A multifunctional viologen coordination compound crystal and a preparation method thereof

Abstract

A multifunctional viologen coordination compound crystal and a preparation method thereof. The structural formula of the crystal is shown in formula (I): wherein Ma is (CHO2) ‑ . In the present invention, H2bcbpy·2Cl molecules are used as the guest, metal Zn is used as the center, and chlorine atoms and oxygen atoms are used as electron donors, providing a multifunctional color-changing material that can respond to ultraviolet light and blue light, and also has thermal induction and ammonia-induced color change. The preparation method of the present invention has non-toxic raw materials, a simple method, and is suitable for large-scale production.

Description

Technical Field

[0001] The present invention relates to a novel viologen color-changing crystalline material and a preparation method thereof, and particularly relates to a coordination compound material synthesized based on electron transfer between a viologen ligand and an electron donor molecule. Background Art

[0002] The design and synthesis of bifunctional or multifunctional crystalline materials, such as materials with multiple ferromagnetic or multiple color-changing properties, have attracted great attention from researchers in the past few decades, because these materials have potential or actual applications in energy storage, magnetic materials, sensors, gas storage and separation, catalytic performance, nonlinear optics, piezoelectric properties, proton conductivity, etc. Coordination compounds with color-changing properties are a relatively common but significant type of compound. Such compound materials can sense many stimuli and can respond to stimuli such as light, electricity, heat, acidity, alkalinity, pressure, etc. and exhibit corresponding color changes. The structures of such materials can be designed and regulated and the functions are diverse, so they have been deeply explored by researchers as a hot topic recently. Photochromic and thermochromic materials have potential application prospects in many fields such as smart windows, information storage, erasable copy paper, protection, decoration, display, storage, switches, etc. If a single material simultaneously has two color-changing properties of photochromism and thermochromism, then it has multiple response functions to external stimuli and thus is expected to be more widely used. However, in actual research, such materials often only have a single response property, and most of them are photochromic materials. Most of them will undergo a huge isomerization phenomenon after responding to stimuli and rarely have a color-changing phenomenon induced by an electron transfer pathway. For example, traditional color-changing materials synthesized with piperazine-based and Schiff base-based ligands as the main body. If this situation cannot be improved, it will greatly limit the development and application of such materials, so that it has reached a bottleneck period. Therefore, it is of great significance to obtain a dual-color-changing functional material with both photochromism and thermochromism. For the design, research and synthesis of such multifunctional materials, it is essential to explore and study the key factors affecting photochromic and thermochromic behaviors.

[0003] As an interesting organic ligand that plays a role in the redox process, viologen-based cationic organic ligands (V 2+ , 1,1-disubstituted-4,4-bipyridine) have reversible color-changing properties, electron-deficient characteristics and redox properties. The viologen cation V 2+Electrons provided by the electron donor form a viologen cation radical, accompanied by a visible color change. Therefore, for viologen cation ligands, a relatively interesting property is the color change process formed by the electron transfer process between the electron donor and the acceptor. Since the electron transfer process is the inducing factor for the color change of viologen compounds, factors affecting electron transfer have been deeply explored, such as the spatial packing type of the compound structure, the length of the distance between the electron donor and the acceptor and their mutual directions, the interaction force of intermolecular or intramolecular hydrogen bonds, and the sensing ability of the viologen unit to photoelectricity, heat, and acidity. Summary of the Invention

[0004] The object of the present invention is to provide a multifunctional color-changing material based on viologen coordination compounds.

[0005] To achieve the above object, the present invention includes the following technical solutions:

[0006] A multifunctional viologen coordination compound crystal, whose structural formula is shown in formula (I):

[0007] Where Ma is (CHO2) - .

[0008] For the multifunctional viologen coordination compound crystal as described above, preferably, the crystallographic parameters of the crystal are as follows: the molecular weight is 614.31, belonging to the monoclinic system, the space group is Cc, and the unit cell parameters: α(°)=90, β(°)=114.944(3), γ(°)=90, Z = 4.

[0009] On the other hand, the present invention provides a preparation method of the multifunctional viologen coordination compound crystal as described above, and the method includes the following steps:

[0010] I. Dissolve zinc nitrate and 1,1-bis(3-carboxyphenyl)-4,4-bipyridine dichloride in a solution of deionized water and N,N-dimethylformamide according to a molar ratio of (1-3):1, and dissolve by stirring;

[0011] II. Place the dissolved solution in a reaction kettle with a polytetrafluoroethylene lining, and carry out synthesis by the solvothermal method. After keeping the temperature constant at (90-110)°C for (2-4) days, cool to room temperature, wash with deionized water, and then obtain light yellow needle-shaped crystals, which are the multifunctional viologen coordination compound crystals.

[0012] For the preparation method as described above, preferably, the volume ratio of water to N,N-dimethylformamide in step I is (1-4):1.

[0013] The preparation method as described above, preferably, the method comprises the following steps:

[0014] I. Dissolve zinc nitrate and 1,1-bis(3-carboxyphenyl)-4,4-bipyridinium dichloride in a solution of deionized water and N,N-dimethylformamide according to a molar ratio of 2:1. The volume ratio of water to N,N-dimethylformamide is 2:1, and dissolve by stirring.

[0015] II. Place the dissolved solution in a reaction kettle with a polytetrafluoroethylene liner, and perform synthesis by a solvothermal method. After maintaining a constant temperature of 100 °C for 3 days, cool to room temperature, wash with deionized water, and then obtain light yellow needle-shaped crystals, which are multifunctional viologen coordination compound crystals.

[0016] 1,1-bis(3-carboxyphenyl)-4,4-bipyridinium dichloride (H2bcbpy·2Cl) used in this application can be obtained through commercial channels or prepared by methods disclosed in the prior art. In a preferred embodiment of the present invention, the following method is used for preparation:

[0017] Add 4,4'-bipyridine and 3-chloromethylbenzoic acid with a molar ratio of 1:(2-2.5) to N,N-dimethylformamide. Under the protection of N2 gas, heat and reflux at a temperature of 110-130 °C for 6-10 hours, then cool to room temperature and filter to obtain a yellow precipitate. Wash the precipitate three times with a hot DMF solution, then wash three times with ethanol, and vacuum dry at 60-80 °C for 10-15 hours; recrystallize with an acetone and deionized water solution with a volume ratio of 1:(1-2) to obtain a highly pure H2bcbpy·2Cl viologen compound.

[0018] The beneficial effects of the present invention are as follows:

[0019] (1) The present invention adopts a simple solvothermal synthesis method. The viologen ligand, solvent, and metal salt used are all non-toxic and harmless, and this method is economical and environmentally friendly.

[0020] (2) The multifunctional viologen coordination compound crystals of the present invention have the properties of photochromism and thermochromism, can sense different light sources such as ultraviolet light and blue light at extremely low concentrations, and have a fast color change speed.

[0021] (3) The multifunctional viologen coordination compound crystals of the present invention can absorb and reflect blue light and ultraviolet light, and can be used as optical materials for preventing blue light and ultraviolet light.

[0022] (4) The multifunctional viologen coordination compound crystals of the present invention change color when encountering ammonia gas and change color rapidly at low concentrations, and can be used as materials for adsorbing and detecting ammonia gas, such as making ammonia gas detection test strips. Description of the Drawings

[0023] Figure 1 Asymmetric structural unit diagram of the compound prepared in Example 1.

[0024] Figure 2 Packing diagram of the compound prepared in Example 1.

[0025] Figure 3 Helical structure diagram of the compound prepared in Example 1.

[0026] Figure 4 UV solid diffuse reflection diagram of the compound prepared in Example 1.

[0027] Figure 5 PXRD diagram of the compound prepared in Example 1.

[0028] Figure 6 ESR spectrum diagram of the compound prepared in Example 1.

[0029] Figure 7 Photochromic photo of the compound prepared in Example 1.

[0030] Figure 8 Thermochromic photo of the compound prepared in Example 1.

[0031] Figure 9 Photo of the compound prepared in Example 1 showing color change upon ammonia adsorption.

[0032] Figure 10 UV solid diffuse reflection diagram of the anti-UV and anti-blue light lens.

[0033] Figure 11 Photo of the color change detected by the ammonia test paper. Detailed implementation manners

[0034] In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions and tests of the present invention will be described in more detail. Obviously, the described embodiments are only a part of the present invention, rather than all embodiments.

[0035] Example 1 Multifunctional viologen coordination compound crystal (I)

[0036] 1. Preparation of viologen compound 1,1-bis(3-carboxyphenyl)-4,4-bipyridinium dichloride (H2bcbpy·2Cl)

[0037] 4,4'-Bipyridine (2 g, 12.8 mmol) and 3-chloromethylbenzoic acid (6.56 g, 38.4 mmol) were added to a 50 mL round-bottom flask containing 13 mL of N,N-dimethylformamide. Under the protection of N2 gas, the mixture was heated to reflux at 120 °C for 8 h, then cooled to 25 °C and filtered to obtain a yellow precipitate, which was washed three times with hot DMF solution and then three times with ethanol, and dried in vacuo at 70 °C for 12 h. After recrystallization with an acetone and deionized water solution in a volume ratio of 1:1, a highly pure H2bcbpy·2Cl viologen compound was obtained. The yield was 93%, and the elemental analysis of C 26 H 22 O4N2Cl2 (%) : theoretical values: C, 62.80; H, 4.42; N, 5.64%. Experimental values: C, 62.75; H, 4.58; N, 5.59%.

[0038] 2. Preparation of multifunctional viologen coordination compound crystal [Zn(Ma)(bcbpy)Cl]·2H2O

[0039] Zn(NO3)2·6H2O (0.2 mmol, 60 mg) and H2bcbpy·2Cl (0.1 mmol, 49.7 mg) were dissolved in a solution of 4 ml of deionized water and 2 ml of N,N-dimethylformamide, and dissolved by stirring. The dissolved solution was placed in a reaction kettle with a 20 ml polytetrafluoroethylene liner and synthesized by solvothermal method. After maintaining at 100 °C for 3 d, it was cooled to room temperature, washed with deionized water, and then a pale yellow needle-like crystal was obtained, which was the target compound. The yield was 87%. The elemental analysis of C 27 H 25 O 8.5 N2ClZn (%) : theoretical values: C, 43.71; H, 3.39; N, 3.46%. Experimental values: C, 43.09; H, 3.48; N, 3.37%.

[0040] 3. Crystal detection

[0041] (1) X-ray single crystal diffraction

[0042] For the product obtained in step 2, on a Gemini R Ultra diffractometer, using the Oxford diffraction method, at 296 K, and using the multi-scan technique for absorption correction, with Mo-Kα radiation from a graphite monochromator ( )Crystal data were collected for the radiation source. Its crystal structure was solved using the 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 the hydrogen atoms on the viologen ligand were fixed. The crystallographic parameters are as follows: the molecular weight is 614.31, it belongs to the monoclinic system, the space group is Cc, and the unit cell parameters: α(°) = 90, β(°) = 114.944(3), γ(°) = 90, Z = 4. The crystallographic data are shown in Table 1.

[0043] Table 1

[0044]

[0045] Figure 1 is the asymmetric structural unit diagram of the compound, Figure 2 is the packing diagram of the compound, Figure 3 is the helical structure diagram of the compound. The structural formula of the compound can be determined as follows:

[0046] where Ma is (CHO2) - .

[0047] (2) UV solid diffuse reflection

[0048] Figure 4 is the UV solid diffuse reflection diagram of the compound, Figure 4 a is the UV solid diffuse reflection absorption curve of the photochromic compound. It can be seen from the figure that there are absorption peaks in the UV light region less than 400 nm and the blue light region of 400 - 420 nm, and the light absorption reaches saturation in about 10 minutes. The compound after color change can return to the original crystal color when placed in the dark for 6 - 12 h. Figure 4 b is the UV solid diffuse reflection absorption curve of the thermochromic compound. Under the condition of 90 °C, it changes color after heating for 5 minutes and has absorption in the regions of 600 - 650 nm and 750 - 775 nm.

[0049] (3) Powder X-ray diffraction

[0050] Figure 5 is the PXRD diagram of the compound, which proves the stability of the compound after color change under light and heating. It can be seen from the figure that the PXRD of the compound after light and heating hardly changes, indicating that the color change response of the compound is due to the generation of free radicals changing 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.

[0051] (4) Electron paramagnetic resonance spectrum

[0052] Figure 6 The ESR spectrum of the compound shows a characteristic peak of viologen radical at 1.9899, which proves that the color change mechanism of the compound is caused by the generation of corresponding radicals. This is a further proof after the PXRD test results. The ERS test shows that the color change of the compound is caused by photoinduced radical generation, completely excluding the possibilities of photoisomerization and photodecomposition.

[0053] Example 2 Multifunctional Viologen Coordination Compound Crystal (II)

[0054] Dissolve Zn(NO3)2·6H2O (0.15 mmol, 45 mg) and H2bcbpy·2Cl (0.05 mmol, 24.8 mg) in a solution of 3 ml deionized water and 3 ml N,N-dimethylformamide, and dissolve by stirring. Place the dissolved solution in a reaction kettle with a 20 ml polytetrafluoroethylene liner, and synthesize by the solvothermal method. After maintaining at 90 °C for 2 d, cool to room temperature, wash with deionized water, and then obtain light yellow needle-like crystals, which are the target compound. The yield is 85%. Elemental analysis C 27 H 25 O 8.5 N2C1Zn (%) : Theoretical value: C, 43.71; H, 3.39; N, 3.46%. Experimental value: C, 43.11; H, 3.45; N, 3.33%.

[0055] Example 3 Multifunctional Viologen Coordination Compound Crystal (III)

[0056] Dissolve Zn(NO3)2·6H2O (0.3 mmol, 90 mg) and H2bcbpy·2Cl (0.1 mmol, 49.7 mg) in a solution of 2 ml deionized water and 4 ml N,N-dimethylformamide, and dissolve by stirring. Place the dissolved solution in a reaction kettle with a 20 ml polytetrafluoroethylene liner, and synthesize by the solvothermal method. After maintaining at 85 °C for 3 d, cool to room temperature, wash with deionized water, and then obtain light yellow needle-like crystals, which are the target compound. The yield is 86%. Elemental analysis C 27 H 25 O 8.5 N2C1Zn (%) : Theoretical value: C, 43.71; H, 3.39; N, 3.46%. Experimental value: C, 43.12; H, 3.47; N, 3.36%.

[0057] Experimental Example 1 Photochromic Experiment

[0058] The compound prepared in Example 1 was irradiated with a 300W xenon lamp, equipped with filters for the ultraviolet band, full wavelength, and blue light band respectively, with ultraviolet light of wavelengths 200 - 400nm, blue light of 400 - 480nm, and white light of 200 - 800nm. The radiation intensity was 150Lux for all cases.

[0059] The photos before and after color change are as Figure 7 shown. The original crystal was yellow. When the crystal was irradiated with ultraviolet light of 200 - 400nm, it turned dark green after 10 seconds and the color restored after 120 minutes when the light source was removed; when irradiated with light of 200 - 800nm, it turned indigo blue after 10 seconds and the color restored after 120 minutes when the light source was removed; when irradiated with blue light of 400 - 480nm, it turned light green after 10 seconds and the color restored after 90 minutes when the light source was removed.

[0060] Experimental Example 2 Thermochromic experiment

[0061] The heat source was a selected vacuum drying oven. The compound crystal material prepared in Example 1 changed color when heated at 90°C for 5 minutes. The photos before and after color change are as Figure 8 shown. After heating, the crystal changed from yellow to ochre red. After cooling in the dark to room temperature for 15 minutes, the crystal restored to its pre - heated color.

[0062] Experimental Example 3 Ammonia adsorption color change experiment

[0063] The ammonia adsorption color change experiment was a beaker experiment conducted under slightly heated evaporation conditions of ammonia water, with an ammonia concentration of 150mg / m 3 , and the photos of the compound crystal material prepared in Example 1 before and after color change are as Figure 9 shown. The crystal changed from yellow to emerald green 0.1 minute after ammonia adsorption. The test paper could restore to its original color about 1 - 2 minutes after leaving the ammonia environment, and the color change was reversible and could be used repeatedly for many times.

[0064] Example 4 Anti - ultraviolet and blue - light lenses (I)

[0065] Take 0.5g of the crystal material prepared in Example 1, add 5ml of methanol and 5ml of ethanol for solubilization, stir for 15 minutes, after dispersing evenly, filter through a 0.45μm test paper, dissolve it in 50g of styrene monomer, stir evenly at high speed, then add 1.0g of initiator benzoyl peroxide, control the pre - polymerization reaction to proceed at 90°C for 5 hours. After the pre - polymerization was completed, put it into a programmed - temperature furnace for 10 - hour programmed - temperature curing, with the temperature rising from room temperature to 80°C for the curing reaction, cool to room temperature, then open the mold, grind the edges, and clean. Put the above - ground and washed lenses into a secondary curing furnace and cure at 120°C for 3 hours to obtain optical lenses. The absorbance of the lenses is as Figure 10As shown in a, it has good absorption in the ultraviolet band and the strong blue light band of 400 - 450 nm. The absorbance is 0.87 at 407 nm and 0.55 at 450 nm.

[0066] Example 5 Anti - ultraviolet and Blue - light Lenses (II)

[0067] Take 0.15 g of the crystal material prepared in Example 1, add 9 ml of methanol and 1 ml of ethanol for solubilization, stir for 20 minutes. After dispersion and filtration through a 0.45 - μm test paper, dissolve it in 100 g of diallyl diglycol dicarbonate monomer, stir evenly at high speed, then add 1.5 g of di - isopropyl peroxydicarbonate initiator, and control the prepolymerization reaction at 55 °C for 4 hours. After the prepolymerization is completed, put it into a programmed - temperature furnace for 15 - hour programmed - temperature curing. The temperature is raised from room temperature to 80 °C for the curing reaction. After cooling to room temperature, open the mold, grind the edges, and clean. Put the above - ground and cleaned lenses into a secondary curing furnace and cure at 140 °C for 3 hours to obtain... The absorbance of the lenses is as Figure 10 As shown in b, it has good absorption in the ultraviolet band and the strong blue light band of 400 - 450 nm. The absorbance is 0.85 at 407 nm and 0.42 at 450 nm.

[0068] Example 6 Anti - ultraviolet and Blue - light Lenses (III)

[0069] Take 0.15 g of the crystal material prepared in Example 1, add 10 ml of methanol for solubilization, stir for 30 minutes. After dispersion and filtration through a 0.45 - μm test paper, dissolve it in 100 g of methyl methacrylate, stir evenly at high speed, then add 2.5 g of azobisisobutyronitrile initiator, and control the prepolymerization reaction at 60 °C for 3 hours. After the prepolymerization is completed, put it into a programmed - temperature furnace for 10 - hour programmed - temperature curing. The temperature is raised from room temperature to 75 °C for the curing reaction. After cooling to room temperature, open the mold, grind the edges, and clean. Put the above - ground and cleaned lenses into a secondary curing furnace and cure at 120 °C for 3 hours to obtain anti - ultraviolet and blue - light lenses. The absorbance of the lenses is as Figure 10 As shown in c, it has good absorption in the ultraviolet band and the strong blue light band of 400 - 450 nm. The absorbance is 0.86 at 407 nm and 0.47 at 450 nm.

[0070] Example 7 Ammonia Detection Test Paper (I)

[0071] 1. Take 0.1 g of the viologen coordination compound crystal prepared in Example 1, dissolve it with 5 ml of methanol and 5 ml of ethanol, then add it to a mixed solution of 5 g of polystyrene sulfonic acid, 5 g of polyethyleneimine and 5 ml of water, stir evenly, and evenly coat the mixture on filter paper, smear 3 times, and the total smearing amount is 50 mg / cm 2The test paper is air-dried to obtain a rapid ammonia detection test paper.

[0072] 2. Dissolve ammonia water in ethanol to prepare a quantitative solution, inject it into a closed container with a known volume using a quantitative syringe, heat to completely vaporize the solution, and the ammonia concentration in the container is 15 mg / L. Put the ammonia detection test paper prepared in step 1 into the container, and it changes color after 5 seconds. The result is as Figure 11 shown in a, and the filter paper turns dark blue in the ammonia atmosphere.

[0073] Example 8 Ammonia Detection Test Paper (II)

[0074] 1. Take 0.15 g of the viologen coordination compound crystal prepared in Example 1, dissolve it with the help of 8 ml of methanol and 2 ml of ethanol, then add it to a mixed solution of 5 g of polystyrene sulfonic acid, 3 g of polyethyleneimine, 2 g of polyvinylpyrrolidone and 5 ml of water, stir evenly, and sonicate for 15 minutes. Apply the mixture evenly on the filter paper, and the total application amount is 50 mg / cm 2 test paper, and dry it under vacuum at 60 °C for 2 h to obtain a rapid ammonia detection test paper.

[0075] 2. Dissolve ammonia water in ethanol to prepare a quantitative solution, inject it into a closed container with a known volume using a quantitative syringe, heat to completely vaporize the solution, and the ammonia concentration in the container is 20 mg / L. Put the ammonia detection test paper prepared in step 1 into the container, and it changes color after 4 seconds. The result is as Figure 11 shown in b, and the filter paper turns dark blue in the ammonia atmosphere.

[0076] Example 9 Ammonia Detection Test Paper (III)

[0077] 1. Take 0.2 g of the viologen coordination compound crystal prepared in Example 1, dissolve it with the help of 6 ml of methanol and 4 ml of ethanol, then add it to a mixed solution of 5 g of polystyrene sulfonic acid, 3 g of polyethyleneimine, 2 g of polyvinylpyrrolidone and 5 ml of water, stir evenly, and sonicate for 20 minutes. Apply the mixture evenly on the filter paper, and the total application amount is 50 mg / cm 2 test paper, and dry it under vacuum at 60 °C for 2 h to obtain a rapid ammonia detection test paper.

[0078] 2. Dissolve ammonia water in ethanol to prepare a quantitative solution, inject it into a closed container with a known volume using a quantitative syringe, heat to completely vaporize the solution, and the ammonia concentration in the container is 25 mg / L. Put the ammonia detection test paper prepared in step 1 into the container, and it changes color after 3 seconds. The result is as Figure 11 shown in c, and the filter paper turns dark blue in the ammonia atmosphere.

Claims

1. A multifunctional viologen coordination compound crystal, characterized in that, Its structural formula is shown in Formula (I): where Ma is (CHO2) - ; The molecular formula of this crystal is C 27 H 25 O 8.5 N2ClZn; The crystallographic parameters of the crystal are as follows: the molecular weight is 614.31, it belongs to the monoclinic system, the space group is Cc, and the unit cell parameters are: α (°) = 90, β (°) = 114.944(3), γ (°) = 90, Z = 4.

2. The preparation method of the multifunctional viologen coordination compound crystal according to claim 1, characterized in that, The method comprises the following steps: I. Dissolve zinc nitrate and 1,1-bis(3-carboxyphenyl)-4,4-bipyridinium dichloride in a solution of deionized water and N,N-dimethylformamide according to a molar ratio of (1-3):1, and dissolve by stirring; II. Place the dissolved solution in a reaction kettle with a polytetrafluoroethylene lining, and carry out synthesis by a solvothermal method. After maintaining a constant temperature at (90-110)°C for (2-4) days, cool to room temperature, wash with deionized water, and then obtain light yellow needle-like crystals, which are multi-functional viologen coordination compound crystals.

3. The preparation method according to claim 2, characterized in that, In the step I, the volume ratio of water to N,N-dimethylformamide is (1-4):

1.

4. The preparation method according to claim 2, wherein The method comprises the following steps: I. Dissolve zinc nitrate and 1,1-bis(3-carboxyphenyl)-4,4-bipyridinium dichloride in a solution of deionized water and N,N-dimethylformamide according to a molar ratio of 2:1, the volume ratio of water to N,N-dimethylformamide is 2:1, and dissolve by stirring; II. Place the dissolved solution in a reaction kettle with a polytetrafluoroethylene lining, and carry out synthesis by a solvothermal method. After maintaining a constant temperature at 100°C for 3 d, cool to room temperature, wash with deionized water, and then obtain light yellow needle-like crystals, which are multi-functional viologen coordination compound crystals.

Images