A method for preparing and applying ammonia-sensitive complex materials based on crystal structure transformation

Abstract

This invention belongs to the field of coordination material technology, and relates to a method for preparing and applying an ammonia-sensitive coordination material based on crystal structure transformation. The ammonia-sensitive coordination material prepared by this invention has the chemical formula Co(C5H3N2O2)(H2O)2(C8H4O4). 0.5 This invention also provides a method for preparing the above-mentioned ammonia-sensitive complex material based on crystal structure transformation. The prepared ammonia-sensitive complex material has excellent thermal stability and reversible ammonia-responsive color change performance. It can be reused, and the preparation process is simple, environmentally friendly, low-cost, and suitable for scale-up production. It has broad application prospects in the fields of ammonia visual monitoring and environmental safety.

Description

Technical Field

[0001] This invention belongs to the field of coordination material technology, specifically relating to a method for preparing and applying an ammonia-sensitive coordination material based on crystal structure transformation. Background Technology

[0002] Ammonia is widely used in various industries, but it is a highly explosive and flammable harmful gas. Long-term exposure to ammonia can cause significant harm to the human body. Therefore, the development of a rapid, reliable, highly sensitive, and selective ammonia gas sensor is urgently needed. Traditional methods for detecting ammonia include optical, acoustic, and chromatographic methods; however, these methods are limited by large instrument size, low measurement accuracy, and complex operation, making them difficult to widely use. In recent years, research on functional coordination materials has received increasing attention in the field of new functional materials. Its research spans fields such as magnetism, optics, and electricity, and has shown great potential application value. Developing multifunctional coordination materials with ammonia-responsive color-changing properties could provide a simple, economical, and effective method for the visual detection of ammonia. Summary of the Invention

[0003] Based on the above background, this invention provides a method for preparing and applying an ammonia-sensitive complex material based on crystal structure transformation. The ammonia-sensitive complex material prepared by this invention exhibits excellent thermal stability and reversible ammonia-responsive color change performance. It can be reused, and the preparation process is simple, environmentally friendly, low-cost, and suitable for large-scale production.

[0004] Technical solution of the present invention:

[0005] An ammonia-sensitive complex material based on crystal structure transformation, with the chemical formula Co(C5H3N2O2)(H2O)2(C8H4O4). 0.5 In the formula, C5H3N2O2 is the 2-pyrazinic acid anion, and C8H4O4 is the terephthalic acid anion; this amino-sensitive complex material belongs to the orthorhombic crystal system, space group Pbca, and the cell parameters are: a = 11.9727 (4) Å, b = 11.1001 (3) Å, c = 15.6755 (4) Å, α = 90.00°, β = 90.00°, γ = 90.00°, V = 2083.26 (9) Å 3 The crystallographic data are shown in Table 1. The structural unit of the complex consists of one cobalt ion center, one 2-pyrazine carboxylic acid anion, 0.5 terephthalic acid anions and two coordinated water molecules. The six-coordinated cobalt ion forms a three-dimensional framework structure through the bridging effect of the 2-pyrazine carboxylic acid anion and the terephthalic acid anion.

[0006] Table 1 Crystallographic data of ammonia-sensitive complex materials

[0007] Mr 300.11 Crystal system Orthogonal Space group P bca a (Å) 11.9727 (4) b (Å) 11.1001 (3) c (Å) 15.6755 (4) α (°) 90 β (°) 90 γ (°) 90 <![CDATA[V (Å 3 )]]> 2083.26 (9) F(000) 1216.0 Z 8 <![CDATA[Dx (g cm –3 )]]> 1.914 <![CDATA[μ (mm –1 )]]> 1.672 θ range (°) 3.40- 29.12 Ref. meas. / indep. 5334 Obs. ref. 2414 <![CDATA[R int ]]> 0.0247 <![CDATA[R1 a ]]> 0.0343 <![CDATA[wR2(all data) b ]]> 0.0893 Goof 1.037 <![CDATA[Δρ(max, min) (e Å -3 )]]> 0.502, -0.512

[0008] a R1 = Σ||F o | – |F c || / Σ|F o | b wR2 = 1 / 2 .

[0009] The preparation method of ammonia-sensitive complex materials based on crystal structure transformation includes the following steps:

[0010] (1) Dissolve 23.8 parts of cobalt chloride hexahydrate in 1500 parts of deionized water to obtain a homogeneous cobalt chloride solution for later use;

[0011] (2) Dissolve 12.4 parts of 2-pyrazine carboxylic acid, 8.3 parts of terephthalic acid and 5.6 parts of KOH in 1500 parts of N,N-dimethylformamide to obtain a homogeneous solution for later use;

[0012] (3) Add the cobalt chloride solution obtained in step (1) to the solution prepared in step (2), mix them evenly, and then transfer them to a stainless steel reactor with a polytetrafluoroethylene liner. React at 80 °C for 5 days, then cool to room temperature, filter, wash and dry to obtain the ammonia-sensitive complex material based on crystal structure transformation (its color is orange-pink).

[0013] The beneficial effects of this invention are as follows:

[0014] The ammonia-sensitive complex material prepared by this invention based on crystal structure transformation has excellent thermal stability and reversible ammonia-responsive color change performance. It can be reused, and the preparation process is simple, environmentally friendly, and low-cost. It is also suitable for large-scale production and has broad application prospects in the fields of ammonia visualization monitoring, gas sensing, and environmental safety. Attached Figure Description

[0015] Figure 1 This is a structural unit diagram of the ammonia-sensitive complex material prepared in this invention;

[0016] Figure 2 This is a three-dimensional framework structure diagram of the ammonia-sensitive complex material prepared in this invention;

[0017] Figure 3 This is a unit cell diagram of the crystal structure of the ammonia-sensitive complex material prepared in this invention after ammonia response. Detailed Implementation

[0018] The present invention will be specifically described below through embodiments. It should be noted that these embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments based on the above description of the present invention. Unless otherwise specified, the parts of raw materials mentioned are all parts by mass.

[0019] Example:

[0020] An ammonia-sensitive complex material based on crystal structure transformation, with the chemical formula Co(C5H3N2O2)(H2O)2(C8H4O4). 0.5 In the formula, C5H3N2O2 is the 2-pyrazinic acid anion, and C8H4O4 is the terephthalic acid anion; this amino-sensitive complex material belongs to the orthorhombic crystal system, space group Pbca, and the cell parameters are: a = 11.9727 (4) Å, b = 11.1001 (3) Å, c = 15.6755 (4) Å, α = 90.00°, β = 90.00°, γ = 90.00°, V = 2083.26 (9) Å 3 The crystallographic data are shown in Table 1. The structural unit of this complex consists of one cobalt ion center, one 2-pyrazine carboxylic acid anion, 0.5 terephthalic acid anions and two coordinated water molecules. The six-coordinated cobalt ions form a three-dimensional framework structure through the bridging effect of the 2-pyrazine carboxylic acid anion and the terephthalic acid anion.

[0021] The preparation method of the above-mentioned ammonia-sensitive complex material based on crystal structure transformation includes the following steps:

[0022] (1) Dissolve 23.8 parts of cobalt chloride hexahydrate in 1500 parts of deionized water to obtain a homogeneous cobalt chloride solution for later use;

[0023] (2) Dissolve 12.4 parts of 2-pyrazine carboxylic acid, 8.3 parts of terephthalic acid and 5.6 parts of KOH in 1500 parts of N,N-dimethylformamide to obtain a homogeneous solution for later use;

[0024] (3) Add the cobalt chloride solution obtained in step (1) to the solution prepared in step (2), mix them evenly, and then transfer them to a stainless steel reactor with a polytetrafluoroethylene liner. React at 80 °C for 5 days, then cool to room temperature, filter, wash and dry to obtain the ammonia-sensitive complex material based on crystal structure transformation (its color is orange-pink).

[0025] Performance testing and applications:

[0026] The ammonia-sensitive complex material product synthesized in the embodiments of the present invention is orange-pink in color. After being exposed to an ammonia environment for 1 minute, its color changes to brownish-red, indicating that the ammonia-sensitive complex material product has excellent ammonia-responsive color-changing performance. In addition, when the above-mentioned complex material that has turned brownish-red is placed in an environment with a relative humidity of 90%, its color can be restored to orange-pink. After being exposed to an ammonia environment for 1 minute, its color changes back to brownish-red, indicating that the ammonia-sensitive complex material synthesized in the embodiments of the present invention has reversible ammonia-responsive color-changing performance and can be reused.

[0027] The ammonia-sensitive complex synthesized in the embodiments of this invention has the chemical formula Co(C5H3N2O2)(H2O)2(C8H4O4). 0.5 The color was orange-pink. After placing it in an ammonia environment for 1 minute, a complex with a transformed crystal structure (its color was brownish-red) was obtained. X-ray single-crystal diffraction analysis was performed on the complex obtained above, and its chemical formula was Co(C5H3N2O2)(NH3)(H2O)(C8H4O4). 0.5 The ammonia-sensitive complex material belongs to the orthorhombic crystal system with space group Pbca and cell parameters: a = 11.9754 (2) Å, b = 11.1018 (2) Å, c = 15.6684 (2) Å, α = 90.00°, β = 90.00°, γ = 90.00°, V = 2083.09 (6) Å. 3 The crystallographic data are shown in Table 2. The structural unit of this complex consists of one cobalt ion center, one 2-pyrazine carboxylic acid anion, 0.5 terephthalic acid anion, one coordinated ammonia molecule, and one coordinated water molecule. The six-coordinated cobalt ion forms a three-dimensional framework structure through the bridging effect of the 2-pyrazine carboxylic acid anion and the terephthalic acid anion. The above results indicate that when the ammonia-sensitive complex synthesized by the method in the embodiments of the present invention is placed in an ammonia environment, one coordinated water molecule on the central cobalt ion is transformed into one coordinated ammonia molecule, which changes the coordination environment of the central cobalt ion. As a result, the ammonia-sensitive complex material changes from the initial orange-pink color to brownish-red after responding to ammonia.

[0028] Table 2 Crystallographic data of ammonia-sensitive complex materials after ammonia response

[0029] Mr 299.13 Crystal system Orthogonal Space group P bca a (Å) 11.9754 (2) b (Å) 11.1018 (2) c (Å) 15.6684 (2) α (°) 90 β (°) 90 γ (°) 90 <![CDATA[V (Å 3 )]]> 2083.09 (6) F(000) 1216.0 Z 8 <![CDATA[Dx (g cm –3 )]]> 1.908 <![CDATA[μ (mm –1 )]]> 1.667 θ range (°) 3.402- 25.099 Ref. meas. / indep. 5446 Obs. ref. 2368 <![CDATA[R int ]]> 0.0245 <![CDATA[R1 a ]]> 0.0373 <![CDATA[wR2(all data) b ]]> 0.1052 Goof 1.062 <![CDATA[Δρ(max, min) (e Å -3 )]]> 0.713, -0.839

[0030] a R1 = Σ||F o | – |F c || / Σ|F o | b wR2 =1 / 2 .

[0031] The thermal stability of the product was evaluated using a thermogravimetric analyzer (SDT-Q600, TA Instruments, USA). The ammonia-sensitive complex material product synthesized by the method in the embodiments of this invention has a stable skeleton structure up to 345℃, indicating that the ammonia-sensitive complex material product has excellent thermal stability.

[0032] In summary, the ammonia-sensitive complex material product prepared by this invention based on crystal structure transformation has excellent thermal stability and reversible ammonia-responsive color change performance. It can be reused, and the preparation process is simple, environmentally friendly, and low-cost. It is also suitable for large-scale production and has broad application prospects in the fields of ammonia visualization monitoring and environmental safety.

[0033] The content of this invention is not limited to the embodiments listed. Any equivalent modifications made by those skilled in the art to the technical solutions of this invention by reading this specification are covered by the claims of this invention.

Claims

1. A method for preparing an ammonia-sensitive complex material based on crystal structure transformation, characterized in that... The steps include: (1) Dissolving 23.8 parts of cobalt chloride hexahydrate in 1500 parts of deionized water to obtain a uniform cobalt chloride solution for later use; (2) Dissolving 12.4 parts of 2-pyrazine carboxylic acid, 8.3 parts of terephthalic acid and 5.6 parts of KOH in 1500 parts of N,N-dimethylformamide to obtain a uniform solution for later use; (3) Adding the cobalt chloride solution obtained in step (1) to the solution prepared in step (2), mixing them evenly, and then transferring them to a stainless steel reactor with a polytetrafluoroethylene liner, reacting at 80 °C for 5 days, then cooling to room temperature, filtering, washing and drying to obtain the ammonia-sensitive complex material based on crystal structure transformation; The chemical formula of the ammonia-sensitive complex material is Co(C5H3N2O2)(H2O)2(C8H4O4). 0.5 In the formula, C5H3N2O2 is the 2-pyrazinic acid anion, and C8H4O4 is the terephthalic acid anion; this amino-sensitive complex material belongs to the orthorhombic crystal system, space group Pbca, and the cell parameters are: a = 11.9727 (4) Å, b = 11.1001 (3) Å, c = 15.6755 (4) Å, α = 90.00°, β = 90.00°, γ = 90.00°, V = 2083.26 (9) Å 3 The structural unit of this complex consists of one cobalt ion center, one 2-pyrazine carboxylic acid anion, 0.5 terephthalic acid anions and two coordinated water molecules. The six-coordinated cobalt ions form a three-dimensional framework structure through the bridging effect of the 2-pyrazine carboxylic acid anion and the terephthalic acid anion.

2. The application of the ammonia-sensitive complex material based on crystal structure transformation obtained by the preparation method according to claim 1 in ammonia detection.

Images