Au7Cu10 nanocluster as well as preparation method and application thereof

Abstract

The invention discloses an Au7Cu10 nanocluster and a preparation method and application thereof.The preparation method comprises the following steps that chloroauric acid and cuprous chloride serve as a gold source and a copper source respectively and are dissolved and stirred in a solvent, 1-adamantanethiol is added, and the color of the solution is changed into dark green from yellow; continuously adding diphenyl-2-pyridine phosphine to enable the color of the solution to be changed from dark green to light orange, continuously adding a mixed solution of sodium borohydride and ice water, and isolating air to enable the color of the solution to be quickly changed into black; and centrifuging to remove a water phase, evaporating an organic phase, washing black precipitate, recrystallizing a crude product at low temperature, and culturing to obtain the Au7Cu10 nanocluster. The Au7Cu10 nanocluster disclosed by the invention shows excellent performance, so that the Au7Cu10 nanocluster has the potential of serving as molecular triplet energy and an electronic substitute in optoelectronics, photocatalysis and solar energy conversion.

Description

Technical Field

[0001] The present invention relates to an Au 7 Cu 10 nanocluster and its preparation method and application, belonging to the technical field of nanomaterial preparation. Background Art

[0002] Nanomaterial-organic hybrids play a central role in facilitating the precise transfer of triplet excitons and electrons, which is an important foundation in fields ranging from optoelectronics to photocatalysis. The study of photoinduced electron transfer from nanomaterials to organic molecules has emerged as a promising approach to replace triplet energy transfer and regulate the utilization of triplet excitons. Despite significant progress in the study of triplet exciton utilization in quantum nanomaterials, the mechanism for directly extracting triplet energy and electrons from nanomaterials remains elusive.

[0003] The emergence of atomically precise metal nanoclusters has provided new opportunities for exploring and improving the utilization of triplet excitons. Metal nanoclusters are a class of novel luminescent nanomaterials that exhibit molecule-like behavior, with tunable bandgaps and unique optical and electronic properties. These properties can be precisely regulated by adjusting their size, structure, and metal composition.

[0004] To promote the practical application of metal nanomaterials, it is necessary to deeply study the electron and energy transfer mechanisms in these materials, which is crucial for their development and utilization in fields such as triplet sensitizers, optical sensing, and catalysis. Metal nanoclusters with well-defined structures provide new opportunities to achieve this goal. Summary of the Invention

[0005] Aiming at the problems existing in the above-mentioned prior art, the present invention provides an Au 7 Cu 10 nanocluster and its preparation method and application, having an exact atomic structure and near-infrared luminescence properties with a high quantum yield.

[0006] To achieve the above object, a preparation method of an Au 7 Cu 10 nanocluster adopted by the present invention comprises the following steps:

[0007] (1) Using chloroauric acid and cuprous chloride as the gold source and copper source respectively, dissolving them in a solvent, stirring, and adding 1-adamantanethiol to make the color of the solution change from yellow to dark green;

[0008] (2) Continuing to add diphenyl-2-pyridylphosphine to make the color of the solution change from dark green to light orange, and then continuing to add a mixture of sodium borohydride and ice water, isolating the air, to make the color of the solution quickly change to black;

[0009] (3) Centrifuge to remove the aqueous phase, evaporate the organic phase, wash the black precipitate, recrystallize the crude product at low temperature, and cultivate to obtain Au 7 Cu 10 nanoclusters.

[0010] As an improvement, in the step (1), chloroauric acid and cuprous chloride are dissolved in tetrahydrofuran;

[0011] The mass ratio of chloroauric acid, cuprous chloride and 1-adamantanethiol is (1 - 2):1:(1 - 3).

[0012] As an improvement, in the step (1), the mass-volume ratio of chloroauric acid to tetrahydrofuran is (50 - 100 mg):(10 - 15 mL).

[0013] As an improvement, in the step (2), the mass ratio of diphenyl-2-pyridylphosphine to chloroauric acid in the step (1) is (2 - 3):(1 - 2).

[0014] As an improvement, in the step (2), the mass-volume ratio of sodium borohydride to ice water is (40 - 60 mg):(4 - 6 mL); the mass ratio of sodium borohydride to chloroauric acid is 1:(1 - 2).

[0015] As an improvement, in the step (3), the black precipitate is washed repeatedly with dichloromethane / n-hexane; the crude product is recrystallized with dichloromethane / n-hexane at 4 °C.

[0016] As an improvement, it specifically includes the following steps:

[0017] (1) Dissolve chloroauric acid and cuprous chloride in tetrahydrofuran and stir vigorously. Subsequently, directly add 1-adamantanethiol to the mixed solution, and the color of the mixture changes from yellow to dark green;

[0018] (2) After 20 - 40 min, add diphenyl-2-pyridylphosphine to the mixed solution, and the color of the solution changes from dark green to light orange; after 10 - 30 min, add the mixed solution of sodium borohydride dissolved in ice water to the above solution, stopper to isolate air, and the color of the solution quickly changes to black;

[0019] (3) After 15 - 20 h, centrifuge to remove the aqueous phase, evaporate the organic phase, then wash the black precipitate repeatedly with dichloromethane / n-hexane, and recrystallize the crude product in dichloromethane / n-hexane; cultivate for 5 - 7 d, and the black crystals that appear are Au 7 Cu 10 nanoclusters.

[0020] In the second aspect of the present invention, there is also provided an Au 7 Cu 10Nanoclusters prepared by the method for preparing the Au 7 Cu 10 nanoclusters;

[0021] The Au 7 Cu 10 metal core of the nanoclusters consists of an icosahedral core of Au 7 Cu 6 and four copper atoms riveted on the surface, and are respectively covered by three thiol ligands, six phosphine ligands and three halogen atoms on the periphery.

[0022] As an improvement, the Au 7 Cu 10 nanoclusters are composed of an icosahedron of Au covered by one upward Cu atom and three downward Cu atoms 7 Cu 6 ;

[0023] In the icosahedron composed of Au 7 Cu 6 the average Au core -M shell and M shell -M shell distances are 2.663 Å and 2.857 Å respectively, and the Au 7 Cu 10 core is covered by three adamantane thiols, six diphenyl-2-pyridylphosphines and three Cl atoms through the bonding modes of Cu-N / S and Au-Cl / P.

[0024] In the third aspect of the present invention, there is also provided an application of the nanoclusters prepared by the preparation method or the Au 7 Cu 10 nanoclusters in energy and electron transfer, especially in triplet energy transfer and / or photoinduced electron transfer technologies, so that the Au 7 Cu 10 nanoclusters can be used as triplet sensitizers, optical sensors and catalysts.

[0025] Reaction mechanism of the present invention:

[0026] According to the "coordination preference" principle between different metal atoms (Au, Cu) and ligands, organic thiol ligands (such as 1-adamantane thiol) and organic phosphine ligands containing N (such as diphenyl-2-pyridylphosphine) are reasonably selected as ligands, and by precisely reducing the ratio of ligands and the reaction temperature (ice water), the ratio of ligands to metal atoms in the target cluster species is regulated, so as to obtain Au 7 Cu 10 nanoclusters with a relatively large surface active space.

[0027] The present invention uses gold salts and copper salts as metal sources, and prepares Au 7 Cu 10 nanoclusters with precise structures under the protection of dual ligands of organic thiols and organic phosphines. Crystal structure analysis shows that the metal core of the cluster consists of an icosahedral Au 7 Cu 6 (M 13 ) core and 4 copper atoms riveted on the surface. The periphery is respectively covered by three thiol ligands, six phosphine ligands and three halogen atoms. The nanoclusters have remarkable near-infrared luminescence properties and can undergo triplet energy transfer and photoinduced electron transfer, and thus can be further used in the fields of triplet sensitizers, optical sensing and catalysts. Description of the Drawings

[0028] Figure 1 Schematic diagram of the atomic structure of the Au 7 Cu 10 nanoclusters of Example 1 of the present invention;

[0029] Figure 2 Ultraviolet-visible absorption spectrum and fluorescence emission spectrum of the Au 7 Cu 10 nanoclusters of Example 1 of the present invention;

[0030] Figure 3 Fluorescence lifetimes of the Au 7 Cu 10 nanoclusters of Example 1 of the present invention in different gas atmospheres;

[0031] Figure 4 Absorption spectrum of the Au 7 Cu 10 nanoclusters of Example 1 of the present invention in the presence of perylene;

[0032] Figure 5 Emission spectrum of the Au 7 Cu 10 nanoclusters of Example 1 of the present invention in the presence of perylene (excitation wavelength is 600 nm, the inset is the Stern-Volmer plot of the dynamic quenching rate constant K SV );

[0033] Figure 6 Fluorescence spectrum of the Au 7 Cu 10 nanoclusters of Example 1 of the present invention mixed with different concentrations of perylene under 663 nm excitation (the inset is a photo of the upconversion emission process caused by triplet annihilation);

[0034] Figure 7 Schematic diagram of the atomic structure of the Au 7 Cu10 Relationship diagram between upconversion efficiency caused by triplet-triplet annihilation of nanoclusters and the concentration of perylene added

[0035] Figure 8 Au of Example 1 of the present invention 7 Cu 10 Absorption spectra of nanoclusters in the presence of different concentrations of methyl violet (the inset shows the absorption spectra of the Au 7 Cu 10 and methyl violet mixture in methanol respectively);

[0036] Figure 9 Au of Example 1 of the present invention 7 Cu 10 Emission spectra of nanoclusters in the presence of different concentrations of methyl violet (the excitation wavelength is 600 nm, and the inset shows the Stern-Volmer plot of the dynamic quenching rate constant K SV ); Detailed implementation manners

[0037] The following embodiments are further explanations of the content of the present invention to illustrate the technical content of the present invention. However, the substantial content of the present invention is not limited to the following embodiments. Those of ordinary skill in the art can and should know that any simple changes or substitutions based on the substantial spirit of the present invention should fall within the protection scope required by the present invention.

[0038] In the following, the ultraviolet spectrophotometer used is the UV-6000PC ultraviolet spectrophotometer; the fluorescence spectrophotometer is the Omnifluo990LSP fluorescence spectrophotometer.

[0039] Example 1

[0040] A preparation method of Au 7 Cu 10 nanoclusters, comprising the following steps:

[0041] (1) Weigh 80 mg of chloroauric acid and dissolve it in 13 mL of tetrahydrofuran. Then add 50 mg of cuprous chloride and continue to dissolve. Under the condition of rapid stirring, directly add 100 mg of 1-adamantanethiol. The color of the solution changes from yellow to dark green, indicating the formation of the Au(I) / Cu(I)-SR complex;

[0042] (2) Continue to stir rapidly for 30 min, directly add 130 mg of diphenyl-2-pyridylphosphine to the above reaction mixture. After stirring for 15 min, pour the solution formed by dissolving 50 mg of sodium borohydride in 5 mL of ice water into the above reaction solution, and plug it to isolate air. The color of the solution quickly turns black;

[0043] (3) After reacting for 16 h, the aqueous phase was removed by centrifugation, and the organic phase was dried by rotary evaporation; subsequently, the black precipitate was washed with dichloromethane / n-hexane multiple times to remove the excess ligand and by-products. Then, the black precipitate was recrystallized using a dichloromethane / n-hexane system at 4 °C for 6 days. The black massive crystals that appeared were the Au 7 Cu 10 nanoclusters.

[0044] Figure 1 Figure for the atomic structure of the Au 7 Cu 10 nanoclusters obtained from the black massive crystals prepared in Example 1 measured by X-ray single crystal diffractometer. It consists of an icosahedron covered by one upward Cu atom and three downward Cu atoms with Au 7 Cu 6 in the middle. In the icosahedron composed of Au 7 Cu 6 , the average Au core -M shell (referring to the bond length between the core Au atom and the shell M atom; M = Au or Cu) and M shell -M shell (M = Au or Cu) distances are 2.663 Å and 2.857 Å respectively. For the surface protecting ligand, the Au 7 Cu 10 core is covered by three 1-adamantanethiol (1-Adm), six diphenyl-2-pyridylphosphine (Ph 2 PyP), and three Cl atoms through Cu-N / S and AuCl / P coordination. Its exact molecular formula is [Au 7 Cu 10 (1-Adm) 3 (Ph 2 PyP) 6 Cl 3 3+ . Note: Figure 1 In, the yellow small balls are nitrogen atoms, the green small balls are copper atoms, the magenta small balls are phosphorus atoms, the cyan small balls are chlorine atoms, the red small balls are sulfur atoms, the gray small balls are carbon atoms, and the purple small balls are nitrogen atoms.

[0045] Example 2

[0046] Au 7 Cu 10 Optical properties of nanoclusters in tetrahydrofuran solution:

[0047] Figure 2 Figure for the UV-visible absorption spectrum of the black crystals prepared in Example 1 in tetrahydrofuran solution and the emission spectra under different gas atmospheres. It can be seen that Au​7 Cu 10 Two characteristic absorption peaks appeared in the absorption spectrum of the nanoclusters, at 365 nm and 635 nm respectively. In addition, this Au 7 Cu 10 The nanocluster solution exhibited an obvious emission band at 740 nm, and the fluorescence quantum yield was as high as 26% in air.

[0048] Figure 3 The Au 7 Cu 10 nanoclusters prepared in Example 1 had fluorescence lifetimes in different gas atmospheres, showing a long lifetime of 3.5 μs in air atmosphere.

[0049] Example 3

[0050] Au 7 Cu 10 Triplet energy transfer performance of the nanoclusters:

[0051] The Au 7 Cu 10 nanoclusters prepared in Example 1 were tested for triplet energy transfer. The specific process was as follows: Au 7 Cu 10 The nanoclusters were mixed with perylene at different concentrations (0 - 6.6 mM), and the ultraviolet-visible absorption spectra and fluorescence emission spectra of different mixtures were measured respectively. After introducing perylene, it was dissolved in an anaerobic tetrahydrofuran solution, excited at 663 nm, and the fluorescence emission spectrum was measured.

[0052] Figure 4 For the Au 7 Cu 10 ultraviolet-visible absorption spectrum of the mixture after introducing perylene into the nanoclusters. It can be seen that Au 7 Cu 10 There were very small changes in the absorbance and spectral shape of the absorption band at 600 - 700 nm, thus ruling out the possibility of forming a complex between Au 7 Cu 10 and perylene, indicating that in the presence of perylene, Au 7 Cu 10 the nanoclusters maintained their original size and composition.

[0053] Figure 5 For the emission spectrum of the mixture after introducing perylene into the Au 7 Cu 10 nanoclusters. It can be seen that when the concentration of perylene added reached 6.6 mM, Au 7 Cu 10 the fluorescence intensity of the nanoclusters in the mixed solution was quenched by 94%. CombiningFigure 4 , it can be inferred that Au 7 Cu 10 There is a triplet energy transfer between the nanoclusters and perylene.

[0054] Figure 6 For Au 7 Cu 10 Fluorescence spectra of the mixed solution of Au 7 Cu 10 nanoclusters and perylene under excitation at 663 nm. It can be seen that under the irradiation of a low-energy (663 nm) light source, the fluorescence of perylene in the high-energy (400 nm - 500 nm) region is induced to be excited, indicating that Au Figure 7 nanoparticles effectively sensitize perylene molecules, and an upconversion process occurs, and its anti-Stokes shift exceeds 0.88 eV. From

[0055] Example 4

[0056] Au 7 Cu 10 Electron transfer performance of Au

[0057] The Au 7 Cu 10 nanoclusters prepared in Example 1 were tested for electron transfer. The specific process is as follows: Au 7 Cu 10 nanoclusters were mixed with methyl violet at different concentrations (0 - 15.5 mM), and the ultraviolet-visible absorption spectra and fluorescence emission spectra of different mixtures were measured respectively.

[0058] Figure 8 For Au 7 Cu 10 Ultraviolet-visible absorption spectra of the mixture after introducing different concentrations of methyl violet into Au 7 Cu 10 nanoclusters. It can be seen that after adding methyl violet, the absorption band of Au 7 Cu 10 nanoclusters at 630 nm remains unchanged, indicating that there is no ground-state interaction between the two components, and Au

[0059] Figure 9 For Au 7 Cu 10 After introducing different concentrations of methyl violet into the Au 7 Cu 10The emission intensity of the nanoclusters decreased, and when the methyl violet concentration increased to 15 mM, more than 90% of the fluorescence intensity was quenched. Combining Figure 8 It can be concluded that this effective quenching indicates that the excited state inactivation occurs through the photoinduced electron transfer pathway.

[0060] The Au 7 Cu 10 nanoclusters of the present invention can be directly used for triplet energy and electron transfer, have the potential as triplet energy level sensitizers, promote triplet energy level annihilation, and achieve an upconversion efficiency of 18.4% in perylene. The excellent performance exhibited by the nanoclusters makes them have the potential as molecular triplet energy and electron substitutes in optoelectronics, photocatalysis, and solar energy conversion.

[0061] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, or improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Au7Cu 10 The method for preparing nanoclusters is characterized in that: The following steps are involved: (1) Use chloroauric acid and cuprous chloride as the gold source and copper source, respectively, dissolve them in a solvent, stir, and add 1-adamantanethiol to change the color of the solution from yellow to dark green; (2) Continue to add diphenyl-2-pyridinylphosphine until the color of the solution changes from dark green to light orange, and continue to add a mixture of sodium borohydride and ice water, isolating the air, so that the color of the solution quickly changes to black; (3) Remove the aqueous phase by centrifugation, evaporate the organic phase, wash the black precipitate, and recrystallize the crude product at low temperature to obtain Au7Cu 10 Nanoclusters.

2. The Au7Cu according to claim 1 10 The method for preparing nanoclusters is characterized in that: In the step (1), chloroauric acid and cuprous chloride are dissolved in tetrahydrofuran; The mass ratio of the chloroauric acid, cuprous chloride and 1-adamantanethiol is (1-2):1:(1-3).

3. The Au7Cu according to claim 2 10 The method for preparing nanoclusters is characterized in that: In the step (1), the mass volume ratio of chloroauric acid to tetrahydrofuran is (50-100 mg): (10-15 mL).

4. The Au7Cu according to claim 1 10 The method for preparing nanoclusters is characterized in that: The mass ratio of diphenyl-2-pyridinylphosphine in step (2) to chloroauric acid in step (1) is (2-3): (1-2).

5. The Au7Cu according to claim 1 10 The method for preparing nanoclusters is characterized in that: The mass volume ratio of sodium borohydride to ice water in step (2) is (40-60 mg): (4-6 mL); The mass ratio of the sodium borohydride to the chloroauric acid is 1:(1-2).

6. The Au7Cu according to claim 1 10 The method for preparing nanoclusters is characterized in that: In the step (3), the black precipitate is washed multiple times with dichloromethane / n-hexane; and the crude product is recrystallized with dichloromethane / n-hexane at 4°C.

7. The Au7Cu according to claim 1 10 The method for preparing nanoclusters is characterized in that: The specific steps include: (1) Dissolve chloroauric acid and cuprous chloride in tetrahydrofuran and stir vigorously. Then, add 1-adamantanethiol directly to the mixed solution. The color of the mixture changes from yellow to dark green. (2) After 20-40 min, diphenyl-2-pyridinylphosphine is added to the mixed solution, and the color of the solution changes from dark green to light orange. After 10-30 min, a mixed solution of sodium borohydride dissolved in ice water is added to the above solution, and a stopper is added to isolate the air, and the color of the solution quickly changes to black. (3) After 15-20 h, the aqueous phase was removed by centrifugation, and the organic phase was evaporated. The black precipitate was then washed several times with dichloromethane / n-hexane, and the crude product was recrystallized from dichloromethane / n-hexane. After culturing for 5-7 days, the black crystals that appeared were Au7Cu 10 Nanoclusters. 8.Au7Cu 10 Nanoclusters, characterized in that The Au7Cu according to any one of claims 1 to 7 is used. 10 The nanoclusters are prepared by a preparation method; The Au7Cu 10 The metal core of the nanocluster consists of an Au7Cu6 icosahedral core and four copper atoms riveted to the surface, which are covered by three thiol ligands, six phosphine ligands and three halogen atoms respectively.

9. The Au7Cu according to claim 8 10 Nanoclusters, characterized in that The Au7Cu 10 The nanoclusters consist of Au7Cu6 icosahedrons capped by one Cu atom pointing upward and three Cu atoms pointing downward; In the icosahedron composed of Au7Cu6, the average Au core -M shell and M shell -M shell The distances are 2.663 Å and 2.857 Å, respectively, for Au7Cu 10 The core is co-capped by three adamantane thiols, six diphenyl-2-pyridylphosphine, and three Cl atoms via Cu-N / S and Au-Cl / P bonding.

10. Au7Cu prepared by the preparation method according to any one of claims 1 to 7 or according to any one of claims 8 to 9 10 Applications of nanoclusters in energy and electron transfer.

Images