Intermediate States Directed Chiral Transfer on a Silver Surface

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Intermediate States Directed Chiral Transfer on a Silver Surface Biao Yang, Nan Cao, Huanxin Ju, Haiping Lin, Youyong Li, Honghe Ding, Jinqiang Ding, Junjie Zhang, Chencheng Peng, Haiming Zhang, Junfa Zhu, Qing Li, and Lifeng Chi J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.8b05699 • Publication Date (Web): 24 Nov 2018 Downloaded from http://pubs.acs.org on November 24, 2018

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Journal of the American Chemical Society

Intermediate States Directed Chiral Transfer on a Silver Surface Biao Yang,1 Nan Cao,1 Huanxin Ju,2 Haiping Lin,*,1 Youyong Li,1 Honghe Ding,2 Jinqiang Ding,1 Junjie Zhang,1 Chencheng Peng,1 Haiming Zhang,1 Junfa Zhu,2 Qing Li,*,1 Lifeng Chi*,1 Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, 199 Ren’ai Road, Suzhou 215123, P. R. China 2National Synchrotron Radiation Laboratory and Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China, Hefei, Anhui 230029, China 1

ABSTRACT: Chiral synthesis on surfaces has acquired tremendous interests. We herein report a novel approach of twodimensional chiral transfer directed by metal-organic intermediate states on a silver surface. With initial deposition at low temperature, the achiral 4,4'-dihydroxybiphenyl molecules self-assemble into large scale two-dimensional networks with four-fold symmetry via intermolecular hydrogen bonding. Fine controlled annealing, however, leads to the formation of tetramer-like chiral metal-organic hybrids, which self-organize into enantiomeric islands on the Ag(100) surface. Subsequent ortho C-C couplings of the reactants lead to dimer products. Of great importance, the chirality expressions of the dimer products are observed to be transferred directly from that of the tetramer intermediate states. The detailed reaction pathways are rationalized by DFT calculations and synchrotron-based XPS experiments, demonstrating the mechanisms of the chiral transfer.

INTRODUCTION Molecular chirality describes the phenomenon of symmetry broken in molecular structures. The two non-superimposable mirror-images structures are referred to as molecular enantiomers. Although the enantiomers have nearly identical physical properties, their difference can commonly be distinguished by biological systems, simply because that all lives are in chiral environments. Correspondingly, in general, only one of the enantiomers can properly fit into the chiral receptor sites of biological systems, the others produce no effect or even toxic effect due to inappropriate molecular recognition. Thus, the creation of chiral environments has been regarded as the key in chiral synthesis to selectively obtain enantiomeric pure compounds in the development of pharmaceuticals and agrochemicals.1-3 In the recent decade, producing and tuning two-dimensional chirality by means of molecular self-assemblies has been a focus of interests, since it provides a feasible means of inducing enormous diversity of chirality on solid state surfaces. To date, a number of achiral molecules have been reported to form enantiomeric domains with local surface chirality due to the twist of molecular backbones and the selfassembly via intermolecular interactions.4-15 Researches toward the surface chirality, have two layer of meanings: (i) to form globally homochiral surface self-assembly networks, and (ii) the synthesis of chiral products, which are connected via the robust covalent bonds. In the past few years, several approaches have been successfully developed to achieve the global surface chirality, e.g. by means of introducing small amount of chiral seeds, which is known as the “sergeants and soldier” strategy.16-20 On the contrary, the synthesis of covalently connected chiral products on surfaces still remains challenging. Considering the success in controlling the chirality of the molecular self-assembly, one candidate strategy is the direct transfer of the chiral information of the

molecular packing of reactants to the products with the newly developed on-surface synthesis techniques. On-surface synthesis, which combines the scanning tunneling microscopy (STM) and ultra-high vacuum techniques (UHV), has been considered as a powerful tool for the constructing of on-surface structures at the molecular level. With this, several reactions have been realized on surfaces, such as Ullmann coupling,21-26 Glaser coupling,27-28 boronic acid condensation,29-31 imine formation32-33 and coupling of alkanes via C-H activations.34-35 In general, activation barriers on metal surfaces can be effectively reduced because of both the metal catalysis and the confinement effects (e.g. increase the meeting probability of the reactants).36-40 More importantly, in certain situation, the reaction products are closely related with the self-assembled structures of the precursors.41-42 In this regard, it provides the possibility to transfer the chiral information of the selfassembled islands to the reaction products. To date, only few studies have been reported towards the chiral transfer on surfaces.43-44 The difficulties arise from the harsh requirements of relative steric placement of the precursors to maintain the overall self-assembled structures during the surface reactions, which is essential for the printing of the chiral information. Scheme 1. (a, b) Scheme of transfer of the chiral information from the tetramer intermediate states to the dimer reaction products.

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indicate that the porous islands are stabilized by intermolecular hydrogen bonds between the hydroxyl groups of DHBPs. Subsequent annealing of the sample at 520 K for 20 minutes results in various dimer products, randomly dispersed on the silver surface, as shown in Figure 1c (Larger scale STM images can be seen in Figure S2). The dimers are formed through the thermally triggered mono-selective ortho C-H bond activations of phenols on silver surfaces.36 The structural models of the three representative products are given in Figure 1d, and we refer them to as the right rotated dimer (“R” dimer), the bridge-like dimer (“B” dimer), and the left rotated dimer (“L” dimer), respectively. As shown, direct heating at 520 K exhibit poor selectivity of the dimer products (see Figure S3 for details). Herein, we proposed a two-step strategy for the transferring of the chiral information on a Ag(100) surface. By introducing an achiral phenol derivative 4,4'-dihydroxybiphenyl (DHBP) on Ag(100) surface (inset in Figure 1a), we found a direct heating of the DHBPs covered surface to 520 K leads to various dimer products, randomly dispersed on the silver surface, showing very poor reaction selectivity. On the contrary, unified tetramer-like metal-organic hybrids intermediate states can be formed via an initial annealing of the surface at 490 K, through the dehydrogenation reaction of the hydroxyl groups in DHBPs. The tetramers are observed to form chiral islands via hydrogen bonds. Subsequent ortho phenyl C-H bond activations and C-C bond couplings lead to well selected and arranged dimer products. Most importantly, the entire manner of molecular self-assembly maintains unchanged during the reactions, so that the chirality expressions of the newly formed dimers are inherited from their respective tetramer intermediate structures (Scheme 1). This way, we have successfully achieved the transfer of the chiral information from the tetramer intermediates to the reaction products on the Ag(100) surfaces. Finally, the detailed reaction pathways are rationalized by density function theory (DFT) calculations and synchrotron-based XPS experiments, which demonstrate the mechanism of the chiral transfer.

RESULTS AND DISCUSSION When deposition on a clean Ag(100) surface held at 200 K, the DHBP molecules self-assemble into porous network structures with a four-fold symmetry. The long axis of the monomers points to one of the [011] directions, as depicted in Figure 1a. Phenols are known to show their pristine configurations on Au(111) surfaces at room temperature.36 We obtained the STM topographic image after depositing DHPBs onto a Au(111) surface, as shown in Figure S1b, which resembles to the STM image after adsorption of DHBPs on a Ag(100) surface held at 200 K. We thus hypothesis that the rods shown in Figure 1a can be attributed to the primary DHBP monomers. The eventual evidence of the state of the self-assembly components is provided by the XPS measurements, which will be discussed later (Figure 5). The DFT optimized structure of the self-assembly island in gas phase is given in Figure 1b, exhibiting excellent square shaped porous network (The calculation details can be found in Methods part of the Supporting Informations). The calculated pore-to-pore distance is 1.37 nm, which agrees well with the experimental observations (1.40 ± 0.05 nm). Calculations

Figure 1. (a) Self-assembly of DHBPs after deposition on a clean Ag(100) surface held at 200 K. The inset gives the structure model of the DHBP molecule. (b) The gas phase relaxed structural model of the self-assembly structure depicted in (a). (c) Representative STM image after annealing the sample at 520 K for 20 minutes. (d) The structural models of the three representative dimer products depicted in (c). Tunneling parameters are It = 100 pA, Vb = -100 mV for (a); It = 20 pA, Vb = -1 V for (c). Image size is 10 nm × 10 nm for both (a) and (c).

On the other hand, when the alternative thermal treatment is applied, the regular arrangement of the intermediate states is observed. Dramatic structural evolutions take place by annealing the surface shown in Figure 2a at room temperature (300 K). As shown in Figure 2b, the island exhibits double line molecular chains (marked with red rectangles, along the [010] direction) decorated with isolated rods in between (marked with black rectangles, along the [0-11] direction). Subsequent annealing of the sample at 370 K leads to close packed islands, in which all the constitute monomers have unified orientations running along the [010] direction (Figure 2c). According to our previous STM and XPS studies,36 the coupling of phenols on Ag(111) surfaces are initiated by the dehydrogenation reactions of hydroxyl groups. We therefore assumed the structural evolutions from Figure 2a to Figure 2c) to the successive dehydrogenation reactions of DHBPs. This hypothesis is further confirmed by the XPS measurement (Figure 5), which will be discussed later. In Figure 2c, all the

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Journal of the American Chemical Society monomers aggregate via a unified head-to-tail fashion, suggesting the complete dehydrogenation of the hydroxyl groups (the corresponding structural model is given in Figure 2g). Considering the similarity between the molecular chains in Figure 2b and the molecular packing in Figure 2c, we proposed the structural model after annealing at 300 K, as shown in Figure 2f. The [010] direction oriented chain components (Figure 2b) can be ascribed to the dehydrogenated DHBPs, and the [0-11] direction oriented rods in between the chains are the pristine ones. This structural model agrees with the XPS observations that partial dehydrogenation of phenols takes place on Ag(100) surfaces at room temperature (Figure 5). A new phase is observed upon further annealing of the sample to 490 K. As shown in Figure 2d, the self-assembled island composes of unified windmill-like tetramers. Each tetramer structure is consisted of four dehydrogenated DHBP molecules that coordinate with a single silver adatom locating at the tetramer center, as shown in Figure 2h. Note that all these phases can extend to large islands on the surfaces (See Figure S4). Although oligomers formed via the oxygen-Cu/Fe coordination have been studied previously,45-48 to the best of our knowledge, the O-Ag coordinated organic complexes have not been reported under UHV.

Figure 2. (a-d) STM images after appropriate annealing. The image sizes are 7 nm × 7 nm for all the images. The annealing temperatures are 200 K for (a); 300 K for (b); 370 K for (c); and 490 K for (d). Tunneling parameters are It = 100 pA, Vb = -100 mV for (a) and (c); It = 100 pA, Vb = -500 mV for (b); It = 20 pA, Vb = -200 mV for (d). (e-h) The corresponding schematic structural models of the STM images shown in (a) to (d), respectively.

Both the tetramer intermediate states and the corresponding self-assembled structures (Figure 3b) are of chirality. We therefore name the tetramer intermediate states according to their chiral configurations: the clockwise “C” and the anticlockwise “AC”, respectively (Figure 3a). The asymmetric packing of the tetramers can be recognized from the STM images (Figure 3b), in which we mark the two homochiral domains as “R” and “L”, respectively. The unit cell parameters are a = b= 1.70 ± 0.05 nm for both chiral domains. It is straightforward to conclude that the “R” domains are composed exclusively of “C” tetramers, and the “L” domains are composed exclusively of “AC” tetramers. In both the “R” and “L” domains, the long axis of the DHBP components of the tetramers points along the [011] or [0-11] direction. As a consequence, the unit cell of the “R”/“L” domains deviate +60º/-60º from the [011] or [0-11] direction, respectively, as shown in Figure 3b. The domains of enantiomeric tetramer islands could extend over hundred nanometers on the Ag(100) (see Figure S5 for details).

Figure 3. The process of chiral transfer directed by intermediate states. (a) High-resolution STM images of the enantiomeric windmill-like tetramers and their corresponding structural models. (b) Enantiomeric self-assembled domains composed of “C” tetramers and “AC” tetramers, respectively. (c) The initial ortho phenyl C-C bonds coupling take place after annealing the sample at 520 K for 10 minutes. The insets give the high-resolution STM images of the mirror symmetric dimers. (d) Regular enantiomeric packings of the dimer products after annealing the sample at 520 K for 30 minutes. The image sizes of (b-d) are 19 nm × 7 nm. Tunneling parameters are It = 20 pA, Vb = -200 mV for left panel of (a-d) and It = 20 pA, Vb = -1 V for right panel of (a-d).

Different from the randomly dispersed/selected dimer products shown in Figure 1c, we have been able to produce well selected chiral products assisted by the formation of the tetramer intermediate states. The initial ortho phenyl C-C bond couplings takes place after annealing the sample shown in Figure 3b at 520 K for 10 minutes. In both the “R” and “L” domains, biphenyls start to connect with each other, which can be evidenced by the bright protrusions in the STM topographic image (Figure 3c). More importantly, one can only find “R” dimer products in the “R” domains, and only the “L” dimer products in the “L” domains, respectively. Annealing the surface at 520 K for longer time leads to further ortho phenyl C-C bond couplings, and eventually results in the regular and enantiomeric packing of the dimer products (Figure 3d). This way, “R” dimers and “L” dimers are successfully synthesized and separated into different domains on the Ag(100) surface. The unit cell parameters are a = 3.55 ± 0.05 nm, b = 3.20 ± 0.05 nm, α=70 ± 5° for both of the two domains. Importantly, the formation of “B” dimer byproducts (Figure 1d) has been entirely prohibited, suggesting excellent reaction selectivity with this tetramer intermediate states directed reaction strategy.



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between the adjacent “R” dimer products is the same as that between the adjacent “C” tetramers (1.7 nm). Since the chiral transfer relies on the maintaining of the self-assemble intermediate structure, the size of the homochiral domain of the reaction products should be comparable to the scale of the tetramer self-assembly. We actually do obtain large scale chiral separation of the dimer products with our two-step strategy, as shown in Figure S6.

Figure 4. Intermediate states directed chiral transfer mechanism. (a) Self-assembly STM image of tetramer-like metal-organic hybrids intermediate states intercepted from “R” domain. (c) STM image of the intercepted dimer row. (b) and (d) The illustrations corresponding to (a) and (c), respectively.

All these phenomena strongly suggest the chiral information of the tetramer intermediate states has been successfully transferred to the newly formed dimer products. In general, large scale chiral transfer is difficult to achieve because of the harsh requirements: the active sites of the reaction precursors should be close enough to each other, and should have suitable relative orientations and distances during the reactions. In this work, the metal-organic hybrid intermediated state not only plays a role in directing the chiral self-organization DHBP monomers, but also helps to maintain the self-assembly structures during the reaction. In this way, the chiral expression of the reaction products can directly be determined by the chiral nature of the intermediate state. Moreover, the printing of the chiral information is not interrupted due to the collapse of the self-assembled islands. To this end, we look back to the initial coupling of the DHBPs after the formation of tetramer intermediate states. Figure 4a depicts a section of the “R” domains, consisting of 3 rows and each row composes of 10 tetramers. For clarity, we mark the DHBP molecules along one of the [011] direction with red color, and the ones along the another [011] direction (that is the [0-11] direction) with green color. The sketch structural model of the “R” domains can then be seen in Figure 4b. The formation of the tetramer intermediate states provides the vicinity of the opposite DHBP pairs. Therefore, initial couplings take place by the ortho C-C coupling of the opposite DHBP pairs within the tetramer. The relative orientation of the opposite DHBP pairs, which is determined by the chiral nature of the “C” tetramers in the “R” domain, favors to the formation of “R” dimer products, as shown in Figure 4d. This way, the chiral information of the tetramer intermediate states is transferred to the dimer products. Moreover, the formation of “R” dimers only leads to slightly shrinking (0.3 nm) along the direction perpendicular to the rows, and certain monomer desorption (one green colored monomer desorbs with the formation of each “R” dimer, as shown in Figure 4c and 4d). The DHBPs maintain their orientations to one of the [011] directions, in both the formed “R” dimers (red color in Figure 4d) and the decorated monomers (green color in Figure 4d). The distance

Figure 5. C 1s and O 1s scans of the synchrotron-based XPS spectra on a DHBP adsorbed Ag(100) surface. The sample preparation and annealing temperatures are indicated between the spectra.

To elucidate the chemical states of the molecules at different stages, the temperature dependent synchrotron-based XPS experiments were carried out. Figure 5 gives the spectra of the C 1s (left panel) and O 1s (right panel) line scans after initial adsorption of the DHBPs on a Ag(100) surface held at 200 K, and subsequently annealing at different temperatures. After deposition of DHBPs on Ag(100) at 200 K, the C 1s spectrum shows two prominent peaks with the binding energy (BE) centered at 284.7 eV and 286.2 eV, respectively. According to previous studies, the lower energy peak (284.7 eV) can be assigned to the aromatic carbons, and the higher energy peak (286.2 eV) represents the C-OH bonds.36, 49 Correspondingly, the O 1s spectrum at this stage shows a sole peak centered at 533.3 eV, which can be ascribed to the hydroxyl groups.36, 49-50 The XPS results confirm that the molecular components in the self-assembly structure shown in Figure 2a are pristine DHBPs. After increasing the annealing temperature, the C-OH bonds transform to C-O bonds gradually. Eventually, a dominant peak centered at 530.3 eV is observed after annealing at 370 K, suggesting that all the COH bonds have transformed to the C-O bonds. Meanwhile, the oxygen related C 1s peak shift downwards from 286.2 eV to 285.6 eV, which is similar to previous reports.36 For the sample shown in Figure 2d, the peak in O 1s spectrum further shifts from 530.3 eV to 529.9 eV. Considering that the interaction of oxygen and silver usually leads to that the binding energy shift downwards,51-52 we ascribed the 529.9 eV peak to the O-Ag coordinations, as shown schematically in Figure 2h. Upon the occurrence of the dimerization reactions,


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Journal of the American Chemical Society the binding energy in O 1s spectrum shifts from 529.9 eV back to 530.3 eV, suggesting that the C-O-Ag complexes transform back to the C-O bonds. Two DHBP molecules are reacted to form a dimer product via C-H bond activations and subsequent C-C bond coupling. In the proposed dimer products, the oxygen atoms close to the newly formed C-C bonds are dissociated, while the other oxygen atoms are not dissociated, as shown in Scheme 1. The reason is: 1) We have studied the ratio of the C 1s to O 1s signal systematically (as seen in Table S1 in the Supporting Information). The ratio remains almost unaltered after annealing at 300 K, 370 K and 490 K. The ratio increases by approximated 28% after annealing at 520 K, suggesting part of the oxygen atoms were dissociated; 2) As shown in Figure 3, the molecular network were not significantly disturbed during the dimerization reaction, which suggest that the strong inter-molecular hydrogen bonding maintains. Thus, the oxygen atoms involved in the hydrogen bonds are not dissociated at 520 K; 3) In comparison to the oxygen atoms close to the newly formed C-C bond, the dissociation of oxygen atoms contributing to the inter-molecular hydrogen bonding would need extra energy cost. The dissociation of oxygen atoms close to the newly formed C-C bond is therefore more feasible; 4) In order to confirm this, we further annealed the sample at 570 K, and the STM image (Figure S7) shows that the self-assembly structure breaks and irregular networks are formed. Moreover, the ratio of the C 1s to O 1s signal increases by more than 250% after annealing at 570 K, indicating almost all the oxygen atoms have been dissociated. After annealing at 520 K, a new peak centered at 533.7 eV starts to emerge. It cannot be ascribed to the C-OH bond, since 520 K is much beyond the temperature that leads to the dehydrogenation reaction of the hydroxyl groups on silver surfaces. This new peak centered at 533.7 eV may be ascribed to the chemical adsorption of the dissociated oxygen atoms on the silver surfaces. In conclusion, this series of XPS measurements support our proposed structural evolutions after annealing the surface at different temperatures. Density functional theory (DFT) calculations have been carried out to study the underlying reaction pathways of C-H bond activations and chiral transfer. The computational details are described in the supplementary materials. Due to limited computational resources, the DHBP molecules are represented with the phenol molecules (Figure 6). As has been discussed above, the initial state (IS) is selected as four phenoxyl groups bonded to one Ag adatom on the Ag(100). While the phenoxyl radicals are known to undergo enol-keto tautomerism, the dehydrogenation on the ortho carbon atoms is feasible. DFT calculations show that the activation barrier of the first dehydrogenation is 1.53 eV. In the transition state (TS1), the dissociated hydrogen atom and the resulted carbon radical is connected to the oxygen atom of a neighboring phenoxyl group and the Ag adatom, respectively. Crossing over TS1, the phenoxyl group that has received the dissociated hydrogen atom starts to diffuse away from the Ag adatom and form hydrogen bond with another neighboring phenoxyl group. This configuration is referred to as the meta-state (MS). Similar dehydrogenation process may occur on the para phenoxyl group with a similar energy barrier of 1.55 eV. In the final state (FS), both of the molecules are connected to the Ag adatom through the ortho-carbon radicals. Staring from the IS, we have also considered the possibility of successive C-H

bond activations on two neighboring phenoxyl groups. As seen in Figure S8, the corresponding activation barrier of the second dehydrogenation is only slightly higher than that in Figure 6. However, please note that the reaction products from both reaction pathways are the linear phenoxyl-Ag-phenoxyl complexes. This indicates that the structural changes (e.g. molecular rotation and diffusion) in the dimerization of ortho phenoxyls is much more drastic than in the para phenoxyl dimerization. Because of the limited computational resources, in the search of transition states, the DHBP molecules are represented with non-self-assembled phenoxyl groups. Such simplification significantly reduced the energy cost for molecular rotations and diffusions on Ag surfaces. In the case of molecular assembled DHBP molecules, the dimerization of para phenoxyl groups is more favorable due to less structural changes. Crossing over the FS, the subsequent C-C bond formation and thus the dimerization of the phenoxyl groups should be very feasible at the experimental conditions. According to our previous report,36 the hydrogen dissociation of hydroxyl groups on metal surfaces may occur with a reaction barrier that is lower than that in the ortho C-H activation. As a consequence, the O-H bonds in dimer products will finally dissociated, as shown in Figure 4d.

Figure 6. The reaction pathways and energy profiles of the successive ortho-dehydrogenation of para phenoxyl radicals.

The DFT calculations elucidate why the chiral information of the reaction products is the same to that of the tetramer intermediate states. We have also considered the other possible reaction pathways, in which intermediate states are not directly related to the phase separation of the final products. For instance, the self-assembly shown in Figure 3b breaks completely at elevated temperatures when the dimerization of DHBP takes place, and the chiral phases shown in Figure 3d is resulting from the re-self-assembly of the mixed dimers and monomers. Nevertheless, such reaction mechanism can be ruled out because: (i) If the chiral phase separation shown in Figure 3d is a result of re-assembly of the monomers and dimers, the coupling of free diffusion monomers at reaction temperature should lead to a mixture of the “R”, “L” and “B” dimers, similar to the situation shown in Figure 1c. In contrast, the formation of the “B” dimers are entirely prohibited (Figure S3) with the two-step strategy



described in Figure 3. (ii) If the system shown in Figure 3d is a result of re-assembly (STM image is taken at 77 K), the selfassembly structure shown in Figure 2d breaks at the reaction temperature of 520 K. The free diffusion monomers should thus couple with each other. However, experimentally, the structure shown in Figure 3d always involves both the dimer products and the monomers, with a fixed monomer/dimer ratio. (iii) Moreover, the structure shown in Figure 3d is the only phase that has been observed after annealing at 520 K, indicating that the monomer/dimer ratio is independent with the annealing time. All these observed phenomenon is contradictory with the re-assembly hypothesis. If annealing the sample at higher temperatures (570 K for 20 minutes), the co-assembly structure shown in Figure 3d would be broken. As shown in Figure S7, randomly connected networks are observed, which arises from the further C-C couplings via the further C-H bond activations.

CONCLUSIONS In summary, we have successfully achieved the transfer of chiral information of the self-assembly structure to the C-C bond coupling products on a silver surface, utilizing the metalorganic hybrid intermediate states. The tetramer intermediate states are of chirality, and tend to self-assemble into enantiomeric islands. The chiral expressions of the newly formed dimers are fully determined by the relative orientation of the opposite DHBP monomers, that is, the chirality of the tetramer intermediate states. The extended domains of the tetramer intermediate states lead to the formation of large scale enantiomeric islands of the C-C bond coupling dimer products, since the self-assembly structure maintains during the well-controlled reaction process. The detailed reaction pathways are rationalized by DFT calculations and synchrotron-based XPS experiments, demonstrating the mechanisms of the chiral transfer on silver surfaces. The present work does not directly lead to homochiral reaction products, and the chirality of the products maintains only when located on surfaces. Despite that, this work provides potential feasible strategies for the transfer of the chiral information of the self-assembly structures to the reaction products, and thus may open a new window for asymmetric synthesis on surfaces.

ASSOCIATED CONTENT Supporting Information. Details of the experiments and calculations. Extended analysis of additional STM results. This material is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION Corresponding Author *[email protected] *[email protected] *[email protected]

Author Contributions The manuscript was written through contributions of all authors.

Notes The authors declare no competing financial interest.

ACKNOWLEDGMENTS

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We acknowledge the Collaborative Innovation Center of Suzhou Nano Science & Technology and the Priority Academic Program Development of Jiangsu Higher Education Institutions. This work was supported by National Science Foundation of China (21790053, 21622306, 91545127, 21403149, 21872099), National Major State Basic Research Development Program of China (2017YFA0205002, 2014CB932600) and Natural Science Foundation of Jiangsu Province (BK20140305).

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