A method of regulating crown ether formation chiral self-assembly structure

Abstract

The application relates to the technical field of supramolecular structure chemistry, and provides a method for regulating chiral self-assembly structure formed by crown ether, which comprises the following steps: depositing dibenzo-18-crown-6 molecules on a metal single crystal surface by thermal evaporation under an ultra-high vacuum environment; and complexing alkali metal atoms by depositing alkali metal salt, so that the molecular disorder of the dibenzo-18-crown-6 molecule complex is avoided, the configuration of the dibenzo-18-crown-6 molecule can be effectively regulated, the original assembly structure of the dibenzo-18-crown-6 molecule is further changed, a supramolecular structure with chirality is formed, and atomic resolution characterization is achieved.

Description

Technical Field

[0001] This invention relates to the field of supramolecular structure chemistry, and in particular to a method for regulating the formation of chiral self-assembled structures by crown ethers. Background Technology

[0002] Crown ethers are ethers composed of flexible oligoethers that possess the ability to recognize and bind specific metal atoms and ammonium ions in complex mixtures. Therefore, they hold great potential for constructing supramolecular assemblies in surface chemistry. Crown ethers are a class of macrocyclic compounds with a floral-like molecular structure. Their cavities readily contain alkali metals, alkaline earth metals, or small organic molecules, exhibiting high complexing ability, particularly strong selectivity for most alkali metal ions, and the ability to form stable complexes. They can form supramolecular chiral structures on metal single-crystal surfaces. The dibenzo-18-crown ether-6 molecule consists of two benzene rings symmetrically bonded to the crown ether ring. Therefore, the dibenzo-18-crown ether-6 molecule has significant application potential in the separation, extraction, and preparation of organometallic complexes. Currently, the main research and applications of the dibenzo-18-crown ether-6 molecule are liquid-phase-based, which makes it difficult to perform structural control and atomic-level resolution characterization of crown ether complexes.

[0003] Patent (202211145296.7) discloses a method for regulating the conformation of surface crown ethers, achieving the regulation and selection of the surface crown ether conformation of 18-crown ether-6 molecules. However, 18-crown ether-6 molecules only possess a single crown ether ring, while dibenzo-18-crown ether-6 molecules have two benzene rings connected to the crown ether ring. Compared to 18-crown ether-6 molecules, dibenzo-18-crown ether-6 molecules have a larger overall size and stronger complexing properties. When adsorbed on metal single crystal surfaces, it may form a more stable supramolecular structure, capable of forming specific coordination bonds with metal ions and forming chiral structures through self-assembly. In contrast, the complexing properties of 18-crown ether-6 are relatively weak. Therefore, when adsorbed on metal single crystal surfaces, the adsorption behavior of 18-crown ether-6 is relatively weak, or even unstable.

[0004] However, due to the special structure of the dibenzo-18-crown ether-6 molecule, if the method for regulating the surface crown ether conformation disclosed in patent (202211145296.7) is used to regulate the dibenzo-18-crown ether-6 molecule, the dibenzo-18-crown ether-6 molecule complex will exhibit severe molecular disorder, making subsequent characterization difficult, and even more difficult to achieve atomic-level resolution characterization. Therefore, the exploration of methods for preparing supramolecular chiral structures of dibenzo-18-crown ether-6 molecule complex on metal single crystal surfaces is of great importance. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the related art. To this end, the present invention provides a method for regulating the formation of chiral self-assembled structures of crown ethers, comprising the following steps:

[0006] S1: Under vacuum, crown ether molecules are placed in an organic molecular evaporation source and heated. After sublimation, the crown ether molecules are deposited on the surface of a metal single crystal to obtain a self-assembled structure of crown ether molecules.

[0007] S2: Under vacuum conditions, R-Cl molecules are deposited on the surface of the self-assembled structure of the crown ether molecule to obtain the crown ether-R complex;

[0008] S3: Observe the morphology and structure of crown ether-R complexes under a low-temperature scanning tunneling microscope to form ternary or quaternary assembly structures with chiral structures;

[0009] Where R is Na or K.

[0010] According to the present invention, a method for regulating the formation of a chiral self-assembled structure of a crown ether is provided. In step S3, R is Na, and the morphology and structure of the crown ether-Na complex are observed in a low-temperature scanning tunneling microscope to form a ternary assembly structure with a chiral structure.

[0011] According to the present invention, a method for regulating the formation of chiral self-assembled structures of crown ethers is provided. In step S3, R is K, and the morphology and structure of the crown ether-K complex are observed in a low-temperature scanning tunneling microscope to form a ternary or quaternary assembled structure with a chiral structure.

[0012] According to the present invention, a method for regulating the formation of chiral self-assembled structures of crown ethers is provided, wherein the crown ether is dibenzo-18-crown ether-6.

[0013] According to the present invention, a method for regulating the formation of chiral self-assembled structures of crown ethers is provided, wherein the surface of the metal single crystal is a gold Au(111) surface, a silver Ag(111) surface, or a copper Cu(111) surface.

[0014] According to the present invention, a method for regulating the formation of chiral self-assembled structures of crown ether molecules is provided, wherein the self-assembled structure of the crown ether molecule is a chain-like self-assembled structure.

[0015] According to the present invention, a method for regulating the formation of chiral self-assembled structures of crown ether molecules is provided, wherein the coverage of the self-assembled structures of the crown ether molecules on the surface of the metal single crystal is greater than 0.5 monolayers.

[0016] According to the present invention, a method for regulating the formation of chiral self-assembled structures of crown ethers is provided, wherein the vacuum degree of the vacuum environment is greater than or equal to 1 × 10⁻⁶. -10 mbar.

[0017] According to the method for regulating the formation of chiral self-assembled structures of crown ethers provided by the present invention, the scanning temperature of the low-temperature scanning tunneling microscope in step S3 is 78~79K.

[0018] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0019] This invention provides a method for controlling the formation of chiral self-assembled structures of crown ethers. By thermally evaporating and depositing dibenzo-18-crown ether-6 molecules onto the surface of a metal single crystal under ultra-high vacuum, and then complexing alkali metal atoms by depositing alkali metal salts, this method not only avoids the molecular disorder of the dibenzo-18-crown ether-6 complex but also effectively controls the configuration of the dibenzo-18-crown ether-6 molecule, further altering its original assembly structure and forming a chiral supramolecular structure with atomic-level resolution characterization. This method of constructing crown ether complexes by embedding sodium and potassium atoms on a metal surface has significant implications for the future application of crown ethers in host-guest chemistry and supramolecular structural chemistry.

[0020] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is an image of the self-assembled structure of dibenzo-18 crown ether-6 molecules deposited on the surface of an Au(111) single crystal in a method for regulating the formation of chiral self-assembled structures of crown ethers provided by the present invention.

[0023] Figure 2 This is an image of the self-assembled structure of dibenzo-18 crown ether-6 molecules deposited on the surface of an Ag(111) single crystal in a method for regulating the formation of chiral self-assembled structures of crown ethers provided by the present invention.

[0024] Figure 3 This is an image of the self-assembled structure of dibenzo-18 crown ether-6 molecules deposited on the surface of a Cu(111) single crystal in a method for regulating the formation of chiral self-assembled structures of crown ethers provided by the present invention.

[0025] Figure 4This is a molecular model diagram of the self-assembly structure of the dibenzo-18 crown ether-6 molecule in a method for regulating the formation of chiral self-assembly structures of crown ethers provided by the present invention.

[0026] Figure 5 This is a molecular model diagram of the ternary assembly structure of the crown ether-Na complex with a left-handed chiral structure in a method for regulating the formation of chiral self-assembly structures of crown ethers provided by the present invention.

[0027] Figure 6 This is a molecular model diagram of the ternary assembly structure of the crown ether-Na complex with a dextrorotatory chiral structure in a method for regulating the formation of chiral self-assembly structures of crown ethers provided by the present invention.

[0028] Figure 7 This is an image of a ternary assembly structure of a crown ether-Na complex with a left-handed chiral structure, provided by the present invention as a method for regulating the formation of a chiral self-assembly structure of crown ethers.

[0029] Figure 8 This is an image of a ternary assembly structure of a crown ether-Na complex with a dextrorotatory chiral structure, provided by the present invention as a method for regulating the formation of chiral self-assembly structures of crown ethers.

[0030] Figure 9 This is a molecular model diagram of the ternary assembly structure of the crown ether-K complex with a left-handed chiral structure in a method for regulating the formation of chiral self-assembly structures of crown ethers provided by the present invention.

[0031] Figure 10 This is a molecular model diagram of the ternary assembly structure of the crown ether-K complex with a dextrorotatory chiral structure in a method for regulating the formation of chiral self-assembly structures of crown ethers provided by the present invention.

[0032] Figure 11 This is a molecular model diagram of the quaternary assembly structure of the crown ether-K complex with a chiral structure in the method for regulating the formation of chiral self-assembly structures of crown ethers provided by the present invention.

[0033] Figure 12 This is an image of a ternary assembly structure of a crown ether-K complex with a left-handed chiral structure, provided by the present invention as a method for regulating the formation of a chiral self-assembly structure of crown ethers.

[0034] Figure 13 This is an image of a ternary assembly structure of a crown ether-K complex with a dextrorotatory chiral structure, provided by the present invention as a method for regulating the formation of chiral self-assembly structures of crown ethers.

[0035] Figure 14 This is an image of a quaternary assembly structure of a crown ether-K complex with a chiral structure, provided by the present invention as a method for regulating the formation of a chiral self-assembly structure of crown ethers. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. The following embodiments are used to illustrate this invention but should not be used to limit its scope.

[0037] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0038] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0039] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0040] The following is combined with Figures 1 to 14 This invention describes a method for regulating the formation of chiral self-assembled structures from crown ethers.

[0041] This invention provides a method for regulating the formation of chiral self-assembled structures by crown ethers, comprising the following steps:

[0042] S1: Under vacuum, crown ether molecules are placed in an organic molecular evaporation source and heated. After sublimation, the crown ether molecules are deposited on the surface of a metal single crystal to obtain a self-assembled structure of crown ether molecules.

[0043] In this process, under ultra-high vacuum conditions, a metal single crystal and a crucible are placed in an ultra-high vacuum chamber, and then dibenzo-18 crown ether-6 molecules are placed in the crucible. Further, the crucible is placed in an organic molecular evaporation source for heating. The dibenzo-18 crown ether-6 molecules will undergo thermal sublimation at 80°C and deposit onto the surface of the metal single crystal, forming a self-assembled structure of crown ether molecules.

[0044] Furthermore, in an ultra-high vacuum environment, the dibenzo-18-crown ether-6 molecule undergoes thermal evaporation in an organic molecular evaporation source. Heating to 80°C is required to stably transform the dibenzo-18-crown ether-6 molecule from a solid phase to a gas phase molecule, thereby controlling the deposition rate of the dibenzo-18-crown ether-6 molecule on the surface of a metal single crystal. This further avoids the occurrence of molecular disorder in the subsequent complexation of alkali metal atoms, which would bring difficulties to the characterization operation.

[0045] like Figure 1 As shown, the structure of the dibenzo-18 crown ether-6 molecule on the Au(111) single crystal surface is characterized by the crown ether ring contracting inward, and the self-assembled structure of the crown ether molecule exhibits a chain-like structure.

[0046] like Figure 2 As shown, the structure of the dibenzo-18 crown ether-6 molecule on the Ag(111) single crystal surface is that the crown ether ring contracts inward, and the self-assembled structure of the crown ether molecule exhibits a chain-like structure.

[0047] like Figure 3 As shown, the structure of the dibenzo-18 crown ether-6 molecule on the Cu(111) single crystal surface is that the crown ether ring contracts inward, and the self-assembled structure of the crown ether molecule exhibits a chain-like structure.

[0048] This is because, under the influence of electrostatic potential, the dibenzo-18 crown ether-6 molecules are arranged in a chain-like pattern, such as... Figure 4 As shown, the red spheres represent oxygen atoms, the gray spheres represent carbon atoms, and the white spheres represent hydrogen atoms. The dibenzo-18 crown ether-6 molecule has a positive electrostatic potential at the oxygen atom near the benzene ring, while the oxygen atom in the middle of the crown ether ring has a negative electrostatic potential. Under the influence of electrostatic potential, the dibenzo-18 crown ether-6 molecules are arranged in a chain-like manner.

[0049] S2: Under vacuum conditions, R-Cl molecules are deposited on the surface of the self-assembled structure of the crown ether molecule to obtain the crown ether-R complex;

[0050] S3: Observe the morphology and structure of crown ether-R complexes under a low-temperature scanning tunneling microscope to form ternary or quaternary assembly structures with chiral structures;

[0051] Where R is Na or K.

[0052] According to the present invention, a method for regulating the formation of a chiral self-assembled structure of a crown ether is provided. In step S3, R is Na, and the morphology and structure of the crown ether-Na complex are observed in a low-temperature scanning tunneling microscope to form a ternary assembly structure with a chiral structure.

[0053] In one embodiment, the surface assembly structure of the crown ether-Na complex was observed using a low-temperature scanning tunneling microscope: NaCl was placed in the aforementioned crucible, and when the crucible was heated to 450°C, NaCl thermally deposited onto the dibenzo-18-crown ether-6 molecule on the surface of the metal single crystal. The crown ether ring trapped Na atoms, forming a crown ether-Na complex, as shown below. Figure 5 and Figure 6 As shown, the red spheres represent oxygen atoms, the gray spheres represent carbon atoms, the white spheres represent hydrogen atoms, and the blue spheres represent Na atoms. The crown ether-Na complex exhibits a spindle-shaped structure, with the crown ether ring appearing circular. This indicates that the Na atom has successfully complexed into the interior of the dibenzo-18 crown ether-6 molecule. At this point, the benzene ring position exhibits a negative electrostatic potential, while the oxygen atom position in the center of the crown ether ring exhibits a positive electrostatic potential, thus resulting in a ternary assembly structure with chiral characteristics.

[0054] like Figure 5 and Figure 7 As shown, the crown ether-Na complex has a ternary assembly structure with a left-handed chiral structure.

[0055] like Figure 6 and Figure 8 As shown, the crown ether-Na complex has a ternary assembly structure with a dextrorotatory chiral structure.

[0056] According to the present invention, a method for regulating the formation of chiral self-assembled structures of crown ethers is provided. In step S3, R is K, and the morphology and structure of the crown ether-K complex are observed in a low-temperature scanning tunneling microscope to form a ternary or quaternary assembled structure with a chiral structure.

[0057] In one embodiment, the surface assembly structure of the crown ether-K complex was observed using a low-temperature scanning tunneling microscope: KCl was placed in the aforementioned crucible, and when the crucible was heated to 290°C, KCl thermally deposited onto the dibenzo-18-crown ether-6 molecule on the surface of the metal single crystal. The crown ether ring captured the K atom, forming the crown ether-K complex, as shown below. Figure 9 , Figure 10 and Figure 11As shown, the red spheres represent oxygen atoms, the gray spheres represent carbon atoms, and the white spheres represent hydrogen atoms. Compared to Na atoms, K atoms have a larger diameter, making them more prominent and appearing as purple spheres. The crown ether-K complex exhibits a spindle-shaped structure, with the crown ether ring appearing circular. This indicates that the K atom has successfully complexed into the interior of the dibenzo-18 crown ether-6 molecule. At this point, the benzene ring position exhibits a negative electrostatic potential, while the oxygen atom position in the center of the crown ether ring exhibits a positive electrostatic potential, thus resulting in a ternary or quaternary assembly structure with chiral characteristics.

[0058] like Figure 9 and Figure 12 As shown, the crown ether-K complex has a ternary assembly structure with a left-handed chiral structure.

[0059] like Figure 10 and Figure 13 As shown, the crown ether-K complex has a ternary assembly structure with a dextrorotatory chiral structure.

[0060] like Figure 11 and Figure 14 As shown, the crown ether-K complex has a chiral quaternary assembly structure.

[0061] According to the present invention, a method for regulating the formation of chiral self-assembled structures of crown ethers is provided, wherein the crown ether is dibenzo-18-crown ether-6.

[0062] According to the present invention, a method for regulating the formation of chiral self-assembled structures of crown ethers is provided, wherein the surface of the metal single crystal is a gold Au(111) surface, a silver Ag(111) surface, or a copper Cu(111) surface.

[0063] According to the present invention, a method for regulating the formation of chiral self-assembled structures of crown ether molecules is provided, wherein the self-assembled structure of the crown ether molecule is a chain-like self-assembled structure.

[0064] According to the present invention, a method for regulating the formation of chiral self-assembled structures of crown ether molecules is provided, wherein the self-assembled structures of the crown ether molecules have a coverage of more than 0.5 monolayers on the surface of the metal single crystal.

[0065] Furthermore, the fact that the self-assembled structure of the crown ether molecules has a coverage of more than 0.5 monolayers on the surface of the metal single crystal indicates that after thermal evaporation of dibenzo-18-crown ether-6, it can be stably deposited on the surface of the metal single crystal, avoiding the occurrence of molecular disorder in the subsequent complexation of alkali metal atoms.

[0066] According to the present invention, a method for regulating the formation of chiral self-assembled structures of crown ethers is provided, wherein the vacuum degree of the vacuum environment is greater than or equal to 1 × 10⁻⁶. -10 mbar.

[0067] According to the method for regulating the formation of chiral self-assembled structures of crown ethers provided by the present invention, the scanning temperature of the low-temperature scanning tunneling microscope in step S3 is 78~79K.

[0068] In summary, this invention protects a method for regulating the formation of chiral self-assembled structures of crown ethers. Under ultra-high vacuum conditions, crown ether molecules are deposited onto the surface of a metal single crystal through thermal evaporation, and alkali metal atoms are then complexed to achieve the purpose of regulating the chiral supramolecular structure of the crown ether. Characterization at atomic-level resolution is achieved, which is of great significance for the application of crown ethers in host-guest chemistry and supramolecular structural chemistry.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of modulating the crown-forming chiral self-assembly structure, characterized by, The method comprises the following steps: S1: placing a crown ether molecule in an organic molecule evaporation source and heating under a vacuum environment, subliming and depositing the crown ether molecule to a metal single crystal surface to obtain a self-assembled structure of the crown ether molecule; S2: depositing an R-Cl molecule on the surface of the self-assembled structure of the crown ether molecule under a vacuum environment to obtain a crown ether-R complex; S3: observing the morphology structure of the crown ether-R complex in a low-temperature scanning tunneling microscope to form a ternary or quaternary assembly structure with a chiral structure; wherein R is Na or K, the coverage of the self-assembled structure of the crown ether molecule on the metal single crystal surface is greater than 0.5 monolayer, the crown ether is dibenzo-18-crown-6, and the self-assembled structure of the crown ether molecule is a chain-like self-assembled structure.

2. The method for regulating the formation of chiral self-assembled structures of crown ethers according to claim 1, characterized in that, In the S3 step, the R is Na, the morphology structure of the crown ether-Na complex is observed in a low-temperature scanning tunneling microscope to form a ternary assembly structure with a chiral structure.

3. The method for regulating the formation of chiral self-assembled structures of crown ethers according to claim 1, characterized in that, In the S3 step, the R is K, the morphology structure of the crown ether-K complex is observed in a low-temperature scanning tunneling microscope to form a ternary or quaternary assembly structure with a chiral structure.

4. The method for regulating the formation of chiral self-assembled structures of crown ethers according to claim 1, characterized in that, The metal single crystal surface is a gold Au(111) surface, a silver Ag(111) surface or a copper Cu(111) surface.

5. The method for regulating the formation of chiral self-assembled structures of crown ethers according to claim 1, characterized in that, The vacuum degree of the vacuum environment is greater than or equal to 1×10-10 mbar.

6. The method for regulating the formation of chiral self-assembled structures of crown ethers according to claim 1, characterized in that, The scanning temperature of the low-temperature scanning tunneling microscope in the S3 step is 78-79 K.

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