Concentration-Directed Polymorphic Surface Covalent Organic

Concentration-Directed Polymorphic Surface Covalent Organic Frameworks: Rhombus, Parallelogram, and Kagome Yi-Ping Mo,†,‡ Xuan-He Liu,†,‡ and Dong Wang*,† †

CAS Key Laboratory of Molecular Nanostructure and Nanotechnology and CAS Research and Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, People’s Republic of China ‡ University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China S Supporting Information *

ABSTRACT: Polymorphic single-layered covalent organic frameworks (sCOFs) via on-surface synthesis have been investigated by employing the tetradentate monomer 1,3,6,8-tetrakis(p-formylphenyl)pyrene with D2h symmetry and ditopic linear diamine building blocks. Three kinds of well-ordered sCOFs, including rhombus, parallelogram, and Kagome networks, are observed on the graphite surface by scanning tunnel microscopy. The pore size and periodicity of sCOFs are tunable by employing diamine monomers with different lengths. Statistical analysis reveals that two types of quadrate networks are preferred at high concentration, whereas the occupancy of Kagome networks increases at low concentration. This trend can be understood by the differences in the network density of three kinds of networks. The reversibility and the self-sorting ability of the dynamic covalent reaction make it possible to control the polymorphic distribution similar to the principle demonstrated in supramolecular selfassembly. KEYWORDS: surface covalent organic frameworks, Kagome, scanning tunneling microscopy, monomer concentration, dynamic covalent bonds properties16−18 and magnetic properties.19−21 However, molecular Kagome structures are very rare. Since Zaworotko and co-workers reported a nanoscale Kagome lattice by supramolecular assembly,22 great efforts have been paid to design and construct such fascinating structures. So far, only a few examples of surface-supported 2D Kagome networks stabilized by van der Waals interactions, hydrogen bonding, or coordination interactions have been achieved.23−27 Recently, Wang et al. reported chiral Kagome lattices assembled by onsurface-synthesized organometallic compounds, which were stabilized by the synergy of multiple intermolecular interactions.28 To the best of our knowledge, the synthesis of Kagome structures linked by covalent bonds via on-surface reactions has not been demonstrated. On the other hand, synthesis of bulk COF materials of Kagome lattices has been reported under solvothermal conditions by employing tetraphenylethene-cored precursors29−32 or a monomer with reduced symmetry.33 Polymorphism is a common issue in crystal growth and design. The polymorphic surface assembly from the same

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ingle-layered covalent organic frameworks (sCOFs), featuring atomic thickness and two-dimensional (2D) porous networks with covalently bonded building blocks, have attracted tremendous attention in recent years.1 As an organic analogue to graphene, sCOFs are promising to display interesting electronic/optoelectronic properties and are potential candidates for miniature molecular devices.2 The merits of 2D sCOFs not only lie in the rigid and robust architectures with high stability but also rest on the structural diversity with concomitant function. Theoretical calculations predict that the electronic properties of sCOFs can be greatly controlled by tailoring the topology of the materials.3−5 Typically, sCOFs are fabricated from high-symmetry building blocks in order to achieve easily predictable structures with high quality. Multitopic precursors with C3 or C4 symmetry are most commonly utilized6−15 to react with ditopic linear building blocks and attain an extended hexagonal honeycomb sCOF or quadrate sCOF with uniform pore structures. The design and construction of high-quality sCOFs with diverse topologic structures are still in high demand. Among various possible 2D molecular networks, the Kagome structure, composed of regularly arranged triangular and hexagonal pores, is particularly intriguing because of not only its special topology but also the associated vibrational © 2017 American Chemical Society

Received: September 27, 2017 Accepted: November 13, 2017 Published: November 13, 2017 11694

DOI: 10.1021/acsnano.7b06871 ACS Nano 2017, 11, 11694−11700

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ACS Nano Scheme 1. Topological design of polymorphic sCOFs and chemical structures of monomers: 1,3,6,8-tetrakis(pformylphenyl)pyrene (1), p-phenylenediamine (2), benzidine dihydrochloride (3), and 4,4″-diamino-p-terphenyl (4).

graphite (HOPG). The condensation reaction was carried out at 120 °C for 3 h in a closed system. Three kinds of highly ordered sCOFs were formed with different morphologies, including rhombus, parallelogram, and Kagome networks. A high-resolution STM image of the polymorphic sCOFs is displayed in Figure 1b. This result is distinct from that in the bulk COFs synthesized by the solvothermal method using the same monomer combination, in which only quadrate networks are acquired.46−48 Figure 2 presents the high-resolution STM images of each kind of sCOF with the corresponding structural models. Regular networks with uniform pores can be observed for two types of quadrate sCOFs. The measured lattice parameters of the rhombus networks (Figure 2a) are a = b = 2.5 ± 0.2 nm; γ = 82 ± 2°. Structural analysis of the parallelogram networks (Figure 2c) reveals the experimental lattice parameters are a = 2.3 ± 0.2 nm; b = 2.5 ± 0.2 nm; γ = 71 ± 2°. Detailed structural analysis indicates that the difference between two structures can be understood by the configuration of the imine bond (see the SI for details). Specifically, the imine bonds in the rhombus networks are heterdromous after condensation (Figure 2b), whereas they are homodromous in the parallelogram networks (Figure 2d). The structural modeling results in excellent agreement between the experimental and simulated lattice parameters (Table 1). Figure 2e discloses the structural details of the highly ordered Kagome sCOF. The Kagome networks contain two disparate types of pores, i.e., triangular and hexagonal ones. The lattice parameters of the Kagome morphological sCOF are measured to be a = 4.7 ± 0.2 nm; b = 4.9 ± 0.2 nm; γ = 61 ± 2°, which are in excellent agreement with the expected value by structural modeling (a = b = 4.77 nm; γ = 60°). Similar bulk COFs bearing two different kinds of pores are constructed under solvothermal conditions recently, by employing tetraphenylethene-cored precursors or a monomer with reduced symmetry.29−33 Compared to quadrate networks, the orientation of molecule 1 in the Kagome morphological networks is rotated 120° at the vertex of each hexagon. In addition, the imine bonds in the Kagome networks keep a homodromous configuration (Figure 2f), which is responsible for the high possibility of the domain boundary between Kagome morphological networks and parallelogram networks (as shown in Figure 1b). Polymorphological sCOFs Fabricated by Other Monomers. To investigate the influence of the length of the ditopic building blocks on the growth of sCOFs, monomers 3 and 4 were employed to fabricate sCOFs with molecule 1 (Scheme

building blocks has been extensively studied and can be tuned by temperature, concentration, molar ratio, etc.24,34−40 Moreover, some previous studies have reported the structural evolution from oligomers to sCOFs depdending on thermal treatment or stoichiometric ratio of the reactants.9,12,41−45 However, the controllable synthesis of polymorphic sCOFs, more specifically, the controlled synthesis of sCOFs with diverse topologies, has been rarely studied. Herein, we report the polymorphic sCOFs fabricated by the reaction between 1,3,6,8-tetrakis(p-formylphenyl)pyrene (1) with D2h symmetry and ditopic diamine monomers (2, 3, 4) with different lengths (Scheme 1). Due to the reduced symmetry of the employed monomer (monomer 1) compared to typical monomers with C3 or C4 symmetry, polymorphic sCOFs are expected. Highly ordered covalent networks with the morphologies of the rhombus, parallelogram, and Kagome are disclosed by scanning tunneling microscope (STM). The product distribution can be tuned by adjusting the monomer concentration. The comparison between the polymorphic structures by on-surface synthesis and self-assembly points out that the reversibility of the dynamic covalent chemistry is the key for the concentration-controlled polymorphic sCOFs synthesis.

RESULTS AND DISCUSSION sCOFs Fabricated by Monomer 1 + 2. Figure 1a gives the representative STM image obtained by Schiff-base reaction between monomer 1 and 2 on highly oriented pyrolytic

Figure 1. (a) Large-scale STM image of polymorphic sCOFs obtained by monomer 1 + 2, revealing the coexisting rhombus (I), parallelogram (II), and Kagome (III) networks. (b) Highresolution STM image showing the boundary of parallelogram and Kagome morphological networks. Imaging conditions: Vbias = 700 mV, It = 500 pA. 11695


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Figure 2. Overview of the three morphological sCOFs formed by reaction between monomers 1 and 2. (a, c, e) High-resolution STM images of the rhombus, parallelogram, and Kagome morphological networks, respectively. (b, d, f) Structural models of the three morphological networks. Imaging conditions: Vbias = 700 mV, It = 500 pA.

Figure 3. Influence of monomer concentration on the growth of sCOFs by monomer 1 + 4. (a−d) STM images of the generated networks obtained at a monomer 1 concentrations of 1 × 10−4 mol/L; 2 × 10−5 mol/L; 4 × 10−6 mol/L; and 2 × 10−6 mol/L, respectively. (e) High-resolution STM image of Kagome morphological networks. Imaging conditions: Vbias = 700 mV, It = 500 pA.

1). Three morphological sCOFs, including rhombus, parallelogram, and Kagome networks, are all observed in both reaction systems (Figure S3 and Figure 3). By elongating the backbone of the diamine through adding phenyl groups one by one, a series of sCOFs with tunable pore size and periodicity are obtained, which have the potential to accommodate functional

guest molecules with different sizes. The unit cell parameters of each morphological sCOF determined from STM characterization are listed in Table 1, which show good consistency with the expected size predicted by structural modeling (given in parentheses in Table 1). These results unambiguously demonstrate the covalent bond formation. In the previous

Table 1. Structural Parameters of Rhombus, Parallelogram, and Kagome Morphological sCOFs Obtained by Reactions between Monomers 1 and 2, 3, 4 combination

structure

1+2

rhombus parallelogram Kagome rhombus parallelogram Kagome rhombus parallelogram Kagome

1+3

1+4

a (nm)a,b 2.5 2.3 4.7 2.8 2.8 5.7 3.3 3.2 6.6

± ± ± ± ± ± ± ± ±

0.2(2.45) 0.2(2.38) 0.2(4.77) 0.2(2.87) 0.2(2.81) 0.2(5.63) 0.2(3.29) 0.2(3.24) 0.2(6.49)

b (nm)a,b 2.5 2.5 4.9 2.9 2.9 5.8 3.3 3.4 6.6

± ± ± ± ± ± ± ± ±

0.2(2.45) 0.2(2.45) 0.2(4.77) 0.2(2.87) 0.2(2.87) 0.2(5.63) 0.2(3.29) 0.2(3.29) 0.2(6.49)

γ (deg)a,b 82 71 61 80 69 60 78 66 60

± ± ± ± ± ± ± ± ±

2(83) 2(70) 2(60) 2(79) 2(68) 2(60) 2(77) 2(67) 2(60)

Nc

area (nm2)d

D (nm−2)e

1 1 3 1 1 3 1 1 3

5.96 5.48 19.7 8.09 7.48 27.5 10.5 9.83 36.5

0.168 0.182 0.152 0.124 0.134 0.109 0.095 0.102 0.082

a

For the definition of the unit cell refer to Figure 2. bThe simulated value is given in parentheses. cNumber of tetraphenylpyrene-cored units per unit cell. dUnit cell area. eNetwork density (number of tetraphenylpyrene core/nm2). 11696


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A similar trend of product distribution on monomer concentration is disclosed in the cases of co-condensation of monomers 1 + 2 and 1 + 3. Statistical analysis (Figure 4) reveals that two types of quadrate networks are preferred at high concentration. Upon decreasing the monomer concentration, the occupancies of both rhombus and parallelogram networks fall, while the occupancy of Kagome networks increases. Representative STM images showing the concentration-dependent structure evolution in the product distribution are displayed in Figures S4 and S5. Discussion. The concentration-guided product distribution can be understood by thermodynamic analysis. The imine linkage employed for sCOF synthesis in this work is a classic dynamic covalent chemistry (DCC) reaction, which is reversible and controlled by thermodynamics. The spontaneous phase separation of rhombus, parallelogram, and Kagome networks is observed after reaction, which means that when three kinds of nuclei are formed simultaneously on the surface, the attached monomers can recognize the motifs of the nucleus and adjust themselves to grow to form the same morphological sCOFs exclusively. Such a process clearly demonstrates that the on-surface DCC is thermodynamically controlled and reversible. Taking the rhombus and parallelogram structures as examples, they differ each other only by the relative configuration of the imine bond around the monomer 1 core (Figure S2). If there are any mismatched motifs formed, the disordered structure would cause distortion of the bond length or bond angle (Figure S6) and therefore is thermodynamically unfavored. The reversibility of DCC makes it possible for products to undergo an “error-checking” or “proof-reading” process during the synthesis, which is crucial to obtaining wellordered 2D covalent networks. Previously, the self-sorting feature of dynamic covalent bonds to form only one or a small subset out of many possible structures has been widely demonstrated in the construction of macrocycles or organic cages in the solution phase.50 Herein, this self-sorting process guarantees the formation of highly ordered polymorphic nanostructures. Next, we address the concentration-controlled polymorphic structure distribution. For any pair of monomers, three structures have the same number of covalent bonds after reaction and therefore roughly have the same chemical free energy. The concentration-guided product distribution on surface synthesis is presumably related to the differences in the network density of the three kinds of networks. The reaction is carried out under equilibrium control, and the chemical potential of the surface-supported structures after reaction can be described by51,52

report, a longer diamine molecule results in a decreased domain size of the desired sCOFs and the formation of disordered structures when reacting with tetradentate precursors with tetrathiafulvalene (TTF) as backbone.49 However, high-quality networks with few disordered structures or defects are acquired independent of the length of the linear diamine monomers in this study. Concentration Effect on the Product Distribution. Next, we explore the effect of monomer concentration on the product distribution. Taking the reaction between monomers 1 and 4 as an example, by keeping the molar ratio of the two building blocks constant (aldehyde:amine = 1:2), a clear dependence of the product distribution on the monomer concentration is disclosed. Figure 3 displays typical STM images acquired at four different concentrations. Statistical analysis of the concentration-dependent occupancy of the three morphological networks is summarized in Figure 4. The

Figure 4. Histogram showing the concentration-dependent occupancy of the three morphological networks: rhombus (cyan), parallelogram (violet), and Kagome (magenta).

occupancy of each sCOF is calculated by dividing the area of each morphological network by the area of all kinds of structures, which provides a measure of relative structure ratio of each morphological network. At an aldehyde concentration of 1 × 10−4 mol/L, two types of quadrate networks are the major products (Figure 3a). The occupancies of rhombus and parallelogram networks are 41% and 59%, respectively (Figure 4, Table S2). The Kagome network appears at an aldehyde concentration of 2 × 10−5 mol/L with the occupancy of 6%. Small domains of Kagome networks can be seen in Figure 3b (marked by white dashed circles). Upon decreasing the monomer concentration, the Kagome network becomes the dominant product (60% at an aldehyde concentration of 4 × 10−6 mol/L) with decreasing coverage of both rhombus and parallelogram morphological networks (Figure 3c). And the occupancy of the Kagome network reaches 89% at the lowest concentration probed (2 × 10−6 mol/L for the aldehyde monomer), as shown in Figure 3d. Figure 3e shows a magnified STM image of Kagome morphological networks in Figure 3d. Highly ordered Kagome lattices with triangular and hexagonal pores are disclosed.

μs ∼

∑ γi[nm−2] × Ai i

where γi is the free energy per unit area of the ith morphological sCOF and Ai is the area occupied by the ith morphological sCOF. Here, the free energy density is used to describe the free energy of the product on the surface. As the reaction is under thermodynamic control, the chemical potential of the monomer and substrate is at equilibrium during the reaction. As we increase the concentration of monomers, which increases the chemical potential of the reactants, the structure with a higher free energy density would be favored. As each structure has the same number of covalent bonds per monomer 1, the free energy density is proportional to the network density (D), i.e., the number of molecules 1 per 11697


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dynamic reaction, owing to its reversible nature, implies other cues could to be used to achieve tailored synthesis of wellordered surface covalent nanostructures.

area, which can be calculated by dividing the unit cell acreage by the number of molecules in every unit cell. Table 1 summarizes the network density of each morphological sCOF obtained by reactions between monomers 1 and 2, 3, 4. For a given diamine monomer, the Kagome sCOFs have a smaller network density than the rhombus and parallelogram sCOFs. The experimental results show that decreasing the monomer concentration favors the formation of Kagome sCOFs. The tendency of forming networks from high packing density to low packing density upon diluting is consistent with the above thermodynamic analysis. The concentration effect on polymorphic self-assembly nanostructures has been explored intensively. It has been shown that the lower the concentration, the larger the chance to obtain a low-density assembly, which is confirmed to be a general phenomenon in concentrationdependent supramolecular assembly.34−36 In this study, we find that the same tendency also applies to the on-surface synthesis of covalent bond connected networks through dynamic covalent chemistry. In particular, it is noted that three polymorphic structures in the present system are almost isoenergetic, as there is almost no involvement of weak intermolecular interactions. In contrast, the polymorphic assemblies are generally driven by different combinations of intermolecular interactions and therefore have small free energy difference. The key to obtain highly ordered polymorphic structures is equilibrium control. In this work, we employ CuSO4·5H2O powder as thermodynamic regulation agent to improve the reversibility of the dehydration reaction.4 As a control experiment, the polymerization of monomers 1 and 4 without the presence of water results in the formation of disordered products (Figure S7). In addition, reaction temperature also plays an important role. If we reduce the reaction temperature to 110 °C, three morphological sCOFs are still observed after on-surface reaction but with significantly decreased domain size and quality (Figure S8). This may be related with the decreased molecular diffusion rate at the low reaction temperature. We have investigated the influence of molecular ratio on the growth of polymorphic sCOFs as well. Deviation from the stoichiometric ratio results in a large number of defects in the formed networks or linear byproduct as displayed in Figure S9 (see SI for details).

METHODS 1,3,6,8-Tetrakis(p-formylphenyl)pyrene (1) was synthesized according to the reported procedures. Its 1H NMR and 13C NMR spectra match well with those reported in related literature.53 p-Phenylenediamine (2) was purchased from Acros. Benzidine dihydrochloride (3) was bought from Sigma, and 4,4″-diamino-p-terphenyl (4) was acquired from TCI. Tetrahydrofuran (THF) was purchased from TCI. All the chemicals used in the present work, unless otherwise specified, were used without any further purification. In a typical synthesis procedure, 1,3,6,8-tetrakis(p-formylphenyl)pyrene (1) was mixed with linear diamine building blocks (benzidine dihydrochloride (3) or 4,4″-diamino-p-terphenyl (4)) in THF in a stoichiometric ratio. Then a 5 μL solution containing two building blocks was deposited onto the surface of freshly cleaved HOPG. About 1.1 g of CuSO4·5H2O powder was preloaded in the 100 mL Teflonsealed autoclave to serve as chemical equilibrium regulation agent. Next, the HOPG loaded with reaction monomers was transferred into the autoclave as well and heated at 120 °C for 3 h, while in the case of p-phenylenediamine (2), the powder was added to the bottom of the 100 mL autoclave instead of dissolved in solution. STM characterization was carried out after cooling to room temperature. STM experiments were performed under ambient conditions with mechanically cut Pt/Ir wires (90:10) by NanoscopeIIIa SPM (Bruker Nano). All the images were recorded in constant-current mode and are shown without further processing. The statistical analysis was conducted by analyzing more than 20 STM images for each reaction at different concentrations. The STM images were collected from random positions of the surface for every sample. The occupancy of each structure was calculated by dividing the area of each morphological network by the area of all kinds of structures, and the error bar was obtained by calculating the standard deviation of the data.

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acsnano.7b06871. Detailed structural analysis indicating the difference between two quadrate networks as well as the occupancy of each morphological sCOF at various monomer concentrations and supplementary STM figures (PDF)

CONCLUSION In summary, we demonstrate the polymorphic sCOFs via onsurface Schiff base reaction between D2h monomer 1 and ditopic diamine precursors. High-quality covalent networks with the morphologies of rhombus, parallelogram, and Kagome are observed on a graphite surface. By varying the backbone length of the ditopic building blocks, a series of covalent networks with tunable pore size and periodicity are fabricated. It is well established that concentration control is a general and powerful approach for structural selection in supramolecular assembly, and we find it can also be applied to the polymorphic-controlled on-surface synthesis of covalent bond connected networks based on dynamic covalent bonds. Two types of quadrate networks are predominant products at relatively high concentration, and their occupancies decrease upon diluting. The intriguing Kagome networks are biased to form under dilute conditions. The present study broadens the structural diversity of sCOFs depending on the rational design of precursors. The similarity in concentration-controlled polymorphism in supramolecular assembly and on-surface

AUTHOR INFORMATION Corresponding Author

*E-mail: [email protected]. ORCID

Dong Wang: 0000-0002-1649-942X Notes

The authors declare no competing financial interest.

ACKNOWLEDGMENTS This work is supported by National Natural Science Foundation of China (Grants 21433011, 91527303), the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB12020100), and the National Basic Research Program (2017YFA024702). REFERENCES (1) Liu, X. H.; Guan, C. Z.; Wang, D.; Wan, L. J. Graphene-Like Single-Layered Covalent Organic Frameworks: Synthesis Strategies and Application Prospects. Adv. Mater. 2014, 26, 6912−6920. 11698


Article

ACS Nano (2) Perepichka, D. F.; Rosei, F. Extending Polymer Conjugation into the Second Dimension. Science 2009, 323, 216−217. (3) Baughman, R. H.; Eckhardt, H.; Kertesz, M. Structure-Property Predictions for New Planar Forms of Carbon: Layered Phases Containing sp2 and sp Atoms. J. Chem. Phys. 1987, 87, 6687−6699. (4) Abraham, F. F.; Nelson, D. R. Diffraction from Polymerized Membranes. Science 1990, 249, 393−398. (5) Adjizian, J. J.; Briddon, P.; Humbert, B.; Duvail, J. L.; Wagner, P.; Adda, C.; Ewels, C. Dirac Cones in Two-Dimensional Conjugated Polymer Networks. Nat. Commun. 2014, 5, 5842−5851. (6) Zwaneveld, N. A.; Pawlak, R.; Abel, M.; Catalin, D.; Gigmes, D.; Bertin, D.; Porte, L. Organized Formation of 2D Extended Covalent Organic Frameworks at Surfaces. J. Am. Chem. Soc. 2008, 130, 6678− 6679. (7) Liu, X. H.; Guan, C. Z.; Ding, S. Y.; Wang, W.; Yan, H. J.; Wang, D.; Wan, L. J. On-Surface Synthesis of Single-Layered TwoDimensional Covalent Organic Frameworks via Solid-Vapor Interface Reactions. J. Am. Chem. Soc. 2013, 135, 10470−10474. (8) Xu, L.; Zhou, X.; Yu, Y.; Tian, W. Q.; Ma, J.; Lei, S. SurfaceConfined Crystalline Two-Dimensional Covalent Organic Frameworks via on-Surface Schiff-Base Coupling. ACS Nano 2013, 7, 8066− 8073. (9) Liu, X. H.; Mo, Y. P.; Yue, J. Y.; Zheng, Q. N.; Yan, H. J.; Wang, D.; Wan, L. J. Isomeric Routes to Schiff-Base Single-Layered Covalent Organic Frameworks. Small 2014, 10, 4934−4939. (10) Liu, X. H.; Guan, C. Z.; Zheng, Q. N.; Wang, D.; Wan, L. J. Molecular Engineering of Schiff-Base Linked Covalent Polymers with Diverse Topologies by Gas-Solid Interface Reaction. J. Chem. Phys. 2015, 142, 101905−101909. (11) Yue, J. Y.; Liu, X. H.; Sun, B.; Wang, D. The on-Surface Synthesis of Imine-Based Covalent Organic Frameworks with NonAromatic Linkage. Chem. Commun. 2015, 51, 14318−14321. (12) Gong, Z. M.; Yang, B.; Lin, H. P.; Tang, Y. Y.; Tang, Z. Y.; Zhang, J. J.; Zhang, H. M.; Li, Y. Y.; Xie, Y. S.; Li, Q.; Chi, L. F. Structural Variation in Surface-Supported Synthesis by Adjusting the Stoichiometric Ratio of the Reactants. ACS Nano 2016, 10, 4228− 4235. (13) Hu, Y.; Goodeal, N.; Chen, Y.; Ganose, A. M.; Palgrave, R. G.; Bronstein, H.; Blunt, M. O. Probing the Chemical Structure of Monolayer Covalent-Organic Frameworks Grown via Schiff-Base Condensation Reactions. Chem. Commun. 2016, 52, 9941−9944. (14) Yu, Y.; Lin, J.; Wang, Y.; Zeng, Q.; Lei, S. Room Temperature on-Surface Synthesis of Two-Dimensional Imine Polymers at the Solid/Liquid Interface: Concentration Takes Control. Chem. Commun. 2016, 52, 6609−6612. (15) Mo, Y. P.; Liu, X. H.; Sun, B.; Yan, H. J.; Wang, D.; Wan, L. J. The Intramolecular H-Bonding Effect on the Growth and Stability of Schiff-Base Surface Covalent Organic Frameworks. Phys. Chem. Chem. Phys. 2017, 19, 539−543. (16) Souslov, A.; Liu, A. J.; Lubensky, T. C. Elasticity and Response in Nearly Isostatic Periodic Lattices. Phys. Rev. Lett. 2009, 103, 205503. (17) Sun, K.; Souslov, A.; Mao, X. M.; Lubensky, T. C. Surface Phonons, Elastic Response, and Conformal Invariance in Twisted Kagome Lattices. Proc. Natl. Acad. Sci. U. S. A. 2012, 109, 12369− 12374. (18) Björkman, T.; Skakalova, V.; Kurasch, S.; Kaiser, U.; Meyer, J. C.; Smet, J. H.; Krasheninnikov, A. V. Vibrational Properties of a TwoDimensional Silica Kagome Lattice. ACS Nano 2016, 10, 10929− 10935. (19) Chalker, J. T.; Holdsworth, P. C.; Shender, E. F. Hidden Order in a Frustrated System: Properties of the Heisenberg Kagome Antiferromagnet. Phys. Rev. Lett. 1992, 68, 855−858. (20) Greedan, J. E. Geometrically Frustrated Magnetic Materials. J. Mater. Chem. 2001, 11, 37−53. (21) Grohol, D.; Matan, K.; Cho, J. H.; Lee, S. H.; Lynn, J. W.; Nocera, D. G.; Lee, Y. S. Spin Chirality on a Two-Dimensional Frustrated Lattice. Nat. Mater. 2005, 4, 323−328.

(22) Moulton, B.; Lu, J.; Hajndl, R.; Hariharan, S.; Zaworotko, M. J. Crystal Engineering of a Nanoscale Kagomé Lattice. Angew. Chem., Int. Ed. 2002, 41, 2821−2824. (23) Furukawa, S.; Uji-i, H.; Tahara, K.; Ichikawa, T.; Sonoda, M.; De Schryver, F. C.; Tobe, Y.; De Feyter, S. Molecular Geometry Directed Kagomé and Honeycomb Networks: Toward Two-Dimensional Crystal Engineering. J. Am. Chem. Soc. 2006, 128, 3502−3503. (24) Tahara, K.; Furukawa, S.; Uji-i, H.; Uchino, T.; Ichikawa, T.; Zhang, J.; Mamdouh, W.; Sonoda, M.; De Schryver, F. C.; De Feyter, S. Two-Dimensional Porous Molecular Networks of Dehydrobenzo [12] annulene Derivatives via Alkyl Chain Interdigitation. J. Am. Chem. Soc. 2006, 128, 16613−16625. (25) Schlickum, U.; Decker, R.; Klappenberger, F.; Zoppellaro, G.; Klyatskaya, S.; Auwarter, W.; Neppl, S.; Kern, K.; Brune, H.; Ruben, M. Chiral Kagomé Lattice from Simple Ditopic Molecular Bricks. J. Am. Chem. Soc. 2008, 130, 11778−11782. (26) Shi, Z.; Lin, N. Porphyrin-Based Two-Dimensional Coordination Kagome Lattice Self-Assembled on a Au (111). J. Am. Chem. Soc. 2009, 131, 5376−5377. (27) Shi, Z.; Lin, N. Structural and Chemical Control in Assembly of Multicomponent Metal−Organic Coordination Networks on a Surface. J. Am. Chem. Soc. 2010, 132, 10756−10761. (28) Wang, T.; Fan, Q.; Feng, L.; Tao, Z.; Huang, J.; Ju, H.; Xu, Q.; Hu, S.; Zhu, J. Chiral Kagome Lattices from on-Surface Synthesized Molecules. ChemPhysChem 2017, DOI: 10.1002/cphc.201700769. (29) Zhou, T. Y.; Xu, S. Q.; Wen, Q.; Pang, Z. F.; Zhao, X. One-Step Construction of Two Different Kinds of Pores in a 2D Covalent Organic Framework. J. Am. Chem. Soc. 2014, 136, 15885−15888. (30) Ascherl, L.; Sick, T.; Margraf, J. T.; Lapidus, S. H.; Calik, M.; Hettstedt, C.; Karaghiosoff, K.; Döblinger, M.; Clark, T.; Chapman, K. W.; Auras, F.; Bein, T. Molecular Docking Sites Designed for the Generation of Highly Crystalline Covalent Organic Frameworks. Nat. Chem. 2016, 8, 310−316. (31) Dalapati, S.; Jin, E.; Addicoat, M.; Heine, T.; Jiang, D. L. Highly Emissive Covalent Organic Frameworks. J. Am. Chem. Soc. 2016, 138, 5797−5800. (32) Pang, Z. F.; Xu, S. Q.; Zhou, T. Y.; Liang, R. R.; Zhan, T. G.; Zhao, X. Construction of Covalent Organic Frameworks Bearing Three Different Kinds of Pores through the Heterostructural Mixed Linker Strategy. J. Am. Chem. Soc. 2016, 138, 4710−4713. (33) Zhu, Y.; Wan, S.; Jin, Y.; Zhang, W. Desymmetrized Vertex Design for the Synthesis of Covalent Organic Frameworks with Periodically Heterogeneous Pore Structures. J. Am. Chem. Soc. 2015, 137, 13772−13775. (34) Lei, S.; Tahara, K.; De Schryver, F. C.; Van der Auweraer, M.; Tobe, Y.; De Feyter, S. One Building Block, Two Different Supramolecular Surface-Confined Patterns: Concentration in Control at the Solid-Liquid Interface. Angew. Chem., Int. Ed. 2008, 47, 2964− 2968. (35) Tahara, K.; Okuhata, S.; Adisoejoso, J.; Lei, S.; Fujita, T.; Feyter, S. D.; Tobe, Y. 2D Networks of Rhombic-Shaped Fused Dehydrobenzo [12] annulenes: Structural Variations under Concentration Control. J. Am. Chem. Soc. 2009, 131, 17583−17590. (36) Kampschulte, L.; Werblowsky, T. L.; Kishore, R. S.; Schmittel, M.; Heckl, W. M.; Lackinger, M. Thermodynamical Equilibrium of Binary Supramolecular Networks at the Liquid−Solid Interface. J. Am. Chem. Soc. 2008, 130, 8502−8507. (37) Meier, C.; Roos, M.; Künzel, D.; Breitruck, A.; Hoster, H. E.; Landfester, K.; Gross, A.; Behm, R. J.; Ziener, U. Concentration and Coverage Dependent Adlayer Structures: From Two-Dimensional Networks to Rotation in a Bearing. J. Phys. Chem. C 2010, 114, 1268− 1277. (38) Thi Ngoc Ha, N.; Gopakumar, T. G.; Hietschold, M. Polymorphism Driven by Concentration at the Solid−Liquid Interface. J. Phys. Chem. C 2011, 115, 21743−21749. (39) Silly, F. Two-Dimensional 1,3,5-Tris(4-carboxyphenyl)benzene Self-Assembly at the 1-Phenyloctane/Graphite Interface Revisited. J. Phys. Chem. C 2012, 116, 10029−10032. 11699


Article

ACS Nano (40) Silly, F. Concentration-Dependent Two-Dimensional HalogenBonded Self-Assembly of 1,3,5-Tris(4-iodophenyl)benzene Molecules at the Solid−Liquid Interface. J. Phys. Chem. C 2017, 121, 10413− 10418. (41) Blunt, M. O.; Russell, J. C.; Champness, N. R.; Beton, P. H. Templating Molecular Adsorption Using a Covalent Organic Framework. Chem. Commun. 2010, 46, 7157−7159. (42) Zhang, Y. Q.; Kepcija, N.; Kleinschrodt, M.; Diller, K.; Fischer, S.; Papageorgiou, A. C.; Allegretti, F.; Bjork, J.; Klyatskaya, S.; Klappenberger, F.; Ruben, M.; Barth, J. V. Homo-Coupling of Terminal Alkynes on a Noble Metal Surface. Nat. Commun. 2012, 3, 1286−1293. (43) Eichhorn, J.; Nieckarz, D.; Ochs, O.; Samanta, D.; Schmittel, M.; Szabelski, P. J.; Lackinger, M. On-Surface Ullmann Coupling: The Influence of Kinetic Reaction Parameters on the Morphology and Quality of Covalent Networks. ACS Nano 2014, 8, 7880−7889. (44) Peyrot, D.; Silly, F. On-Surface Synthesis of Two-Dimensional Covalent Organic Structures versus Halogen-Bonded Self-Assembly: Competing Formation of Organic Nanoarchitectures. ACS Nano 2016, 10, 5490−5498. (45) Liu, C.; Yu, Y.; Zhang, W.; Zeng, Q.; Lei, S. Room-Temperature Synthesis of Covalent Organic Frameworks with a Boronic Ester Linkage at the Liquid/Solid Interface. Chem. - Eur. J. 2016, 22, 18412− 18418. (46) Dalapati, S.; Jin, S.; Gao, J.; Xu, Y. H.; Nagai, A.; Jiang, D. L. An Azine-Linked Covalent Organic Framework. J. Am. Chem. Soc. 2013, 135, 17310−17313. (47) Rabbani, M. G.; Sekizkardes, A. K.; Kahveci, Z.; Reich, T. E.; Ding, R.; El-Kaderi, H. M. A 2D Mesoporous Imine-Linked Covalent Organic Framework for High Pressure Gas Storage Applications. Chem. - Eur. J. 2013, 19, 3324−3328. (48) Wu, Y.; Xu, H.; Chen, X.; Gao, J.; Jiang, D. L. A π-Electronic Covalent Organic Framework Catalyst:π-Walls as Catalytic Beds for Diels-Alder Reactions under Ambient Conditions. Chem. Commun. 2015, 51, 10096−10098. (49) Dong, W. L.; Wang, L.; Ding, H. M.; Zhao, L.; Wang, D.; Wang, C.; Wan, L. J. Substrate Orientation Effect in the on-Surface Synthesis of Tetrathiafulvalene-Integrated Single-Layer Covalent Organic Frameworks. Langmuir 2015, 31, 11755−11759. (50) Wu, A.; Isaacs, L. Self-Sorting: The Exception or the Rule? J. Am. Chem. Soc. 2003, 125, 4831−4835. (51) Xiao, W.; Feng, X.; Ruffieux, P.; Gröning, O.; Müllen, K.; Fasel, R. Self-Assembly of Chiral Molecular Honeycomb Networks on Au (111). J. Am. Chem. Soc. 2008, 130, 8910−8912. (52) Palma, C. A.; Bjork, J.; Bonini, M.; Dyer, M. S.; Llanes Pallas, A.; Bonifazi, D.; Persson, M.; Samorì, P. Tailoring Bicomponent Supramolecular Nanoporous Networks: Phase Segregation, Polymorphism, and Glasses at the Solid-Liquid Interface. J. Am. Chem. Soc. 2009, 131, 13062−13071. (53) Rabbani, M. G.; Sekizkardes, A. K.; El-Kadri, O. M.; Kaafarani, B. R.; El-Kaderi, H. M. Pyrene-Directed Growth of Nanoporous Benzimidazole-Linked Nanofibers and Their Application to Selective CO2 Capture and Separation. J. Mater. Chem. 2012, 22, 25409−25417.

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