| 1. |
- Hao, Zhengming, et al.
(författare)
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Converting n-Alkanol to Conjugated Polyenal on Cu(110) Surface at Mild Temperature
- 2022
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Ingår i: The Journal of Physical Chemistry Letters. - : AMER CHEMICAL SOC. - 1948-7185. ; 13:14, s. 3276-3282
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Tidskriftsartikel (refereegranskat)abstract
- Achieving C(sp(3))-H activation at a mild temperature is of great importance from both scientific and technologic points of view. Herein, on the basis of the on-surface synthesis strategy, we report the significant reduction of the C(sp(3))-H activation barrier, which results in the full C(sp(3))-H to C(sp(2))-H transformation of n-alkanol (octacosan-1-ol) at a mild temperature as low as 350 K on the Cu(110) surface, yielding the conjugated polyenal (octacosa-tridecaenal) as the final product. The reaction mechanism is revealed by the combined scanning tunneling microscope, density functional theory, and synchrotron radiation photoemission spectroscopy.
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| 2. |
- Hao, Zhengming, et al.
(författare)
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From n-alkane to polyacetylene on Cu (110): Linkage modulation in chain growth
- 2022
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Ingår i: Science in China Series B. - : SCIENCE PRESS. - 1674-7291 .- 1869-1870. ; 65:4, s. 733-739
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Tidskriftsartikel (refereegranskat)abstract
- Direct coupling or transformation of inert alkanes based on the selective C-H activation is of great importance for both chemistry and chemical engineering. Here, we report the coupling of polyenes that are transformed from n-dotriacontane (n-C32H66) through on-surface cascade dehydrogenation on Cu (110) surface, leading to the formation of polyacetylene (PA). Three distinct linkages have been resolved by scanning tunneling microscope (STM) and noncontact atomic force microscope (nc-AFM). Apart from the alpha-type linkage which is the stemless coupling of the terminal C-C double bond in trans-configuration, beta- and gamma-type linkages appear as knots or defects which are, in fact, the C-C couplings in cis-configurations. Interestingly, the "defects" can be effectively suppressed by adjusting the surface coverage, thus making it of general interest for uniform structure modulation.
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| 3. |
- Li, Lifeng, et al.
(författare)
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Hydrodynamics and mass transfer of concentric-tube internal loop airlift reactors : A review
- 2022
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 359
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Forskningsöversikt (refereegranskat)abstract
- The concentric-tube internal loop airlift reactor is a typical reactor configuration which has been adopted for a myriad of chemical and biological processes. The reactor hydrodynamics (including mixing) and the mass transfer between the gas and liquid phases remarkably affect the operational conditions and thus are crucial to the overall reactor performance. Hence, this study aims at providing a thorough description of the basic concepts and a comprehensive review of the relevant reported studies on the hydrodynamics and mass transfer of the concentric-tube internal loop airlift reactors, taking microalgae cultivation as an exemplary application. In particular, the reactor characteristics, geometry, CFD modeling, experimental characterization, and scale up considerations are elucidated. The research gaps for future research and development are also identified.
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| 4. |
- Li, Qing, et al.
(författare)
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Hierarchical Dehydrogenation Reactions on a Copper Surface
- 2018
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Ingår i: Journal of the American Chemical Society. - : AMER CHEMICAL SOC. - 0002-7863 .- 1520-5126. ; 140:19, s. 6076-6082
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Tidskriftsartikel (refereegranskat)abstract
- Hierarchical control of chemical reactions is being considered as one of the most ambitious and challenging topics in modern organic chemistry. In this study, we have realized the one-by-one scission of the X-H bonds (X = N and C) of aromatic amines in a controlled fashion on the Cu(lll) surface. Each dehydrogenation reaction leads to certain metal-organic supramolecular structures, which were monitored in single-bond resolution via scanning tunneling microscopy and noncontact atomic force microscopy. Moreover, the reaction pathways were elucidated from X-ray photoelectron spectroscopy measurements and density functional theory calculations. Our insights pave the way for connecting molecules into complex structures in a more reliable and predictable manner, utilizing carefully tuned stepwise on-surface synthesis protocols.
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| 5. |
- Li, Xuechao, et al.
(författare)
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Direct transformation of n-alkane into all-trans conjugated polyene via cascade dehydrogenation
- 2021
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Ingår i: National Science Review. - : Oxford University Press. - 2095-5138 .- 2053-714X. ; 8:10
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Tidskriftsartikel (refereegranskat)abstract
- Selective C(sp(3))-H activation is of fundamental importance in processing alkane feedstocks to produce high-value-added chemical products. By virtue of an on-surface synthesis strategy, we report selective cascade dehydrogenation of n-alkane molecules under surface constraints, which yields monodispersed all-trans conjugated polyenes with unprecedented length controllability. We are also able to demonstrate the generality of this concept for alkyl-substituted molecules with programmable lengths and diverse functionalities, and more importantly its promising potential in molecular wiring.
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| 6. |
- Li, Xuechao, et al.
(författare)
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Pyridinic Nitrogen Modification for Selective Acetylenic Homocoupling on Au(111)
- 2023
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Ingår i: Journal of the American Chemical Society. - : AMER CHEMICAL SOC. - 0002-7863 .- 1520-5126. ; 145:8, s. 4545-4552
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Tidskriftsartikel (refereegranskat)abstract
- On-surface acetylenic homocoupling has been proposed to construct carbon nanostructures featuring sp hybrid-ization. However, the efficiency of linear acetylenic coupling is far from satisfactory, often resulting in undesired enyne products or cyclotrimerization products due to the lack of strategies to enhance chemical selectivity. Herein, we inspect the acetylenic homocou-pling reaction of polarized terminal alkynes (TAs) on Au(111) with bond-resolved scanning probe microscopy. The replacement of benzene with pyridine moieties significantly prohibits the cyclotrimerization pathway and facilitates the linear coupling to produce well-aligned N-doped graphdiyne nanowires. Combined with density functional theory calculations, we reveal that the pyridinic nitrogen modification substantially differentiates the coupling motifs at the initial C-C coupling stage (head-to-head vs head-to-tail), which is decisive for the preference of linear coupling over cyclotrimerization.
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| 7. |
- Niu, Kaifeng, et al.
(författare)
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C-H activation of light alkanes on MXenes predicted by hydrogen affinity
- 2020
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : ROYAL SOC CHEMISTRY. - 1463-9076 .- 1463-9084. ; 22:33, s. 18622-18630
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Tidskriftsartikel (refereegranskat)abstract
- C-H activation of light alkanes is one of the most important reactions for a plethora of applications but requires catalysts to operate at feasible conditions. MXenes, a new group of two-dimensional materials, have shown great promise as heterogeneous catalysts for several applications. However, the catalytic activity of MXenes depends on the type and distribution of termination groups. Theoretically, it is desired to search for a relation between the catalytic activity and the termination configuration by employing a simple descriptor in order to avoid tedious activation energy calculations. Here, we show that MXenes are promising for splitting C-H bonds of light alkanes. Furthermore, we present how a quantitative descriptor - the hydrogen affinity - can be used to characterize the termination configuration of Ti2CTz(T = O, OH) MXenes, as well as the catalytic activity towards dehydrogenation reactions, using propane as model system. First-principles calculations reveal that the hydrogen affinity can be considered as an intrinsic property of O and OH terminated Ti2C MXenes, in which the mean hydrogen affinity for the terminated Ti2C MXenes is linearly correlated to the statistical average of their OH fraction. In addition, the C-H activation energies exhibit a strong scaling relationship to the hydrogen affinity. This quantity can therefore yield quick predictions of catalytic activity of terminated Ti2C MXenes towards C-H activations, and even predict their chemical selectivity toward scissoring different C-H bonds. We believe that the hydrogen affinity will accelerate the discovery of further applications of the broad family of MXenes in heterogeneous catalysis.
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| 8. |
- Niu, Kaifeng, 1994-
(författare)
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Mechanistic investigations of chemical reactions on 2D MXenes and metal surfaces from first-principles
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Chemical reactions on surfaces play a central role both for our daily life and industrial purposes, including the storage and release of energy, as well as the formation of new materials. To achieve high efficiency, catalysis lies in the heart of chemical reactions as it plays a critical role in accelerating the chemical transformation to target products. However, environmental issues arise as the applications of catalytic technologies and current synthetic approaches such as pollution from undesirable byproducts and massive emission of carbon dioxides due to the usage of fossil fuels. This calls for developing improved strategies for fabricating new materials with highly efficient catalytic properties. In recent years, on-surface chemical reactions have also been used to synthesize new low-dimensional materials with atomic precision, by coupling molecules into nanostructures. It is crucial to not only obtain high activity for chemical reactions, but also achieve distinct selectivity towards desired products. For this purpose, understanding mechanisms of target chemical reactions and origins of catalysts’ activity are of great significance to facilitate chemical processes.In this thesis, three types of chemical reactions are investigated within the framework of density functional theory (DFT), in which chemical reactions relevant for both heterogeneous catalysis and electrochemical synthesis are considered on two-dimensional transition metal carbides (2D MXenes), and chemical reactions for synthesizing organic nanostructures are studied on metal surfaces. Focusing on one of the most fundamental chemical reaction, C(sp3)-H activation, we demonstrate that MXenes can serve as highly efficient heterogeneous catalysts and exhibit high activity. The thermally triggered C-H activations are shown to follow the “radical-like” mechanism on MXenes, in which O terminations serve as active sites. By adopting the hydrogen affinity (EH) as a descriptor, both the geometry configuration and the catalytic activity of MXenes can be quantitatively characterized.In the context of on-surface synthesis, we theoretically propose reaction mechanisms of two types of chemical reactions on surface. A new strategy for constructing C-C bonds via the desulfonylation reaction was achieved experimentally for the first time by collaborators. With DFT calculations, an observed discrepancy between Ag(111) and Au(111) is ascribed to interactions between surfaces and molecules. Secondly, the formation mechanism of the 2D biphenylene network (BPN), a recently realized carbon allotrope formed by intermolecular HF zipping on Au(111), has been computationally investigated.With the tool of DFT calculations, a single Ni atom catalyst supported by Ti3C2T2 MXenes for electrochemical nitrogen reduction has been theoretically proposed. Such single atom catalyst (SAC) is computationally screened from three aspects including stability, activity, and selectivity. Our theoretical results show that not only the catalytic performance of the Ni SAC predicted by screening criteria can be verified, but also a H rich environment can be beneficial for the electrochemical nitrogen reduction on such SACs.In summary, first-principles calculations have been performed to evaluate the catalytic performance of 2D MXenes towards C-H activation, unravel formation mechanisms of organic materials synthesized via on-surface reactions, and design effective catalysts towards the synthesis of ammonia. It is anticipated that this thesis can pave the way for the rational design of high-efficient catalysts for various reactions and shed lights on developing synthetic strategies of unprecedented organic materials.
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| 9. |
- Niu, Kaifeng, et al.
(författare)
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On-surface synthesis of 2D COFs via molecular assembly directed photocycloadditions: a first-principles investigation
- 2021
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Ingår i: Journal of Physics. - : IOP PUBLISHING LTD. - 0953-8984 .- 1361-648X. ; 33:47
-
Tidskriftsartikel (refereegranskat)abstract
- Over the past decades, the rational synthesis of two-dimensional covalent organic framework (2D COFs) monolayer via on-surface chemistry has been widely explored. Herein, we propose the [2 + 2] photocycloaddition as a novel strategy for large-scale fabrication of COFs from theoretical perspective. Thanks to the symmetry forbidden of thermal [2 + 2] cycloaddition, the molecular precursors carrying vinyl groups will not chemically interact with each other during thermal annealing, which is essential to achieve molecular assembly. The subsequent photocycloaddition of these precursors may produce large-scale 2D COFs at low temperatures, in which the symmetry of molecular assembly remains unchanged. Our results show that 2D COFs can be produced via [2 + 2] photocycloadditions directed from self-assembled precursors, in which alkylbenzene molecules with vinyl groups on side chains exhibit appropriate intermolecular distances. By performing high-throughput calculations, several promising molecular precursors are proposed to achieve large-scale 2D COFs. This work provides an applicable strategy for the large-scale synthesis of 2D carbon materials.
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| 10. |
- Niu, Kaifeng, et al.
(författare)
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Structure-activity correlation of Ti2CT2 MXenes for C-H activation
- 2021
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Ingår i: Journal of Physics. - : IOP PUBLISHING LTD. - 0953-8984 .- 1361-648X. ; 33:23
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Tidskriftsartikel (refereegranskat)abstract
- As a bourgeoning class of 2D materials, MXenes have recently attracted significant attention within heterogeneous catalysis for promoting reactions such as hydrogen evolution and C-H activation. However, the catalytic activity of MXenes is highly dependent on the structural configuration including termination groups and their distribution. Therefore, understanding the relation between the structure and the activity is desired for the rational design of MXenes as high-efficient catalysts. Here, we present that the correlation between the structure and activity of Ti2CT2 (T is a combination of O, OH and/or F) MXenes for C-H activation can be linked by a quantitative descriptor: the hydrogen affinity (E (H)). A linear correlation is observed between the mean hydrogen affinity and the overall ratio of O terminations (x (O)) in Ti2CT2 MXenes, in which hydrogen affinity increases as the x (O) decreases, regardless to the species of termination groups. In addition, the hydrogen affinity is more sensitive to the presence of OH termination than F terminations. Moreover, the linear correlation between the hydrogen affinity and the activity of Ti2CT2 MXenes for C-H activation of both -CH3 and -CH2- groups can be extended to be valid for all three possible termination groups. Such a correlation provides fast prediction of the activity of general Ti2CT2 MXenes, avoiding tedious activation energy calculations. We anticipate that the findings have the potential to accelerate the development of MXenes for heterogeneous catalysis applications.
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| 11. |
- Niu, Kaifeng, et al.
(författare)
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Termination-Accelerated Electrochemical Nitrogen Fixation on Single-Atom Catalysts Supported by MXenes
- 2022
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Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 13:12, s. 2800-2807
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis of ammonia (NH3) from nitrogen (N2) under ambientconditions is of great significance but hindered by the lack of highly efficient catalysts. Byperformingfirst-principles calculations, we have investigated the feasibility for employing atransition metal (TM) atom, supported on Ti3C2T2MXene with O/OH terminations, as asingle-atom catalyst (SAC) for electrochemical nitrogen reduction. The potential catalyticperformance of TM single atoms is evaluated by their adsorption behavior on the MXene,together with their ability to bind N2and to desorb NH3molecules. Of importance, the OHterminations on Ti3C2T2MXene can effectively enhance the N2adsorption and decrease theNH3adsorption for single atoms. Based on proposed criteria for promising SACs, ourcalculations further demonstrate that the Ni/Ti3C2O0.19(OH)1.81exhibits reasonablethermodynamics and kinetics toward electrochemical nitrogen reduction.
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| 12. |
- Niu, Kaifeng, 1994-, et al.
(författare)
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Unveiling the formation mechanism of the biphenylene network
- 2023
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Ingår i: Nanoscale Horizons. - : ROYAL SOC CHEMISTRY. - 2055-6764 .- 2055-6756. ; 8:3, s. 368-376
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Tidskriftsartikel (refereegranskat)abstract
- We have computationally studied the formation mechanism of the biphenylene network via the intermolecular HF zipping, as well as identified key intermediates experimentally, on the Au(111) surface. We elucidate that the zipping process consists of a series of defluorinations, dehydrogenations, and C–C coupling reactions. The Au substrate not only serves as the active site for defluorination and dehydrogenation, but also forms C–Au bonds that stabilize the defluorinated and dehydrogenated phenylene radicals, leading to "standing" benzyne groups. Despite that the C–C coupling between the "standing" benzyne groups is identified as the rate-limiting step, the limiting barrier can be reduced by the adjacent chemisorbed benzyne groups. The theoretically proposed mechanism is further supported by scanning tunneling microscopy experiments, in which the key intermediate state containing chemisorbed benzyne groups can be observed. This study provides a comprehensive understanding towards the on-surface intermolecular HF zipping, anticipated to be instructive for its future applications.
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| 13. |
- Song, Luying, et al.
(författare)
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Intra- and Inter-Self-Assembly of Identical Supramolecules on Silver Surfaces
- 2022
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Ingår i: The Journal of Physical Chemistry Letters. - : AMER CHEMICAL SOC. - 1948-7185. ; 13:38, s. 8902-8907
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Tidskriftsartikel (refereegranskat)abstract
- Self-assembly of identical organometallic supra -molecules into ordered superstructures is of great interest in both chemical science and nanotechnology due to its potential to generate neoteric properties through collective effects. In this work, we demonstrate that large-scale self-organization of atomically precise organometallic supramolecules can be achieved through cascaded on-surface chemical reactions, by the combination of intra-and inter-supramolecular interactions. Supramolecules with defined size and shape are first built through intramolecular reaction and intermolecular metal coordination, followed by the formation of well-ordered two-dimensional arrays with the assistance of Br atoms by-C-HmiddotmiddotmiddotBr interactions. The mechanism of this process has been investigated from the perspectives of thermodynamics and kinetics.
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| 14. |
- Song, Luying, et al.
(författare)
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Synthesis of Two-Dimensional Metal-Organic Frameworks via Dehydrogenation Reactions on a Cu(111) Surface
- 2020
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Ingår i: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 124:23, s. 12390-12396
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Tidskriftsartikel (refereegranskat)abstract
- Metal-organic frameworks prepared on surfaces (SMOFs) have been considered to have potential applications in various research fields. Traditionally, the SMOFs are prepared by coadsorbing organic ligands and metal atoms on surfaces. In this article, we successfully construct the SMOFs via the dehydrogenation reactions of aromatic amines on the Cu(111) surfaces. The dehydrogenated nitrogen radicals interact with the copper adatoms, forming the N-Cu-N bonds. Combining with the scanning tunneling microscopy and the density functional theory calculations, we obtain the structural models of the SMOFs.
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| 15. |
- Wang, Junbo, et al.
(författare)
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Influence of Molecular Configurations on the Desulfonylation Reactions on Metal Surfaces
- 2022
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Ingår i: Journal of the American Chemical Society. - : AMER CHEMICAL SOC. - 0002-7863 .- 1520-5126. ; 144:47, s. 21596-21605
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Tidskriftsartikel (refereegranskat)abstract
- On-surface synthesis is a powerful methodology for the fabrication of low-dimensional functional materials. The precursor molecules usually anchor on different metal surfaces via similar configurations. The activation energies are therefore solely determined by the chemical activity of the respective metal surfaces. Here, we studied the influence of the detailed adsorption configuration on the activation energy on different metal surfaces. We systematically studied the desulfonylation homocoupling for a molecular precursor on Au(111) and Ag(111) and found that the activation energy is lower on inert Au(111) than on Ag(111). Combining scanning tunneling microscopy observations, synchrotron radiation photoemission spectroscopy measurements, and density functional theory calculations, we elucidate that the phenomenon arises from different molecule-substrate interactions. The molecular precursors anchor on Au(111) via Au-S interactions, which lead to weakening of the phenyl-S bonds. On the other hand, the molecular precursors anchor on Ag(111) via Ag-O interactions, resulting in the lifting of the S atoms. As a consequence, the activation barrier of the desulfonylation reactions is higher on Ag(111), although silver is generally more chemically active than gold. Our study not only reports a new type of on-surface chemical reaction but also clarifies the influence of detailed adsorption configurations on specific on-surface chemical reactions.
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| 16. |
- Wang, Lina, et al.
(författare)
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Tailoring Alkane Uniaxial Self-Assembly via Polymer Modified Step Edges
- 2019
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Ingår i: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 123:47, s. 28811-28815
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Tidskriftsartikel (refereegranskat)abstract
- Controlling the orientations of molecules in self-assembled monolayers on surfaces is an effective means to construct high quality organic devices. Herein, we utilize linear polymer-modified step edges as a simple and peculiar template for regulating the subsequent self-assembly of alkane molecules (n-C32H66). With this strategy, all the alkane molecules orientate along the step edge ([011] directions). Combining with systematical DFT calculations, we demonstrated that it is the van der Waals interactions between the molecules that leads to (1) the initially adsorbed alkane monomers lie parallel to the polymers; (2) the adjacent alkane molecules show a parallel configuration. Since the polymers anchor on the surface along an exclusive [011] direction, all the adsorbed molecules in the self-assembly islands are regulated along the [011] directions as well.
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| 17. |
- Yang, Biao, et al.
(författare)
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Abiotic Formation of an Amide Bond via Surface-Supported Direct Carboxyl-Amine Coupling
- 2022
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Ingår i: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 61:5
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Tidskriftsartikel (refereegranskat)abstract
- Amide bond formation is one of the most important reactions in biochemistry, notably being of crucial importance for the origin of life. Herein, we combine scanning tunneling microscopy and X-ray photoelectron spectroscopy studies to provide evidence for thermally activated abiotic formation of amide bonds between adsorbed precursors through direct carboxyl-amine coupling under ultrahigh-vacuum conditions by means of on-surface synthesis. Complementary insights from temperature-programmed desorption measurements and density functional theory calculations reveal the competition between cross-coupling amide formation and decarboxylation reactions on the Au(111) surface. Furthermore, we demonstrate the critical influence of the employed metal support: whereas on Au(111) the coupling readily occurs, different reaction scenarios prevail on Ag(111) and Cu(111). The systematic experiments signal that archetypical bio-related molecules can be abiotically synthesized in clean environments without water or oxygen.
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| 18. |
- Yang, Biao, et al.
(författare)
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Synthesis of Surface Covalent Organic Frameworks via Dimerization and Cyclotrimerization of Acetyls
- 2015
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society. - 0002-7863 .- 1520-5126. ; 137:15, s. 4904-4907
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Tidskriftsartikel (refereegranskat)abstract
- The formation of additional phenyl rings on surfaces is of particular interest because it allows for the building-up of surface covalent organic frameworks. In this work, we show for the first time that the cyclotrimerization of acetyls to aromatics provides a promising approach to 2D conjugated covalent networks on surfaces under ultrahigh vacuum. With the aid of scanning tunneling microscopy, we have systematically studied the reaction pathways and the products. With the combination of density functional theory calculations and X-ray photoemission spectroscopy, the surface-assisted reaction mechanism, which is different from that in solution, was explored.
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| 19. |
- Zhong, Qigang, et al.
(författare)
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On-Surface Stereochemical Characterization of a Highly Curved Chiral Nanographene by Noncontact Atomic Force Microscopy and Scanning Tunneling Microscopy
- 2023
-
Ingår i: CCS CHEMISTRY. - : CHINESE CHEMICAL SOC. - 2096-5745.
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Tidskriftsartikel (refereegranskat)abstract
- A highly distorted chiral nanographene structure composed of triple corannulene-fused [5]helicenes is prepared with the help of the Heck reaction and oxidative photocyclization with an overall isolated yield of 28%. The complex three-dimensional (3D) structure of the bowl-helix hybrid nanostructure is studied by a combination of non contact atomic force microscopy (AFM) and scanning tunneling microscopy (STM) on the Cu(111) surface, density functional theory calculations, AFM/STM simulations, and high-performance liquid chromatography-electronic circular dichroism analysis. This examination reveals a molecular structure in which the three bowl-shaped corannulene bladesd position themselves in a C3-symmetric fashion around a highly twisted triphenylene core. The molecule appears to be shaped like a propeller in which the concave side of the bowls face away from the connected [5]helicene motif. The chirality of the nanostructure is confirmed by the direct visualization of both MMM and PPP enantiomers at the single-molecule level by scanning probe microscopies. These results underline that submolecular resolution imaging by AFM/STM is a powerful real-space tool for the stereochemical characterization of 3D curved chiral nanographene structures.
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| 20. |
- Zhong, Qigang, et al.
(författare)
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Substrate-Modulated Synthesis of Metal-Organic Hybrids by Tunable Multiple Aryl-Metal Bonds
- 2022
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Ingår i: Journal of the American Chemical Society. - : AMER CHEMICAL SOC. - 0002-7863 .- 1520-5126. ; 144:18, s. 8214-8222
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Tidskriftsartikel (refereegranskat)abstract
- Assembly of semiconducting organic molecules with multiple aryl-metal covalent bonds into stable one- and two- dimensional (1D and 2D) metal-organic frameworks represents a promising route to the integration of single-molecule electronics in terms of structural robustness and charge transport efficiency. Although various metastable organometallic frameworks have been constructed by the extensive use of single aryl-metal bonds, it remains a great challenge to embed multiple aryl-metal bonds into these structures due to inadequate knowledge of harnessing such complex bonding motifs. Here, we demonstrate the substrate-modulated synthesis of 1D and 2D metal-organic hybrids (MOHs) with the organic building blocks (perylene) interlinked solely with multiple aryl-metal bonds via the stepwise thermal dehalogenation of 3,4,9,10-tetrabromo-1,6,7,12-tetrachloroperylene and subsequent metal-organic connection on metal surfaces. More importantly, the conversion from 1D to 2D MOHs is completely impeded on Au(111) but dominant on Ag(111). We comprehensively study the distinct reaction pathways on the two surfaces by visually tracking the structural evolution of the MOHs with high-resolution scanning tunneling and noncontact atomic force microscopy, supported by first-principles density functional theory calculations. The substrate-dependent structural control of the MOHs is attributed to the variation of the M-X (M = Au, Ag; X = C, Cl) bond strength regulated by the nature of the metal species.
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