A multi-core copper nanocluster fluorescent material and a preparation method thereof

Abstract

A preparation method of a multi-core copper nanocluster fluorescent material, comprising the following steps: dissolving Cu(ClO4)2, an alkynyl ligand 1,2-diethynylbenzene and triethylamine in a first solvent, stirring and reacting to obtain a first solution, forming Cu2(C≡C)2Ph; adding a bisphosphine ligand L to the first solution to obtain a second solution; the bisphosphine ligand L is one of 1,4-bis(diphenylphosphino)butane, 1,5-bis(diphenylphosphino)pentane, 1,6-bis(diphenylphosphino)hexane; adding a compound containing a negative-valence hydrogen to the second solution to obtain a third solution containing multi-core copper nanoclusters, and drying to obtain a solid multi-core copper nanocluster crystal, which is the multi-core copper nanocluster fluorescent material. The preparation method is simple, the raw materials are easy to obtain, the synthesis steps are few, the synthesis conditions are mild, the yield is relatively high, and it is suitable for large-scale production; the fluorescent material prepared by this method can be stably stored in air and emit bright yellow light at room temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of metal cluster fluorescent materials, and particularly relates to a multi-core copper nanocluster fluorescent material and a preparation method thereof. Background Art

[0002] Multi-core copper nanoclusters usually have excellent solid and liquid fluorescence properties and have broad application prospects. However, the copper in the luminescent copper nanoclusters is in a low valence state, and the low-valence copper is relatively active and has a relatively low redox potential, so it is less stable; at the same time, the currently synthesized multi-core copper clusters have problems such as low fluorescence quantum yield, short lifetime, complex synthesis, and unclear structural composition. Therefore, it is very necessary to develop a preparation method for multi-core copper clusters with clear structural composition, simple synthesis, good stability, and high fluorescence intensity. Summary of the Invention

[0003] The object of the present invention is to provide a multi-core copper nanocluster fluorescent material and a preparation method thereof. The preparation method is simple, the raw materials are easy to obtain, the synthesis steps are few, the synthesis conditions are mild, the yield is relatively high, and it is suitable for large-scale production; the multi-core copper nanocluster fluorescent material prepared by this method can be stably stored in air and can emit bright yellow light at room temperature.

[0004] To achieve the above object, the present invention provides a preparation method for a multi-core copper nanocluster fluorescent material, including the following steps:

[0005] (1) Dissolve Cu(ClO4)2, the alkyne ligand 1,2-diethynylbenzene, and triethylamine in a first solvent, stir and react to obtain a first solution, and form Cu2(C≡C)2Ph;

[0006] (2) Add the bisphosphine ligand L to the first solution prepared in step (1) to obtain a second solution; the bisphosphine ligand L is one of 1,4-bis(diphenylphosphino)butane, 1,5-bis(diphenylphosphino)pentane, and 1,6-bis(diphenylphosphino)hexane;

[0007] (3) Add a compound containing negative-valent hydrogen to the second solution prepared in step (2) to obtain a third solution containing multi-core copper nanoclusters, and after drying, obtain a solid multi-core copper nanocluster crystal, which is the multi-core copper nanocluster fluorescent material.

[0008] Preferably, in step (1), the molar ratio between Cu(ClO4)2 and the alkyne ligand 1,2-diethynylbenzene is 1:8; the molar ratio between the alkyne ligand 1,2-diethynylbenzene and triethylamine is 1:2.2.

[0009] Preferably, in step (2), the molar ratio between Cu(ClO4)2 and the bisphosphine ligand L is 1 to (0.2:5).

[0010] Preferably, in step (3), the compound containing hydrogen in a negative valence state is NaBH4, and the molar ratio between Cu2(C≡C)2Ph and NaBH4 is (1 / 25 - 1 / 2):1.

[0011] Preferably, in step (3), recrystallization of the solid multi-core copper cluster crystal is further included; the time from adding the compound containing hydrogen in a negative valence state to the second solution to drying the third solution is controlled to be 2 - 12 h.

[0012] Preferably, in step (1), the first solvent is at least one of methanol, dichloromethane, chloroform, and tetrahydrofuran.

[0013] Preferably, in step (3), it includes dissolving the compound containing hydrogen in a negative valence state in a second solvent to obtain a fourth solution, and adding the fourth solution to the second solution to obtain a third solution containing multi-core copper nanoclusters.

[0014] Preferably, in step (3), the second solvent is ethanol.

[0015] Preferably, all steps are carried out at a temperature of 15°C - 40°C and in air.

[0016] The present invention also provides a multi-core copper nanocluster fluorescent material prepared by the preparation method of the above multi-core copper nanocluster fluorescent material. The molecular formula of the multi-core copper nanocluster fluorescent material is [Cu 13 (L)4(C≡CPhC≡C)6](ClO4), wherein thirteen copper atoms form a square four-leaf clover-like structure, four diphosphine ligands coordinate with the copper atoms on the square edges to form four sides, and six alkynyl ligands coordinate with the copper atoms on the edges and faces to form a flat cluster as a whole.

[0017] Compared with the prior art solutions, the present invention can be carried out under normal temperature, normal pressure and air conditions, preferably at a temperature of 15°C - 40°C, and does not require strict inert atmosphere reaction conditions, and the preparation conditions are mild; in addition, the method of the present invention also has the advantages of simplicity and high efficiency. When all reactants are dissolved and completely mixed, the multi-core copper nanoclusters can be obtained, and the operation process is very simple, providing the possibility for large-scale production of the multi-core copper nanoclusters. The synthesis method provided by the preparation method of the present invention is simple, the raw materials are easy to obtain, the synthesis steps are few, the synthesis conditions are mild, the yield is relatively high, and it has the potential for industrial application; the prepared fluorescent copper nanoclusters not only have good stability, but also have a very small particle size, and the size of the obtained multi-core copper nanoclusters can be less than 5 nm; in addition, the fluorescent copper nanoclusters emit bright yellow light at room temperature, and the emission wavelength is 590 nm. Description of the Drawings

[0018] Figure 1 The molecular structure diagram of the fluorescent copper nanocluster cation group ([Cu 13 (L)4(C≡CPhC≡C)6] + ) prepared in Example 1 of the present invention;

[0019] Figure 2 The anatomical diagram of the fluorescent copper nanoclusters prepared in Example 1 of the present invention;

[0020] Figure 3 The high-resolution mass spectrum of the fluorescent copper nanoclusters prepared in Example 1 of the present invention;

[0021] Figure 4 The absorption spectrum of the fluorescent copper nanoclusters prepared in Example 1 of the present invention;

[0022] Figure 5 The fluorescence lifetime diagram of the fluorescent copper nanoclusters prepared in Example 1 of the present invention;

[0023] Figure 6 The fluorescence spectrum of the fluorescent copper nanoclusters prepared in Example 1 of the present invention;

[0024] Figure 7 The X-ray photoelectron spectroscopy diagram of the fluorescent copper nanoclusters prepared in Example 1 of the present invention. Detailed implementation manners

[0025] The present invention will be further described in detail below in conjunction with specific embodiments.

[0026] The embodiment of the present invention provides a multi-core copper nanocluster fluorescent material, and the molecular formula of the multi-core copper nanocluster fluorescent material is [Cu 13 (L)4(C≡CPhC≡C)6](ClO4), wherein the L is an organophosphorus compound ligand, and the valence in the chemical formula [Cu 13 (L)4(C≡CPhC≡C)6] + is 0, and the multi-core copper nanocluster includes four organophosphorus compound ligands; the L includes two phosphorus atoms connected to two benzene rings and a polycarbon chain connected between the phosphorus atoms, and the length of the polycarbon chain can be four or five or six. In some preferred embodiments, the L is 1,4-bis(diphenylphosphino)butane (C 28 H 28 P2 dppb), 1,5-bis(diphenylphosphino)pentane (C 29 H 30 P2 dppp) or 1,6-bis(diphenylphosphino)hexane (C 30 H 32 P2dpph).

[0027] Please refer to Figure 1 and Figure 2 The multinuclear copper nanocluster is composed of 13 copper atoms, 6 alkynyl ligands and 4 bisphosphine ligands. The center of the innermost layer is a layered square Cu5, and there is a circular square Cu8 in the outer ring. The square in the center and the square in the outer ring form Cu 13 through a coplanar manner. The bisphosphine ligand coordinates with 4 copper atoms at the vertices to form a ribbon-like coordination structure in the outer ring. The bidentate alkynyl ligand coordinates with the copper atoms on the faces and edges in a μ4 mode, and finally forms a copper nanocluster with a "four-leaf clover" structure.

[0028] The embodiment of the present invention also provides a preparation method of the above-mentioned multinuclear copper nanocluster fluorescent material, including the following steps:

[0029] (1) Dissolve Cu(ClO4)2, alkynyl ligand 1,2-diethynylbenzene and triethylamine in the first solvent, and stir and react to obtain a first solution to form Cu2(C≡C)2Ph. The first solution is a colorless and transparent solution;

[0030] Under normal temperature and pressure, by stirring, Cu(ClO4)2, alkynyl ligand 1,2-diethynylbenzene and triethylamine can be completely dissolved in the first solvent while sufficient reaction can be achieved to obtain the first solution. The stirring time can be adjusted according to the solubility of Cu(ClO4)2, alkynyl ligand 1,2-diethynylbenzene and triethylamine in the first solvent;

[0031] The stirring time is preferably less than 2 h, more preferably less than 40 min, and even more preferably less than 20 min;

[0032] Preferably, the first solvent is at least one of methanol, dichloromethane, chloroform, and tetrahydrofuran; the first solvent can dissolve Cu(ClO4)2, alkynyl ligand 1,2-diethynylbenzene and triethylamine at the same time and does not chemically react with Cu(ClO4)2, alkynyl ligand 1,2-diethynylbenzene and triethylamine. The amount of the first solvent can ensure that Cu(ClO4)2, alkynyl ligand 1,2-diethynylbenzene and triethylamine can be completely dissolved;

[0033] (2) Add bisphosphine ligand L to the first solution prepared in step (1) to obtain a second solution; L is one of 1,4-bis(diphenylphosphino)butane (C 28 H 28 P2 dppb), 1,5-bis(diphenylphosphino)pentane (C 29 H 30 P2 dppp), 1,6-bis(diphenylphosphino)hexane (C 30 H 32 P2 dpph);

[0034] (3) Add a compound containing hydrogen in a negative valence state to the second solution prepared in step (2) to obtain a third solution containing polynuclear copper nanoclusters. The third solution is an orange-red clear solution. After drying, the solid polynuclear copper nanocluster crystal is the polynuclear copper nanocluster fluorescent material.

[0035] To achieve a higher yield of polynuclear copper nanoclusters, the molar ratio between Cu(ClO4)2 and the alkyne ligand 1,2-diethynylbenzene is 1:8, and the molar ratio between the alkyne ligand 1,2-diethynylbenzene and triethylamine is 1:2.2.

[0036] In a preferred embodiment, the compound containing hydrogen in a negative valence state is preferably NaBH4.

[0037] To achieve a higher yield of polynuclear copper nanoclusters, the molar ratio between the compound containing hydrogen in a negative valence state and Cu2(C≡C)2Ph is (1 / 25 - 1 / 2):1. More preferably, the molar ratio is 1:1. Under this condition, the yield of the obtained polynuclear copper nanoclusters is the highest.

[0038] In one embodiment, the compound containing hydrogen in a negative valence state is first dissolved in a second solvent to form a fourth solution, and then the fourth solution is added to the second solution, so that the compound containing hydrogen in a negative valence state can be uniformly mixed with the second solution and react to obtain a red clear third solution. Specifically, the second solvent can be ethanol, as long as the second solvent can dissolve the compound containing hydrogen in a negative valence state and does not chemically react with the compound containing hydrogen in a negative valence state, and the amount of the second solvent can ensure that the compound containing hydrogen in a negative valence state can be completely dissolved.

[0039] To avoid the generation of by-products, after adding the compound containing hydrogen in a negative valence state to the second solution for 2 h - 12 h, the third solution is dried. If the time is too long, the possibility of the product reacting with air to form by-products is greater. Preferably, after adding the compound containing hydrogen in a negative valence state to the second solution for 2 h - 4 h, the third solution is dried. Preferably, the third solution is dried by rotary evaporation to quickly end the reaction.

[0040] The preparation method further includes recrystallizing the above-mentioned solid polynuclear copper nanoclusters, that is, further purifying the polynuclear copper nanoclusters to obtain an orange polynuclear copper nanocluster [Cu 13 (L)4(C≡CPhC≡C)6](ClO4) crystal.

[0041] Example 1

[0042] A preparation method of a polynuclear copper nanocluster fluorescent material, comprising the following steps:

[0043] (1) Dissolve 0.1 mmol of Cu(ClO4)2 and 0.8 mmol of 1,2 - diethynylbenzene in a mixed solution of 10 mL of dichloromethane and 5 mL of methanol, and then add 1.76 mmol of triethylamine. The molar ratio of Cu(ClO4)2 to 1,2 - diethynylbenzene is 1:8, and the molar ratio of 1,2 - diethynylbenzene to triethylamine is 1:2.2. Stir and react to obtain the first solution, forming Cu2(C≡C)2Ph;

[0044] (2) Under stirring, add 0.5 mmol of 1,4 - bis(diphenylphosphino)butane to the first solution prepared in step (1) to obtain the second solution; the molar ratio between Cu(ClO4)2 and 1,4 - bis(diphenylphosphino)butane is 1:5;

[0045] (3) Add an ethanol solution containing 0.2 mmol of NaBH4 to the second solution prepared in step (2). The color of the solution gradually turns orange - yellow, and the solvent is evaporated to obtain copper nanoclusters with the molecular formula [Cu 13 (dppb)4(C≡CPhC≡C)6](ClO4), with a yield of 32%.

[0046] Example 2 - 3

[0047] Only change the type of L ligand, and keep other involved steps and process parameters the same as those in Example 1. The yields of the products prepared in Examples 1 - 3 are shown in Table 1 below.

[0048] Table 1 Yields corresponding to different L ligands

[0049]

[0050]

[0051] Figure 1 For the structural schematic diagram of the cation part of [Cu 13 (dppb)4(C≡CPhC≡C)6] + prepared in Example 1 (hydrogen is not shown). It can be seen from the figure that the thirteen Cu atoms in [Cu 13 (dppb)4(C≡CPhC≡C)6] + are centrosymmetrically distributed in space, and four bis - phosphine ligands and six alkynyl ligands coordinate with the copper atoms to form a highly symmetric cluster structure.

[0052] Figure 2 This is the anatomical diagram of the fluorescent copper nanoclusters of the present invention. The cation part [Cu 13 (L)4(C≡CPhC≡C)6] +It is a four-leaf clover core composed of 13 copper atoms. Among them, 5 copper atoms form a heart-shaped square, and 8 copper atoms form a larger square that surrounds the core. The 13 copper atoms do not form an absolute plane but are arranged in a staggered "inside" and "outside" pattern. 6 bidentate alkynyl ligands coordinate with the copper atoms on the surface, and 4 diphosphine ligands coordinate with the copper atoms on the edges, finally forming a flat "four-leaf clover" structure of copper nanoclusters with a size of about 2 nm.

[0053] Figure 3 It is the mass spectrum of the fluorescent copper nanoclusters prepared in Example 1. The upper part of the mass spectrum is the experimental value of the molecular ion peak, and the lower part is the simulated value, which match well in both mass ranges. Among them, for the +1 valence part: [Cu 13 (L)4(C≡CPhC≡C)6] + . It can be found from this that the fluorescent copper nanoclusters prepared in the present invention are stable under mass spectrometry conditions, and [Cu 13 (L)4(C≡CPhC≡C)6] + is consistent with the structure [Cu 13 (L)4(C≡CPhC≡C)6] + in the solid, indicating that the fluorescent copper nanoclusters prepared in the present invention are stably present in the solution state.

[0054] Figure 4 It is the ultraviolet absorption spectrum of the fluorescent copper nanoclusters prepared in Example 1. Cu 13 has two absorption bands at 290 nm, while metal copper nanoparticles usually have a sharp absorption peak at 495 nm, indicating the non-metallic characteristics of Cu 13 . The absorption bands can be attributed to the ultraviolet signals of the alkynyl ligands.

[0055] The copper nanoclusters prepared in Example 1 emit bright yellow light under the irradiation of a room-temperature ultraviolet lamp, as Figure 5 shown; when measuring the emission spectrum of the copper nanoclusters, the maximum emission wavelength is obtained as 580 nm, as Figure 6 shown.

[0056] Figure 7 It is the X-ray photoelectron spectrum of [Cu 13 (dppb)4(C≡CPhC≡C)6](ClO4) prepared in Example 1, indicating that it contains elements such as Cu, C, P, O, Cl, etc.

[0057] As can be seen from the above analysis, the copper nanoclusters synthesized by the present invention not only have a clear structure and composition, but also are applicable to a variety of diphosphine ligands, such as dppb, dppp, dpph, etc., with rich and adjustable structures, good stability, and the copper nanoclusters emit bright yellow light at room temperature; and the synthesis method disclosed and protected by the present invention has the advantages of simple operation, strong applicability and convenient industrial production.

Claims

1. A preparation method of a multi-core copper nanocluster fluorescent material, characterized in that, It includes the following steps: (1) Dissolve Cu(ClO4)2, alkynyl ligand 1,2-diethynylbenzene and triethylamine in a first solvent, stir and react to obtain a first solution, forming Cu2(C≡C)2Ph; (2) Add a bisphosphine ligand L to the first solution prepared in step (1) to obtain a second solution; the bisphosphine ligand L is one of 1,4-bis(diphenylphosphino)butane, 1,5-bis(diphenylphosphino)pentane, 1,6-bis(diphenylphosphino)hexane; (3) Adding a compound containing negatively charged hydrogen to the second solution prepared in step (2) to obtain a third solution containing polynuclear copper nanoclusters, and drying to obtain a solid polynuclear copper nanocluster crystal, which is the polynuclear copper nanocluster fluorescent material; the molecular formula of the polynuclear copper nanocluster fluorescent material is [Cu 13 (L)4(C≡CPhC≡C)6](ClO4), wherein thirteen copper atoms form a square four-leaf clover structure, four diphosphine ligands coordinate with the copper atoms on the square edges to form four sides, and six alkynyl ligands coordinate with the copper atoms on the edges and faces to form a flat cluster as a whole.

2. The preparation method of a multi-core copper nanocluster fluorescent material according to claim 1, characterized in that, In step (1), the molar ratio between Cu(ClO4)2 and alkynyl ligand 1,2-diethynylbenzene is 1:8; the molar ratio between alkynyl ligand 1,2-diethynylbenzene and triethylamine is 1:2.

2.

3. The preparation method of a multi-core copper nanocluster fluorescent material according to claim 1 or 2, characterized in that, In step (2), the molar ratio between Cu(ClO4)2 and bisphosphine ligand L is 1:

5.

4. The preparation method of a multi-core copper nanocluster fluorescent material according to claim 1 or 2, characterized in that, In step (3), the compound containing negatively charged hydrogen is NaBH4, and the molar ratio between Cu2(C≡C)2Ph and NaBH4 is (1 / 25~1 / 2):

1.

5. The preparation method of a multi-core copper nanocluster fluorescent material according to claim 1 or 2, characterized in that, In step (3), it also includes recrystallizing the solid polynuclear copper cluster crystal; controlling the time from adding the compound containing negatively charged hydrogen to the second solution to drying the third solution to be 2~12 h.

6. The preparation method of a multi-core copper nanocluster fluorescent material according to claim 1 or 2, characterized in that, In step (1), the first solvent is at least one of methanol, dichloromethane, chloroform, and tetrahydrofuran.

7. The preparation method of a multi-core copper nanocluster fluorescent material according to claim 1 or 2, characterized in that, In step (3), it includes dissolving the compound containing negatively charged hydrogen in a second solvent to obtain a fourth solution, and adding the fourth solution to the second solution to obtain a third solution containing polynuclear copper nanoclusters.

8. The preparation method of a multi-core copper nanocluster fluorescent material according to claim 7, characterized in that, In step (3), the second solvent is ethanol.

9. The preparation method of a multi-core copper nanocluster fluorescent material according to claim 1 or 2, characterized in that, All steps are carried out at a temperature of 15°C - 40°C and in air.

10. A multi-core copper nanocluster fluorescent material prepared by the preparation method of a multi-core copper nanocluster fluorescent material according to any one of claims 1-9, the molecular formula of the multi-core copper nanocluster fluorescent material is [Cu 13 (L)4(C≡CPhC≡C)6](ClO4), wherein, Thirteen copper atoms form a square four-leaf clover-like structure. Four bisphosphine ligands coordinate with the copper atoms on the square edges to form four sides, and six alkynyl ligands coordinate with the copper atoms on the edges and faces to form a flat cluster as a whole.

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