Manganese-based crystal material with temperature-triggered reversible structural transition and adjustable luminescent color, and preparation method and application thereof

Abstract

The present application relates to the field of optical materials, and particularly relates to a manganese-based crystal material with temperature-triggered reversible structure transition and adjustable light-emitting color and a preparation method and application thereof. The red light-emitting phase has a chemical formula of (C6H8N)3Mn2Cl7.3H2O, belongs to a monoclinic system, and a space group is P2(1) / n P2 1 / n ; the green light-emitting phase has a chemical formula of (C6H8N)2MnCl4, belongs to a monoclinic system, and a space group is P2(1) / n C2 / c . The present application provides a manganese-based crystal material with temperature-triggered reversible structure transition and adjustable light-emitting color, which has a chemical formula of (C6H8N)3Mn2Cl7.3H2O at room temperature and is converted into (C6H8N)2MnCl4 after being heated to 60 DEG C. The crystal material can be obtained by using a simple solvent evaporation method, and the preparation method is simple. The reversible removal and adsorption of crystal water by temperature or humidity can realize the reversible structure transition and light-emitting switching between the water-containing red light-emitting crystal and the anhydrous green light-emitting crystal.

Description

Technical Field

[0001] This invention relates to the field of optical materials, and more particularly to a manganese-based crystal material with temperature-triggered reversible structural transformation and tunable luminescence color, its preparation method, and its applications. Background Technology

[0002] Organic-inorganic hybrid metal halide materials have gained widespread attention in fields such as solid-state lighting and display backlighting due to their excellent optoelectronic properties. Among them, manganese-based halide systems, with their advantages of high raw material abundance, low biotoxicity, low manufacturing cost, and characteristic dd transition emission, have become a strong candidate system to replace traditional rare-earth-doped phosphors and lead-based perovskite materials. Although lead-based perovskites have excellent optoelectronic properties, their inherent toxicity severely restricts their commercialization, thus further driving the research boom in manganese-based halide systems. The characteristic emission of manganese ions essentially originates from their 3d transition emission. 5 Within the configuration 4 T1→ 6 The A1 transition, a radiative transition, has an emission wavelength that is highly sensitive to the local coordination environment. Crystal field theory indicates that when Mn... 2+ With tetracoordinate [MnX4] 2- When a tetrahedral configuration exists, the crystal field splitting energy is relatively small, resulting in narrow-band green light emission; while with a six-coordinate [MnX6] configuration... 4- When the octahedral configuration is present, the splitting energy is significantly increased, resulting in broadband red light emission.

[0003] The emission color of manganese-based luminescent materials is mainly controlled through chemical composition adjustment strategies. For example, by changing the type of organic cations and their molar ratio with manganese salts, manganese-based halides with tetrahedral or octahedral coordination can be selectively induced, thereby obtaining green or red light emission, respectively. However, a significant drawback of this strategy is that the emission color of the material is fixed after synthesis, making dynamic and reversible control impossible. In recent years, some studies have attempted to use external stimuli such as temperature and humidity to induce structural phase transitions in materials to achieve emission switching, but these still suffer from problems such as slow response speed, insufficient reversibility, and dependence on specific humidity environments.

[0004] Therefore, developing a novel manganese-based red-green luminescent reversible variable material with fast response speed, good reversibility, and convenient control method is of great significance for promoting the practical application of manganese-based luminescent materials in cutting-edge fields such as intelligent sensing, dynamic anti-counterfeiting, and information encryption.

[0005] Therefore, existing technologies need to be improved. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescent color, as well as its preparation method and application. The aim is to provide a novel manganese-based red-green luminescent reversible transformation material with fast response speed, good reversibility and convenient control method.

[0007] The technical solution of the present invention is as follows: In a first aspect, the present invention provides a manganese-based crystalline material with a temperature-triggered reversible structural transformation and tunable luminescence color, comprising a red-emitting phase and a green-emitting phase that can interconvert, wherein the red-emitting phase has the chemical formula (C6H8N)3Mn2Cl7·3H2O at room temperature, belongs to the monoclinic crystal system, and has a space group of P2 1 / n The unit cell parameters are a = 7.3466(1)Å, b =19.1855(3)Å, c = 20.7478(3) Å, α = γ = 90°, β = 97.790(2)°, Z = 4, V = 2897.38(7)Å 3 ; The green-emitting phase has the chemical formula (C6H8N)2MnCl4 at room temperature, belongs to the monoclinic crystal system, and has the space group [missing information]. C2 / c The unit cell parameters are a = 17.7888(4)Å, b = 7.7779(2)Å, c = 25.7780(6) Å, α = γ = 90°, β = 99.350(2)°, Z= 8, V = 3519.25(15)Å 3 .

[0008] Secondly, the present invention provides a method for preparing a manganese-based crystalline material with a temperature-triggered reversible structural transition and tunable luminescence color, comprising the following steps: Anhydrous manganese chloride and hydrochloric acid were mixed, and solvent was added. The mixture was stirred until a pale yellow solution was obtained. Add 4-methylpyridine to the mixed solution, stir and heat to 70-80°C to obtain a transparent solution; The transparent solution is volatilized and crystallized at 25-35°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0009] Optionally, the solvent is water or anhydrous ethanol.

[0010] Optionally, when the solvent is water, the resulting manganese-based crystal material with temperature-triggered reversible structural transformation and tunable luminescence color has the chemical formula (C6H8N)3Mn2Cl7·3H2O, belongs to the monoclinic crystal system at room temperature, and has the space group [missing information]. P2 1 / n The unit cell parameters are a = 7.3466(1)Å, b = 19.1855(3)Å, c = 20.7478(3) Å, α = γ = 90°, β = 97.790(2)°, Z = 4, V = 2897.38(7)Å 3 .

[0011] Optionally, when the solvent is anhydrous ethanol, the resulting manganese-based crystal material with temperature-triggered reversible structural transformation and tunable luminescence color has the chemical formula (C6H8N)2MnCl4, belongs to the monoclinic crystal system at room temperature, and has a space group of C2 / c The unit cell parameters are a = 17.7888(4)Å, b = 7.7779(2)Å, c = 25.7780(6) Å, α = γ = 90°, β = 99.350(2)°, Z = 8, V = 3519.25(15)Å 3 .

[0012] Optionally, the molar ratio of anhydrous manganese chloride, HCl in hydrochloric acid, and 4-methylpyridine is 1:2:1-2.

[0013] Thirdly, the present invention provides an application of a manganese-based crystal material with temperature-triggered reversible structural transformation and tunable luminescent color in optoelectronic devices.

[0014] Beneficial effects: This invention provides a manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescent color. Its chemical formula at room temperature is (C6H8N)3Mn2Cl7·3H2O, and it transforms into (C6H8N)2MnCl4 when heated to 60℃.

[0015] It can be obtained by a simple solvent evaporation method, and the preparation method is simple and easy to obtain.

[0016] The reversible removal and adsorption of crystal water through temperature or humidity enables a reversible structural transformation and light emission switching between hydrated red crystals and anhydrous green crystals. This technology can be widely applied in dynamic displays, optical anti-counterfeiting, intelligent sensing, and information encryption. Attached Figure Description

[0017] Figure 1 This is a single-cell crystal structure diagram of the manganese-based crystal material with temperature-triggered reversible structural transformation and tunable luminescence color (compound 1) of the present invention.

[0018] Figure 2 A schematic diagram of the projection along the b-axis of a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescent color (Compound 1).

[0019] Figure 3 This is a single-cell crystal structure diagram of the manganese-based crystal material with temperature-triggered reversible structural transformation and tunable luminescence color (compound 2) of the present invention.

[0020] Figure 4 This is a crystal structure diagram of the manganese-based crystalline material with temperature-triggered reversible structural transformation and tunable luminescence color (compound 2) of the present invention.

[0021] Figure 5 This is a powder diffraction pattern of the manganese-based crystalline material (compound 1) of the present invention, which has a temperature-triggered reversible structural transformation and tunable luminescence color.

[0022] Figure 6 This is a powder diffraction pattern of the manganese-based crystalline material (compound 2) of the present invention, which has a temperature-triggered reversible structural transformation and tunable luminescence color.

[0023] Figure 7 This is the standard chromaticity coordinate diagram of the manganese-based crystal material with temperature-triggered reversible structural transformation and tunable luminescence color, as described in this invention.

[0024] Figure 8 The emission spectrum of the manganese-based crystal material with temperature-triggered reversible structural transformation and tunable emission color under 650 nm excitation (compound 1) is shown.

[0025] Figure 9 The emission spectrum of the manganese-based crystal material with temperature-triggered reversible structural transformation and tunable emission color under 530 nm excitation (compound 2) is shown.

[0026] Figure 10 The emission spectra of the manganese-based crystal material with temperature-triggered reversible structural transformation and tunable luminescence color, as measured by excitation wavelengths of 374 nm and 359 nm, are shown in the figure.

[0027] Figure 11 The lifetime decay curve of the manganese-based crystal material with temperature-triggered reversible structural transformation and tunable luminescence color (compound 1) was monitored at 650 nm using 374 nm as the excitation source.

[0028] Figure 12 The lifetime decay curve of the manganese-based crystal material with temperature-triggered reversible structural transformation and tunable luminescence color of the present invention (compound 1) was monitored at 530 nm using 359 nm as the excitation source. Detailed Implementation

[0029] This invention provides a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color, as well as its preparation method and applications. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0030] This invention marks the first time that two crystalline materials have been obtained: (C6H8N)2MnCl4 emitting green light and (C6H8N)3Mn2Cl7·3H2O emitting red light. Currently, no applications of this homologous biscrystalline system in the field of reversible red-green light emission transitions have been reported. The two crystals can be selectively obtained using the same raw materials through a simple solvent evaporation method, differing only in the presence or absence of water molecules in the crystallization system. More importantly, this invention is the first to utilize the reversible removal and adsorption of water of crystallization to achieve a reversible structural transformation and light emission switching between anhydrous red-light crystals and anhydrous green-light crystals. The prepared crystals can be widely used in dynamic displays, optical anti-counterfeiting, intelligent sensing, and information encryption.

[0031] Based on this, this embodiment provides a manganese-based crystal material with temperature-triggered reversible structural transformation and tunable luminescence color, comprising a red-emitting phase and a green-emitting phase that can interconvert, wherein the red-emitting phase has the chemical formula (C6H8N)3Mn2Cl7·3H2O at room temperature, belongs to the monoclinic crystal system, and has a space group of P2 1 / n The unit cell parameters are a = 7.3466(1)Å, b =19.1855(3)Å, c = 20.7478(3) Å, α = γ = 90°, β = 97.790(2)°, Z = 4, V = 2897.38(7)Å 3 ; The green-emitting phase has the chemical formula (C6H8N)2MnCl4 at room temperature, belongs to the monoclinic crystal system, and has the space group [missing information]. C2 / c The unit cell parameters are a = 17.7888(4)Å, b = 7.7779(2)Å, c = 25.7780(6) Å, α = γ = 90°, β= 99.350(2)°, Z= 8, V = 3519.25(15)Å 3 .

[0032] In this embodiment, the manganese-based crystal material with temperature-triggered reversible structural transition and tunable emission color was analyzed using X-ray single-crystal diffraction. Single-crystal X-ray diffraction data were collected using a Rigaku XtaLAB Synergy-R CCD single-crystal diffractometer, with Cu-Kα rays (λ = 1.542 Å) as the radiation source, a data collection temperature of 293 K, and a scanning mode of ω-2θ. The data underwent absorption correction using the Multi-Scan method. Structural analysis was performed using the SHELXTL-97 software package; and the structure was analyzed using an F-based... 2 The coordinates of all atoms and the anisotropic thermal parameters were refined using the full matrix least squares method. X-ray single crystal diffraction results showed that the chemical formula of compound 1 is (C6H8N)3Mn2Cl7·3H2O. At room temperature (293K), it belongs to the monoclinic crystal system, space group P21 / n, and the cell parameters are a = 7.3466(1)Å, b = 19.1855(3)Å, c = 20.7478(3)Å, α = γ = 90°, β = 97.790(2)°, Z = 4, V = 2897.38(7)Å. 3 .

[0033] Heating (C6H8N)3Mn2Cl7·3H2O (compound 1) at 60 °C transforms it into (C6H8N)2MnCl4 (compound 2), which belongs to the monoclinic crystal system at room temperature and has a space group of [missing information]. C2 / c The unit cell parameters are a = 17.7888(4)Å, b = 7.7779(2)Å, c =25.7780(6) Å, α = γ = 90°, β = 99.350(2)°, Z = 8, V = 3519.25(15)Å 3 .

[0034] (C6H8N)2MnCl4 (compound 2) will also absorb water molecules in a high humidity atmosphere and transform into (C6H8N)3Mn2Cl7·3H2O (compound 1).

[0035] In other words, (C6H8N)3Mn2Cl7·3H2O (compound 1) and (C6H8N)2MnCl4 (compound 2) can interconvert. For example, after exposure to a high humidity atmosphere or heating at 60°C, the reversible absorption or removal of coordinated water molecules can undergo a sensitive reversible transition between red and green light emission.

[0036] This embodiment also provides a method for preparing a manganese-based crystalline material with a temperature-triggered reversible structural transition and tunable luminescence color, comprising the following steps: Anhydrous manganese chloride and hydrochloric acid were mixed, and solvent was added. The mixture was stirred until a pale yellow solution was obtained. Add 4-methylpyridine to the mixed solution, stir and heat to 70-80°C to obtain a transparent solution; The transparent solution is volatilized and crystallized at 25-35°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0037] For example, it can be stirred and heated to 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, or 80°C.

[0038] For example, the transparent solution evaporates and crystallizes at 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C, and 35°C.

[0039] In some embodiments, the solvent is water or anhydrous ethanol.

[0040] In one specific embodiment, when the solvent is water, the resulting manganese-based crystal material with temperature-triggered reversible structural transformation and tunable luminescence color has the chemical formula (C6H8N)3Mn2Cl7·3H2O, belongs to the monoclinic crystal system at room temperature, and has the space group [missing information]. P2 1 / n The unit cell parameters are a = 7.3466(1)Å, b = 19.1855(3)Å, c = 20.7478(3) Å, α = γ =90°, β = 97.790(2)°, Z = 4, V = 2897.38(7)Å 3 .

[0041] In one specific embodiment, when the solvent is anhydrous ethanol, the resulting manganese-based crystal material with temperature-triggered reversible structural transformation and tunable luminescence color has the chemical formula (C6H8N)2MnCl4, belongs to the monoclinic crystal system at room temperature, and has the space group [missing information]. C2 / c The unit cell parameters area = 17.7888(4)Å, b = 7.7779(2)Å, c = 25.7780(6) Å, α = γ =90°, β = 99.350(2)°, Z = 8, V = 3519.25(15)Å 3 .

[0042] In some embodiments, the molar ratio of anhydrous manganese chloride, HCl in hydrochloric acid, and 4-methylpyridine is 1:2:1-2, for example, 1:2:1 or 1:2:2.

[0043] This embodiment also provides an application of a manganese-based crystal material with temperature-triggered reversible structural transition and tunable luminescent color in optoelectronic devices.

[0044] The present invention will be further described below through specific embodiments.

[0045] Example 1 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of distilled water, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 70°C to obtain a transparent solution; The transparent solution was evaporated and crystallized at 25°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0046] Example 2 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of distilled water, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 71°C to obtain a transparent solution; The transparent solution was evaporated and crystallized at 26°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0047] Example 3 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of distilled water, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 72°C to obtain a transparent solution; The transparent solution was evaporated and crystallized at 27°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0048] Example 4 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of distilled water, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 73°C to obtain a transparent solution; The transparent solution was evaporated and crystallized at 28°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0049] Example 5 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of distilled water, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 74°C to obtain a transparent solution; The transparent solution was evaporated and crystallized at 29°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0050] Example 6 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of distilled water, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 75°C to obtain a transparent solution; The transparent solution was evaporated and crystallized at 29°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0051] Example 7 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of distilled water, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 76°C to obtain a transparent solution; The transparent solution was evaporated and crystallized at 30°C to obtain the manganese-based crystalline material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0052] Example 8 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of distilled water, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 77°C to obtain a transparent solution; The transparent solution was volatilized and crystallized at 31°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0053] Example 9 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of distilled water, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 78°C to obtain a transparent solution; The transparent solution was evaporated and crystallized at 32°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0054] Example 10 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of distilled water, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 80°C to obtain a transparent solution; The transparent solution was evaporated and crystallized at 35°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0055] The manganese-based crystal materials obtained in Examples 1-10, exhibiting temperature-triggered reversible structural transformation and tunable emission color, were analyzed using X-ray single-crystal diffraction. Single-crystal X-ray diffraction data were collected using a Rigaku XtaLAB Synergy-R CCD single-crystal diffractometer, with Cu-Kα rays (λ = 1.542 Å) as the radiation source, a data collection temperature of 293 K, and a scanning mode of ω-2θ. The data underwent absorption correction using the Multi-Scan method. Structural analysis was performed using the SHELXTL-97 software package; and the structure was analyzed using F-based... 2 The coordinates and anisotropic thermal parameters of all atoms were refined using the full matrix least squares method. X-ray single-crystal diffraction results showed that the chemical formula (C6H8N)3Mn2Cl7·3H2O belongs to the monoclinic crystal system at room temperature (293K), with space group P21 / n and cell parameters a = 7.3466(1)Å, b = 19.1855(3)Å, c = 20.7478(3)Å, α = γ = 90°, β = 97.790(2)°, Z = 4, V = 2897.38(7)Å. 3 Its crystal structure is as follows: Figure 1 As shown, Figure 1 This is a schematic diagram of the crystal structure. Figure 2 This is a schematic projection of the crystal structure along the b-axis. It can be seen that each Mn atom is coordinated with 4 Cl atoms and 2 coordinated water molecules to form a slightly distorted octahedral anionic framework structure. The octahedra are connected by Cl atoms sharing edges to form a one-dimensional chain structure.

[0056] The phase and structure of the obtained crystalline products were characterized by powder X-ray diffraction (XRD). The tests were performed on a Bruker D8 Advance X-ray powder diffractometer, with the following conditions: fixed target monochromatic light source Cu-Kα (λ = 1.540598 Å), scanning range 2θ = 5~50°, and scanning step size 0.2°. Figure 5 The powder X-ray diffraction test results of (C6H8N)3Mn2Cl7·3H2O (compound 1) and the X-ray diffraction pattern obtained from the single crystal structure simulation are shown, indicating that the obtained sample has high purity.

[0057] Example 11 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of anhydrous ethanol, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 70°C to obtain a transparent solution; The transparent solution was evaporated and crystallized at 25°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0058] Example 12 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of anhydrous ethanol, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 71°C to obtain a transparent solution; The transparent solution was evaporated and crystallized at 26°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0059] Example 13 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of anhydrous ethanol, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 72°C to obtain a transparent solution; The transparent solution was evaporated and crystallized at 27°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0060] Example 14 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of anhydrous ethanol, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 73°C to obtain a transparent solution; The transparent solution was evaporated and crystallized at 28°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0061] Example 15 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of anhydrous ethanol, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 74°C to obtain a transparent solution; The transparent solution was evaporated and crystallized at 29°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0062] Example 16 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of anhydrous ethanol, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 75°C to obtain a transparent solution; The transparent solution was evaporated and crystallized at 29°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0063] Example 17 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of anhydrous ethanol, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 76°C to obtain a transparent solution; The transparent solution was evaporated and crystallized at 30°C to obtain the manganese-based crystalline material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0064] Example 18 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g of hydrochloric acid, add 1.0 g of anhydrous ethanol, and stir until a pale yellow mixed solution is obtained. 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 77°C to obtain a transparent solution; The transparent solution was volatilized and crystallized at 31°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0065] Example 19 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of anhydrous ethanol, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 78°C to obtain a transparent solution; The transparent solution was evaporated and crystallized at 32°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0066] Example 20 A method for preparing a manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color includes the following steps: Mix 1.27 g of anhydrous manganese chloride and 2.0 g (0.02 mol) of hydrochloric acid, add 1.0 g of anhydrous ethanol, and stir until a pale yellow mixed solution is obtained; 1.90 g of 4-methylpyridine was added to the mixed solution, stirred and heated to 80°C to obtain a transparent solution; The transparent solution was evaporated and crystallized at 35°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

[0067] The manganese-based crystal materials with temperature-triggered reversible structural transformation and tunable emission color obtained in Examples 11-20 were subjected to structural analysis using X-ray single-crystal diffraction. Single-crystal X-ray diffraction data were collected using a Rigaku XtaLAB Synergy-R CCD single-crystal diffractometer, with Cu-Kα rays (λ = 1.542 Å) as the radiation source, a data collection temperature of 293 K, and a scanning mode of ω-2θ. The data underwent absorption correction using the Multi-Scan method. Structural analysis was performed using the SHELXTL-97 software package; and the structure was analyzed using an F-based... 2The coordinates and anisotropic thermal parameters of all atoms were refined using the full matrix least squares method. X-ray single-crystal diffraction results showed that the chemical formula was (C6H8N)2MnCl4, which belongs to the monoclinic crystal system at room temperature (293K), with space group C2 / c and cell parameters a = 17.7888(4) Å, b = 7.7779(2) Å, c = 25.7780(6) Å, α = γ = 90°, β = 99.350(2)°, Z = 8, V = 3519.25(15) Å. 3 Its crystal structure is as follows: Figure 3 As shown, Figure 3 This is a schematic diagram of the crystal structure. Figure 4 This is a schematic projection of the crystal structure along the b-axis. It can be seen that each Mn atom is connected to four Cl atoms to form a MnCl4 tetrahedral anionic framework. The cations are connected to the anionic framework via NH···Br hydrogen bonds, forming a one-dimensional chain structure along the c-axis. Organic cation (C6H8N) + The inorganic units are connected by N—H···Cl hydrogen bonds, which stabilizes the crystal structure and promotes the directional alignment of cations.

[0068] The phase and structure of the obtained crystalline products were characterized by powder X-ray diffraction (XRD). The tests were performed on a Bruker D8 Advance X-ray powder diffractometer, with the following conditions: fixed target monochromatic light source Cu-Kα (λ = 1.540598 Å), scanning range 2θ = 5~50°, and scanning step size 0.2°. Figure 5 , Figure 6 The powder X-ray diffraction results of (C6H8N)3Mn2Cl7·3H2O (compound 1) and (C6H8N)2MnCl4 (compound 2) are shown, along with the X-ray diffraction patterns obtained from single-crystal structure simulation. Comparison of the two patterns reveals that the positions and intensities of the diffraction peaks are essentially identical, indicating that the obtained samples have high purity.

[0069] Spectroscopic and transient fluorescence lifetime measurements were performed using an FLS 1000 transient fluorescence spectrometer manufactured by Edinburgh Instruments Ltd., UK. The tests were conducted at room temperature. (C6H8N)3Mn2Cl7·3H2O (compound 1) obtained in Examples 1-10 and (C6H8N)2MnCl4 (compound 2) obtained in Examples 11-20 were fixed on quartz plates with a thickness of 1 mm and placed inside the spectrometer's sample chamber. A pulsed laser was used as the excitation source, and spectral and transient fluorescence lifetime data were acquired for each sample. Figure 7As shown, the CIE 1931 color coordinates of compound 1, calculated from the emission spectrum, are (0.6102, 0.3636), located in the red region, while the CIE 1931 color coordinates of compound 2 are (0.2605, 0.6733), located in the green region. This indicates that both crystals obtained in this invention have characteristic emission with high color purity and are suitable for red and green light-emitting devices, respectively.

[0070] With emission wavelengths fixed at 650 nm and 530 nm, the excitation spectra of (C6H8N)3Mn2Cl7·3H2O (compound 1) obtained in Examples 1-10 and (C6H8N)2MnCl4 (compound 2) obtained in Examples 11-20 were tested in the wavelength range of 200–500 nm. The excitation peaks of compound 1 were measured to be 374 nm, 400 nm, and 422 nm. Figure 8 As shown; the excitation peaks of compound 2 are at 359 nm, 382 nm, and 434 nm, as... Figure 9 As shown, the characteristic excitation peaks of compounds 1 and 2 both fall within the near-ultraviolet-blue light range, and can be effectively excited by commercial near-ultraviolet and blue LED chips, thus showing promise for application in commercial near-ultraviolet and blue LED chips.

[0071] Figure 10 The emission spectra of the manganese-based crystal material with temperature-triggered reversible structural transition and tunable luminescence color, as described in this invention, were measured at excitation wavelengths of 374 nm and 359 nm, respectively. From... Figure 10 It can be seen that the emission peaks of compound 1 and compound 2 are located at 650 nm and 530 nm, respectively. Moreover, the emission colors of the two compounds 1 and 2 can interconvert. After exposure to a high humidity atmosphere or heating at 60°C, the reversible absorption or removal of coordinated water molecules can cause a sensitive reversible transition between red and green light emission.

[0072] The optimal excitation wavelengths of compound 1 (374 nm) and compound 2 (359 nm) were used as excitation sources, respectively. The fluorescence kinetics signals at 650 nm red light and 530 nm green light were monitored, and the fluorescence lifetime decay curves of compounds 1 and 2 were obtained. The results are shown below. Figure 11 , Figure 12 As shown in the figure. Among them, the average lifetime of compound 1 was 102.163 μs, and the average lifetime of compound 2 was 3.185 μs.

[0073] In summary, this invention provides a manganese-based crystal material with a temperature-triggered reversible structural transformation and tunable luminescence color. Its chemical formula at room temperature is (C6H8N)3Mn2Cl7·3H2O, and it transforms into (C6H8N)2MnCl4 when heated to 60℃.

[0074] It can be obtained by a simple solvent evaporation method, and the preparation method is simple and easy to obtain.

[0075] The reversible removal and adsorption of crystal water through temperature or humidity enables a reversible structural transformation and light emission switching between hydrated red crystals and anhydrous green crystals. This technology can be widely applied in dynamic displays, optical anti-counterfeiting, intelligent sensing, and information encryption.

[0076] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A manganese-based crystalline material with temperature-triggered reversible structural transition and tunable luminescence color, characterized in that, This includes red-light-emitting and green-light-emitting phases that can interconvert. The red-light-emitting phase has the chemical formula (C6H8N)3Mn2Cl7·3H2O at room temperature, belongs to the monoclinic crystal system, and has the space group [missing information]. P2 1 / n The unit cell parameters are a = 7.3466(1)Å, b = 19.1855(3)Å, c =20.7478(3) Å, α = γ = 90°, β = 97.790(2)°, Z = 4, V = 2897.38(7)Å 3 ; The green-emitting phase has the chemical formula (C6H8N)2MnCl4 at room temperature, belongs to the monoclinic crystal system, and has the space group [missing information]. C2 / c The unit cell parameters are a = 17.7888(4)Å, b = 7.7779(2)Å, c = 25.7780(6) Å, α = γ = 90°, β = 99.350(2)°, Z= 8, V = 3519.25(15)Å 3 .

2. A method for preparing a manganese-based crystalline material with tunable luminescence color and temperature-triggered reversible structural transition as described in claim 1, characterized in that, Includes the following steps: Anhydrous manganese chloride and hydrochloric acid were mixed, and solvent was added. The mixture was stirred until a pale yellow solution was obtained. Add 4-methylpyridine to the mixed solution, stir and heat to 70-80°C to obtain a transparent solution; The transparent solution is volatilized and crystallized at 25-35°C to obtain the manganese-based crystal material with temperature-triggered reversible structural transformation and adjustable luminescence color.

3. The method for preparing a manganese-based crystalline material with tunable luminescence color and temperature-triggered reversible structural transition according to claim 2, characterized in that, The solvent is water or anhydrous ethanol.

4. The method for preparing a manganese-based crystalline material with tunable luminescence color and temperature-triggered reversible structural transition according to claim 3, characterized in that, When the solvent is water, the resulting manganese-based crystalline material exhibiting temperature-triggered reversible structural transformation and tunable luminescence color is a red-emitting phase with the chemical formula (C6H8N)3Mn2Cl7·3H2O. At room temperature, it belongs to the monoclinic crystal system with space group [missing information]. P2 1 / n The unit cell parameters are a = 7.3466(1)Å, b = 19.1855(3)Å, c = 20.7478(3) Å, α = γ = 90°, β = 97.790(2)°, Z = 4, V = 2897.38(7)Å 3 .

5. The method for preparing a manganese-based crystalline material with tunable luminescent color and temperature-triggered reversible structural transition according to claim 3, characterized in that, When the solvent is anhydrous ethanol, the resulting manganese-based crystalline material exhibiting temperature-triggered reversible structural transformation and tunable luminescence color is a green-emitting phase with the chemical formula (C6H8N)2MnCl4. At room temperature, it belongs to the monoclinic crystal system with space group [missing information]. C2 / c The unit cell parameters are a = 17.7888(4)Å, b = 7.7779(2)Å, c = 25.7780(6) Å, α = γ = 90°, β = 99.350(2)°, Z = 8, V = 3519.25(15)Å 3 .

6. The method for preparing a manganese-based crystalline material with tunable luminescence color and temperature-triggered reversible structural transition according to claim 2, characterized in that, The molar ratio of anhydrous manganese chloride, HCl in hydrochloric acid, and 4-methylpyridine is 1:2:1-2.

7. The application of the manganese-based crystal material with temperature-triggered reversible structural transition and tunable luminescent color as described in claim 1 in optoelectronic devices.

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