Soluble microporous polymer as well as preparation method and application thereof

Abstract

The invention belongs to the field of porous organic polymers, and particularly relates to highly-protonated solution-processable microporous polymer powder, a preparation method thereof and application of the highly-protonated solution-processable microporous polymer powder as a photocatalyst. According to the invention, p-benzobithiazole monomers are used as raw materials for polymerization, and the microporous polymer powder capable of being processed in a solution is prepared. The polymer has good optical performance and can be used as an organic reaction catalyst.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of porous organic polymers, and particularly relates to a highly protonated solution-processable microporous polymer powder, a preparation method thereof and application thereof as a photocatalyst. BACKGROUND

[0002] Photocatalysis is an advanced technology that uses light energy to catalyze chemical reactions. At present, photocatalysis has shown great application potential in many fields such as environmental governance, energy production, chemical synthesis and material science. Because it can utilize abundant solar energy, reduce energy consumption, and is simple and safe to operate, it has attracted widespread attention and research as a promising green technology in recent years. However, the photocatalytic performance is greatly limited by the material performance and stability, which is difficult to satisfy. In order to solve this problem and further break through the bottleneck of photocatalytic reaction, it is particularly important to develop a new type of photocatalyst with high exciton lifetime, low exciton binding energy, excellent photoactivity and excellent stability.

[0003] Covalent triazine-based polymers (CTPs) were first reported by Thomas et al. in 2008, which are porous organic polymer materials synthesized by covalent bonding between triazine nuclei and aromatic rings. CTPs have synthetic diversity, high chemical / thermal stability, structural tunability and significant functionalization potential, and are considered to be a promising photocatalyst for the synthesis of various products. By pre-designing the structure, introducing photoactive groups and further improving the conjugation degree, the photoactivity and exciton performance of CTPs can be improved. Since most CTPs are non-melting and non-dissolving powders, they are commonly used as catalysts for heterogeneous catalysis, which is convenient for recovery while ensuring catalytic efficiency. In order to further improve the catalytic efficiency, it is crucial to adjust the band gap of the catalyst. As a completely conjugated organic structure, CTP is a semiconductor with a customizable band gap. Considering that the uniformly distributed triazine rings in CTP can act as protonation sites, the band gap of CTP can be effectively adjusted by protonation, thereby greatly regulating the performance of photocatalysis and achieving efficient heterogeneous catalysis. In addition, a high degree of protonation is expected to effectively inhibit molecular aggregation through electrostatic repulsion, thereby exposing more catalytically active sites, which together enhance the photocatalytic performance. The protonated CTP can be uniformly dispersed in a solution to form a new type of CTP porous organic material in the form of a uniform transparent sol and a solution-processable material by utilizing solution interactions and intermolecular electrostatic repulsion. The solubility of the CTP in some solvents is better than that of most organic porous materials, and it can be used for "quasi-homogeneous catalysis" to photocatalyze organic reactions. By screening solvents, the conversion between heterogeneous catalysis and quasi-homogeneous catalysis can be realized, which exhibits excellent organic catalytic performance and is expected to become a versatile and efficient photocatalyst. SUMMARY

[0004] The application successfully synthesizes a CTP material with long exciton lifetime, high degree and uniform protonation by suitable molecular design, which can realize excellent photocatalytic performance under heterogeneous catalysis, and can be dispersed into sol for quasi-homogeneous catalysis, and has good research prospect.

[0005] The technical scheme of the application is as follows:

[0006] The application first provides a soluble microporous polymer, which is a polymer polymerized from a p-benzodithiazole monomer; the structure of the p-benzodithiazole monomer is .

[0007] Further, the soluble microporous polymer has a repeating unit shown in formula (1):

[0008]

[0009] Formula (1).

[0010] Further, the soluble microporous polymer has a repeating unit shown in formula (2):

[0011]

[0012] Formula (2).

[0013] Further, the preparation method of the p-benzodithiazole monomer comprises the following steps: subjecting 2,5-diamino-1,4-benzenedithiol dihydrochloride ( ) and 4-cyanobenzaldehyde ( ) to cyclization condensation reaction to obtain the p-benzodithiazole monomer.

[0014] Further, the molar ratio of the 2,5-diamino-1,4-benzenedithiol dihydrochloride to the 4-cyanobenzaldehyde is 1:2-2.5. The excess of the 4-cyanobenzaldehyde can accelerate the reaction and improve the reaction rate.

[0015] Further, the cyclization condensation reaction is carried out at a temperature of 60-80℃ for 6-8h. The solvent used in the cyclization condensation is ethanol.

[0016] The application further provides a preparation method of the soluble microporous polymer. The preparation method comprises the following steps: cooling the p-benzodithiazole monomer and triflic acid at-5--30℃, then performing polymerization reaction at 50-70℃ to obtain a preliminary CTP, adding alkali to deprotonate to obtain a deprotonated soluble microporous polymer (the structure is a repeating unit shown in formula (1)).

[0017] Further, in the above method for preparing the soluble microporous polymer, the deprotonated soluble microporous polymer is converted into the protonated soluble microporous polymer (repeat units as shown in formula (2)) by adding an acid. The deprotonated soluble microporous polymer is stirred in a flask at room temperature for 3-6 hours.

[0018] Further, in the above method for preparing the soluble microporous polymer, the acid used for protonation is a hydrochloric acid solution or a sulfuric acid solution. The hydrochloric acid solution is obtained by mixing concentrated hydrochloric acid with a mass fraction of 35-38% and water in a volume ratio of 1:1. 3 mL of the above hydrochloric acid solution is needed for protonation of 100 mg of CTP. The sulfuric acid solution is obtained by mixing concentrated sulfuric acid with a mass fraction of 95-98% and water in a volume ratio of 1:2. 3 mL of the above sulfuric acid solution is needed for protonation of 100 mg of CTP.

[0019] Further, in the above method for preparing the soluble microporous polymer, 1-5 mL of triflic acid is used for 100 mg of the monomer of the p-benzodithiazole type. Preferably, 2 mL of triflic acid is used for 100 mg of the monomer of the p-benzodithiazole type.

[0020] Further, in the above method for preparing the soluble microporous polymer, the cooling temperature is -25°C.

[0021] Further, in the above method for preparing the soluble microporous polymer, the cooling time is 0.5-3 h. Preferably, the cooling time is 1.5 h.

[0022] Further, in the above method for preparing the soluble microporous polymer, the polymerization reaction is carried out in an inert atmosphere, such as a nitrogen atmosphere. The container used for the polymerization reaction is a Schlenk tube. The polymerization reaction does not require the use of a solvent.

[0023] Further, in the above method for preparing the soluble microporous polymer, the polymerization reaction time is 10-15 h.

[0024] Further, in the above method for preparing the soluble microporous polymer, the base is sodium hydroxide.

[0025] The present application also provides the use of the above soluble microporous polymer as a photocatalyst for organic reactions.

[0026] Further, the catalysis is the introduction of a difluoromethyl group on a heterocyclic small molecule through C-H activation principles.

[0027] The present application has the following advantages:

[0028] The polymer containing a benzobisthiazole structural unit in the application can be protonated by proton acceptors on its skeleton, the band gap is regulated by protonation, the visible light absorption is expanded, and the visible light is used to realize efficient photocatalysis, improve photoactivity, and facilitate the dissociation and transport of photo-generated carriers. The CTP after protonation as a catalyst for photocatalysis has a significant improvement compared with the CTP before protonation, the conversion rate is more than 99%, the yield is more than 73%, and the yield is increased by 320% (yield increase rate = (protonated catalytic yield - unprotonated catalytic yield) / unprotonated catalytic yield) compared with the CTP before protonation. It has a wide application prospect.

[0029] Meanwhile, it is found that the proton acceptor on its skeleton can be uniformly dispersed in the solvent by the charge-induced dispersion (CID) mechanism to form a clear and transparent solution, realize solution processing and further quasi-homogeneous catalysis (the solubility in formic acid is as high as 10 mg / mL, and the solubility in NMP is as high as 6.5 mg / mL. The corresponding solution processing performance has a great leap), and high-quality thin films can be prepared, so that the photoelectric properties of the material can be more accurately measured by the film, and it is also more convenient for subsequent possible industrial use, which has great application potential. When the polymer in the application is used as a catalyst, the problems of poor universality, pollution, toxicity, and many by-products in the traditional catalytic reaction of introducing difluorine can be solved. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 XPS N1s and Cl2p spectra of BTT-CTP and BTTH-CTP obtained in Example 1; wherein a is the process of synthesizing CTP and converting by acid and base; b is the XPS N1s spectrum of BTT-CTP and BTTH-CTP, it can be seen that there is a new peak, which indicates the success of protonation, and the site of protonation is on N. By analyzing the new peak, it can be known that protonation occurs on the triazine ring, and the degree of protonation is 50%, and on average, 1.5 N on each triazine ring is protonated. Because it is very difficult to protonate 3 N sites on a triazine ring at the same time, 1 or 2 N sites on each triazine ring are protonated, so it can be shown that not only high degree of protonation is achieved, but also the protonation is very uniform; c is Cl2p spectrum, because hydrochloric acid is used for protonation, Cl - will become a counterion, and there is a Cl peak after protonation, which can be used as evidence of the success of protonation. Figures b and c are measured by powder X-ray on a Rigaku SmartLab X-ray diffractometer, copper-K alpha radiation (λ = 1.54178 angstrom) is used, the scanning speed is 5 °C min −1 .

[0031] Figure 2 Optical properties of BTT-CTP and BTTH-CTP obtained in Example 1; where a is the UV-Vis absorption spectrum, it can be seen from the comparison of BTT-CTP and BTTH-CTP that the absorption wavelength of the material after protonation is greatly expanded for visible light, which also leads to the narrowing of its band gap, making it easier for the CTP after protonation to be excited by light, having better optical properties, and can make more full and efficient use of natural light. b is the band gap diagram, the HOMO energy level is determined to be -6.46 eV (BTT-CTP) and -6.29 eV (BTTH-CTP) by ultraviolet photoelectron spectroscopy (UPS) measurement. According to the optical band gap and UPS spectrum of BTT-CTP and BTTH-CTP, the corresponding LUMO energy levels of BTT-CTP and BTTH-CTP are calculated to be -3.74 eV and -4.18 eV, respectively, and the band gap of CTP is narrowed by protonation, making it easier to be excited, and achieving more efficient use of visible light. c is the fluorescence lifetime diagram, it can be seen that the fluorescence lifetime after protonation is longer than that before protonation. In order to clarify the nature of the exciton dynamics, the femtosecond transient absorption (fs-TA) spectra of BTT-CTP and BTTH-CTP films were measured across 430-780 nm. After excitation at 400 nm, the TA spectrum of the BTTH-CTP film immediately shows a dominant excited state absorption (ESA) band reaching a peak at 615 nm, corresponding to the S1→ S n transition. A similar spectral pattern is observed in the BTT-CTP film, with a peak at 600 nm. Further fitting of the exciton dynamics of BTT-CTP and BTTH-CTP films shows that both dynamics traces can be well described by a multi-exponential decay. It is found that both BTT-CTP and BTTH-CTP have a long exciton relaxation time, 4738 ps (d) and 5015 ps (e) respectively. Figure 2 d)and 5015 ps ( Figure 2 e)respectively. f The binding energy of BTTH-CTP is calculated to be 39.1±2.7 meV by fitting the integral PL intensity as a function of temperature using the Arrhenius equation, which is relatively low compared to most organic semiconductors, and the small E bThe values help charge separation in the BTTH-CTP photocatalytic reaction. It is seen from 2a that the light absorption of the protonated CTP is red-shifted, and the ability to utilize natural light is improved. 2b shows that the protonation of CTP makes the band gap narrower, which is more conducive to the excitation of excitons and improves the photocatalytic performance. 2c shows that the fluorescence lifetime of CTP before and after protonation has little change. 2d and 2e compare the exciton lifetime of BTT-CTP and BTTH-CTP before and after protonation, both of which have very long exciton lifetime, which is suitable for photocatalysis. 2f shows that the exciton binding energy of BTTH-CTP after protonation is very low, which is also beneficial to photocatalysis. Figure 2 It is shown that BTTH-CTP has excellent optical properties.

[0032] Figure 2 a UV-Vis spectra were recorded on a Shimadzu UV-3600 spectrometer. 2c The photoluminescence decay curve was measured on a picosecond lifetime fluorescence spectrometer (QUANTAURUS-TAU C11367-11) in the time-correlated single photon counting (TCSPC) mode. 2d and 2e A 7-channel optical filter was inserted in the probe beam to cut off the 1030 nm fundamental wave. The time delay between the pump beam and the probe beam was adjusted by a motorized translation stage in the probe beam controlled by a computer. The time resolution between the pump pulse and the probe pulse was ~200 femtoseconds (full width at half maximum). The transmitted light was detected by a CMOS linear image sensor. The excitation pulse energy was measured to be ~60 nJ pulse −1 at the sample. The stability of the sample was checked by spectrophotometry before and after each experiment. After instrument response function (IRF) deconvolution, the kinetic traces obtained from the time-resolved spectra were analyzed by nonlinear least-squares fitting of a general exponential and function using nonlinear least-squares fitting. All spectral measurements were carried out at room temperature. 2f The photoluminescence spectra as a function of temperature were recorded on a HORIBA Fluorolog-3 assembly fluorescence spectrometer.

[0033] Figure 3To evaluate the photocatalytic feasibility of the two CTPs and study the effect of protonation on their catalytic performance, the heterocyclic C-H difluoromethylation was chosen as the reaction. In a typical reaction under the optimized conditions, 1-methylquinolin-2(1H)-one (20 mg) was used as the substrate and BTT(H)-CTPs (5 mg) as the photocatalyst. The reaction was carried out in a mixture of n-hexane and acetic acid under an O2 atmosphere using CHF2SO2Na (34.7 mg) as the source of difluoromethyl radicals, while irradiating white light (400-800 nm). As shown in 3a, the conversion efficiency of BTTH-CTP was 99% and the gas chromatography yield was 86%. It can be seen that the catalytic performance of BTTH-CTP after protonation was greatly improved compared with BTT-CTP, and the catalytic performance after protonation was significantly improved by 3 times, and there was almost no yield without oxygen and after adding TEMPO, which indicated that oxygen and active radicals generated by the catalyst were the main catalytic active substances; as shown in 3b (solid for BTTH-CTP, diagonal line for BTT-CTP), when BTT-CTP was used as the photocatalyst, the best catalytic performance was observed under 365 nm light (50% conversion, 35% yield), which was significantly higher than that under 420 nm light (46% conversion, 25% yield) and white light (46% conversion, 23% yield). This can be attributed to its relatively large band gap, which requires higher energy for electron transition, so it mainly absorbs high-energy ultraviolet and blue-violet light. In addition, its maximum absorption peak is near 365 nm, and the absorption edge is at 500 nm, indicating a lack of effective absorption ability for white light. After protonation treatment, the absorption edge showed a red shift of about 130 nm, indicating that its ability to absorb low-energy, long-wavelength visible light was enhanced. This modification released its photocatalytic potential by generating more photo-generated charge carriers to drive the reaction, thereby significantly improving the catalytic performance under white light. Therefore, the protonated catalyst achieved excellent photocatalytic performance under white light (99% conversion, 86% yield), and under 365 nm light (99% conversion, 51% yield) and 420 nm light (89% conversion, 42% yield), its efficiency under white light was greatly improved. Ultraviolet light accounts for only about 5% of the total energy of natural light, while white light, as the main component of natural light, accounts for about 45%. Protonation treatment changed the best light source from high-cost, potentially dangerous ultraviolet light to low-cost, safe white light, while significantly improving the photocatalytic performance.3c is the conversion and yield of BTTH-CTP in different solvents, which proves that the system can complete the reaction in different solvents, wherein HEX is n-hexane, CYH is cyclohexane, DMF is N,N-dimethylformamide, DMB is dibenzoylmethane, DEG is diethylene glycol, DMSO is dimethyl sulfoxide, and it is particularly worth noting that due to the charge-induced dispersion effect after protonation, BTTH-CTP can be uniformly dispersed in DMSO, so as to carry out quasi-homogeneous catalysis (99% conversion, 53% yield).

[0034] Figure 3 The experiment is a heterocyclic C-H difluoromethylation reaction: BTT(H)-CTP (5 mg), substrate (1-methylquinolin-2(1H)-one, 20 mg) and sodium difluoromethylsulfonate (34.7 mg) are placed in a 25 mL Schlenk tube, vacuumed for 5 minutes and then filled with an oxygen ball atmosphere. After adding n-hexane (1 mL), 0.6 mL of acetic acid is additionally added to the BTTH-CTP to maintain the pH value of the system, and the reaction mixture is placed under a 400-800 nm white light LED light source and stirred at a speed of 125 rpm for 12 hours, during which the reaction is maintained at a constant temperature of 25°C by cooling with an electric fan. After the reaction is completed, the CTP catalyst is separated and washed with water and methanol. All liquid components are collected, and n-dodecane is used as an internal standard for quantitative analysis using a gas chromatograph (GC) equipped with a hydrogen flame ionization detector (FID). The structure of the product is confirmed by comparing the retention time of the standard, and further verified by gas chromatography-mass spectrometry (GC-MS). GC analysis uses Agilent 7890B gas chromatograph equipped with HP-5 chromatographic column (30 m × 320 μm × 0.25 μm), FID detector, and hydrogen as carrier gas; GC-MS analysis uses the same type of chromatograph and chromatographic column, and is equipped with a quadrupole mass spectrometer, and helium is used as the carrier gas.

[0035] Figure 4 Organic reaction equation diagram using BTT-CTP and BTTH-CTP as catalysts. DETAILED DESCRIPTION

[0036] In the present application, the polymer with the repeating unit as shown in formula (1) can be converted into a polymer with the repeating unit as shown in formula (2) by adding an acid; the polymer with the repeating unit as shown in formula (2) can also be converted into a polymer with the repeating unit as shown in formula (1) by adding a base.

[0037] In the method of the present application, the polymerization reaction is mixing 100 mg of the monomer of the benzobisthiazole class with 1-5 mL of trifluoromethanesulfonic acid in a Schlenk tube under a nitrogen atmosphere, first cooling at -5 to -30°C (preferably -25°C) for 0.5-3 h (preferably 1.5 h), and then polymerizing at 50-70°C for 10-15 h without other solvents.

[0038] In the method of the present application, after the polymerization reaction, a CTP deep red solution completely protonated by trifluoromethanesulfonic acid is obtained, and in order to obtain a solid powder material, further deprotonation is performed by adding a base, which can be an organic base (such as triethylamine) or an inorganic base (such as sodium hydroxide), preferably a 2 M aqueous sodium hydroxide solution is prepared for deprotonation. The operation is to pour a small amount of the Schlenk tube containing the CTP protonated by trifluoromethanesulfonic acid into the Schlenk tube, and observe the color of the solution changing from red to yellow while continuously precipitating yellow solids. The yellow solids are centrifuged and subjected to Soxhlet treatment to obtain a polymer powder with a repeating structure as shown in formula (1).

[0039] Example 1

[0040] I. Preparation of powder BTT-BN

[0041] Disperse 2,5-diamino-1,4-benzenedithiol dihydrochloride (A, 5 g, 29.03 mmol) and 4-cyanobenzaldehyde (B, 8.75 g, 66.76 mmol) in 20 mL of EtOH, ultrasonic for 1 min, then in a sealed container at 60 o C, react for 6 h, wash and dry with methanol or ethanol after cooling to room temperature, to obtain monomer BTT-BN orange-yellow solid powder for the subsequent reaction.

[0042] II. Preparation of BTT-CTP covalent triazine polymer

[0043] Weigh the monomer BTT-BN powder into a Schlenk tube, add trifluoromethanesulfonic acid (TfOH), seal with a rubber plug, and place it in a -25°C environment for 1.5 hours, the ratio of monomer to trifluoromethanesulfonic acid is 100 mg of monomer to 2 mL of trifluoromethanesulfonic acid, then seal the container and react at 60°C for 12 h, neutralize with 2M NaOH in deionized water after cooling to room temperature, precipitate a light yellow precipitate, wash with solvent and dry to obtain light yellow BTT-CTP powder.

[0044] III. Preparation of BTTH-CTP covalent triazine polymer

[0045] The weighed BTT-CTP powder was put into a round bottom flask, hydrochloric acid was added, and the flask was sealed with a rubber plug and stirred at 30°C for 6h. After cooling to room temperature, the product was washed with solvent and dried to obtain a more unprotonated BTT-CTP powder with darker color and better solubility. The ratio of unprotonated CTP powder to hydrochloric acid was 2mL of concentrated hydrochloric acid mixed with deionized water for every 100mg of CTP powder.

[0046] Example 2

[0047] The preparation process was the same as that of Example 1, except that the raw materials were changed to BTT-BN 100mg and TfOH 1.5mL. The resulting product was a powder, labeled as BTTH-CTP #2.

[0048] Example 3

[0049] The preparation process was the same as that of Example 1, except that the raw materials were changed to BTT-BN 100mg and TfOH 3mL. The resulting product was a powder, labeled as BTTH-CTP #3.

[0050] Example 4

[0051] The preparation process was the same as that of Example 1, except that the raw materials were changed to BTT-BN 100mg and TfOH 4mL. The resulting product was a powder, labeled as BTTH-CTP #4.

[0052] Example 5

[0053] The preparation process was the same as that of Example 1, except that the raw materials were changed to BTT-BN 100mg and TfOH 5mL. The resulting product was a powder, labeled as BTTH-CTP #5.

[0054] Example 6

[0055] The preparation process was the same as that of Example 1, except that the protonated acid was changed to concentrated sulfuric acid. The resulting product was a powder, labeled as BTTH-CTP #6.

[0056] Example 7

[0057] The preparation process was the same as that of Example 6, except that the raw materials were changed to BTT-BN 100mg and TfOH 1.5mL. The resulting product was a powder, labeled as BTTH-CTP #7.

[0058] Example 8

[0059] The same as the preparation process of Example 6, the only difference is that the raw materials are changed to: BTT-BN 100 mg, TfOH 3 mL; the resulting product is a powder, denoted as BTTH-CTP #8.

[0060] Example 9

[0061] The same as the preparation process of Example 6, the only difference is that the raw materials are changed to: BTT-BN 100 mg, TfOH 4 mL; the resulting product is a powder, denoted as BTTH-CTP #9.

[0062] Example 10

[0063] The same as the preparation process of Example 6, the only difference is that the raw materials are changed to: BTT-BN 100 mg, TfOH 5 mL; the resulting product is a powder, denoted as BTTH-CTP #10.

Claims

1. A soluble microporous polymer, characterized by: It is a polymer obtained by polymerization of a p-benzobisthiazole monomer; the p-benzobisthiazole monomer has a structure of .

2. The dissolvable microporous polymer of claim 1, wherein: It has a repeating unit shown in formula (1) or formula (2): Formula (1) Formula (2).

3. The dissolvable microporous polymer of claim 1 or 2, wherein: The preparation method of the p-benzobisthiazole monomer comprises the following steps: subjecting 2,5-diamino-1,4-benzenedithiol dihydrochloride and 4-cyanobenzaldehyde to cyclization condensation reaction to obtain the p-benzobisthiazole monomer. Further, the molar ratio of the 2,5-diamino-1,4-benzenedithiol dihydrochloride to the 4-cyanobenzaldehyde is 1:2-2.

5. Further, the cyclization condensation reaction is carried out at a temperature of 60-80℃ for 6-8h.

4. Process for the production of a soluble microporous polymer according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: subjecting the p-benzobisthiazole monomer to cooling with trifluoromethanesulfonic acid at-5--30℃, and then subjecting to polymerization reaction at 50-70℃ to obtain a preliminary CTP, and adding alkali to deprotonate to obtain a deprotonated soluble microporous polymer.

5. The method of claim 4, wherein: The deprotonated soluble microporous polymer is protonated by adding acid to be converted into a protonated soluble microporous polymer.

6. The method of making a soluble microporous polymer according to claim 4 or 5, wherein: 1-5 mL of trifluoromethanesulfonic acid corresponds to 100 mg of the p-benzobisthiazole monomer; preferably, 2 mL of trifluoromethanesulfonic acid corresponds to 100 mg of the p-benzobisthiazole monomer.

7. The method of making a soluble microporous polymer according to any one of claims 4-6, wherein: The cooling temperature is-25℃, and the cooling time is 0.5-3h; preferably, 1.5h.

8. The method of making a soluble microporous polymer according to any one of claims 4-7, wherein: The polymerization reaction time is 10-15h.

9. Use of the soluble microporous polymer of any one of claims 1-3 or the soluble microporous polymer prepared by the method of any one of claims 4-8 as a photocatalyst for organic reactions.

10. Use according to claim 9, characterized in that: The catalysis is introducing difluoromethyl on a heterocyclic small molecule through C-H activation principle.

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