CN114133581B - Mg-MOFs, preparation method thereof and application thereof in iron ion detection - Google Patents

Abstract

The present invention relates to a novel Mg-MOFs, its preparation method and its application in the detection of iron ions. The structural formula of the Mg-MOFs is [Mg(L)xG], wherein L is a quadrilateral containing a tetracarboxylic acid group A symmetrical ligand, G is a solvent molecule coordinated with magnesium ions or in the crystal channel. The preparation method of Mg-MOFs is: dissolving metal magnesium salt and ligand L in a mixed solution of organic solvent and water; after ultrasonic uniformity, sealing and placing in an oven at 100°C-120°C for 24-72 hours; naturally cooling to room temperature, Washed, filtered and dried to obtain Mg‑MOFs material. Thanks to the unique structure, the Mg-MOFs material prepared by the present invention has a significant fluorescence response to metal iron ions, so it has potential application prospects in the detection of metal iron ions.

Description

A kind of Mg-MOFs, its preparation method and its application in iron ion detection

technical field

The invention relates to the preparation and application of Mg-MOFs, specifically, the Mg-MOFs can be used as fluorescent probes for detecting metal ions.

Background technique

Ferric ions are widely present in organisms, and they play important roles in biochemical processes such as oxygen transport, hemoglobin formation, cell metabolism and DNA replication. The lack or excess of ferric ions can lead to anemia, mental decline, arthritis, diabetes, cancer and other physical diseases. Therefore, the selective and sensitive detection of ferric ions relative to other metal ions is of great significance. At present, the traditional methods for detecting metal ions mainly include ion mobility spectrometry (IMS), high performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LCMS). Time. Therefore, there is an urgent need for a rapid and efficient detection technology for this specific environmental pollutant.

In recent years, luminescent metal-organic frameworks (LMOFs) have attracted increasing attention for their applications in sensing due to their diverse structures and topologies, outstanding optical properties, and emission wavelengths. Currently, most LMOFs for fluorescence detection are mostly based on transition or lanthanide metal ions, while LMOFs constructed from alkaline earth metal ions are rarely used in fluorescence detection, which may be due to difficulties in their crystallization process. and unpredictable coordination patterns. In fact, alkaline earth metal-organic frameworks have many unparalleled advantages, such as low density, bio-friendliness, non-toxicity and low cost, etc.; more importantly, when alkaline earth metal-organic frameworks are used as When using fluorescent probes, secondary pollution caused by heavy metal ions can be effectively avoided. Therefore, the alkaline earth metal-organic framework material is a very potential fluorescent material that can be applied to the detection of metal ions.

Contents of the invention

The purpose of the present invention is to provide a kind of Mg-MOFs and its preparation method and the application in metal ion detection, this Mg-MOFs has high selectivity and high sensitivity to ferric ion, can be used as fluorescent probe to monitor trivalent Iron ions.

The Mg-MOFs used to detect metal ions of the present invention has a long-range ordered crystal structure and regular channels, and its chemical formula is [Mg(L)xG], wherein L is N, N, N', N'-tetra (4-carboxyphenyl)-1,4-phenylenediamine, tetrakis(4-carboxyphenyl)methane, 4',5'-bis(4-carboxyphenyl)-3',6'-dimethyl -[1,1':2',1"-terphenyl]-4,4"-dicarboxylic acid, 4',5'-bis(4-carboxyphenyl)-3',6'-dihydroxy- [1,1':2',1"-terphenyl]-4,4"-dicarboxylic acid, x=1-4; G represents the solvent molecule coordinated with the magnesium ion or in the crystal channel, which is N, N-dimethylformamide, N,N-dimethylacetamide or N,N-diethylformamide.

The preparation method of Mg-MOFs for detecting metal ions of the present invention comprises the following steps: dissolving metal magnesium salt and quadrilateral symmetrical ligands containing tetracarboxylic acid groups in water, ethanol and organic solvents to obtain a mixed solution, The obtained solution was put into a glass bottle, heated and reacted at 100°C-120°C for 24-72 hours, naturally cooled to room temperature, centrifuged, washed, filtered and dried to obtain Mg-MOFs.

Further, the metal magnesium salt used is one or more of magnesium nitrate, magnesium sulfate, magnesium acetate or magnesium chloride.

Further, the tetragonal symmetrical ligands containing tetracarboxylic acid groups used are (a) N,N,N',N'-tetrakis(4-carboxyphenyl)-1,4-phenylenediamine, (b) Tetrakis(4-carboxyphenyl)methane, (c) 4',5'-bis(4-carboxyphenyl)-3',6'-dimethyl-[1,1':2',1"- Terphenyl]-4,4"-dicarboxylic acid or (d) 4',5'-bis(4-carboxyphenyl)-3',6'-dihydroxy-[1,1':2',1 "-Terphenyl]-4,4"-dicarboxylic acid, the structural formulas of the four are as follows:

Further, the organic solvent used is any one of N,N-dimethylformamide, N,N-dimethylacetamide or N,N-diethylformamide. And wherein the volume ratio of water, ethanol, and organic solvent is 1:1:2-5.

Further, the molar ratio of the metal magnesium ion to the organic ligand in the metal magnesium salt used is 1-4:1.

The application of the Mg-MOFs for detecting metal ions provided by the present invention is characterized in that it is used as a fluorescent probe for detecting ferric ions contained in the system.

Further, the detection method is: ultrasonically disperse the prepared Mg-MOFs in the solution, and then drop the solution to be detected in situ for fluorescence detection.

The concrete beneficial effects of the present invention are:

a＝β＝γ＝90°，晶胞体积为

Z＝2，D_c＝0.851。1. The preparation method of the Mg-MOFs of the present invention is a solvothermal method, the synthesis method has simple process, mild conditions, and the yield is as high as 60%-65%. After dissolving the reaction raw materials, react at 100-120°C to obtain the desired substance. There are no poisonous and harmful substances and catalysts in all the raw materials used, and no toxic and harmful substances are produced during the preparation process. The obtained porous material has a novel structure, a long-range ordered crystal structure and regular channels. The porous material belongs to the orthorhombic crystal system, the space group is Imma, and the unit cell parameters are

a=β=γ=90°, the unit cell volume is

Z = 2, Dc = _0.851 .

2. The Mg-MOFs is a three-dimensional infinite network structure formed by a magnesium chain composed of four magnesium ions and a quadrilateral symmetrical ligand connection of a deprotonated tetracarboxylic acid group, and each magnesium chain is connected with 8 deprotonated The quadrilaterally symmetrical ligands of the tetracarboxylic acid groups of each deprotonated tetracarboxylic acid group link four magnesium chains.

3. Compared with other rare earth organic frameworks and transition metal organic frameworks, the Mg-MOFs prepared by the present invention is a crystalline material with an ordered microporous structure, has a long-range ordered crystal structure and regular channels, and can pass through The design of the framework structure and the adjustment of the pore size obtain a larger ion distance, so that metal ions can enter the pore and improve the detection efficiency; and the coordination of the ligand carboxyl oxygen in the structure remains uncoordinated, so it is very important for selective sensing. Trace metals provide additional benefits.

4. The Mg-MOFs prepared by the present invention have relatively excellent stability. After soaking in the solution of iron ions for 12 hours, its powder X-ray spectrum can still correspond well to that before soaking, which proves that it has better stability. The stability ensures its application in the field of fluorescence detection.

5. The Mg-MOFs prepared by the present invention have excellent luminescent properties, and it can specifically recognize ions immersed in metallic iron liquid. When detecting metal iron ions, it will not be interfered by copper ions, zinc ions, potassium ions, lithium ions, barium ions, cadmium ions, nickel ions, sodium ions, chloride ions, calcium ions, lead ions and cobalt ions. The detection of ferric ions exhibits excellent selectivity.

6. Compared with other technologies for detecting ferric ions, the use of Mg-MOFs of the present invention can realize quenching detection of ferric ions. This method has high sensitivity, less sampling volume, relatively cheaper equipment, and can be conveniently It is applied to the direct detection, labeling and identification of biological systems, so it has great significance and prospects for metal ions.

Description of drawings

Fig. 1 is the crystal structure figure of Mg-MOFs of the present invention;

Fig. 2 is the concentration variation relationship between Mg-MOFs and ferric ions in Example 1 of the present invention;

Fig. 3 is the selectivity experiment result of Mg-MOFs in the embodiment 1 of the present invention for other metal ion interferers;

Fig. 4 is the stability result of the Mg-MOFs in Example 1 of the present invention soaked in the ferric ion solution for 12 hours.

detailed description

Example 1:

Using magnesium nitrate and N,N,N',N'-tetrakis(4-carboxyphenyl)-1,4-phenylenediamine, Mg-MOFs (named ZJU-118) were synthesized by solvothermal method. The specific synthesis The route is as follows:

Dissolve 0.06 mmol of magnesium nitrate and 0.02 mmol of N,N,N',N'-tetrakis(4-carboxyphenyl)-1,4-phenylenediamine in water, ethanol and N,N-dimethylformaldehyde In amide (DMF), the volume ratio of water, ethanol and DMF is 1:1:4. Put the obtained mixed solution into a glass bottle, heat and react at 110°C for 24 hours, cool naturally to room temperature, centrifuge, wash, and filter and dried to give Mg(L ₁ ) ₄ DMF in 65.1% yield

从C轴看，孔道尺寸约为

在370nm的激发下，所得到的发射光谱的峰值位于450nm左右，随着三价铁离子含量增加，其发射光谱强度降低，其发射光谱强度的比值与三价铁离子的加入量有很好的线性关系，可以用下面的公式拟合According to single crystal X-ray diffraction analysis, Mg(L ₁ ) ₄ DMF has a long-range ordered crystal structure and a regular three-dimensional pore structure. Viewed from the A axis, the pore size is about

Viewed from the C axis, the channel size is approx.

Under the excitation of 370nm, the peak value of the obtained emission spectrum is located at about 450nm. As the content of ferric ions increases, the intensity of the emission spectrum decreases, and the ratio of the intensity of the emission spectrum to the amount of ferric ions added has a good relationship. The linear relationship can be fitted with the following formula

I=0.852+0.253[AA]

Where [AA] is the amount of iron ions added (in M), and I is the luminous intensity. It can be seen from Figure 2 that the fluorescence intensity of the Mg-MOFs decreases when the concentration of iron ions is very low, which indicates that the detection limit of the Mg-MOFs for iron ions is low, which can reach 6.75 μM after testing.

In order to investigate the selective response of the Mg-MOFs to iron ions, different interfering substances were added to the system and the fluorescence changes were detected. After adding other interferents: copper ions, zinc ions, potassium ions, lithium ions, barium ions, cadmium ions, nickel ions, sodium ions, chloride ions, calcium ions, lead ions and cobalt ions, then add 200 μL of the same concentration and 400 μL of iron ion solution, the change of the fluorescence intensity emitted at 450nm is not affected by other interfering substances, so as to realize the specific recognition of iron ion, the results are shown in Figure 3.

The powder X-ray diffraction pattern of the newly synthesized Mg(L ₁ ) ₄ DMF is in good agreement with its single crystal simulation X-ray diffraction pattern, which proves that the material has a long-range ordered crystal structure and good crystallinity. After immersing Mg(L ₁ ) ₄ DMF in ferric ion solution for 12 hours, its powder X-ray diffraction pattern can still be in good agreement with its single crystal simulation X-ray diffraction pattern, proving that it has good stability (Fig. 4 ), the integrity of this structure is still maintained in the process of detecting iron ions, and it can be reused.

Example 2:

Mg-MOFs were synthesized by solvothermal method using magnesium chloride and tetrakis(4-carboxyphenyl)methane. The specific synthetic route is as follows:

Dissolve 0.08mmol of magnesium chloride and 0.02mmol of tetrakis(4-carboxyphenyl)methane in water, ethanol and N,N-dimethylacetamide (DMA), and the volume ratio of water, ethanol and DMA is 1:1: 2. Put the obtained mixed solution into a glass bottle, heat the reaction at 100°C for 48 hours, naturally cool to room temperature, centrifuge, wash, filter and dry to obtain Mg(L ₂ ) ₂ DMA with a yield of 62.4%

从C轴看，孔道尺寸约为

在370nm的激发下，所得到的发射光谱的峰值位于450nm左右，随着三价铁离子含量增加，其发射光谱强度降低，其发射光谱强度的比值与三价铁离子的加入量有很好的线性关系。According to single crystal X-ray diffraction analysis, Mg(L ₂ ) ₂ DMA has a long-range ordered crystal structure and a regular three-dimensional pore structure. Viewed from the A axis, the pore size is about

Viewed from the C axis, the channel size is approx.

Under the excitation of 370nm, the peak value of the obtained emission spectrum is located at about 450nm. As the content of ferric ions increases, the intensity of the emission spectrum decreases, and the ratio of the intensity of the emission spectrum to the amount of ferric ions added has a good relationship. linear relationship.

In order to investigate the selective response of the Mg-MOFs to iron ions, different interfering substances were added to the system and the fluorescence changes were detected. After adding other interferents: copper ions, zinc ions, potassium ions, lithium ions, barium ions, cadmium ions, nickel ions, sodium ions, chloride ions, calcium ions, lead ions and cobalt ions, then add 200 μL of the same concentration and 400 μL of iron ion solution, the change of the fluorescence intensity emitted at 450nm is not affected by other interfering substances, so as to realize the specific recognition of iron ion.

The powder X-ray diffraction pattern of the newly synthesized Mg(L ₂ ) ₂ DMA is in good agreement with its single crystal simulation X-ray diffraction pattern, which proves that the material has a long-range ordered crystal structure and good crystallinity.

After immersing Mg(L ₂ ) ₂ DMA in ferric ion solution for 12 hours, its powder X-ray diffraction pattern can still be in good agreement with its single crystal simulated X-ray diffraction pattern, which proves that it has good stability. The integrity of this structure is maintained during the process of iron ions, and can be reused.

Example 3:

Using magnesium sulfate and 4',5'-bis(4-carboxyphenyl)-3',6'-dimethyl-[1,1':2',1"-terphenyl]-4,4"- Dicarboxylic acid, synthesize Mg-MOFs by solvothermal method, the specific synthetic route is as follows:

0.02 mmol of magnesium sulfate and 0.02 mmol of 4',5'-bis(4-carboxyphenyl)-3',6'-dimethyl-[1,1':2',1"-terphenyl] -4,4”-Dicarboxylic acid was dissolved in water, ethanol and N,N-diethylformamide (DEF), the volume ratio of water, ethanol and DEF was 1:1:3, and the resulting mixed solution was put into In a glass bottle, heat the reaction at 120°C for 72 hours, naturally cool to room temperature, centrifuge, wash, filter and dry to obtain MgL ₃ DEF with a yield of 60.3%

从C轴看，孔道尺寸约为

在370nm的激发下，所得到的发射光谱的峰值位于450nm左右，随着三价铁离子含量增加，其发射光谱强度降低，其发射光谱强度的比值与三价铁离子的加入量有很好的线性关系。According to single crystal X-ray diffraction analysis, MgL ₃ DEF has a long-range ordered crystal structure and a regular three-dimensional pore structure. Viewed from the A axis, the pore size is about

Viewed from the C axis, the channel size is approx.

Under the excitation of 370nm, the peak value of the obtained emission spectrum is located at about 450nm. As the content of ferric ions increases, the intensity of the emission spectrum decreases, and the ratio of the intensity of the emission spectrum to the amount of ferric ions added has a good relationship. linear relationship.

In order to investigate the selective response of the Mg-MOFs to iron ions, different interfering substances were added to the system and the fluorescence changes were detected. After adding other interferents: copper ions, zinc ions, potassium ions, lithium ions, barium ions, cadmium ions, nickel ions, sodium ions, chloride ions, calcium ions, lead ions and cobalt ions, then add 200 μL of the same concentration and 400 μL of iron ion solution, the change of the fluorescence intensity emitted at 450nm is not affected by other interfering substances, thereby realizing the specific recognition of iron ions.

The powder X-ray diffraction pattern of the newly synthesized MgL ₃ DEF is in good agreement with its single crystal simulation X-ray diffraction pattern, which proves that the material has a long-range ordered crystal structure and good crystallinity.

After immersing MgL ₃ DEF in ferric ion solution for 12 hours, its powder X-ray diffraction pattern can still be in good agreement with its single crystal simulated X-ray diffraction pattern, which proves that it has good stability. It still maintains the integrity of this structure and can be reused.

Example 4:

Using magnesium acetate and 4',5'-bis(4-carboxyphenyl)-3',6'-dihydroxy-[1,1':2',1"-terphenyl]-4,4"-bis Carboxylic acid, synthesize Mg-MOFs by solvothermal method, the specific synthetic route is as follows:

0.04mmol of magnesium sulfate and 0.02mmol of 4',5'-bis(4-carboxyphenyl)-3',6'-dihydroxy-[1,1':2',1"-terphenyl]- 4,4"-dicarboxylic acid was dissolved in water, ethanol and N,N-dimethylacetamide (DMF), the volume ratio of water, ethanol and DMF was 1:1:5, and the resulting mixed solution was put into a glass bottle, heated at 115°C for 72 hours, naturally cooled to room temperature, centrifuged, washed, filtered and dried to obtain Mg(L ₄ ) ₃ DEF with a yield of 63.2%

从C轴看，孔道尺寸约为

在370nm的激发下，所得到的发射光谱的峰值位于450nm左右，随着三价铁离子含量增加，其发射光谱强度降低，其发射光谱强度的比值与三价铁离子的加入量有很好的线性关系。According to single crystal X-ray diffraction analysis, Mg(L ₄ ) ₃ DMF has a long-range ordered crystal structure and a regular three-dimensional pore structure. Viewed from the A axis, the pore size is about

Viewed from the C axis, the channel size is approx.

Under the excitation of 370nm, the peak value of the obtained emission spectrum is located at about 450nm. As the content of ferric ions increases, the intensity of the emission spectrum decreases, and the ratio of the intensity of the emission spectrum to the amount of ferric ions added has a good relationship. linear relationship.

In order to investigate the selective response of the Mg-MOFs to iron ions, different interfering substances were added to the system and the fluorescence changes were detected. After adding other interferents: copper ions, zinc ions, potassium ions, lithium ions, barium ions, cadmium ions, nickel ions, sodium ions, chloride ions, calcium ions, lead ions and cobalt ions, then add 200 μL of the same concentration and 400 μL of iron ion solution, the change of the fluorescence intensity emitted at 450nm is not affected by other interfering substances, thereby realizing the specific recognition of iron ions.

The powder X-ray diffraction pattern of the newly synthesized Mg(L ₄ ) ₃ DMF is in good agreement with its single crystal simulation X-ray diffraction pattern, which proves that the material has a long-range ordered crystal structure and good crystallinity.

After immersing Mg(L ₄ ) ₃ DMF in ferric ion solution for 12 hours, its powder X-ray diffraction pattern can still be in good agreement with its single crystal simulated X-ray diffraction pattern, which proves that it has good stability. The integrity of this structure is maintained during the process of iron ions, and can be reused.

Claims (8)

1. A kind of Mg-MOFs, it is characterized in that: described Mg-MOFs has long-range ordered crystal structure and regular channel, and its chemical formula is [Mg(L)xG], and wherein L is N, N, N' ,N'-Tetrakis(4-carboxyphenyl)-1,4-phenylenediamine, the structural formula is as follows:

x=1-4; G represents the solvent molecule coordinated with the magnesium ion or in the crystal channel, which is N,N-dimethylformamide, N,N-dimethylacetamide or N,N-diethyl formamide; the lower detection limit of the Mg-MOFs for iron ions reaches 6.75 μM. 2. the method for preparing the Mg-MOFs described in claim 1, is characterized in that, comprises the following steps: Dissolve metal magnesium salt and tetragonal symmetrical ligands containing tetracarboxylic acid groups in a mixed solvent of water, ethanol and organic solvent to obtain a mixed solution, put the mixed solution in a container, and heat it at 100°C-120°C for 24 -72 hours, naturally cooled to room temperature, centrifuged, washed, filtered and dried to obtain Mg-MOFs; the quadrilateral symmetric ligands containing tetracarboxylic acid groups are N, N, N', N'-tetra(4 -carboxyphenyl)-1,4-phenylenediamine. 3. The preparation method of Mg-MOFs according to claim 2, characterized in that the metal magnesium salt is one or more of magnesium nitrate, magnesium sulfate, magnesium acetate, and magnesium chloride. 4. the preparation method of Mg-MOFs according to claim 2 is characterized in that, described organic solvent is N, N-dimethylformamide, N, N-dimethylacetamide or N, N- Any one of diethylformamide. 5. The preparation method of Mg-MOFs according to claim 2, characterized in that, in the mixed solvent, the volume ratio of water, ethanol, and organic solvent is 1:1:2-5. 6. The preparation method of Mg-MOFs according to claim 2, characterized in that the molar ratio of the metal magnesium ions in the metal magnesium salt to the tetragonal symmetrical ligand is 1-4:1. 7. The application of Mg-MOFs according to claim 1 in the detection of iron ions, characterized in that it is used as a fluorescent probe for detecting ferric ions contained in the system. 8. The application of Mg-MOFs in the detection of iron ions according to claim 7, characterized in that the specific method for detecting ferric ions is as follows: In the solution containing Mg-MOFs, the solution to be detected is added dropwise in situ , for fluorescence detection.

Images