Application of a metallofullerene electron spin probe in measuring phase transition of materials

Abstract

The application discloses application of a metal fullerene electron spin probe in measurement of material phase transition, wherein the metal fullerene is paramagnetic metal fullerene; the paramagnetic metal fullerene is at least one of La@C 82 , Y@C 82 , Sc@C 82 , Sc3C2@C 80 , Y2@C 79 N or a combination thereof. The application is based on high sensitivity of electron spin of the metal fullerene, the metal fullerene is added into the material, the high-efficiency regulation of spin state in the metal fullerene is utilized according to state change in the material phase transition, and the electron paramagnetic resonance signal is utilized to reflect the material phase transition process; the electron spin probe can improve the accuracy and sensitivity of the phase transition measurement, and in-situ measurement of the material deep phase transition can be realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of application of fullerene materials, and particularly relates to application of a metal fullerene electron spin probe in measurement of material phase transition. BACKGROUND

[0002] A homogeneous part in a material system with the same physical and chemical properties and a clear boundary with other parts is called a phase. The mutual transformation between different phases is called "phase transition" or "state change". Most of the various substances in nature exist in three aggregation states of solid, liquid and gas. In order to describe different aggregation states of substances, "phase" is used to represent the "phase appearance" of the three forms of solid, liquid and gas of substances. Phase transition is a very common physical process, which is widely involved in production and scientific and technological work. In the conversion process of the form of matter, heat is necessarily absorbed or released. The main difference between the three states of matter is the distance between molecules, the size of the intermolecular force and the way of thermal motion. Therefore, under appropriate conditions, matter can change from one state to another. Phase transition is the result of the competition between order and disorder, in which interaction is the cause of order and thermal motion is the source of disorder. Phase transition phenomenon is widely existing, and various phase transition processes are involved in the fields of material science, thermodynamic engineering, metallurgical engineering, chemical industry and the like. Phase change materials can be regarded as energy storage, and this characteristic has great significance in the fields of energy saving and temperature control.

[0003] In addition to traditional phase change materials, more and more new phase change materials have been developed. For example, light-responsive materials refer to materials that can undergo intermolecular or intramolecular chemical or physical changes after absorbing light of a certain wavelength. With the change at the molecular level, the macroscopic properties of the material will also change, such as shape, solid-liquid state, color, and refractive index. Among them, azobenzene is a typical organic compound with two isomers, in which the cis isomer gradually changes to the trans form under ultraviolet light of 320-380 nm wavelength; under visible light of 420-480 nm wavelength, it also changes from cis to trans structure. This isomerization process is reversible, and this change can be directly used for optical switching, and can be further amplified to the light response of the properties of the material. The change of the two isomers will cause the change of their macroscopic physical properties, such as aggregation state, so azobenzene compounds play an important role in the development and application of smart materials. In 2001, a research team first developed a liquid crystal elastomer based on azobenzene groups, which is a new material that has order and elasticity to respond to external stimuli. In 2003, Japanese scientists reported a liquid crystal elastomer film based on azobenzene-containing polyacrylate, and the azobenzene groups on the surface of the film have strong response to ultraviolet light, so the surface layer of the film shrinks under ultraviolet light, and the film bends towards the incident light direction. More researchers made the film into a transmission track and irradiated the two sides of the track with ultraviolet light and visible light, respectively, to make the track rotate. It can be seen that azobenzene materials also have important applications in micro-motors. A research team studied liquid crystal polymer materials of azobenzene-containing stilbazole that can respond to a wider spectrum range. The material uses a longer conjugated system to expand the response range in the visible light region, and on this basis, a micro-robot similar to a finger, wrist, and arm can be made from this material to realize the conversion from light energy to mechanical energy. For the design of light-responsive materials, reversibility and recyclability of the material are important parameters, so azobenzene compounds are the most widely used reversible light-induced isomerization molecules with important application value. Light response has controllability in time and space, selectivity, non-invasiveness, and remote energy transfer.

[0004] Phase change process measurement is an important characterization method for phase change materials. The commonly used methods include variable temperature X-ray diffraction, thermal analysis, and optical power analysis. These methods require a large amount of sample, which cannot meet the phase change measurement of some micro samples.

[0005] EPR (Electron Paramagnetic Resonance) is a method for studying magnetic substances containing one or more unpaired electrons, which provides information at the microscopic scale of electrons, orbits, atomic nuclei, etc. The EPR signal of a system is determined by its internal structure, which in turn determines the application of such substances in information science, life science, etc. The EPR signal is also closely related to the motion of the molecule and the microenvironment, for example, EPR technology is widely used in biomolecular structure probes. Electron paramagnetic resonance spectroscopy has the advantages of high sensitivity and small sample size. Therefore, EPR technology is an important research method in the fields of materials, biology, environment, etc.

[0006] Paramagnetic metallofullerenes have stable unpaired single electrons. Typical paramagnetic metallofullerenes include La@C 82 , Y@C 82 , Sc@C 82 , Sc3C2@C 80 , Y2@C 79 N, etc. The unpaired single electron in these metallofullerenes is coupled with the metal nucleus to produce multiple clear EPR lines. Since these metallofullerenes were discovered, scientists have carried out basic research on their electron spins, and have controlled the electron spin and molecular paramagnetic properties through chemical and physical methods. For example, paramagnetic azametallofullerene Y2@C 79 N is a carbon cage formed by replacing one carbon atom on the C80 carbon cage with a nitrogen atom to form a defect, which forms a sharp electron spin. The paramagnetic azametallofullerene has important application potential in quantum computing, information storage, etc. According to reports, the nitrogen atom is close to the [6,6,5] ring segment on the equator of the fullerene carbon cage, and the EPR spectrum of the odd electron Y2@C 79 N indicates that the spin electron density is mainly located on the two equivalent Y ions. Since the carbon cage protects the spin located on Y2, it is very stable in the atmospheric environment. Thus, the stable azametallofullerene with sensitive paramagnetic properties is a very potential spin probe material.

[0007] Paramagnetic metallofullerenes have unique electron paramagnetic resonance characteristics, and have broad application prospects in the fields of sensor devices, quantum sensing, micro-nano detectors, etc. The electron spin probe based on metallofullerenes will improve the accuracy and sensitivity of phase change measurement. The spin probe is used in small amounts, and can realize the measurement of trace samples. The spin probe is embedded in the material, and can realize in-situ measurement of the deep part of the material, which is also impossible by traditional methods. SUMMARY

[0008] The application provides application of a metal fullerene electron spin probe in measurement of phase transition of a material, wherein the metal fullerene is a paramagnetic metal fullerene.

[0009] According to the application, the paramagnetic metal fullerene can be at least one of La@C 82 , Y@C 82 , Sc@C 82 , Sc3C2@C 80 , Y2@C 79 N or a combination thereof.

[0010] According to the application, the mass concentration of the paramagnetic metal fullerene in the material can be 0.1%-5%; for example, it can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%.

[0011] According to the application, the material can be an aromatic compound, wherein the aromatic compound contains at least one of the following substructures in a molecule: benzene, toluene, xylene, mesitylene, chlorobenzene, dichlorobenzene, trichlorobenzene, naphthalene, methylnaphthalene, chloronaphthalene, bromonaphthalene, anthracene, methylanthracene, chloranthracene, bromanthracene, dibromanthracene, phenanthrene, benzophenanthrene, azulene, perylene, indole, quinoline, fluorene, etc. The aromatic compound undergoes phase transition under variable temperature conditions, such as solid-liquid transition, transition of molecules from disorder to order, change of intermolecular distance, change of intermolecular interaction force, change of molecular thermal motion, etc.; preferably, the phase transition point temperature of the material is 77K-573K. The phase transition point temperature refers to the temperature at which the three states of solid, liquid and gas are converted into each other, such as the critical temperature of solid-liquid transition, the critical temperature of gas-solid transition, the critical temperature of liquid-gas transition, etc.

[0012] According to the application, the material can be an azobenzene compound; for example, it can be at least one of 4,4'-bis(hexyloxy)-3-methylazobenzene, 4,4'-bis(decyloxy)-3-methylazobenzene, 4-[bis(9,9-dimethylfluoren-2-yl)amino]azobenzene, 4,4'-bis(dodecyloxy)-3-methylazobenzene. After the material absorbs light, it can undergo photoisomerization of cis-trans isomerization, so that the intermolecular interaction changes and phase transition occurs. Preferably, the wavelength of light for the photoisomerization of trans-azobenzene compound to cis-azobenzene compound is 320-380nm, preferably 365nm, and the wavelength of light for the photoisomerization of cis-azobenzene compound to trans-azobenzene compound is 420-480nm, preferably 460nm. As an example, the power of light in this process can be 5-10watts, the irradiation distance can be 1-5cm, and the irradiation time can be 1-30min.

[0013] In a preferred embodiment of the present application, the material is capable of dissolving or dispersing metallofullerenes. The dissolving or dispersing method includes direct mixing method and adding a cosolvent mixing method, and if the metallofullerenes are uniformly dispersed in the material in a single molecule form, the electron spin energy can be more directly, more sensitively and more quickly perceived to the phase change of the material.

[0014] Exemplarily, the material is 1-chloronaphthalene or 4,4'-bis(hexyloxy)-3-methylazobenzene; and the paramagnetic metallofullerene is, for example, Y2@C 79 N or Sc3C2@C 80 .

[0015] The present application also provides a method for detecting the phase change of a material by using a metallofullerene electron spin probe, which comprises:

[0016] Mixing the metallofullerene and the material to obtain a sample solution, and performing electron paramagnetic resonance test on the sample solution before and after the phase transition under external stimulation.

[0017] According to the present application, the metallofullerene can also be used in the form of a metallofullerene solution, wherein the metallofullerene solution is obtained by dissolving the metallofullerene in an organic solvent, and the organic solvent is exemplarily carbon disulfide solution.

[0018] According to the present application, the concentration of the metallofullerene in the organic solvent or the material is 0.5×10 -3 M to 3×10 -3 M, and is exemplarily about 1×10 -3 M.

[0019] According to the present application, the mass ratio of the metallofullerene solution to the material is 0.5-6:1, for example, 1:1.

[0020] According to the present application, the external stimulation is heating or light irradiation. For example, the power of the light irradiation is 5-10 watts, the irradiation distance is 1-5 centimeters, and the irradiation time is 1-30 minutes.

[0021] According to the present application, the wavelength of the light irradiation is the wavelength at which the molecular form of the material changes; exemplarily, the trans-isomer of azobenzene compounds will gradually change into cis-isomer under 320-380 nm ultraviolet light irradiation, and will change from cis-isomer to trans-isomer under 420-480 nm visible light irradiation.

[0022] The present application has the following beneficial effects:

[0023] The application is based on high sensitivity of electronic spin of metallofullerene, adding it into the material, using state change of the material during phase transition, high efficiency regulation of spin state in metallofullerene, and using electron paramagnetic resonance signal to reflect the phase transition process of the material, the electronic spin probe can improve the accuracy and sensitivity of phase transition measurement, and can also realize in-situ measurement of phase transition in deep material. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is metallofullerene Y2@C 79 The electron paramagnetic resonance signal change diagram of N before and after phase transition point in 1-chloronaphthalene solvent.

[0025] Figure 2 is metallofullerene Sc3C2@C 80 The electron paramagnetic resonance signal change diagram of N before and after photoisomerization with 4,4'-bis(hexyloxy)-3-methylazobenzene.

[0026] Figure 3 is metallofullerene Y2@C 79 The electron paramagnetic resonance signal change diagram of N before and after photoisomerization with 4,4'-bis(hexyloxy)-3-methylazobenzene. DETAILED DESCRIPTION

[0027] The technical solutions of the application will be further described in detail below in combination with specific embodiments. It should be understood that the following examples are only illustratively described and explained, and should not be interpreted as limiting the scope of protection of the application. Any technology realized based on the above description of the application is covered within the scope of protection intended by the application.

[0028] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0029] Example 1

[0030] A method for detecting material phase transition by a metallofullerene electronic spin probe, the method comprising:

[0031] 1×10 -3 M of Y2@C 79 N was mixed uniformly in 50 microliters of 1-chloronaphthalene solution, wherein the mass concentration of the metallofullerene in the material was 0.1%, to prepare a sample. The above sample was placed in a paramagnetic tube, degassed and subjected to electron paramagnetic resonance test. The sample was subjected to electron paramagnetic resonance test before and after phase transition:

[0032] 1. The sample was subjected to electron paramagnetic resonance test at room temperature, and the obtained metallofullerene Y2@C 79 N electronic spin signal is as follows:Figure 1 (i.e., the curve marked 293K) is shown.

[0033] 2. Gradually lower the temperature of the sample to the liquid-solid phase transition point of 1-chloronaphthalene, 253 K. At this point, the molecular state of 1-chloronaphthalene changes from disorder to order, i.e., a phase transition occurs from liquid to solid. At the phase transition temperature, the resulting metallofullerene Y2@C 79 N electron spin signal, such as Figure 1 As shown (i.e., the curve labeled 253K).

[0034] Depend on Figure 1 It can be seen that 1-chloronaphthalene is in a liquid state above 253 K, and the metal fullerene Y2@C 79 N exhibits ultrafine coupling splitting peaks; when 1-chloronaphthalene undergoes a phase transition at 253 K, the metallofullerene Y2@C 79 The electron spin signal of N changes significantly, becoming a broad peak. This is evident in the metallofullerene Y2@C. 79 The electron spin of nitrogen can reflect the phase transition caused by temperature changes in a material.

[0035] Example 2

[0036] A method for detecting phase transitions in metallofullerenes using an electron spin probe, the method comprising: using a metallofullerene with a concentration of 1×10 -3 M's Sc3C2@C 80 A carbon disulfide solution of 50 μL was prepared by adding 5.6 mg of azobenzene compound 4,4'-bis(hexyloxy)-3-methylazobenzene solid, followed by ultrasonic dissolution. The carbon disulfide was removed by heating, and the sample was placed in a paramagnetic tube. The metallofullerene contained 1% by mass in the material. The sample was then vacuum-dried in a vacuum oven for 24 hours. The resulting solid sample in the paramagnetic tube was subjected to electron paramagnetic resonance (EPR) testing.

[0037] Electron paramagnetic resonance (EPR) tests were performed on the samples before and after the phase transition:

[0038] 1. Electron paramagnetic resonance (EPR) testing was performed on the sample at room temperature, and the results are as follows: Figure 2 As shown (i.e.) Figure 2 (Mid-solid curve).

[0039] 2. The sample was treated as follows: a 5-watt, 365nm ultraviolet lamp was used for irradiation at a distance of 1 cm for 5 minutes. Electron paramagnetic resonance (EPR) testing was then performed, and the results are as follows: Figure 2 As shown (i.e.) Figure 2 (Curve of irradiation with 365nm ultraviolet light for 5 minutes).

[0040] 3. Next, the sample was further treated as follows: 5-watt ultraviolet lamp with a wavelength of 460nm, irradiation distance of 1 cm, and irradiation time of 5 minutes. Electron paramagnetic resonance (EPR) testing was then performed, and the results are as follows: Figure 2 As shown (i.e.) Figure 2 (Curve of irradiation with 460nm visible light for 5 minutes).

[0041] Depend on Figure 2 It is evident that when this azobenzene compound is irradiated at 365 nm, the azotrans-to-cis transition occurs, and the azobenzene compound undergoes a phase transition from solid to liquid state. The metallofullerene Sc3C2@C 80 The electron spin signal changed significantly, showing a hyperfine coupling splitting peak; and when the azobenzene compound was further irradiated at 460 nm, the azobenzene underwent a cis-to-trans transition, and the compound changed from a liquid to a solid state. The metallofullerene Sc3C2@C 80 The electron spin signal also changes significantly, becoming a broad peak. Therefore, the metallofullerene Sc3C2@C of this invention... 80 The electron spin can reflect the phase transition caused by photoisomerization of materials.

[0042] Example 3

[0043] A method for detecting phase transitions in metallofullerenes using an electron spin probe, the method comprising: using a metallofullerene with a concentration of 1×10 -3 M's Y2@C 79 0.5 mL of a carbon disulfide solution containing N was mixed with 5.6 mg of azobenzene compound 4,4'-bis(hexyloxy)-3-methylazobenzene solid. The mixture was sonicated until fully dissolved and mixed to obtain a sample. The sample was then heated to remove the carbon disulfide and placed in a paramagnetic tube, wherein the metallofullerene concentration in the material was 1% by mass. The sample was then vacuum-dried in a vacuum drying oven for 24 hours to remove the solvent. The resulting solid sample in the paramagnetic tube was subjected to electron paramagnetic resonance (EPR) testing.

[0044] 1. The sample was tested at room temperature. The results are as follows: Figure 3 As shown (i.e.) Figure 3 (Mid-solid curve).

[0045] 2. The sample was treated as follows: a 5-watt, 365nm ultraviolet lamp was used for irradiation at a distance of 1 cm for 5 minutes. Electron paramagnetic resonance (EPR) testing was then performed, and the results are as follows: Figure 3 As shown (i.e.) Figure 3 (Curve of irradiation with 365nm ultraviolet light for 5 minutes).

[0046] 3. Then, the sample was treated as follows: power 5 watts, wavelength 460 nm UV light, irradiation distance 1 cm, irradiation time 5 minutes. Subsequently, electron paramagnetic resonance test was performed, and the results are shown in FIG. 4 (i.e., the curve of 460 nm visible light irradiation for 5 min). Figure 3 Figure 3

[0047] Figure 3 As can be seen, after the azobenzene compound was irradiated at 365 nm, the azo trans to cis transition occurred, the azobenzene compound underwent phase transition from solid to liquid, and the electron spin signal of the metallofullerene Y2@C 79 N also changed obviously, and super-fine coupling splitting peaks appeared; when the azobenzene compound was continuously irradiated at 460 nm, the azo cis to trans transition occurred, the azobenzene compound underwent phase transition from liquid to solid, and the electron spin signal of the metallofullerene Y2@C 79 N also changed obviously, and the signal became a wide peak. It can be seen that the electron spin of the metallofullerene Y2@C 79 N can reflect the phase change caused by the photoisomerization of the material.

[0048] The above has exemplarily described the embodiments of the present application. However, the protection scope of the present application is not limited to the above-described embodiments. Any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principle of the present application shall be included in the protection scope of the present application.​​​

Claims

1. Use of a metallofullerene electron spin probe in measuring phase transitions in materials, characterized in that, The metal fullerene is a paramagnetic metal fullerene. The paramagnetic metal fullerenes are at least one of La@C 82 , Y@C 82 , Sc@C 82 , Sc3C2@C 80 , Y2@C 79 N or a combination thereof. The material is an aromatic compound, and the aromatic compound contains at least one of the following substructures in a molecule: benzene, toluene, xylene, mesitylene, chlorobenzene, dichlorobenzene, trichlorobenzene, naphthalene, methylnaphthalene, chloronaphthalene, bromonaphthalene, anthracene, methylanthracene, chloranthracene, bromanthracene, dibromanthracene, phenanthrene, benzophenanthrene. Alternatively, the aromatic compound is an azobenzene compound.

2. Use according to claim 1, characterized in that, The mass concentration of the paramagnetic metal fullerene in the material is 0.1%-5%.

3. Use according to claim 1, characterized in that, The azobenzene compound is at least one selected from 4,4'-bis(hexyloxy)-3-methylazobenzene, 4,4'-bis(decyloxy)-3-methylazobenzene, 4-[bis(9,9-dimethylfluoren-2-yl)amino]azobenzene, and 4,4'-bis(dodecyloxy)-3-methylazobenzene.

4. Use according to claim 1, characterized in that, The material is 1-chloronaphthalene or 4,4'-bis(hexyloxy)-3-methylazobenzene; the paramagnetic metallofullerene is Y2@C 79 N or Sc3C2@C 80 .

5. A method for detecting phase transition of a material by a metallofullerene electron spin probe, characterized in that: The method comprises: The metal fullerene in the application of any one of claims 1-4 is mixed with the material to obtain a sample solution, and electron paramagnetic resonance testing is performed on the sample solution before and after phase transition under external stimulation.

6. The method of claim 5, wherein, The metal fullerene is a metal fullerene solution, the metal fullerene solution is that the metal fullerene is dissolved in an organic solvent, and the organic solvent is carbon disulfide solution.

7. The method of claim 6, wherein, The concentration of the metallofullerene in the organic solvent or the material is 0.5 x 10 -3 M~3x10 -3 M.

8. The method of claim 6, wherein, The mass ratio of the metal fullerene solution to the material is 0.5-6:

1.

9. The method of claim 5, wherein, The external stimulation is heating or light irradiation; the power of the light irradiation is 5-10 watts, the irradiation distance is 1-5 centimeters, and the light irradiation time is 1-30 minutes.

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