Copper cluster material and preparation method and application thereof

Abstract

The invention belongs to the field of new materials, and relates to a novel functional material, in particular to a copper cluster material and a preparation method and application thereof. The copper cluster material can be prepared through a one-step reduction strategy, namely, the copper cluster material is prepared by reducing a mixture of imidazolium salt and cuprous iodide under a strong alkali condition, the copper cluster material is abbreviated as Cu2I2 (NHCPy1) 2, and the structure of the copper cluster material comprises a Cu2I2 core and two protective ligands on the periphery. The copper cluster material has green luminescence at room temperature, the quantum yield can reach 80% or above, and the copper cluster material has good thermal stability and film-forming performance. The luminescence of the copper cluster is mainly derived from electron transition from a metal core to a peripheral ligand, and the good stability of the copper cluster is derived from the strong coordination effect of carbene and the favorable accumulation mode of the cluster. The copper cluster material is used for 3D printing ink, and good green fluorescence is reserved. In short, the composite material is low in cost, easy to obtain, high in stability and good in processability, and can be used for green luminous 3D printing ink.

Description

Technical Field

[0001] The present invention belongs to the field of new materials, relates to novel functional materials, and particularly refers to a copper cluster material. Background Art

[0002] 3D printing, also known as additive manufacturing, is a digital manufacturing technology that realizes material stacking through melting, bonding, sintering, etc. under computer control to form a three-dimensional complex structure with continuous material layers. It is widely used in industries, architecture, automobiles, aerospace, biomedicine, etc., and is particularly suitable for complex tissues that require personalized customization or small-batch production. The raw materials for 3D printing are usually various thermosensitive or photosensitive resins. In order to endow the materials with novel and unique properties, additional additives (i.e., "inks") are often added to improve the physical and chemical properties of the materials.

[0003] As a newly emerging atomically precise nanomaterial, coinage metal nanoclusters have the advantages of well-defined structures and tunable properties, providing an ideal platform for studying atomic-level quantum effects and structure-activity relationships, and have shown good application prospects in the fields of catalysis, sensing, medicine, data storage, and optoelectronics. Currently, ligands such as thiols, organophosphines, alkynyl derivatives, carboxylic acid derivatives, and pyridine-containing molecules are usually used to prepare coinage metal nanoclusters. However, limited by factors such as poor stability of such clusters and uncontrollable preparation processes, the rational design and functionalization of atomically precise coinage metal nanoclusters constructed by the above ligands still have a long way to go. Among them, copper cluster materials have received increasing attention due to their low cost, diverse structures, and easy property regulation.

[0004] N-heterocyclic carbene is a neutral heterocyclic compound containing a carbene carbon atom and at least one nitrogen atom within the ring structure, and can serve as an excellent ligand that can coordinate with almost all transition metals. Compared with traditional ligands such as thiols, phosphines, pyridines, and carboxylic acids, it has excellent properties such as strong electron-donating ability and easy structure modification. The research on N-heterocyclic carbene-protected metal nanoclusters is still in its infancy, and currently only a few cases such as Au 11 , Au 13 have been reported, and the depth and breadth of its research are far behind those of traditional ligand-protected metal nanoclusters. Even so, existing research generally shows that compared with traditional ligand-protected metal nanoclusters, N-heterocyclic carbene ligands can effectively improve the stability of the clusters while maintaining good luminescence and catalytic properties of the clusters, and are a very promising peripheral protection ligand. Therefore, constructing N-heterocyclic carbene-protected metal nanocluster materials and using them in 3D printing inks has great application prospects. Summary of the Invention

[0005] To solve the above technical problems, the present invention proposes a copper cluster material, its preparation method, and application.

[0006] The technical solution of the present invention is realized as follows: A copper cluster material, using an imidazolium salt precursor NHC Py1 •HCl, and by means of an in-situ reduction strategy, synthesizes an atomically precise N-heterocyclic carbene-protected copper cluster Cu2I2(NHC Py1 )2, and this cluster exhibits good luminescence properties and stability.

[0007] The chemical formula of this copper cluster material is C 40 H 34 Cu2I2N6, the space group is P 21 / n , and the unit cell parameters are as follows: a = 10.7 Å, b =11.1 Å, c = 18.8 Å, α = 90°, β = 100.9°, γ = 90°, V = 2198 Å 3 ; the structural formula is: .

[0008] The preparation steps of the above copper cluster material are as follows: Dissolve the imidazolium salt precursor NHC Py1 •HCl in tetrahydrofuran, dissolve cuprous iodide in acetonitrile, then mix the above two, stir, add potassium tert-butoxide, continue to stir to obtain a green-emitting suspension, and centrifuge to obtain the copper cluster product Cu2I2(NHC Py1 )2.

[0009] The molar ratio of the above imidazolium salt precursor NHC Py1 •HCl, cuprous iodide and potassium tert-butoxide is 1:1:1 - 1.1.

[0010] The concentration of the tetrahydrofuran solution of the above imidazolium salt precursor NHC Py1 •HCl is 0.05 - 0.06 mmol / mL, and the concentration of the acetonitrile solution of cuprous iodide is 0.05 - 0.06 mmol / mL.

[0011] The preparation method of the above copper cluster material also includes the preparation method of single crystals of the copper cluster material.

[0012] The preparation method of single crystals of the above copper cluster material has the steps of: Dissolve the copper cluster material in dichloromethane, and then diffuse it in diethyl ether until single crystals of the copper cluster material, that is, pure Cu2I2(NHC Py1 )2, are obtained.

[0013] The copper cluster material of the present invention is used in 3D printing ink, and the steps are as follows: The copper cluster Cu2I2(NHC Py1 )2 is dissolved in N,N-dimethylformamide, and then added to the photosensitive resin. The mixture is stirred in the dark for 2-3 hours. Set the 3D printing program to print out the 3D model of the single crystal structure. This material exhibits green luminescence, and the maximum emission wavelength is located at 530 nm.

[0014] The application of the above copper cluster material in the preparation of sensors and biomedical reagents.

[0015] Advantages of the present invention: 1. The copper cluster material structure of the present application contains a Cu2I2 core and two peripheral protecting ligands. This copper cluster material has green luminescence at room temperature, and the quantum yield can reach more than 80%. It has good thermal stability and film-forming properties. The luminescence of the copper cluster mainly originates from the electronic transition from the metal core to the peripheral ligands, and its good stability stems from the strong coordination of the carbene and the favorable stacking mode of the cluster.

[0016] 2. The copper cluster material protected by N-heterocyclic carbene of the present application has good thermal stability: Under the condition of a heating rate of 10 °C / min, the thermal stability of the solid material is measured by thermogravimetric analysis under inert N2 conditions. The copper cluster Cu2I2(NHC Py1 )2 does not show decomposition before about 250 °C. A main degradation stage appears around 280-360 °C, mainly the degradation of copper and iodine elements. Subsequently, the gradual collapse region between 380-480 °C indicates the loss of N-heterocyclic carbene ligands. The differential scanning calorimetry curve shows an endothermic peak at about 300 °C, which is consistent with the thermogravimetric analysis results.

[0017] 3. The copper cluster material of the present application has good film-forming properties: The copper cluster Cu2I2(NHC Py1 )2 is made into a film with polyvinylidene fluoride (PVDF). Because PVDF has good piezoelectric, pyroelectric and ferroelectric properties, it has been widely used in the fields of sensors and biomedicine. The emission spectrum of the copper cluster film is very similar to the solid-state emission spectrum of its powder, and the quantum yield of the copper cluster film hardly decreases, reaching more than 80%. The lifetime is 9.8 μs, showing phosphorescent properties. These all indicate that Cu2I2(NHC Py1 )2 copper clusters have good processing properties without sacrificing luminescence performance. Description of the Drawings

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 For the imidazolium salt precursor NHC of the present invention Py1 •HCl structure diagram.

[0020] Figure 2 For the Cu2I2(NHC of the present invention Py1 )2 copper cluster crystal structure diagram.

[0021] Figure 3 For the Cu2I2(NHC of the present invention Py1 )2 copper cluster solid luminescence diagram.

[0022] Figure 4 For the Cu2I2(NHC of the present invention Py1 )2 copper cluster thermogravimetric analysis diagram.

[0023] Figure 5 For the Cu2I2(NHC of the present invention Py1 )2 copper cluster film-forming performance diagram.

[0024] Figure 6 For the Cu2I2(NHC of the present invention Py1 )2 copper cluster 3D printing device diagram under sunlight and ultraviolet light. Detailed implementation manners

[0025] The following will clearly and completely describe the technical solutions of the present invention in combination with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0026] The test methods used in the following experimental examples are all conventional methods unless otherwise specified; the materials, reagents, etc. used are reagents and materials that can be obtained from commercial channels unless otherwise specified.

[0027] The present invention uses the imidazolium salt precursor NHC Py1 •HCl (the structural formula is as Figure 1 shown, CAS: 1164114-85-5), and uses an in-situ reduction strategy to synthesize an atomically precise nitrogen heterocyclic carbene-protected copper cluster Cu2I2(NHC Py1 )2 (the crystal structural formula is asFigure 2 As shown in the figure, the cluster exhibits good luminescence properties and stability.

[0028] The above copper cluster material can be prepared by the following steps: Dissolve the imidazolium salt precursor NHC Py1 •HCl in tetrahydrofuran, dissolve cuprous iodide in acetonitrile, then mix the above two, stir for 10 minutes, add potassium tert-butoxide, and continue stirring for 12 hours to obtain a green-luminescent suspension. After centrifugal separation, the copper cluster product Cu2I2(NHC Py1 )2 is obtained, and its structural formula is: .

[0029] The following is a description in combination with specific examples: Example 1 The preparation steps of the copper cluster material in this example are as follows: Dissolve the imidazolium salt precursor NHC Py1 •HCl (0.1 mmol, 34 mg) in 2 mL of tetrahydrofuran, dissolve cuprous iodide (0.1 mmol, 19 mg) in 2 mL of acetonitrile, then mix the above two, stir for ten minutes, add potassium tert-butoxide (0.11 mmol, 12.34 mg), and continue stirring for 12 hours to obtain a green-luminescent suspension. After centrifugal separation, the copper cluster product is obtained.

[0030] The preparation steps of the single crystal of the above copper cluster material: Dissolve the above product in dichloromethane and diffuse it in diethyl ether. After about 3 days, a pure product Cu2I2(NHC Py1 )2 copper cluster single crystal is obtained. Its single crystal structure is shown in Figure 2 . The unit cell parameters are as follows: a = 10.7 Å, b = 11.1 Å, c = 18.8 Å, α = 90°, β = 100.9°, γ = 90°, V = 2198 Å3.

[0031] Its solid luminescence is shown in Figure 3 , and it can be seen from Figure 3 that the material has good green luminescence performance.

[0032] The thermogravimetric analysis is shown in Figure 4 , and it can be seen from Figure 4 that the copper cluster material has good thermal stability: under the condition of a heating rate of 10 °C / min, the thermal stability of the solid material is measured by thermogravimetric analysis under an inert N2 condition. The copper cluster Cu2I2(NHC Py1)2 did not show decomposition before about 250 °C. A major degradation stage occurred around 280 - 360 °C, mainly the degradation of copper and iodine elements. Subsequently, the gradual collapse region between 380 - 480 °C indicated the loss of the N-heterocyclic carbene ligand. The differential scanning calorimetry curve showed an endothermic peak at about 300 °C, which was consistent with the thermogravimetric analysis results.

[0033] The film-forming performance is shown in Figure 5 , from Figure 5 it can be seen that the copper cluster material has good film-forming performance: The copper cluster Cu2I2(NHC Py1 )2 was made into a film with polyvinylidene fluoride (PVDF). Because PVDF has good piezoelectric, pyroelectric, and ferroelectric properties, it has been widely used in fields such as sensors and biomedicine. The emission spectrum of the copper cluster film is very similar to the solid-state emission spectrum of its powder, and the quantum yield of the copper cluster film has almost no loss, reaching more than 80%. The lifetime is 9.8 μs, showing phosphorescent properties. These all indicate that Cu2I2(NHC Py1 )2 copper clusters have good processability without sacrificing luminescence performance.

[0034] Example 2 The preparation steps of the copper cluster material in this example are as follows: Dissolve the imidazole salt precursor NHC Py1 •HCl (0.1 mmol, 34 mg) in 2 mL of tetrahydrofuran, dissolve cuprous iodide (0.1 mmol, 19 mg) in 2 mL of acetonitrile, then mix the above two, stir for ten minutes, add potassium tert-butoxide (0.1 mmol, 11.22 mg), and continue to stir for 11 hours to obtain a green-luminescent suspension, and centrifuge to separate to obtain the copper cluster product.

[0035] Example 3 The preparation steps of the copper cluster material in this example are as follows: Dissolve the imidazole salt precursor NHC Py1 •HCl (0.1 mmol, 34 mg) in 2 mL of tetrahydrofuran, dissolve cuprous iodide (0.1 mmol, 19 mg) in 2 mL of acetonitrile, then mix the above two, stir for ten minutes, add potassium tert-butoxide (0.11 mmol, 12.34 mg), and continue to stir for 13 hours to obtain a green-luminescent suspension, and centrifuge to separate to obtain the copper cluster product.

[0036] Example 4 The preparation steps of the copper cluster material in this example are as follows: Dissolve the imidazole salt precursor NHC Py1• HCl (0.12 mmol, 40.8 mg) was dissolved in 2 mL of tetrahydrofuran. Copper(I) iodide (0.1 mmol, 19 mg) was dissolved in 2 mL of acetonitrile. Then the above two were mixed and stirred for ten minutes. After that, potassium tert-butoxide (0.11 mmol, 12.34 mg) was added and stirring was continued for 13 hours to obtain a green-emitting suspension. The copper cluster product was obtained by centrifugation.

[0037] Example 5 The preparation steps of the copper cluster material in this example are as follows: The imidazolium salt precursor NHC Py1 • HCl (0.1 mmol, 34 mg) was dissolved in 2 mL of tetrahydrofuran. Copper(I) iodide (0.12 mmol, 22.8 mg) was dissolved in 2 mL of acetonitrile. Then the above two were mixed and stirred for ten minutes. After that, potassium tert-butoxide (0.1 mmol, 11.22 mg) was added and stirring was continued for 12 hours to obtain a green-emitting suspension. The copper cluster product was obtained by centrifugation.

[0038] Example 6 The preparation steps of the copper cluster material in this example are as follows: The imidazolium salt precursor NHC Py1 • HCl (0.12 mmol, 40.8 mg) was dissolved in 2 mL of tetrahydrofuran. Copper(I) iodide (0.1 mmol, 19 mg) was dissolved in 2 mL of acetonitrile. Then the above two were mixed and stirred for ten minutes. After that, potassium tert-butoxide (0.1 mmol, 11.22 mg) was added and stirring was continued for 13 hours to obtain a green-emitting suspension. The copper cluster product was obtained by centrifugation.

[0039] Example 7 The preparation steps of the copper cluster material in this example are as follows: The imidazolium salt precursor NHC Py1 • HCl (0.1 mmol, 34 mg) was dissolved in 2 mL of tetrahydrofuran. Copper(I) iodide (0.12 mmol, 22.8 mg) was dissolved in 2 mL of acetonitrile. Then the above two were mixed and stirred for ten minutes. After that, potassium tert-butoxide (0.11 mmol, 12.34 mg) was added and stirring was continued for 14 hours to obtain a green-emitting suspension. The copper cluster product was obtained by centrifugation.

[0040] Application Example Prepare 3D printing ink using the copper cluster material prepared in Example 1: 100 mg of copper clusters are dissolved in 1 mL of N,N-dimethylformamide, and then added to 200 mL of photosensitive resin (ELEGOO rigid photosensitive resin, Shenzhen Smart Technology Co., Ltd.). The mixture is stirred in the dark for 2 hours. Set the 3D printing program and print out the 3D model with a single crystal structure. After multiple experimental verifications, 3D printing ink can be prepared when the concentration of the copper cluster material is 0.1 - 0.2 g / mL.

[0041] The 3D printing device with its green light-emitting property is shown in Figure 6 , from Figure 6 it can be seen that this material has good 3D printing performance.

[0042] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A copper cluster material having the chemical formula C 40 H 34 Cu2I2N6, space group is P twenty one / n , the unit cell parameters are as follows: a = 10.7Å, b = 11.1 Å, c = 18.8 Å, α = 90°, β = 100.9°, γ = 90°, V = 2198 Å 3 ; The structural formula is: 。 2. The preparation method of the copper cluster material according to claim 1, characterized in that, The steps are as follows: A tetrahydrofuran solution of imidazolium salt precursor NHC Py1 •HCl is stirred and mixed with an acetonitrile solution of cuprous iodide, then potassium tert-butoxide is added, and stirring is continued until a green-emitting suspension is obtained. The copper cluster material, namely Cu2I2(NHC Py1 )2, is obtained by centrifugal separation.

3. The preparation method of the copper cluster material according to claim 2, characterized in that: The imidazolium salt precursor NHC Py1 • The molar ratio of HCl, copper(I) iodide, and potassium tert-butoxide is 1:1:1 - 1.

1.

4. The preparation method of the copper cluster material according to claim 3, wherein: The imidazolium salt precursor NHC Py1 • The concentration of the HCl solution in tetrahydrofuran is 0.05 - 0.06 mol / mL, and the concentration of the cuprous iodide solution in acetonitrile is 0.05 - 0.06 mmol / mL.

5. The preparation method of the copper cluster material according to any one of claims 2-4, characterized in that: It also includes a preparation method of single crystal of copper cluster material.

6. The preparation method of the copper cluster material according to claim 5, characterized in that, The preparation method of the single crystal of the copper cluster material comprises the following steps: dissolving the copper cluster material in dichloromethane, and then diffusing it in diethyl ether until a single crystal of the copper cluster material, that is, pure Cu2I2(NHC Py1 )2, is obtained.

7. A 3D printing green-emitting ink, characterized in that: It includes the copper cluster material of Claim 1.

8. The preparation method of the 3D printing green luminescent ink according to claim 7, characterized in that: Dissolve the copper cluster material in an organic solvent to obtain a mixed solution, and then add a photosensitive resin and stir in the dark to obtain a 3D printing green-emitting ink.

9. The preparation method of the 3D printing green luminescent ink according to claim 8, wherein: The concentration of the copper cluster material in the mixed solution is 0.1 - 0.2 g / mL; the volume ratio of the mixed solution to the photosensitive resin is 1:200 - 300.

10. Application of the copper cluster material according to Claim 1 in the preparation of sensors and biomedical reagents.

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