the present application are herein incorporated by reference in their entirety.

Claims

Having described the invention, the following is claimed:

1. A method comprising: synthesizing covalently bonded lattices based on irreversible bond-making reactions which favor exhaustive substitution on multi-functional substrates, wherein the irreversible bond-making reactions include ordered two-dimensional interfacial polymerizations of a monomer at a liquid / liquid interface, liquid-solid interface, or liquid-gas interface.

2. The method of claim 1 , wherein the ordered two-dimensional interfacial polymerizations occur in the absence of a physical substrate or added template.

3. The method of claim 1, wherein the interfacial polymerization is a Sonogashira cross-coupling reaction between a terminal alkyne and an aryl halide.

4. The method of any of claims 1 to 3, wherein the monomer is a 1,3,5-trihalo- 2,4,6-triethynylbenzene monomer, either symmetric or unsymmetric, dissolved in an organic solvent.

5. The method of any of claim 3 or claim 4, wherein the Sonogashira crosscoupling reaction is performed using a palladium precatalyst which is soluble in an organic phase and insoluble in an aqueous phase.

6. The method of claim 5, wherein the precatalyst is selected from tetrakis(triphenylphosphine)palladium(0) , bis(dibenzylideneacetone)palladium(0) , tris(dibenzylideneacetone)dipalladium(0), dichlorobis(tricyclohexylphosphine)palladium(II), dichlorobis(tri-o-tolylphosphine)palladium(II), (l,3-bis(2,6-diisopropylphenyl)imidazolidene) ( 3 -chloropyridyl) palladium(II) dichloride, (l,3-bis(2,6-dimethylphenyl)imidazolidene) ( 3- chloropyridyl) palladium(II) dichloride, or [l,3-bis(2,6-diisopropylphenyl)imidazol-2- ylidene](3-chloropyridyl)palladium(II) dichloride.

7. The method of any of claim 3 or 4, wherein the Sonogashira cross-coupling reaction is performed using a palladium precatalyst which is soluble in an aqueous phase and insoluble in an organic phase.

8. The method of claim 7, wherein the precatalyst is selected from any of the possible alkali metal salts of sulfonated phosphine complexes of palladium (0), where the sulfonated phosphine ligand is any of Triphenylphosphine-3,3',3''-trisulfonate, bis(p- sulfonatophenyl)phenylphosphine, (p-sulfonatophenyl)diphenylphosphine or the ligands can be any of (2-di-t-butylphospinoethyl)trimethylammonium chloride or 4-(di-t-butylphospino)- N,N-dimethylpiperidinium chloride.

9. The method of any of claims 3 to 8, wherein the Sonogashira cross-coupling reaction is performed using a copper co-catalyst and wherein the copper co-catalyst is selected from copper(I) iodide, copper(I) chloride, copper(I) bromide, tetrakis(acetonitrile)copper(I) hexafluorophosphate, tetrakisacetonitrile copper(I) triflate, copper(O) foil or shavings combined with pyridine, copper(O) foil or shavings combined with any aliphatic tertiary amine or acetonitrile, or copper(II) sulfate combined with sodium ascorbate.

10. The method of claim 9, wherein the copper co-catalyst is soluble in the aqueous phase and insoluble in the organic phase.

11. The method of claim 9 or 10, wherein the monomer is provided in the organic phase and the palladium catalyst and copper co-catalyst are provided in the aqueous phase.

12. The method of claim 11, wherein the organic phase overlies the aqueous phase during interfacial polymerization of the monomer.

13. The method of any of claims 7 to 12, wherein the organic phase includes the monomer dissolved in hexane and the aqueous phase includes a mixture of water soluble palladium catalyst, water soluble copper co-catalyst, water, and optionally acetonitrile or pyridine.

14. The method of any of claims 1 to 13, wherein the covalently bonded lattices include sp2 / sp1allotropes of carbon.

15. The method of any of claims 1 to 14, wherein monomer concentration and optionally separation of catalysts from the monomer during the two-dimensional interfacial polymerizations is effective to synthesize substantially crystalline covalently bonded lattices with minimal to no defects.

16. The method of any of claims 1 to 15, wherein the covalently bonded lattices include y-graphyne.

17. The method of any of claims 1 to 16, yielding multilayer y-graphyne with linear size of crystalline domains in the range of 10 nanometers to 10 millimeters.

18. The method of any of claims 1 to 16, yielding few-layer (1-30 layers) y- graphyne with linear size of crystalline flakes in the range of about 10 nanometers to about 10 millimeters.

19. y-Graphyne formed by interfacial polymerization.

20. The y-graphyne of claim 19, formed by interfacial polymerization of a first mixture of a l,3,5-trihalo-2,4,6-triethynylbenzene monomer, either symmetric or unsymmetric, dissolved in an organic phase and a second mixture of a water soluble copper catalyst and optionally a water soluble palladium catalyst in an aqueous phase.

21. The y-graphyne of claim 19 or 20, wherein the interfacial polymerization is a Sonogashira cross-coupling reaction.

22. The y-graphyne of any of claims 19 to 21, having linear size crystalline domains in the range of about 10 nanometers to about 10 millimeters.

23. The y-graphyne of any of claims 19 or 22, having few-layer (1-30 layers) with linear size crystalline flakes in the range of about 10 nanometers to about 10 millimeters.

24. A method of exfoliating y-graphyne layers from a y-graphyne multilayer flake, the method comprising: chemically modifying sheet edges of a y-graphyne multilayer flake to introduce terminal groups on the sheet edges that enhance dispersibility and / or solubility of the y-graphyne multilayer flake in solvent; adding the chemically modified y-graphyne multilayer flake to the solvent; and agitating the chemically modified y-graphyne multilayer flake in the solvent to exfoliate the y-graphyne layers from the chemically modified y-graphyne multilayer sheet.

25. The method of claim 24, wherein sheet edges of a y-graphyne multilayer flake prior to chemical modification include terminal halide and / or alkyne groups.

26. The method of claim 25, wherein the terminal halide groups and / or alkyne groups are chemically modified to organic groups that enhance the dispersibility and / or solubility of the y-graphyne multilayer flake.

27. The method of claim 26, wherein the terminal halide groups are chemically modified to the organic groups by a Sonogashira coupling reaction.

28. The method of claim 26, wherein the terminal halide groups are chemically modified to phenylethynyl groups, 2-ethynyl-6-methoxynaphthalene groups, alkylethynyl groups with the number of saturated carbons between about 4 and about 20, or prop-2-yn-l- yloxy-(poly(ethylene glycol)) groups with the number of ethylene glycol repeat units between about 5 and about 250, by a Sonogashira coupling reaction.

29. The method of claim 26, wherein the terminal alkyne groups are modified to 1 ,4-disubstituted 1,2,3-triazole groups by a copper-catalyzed azide alkyne cycloaddition reaction.

30. The method of claim 29, wherein the substituent on the 4-position of the 1,2,3- triazole group is any of: alkyl with a number of saturated carbons between about 8 and about 20; phenyl or substituted phenyl; naphthyl or substituted naphthyls; benzyl or benzyl with substitution on the aromatic ring; or poly(ethylene glycol) with the number of ethylene glycol repeat units between about 5 and about 250.

31. The method of any of claims 24 to 30, wherein the solvent comprises hexane, benzene, toluene, xylene, dimethylformamide, N-methylpyrrolidone, methanol, ethanol, n- propanol, isopropanol, acetone, water, or mixtures thereof.

32. The method of any of claims 24 to 31, wherein the chemically modified y- graphyne multilayer flake is mechanically agitated in the solvent to exfoliate the y-graphyne layers.

33. The method of claim 32, wherein the chemically modified y-graphyne multilayer flake is mechanically agitated by ultrasound.

34. The method of any of claims 24 to 33, wherein the exfoliated y-graphyne layers have a thickness less than about 10 nm, preferably less than about 1 nm.

35. A y-graphyne layer or few layered sheet formed by the method of any of claims 24 to 34.

36. A method for dispersing multilayer y-graphyne synthesized by the method of claims 1, 2, and 4, where the dispersant solvent is any of N,N-dimethylformamide or N- methylpyrrolidone, and the dispersion is achieved either by ultrasonic processing or mechanical mixing.

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