Nickel-based metal organic framework material as well as preparation method and application thereof

Abstract

The invention provides a nickel-based metal organic framework material as well as a preparation method and application thereof, and the nickel-based metal organic framework material is assembled by taking Ni as a metal center and tris-(4-imidazolyl phenyl) amine, H4TCPP, N, N-dimethylformamide and H2O as ligands. When the nickel-based metal organic framework material is used as a fluorescent probe, the nickel-based metal organic framework material is good in stability, has high selectivity and high sensitivity to benzidine, can effectively detect the existence of benzidine, does not need to use a large-scale instrument during use, is simple in operation method, can effectively reduce the labor cost, the consumable cost and the like, and is suitable for industrial production. And the method has wide potential application value.

Description

Technical Field

[0001] The present invention relates to the technical field of optical sensing imaging detection, and in particular to a nickel-based metal organic framework material and a preparation method and application thereof. Background Art

[0002] Benzidine is an aromatic amine compound widely used in the production of dyes, pigments and rubber chemicals. However, benzidine is highly toxic and long-term exposure can cause bladder cancer, pancreatic cancer and other types of cancer, which is seriously harmful to human health. Therefore, governments and environmental protection organizations have strict regulations on the content of benzidine in the environment, which requires reliable, sensitive and efficient detection methods to monitor the presence of benzidine to ensure public health and environmental safety.

[0003] Traditional detection methods for benzidine mainly include gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry. These methods have high sensitivity and accuracy, but they usually require expensive equipment, complex sample pretreatment, and professional technicians to operate. Therefore, in practical applications, especially in rapid on-site detection and large-scale environmental monitoring, the use of the above traditional methods is greatly limited.

[0004] In recent years, based on the rapid development of nanomaterials, sensor technology and new optical detection methods, the detection technology of benzidine has also made some progress. For example, the surface enhanced Raman scattering technology using nanometal materials can detect benzidine at low concentrations; the detection method based on electrochemical sensors has good sensitivity and selectivity. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a nickel-based metal organic framework material and a preparation method and application thereof, so as to solve the problems of high cost and labor consumption in the prior art when performing benzidine detection.

[0006] To achieve the above-mentioned object and other related objects, the first aspect of the present invention provides a nickel-based metal organic framework material, wherein the nickel-based metal organic framework material is assembled with Ni as the metal center and tri-(4-imidazolylphenyl)amine, H4TCPP, N,N-dimethylformamide and H2O as ligands;

[0007] Wherein, the structural formula of tri-(4-imidazolylphenyl)amine is:

[0008]

[0009] The structural formula of H4TCPP is:

[0010]

[0011] Preferably, the crystal structure of the nickel-based metal organic framework material is a monoclinic system, and the space group symbol is P21 / n. The space group symbol P21 / n specifically describes the symmetry and arrangement of the Ni-MOF material crystal. Specifically, "P" indicates that the Ni-MOF material is a simple lattice with only one lattice point in the unit cell; "21" indicates that there is a 2-fold rotational symmetry and a translational symmetry; this means that there is a rotation axis with a rotation angle of 180° (2 times) in the lattice, and the translational symmetry associated therewith; " / n" indicates that there is a mirror symmetry. In the P21 / n space group, the mirror plane is perpendicular to the 2-fold rotation axis, that is, there is a mirror symmetry perpendicular to the rotation axis.

[0012] Preferably, there are two Ni in each asymmetric unit in the crystal structure of the nickel-based metal organic framework material. 2+ , a Tipa ligand, a deprotonated H4TCPP ligand, two DMF ligands and a water molecule ligand; two Ni 2+ By assembling with ligands, two interpenetrating three-dimensional network structures are constructed along the

[010]

[001] direction.

[0013] The nickel-based metal organic framework material provided by the present invention has a structure as shown in the attached Figure 1 When the nickel-based metal organic framework material is combined with the benzidine molecule, the electrostatic effect of the formed hydrogen bonds causes the ultraviolet absorption to be enhanced, and the fluorescence is enhanced at the same time.

[0014] The second aspect of the present invention provides a method for preparing the nickel-based metal-organic framework material as described above, comprising mixing the tri-(4-imidazolylphenyl)amine, the H4TCPP and nickel ions in a solvent to obtain a mixed solution, and heating, cooling and washing the mixed solution to obtain the nickel-based metal-organic framework material.

[0015] Preferably, the solvent comprises N,N-dimethylformamide and water.

[0016] Preferably, the volume ratio of N,N-dimethylformamide to water is (4-5):2, such as 4:2 or 5:2.

[0017] Preferably, the nickel ions are derived from nickel salts.

[0018] More preferably, the nickel salt includes one or more of nickel nitrate, nickel acetate, nickel sulfate, nickel chloride, nickel sulfamate, nickel bromide, and nickel carbonyl.

[0019] Preferably, the molar ratio of the nickel ion to tri-(4-imidazolylphenyl)amine and H4TCPP is 4:(1-1.2):(1-1.2), such as 4:1:1, 4:1.1:1.1, 4:1.2:1.2.

[0020] Preferably, the addition amount of the nickel ions and water is 4 mol: (4-5) mL, such as 1 mol: 1 mL, 4 mol: 5 mL.

[0021] Preferably, the heating temperature is 100-160°C. For example, the heating temperature may be 100-140°C or 140-160°C.

[0022] Preferably, the heating time is 2 to 4 days. For example, the heating time can be 2 days, 3 days, or 4 days.

[0023] Preferably, the temperature is cooled to 20-25°C after the heating is completed.

[0024] Preferably, the cooling time is 2 to 3 days.

[0025] Preferably, the washing is performed using N,N-dimethylformamide.

[0026] A third aspect of the present invention provides a use of the nickel-based metal organic framework material as described above as a fluorescent probe in detecting benzidine.

[0027] Preferably, the fluorescent probe further comprises a second solvent; the second solvent comprises one or more of water and an organic solvent.

[0028] Preferably, the organic solvent is an organic solvent miscible with water.

[0029] More preferably, the organic solvent is N,N-dimethylformamide.

[0030] A fourth aspect of the present invention provides a method for detecting benzidine in an object to be detected, wherein a fluorescent probe containing the nickel-based metal organic framework material as described above is contacted with the object to be detected, and then irradiated with excitation light, and then the change in fluorescence intensity at the fluorescence emission peak is detected to determine whether the object to be detected contains benzidine.

[0031] Preferably, the wavelength of the excitation light is 320-340 nm, more preferably 330 nm.

[0032] Preferably, when detecting the change in fluorescence intensity at the fluorescence emission peak, the selected wavelength is 400-430 nm, and more preferably, the selected wavelength is 415 nm.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. When the nickel-based metal organic framework material provided by the present invention is used as a fluorescent probe, it has good stability, high selectivity and high sensitivity to benzidine, can effectively detect the presence of benzidine, and has a wide range of potential application value.

[0035] 2. When the nickel-based metal organic framework material provided by the present invention is applied to the detection of benzidine, no large-scale instruments are required, and the operation method is simple, which can effectively reduce labor costs, consumables costs, etc.

[0036] 3. The raw materials of the nickel-based metal organic framework material provided by the present invention are easy to obtain, the yield is high, the operating conditions are easy to control, the preparation cost is low, and it is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is the X-ray single crystal diffraction pattern of the Ni-MOF material provided in Example 1 of the present invention.

[0038] Figure 2 It is a schematic diagram of the 3D structure of the Ni-MOF material provided in Example 1 of the present invention.

[0039] Figure 3 This is the infrared spectrum of the Ni-MOF material provided in Example 1 of the present invention.

[0040] Figure 4 This is a thermogravimetric analysis diagram of the Ni-MOF material provided in Example 1 of the present invention.

[0041] Figure 5 It is a result diagram of ultraviolet absorption spectrum analysis of the fluorescent probe containing Ni-MOF material and benzidine provided in Example 1 of the present invention.

[0042] Figure 6 This is a histogram of the fluorescence intensity of the fluorescent probe containing Ni-MOF material provided in Example 1 of the present invention in different organic pollutants.

[0043] Figure 7 It is a histogram of the fluorescence intensity of the fluorescent probe containing Ni-MOF material provided in Example 1 of the present invention under the coexistence conditions of benzidine and different organic pollutants.

[0044] Figure 8 This is a fluorescence emission spectrum diagram of the fluorescent probe containing Ni-MOF material provided in Example 1 of the present invention in different concentrations of benzidine.

[0045] Fig. 9 This is a dot plot of the fluorescence intensity of the fluorescent probe containing the Ni-MOF material provided in Example 1 of the present invention in different concentrations of mercury ions. DETAILED DESCRIPTION

[0046] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0047] In this application, nickel-based metal organic framework materials are abbreviated as Ni-MOF materials, and tri-(4-imidazolylphenyl)amine is abbreviated as Tipa.

[0048] The present application does not specifically limit the sources of tri-(4-imidazolylphenyl)amine (Tipa) and H4TCPP, which can be obtained by purchase or synthesis.

[0049] The Tipa used in the following examples is Adamas|97%|RG; the Ni(NO3)2·6H2O is Adamas|99%|RG|500g.

[0050] Example 1: Synthesis of Ni-MOF materials

[0051] 0.011g Tipa (0.025mmol), 0.014g H4TCPP (0.025mmol) and 0.029g Ni(NO3)2·6H2O (0.1mmol) were placed in a polytetrafluoroethylene reactor, 10mL DMF and 4mL water were added, and the mixture was evenly mixed by ultrasonic oscillation to obtain a mixed solution; the mixed solution was sealed, moved into an electric heated air drying oven, heated at 140°C for 48h, and then cooled at room temperature for 48h; after cooling, it was washed with DMF and dried to obtain green block crystals with a yield of 68%.

[0052] The flow chart of the reaction is shown below:

[0053]

[0054] Example 2: Structural Characterization of Ni-MOF—X-ray Single Crystal Diffraction Analysis

[0055] The applicant conducted an X-ray single crystal diffraction analysis on the Ni-MOF prepared in Example 1 using a D8VENTURE X-ray single crystal diffractometer. The specific results are as follows: Figure 1 and Figure 2 shown.

[0056] Depend on Figure 1 It can be seen that Ni-MOF belongs to the monoclinic system and its space group symbol is P21 / n. Each asymmetric unit of Ni-MOF has two different coordination modes of Ni2+ (marked as Ni 2+ 1 and Ni 2+ 2), a Tipa ligand, a deprotonated H4TCPP ligand, two DMF molecular ligands and a water ligand.

[0057] Specifically, Ni 2+ 1 is in a six-coordinate environment with Ni 2+ The two nitrogen atoms (N7, N9) in the 1-coordinate group come from two different Tipa ligands, the two oxygen atoms (O1, O8) come from two different H4TCPP ligands, one oxygen atom (O9) comes from the DMF ligand, and one oxygen atom (O10) comes from the water ligand;

[0058] Ni 2+ 2 is also in a six-coordinate environment, with Ni 2+ The 2-coordinated nitrogen atom (N5) comes from the Tipa ligand, the four oxygen atoms (O2, O3, O5, O7) come from four different H4TCPP ligands, and one oxygen atom (O10) comes from the water ligand. 2+ 1 and Ni 2+ 2 is connected through O10 to form Ni 2+ 1-O10-Ni 2+ 2 bonds. Each metal cluster is connected and coordinated with the ligands Tipa, H4TCPP, H2O, and DMF, and finally constructs two interpenetrating three-dimensional network structures along the

[010]

[001] direction. From a topological perspective, the structure of Ni-MOF can be simplified to a network structure of 3, 4, 7-connected nodes, and its topological symbol is {4.62}{44.62}{48.611.82}.

[0059] Figure 2 Specifically shown is a schematic diagram of the 3D structure of the Ni-MOF prepared in Example 1.

[0060] Example 3: Structural Characterization of Ni-MOF - Infrared Analysis

[0061] The applicant conducted infrared detection analysis on the Ni-MOF prepared in Example 1, using an infrared analysis detector, and the infrared spectrum results are as follows: Figure 3 shown.

[0062] Depend on Figure 3 It can be seen that H4TCPP is at 3725cm -1 It may be the free hydroxyl stretching vibration absorption peak, 3444cm -1 The peak at 1710 cm is the stretching vibration peak of the hydroxyl group in H4TCPP. -1 is the carbonyl stretching vibration peak in H4TCPP; Tipa: 1498cm-1 It is the stretching vibration absorption peak of C=N on imidazole; Ni-TCPP (product Ni-MOF): 1639cm -1 is the stretching vibration absorption peak of C=C on the benzene ring, 1506cm -1 is the stretching vibration absorption peak of the C=N bond on imidazole, 1396cm -1 It is the symmetrical stretching vibration absorption peak of the carboxylate group. At about 3400cm -1 The broad absorption band at is in good agreement with the presence of residual water molecules in MOFs.

[0063] Among them, the infrared spectrum (IR) data of the product Ni-MOF are: C, 50.64; H, 2.36; N, 15.31. Found: C, 50.52; H, 2.37; N, 15.36. IR (KBr, cm-1): 3550 (m), 3343 (m), 3150 (m), 3065 (m), 1715 (w), 1672 (m), 1638 (m), 1548 (m), 1514 (m), 1384 (m), 1343 (m), 1248 (w), 1107 (w), 1086 (m), 1016 (m), 852 (w), 742 (w), 650 (w).

[0064] From the above, it can be seen that the Ni-MOF material was finally prepared in Example 1.

[0065] Example 4: Thermal Stability Analysis of Ni-MOF

[0066] In order to explore the stability of the probe Ni-MOF material at different temperatures, the applicant conducted a thermogravimetric analysis on the Ni-MOF material prepared in Example 1. The specific steps are: using a PerkinElmer TGA8000 thermogravimetric analyzer, weighing an appropriate amount of the Ni-MOF material prepared in Example 1, placing it in a crucible, closing the device, and observing the mass change of the Ni-MOF material after the value stabilizes. The specific results are as follows: Figure 4 shown.

[0067] Depend on Figure 4 It can be seen that Ni-MOF loses 3.48% (theoretical value is 4.22%) at 30-70°C, which is attributed to the loss of three free water molecules in the skeleton; upon further heating, Ni-MOF loses 14.36% (theoretical value is 14.06%) at 110-260°C, which is attributed to the loss of corresponding coordinated water molecules. After further heating, the mass of Ni-MOF drops sharply after 370°C, which is attributed to the collapse of the skeleton structure.

[0068] This indicates that the Ni-MOF prepared in Example 1 can maintain a basically stable structure before 370°C and has a certain thermal stability.

[0069] Example 5: Ultraviolet absorption spectrum analysis of fluorescent probe containing Ni-MOF material

[0070] In order to explore whether the fluorescent probe containing Ni-MOF material can be coupled with benzidine for the detection of benzidine, the applicant conducted ultraviolet absorption spectrum analysis. The specific steps are:

[0071] Setting up the Ni-MOF group: dispersing the Ni-MOF prepared in Example 1 in water to prepare a 1 mg / 3 mL solution, taking 3 mL and placing it in a constant volume cuvette;

[0072] Ni-MOF+benzidine group: The Ni-MOF prepared in Example 1 was dispersed in water to prepare a 1 mg / 3 mL solution, and then 60 μM benzidine was added, and 3 mL was placed in a constant volume cuvette;

[0073] Benzidine group: prepare 60 μM benzidine and place 3 mL in a constant volume cuvette;

[0074] Then, the three groups of cuvettes were irradiated with ultraviolet light for 20 minutes. After returning to room temperature, the ultraviolet absorption spectra were collected at each excitation time period. The results are as follows: Figure 5 As shown, the excitation light is: 330nm.

[0075] Depend on Figure 5 It can be seen that the curve of the Ni-MOF+benzidine group has absorption at 330 nm, which indicates that the Ni-MOF prepared in Example 1 can be coupled with benzidine after being dissolved in water, and can be used for the detection of benzidine.

[0076] Example 6: Ion selectivity experiment of fluorescent probe containing Ni-MOF material

[0077] The applicant also determined the optical properties of fluorescent probes containing Ni-MOF materials in different organic pollutants.

[0078] The specific steps are as follows: 1.0 mg of Ni-MOF prepared in Example 1 is dissolved in 3.0 mL of water to prepare a fluorescent probe, and then different organic pollutants are added to the fluorescent probe: 60 μM, λex: 330 nm, to obtain the fluorescence emission spectrum. The fluorescence intensity at the fluorescence emission peak of 415 nm is plotted against different organic pollutants to obtain a histogram of the fluorescence intensity after adding different organic pollutants. The results are as follows: Figure 6 shown.

[0079] Depend on Figure 6It can be seen that after adding benzidine to the fluorescent probe, the fluorescence is significantly enhanced, while the fluorescence intensity remains basically unchanged after adding other organic pollutants. This shows that the electrostatic effect of hydrogen bonds generated after benzidine combines with the Ni-MOF material in the fluorescent probe causes enhanced ultraviolet absorption and fluorescence. This further shows that the fluorescent probe containing Ni-MOF material has high selectivity for benzidine.

[0080] Example 7: Ion competition experiment of fluorescent probe containing Ni-MOF material

[0081] The applicant also measured the optical properties of fluorescent probes containing Ni-MOF materials added to benzidine and other different organic pollutants in the presence of multiple organic pollutants.

[0082] The specific steps are as follows: 1.0 mg of Ni-MOF prepared in Example 1 is dissolved in 3.0 mL of water to prepare a fluorescent probe, and then different organic pollutants are added to the fluorescent probe at 60 μM and λex: 330 nm to obtain a fluorescence emission spectrum. The fluorescence intensity at the fluorescence emission peak of 415 nm is plotted against different organic pollutants to obtain a fluorescence intensity bar graph of benzidine and different organic pollutants. The results are as follows: Figure 7 shown.

[0083] Depend on Figure 7 It can be seen that when benzidine and other organic pollutants coexist, aminobenzidine has an effect on the fluorescence intensity, while other organic pollutants have a weaker effect on the fluorescence intensity. This shows that when there are other organic pollutants in the environment, the detection of benzidine by the fluorescent probe is less affected by other organic pollutants and is suitable for most environments.

[0084] Example 8: Continuous titration experiment of fluorescent probe containing Ni-MOF material

[0085] 1.0 mg of the probe Ni-MOF was dissolved in 3.0 mL of water to prepare a fluorescent probe, and different concentrations of benzidine were added, λex: 330 nm, and the fluorescence emission spectrum was obtained, such as Figure 8 The fluorescence intensity at the fluorescence emission peak of 415 nm was plotted against different concentrations of benzidine, and a dot graph of the fluorescence intensity of the continuous titration spectrum of different concentrations of benzidine added to the fluorescent probe containing Ni-MOF material was obtained, as shown in Fig. 9 shown.

[0086] Depend on Figure 8 and Fig. 9 It can be seen that with the increase of benzidine concentration, the fluorescence intensity gradually increased. When the benzidine concentration was higher than 60 μM, the fluorescence intensity tended to be stable and remained almost unchanged, and the solution reached a saturated state.

[0087] In summary, the nickel-based metal organic framework material provided by the present invention can achieve high selectivity and high sensitivity detection of benzidine in most environments when used for benzidine detection, and has excellent competitive test performance; and the nickel-based metal organic framework material has a simple preparation process, is easy to operate when used for detection, and has broad application prospects.

[0088] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A nickel-based metal organic framework material, characterized in that: The nickel-based metal organic framework material is assembled with Ni as the metal center and tri-(4-imidazolylphenyl)amine, H4TCPP, N,N-dimethylformamide and H2O as ligands; Wherein, the structural formula of tri-(4-imidazolylphenyl)amine is: The structural formula of H4TCPP is:

2. The nickel-based metal organic framework material according to claim 1, characterized in that: The crystal structure of the nickel-based metal organic framework material is monoclinic, and the space group symbol is P21 / n.

3. The nickel-based metal organic framework material according to claim 1, characterized in that: In the crystal structure of the nickel-based metal organic framework material, there are two Ni 2+ , a Tipa ligand, a deprotonated H4TCPP ligand, two DMF ligands and a water molecule ligand; two Ni 2+ By assembling with ligands, two interpenetrating three-dimensional network structures are constructed along the [010][001] direction.

4. A method for preparing a nickel-based metal organic framework material as claimed in any one of claims 1 to 3, characterized in that: The tri-(4-imidazolylphenyl)amine, the H4TCPP and nickel ions are mixed in a first solvent to obtain a mixed solution, and the mixed solution is heated, cooled and washed to obtain the nickel-based metal organic framework material.

5. The preparation method according to claim 4, characterized in that: The first solvent includes N,N-dimethylformamide and water; And / or, the nickel ions are derived from nickel salts; The molar ratio of the nickel ion to tri-(4-imidazolylphenyl)amine and H4TCPP is 4:(1-1.2):(1-1.2).

6. The preparation method according to claim 5, characterized in that: The amount of nickel ions and water added is 4 mol: (4-5) mL; And / or, the volume ratio of N,N-dimethylformamide to water is (4-5):2; And / or, the nickel salt includes one or more of nickel nitrate, nickel acetate, nickel sulfate, nickel chloride, nickel sulfamate, nickel bromide, and nickel carbonyl.

7. The preparation method according to claim 4, characterized in that: The heating temperature is 100-160°C; And / or, cooling after heating is completed, the cooling temperature is 20-25°C; And / or, the washing is performed using N,N-dimethylformamide.

8. Use of the nickel-based metal organic framework material as claimed in any one of claims 1 to 3 as a fluorescent probe in detecting benzidine.

9. The use according to claim 8, characterized in that: The fluorescent probe further includes a second solvent; the second solvent includes one or more of water and an organic solvent. Preferably, the organic solvent is an organic solvent miscible with water.

10. A method for detecting benzidine in a test object, characterized in that: A fluorescent probe containing the nickel-based metal organic framework material as claimed in any one of claims 1 to 3 is brought into contact with the object to be detected, then irradiated with excitation light, and then the change in fluorescence intensity at the fluorescence emission peak is detected to determine whether the object to be detected contains benzidine.

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