Application of a viologen coordination compound crystal as a photochromic material

Abstract

The invention discloses an application of a viologen coordination compound crystal as a photochromic material, wherein the structural formula of the viologen coordination compound crystal is shown in formula (I): wherein BTC is pyromellitic acid. The invention uses a viologen molecule (Bcnbpy·2Cl) as a guest and an oxygen atom of a carboxyl group of pyromellitic acid as an electron donor, thereby providing a multifunctional color-changing material that can respond to ultraviolet light and blue light and can be used as an ultraviolet and / or blue light protection material.

Description

Technical Field

[0001] The invention relates to the application of a novel viologen color-changing crystal material, and in particular to the application of a coordination compound synthesized based on electron transfer between a viologen ligand and an electron donor molecule in photochromic and ultraviolet and blue light protection materials. Background Art

[0002] In recent years, the storage of chemical information in molecules, detection at the molecular level, and conversion into analyzable and detectable signals have attracted increasing research interest. Chemical information analytical sensing materials can detect and identify analytical substances through color changes, fluorescence characteristics, photosensitivity, and conductivity. Based on the actual situation and the problems we are facing, cationic coordination polymer materials and two-dimensional and three-dimensional metal organic framework materials have come into our sight. These materials generally have pores of a certain size, which are formed by connecting metal centers and organic linkers, and have cationic sites. Due to the special and novel structural characteristics of these materials, as well as their excellent reversibility and recyclability in the detection process, they are synthesized and studied by more and more researchers. Cationic coordination polymers, as a material with excellent sensing and detection performance, can identify and detect analytes stored in compounds through fluorescence detection or color changes of materials. This ability is mainly based on the role played by the functional units provided by organic ligands. In recent years, based on some organic ligands with color-changing properties, such as piperazines, diarylethenes and viologen cations, the synthesized coordination polymers or metal organic frameworks have been increasingly used in light, electricity and thermochemistry. Organic ligands have a real impact on the properties of the complexes, especially as functional units or sites, which are decisive for the functionality and potential applications of the synthesized compounds. Therefore, the solubility, stability and functionality of organic ligands are the focus of researchers.

[0003] As an interesting organic ligand that plays a role in redox processes, viologen-type cationic organic ligands (V 2+ , 1,1-disubstituted-4,4-bipyridine) has reversible color change performance, electron-deficient characteristics and redox properties. Viologen cation V 2+The electrons provided by the electron donor form the viologen cation radicals, which are accompanied by visible color changes. Therefore, for viologen cation ligands, a more interesting characteristic is the color change process caused by the electron transfer process between the electron donor and the acceptor. Since the electron transfer process is the inducing factor of the color change of viologen compounds, the factors affecting the electron transfer have been deeply explored, such as the spatial stacking type of the compound structure, the distance between the electron donor and the acceptor and the direction between them, the force of the intermolecular or intramolecular hydrogen bonds, and the sensitivity of the viologen unit to photoelectricity, heat and acidity. Summary of the invention

[0004] The purpose of the present invention is to provide an application of a viologen coordination compound crystal as a photochromic material. The compound can respond to ultraviolet light and blue light and can be used as an ultraviolet and / or blue light protection material.

[0005] In order to achieve the above object, the present invention includes the following technical solutions:

[0006] A viologen coordination compound crystal is used as a photochromic material. The structural formula of the viologen coordination compound crystal is shown in formula (I):

[0007] Among them, BTC is pyromellitic acid.

[0008] The application as described above is characterized in that the crystallographic parameters of the crystal are as follows: molecular weight is 674.61, belongs to the triclinic system, space group is P-1, unit cell parameters are: α(°)=72.060(3), β(°)=77.983(3), γ(°)=81.530(3), Z=1.

[0009] The application as described above is characterized in that the photochromic response wavelength range is 200 to 500 nm.

[0010] The above application is characterized in that the viologen coordination compound crystal is used as an anti-ultraviolet and / or anti-blue light material.

[0011] On the other hand, the present invention provides an anti-ultraviolet and / or anti-blue light material, which is composed of a viologen coordination compound crystal as shown in formula (I) and an optical resin material.

[0012] The 1,1-bis(3-cyanophenyl)-4,4-bipyridyl dichloride (bcnbpy·2Cl) used in the present invention is preferably prepared by the following method:

[0013] The method comprises adding 4,4'-bipyridine and 3-chloromethylbenzoic acid in a molar ratio of 1:(2-3) to N,N-dimethylformamide, heating and reflux at a temperature of 110-130° C. for 6-10 minutes under the protection of N2 gas, then cooling to room temperature, filtering to obtain a yellow precipitate, washing it three times with a hot DMF solution, then washing it three times with ethanol, and vacuum drying it at 60-80° C. for 10-15 hours; and recrystallizing it with a methanol and deionized water solution in a volume ratio of 1:(1-2) to obtain a bcnbpy·2Cl viologen compound with high purity.

[0014] The beneficial effects of the present invention are:

[0015] (1) The multifunctional viologen coordination compound crystal of the present invention has the property of photochromism and can sense different light sources, such as ultraviolet light and blue light, at extremely low concentrations and has a fast color change speed.

[0016] (2) The multifunctional viologen coordination compound crystal of the present invention can absorb and reflect blue light and ultraviolet light, and can be used as an optical material for protecting against blue light and ultraviolet light. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a diagram of the asymmetric structural unit of the compound prepared in Example 1.

[0018] Figure 2 This is a stacking diagram of the compound prepared in Example 1.

[0019] Figure 3 This is the electron transfer diagram of the compound prepared in Example 1.

[0020] Figure 4 This is the PXRD pattern of the compound prepared in Example 1.

[0021] Figure 5 This is the UV solid diffuse reflectance image of the compound prepared in Example 1.

[0022] Figure 6 This is a photochromic photograph of the compound prepared in Example 1. DETAILED DESCRIPTION

[0023] In order to make the objectives, technical solutions and advantages of the present invention clearer, we will describe the technical solutions and tests of the present invention in more detail. Obviously, the described embodiments are only part of the present invention, not all embodiments.

[0024] Example 1 Viologen coordination compound crystal (I)

[0025] 1. Preparation of the viologen compound 1,1-bis(3-cyanobenzyl)-[4,4′-bipyridine]-1,1′-diium chloride (abbreviated as bcnbpy·2Cl)

[0026] 4,4'-bipyridine (1.56g, 10mmol) and 3-chloromethylbenzyl cyanide (3.79g, 25mmol) were added to a 50mL round-bottom flask containing 25mL N,N-dimethylformamide. Under the protection of nitrogen, the mixture was heated to reflux at 110°C for 4-8h, then cooled to 25°C and filtered to obtain a yellow-white precipitate. The precipitate was washed three times with hot DMF solution, then washed three times with ethanol, and vacuum dried at 75°C for 12h. The Bcnbpy·2Cl viologen compound with a high purity was obtained by recrystallization with a methanol and deionized water solution in a volume ratio of 1:1. The hydrogen spectrum and carbon spectrum NMR data are as follows: 1 H-NMR (600MHz, D2O): δ=5.96 (s, 4H), 7.61 (t, J=18Hz, 2H), 7.75 (d, J=6Hz, 2H), 7.82 (d, J=6Hz, 4H), 8.51 (d, J=6Hz, 4H), 9.11 (d, J=6Hz, 4H); 13 C-NMR (600MHz, D2O): δ=63.1, 112.5, 118.2, 127.4, 130.5, 132.9, 133.5, 134.0, 145.8, 190.5.

[0027] 2. Preparation of Viologen Coordination Compound Crystals [(BTC)(bcnbpy)2Cl]·2H2O

[0028] Dissolve pyromellitic acid (50.8 mg, 0.2 mmol) and bcnbpy·2Cl (45.9 mg, 0.1 mmol) in a mixed solution of 2 ml deionized water and 4 ml N, N-dimethylformamide, and dissolve by stirring. Place the dissolved solution in a 20 ml polytetrafluoroethylene liner and synthesize by a solvent thermal method. After being kept at 90° C. for 4 days, cool to room temperature, wash with deionized water, and then obtain orange-yellow block crystals, which are viologen coordination compound crystals, with a yield of 73%.

[0029] 3. Crystal detection

[0030] (1) X-ray single crystal diffraction

[0031] The product obtained in step 2 was analyzed on a Gemini R Ultra diffractometer using the Oxford diffraction method at 296 K and absorption correction using a multi-scan technique with a Mo-Kα ray from a graphite monochromator. Crystal data was collected for the radiation source. Its crystal structure was crystallographically resolved using SHELXTL-2014 and Olex2 programs. Anisotropic refinement was performed on the thermal parameters of all non-hydrogen atoms in the compound, and the positions of hydrogen atoms on the viologen ligands were fixed. The crystallographic parameters were measured as follows: molecular weight is 674.61, belongs to the triclinic system, space group is P-1, unit cell parameters: α(°)=72.060(3), β(°)=77.983(3), γ(°)=81.530(3), Z = 1. Its crystal structure data is shown in Table 1.

[0032] Table 1

[0033] Table 1 Crystal data and structure refinement for 1.

[0034]

[0035] Figure 1 is the asymmetric structural unit diagram of the compound, Figure 2 The electron transfer diagram of the compound can be determined as follows:

[0036] BTC is pyromellitic acid (C 10 H2O8) 4- .

[0037] (2) UV solid diffuse reflection

[0038] Figure 3 This is the UV solid diffuse reflectance diagram of the compound. The test results show that the compound responds quickly to both UV light and blue light, and generates responsive viologen free radicals through photoinduced electron transfer. The color change process is a process of electron transfer, and the structure of the compound has hardly changed.

[0039] (3) Powder X-ray diffraction

[0040] Figure 4The PXRD diagram of the compound proves the stability of the compound after discoloration under blue light and UV irradiation. It can be seen from the figure that the PXRD of the compound after light irradiation has almost no change, which shows that the color change response of the compound is caused by the generation of free radicals to change the color of the compound, rather than the result of photoisomerization and photodecomposition. This result supports the potential application prospects of this compound in optical materials.

[0041] (4) Light-controlled fluorescence images

[0042] Figure 5 This is the photo-controlled fluorescence diagram of the compound, which shows that no matter under the induction of ultraviolet light or blue light, the fluorescence intensity of the compound increases with the irradiation time, the color of the compound changes, and the fluorescence intensity decreases. Moreover, the compound can respond to light quickly, and the fluorescence change occurs within one second. This fast-response material is suitable for application as a photo-controlled fluorescent material.

[0043] Example 2 Viologen coordination compound crystal (II)

[0044] Dissolve pyromellitic acid (76.2 mg, 0.3 mmol) and bcnbpy·2Cl (45.9 mg, 0.1 mmol) prepared in Example 1 in a mixed solution of 4 ml deionized water and 4 ml N, N-dimethylformamide, and dissolve by stirring. Place the dissolved solution in a 20 ml polytetrafluoroethylene liner and synthesize by a solvent thermal method. After being kept at 100°C for 5 days, cool to room temperature, wash with deionized water, and then obtain orange-yellow block crystals, which are viologen coordination compound crystals, with a yield of 75%. Elemental analysis C36 H26 N4O10 (%): Theoretical value: C, 64.09; H, 3.85; N, 8.30%. Experimental value: C, 63.88; H, 3.88; N, 8.27%.

[0045] Example 3 Viologen coordination compound crystal (III)

[0046] The pyromellitic acid and bcnbpy·2C1 prepared in Example 1 were dissolved in a mixed solution of deionized water and N,N-dimethylformamide in a volume ratio of 1:1 in a molar ratio of 3:1, and dissolved by stirring. The dissolved solution was placed in a 20ml polytetrafluoroethylene liner and synthesized by a solvent thermal method. After being kept at a constant temperature of 100°C for 5 days, it was cooled to room temperature and washed with deionized water to obtain orange-yellow block crystals, which were viologen coordination compound crystals with a yield of 75%. Elemental analysis C36H26N4O10 (%): Theoretical value: C, 64.09; H, 3.85; N, 8.30%. Experimental value: C, 63.62; H, 3.90; N, 8.24%.

[0047] Experimental Example 1 Photochromic Experiment

[0048] The viologen compound prepared in Example 1 was irradiated with a 300W xenon lamp as the light source, and filters of the ultraviolet band 200-400nm and the blue light band 400-480nm were installed respectively for irradiation, the wavelengths of ultraviolet light and blue light respectively covered, and the radiation intensity was 100Lux.

[0049] Photos of the compound before and after color change Figure 6 As shown, the original crystal is orange-yellow. When 200-400nm ultraviolet light is irradiated to the crystal, it turns to medium gray after 5 seconds, and the color recovers 120 minutes after the light source is removed. When 400-480nm blue light is irradiated to the crystal, it turns to camel after 5 seconds, and the color recovers 90 minutes after the light source is removed. After the color returns to the original color, it will change color again when irradiated with the corresponding light source again, which shows that the color change of the compound material is reversible.

Claims

1. Application of a viologen coordination compound crystal as a photochromic material and an ultraviolet and / or blue light protection material, characterized in that: The structural formula of the viologen coordination compound crystal is shown in formula (I): Among them, BTC is pyromellitic acid; The crystallographic parameters of the crystal are as follows: molecular weight is 674.61, belongs to the triclinic system, space group is P-1, unit cell parameters: α(°)=72.060(3), β(°)=77.983(3), γ(°)=81.530(3), Z=1.

2. The use according to claim 1, characterized in that The photochromic response wavelength range is 200-500nm.

3. An anti-ultraviolet and / or anti-blue light material, characterized in that: The material is composed of a viologen coordination compound crystal represented by formula (I) as claimed in claim 1 and an optical resin material.

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