Oxygen bridging method for regulating aromaticity and surface reaction activity of nickel (II) norcorrole derivative as well as product and application thereof

Abstract

The invention discloses a method for editing and regulating aromaticity and surface reaction activity of a nickel (II) norcorrole derivative through an oxygen bridging skeleton, a product of the method and application of the product, and belongs to the technical field of surface molecular science and molecular nanotechnology. In a solution phase pre-synthesis stage, a predetermined number of oxygen atoms are introduced into a pyrrole-pyrrole connecting bond of a nickel (II) norcorrole molecule, a determined number of C-O-C bridging structures are constructed and formed, and a precursor molecule with a programmable structure is obtained. The precursor is deposited on the surface of a metal single crystal and is subjected to a surface-assisted dehydrocyclization reaction after thermal annealing treatment, and oxygen atoms are retained and integrated into a final macrocyclic skeleton. The introduction of the oxygen bridge systematically regulates and controls the electronic structure and aromaticity distribution of the product, and further reconstructs the front line orbit space distribution. In the surface covalent coupling reaction, products not doped with oxygen are subjected to multi-path coupling to form products with different structures, and oxygen bridging products selectively form a single beta-beta site coupling structure.

Description

Technical Field

[0001] This invention belongs to the fields of surface molecular science, molecular nanotechnology, and physical chemistry, specifically relating to a method for skeletal editing of nickel(II) norcarbole derivatives on solid surfaces to regulate their global aromaticity and edge site reactivity. This invention also relates to cyclized macrocyclic molecules with oxygen-bridged structures prepared by this method, and their application in surface covalent assembly. Background Technology

[0002] Aromaticity and antiaromaticity are fundamental factors influencing the electronic structure and chemical stability of π-conjugated systems, and their regulation is a crucial basis for the design of functional organic molecules and related materials. Extensive research has been conducted in molecular electronics, quantum information, and catalysis focusing on aromaticity regulation. However, effectively regulating molecular aromaticity and its reactive behavior in the heterogeneous and confined interfacial environment of solid surfaces remains challenging. Traditional solution-phase regulation methods, such as redox reactions, protonation, or ligand exchange, typically rely on the solvent environment and molecular diffusion processes, making them difficult to apply directly to surface-confined systems.

[0003] In recent years, surface science has made significant progress in molecular adsorption, structural characterization, and surface-assisted reactions. High-resolution scanning probe microanalysis (SMS) can resolve molecular configurations and electronic state changes at the single-molecule scale, and surface-assisted reactions have been widely used to construct extended π-conjugated structures and study their electronic properties. Studies on the extension of π-systems and the regulation of electronic structure through surface-assisted reactions in porphyrin-like and other metal-organic macrocyclic systems have been reported. These achievements have deepened our understanding of the evolution of surface molecular electronic structures, but most of these works are based on existing molecular frameworks and involve surface reactions or physical field manipulation.

[0004] In contrast, there is relatively little research on how to design and edit the precursor framework before molecular deposition to give the molecules a predetermined electronic structure before they enter the surface reaction stage, and how this can further influence their surface covalent reaction behavior. In particular, a systematic approach has not yet been developed to introduce bridging structures into the molecular framework to alter the characteristics of the π-system and thus affect subsequent surface reaction pathways.

[0005] For organometallic macrocyclic molecules such as nickel(II)norcarbol, their π-electronic structure endows them with specific aromatic or antiaromatic behaviors, which may exhibit multiple competing pathways during surface reactions. How to control their aromatic characteristics and further influence the reaction selectivity of surface covalent coupling by structurally modulating their core framework before deposition on the surface remains an unsolved problem. Summary of the Invention

[0006] This invention provides a technical solution for influencing the aromaticity and surface reaction behavior of molecular precursors by structurally adjusting the molecular precursor framework under surface synthesis conditions. Existing surface chemistry methods are mostly based on predetermined molecular structures to carry out surface reactions or physical field control, lacking technical means to adjust the subsequent surface reaction pathways through framework structure design before molecular deposition onto the surface.

[0007] The core of this invention lies in proposing a regulatory strategy based on oxygen-bridged framework editing. This strategy involves introducing 0, 1, or 2 oxygen atoms into the pyrrole-pyrrole linkage of the nickel(II) norcarbole derivative during the solution-phase pre-synthesis stage, forming a defined number of C–O–C bridging structures. These oxygen-bridged structures are retained and integrated into the final product framework during subsequent surface thermal activation, resulting in cyclized products with different aromatic characteristics and surface reaction behaviors.

[0008] (I) The core method of this invention: skeleton editing based on precursor design and surface thermal activation

[0009] Includes the following steps:

[0010] 1. Design and synthesis of precursor molecules with oxygen-containing bridging structures

[0011] Nickel(II) norcarbole derivatives with varying numbers of oxygen atoms inserted at pyrrole-pyrrole direct linkages were synthesized as solution-phase precursors. The precursors included: a baseline molecule without oxygen insertions, denoted as Ni(II)-Nor; a molecule with one oxygen atom inserted at one linkage, denoted as Ni(II)-OxNor; and a molecule with one oxygen atom inserted at each of two different linkages, denoted as Ni(II)-2OxNor. The introduction of the oxygen atoms was completed before the molecules were deposited onto the metal surface.

[0012] 2. Surface deposition and thermally induced cyclization reaction

[0013] The precursor molecules are deposited on a metal single crystal surface (preferably Au(111)) and then thermally annealed under vacuum or an inert atmosphere. The annealing temperature is sufficient to trigger a surface-assisted dehydrogenation cyclization reaction (e.g., 480 K–520 K), causing the peripheral substituents of the precursor molecules to circumvolute with the core macrocycle, forming a planarized extended π-conjugated cyclized macrocycle structure. During this process, the oxygen atoms pre-introduced in the precursor are retained and integrated into the molecular framework of the final product, forming a stable C–O–C bridging structure. The number of oxygen bridges, as a structural variable, can be used to distinguish the structural and electronic characteristics of the resulting cyclized product.

[0014] (ii) Core product: Cyclic macrocycles with oxygen-bridged structures

[0015] The cyclized product prepared by the above method has the following structural characteristics: the product is a planar nickel(II) norcarbole derivative, with an additional benzene ring structure formed on its periphery through dehydrogenation cyclization, constituting an extended π-conjugated system. The molecular skeleton of the product contains 0, 1, or 2 C–O–C bridge bonds determined by the precursor editing step. Theoretical and computational analysis shows that the C–O–C bridge bonds participate in the regulation of molecular electronic structure and affect the aromaticity distribution characteristics. With the change in the number of oxygen bridges, the aromaticity of the cyclized product exhibits differentiated characteristics.

[0016] (III) Technical Effects and Applications: The Influence of Structural Adjustment on Surface Reaction Behavior

[0017] Different cyclized products prepared using the above method exhibit different covalent coupling behaviors under the same surface annealing conditions: for the oxygen-free cyclized product Ni(II)-Nor, various dimers with different structures can be formed on the surface, including laterally linked β–β dimers and dimer structures linked by six-membered rings. For the monooxygen-bridged cyclized product Ni(II)-OxNor, under the same conditions, it mainly forms a β–β site-linked dimer structure. By adjusting the number of oxygen bridges in the precursor, the aromaticity characteristics of the cyclized product can be affected, and its covalent reaction pathway on the surface can be influenced, thus providing a means for surface molecular structure design and site-selective covalent assembly.

[0018] This invention aims to address the core challenge in existing surface chemistry techniques: the lack of an effective and programmable synergistic regulation mechanism between the intrinsic electronic properties (such as global aromaticity) and surface chemical reactivity of organometallic macrocyclic molecules adsorbed on solid surfaces. Specifically, existing methods cannot, through a simple and fundamental chemical modification, pre-"edit" the core framework of the molecule before or during its fixation on the surface. This would not allow for continuous and precise adjustment of aromaticity intensity, nor would it directly translate this change in electronic structure into precise guidance of reactivity at specific molecular sites. Ultimately, it fails to achieve rational convergence and controllable synthesis on surfaces from complex, random multi-path coupling reactions to a single, predictable covalent bond formation pathway.

[0019] The core of this invention lies in proposing an "oxygen atom-oriented framework editing" strategy (hereinafter referred to as "oxygen editing" or "oxygen doping"). The essence of this strategy is: during the solution-phase pre-synthesis stage, oxygen atoms are precisely introduced into the pyrrole-pyrrole linkages of nickel(II) norcarbole derivatives to construct a defined number of COC-bridged structures (i.e., "oxygen bridging"). In the subsequent surface thermal activation process, this "oxygen bridging" acts as an intrinsic "chemical instruction," simultaneously regulating the global aromaticity and edge reactivity of the final product, thereby precisely guiding its surface covalent assembly path, forming a universal regulatory logic of "framework editing → aromaticity programming → reaction path control".

[0020] (I) The core method of this invention: framework editing based on precursor design and surface thermal activation. It includes the following sequentially related steps:

[0021] 1. Design and synthesis of precursor molecules containing oxygen-containing editing instructions:

[0022] A series of nickel(II) norcarbole derivatives with different numbers of oxygen atoms inserted at the pyrrole-pyrrole direct linkages were synthesized as solution-phase precursors. The precursors comprise at least the following:

[0023] The reference molecule without oxygen insertion (denoted as Ni(II)-Nor).

[0024] A molecule in which an oxygen atom is inserted at a linker (denoted as Ni(II)-OxNor).

[0025] A molecule in which an oxygen atom is inserted at each of the two connecting bonds (denoted as Ni(II)-2OxPor).

[0026] The introduction of the oxygen atoms is a pre-editing of the skeleton that is completed before the molecules are deposited onto the surface.

[0027] 2. Surface deposition and thermally induced cyclization and editing effects are achieved:

[0028] The precursor molecules are deposited on a clean metal single crystal surface (preferably Au(111)) and then subjected to controlled thermal annealing in an inert atmosphere or vacuum.

[0029] Thermally activated cyclization: The annealing temperature needs to be sufficient to trigger a surface-assisted cyclization dehydrogenation reaction (usually above 450 K) so that the substituents on the periphery of the precursor molecule (such as benzyl) and the core macrocycle close together to form a fully planarized, extended π-conjugated cyclized macrocycle structure.

[0030] Editing effect takes effect: In this process, the oxygen atoms pre-implanted in the precursor are retained and integrated into the backbone of the final product, forming a stable COC bridging structure. The number of oxygen atoms (0, 1, 2) is directly used as a programmable variable, determining the final electronic structure and chemical properties of the cyclization product.

[0031] (ii) Core product: a cyclic macrocycle with a programmable oxygen-bridged structure and aromaticity.

[0032] The above method can be used to prepare a series of cyclic macrocyclic molecules with well-defined structures and tunable properties. Their core structural features are:

[0033] The cyclization product is a planar nickel(II) norcarboxylic acid derivative, with an additional benzene ring formed around its periphery through cyclization and dehydrogenation.

[0034] The molecular skeleton of the product contains a defined number of COC bridging bonds (0, 1, or 2) determined by the precursor editing step.

[0035] The COC bridge is not only a structural unit in the product, but also plays a crucial role as a "σ-conjugation hub." Theoretical calculations (such as σ-ACID analysis) show that it participates in σ-electron delocalization through the in-plane lone pair electrons of the oxygen atom, thereby magnetically coupling the aromatic segments on both sides. This is the electronic structure root that drives the systematic evolution of the global aromaticity of the product.

[0036] (III) Technical Effects and Applications: Site-Selective Surface Assembly Guided by Aromatic Programming

[0037] Different cyclized products prepared by the above method exhibit drastically different surface chemical reaction behaviors due to their varying degrees of backbone editing, which constitutes the direct application value of this invention:

[0038] 1. For undoped oxygen-cyclosubstituted Ni(II)-Nor: its aromaticity is fragmented, with leading molecular orbitals widely distributed at multiple edge sites (such as β, δ, and ζ sites). Under appropriate surface annealing conditions, it can undergo covalent coupling through multiple energy-similar pathways to generate various structurally isomeric dimers (e.g., directly laterally linked β-β dimers, and dimers indirectly linked through one or two additional six-membered rings).

[0039] 2. For the monooxygen-bridged cyclized Ni(II)-OxNor: Due to its enhanced global aromaticity and the electron density rearrangement caused by the oxygen bridge, its highest occupied molecular orbital is highly localized on a specific β-carbon atom adjacent to the oxygen bridge. This results in the molecule covalently linking almost exclusively (selectivity >95%) through this pair of β sites on the surface, generating only one structurally defined β-β dimer.

[0040] Regulatory Logic and Causal Relationship: This invention thus establishes and verifies a universal regulatory logic: by controlling the number of oxygen editing instructions in the precursor, the aromaticity intensity of the product can be programmably set → aromaticity determines the spatial distribution of the leading orbitals → the orbital distribution activates specific edge atoms → the activated atoms dominate the covalent reaction pathway on the surface. This achieves rational prediction and precise synthesis from molecular structure design to surface reaction products.

[0041] Preferred embodiments of the present invention:

[0042] 1. The surface of the metal single crystal is preferably a gold, silver or copper single crystal with a face-centered cubic (111) crystal plane, and most preferably Au(111).

[0043] 2. The preferred temperature range for the heat annealing treatment is 480 K to 520 K, in order to achieve complete cyclization and avoid excessive decomposition.

[0044] 3. The surface deposition is preferably carried out in an ultra-high vacuum environment to ensure surface cleanliness and process controllability.

[0045] Compared with existing surface chemistry methods described in the background section, the "oxygen atom directional framework editing" strategy and its products provided by this invention, by embedding chemical doping instructions into the molecular precursor, achieve fully programmable design from molecular structure to surface reaction, bringing the following significant and interrelated beneficial effects:

[0046] Compared with existing surface chemistry methods described in the background art, the oxygen-bridged framework editing strategy and its products provided by this invention, by pre-placing chemical doping structures in the molecular precursor, enable the molecular framework adjustment to be completed before deposition onto the surface and to be retained and manifested in subsequent surface reactions, thereby exhibiting systematic differences in aromaticity characteristics and surface reaction behavior, specifically reflected in the following aspects:

[0047] 1. This invention achieves continuous regulation of the aromaticity distribution characteristics of surface molecules. In existing technologies, the means to structurally regulate the global aromaticity of a single molecule under solid surface conditions are relatively limited. This invention obtains a series of cyclic macrocycles with different aromaticity characteristics on the Au(111) surface by controlling the number of oxygen atoms inserted in the precursor (0, 1, and 2 respectively). Experimental characterization and theoretical calculations (such as isochemical shielding surface analysis and geometric aromaticity index calculation) show that: from the undoped cyclic product Ni(II)-Nor (whose aromaticity exhibits fragmented characteristics), to the single-oxygen-doped Ni(II)-OxNor (whose aromaticity distribution range expands), and then to the double-oxygen-doped Ni(II)-2OxNor (whose peripheral region exhibits a more continuous aromaticity distribution), the aromaticity distribution shows a gradient trend with the change in the number of oxygen bridges, realizing a continuous and controllable evolution of aromaticity from local localization to global delocalization. The above results indicate that the number of oxygen bridges can be used as a structural variable to regulate the aromaticity distribution characteristics.

[0048] 2. This invention establishes a correspondence between aromaticity regulation and surface reaction pathways. Existing surface synthesis systems often exhibit diverse reaction pathways and dispersed product distribution. Experimental results from this invention show that for undoped cyclized Ni(II)-Nor, its dispersed electron distribution allows it to react via multiple sites such as β, δ, and ζ at the molecular edge, generating three covalent dimers with different structures. However, cyclized Ni(II)-OxNor, after single-oxygen editing, primarily forms a β–β dimer structure linked by specific β-carbon atom pairs under the same surface reaction conditions. This comparative result demonstrates a clear correlation between the degree of framework editing and reaction pathway selectivity, and the experimentally observed reaction pathway selectivity represents a fundamental breakthrough from multi-path random coupling to precise single-path synthesis.

[0049] 3. This invention reveals the modulating effect of skeletal editing on the frontier electron distribution of molecules. Density functional theory calculations show that in Ni(II)-OxNor with a single oxygen bridge, the highest occupied molecular orbital has a high electron density distribution at the β-carbon atom adjacent to the oxygen bridge, while the distribution at other edge sites is relatively weakened. This electron distribution characteristic is consistent with experimental observations that the molecule mainly couples via β sites, indicating an intrinsic link between precursor structure editing and the final reaction site.

[0050] 4. This invention deepens our understanding of the role of heteroatom-bridging structures in surface macrocyclic systems. Comprehensive experimental characterization and theoretical analysis (such as anisotropic induced current density analysis) show that in the cyclized macrocyclic system, C–O–C bridging bonds participate in the construction of molecular electron delocalization pathways and regulate the overall electron distribution range. This analysis helps to understand the influence of oxygen bridging structures on aromaticity and reaction behavior in this system.

[0051] 5. This invention achieves continuous, precise, and intrinsic regulation of surface molecular aromaticity. Existing technologies struggle to quantitatively regulate the global aromaticity of single molecules on a surface. This invention successfully prepared a series of cyclic macrocycles with progressively enhanced aromaticity on the Au(111) surface by controlling the number of oxygen atoms inserted in the precursor (0, 1, and 2 in sequence). Experimental characterization and theoretical calculations (such as isochemically shielded surface analysis and geometric aromaticity index calculations) jointly confirmed that the aromaticity evolved continuously and controllably from "local localization" to "global delocalization" from undoped cyclic products (Ni(II)-Nor, whose aromaticity exhibits fragmented characteristics), to monooxygen-doped cyclic products (Ni(II)-OxNor, whose aromaticity is significantly enhanced and its range is expanded), and then to dioxygen-doped cyclic products (Ni(II)-2OxPor, forming a strong and continuous global aromatic circulation). This regulation achieved through intrinsic chemical structure editing has a precision and reliability far exceeding that of indirect methods such as external physical field perturbation.

[0052] 6. This invention establishes a direct causal relationship from aromaticity regulation to reactivity guidance, achieving a leap in the selectivity of surface reactions. Existing surface synthesis often faces the challenges of uncontrollable reaction pathways and product mixing. This invention clearly demonstrates for the first time that by controlling aromaticity through the aforementioned skeleton editing, the frontal electron density distribution of molecules can be directly rearranged, thereby precisely "activating" specific reaction sites. Specific experimental results show that for undoped cyclized Ni(II)-Nor, its dispersed electron density allows it to react through multiple sites such as β, δ, and ζ at the molecular edge, ultimately generating three covalent dimers with distinct structures. However, after single-oxygen editing, cyclized Ni(II)-OxNor, under identical surface reaction conditions, exhibits a highly convergent product structure, consisting of only one dimer linked by specific β-carbon atom pairs. The experimentally observed reaction pathway selectivity represents a fundamental breakthrough from "multi-path random coupling" to "single-path precise synthesis." This phenomenon has been directly verified by high-resolution scanning tunneling microscopy and non-contact atomic force microscopy imaging.

[0053] 7. This invention provides a universal and predictable rational paradigm for constructing surface molecules. This invention reveals and verifies a universal logical chain of "skeleton editing instructions → aromaticity programming → orbital distribution → site activation → reaction path". This means that for systems of the same series or similarity, the main products of surface reactions can be predicted before experimentation simply by designing the doping mode of the precursor, greatly reducing the trial-and-error costs in traditional surface synthesis and providing a novel and rational design tool for constructing complex and functional surface molecular structures and devices.

[0054] 8. This invention deepens the understanding of surface interface chemistry processes and reveals a new role for oxygen atoms. Contrary to the traditional understanding that oxygen atoms primarily act as π-electron donors, comprehensive characterization and theoretical calculations (such as anisotropic induced current density analysis) in this invention show that in the cyclocyclic macrocyclic system, oxygen atoms mainly act as "σ-conjugation hubs," magnetically coupling adjacent aromatic segments through their in-plane lone pair electrons participating in σ-electron delocalization. This mechanism not only rationally explains the superior regulatory effect of this invention but also provides new design ideas and theoretical basis for future performance regulation using heteroatoms in surface chemistry. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the technical route of the present invention;

[0056] Figure 2 The structural characterization diagrams of the cyclized Ni(II)-Nor, Ni(II)-OxNor, and Ni(II)-2OxPor on the Au(111) surface of the present invention are shown.

[0057] Figure 3 This diagram shows experimental evidence of the electronic structure evolution caused by oxygen atom editing in this invention.

[0058] Figure 4 This is a diagram illustrating the comprehensive theoretical calculation evidence for the oxygen atom editing regulation of global aromaticity in this invention.

[0059] Figure 5 The structural characterization and comparison diagrams show the surface dimerization behavior of different cyclization products of the present invention;

[0060] Figure 6 This is a comparison diagram of the frontier molecular orbitals of the dimers formed by cyclized Ni(II)-Nor and cyclized Ni(II)-OxNor of the present invention. Detailed Implementation

[0061] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the following examples provide a more detailed description of the invention. It should be noted that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0062] The oxygen-bridging skeleton editing strategy and its technical approach provided by this invention are as follows: Figure 1 As shown. Figure 1 a represents the molecular structural formulas of three nickel(II) norcarbole precursors with different numbers of oxygen atoms (0, 1, and 2), denoted as Ni(II)-Nor, Ni(II)-OxNor, and Ni(II)-2OxNor, respectively. Figure 1b is a schematic diagram of the cyclization and dehydrogenation reaction of the precursor on the Au(111) surface after thermal annealing. After the reaction, a planar cyclized macrocycle is formed. The diagram marks the sites (β, δ, ζ) at the molecular edge that may participate in subsequent reactions. Figure 1 c illustrates the surface covalent coupling results of the cyclization products: undoped Ni(II)-Nor can form various dimer structures, while monooxygen-doped Ni(II)-OxNor mainly forms dimers linked by β-β sites. The core of this invention lies in: pre-synthesizing nickel(II) norcarbole derivatives with different numbers of oxygen atoms at the pyrrole-pyrrole linkages as precursors ( Figure 1 a); After depositing the precursor on the metal surface, a surface-assisted cyclization and dehydrogenation reaction is triggered by thermal annealing to form a planar cyclized macrocycle ( Figure 1 b); Cycloning products with different oxygen doping levels exhibit different covalent coupling behaviors under the same surface conditions. Among them, undoped products can form various dimers, while monooxygen-doped products mainly form β-β dimers. Figure 1 c). The following embodiments provide a detailed description of the specific implementation of this technical approach.

[0063] Unless otherwise specified, all embodiments of the present invention are performed in a standard ultra-high vacuum (UHV) system (base pressure <1×10⁻⁶). - 10 The process was carried out in mbar. The surface of the metal single crystal used (such as Au(111)) was cleaned by cyclic argon ion sputtering (energy 500 eV) and annealing (approximately 720 K). The thermal annealing was performed using a sample stage heated by direct current or a radiation heater, with a controllable heating rate. Example 1: Preparation of cyclocarboxylated nickel(II)-nor (Ni(II)-Nor)

[0064] First, Ni(II)-Nor precursor powder (corresponding to) was prepared using a known organic synthesis method in the literature. Figure 1 (Structure a, leftmost). In ultra-high vacuum (UHV, base pressure <1×10⁻⁶). -10 In an environment of mbar, clean Au(111) single crystals were placed at room temperature. Ni(II)-Nor powder was loaded into a degassed Knudsen cell and heated to approximately 500 K, causing it to sublimate and deposit onto the Au(111) surface, forming a submonolayer coating. Subsequently, the sample was heated to 480 K at a rate of approximately 1 K / s and held for 10 minutes to complete the surface-assisted cyclization dehydrogenation reaction (corresponding to...). Figure 1 (See process b). After natural cooling to a low temperature (~4.5 K), the cyclized Ni(II)-Nor product was obtained.

[0065] Example 2: Preparation of cyclized monooxygen-bridged nickel(II) norcarbole (Ni(II)-OxNor)

[0066] The preparation steps are the same as in Example 1, but the precursor is replaced with Ni(II)-OxNor powder obtained by organic synthesis (its molecular structure contains an oxygen bridge, corresponding to...). Figure 1 (a) Intermediate structure). After sublimation, deposition, and 480 K thermal annealing under the same conditions ( Figure 1 (b) Obtain the cyclized Ni(II)-OxNor product. This step realizes the design of the oxygen-containing precursor and the surface thermal activation cyclization and editing effect in the technical solution.

[0067] Example 3: Preparation of cyclized hydrogen oxide-bridged nickel(II) norcarbole (Ni(II)-2OxPor)

[0068] The preparation steps are the same as in Example 1, but the precursor is replaced with Ni(II)-2OxPor powder obtained by organic synthesis (its molecular structure contains two oxygen bridges, corresponding to...). Figure 1 (The rightmost structure in a). After sublimation, deposition, and 480 K thermal annealing under the same conditions ( Figure 1 (b) Obtain the cyclized Ni(II)-2OxPor product. This step realizes the design of the oxygen-containing precursor and the surface thermal activation cyclization and editing effect in the technical solution.

[0069] Comparative Example 1: Comparison of precursor molecules without cyclization

[0070] After depositing the Ni(II)-OxNor precursor on the Au(111) surface according to the steps in Example 2, it was not subjected to thermal annealing at 480 K, and its uncyclized initial adsorption state was maintained as a control sample.

[0071] Structural characterization

[0072] STM and nc-AFM imaging ( Figure 2 (a) Molecular structural formulas of three nickel(II) norcarbol solution precursors (Ni(II)-Nor, Ni(II)-OxNor, Ni(II)-2OxPor) with definite oxygen atom numbers (0, 1, 2).

[0073] (b) Schematic diagram of the process by which the precursor is cyclized and dehydrogenated on the Au(111) surface by thermal annealing to generate planar cyclic macrocyclic molecules. The edge sites (β, δ, ζ) with different reactivity are marked in the figure. (c) Comparison of experimental results of further covalent coupling of cyclized products on the surface: It can be seen intuitively that cyclized Ni(II)-Nor can form a variety of dimers, while cyclized Ni(II)-OxNor only generates a single β-β dimer: Cyclolated products obtained in Examples 1-3 in large-area STM images ( Figure 2 All molecules in the high-resolution STM images (ac) showed well-dispersed single molecules. Figure 2The df) matches the superimposed density functional theory (DFT) optimized structure model. Key evidence comes from constant-height mode non-contact atomic force microscopy (nc-AFM) images. Figure 2 gi): Images of cyclized Ni(II)-Nor ( Figure 2 g) shows a complete carbon skeleton; while cyclized Ni(II)-OxNor ( Figure 2 h) and cyclized Ni(II)-2OxPor ( Figure 2 In image i), prominent bright spots are clearly visible at the bridging positions of the molecular backbone, directly corresponding to the incorporated oxygen atoms, which intuitively proves that oxygen atoms are retained and integrated into the final molecular backbone during the surface cyclization process.

[0074] Electronic structure characterization Figure 3 (ac) represents the representative scanning tunneling spectra (dI / dV spectra) of cyclosubstituted Ni(II)-Nor, Ni(II)-OxNor, and Ni(II)-2OxPor on Au(111), showing their frontier orbital (HOMO, LUMO) resonance peaks and band gaps. (df) represents the experimental dI / dV space mapping diagrams of cyclosubstituted Ni(II)-OxNor at the HOMO and LUMO energy levels, showing the actual distribution of its frontier electron density. A systematic scanning tunneling spectroscopy (STS) measurement was performed on the three cyclosubstituted products obtained in Examples 1-3. Figure 3 As shown in Figure ac, the dI / dV spectra of single molecules of cyclosubstituted Ni(II)-Nor, cyclosubstituted Ni(II)-OxNor, and cyclosubstituted Ni(II)-2OxPor all exhibit clear frontier orbital resonance peaks. Among them, cyclosubstituted Ni(II)-Nor ( Figure 3 a) The HOMO and LUMO are located at -0.80 V and +0.76 V, respectively, with a band gap of approximately 1.56 eV; cyclosubstituted Ni(II)-OxNor ( Figure 3 b) The resonance peaks are located at -1.02 V and +0.88 V, with a band gap of 1.90 eV; cyclosubstituted Ni(II)-2OxPor ( Figure 3 The resonance peaks of c) are located at -1.10 V and +1.00 V, with a band gap of approximately 2.10 eV. This data sequence shows a correspondence between the number of oxygen atoms and the band gap and energy level positions of the cyclization product. Furthermore, spatially resolved dI / dV mapping of cyclized Ni(II)-OxNor (…) Figure 3 The df) shows that the HOMO electron density is strongest in the region near the oxygen bridge, which directly confirms the rearrangement effect of oxygen atom editing on the spatial distribution of the leading orbit.

[0075] Aromatic theory analysis ( Figure 4(ac) Magnetic shielding evidence: Calculated diagrams of two-dimensional isochemical shielding surfaces (ICSSzz) for cyclized Ni(II)-Nor, Ni(II)-OxNor, and Ni(II)-2OxPor, respectively. (df) Geometric structure evidence: Corrected geometric aromaticity index (HOMAc) analysis diagrams for cyclized Ni(II)-Nor, Ni(II)-OxNor, and Ni(II)-2OxPor, respectively. : DFT calculations were performed on the cyclization products of Examples 1-3. Calculated diagrams of two-dimensional isochemical shielding surfaces (ICSSzz) Figure 4 The results (ac) show that, from cyclized Ni(II)-Nor to cyclized Ni(II)-2OxPor, the magnetically shielded region (red) characterizing aromaticity gradually expands and strengthens from two isolated segments, eventually forming a continuous shielding ring around the molecule. Simultaneously, the geometric aromaticity index (HOMAc) analysis ( Figure 4 The data (df) showed that the HOMAc value of the critical ring increased with the number of oxygen atoms (e.g., from 0.89 to 0.92 for a certain benzene ring), which geometrically confirmed the continuous enhancement of aromaticity. These results indicate a correlation between the number of oxygen bridges and the aromaticity distribution characteristics of the cyclization products.

[0076] Surface reaction performance testing, such as Figure 5 As shown, (ac) are scanning tunneling microscope (STM) images and structural models of three different covalent dimers formed on Au(111) by cyclized Ni(II)-Nor. (d) are STM images and structural models of a single β-β dimer of cyclized Ni(II)-OxNor under the same conditions. (eg) are non-contact atomic force microscopy (nc-AFM) atomic-resolution images of each dimer in (ac). (h) is the nc-AFM atomic-resolution image of the β-β dimer in (d).

[0077] The monomer samples obtained in Example 1 (cyclized Ni(II)-Nor) and Example 2 (cyclized Ni(II)-OxNor) were subjected to secondary annealing at slightly higher temperatures (500-520 K) to induce intermolecular covalent coupling. For cyclized Ni(II)-Nor, STM observation revealed that it could form various covalent dimers with different structures. Figure 5 ac shows STM images of three representative structures (corresponding to) Figure 1 c. Upper path). For cyclized Ni(II)-OxNor, under the same conditions, STM observations revealed that a dimer mainly forms ( Figure 5 d, corresponding to Figure 1 (c Lower path). Subsequently, the observed dimer was imaged at atomic resolution using non-contact atomic force microscopy (nc-AFM) to confirm its structure. Figure 5 eg corresponds to respectively Figure 5 The nc-AFM images of the three cyclized Ni(II)-Nor dimers in ac clearly revealed their respective linkage modes. Figure 5 Image h shows the nc-AFM image of the cyclized Ni(II)-OxNor monodimer. Its atomic-level structure clearly shows that the two macrocyclic molecules are directly covalently linked head-to-head (i.e., β-β linkage) through two specific β-carbon atoms. The atomic-resolution nc-AFM image reveals that the undoped product can form various dimers with different structures, while the monooxygen-doped product mainly forms a β-β dimer structure. This comparison directly confirms that monooxygen editing can guide reaction sites, achieving highly selective surface assembly.

[0078] Analysis of reaction selectivity mechanism ( Figure 6 (a, b) DFT-calculated isosurface plots of LUMO(a) and HOMO(b) for lateral β-β dimers of cyclized Ni(II)-Nor; (c, d) DFT-calculated isosurface plots of LUMO(c) and HOMO(d) for cyclized Ni(II)-Nor dimers connected by one six-membered ring; (e, f) DFT-calculated isosurface plots of LUMO(e) and HOMO(f) for cyclized Ni(II)-Nor dimers connected by two six-membered rings; (g, h) DFT-calculated isosurface plots of LUMO(g) and HOMO(h) for cyclized Ni(II)-OxNor mono-β-β dimers: To explain the above distinct dimerization behaviors, ... Figure 5 All observed dimers were subjected to DFT calculations to obtain their frontier molecular orbitals (FMOs). For example... Figure 6 As shown, the FMO of various dimers of cyclized Ni(II)-Nor exhibits diverse distribution patterns at the junctions. Figure 6 The presence of af indicates that its monomers can react through multiple electronic coupling mechanisms. In contrast, the single β-β dimer of cyclized Ni(II)-OxNor exhibits highly localized HOMO and concentration at the β-β linkage sites ( Figure 6 The gh indicates that this specific connection mode possesses optimal orbital overlap and electronic stability. This elucidates, at the root of electronic structure, how oxygen atom editing guides the reaction pathway from divergent to convergent, fully revealing how... Figure 1 The "edit-control-guide" logical chain shown.

[0079] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. An oxygen bridging method for regulating the aromaticity and surface reactivity of nickel(II) norcarbole derivatives, characterized in that, Includes the following steps: (1) Synthesize nickel(II) norcarbole derivatives in solution phase and insert oxygen atoms into 0, 1 or 2 pyrrole-pyrrole direct linkages to form C-O-C bridged structures, thereby obtaining precursor molecules containing different numbers of oxygen bridges; (2) The precursor molecules are deposited on the metal surface and subjected to thermal annealing under vacuum or inert atmosphere to induce surface-assisted dehydrogenation cyclization reaction, thereby obtaining cyclized macrocyclic products. In step (1), the oxygen atom inserted is retained and integrated into the molecular backbone of the cyclized macrocyclic product during the thermal annealing process.

2. The method according to claim 1, characterized in that, The precursor includes: Oxygen-free nickel(II) norcarbole derivatives, hereinafter referred to as Ni(II)-Nor; A nickel(II) norcarbole derivative with an oxygen atom inserted at a pyrrole-pyrrole linker, hereinafter referred to as Ni(II)-OxNor; A nickel(II) norcarbole derivative, hereinafter referred to as Ni(II)-2OxNor, is formed by inserting an oxygen atom into each of two different pyrrole-pyrrole linkages. The introduction of the oxygen atoms is completed before the molecules are deposited onto the metal surface.

3. The method according to claim 1 or 2, characterized in that, The metal surface is an Au, Ag, or Cu single crystal surface.

4. The method according to claim 1, characterized in that, The heat annealing temperature is 350 K–650 K.

5. The method according to claim 1, characterized in that, The cyclized macrocyclic product is a planar nickel(II) norcarboxylic acid derivative, with an additional benzene ring structure formed around it through dehydrogenation cyclization.

6. The method according to claim 1, characterized in that, The second step is specifically as follows: Thermally activated cyclization: The annealing temperature needs to be sufficient to trigger a surface-assisted cyclization dehydrogenation reaction, causing the substituents on the periphery of the precursor molecule to close the ring with the core macrocycle, forming a completely planar, extended π-conjugated cyclized macrocycle structure. Editing effect takes effect: In this process, the oxygen atoms pre-implanted in the precursor are retained and integrated into the backbone of the final product, forming a stable COC bridging structure; the number of oxygen atoms (0, 1, 2) is directly used as a programmable variable, which determines the final electronic structure and chemical properties of the cyclization product.

7. The method according to claim 2, characterized in that, Cycloning products with different numbers of oxygen bridges form dimers with different structures under the same annealing conditions, among which: Ni(II)-Nor forms dimers with various structures; Ni(II)-OxNor mainly forms dimers linked by β–β sites.

8. The cyclized macrocyclic product prepared by the method according to any one of claims 1–7, characterized in that: The product is a planar nickel(II) norcarbole derivative containing 0, 1, or 2 C–O–C bridging bonds.

9. The product according to claim 8, characterized in that, The C–O–C bridging bond alters the aromaticity of the cyclized macrocyclic product.

10. An application of the product as described in claim 8, characterized in that, Used to construct dimers or higher-order covalently assembled structures on metal surfaces via covalent coupling reactions.

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