A method for regulating zirconium-based metal-organic framework nanoparticles using carboxylated cellulose nanoparticles

Abstract

This invention relates to a method for regulating zirconium-based metal-organic framework nanoparticles using carboxylated cellulose nanoparticles. This method utilizes carboxylated cellulose nanoparticles, a green and environmentally friendly material, as a defect modulator, and obtains UiO-66-OH with tunable defect levels via an in-situ one-pot synthesis. Using carboxylated nanoparticles as a nano-soft template, carboxyl competitive ligands, and surface-assisted growth medium, the method induces the heterogeneous nucleation and explosive growth of UiO-66-OH crystals into nanospheres. Precise defect regulation is achieved through the precise competitive coordination of carboxyl groups and zirconium ions. While achieving defect regulation and ensuring stability, background fluorescence is modulated through the disruption of intramolecular charge transfer (ICT). This provides a solid research foundation for the regulation of defective metal-organic framework materials and their bio-friendly applications.

Description

Technical Field

[0001] This invention belongs to the field of crystal material synthesis and regulation, and provides a method for regulating zirconium-based metal-organic framework nanoparticles by carboxylating nanocellulose. Background Technology

[0002] Zirconium-based metal-organic frameworks are multifunctional composite materials that utilize coordination interactions and organic molecular ligands to crystallize around tetravalent zirconium ions. They possess high porosity, large specific surface area, and good water stability, and are widely used in sensing, catalysis, and adsorption fields.

[0003] However, defect-free metal-organic framework (MOF) materials, represented by UiO-66, suffer from insufficient exposure of active sites due to their highly ordered crystal structure, and are accompanied by a strong intrinsic fluorescence background. These factors together restrict their practical application.

[0004] To address the aforementioned challenges, defect engineering in metal-organic frameworks (MOFs) has emerged. This technology aims to purposefully and controllably introduce or create defects during MOF synthesis, thereby precisely controlling their physicochemical properties. Defect types primarily include ligand defects, metal node defects, and guest molecule-induced defects. Defect-type MOFs, due to their exposed metal sites, more complex pore environments, and more active sites, possess greater application potential in sensing, catalysis, and gas adsorption.

[0005] To achieve precise control of defect-type metal-organic frameworks (MOFs) and obtain better performance, existing technologies have proposed many solutions, such as: Publication number CN115216025B discloses a method for preparing defective Mg-MOF-74 using a hydrothermal reaction. This method utilizes a hydrothermal reaction with altered feeding sequences to prepare defective Mg-MOF-74, due to Cl... - The weak coordination process of ions interferes with the normal coordination between metal ions and ligands, resulting in ligand-deficient metal-organic frameworks (MOFs). This increases the number of adsorption sites and improves the adsorption efficiency of CO2.

[0006] Publication number CN118930894B discloses a method for preparing and applying oxygen-deficient MOF-on-MOF heterojunction metal-organic framework materials. The method involves first growing Ni-NDC nanosheets in situ on a support using a solvothermal method, followed by the solvothermal growth of Fe-BDC nanosheets on the Ni-NDC nanosheets. This method synthesizes lattice-deformed, oxygen-deficient metal-organic frameworks. Due to the presence of defects, this material promotes interfacial charge transport and enhances the adsorption capacity for intermediate products, showing promising application prospects in the field of electrocatalysis.

[0007] Publication number CN109847803B discloses a defective MOF catalyst, its preparation method, and its application. It utilizes a five-membered heterocyclic monocarboxylic acid as a modifier to modify HD-MOFs (Fe), resulting in asymmetric bridging and lattice defects in the Fe-O metal clusters. These defects enhance both the MOF's ability to generate hydroxyl radicals and its electron migration capabilities, ultimately improving its catalytic activity against organic pollutants.

[0008] While existing technologies provide effective strategies for the synthesis of defective metal-organic frameworks (MOFs), the precise quantification of defect concentrations leads to an unclear structure-activity relationship between defect structures and performance enhancements. Furthermore, the chemical modifiers commonly used in synthesis often lack biocompatibility, further limiting the application of defective MOFs in environmental sensing, biomedicine, and other related fields.

[0009] To address the aforementioned problems, this invention provides a method for regulating defective zirconium-based metal-organic framework nanoparticles using carboxylated cellulose nanoparticles. By controlling the amounts of carboxylated cellulose nanoparticles and zirconium metal, the defect of UiO-66-OH is regulated, and the bulk fluorescence of the material is modulated through the disruption of intramolecular charge transfer (ICT). This broadens the applications of defective metal-organic framework nanoparticles in sensing, adsorption, and catalysis. Furthermore, this material utilizes the bio-friendly material carboxylated cellulose nanoparticles for regulation, providing an application model and technical practice for the bio-friendly application of metal-organic framework materials. Summary of the Invention

[0010] The purpose of this invention is to provide a method for regulating zirconium-based metal-organic framework nanoparticles using carboxylated cellulose nanoparticles. This method utilizes carboxylated cellulose nanoparticles, a green and environmentally friendly material, as a defect modulator, and obtains UiO-66-OH with tunable defect levels through an in-situ one-pot synthesis. Using carboxylated nanoparticles as a nanotemplate, carboxyl competitive ligand, and surface-assisted growth medium, the heterogeneous nucleation and explosive growth of UiO-66-OH crystals into nanospheres is induced. Precise defect regulation is achieved through the precise competitive coordination of carboxyl groups and zirconium ions. While achieving defect regulation and ensuring stability, background fluorescence is regulated through the disruption of intramolecular charge transfer (ICT). This provides a solid research foundation for the regulation of defective metal-organic framework materials and their bio-friendly applications.

[0011] This invention discloses a method for regulating zirconium-based metal-organic framework nanoparticles using carboxylated nanocellulose. This method obtains UiO-66-OH nanoparticles with different defect levels by adjusting the ratio of nanocellulose to zirconium metal. The specific operation is carried out according to the following steps: a. Add 1.2% by mass of carboxylated nanocellulose to N,N-dimethylformamide and stir thoroughly at room temperature to obtain a carboxylated nanocellulose dispersion; b. Dissolve zirconium chloride in 1.5 mL of N,N-dimethylformamide and stir thoroughly at room temperature until completely dissolved to obtain a mixture; c. Add the mixture obtained in step b to the carboxylated nanocellulose dispersion obtained in step a and stir for 4 hours to obtain a mixture solution; d. Dissolve 2-hydroxyterephthalic acid in 1.5 mL of N,N-dimethylformamide solution and stir until completely dissolved to obtain the ligand solution; f. Add the ligand solution obtained in step d to the mixture solution obtained in step c, and stir thoroughly for 1 h until the mixture solution is homogeneous and free of stratification; g. Add 6.4 mL of acetic acid and 0.25 mL of deionized water to the solution obtained in step f, stir for 10 min, and obtain a mixture; h. Place the mixture obtained in step g into the inner liner of the reactor, heat it to 100-150 ℃, and react for 1-3 h. After the reaction is completed, cool and let it stand. Use N,N-dimethylformamide and pure water to repeatedly centrifuge and wash 3 times to obtain zirconium-based metal-organic framework nanoparticles of light white yellow colloidal substance UiO-66-OH.

[0012] This invention discloses a method for controlling zirconium-based metal-organic framework nanoparticles using carboxylated cellulose nanoparticles. This method utilizes carboxylated cellulose nanoparticles as a green regulator to effectively induce the controllable synthesis of defective zirconium-based metal-organic framework nanoparticles. Under the synergistic effect of the carboxylated cellulose nanoparticles as a nanotemplate, the carboxyl competitive ligand, and surface assistance, UiO-66-OH crystals undergo in-situ heterogeneous nucleation and explosive growth into nanospheres on the surface of the carboxylated cellulose nanoparticles. Precise defect control is achieved through the precise competitive coordination of carboxyl groups and zirconium ions. While achieving defect control and ensuring stability, background fluorescence is also regulated. Based on the mechanism of host-guest size matching and intramolecular charge transfer (ICT) disruption and reconstruction, real-time fluorescence detection and degradation of glyphosate are realized. This lays a solid material foundation for its sensitive detection and specific adsorption of environmental pollutants. Attached Figure Description

[0013] Figure 1 The images are scanning electron microscope images of zirconium-based metal-organic framework nanoparticles in Examples 1-6 of this invention, wherein (a) UiO; (b) UiO-1; (c) UiO-2; (d) UiO-3; (e) UiO-4; and (f) UiO-5. Figure 2This is a statistical analysis of the particle size of the zirconium-based metal-organic framework nanoparticles in Examples 1-6 of this invention; Figure 3 This is a scanning electron microscope image of the zirconium-based metal-organic framework nanoparticle material in Example 3 of the present invention; Figure 4 The diagrams show the zeta potential correlation of zirconium-based metal-organic framework nanoparticles in Examples 1-6 of this invention, where (a) is a zeta potential data diagram; and (b) is a physical image of the dispersion of zirconium-based metal-organic framework nanoparticles in Examples 1 and 3. Figure 5 These are X-ray diffraction (XRD) characterization diagrams from Examples 2-6 of this invention; Figure 6 These are Fourier transform infrared (FTIR) characterization diagrams from Examples 2-6 of this invention; Figure 7 The following are characterization diagrams of nitrogen adsorption-desorption curves (BET) in Examples 2-6 of the present invention, where (a) nitrogen adsorption-desorption and (b) pore size distribution. Figure 8 The X-ray photoelectron spectra in Examples 2-6 of the present invention are shown, where (a) is the total spectrum, (b) is the C 1s spectrum, (c) is the Zr 3d spectrum, and (d) is the O 1s spectrum. Figure 9 These are the characterization diagrams of simultaneous thermogravimetric analysis (TGA) in Examples 2-6 of this invention; Figure 10 These are comparison images of the background fluorescence intensity of zirconium-based nanomaterials in Examples 1-6 of this invention. Detailed Implementation

[0014] The present invention will be further described in detail below through specific embodiments: Example 1 (Comparison) Synthesis of defect-free UiO-66-OH zirconium-based nanoparticles: a. Dissolve 21 mg of zirconium chloride and 89.25 mg of 2-hydroxyterephthalic acid in 6.75 mL of N,N-dimethylformamide and stir thoroughly at room temperature until completely dissolved; b. Add 6.4 mL of acetic acid and 0.25 mL of deionized water to the solution obtained in step a, and stir for 10 min; c. Place the solution obtained in step b into the inner liner of the reactor, heat it to 120 ℃, react for 2 h, and cool and let it stand after the reaction is complete. d. The precipitate was washed three times by centrifugation with N,N-dimethylformamide and then dried in a vacuum oven at 60 °C for 24 h to obtain defect-free UiO-66-OH. Example 2

[0015] Synthesis of zirconium-based nanoparticles by adjusting the ratio of nanocellulose and zirconium metal: a. Take 1 g (wet weight) of carboxylated nanocellulose with a mass percentage of 1.2% and add it to 3.75 mL of N,N-dimethylformamide. Stir and disperse the mixture thoroughly at room temperature to obtain a carboxylated nanocellulose dispersion. b. Dissolve 21 mg of zirconium chloride in 1.5 mL of N,N-dimethylformamide and stir thoroughly at room temperature until completely dissolved; c. Add the zirconium chloride solution obtained in step b to the carboxylated nanocellulose dispersion obtained in step a and stir for 4 h to obtain a mixture solution; d. Dissolve 65.64 mg of 2-hydroxyterephthalic acid in 1.5 mL of N,N-dimethylformamide solution and stir until completely dissolved to obtain the ligand solution; f. Add the ligand solution obtained in step d to the mixture solution obtained in step c, and stir thoroughly for 1 h until the mixture solution is homogeneous and free of stratification; g. Add 6.4 mL of acetic acid and 0.25 mL of deionized water to the solution obtained in step f and stir for 10 min; h. Place the solution obtained in step g into the inner liner of the reactor, heat it to 100 °C, and react for 1 h. After the reaction is completed, cool and let it stand. Use N,N-dimethylformamide and pure water to repeatedly centrifuge and wash 3 times each to obtain UiO-66-OH zirconium-based metal-organic framework nanoparticles in a light white yellow gel. Example 3

[0016] Synthesis of zirconium-based nanoparticles by adjusting the ratio of nanocellulose and zirconium metal: a. Take 1.5 g (wet weight) of carboxylated nanocellulose with a mass percentage of 1.2% and add it to 3.75 mL of N,N-dimethylformamide. Stir and disperse the mixture thoroughly at room temperature to obtain a carboxylated nanocellulose dispersion. b. Dissolve 21 mg of zirconium chloride in 1.5 mL of N,N-dimethylformamide and stir thoroughly at room temperature until completely dissolved; c. Add the zirconium chloride solution obtained in step b to the carboxylated nanocellulose dispersion obtained in step a and stir for 4 h to obtain a mixture solution; d. Dissolve 65.64 mg of 2-hydroxyterephthalic acid in 1.5 mL of N,N-dimethylformamide solution and stir until completely dissolved to obtain the ligand solution; f. Add the ligand solution obtained in step d to the mixture solution obtained in step c, and stir thoroughly for 1 h until the mixture solution is homogeneous and free of stratification; g. Add 6.4 mL of acetic acid and 0.25 mL of deionized water to the solution obtained in step f and stir for 10 min; h. Place the solution obtained in step g into the inner liner of the reactor, heat it to 110 °C, and react for 2 h. After the reaction is completed, cool and let it stand. Use N,N-dimethylformamide and pure water to repeatedly centrifuge and wash 3 times each to obtain UiO-66-OH zirconium-based metal-organic framework nanoparticles in a light white yellow gel. Example 4

[0017] Synthesis of zirconium-based nanoparticles by adjusting the ratio of nanocellulose and zirconium metal: a. Take 3 g (wet weight) of carboxylated nanocellulose with a mass percentage of 1.2% and add 3.75 mL of N,N-dimethylformamide (DMF). Stir and disperse thoroughly at room temperature to obtain a carboxylated nanocellulose dispersion. b. Dissolve 21 mg of zirconium chloride in 1.5 mL of N,N-dimethylformamide and stir thoroughly at room temperature until completely dissolved; c. Add the zirconium chloride solution obtained in step b to the carboxylated nanocellulose dispersion obtained in step a and stir for 4 h to obtain a mixture solution; d. Dissolve 65.64 mg of 2-hydroxyterephthalic acid in 1.5 mL of N,N-dimethylformamide solution and stir until completely dissolved to obtain the ligand solution; f. Add the ligand solution obtained in step d to the mixture solution obtained in step c, and stir thoroughly for 1 h until the mixture solution is homogeneous and free of stratification; g. Add 6.4 mL of acetic acid and 0.25 mL of deionized water to the solution obtained in step f and stir for 10 min; h. Place the solution obtained in step g into the inner liner of the reactor, heat it to 120 °C, and react for 1 h. After the reaction is completed, cool and let it stand. Use N,N-dimethylformamide and pure water to repeatedly centrifuge and wash 3 times to obtain UiO-66-OH zirconium-based metal-organic framework nanoparticles in a light white yellow gel. Example 5

[0018] Synthesis of zirconium-based nanoparticles by adjusting the ratio of nanocellulose and zirconium metal: a. Take 5 g (wet weight) of carboxylated nanocellulose with a mass percentage of 1.2% and add 3.75 mL of N,N-dimethylformamide to stir and disperse thoroughly at room temperature to obtain a carboxylated nanocellulose dispersion; b. Dissolve 21 mg of zirconium chloride in 1.5 mL of N,N-dimethylformamide and stir thoroughly at room temperature until completely dissolved; c. Add the zirconium chloride solution obtained in step b to the carboxylated nanocellulose dispersion obtained in step a and stir for 4 h to obtain a mixture solution; d. Dissolve 65.64 mg of 2-hydroxyterephthalic acid in 1.5 mL of N,N-dimethylformamide solution and stir until completely dissolved to obtain the ligand solution; f. Add the ligand solution obtained in step d to the mixture solution obtained in step c, and stir thoroughly for 1 h until the mixture solution is homogeneous and free of stratification; g. Add 6.4 mL of acetic acid and 0.25 mL of deionized water to the solution obtained in step f and stir for 10 min; h. Place the solution obtained in step g into the inner liner of the reactor, heat it to 130 °C, and react for 1.5 h. After the reaction is completed, cool and let it stand. Use N,N-dimethylformamide and pure water to repeatedly centrifuge and wash 3 times to obtain UiO-66-OH zirconium-based metal-organic framework nanoparticles in a light white-yellow gel. Example 6

[0019] Synthesis of zirconium-based nanoparticles by adjusting the ratio of nanocellulose and zirconium metal: a. Take 8 g (wet weight) of carboxylated nanocellulose with a mass percentage of 1.2% and add 3.75 mL of N,N-dimethylformamide to stir and disperse thoroughly at room temperature to obtain a carboxylated nanocellulose dispersion; b. Dissolve 21 mg of zirconium chloride in 1.5 mL of N,N-dimethylformamide and stir thoroughly at room temperature until completely dissolved; c. Add the zirconium chloride solution obtained in step b to the carboxylated nanocellulose dispersion obtained in step a and stir for 4 h to obtain a mixture solution; d. Dissolve 65.64 mg of 2-hydroxyterephthalic acid in 1.5 mL of N,N-dimethylformamide (DMF) solution and stir until completely dissolved to obtain the ligand solution; f. Add the ligand solution obtained in step d to the mixture solution obtained in step c, and stir thoroughly for 1 h until the mixture solution is homogeneous and free of stratification; g. Add 6.4 mL of acetic acid and 0.25 mL of deionized water to the solution obtained in step f and stir for 10 min; h. Place the solution obtained in step g into the inner liner of the reactor, heat it to 150 °C, and react for 3 h. After the reaction is completed, cool and let it stand. Use N,N-dimethylformamide and pure water to repeatedly centrifuge and wash 3 times to obtain UiO-66-OH zirconium-based metal-organic framework nanoparticles in a light white yellow gel. Example 7

[0020] Preparation and detection of glyphosate aqueous solution using UiO-66 fluorescence test reagents with different defect levels a. Add 20 ml of deionized water solution to any of the defective UiO-66-OH obtained in Examples 2-6, and after standing, a 0.1 mg / mL defective UiO-66-OH aqueous solution is obtained; b. Transfer the defective UiO-66-OH aqueous solution obtained in step a to a cuvette for fluorescence spectroscopy testing. The excitation wavelength is λex = 311 nm; slit width: 1 nm; λem = 431 nm; slit width: 0.6 nm; spectrometer: Edinburgh FLS1000. Record the fluorescence intensity and use data processing software to obtain the relationship between different defect degrees of UiO-66-OH and fluorescence intensity. c. Add 0, 0.05, 0.1, 0.5, 5, and 10 mg / mL glyphosate aqueous solution to 0.1 mg / mL defective UiO-66-OH aqueous solution, respectively, and perform fluorescence spectroscopy tests. The excitation wavelength is λex = 311 nm; slit wavelength is 1 nm; λem = 431 nm; slit wavelength is 0.6 nm; spectrometer is Edinburgh FLS1000. Record the fluorescence intensity and use data processing software to obtain the fluorescence intensity changes of UiO-66-OH before and after glyphosate detection with different defect degrees. Example 8

[0021] The defect-free UiO-66-OH obtained in Example 1 was compared with any UiO-66-OH with different defect levels obtained in Examples 2-6. The results showed that, compared with the defect-free UiO-66-OH, the crystal morphology of UiO-66-OH with different defect levels tended to be irregular spherical and the size was significantly reduced. Compared with the defect-free UiO-66-OH, the background fluorescence of UiO-66-OH with different defect levels was lower, and the fluorescence change was more significant after glyphosate detection.

Claims

1. A method for regulating zirconium-based metal-organic framework nanoparticles using carboxylated cellulose nanoparticles, characterized in that, This method obtains UiO-66-OH nanoparticles with different defect levels by adjusting the ratio of nanocellulose and zirconium metal. The specific operation is carried out according to the following steps: a. Add 1.2% by mass of carboxylated nanocellulose to N,N-dimethylformamide and stir thoroughly at room temperature to obtain a carboxylated nanocellulose dispersion; b. Dissolve zirconium chloride in 1.5 mL of N,N-dimethylformamide and stir thoroughly at room temperature until completely dissolved to obtain a mixture; c. Add the mixture obtained in step b to the carboxylated nanocellulose dispersion obtained in step a and stir for 4 h to obtain a mixture solution; d. Dissolve 2-hydroxyterephthalic acid in 1.5 mL of N,N-dimethylformamide solution and stir until completely dissolved to obtain the ligand solution; f. Add the ligand solution obtained in step d to the mixture solution obtained in step c, and stir thoroughly for 1 h until the mixture solution is homogeneous and free of stratification; g. Add 6.4 mL of acetic acid and 0.25 mL of deionized water to the solution obtained in step f, stir for 10 min, and obtain a mixture; h. Place the mixture obtained in step g into the inner liner of the reactor, heat it to 100-150 ℃, and react for 1-3 h. After the reaction is completed, cool and let it stand. Use N,N-dimethylformamide and pure water to repeatedly centrifuge and wash 3 times to obtain zirconium-based metal-organic framework nanoparticles of light white yellow colloidal substance UiO-66-OH.

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