Water vapor visualization material for food packaging and application of water vapor visualization material

Abstract

The invention relates to a nano composite luminescent material and the technical field of food packaging intelligent sensing. In particular to a water vapor visualization material for food packaging and application of the water vapor visualization material. The material emits orange red light (the maximum emission peak is 635 nm, the emission life is 7.2 [mu] s, and the quantum yield is about 0.30) in a solid state at the room temperature in a dry state; after contacting with water or water vapor, the material is converted into yellow light due to coordination emission of water molecules (the maximum emission peak is 608 nm, the emission life is 5.1 microseconds, and the quantum yield is increased to about 0.90), so that remarkable and visual humidity response is realized. The material is lead-free, easily available in raw materials, simple and convenient to prepare, stable in performance and suitable for food packaging, storage and transportation.

Description

Technical Field

[0001] This invention belongs to the field of nanocomposite luminescent materials and intelligent sensing technology for food packaging, specifically relating to a material for visualizing moisture in food packaging and its application. Background Technology

[0002] Moisture and environmental humidity are key factors determining product quality and safety throughout the entire food production, distribution, and storage process. Moisture infiltration can cause crisp snacks to become damp and lose their texture, powders to clump, and spices and teas to lose their aroma. Condensation during cold chain transportation can lead to moisture absorption of the outer packaging and contents, and under certain water activity conditions, it can easily induce microbial growth, shortening shelf life. Existing humidity monitoring methods mainly include silica gel desiccants and color-changing indicator cards, cobalt salt-based color-changing humidity cards, electronic humidity sensing tags (such as RFID / resistive-capacitive types), and organic fluorescent dye indicators. However, these methods generally suffer from limited response sensitivity and selectivity, insufficiently intuitive color changes or susceptibility to background interference, inadequate long-term stability and photostability, high dependence on packaging structure and power supply, potential safety and migration risks (such as some cobalt salts and small molecule organic dyes), and high preparation and integration costs. Optical readout humidity / moisture indicators offer advantages such as non-contact operation, visualization, remote readability, and easy integration into films or labels. However, achieving a rapid, significant, and interference-resistant optical response to trace amounts of moisture or water vapor while ensuring food contact safety and processing compatibility remains a key challenge for the industry. Sb(III)-based metal halides, due to their ns... 2 The self-trapped exciton emission resulting from the electronic configuration is highly sensitive to the local coordination environment and trace moisture, and holds promise as a lead-free, photostable inorganic luminescent humidity indicator platform. However, existing systems still have limited research in terms of structural controllability, response amplitude and readout consistency, as well as processability and safety isolation design under food packaging conditions.

[0003] To address the aforementioned issues, developing a lead-free inorganic luminescent material that exhibits a significant visual fluorescence response to moisture, displays a clear emission difference between dry and damp conditions, and can be formulated into inks / coatings / labels and effectively isolated from food through a barrier layer is of great significance for improving food quality monitoring and intelligent packaging. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention aims to provide a novel water vapor visualization material for food packaging, its preparation method, and its applications. This material exhibits a recognizable optical response to water molecules and can be used in fields such as water vapor detection and environmental humidity monitoring, meeting the intelligent sensing needs of food packaging scenarios and showing promising application prospects.

[0005] Objective 1 of this invention: To provide a moisture visualization material for food packaging, comprising substance A, wherein substance A has the molecular formula C40 H 48 Cl5K2O 12 The crystal structure of Sb has the following cell parameters: a = 9.4164(7) Å, b = 30.064(2) Å, c = 30.064(2) Å, α = 90°, β = 90.854(2)°, γ = 90°, and the space group is [missing information]. P twenty one.

[0006] According to a preferred embodiment of the present invention, the above-mentioned substance A can be prepared by the following method: Antimony (Sb) salt, KCl and It is prepared by self-assembly reaction in solvent A.

[0007] According to a preferred embodiment of the present invention, the antimony salt is SbCl3 and / or Sb(OAc)3.

[0008] According to a preferred embodiment of the present invention, the SbCl3 and KCl and The molar ratio is 1:0.2~20:0.2~20, and the optimal ratio is 1:2:2.

[0009] According to a preferred embodiment of the present invention, the Sb(OAc)3 and KCl and The molar ratio is 1:0.4~40:0.2~20, and the optimal ratio is 1:4:2.

[0010] According to a preferred embodiment of the present invention, the solvent A is selected from one or more of methanol, ethanol, propanol, isopropanol, butanol, acetonitrile, dichloromethane, acetone, n-hexane, chloroform, N,N-dimethylformamide, N,N-dimethylacetamide, and 1,2-dichloroethane; preferably, the solvent is dried and dehydrated before use.

[0011] The second objective of this invention is to provide a moisture visualization material for food packaging, comprising substance B, wherein the molecular formula of substance B is C. 40 H 50 Cl5K2O 13 The crystal structure of Sb has the following cell parameters: a = 9.2333(2) Å, b = 16.4974(2) Å, c = 30.4616(5) Å, α = 90°, β = 98.345(2)°, γ = 90°, and the space group is [missing information]. P 21 / n.

[0012] According to a preferred embodiment of the present invention, substance B can be prepared by the following method: Option 1: In the presence of water, mix antimony salt, KCl, and... It was prepared via a self-assembly reaction in solvent B; Option 2: Add Sb₂O₃, KCl, It is prepared by self-assembly reaction of hydrochloric acid in solvent C.

[0013] According to a preferred embodiment of the present invention, in embodiment one, the antimony salt is SbCl3 and / or Sb(OAc)3.

[0014] According to a preferred embodiment of the present invention, in embodiment one, the SbCl3, KCl and The molar ratio of the substances is 1:0.2~20:0.2~20, and the optimal ratio is 1:2:2.

[0015] According to a preferred embodiment of the present invention, in Sb(OAc)3, KCl and The molar ratio of the substances is 1:0.4~40:0.2~20, and the optimal ratio is 1:4:2.

[0016] According to a preferred embodiment of the present invention, in the second embodiment, the Sb₂O₃, KCl and The molar ratio is 1:0.8~80:0.4~40, and the optimal ratio is 1:8:4.

[0017] According to a preferred embodiment of the present invention, in embodiment two, the amount of hydrochloric acid is 6 to 60 times that of Sb₂O₃.

[0018] According to a preferred embodiment of the present invention, solvent B and solvent C are one or more of water, methanol, ethanol, propanol, isopropanol, butanol, acetonitrile, dichloromethane, acetone, n-hexane, chloroform, N,N-dimethylformamide, N,N-dimethylacetamide, chloroform, and 1,2-dichloroethane.

[0019] Objective 3: To provide a single-crystal form for a moisture visualization material used in food packaging, with the following cell parameters: a = 9.4164(7) Å, b = 30.064(2) Å, c = 30.064(2) Å, α = 90°, β = 90.854(2)°, γ = 90°, and space group: P twenty one; Alternatively, its unit cell parameters are: a = 9.2333(2) Å, b = 16.4974(2) Å, c = 30.4616(5) Å, α = 90°, β = 98.345(2)°, γ = 90°, and the space group is [missing information]. P twenty one / n.

[0020] Fourth objective of the invention: to provide an application of the above-mentioned moisture visualization material for food packaging in moisture detection.

[0021] The technical features and beneficial effects of this invention are as follows: 1. A Sb(III)-based halide luminescent system was constructed using a crown ether-potassium ion template strategy. Under dry conditions, substance A was formed, which was then converted into substance B containing coordinated water after being exposed to water vapor. The structural differences could be clearly characterized by single-crystal X-ray diffraction.

[0022] 2. The synthesis method is mild and simple: it can be achieved by one-pot reaction under normal pressure, the raw materials are cheap and readily available, the yield is high (>90%), and it has the feasibility of scale-up preparation.

[0023] 3. Exhibits excellent photophysical properties in the solid state at room temperature: the maximum emission peak in the dry state is located at 635 nm, the lifetime is about 7.2 μs, and the quantum yield is about 0.30; after coordination with water molecules, the emission changes to yellow light, the peak shifts to 608 nm, the lifetime is about 5.1 μs, and the quantum yield is significantly increased to about 0.90.

[0024] 4. It exhibits a significant and visible optical response to water molecules: the emission color, peak position, lifetime and quantum yield change synchronously, which is easy to identify with the naked eye and interpret with instruments. It enables sensitive monitoring in water vapor / ambient humidity scenarios and is suitable for applications such as environmental monitoring, leak warning and smart packaging. It has good application prospects and expansion potential.

[0025] 5. Clear response mechanism: water molecules and K + Coordination induces changes in the local coordination environment and lattice rigidity, thereby modulating [SbCl5]. 2– The self-trapped exciton emission behavior leads to improved emission displacement and efficiency. Attached Figure Description

[0026] Figure 1 This is the single-crystal structure diagram of substance A.

[0027] Figure 2 Excitation of substance A in solid state (λ) em = 635 nm) and emission (λ ex = 355 nm) curve.

[0028] Figure 3 The maximum emission peak (λ) of substance A in solid state max The lifetime decay curve of ( = 635 nm).

[0029] Figure 4 This is a single-crystal structure diagram of substance B.

[0030] Figure 5 Excitation of substance B in solid state (λ) em= 608 nm) and emission (λ ex = 360 nm) curve.

[0031] Figure 6 The maximum emission peak (λ) of substance B in solid state max The lifetime decay curve of ( = 608 nm). Detailed Implementation

[0032] To make the invention's objectives, technical solutions, and effects clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments; however, this does not limit the invention to the embodiments described. Experimental methods in the following embodiments that do not specify specific conditions are performed according to conventional methods and conditions, or according to the product manual.

[0033] The reagents and solvents involved in this invention are all commercially available.

[0034] Example 1: Synthesis method of substance A in this invention Weigh out SbCl3 (1 equivalent), KCl (2 equivalents), and dibenzo-18-crown ether-6 (2 equivalents) and dissolve them in anhydrous methanol. Heat under reflux in an argon atmosphere until the solution is clear, then continue heating in an argon atmosphere to allow the solvent to slowly evaporate, precipitating colorless granular crystals. Filter, wash with a small amount of anhydrous methanol, and dry to obtain the product, colorless granular crystals, in 92.3% yield.

[0035] Example 2: Synthesis method of substance A in this invention Weigh out Sb(OAc)3 (1 equivalent), KCl (4 equivalents), and dibenzo-18-crown ether-6 (2 equivalents) and dissolve them in anhydrous methanol. Heat under reflux under argon protection until the solution is clear, then continue heating to allow the solvent to slowly evaporate, precipitating colorless, blocky crystals. Filter, wash with a small amount of anhydrous methanol, and dry, yield 91.7%.

[0036] Example 3: Synthesis method of substance B in this invention Weigh out SbCl3 (1 equivalent), KCl (2 equivalents), and dibenzo-18-crown ether-6 (2 equivalents), dissolve them in methanol, and heat under reflux until the solution is clear; then allow to stand at room temperature for slow evaporation, precipitating colorless granular crystals. Filter, wash with a small amount of methanol, and dry, yield 95.2%.

[0037] Example 4: Synthesis method of substance B in this invention Weigh out Sb(OAc)3 (1 equivalent), KCl (4 equivalents), and dibenzo-18-crown-6 (2 equivalents), dissolve them in methanol, and heat under reflux until the solution is clear; then allow to stand at room temperature to allow the solvent to evaporate slowly, precipitating colorless granular crystals. Filter, wash with a small amount of methanol, and dry, with a yield of 90.6%.

[0038] Comparative Example 1: Following the synthesis method of Example 1, KCl was replaced with NaCl, RbCl, CsCl, or NH4Cl to prepare corresponding luminescent materials, and the same spectral tests were performed in both the dry state and under conditions of exposure to moisture / water vapor. The results showed that none of the above materials exhibited the water-sensitive response characteristics of the materials of the present invention.

[0039] Comparative Example 2: Following the synthesis method of Example 2, KCl was replaced with NaCl, RbCl, CsCl, or NH4Cl to prepare the corresponding luminescent materials, and the same spectral tests were performed in both the dry state and under conditions of exposure to moisture / water vapor. The results showed that none of the above materials exhibited the water-sensitive response characteristics of the materials of the present invention.

[0040] Application Example 1: Structural characterization of substance A in this invention.

[0041] The crystal obtained in Example 1 was used as an example for X-ray single-crystal diffraction characterization. A Bruker D8 Venture diffractometer was used with Mo-Kα radiation (λ = 0.71073 Å) at a test temperature of 273 K. Data acquisition and processing were performed using Bruker APEX4 software. The cell parameters were: a = 9.4164(7) Å, b = 30.064(2) Å, c = 30.064(2) Å, α = 90°, β = 90.854(2)°, γ = 90°; the crystal system was monoclinic and the space group was [missing information]. P 21. Other key crystallographic parameters are shown in Table 1. Structural analysis indicates that the crystal molecular formula is C2. 40 H 48 Cl5K2O 12 Sb, where DB18C6 is dibenzo-18-crown-6. Anion [SbCl5] 2– It exhibits a square pyramidal configuration; the Sb–Cl bond lengths are 2.370(4)–2.636(4). Each DB18C6 bond is associated with K. + Coordination forms a monovalent cation [K(DB18C6)] + Its K–O bond length is 2.711(12)–2.849(10). Two [K(DB18C6)] + With [SbCl5] 2– A sandwich assembly was constructed via K···Cl coordination. One of the K... + It coordinates with two Cl atoms, and the other K atom is coordinated with two Cl atoms. + It coordinates with one Cl atom, and the K–Cl bond length is 3.130(6)–3.314(6). The single-crystal structure is as follows: Figure 1 As shown.

[0042] Table 1

[0043] Application Example 2: Structural Characterization of Substance B in this Invention X-ray single-crystal diffraction characterization was performed using the crystal obtained in Example 3 as an example. A Bruker D8 Venture diffractometer was used with Mo-Kα radiation (λ = 0.71073 Å) at a test temperature of 273 K. Data acquisition and processing were performed using Bruker APEX4 software. Cell parameters: a = 9.2333(2) Å, b = 16.4974(2) Å, c = 30.4616(5) Å, α = 90°, β = 98.345(2)°, γ = 90°; crystal system: monoclinic, space group: P 21 / n. Other key crystallographic parameters are shown in Table 2. Structural analysis indicates that the crystal molecular formula is C1. 40 H 50 Cl5K2O 13 Sb, where DB18C6 is dibenzo-18-crown-6. Anion [SbCl5] 2– It exhibits a square pyramidal configuration; the Sb–Cl bond lengths are 2.3756(5)–2.6745(7). DB18C6 and K + Coordination forms a monovalent cation [K(DB18C6)] + Its K–O bond length is 2.7535(18)–2.8487(16). Two [K(DB18C6)] + With [SbCl5] 2– A sandwich assembly was constructed using K···Cl coordination interactions: one K+ atom was coordinated with two Cl atoms, with K–Cl bond lengths of 3.2631(8)–3.2857(8); another K… + It coordinates with one Cl atom and one H₂O molecule, with K–Cl and K–O bond lengths of 3.2148(9) and 3.074(4), respectively. The single-crystal structure is shown in [reference needed]. Figure 4 .

[0044] Table 2

[0045] Application Example 3: Photophysical Characterization Material A obtained in Example 1 was used for photophysical characterization. Its excitation-emission spectrum and time-resolved emission lifetime were measured at room temperature in a solid state using an Edinburgh FLS920 fluorescence spectrometer. The results showed that the material emits orange-red light, and the excitation and emission spectra are shown below. Figure 2 The maximum emission peak is located at 635 nm; the emission lifetime is 7.2 μs (see...). Figure 3 The luminescence quantum yield was 0.30. After the sample was treated in a water vapor atmosphere, water molecules coordinated to form the corresponding substance B (see...). Figure 4 The emission light changed from orange-red to yellow; the excitation and emission spectra are shown below. Figure 5 The maximum emission peak is located at 608 nm; the emission lifetime is 5.1 μs (see...). Figure 6 The luminescent quantum yield was increased to 0.90.

[0046] The above experimental results show that the material provided by this invention can achieve a blue shift in emission wavelength in the presence of water vapor, changing from orange-red light to yellow light. Clearly, under ultraviolet light, the water vapor content inside the packaging bag can be visually inspected, making the detection sensitive and convenient. Therefore, the material of this invention can detect water vapor inside packaging bags and has potential application prospects in the field of food packaging bags.

Claims

1. A water vapor visualizing material for food packaging, characterized by, which comprises a substance A having the molecular formula C 40 H 48 Cl5K2O 12 Sb; cell parameters: a = 9.4164(7) Å, b = 30.064(2) Å, c = 30.064(2) Å, α = 90°, β = 90.854(2)°, γ = 90°, space group P 21.

2. The water vapor visualizing material for food packaging according to claim 1, wherein The substance A is prepared by the following method: an antimony salt, KCl and are prepared by self-assembly reaction in a solvent.

3. The water vapor visualizing material for food packaging according to claim 2, wherein The antimony salt is SbCl3 and / or Sb(OAc)3.

4. The water vapor visualizing material for food packaging according to claim 2, wherein The solvent is selected from one or more of methanol, ethanol, propanol, isopropanol, butanol, acetonitrile, dichloromethane, acetone, n-hexane, chloroform, N,N-dimethylformamide, N,N-dimethylacetamide, and 1,2-dichloroethane.

5. The water vapor visualizing material for food packaging according to claim 3, wherein The substance amount ratio of the SbCl3, KCl and is 1 : 0.2~20 : 0.2~20.

6. The water vapor visualizing material for food packaging according to claim 3, wherein The Sb(OAc)3 and KCl are in a molar ratio of 1 : 0.4~40 : 0.2~20. The Sb(OAc)3 and KCl are in a molar ratio of 1 : 0.4~40 : 0.2~20.

7. A water vapor visualizing material for food packaging, characterized by, which comprises a substance B, the molecular formula of which is C 40 H 50 Cl5K2O 13 Sb, with the cell parameters: a = 9.2333(2) Å, b = 16.4974(2) Å, c = 30.4616(5) Å, α = 90°, β = 98.345(2) °, γ = 90°, space group P 21 / n.

8. The water vapor visualizing material for food packaging according to claim 7, wherein The substance B is prepared by the following method: Scheme one: in the presence of water, antimony salt, KCl and Prepared by self-assembly reaction in solvent; Scheme two: Sb2O3, KCl, and hydrochloric acid are prepared by self-assembly reaction in a solvent.

9. The water vapor visualizing material for food packaging according to claim 8, wherein One or more of the following conditions are met: 1) In Scheme I, the antimony salt is SbCl3 and / or Sb(OAc)3; 2) In the first scheme, the mass ratio of the SbCl3, KCl and 0.2~20 : 0.2~20. 3) in the first aspect, the mass ratio of the Sb(OAc)3, KCl and 1 : 0.4~40 : 0.2~20; 4) in the second scheme, the mass ratio of the Sb2O3, KCl and is 1:0.8~80:0.4~40; 5) In Scheme II, the amount of substance of the hydrochloric acid is 6-60 times that of Sb2O3; 6) The solvent is water, methanol, ethanol, propanol, isopropanol, butanol, acetonitrile, dichloromethane, acetone, n-hexane, chloroform, N,N-dimethylformamide, N,N-dimethylacetamide, chloroform, 1,2-dichloroethane, or a combination of one or more thereof.

10. Use of the water vapor visualizing material for food packaging according to any one of claims 1-9 in water vapor detection.

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