Method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and proton nuclear magnetic resonance spectroscopy

Abstract

The present invention relates to the technical field of charge-assisted hydrogen bond recognition, specifically a method for recognizing charge-assisted hydrogen bonds in infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. The present invention uses oxygen-rich or nitrogen-rich materials with different isoelectric points as models and as adsorbents to adsorb ionizable organic compounds with different pK a values, obtaining composite material samples. Any short and strong hydrogen bonds or low-energy-barrier hydrogen bonds similar to CAHB formed between the oxygen-rich or nitrogen-rich materials and IOCs can be recognized and tested by the method of the present application through FTIR and 1 HNMR, thereby realizing direct recognition and testing of the formation of CAHB at the molecular scale.

Description

Technical Field

[0001] The present invention relates to the technical field of charge-assisted hydrogen bond recognition, and specifically to a method for recognizing charge-assisted hydrogen bonds in infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. Background Art

[0002] Charge-assisted hydrogen bond (CAHB) plays an important role in molecular self-assembly, biocatalysis, fuel cells, and environmental remediation applications. CAHB is based on ordinary hydrogen bond (OHB, based on electrostatic interaction), and is accompanied by covalent bond and Coulomb interaction to form an unusually strong and short hydrogen bond, and has the covalent bond property of 3-center - 4-electron. Specifically, the formation of CAHB is due to the existence of two energy-equivalent valence bond resonance forms, thus forming a short and strong hydrogen bond. In a given CAHB structure, the absolute value (|ΔpK a |) of the difference in dissociation constants between the H donor group and the H acceptor group is a key indicator for the formation of CAHB, that is, when |ΔpK a |<5.0, it is possible to form CAHB, and its strength will increase as |ΔpK a | decreases; when |ΔpK a |≥5.0, what is formed is OHB, and its strength is only 1 / 4 of that of CAHB.

[0003] Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance spectroscopy ( 1 1H NMR) are important spectroscopic techniques for characterizing hydrogen bonds. Especially for the formation of OHB, the electron cloud around the H nucleus will be attracted by the H acceptor, resulting in a decrease (red shift) in the stretching vibration frequency of the chemical bond at the H donor in Fourier transform infrared spectroscopy (FTIR); the formation of OHB also weakens the electron shielding effect around the H nucleus, resulting in a shift of the chemical shift of H in 1 1H NMR to the low field (the chemical shift increases to 10 - 13 ppm); although the techniques for detecting OHB by Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance spectroscopy ( 1 1H NMR) are mature, there is currently no effective method for recognizing CAHB.

[0004] The specific reason is that: different from OHB, CAHB has the characteristics of covalent bonds, and its formation may show different phenomena in FTIR and 1 1H NMR characterizations, and different indicator peaks may appear in FTIR and 1 1H NMR during the formation process, such as a blue shift (increase in stretching vibration frequency) of the chemical bond at the H donor in FTIR, and H in 1In the HNMR, a chemical shift appears in the very low-field region (≈18 ppm). Therefore, there is currently no effective method to characterize CAHB. Thus, a method for identifying charge-assisted hydrogen bonds by using FTIR and 1 HNMR characterization techniques is needed. Summary of the Invention

[0005] Aiming at the deficiencies of the above-mentioned existing technologies, the purpose of the present invention is to provide a method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy. The present invention uses infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy to realize the identification and testing of the formation of CAHB.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy, comprising the following steps:

[0008] Step 1: Preparation of the IOCs stock solution:

[0009] Using H 2 O and D 2 O as solvents respectively, prepare two kinds of IOCs stock solutions with a concentration of 50 - 200 mg / L;

[0010] Step 2: Prepare composite material samples of oxygen-rich or nitrogen-rich materials adsorbed with IOCs, where the IOCs are from the IOCs stock solution;

[0011] Specifically, mix the two kinds of IOCs stock solutions with oxygen-rich or nitrogen-rich materials respectively, centrifuge, and after solid-liquid separation and freeze-drying, obtain composite material samples, where the mass ratio of the solute of the IOCs stock solution to the oxygen-rich or nitrogen-rich material is 400 - 1600:1;

[0012] Step 3: Charge-assisted hydrogen bond identification method:

[0013] Perform 1 H NMR measurement and FTIR measurement on the composite material samples;

[0014] After 1 HNMR measurement, compared with the oxygen-rich or nitrogen-rich material without adsorbed IOCs, the composite material sample with H 2 O as the solvent has a new characteristic peak in the very low-field region, but for the composite material sample with D 2 O as the solvent, this new characteristic peak disappears;

[0015] After FTIR measurement, the composite material sample with H 2 O as the solvent measures a hydroxyl peak (-OH) and an amino peak (-NH 2) blue shift, and the main characteristic peak appears at a higher frequency than the hydroxyl peak and the amino peak frequencies.

[0016] Preferably, the first step further includes the preparation of the background solution, and the specific method is as follows:

[0017] Respectively using H 2 O and D 2 O as solvents, and using NaCl or CaCl 2 as solutes to prepare the background solution of the simulated natural water body; the IOCs stock solution uses the two background solutions as solvents respectively;

[0018] Among them, the concentration of the background solution is 0 to 0.02 mol / L; the mass ratio of the solute of the IOCs stock solution to the volume of the background solution is 50 to 200 mg: 1 L.

[0019] Preferably, the pH values of the background solution and the IOCs stock solution are both adjusted to: greater than the (pKa value + 2) corresponding to the ionizable organic compound, and generally the pH is about 3 - 12. At this time, it is ensured that the IOCs exist in one form.

[0020] Preferably, the solute in the IOCs stock solution is an ionizable organic compound.

[0021] Preferably, the ionizable organic compounds include clofibric acid, paracetamol, p-aminobenzoic acid, sulfamethazine, benzoic acid and other ionizable organic compounds containing hydroxyl, carboxyl and amino groups.

[0022] Preferably, the oxygen-rich or nitrogen-rich materials in the second step include oxidized multi-walled carbon nanotubes (O-CNTs), amino-functionalized multi-walled carbon nanotubes (N-CNTs), graphene oxide, oxidized minerals (such as nano-silica Nano-SiO 2 and nano-aluminum oxide Nano-Al 2 O 3 ), artificial resin (styrene-divinylbenzene-based ethylenediamine resin).

[0023] Preferably, the mixing method in the second step is: in a constant temperature oscillator, shake in the dark at 20 - 25 °C and 150 - 180 rmp for 48 h or more.

[0024] Preferably, the 1 method for HNMR measurement is: after ultrasonically mixing the composite material sample with deuterated dimethyl sulfoxide, add it to a nuclear magnetic resonance tube and measure it on a 1 H NMR detector.

[0025] Preferably, the method for FTIR measurement is: using H 2The composite material sample with O as the solvent is mixed with KBr and ground. After pressing into a tablet, it is measured on an FTIR detector.

[0026] Preferably, the FTIR measurement frequency range is 1200 - 4000 cm -1 , the resolution ≥ 0.4 cm -1 , the wavenumber accuracy is 0.01 cm -1 , and the wavelength accuracy is 0.1 cm -1 .

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1. The present invention provides a method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy. Any short and strong hydrogen bonds or low-barrier hydrogen bonds similar to CAHB formed between oxygen-rich or nitrogen-rich materials and IOCs can be identified and tested by the method of the present application through FTIR and 1 H NMR (including H / D isotope substitution), and then directly identify and test the formation of CAHB at the molecular scale.

[0029] 2. Different from OHB, CAHB, as a short and strong hydrogen bond with covalent bond characteristics, may show different indicator peaks in FTIR and 1 H NMR during the formation process, such as the blue shift (increase in stretching vibration frequency) of the chemical bond at the H donor in FTIR and the chemical shift of H in 1 H NMR in the extremely low-field region (≈18 ppm); in addition, according to the characteristic that solvent H 2 O participates in the formation of CAHB, after H / D isotope substitution (replacing D 2 O with H 2 O), 1 the chemical shift in the extremely low-field region of H NMR disappears, so as to identify the formation of CAHB. The solution of the above technical problems is beneficial to further clarify the molecular mechanism of CAHB, which is of great significance for its applications in materials, biology, environment, energy and other aspects.

[0030] 3. The present invention selects oxygen-rich or nitrogen-rich materials with different isoelectric points (PZC) (carbon nanotubes, nano-silica Nano-SiO 2 , nano-aluminum oxide Nano-Al 2 O 3 ) as model adsorbents to adsorb ionizable organic compounds (IOCs) with different pK a to form different types of CAHB (|ΔpK a | < 5.0). On the one hand, according to solvent H 2The characteristics of O participating in the formation of CAHB were studied by H / D isotope substitution (replacing D 2 O with H 2 O), and 1 1H NMR was used to clarify the essence of CAHB formation. On the other hand, FTIR was used to explore the direct spectral evidence for the formation of CAHB. Brief Description of the Drawings

[0031] Figure 1 Amplified comparison 1H NMR spectra of O-CNTs in Example 1 of the present invention before and after adsorbing CA in water and deuterated water; 1

[0032] Figure 2 Full 1H NMR spectra of O-CNTs in Example 1 of the present invention before and after adsorbing CA in water and deuterated water; 1

[0033] Figure 3 Combined 1H NMR spectra of O-CNTs in Example 1 of the present invention before and after adsorbing CA in water and deuterated water; 1

[0034] Figure 4 FTIR comparison spectra of O-CNTs in Example 1 of the present invention before and after adsorbing CA in water;

[0035] Figure 5 Amplified comparison 1H NMR spectra of N-CNTs in Example 2 of the present invention before and after adsorbing ACT in water and deuterated water; 1

[0036] Figure 6 Full 1H NMR spectra of N-CNTs in Example 2 of the present invention before and after adsorbing ACT in water and deuterated water; 1

[0037] Figure 7 Combined 1H NMR spectra of N-CNTs in Example 2 of the present invention before and after adsorbing ACT in water and deuterated water; 1

[0038] Figure 8 FTIR comparison spectra of N-CNTs in Example 2 of the present invention before and after adsorbing ACT in water;

[0039] Figure 9 Amplified comparison 1H NMR spectra of O-CNTs in Example 3 of the present invention before and after adsorbing PABA in water and deuterated water; 1

[0040] Figure 10 Full 1H NMR spectra of O-CNTs in Example 3 of the present invention before and after adsorbing PABA in water and deuterated water; 11H NMR full spectrum;

[0041] Figure 11 1H NMR combined spectra of O-CNTs in Example 3 of the present invention before and after adsorbing PABA in water and deuterium water; 1 1H NMR combined spectra;

[0042] Figure 12 FTIR control spectra of O-CNTs in Example 3 of the present invention before and after adsorbing PABA in water;

[0043] Figure 13 1H NMR enlarged control spectra of N-CNTs in Example 4 of the present invention before and after adsorbing SMR in water and deuterium water; 1 1H NMR enlarged control spectra;

[0044] Figure 14 1H NMR full spectra of N-CNTs in Example 4 of the present invention before and after adsorbing SMR in water and deuterium water; 1 1H NMR full spectra;

[0045] Figure 15 1H NMR combined spectra of N-CNTs in Example 4 of the present invention before and after adsorbing SMR in water and deuterium water; 1 1H NMR combined spectra;

[0046] Figure 16 FTIR control spectra of N-CNTs in Example 4 of the present invention before and after adsorbing SMR in water. Detailed Description of the Invention

[0047] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the protection scope of the present invention is not limited by the specific embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the protection scope of the present invention. The experimental methods described in each embodiment of the present invention are conventional methods unless otherwise specified.

[0048] Example 1

[0049] A method for identifying charge-assisted hydrogen bonds in infrared spectra and nuclear magnetic resonance hydrogen spectra, comprising the following steps:

[0050] Step 1. Preparation of background solution and IOCs stock solution: First, use H 2 2O and D 2 2O to prepare background solutions containing 0.01 mol / L CaCl 2 2, and then use these two background solutions to prepare 200 mg / L stock solutions of clofibric acid (CA, pK a a = 2.90). Then adjust the pH of the background solution and the CA stock solution to 7.0 so that more than 99% of CA exists in the anionic state, and store it in the dark at room temperature;

[0051] Step 2. Sample preparation: First, add 200 mg / L of CA stock solution into an 8 mL glass vial containing 5 mg of oxidized multi-walled carbon nanotubes (O-CNTs, PZC = 3.07). After placing the prepared sample in a thermostatic shaker and shaking it in the dark (temperature: 25 °C, rotation speed: 150 rmp) for 48 h, centrifuge it for 30 min at a rotation speed of 3000 rmp; then pour out the supernatant in the vial and freeze-dry it for 24 h to obtain powder samples (O-CNTs + CA) and (O-CNTs + CA (deuteration)) prepared by O-CNTs adsorbing CA, dry and store them at 50 °C for 1 1H NMR and FTIR characterization. The above adsorption samples are each prepared once in H 2 2O and D 2 2O, and at the same time, use the original O-CNTs sample without adsorbed CA as a blank control (O-CNTs) for FTIR and 1 1H NMR determination;

[0052] Step 3. 1 1H NMR determination: Take out 0.2 mg from each of the above samples (O-CNTs + CA, O-CNTs + CA (deuteration), and O-CNTs), place it in 3 mL of deuterated dimethyl sulfoxide (DMSO-d6), and ultrasonicate it for 30 min. Then, use a pipette to add the above solution into a 5 mm nuclear magnetic resonance tube, and then perform the measurement on a 1 1H NMR (Bruker Ascend 600 MHz, USA), with a resolution of 0.21 HZ and a forward detection broadband (BBO) probe;

[0053] Step 4. FTIR determination: Take out 1.0 mg from the sample (O-CNTs + CA) prepared in H 2 2O and the blank control (O-CNTs) above, mix it with 50 mg of dry KBr and grind it. Use the tablet pressing method to make the mixed KBr and sample into a transparent thin slice, and then put it into an FTIR detector (Tensor 27) for scanning. The measurement frequency range is 1200 - 4000 cm -1 -1, and each sample is scanned 100 times, with a resolution of ≥ 0.4 cm -1 -1; wavenumber accuracy: 0.01 cm -1 -1; wavelength accuracy: 0.1 cm -1 .

[0054] The test results show that:

[0055] As Figures 1-4 shown, the adsorption samples prepared in H 2 2O can be in1 A characteristic peak with a chemical shift of 17.12 ppm was found in the extremely low field region of 1H NMR. However, after deuteration (when H 2 O is replaced by D 2 O), this characteristic peak disappeared, which well identified CAHB and indicated that H 2 O participated in the formation of CAHB;

[0056] FTIR measurement found that a characteristic peak (3787 cm -1 ) was detected at a higher frequency than the -OH peak (3465 cm -1 ). This characteristic peak can be used as direct evidence for the formation of CAHB, that is, the formation of CAHB can be effectively identified.

[0057] Example 2

[0058] A method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and proton nuclear magnetic resonance spectroscopy, comprising the following steps:

[0059] Step 1, preparation of background solution and IOCs stock solution: First, use H 2 O and D 2 O to prepare background solutions containing 0.01 mol / L CaCl 2 (simulating the natural water environment), and then use these two background solutions to prepare 200 mg / L stock solutions of acetaminophen (ACT, pK a = 9.46). Then, adjust the pH of the background solution and the ACT stock solution to 7.0 so that more than 99% of the ACT exists in the molecular state, and store it in the dark at room temperature;

[0060] Step 2, sample preparation: First, add 200 mg / L of the ACT stock solution to an 8 mL glass vial containing 5 mg of amino-functionalized multi-walled carbon nanotubes (N-CNTs, PZC = 8.04). Place the prepared sample in a thermostatic oscillator and shake it in the dark (temperature: 25 °C, rotation speed: 150 rmp) for 48 h, and then centrifuge it for 30 min at a rotation speed of 3000 rmp; then pour out the supernatant in the vial and freeze-dry it for 24 h to obtain powder samples (N-CNTs + ACT) and (N-CNTs + ACT (deuteration)) prepared by N-CNTs adsorbing ACT, dry and store them at 50 °C for 1 1H NMR and FTIR characterization. The above adsorption samples are each prepared once in H 2 O and D 2 O, and at the same time, the original N-CNTs sample without adsorbed ACT is used as a blank control (N-CNTs) for FTIR and 1 1H NMR measurement;

[0061] Step 3: 1 1H NMR measurement: Take out 0.2 mg from each of the above samples (N-CNTs+ACT, N-CNTs+ACT (deuteration), and N-CNTs), place it in 3 mL of deuterated dimethyl sulfoxide (DMSO-d6), and ultrasonicate for 30 min. Then, use a pipette to add the above solution into a 5 mm nuclear magnetic resonance tube, and then measure it on 1 1H NMR (Bruker Ascend 600 MHz, USA), resolution 0.21 HZ; forward detection broadband (BBO) probe;

[0062] Step 4: FTIR measurement: Take out 1.0 mg from each of the above samples (N-CNTs+ACT) prepared from H 2 2O and the blank control (N-CNTs), mix it with 50 mg of dry KBr and grind it. Use the tablet pressing method to make the mixed KBr and sample into a transparent thin film, and then put it into the FTIR detector (Tensor 27) for scanning. The measurement frequency range is 1200 - 4000 cm -1 -1, each sample is scanned 100 times, resolution: ≥0.4 cm -1 -1; wavenumber accuracy: 0.01 cm -1 -1; wavelength accuracy: 0.1 cm -1 .

[0063] The test results show that:

[0064] As Figures 5-8 shown, the adsorbed sample prepared from H 2 2O can find a characteristic peak with a chemical shift of 17.41 ppm in the extremely low field region of 1H NMR, but this characteristic peak disappears after deuteration (after H 1 2O is replaced by D 2 2O), which well identifies CAHB and indicates that H 2 2O participates in the formation of CAHB; 2

[0065] It is found that a characteristic peak (3787 cm 2 -1) is detected at a higher frequency than the -NH -1 peak (3420 cm -1 -1). This characteristic peak can be used as direct evidence for the formation of CAHB, that is, it can effectively identify the formation of CAHB.

[0066] Example 3

[0067] A method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy, comprising the following steps:

[0068] ​Step 1. Preparation of background solution and IOCs stock solution: First, use H 2 O and D 2 O to prepare a background solution containing 0.01 mol / L CaCl 2 (simulating the natural water environment), and then use these two background solutions to prepare 200 mg / L p-aminobenzoic acid (PABA, pK a = 4.77) stock solution respectively. Then adjust the pH of the background solution and PABA stock solution to 7.0 so that more than 99% of PABA exists in the anionic state, and store it in the dark at room temperature;

[0069] Step 2. Sample preparation: First, add 200 mg / L PABA stock solution to an 8 mL glass vial containing 5 mg of oxidized multi-walled carbon nanotubes (O-CNTs, PZC = 3.07). Place the prepared sample in a thermostatic oscillator and shake it in the dark (temperature: 25 °C, rotation speed: 150 rmp) for 48 h, and then centrifuge it for 30 min at a rotation speed of 3000 rmp; then pour out the supernatant in the vial and freeze-dry it for 24 h to obtain a powder sample (O-CNTs+PABA) and (O-CNTs+PABA(deuteration)) prepared by O-CNTs adsorbing PABA. Dry and store it at 50 °C for 1 H NMR and FTIR characterization. The above adsorption samples are each prepared once in H 2 O and D 2 O, and at the same time, use the original O-CNTs sample without adsorbed PABA as a blank control (O-CNTs) for FTIR and 1 H NMR determination;

[0070] Step 3. 1 H NMR determination: Take out 0.2 mg from each of the above samples (O-CNTs+PABA, O-CNTs+PABA(deuteration) and O-CNTs) and place it in 3 mL of deuterated dimethyl sulfoxide (DMSO-d6), ultrasonicate it for 30 min, and then use a pipette to add the above solution to a 5 mm nuclear magnetic resonance tube. Then measure it on a 1 HNMR (Bruker Ascend 600 MHz, USA), with a resolution of 0.21 HZ and a positive detection broadband (BBO) probe;

[0071] Step 4. FTIR determination: Take the above samples from H 21.0 mg was taken from each sample (O-CNTs+PABA) prepared in H₂O and the blank control (O-CNTs), mixed with 50 mg of dry KBr, ground, and made into a transparent thin film using the tablet pressing method. Then it was placed in an FTIR detector (Tensor 27) for scanning, and the measurement frequency range was 1200 - 4000 cm -1 , each sample was scanned 100 times, resolution: ≥0.4 cm -1 ; wavenumber accuracy: 0.01 cm -1 ; wavelength accuracy: 0.1 cm -1 .

[0072] The test results showed that:

[0073] As Figures 9-12 shown, the adsorbed sample prepared in H₂O could find a characteristic peak with a chemical shift of 17.80 ppm in the very low field region of ¹H NMR, but this characteristic peak disappeared after deuteration (after H₂O was replaced by D₂O), which well identified CAHB and indicated that H₂O participated in the formation of CAHB; 2 the adsorbed sample prepared in H₂O could find a characteristic peak with a chemical shift of 17.80 ppm in the very low field region of ¹H NMR, but this characteristic peak disappeared after deuteration (after H₂O was replaced by D₂O), which well identified CAHB and indicated that H₂O participated in the formation of CAHB; 1 ¹H NMR, but this characteristic peak disappeared after deuteration (after H₂O was replaced by D₂O), which well identified CAHB and indicated that H₂O participated in the formation of CAHB; 2 O was replaced by D 2 ₂O) this characteristic peak disappeared, which well identified CAHB, and indicated that H 2 ₂O participated in the formation of CAHB;

[0074] It was found that a characteristic peak (3787 cm -1 ) was detected at a higher frequency than the -OH peak (3465 cm -1 ), and this characteristic peak could be used as direct evidence for the formation of CAHB, that is, the formation of CAHB could be effectively identified.

[0075] Example 4

[0076] A method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy, comprising the following steps:

[0077] Step 1, preparation of background solution and IOCs stock solution: First, background solutions containing 0.01 mol / L CaCl 2 (simulating the natural water environment) were prepared using H₂O and D₂O respectively, and then stock solutions of sulfamethazine (SMR, pK 2 2 =6.80) at 200 mg / L were prepared using these two background solutions respectively. Then the pH of the background solution and the SMR stock solution was adjusted to 5.6 to make more than 99% of the SMR exist in the molecular state, and it was stored in the dark at room temperature;(simulating the natural water environment) were prepared using H₂O and D₂O respectively, and then stock solutions of sulfamethazine (SMR, pK a =6.80) at 200 mg / L were prepared using these two background solutions respectively. Then the pH of the background solution and the SMR stock solution was adjusted to 5.6 to make more than 99% of the SMR exist in the molecular state, and it was stored in the dark at room temperature;

[0078] Step 2. Sample preparation: First, add 200 mg / L of the SMR stock solution into an 8 mL glass vial containing 5 mg of amino-functionalized multi-walled carbon nanotubes (N-CNTs, PZC = 8.04). Place the prepared sample in a thermostatic shaker and shake it in the dark (temperature: 25 °C, rotation speed: 150 rmp) for 48 h. Then, centrifuge it for 30 min at a rotation speed of 3000 rmp. Next, pour out the supernatant in the vial and freeze-dry it for 24 h to obtain powder samples (N-CNTs + SMR) and (N-CNTs + SMR (deuteration)) prepared by adsorbing SMR on N-CNTs. Dry and store them at 50 °C for 1 1H NMR and FTIR characterizations. The above adsorption samples are each prepared once in H 2 2O and D 2 2O. At the same time, use the original N-CNTs sample without adsorbed SMR as a blank control (N-CNTs) for FTIR and 1 1H NMR measurements;

[0079] Step 3. 1 1H NMR measurement: Take out 0.2 mg from each of the above samples (N-CNTs + SMR, N-CNTs + SMR (deuteration), and N-CNTs) and place it into 3 mL of deuterated dimethyl sulfoxide (DMSO-d6). After ultrasonication for 30 min, use a pipette to add the above solution into a 5 mm nuclear magnetic resonance tube. Then, perform the measurement on a 1 1H NMR (Bruker Ascend 600 MHz, USA) with a resolution of 0.21 HZ and a forward detection broadband (BBO) probe;

[0080] Step 4. FTIR measurement: Take out 1.0 mg from each of the above samples (N-CNTs + SMR) prepared in H 2 2O and the blank control (N-CNTs), mix it with 50 mg of dry KBr and grind them. Use the tablet pressing method to make the mixed KBr and sample into a transparent thin film. Then, put it into an FTIR detector (Tensor 27) for scanning. The measurement frequency range is 1200 - 4000 cm -1 -1, and each sample is scanned 100 times with a resolution of ≥ 0.4 cm -1 -1; wavenumber accuracy: 0.01 cm -1 -1; wavelength accuracy: 0.1 cm -1 .

[0081] The detection results show that:

[0082] As Figures 13-16 shown, the adsorption samples prepared in H 2 2O can be 1A characteristic peak with a chemical shift of 17.71 ppm was found in the extremely low-field region of ¹H NMR. However, this characteristic peak disappeared after deuteration (when H 2 O was replaced by D 2 O), which well identified CAHB and indicated that H 2 O participated in the formation of CAHB;

[0083] A characteristic peak was detected at a higher frequency than the -NH 2 peak (3420 cm -1 ⁻¹), and this characteristic peak (3787 cm -1 ⁻¹) can be used as direct evidence for the formation of CAHB, that is, the formation of CAHB can be effectively identified.

[0084] Example 5

[0085] A method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy, comprising the following steps:

[0086] Step 1, preparation of background solution and IOCs stock solution: First, use H 2 O to prepare a background solution containing 0.01 mol / L CaCl 2 (simulating the natural water environment), and then use this background solution to prepare a 200 mg / L stock solution of benzoic acid (BA, pK a = 4.17). Then, adjust the pH of the background solution and the BA stock solution to 7.0 so that more than 99% of the BA exists in the anionic state, and store it in the dark at room temperature;

[0087] Step 2, sample preparation: First, add the 200 mg / L BA stock solution to a 20 mL glass vial containing 20 mg of nano-silica (Nano-SiO 2 , PZC = 2.46). Place the prepared sample in a thermostatic oscillator and shake it in the dark (temperature: 25 °C, rotation speed: 150 rmp) for 48 h, and then centrifuge it at a rotation speed of 3000 rmp for 30 min; then pour out the supernatant in the vial and freeze-dry it for 24 h to obtain a powder sample prepared by Nano-SiO 2 adsorbing BA. Dry it at 50 °C and store it for FTIR characterization. At the same time, use the original Nano-SiO 2 sample without adsorbing BA as a blank control for FTIR measurement;

[0088] Step 3, FTIR measurement: The above-mentioned sample prepared from H 21.0 mg was taken from each sample prepared in O and mixed with 50 mg of dry KBr and ground. The mixed KBr and sample were made into a transparent thin film by the tablet pressing method, and then put into an FTIR detector (Tensor 27) for scanning. The measurement frequency range was 1200 - 4000 cm -1 , each sample was scanned 100 times, resolution: ≥0.4 cm -1 ; wavenumber accuracy: 0.01 cm -1 ; wavelength accuracy: 0.1 cm -1 .

[0089] The test results showed that:

[0090] In this example, only FTIR measurement was carried out. It was found that a characteristic peak (3660 cm -1 ) was detected at a higher frequency than the -OH peak (3457 cm -1 ). This characteristic peak can be used as direct evidence for the formation of CAHB, that is, the formation of CAHB can be effectively identified.

[0091] Example 6

[0092] A method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and proton nuclear magnetic resonance spectroscopy, comprising the following steps:

[0093] Step 1, preparation of background solution and IOCs stock solution: First, use H 2 O to prepare a 200 mg / L sulfamethazine (SMR, pK a = 6.80) stock solution, and then adjust the pH of the background solution and the SMR stock solution to 5.6 so that more than 99% of the SMR exists in the molecular state, and store it in the dark at room temperature;

[0094] Step 2, sample preparation: First, add the 200 mg / L SMR stock solution to a 20 mL glass vial containing 20 mg of nano-aluminum oxide (Nano-Al 2 O 3 , PZC = 7.12). After placing the prepared sample in a constant temperature oscillator and shaking it in the dark (temperature: 25 °C, rotation speed: 150 rmp) for 48 h, centrifuge it at a rotation speed of 3000 rmp for 30 min; then pour out the supernatant in the vial and freeze-dry it for 24 h to obtain a powder sample prepared by Nano-Al 2 O 3 adsorbing SMR. Dry and store it at 50 °C for FTIR characterization. At the same time, use the original Nano-Al 2 O 3 sample without adsorbed SMR as a blank control for FTIR measurement;

[0095] Step 3. FTIR measurement: Take out 1.0 mg from each of the above-prepared samples from H 2 O, mix it with 50 mg of dry KBr and grind. Use the tablet pressing method to make the mixed KBr and sample into a transparent thin film, and then put it into an FTIR detector (Tensor 27) for scanning. The measurement frequency range is 1200 - 4000 cm -1 , each sample is scanned 100 times, resolution: ≥0.4 cm -1 ; wavenumber accuracy: 0.01 cm -1 ; wavelength accuracy: 0.1 cm -1 .

[0096] The test results show that:

[0097] In this embodiment, only FTIR measurement is performed. The results show that a characteristic peak (3730 cm -1 ) is detected at a higher frequency than the -OH peak (3436 cm -1 ). This characteristic peak can be used as direct evidence for the formation of CAHB, that is, the formation of CAHB can be effectively identified.

[0098] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. Method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and proton nuclear magnetic resonance spectroscopy, Characterized in that, Comprising the following steps: Step 1: Preparation of the IOCs stock solution: Using H 2 O and D 2 O as solvents respectively, two stock solutions of IOCs with a concentration of 50 - 200 mg / L were prepared; Step 2: Preparation of a composite material sample after an oxygen-rich or nitrogen-rich material adsorbs IOCs, where the IOCs are from the IOCs stock solution; Step 3: Method for identifying charge-assisted hydrogen bonds: Perform 1 1H NMR measurement and FTIR measurement on the composite material sample; After 1 1H NMR measurement, compared with the oxygen-rich or nitrogen-rich materials without adsorbed IOCs, the composite material sample with H 2 2O as the solvent has new characteristic peaks in the very low field region, but for the composite material sample with D 2 2O as the solvent, this new characteristic peak disappears; After FTIR measurement, for the composite material sample with H 2 2O as the solvent, a blue shift of the hydroxyl peak and the amino peak was detected, and the main characteristic peaks appeared at higher frequencies than those of the hydroxyl peak and the amino peak.

2. The method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and proton nuclear magnetic resonance spectroscopy according to claim 1, Characterized in that, Said step 1 further includes the preparation of a background solution, and the specific method is: Using H 2 O and D 2 O as solvents respectively, and using NaCl or CaCl 2 as solutes to prepare background solutions; the stock solutions of the IOCs use the two background solutions as solvents respectively; Wherein, the concentration of the background solution is 0 to 0.02 mol / L; the mass ratio of the solute of the IOCs stock solution to the volume of the background solution is 50 to 200 mg: 1 L.

3. The method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and proton nuclear magnetic resonance spectroscopy according to claim 2, Characterized in that, Adjust the pH of both the background solution and the IOCs stock solution to: pH > pKa value of the ionizable organic compound + 2.

4. The method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and proton nuclear magnetic resonance spectroscopy according to claim 1, Characterized in that, The solute in the IOCs stock solution is an ionizable organic compound.

5. The method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and proton nuclear magnetic resonance spectroscopy according to claim 4, Characterized in that, The ionizable organic compound includes clofibric acid, paracetamol, p-aminobenzoic acid, sulfamethazine, benzoic acid, and other ionizable organic compounds containing hydroxyl, carboxyl, and amino groups.

6. The method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and proton nuclear magnetic resonance spectroscopy according to claim 1, Characterized in that, The oxygen-rich or nitrogen-rich material in said step 2 includes oxidized multi-walled carbon nanotubes, amino-functionalized multi-walled carbon nanotubes, graphene oxide, oxidized minerals, and artificial resins.

7. The method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and proton nuclear magnetic resonance spectroscopy according to claim 1, Characterized in that, The mixing method in said step 2 is: in a thermostatic oscillator, shake in the dark at 20 - 25 °C and 150 - 180 rmp for 48 h or more.

8. The method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and proton nuclear magnetic resonance spectroscopy according to claim 1, Characterized in that, The 1 method for determining ¹H NMR is as follows: After ultrasonically mixing the composite material sample with deuterated dimethyl sulfoxide, add it to a nuclear magnetic resonance tube and measure it on a 1 ¹H NMR detector.

9. The method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and proton nuclear magnetic resonance spectroscopy according to claim 1, Characterized in that, The method for FTIR measurement is as follows: A composite material sample with H 2 O as the solvent is mixed and ground with KBr. After pressing into a tablet, it is measured on an FTIR detector.

10. The method for identifying charge-assisted hydrogen bonds in infrared spectroscopy and proton nuclear magnetic resonance spectroscopy according to claim 9, Characterized in that, The FTIR measurement frequency range is 1200 - 4000 cm -1 , the resolution is ≥ 0.4 cm -1 , the wavenumber accuracy is 0.01 cm -1 , and the wavelength accuracy is 0.1 cm -1 .

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