A method for detecting the formation of SABRE intermediates by a substrate-coordinated catalyst precursor

Abstract

The present invention belongs to the technical field of nuclear magnetic resonance detection, and particularly relates to a method for detecting the formation of SABRE intermediates by substrate-coordinated catalyst precursors, comprising the following steps: preparing an NMR sample to be measured, collecting a one-dimensional <supgt;1< / supgt;H NMR spectrum, collecting a 2D DOSY spectrum, obtaining a high-resolution 2D DOSY spectrum, assigning spectral peaks to extract the self-diffusion coefficient, and processing and analyzing the results. Compared with the existing method for judging SABRE intermediates by 2D spectra, the 2D DOSY spectrum adopted by the present invention has the advantages of time-saving, simplicity, intuitiveness, etc.; by comparing the change in the self-diffusion coefficient of the substrate before and after binding to the catalyst precursor and the phenomenon that the bound substrate and the catalyst precursor diffuse at the same diffusion rate, it is possible to judge the substrate that binds to the catalyst precursor to form SABRE intermediates.

Description

Technical Field

[0001] The present invention belongs to the technical field of nuclear magnetic resonance detection, and particularly relates to a method for detecting the formation of SABRE intermediates by a substrate coordination catalyst precursor. Background Art

[0002] Para-hydrogen induced polarization (PHIP) is a molecular hyperpolarization technique used to enhance the intensity of nuclear magnetic resonance spectroscopy (NMR) and imaging (MRI) signals. In recent years, a newly developed PHIP method, signal amplification by reversible exchange (SABRE), has attracted much attention since its discovery in 2009. The principle of the para-hydrogen (para-H2) induced hyperpolarization enhancement technique is to add the enriched para-H2 (purity can be greater than 99%) to the substrate molecule with an unsaturated bond through a catalytic hydrogenation reaction, or transfer the spin order of para-H2 to the 1 H nucleus and heteroatoms of the substrate molecule ( 13 C, 15 N, 19 F, 31 P, etc.). To generate SABRE hyperpolarization, a catalyst is required. Currently, the most commonly used one is an Ir-based organometallic complex, also called the SABRE catalyst precursor, which can simultaneously bind para-H2 and the substrate to be hyperpolarized to form a SABRE active catalyst. The SABRE active catalyst can "catalyze" the transfer of spin order from para-H2 to the substrate bound to the catalyst precursor. Since the process of binding para-H2 and the substrate to the SABRE catalyst precursor is dynamically reversible, the polarized substrate dissociates from the SABRE active catalyst and returns to the solution, resulting in the aggregation of the polarization of free substrate molecules, thereby achieving the hyperpolarization of free substrate molecules. Compared with the catalytic hydrogenation PHIP method, the advantage of the SABRE method is that the substrate will not be depleted in the reaction. After the substrate polarization relaxes to the thermal equilibrium state, it can bind to the SABRE catalyst precursor again for multiple hyperpolarizations.

[0003] The mechanism study of SABRE hyperpolarization has always attracted much attention. Understanding the spin dynamics behind the SABRE method is of great significance for further optimizing its performance and expanding its application scope. The Pravdivtsev team explored the mechanism of SABRE spin polarization transfer through the study of the polarization transfer field and proposed that the transfer of the para-H2 spin order originates from the spin coherence mixing at the nuclear spin level anti-crossings (LAC), and its generation is most effective at low magnetic fields. In addition, the spectral peaks of metal hydride complexes located at high fields can be used to determine the structure after the ligand and para-H2 bind to the catalyst precursor, especially in the presence of double ligands and multiple ligands. The Knecht team also detected the short-lived hydride intermediate [Ir(IMes)(Py)3(H)2]Cl in the catalytic cycle of metal complexes by chemical exchange saturation transfer (CEST) NMR technology. These complexes are usually difficult to observe because of their low concentration and reversible ligand exchange with the main complex. In addition, exchange spectroscopy (EXSY) and density functional theory were also used to study the stability and mechanism of fast hydrogen exchange in these complexes, and it was found that this process is driven by the dissociation of the ligand, forming a key five-coordinate intermediate. This complex intermediate can be used as a special sensor, and its hydride chemical shift and corresponding hyperpolarization level can characterize the binding of the ligand and its strength. In addition, some researchers have also used 1 1H NMR and 2D TOCSY spectra to characterize the spectral peaks of the complexes generated during the SABRE hyperpolarization process.

[0004] The above studies are all about the detection of hydride intermediates formed after introducing para-H2. Recently, it was reported in the literature that before introducing para-H2, the substrate had replaced the Cl atom in the Ir-based catalyst precursor [IrCl(COD)(Imes)] (Imes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, COD = cycloocta-1,5-diene) and coordinated to the catalyst precursor, and it was proposed that the formation of this complex might be related to the hyperpolarization of this molecule. Therefore, the detection of this complex is crucial for studying the mechanism of SABRE hyperpolarization. Two-dimensional diffusion ordered spectroscopy (2D DOSY) is an NMR spectroscopy technique that realizes the virtual separation of mixtures according to the different self-diffusion coefficients of analytes. According to the differences in self-diffusion coefficients caused by differences in molecular weight or particle size, the components in the mixture can be separated in the diffusion dimension, realizing the virtual separation of the mixture, and it is widely used to study natural mixtures and pharmaceutical preparations and evaluate the number and types of species in solution. In addition, according to our literature review, there is currently no report on the detection of SABRE intermediate complexes by 2D DOSY spectroscopy method.

[0005] Therefore, the present invention proposes a method for detecting the formation of SABRE intermediates by substrate coordination with the catalyst precursor through 2D DOSY, that is, detecting the SABRE intermediates generated after the substrate binds to the catalyst precursor by 2D DOSY spectroscopy. Summary of the Invention

[0006] The object of the present invention is to overcome the defects existing in the prior art and provide a method that can be used to detect the formation of SABRE intermediates by substrate coordination with the catalyst precursor, and can be used to judge which compound binds to the SABRE catalyst precursor to generate SABRE intermediates.

[0007] In order to achieve the above object, one of the technical solutions of the present invention is: a method for detecting the formation of SABRE intermediates by substrate coordination with the catalyst precursor, including the following steps:

[0008] (1) Prepare the NMR sample to be measured: Mix the Ir-based catalyst precursor, the substrate, and the substrate and the Ir-based catalyst precursor with deuterated methanol respectively to obtain different samples to be measured;

[0009] (2) Collect one-dimensional 1 1H NMR spectra: Place the prepared samples to be measured in a 500 MHz Varian NMR nuclear magnetic resonance spectrometer respectively, perform field homogenization at room temperature to make the magnetic field as uniform as possible; use a conventional one-dimensional single-pulse sequence to collect one-dimensional1 1H NMR spectrum was obtained to get information such as the line width of the spectral line and the magnetic field uniformity. This one-dimensional 1 1H NMR spectrum was used for spectral peak assignment and the chemical shift dimension projection spectrum of the 2D DOSY spectrum. The spectral peaks were assigned by comparing the one-dimensional 1H NMR spectrum with the predicted spectrum by ChenDraw and integrating the spectral peaks, etc. In the 2D DOSY spectrum, the 1H NMR spectrum was set as the chemical shift dimension projection spectrum (F2 dimension, horizontal axis) by Mestrenova.

[0010] (3) Collect 2D DOSY spectrum: Call the BPPLED sequence on the nuclear magnetic resonance spectrometer to collect the 2D DOSY spectrum and set the number of data points in the diffusion dimension. In addition to meeting the best effect of balancing resolution and signal-to-noise ratio, the experimental parameters used also need to make the signal decay sufficiently.

[0011] (4) Use MestReNova software (Version 14.0) to process the collected original FID data, including phase adjustment, baseline correction, and DOSY transformation, to obtain a high-resolution 2D DOSY spectrum.

[0012] (5) Assign the 2D DOSY spectral peaks according to the one-dimensional hydrogen spectrum, and extract the self-diffusion coefficients of the spectral peaks with the same diffusion rate. All DOSY spectra were processed and sorted in the same way.

[0013] (6) Assign the DOSY spectral peaks of the samples according to the 1H NMR and DOSY spectra of the Ir-based catalyst precursor, the substrate, and the mixture of the substrate and the Ir-based catalyst precursor, analyze the spectral peaks of the self-diffusion coefficients in the samples and the sources of the compounds, and judge the binding states of the compounds and the compounds co-diffusing with the Ir-based catalyst precursor. 1 1H NMR and DOSY spectra of the samples were used to assign the DOSY spectral peaks, analyze the spectral peaks of the self-diffusion coefficients in the samples and the sources of the compounds, judge the binding states of the compounds, and the compounds co-diffusing with the Ir-based catalyst precursor.

[0014] In a preferred embodiment of the present invention, in the step (1), the concentration of the Ir-based catalyst precursor in deuterated methanol is 4 - 6 mM, and the concentration of the substrate is 40 - 60 mM.

[0015] In a preferred embodiment of the present invention, in the step (1), the substrate is a compound containing a group that can coordinate to the catalyst precursor.

[0016] Further, the compound containing a group that can coordinate to the catalyst precursor includes pyridine and its derivatives or amines containing N atoms.

[0017] In a preferred embodiment of the present invention, in the step (2), the conventional 1H NMR spectrum experiments include pre-experimental tuning, field locking, and field shimming. The collected spectra are used to confirm parameters such as magnetic field uniformity and spectrum appearance, as well as to attribute spectrum peaks.

[0018] In a preferred embodiment of the present invention, the conventional one-dimensional pulse sequence in step (2) is a one-dimensional pulse sequence provided by the nuclear magnetic resonance spectrometer, which is composed of a non-selective π / 2 radio frequency pulse and a sampling period, and its purpose is to check the uniformity of the magnetic field and provide a basis for setting the spectrum width parameters. The acquired one-dimensional hydrogen spectrum is used for peak attribution and as the F2-dimensional projection spectrum of the 2D DOSY spectrum.

[0019] In a preferred embodiment of the present invention, the pulse sequence used for 2D DOSY sampling in step (3) is BPPLED (bipolar gradient longitudinal eddy current delay), which belongs to the spin echo or excitation echo technology under the pulse field gradient effect; the parameters that need to be optimized in the BPPLED sequence are: diffusion time, gradient field action time and intensity; because the sequence is sensitive to the molecular weight of the molecule, the diffusion rates of molecules with different molecular weights are different, so it is necessary to select appropriate diffusion time, gradient field action time and gradient field array according to the molecular size so that the signal intensity attenuation presents a better curve; the key parameters in the pulse sequence are reasonably set, in addition to achieving the effect of taking into account the best resolution and signal-to-noise ratio, it is also necessary to optimize the experimental parameters for different samples to make the signal fully attenuated (spectral peak intensity variation range: 95% to 5%), so as to obtain the 2D DOSY free induction decay (FID) signal of the above-mentioned sample.

[0020] In a preferred embodiment of the present invention, the number of diffusion dimension data points in step (3) is set to 32.

[0021] In a preferred embodiment of the present invention, the data processing in step (4) requires processing the collected FID signal, including phase adjustment, baseline correction, and DOSY transformation, to obtain a high-resolution 2D DOSY spectrum; the two dimensions of the 2D DOSY spectrum are the chemical shift dimension (F2 dimension, horizontal axis) and the self-diffusion coefficient dimension (F1 dimension, vertical axis), which respectively provide the chemical shift information of the observed nucleus (with 1 H NMR spectrum) and the self-diffusion coefficient (D) or the logarithm of the self-diffusion coefficient (logD) which is related to the molecular weight of the molecule.

[0022] In a preferred embodiment of the present invention, in step (5), the peak attribution is to identify and recognize the spectral peaks to confirm the source compound. The extraction of the self-diffusion coefficient refers to extracting their self-diffusion coefficients respectively according to the spectral peak characteristics of the diffusion dimension. The diffusion dimension projection spectrum is the spectral peak projection of different self-diffusion coefficients in the diffusion dimension. Draw a straight line along the horizontal axis through the center of the peak, and the intersection point with the vertical axis (self-diffusion coefficient dimension) is the self-diffusion coefficient value (D or logD) corresponding to the peak. Components of different sizes have different self-diffusion coefficients.

[0023] In a preferred embodiment of the present invention, in step (6), according to the 1 HNMR spectrum for peak attribution. After clarifying the peak attribution, attribute the spectral peaks with different diffusion coefficients. By comparing the changes in the self-diffusion coefficients before and after adding the catalyst precursor and the source of the compounds with the same self-diffusion coefficient, judge the binding state of the substrate and the substrate that binds to the catalyst precursor to form the SABRE intermediate.

[0024] After the substrate and the catalyst precursor are mixed, the substrate that can coordinate with the catalyst precursor will automatically coordinate to form the SABRE intermediate.

[0025] To achieve the above object, the second technical solution of the present invention is: an application of a method for detecting the formation of a SABRE intermediate complex by a substrate coordinating a catalyst precursor in detecting the formation of a SABRE intermediate complex by a substrate coordinating a catalyst precursor.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1. Compared with the prior art method of judging the SABRE intermediate by 2D spectrum, the 2D DOSY spectrum of the present invention has the advantages of time-saving, simple and intuitive. By comparing the changes in the self-diffusion coefficients of the substrate before and after binding to the catalyst precursor and the phenomenon that the bound substrate and the catalyst precursor diffuse at the same diffusion rate, it is possible to judge the substrate that binds to the catalyst precursor to form the SABRE intermediate.

[0028] 2. The present invention can be used to analyze and compare and judge the substrates that can bind to the catalyst precursor to form the SABRE intermediate, and further judge the binding ability and binding strength of different substrates and the catalyst precursor in this system, which is of great help for analyzing the mechanism of the SABRE hyperpolarization process.

[0029] 3. The nuclear magnetic resonance pulse sequence adopted by the present invention is the BPPLED sequence. This sequence is simple to operate and can be implemented on a high-resolution NMR spectrometer equipped only with a z-axis gradient probe. Different from general 2D NMR spectroscopy methods, 2D DOSY spectroscopy belongs to pseudo-two-dimensional spectroscopy, with a short sampling time, intuitive and easy to judge, and is suitable for the study of intermolecular interactions and dynamic processes, having significant advantages in the study of the SABRE hyperpolarization process and mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The BPPLED pulse sequence used in the present invention;

[0031] Figure 2 (a) The 1H NMR spectrum of 3-pyridinecarboxaldehyde (substrate) in deuterated methanol, the structural formulas and proton numbers of 3-pyridinecarboxaldehyde (substrate, L1) and hemiacetal product (L2), and (b) is the hemiacetal reaction equation; 1 The 2D DOSY spectra of different systems of the present invention. (a) The 2D DOSY spectrum of the Ir-based catalyst precursor system, (b) the 2D DOSY spectrum of the pyridine (substrate) + Ir-based catalyst precursor mixture system, (c) the 2D DOSY spectrum of the 3-pyridinecarboxaldehyde (substrate) system, and (d) the 2D DOSY spectrum of the 3-pyridinecarboxaldehyde (substrate) + Ir-based catalyst precursor mixture system;

[0032] Figure 3 The 2D DOSY spectra of different systems of the present invention. (a) The 2D DOSY spectrum of the Ir-based catalyst precursor system, (b) the 2D DOSY spectrum of the pyridine (substrate) + Ir-based catalyst precursor mixture system, (c) the 2D DOSY spectrum of the 3-pyridinecarboxaldehyde (substrate) system, and (d) the 2D DOSY spectrum of the 3-pyridinecarboxaldehyde (substrate) + Ir-based catalyst precursor mixture system;

[0033] Figure 4 Schematic diagram of the substrate binding to the SABRE catalyst precursor to form an intermediate complex in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be described in more detail below with reference to the accompanying drawings and specific embodiments. However, the protection scope of the present invention is not limited to these embodiments.

[0035] The Ir-based catalyst precursor and 3-pyridinecarboxaldehyde used in the following examples were all purchased from Shanghai Jizhi Biochemical Technology Co., Ltd.; deuterated methanol and pyridine were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. The above reagents were used directly without any pretreatment.

[0036] Example 1

[0037] This example is applicable to the detection of the SABRE intermediate complex formed by the binding of the substrate to the catalyst precursor using the 2D DOSY spectroscopy method:

[0038] (1) Mix the Ir-based catalyst precursor, 3-pyridinecarboxaldehyde, pyridine, the Ir-based catalyst precursor and 3-pyridinecarboxaldehyde, and the Ir-based catalyst precursor and pyridine with the solvent CD3OD (deuterated methanol) respectively to form mixed solutions, and put them into white transparent sample bottles. The concentrations of the substrates 3-pyridinecarboxaldehyde and pyridine in CD3OD (deuterated methanol) are both 50 mM, and the concentration of the Ir-based catalyst precursor is 5 mM; Shake the above solutions well to ensure complete dissolution in the glove box.

[0039] (2) Sample detection: Place the prepared experimental samples to be tested in an NMR nuclear magnetic resonance spectrometer respectively, perform shimming to ensure the spectral resolution, and collect a 1 1H NMR spectrum using a conventional one-dimensional single-pulse sequence to obtain the line width of the spectrum, which provides a basis for setting the spectral width parameter. Set the experimental parameters as the spectral width sw of the direct dimension to be 8 kHz, the number of accumulations nt to be 1, the pulse flip angle to be 30°, the sampling time at to be 1 s, and the relaxation delay d1 to be 5 s, and then start collecting the conventional one-dimensional 1 1H NMR spectrum; Call out the BPPLED pulse sequence ( Figure 1 ), and set the experimental parameters according to the concentration of the sample and the 1 distribution range of the 1H NMR spectral peaks. The experimental parameters are that the spectral width sw of the direct dimension is 8 kHz, the number of accumulations nt is 8, the number of dummy scans ss is 16, the sampling time at is 1 s, and the relaxation delay d1 is 5 s. Since the solvent peak is strong, in the experiment, the water suppression module of the BPPLED pulse sequence is turned on to suppress the solvent peak. The typical diffusion module parameter settings are as follows: the diffusion time Δ is 0.1 s, the gradient field application time δ is 0.002 s, the turbo delay Te is 0.005 s, the value of the gradient field strength g is between 2 and 40 G / cm, and 32 diffusion dimension data points are set, that is, 32 gradient field strength values ， The numerical value is adjusted according to the attenuation situation of different samples; Appropriate parameters make the spectral peaks fully attenuated, and then data sampling is performed.

[0040] (3) Experimental data processing

[0041] Perform Fourier transform, manual phase adjustment, and multi-point baseline correction on the one-dimensional hydrogen spectrum collected in step (2) using MestReNova (Version 14.0) software; In order to assign the spectral peaks of the sample solution, first predict the 1H NMR chemical shifts of the Ir-based catalyst precursor, 3-pyridinecarboxaldehyde, pyridine, and the solvent deuterated methanol in ChemDraw respectively, and then assign the spectral peaks in combination with the literature; For the BPPLED spectrum, use the advanced DOSY spectrum conversion of MestReNova, and set the self-diffusion coefficient range from 10 1 to 10 -8 to 10 -10 m2 s -1 , a 2D DOSY plot with chemical shift on the horizontal axis and self-diffusion coefficient on the vertical axis is obtained.

[0042] Figure 2 (a) shows the 1 1H NMR spectrum of 3-pyridinecarboxaldehyde (substrate) in deuterated methanol, the structural formulas and proton numbering of 3-pyridinecarboxaldehyde (substrate, L1) and hemiacetal product (L2), Figure 2 (b) is the hemiacetal reaction equation; after assignment, it can be found that in addition to a set of proton peaks of 3-pyridinecarboxaldehyde, there is another set of proton spectral peaks, which are found to come from the hemiacetal product formed by the reaction of 3-pyridinecarboxaldehyde with deuterated methanol after analysis. 3-pyridinecarboxaldehyde and the hemiacetal product are named L1 and L2 respectively.

[0043] Figure 3 The 2D DOSY spectra of different systems are shown. The top and left sides of the spectra are 1 1H NMR spectrum and diffusion dimension projection spectrum respectively, and the self-diffusion coefficient can be directly read from the spectrum. For easy comparison, all spectra use the same range of self-diffusion coefficients and a reference line is drawn at 1.0×10 -9 m 2 s -1 to observe the change of the self-diffusion coefficient. From Figure 3 (a), it can be found that all the spectral peaks of the Ir-based catalyst precursor are on the same diffusion line in the 2D DOSY spectrum, and the self-diffusion coefficient read at this point is 8.61×10 -10 m 2 s -1 . Figure 3 (b) is the 2D DOSY spectrum of pyridine in deuterated methanol solution. From the 1 1H NMR spectrum at the top, it can be seen that in addition to the spectral peaks of free pyridine, there is a set of weaker spectral peaks at a higher field. By consulting the literature, it is known that they come from the pyridine molecules in the bound state after binding with the Ir-based catalyst precursor. In the diffusion dimension projection of the 2D DOSY spectrum, we can see two clear self-diffusion spectral peaks. One comes from the self-diffusion of free pyridine molecules, with D being 1.64×10 -9 m 2 s -1 , and the other clearly shows that it comes from the catalyst and the bound pyridine molecules, with D being 7.41×10 -10 m 2 s -1 . To distinguish the two states of pyridine molecules, an "f" is added before the name of the free-state protons for distinction, as shown in the Figure 3 1H NMR spectrum assignment at the top of the 2D DOSY spectrum in (b). By comparisonFigure 3 (a) and Figure 3 The self-diffusion coefficients of the catalyst precursors in (b) show that the D value of the catalyst precursor combined with pyridine molecules is smaller. This is mainly because after the pyridine molecules replace the Cl atoms, the molecular weight of the catalyst precursor increases and the diffusion coefficient decreases.

[0044] Figure 3 (c) is the 2D DOSY spectrum of 3-pyridinecarboxaldehyde in deuterated methanol solution. According to Figure 2 the attribution results in, it can be determined that the two self-diffusion coefficients belong to L1 and L2 respectively. Figure 3 (d) is the 2D DOSY of the deuterated methanol solution of the mixture of 3-pyridinecarboxaldehyde (substrate) + Ir-based catalyst precursor. It can be found that there are a total of three spectral peaks in the diffusion dimension, corresponding to three self-diffusion rates. After attribution, it is found that the self-diffusion coefficients of the above two spectral peaks come from L1 and L2 respectively, and their self-diffusion coefficients are basically the same as those of 3-pyridinecarboxaldehyde alone in methanol solution. In addition, we also observed that the third self-diffusion coefficient comes from some small peaks beside the catalyst and L2. As can be seen from the results of pyridine in Figure 3 (b), these small peaks beside L2 come from the bound L2 combined with the catalyst precursor. Their co-diffusion with the catalyst precursor fully proves that L2 replaces the Cl atom and binds to the catalyst precursor, while L1 does not bind to the catalyst precursor. This also shows that L2 has higher activity when binding to the catalyst precursor. Similarly, in order to distinguish the two states of L2, the free L2 is named fL2, such as Figure 3 the 1 H NMR spectrum attribution at the top of the 2D DOSY spectrum in (d).

[0045] Figure 4 is a schematic diagram of the formation of an intermediate complex by the substrate binding to the SABRE catalyst precursor. The hemiacetal product L2 replaces the Cl atom on the Ir-based catalyst precursor and uses the N atom on L2 as the coordination site.

[0046] In summary, the BPPLED sequence can be used to monitor the intermediate complex generated by the binding of the substrate to the catalyst precursor, and direct evidence of the binding of the ligand to the catalyst precursor is obtained. In addition, as can be seen from the results of this example, when there is more than one substrate in the system, this method can also judge which substrate binds to the catalyst precursor and its strength, providing important intermediate process information for studying the SABRE hyperpolarization mechanism.

[0047] The above embodiments are only the optimized implementation methods of the present invention, used to exemplarily illustrate the principles and effects of the present invention, rather than to limit the present invention. It should be noted that for any person skilled in the art, without departing from the spirit and scope of the present invention, modifications made to the above embodiments should also be regarded as within the protection scope of the present invention.

Claims

1. A method for detecting the formation of SABRE intermediates from substrate-coordinated catalyst precursors, characterized in that, It includes the following steps: (1) Prepare the NMR sample to be measured: Mix the Ir-based catalyst precursor, the substrate, and the substrate and the Ir-based catalyst precursor with deuterated methanol respectively to obtain different samples to be measured. The concentration of the Ir-based catalyst precursor in the deuterated methanol is 4-6 mM, and the concentration of the substrate is 40-60 mM. The substrate is a compound containing a moiety that can coordinate to the catalyst precursor. The compound containing a moiety that can coordinate to the catalyst precursor includes pyridine and its derivatives or amines containing N atoms; (2) Collect one-dimensional 1 HNMR spectrum: Place the prepared sample to be measured in step (1) into a nuclear magnetic resonance spectrometer respectively. After shimming at room temperature, use a conventional one-dimensional single pulse sequence to collect one-dimensional 1 HNMR spectrum; (3) Collect the 2D DOSY spectrum: Call the BPPLED sequence on the nuclear magnetic resonance spectrometer to set parameters to collect the 2D DOSY spectrum and set the number of data points in the diffusion dimension; (4) Obtain the high-resolution 2D DOSY spectrum: Process the original FID data of the 2D DOSY spectrum collected in step (3) to obtain a high-resolution 2D DOSY spectrum; (5) Extraction of attributed spectral peaks from diffusion coefficients: Based on the one-dimensional 1 The 2D DOSY peaks collected in step (3) are assigned using the H NMR spectrum, and the self-diffusion coefficients of the peaks with the same diffusion rate are extracted; (6) Result processing and analysis: Assign the DOSY spectrum peaks of different samples, analyze the peaks of the self-diffusion coefficient in the samples and the compound sources, and judge the binding state of the compounds and the compounds that co-diffuse with the SABRE catalyst precursor.

2. The method for detecting the formation of a SABRE intermediate by a substrate coordination catalyst precursor according to claim 1, wherein The conventional one-dimensional pulse sequence in step (2) is the one-dimensional pulse sequence built into the nuclear magnetic resonance spectrometer, which consists of a non-selective π / 2 radio frequency pulse and a sampling period.

3. The method for detecting the formation of a SABRE intermediate by a substrate coordination catalyst precursor as claimed in claim 1, wherein In step (3), the number of data points in the diffusion dimension is set to 32.

4. The method for detecting the formation of a SABRE intermediate from a substrate coordination catalyst precursor according to claim 1, characterized in that, The data processing in step (4) includes phase adjustment, baseline correction, and DOSY transformation.

5. The method for detecting the formation of a SABRE intermediate from a substrate coordination catalyst precursor according to claim 1, characterized in that, In step (5), the spectrum peak assignment is to identify and recognize the spectrum peaks and confirm the source compounds. The extraction of the self-diffusion coefficient is to extract their self-diffusion coefficients respectively according to the spectrum peak characteristics in the diffusion dimension.

6. The method for detecting the formation of a SABRE intermediate by a substrate coordination catalyst precursor as described in claim 1, wherein, In step (6), by comparing the changes in the self-diffusion coefficient before and after adding the catalyst precursor and the compound sources with the same self-diffusion coefficient, judge the binding state of the substrate and which substrate combines with the catalyst precursor to form the SABRE intermediate.

7. Use of the method according to any one of claims 1-6 in detecting the formation of a SABRE intermediate complex by coordinating a substrate with a catalyst precursor.

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