Constructing two-dimensional holey graphyne with unusual annulative π-extension

•A two-dimensional carbon allotrope of holey graphyne (HGY) was designed•1,3,5-tribromo-2,4,6-triethynylbenzene synthesized for fabrication HGY•HGY comprised a pattern six-vertex and highly strained, eight-vertex rings•HGY’s direct p-type semiconductor with high carrier mobility simulated Carbon has many faces, such as graphene, nanotubes, fullerene, graphdiyne, where hexagons are the primary building blocks these materials. Since exotic properties allotropes related to their unique structure, some basic questions will occur. Is it possible design new allotropes? An intriguing molecule, dibenzocyclooctadiyne, first by Sondheimer coworkers, caught our attention. In two aromatic benzene rings connected bent acetylenic linkages, resulting in eight-membered ring. This interesting molecule inspired us synthesize allotrope, namely graphyne, reported this work. Here, we report two-dimensional, single-crystalline an interfacial two-solvent system through Castro-Stephens-type coupling reaction from 1,3,5-tribromo-2,4,6-triethynylbenzene. As type 2D HGY is alternately linked between C≡C bonds composed equal percentage sp2 sp hybridized atoms. By combining experimental theoretical studies, systematically investigated stability its vibrational optical properties. Density functional theory computations predicted that embraces bandgap (∼1.1 eV) mobility. Transmission electron microscopic studies revealed sheets crystalline AB stacking. Its semiconducting character, nonlinear bonding, special π-conjugated structure endow promising applications optoelectronic, energy harvesting, gas separation, catalysis, water remediation, sensor, energy-related fields. Diamond graphite naturally occurring allotropes, which possess sp3 atoms, respectively. The discovery various other materials, graphene,1Novoselov K.S. Geim A.K. Morozov S.V. Jiang D. Zhang Y. 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So far, mainly four geometries graphynes, α-, β-, γ-, 6,6,12-graphyne,4Li have explored, percentages linkages 100%, 66.67%, 33.33%, 41.67%, respectively.7Wu Interestingly, similar 6,6,12-graphynes5Baughman Dirac-cone-like band structures at Fermi level exhibit small effective masses mobility,6Malko while graphdiyne4Li γ-graphyne5Baughman nonzero gaps. Recently, Casari coworkers experimentally fabricated graphdiyne-like nanonetwork10Rabia Tumino Milani Russo V. Bassi A.L. N. Lucotti Achilli Fratesi Manini al.Structural, electronic, nanonetwork on au (111): implications engineering sp-sp2 nanostructures.ACS Appl. Nano Mater. 2020; 3: 12178-12187https://doi.org/10.1021/acsanm.0c02665Crossref (11) designed all graphdiyne-related allotropes,11Serafini P. Proserpio D.M. C.S. 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Synthesis sym-dibenzo-1,5-cyclooctadiene-3,7-diyne sym-dibenzo-1,3,5-cyclooctatrien-7-yne, presumably conjugated compounds.J. Am. 1974; 96: 5604-5605https://doi.org/10.1021/ja00824a066Crossref (131) exciting HGY, Herein, whose rings. We ultrathin, bottom-up approach transition-metal-mediated cross-coupling 1,3,5-tribromo-2,4,6-triethynylbenzene interface (water dichloromethane). spectroscopic joint studies. It potential optoelectronic means density (DFT) computations, theoretically geometric (see Data S1. Crystallographic information files HGY). novel space group P6/mmm (D6h1) Hermann-Mauguin (Schoenflies) notation. Different six-membered rings, not but also atom hexagonal units (Figure 1A ). optimized constant = b 10.83 Å S1; Tables S1–S3). According analysis 1A), hybridized, alternating single double bond distance 1.461 1.396 Å, comparison, hybridized; lengths alternate 1.461, 1.412, 1.226 Å; angles 114.3° 155.6°, respectively 1A). Note charge densities 1B), variation indicates (sp2 sp). These results good agreement line along direction S2). Stability requirement real be evaluated computed cohesive energy, phonon spectra, elastic constants, ab initio molecular dynamics (AIMD) simulations. First, per atom, Ecoh, calculated Ecoh (n·Ecoh, – Et)/n, Et, n total primitive cell, number cell. (7.30 eV/atom) very close (8.11 eV1), indicating thermodynamic stability. Then, frequencies modes Brillouin zone (BZ) (Figures 1C No imaginary were observed, kinetically stable. maximum frequency longitudinal optic mode (LO) 2,400 cm−1 chain.2Kroto addition, constants (C11 C22 91.06 N/m, C12 35.60 C66 0.15 N/m) satisfy specification crystal > |C12|, 0), showing mechanically To further investigate issue thermal stability, carried out AIMD simulation T 1,000 K 10 ps. atomic (2∗2∗1) before after 1D), found remains well-connected framework ps MD simulations temperature, Our thermogravimetric (TGA) showed decomposition temperature about 750°C S2), consistent above strongly indicate thermodynamic, kinetic, mechanic, stabilities thus synthetic target. scheme using monomer (1,3,5-tribromo-2,4,6-triethynylbenzene, 1) (Scheme Figures 2A 2B ).14Stephens R.D. Castro C.E. substitution aryl iodides cuprous acetylides. synthesis tolanes Heterocyclics.J. Org. 1963; 28: 3313-3315https://doi.org/10.1021/jo01047a008Crossref (662) Firstly, known 2,4,6-tribromobenzene-1,3,5-tricarbaldehyde 4 (the precursor mesitylene modified literature procedure.15Becker Voss Villinger Schulz efficient route 1, 3, 5-triazido-2, 4, 6-tricyanobenzene.Z. Naturforsch. 67: 643-649https://doi.org/10.5560/znb.2012-0092Crossref 1 Corey-Fuchs reaction16Corey E.J. Fuchs P.A. method formyl→ethynyl conversion (RCHO→RC CH or RC CR′).Tetrahedron 1972; 13: 3769-3772https://doi.org/10.1016/S0040-4039(01)94157-7Crossref (1863) lithium diisopropylamide base. More specifically, illustrate preparation detailed procedures (1H nuclear magnetic resonance [NMR], 13C NMR yields, process) given supplemental S3–S9). Finally, transformed into film organic via initial intermediate S10). identified 13C-solid S9), shows prominent peaks. peaks 91.1 (red color) 80.9 ppm (blue assigned whereas 129.7 126.8 attributed (green color). newly formed peak terminal (defect) bonding. gain insights underlying mechanism formation strained dimer rather than trimer intermediate, applied climbing-image nudged (CI-NEB) evaluate barrier both S11). Both reactions exothermic, according profiles states final trimer. (17.76 lower (23.74 eV), confirms process, ruled (γ-graphyne) based intermediate. room comparison γ-graphyne, since difference barriers 5.98 eV, γ-graphyne needs more overcoming kinetic barrier. morphologies lateral dimension up several micrometers, characterized microscopy (OM) scanning (SEM) 3A flat sheet thickness 5.3 nm observed force (AFM) 3B) 3D image S12), 15 layers interlayer 0.36 (based transmission [TEM] measurements described below). TEM used analyze morphology microstructure film: low-resolution S13) high-resolution (HRTEM) 3C) reconfirm successful continuous film. corresponding fast Fourier transform (FFT) HRTEM (inset Figure verifies nature film, in-plane order over relatively large area exhibits single-crystal diffractions spots. d-spacing (200) reflections 0.442 3D). Another set hexagonally arranged diffraction spots larger 0.27 indexed (220) HGY. verify nanosheet, [001] axis observation model “AB” stacking (t) (ranging 1.3 61.4 step nm) defocus (Δf) ranging −120 +240 60 3E S14). images value range Δf (120–240 well match green red squares; 3E). Thus, nanosheets stacked manner. Furthermore, examined X-ray (XRD) measurement. (002) approximately 24.5° spacing 3F), FFT 3G. fringe reveals curve streaks parameter nm, XRD result peak, 3H–3J). (∼0.36 slightly higher due weak van der Waals interactions.17Reina Jia Ho Nezich Son Bulovic Dresselhaus M.S. Kong Large area, few-layer films arbitrary substrates chemical vapor deposition.Nano 2009; 9: 30-35https://doi.org/10.1021/nl801827vCrossref (5175) 18Zhou Gao R. Xie Z. Yang nanowalls reaction.J. 2015; 137: 7596-7599https://doi.org/10.1021/jacs.5b04057Crossref (417) 19Qian Huang Chen Self-catalyzed growth large-area nanofilms carbon.Sci. Rep. 7756https://doi.org/10.1038/srep07756Crossref (117) study properties20Park Ryou Hong Sumpter B.G. Yoon Electronic bilayer coupled external electric field.Phys. 115: 015502https://doi.org/10.1103/PhysRevLett.115.015502Crossref (45) 21Cao Fatemi Demir Fang Tomarken S.L. Luo J.Y. Sanchez-Yamagishi J.D. Watanabe Taniguchi T. Kaxiras E. al.Correlated insulator behaviour half-filling magic-angle superlattices.Nature. 2018; 556: 80-84https://doi.org/10.1038/nature26154Crossref (2468) 22Liu Hao Halperin B.I. Interlayer fractional quantum Hall layer.Nat. 15: 893-897https://doi.org/10.1038/s41567-019-0546-0Crossref essential elemental composition probed systemically energy-dispersive spectroscopy (EDS), photoelectron (XPS), Fourier-transform infrared (FT-IR), Raman spectroscopy. survey spectra XPS 4A S15) primarily carbon, silicon oxygen signals SiO2 layer. (STEM)-EDS maps 4B) show distributions C, Br, O. result, dominating element proving completion give nanosheets. EDS S16) result. High-resolution discriminate against circumstance element. C 1s 284.8 eV deconvoluted Gaussian sub-peaks 4A), contributions (C=C; 284.5 (C≡C; 285.3 species. Also, abundance sp/sp2 same structure. C-O C=O, minor located 286.6 288.5 O most likely derives absorption air pores oxidation alkyne, cause defects. Meanwhile, analyzed FT-IR compared 1. When formed, C–Br stretching (at 682 cm−1) C≡C–H 3,278 dramatically decrease (to nearly negligible). 4C) 1,933 2,115 corresponds (sp) intense (1,336 HGY; 1,338 bending vibration delocalized confirming scattering powerful tool structural particularly those Raman-active alkyne linkers arrayed concrete topology measured spectrum comparing DFT-simulated 4D 4E). Experimentally, active 200 2,500 cm−1, agrees computational S17–S19). 1,946 2,207 A1g (2,091 E2g (2,128 4E) linkage 4C). 1,525 first-order (1,539 in-phase shifted G (1,575 cm−1).23Tuinstra Koenig J.L. graphite.J. 1970; 53: 1126-1130https://doi.org/10.1063/1.1674108Crossref (8585) 1,296 called D band, breathing (1,398 domains details). Terminal (2,100–2,120 almost negligible, residues monomers integrated network HGY,24Matsuoka Sakamoto Hoshiko Sasaki Masunaga Nagashio Nishihara Crystalline produced gas/liquid liquid/liquid interface.J. 2017; 139: 3145-3152https://doi.org/10.1021/jacs.6b12776Crossref (372) except few edges defect sites. (Eg) feature semiconductors determines optoelectronics. diffuse reflectance (DRS) From coefficient (α) obtained (Equation S1) Kubelka-Munk equation determined ∼1.1 transition function 4F), (∼1.0 5A 5B ) DFT HSE06 function. 1.1 point 5B) reciprocal conduction minimum (CBM) valence (VBM) originate π∗ π states, respectively, dispersion arises overlap 2Pz orbitals 5C). wavefunction pair CBM VBM plotted 5D).25Long Tang Shuai nanoribbons: predictions.ACS Nano. 2011; 2593-2600https://doi.org/10.1021/nn102472sCrossref (780) details work (5.2 presented S20 S21 procedures. (FBZ) 5E) line) orthogonal lattice. (fractional k-space coordinates [−1/3, 2/3, 0]) defined cell folded (0, 1/3, 0) sitting FBZ supercell. Compared rhombus drawn dashed lines 5F), there 48 rectangle (lattice aox 18.76 boy =10.83 Å). Bardeen Shockley 195026Bardeen Deformation potentials mobilities non-polar crystals.Phys. 1950; 80: 72-80https://doi.org/10.1103/PhysRev.80.72Crossref (2307) derived deformation (DP) intrinsic (u) crystal, extensively (μ) materials.25Long Scholar,27Cai Y.-W. Polarity-reversed robust monolayer MoS2 nanoribbons.J. 136: 6269-6275https://doi.org/10.1021/ja4109787Crossref (667) 28Lin Gu Porous silaphosphorene, silaarsenene silaantimonene: sweet marriage Si P/As/Sb.J. 6: 3738-3746https://doi.org/10.1039/C7TA10466ACrossref 29Chen Xi Carrier should even prediction.J. 4: 1443-1448https://doi.org/10.1021/jz4005587Crossref (293) calculation, adopted supercell vertical directions, x y, sheet, allows intuitive explanation property 5G S22). Based DP theory, (E1), moduli (C), mass (m∗), relaxation time (τ) Equation S3 summarized Table compare times, mobilities, bandgaps 6-6-12-graphyne, S4.25Long Scholar,29Chen me 0.21 y direction, dispersed being direction. Specifically, 1.16 × 104 cm2 V−1 s−1 0.81 hole (4.51 s−1) (2.26 three times electrons. S3, electrons, holes long, acoustic, phonon-scattering times. constant, capability (hole) acoustic phonon. VBM, explained frontier accountable transport. edge shift (VBM CBM) exhibited strain S22), wave functions S22) orbital theories, nodes directions findings explain why small-angle (SAXRD) charge-carrier devices, impossible current stage limited defect-free elsewhere future.Table 1The theoryCarrier typeE1 (eV)C2D (N/m)m∗ (me)μ (104 cm2V−1s−1)τ(ps)ey1.9191.060.210.810.96hy1.1491.060.212.262.70ex1.8991.060.151.611.37hx1.1391.060.154.513.84The (C2D), (μ), (e) (h) 300 Open table tab summary, ultrathin consisting six- could prepared five steps mesitylene. developed material, multi-layered images, intermolecular force. big pore diameter 0.8–1.0 nm. DRS-UV eV; (1.61 (0.81 theory. present demonstrates introduces concept allotrope. With studying pave way synthesizing HGY-related nanocarbon