Gold-copper nanoclusters and preparation method and optical device thereof

Abstract

The present application belongs to the field of nanomaterials, and particularly relates to a gold-copper nanocluster, a preparation method thereof and an optical device. n Cu 22‑n Y 18 wherein Y represents a dehydrogenated alkyne ligand, and 16<=n<=21. Thus, the gold-copper nanocluster has excellent quantum yield and optical properties.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials, specifically to gold-copper nanoclusters, their preparation methods, and optical devices. Background Technology

[0002] Near-infrared luminescent materials have attracted widespread attention due to their potential applications in deep tissue bioimaging and optical devices. Colloidal quantum dots and organic fluorescent dyes are two of the most studied near-infrared luminescent materials, but these two materials suffer from problems such as high toxicity, complex post-modification processes, small Stokes shift, short lifetime, and poor photostability.

[0003] In recent years, metal nanoclusters have emerged as a new type of near-infrared emitting material. Metal nanoclusters have advantages such as well-defined structure, low toxicity, large Stokes shift, and excellent photostability and luminescence lifetime. However, the photoluminescence quantum yield (PLQY) of existing metal nanoclusters is generally low, which makes it difficult to meet the requirements for large-scale promotion and use of metal nanoclusters. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] In a first aspect, the present invention provides a gold-copper nanocluster, wherein the molecular formula of the gold-copper nanocluster is Au. n Cu 22-n Y 18 Where Y represents a dehydrogenated alkyne ligand, and 16 ≤ n ≤ 21. Thus, gold-copper nanoclusters exhibit excellent quantum yield and optical properties.

[0006] According to some embodiments of the present invention, the alkyne ligand includes at least one alkyne compound with the general formula ZC≡CH, wherein Z is a substituent. Thus, the dehydroalkyne ligand possesses significant steric hindrance and strong electron-donating ability, which can protect the gold-copper core, reduce the sensitivity of the gold-copper nanoclusters to air and solvents, and further improve the stability of the gold-copper nanoclusters.

[0007] According to some embodiments of the present invention, Z is a substituted or unsubstituted phenyl group, and the substituent of the phenyl group includes at least one selected from methyl, dimethyl, and tert-butyl. This further optimizes the steric hindrance of the dehydroacetylene ligand, improves its electron-donating ability, protects the gold-copper core, reduces the sensitivity of the gold-copper nanoclusters to air and solvents, and further improves the stability of the gold-copper nanoclusters.

[0008] According to some embodiments of the present invention, 16 ≤ n ≤ 19. Therefore, by controlling the proportion of copper atoms in the gold-copper nanoclusters, the number of Au-Cu bonds can be increased, thereby improving the stability of the gold-copper nanoclusters.

[0009] According to some embodiments of the present invention, the core of the gold-copper nanoclusters is [Au7] containing four free electrons. 4+ The [Au7] 4+ It consists of two tetrahedrons [Au4]. 2+ Formed by Au atoms connected at the vertices; a total of 6 Au atoms and / or Cu atoms are located in 2 of the aforementioned tetrahedra [Au4]. 2+ On the plane of symmetry, and with the tetrahedron [Au4] 2+ The Au atoms at the vertices are connected to form a hexagonal structure; each of the three meta Au atoms in the hexagonal structure has a total of 3 Au atoms and / or Cu atoms on one side; the dehydrogenated alkyne ligands are respectively connected to the tetrahedron [Au4]. 2+ The Au atoms and / or Cu atoms outside the Au atoms at the vertices are connected by σ bonds or π bonds. This makes the gold-copper nanoclusters compact and further improves their high stability.

[0010] In a second aspect, the present invention provides a method for preparing the aforementioned gold-copper nanoclusters, comprising: (1) mixing and reacting a first solvent with a gold precursor, an alkyne ligand, and an alkaline substance to obtain a first solution; (2) mixing and reacting the first solution, a copper salt solution, and a reducing agent, and drying the mixture to obtain a first mixture; and (3) crystallizing the first mixture to obtain gold-copper nanoclusters. Thus, the preparation method is simple and easy to implement, suitable for large-scale production, and has a high yield of gold-copper nanoclusters.

[0011] According to some embodiments of the present invention, the gold precursor comprises Me2SAuCl. This facilitates a coordination reaction between the gold precursor and the dehydrogenated alkyne ligand.

[0012] According to some embodiments of the present invention, the copper salt solution includes at least one selected from Cu(MeCN)4BF4, Cu(NO3)2, C4O4F6Cu, Cu(CF3SO3)2, and Cu(CH3COO)2. Therefore, the copper salt solution exhibits relatively stable properties, which is beneficial for improving the concentration of Au and Cu. + The reaction rate with the dehydroacetylene ligand.

[0013] According to some embodiments of the present invention, the reducing agent includes BH3· tAt least one of BuNH2, NaBH4, PhSiH2, and BH3·NEt3. Therefore, the reducing agent is beneficial for removing Au from the first solution. + Reduction to Au and suppression of Cu + Oxidation occurs.

[0014] According to some embodiments of the present invention, the first solvent includes at least one of toluene and chloroform. This facilitates better dissolution of the gold precursor, the alkyne ligand, and the basic substance.

[0015] According to some embodiments of the present invention, the molar ratio of the gold precursor to the alkyne ligand is 1:(0.5-2). This facilitates better coordination reactions between the dehydrogenated alkyne ligand and the gold precursor, reducing waste of either the gold precursor or the alkyne ligand.

[0016] According to some embodiments of the present invention, the molar ratio of the first solution, the copper salt solution, and the reducing agent is 1:(0.1-2):(0.01-1). This is beneficial for increasing the reaction rate and reducing the waste of the first solution, the copper salt solution, and the reducing agent.

[0017] According to some embodiments of the present invention, the crystallization process includes: adding the first mixture to a first organic solvent to obtain a second solution; and adding the second solution to a second organic solvent for crystallization treatment to obtain the gold-copper nanoclusters. This is beneficial for improving the crystallization quality of the gold-copper nanoclusters.

[0018] According to some embodiments of the present invention, the first organic solvent comprises a mixed solvent of dichloromethane and toluene. Therefore, the first organic solvent facilitates the orderly arrangement of the internal lattice of the gold-copper nanoclusters, thereby improving the crystallinity of the gold-copper nanoclusters.

[0019] According to some embodiments of the present invention, the second organic solvent includes at least one selected from acetonitrile, methanol, ethanol, n-hexane, n-pentane, n-heptane, and diethyl ether. This is beneficial for improving the crystallinity of gold-copper nanoclusters.

[0020] In a third aspect, the present invention provides an optical device comprising the aforementioned gold-copper nanoclusters, or gold-copper nanoclusters prepared by the aforementioned method. Thus, the optical device possesses all the features and advantages of the aforementioned gold-copper nanoclusters, which will not be elaborated further here.

[0021] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0022] Figure 1This is a molecular structure diagram of gold-copper nanoclusters obtained by X-ray single-crystal diffraction according to an embodiment of the present invention;

[0023] Figure 2 This is a molecular structure diagram of a gold-copper core according to an embodiment of the present invention;

[0024] Figure 3 This is a flowchart of a method for preparing gold-copper nanoclusters according to some embodiments of the present invention;

[0025] Figure 4 ESI-TOF image of the gold-copper nanoclusters prepared in Example 1 in positive ion mode;

[0026] Figure 5 The quantum yield diagram of the gold-copper nanoclusters prepared in Example 1 dissolved in dichloromethane in an air atmosphere;

[0027] Figure 6 The quantum yield diagram of the gold-copper nanoclusters prepared in Example 1 dissolved in dichloromethane under a nitrogen atmosphere;

[0028] Figure 7 Quantum yield diagram of the gold-copper nanoclusters prepared in Example 1 dissolved in dichloromethane under an oxygen atmosphere;

[0029] Figure 8 The ultraviolet-visible absorption spectrum of the gold-copper nanoclusters prepared in Example 1 dissolved in dichloromethane;

[0030] Figure 9 The excitation and emission spectra of the gold-copper nanoclusters prepared in Example 1 dissolved in dichloromethane are shown.

[0031] Figure 10 This is a schematic diagram of the emission lifetime of the gold-copper nanoclusters prepared in Example 1 dissolved in dichloromethane.

[0032] Figure 11 The ultraviolet absorption spectra of the gold-copper nanoclusters prepared in Example 1 after irradiation for different days are shown. Detailed Implementation

[0033] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0034] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0035] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are open-ended expressions, meaning they include what is specified in this application but do not exclude other aspects.

[0036] In a first aspect, the present invention provides a gold-copper nanocluster, the molecular formula of which is Au. n Cu 22-n Y 18 Where Y represents a dehydrogenated alkyne ligand, and 16 ≤ n ≤ 21. Thus, gold-copper nanoclusters exhibit excellent quantum yield and optical properties.

[0037] In this invention, "acetylene ligand" refers to the acetylene compound itself that can act as a gold-copper ligand, while "dehydrogenated acetylene ligand" refers to an acetylene compound that has lost one hydrogen atom.

[0038] The following explains how the gold-copper nanoclusters in this application can achieve the above-mentioned technical effects:

[0039] Introducing Cu atoms into Au compounds results in a compact structure of gold-copper nanoclusters due to the shorter Au-Cu bond length compared to Au-Au bonds. This leads to high stability and reduced non-radiative transitions caused by vibrations within the gold-copper nanoclusters, resulting in excellent quantum yield and optical properties. The dehydroacetylene ligand, with its significant steric hindrance and strong electron-donating ability, protects the gold-copper core, reducing the nanoclusters' sensitivity to air and solvents and further enhancing their stability. Consequently, the gold-copper nanoclusters exhibit excellent quantum yields in air, nitrogen, and oxygen atmospheres. Furthermore, these nanoclusters possess a large Stokes shift, a long emission lifetime, a large extinction coefficient, and superior optical stability.

[0040] In some embodiments, the alkyne ligand comprises at least one alkyne compound of the general formula ZC≡CH, wherein Z is a substituted or unsubstituted phenyl group, and the substituent of the phenyl group comprises at least one of methyl, dimethyl, and tert-butyl groups. It should be understood that when Z has a substituent, the number of substituents can be one or more, and when the number of substituents is multiple, the substituents can be the same or different. Specific examples of alkyne compounds include, but are not limited to,t BuPhC≡CH, phenylacetylene, methylphenylacetylene, dimethylphenylacetylene, etc.

[0041] Optionally, alkyne compounds are t BuPhC≡CH, thus ensuring that the alkyne compound has greater steric hindrance and stronger electron-donating ability, can protect the gold-copper core, reduce the sensitivity of the gold-copper nanoclusters to air and solvents, and further improve the stability of the gold-copper nanoclusters.

[0042] In some embodiments, 16 ≤ n ≤ 19. For example, 16, 16.5, 17, 17.5, 18, 18.5, 19, etc. By controlling the proportion of copper atoms in the gold-copper nanoclusters, the number of Au-Cu bonds can be increased, which is beneficial to improving the stability of the gold-copper nanoclusters.

[0043] In some embodiments, reference Figure 2 The core of the gold-copper nanoclusters is [Au7] containing four free electrons. 4+ [Au7] 4+ It consists of two tetrahedrons [Au4]. 2+ Formed by Au atoms connected at the vertices; a total of 6 Au atoms and / or Cu atoms are located in 2 tetrahedra [Au4]. 2+ On the plane of symmetry, and with the tetrahedron [Au4] 2+ The Au atoms at the vertices are connected to form a hexagonal structure; each of the three meta Au atoms in the hexagonal structure has a total of 3 Au atoms and / or Cu atoms on one side, and the dehydrogenated alkyne ligands are connected to each other except for the tetrahedral [Au4]. 2+ The Au atoms and / or Cu atoms, excluding the Au atom at the vertex, are connected by either σ-bonds or π-bonds. As an example, refer to... Figure 1 When the molecular formula of gold-copper nanoclusters is Au 16 Cu6( t BuPhC≡C) 18 At this time, the compact structure of gold-copper nanoclusters further enhances their high stability.

[0044] In a second aspect, the present invention provides a method for preparing gold-copper nanoclusters, referring to... Figure 3 The method includes the following steps:

[0045] S1: The first solvent is mixed with the gold precursor, the acetylene ligand, and the basic substance to react and obtain the first solution.

[0046] According to some embodiments of the present invention, in this step, an alkaline substance promotes the dehydrogenation of hydrogen from the alkynyl ligand to obtain a dehydrogenated alkynyl ligand, which then undergoes a coordination reaction with the gold precursor to obtain a first solution.

[0047] In some embodiments, the temperature of the mixed reaction is 10°C-35°C, and the reaction time is 0.1 min-30 min. This facilitates better coordination reactions between the dehydrogenated alkyne ligand and the gold precursor.

[0048] In some embodiments, the molar ratio of the gold precursor to the acetylene ligand is 1:(0.5-2).

[0049] As a specific example, the molar ratio of gold precursor to acetylene ligand can be 1:0.5, 1:1, 1:1.5, or 1:2, etc.

[0050] Controlling the molar ratio of gold precursor and alkynyl ligand within the above range is beneficial for the dehydrogenated alkynyl ligand and gold precursor to undergo better coordination reaction, thereby reducing the waste of gold precursor or alkynyl ligand.

[0051] In some embodiments, the amount of alkaline substance used is 0.5-2 mol relative to 1 mol of alkyne ligand, for example 0.5 mol, 0.7 mol, 0.8 mol, 0.9 mol, 1 mol, 1.5 mol, 2 mol, etc.

[0052] It is understandable that, since the first solvent does not participate in the reaction, those skilled in the art can choose the amount of the first solvent according to actual needs, which will not be elaborated here.

[0053] In this invention, Me represents methyl.

[0054] In some embodiments, the gold precursor comprises Me2SAuCl, which facilitates coordination reactions between the gold precursor and the dehydrogenated alkyne ligand.

[0055] In some embodiments, the alkaline substance includes at least one selected from Et3N, NaOH, trimethylamine, diethylamine, sodium methoxide, and pyridine. Thus, the aforementioned alkaline substance can promote the dehydrogenation of hydrogen from the alkyne ligand, thereby enabling the dehydrogenated alkyne ligand and the gold precursor to undergo a better coordination reaction.

[0056] In some embodiments, the first solvent includes at least one of chloroform and toluene.

[0057] S2: Mix the first solution, copper salt solution, and reducing agent, react them, and dry to obtain the first mixture.

[0058] According to some embodiments of the present invention, in this step, by adding a reducing agent, it is beneficial to remove Au from the first solution. +Reduction to Au can suppress Cu. + Oxidation can also cause Cu to... 2+ Reduced to Cu + Au, Cu + It reacts with a dehydroacetylene ligand, and after drying, yields the first mixture. It should be noted that the reducing power of the above reducing agent is greater than that of Au. + and Cu 2+ Its reducing power is less than that of Cu + The reducibility.

[0059] In some embodiments, the molar ratio of the first solution, the copper salt solution, and the reducing agent is 1:(0.1-2):(0.01-1). Therefore, by controlling the molar ratio of the first solution, the copper salt solution, and the reducing agent, it is beneficial to increase the reaction rate and reduce the waste of the first solution, the copper salt solution, and the reducing agent.

[0060] In some embodiments, the reaction temperature for the mixed reaction is 10°C-35°C, and the reaction time is 1-48 hours. This is beneficial for Au and Cu. + It reacts better with dehydroacetylenic ligands.

[0061] In some embodiments, the copper salt solution includes at least one of Cu(MeCN)4BF4, Cu(NO3)2, C4O4F6Cu, Cu(CF3SO3)2, and Cu(CH3COO)2.

[0062] Optionally, the copper salt solution is Cu(MeCN)₄BF₄. Cu(MeCN)₄BF₄ is relatively stable, and the Cu in this copper salt solution... + It can directly participate in the reaction, which helps to increase the reaction rate.

[0063] In some embodiments, the reducing agent includes BH3· t At least one of BuNH2, NaBH4, PhSiH2, and BH3·NEt3. Therefore, during the mixed reaction, the reducing agent can undergo oxidation, releasing electrons, which facilitates the removal of Au from the first solution. + Reduction to Au and suppression of Cu + Oxidation occurs.

[0064] Optionally, the reducing agent is BH3· t BuNH2, BH3· t BuNH2 has a moderate reducing power, which is beneficial for the reaction to proceed.

[0065] In some embodiments, the drying process may employ rotary evaporation of the solution to remove the solvent, thereby obtaining a first mixture.

[0066] S3: Crystallize the first mixture to obtain gold-copper nanoclusters.

[0067] According to some embodiments of the present invention, in this step, the first mixture is subjected to crystallization treatment to obtain high-purity gold-copper nanoclusters.

[0068] In some embodiments, the crystallization process includes: adding a first mixture to a first organic solvent to obtain a second solution; and adding the second solution to a second organic solvent for crystallization to obtain gold-copper nanoclusters. Thus, adding the first mixture to the first organic solvent is beneficial for removing impurities from the first mixture and for dissolving the first mixture, thereby achieving the crystallization process of the gold-copper nanoclusters.

[0069] In some embodiments, the molar ratio of the first organic solvent and the second organic solvent is 1:(1-10). This allows the second organic solvent to diffuse more effectively, thereby improving the crystallinity of the gold-copper nanoclusters.

[0070] In some embodiments, the first organic solvent includes a mixture of dichloromethane and toluene, wherein the mixing ratio of dichloromethane and toluene is not specifically limited and can be selected by those skilled in the art according to the actual situation.

[0071] In some embodiments, the second organic solvent includes at least one selected from acetonitrile, methanol, ethanol, n-hexane, n-pentane, n-heptane, and diethyl ether. In some embodiments, the second organic solvent is acetonitrile.

[0072] In some embodiments, the crystallization process includes: firstly, dissolving the first mixture in a mixed solvent of dichloromethane and toluene, centrifuging to obtain a second solution. Thus, selecting a mixed solvent of dichloromethane and toluene as the first organic solvent is beneficial for achieving the ordered arrangement of the internal lattice of the gold-copper nanoclusters and improving the crystallization quality of the gold-copper nanoclusters. Subsequently, the second solution is added to acetonitrile for diffusion to obtain gold-copper nanoclusters. Thus, the second solution is dissolved in acetonitrile solvent, and the acetonitrile solvent slowly diffuses into the gold-copper nanoclusters, gradually completing the crystallization process of the gold-copper nanoclusters.

[0073] In some embodiments, the crystallization treatment time is 1 day to 28 days. Therefore, by controlling the crystallization treatment time within the above range, the crystallization effect of the crystallization treatment can be improved.

[0074] In some embodiments, the gold-copper nanoclusters described above can be used in the fields of deep tissue bioimaging and optical devices.

[0075] In a third aspect, the present invention provides an optical device comprising the aforementioned gold-copper nanoclusters, or gold-copper nanoclusters prepared by the aforementioned method. Thus, the optical device possesses all the features and advantages of the aforementioned gold-copper nanoclusters, which will not be elaborated further here.

[0076] The following are specific examples. Unless otherwise specified, all reagents used in the following examples are commercially available or can be synthesized by known methods, and reaction conditions not listed are readily available to those skilled in the art.

[0077] Example 1

[0078] The specific steps for preparing gold-copper nanoclusters include:

[0079] (1) Under stirring conditions, 0.1 mmol of Me2SAuCl and 0.1 mmol of 4- t BuPhC≡CH and 0.3 mmol of Et3N were added to 5 ml of toluene to react and obtain the first solution; the reaction temperature was 25 °C and the reaction time was 5 minutes.

[0080] (2) Under stirring conditions, 0.1 mmol of the first solution, 0.04 mmol of Cu(MeCN)4BF4, and 0.02 mmol of BH3· t BuNH2 was subjected to a mixed reaction. After the reaction was completed, the solvent was removed by rotary evaporation to obtain the first mixture. The reaction temperature was 25°C and the reaction time was 4 hours.

[0081] (3) Dissolve the first mixture in a mixed solvent of dichloromethane and toluene, and centrifuge to obtain a second solution; wherein the volume of the mixed solvent is 2 mL, and the molar ratio of dichloromethane to toluene is 1:1;

[0082] (4) The second solution was added to 4 mL of acetonitrile solvent and diffused for 14 days to obtain gold-copper nanoclusters.

[0083] The gold-copper nanoclusters obtained above were analyzed, with reference to... Figure 4 The molecular formula of the cluster is Au. 16 Cu6( t BuPhC≡C) 18 .

[0084] The quantum yield of gold-copper nanoclusters in air, nitrogen, and oxygen atmospheres was measured using an integrating sphere, with reference to... Figures 5-7The quantum yield of gold-copper nanoclusters in air atmosphere is 95.6%, the quantum yield of gold-copper nanoclusters in nitrogen atmosphere is greater than 99%, and the quantum yield of gold-copper nanoclusters in oxygen atmosphere is 61.1%. The gold-copper nanoclusters prepared in Example 1 have excellent quantum yield.

[0085] The gold-copper nanoclusters obtained above were dissolved in dichloromethane, as referenced. Figure 8 The absorbance coefficient ε = A / L·c, where A = 0.165, the cuvette width L = 1 cm, and the concentration of the gold-copper nanoclusters dissolved in dichloromethane solution c = 1.8 mg / 180 ml, yields ε = 5 × 10⁻⁶. 4 cm -1 It can be seen that the extinction coefficient of gold-copper nanoclusters is >10. 4 cm -1 ;refer to Figure 9 It can be seen that the emission peak at ~725nm is located in the near-infrared region and has a large Stokes shift (~120nm); Reference Figure 10 It can be seen that the gold-copper nanoclusters have a relatively long lifetime, approximately 1.64 microseconds; the gold-copper nanoclusters were irradiated with an ultraviolet lamp (365nm) and referenced... Figure 11 After irradiation for ten days, the gold-copper nanoclusters did not transform into other substances, proving that the gold-copper nanoclusters have excellent stability.

[0086] Example 2

[0087] The specific steps for preparing gold-copper nanoclusters include:

[0088] (1) Under stirring conditions, 0.1 mmol of Me2SAuCl and 0.1 mmol of 4- t BuPhC≡CH, 0.15 mmol of pyridine was added to 5 ml of toluene to react and obtain the first solution; wherein the reaction temperature was 10 °C and the reaction time was 30 minutes;

[0089] (2) Under stirring conditions, 0.1 mmol of the first solution, 0.1 mmol of Cu(CF3SO3)2 and 0.1 mmol of BH3·NEt3 were mixed and reacted. After the reaction was completed, the solvent was removed by rotary evaporation to obtain the first mixture. The reaction temperature was 20℃ and the reaction time was 20 hours.

[0090] (3) Dissolve the first mixture in a mixed solvent of dichloromethane and toluene, and centrifuge to obtain a second solution; wherein the volume of the mixed solvent is 2 mL, and the molar ratio of dichloromethane to toluene is 2:1;

[0091] (4) The second solution was added to 8 mL of acetonitrile solvent and diffused for 7 days to obtain gold-copper nanoclusters.

[0092] Example 3

[0093] The specific steps for preparing gold-copper nanoclusters include:

[0094] (1) Under stirring conditions, 0.1 mmol of Me2SAuCl and 0.1 mmol of 4- t BuPhC≡CH and 0.1 mmol of Et3N were added to 5 ml of toluene to react and obtain the first solution; the reaction temperature was 35 °C and the reaction time was 3 minutes.

[0095] (2) Under stirring conditions, 0.1 mmol of the first solution, 0.1 mmol of Cu(MeCN)4BF4, and 0.1 mmol of BH3· t BuNH2 was subjected to a mixed reaction. After the reaction was completed, the solvent was removed by rotary evaporation to obtain the first mixture. The reaction temperature was 25°C and the reaction time was 4 hours.

[0096] (3) Dissolve the first mixture in a mixed solvent of dichloromethane and toluene, and centrifuge to obtain a second solution; wherein the volume of the mixed solvent is 2 mL, and the molar ratio of dichloromethane to toluene is 1:1;

[0097] (4) The second solution was added to 10 mL of acetonitrile solvent and diffused for 20 days to obtain gold-copper nanoclusters.

[0098] Example 4

[0099] The specific steps for preparing gold-copper nanoclusters include:

[0100] (1) Under stirring conditions, 0.1 mmol of Me2SAuCl, 0.1 mmol of phenylacetylene, and 0.2 mmol of trimethylamine were added to 5 ml of chloroform to react and obtain the first solution; wherein the reaction temperature was 35 °C and the reaction time was 3 minutes.

[0101] (2) Under stirring conditions, 0.1 mmol of the first solution, 0.1 mmol of Cu(CH3COO)2 and 0.1 mmol of NaBH4 were mixed and reacted. After the reaction was completed, the solvent was removed by rotary evaporation to obtain the first mixture. The reaction temperature was 35℃ and the reaction time was 2 hours.

[0102] (3) Dissolve the first mixture in a mixed solvent of dichloromethane and toluene, and centrifuge to obtain a second solution; wherein the volume of the mixed solvent is 2 mL, and the molar ratio of dichloromethane to toluene is 1:1;

[0103] (4) The second solution was added to 10 mL of acetonitrile solvent and diffused for 14 days to obtain gold-copper nanoclusters.

[0104] Tests on the gold-copper nanoclusters prepared in Examples 2-4 revealed that the gold-copper nanoclusters exhibited excellent quantum yields in air, nitrogen, and oxygen atmospheres. Furthermore, the nanoclusters also possessed large Stokes shifts, long emission lifetimes, large extinction coefficients, and excellent optical stability.

[0105] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A gold-copper nanocluster, characterized in that, The molecular formula of the gold copper nanocluster is Au n Cu 22-n Y 18 wherein Y represents a dehydrogenated alkyne ligand, 16≤n≤21.

2. The gold-copper nanocluster of claim 1, wherein, The alkyne ligand includes at least one of alkyne compounds with a general formula of Z-C≡CH, wherein Z is a substituent; The Z is a substituted or unsubstituted phenyl, and the substituent of the phenyl includes at least one of methyl, dimethyl and tert-butyl.

3. The gold-copper nanocluster of claim 1, wherein, 16≤n≤19。 4. The gold-copper nanocluster according to any one of claims 1-3, wherein, The core of the gold-copper nanoclusters is [Au7] containing four free electrons. 4+ The [Au7] 4+ It consists of two tetrahedrons [Au4]. 2+ Formed by Au atoms connected at the vertices; a total of 6 Au atoms and / or Cu atoms are located in 2 of the aforementioned tetrahedra [Au4]. 2+ On the plane of symmetry, and with the tetrahedron [Au4] 2+ The Au atoms at the vertices are connected to form a hexagonal structure; each of the three meta Au atoms in the hexagonal structure has a total of 3 Au atoms and / or Cu atoms on one side; the dehydrogenated alkyne ligands are respectively connected to the tetrahedron [Au4]. 2+ The Au atoms and / or Cu atoms located outside the Au atom at the vertex are connected by σ bonds or π bonds.

5. A method of preparing the gold-copper nanocluster of any one of claims 1-4, characterized in that, The method comprises: (1) mixing a first solvent, a gold precursor, an alkyne ligand and a basic substance to obtain a first solution; the gold precursor includes Me2SAuCl; (2) mixing the first solution, a copper salt solution and a reducing agent to obtain a first mixture after drying; (3) performing a crystallization treatment on the first mixture to obtain the gold copper nanocluster.

6. The method of claim 5, wherein, The copper salt solution includes at least one of Cu(MeCN)4BF4, Cu(NO3)2, C4O4F6Cu, Cu(CF3SO3)2 and Cu(CH3COO)2; and / or the reducing agent comprises BH3· t at least one of BuNH2, NaBH4, PhSiH2, BH3·NEt3. And / or, the first solvent includes at least one of toluene and chloroform.

7. The method according to claim 5 or 6, characterized in that, The feeding molar ratio of the gold precursor and the alkyne ligand is 1:(0.5-2); And / or, the feeding molar ratio of the first solution, the copper salt solution and the reducing agent is 1:(0.1-2):(0.01-1).

8. The method of claim 5, wherein, The crystallization treatment comprises: adding the first mixture into a first organic solvent to obtain a second solution; adding the second solution into a second organic solvent to perform a crystallization treatment to obtain the gold copper nanocluster.

9. The method of claim 8, wherein, The first organic solvent includes a mixed solvent of dichloromethane and toluene; And / or, the second organic solvent includes at least one of acetonitrile, methanol, ethanol, n-hexane, n-pentane, n-heptane and diethyl ether.

10. An optical device, characterized by The gold copper nanocluster of any one of claims 1-4, or the gold copper nanocluster prepared by the method of any one of claims 5-9.

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