Preparation method of one-dimensional graphdiyne chain

Abstract

The invention discloses a preparation method of a one-dimensional graphdiyne chain. According to the preparation method, a silver single crystal substrate with a (110) crystal face is selected as a substrate, precursor molecules PBDA are deposited on the surface of the silver single crystal substrate through a molecular beam epitaxy growth technology to obtain a self-assembly sample, then the self-assembly sample is subjected to gradual annealing treatment to induce a polymerization reaction of the molecules, and the PBDA is prepared. And thus, a one-dimensional graphdiyne chain connected by carbon-carbon triple bonds is obtained. The preparation method of the one-dimensional graphdiyne chain, provided by the invention, has relatively high scientific research value and wide application potential.

Description

Technical Field

[0001] The invention belongs to the field of surface synthesis, and in particular relates to a method for preparing a one-dimensional graphene chain. Background Art

[0002] The carbon-carbon triple bond (–C≡C–) is one of the most basic bonding types in organic chemistry. It is not only the key to the synthesis of carbon allotropes, such as carbene, graphyne, graphynediyne, and one-dimensional graphyne chains, but also plays an irreplaceable role in mechanism research and the manufacture of functionalized devices, such as organic solar cells, optical sensors, and organic field-effect transistors. Incorporating sp-hybridized –C≡C– bonds into the semiconductor core can give it excellent properties. This type of bonding does not have the Z / E isomerization problem, thus avoiding the separation problem caused by multiple isomers. In addition, its introduction can also improve the rigidity of the molecular structure and reduce the amplitude of thermal motion. At the same time, compared with the other two bonding types, the –C≡C– bond can minimize the steric hindrance between adjacent aromatic units, increase the planarity of the molecular system, enhance the π-conjugated properties of the main chain, and ultimately improve the carrier mobility and the transmission capacity of spin electrons.

[0003] Although we have been able to successfully synthesize carbon-carbon triple bonds through the coupling reaction between two ethyl alkynyl ligands in trimolybdenum clusters in traditional solution chemistry, the high molecular weight of polymers generally leads to a significant decrease in their solubility. Therefore, the in situ preparation of such π-conjugated polymers in solution chemistry still faces great challenges.

[0004] It is worth noting that one-dimensional graphdiyne chains and two-dimensional graphdiyne macrocycles bridged by diacetylene groups have been successfully synthesized by using precursor molecules with terminal alkyne, alkynyl bromide or trimethylsilane groups through dehydrogenation or dehalogenation homocoupling reactions. However, as the key component structure of graphdiyne, the synthesis of low-dimensional polymers bridged by acetylene is mainly based on the synthesis of polymers with specific halide substituents (such as –CBr 3 , –CCl 3 , =CBr 2 ) precursors by dehalogenation coupling reaction. In addition, the byproducts produced by the dehalogenation reaction, such as dissociated halogen atoms or edge fusion products, may affect the final product structure or the target intrinsic electronic state. Therefore, exploring cleaner and more efficient strategies to integrate ethynyl scaffolds into carbon-based nanostructures is crucial for the construction of graphyne-based materials, which is expected to bring revolutionary breakthroughs in related fields. Summary of the invention

[0005] In view of the difficulty of introducing carbon-carbon triple bonds to construct a one-dimensional graphyne chain, the present invention proposes a method for preparing a one-dimensional graphyne chain. Specifically, the present invention uses the strategy that PBDA molecules with acetonitrile groups will undergo intermolecular polymerization under the catalytic action of a silver substrate, deposits the precursor molecule PBDA on the surface of the silver substrate, and anneals at 190°C for 20 minutes to obtain polymer 1. Then, the sample is further annealed to 250°C and kept warm for 20 minutes to obtain polymer 2.

[0006] A method for preparing a one-dimensional graphyne chain, the specific steps of which include:

[0007] Step 1, preparing a silver single crystal substrate;

[0008] Step 2, depositing the precursor molecule PBDA onto a silver single crystal substrate maintained at room temperature by molecular beam epitaxy technology;

[0009] Step 3, gradually heating the sample, first annealing to 190°C, keeping the temperature for 20 minutes to obtain polymer 1, and then continuing to anneal to 250°C, keeping the temperature for 20 minutes to obtain polymer 2;

[0010] The preparation process of the silver single crystal substrate is specifically as follows:

[0011] Step 1.1, in an ultra-high vacuum chamber, subjecting a silver substrate to argon ion sputtering to obtain a silver base;

[0012] Step 1.2: Heat the silver substrate obtained in step 1.1 to 450° C. and keep it warm for 10-30 minutes to obtain a silver single crystal substrate.

[0013] In step 2, the evaporation temperature of the precursor molecule PBDA is 130° C., and the deposition time is 10 minutes.

[0014] In step 3, the growth temperature of polymer 1 is 190° C. and the temperature is kept for 20 minutes. The growth temperature of polymer 2 is 250° C. and the temperature is kept for 20 minutes.

[0015] The beneficial effects of the present invention are:

[0016] (1) The present invention utilizes acetonitrile-functionalized precursor molecules to construct carbon-carbon triple bond-bridged polymers;

[0017] (3) The present invention can construct two different polymers in a temperature-controllable manner; BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The embodiment of the present invention shows the reaction path diagram of PBDA molecules on a silver single crystal substrate;

[0019] Figure 2The scanning tunneling microscope image of the embodiment of the present invention shows the gradual annealing of the precursor PBDA molecule on the surface of the silver single crystal;

[0020] Figure 3 The embodiment of the present invention shows a high-definition bond-resolved scanning tunneling microscope image and a non-contact atomic force microscope image of a one-dimensional graphyne chain. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

[0022] Test instruments and equipment:

[0023] Low-temperature scanning tunneling microscope: purchased from Omicron, Germany.

[0024] K-cell molecular evaporation source: purchased from Omicron, Germany.

[0025] Argon ion gun: purchased from Omicron, Germany.

[0026] raw material:

[0027] Precursor molecule PBDA: synthesized by Professor Chen Long's team from Jilin University, with a purity of 98%.

[0028] Silver single crystal: purchased from MaTecK, purity 99.999%.

[0029] Example

[0030] A method for preparing a one-dimensional graphyne chain, the specific steps of which include:

[0031] Step 1: preparing a silver single crystal substrate; the preparation process of the silver single crystal substrate is specifically as follows:

[0032] Step 1.1, in an ultra-high vacuum chamber, subjecting a silver substrate to argon ion sputtering to obtain a silver base;

[0033] Step 1.2, heating the silver substrate obtained in step 1.1 to 450° C. and keeping the temperature for 10 minutes to obtain a silver single crystal substrate;

[0034] Step 2, 2 mg of precursor molecule PBDA was evaporated at 130° C. using a thermal resistance K-cell molecular evaporation source and deposited on the 50 g silver single crystal substrate in step 1 to obtain a substrate and a PBDA self-assembled structure deposited on the substrate. The temperature of the silver single crystal substrate was controlled to be 25° C. during the deposition process, and the deposition time was 10 minutes;

[0035] Step 3, gradually heating the PBDA molecules on the substrate in step 2 to 190° C., keeping the temperature for 20 minutes, and then continuing to anneal to 250° C., keeping the temperature for 20 minutes;

[0036] The reaction pathway of the PBDA molecule on the silver single crystal substrate proposed in this embodiment is as follows: Figure 1 shown.

[0037] The stepwise annealing results of the PBDA molecules on the silver single crystal substrate proposed in this embodiment are as follows: Figure 2 As shown. At room temperature, PBDA molecules form a head-to-head self-assembled structure on the surface of a silver single crystal. When the annealing temperature reaches 190°C, the molecules will polymerize to form a one-dimensional polymer 1. Polymer 1 tends to be distributed in two single chains close to each other, which is mainly caused by the weak interaction between the cyano group and the adjacent molecular chain. When the annealing temperature reaches 250°C, polymer 1 opens to form a single polymer 2 distributed on the substrate.

[0038] The one-dimensional graphyne chain prepared in this embodiment is as follows Figure 3 High-resolution bond-resolved scanning tunneling microscopy images and non-contact atomic force microscopy images clearly show that the benzene ring units are connected by carbon-carbon triple bonds, proving the successful synthesis of the one-dimensional graphyne chain.

Claims

1. A method for preparing a one-dimensional graphyne chain, characterized in that The specific steps include: Step 1, preparing a silver single crystal substrate; Step 2, depositing the precursor molecule PBDA onto a silver single crystal substrate maintained at room temperature by molecular beam epitaxy technology; Step 3: gradually increase the temperature of the sample, first annealing it to 190°C and keeping it warm for 20 minutes to obtain polymer 1, and then continue to anneal it to 250°C and keep it warm for 20 minutes to obtain polymer 2.

2. The method for preparing a one-dimensional graphyne chain according to claim 1, characterized in that: The preparation process of the silver single crystal substrate is specifically as follows: Step 1.1, in an ultra-high vacuum chamber, subjecting a silver substrate to argon ion sputtering treatment to obtain a silver base; Step 1.2: Heat the silver substrate obtained in step 1.1 to 450° C. and keep it warm for 10-30 minutes to obtain a silver single crystal substrate.

3. A method for preparing a one-dimensional graphyne chain according to claim 1, characterized in that: In step 2, the evaporation temperature of the precursor molecule PBDA is 130° C., and the deposition time is 10 minutes. In step 4, the evaporation temperature of the precursor molecule PBDA is 120° C., and the deposition time is 10 minutes.

4. The method for preparing a one-dimensional graphyne chain according to claim 1, characterized in that: The annealing step in step 3 is divided into two steps, first annealing to 190° C., keeping warm for 20 minutes, and then annealing to 250° C., keeping warm for 20 minutes.

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