CN105503912B - A kind of new Zn (II) metal organic frameworks and its synthetic method and application - Google Patents

Abstract

The invention relates to a novel Zn(II) metal-organic framework and its synthesis method and application. The technical scheme adopted is: metal zinc salt, 4'-(1H-tetrazolium-5)-biphenyl-3,5-dicarboxylic acid, N,N-dimethylformamide are added in the container, at normal temperature and stir; seal the container and place it in an oven at a temperature of 348K for 1 day; slowly cool to room temperature to obtain colorless blocky crystals; wash, filter and dry to obtain the target product. A metal-organic framework (MOFs) constructed by Zn(II) and 4'-(1H-tetrazolium-5)-biphenyl-3,5-dicarboxylic acid prepared by the present invention shows strong fluorescence performance, and has a specific recognition function for Mg ²⁺ .

Description

A novel Zn(II) metal-organic framework and its synthesis method and application

technical field

The present invention relates to the synthesis and application of novel Zn(II) metal-organic frameworks, in particular, to a compound composed of Zn(II) and 4'-(1H-tetrazolium-5)-biphenyl-3,5- Metal-organic frameworks (MOFs) constructed with dicarboxylic acids exhibit strong fluorescence properties and have a specific recognition function for Mg ²⁺ .

Background technique

Metal-organic frameworks (MOFs) coordination polymers are a novel class of crystalline three-position materials, which have attracted extensive attention in the fields of catalysis, gas adsorption, molecular recognition, optics, etc. Multifunctional metal-organic frameworks with properties such as luminescence, magnetism, and high porosity have received special attention as chemical sensors. In recent years, with the continuous advancement of science and technology, fluorescent chemical sensors have attracted much attention because of their high sensitivity. Fluorescent chemical sensors have a wide range of applications in the detection of biologically active substances, the detection of ions, molecules and the detection of explosives. Most metal-organic frameworks are built from transition metal ion clusters, and these systems are currently receiving increasing attention not only because of their fascinating structures but also because of their potential applications in different scientific fields. The unique structure of coordination polymers is obtained by adjusting the coordination of metals and ligands through different building blocks and reaction conditions. Therefore, the construction of metal-organic frameworks with special structures and functions by designing and selecting organic ligands and metal units is a subject of continuous research and development.

Contents of the invention

The purpose of the present invention is to utilize zinc as metal node, utilize 4'-(1H-tetrazolium-5)-biphenyl-3,5-dicarboxylic acid as organic ligand, under certain temperature, utilize solvothermal Methods A 3D coordination polymer was synthesized.

The technical scheme adopted in the present invention is: novel Zn(II) metal-organic framework, the compound is constructed by Zn(II) and 4'-(1H-tetrazolium-5)-biphenyl-3,5-dicarboxylic acid, The crystal structure of the compound belongs to the tetragonal crystal system, and there are two different Zn atom coordination modes in the compound, among which, the first Zn atom coordination mode is the tetracoordination mode: two oxygen atoms come from 4'–(1H‐tetra Azole‐5)‐biphenyl‐3,5‐dicarboxylic acid ligand, one N from 4'–(1H‐tetrazolium‐5)‐biphenyl‐3,5‐dicarboxylic acid ligand, one oxygen The atoms come from the coordination ^OH‐ ; the second Zn atom coordination mode is the hexacoordination mode: three nitrogen atoms come from the 4'–(1H‐tetrazolium‐5)‐biphenyl‐3,5‐dicarboxylic acid coordination body, two oxygen atoms come from the 4'–(1H‐tetrazolium‐5)‐biphenyl‐3,5‐dicarboxylic acid ligand, and one oxygen atom comes from the coordinated ^OH‐ .

The synthetic method of above-mentioned novel Zn (II) metal-organic framework comprises the following synthetic steps:

1) Add metal zinc salt, 4'-(1H-tetrazolium-5)-biphenyl-3,5-dicarboxylic acid, N,N-dimethylformamide into the container, and stir at room temperature; Preferably, the metal zinc salt is Zn(NO ₃ ) ₂ .

2) Seal the container and put it in an oven at 343-353 for 22-28 hours;

3) Slowly cooling to room temperature to obtain colorless blocky crystals; preferably, the rate of slow cooling to room temperature is 15-20°C·h ^-1 .

4) washing, filtering and drying to obtain the target product.

The beneficial effects of the present invention are: the metal-organic framework (MOFs) constructed by Zn(II) and 4'-(1H-tetrazolium-5)-biphenyl-3,5-dicarboxylic acid prepared by the present invention shows Strong fluorescent performance, and has a specific recognition function for Mg ²⁺ . The preparation method of the metal-organic framework (MO Fs) constructed by Zn(II) and 4'-(1H-tetrazolium-5)-biphenyl-3,5-dicarboxylic acid of the present invention is simple, and the compound has excellent properties in the field of fluorescence Great application value.

Description of drawings

Figure 1 is a schematic diagram of the synthesis of the novel Zn(II) metal-organic frameworks (MOFs) of the present invention.

Fig. 2 is an XRD pattern of the novel Zn(II) metal-organic framework (MOFs) of the present invention.

Fig. 3 is a schematic diagram of the coordination mode of the novel Zn(II) metal-organic framework (MOFs) of the present invention.

Fig. 4 is a schematic diagram of the three-dimensional structure of the novel Zn(II) metal-organic framework (MOFs) of the present invention.

Fig. 5 is a liquid fluorescence emission spectrum diagram of the novel Zn(II) metal-organic framework (MOFs) of the present invention.

Fig. 6 is a diagram of the fluorescence intensity of the methanol suspension of the novel Zn(II) metal-organic framework (MOFs) of the present invention under different metals.

detailed description

Example 1 Zn(Ⅱ) metal organic framework (MOFs)

Add 0.25mmol of Zn(NO ₃ ) ₂ , 0.05mmol of 4'–(1H-tetrazolium-5)-biphenyl-3,5-dicarboxylic acid, 1ml of N,N-dimethylformamide into 5ml of in a glass jar. Seal the glass bottle and put it in the oven. Heat to bring the temperature of the oven to 348K, and keep the temperature under this condition for 24 hours. Cool slowly to room temperature at a cooling rate of 15-20°C·h ^-1 to obtain colorless blocky crystals; wash, filter and dry to obtain the target product Zn(II) metal-organic frameworks (MOFs), with a yield of 65% .

The XRD of the Zn(II) metal-organic framework synthesized by the present invention is shown in Figure 2, in which i is the simulated crystal powder diffraction pattern, and ii is the measured powder diffraction pattern of the synthesized crystal.

The structure of the Zn(II) metal-organic framework synthesized by the present invention is shown in Figure 3 and Figure 4, and the crystal structure belongs to the tetragonal crystal system. The molecular formula is: {[Zn ₂ (L) _3.5 (OH) ₂ ](DMF) ₃ (H ₂ O) ₂ } _n (L is 4'–(1H-tetrazolium-5)-biphenyl-3,5 -dicarboxylic acid ligand). There are two different coordination modes of Zn atoms in this compound. Zn1 is a four-coordination mode, two oxygen atoms come from 4'–(1H-tetrazolium-5)-biphenyl-3,5-dicarboxylic acid ligand, and one N comes from 4’–(1H-tetrazolium -5)-biphenyl-3,5-dicarboxylic acid ligand, one oxygen atom comes from the coordination OH ^- ; Zn2 is a six-coordination pattern, three nitrogen atoms come from 4'–(1H-tetrazolium-5) -Biphenyl-3,5-dicarboxylic acid ligand, two oxygen atoms from 4'–(1H-tetrazolium-5)-biphenyl-3,5-dicarboxylic acid ligand, one oxygen atom from ligand bit ^OH- .

Example 2 Luminescence of Zn(II) metal-organic frameworks (MOFs)

Method: The Zn(II) metal-organic frameworks (MOFs) prepared in Example 1 were used to conduct luminescence performance experiments.

1) Dissolve Zn(II) metal-organic framework (MOFs) crystals in methanol solvent to obtain a mixed solution with Zn(II) metal-organic framework (MOFs) concentration of 1×10 ^-4 M, and the excitation wavelength is 305nm , the fluorescence emission of the crystal was measured, and the emission peak was 560nm.

2) Dissolving crystals of Zn(II) metal-organic frameworks (MOFs) in methanol solvent to obtain a mixed solution of Zn(II) metal-organic frameworks (MOFs) with a concentration of 1×10 ^-4 M.

Take 5ml of the mixed solution and add 25ul of Ag ⁺ , Zn ²⁺ , Al ³⁺ , Bi ³⁺ , Cd ²⁺ , Ce ³⁺ , Co ²⁺ , Cr ³⁺ , ^Cu at a concentration of 1×10 ^-4 M. ²⁺ , Fe ³⁺ , Hg ²⁺ , In ³⁺ , Mg ²⁺ , Na ⁺ , Ni ²⁺ , Pb ²⁺ in methanol solution, and make a blank at the same time. Using light with a wavelength of 305nm as the excitation light, the fluorescence intensity of Zn(II) metal-organic framework (MOFs) crystals in the mixed solution was detected by a fluorescence photometer.

The results are shown in FIG. 6 . It can be seen from FIG. 6 that the emission spectrum of Zn(II) metal organic framework (MOFs) as the characteristic emission wavelength appears in the spectrum. It shows that the metal-organic framework (MOFs) constructed by Zn(II) and 4'-(1H-tetrazolium-5)-biphenyl-3,5-dicarboxylic acid of the present invention has strong fluorescence performance at room temperature. It can be seen from Figure 6 that the crystals of metal-organic frameworks (MOFs) constructed by Zn(Ⅱ) and 4'-(1H-tetrazolium-5)-biphenyl-3,5-dicarboxylic acid are in Mg ²⁺ methanol solvent The most fluorescent. This shows that a metal-organic framework (MOFs) crystal constructed by Zn(II) and 4'-(1H-tetrazolium-5)-biphenyl-3,5-dicarboxylic acid of the present invention can be used as a fluorescent detector. The needle detects Mg ²⁺ .

Claims (7)

1. a kind of synthetic method of Zn (II) metal organic framework, it is characterised in that including following synthesis step：

1) by metal zinc salt, 4'- (1H- tetrazoles -5)-biphenyl -3,5- dicarboxylic acids, DMF is added in container, In under normal temperature, stir；

2) it is put into after container is sealed in baking oven, under 343-353K, keeps 22-28h；

3) it is slowly cooled to room temperature, obtains colourless bulk crystals；

4) wash, filter and dry, obtain target product；

Described Zn (II) metal organic framework：Molecular formula is：{[Zn₂(L)_3.5(OH)₂](DMF)₃(H₂O)₂}_n, wherein, L is 4'- (1H- tetrazoles -5)-biphenyl -3,5- dicarboxylates；The compound by Zn (II) and 4'- (1H- tetrazoles -5)-biphenyl - 3,5- dicarboxylic acids are constructed, and the compound crystal structure, which belongs to, two kinds of different Zn Atomic coordinate moulds in tetragonal crystal system, compound Formula, wherein, the first Zn Atomic coordinate pattern is four-coordination pattern：Two oxygen atoms from 4'- (1H- tetrazoles -5)-biphenyl - 3,5- dicarboxylates a, N comes from 4'- (1H- tetrazoles -5)-biphenyl -3,5- dicarboxylates, and an oxygen atom carrys out autogamy Position OH^-；Second of Zn Atomic coordinate pattern is hexa-coordinate pattern：Three nitrogen-atoms come from 4'- (1H- tetrazoles -5)-biphenyl -3, 5- dicarboxylates, two oxygen atoms carry out 4'- (1H- tetrazoles -5)-biphenyl -3,5- dicarboxylates, and an oxygen atom comes from It is coordinated OH^-。

2. the synthetic method of Zn (II) metal organic framework according to claim 1, it is characterised in that described metallic zinc Salt is Zn (NO₃)₂。

3. the synthetic method of Zn (II) metal organic framework according to claim 2, it is characterised in that：By 0.25mmol's Zn(NO₃)₂, 0.05mmol 4'- (1H- tetrazoles -5)-biphenyl -3,5- dicarboxylic acids, 1mlN, dinethylformamide, which is added, to be held In device.

4. the synthetic method of Zn (II) metal organic framework according to claim 1,2 or 3, it is characterised in that：Described The rate of temperature fall being slowly cooled to room temperature is 15-20 DEG C of h^-1。

5. according to Zn (II) metal organic frameworks the answering in fluorescence probe field of the synthetic method synthesis described in claim 1 With.

6. application according to claim 5, it is characterised in that method is as follows：By the new Zn (II) described in claim 1 Metal organic framework is configured to methanol suspension, and the methanol solution of metal ion is added dropwise, using wavelength be 305nm light as exciting light, Carry out fluoroscopic examination.

7. application according to claim 6, it is characterised in that：Described metal ion is Mg²⁺。