Near-infrared responsive photothermal silver palladium nanocluster materials, preparation method and application thereof

Abstract

The application belongs to the cross field of nanomaterials and coordination chemistry, and specifically discloses a near-infrared responsive photothermal silver-palladium nanocluster material, a preparation method and application in near-infrared photothermal conversion. 362 H 270 Ag 20 Cl4F 12 P8Pd5Sb2, which is abbreviated as Ag 20 Pd5(4‑EBP) 18 (DPPP)4(SbF6)2·2CH2Cl2, belongs to a monoclinic system, and a space group is P21 / n, a =16.228(13)Å, b =40.670(3)Å, c =25.941(2)Å, α=90°, β =100.283(2)°, gamma =90°, V=16846(2)Å 3 , and a molecular weight is 8170.22 Da. The preparation method has short process flow, simple operation, and raw materials are easy to obtain. The photothermal silver-palladium nanocluster has a high photothermal efficiency of 73.25% under 915 nm (0.6 W / cm 2 ) laser excitation, and has good application prospect.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of nanomaterials and coordination chemistry, and in particular relates to a near-infrared responsive photothermal silver-palladium nanocluster material, its preparation method, and its application in near-infrared photothermal conversion. Background Technology

[0002] The efficient conversion and utilization of solar energy is a cutting-edge research topic, and achieving efficient capture and conversion of near-infrared light energy, which accounts for approximately 54% of total solar energy, remains a core challenge in this field. Traditional photothermal conversion materials generally suffer from weak near-infrared absorption, poor wavelength matching, insufficient light capture capacity, and poor photostability, resulting in low photothermal conversion efficiency. This makes it difficult to achieve synergistic optimization of strong near-infrared absorption, high conversion efficiency, and high stability, severely restricting their crucial technological support role in solar energy utilization, energy conversion, and sustainable development. Photothermal conversion efficiency (PCE), as a core performance indicator, fundamentally determines the application potential of materials in photothermal therapy, photothermal seawater desalination, and photothermal de-icing. Therefore, developing novel near-infrared responsive photothermal conversion materials that combine high photothermal conversion performance with excellent photostability is key to promoting the practical application of photothermal technology. Summary of the Invention

[0003] The purpose of this invention is to provide a near-infrared responsive photothermal silver-palladium nanocluster material, which combines high-efficiency photothermal conversion performance with excellent photostability and strong near-infrared absorption.

[0004] To achieve the above objectives, the present invention employs the following technical solution: a near-infrared responsive photothermal silver-palladium nanocluster, wherein the chemical formula of the photothermal silver-palladium nanocluster material is C2. 362 H 270 Ag 20 Cl4F 12 P8Pd5Sb2, abbreviated as Ag 20 Pd5(4-EBP) 18 (DPPP)4(SbF6)2·2CH2Cl2 belongs to the monoclinic crystal system; space group P21 / n. a =16.228(13) Å, b =40.670(3)Å, c =25.941(2) Å, α =90°, β =100.283(2)°, γ =90°, V=16846(2) Å 3 The molecular weight is 8170.22 Da; DPPP is 1,3-bis(diphenylphosphine)propane, and 4-EBP is deprotonated 4-acetylene biphenyl. The structural formula is shown in the figure below: .

[0005] As a further improvement of photothermal silver-palladium nanoclusters

[0006] Preferably, the structure of the photothermal silver-palladium nanocluster material consists of 20 Ag atoms, 5 Pd atoms, 4 DPPP organic ligands, 18 deprotonated 4-acetylene biphenyls, 2 hexafluoroantimonate counterions, and 2 dichloromethane solvent molecules.

[0007] The second objective of this invention is to provide a method for preparing the near-infrared responsive photothermal silver-palladium nanoclusters described in any one of the above-mentioned claims, comprising the following steps: S1. Add silver salt to a mixed solvent of dichloromethane and methanol, stir to dissolve it completely, then add 1,3-bis(diphenylphosphine)propane, palladium salt and 4-acetylene biphenyl, and continue stirring to obtain a homogeneous mixed solution. S2. Add sodium borohydride aqueous solution to the mixed solution and react at room temperature for 24-48 h to obtain a suspension; add excess n-hexane to the suspension, centrifuge to collect the precipitate, and wash and centrifuge again with excess n-hexane to obtain the crude product; S3. Dissolve the crude product in dichloromethane, and at room temperature, diffuse diethyl ether into the solution in the gas phase to induce crystal formation. Collect the crystal product, air dry it naturally, and obtain a photothermal silver-palladium nanocluster material with near-infrared response.

[0008] As a further improvement to the preparation method of the above-mentioned photothermal silver-palladium nanoclusters: Preferably, the molar ratio of sodium borohydride contained in the silver salt, palladium salt, 1,3-bis(diphenylphosphine)propane, 4-acetylene biphenyl and sodium borohydride aqueous solution is 1:0.092:(0.8-1):(1.2-1.8):(0.4-2.3).

[0009] Preferably, the silver salt in step S1 is silver hexafluoroantimonate and the palladium salt is palladium acetate.

[0010] Preferably, in step S1, dichloromethane and methanol are mixed in a volume ratio of 6:1 to form a mixed solvent, and the amount of silver salt added to the mixed solvent is 0.007-0.010 mmol / mL.

[0011] Preferably, the concentration of the sodium borohydride aqueous solution in step S2 is 0.1-0.53 mmol / mL.

[0012] Preferably, in step S2, when collecting the precipitate by centrifugation, the centrifugation speed is 8500-10000 rpm for 40-60 seconds.

[0013] A second objective of this invention is to provide an application of the near-infrared responsive photothermal silver-palladium nanoclusters described in any one of the above-mentioned claims in near-infrared photothermal conversion.

[0014] As a further improvement to the application of the aforementioned photothermal silver-palladium nanoclusters in near-infrared photothermal conversion: Preferably, the near-infrared responsive photothermal silver-palladium nanoclusters are dissolved in N,N-dimethylformamide at a concentration of 0.4 mg / mL to obtain a photothermal silver-palladium nanoclusters solution; the solution is then irradiated with a laser with an output wavelength of 915 nm and a power density of 0.6 W / cm² to test the photothermal conversion efficiency of the solution.

[0015] The advantages of this invention compared to the prior art are as follows: 1) The preparation method of this invention provides a reference for the synthesis technology of photothermal silver-palladium nanoclusters. The preparation method provided by this invention has a simple operation process, mild reaction conditions, no need for calcination, and no complicated process flow. The synthesis is carried out at room temperature and pressure, the operation steps are simple, and the raw materials are readily available. Photothermal silver-palladium nanoclusters with infrared response can be easily and quickly prepared at room temperature using a one-pot method.

[0016] 2) This invention provides a photothermal silver-palladium nanocluster material that not only has an atomically precise structure, but also high photostability and high dispersibility.

[0017] 3) This invention employs the π-conjugated polycyclic aromatic hydrocarbon 4-acetylenebiphenyl as an organic ligand, effectively enhancing the non-covalent interactions between and within clusters. This not only facilitates the acquisition of crystalline products but also significantly modulates the core structure of the clusters, achieving an aspect ratio as high as 6.32. The rod-like cluster core strengthens the localized surface plasmon resonance effect, improving the material's light-harvesting capability in the near-infrared region. UV-Vis absorption spectroscopy shows that this photothermal silver-palladium nanocluster material exhibits two strong and broad characteristic absorption peaks at 730 nm and 885 nm, both located in the near-infrared I region.

[0018] 4) This photothermal silver-palladium nanocluster material benefits from its excellent light-harvesting ability in the near-infrared region, and can be excited by a 915 nm laser at room temperature (0.6 W·cm⁻¹). -2 Under these conditions, its solution photothermal conversion efficiency reaches as high as 73.25%, which is significantly better than most reported traditional photothermal conversion materials, showing good application prospects. Attached Figure Description

[0019] Figure 1 Schematic diagram of the cation host structure of the photothermal silver-palladium nanocluster material prepared in this invention (a) and Ag 20 Schematic diagram of Pd5 metal core structure (b) and unit cell (c).

[0020] Figure 2 High-resolution mass spectra of the photothermal silver-palladium nanocluster material crystal solutions prepared in Examples 1-3 in positive ion mode.

[0021] Figure 3 UV-Vis absorption spectra of the photothermal silver-palladium nanocluster material crystal solutions prepared in Examples 1-3.

[0022] Figure 4 The UV-Vis absorption spectrum of the crude product of the photothermal silver-palladium nanocluster material prepared in Comparative Example 1.

[0023] Figure 5 Ag3 of the photothermal silver-palladium nanoclusters prepared in Examples 1-3 d and Pd 3 d High-resolution XPS fine spectrum of the orbit.

[0024] Figure 6 The curves showing the change in solution temperature over time of the photothermal silver-palladium nanoclusters prepared in Examples 1-3 under 915 nm near-infrared laser irradiation.

[0025] Figure 7 The graph shows the negative natural logarithm of the cooling time versus the driving force temperature for the photothermal silver-palladium nanoclusters prepared in Examples 1-3 under 915 nm laser irradiation.

[0026] Figure 8 The UV-Vis absorption spectra of the photothermal silver-palladium nanocluster material crystal solutions prepared in Examples 1-3 after photothermal performance testing. Detailed Implementation

[0027] 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.

[0028] Example 1

[0029] This embodiment provides a method for preparing photothermal silver-palladium nanoclusters, including the following steps: S1. Dissolve silver hexafluoroantimonate (20 mg, 0.058 mmol) in a mixed solvent of 6 mL dichloromethane and 1 mL methanol, and stir until fully dissolved; add 1,3-bis(diphenylphosphine)propane (23 mg, 0.056 mmol) and palladium acetate (1.20 mg, 0.00534 mmol), then add 4-acetylenebiphenyl (13 mg, 0.073 mmol) and continue stirring for 90 min to obtain a homogeneous mixed solution; S2. Dissolve sodium borohydride (5 mg, 0.132 mmol) in 0.25 mL of water and pour it into the above mixed solution. React at room temperature for 24 h. After the reaction is complete, a suspension is obtained. Add excess n-hexane to the suspension. Centrifuge the suspension at 9000 rpm for 50 seconds. Collect the precipitate and wash and centrifuge it with excess n-hexane. Repeat twice to obtain the crude product. S3. The crude product was dissolved in dichloromethane, and then at room temperature, diethyl ether was diffused into the solution in the gas phase to induce crystal formation. After three days, black crystals were obtained, and photothermal silver palladium nanoclusters with near-infrared response were prepared.

[0030] Example 2

[0031] This embodiment provides a method for preparing photothermal silver-palladium nanoclusters, including the following steps: S1. Dissolve silver hexafluoroantimonate (20 mg, 0.058 mmol) in a mixed solvent of 6 mL dichloromethane and 1 mL methanol, and stir until fully dissolved; add 1,3-bis(diphenylphosphine)propane (22 mg, 0.053 mmol) and palladium acetate (1.20 mg, 0.00534 mmol), then add 4-acetylenebiphenyl (15 mg, 0.084 mmol) and continue stirring for 90 min to obtain a homogeneous mixed solution; S2. Dissolve sodium borohydride (3 mg, 0.079 mmol) in 0.25 mL of water and pour it into the above mixed solution. React at room temperature for 24 h. After the reaction is complete, a suspension is obtained. Add excess n-hexane to the suspension. Centrifuge the suspension at 9000 rpm for 50 seconds. Collect the precipitate and wash and centrifuge it with excess n-hexane. Repeat twice to obtain the crude product. S3. The crude product was dissolved in dichloromethane, and then at room temperature, diethyl ether was diffused into the solution in the gas phase to induce crystal formation. After three days, black crystals were obtained, and photothermal silver palladium nanoclusters with near-infrared response were prepared.

[0032] Example 3

[0033] This embodiment provides a method for preparing photothermal silver-palladium nanoclusters, including the following steps: S1. Dissolve silver hexafluoroantimonate (20 mg, 0.058 mmol) in a mixed solvent consisting of 6 mL dichloromethane and 1 mL methanol, and stir until fully dissolved; add 1,3-bis(diphenylphosphine)propane (20 mg, 0.048 mmol) and palladium acetate (1.20 mg, 0.00534 mmol), then add 4-acetylenebiphenyl (18 mg, 0.101 mmol) and continue stirring for 90 min to obtain a homogeneous mixed solution; S2. Dissolve sodium borohydride (1 mg, 0.026 mmol) in 0.25 mL of water and pour it into the above mixed solution. React at room temperature for 48 h. After the reaction is complete, a suspension is obtained. Add excess n-hexane to the suspension. Centrifuge the suspension at 9000 rpm for 50 seconds. Collect the precipitate and wash and centrifuge it with excess n-hexane. Repeat twice to obtain the crude product. S3. The crude product was dissolved in dichloromethane, and then at room temperature, diethyl ether was diffused into the solution in the gas phase to induce crystal formation. After three days, black crystals were obtained, and photothermal silver palladium nanoclusters with near-infrared response were prepared.

[0034] Comparative Example 1

[0035] S1. Dissolve silver hexafluoroantimonate (20 mg, 0.058 mmol) in a mixed solvent of 6 mL dichloromethane and 1 mL methanol, and stir until fully dissolved; add 1,3-bis(diphenylphosphine)propane (22 mg, 0.053 mmol) and palladium acetate (1.20 mg, 0.00534 mmol), and continue stirring for 90 min to obtain a homogeneous mixed solution; S2. Dissolve sodium borohydride (3 mg, 0.079 mmol) in 0.25 mL of water and pour it into the above mixed solution. React at room temperature for 24 h. After the reaction is complete, a suspension is obtained. Add excess n-hexane to the suspension. Centrifuge the suspension at 9000 rpm for 50 seconds. Collect the precipitate and wash and centrifuge it with excess n-hexane. Repeat twice to obtain the crude product. S3. The crude product was dissolved in dichloromethane, and then at room temperature, diethyl ether was diffused into the solution in the gas phase to induce crystal formation. After three days, no crystal product could be obtained.

[0036] The photothermal silver-palladium nanoclusters of the present invention prepared in Examples 1-3 were further characterized as follows: (1) Determination of crystal structure Under nitrogen protection and a low temperature of 193 K, the crystalline products from Examples 1-3 were selected under a microscope and tested using a single-crystal X-ray diffractometer (Bruker D8 Venture). Ga-Kα rays with λ = 1.34139 Å monochromated by a graphite monochromator were used for diffraction, and diffraction data were collected using the ω-scan method. The single-crystal structure was solved directly using the SHELXL-97 software program, with the least squares method F² used for refinement, and empirical absorption correction using the SADABS program. First, the positions of all non-hydrogen atoms were determined and anisotropic corrections were made. All Ag, Pd, Sb, F, P, Cl, and C atoms were directly identified. The refinement of the hydrogen atom positions in the molecule was obtained using isotropic calculations. Detailed crystal measurement data are shown in Table 1. Figure 1 As shown in cell (c), the results indicate that the precise structure of the resolved photothermal silver-palladium nanoclusters is Ag. 20 Pd5(4-EBP) 18 (DPPP)4(SbF6)2·2CH2Cl2 has a structure consisting of 20 Ag atoms, 5 Pd atoms, 4 DPPP organic ligands, 18 deprotonated 4-acetylene biphenyls, 2 hexafluoroantimonate counterions, and 2 dichloromethane solvent molecules, and belongs to the monoclinic crystal system. Figure 1 (a) Shows cationic Ag in photothermal silver-palladium nanoclusters 20 Pd5(4-EBP) 18 The main structure of (DPPP)4 has a size of approximately 2.6 nm; Figure 1 (b) Further, it is shown that the nanocluster has a rod-like Ag structure. 20 The Pd5 metal core has a length of 18.83 Å, a radial length of 2.98 Å, and an aspect ratio as high as 6.32.

[0037] Table 1 Main crystallographic parameters

[0038] R1=∑||Fo|-|Fc|| / ∑|Fo|. wR2=[∑w(F o 2 -F c 2 ) 2 / ∑w(F o 2 ) 2 ] 1 / 2

[0039] Figure 2The photothermal silver-palladium nanoclusters prepared in Examples 1-3 were dissolved in dichloromethane and subjected to electrospray high-resolution mass spectrometry (Waters Q-TOF) in positive ion mode. The results showed that the silver-palladium nanoclusters had very good monodispersity, with a very strong mass spectrum peak signal at m / z 3765.78 Da. This molecular ion peak corresponds to [Ag] 20 Pd5(4-EBP) 18 (DPPP)4] 2+ This indicates that the main structure of the nanocluster exists primarily in the form of +2 valent cations.

[0040] Figure 3 The UV-Vis absorption spectra of the photothermal silver-palladium nanocluster crystals prepared in Examples 1-3 dissolved in dichloromethane (instrument model: Yuanxi UV8000) show that the photothermal silver-palladium nanocluster material has strong absorption in the near-infrared region, exhibiting two strong and broad characteristic absorption peaks at 730 nm and 885 nm, respectively.

[0041] Figure 4 The image shows the UV-Vis absorption spectrum of the crude product obtained in Comparative Example 1 without the addition of 4-acetylene biphenyl. The results show that in the absence of 4-acetylene biphenyl, the crude product cannot crystallize and has no characteristic absorption peak in the near-infrared region, indicating that the π-conjugated polycyclic aromatic hydrocarbon 4-acetylene biphenyl organic ligand is an indispensable key component for preparing photothermal silver-palladium nanoclusters with near-infrared response.

[0042] Figure 5 X-ray photoelectron spectroscopy (XPS) of the photothermal silver-palladium nanoclusters prepared in Examples 1-3 was performed using an ESCALAB 250 Xi XPS system provided by Thermo Scientific. The fine XPS spectra confirmed the presence of Ag and Pd elements in the photothermal silver-palladium nanoclusters.

[0043] (2) Photothermal conversion experiment of the photothermal silver-palladium nanocluster material of the present invention

[0044] Photothermal conversion of photothermal silver-palladium nanoclusters under 915 nm laser irradiation: The photothermal silver-palladium nanoclusters prepared in Examples 1-3 were dissolved in 0.6 mL of DMF (N,N-dimethylformamide) to prepare a 0.4 mg / mL DMF solution of photothermal silver-palladium nanoclusters. The solution was placed in a 1.5 mL transparent EP centrifuge tube. A continuous laser with an output wavelength of 915 nm and a power density of 0.6 W / cm² was used as the light source, and the solution was vertically irradiated to the center. The temperature change in the central region of the solution was recorded and monitored in real time using an infrared thermal imager (model Guide Sensing PS400) for 6.5 min. The temperature change is as follows. Figure 6As shown. The photothermal conversion efficiency (η) was calculated according to the standard method: the absorbance of the solution at 915 nm was 0.59, the maximum temperature difference between the solution and the ambient temperature was 61℃, the specific heat capacity of the solvent DMF was 2.14 kJ / (kg·℃), the density of the solvent DMF was 0.948 g / cm³, and the thermal conductivity time constant (τ) was... s The value is 173.04 s. Figure 7 The system's heat loss Q s The J is 0.116. The calculated photothermal conversion efficiency (η) is 73.25%. Figure 8 After photothermal testing, the UV-Vis characteristic absorption peaks of the silver-palladium nanoclusters remained consistent with those before testing, indicating that the clusters possess excellent photostability. These test results directly demonstrate that the photothermal silver-palladium nanoclusters prepared according to this invention exhibit excellent photostability at 915 nm and 0.6 W / cm². 2 Under near-infrared light irradiation, it exhibits extremely excellent photothermal conversion capabilities, significantly outperforming most reported traditional photothermal conversion materials, and shows promising application prospects.

[0045] 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 near-infrared responsive photothermal silver-palladium nanocluster material, characterized in that, The chemical formula of the photothermal silver-palladium nanocluster material is C. 362 H 270 Ag 20 Cl4F 12 P8Pd5Sb2, abbreviated as Ag 20 Pd5(4-EBP) 18 (DPPP)4(SbF6)2·2CH2Cl2 belongs to the monoclinic crystal system; space group P21 / n. a =16.228(13) Å, b =40.670(3) Å, c =25.941(2) Å, α =90°, β =100.283(2)°, γ =90°, V=16846(2) Å 3 The molecular weight is 8170.22 Da; DPPP is 1,3-bis(diphenylphosphine)propane, and 4-EBP is deprotonated 4-acetylene biphenyl. The structural formula is shown in the figure below: 。 2. The near-infrared responsive photothermal silver-palladium nanoclusters according to claim 1, characterized in that, The structure of the photothermal silver-palladium nanocluster material consists of 20 Ag atoms, 5 Pd atoms, 4 DPPP organic ligands, 18 deprotonated 4-acetylene biphenyls, 2 hexafluoroantimonate counterions, and 2 dichloromethane solvent molecules.

3. A method for preparing the near-infrared responsive photothermal silver-palladium nanoclusters as described in claim 1 or 2, characterized in that, Includes the following steps: S1. Add silver salt to a mixed solvent of dichloromethane and methanol, stir to dissolve it completely, then add 1,3-bis(diphenylphosphine)propane, palladium salt and 4-acetylene biphenyl, and continue stirring to obtain a homogeneous mixed solution. S2. Add sodium borohydride aqueous solution to the mixed solution and react at room temperature for 24-48 h to obtain a suspension; add excess n-hexane to the suspension, centrifuge to collect the precipitate, and wash and centrifuge again with excess n-hexane to obtain the crude product; S3. Dissolve the crude product in dichloromethane, and at room temperature, diffuse diethyl ether into the solution in the gas phase to induce crystal formation. Collect the crystal product, air dry it naturally, and obtain a photothermal silver-palladium nanocluster material with near-infrared response.

4. The method for preparing the near-infrared responsive photothermal silver-palladium nanoclusters according to claim 3, characterized in that, The molar ratio of sodium borohydride in the aqueous solutions of silver salt, palladium salt, 1,3-bis(diphenylphosphine)propane, 4-acetylene biphenyl and sodium borohydride is 1:0.092:(0.8-1):(1.2-1.8):(0.4-2.3).

5. The method for preparing the near-infrared responsive photothermal silver-palladium nanoclusters according to claim 3 or 4, characterized in that, The silver salt mentioned in step S1 is silver hexafluoroantimonate, and the palladium salt is palladium acetate.

6. The method for preparing the near-infrared responsive photothermal silver-palladium nanoclusters according to claim 3, characterized in that, In step S1, dichloromethane and methanol are mixed in a volume ratio of 6:1 to form a mixed solvent, and the amount of silver salt added to the mixed solvent is 0.007-0.010 mmol / mL.

7. The method for preparing the near-infrared responsive photothermal silver-palladium nanoclusters according to claim 3, characterized in that, The concentration of the sodium borohydride aqueous solution in step S2 is 0.1-0.53 mmol / mL.

8. The method for preparing the near-infrared responsive photothermal silver-palladium nanoclusters according to claim 3, characterized in that, In step S2, when collecting the precipitate by centrifugation, the centrifuge speed is 8500-10000 rpm for 40-60 seconds.

9. The application of the near-infrared responsive photothermal silver-palladium nanoclusters as described in claim 1 or 2 in near-infrared photothermal conversion.

10. The application of the near-infrared responsive photothermal silver-palladium nanoclusters according to claim 9 in near-infrared photothermal conversion, characterized in that, Near-infrared responsive photothermal silver-palladium nanoclusters were dissolved in N,N-dimethylformamide at a concentration of 0.4 mg / mL to obtain a photothermal silver-palladium nanoclusters solution. The solution was then irradiated with a laser with an output wavelength of 915 nm and a power density of 0.6 W / cm² to test its photothermal conversion efficiency.

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