A siloxane ligand protected Ag 40 Nanoclusters, their synthesis methods and applications

Abstract

This invention provides a siloxane ligand-protected Ag 40 Nanoclusters, their synthesis methods, and applications. This invention relates to Ag protected by siloxane ligands. 40 Nanoclusters are composed of RC≡C ‑ and (Ph 4 Si 4 O 8 ) 4‑ Ag protected by both ligands 40 Nanoclusters, with the molecular formula {Ag} 40 [(RC≡C) 8 (Ph 4 Si 4 O 8 ) 6 The silver nanoclusters synthesized in this invention have precise atoms and novel structures; the synthesis method is simple, easy to operate, mild under mild conditions, and the raw materials are readily available, making it potential for industrial and commercial production; the obtained silver nanoclusters exhibit superior fluorescence performance at low temperatures and have a long fluorescence lifetime, making them practically valuable in the field of fluorescent probes and worthy of market promotion.

Description

A siloxane ligand protected Ag 40 Nanoclusters, their synthesis methods and applications Technical Field

[0001] This invention relates to a siloxane ligand-protected Ag 40 Nanoclusters, their synthesis methods, and applications belong to the field of nanocluster and fluorescent materials technology. Background Technology

[0002] Metal siloxanes are typical representatives of the silicon-based compound family, generally referring to cage-like or cluster-like compounds containing Si-OM (M = metal ion) segments. The coordination ability of metals makes metal siloxanes a unique branch of organosilicon compounds. Based on the exploration of cage-like metal siloxanes, researchers have gained a deeper understanding of homogeneous catalytic surface reactions and activities at the molecular level, while atomically precise silsesquioxane metal nanoclusters still have enormous potential for further exploration.

[0003] In recent years, nanoclusters have attracted widespread attention due to their beautiful geometric configurations and potential applications. Ligand engineering for nanoclusters has expanded from traditional alkyne, phosphine, and thiol ligands to nitrogen-containing ligands, metal ligands, and macrocyclic ligands. As a novel type of macrocyclic protecting ligand, oligomeric siloxanes are derived from the hydrolysis and condensation of alkoxysilanes, and most reactions involving siloxanes are carried out in an inert atmosphere. Further research is warranted on how to prepare novel siloxane-protected silver metal nanoclusters using simpler methods.

[0004] Furthermore, existing research results on silver nanoclusters show that some silver nanoclusters have luminescent properties, but their fluorescence lifetime is short, only tens of microseconds or even a few microseconds, which limits their application in the field of fluorescent probes.

[0005] Therefore, developing a novel macrocyclic protective ligand and applying it to the preparation of silver nanoclusters using a simple synthesis method, while simultaneously enabling the resulting silver nanoclusters to possess excellent fluorescence properties, is worthy of further investigation. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a siloxane ligand-protected Ag 40 Nanoclusters, their synthesis methods, and applications. The silver nanoclusters synthesized in this invention have precise atoms and novel structures; the synthesis method is simple, easy to operate, operates under mild conditions, and uses readily available raw materials, making it potential for industrial and commercial production; the obtained silver nanoclusters exhibit superior fluorescence performance at low temperatures and have a long fluorescence lifetime, making them practically valuable in the field of fluorescent probes and worthy of market promotion.

[0007] The technical solution of the present invention is as follows:

[0008] The first objective of this invention is to provide a siloxane ligand-protected Ag 40 Nanoclusters, Ag protected by the siloxane ligand 40 Nanoclusters are composed of RC≡C - and (Ph4Si4O8) 4- Ag protected by both ligands 40 Nanoclusters, with the molecular formula {Ag} 40 [(RC≡C)8(Ph4Si4O8)6]}.

[0009] According to a preferred embodiment of the present invention, the ligand RC≡C - In this embodiment, the substituent R is one of cyclopropyl, tert-butyl, phenyl, or a substituted phenyl group; preferably, the substituent in the substituted phenyl group is -CH3, -OCH3, -C(CH3)3, or -F. (Ligand (Ph4Si4O8)) 4- It is obtained by in-situ hydrolysis and condensation of PhSi(OY)3; wherein the substituent Y is methyl, ethyl or isopropenyl, and Ph is phenyl.

[0010] According to a preferred embodiment of the present invention, the Ag protected by the siloxane ligand 40 Nanoclusters crystallize in the cubic Pm-3 space group.

[0011] According to a preferred embodiment of the present invention, Ag protected by siloxane ligands 40 Nanoclusters composed of Ag 40 Kernel, RC≡C - and (Ph4Si4O8) 4- Composed of a shell made up of binary ligands; Ag 40 The kernel approximates a cube, with eight ligands RC≡C- at the eight vertices of the cube in μ3-η. 1 :η 1 :η 1 Coordination mode and Ag 40 Kernel coordination; (Ph4Si4O8) 4- The macrocyclic ligand is a tetradentate ligand, consisting of 6 (Ph4Si4O8) ligands. 4- The ligands chelate on the six faces of the cube in a μ4 coordination mode. It is worth noting that this Ag... 40 Metallic core and (Ph4Si4O8) 4- Macrocyclic ligands have never been reported in the prior art. This structure is the first silver nanocluster protected by siloxane ligands, and also the metal siloxane cluster with the highest known nucleus number to date.

[0012] According to a preferred embodiment of the present invention, the Ag protected by the siloxane ligand 40 The nanoclusters appear as orange-red blocky crystals.

[0013] The second objective of this invention is to provide Ag protected by the aforementioned siloxane ligands. 40 The method for synthesizing nanoclusters includes the following steps:

[0014] (1) Dissolve silver salt in ammonia water, add organic solvent, and add alkyne ligand RC≡CH dropwise under stirring; then add triethylamine, stir the reaction, filter, wash and dry to obtain silver alkyne precursor, abbreviated as (RC≡CAg). n ;

[0015] (2) The silver acetylation precursor, silver salt, PhSi(OY)3 ligand, and triethylamine were thoroughly dispersed in a polar solvent, and Ag protected by siloxane ligands was obtained by solvothermal reaction. 40 Nanoclusters.

[0016] According to a preferred embodiment of the present invention, in step (1), the silver salt is Ag2O, AgNO3 or AgCl; the organic solvent is one or a combination of two or more of acetonitrile, methanol or ethanol.

[0017] According to a preferred embodiment of the present invention, in step (1), the mass concentration of ammonia is 25%-28%; the molar amount of silver salt and the volume ratio of ammonia are 0.1-0.5 mol / L; and the molar amount of silver salt and the volume ratio of organic solvent are 0.1-1.0 mol / L.

[0018] According to a preferred embodiment of the present invention, in step (1), the substituent R of the alkynyl ligand RC≡CH is one of cyclopropyl, tert-butyl, phenyl or substituted phenyl; preferably, the substituent in the substituted phenyl is -CH3, -OCH3, -C(CH3)3 or -F.

[0019] According to a preferred embodiment of the present invention, in step (1), triethylamine needs to be added dropwise at a rate of 1 to 2 mL / min under vigorous stirring conditions so that the added triethylamine is rapidly dispersed in the solution.

[0020] According to a preferred embodiment of the present invention, in step (1), the molar ratio of silver salt to alkynyl ligand RC≡CH is 1:1, and the molar ratio of alkynyl ligand RC≡CH to triethylamine is 1:1.5.

[0021] According to the present invention, in step (1), after the addition of triethylamine, a large amount of white precipitate is immediately generated.

[0022] According to a preferred embodiment of the present invention, in step (1), the stirring reaction temperature is room temperature, the stirring reaction time is 2 to 4 hours, and the stirring reaction is carried out in the dark.

[0023] According to a preferred embodiment of the present invention, in step (1), the washing is performed sequentially using ethanol and diethyl ether.

[0024] According to a preferred embodiment of the present invention, in step (2), the silver salt is an organic silver salt; preferably, the silver salt is CF3COOAg, PhCOOAg, CH3SO3Ag, CF3SO3Ag, MePhSO3Ag or (CF3SO2N)2Ag.

[0025] According to a preferred embodiment of the present invention, in step (2), the substituent Y in the PhSi(OY)3 ligand is methyl, ethyl or isopropenyl.

[0026] According to a preferred embodiment of the present invention, in step (2), the molar ratio of the silver alkynyl precursor to the silver salt is 1:(1-3), the molar ratio of the PhSi(OY)3 ligand to the silver alkynyl precursor is (3-5):1, and the molar ratio of the triethylamine to the silver alkynyl precursor is (2-8):1.

[0027] According to a preferred embodiment of the present invention, in step (2), the polar solvent is one or a combination of two of methanol, isopropanol, n-butanol, acetonitrile or N,N-dimethylformamide; the molar ratio of silver salt to the volume ratio of polar solvent is 10 to 60 mmol / L.

[0028] According to a preferred embodiment of the present invention, in step (2), the dispersion is carried out under ultrasonic conditions; the ultrasonic temperature is 40°C, the ultrasonic power is 70W, and the ultrasonic time is 30-60min, resulting in a bright orange solution.

[0029] According to a preferred embodiment of the present invention, in step (2), the solvothermal reaction temperature is 65-75°C and the solvothermal reaction time is 20-60h; preferably, the solvothermal reaction temperature is 70°C and the solvothermal reaction time is 52-58h.

[0030] According to a preferred embodiment of the present invention, in step (2), the reaction solution obtained from the solvothermal reaction is filtered, and the resulting solid product is dried to obtain Ag protected by siloxane ligands. 40 Nanoclusters, i.e., when the solvothermal reaction time is relatively long, can directly produce orange-red Ag by burning. 40 Crystals; or, the reaction solution obtained from the solvothermal reaction is filtered, and the filtrate is placed in the dark at room temperature to evaporate and crystallize, yielding Ag protected by siloxane ligands. 40 Nanoclusters.

[0031] The third objective of this invention is to provide Ag protected by the aforementioned siloxane ligands. 40 Application of nanoclusters in fluorescent probes.

[0032] In this invention, Ag 40 Crystals of nanoclusters and trace amounts of Ag 40 The solution obtained by dissolving the crystals of the nanoclusters in dichloromethane exhibits excellent fluorescence properties at low temperatures, emitting red light, and the fluorescence lifetime of the solution is as long as nearly 819 μs.40 The outstanding optical properties and stable luminescence characteristics of nanoclusters make their application in the field of fluorescent probes practically valuable and worthy of market promotion.

[0033] The technical features and beneficial effects of this invention are as follows:

[0034] 1. The silver nanoclusters protected by the siloxane ligands of this invention are composed of RC≡C - and (Ph4Si4O8) 4- Ag protected by both ligands 40 Nanoclusters, with the molecular formula {Ag} 40 [(RC≡C)8(Ph4Si4O8)6]}. This structure is not only atomically precise, but also reveals a novel macrocyclic ligand (Ph4Si4O8). 4- Tetradentate peroxy macrocyclic ligand (Ph4Si4O8) 4- It possesses multiple coordination sites and strong coordination ability, enhancing Ag 40 The structural stability of nanoclusters. From the perspective of classical hard and soft acid-base theory, (Ph4Si4O8) 4- Ag is a hard base, while silver is a soft acid. Coordinating a soft acid with a hard base is challenging, and examples of this work in known silver nanoclusters are extremely rare. The Ag described in this invention... 40 This is the first silver nanocluster protected by a siloxane ligand, enriching the diversity of coin metal nanocluster ligand engineering. Furthermore, this invention represents the highest known number of nuclei in metal siloxane nanoclusters to date, laying the foundation for further development and utilization of siloxane ligands. Current research on silver nanoclusters shows that some exhibit luminescence properties, but their fluorescence lifetimes are short, only tens or even a few microseconds. For example, Ag64-S (J. Am. Chem. Soc. 2022, 144, 40, 18305–18314) has a fluorescence lifetime of 19.38 μs, Ag64-Se has a fluorescence lifetime of 16.23 μs, and Ag22 (Angew. Chem. Int. Ed. 2022, 61, e202211628) has a fluorescence lifetime of 8.48 μs. The Ag nanocluster protected by the siloxane ligand described in this invention… 40 The nanoclusters exhibit superior fluorescence properties at low temperatures, emitting red light with a fluorescence lifetime of nearly 819 μs. The outstanding optical properties and stable luminescence characteristics of the silver nanoclusters in this invention provide important evidence for studying the structure-activity relationship of silver nanoclusters, and also demonstrate their practical application value in the field of fluorescent probes, making them worthy of commercial promotion.

[0035] 2. This invention Ag 40The synthesis of nanoclusters is simple, easy to operate, requires mild conditions, and uses readily available raw materials, making it a potential candidate for industrial and commercial production.

[0036] 3. The synthesis of this invention utilizes a simplified "one-pot" synthesis procedure. Currently reported examples of siloxane ligand-protected transition metal clusters are synthesized in two steps: first, the substituted silane is refluxed at high temperature to hydrolyze and condense, followed by a solvothermal reaction. For example, Eu... 13 (Chem. Mater. 2022, 34, 9, 4186–4194) and Gd13 (ChemPhysMater. 2022, 1, 247–251). In step (2) of this invention, the substituted silane is directly added to the reaction system, and the solution is acid-base adjusted by triethylamine, causing it to hydrolyze and condense in situ to generate a protected ligand siloxane, which then coordinates. This greatly simplifies the experimental steps and optimizes the experimental conditions.

[0037] 4. In step (2) of this invention, the addition of silver salt is to depolymerize the poorly soluble silver acetylide precursor and improve its solubility in the reaction system. Without silver salt, the silver acetylide precursor cannot depolymerize and exists as a solid polymer, ultimately failing to yield the target product of this invention. In step (2) of this invention, the amount of triethylamine plays a crucial role in the hydrolysis and condensation of the substituted silane, and is key to the success or failure of the experiment. Insufficient triethylamine prevents the hydrolysis and condensation of the substituted silane; excessive triethylamine will cause the substituted silane to precipitate, neither of which yields the target product of this invention.

[0038] 5. The Ag protected by the siloxane ligand of the present invention 40 Nanoclusters exhibit superior fluorescence properties, and Ag under low-temperature conditions 40 Crystals and trace Ag 40 The solutions obtained by dissolving the crystals in dichloromethane all emit red fluorescence, and the fluorescence lifetime of the solutions is as long as nearly 819 μs, which has the potential for practical application in the field of fluorescent probes.

[0039] 6. The solvothermal reaction temperature of this invention needs to be suitable. If the temperature is too low, PhSi(OY)3 cannot undergo hydrolysis and condensation in solution; if the temperature is too high, the silver salt will undergo a silver mirror reaction, and the target product of this invention cannot be obtained in either case. The molar ratio of the acetylinic silver precursor, PhSi(OY)3 ligand, and silver salt in this invention needs to be suitable. When the ratio of the acetylinic silver precursor to the silver salt is constant, reducing the amount of PhSi(OY)3 results in a colorless solution after the reaction, while increasing the amount of PhSi(OY)3 results in a gel-like solution, and the target product of this invention cannot be obtained in either case. When the ratio of the acetylinic silver precursor to the PhSi(OY)3 ligand is constant, reducing the amount of silver salt results in the acetylinic silver precursor not being completely depolymerized, leaving a white solid residue at the bottom of the flask after the reaction; increasing the amount of silver salt results in a severe silver mirror phenomenon after the reaction, and the target product of this invention cannot be obtained in either case. When the ratio of PhSi(OY)3 ligand to silver salt is constant, the target product of this invention cannot be obtained regardless of whether the amount of silver acetylide precursor is reduced or increased.

[0040] 7. The novel ligand of this invention (Ph4Si4O8) 4- The introduction of this yielded a completely new approximately cubic Ag. 40 Core. Cyclic tetramer (Ph4Si4O8) 4- The ligands possess C4 symmetry, thereby enhancing the overall Ag content. 40 Symmetry of nanoclusters. 6 (Ph4Si4O8) 4- Chelation enhances Ag on all six faces of the cube. 40 The stability of the nanoclusters. Eight tert-butylacetylene ligands are also symmetrically covering the eight vertices of the cube, further enhancing the symmetry and stability of the structure. Figure description:

[0041] Figure 1 shows the silver nanoclusters {Ag} protected by siloxane ligands prepared and synthesized in Example 2 of this invention. 40 A schematic diagram of the overall structure of the ball-and-stick model of [(RC≡C)8(Ph4Si4O8)6]}.

[0042] Figure 2 shows the silver nanoclusters {Ag} protected by siloxane ligands prepared and synthesized in Example 2 of this invention. 40 A schematic diagram of the bond-line overall structure of [(RC≡C)8(Ph4Si4O8)6]}.

[0043] Figure 3 is a schematic diagram of the structure of the RC≡C- ligand in the silver nanoclusters protected by siloxane ligands prepared and synthesized in Example 2 of the present invention.

[0044] Figure 4 shows the silver nanoclusters (Ph4Si4O8) protected by siloxane ligands synthesized in Example 2 of this invention. 4- A schematic diagram of the ligand structure.

[0045] Figure 5 shows the temperature-dependent solid-state ultraviolet spectrum of the silver nanoclusters protected by siloxane ligands prepared and synthesized in Example 2 of this invention.

[0046] Figure 6 shows the liquid ultraviolet monitoring spectrum of the silver nanoclusters protected by siloxane ligands prepared and synthesized in Example 2 of the present invention.

[0047] Figure 7 shows the solid-state temperature-varying fluorescence of the silver nanoclusters protected by siloxane ligands prepared and synthesized in Example 2 of this invention from 80K to 290K.

[0048] Figure 8 shows the solution fluorescence emission spectra of the silver nanoclusters protected by siloxane ligands prepared and synthesized in Example 2 of the present invention from 80K to 300K.

[0049] Figure 9 shows the solution fluorescence lifetime test results of the silver nanoclusters protected by siloxane ligands prepared and synthesized in Example 2 of this invention from 80 to 300 K. Detailed implementation method:

[0050] The present invention will be further described below with reference to specific embodiments and accompanying drawings, but is not limited thereto.

[0051] Unless otherwise specified, all raw materials used in the embodiments are conventional products; and all methods used are existing technologies unless otherwise specified.

[0052] Example 1:

[0053] Ag protected by siloxane ligands in this invention 40 The specific method for synthesizing nanoclusters is as follows:

[0054] (1) Prepare a silver ammonia solution by dissolving silver salt in ammonia water. The molar ratio of silver salt to ammonia water is 0.2 mol / L. Ethanol is selected as the organic solvent. The molar ratio of silver salt to ethanol is 0.25 mol / L. The molar ratio of silver salt to alkyne ligand RC≡CH is 1:1. The molar ratio of alkyne ligand RC≡CH to triethylamine is 1:1.5.

[0055] That is, dissolve 30 mmol of Ag₂O in 150 mL of 25% ammonia solution, add 120 mL of ethanol, and then add 30 mmol dropwise under stirring. t BuC≡CH; then, under vigorous stirring, 45 mmol of triethylamine was added dropwise at a rate of 1 mL / min, immediately producing a large amount of white precipitate. After stirring at room temperature for 4 h, the mixture was filtered, washed three times each with ethanol and ether, and dried in a cool, dry, and ventilated place to obtain the tert-butylacetyleny silver precursor ( t BuC≡CAg) n The yield was 93%.

[0056] (2) tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio with silver salt is 1:2, substituted silane and tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio of triethylamine to silver tert-butylacetylenyne precursor is 4:1. t BuC≡CAg) n The molar ratio is 5:1, and the polar solvents chosen are methanol and N,N-dimethylformamide.

[0057] That is, 0.05 mmol of tert-butylacetylene silver precursor ( t BuC≡CAg) n 0.1 mmol CF3SO3Ag was dissolved in 2 mL of N,N-dimethylformamide, followed by 3 mL of methanol solution containing 0.2 mmol PhSi(OMe)3 and 0.25 mmol triethylamine. The mixture was sonicated at 70 W and 40 °C for 40 min, gradually turning orange-yellow. After sonication, the reaction flask was placed in a reaction vessel and subjected to a solvothermal reaction at 70 °C for 58 h. After the solvothermal reaction was completed, orange-red Ag was directly calcined. 40 After filtration of the crystal and reaction solution, the resulting solid product is dried to obtain the product with the molecular formula Ag. 40 [( t Orange-red blocky crystals of [BuC≡C)8(Ph4Si4O8)6] were obtained with a yield of 11%.

[0058] Example 2:

[0059] Ag protected by siloxane ligands in this invention 40 The specific method for synthesizing nanoclusters is as follows:

[0060] (1) Prepare a silver ammonia solution by dissolving silver salt in ammonia water. The molar ratio of silver salt to ammonia water is 0.2 mol / L. Ethanol is selected as the organic solvent. The molar ratio of silver salt to ethanol is 0.25 mol / L. The molar ratio of silver salt to alkyne ligand RC≡CH is 1:1. The molar ratio of alkyne ligand RC≡CH to triethylamine is 1:1.5.

[0061] That is, dissolve 30 mmol of Ag₂O in 150 mL of 25% ammonia solution, add 120 mL of ethanol, and then add 30 mmol dropwise under stirring. t BuC≡CH; then, under vigorous stirring, 45 mmol of triethylamine was added dropwise at a rate of 1 mL / min, immediately producing a large amount of white precipitate. After stirring at room temperature for 4 h, the mixture was filtered, washed three times each with ethanol and ether, and dried in a cool, dry, and ventilated place to obtain the tert-butylacetyleny silver precursor ( t BuC≡CAg)n The yield was 93%.

[0062] (2) tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio with silver salt is 1:2, substituted silane and tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio of triethylamine to silver tert-butylacetylenyne precursor is 4:1. t BuC≡CAg) n The molar ratio is 5:1, and the polar solvents chosen are methanol and N,N-dimethylformamide.

[0063] That is, 0.05 mmol of tert-butylacetylene silver precursor ( t BuC≡CAg) n 0.1 mmol CF3SO3Ag was dissolved in 2 mL of N,N-dimethylformamide, followed by 3 mL of methanol solution containing 0.2 mmol PhSi(OMe)3 and 0.25 mmol triethylamine. The mixture was sonicated at 70 W and 40 °C for 40 min, gradually turning orange-yellow. After sonication, the reaction flask was placed in a reaction vessel and subjected to a solvothermal reaction at 70 °C for 52 h. After the solvothermal reaction, the solution was filtered, and the filtrate was allowed to evaporate at room temperature under dark conditions to crystallize, yielding Ag. 40 [( t Orange-red blocky crystals of [BuC≡C)8(Ph4Si4O8)6] were obtained with a yield of 15%.

[0064] Example 3:

[0065] Ag protected by siloxane ligands in this invention 40 The specific method for synthesizing nanoclusters is as follows:

[0066] (1) Prepare a silver ammonia solution by dissolving silver salt in ammonia water. The molar ratio of silver salt to ammonia water is 0.2 mol / L. Ethanol is selected as the organic solvent. The molar ratio of silver salt to ethanol is 0.25 mol / L. The molar ratio of silver salt to alkyne ligand RC≡CH is 1:1. The molar ratio of alkyne ligand RC≡CH to triethylamine is 1:1.5.

[0067] That is, dissolve 30 mmol of Ag₂O in 150 mL of 25% ammonia solution, add 120 mL of ethanol, and then add 30 mmol dropwise under stirring. tBuC≡CH; then, under vigorous stirring, 45 mmol of triethylamine was added dropwise at a rate of 1 mL / min, immediately producing a large amount of white precipitate. After stirring at room temperature for 4 h, the mixture was filtered, washed three times each with ethanol and ether, and dried in a cool, dry, and ventilated place to obtain the tert-butylacetyleny silver precursor ( t BuC≡CAg) n The yield was 93%.

[0068] (2) tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio with silver salt is 1:2, substituted silane and tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio of triethylamine to silver tert-butylacetylenyne precursor is 4:1. t BuC≡CAg) n The molar ratio is 5:1, and the polar solvents chosen are isopropanol and N,N-dimethylformamide.

[0069] That is, 0.05 mmol of tert-butylacetylene silver precursor ( t BuC≡CAg) n 0.1 mmol CF3SO3Ag was dissolved in 2 mL of N,N-dimethylformamide, followed by 3 mL of isopropanol solution containing 0.2 mmol PhSi(OMe)3 and 0.25 mmol triethylamine. The mixture was sonicated at 70 W and 40 °C for 40 min, gradually turning orange-yellow. After sonication, the reaction flask was placed in a reaction vessel and subjected to a solvothermal reaction at 70 °C for 52 h. After the solvothermal reaction was completed, the solution was filtered, and the filtrate was allowed to evaporate at room temperature under dark conditions to crystallize, yielding Ag. 40 [( t Orange-red blocky crystals of [BuC≡C)8(Ph4Si4O8)6] were obtained with a yield of 18%.

[0070] Example 4:

[0071] Ag protected by siloxane ligands in this invention 40 The specific method for synthesizing nanoclusters is as follows:

[0072] (1) Prepare a silver ammonia solution by dissolving silver salt in ammonia water. The molar ratio of silver salt to ammonia water is 0.2 mol / L. Ethanol is selected as the organic solvent. The molar ratio of silver salt to ethanol is 0.25 mol / L. The molar ratio of silver salt to alkyne ligand RC≡CH is 1:1. The molar ratio of alkyne ligand RC≡CH to triethylamine is 1:1.5.

[0073] That is, dissolve 30 mmol of Ag₂O in 150 mL of 25% ammonia solution, add 120 mL of ethanol, and then add 30 mmol dropwise under stirring. t BuC≡CH; then, under vigorous stirring, 45 mmol of triethylamine was added dropwise at a rate of 1 mL / min, immediately producing a large amount of white precipitate. After stirring at room temperature for 4 h, the mixture was filtered, washed three times each with ethanol and ether, and dried in a cool, dry, and ventilated place to obtain the tert-butylacetyleny silver precursor ( t BuC≡CAg) n The yield was 93%.

[0074] (2) tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio with silver salt is 1:2, substituted silane and tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio of triethylamine to silver tert-butylacetylenyne precursor is 4:1. t BuC≡CAg) n The molar ratio is 5:1, and the polar solvents chosen are n-butanol and N,N-dimethylformamide.

[0075] That is, 0.05 mmol of tert-butylacetylene silver precursor ( t BuC≡CAg) n 0.1 mmol CF3SO3Ag was dissolved in 2 mL of N,N-dimethylformamide, followed by 3 mL of n-butanol solution containing 0.2 mmol PhSi(OMe)3 and 0.25 mmol triethylamine. The mixture was sonicated at 70 W and 40 °C for 40 min, gradually turning orange-yellow. After sonication, the reaction flask was placed in a reaction vessel and subjected to a solvothermal reaction at 70 °C for 52 h. After the solvothermal reaction was completed, the solution was filtered, and the filtrate was allowed to evaporate at room temperature under dark conditions to crystallize, yielding Ag. 40 [( t Orange-red blocky crystals of [BuC≡C)8(Ph4Si4O8)6] were obtained with a yield of 24%.

[0076] Example 5:

[0077] Ag protected by siloxane ligands in this invention 40 The specific method for synthesizing nanoclusters is as follows:

[0078] (1) Prepare a silver ammonia solution by dissolving silver salt in ammonia water. The molar ratio of silver salt to ammonia water is 0.2 mol / L. Ethanol is selected as the organic solvent. The molar ratio of silver salt to ethanol is 0.25 mol / L. The molar ratio of silver salt to alkyne ligand RC≡CH is 1:1. The molar ratio of alkyne ligand RC≡CH to triethylamine is 1:1.5.

[0079] That is, dissolve 30 mmol of Ag₂O in 150 mL of 25% ammonia solution, add 120 mL of ethanol, and then add 30 mmol dropwise under stirring. t BuC≡CH; then, under vigorous stirring, 45 mmol of triethylamine was added dropwise at a rate of 1 mL / min, immediately producing a large amount of white precipitate. After stirring at room temperature for 4 h, the mixture was filtered, washed three times each with ethanol and ether, and dried in a cool, dry, and ventilated place to obtain the tert-butylacetyleny silver precursor ( t BuC≡CAg) n The yield was 93%.

[0080] (2) tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio with silver salt is 1:2, substituted silane and tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio of triethylamine to silver tert-butylacetylenyne precursor is 4:1. t BuC≡CAg) n The molar ratio is 5:1, and the polar solvents chosen are acetonitrile and N,N-dimethylformamide.

[0081] That is, 0.05 mmol of tert-butylacetylene silver precursor ( t BuC≡CAg) n 0.1 mmol CF3SO3Ag was dissolved in 2 mL of N,N-dimethylformamide, followed by 3 mL of acetonitrile solution containing 0.2 mmol PhSi(OMe)3 and 0.25 mmol triethylamine. The mixture was sonicated at 70 W and 40 °C for 40 min, gradually turning orange-yellow. After sonication, the reaction flask was placed in a reaction vessel and subjected to a solvothermal reaction at 70 °C for 52 h. After the solvothermal reaction was completed, the solution was filtered, and the filtrate was allowed to evaporate at room temperature under dark conditions to crystallize, yielding Ag. 40 [( t Orange-red blocky crystals of [BuC≡C)8(Ph4Si4O8)6] were obtained with a yield of 27%.

[0082] Comparative Example 1:

[0083] The method for synthesizing nanoclusters is as described in Example 2, except that: no silver acetylide precursor is added in step (2); the other steps and conditions are the same as in Example 2.

[0084] Specifically, 0.1 mmol CF3SO3Ag was dissolved in 2 mL of N,N-dimethylformamide, followed by the addition of 3 mL of methanol solution containing 0.2 mmol PhSi(OMe)3 and 0.25 mmol triethylamine. The mixture was sonicated at 70 W and 40 °C for 40 min. The resulting solution was filtered, and the filtrate was allowed to evaporate at room temperature in the dark. The target product was obtained when no crystallization occurred.

[0085] Comparative Example 2:

[0086] The method for synthesizing nanoclusters is as described in Example 2, except that the triethylamine in step (2) is replaced with other bases of different strengths in the same molar amount, namely: sodium hydroxide, tetramethylammonium hydroxide, and tetramethylethylenediamine; the other steps and conditions are the same as in Example 2.

[0087] Specifically:

[0088] (1) Tert-butylacetylenic silver precursor ( t BuC≡CAg) n The preparation is the same as in Example 2;

[0089] (2) In this step, triethylamine is replaced with other bases of different strengths, namely: sodium hydroxide, tetramethylammonium hydroxide, and tetramethylethylenediamine.

[0090] ① tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio with silver salt is 1:2, substituted silane and tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio of sodium hydroxide to tert-butylacetylenic silver precursor is 4:1. t BuC≡CAg) n The molar ratio is 5:1, and the polar solvents chosen are methanol and N,N-dimethylformamide.

[0091] That is, 0.05 mmol of tert-butylacetylene silver precursor ( t BuC≡CAg) nDissolve 0.1 mmol CF3SO3Ag in 2 mL of N,N-dimethylformamide, add 3 mL of methanol solution containing 0.2 mmol PhSi(OMe)3, and weigh 0.25 mmol (10 mg) of sodium hydroxide solid into the reaction solution. Sonicate the mixture at 70 W and 40 °C for 40 min; the solution immediately turns orange. After sonication, place the reaction flask into a reaction vessel and allow it to undergo a solvothermal reaction at 70 °C for 52 h. After the solvothermal reaction, filter the solution and allow the filtrate to evaporate at room temperature under dark conditions; no crystals were obtained.

[0092] ② tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio with silver salt is 1:2, substituted silane and tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio is 4:1, with tetramethylammonium hydroxide and tert-butylacetylenic silver precursor ( t BuC≡CAg) n The molar ratio is 5:1, and the polar solvents chosen are methanol and N,N-dimethylformamide.

[0093] That is, 0.05 mmol of tert-butylacetylene silver precursor ( t BuC≡CAg) n The solution was dissolved in 2 mL of N,N-dimethylformamide with 0.1 mmol CF3SO3Ag, followed by 3 mL of methanol solution containing 0.2 mmol PhSi(OMe)3. 0.25 mmol (26 μL) of tetramethylammonium hydroxide solution was then transferred using a pipette. The mixture was sonicated at 70 W at 40 °C for 40 min, immediately turning a bright orange color. After sonication, the reaction flask was placed in a reaction vessel and subjected to a solvothermal reaction at 70 °C for 52 h. After the solvothermal reaction, the solution was filtered, and the filtrate was allowed to evaporate at room temperature under dark conditions; no crystals were obtained.

[0094] ③Terty-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio with silver salt is 1:2, substituted silane and tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio of tetramethylethylenediamine to tert-butylacetyleny silver precursor is 4:1. t BuC≡CAg) n The molar ratio is 5:1, and the polar solvents chosen are methanol and N,N-dimethylformamide.

[0095] That is, 0.05 mmol of tert-butylacetylene silver precursor ( t BuC≡CAg) nThe solution was dissolved in 2 mL of N,N-dimethylformamide with 0.1 mmol CF3SO3Ag, followed by 3 mL of methanol solution containing 0.2 mmol PhSi(OMe)3 and 0.25 mmol (37 μL) tetramethylethylenediamine. The mixture was sonicated at 70 W at 40 °C for 40 min, immediately turning a pale yellow color. After sonication, the reaction flask was placed in a reaction vessel and subjected to a solvothermal reaction at 70 °C for 52 h. After the solvothermal reaction, the solution was filtered, and the filtrate was allowed to evaporate at room temperature under dark conditions; no crystals were obtained.

[0096] Comparative Example 3:

[0097] The method for synthesizing nanoclusters is as described in Example 2, except that silver salt is not added in step (2); the other steps and conditions are the same as in Example 2.

[0098] Specifically:

[0099] (1) Tert-butylacetylenic silver precursor ( t BuC≡CAg) n The preparation is the same as in Example 2;

[0100] (2) No silver salt is added in this step.

[0101] That is, 0.05 mmol of tert-butylacetylene silver precursor ( t BuC≡CAg) n Dissolve the sample in 2 mL of N,N-dimethylformamide, then add 3 mL of methanol solution containing 0.2 mmol PhSi(OMe)₃ and 0.25 mmol triethylamine. Sonicate the mixture at 70 W and 40 °C for 40 min to obtain a milky white turbid liquid. After sonication, place the reaction flask into a reaction vessel and allow it to undergo a solvothermal reaction at 70 °C for 52 h. After the solvothermal reaction is complete, filter the solution, and then allow the filtrate to evaporate at room temperature under dark conditions. If crystallization does not occur, the target product is obtained.

[0102] The above comparative examples and embodiments illustrate that the synergistic protection of Ag by the silver acetylene precursor and siloxane ligands during the reaction process is crucial. 40 A prerequisite for stable formation. Without the addition of the silver acetylene precursor, Ag cannot be crystallized. 40 Silver nanoclusters. Secondly, adjusting the solution pH with triethylamine directly determines the reaction process of substituted silane hydrolysis and condensation, which is crucial to the success of the experiment. Finally, the addition of silver salt not only promotes the dissociation of the silver acetylide precursor polymer and increases its solubility in the solution system, but also provides silver atoms for the formation of silver nanoclusters. Silver salt is also an indispensable reaction condition during the crystallization process.

[0103] Comparative Example 4:

[0104] The method for synthesizing nanoclusters is as described in Example 2, except that the solvothermal reaction temperatures in step (2) are 60°C and 80°C, respectively; the other steps and conditions are the same as in Example 2.

[0105] Specifically:

[0106] (1) Tert-butylacetylenic silver precursor ( t BuC≡CAg) n The preparation is the same as in Example 2;

[0107] (2) The solvothermal reaction temperatures in this step are 60℃ and 80℃, respectively.

[0108] ① tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio with silver salt is 1:2, substituted silane and tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio of triethylamine to silver tert-butylacetylenyne precursor is 4:1. t BuC≡CAg) n The molar ratio is 5:1, and the polar solvents chosen are methanol and N,N-dimethylformamide.

[0109] That is, 0.05 mmol of tert-butylacetylene silver precursor ( t BuC≡CAg) n The solution was dissolved in 2 mL of N,N-dimethylformamide with 0.1 mmol CF3SO3Ag, followed by 3 mL of methanol solution containing 0.2 mmol PhSi(OMe)3 and 0.25 mmol triethylamine. The mixture was sonicated at 70 W and 40 °C for 40 min, gradually turning orange-yellow. After sonication, the reaction flask was placed in a reaction vessel and subjected to a solvothermal reaction at 60 °C for 52 h. After the solvothermal reaction was completed, the resulting solution was filtered to obtain a colorless solution. The filtrate was then allowed to evaporate at room temperature under dark conditions; no crystals were obtained.

[0110] ② tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio with silver salt is 1:2, substituted silane and tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio of triethylamine to silver tert-butylacetylenyne precursor is 4:1. t BuC≡CAg) n The molar ratio is 5:1, and the polar solvents chosen are methanol and N,N-dimethylformamide.

[0111] That is, 0.05 mmol of tert-butylacetylene silver precursor ( t BuC≡CAg)n The solution was dissolved in 2 mL of N,N-dimethylformamide with 0.1 mmol CF3SO3Ag, followed by 3 mL of methanol solution containing 0.2 mmol PhSi(OMe)3 and 0.25 mmol triethylamine. The mixture was sonicated at 70 W and 40 °C for 40 min, gradually turning orange-yellow. After sonication, the reaction flask was placed in a reaction vessel and subjected to a solvothermal reaction at 80 °C for 52 h. After the solvothermal reaction, a silver mirror phenomenon was observed on the wall of the reaction flask. The resulting solution was filtered to obtain a light yellow solution. The filtrate was then allowed to evaporate at room temperature under dark conditions; no crystals were obtained.

[0112] As illustrated by the comparative examples and embodiments above, the reaction system of this invention is highly sensitive to the solvothermal reaction temperature. If the reaction temperature is too low, PhSi(OY)3 cannot undergo in-situ hydrolysis and condensation in solution; if the reaction temperature is too high, a severe silver mirror reaction will occur, ultimately preventing the acquisition of the target product of this invention. Therefore, the solvothermal reaction temperature is crucial to the reaction system.

[0113] Comparative Example 5:

[0114] The method for synthesizing nanoclusters is as described in Example 2, except that the amount of PhSi(OMe)3 ligand in step (2) is increased and decreased respectively, while the other steps and conditions are the same as in Example 2.

[0115] Specifically:

[0116] (1) Tert-butylacetylenic silver precursor ( t BuC≡CAg) n The preparation is the same as in Example 2;

[0117] (2) The amount of PhSi(OMe)3 used in this step is 0.3 mmol and 0.1 mmol, respectively.

[0118] ① tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio with silver salt is 1:2, substituted silane and tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio of triethylamine to silver tert-butylacetylene precursor is 6:1. t BuC≡CAg) n The molar ratio is 5:1, and the polar solvents chosen are methanol and N,N-dimethylformamide.

[0119] That is, 0.05 mmol of tert-butylacetylene silver precursor ( t BuC≡CAg) n0.1 mmol CF3SO3Ag was dissolved in 2 mL of N,N-dimethylformamide, followed by the addition of 3 mL of methanol solution containing 0.3 mmol PhSi(OMe)3 and 0.25 mmol triethylamine. The mixture was sonicated at 70 W and 40 °C for 40 min, gradually turning orange-yellow. After sonication, the reaction flask was placed in a reaction vessel and subjected to a solvothermal reaction at 70 °C for 52 h. After the solvothermal reaction, the solution was gel-like. Filtering yielded a pale yellow solution. The filtrate was evaporated at room temperature under dark conditions; no crystals were obtained.

[0120] ② tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio with silver salt is 1:2, substituted silane and tert-butylacetyleny silver precursor ( t BuC≡CAg) n The molar ratio of triethylamine to silver tert-butylacetylene precursor is 2:1. t BuC≡CAg) n The molar ratio is 5:1, and the polar solvents chosen are methanol and N,N-dimethylformamide.

[0121] That is, 0.05 mmol of tert-butylacetylene silver precursor ( t BuC≡CAg) n The solution was dissolved in 2 mL of N,N-dimethylformamide with 0.1 mmol CF3SO3Ag, followed by 3 mL of methanol solution containing 0.1 mmol PhSi(OMe)3 and 0.25 mmol triethylamine. The mixture was sonicated at 70 W and 40 °C for 40 min, gradually turning orange-yellow. After sonication, the reaction flask was placed in a reaction vessel and subjected to a solvothermal reaction at 70 °C for 52 h. After the solvothermal reaction, the solution was gel-like. The solution was filtered to obtain a colorless solution. The filtrate was evaporated at room temperature under dark conditions, and no crystals were obtained.

[0122] As illustrated by the comparative examples and embodiments above, if the ratio of PhSi(OMe)3 to silver acetylene precursor in the reaction system is too high, PhSi(OMe)3 will undergo extensive hydrolysis in the reaction system, resulting in a gel-like reaction solution after solvothermal reaction, which is not conducive to crystallization. If the ratio is too low, PhSi(OMe)3 cannot coordinate and chelate with silver atoms in the system, and the target product cannot be obtained. During the reaction process, the feed ratio of the precursor to the ligand plays a significant role in whether the target reaction can proceed smoothly and ultimately obtain the target product.

[0123] Experimental Example 1: Structural Characterization

[0124] The crystal structure of the silver nanoclusters synthesized in Example 2 was characterized, and the specific structure is shown in Figures 1 and 2.

[0125] The structure of the silver nanoclusters prepared in Example 2 was determined by single-crystal X-ray diffraction: Ag 40 [( t [BuC≡C)8(Ph4Si4O8)6]. Silver nanoclusters crystallize in the cubic crystal system, space group Pm-3. These silver nanoclusters consist of a core and a shell. The novel core and six macrocyclic hard base ligands (Ph4Si4O8) chelated on the surface are present in the silver nanoclusters. 4- These are the two highlights of crystal structure.

[0126] The core of the silver nanoclusters is approximately cubic, and the outer shell is composed of... t BuC≡C - and (Ph4Si4O8) 4- It is composed of binary ligands. Through the combined action of alkynyl ligands and siloxane ligands, this example of Ag with structural aesthetics was generated. 40 Silver nanoclusters. 8 t BuC≡C - It is attached to the eight vertices of the cube, 6 of which are (Ph4Si4O8). 4- The ligands chelate on the six faces of the cube, increasing structural stability. On one hand, according to the classical hard-soft acid-base theory (HSAB), (Ph4Si4O8) 4- As a hard base, it tends to coordinate with hard acids, while the coin metal is a soft acid, making coordination between soft acids and hard bases more difficult. On the other hand, (Ph4Si4O8) 4- It is a bowl-shaped macrocyclic ligand, and the steric hindrance further increases the difficulty of coordination. Therefore, Ag... 40 The structure contains 6 (Ph4Si4O8) atoms. 4- The coordination of these elements is all the more precious.

[0127] Figures 3 and 4 further analyze Ag 40 The structure of the nanoclusters was shown, and tert-butylacetylene ligands were also demonstrated. t BuC≡C - And phenylsiloxane ligand (Ph4Si4O8) 4- The coordination mode.

[0128] The core of the silver nanoclusters is approximately cubic, and its metallic framework consists of Ag. 16 Kernel and Ag 24 The shell is composed of [elements], therefore the kernel can be described as Ag. 16 @Ag 24The silver nanocluster core can be viewed as two intersecting Ag8 units. Each Ag8 unit consists of two square pyramids and a tetrahedron. The two pyramids share a common base, and the tetrahedron is located between the two pyramids, coplanar with both pyramids. Rotating an Ag8 unit perpendicular to the plane 90 degrees clockwise and then flipping it yields the opposite Ag8 unit. The outer perimeter is formed by constructing eight triangles based on the eight vertices of a cube. 24 The outer shell. All eight tert-butylacetylene ligands at the apex are in μ3-η... 1 :η 1 :η 1 Coordination mode and Ag 24 The outer shell connects the ligands. After hydrolysis and condensation, PhSi(OMe)3 forms a "bowl-shaped" tetradentate ligand (Ph4Si4O8). 4- It is chelated on the six faces of the cube in a μ4 coordination mode.

[0129] Test Example 2: Performance Measurement

[0130] (1) Ag protected by the siloxane ligands synthesized in Example 2 40 The nanoclusters were subjected to variable-temperature solid-state UV spectroscopy and liquid UV spectroscopy, as shown in Figures 5 and 6.

[0131] As shown in Figure 5, the variable-temperature solid-state UV spectrum exhibits a broad absorption peak in the range of 294 nm to 520 nm. Figure 6 shows that trace amounts (two to three crystals) of Ag... 40 The liquid UV absorption spectrum of the nanoclusters dissolved in 3 mL of dichloromethane solution showed three absorption peaks at 355 nm, 420 nm, and 500 nm. The high-energy absorption peaks represent charge transfer between the ligand and the metal, while the low-energy absorption peaks represent charge transfer between the metals. After three days of real-time UV monitoring, the absorption peak positions remained unchanged, indicating that Ag... 40 Nanoclusters exhibit good stability in solution.

[0132] (2) Ag protected by the siloxane ligands synthesized in Example 2 40 The luminescence properties of the nanoclusters in both solid and solution were investigated, as shown in Figures 7, 8, and 9. In Figures 7 and 8, the arrows indicate gradually increasing test temperatures.

[0133] As shown in Figure 7, Ag 40 The solid-state fluorescence emission peak of the nanoclusters is at 717 nm. Temperature and fluorescence intensity show a linear negative correlation; the lower the temperature, the stronger the fluorescence, especially exhibiting excellent fluorescence performance at low temperatures. Furthermore, the fluorescence images of the crystals at different temperatures strongly corroborate the conclusion that solid-state fluorescence significantly increases with decreasing temperature. As shown in Figure 8, trace amounts (two to three crystals) of Ag... 40Nanoclusters dissolved in 3 mL of dichloromethane solution, from 80 K to 300 K, Ag 40 Temperature-dependent emission spectra of the nanocluster solution showed an emission wavelength of 690 nm. The fluorescence of the solution significantly increased with decreasing temperature. Figure 9 shows that trace amounts (two to three crystals) of Ag... 40 The nanoclusters dissolved in 3 mL of dichloromethane solution exhibited a fluorescence lifetime of up to 819 μs at 80 K. The fluorescence lifetime decreased with increasing temperature. The fluorescence lifetime of the solution in this invention is significantly longer than that of other reported silver nanoclusters: Ag64-S and Ag64-Se (J. Am. Chem. Soc. 2022, 144, 40, 18305–18314) have fluorescence lifetimes of 19.38 μs and 16.23 μs, respectively; Ag22 (Angew. Chem. Int. Ed. 2022, 61, e202211628) has a fluorescence lifetime of 8.48 μs.

[0134] In summary, the silver nanoclusters protected by siloxane ligands synthesized by the present invention not only have well-defined structures and compositions, but also feature simple synthesis methods, convenient operation, mild conditions, and readily available raw materials. Furthermore, they exhibit excellent fluorescence properties and have practical application value in the field of fluorescent probes.

[0135] The embodiments described above are merely preferred embodiments of the present invention and not all embodiments. Based on the embodiments of the present invention, any equivalent substitutions, improvements, recombinations, etc., made without creative effort to obtain all other embodiments are within the scope of protection of the present invention.

Claims

1. A siloxane ligand-protected Ag 40 Nanoclusters, characterized in that, The Ag protected by the siloxane ligand 40 Nanoclusters are composed of RC≡C - and (Ph4Si4O8) 4- Ag protected by both ligands 40 Nanoclusters, with the molecular formula {Ag} 40 [(RC≡C)8(Ph4Si4O8)6]}; Ag protected by the siloxane ligand 40 Nanoclusters crystallize in the cubic crystal system, space group Pm-3; Siloxane ligand protected Ag 40 Nanoclusters composed of Ag 40 Kernel, RC≡C - and (Ph4Si4O8) 4- Composed of a shell made up of binary ligands; Ag 40 The kernel is approximately cubic with 8 ligands RC≡C - At the eight vertices of the cube, with μ3-η 1 :η 1 :η 1 Coordination mode and Ag 40 Kernel coordination; (Ph4Si4O8) 4- The macrocyclic ligand is a tetradentate ligand, consisting of 6 (Ph4Si4O8) ligands. 4- The ligands are chelated on the six faces of the cube in a μ4 coordination mode.

2. Ag protected by the siloxane ligand according to claim 1 40 Nanoclusters, characterized by ligands RC≡C - In this context, the substituent R is one of cyclopropyl, tert-butyl, phenyl, or a substituted phenyl group; the substituent in the substituted phenyl group is -CH3, -OCH3, -C(CH3)3, or -F.

3. Ag protected by siloxane ligands according to claim 1 40 Nanoclusters, characterized in that, The Ag protected by the siloxane ligand 40 The nanoclusters appear as orange-red blocky crystals.

4. Ag protected by siloxane ligands as described in any one of claims 1-3 40 The method for synthesizing nanoclusters includes the following steps: (1) dissolving silver salt in ammonia water, adding organic solvent, and adding alkyne ligand RC≡CH dropwise under stirring conditions; then adding triethylamine, reacting with stirring, filtering, washing, and drying to obtain the silver alkyne precursor, abbreviated as (RC≡CAg). n (2) The silver acetylene precursor, silver salt, PhSi(OY)3 ligand, and triethylamine were fully dispersed in a polar solvent and subjected to a solvothermal reaction to obtain Ag protected by siloxane ligands. 40 Nanoclusters; the substituent Y in the PhSi(OY)3 ligand is methyl, ethyl or isopropenyl; the molar ratio of silver alkynyl precursor to silver salt is 1:(1-3), the molar ratio of PhSi(OY)3 ligand to silver alkynyl precursor is (3~5):1, and the molar ratio of triethylamine to silver alkynyl precursor is (2~8):

1.

5. Ag protected by the siloxane ligand according to claim 4 40 A method for synthesizing nanoclusters, characterized in that, Step (1) includes one or more of the following conditions: i. The silver salt is Ag₂O, AgNO₃, or AgCl; the organic solvent is one or a combination of two or more of acetonitrile, methanol, or ethanol; ii. The mass concentration of ammonia is 25%-28%; the molar ratio of silver salt to ammonia is 0.1-0.5 mol / L; the molar ratio of silver salt to organic solvent is 0.1-1.0 mol / L; iii. The substituent R of the alkyne ligand RC≡CH is cyclopropyl. One of tert-butyl, phenyl, or substituted phenyl; the substituent in the substituted phenyl is -CH3, -OCH3, -C(CH3)3, or -F; iv. Triethylamine is added dropwise at a rate of 1-2 mL / min under vigorous stirring; v. The molar ratio of silver salt to alkyne ligand RC≡CH is 1:1, and the molar ratio of alkyne ligand RC≡CH to triethylamine is 1:1.5; vi. The stirring reaction is carried out at room temperature for 2-4 hours, and the stirring reaction is carried out in the dark throughout the process.

6. Ag protected by the siloxane ligand according to claim 4 40 A method for synthesizing nanoclusters, characterized in that, Step (2) includes one or more of the following conditions: i. The silver salt is an organic silver salt; ii. The polar solvent is one or a combination of two of methanol, isopropanol, n-butanol, acetonitrile, or N,N-dimethylformamide; the molar ratio of the silver salt to the volume ratio of the polar solvent is 10~60 mmol / L; iii. Sufficient dispersion is carried out under ultrasonic conditions; the ultrasonic temperature is 40℃, the ultrasonic power is 70W, and the ultrasonic time is 30~60min; iv. The reaction solution obtained from the solvothermal reaction is filtered, and the resulting solid product is dried to obtain Ag protected by siloxane ligands. 40 Nanoclusters; or, the reaction solution obtained from the solvothermal reaction is filtered, and the filtrate is evaporated at room temperature in the dark, crystallizing to obtain Ag protected by siloxane ligands. 40 Nanoclusters.

7. Ag protected by siloxane ligands according to claim 6 40 A method for synthesizing nanoclusters, characterized in that, The silver salts are CF3COOAg, PhCOOAg, CH3SO3Ag, CF3SO3Ag, MePhSO3Ag, or (CF3SO2N)2Ag.

8. Ag protected by the siloxane ligand according to claim 4 40 A method for synthesizing nanoclusters, characterized in that, In step (2), the solvothermal reaction temperature is 65-75℃ and the solvothermal reaction time is 20-60h.

9. Ag protected by siloxane ligands as described in any one of claims 1-3 40 Application of nanoclusters in the preparation of fluorescent probes.

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