CN107698777A - A kind of porous polymer of cupric coordination, preparation method and application - Google Patents

Abstract

A copper-coordinated porous polymer, its preparation method and application. The present invention belongs to coordination polymer materials. Its chemical formula is [Cu ₃ (Tra) ₂ O ₂ •7H ₂ O] _n , and its molecular structure is C ₂₄ H ₃₂ Cu ₁₂ N ₃₆ O ₃₈ , where Tra is the deprotonated anion of 1,2,4-triazole , Cu is divalent copper ion, and the form of the material is solid crystal. The crystallization of the polymer is a trigonal crystal system, the space group R-3C, and the porosity of the three-dimensional framework structure is 51.9%. The preparation is: react 1,2,4-triazole-3-carboxylic acid and 5-amino-1,2,4-triazole- ₃ -carboxylic acid with CuCl under hydrothermal conditions to obtain dark green of crystals. The invention can be used as a photocatalyst to convert greenhouse gas carbon dioxide into carbon monoxide. The preparation process of the invention is easy to implement, the product purity and yield are high, and the invention has a good application prospect in the aspect of photocatalytic conversion of carbon dioxide.

Description

A copper-coordinated porous polymer, preparation method and application

technical field

The invention belongs to coordination polymer materials, especially porous coordination polymers and their preparation methods and applications.

Background technique

The earth is rich in fossil fuel resources, such as oil and coal. Since the combustion of fossil fuels releases a large amount of CO ₂ , it causes many serious environmental problems such as global warming. The idea of reducing _CO2 to chemical fuels is an effective way to solve the _CO2 problem. To achieve this goal, visible light can be used to catalytically reduce CO ₂ , thereby reducing greenhouse gas emissions and obtaining new fuels such as CO and methane. Searching for efficient photocatalysts is the key to solving CO ₂ reduction (CN 103721738A; CN 105749914A; CN 103464172B). Traditional carbon dioxide photocatalysts generally use cheap and abundant metal complexes such as manganese and iron (ACS Catal., 2015, 5, 2521–2528; J.Am.Chem.Soc., 2016, 138, 4354–4357), However, these complexes are compounds of small molecular structure, generally do not have a regular pore structure, and do not have a strong absorption of carbon dioxide. 1,2,4-Triazole and its derivatives are a class of excellent ligands with multiple coordination sites, which can form metal complexes with different structures and functions with transition metals, and have various coordination modes , which provides the possibility to synthesize porous copper coordination compounds with novel structures; and copper is a cheap metal, and the complexes formed with copper ions have good application prospects in the fields of electricity, catalysis, optics and so on (CN 104646058A; CN 102532170B). However, there are few reports on the application of triazole copper coordination polymers in the photocatalytic reduction of carbon dioxide.

Contents of the invention

The object of the present invention is to use 1,2,4-triazole-3-carboxylic acid and 5-amino-1,2,4-triazole-3-carboxylic acid as precursor ligands, and copper ion as metal center , to prepare a novel porous copper coordination polymer, and use the coordination polymer as a catalyst for photocatalytic carbon dioxide reduction.

In order to solve the above technical problems, the technical solution of the present invention includes:

(1) A copper-coordinated porous polymer

The chemical formula of the polymer is [Cu ₃ (Tra) ₂ O ₂ ·7H ₂ O] _n , where Tra represents the anion after deprotonation of the organic ligand 1,2,4-triazole, and Cu is copper ion. The polymer has a one-dimensional channel formed by Tra ligands bridging copper ions through oxygen atoms, and further has a three-dimensional porous skeleton network; the polymer crystal belongs to the trigonal crystal system, the space group is R-3C, and the unit cell parameters are: b=17.569(5), α=β=90°, γ=120°,

Further: the porosity of the three-dimensional framework structure of the porous polymer crystal is 51.9%; the decomposition temperature of the framework structure is 305°C.

(2) The method for preparing the above-mentioned porous coordination polymer material

Include the following steps:

(1) Mix 1,2,4-triazole-3-carboxylic acid and 5-amino-1,2,4-triazole- ₃ -carboxylic acid with CuCl in distilled water;

(2) After sealing the mixture obtained above, conduct a hydrothermal reaction at 150-180°C for 24-48 hours, and then slowly cool to room temperature at a rate of 5°C per hour to obtain dark green needle-shaped crystals;

(3) washing the above-mentioned dark green needle-like crystals with ethanol, and drying naturally to obtain a single crystal sample of the porous coordination polymer;

(4) Vacuum drying at 110°C to obtain the porous coordination polymer.

Further: the molar ratio of 1,2,4-triazole-3-carboxylic acid, 5-amino-1,2,4-triazole- ₃ -carboxylic acid and CuCl in the step (1) is 1 :1:1～1:1:2.

(3) Application of porous copper coordination polymer of the present invention

A method of using one of the copper-coordinated porous polymers as a photocatalyst.

Further: using the coordination polymer as a photocatalyst for reducing carbon dioxide to carbon monoxide.

Compared with traditional catalysts, the beneficial effects of the present invention are:

First of all, the multi-coordination points of 1,2,4-triazole-3-carboxylic acid and 5-amino-1,2,4-triazole-3-carboxylic acid are used to achieve the formation of copper ions The purpose of coordination compounds. 1,2,4-triazole-3-carboxylic acid and 5-amino-1,2,4-triazole-3-carboxylic acid undergo the removal of amino and carboxyl groups in the hydrothermal reaction, and form with copper ions Oxygen bridges are formed to form a three-dimensional network skeleton, and the higher porosity can absorb carbon dioxide.

The Cu complex in the present invention is a giant molecule with a framework structure, has a regular pore structure and good porosity, has obvious absorption of carbon dioxide, and can also catalyze the reduction of _CO2 gas to CO.

Secondly, copper coordination compounds are used to take advantage of the cheap and easy-to-obtain feature of metallic copper. Such compounds have the great advantage of low cost as catalysts.

Third, the photocatalyst material of the present invention is simple to prepare, has good reproducibility, high yield and high product purity.

Fourth, the photocatalyst of the present invention has a stable structure and high thermal stability.

Description of drawings

Figure 1 is the infrared spectrogram of the porous coordination polymer. In the figure, the infrared spectrogram of the porous coordination polymer shows strong absorption at 1513 cm ^-1 after the copper ions participate in the coordination with the N atom in the triazole. It shows that the copper ion and the ligand form a coordination compound.

Fig. 2 is a powder diffraction comparison diagram of the single crystal sample of the porous coordination polymer and the single crystal simulation. The figure shows that the diffraction of the single crystal sample of the prepared porous coordination polymer is basically consistent with that of the single crystal simulation, indicating that the prepared porous coordination polymer sample has a relatively high purity.

Fig. 3 is a coordination structure diagram of the porous coordination polymer. In the figure, the copper ions are coordinated with the 1 and 4 nitrogen atoms in the triazole, and the copper ions are linked with the triazole coordination units through oxygen bridges to form a three-dimensional skeleton structure. Fig. 4 is a three-dimensional structure packing diagram of the porous coordination polymer crystal. It can be found that after one-dimensional channels are stacked in three-dimensional space, a coordination polymer with a microporous structure is formed.

Figure 5 is the fluorescence emission spectrum of the porous coordination polymer. The figure shows that under ultraviolet excitation, the coordination polymer has the strongest emission peak at 467nm, which is the fluorescence emission that the triazole ligand absorbs energy and then returns to the ground state.

Figure 6 is a gas chromatographic detection diagram of the catalytic reduction of _CO2 using the porous coordination polymer as a photocatalyst, which shows that _CO2 can be reduced to CO under the action of the porous coordination polymer. It shows that the porous coordination polymer has a good effect on the catalytic conversion of carbon dioxide. The photocatalytic cycle conversion number (TON) was 35.

Figure 7 is the adsorption curve of the porous coordination polymer for carbon dioxide gas at a temperature of 273K. It can be seen from the figure that the adsorption capacity of the porous coordination polymer for carbon dioxide gas can reach 15.6 cm ^{3 /} g.

The present invention will be further described below in conjunction with specific embodiments. Examples include but do not limit the scope of protection of the present invention.

detailed description

(1) Preparation of the porous coordination polymer material

Example 1:

11.31 mg (0.1 mmol) 1,2,4-triazole-3-carboxylic acid, 12.81 mg (0.1 mmol) 5-amino-1,2,4-triazole-3-carboxylic acid, 34.1 mg ( 0.2mmol) of CuCl ₂ ·2H ₂ O was added to 10mL of distilled water and mixed evenly; the resulting mixture was sealed and then hydrothermally reacted at 150°C for 48 hours, then cooled to room temperature at a rate of 5°C per hour to obtain Dark green massive transparent crystals were washed with ethanol and dried naturally to obtain a single crystal sample of the porous coordination polymer. The porous coordination polymer can be prepared by vacuum drying at 110°C.

Example 2:

11.31 mg (0.1 mmol) 1,2,4-triazole-3-carboxylic acid, 12.81 mg (0.1 mmol) 5-amino-1,2,4-triazole-3-carboxylic acid, 34.1 mg ( 0.2mmol) of CuCl ₂ ·2H ₂ O was added to 10mL of distilled water and mixed uniformly; the resulting mixture was sealed and subjected to hydrothermal reaction at 160°C. After reacting for 36 hours, it was cooled to room temperature at a rate of 5°C per hour to obtain The dark green blocky transparent crystals are washed with ethanol and dried naturally to obtain a single crystal sample of the porous coordination polymer, which is then vacuum-dried at 110°C to obtain the porous coordination polymer.

Example 3:

11.31 mg (0.1 mmol) 1,2,4-triazole-3-carboxylic acid, 12.81 mg (0.1 mmol) 5-amino-1,2,4-triazole-3-carboxylic acid, 25.6 mg ( 0.15 mmol) of CuCl ₂ ·2H ₂ O was added to 10 mL of distilled water and mixed uniformly; the resulting mixture was sealed and subjected to hydrothermal reaction at 170°C. After 36 hours of reaction, it was cooled to room temperature at a rate of 5°C per hour to obtain The dark green blocky transparent crystals are washed with ethanol and dried naturally to obtain a single crystal sample of the porous coordination polymer, which is then vacuum-dried at 110°C to obtain the porous coordination polymer.

Example 4:

11.31 mg (0.1 mmol) 1,2,4-triazole-3-carboxylic acid, 12.81 mg (0.1 mmol) 5-amino-1,2,4-triazole-3-carboxylic acid, 25.6 mg ( 0.10 mmol) of CuCl ₂ ·2H ₂ O was added to 10 mL of distilled water and mixed uniformly; the resulting mixture was sealed and then subjected to hydrothermal reaction at 180°C. After 24 hours of reaction, it was cooled to room temperature at a rate of 5°C per hour to obtain The dark green blocky transparent crystals are washed with ethanol and dried naturally to obtain a single crystal sample of the porous coordination polymer, which is then vacuum-dried at 110°C to obtain the porous coordination polymer.

(2) Determination of Porous Coordination Polymer Structure

Table 1: Parameter table of porous coordination polymer crystals

Select a single crystal with a suitable size under a microscope, and at a temperature T=293(2)K, on a Rigaku R-AXISSPIDER diffractometer, use Mo-K rays monochromated by a graphite monochromator Diffraction data were collected in the ω-φ fashion. Absorption correction was performed by the ABSCOR program. The structure was parsed and refined using the SHELXTL program using the direct method. First use difference function method and least square method to determine all non-hydrogen atom coordinates, non-hydrogen atom coordinates and anisotropy parameters are corrected by full matrix least square method, and then use theoretical hydrogenation method to obtain the hydrogen atom position of the main skeleton, and then use The crystal structure was refined by the least squares method. Some parameters of crystallographic diffraction point data collection and structure refinement are shown in Table 1 above.

The infrared spectrum experiment of the present invention is completed using BRUKER TENSOR 27.

Fluorescence spectroscopy experiments were performed using a Hitachi F-4600 fluorescence spectrometer.

Powder diffraction data collection was done on a Rigaku D-MAX 2200VPC diffractometer.

Single crystal diffraction was performed on a Rigaku R-AXIS SPIDER diffractometer.

Gas chromatography detection was completed in SHIMADZU GC-2014C.

Claims (6)

1. A kind of 1. porous polymer of cupric coordination, it is characterised in that：The polymer chemistry formula is [Cu₃(Tra)₂O₂·7H₂O]_n, its In, Tra represents the anion after the triazole deprotonation of organic ligand 1,2,4-, and Cu is copper ion, and the polymer has Tra parts The one-dimensional channels formed by oxygen atom bridging copper ion, and further there is three-dimensional porous back bone network；The polymer is brilliant Body belongs to trigonal system, space group R-3C, and cell parameter is respectively：B=17.569 (5),α=β=90 °, γ=120 °,
2. 2. according to claim 1 and described porous polymer, it is characterised in that：The three-dimensional framework knot of the porous polymer crystal The porosity of structure is 51.9%；The decomposition temperature of frame structure is 305 DEG C.
3. 3. preparing a kind of method of porous polymer as claimed in claim 1 or 2, comprise the following steps：

   (1) by 1,2,4- triazole -3- carboxylic acids and 5- amino-1,2,4-triazol -3- carboxylic acids and CuCl₂Mixed in distilled water Uniformly；

   (2) hydro-thermal reaction will be carried out after the sealing of above-mentioned gained mixed liquor at 150~180 DEG C 24~48 hours, then with per hour 5 DEG C speed be slowly cooled to room temperature, obtain blackish green acicular crystal；

   (3) above-mentioned blackish green acicular crystal, naturally dry, the single crystal samples of the obtained Porous coordination polymer are washed with ethanol；

   (4) 110 DEG C of vacuum drying, you can the Porous coordination polymer is made.
4. 4. preparation method according to claim 3, it is characterised in that：1,2,4- triazole -3- the carboxylics of the step (1) Acid, 5- amino-1,2,4-triazol -3- carboxylic acids and CuCl₂Mol ratio be 1:1:1~1:1:2.
5. A kind of 5. method as photochemical catalyst of the porous polymer of application cupric coordination as claimed in claim 1 or 2.
6. 6. application process according to claim 5, it is characterised in that：Using the coordination polymer as carbon dioxide reduction into The photochemical catalyst of carbon monoxide.