Silver cluster metal nanomaterial, preparation method and application thereof

Abstract

The present invention provides a novel metal nanomaterial, specifically a silver cluster metal nanomaterial, a preparation method, and its application. Over a wide temperature range, there is a one-to-one correspondence between the emission intensity at 545 nm and the emission intensity at 505 nm. This property demonstrates the material's superior ratiometric fluorescence thermometry performance. The silver cluster metal nanomaterial can be used as a nanofluorescence thermometer and has great application potential in high-tech fields such as biomedicine (such as cell metabolism, pathology, medical imaging, and drug delivery) and electronic component manufacturing.

Description

Technical Field

[0001] The invention relates to a silver cluster metal nano material, a preparation method and application thereof, and belongs to the field of metal nano materials. Background Art

[0002] Temperature is one of nature's most fundamental parameters. Reliable, fast, and accurate temperature measurement is essential in numerous fields. A variety of temperature measurement tools have been developed to meet diverse needs in production and daily life, based on principles such as volume change (e.g., mercury thermometers), mechanical displacement (e.g., bimetallic thermometers), potential difference (e.g., thermocouples), electrical conductivity (e.g., thermistors), and infrared radiation (e.g., thermal imaging thermometers).

[0003] Fluorescence thermometry is an emerging temperature measurement method that determines temperature by detecting the fluorescence signal from thermosensitive fluorescent materials. Compared to traditional thermometers, fluorescence thermometry offers advantages such as remote temperature measurement, high sensitivity, submicrometer-scale resolution, rapid response, and non-contact temperature measurement. Fluorescence thermometry holds significant advantages in measuring the temperature of microscopic objects, such as those in biomedicine, biosensing, and nanoscale devices. The core of fluorescence thermometry lies in thermoluminescent color-changing materials. When the temperature changes, the internal electronic structure or molecular configuration of these materials changes, resulting in a change in the fluorescence signal. Optical indicators for detecting thermoluminescent color changes include fluorescence emission position, lifetime, and intensity. Emission intensity, which can be quickly and accurately measured through photon counting, has therefore been widely studied.

[0004] Silver nanoclusters, a class of metallic nanomaterials, are ultra-small materials composed of a few to several hundred silver atoms, typically ranging in size from 1 to 10 nanometers. The metallic interactions within their cores, as well as the vibrational and rotational behavior of their protective ligands, are highly susceptible to temperature fluctuations. These subtle structural changes significantly influence their photophysical properties, often causing silver clusters to exhibit thermoluminescence color changes. Therefore, silver nanoclusters are considered an ideal fluorescent thermometric material.

[0005] Although some studies have reported silver clusters with thermochromic properties, and the fluorescence intensity of some silver clusters shows a good dependence on temperature changes, the number of such materials is still limited. In particular, reports on silver nanoclusters with dual or multiple emission properties and the potential for ratiometric fluorescence thermometry are relatively scarce. Summary of the Invention

[0006] The present invention aims to provide a new type of metal nanomaterial, which can be applied to nanofluorescence thermometers and has good application prospects in high-tech fields such as biomedicine (such as cell metabolism, pathology, medical imaging and drug delivery, etc.) and electronic component manufacturing.

[0007] The first object of the present invention is to provide a silver cluster metal nanomaterial, the molecular formula of which is Ag 26 (H2decz)2(Hdecz)8(PhCOO)8(P(PhF)3)6;

[0008] The "H2decz" is The "Hdecz" is The PhCOO is benzoate The P(PhF)3 is tri(4-fluorophenyl)phosphine

[0009] According to the preferred embodiment of the present invention, the silver cluster metal nanomaterial can be prepared by the following method:

[0010] (1) Silver acetylene precursor: Under alkaline conditions, silver (I) salt and 3,6-di-tert-butyl-1,8-diethyl-9H-carbazole undergo polymerization reaction in a solvent to generate silver acetylene precursor;

[0011] (2) dissolving the silver acetylene precursor, silver (I) benzoate and tri(4-fluorophenyl)phosphine in a solvent, and preparing the metal nanomaterial through a self-assembly reaction;

[0012] Wherein, the structural formula of the 3,6-di-tert-butyl-1,8-diethyl-9H-carbazole is

[0013] According to the present invention, preferably, in step (1), the silver (I) salt can be one or a combination of more than one of Ag2O, AgNO3, AgF, AgCl, AgBr, AgI, CF3SO3Ag, AgClO4, AgBF4, AgPF6 or AgSbF6.

[0014] Preferably, according to the present invention, in step (1), the solvent may be one or a combination of more than one of water, chloroform, dichloromethane, acetonitrile, ethanol or methanol.

[0015] According to the present invention, preferably, in step (1), the base can be one or a combination of more than one of ammonia water, triethylamine, sodium hydroxide, potassium hydroxide, sodium hydride or calcium hydride, sodium methoxide, sodium ethoxide, n-butyl lithium, tert-butyl lithium, tetramethylethylenediamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

[0016] According to the preferred embodiment of the present invention, in step (1), the molar ratio of the silver (I) salt to the 3,6-di-tert-butyl-1,8-diethyl-9H-carbazole is 2-2.5:1.

[0017] According to the preferred embodiment of the present invention, in step (2), the solvent may be one or a combination of more than one of dichloromethane, chloroform, acetonitrile, 1,2-dichloroethane, dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0018] According to the preferred embodiment of the present invention, in step (2), the reaction ratio of the acetylenic silver precursor, silver (I) benzoate and tri(4-fluorophenyl)phosphine is 9-11:7-9:5-7, and the optimal reaction molar ratio is 10:8:6.

[0019] According to the preferred embodiment of the present invention, in step (2), the reaction conditions can be either room temperature stirring or low temperature solvent heating.

[0020] The second object of the invention is to provide a crystal form of a silver cluster metal nanomaterial, wherein the unit cell parameters of the crystal form are: α(deg)=99.088(3); β(deg)=95.676(2); γ(deg)=117.691(2).

[0021] A third object of the invention is to provide a method for preparing a metal nanomaterial, which may be the method for preparing the metal nanomaterial described herein.

[0022] A fourth object of the invention is to provide an application of the above-mentioned silver cluster metal nanomaterial in a ratiometric fluorescence thermometer.

[0023] Without violating the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0024] Unless otherwise specified, the reagents and raw materials used in the present invention are commercially available.

[0025] The technical features and beneficial effects of the present invention are as follows:

[0026] 1. The synthesis method of the silver cluster metal nanomaterials described in the present invention is simple and mild, and the product can be easily purified by volatilization or diffusion treatment. This synthesis method not only reduces environmental impact but also improves production efficiency and has significant economic benefits.

[0027] 2. The silver cluster metal nanomaterials described in the present invention have an atomically precise structure and, combined with theoretical calculations, can conduct in-depth structure-activity relationship research.

[0028] 3. The silver cluster metal nanomaterials described in the present invention demonstrate promising potential for fluorescence thermometry. Under 365nm excitation, the four maximum emission peaks in their solid-state temperature curve—at 605nm, 640nm, 505nm, and 545nm—all exhibit significant temperature dependence. The emission intensities at 545nm, 605nm, and 640nm exhibit a good linear response to temperature, while at 505nm, the emission intensity exhibits a significant exponential response to temperature.

[0029] 4. The silver cluster metal nanomaterials described in the present invention have excellent potential for ratiometric fluorescence thermometry. At low temperatures, the silver cluster metal nanomaterials transition from single emission to triple emission. Simultaneously, their maximum emission peak red-shifts from 605nm to 640nm, while two new emission peaks appear at 505nm and 545nm. Between 30°C and -190°C, the ratio of the emission intensity at 545nm to the emission intensity at 505nm corresponds one-to-one with temperature. This ratiometric thermometry property can greatly enhance the sensitivity and accuracy of temperature measurements. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A single crystal structure of a silver cluster metal nanomaterial. For simplicity, hydrogen atoms and the tert-butyl group on 3,6-di-tert-butyl-1,8-diethyl-9H-carbazole are omitted.

[0031] Figure 2 This is the UV-visible absorption curve of silver cluster metal nanomaterials in dichloromethane solution.

[0032] Figure 3 is the excitation of silver cluster metal nanomaterials in the solid state (λ em = 605 nm, dotted line) and emission (λ ex =365nm, solid line) curve.

[0033] Figure 4 is the maximum emission peak of silver cluster metal nanomaterials in the solid state (λ max =605nm) life decay curve.

[0034] Figure 5 This is the temperature-dependent fluorescence curve of silver cluster metal nanomaterials in the solid state, with an excitation wavelength of 365nm.

[0035] Figure 6 These are the curves of the emission intensity of solid-state silver cluster metal nanomaterials at different emission wavelengths changing with temperature under 365nm ultraviolet light excitation; (A) the response curve of emission intensity and temperature at 640nm; (B) the response curve of emission intensity and temperature at 605nm; (C) the response curve of emission intensity and temperature at 545nm; (D) the response curve of emission intensity and temperature at 505nm.

[0036] Figure 7 This is the response curve of the ratio of the emission intensity at 545nm to the emission intensity at 505nm of the solid-state silver cluster metal nanomaterial under 365nm ultraviolet light excitation and temperature. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and technical effect of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and examples; however, the present invention is not limited to the embodiments described. Experimental methods in the following examples without specifying specific conditions may be selected according to conventional methods and conditions, or according to product specifications.

[0038] The 3,6-di-tert-butyl-1,8-diethyl-9H-carbazole involved in the present invention was prepared according to Dalton Trans. 2017, 46, 4696-4710, and other reagents and solvents were commercially available.

[0039] Example 1: Synthesis method of silver cluster metal nanomaterials in the present invention

[0040] (1) Weigh 1 equivalent of Ag2O and add it to 25% ammonia water. Stir until it becomes clear to obtain a silver ammonia solution. Dissolve 1 equivalent of 3,6-di-tert-butyl-1,8-diethyl-9H-carbazole in 1,4-dioxane and add it dropwise to the silver ammonia solution under vigorous stirring. The reaction quickly generates a red precipitate. Stirring is continued for 6 hours. Filter, wash with water three times, and vacuum dry to obtain a deep red silver acetylene precursor with a yield of 82.7%.

[0041] (2) 10 equivalents of silver acetylene precursor, 8 equivalents of silver (I) benzoate, and 6 equivalents of tri(4-fluorophenyl)phosphine were dissolved in dichloromethane and stirred at room temperature for 12 h to obtain a deep red solution. The mother liquor was transferred to a test tube, overlaid with 3 volumes of n-hexane for interfacial diffusion, and sealed and allowed to stand for 5 days to obtain red bulk silver cluster metal nanomaterial crystals with a crystal yield of 73.5%.

[0042] Example 2: Synthesis method of silver cluster metal nanomaterials in the present invention

[0043] (1) Weigh 2 equivalents of AgNO3, dissolve it in water, and add 25% ammonia water dropwise. A gray precipitate is first generated in the system, which then slowly dissolves. Stop adding the solution when the system becomes clear again to obtain a silver ammonia solution. Dissolve 1 equivalent of 3,6-di-tert-butyl-1,8-diethyl-9H-carbazole in 1,4-dioxane and add it dropwise to the silver ammonia solution under vigorous stirring. The reaction quickly generates a red precipitate and continues stirring for 6 hours. Filter, wash with water 3 times, and vacuum dry to obtain a red silver acetylene precursor with a yield of 83.5%.

[0044] (2) 10 equivalents of silver acetylene precursor, 8 equivalents of silver (I) benzoate, and 6 equivalents of tri(4-fluorophenyl)phosphine were dissolved in chloroform and stirred at room temperature for 12 h to obtain a deep red solution. The reaction mother liquor was allowed to evaporate in the dark for one week to obtain red flaky silver cluster metal nanomaterial crystals with a crystal yield of 76.2%.

[0045] Example 3: Synthesis method of silver cluster metal nanomaterials in the present invention

[0046] (1) 2 equivalents of AgNO3 were weighed and added to a methanol solution containing 1 equivalent of 3,6-di-tert-butyl-1,8-diethyl-9H-carbazole. 10 equivalents of triethylamine were added dropwise with vigorous stirring. The reaction rapidly produced a large amount of red precipitate. Stirring was continued for 6 hours until all the white silver nitrate crystals disappeared. The mixture was then filtered, washed three times with methanol, and the methanol was removed under vacuum to obtain a red silver acetylene precursor with a yield of 70.6%.

[0047] (2) 10 equivalents of silver acetylene precursor, 8 equivalents of silver (I) benzoate, and 6 equivalents of tri(4-fluorophenyl)phosphine were dissolved in N,N-dimethylacetamide and stirred at room temperature for 12 h to obtain a deep red solution. The mother liquor was transferred to a test tube, covered with 3 volumes of diethyl ether for interfacial diffusion, sealed, and allowed to stand for 7 days to obtain red bulk silver cluster metal nanomaterial crystals with a crystal yield of 40.5%.

[0048] Example 4: Synthesis method of silver cluster metal nanomaterials in the present invention

[0049] (1) Weigh 2 equivalents of AgSO3CF3 and 1 equivalent of 3,6-di-tert-butyl-1,8-diethyl-9H-carbazole, add dichloromethane, and sonicate to dissolve all reactants. Add 10 equivalents of triethylamine dropwise to the system, and the reaction solution changes from light yellow to dark red. Continue stirring for 6 hours. Remove all dichloromethane and excess triethylamine. Wash with methanol three times, filter, and vacuum-drain the methanol to obtain a red silver acetylene precursor with a yield of 77.8%.

[0050] (2) 10 equivalents of silver acetylene precursor, 8 equivalents of silver (I) benzoate, and 6 equivalents of tri(4-fluorophenyl)phosphine were dissolved in dichloromethane and stirred at room temperature for 12 h to obtain a deep red solution. The mother liquor was transferred to a test tube, topped with 3 volumes of n-hexane for interfacial diffusion, and sealed and allowed to stand for 5 days to obtain red bulk silver cluster metal nanomaterial crystals with a crystal yield of 34.5%.

[0051] Example 5: Synthesis method of silver cluster metal nanomaterials in the present invention

[0052] (1) Weigh 1 equivalent of 3,6-di-tert-butyl-1,8-diethyl-9H-carbazole and 2 equivalents of sodium hydroxide, add methanol, and sonicate until the sodium hydroxide is completely dissolved. Next, add 2 equivalents of AgBF4, which quickly produces a large amount of red precipitate. Stir for 6 hours. Filter, wash with methanol three times, and vacuum-drain the methanol to obtain a red silver acetylene precursor with a yield of 80.1%.

[0053] (2) 10 equivalents of silver acetylene precursor, 8 equivalents of silver (I) benzoate, and 6 equivalents of tri(4-fluorophenyl)phosphine were dissolved in dichloromethane and stirred at room temperature for 12 h to obtain a deep red solution. The mother liquor was transferred to a test tube, topped with 3 volumes of n-hexane for interfacial diffusion, and sealed and allowed to stand for 5 days to obtain red bulk silver cluster metal nanomaterial crystals with a crystal yield of 10.0%.

[0054] Example 6: Structural Characterization

[0055] The crystal obtained in Example 1 was used as an example for single crystal structure characterization. The X-ray single crystal diffraction data of the crystal were collected on a Bruker DiffractometerMD2 diffractometer at the BL17B beamline of the National Center for Protein Science (NCPSS) in Shanghai. The data were processed using the BrukerAPEX4 program. The light source wavelength is The test temperature is 273K. The crystal is triclinic Space group. The molecular formula is C 404 H 344 Ag 26 F 18 N 10 O 16 P6. Other relevant data are shown in Table 1:

[0056] Table 1

[0057]

[0058] like Figure 1 As shown in Figure 2, X-ray single crystal diffraction experiments show that the core of the nanocluster is composed of 26 silver atoms. 26 Ten 3,6-di-tert-butyl-1,8-diethyl-9H-carbazole ligands, eight benzoate ligands, and six tris(4-fluorophenyl)phosphine ligands are distributed on the cluster. Two of the 3,6-di-tert-butyl-1,8-diethyl-9H-carbazole ligands remove a hydrogen atom from the ethynyl group and act as monodentate ligands to coordinate with the silver atom, with a coordination mode of μ3-η. 2 :η 1 :η 1 The remaining eight 3,6-di-tert-butyl-1,8-diethyl-9H-carbazole ligands remove the hydrogen atoms on the two alkynyl groups and coordinate with the silver atom as bidentate ligands. There are three coordination modes: ①μ3-η 1 :η 1 :η 1 ,μ2-η 1 :η 1 ②μ2-η 2 :η 1 ,μ1-η 1 ③μ3-η 1 :η 1 :η 1 ,μ3-η 1 :η 1 :η 1 Benzoate groups are bound to silver atoms by bidentate coordination. According to different coordination modes, these benzoate groups can be divided into two groups: one group has four benzoate groups coordinated with three silver atoms. The other group of four benzoate groups coordinates with two silver atoms. The tri(4-fluorophenyl)phosphine (P(PhF)3) ligand coordinates to a silver atom through an Ag-P bond, further stabilizing the cluster structure.

[0059] Example 7: Photophysical testing

[0060] The UV-Vis absorption spectrum of the material was measured on a Perkin-Elmer Lambda 365 UV-Vis spectrophotometer. The silver cluster metal nanomaterial exhibited four main UV absorption peaks in dichloromethane solution, which were located at 300 nm, 310 nm, 362 nm and 395 nm ( Figure 2 ).

[0061] The excitation and emission spectra and emission lifetime of the material were characterized by Edinburgh Analytical Instruments (FLS920 fluorescence spectrometer). In solution, the silver cluster metal nanomaterial is almost non-luminescent, but in powder form it can emit orange-red light. At room temperature, the maximum emission peak of its solid powder is located at 605nm ( Figure 3 ), the emission lifetime is 57.7ns( Figure 4 ). Temperature-variable fluorescence experiments show that Ag 26 It has good thermoluminescence color change properties in the solid state. When the temperature drops from 30℃ to -190℃, the silver cluster metal nanomaterial changes from single emission to triple emission. Its maximum emission peak red-shifts from 605nm to 640nm, and two new emission peaks appear at 505nm and 545nm ( Figure 5These emission peaks show obvious temperature dependence. The emission intensities at 640nm, 605nm and 545nm show a good linear response relationship with temperature ( Figure 6 At 505 nm, the emission intensity shows a significant exponential response relationship with temperature ( Figure 6 In addition, the silver cluster metal nanomaterial also exhibits ratiometric fluorescence thermometry potential. Between 30°C and -190°C, there is a clear correspondence between the ratio of the emission intensity at 545nm to the emission intensity at 505nm and the temperature ( Figure 7 ).

Claims

1. A silver cluster metal nanomaterial, characterized in that: The molecular formula of the metal nanomaterial is Ag 26 (H2decz)2(Hdecz)8(PhCOO)8(P(PhF)3)6; Wherein, the "H2decz" is ; The "Hdecz" is ; The PhCOO is benzoate ; The P(PhF)3 is tri(4-fluorophenyl)phosphine .

2. The silver cluster metal nanomaterial according to claim 1, characterized in that The metal nanomaterial is prepared by the following method: (1) Under alkaline conditions, silver (I) salt and 3, 6-di-tert-butyl-1, 8-diethyl-9H-carbazole undergo polymerization in a solvent to generate an acetylene silver precursor; (2) dissolving the silver acetylene precursor, silver (I) benzoate and tri(4-fluorophenyl)phosphine in a solvent, and preparing the metal nanomaterial through a self-assembly reaction; Wherein, the structural formula of the 3,6-di-tert-butyl-1,8-diethyl-9H-carbazole is .

3. The silver cluster metal nanomaterial according to claim 2, characterized in that In step (1), the silver (I) salt is one or a combination of more than one of AgNO3, AgF, AgCl, AgBr, AgI, CF3SO3Ag, AgClO4, AgBF4, AgPF6 or AgSbF6.

4. The silver cluster metal nanomaterial according to claim 2, characterized in that In step (1), the solvent is one or a combination of more than one of water, chloroform, dichloromethane, acetonitrile, ethanol or methanol.

5. The silver cluster metal nanomaterial according to claim 2, characterized in that In step (1), the base is one or a combination of more than one of ammonia water, triethylamine, sodium hydroxide, potassium hydroxide, sodium hydride or calcium hydride, sodium methoxide, sodium ethoxide, n-butyl lithium, tert-butyl lithium, tetramethylethylenediamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

6. The silver cluster metal nanomaterial according to claim 2, characterized in that In step (1), the molar ratio of the silver (I) salt to the 3, 6-di-tert-butyl-1, 8-diethyl-9H-carbazole is 2-2.5:

1.

7. The silver cluster metal nanomaterial according to claim 2, characterized in that In step (2), the solvent is one or a combination of dichloromethane, chloroform, acetonitrile, 1,2-dichloroethane, dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide.

8. The silver cluster metal nanomaterial according to claim 2, characterized in that In step (2), the reaction molar ratio of the acetylenic silver precursor, silver (I) benzoate and tri(4-fluorophenyl)phosphine is 9-11: 7-9: 5-7.

9. The silver cluster metal nanomaterial according to claim 8, characterized in that In step (2), the reaction molar ratio of the acetylenic silver precursor, silver (I) benzoate and tri(4-fluorophenyl)phosphine is 10:8:

6.

10. A crystal form of the silver cluster metal nanomaterial according to any one of claims 1 to 9, characterized in that: The unit cell parameters are a (Å)=20.7946(18); b (Å)=22.3400(18); c (Å)=23.341(2); α (deg)=99.088(3); β (deg)=95.676(2); γ (deg)=117.691(2).

11. Use of the silver cluster metal nanomaterial according to any one of claims 1 to 9 in a ratiometric fluorescence thermometer.

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