A method for preparing paper-based cobalt-doped terbium metal-organic framework material

Abstract

The present invention provides a method for preparing a paper-based cobalt-doped terbium metal-organic framework material with reasonable design and simple operation. Isophthalic acid is used as a metal ion ligand to prepare a cobalt-doped terbium metal-organic framework. The prepared cobalt-doped terbium metal-organic framework material can be used as an electrochemiluminescent luminescent reagent and a co-reaction promoter. The cobalt-doped terbium metal-organic framework has a larger pore size and volume, a higher surface area and a lower electron transfer resistance, which makes it easier for reactants and active intermediates to approach the electrochemiluminescent internal luminescent reagent, thereby improving the electrochemiluminescent emission performance. At the same time, the catalytic effect of cobalt ions on hydrogen peroxide can be used to construct an electrochemiluminescence mechanism in which a double co-reaction promoter enhances the signal intensity, thereby amplifying the electrochemiluminescence signal. The lanthanide metal-organic framework has the advantages of high sensitivity, wide detection range, stable response, etc., and has broad application prospects in the field of electrochemiluminescence.

Description

Technical Field

[0001] The invention relates to a method for preparing a paper-based cobalt-doped terbium metal-organic framework material, and belongs to the field of preparation of composite nano materials. Background Art

[0002] Metal-organic framework materials are a class of materials synthesized from metal ions or metal oxide clusters, which are connected by organic ligands to form a porous three-dimensional framework. Among them, the cobalt-doped terbium metal-organic framework not only has the advantages of large specific surface area, adjustable pore size and easy functionalization of metal-organic framework materials, but also has the advantages of hard acid Tb 3+ The strong coordination with the hard base isophthalic acid makes up for the instability of metal-organic framework materials. In addition, since the terbium metal-organic framework has a long decay lifetime and high luminescence efficiency, and the current research on terbium is still in its early stages, it has great application potential.

[0003] Electrochemiluminescence is a technology that combines electrochemistry and optics. Therefore, electrochemiluminescence has the advantages of simplicity, portability, stability of electrochemistry and high selectivity, sensitivity, and wide dynamic range of traditional chemiluminescence. At present, the electrochemiluminescence luminescent reagents are mainly luminol, ruthenium bipyridine, quantum dots, metal nanoclusters, and nanocomposites. However, due to the leakage of small luminescent components, the application of metal-organic frameworks loaded with ruthenium bipyridine or luminol is limited, and the stability of electrochemiluminescence emission is seriously affected. In addition, in traditional electrochemiluminescence systems, the luminescent reagent and the coreaction promoter are usually not in the same nanostructure, which increases the distance between the luminescent reagent and the coreaction promoter, resulting in energy loss and affecting the sensitivity of detection. Summary of the invention

[0004] In view of the existing problems, the present technical scheme provides a method for preparing a paper-based cobalt-doped terbium metal-organic framework material with a reasonable design and simple operation. Isophthalic acid is used as a metal ion ligand to prepare a cobalt-doped terbium metal-organic framework. The prepared cobalt-doped terbium metal-organic framework material can be used as an electrochemiluminescent luminescent reagent and a co-reaction promoter. The cobalt-doped terbium metal-organic framework has a larger pore size and volume, a higher surface area and a lower electron transfer resistance, which makes it easier for reactants and active intermediates to approach the electrochemiluminescent internal luminescent reagent, thereby improving the electrochemiluminescent emission performance. At the same time, the catalytic effect of cobalt ions on hydrogen peroxide can be used to construct an electrochemiluminescence mechanism with a double co-reaction promoter to enhance the signal intensity, thereby amplifying the electrochemiluminescence signal. The lanthanide metal-organic framework has the advantages of high sensitivity, wide detection range, stable response, etc., and has broad application prospects in the field of electrochemiluminescence.

[0005] The preparation method of the paper-based cobalt-doped terbium metal-organic framework comprises the following steps:

[0006] (1) Prepare 0.01~0.03 mol / L terbium nitrate solution, 0.03~0.04 mol / L cobalt nitrate solution, and 0.03~0.04 mol / L isophthalic acid solution;

[0007] (2) Evenly distribute the terbium nitrate solution and cobalt nitrate solution prepared in step (1) into 10-15 mL of N,N-dimethylformamide solution;

[0008] (3) uniformly dispersing the isophthalic acid solution prepared in step (1) in the mixed solution of step (2);

[0009] (4) Transfer the mixed solution of step (3) into a 50 mL stainless steel reactor lined with polytetrafluoroethylene, seal and tighten the reactor, and place it in a preheated oven at 160-170°C for 7-9 h;

[0010] (5) After the reaction is completed, the sample is naturally cooled to room temperature, centrifuged, washed three times with anhydrous ethanol, and then placed in a drying oven at 60°C for 10-12 h;

[0011] (6) Designing a paper chip pattern using Adobe Illustrator CS6 software, then transferring the designed pattern to the surface of the paper chip using a solid wax printer, and then transferring it to an oven for heating treatment so that the wax penetrates the entire thickness of the paper to form a hydrophilic area surrounded by a hydrophobic wall;

[0012] (7) cutting the paper chip obtained in step (6) into individual paper chips;

[0013] (8) Take 90~110 μL of 2 mg mL -1 The dopamine solution was dripped onto the hydrophilic area of ​​the paper chip, dried at room temperature, and the dripping was repeated twice to obtain the dopamine-functionalized hydrophilic area;

[0014] (9) Take 50~60 μL of 0.5 mg mL -1 Sodium tetrachloropalladate solution was added dropwise to the hydrophilic area functionalized with dopamine, dried at room temperature, and the addition was repeated twice;

[0015] (10) Preparation of growth medium

[0016] Take 80-100 μL of formaldehyde solution and add 45-50 mL of solution A, where solution A contains 12 mg·mL -1 Sodium hydroxide, 15 mg mL -1 Copper sulfate, 29 mg mL -1A mixed solution of potassium sodium tartrate, the solution obtained by uniformly mixing the two solutions is the growth solution;

[0017] (11) placing the dried paper chip in step (9) into the growth solution prepared in step (10), soaking for 30 min, taking it out and rinsing it with deionized water, and then drying it in a 50°C vacuum drying oven for 1.5 h. Grinding the obtained copper paper electrode in the same direction with a mortar until it is smooth;

[0018] (12) Take 0.001-0.003 g of the sample in step (5), add 50 μL of 5% Nafion and 950 μL of anhydrous ethanol solution, and disperse by ultrasonic oscillation to form a uniform suspension;

[0019] (13) Take 100 μL of the suspension in step (12) and drop it onto the electrode surface obtained in step (11), and dry it at room temperature for 2 h.

[0020] The method for uniformly dispersing the substances in step (1) and step (2) is one of ultrasonic dispersion and magnetic stirring.

[0021] The sample morphology obtained in step (5) is a porous spherical shape with a size of 800 nm.

[0022] The copper paper electrode square resistance obtained in step (11) is 0.4 Ω·sq -1 .

[0023] Cobalt ion doping and the addition of hydrogen peroxide can construct a dual co-reaction promotion strategy to increase the number of free radicals generated, thereby improving the electrochemiluminescence intensity of the terbium metal-organic framework.

[0024] Beneficial effects of the present invention

[0025] (1) The terbium metal-organic framework as a luminescent agent and a co-reaction promoter of cobalt ions are located in the same nanostructure, which reduces the distance between the luminescent agent and the co-reaction promoter, reduces energy loss and increases the sensitivity of detection.

[0026] (2) The operation process is simple and the conditions are relatively mild, which is conducive to the industrial production of the product.

[0027] (3) The introduction of cobalt and terbium metal ions is conducive to obtaining nanoscale metal-organic framework materials with uniform particle size distribution.

[0028] (4) Lanthanide metal-organic framework materials have high sensitivity, wide detection range, and stable response, and have great application potential in electrochemiluminescence systems.

[0029] (5) This method uses paper as the base material, which has the advantages of low cost, environmental protection and easy transportation.

[0030] (6) Paper-based electrodes have the characteristics of large specific surface area and good conductivity, which lays a good foundation for the efficient transmission of electrons in electrochemiluminescence systems.

[0031] (7) The preparation method of paper-based cobalt-doped terbium metal-organic framework material shortens the distance between the luminescent reagent material and the electrode surface, thereby enhancing the electrochemical luminescence intensity of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 . Schematic diagram of the paper chip design printed on A4 paper.

[0033] Figure 2 . The size and shape of a single paper chip.

[0034] Figure 3 . Scanning electron microscope image of cobalt-doped terbium metal-organic framework material.

[0035] Figure 4 . Fluorescence emission spectrum and fluorescence excitation spectrum of cobalt-doped terbium metal-organic framework materials.

[0036] Figure 5 . Electrochemical luminescence intensity response diagram of cobalt-doped terbium metal-organic framework material. Experimental parameters: gain: 4; high voltage: 800 V. DETAILED DESCRIPTION

[0037] Example 1

[0038] (1) Take 5 mL of 0.02 mol / L terbium nitrate aqueous solution and 5 mL of 0.03 mol / L cobalt nitrate aqueous solution, add them to 10 mL of N,N-dimethylformamide solution and stir magnetically for 10 min.

[0039] (2) Add 5 mL of 0.03 mol / L isophthalic acid solution to the mixed solution in step (1) and stir magnetically for 15 min.

[0040] (3) Transfer the mixed solution in step (2) into a 50 mL stainless steel reactor lined with polytetrafluoroethylene, seal the reactor, and place it in a preheated oven at 160 °C for 7.5 h.

[0041] (4) After the reaction is completed, the sample is naturally cooled to room temperature, centrifuged, washed three times with anhydrous ethanol, and then placed in a drying oven at 60°C for 12 h.

[0042] (5) The paper chip pattern was designed using Adobe Illustrator CS6 software. The designed pattern was then transferred to the surface of the paper chip using a solid wax printer. The paper chip was then transferred to an oven for heating so that the wax penetrated the entire thickness of the paper, forming a hydrophilic area surrounded by a hydrophobic wall.

[0043] (6) Cut the paper chip obtained in step (5) into individual paper chips.

[0044] (7) Take 100 μL of 2 mg mL -1 The dopamine solution was dripped onto the hydrophilic area of ​​the paper chip and dried at room temperature. The dripping was repeated twice to obtain a dopamine-functionalized hydrophilic area.

[0045] (8) Take 50 μL of 0.5 mg mL -1 The sodium tetrachloropalladate solution was added dropwise to the dopamine functionalized hydrophilic area, dried at room temperature, and the addition was repeated twice.

[0046] (9) Preparation of growth medium

[0047] Take 100 μL of formaldehyde solution and add 50 mL of solution A, where solution A contains 12 mg·mL -1 Sodium hydroxide, 15 mg mL -1 Copper sulfate, 29 mg mL -1 A mixed solution of potassium sodium tartrate, the solution obtained by evenly mixing the two solutions is the growth solution.

[0048] (10) Place the paper chip dried in step (8) into the growth solution prepared in step (9), soak for 30 min, take out and rinse with deionized water, and then dry in a 50°C vacuum drying oven for 1.5 h. Grind the obtained copper paper electrode in the same direction with a mortar until it is smooth.

[0049] (11) Take 0.003 g of the sample in step (4), add 50 μL of 5% Nafion and 950 μL of anhydrous ethanol solution, and disperse by ultrasonic oscillation to form a uniform suspension.

[0050] (12) Take 100 μL of the suspension in step (12) and drop it onto the electrode surface obtained in step (11), and dry it at room temperature for 2 h.

[0051] Example 2

[0052] The preparation steps are the same as those in Example 1, except that 5 mL of 0.02 mol / L terbium nitrate aqueous solution and 0.03 mol / L cobalt nitrate aqueous solution in step (1) are replaced by 0.02 mol / L terbium nitrate solution and 0.03 mol / L cobalt nitrate solution prepared using N,N-dimethylformamide solution as solvent.

[0053] Example 3

[0054] The preparation steps are the same as those in Example 1, except that: in step (1), 5 mL of 0.02 mol / L terbium nitrate aqueous solution and 5 mL of 0.03 mol / L cobalt nitrate aqueous solution are added to 10 mL of N,N-dimethylformamide solution and ultrasonically dispersed for 10 min. Then, 5 mL of 0.03 mol / L isophthalic acid solution is added to the mixed solution in step (1) and ultrasonically dispersed for 15 min.

[0055] Example 4

[0056] The preparation steps are the same as those in Example 1, except that the mixed solution in step (2) is transferred to a 50 mL stainless steel reactor lined with polytetrafluoroethylene, the reactor is sealed and tightened, and placed in a preheated 160°C oven for reaction for 9 h.

Claims

1. A method for preparing a paper-based cobalt-doped terbium metal-organic framework material, characterized in that The following steps are involved: (1) Prepare 0.01~0.03 mol / L terbium nitrate solution, 0.03~0.04 mol / L cobalt nitrate solution, and 0.03~0.04 mol / L isophthalic acid solution; (2) The terbium nitrate solution and the cobalt nitrate solution prepared in step (1) are uniformly dispersed in 10-15 mL of N,N-dimethylformamide solution; (3) uniformly dispersing the isophthalic acid solution prepared in step (1) in the mixed solution of step (2); (4) Transfer the mixed solution of step (3) into a 50 mL stainless steel reactor lined with polytetrafluoroethylene, seal and tighten the reactor, and place it in a preheated oven at 160-170°C for 7-9 h; (5) After the reaction is completed, the sample is naturally cooled to room temperature, centrifuged, washed three times with anhydrous ethanol, and then placed in a drying oven at 60°C for 10-12 h; (6) Designing a paper chip pattern using Adobe Illustrator CS6 software, then transferring the designed pattern to the surface of the paper chip using a solid wax printer, and then transferring it to an oven for heating treatment so that the wax penetrates the entire thickness of the paper to form a hydrophilic area surrounded by a hydrophobic wall; (7) cutting the paper chip obtained in step (6) into individual paper chips; (8) Take 90~110 μL of 2 mg mL -1 The dopamine solution was dripped onto the hydrophilic area of ​​the paper chip, dried at room temperature, and the dripping was repeated twice to obtain the dopamine-functionalized hydrophilic area; (9) Take 50~60 μL of 0.5 mg mL -1 Sodium tetrachloropalladate solution was added dropwise to the hydrophilic area functionalized with dopamine, dried at room temperature, and the addition was repeated twice; (10) Preparation of growth medium Take 80-100 μL of formaldehyde solution and add 45-50 mL of solution A, where solution A contains 12 mg·mL -1 Sodium hydroxide, 15 mg mL -1 Copper sulfate, 29 mg mL -1 A mixed solution of potassium sodium tartrate, the solution obtained by uniformly mixing the two solutions is the growth solution; (11) placing the dried paper chip in step (9) into the growth solution prepared in step (10), soaking for 30 min, taking it out and rinsing it with deionized water, and then drying it in a 50°C vacuum drying oven for 1.5 h. Grinding the obtained copper paper electrode in the same direction with a mortar until it is smooth; (12) Take 0.001-0.003 g of the sample in step (5), add 50 μL of 5% Nafion and 950 μL of anhydrous ethanol solution, and disperse by ultrasonic oscillation to form a uniform suspension; (13) Take 100 μL of the suspension in step (12) and drop it onto the electrode surface obtained in step (11), and dry it at room temperature for 2 h.

2. The method for preparing a paper-based cobalt-doped terbium metal-organic framework material as claimed in claim 1, characterized in that The method for uniformly dispersing the substances in step (2) and step (3) is one of ultrasonic dispersion and magnetic stirring methods.

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