阅读说明：本技术 一种金属-有机框架材料及其制备方法与应用 (Metal-organic framework material and preparation method and application thereof ) 是由 高强 张艳梅 陆楠 陈祥 陈立庄 于 2021-01-18 设计创作，主要内容包括：本发明公开了一种金属-有机框架材料及其制备方法与应用,该金属-有机框架材料化学式为[Cu(btr)-2(hpztr)-2·(pztr～(-1))-2·(NO-3～-)-3]-n,其中,Hpztr为4-(3,5-二甲基吡唑-4-基)-1,2,4-三唑,btr为4,4’-双-1,2,4-三氮唑；该材料的制备方法包括以下步骤：(1)合成Hpztr；(2)合成btr；(3)利用混合溶剂将铜盐和Hpztr、btr进行溶解,得到混合溶液；(4)将混合溶液置于90～100℃恒温干燥箱当中反应,冷却至室温,过滤、洗涤、干燥,即得到金属-有机框架材料；该材料能够应用在去除水中离子中。该材料具有较高的热稳定性和化学稳定性；能够在常温常压下有效吸附富集水中阴离子,尤其是吸附速率高和吸附量大；能够作为一种高效的净水吸附剂用于去除水中的(The invention discloses a metal-organic framework material and a preparation method and application thereof, wherein the chemical formula of the metal-organic framework material is [ Cu (btr) ] 2 (hpztr) 2 ·(pztr ‑1 ) 2 ·(NO 3 ‑ ) 3 ] n Wherein Hpztr is 4- (3, 5-dimethylpyrazole-4-yl) -1,2, 4-triazole, btr is 4, 4' -bis-1, 2, 4-triazole; the preparation method of the material comprises the following steps: (1) synthesizing Hpztr; (2) Synthesizing btr; (3) dissolving copper salt, Hpztr and btr by using a mixed solvent to obtain a mixed solution; (4) placing the mixed solution in a drying oven at a constant temperature of 90-100 ℃ for reaction, cooling to room temperature, filtering, washing and drying to obtain a metal-organic framework material; the material can be used for removing water In the ion. The material has higher thermal stability and chemical stability; can effectively adsorb and enrich anions in water at normal temperature and normal pressure, in particular to The adsorption rate is high and the adsorption capacity is large; capable of being used as a high-efficiency water purification adsorbent for removing water)

1. A metal-organic framework material, characterized in that the chemical formula of the metal-organic framework material is [ Cu (btr) ]₂(hpztr)₂·(pztr^-1)₂·(NO₃ ^-)₃]_nWherein Hpztr is 4- (3, 5-dimethylpyrazole-4-yl) -1,2, 4-triazole, and btr is 4, 4' -bis-1, 2, 4-triazole.

2. The metal-organic framework material of claim 1, wherein the unit cell parameters of the metal-organic framework material are:α＝90°，β＝90°，γ＝90°。

3. a method for preparing the metal-organic framework material according to claim 1, comprising the steps of:

(1) synthesizing an organic ligand 4- (3, 5-dimethylpyrazole-4-yl) -1,2, 4-triazole;

(2) synthesizing organic ligand 4, 4' -bis-1, 2, 4-triazole;

(3) dissolving copper salt and organic ligand 4- (3, 5-dimethylpyrazole-4-yl) -1,2, 4-triazole and 4, 4' -bis-1, 2, 4-triazole by using a mixed solvent to obtain a mixed solution;

(4) and (3) placing the mixed solution in a drying oven with a constant temperature of 90-100 ℃ for reaction, cooling to room temperature, filtering, washing and drying to obtain the metal-organic framework material.

4. The method for preparing a metal-organic framework material according to claim 3, wherein the step 1 comprises the steps of:

(11) dissolving 4-nitro-3, 5-dimethylpyrazole and KOH in deionized water, heating to 90-100 deg.C, adding SnCl₂·2H₂Keeping the temperature unchanged, continuously reacting, cooling to room temperature after complete reaction, filtering a solid product, washing and drying; obtaining a 4-amino-3, 5-dimethylpyrazole intermediate;

(12) dissolving the 4-amino-3, 5-dimethylpyrazole ligand intermediate, N' -bis (dimethylaminomethylene) hydrazine and p-toluenesulfonic acid in o-xylene, stirring, refluxing, reacting, cooling to room temperature after the reaction is finished, filtering, and washing with xylene and ethanol to obtain the organic ligand 4- (3, 5-dimethylpyrazole-4-yl) -1,2, 4-triazole.

5. The method for preparing metal-organic framework material according to claim 4, wherein 4-nitro-3, 5-dimethylpyrazole, KOH and SnCl are used in step 11₂·2H₂The mass ratio of O is 1: 8-10: 5-6; in the step 12, the mass ratio of 4-amino-3, 5-dimethylpyrazole to N, N' -bis (dimethylaminomethylene) hydrazine to p-toluenesulfonic acid is 1: 1-2: the use amount of 0.05-0.1, 4-amino-3, 5-dimethylpyrazole and o-xylene is 1 g: 7-10 mL.

6. The method for preparing a metal-organic framework material according to claim 3, wherein the step 2 comprises the steps of:

(21) dissolving N, N' -bis (dimethylaminomethylene) hydrazine hydrochloride and 4-amino-1, 2, 4-triazole in toluene;

(22) heating and refluxing for reaction, filtering the obtained precipitate, washing with cold methanol, and drying to obtain the 4, 4' -bis-1, 2, 4-triazole.

7. The method for preparing a metal-organic framework material according to claim 6, wherein the mass ratio of 4-amino-1, 2, 4-triazole to N, N' -bis (dimethylaminomethylene) hydrazine hydrochloride in step 21 is 1: 1-2 g of 1-3, 4-amino-1, 2, 4-triazole and toluene: 20 mL.

8. The method for preparing a metal-organic framework material according to claim 3, wherein the volume ratio of the mixed solvent in the step 3 is 3-2: 1, copper salt is copper nitrate trihydrate, the molar ratio of the copper salt to an organic ligand 4- (3, 5-dimethylpyrazole-4-yl) -1,2, 4-triazole to 4, 4' -bis-1, 2, 4-triazole is 1-2: 1: 1.

9. use of the metal-organic framework material of claim 1 for the removal of water anions.

10. Use according to claim 9, wherein the anion isIons.

Technical Field

The invention relates to a material and a preparation method and application thereof, in particular to a metal-organic framework material and a preparation method and application thereof.

Background

Water is one of the most precious natural resources on the earth, and has irreplaceable significance for the survival and development of human beings, animals, plants and the like. However, with the expansion of human activities and the rapid development of modern industries, water pollution is becoming more severe and has become a serious problem in common worldwide. Various harmful substances are introduced into water bodies by industrial waste residue disposal, chemical wastewater discharge, nuclear waste leakage, pesticide over-standard use and the like. The common heavy metal ions in the wastewater mainly comprise arsenic, copper, chromium, lead, mercury, nickel, zinc ions and the like. Excessive levels of these ions pose a significant threat to the survival of humans and other living beings. The removal of these heavy metal ions from water is usually achieved by adsorption or ion exchange through porous materials. At present, common porous materials for removing heavy metal ion pollutants in water mainly comprise zeolite, activated carbon, clay, aluminum phosphate and the like. Most of these porous materials are readily available and relatively low cost. However, the specific surface area of the material is low, and the surface modification is difficult, so that the removal rate and the adsorption quantity of pollutants are poor, and the performance of the material is not ideal.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a metal-organic framework material which can adsorb heavy metal ions in water, has high adsorption speed and good stability, and also aims to provide a preparation method of the metal-organic framework material and an application of the metal-organic framework material.

The technical scheme is as follows: the chemical formula of the metal-organic framework material is [ Cu (btr) ]₂(hpztr)₂·(pztr^-1)₂·(NO₃ ^-)₃]_nWherein Hpztr is 4- (3, 5-dimethylpyrazole-4-yl) -1,2, 4-triazole, and btr is 4, 4' -bis-1, 2, 4-triazole.

Wherein the unit cell parameters of the metal-organic framework material are as follows:α＝90°，β＝90°，γ＝90°。

the preparation method of the metal-organic framework material comprises the following steps:

(1) synthesizing an organic ligand 4- (3, 5-dimethylpyrazole-4-yl) -1,2, 4-triazole;

(2) synthesizing organic ligand 4, 4' -bis-1, 2, 4-triazole;

(3) dissolving copper salt and organic ligand 4- (3, 5-dimethylpyrazole-4-yl) -1,2, 4-triazole and 4, 4' -bis-1, 2, 4-triazole by using a mixed solvent to obtain a mixed solution;

(4) and (3) placing the mixed solution in a drying oven with a constant temperature of 90-100 ℃ for reaction, cooling to room temperature, filtering, washing and drying to obtain the metal-organic framework material.

Wherein, step 1 includes the following steps:

(11) dissolving 4-nitro-3, 5-dimethylpyrazole and KOH in deionized water, heating to 90-100 deg.C, adding SnCl₂·2H₂O, keeping the temperature unchanged, continuing the reaction, cooling to room temperature after the reaction is completed, filtering the solid product, and washingWashing and drying; obtaining a 4-amino-3, 5-dimethylpyrazole intermediate;

(12) dissolving the 4-amino-3, 5-dimethylpyrazole ligand intermediate, N' -bis (dimethylaminomethylene) hydrazine and p-toluenesulfonic acid in o-xylene, stirring, refluxing, reacting, cooling to room temperature after the reaction is finished, filtering, and washing with xylene and ethanol to obtain the organic ligand 4- (3, 5-dimethylpyrazole-4-yl) -1,2, 4-triazole.

Wherein, in the step 11, 4-nitro-3, 5-dimethylpyrazole, KOH and SnCl are adopted₂·2H₂The mass ratio of O is 1: 8-10: 5-6; in the step 12, the mass ratio of 4-amino-3, 5-dimethylpyrazole to N, N' -bis (dimethylaminomethylene) hydrazine to p-toluenesulfonic acid is 1: 1-2: the use amount of 0.05-0.1, 4-amino-3, 5-dimethylpyrazole and o-xylene is 1 g: 7-10 mL.

Wherein, step 2 includes the following steps:

(21) dissolving N, N' -bis (dimethylaminomethylene) hydrazine hydrochloride and 4-amino-1, 2, 4-triazole in toluene;

(22) heating and refluxing for reaction, filtering the obtained precipitate, washing with cold methanol, and drying to obtain the 4, 4' -bis-1, 2, 4-triazole.

Wherein, in the step 21, the mass ratio of the 4-amino-1, 2, 4-triazole to the N, N' -bis (dimethylaminomethylene) hydrazine hydrochloride is 1: 1-2 g of 1-3, 4-amino-1, 2, 4-triazole and toluene: 20 mL.

Wherein, the volume ratio of the mixed solvent in the step 3 is 3-2: 1, copper salt is copper nitrate trihydrate, the molar ratio of the copper salt to an organic ligand 4- (3, 5-dimethylpyrazole-4-yl) -1,2, 4-triazole to 4, 4' -bis-1, 2, 4-triazole is 1-2: 1: 1.

the metal-organic framework material can be applied to removing water anions, wherein the anions areIons.

The working principle is as follows: 4, 4' -bis-1, 2, 4-triazole is a neutral ligand, and the molecule is coordinated with positively charged metal cations, so that the maximum degree of coordination can be realizedSo as to ensure that the main skeleton of the MOFs prepared is positive. According to the theory of soft and hard acids and bases, Cu⁺The ions are selected to further ensure counter ions (NO) in the system₃ ^-) Does not participate in coordination. The two points fundamentally endow the material with the capability of adsorbing toxic anions in an ion exchange mode. In addition, N sites abundant in two molecules of 4- (3, 5-dimethylpyrazole-4-yl) -1,2, 4-triazole and 4, 4' -bis-1, 2, 4-triazole are main frameworks andhydrogen bonds are formed, and further, the improvement of the adsorption quantity and the selectivity provides guarantee.

Has the advantages that: compared with the prior art, the invention has the following remarkable advantages: 1. has higher thermal stability and chemical stability; 2. can effectively adsorb and enrich anions in water at normal temperature and normal pressure; the adsorption rate is high and the adsorption capacity is large; capable of being used as a high-efficiency water purification adsorbent for removing water。

Drawings

FIG. 1 is a diagram of coordination environment of a metal-organic framework material;

FIG. 2 is a three-dimensional block diagram of a metal-organic framework material;

FIG. 3 is a graph of actual test and simulated XRD contrast for metal-organic framework materials;

FIG. 4 is an XRD pattern measured after immersion of the metal-organic framework material in aqueous solutions of different pH values;

FIG. 5 is an XRD pattern measured after immersion of the metal-organic framework material in an organic solvent;

FIG. 6 is a thermogravimetric plot of a metal-organic framework material;

FIG. 7 shows adsorption of metal-organic framework materialsComparing the front IR spectrogram with the rear IR spectrogram;

FIG. 8 shows the adsorption of the metal-organic framework material in example 1A light absorption spectrum in the process;

FIG. 9 shows the adsorption of the metal-organic framework material in example 2A light absorption spectrum in the process;

FIG. 10 shows the adsorption of the metal-organic framework material in example 3Light absorption spectra in the process.

Detailed Description

Example 1

(1) Synthesis of organic ligand 4- (3, 5-dimethylpyrazol-4-yl) -1,2, 4-triazole Hpztr:

synthesis of 4-amino-3, 5-dimethylpyrazole ligand intermediate: 5.07g, 36mmol of 4-nitro-3, 5-dimethylpyrazole and 40.0g of KOH are dissolved in 100mL of deionized water, which is heated to 90 ℃ in an oil bath, and 27.57g, 122mmol of SnCl are weighed₂·2H₂Adding O into the system for three times, keeping the temperature constant at the feeding interval of 1 hour, continuously reacting for 6 hours, cooling to room temperature, filtering a solid product, washing with 3mL of ice water, and drying to obtain 2.60g of a 4-amino-3, 5-dimethylpyrazole ligand intermediate with the yield of about 65%;

synthesis of 4- (3, 5-dimethylpyrazol-4-yl) -1,2, 4-triazole Hpztr ligand: 3.33g, 30mmol of 4-amino-3, 5-dimethylpyrazole, 4.69g, 33mmol of N, N' -bis (dimethylaminomethylene) hydrazine and 0.24g, 1.3mmol of p-toluenesulfonic acid were dissolved in 25mL of o-xylene, stirred under reflux for 24h, after completion of the reaction, the system was cooled to room temperature, filtered, washed with xylene and ethanol to give 3.28g of 4- (3, 5-dimethylpyrazol-4-yl) -1,2, 4-triazole Hpztr ligand, yield was about 67%, formula:

(2) synthesizing an organic ligand 4, 4' -bis-1, 2, 4-triazole btr:

3.30g, 15.4mmol of N, N '-bis (dimethylaminomethylene) hydrazine hydrochloride and 1.55g, 18.4mmol of 4-amino-1, 2, 4-triazole are dissolved in 20mL of toluene, heated to 110 ℃ and refluxed for 12h, the resulting precipitate is filtered, washed with cold methanol and dried in vacuo to give 1.77g of synthetic organic ligand 4, 4' -bis-1, 2, 4-triazole btr as a white powder in 86.4% yield, of the formula:

(3) weighing 0.20mmol of copper nitrate trihydrate, 0.10mmol of organic ligand 4- (3, 5-dimethylpyrazole-4-yl) -1,2, 4-triazole Hptr and 0.10mmol of organic ligand 4, 4' -bis-1, 2, 4-triazole btr, adding the mixture into a 20mL high-temperature resistant glass bottle, and adding a mixed solvent with the total volume of 8mL, wherein the volume ratio of the mixed solvent is 3: 1 of methanol and deionized water;

(4) sealing the glass bottle, placing the glass bottle into a constant temperature drying oven, reacting for 2 days at 90 ℃, slowly cooling to room temperature, and filtering to obtain 65mg of colorless transparent blocky crystals, namely the metal organic framework material [ Cu (btr) ]₂(hpztr)₂·(pztr^-1)₂·(NO₃ ^-)₃]_nThe yield was about 67%,

[Cu(btr)₂(hpztr)₂·(pztr^-1)₂·(NO₃ ^-)₃]_nthe actual XRD pattern and the simulated XRD pattern are shown in figure 3, and XRD diffraction peaks in the two patterns can be well matched, which means that the molecular structure of the obtained material is consistent with the result obtained by single crystal diffraction, and the material has high phase purity. To examine the chemical stability of the resulting MOF material, [ Cu (btr) ]₂(hpztr)₂·(pztr^-1)₂·(NO₃ ^-)₃]_nThe sample was immersed in an aqueous solution at pH 1, pH 3, pH 7 and pH 13, respectively, and the XRD of the sample was measured after 12 hours. As shown in FIG. 4, inUnder the near-neutral or acidic condition, the XRD of the MOF material is not obviously changed. This means that the skeleton can remain intact under the respective conditions. However, the sample soaked in the alkaline aqueous solution at pH 13 had no sharp diffraction peak, and the skeleton collapsed under this condition. Will [ Cu (btr)₂(hpztr)₂·(pztr^-1)₂·(NO₃ ^-)₃]_nSoaking in DMF, ethanol, acetonitrile, deionized water and K₂Cr₂O₇In aqueous solution, XRD of the sample after soaking was tested for 12 h. The spectrum is shown in fig. 5, the diffraction peak of the soaked sample can better correspond to the peak of the newly prepared sample, which means that the framework of the MOF can not be obviously damaged within 12 hours when the sample is soaked in the solution or the solvent. To [ Cu (btr) ]₂(hpztr)₂·(pztr^-1)₂·(NO₃ ^-)₃]_nPerforming thermogravimetric testing, wherein the testing conditions are as follows: under the protection of nitrogen, the temperature rise interval is from room temperature to 800 ℃, and the temperature rise rate is 10 ℃ min^-1The atlas is shown in fig. 6, and three obvious weight loss processes exist in the curve. The first weight loss process occurs at about 60 ℃, and is a process for removing solvents such as methanol, water and the like in the framework. The two weight loss processes after 200 ℃ should correspond to the destruction of the framework and the decomposition of the organic components.

[Cu(btr)₂(hpztr)₂·(pztr^-1)₂·(NO₃ ^-)₃]_nAdsorptionAnd (3) performance testing:

0.05mmol of [ Cu (btr) ]₂(hpztr)₂·(pztr^-1)₂·(NO₃ ^-)₃]_nSoaking in 20mL of solution with the concentration of 0.0025 mol.L^-1K of₂Cr₂O₇In an aqueous solution, wherein [ Cu (btr) ]₂(hpztr)₂·(pztr^-1)₂·(NO₃ ^-)₃]_nAndthe molar ratio is 1:1, the mixture is magnetically stirred for 48 hours at room temperature, and the ultraviolet-visible spectrum pair is utilizedThe adsorption process of (1) was monitored, 0.2mL of the supernatant was removed at different times, and the UV-Vis adsorption intensity was determined, and the test chart is shown in FIG. 8, in which the intensity of the absorption peak gradually decreased with the time of the experiment, which means that the supernatant was in the form of a supernatantThe content of (A) is gradually reduced, and the MOF can effectively remove the adsorbed substances. By measuring K₂Cr₂O₇The decoloring of the aqueous solution was evaluated by calculating [ Cu (btr) ]₂(hpztr)₂·(pztr^-1)₂·(NO₃ ^-)₃]_nAdsorption capacity of (2):

wherein D is the adsorption capacity, C₀，A₀And C₁，A₁Respectively is K at 257nm of adsorption equilibrium peak before and after anion exchange₂Cr₂O₇Concentration of aqueous solution and absorbance. After 48 hours of continuous adsorption, about 39 percent of Cr is contained₂O₇ ^2-Is enriched in the metal organic framework. Thereafter, the crystals in the solution were filtered off, rinsed with deionized water, dried in air and the XRD and IR tests were performed on these samples; adsorption of metal-organic framework materialsFront and back IR comparison spectra. As shown in FIG. 7, NO in the sample after adsorption test₃ ^-The corresponding characteristic peak is obviously weakenedThe characteristic peak of (a) is enhanced. The test results confirm that the adsorption process does not work for the MOF material as a wholeThe integrity of the skeleton is destroyed, and the original NO in the skeleton₃ ^-Is partially exchanged into。

Example 2

(1) Synthesis of organic ligand 4- (3, 5-dimethylpyrazol-4-yl) -1,2, 4-triazole Hpztr:

synthesis of 4-amino-3, 5-dimethylpyrazole ligand intermediate: 5.07g, 36mmol of 4-nitro-3, 5-dimethylpyrazole and 51.0g of KOH are dissolved in 100mL of deionized water, heated to 90 ℃ in an oil bath, and 27.0g of SnCl is weighed₂·2H₂Adding O into the system for three times, keeping the temperature constant at the feeding interval of 1 hour, continuously reacting for 6 hours, cooling to room temperature, filtering a solid product, washing with 3mL of ice water, and drying to obtain 2.10g of a 4-amino-3, 5-dimethylpyrazole ligand intermediate with the yield of about 52 percent;

synthesis of 4- (3, 5-dimethylpyrazol-4-yl) -1,2, 4-triazole Hpztr ligand: dissolving 3.33g, 30mmol of 4-amino-3, 5-dimethylpyrazole, 3.50g of N, N' -bis (dimethylaminomethylene) hydrazine and 0.16g of p-toluenesulfonic acid in 25mL of o-xylene, stirring and refluxing for 24h, after the reaction is finished, cooling the system to room temperature, filtering, and washing with xylene and ethanol to obtain 2.8g of 4- (3, 5-dimethylpyrazol-4-yl) -1,2, 4-triazole Hpztr ligand with the yield of about 56%;

(2) synthesizing an organic ligand 4, 4' -bis-1, 2, 4-triazole btr:

dissolving 2g of N, N '-bis (dimethylaminomethylene) hydrazine hydrochloride and 1.55g of 4-amino-1, 2, 4-triazole in 20mL of toluene, heating to 110 ℃ and refluxing for 12h, filtering the obtained precipitate, washing with cold methanol, and drying in vacuum to obtain 0.95g of synthetic organic ligand 4, 4' -bis-1, 2, 4-triazole btr as white powder with a yield of about 60.4%;

(3) weighing 0.10mmol of copper nitrate trihydrate, 0.10mmol of organic ligand 4- (3, 5-dimethylpyrazole-4-yl) -1,2, 4-triazole Hptr and 0.10mmol of organic ligand 4, 4' -bis-1, 2, 4-triazole btr, adding the mixture into a 20mL high-temperature resistant glass bottle, and adding a mixed solvent with the total volume of 4mL, wherein the volume ratio of the mixed solvent is 3: 1 of methanol and deionized water;

(4) sealing the glass bottle, placing the glass bottle into a constant temperature drying oven, reacting for 2 days at 90 ℃, slowly cooling to room temperature, and filtering to obtain 30mg of colorless transparent blocky crystals, namely the metal organic framework material [ Cu (btr) ]₂(hpztr)₂·(pztr^-1)₂·(NO₃ ^-)₃]_nThe yield is 35 percent,

[Cu(btr)₂(hpztr)₂·(pztr^-1)₂·(NO₃ ^-)₃]_nadsorptionAnd (3) performance testing:

0.1mmol of [ Cu (btr) ]₂(hpztr)₂·(pztr^-1)₂·(NO₃ ^-)₃]_nSoaking in 20mL of solution with the concentration of 0.0025 mol.L^-1K of₂Cr₂O₇In an aqueous solution, wherein [ Cu (btr) ]₂(hpztr)₂·(pztr^-1)₂·(NO₃ ^-)₃]_nAndthe molar ratio is 2:1, the mixture is magnetically stirred for 48 hours at room temperature, and the ultraviolet-visible spectrum pair is utilizedThe adsorption process of (1) was monitored, 0.2mL of the supernatant was removed at different times and the UV-Vis adsorption strength was determined, as shown in FIG. 9, with the absorption intensity decreasing with the time of the experiment and with continuous adsorption for 48h, about 77% of Cr was present₂O₇ ^2-Is enriched in the metal organic framework.

Example 3

(1) Synthesis of organic ligand 4- (3, 5-dimethylpyrazol-4-yl) -1,2, 4-triazole Hpztr:

synthesis of 4-amino-3, 5-dimethylpyrazole ligand intermediate: 5.07g, 36mmol of 4-nitro-3, 5-dimethylpyrazole and 40.0g of KOH are dissolved in 100mL of deionized water, which is heated to 90 ℃ in an oil bath, and 27.57g, 122mmol of SnCl are weighed₂·2H₂Adding O into the system for three times, keeping the temperature constant at the feeding interval of 1 hour, continuously reacting for 6 hours, cooling to room temperature, filtering a solid product, washing with 3mL of ice water, and drying to obtain 2.60g of a 4-amino-3, 5-dimethylpyrazole ligand intermediate with the yield of about 65%;

synthesis of 4- (3, 5-dimethylpyrazol-4-yl) -1,2, 4-triazole Hpztr ligand: 3.33g, 30mmol of 4-amino-3, 5-dimethylpyrazole, 4.69g of 33mmol of N, N' -bis (dimethylaminomethylene) hydrazine and 0.24g, 1.3mmol of p-toluenesulfonic acid were dissolved in 25mL of o-xylene, stirred under reflux for 24h, after completion of the reaction, the system was cooled to room temperature, filtered, washed with xylene and ethanol to give 3.28g of 4- (3, 5-dimethylpyrazol-4-yl) -1,2, 4-triazole Hpztr ligand in about 67% yield:

(2) synthesizing an organic ligand 4, 4' -bis-1, 2, 4-triazole btr:

3.30g, 15.4mmol of N, N '-bis (dimethylaminomethylene) hydrazine hydrochloride and 1.55g, 18.4mmol of 4-amino-1, 2, 4-triazole are dissolved in 20mL of toluene, heated to 110 ℃ under reflux for 12h, the resulting precipitate is filtered, washed with cold methanol and dried in vacuo to give 1.77g of synthetic organic ligand 4, 4' -bis-1, 2, 4-triazole btr as a white powder in 86.4% yield:

(3) weighing 0.10mmol of copper nitrate trihydrate, 0.10mmol of organic ligand 4- (3, 5-dimethylpyrazole-4-yl) -1,2, 4-triazole Hptr and 0.10mmol of organic ligand 4, 4' -bis-1, 2, 4-triazole btr, adding the mixture into a 20mL high-temperature resistant glass bottle, and adding a mixed solvent with the total volume of 8mL, wherein the volume ratio of the mixed solvent is 3: 1 of methanol and deionized water;

(4) sealing the glass bottle, placing the glass bottle into a constant temperature drying oven, reacting for 2 days at 90 ℃, slowly cooling to room temperature, and filtering to obtain 65mg of colorless transparent blocky crystals, namely the metal organic framework material [ Cu (btr) ]₂(hpztr)₂·(pztr^-1)₂·(NO₃ ^-)₃]_nThe yield was 67%.

[Cu(btr)₂(hpztr)₂·(pztr^-1)₂·(NO₃ ^-)₃]_nAdsorptionAnd (3) performance testing:

0.4mL of deionized water is added to the solution with the concentration of 0.0025 mol.L^-1K of₂Cr₂O₇The aqueous solution was diluted to 20 mL. Cr in the obtained solution₂O₇ ^2-The corresponding concentration of (B) is 14.7ppm, stirring is carried out for 48 hours under the magnetic force at room temperature, and the ultraviolet-visible spectrum pair is utilizedThe adsorption process of (1) was monitored, 0.2mL of the supernatant was removed at different times and the UV-Vis adsorption strength was determined, the test chart is shown in FIG. 10, after a period of adsorption, the absorbance strength decreased significantly, and after 48h of continuous adsorption, about 33% of Cr was present₂O₇ ^2-Is enriched in the metal organic framework.