Metallofullerene electron spin probe and application thereof in measuring porous material gas adsorption performance

Abstract

The present application relates to a kind of metal fullerene electron spin probe and its application in measuring the adsorption gas capacity of porous material.The metal fullerene electron spin probe of the present application, the electron spin probe is obtained by the metal fullerene containing electron spin being adsorbed into the channel of porous material;The metal fullerene containing electron spin is selected from Sc3C2@C 80 And / or Y2@C 79 N.The present application utilizes metal fullerene electron spin probe to perceive the adsorption capacity of porous material to gas, and can realize in-situ gas perception and measurement.The metal fullerene electron spin probe of the present application can realize the online, real-time, non-destructive detection of target gas on electron paramagnetic resonance spectrometer.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of porous materials and fullerene composites, and particularly relates to a metal fullerene electron spin probe and its application in measuring the gas adsorption performance of porous materials. BACKGROUND

[0002] In recent years, porous materials constructed by metal organic framework compounds (MOF) and covalent organic frameworks (COF) have been widely used in many fields, such as gas storage and separation, heterogeneous, energy storage materials, optoelectronics, sensing, and drug delivery. These porous materials have shown excellent performance in these fields. In particular, these porous materials have shown unique advantages in gas storage and gas sensing. For example, organic porous materials can well adsorb energy gases such as hydrogen, methane, and acetylene, and have good application prospects in gas storage and energy utilization. Gas adsorption method is one of the most important methods for characterizing the adsorption capacity and adsorption process of porous materials, but this method requires a large amount of samples. Organic porous materials can also be used for gas sensing, which can specifically perceive a certain gas by using the change of absorbance and fluorescence after adsorbing the gas, and then analyze the adsorption capacity of the gas. However, this method cannot realize in-situ detection inside the pore channel. In gas adsorption measurement, other techniques that can realize in-situ precise measurement need to be explored.

[0003] As a new type of carbon nanomaterial, endohedral metallofullerene has excellent electron spin characteristics and paramagnetic properties, which have wide application prospects in quantum technology, magnetic materials, magnetic sensing, and precise measurement. It has become an important functional material in the fields of physics, chemistry, and materials. The electron spin characteristics of metallofullerene come from a single electron on the orbital of metallofullerene. Due to the protection of the carbon cage, the electron spin has high stability, and its spin state has sensitive sensing ability to the external environment. Changes in the environment can be observed through electron paramagnetic resonance (EPR) signals. However, the electron spin of metallofullerene in gas sensing and measurement still needs to be explored.

[0004] Due to the nanoscale size of metallofullerene, its molecular diameter is about 1 nanometer. This size and its aromatic carbon cage allow it to enter the pore channel of organic porous materials. For metallofullerene with electron spin, the environment of the pore channel will greatly affect the paramagnetic resonance signal of the spin. For example, the size of the pore channel, the deformation of the framework molecule, and the filling of the solvent will affect the spin relaxation process, and thus change the EPR signal of the spin. Therefore, exploring the sensing of the spin to the gas filled in the pore channel will have great feasibility and practical significance. This detection can realize the detection of gas species, the detection of gas adsorption capacity, and the detection of gas adsorption process, which will greatly promote the application of metallofullerene electron spin. SUMMARY

[0005] To solve the above problems, the present application provides a metallofullerene electron spin probe and its application in measuring the gas adsorption performance of porous materials.

[0006] The present application provides a metallofullerene electron spin probe, which is obtained by adsorbing metallofullerene containing electron spin into the pores of a porous material.

[0007] According to an embodiment of the present application, the metallofullerene containing electron spin is selected from Sc3C2@C 80 and / or Y2@C 79 N. Preferably, the electron spin of Sc3C2@C 80 is located on the Sc3C2 cluster within the carbon cage, and the spin is coupled with three Sc. Exemplarily, the electron spin of Sc3C2@C 80 generates 22 EPR hyperfine splitting lines, and the shape of the EPR lines and the intensity of the lines are related to the surrounding environment of Sc3C2@C 80 .

[0008] Preferably, the electron spin of Y2@C 79 N is located on the Y2 cluster within the carbon cage, and the spin is coupled with two Y. Exemplarily, the electron spin of Y2@C 79 N generates 3 EPR hyperfine splitting lines, and the shape of the EPR lines and the intensity of the lines are related to the surrounding environment of Y2@C 79 N.

[0009] According to an embodiment of the present application, the pore diameter of the porous material is greater than 0.8 nanometers, and the pore diameter is less than 5 nanometers, preferably, the pore diameter is less than 3 nanometers, such pore size can ensure that the metallofullerene enters and uniformly distributes in the pores of the porous material.

[0010] According to an embodiment of the present application, the porous material is selected from metal organic framework compounds (MOF) and / or covalent organic framework compounds (COF).

[0011] Preferably, the metal organic framework compound is selected from metal organic framework compounds constructed by using organic carboxylic acid as organic ligand and metal ion as node. Preferably, the metal ion is selected from diamagnetic metal ions such as Zn, Mg, Zr, etc.

[0012] Preferably, the metal organic framework compound is selected from at least one of MOF-177, MOF-180, MOF-200, etc.

[0013] Preferably, the covalent organic framework compound is a polymer material prepared by co-condensation of an organic compound containing benzaldehyde group and an organic compound containing aniline group.

[0014] Preferably, the covalent organic framework compound (COF) is selected from at least one of Py-COF, Py-Py-COF, Py-TT-COF, and the like. Among them, the Py-COF is a two-dimensional pyrene-based imine COF (Py-COF) constructed by two benzaldehyde and two aniline groups diagonally connected in a single pyrene core molecule; the Py-Py-COF and the Py-TT-COF are covalent organic framework compound materials with two-dimensional pore structure synthesized by aldehyde pyrene and amino pyrene as organic ligands.

[0015] According to an embodiment of the present application, the porous material has a complete crystal structure. Preferably, the porous material is prepared by a preparation method commonly used in the technical field, and crystals with a complete crystal form are selected by optical microscopy combined with a single crystal X-ray diffractometer. Preferably, the crystal size of the porous material is greater than 0.5 millimeters in any dimension.

[0016] The inventors have found that the porous material with a complete crystal structure has a more regular pore structure, which is beneficial to the adsorption of metal fullerenes.

[0017] The present application also provides a preparation method of the above-mentioned metal fullerene electron spin probe, comprising: adsorbing metal fullerenes with electron spins into the pores of the porous material.

[0018] Preferably, the organic porous material can be prepared by a solvothermal method, a microwave method, or the like.

[0019] According to an embodiment of the present application, the preparation method of the electron spin probe comprises: first preparing a porous material, soaking it in a metal fullerene solution, and adsorbing metal fullerenes to obtain a metal fullerene electron spin probe.

[0020] According to an embodiment of the present application, the solvent is selected from organic solvents that can dissolve metal fullerenes but cannot dissolve the porous material. Preferably, the solvent is toluene.

[0021] According to an embodiment of the present application, the concentration of the metal fullerene solution can be 1×10 -5 -10 -4 mol / L.

[0022] According to an embodiment of the present application, the soaking and adsorbing time is 1-7 days, preferably 3 days.

[0023] According to an embodiment of the present application, the electron spin probe is washed with the above-mentioned solvent, which improves the measurement sensitivity of the spin signal to the gas adsorption performance. The present application does not have specific limitations on the washing, as long as the metal fullerenes on the surface of the electron spin probe can be washed off and the metal fullerenes are ensured to be located inside the pores.

[0024] According to the embodiment of the present application, another preparation method of the electron spin probe comprises: adding the metallofullerene into a precursor mother liquor of the porous material, and obtaining the metallofullerene electron spin probe with high filling rate of metallofullerene by embedding the metallofullerene while co-crystallizing the porous material.

[0025] According to the embodiment of the present application, the metallofullerene electron spin probe has a complete crystal structure. In the present application, the metallofullerene electron spin probe is selected by optical microscope and single crystal X-ray diffractometer. Preferably, the metallofullerene electron spin probe has a crystal size of greater than 0.5 mm in any dimension.

[0026] The inventors have found that the metallofullerene electron spin probe crystal with good crystal form has a more regular pore structure, which is more conducive to the adsorption of gas, and ultimately will be conducive to the measurement of the gas adsorption performance by using the spin signal.

[0027] According to the embodiment of the present application, the content of the metallofullerene in the metallofullerene electron spin probe is 0.01-0.1 mol / 10 mg, for example, 0.06 mol / 10 mg.

[0028] According to the embodiment of the present application, the metallofullerene electron spin probe also needs to be vacuum dried to remove the solvent inside the pore, thereby improving the measurement sensitivity of the spin signal to the gas adsorption performance.

[0029] The present application also provides the use of the above-mentioned metallofullerene electron spin probe for in-situ measuring the gas adsorption capacity of the above-mentioned porous material.

[0030] The present application also provides a method for in-situ measuring the gas adsorption capacity of the porous material by using the above-mentioned metallofullerene electron spin probe, which comprises: preparing the metallofullerene electron spin probe, detecting the EPR signal of the metallofullerene electron spin by using an electron paramagnetic resonance (EPR) spectrometer after filling the gas, and in-situ detecting the gas adsorption capacity of the porous material. Preferably, the EPR signal of the metallofullerene is different under different gas conditions.

[0031] According to the embodiment of the present application, the crystal size of the metallofullerene electron spin probe is greater than 0.5 mm in any dimension.

[0032] The present application does not specifically limit the amount of the metallofullerene electron spin probe used in the above-mentioned method, as long as the EPR signal can be measured. Exemplarily, the amount of the metallofullerene electron spin probe is 1 mg.

[0033] According to the embodiment of the present application, the metallofullerene electron spin probe is placed in a sealed atmosphere before being filled with gas. Preferably, the metallofullerene electron spin probe is vacuum degassed before being filled with gas to remove air and other impurities in the pores of the porous material. Preferably, the vacuum degree of the sealed atmosphere is less than 0.1 Pa. Preferably, the vacuum time is 10-60 minutes, preferably 30 minutes.

[0034] According to the embodiment of the present application, the gas is filled in the sealed atmosphere to equilibrium after being vacuum degassed.

[0035] Preferably, the pressure of the sealed atmosphere is maintained at 0.05-0.2 MPa, preferably 0.1 MPa, after being filled with gas.

[0036] Preferably, the gas filling and equilibrium time is 10-60 minutes, preferably 30 minutes.

[0037] According to the embodiment of the present application, the gas is selected from at least one of nitrogen, carbon dioxide, methane, hydrogen, carbon monoxide, acetylene, nitrogen dioxide, ethylene, ethane, propane, propyne, butyne, natural gas, liquefied petroleum gas, biogas, coal gas, and the like.

[0038] The inventors found that the EPR signal of the metallofullerene electron spin is detected by an electron paramagnetic resonance spectrometer, and the effect of the interaction between the metallofullerene and the adsorbed gas in the pores on the EPR signal is used to analyze the adsorption capacity of the porous material for the gas. In principle, the more gas molecules are adsorbed, the less space is in the pores, and the movement of the metallofullerene is restricted, which reduces the spin relaxation time and in turn reduces the EPR signal intensity of the spin. Therefore, the adsorption capacity of the porous material for the gas can be judged according to the EPR signal intensity of the spin. The method for in-situ measuring the gas adsorption capacity of the porous material by the above metallofullerene electron spin probe can quickly evaluate the adsorption capacity of the porous material for different gases according to the EPR signal intensity of the metallofullerene.

[0039] The present application also provides the use of the above metallofullerene electron spin probe in an electron paramagnetic resonance spectrometer.

[0040] The present application has the following advantages:

[0041] 1) The present application screens suitable porous materials represented by metal organic framework compounds (MOF) and covalent organic frameworks (COF), adsorbs metallofullerene containing electron spin into the pores of the porous materials, injects gas into the composite porous materials, and then detects the EPR signal of the electron spin of the metallofullerene by using an electron paramagnetic resonance (EPR) spectrometer, uses the influence of the interaction between the metallofullerene and the surrounding environment on the EPR signal, and analyzes the gas adsorption capacity of the porous materials according to the changes in the EPR signal under different gas filling conditions.

[0042] 2) The electron spin probe of the metallofullerene of the present application measures the gas adsorption capacity of the porous materials, and since the metallofullerene is also in the pores, in-situ gas sensing and measurement can be achieved. The in-situ pore measurement is not achieved by the traditional gas adsorption measurement method.

[0043] 3) The electron spin of the metallofullerene is very sensitive, and the gas adsorption capacity of the porous materials to different gases can be measured by using a crystal of 1 mm in size (about 0.5 mg), while the traditional gas adsorption measurement method requires more than 100 mg of sample. Therefore, the method of measuring the gas adsorption capacity of the porous materials by using the electron spin probe of the metallofullerene is superior to the traditional gas adsorption measurement method in terms of the amount used, and can be used for rapid evaluation of the gas adsorption capacity of the porous materials to different gases.

[0044] 4) The present application detects the EPR signal of the electron spin of the metallofullerene by using an electron paramagnetic resonance spectrometer, and judges the gas adsorption capacity of the porous materials according to the EPR signal intensity. The more gas molecules adsorbed, the less space in the pores, and the movement of the metallofullerene will be restricted, which will reduce the relaxation time of the spin, and the EPR signal intensity of the spin will be lower.

[0045] The electron spin probe of the present application can realize online, real-time, and non-destructive detection on an electron paramagnetic resonance spectrometer, and can monitor the concentration change of the target gas in real time. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 The EPR comparison chart of the metallofullerene electron spin probe obtained in Example 1 of the present application after N2 and CO2 are filled. DETAILED DESCRIPTION

[0047] The technical solutions of the present application will be further described in detail below in combination with specific examples. It should be understood that the following examples are only illustrative and explanatory of the present application, and should not be interpreted as limiting the scope of protection of the present application. Any technology realized based on the above description of the present application is covered within the scope intended to be protected by the present application.

[0048] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0049] Example 1

[0050] 3.1 mg of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene (Py(CHO)4) and 3.5 mg of 1,3,6,8-tetrakis(p-aminophenyl)pyrene (Py(CHO)4) were placed in a reaction vessel, along with 333 μL of mesitylene, 167 μL of benzyl alcohol, and 50 μL of 6M acetic acid. The reaction temperature was set at 120 °C, and the reaction time was 3 days. After cooling to room temperature, the precipitate was filtered and washed three times with acetonitrile. After a period of time, it was washed three more times with toluene, repeating this process several times to completely replace the solvent in the solid channels with toluene. 10 mg of air-dried Py-COF was selected and weighed and placed in 2 mL of Sc3C2@C 80 Toluene solution (concentration 3.0 × 10⁻⁶) - 5 In a solution of mol / L, allow it to fully adsorb Sc3C2@C 80 The solid was removed and dried under vacuum to obtain... The composite material is the metallofullerene electron spin probe of this embodiment. (Take...) 1 mg of the composite material was placed in a paramagnetic tube and the rubber stopper was tightened. A needle was inserted through the rubber stopper, and a vacuum was applied for 30 minutes to remove gas. Then, N2 was injected, and the mixture was equilibrated at one atmosphere for 30 minutes. Subsequently, the N2-filled composite material was tested using an electron paramagnetic resonance spectrometer to obtain the corresponding EPR spectrum, as shown below. Figure 1 Sample 1 is shown in the figure. The composite material was then subjected to vacuum degassing for 30 minutes, followed by CO2 injection and equilibration at one atmosphere for 30 minutes. The EPR spectrum was then obtained using an electron paramagnetic resonance spectrometer, as shown in the figure. Figure 1 As shown in sample 2.

[0051] from Figure 1 The EPR signal intensity is higher after N2 adsorption, while it is lower after CO2 adsorption. This indicates that porous materials have a higher adsorption capacity for CO2. This EPR result is consistent with the results obtained by the traditional static volumetric adsorption measurement technique, which requires 100 mg of sample. This demonstrates that porous materials can adsorb CO2 with trace amounts of CO2. The composite material was subjected to EPR testing, which effectively distinguished N2 and CO2 in the external environment.

[0052] The above describes exemplary embodiments of the present application. However, 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 should be included in the scope of the present application.

Claims

1. A metallofullerene electron spin probe, characterized in that, The electron spin probe is obtained by adsorbing electron-spin-containing metal fullerenes into the pores of a porous material; the electron-spin-containing metal fullerenes are selected from Sc3C2@C 80 and / or Y2@C 79 N; Sc3C2@C 80 The electron spin is located on the Sc3C2 cluster within the carbon cage, and the spin is coupled to three Sc atoms; Y2@C 79 The electron spin of N is located on the Y2 cluster within the carbon cage, and the spin is coupled to the two Y atoms. The crystal size of the porous material is greater than 0.5 mm in any dimension; the pore diameter of the porous material is greater than 0.8 nm and less than 5 nm, ensuring that the metal fullerene containing electron spin enters and is uniformly distributed in the pores of the porous material. In the metal fullerene electron spin probe, the content of the metal fullerene containing electron spin in the porous material is 0.01-0.1 mol / 10 mg.

2. The metallofullerene electron spin probe according to claim 1, characterized in that, The pore diameter of the porous material is less than 3 nanometers.

3. The metallofullerene electron spin probe according to claim 1, characterized in that, The porous material is selected from metal-organic framework compounds and / or covalent organic framework compounds; The metal-organic framework compound is selected from metal-organic framework compounds constructed with organic carboxylic acids as organic ligands and metal ions as nodes; the metal ions are selected from diamagnetic metal ions such as Zn, Mg, and Zr. The covalent organic framework compound is a polymer material prepared by co-condensation of an organic compound containing a benzaldehyde group and an organic compound containing an aniline group.

4. The metallofullerene electron spin probe according to claim 3, characterized in that, The metal-organic framework compound is selected from at least one of MOF-177, MOF-180, and MOF-200; The covalent organic framework compound is selected from at least one of Py-COF, Py-Py-COF, and Py-TT-COF; wherein, Py-COF is a two-dimensional pyrene imine COF (Py-COF) constructed by diagonally linking two benzaldehydes and two aniline groups in a single pyrene nucleus molecule; Py-Py-COF and Py-TT-COF are covalent organic framework compound materials with two-dimensional porous structures synthesized with amide bonds using aldehyde pyrene and amino pyrene as organic ligands.

5. The metallofullerene electron spin probe according to claim 1, characterized in that, The porous material has a complete crystal structure.

6. The method for preparing the metallofullerene electron spin probe according to any one of claims 1-5, characterized in that, The method for preparing the electron spin probe includes: first preparing a porous material, immersing it in a metal fullerene solution containing electron spin, and adsorbing the metal fullerene containing electron spin to obtain a metal fullerene electron spin probe. Alternatively, the electron-spin-containing metal fullerene can be added to the precursor solution for preparing porous materials, and the electron-spin-containing metal fullerene can be embedded during the co-crystallization construction of porous materials to obtain a metal fullerene electron spin probe with a high filling rate of electron spin-containing metal fullerene.

7. The preparation method according to claim 6, characterized in that, The porous material was prepared by a solvothermal method and a microwave method. The solvent is selected from organic solvents capable of dissolving fullerenes containing electron spin but insoluble in porous materials; the concentration of the fullerene solution containing electron spin is 1 × 10⁻⁶. -5 -10 -4 mol / L; The soaking and adsorption time is 1-7 days; The electron spin probe is rinsed with the solvent to improve the sensitivity of the spin signal to the measurement of gas adsorption performance.

8. The preparation method according to claim 7, characterized in that, The organic solvent is toluene; The soaking and adsorption time is 3 days.

9. The preparation method according to claim 6, characterized in that, The metal fullerene electron spin probe has a complete crystal structure; the metal fullerene electron spin probe is selected by optical microscopy in conjunction with single-crystal X-ray diffraction; the metal fullerene electron spin probe has a crystal size greater than 0.5 mm in any dimension; The metallofullerene electron spin probe is also vacuum dried to remove the solvent inside the pores, thereby improving the sensitivity of the spin signal to the measurement of gas adsorption performance.

10. The application of the metal fullerene electron spin probe according to any one of claims 1-5 for in-situ measurement of the gas adsorption capacity of the porous material.

11. A method for in-situ measurement of the gas adsorption capacity of porous materials using a metallofullerene electron spin probe according to any one of claims 1-5, characterized in that, The method includes: preparing the metal fullerene electron spin probe, filling it with gas, and using an electron paramagnetic resonance spectrometer to detect the EPR signal of the metal fullerene electron spin, thereby detecting the ability of the porous material to adsorb gas in situ.

12. The method according to claim 11, characterized in that, The EPR signal of the metal fullerene differs under different gas conditions; The crystal size of the metallofullerene electron spin probe is greater than 0.5 mm in any dimension.

13. The method according to claim 11, characterized in that, The metal fullerene electron spin probe is placed in a sealed atmosphere before being filled with gas; the metal fullerene electron spin probe is degassed under vacuum before being filled with gas to remove air impurities in the pores of the porous material; the vacuum degree of the sealed atmosphere is less than 0.1 Pa; the vacuuming time is 10-60 minutes. After vacuum degassing, gas is introduced into a sealed atmosphere until equilibrium is reached; After the gas is introduced, the pressure of the sealed atmosphere is maintained at 0.05-0.2 MPa; Inflation and equalization time is 10-60 minutes; The gas is selected from at least one of nitrogen, carbon dioxide, methane, hydrogen, carbon monoxide, acetylene, nitrogen dioxide, ethylene, ethane, propane, propyne, butyne, natural gas, liquefied petroleum gas, biogas, and coal gas.

14. The application of the metal fullerene electron spin probe according to any one of claims 1-5 in an electron paramagnetic resonance spectrometer.

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