N-Cu-N single metal bridged metal organic chain at room temperature and preparation method thereof

Abstract

The invention relates to an N-Cu-N single metal bridged metal organic chain at room temperature and a preparation method thereof, and belongs to the technical field of nano materials. According to the preparation method, a copper single crystal is selected as a substrate, nitrogen-containing precursor molecules are evaporated and deposited on the copper single crystal substrate at a low temperature to obtain a molecular monomer structure deposited on the substrate, and the temperature of the copper single crystal substrate is controlled to be-70 DEG C in the deposition process; a substrate and precursor molecules deposited on the substrate are heated to the room temperature for the first time for heat preservation treatment, and an N-Cu-N single-metal bridged metal organic chain formed by coordination of N and Cu atoms on the substrate after molecular bond breaking at the room temperature can be successfully obtained. The method has the advantages of mild reaction conditions, accurate and controllable structure, high product stability and the like, and is suitable for the fields of monomolecular devices, catalysis, sensing and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nanomaterials, in particular to a synthesis and preparation method of N-Cu-N single-metal bridged metal-organic chain at room temperature. BACKGROUND

[0002] Metal-organic chain is a one-dimensional structure formed by metal atoms and organic ligands connected by coordination bond, which has excellent electron transport performance, structure controllability and potential application value in single-molecule device. Among them, N-M-N (M is metal) structure is widely studied due to its high directionality and stability. At present, the synthesis of metal-organic chain mostly depends on high-temperature annealing or solution method, which has problems such as harsh reaction conditions, uncontrollable structure and many side reactions. Especially in the metal bridged structure, the number and position of metal atoms are difficult to control accurately, which limits its further application. In recent years, the development of surface synthesis technology provides the possibility for the atomic-level precise construction of metal-organic structure. For example, Sun et al. reported a multi-copper atom bridged metal-organic oligomer, but its synthesis still needs annealing at 100℃ or above, and the structure contains multiple copper atoms, which is not conducive to the structure uniformity and performance regulation. Therefore, it is of great scientific significance and application value to develop a method for preparing metal-organic chain with clear structure and controllable number of metal atoms under mild conditions. SUMMARY

[0003] In view of the problems and deficiencies of the prior art, the present application provides a N-Cu-N single-metal bridged metal-organic chain and a preparation method thereof at room temperature. The present application utilizes the strategy that phenazine precursor molecules will undergo a graded chemical reaction to form a metal-organic chain under the catalytic induction of a copper substrate, deposits phenazine precursor molecules onto the surface of a copper substrate to obtain a sample with a phenazine monomer structure on the copper substrate, heats the sample to room temperature, and then anneals the sample to obtain a N-Cu-N single-metal bridged metal-organic chain.

[0004] A N-Cu-N single-metal bridged metal-organic chain and a preparation method thereof at room temperature, the specific steps of which include: Step 1, preparing a copper single crystal substrate; Step 2, evaporating and depositing phenazine precursor molecules on the copper single crystal substrate of step 1 to obtain a substrate and a phenazine monomer structure deposited on the substrate, and the deposition process controls the temperature of the phenazine structure on the substrate and the copper single crystal substrate to be lower than -70℃; Step 3, annealing the substrate and the phenazine monomer structure deposited on the substrate of step 2 to obtain a N-Cu-N single-metal bridged metal-organic chain formed by the coordination of N and Cu atoms on the substrate after the bond breaking of phenazine molecules.

[0005] The preparation process of the copper single crystal substrate is specifically: Step 1.1, argon ion sputtering treatment is performed on the copper substrate in an ultra-high vacuum chamber to obtain a copper substrate; Step 1.2, the copper substrate obtained in step 1.1 is heated to 450 DEG C and kept for 20 min to obtain a clean and flat copper single crystal substrate.

[0006] The evaporation temperature of the phenazine precursor molecule in step 2 is room temperature, and the deposition time is 1 min to 3 min.

[0007] The annealing temperature in step 3 is room temperature, and the holding time is 20-60 min.

[0008] The beneficial effects of the present application are: (1) The present application can prepare a large-area metal organic chain product, and the internal structure of the product is one-dimensional order; (2) The metal organic chain product prepared by the present application is a N-Cu-N single metal bridging one-dimensional structure formed by the coordination of N and Cu atoms on the substrate after the intramolecular bond of each phenazine molecule is broken; (3) The metal organic chain product prepared by the present application can be obtained at room temperature. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is the reaction path diagram proposed by the embodiment of the present application; Figure 2 is the scanning tunneling microscope high-resolution image (Fig. a, b), the bond-resolved scanning tunneling microscope image (Fig. c), and the model structure diagram (Fig. d) of the phenazine precursor molecule evaporated and deposited on the copper single crystal substrate to obtain the substrate and the phenazine monomer structure deposited on the substrate prepared by the embodiment of the present application; Figure 3 is the scanning tunneling microscope high-resolution image (Fig. a, b), the bond-resolved scanning tunneling microscope image (Fig. c), and the model structure diagram (Fig. d) of the N-Cu-N single metal bridging metal organic chain prepared by the embodiment of the present application at room temperature. DETAILED DESCRIPTION

[0010] The present application will be further described below in conjunction with the drawings and specific embodiments.

[0011] Low-temperature scanning tunneling microscope: purchased from German Omicron company.

[0012] K-cell molecule evaporation source: purchased from German Omicron company.

[0013] Argon ion gun: purchased from German Omicron company.

[0014] Phenazine precursor molecule: purchased from Bid pharmaceutical, purity 98%.

[0015] Copper single crystal: purchased from MaTecK, purity 99.999%. Example 1

[0016] The method for preparing the N-Cu-N single-metal bridged metal organic chain on Cu(111) at room temperature, the specific steps of which include: Step 1, preparing a copper single crystal substrate; the preparation process of the copper single crystal substrate, specifically: Step 1.1, in an ultra-high vacuum chamber, performing argon ion sputtering treatment on a copper substrate to obtain a copper substrate; Step 1.2, heating the copper substrate obtained in step 1.1 to 450°C and keeping it for 20 min to obtain a copper single crystal substrate; Step 2, evaporating and depositing 2 mg of phenazine powder on the copper single crystal substrate of step 1 at an evaporation temperature of 25°C using a thermal resistance K-cell molecular evaporation source to obtain a substrate and a phenazine monomer structure deposited on the substrate, and the copper single crystal substrate temperature is controlled to be lower than -70°C during the deposition process, and the deposition time is 2 min; Step 3, performing a first temperature rise to room temperature for the substrate and the phenazine monomer structure deposited on the substrate of step 2 for annealing treatment; keeping it for 60 min to obtain an N-Cu-N single-metal bridged metal organic chain formed by the coordination of N and Cu atoms on the substrate after the intramolecular bond is broken. Example 2

[0017] The method for preparing the N-Cu-N single-metal bridged metal organic chain on Cu(111) at room temperature, the specific steps of which include: Step 1, preparing a copper single crystal substrate; the preparation process of the copper single crystal substrate, specifically: Step 1.1, in an ultra-high vacuum chamber, performing argon ion sputtering treatment on a copper substrate to obtain a copper substrate; Step 1.2, heating the copper substrate obtained in step 1.1 to 450°C and keeping it for 20 min to obtain a copper single crystal substrate; Step 2, evaporating and depositing 10 mg of phenazine powder on the copper single crystal substrate of step 1 at an evaporation temperature of 30°C using a thermal resistance K-cell molecular evaporation source to obtain a substrate and a phenazine monomer structure deposited on the substrate, and the copper single crystal substrate temperature is controlled to be lower than -70°C during the deposition process, and the deposition time is 2 min; Step 3, performing a first temperature rise to room temperature for the substrate and the phenazine monomer structure deposited on the substrate of step 2 for annealing treatment; keeping it for 60 min to obtain an N-Cu-N single-metal bridged metal organic chain formed by the coordination of N and Cu atoms on the substrate after the intramolecular bond is broken. Example 3

[0018] The preparation method of the room-temperature N-Cu-N single-metal bridging metal organic chain on Cu(111) includes the following steps: Step 1, preparing a copper single crystal substrate; the preparation process of the copper single crystal substrate is as follows: Step 1.1, performing argon ion sputtering treatment on the copper substrate in an ultrahigh vacuum cavity to obtain a copper substrate; Step 1.2, heating the copper substrate obtained in step 1.1 to 450 DEG C and keeping the temperature for 20 min to obtain a copper single crystal substrate; Step 2, evaporating and depositing 2 mg of phenazine powder on the copper single crystal substrate obtained in step 1 at an evaporation temperature of 25 DEG C by using a thermal resistance type K-cell molecular evaporation source to obtain a substrate and a phenazine monomer structure deposited on the substrate, and the copper single crystal substrate temperature is controlled to be lower than -70 DEG C during the deposition process, and the deposition time is 2 min; Step 3, performing first temperature rising to room temperature for the substrate and the phenazine monomer structure deposited on the substrate in step 2 for heat preservation treatment; keeping the temperature for 50 min to obtain N-Cu-N single-metal bridging metal organic chains formed by the coordination of N and Cu atoms on the substrate after the intramolecular bond is broken.

[0019] The reaction path of the N-Cu-N single-metal bridging metal organic chain prepared in the embodiment is shown in Figure 1 , and it can be seen from Figure 1 that the product of the present application is a metal organic chain obtained by the reaction of the phenazine precursor molecule on the Cu(111) substrate after being heated to room temperature.

[0020] The high-resolution scanning tunneling microscope images (a, b, c) of the phenazine precursor molecule evaporated and deposited at low temperature on the copper single crystal substrate to obtain a substrate and a phenazine monomer structure deposited on the substrate prepared in the example are shown in Figure 2 , and the model structure diagram (d) is shown in Figure 2 . It can be clearly observed from Figure 2 that the molecular arrangement and monomer structure information of the phenazine precursor molecule deposited on the copper substrate at low temperature.

[0021] Figure 3 The high-resolution scanning tunneling microscope images (a, b, c) of the N-Cu-N single-metal bridging metal organic chain prepared by the preparation method according to the embodiment of the present application are shown in Figure 3 , and the model structure diagram (d) is shown in Figure 3 . It can be directly observed from Figure 3 that all the monomer molecules are converted into one-dimensional ordered long chains after the sample is heated to room temperature, and the structure information of the product is further verified by the high-resolution scanning tunneling microscope image.

[0022] The specific embodiments of the present application are described above with reference to the accompanying drawings, but the present application is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

Claims

1. A method for preparing a room-temperature N-Cu-N single-metal-bridged metal-organic chain, comprising the following steps: Step 1, preparing a copper single-crystal substrate; Step 2, evaporating and depositing a phenazine precursor molecule on the copper single-crystal substrate of Step 1 at a low temperature to obtain a substrate and a phenazine monomer structure sample deposited on the substrate, and controlling the copper single-crystal substrate temperature to be lower than -70℃ during the deposition process; and Step 3, annealing the substrate and the phenazine monomer structure sample deposited on the substrate of Step 2 to obtain a room-temperature N-Cu-N single-metal-bridged metal-organic chain formed by coordination of N and Cu atoms after breaking of the phenazine molecule. The copper single-crystal substrate is prepared by the following steps: Step 1.1, performing argon ion sputtering treatment on a copper substrate in an ultra-high vacuum chamber to obtain a copper substrate; and Step 1.2, heating the copper substrate obtained in Step 1.1 to 400-500℃ and keeping the temperature for 20-30 min to obtain a copper single-crystal substrate. In Step 2, the evaporation temperature of the phenazine precursor molecule is room temperature, and the deposition time is 1 min-3 min; and the copper single-crystal substrate temperature is controlled to be lower than -70℃ during the deposition process. In Step 3, the annealing temperature is room temperature, and the temperature keeping time is 20-60 min.

2. The room temperature N-Cu-N monometallic bridged metal organic chain according to claim 1, wherein: ​ ​ ​ 3. The room temperature N-Cu-N monometallic bridged metal organic chain of claim 1, wherein: ​ 4. The room temperature N-Cu-N monometallic bridged metal organic chain of claim 1, wherein: ​

Images