Cationic Pd nano-cluster and preparation method thereof
A method combining solution-phase reduction and ligand protection was used to prepare cationic Pd nanoclusters via gas-phase diffusion, solving the problem of difficult separation and purification of palladium nanoclusters and obtaining high-purity single-crystal materials with excellent electrocatalytic performance and selective catalytic ability.
Patent Information
- Application Number
- CN202511771127.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-28
- Publication Date
- 2026-02-06
AI Technical Summary
In existing technologies, it is difficult to separate and purify palladium nanoclusters. The high specific surface area makes the clusters prone to deterioration and difficult to cultivate into single crystals. Furthermore, there is limited research on the synthesis of palladium nanoclusters.
A combination of solution-phase reduction and ligand protection was used to grow single crystals via vapor-phase diffusion to prepare cationic Pd nanoclusters with the general molecular formula [Pd4(DPPM)4(PPH)]X2, where X is a halide anion. Bis(diphenylphosphine)methane was used as a ligand to coordinate with the palladium cluster core.
A well-defined, high-purity nanocluster material was obtained, exhibiting a unique UV-Vis absorption spectrum and possessing excellent electrocatalytic performance and selective catalytic ability, capable of selectively reducing cinnamaldehyde to cinnamyl alcohol.
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Figure CN121471277A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the interdisciplinary field of nanomaterials and coordination chemistry, and in particular relates to a cationic Pd nanocluster and its preparation method. Background Technology
[0002] In recent years, metal nanoclusters have emerged as a promising new class of materials due to their tunable size, high specific surface area, and abundant surface active sites, demonstrating excellent performance in fields such as biomedicine and catalysis. In particular, metal nanoclusters provide a precise theoretical model for applications, facilitating the understanding of reaction processes such as product adsorption and active sites in catalytic processes. However, existing research on the synthesis of metal nanoclusters mainly focuses on the preparation of gold, silver, and copper clusters, with very little research on palladium nanoclusters. This is because the separation and purification of palladium clusters is relatively difficult, and the high specific surface area results in high specific surface energy, making palladium clusters prone to degradation and difficult to cultivate into single crystals. Here, we present a method for synthesizing cationic palladium nanoclusters, which allows for the cultivation of single crystals after simple separation and purification, providing an experimental approach for the preparation of palladium nanoclusters. Summary of the Invention
[0003] One of the objectives of this invention is to provide a synthesis scheme for cationic Pd nanoclusters.
[0004] To achieve the above objectives, the present invention employs the following technical solution: a cationic Pd nanocluster with the general molecular formula [Pd₄(DPPM)₄(PPH)]X₂, wherein DPPM is bis(diphenylphosphine)methane and PPH is diphenylphosphine with two hydrogen atoms removed, and its structural formula is shown below: ; PPH is phenylphosphine that has lost two hydrogen atoms and is coordinated with the palladium cluster core through two phosphorus atoms; X is one of the halide anions.
[0005] As a further improvement to the above-mentioned cationic Pd nanoclusters: Preferably, the PPH ligand is in the form of -or -Bridging mode and palladium atom coordination.
[0006] Preferably, the molecular weight of the cationic Pd nanocluster is M ± 50 Da, where M is the theoretical precise molecular weight of the nanocluster.
[0007] Preferably, the anion X is selected from C. B , One of them.
[0008] A second objective of this invention is to provide a method for preparing cationic Pd nanoclusters as described in any one of the above claims, characterized by comprising the following steps: S1. Dissolve the Pd complex containing halogen atoms in a mixed solvent of dichloromethane and methanol, add bisphosphine ligands and reducing agents in sequence and stir thoroughly. React for 1-4 h to obtain a black solution; the molar mass ratio of the Pd complex containing halogen atoms, bisphosphine ligands and reducing agents is 1:(0.5-2):(2-5). S2. Centrifuge the black solution to obtain the supernatant, rotary evaporate the supernatant to obtain the black solid, and dissolve the black solid with trichloroisocyanuric acid to obtain a clear green solution. S3. Using n-pentane as a dispersant, gas-phase diffusion is carried out in a green clear solution to obtain crystals. The crystal products are collected, washed with n-pentane, and then dried under vacuum to obtain cationic Pd nanoclusters.
[0009] As a further improvement to the preparation method of the above-mentioned cationic Pd nanoclusters: Preferably, the halogen-containing Pd complex is (1,5-cyclooctadiene)palladium dichloride, and the reducing agent is tert-butylamine borane.
[0010] Preferably, in step S1, dichloromethane and methanol are mixed as a mixed solvent in a volume ratio of (2-5):1.
[0011] Preferably, in step S1, the concentration of the Pd complex in the mixed solvent is 0.0010-0.015 mmol / ml.
[0012] The advantages of this invention compared to the prior art are as follows: 1) This invention provides a cationic Pd nanocluster with the general molecular formula [Pd₄(DPPM)₄(PPH)]X₂, wherein DPPM is bis(diphenylphosphine)methane, PPH is phenylphosphine stripped of two hydrogen atoms, which coordinates to the palladium cluster core through two phosphorus atoms; X is a catalytically acceptable anion. This Pd nanocluster exhibits a unique UV-Vis absorption spectrum, displaying characteristic absorption peaks at 332 nm, 415 nm, 455 nm, and 613 nm.
[0013] 2) This invention provides a method for preparing cationic Pd nanoclusters. The method combines solution-phase reduction with ligand protection to prepare single-crystal cationic Pd nanoclusters. A key feature of this method is the use of vapor-phase diffusion to grow single crystals, which is an effective means of obtaining well-defined, high-purity nanocluster materials. The process can be divided into three key stages: Reduction and ligand protection reaction: Palladium complexes are reacted with bisphosphine ligands and reducing agents in a mixed organic solvent to generate ligand-protected palladium nanoclusters in situ.
[0014] Preliminary separation and purification: Insoluble matter was removed by centrifugation, and crude product was obtained by rotary evaporation.
[0015] Crystal growth and final purification: High-purity nanocluster single crystals were grown from solution using the mild technique of n-pentane gas-phase diffusion, and the final product was obtained after washing and drying.
[0016] 3) The Pd nanoclusters of the present invention, supported on carbon-based materials, have excellent electrocatalytic performance and can selectively hydrogenate cinnamaldehyde to cinnamyl alcohol, a high-value-added product. Attached Figure Description
[0017] Figure 1 Mass spectra of the Pd nanoclusters prepared in Examples 1-5; Figure 2 The UV-Vis absorption spectra of the Pd nanocluster solutions prepared in Examples 1-5 are shown. Figure 3 XPS tests were performed on the Pd nanoclusters prepared in Examples 1-5. Detailed Implementation
[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0019] Example 1
[0020] This embodiment provides a method for preparing cationic Pd nanoclusters, which specifically includes the following steps: S1. Dissolve 30 mg (1,5-cyclooctadiene) palladium dichloride (0.105 mmol) in a mixed solvent of 6 mL dichloromethane and 12 mL methanol, add 55 mg diphenylphosphine (0.143 mmol), stir for 1 min, then add 2 mL of 35 mg tert-butylamine-borane (0.417 mmol) dissolved in dichloromethane to the solution and react for 2 h. The solution changes from yellow to blackish-green. The molar ratio of Pd complex, bisphosphine ligand, and tert-butylamine borane is 1:1.36:3.97.
[0021] S2. After filtering the obtained solution, centrifuge it and dissolve the obtained clusters in chloroform.
[0022] S3. By using n-pentane as a dispersant, gas-phase diffusion was carried out in a blackish-green chloroform solution to obtain crystals. The crystal products were washed with n-pentane, collected, and dried at room temperature to obtain cationic Pd nanoclusters with the general molecular formula [Pd4(DPPM)4(PPH)]Cl2.
[0023] Example 2
[0024] This embodiment provides a method for preparing cationic Pd nanoclusters, which specifically includes the following steps: S1. Dissolve 30 mg (1,5-cyclooctadiene) palladium dichloride (0.105 mmol) in 6 mL of dichloromethane and 12 mL of methanol, add 76.9 mg of diphenylphosphine methane (0.2 mmol), stir for 1 min, then add 2 mL of dichloromethane dissolved in 30.4 mg of tert-butylamine-borane (0.35 mmol) and react for 2 h. The solution changes from yellow to blackish-green.
[0025] The molar ratio of Pd complex, bisphosphine ligand, and tert-butylamine borane is 1:1.9:3.33.
[0026] S2. After filtering the obtained solution, centrifuge it and dissolve the obtained clusters in chloroform.
[0027] S3. By using n-pentane as a dispersant, gas-phase diffusion was carried out in a blackish-green chloroform solution to obtain crystals. The crystal products were washed with n-pentane, collected, and dried at room temperature to obtain cationic Pd nanoclusters with the general molecular formula [Pd4(DPPM)4(PPH)]Cl2.
[0028] Example 3
[0029] This embodiment provides a method for preparing cationic Pd nanoclusters, which specifically includes the following steps: S1. Dissolve 30 mg (1,5-cyclooctadiene) palladium dichloride (0.105 mmol) in 6 mL of dichloromethane and 12 mL of methanol, add 65 mg of diphenylphosphine methane (0.169 mmol), stir for 1 min, then add 2 mL of dichloromethane dissolved in 33 mg of tert-butylamine-methylborane (0.379 mmol) and react for 2 h. The solution changes from yellow to black-green.
[0030] The molar ratio of Pd complex, bisphosphine ligand, and tert-butylamine borane is 1:1.6:3.61.
[0031] S2. After filtering the obtained solution, centrifuge it and dissolve the obtained clusters in chloroform.
[0032] S3. By using n-pentane as a dispersant, gas-phase diffusion was carried out in a blackish-green chloroform solution to obtain crystals. The crystal products were washed with n-pentane, collected, and dried at room temperature to obtain cationic Pd nanoclusters with the general molecular formula [Pd4(DPPM)4(PPH)]Cl2.
[0033] Example 4
[0034] This embodiment provides a method for preparing cationic Pd nanoclusters, which specifically includes the following steps: S1. Dissolve 30 mg (1,5-cyclooctadiene) palladium dichloride (0.105 mmol) in 6 mL of dichloromethane and 12 mL of methanol, add 45 mg of diphenylphosphine methane (0.117 mmol), stir for 1 min, then add 2 mL of dichloromethane dissolved in 27 mg of tert-butylamine-methylborane (0.310 mmol) and react for 2 h. The solution changes from yellow to black-green.
[0035] The molar ratio of Pd complex, bisphosphine ligand, and tert-butylamine borane is 1:1.11:2.95.
[0036] S2. After filtering the obtained solution, centrifuge it and dissolve the obtained clusters in chloroform.
[0037] S3. By using n-pentane as a dispersant, gas-phase diffusion was carried out in a blackish-green chloroform solution to obtain crystals. The crystal products were washed with n-pentane, collected, and dried at room temperature to obtain cationic Pd nanoclusters with the general molecular formula [Pd4(DPPM)4(PPH)]Cl2.
[0038] Example 5
[0039] This embodiment provides a method for preparing cationic Pd nanoclusters, which specifically includes the following steps: S1. Dissolve 30 mg (1,5-cyclooctadiene) palladium dichloride (0.105 mmol) in 6 mL of dichloromethane and 12 mL of methanol, add 35 mg of diphenylphosphine methane (0.091 mmol), stir for 1 min, then add 2 mL of dichloromethane dissolved in 25 mg of tert-butylamine-methylborane (0.287 mmol) and react for 2 h. The solution changes from yellow to blackish-green.
[0040] The molar ratio of Pd complex, bisphosphine ligand, and tert-butylamine borane is 1:0.86:2.73.
[0041] S2. After filtering the obtained solution, centrifuge it and dissolve the obtained clusters in chloroform.
[0042] S3. By using n-pentane as a dispersant, gas-phase diffusion was carried out in a blackish-green chloroform solution to obtain crystals. The crystal products were washed with n-pentane, collected, and dried at room temperature to obtain cationic Pd nanoclusters with the general molecular formula [Pd4(DPPM)4(PPH)]Cl2.
[0043] Figure 1 Mass spectra of the Pd nanoclusters prepared in Examples 1-5; Figure 1 It can be seen that the cation portion of this cluster is a divalent cation with a mass of 2071 Da.
[0044] Figure 2 The UV-Vis absorption spectra of the Pd nanocluster solutions prepared in Examples 1-5 are shown. Figure 2 It can be seen that the cluster has ultraviolet characteristic absorption peaks at 332nm, 415nm, 455nm, and 613nm.
[0045] Figure 3 XPS testing of the Pd nanoclusters prepared in Examples 1-5; by Figure 3 This reveals the valence states and types of elements contained in the cationic Pd cluster.
[0046] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments. It should be noted that many modifications and improvements can be made by those skilled in the art, and all modifications or improvements not exceeding the scope of the claims should be considered within the protection scope of the present invention.
Claims
1. A cationic Pd nanocluster, characterized in that, Its general molecular formula is [Pd4(DPPM)4(PPH)]X2, where DPPM is bis(diphenylphosphine)methane and PPH is diphenylphosphine with two hydrogen atoms removed. The simplified structural formula is shown below: ； PPH is phenylphosphine that has lost two hydrogen atoms and is coordinated with the palladium cluster core through two phosphorus atoms; X is one of the halide anions.
2. The cationic Pd nanoclusters according to claim 1, characterized in that, The PPH ligand is -or -Bridging mode and palladium atom coordination.
3. The cationic Pd nanoclusters according to claim 1, characterized in that, The molecular weight of this cationic Pd nanocluster is M ± 50 Da, where M is the theoretical exact molecular weight of the nanocluster.
4. The cationic Pd nanoclusters according to claim 1, characterized in that, The anion X is selected from C. B , One of them.
5. A method for preparing cationic Pd nanoclusters according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Dissolve the Pd complex containing halogen atoms in a mixed solvent of dichloromethane and methanol, add bisphosphine ligands and reducing agents in sequence and stir thoroughly. React for 1-4 h to obtain a black solution; the molar mass ratio of the Pd complex containing halogen atoms, bisphosphine ligands and reducing agents is 1:(0.5-2):(2-5). S2. Centrifuge the black solution to obtain the supernatant, rotary evaporate the supernatant to obtain the black solid, and dissolve the black solid with trichloroisocyanuric acid to obtain a clear green solution. S3. Using n-pentane as a dispersant, gas-phase diffusion is carried out in a green clear solution to obtain crystals. The crystal products are collected, washed with n-pentane, and then dried under vacuum to obtain cationic Pd nanoclusters.
6. The method for preparing cationic Pd nanoclusters according to claim 5, characterized in that, The bisphosphine ligand is diphenylphosphine methane, the halogen-containing Pd complex is (1,5-cyclooctadiene)palladium dichloride, and the reducing agent is tert-butylamine borane.
7. The method for preparing cationic Pd nanoclusters according to claim 5, characterized in that, In step S1, dichloromethane and methanol are mixed in a volume ratio of (2-5):1 as a mixed solvent.
8. The method for preparing cationic Pd nanoclusters according to claim 5, characterized in that, In step S1, the concentration of the Pd complex in the mixed solvent is 0.0010-0.015 mmol / ml.