Organic-inorganic hybrid manganese-based halide crystal as well as preparation method and application thereof

Abstract

The invention discloses an organic-inorganic hybrid manganese-based halide crystal as well as a preparation method and application thereof, and belongs to the technical field of molecular materials. The molecular formula of the crystal is IQ2MnBr4, IQ is isoquinolyl, namely (C9H7N) 2MnBr4, and the crystal has a reversible crystal phase change characteristic, can be mutually converted between a centrosymmetric structure and a non-centrosymmetric structure, also has a photoluminescence characteristic and can emit green fluorescence under ultraviolet irradiation. Isoquinoline is used as an organic cation, manganese bromide tetrahydrate metal salt is used as a manganese metal ligand, and a room-temperature slow evaporation method is adopted to prepare the catalyst. The organic-inorganic hybrid manganese-based halide crystal disclosed by the invention is a novel monomolecular crystal which is flexible in structure, small in molecular weight and excellent in thermal stability, relatively stable in crystal growth and moderate in growth rate, emits green light under ultraviolet irradiation, and has application potential in photoluminescent devices.

Description

Technical Field

[0001] The invention belongs to the technical field of molecular materials, and in particular relates to an organic-inorganic hybrid manganese-based halide crystal and a preparation method and application thereof. Background Art

[0002] Organic-inorganic hybrid metal halides have become an important research object in the field of optoelectronic materials due to their excellent properties of combining organic and inorganic components and simple synthesis methods, and have broad application prospects. Three-dimensional (3D) lead-based metal halides have become a research hotspot due to their excellent optical properties, but their environmental unfriendliness and structural instability limit their application. Therefore, researchers are eager to develop new hybrid metal halides that can replace hybrid lead-based halides and achieve environmental friendliness, structural stability, and multi-scenario use.

[0003] Since manganese (Mn) and lead are similar in atomic size and position, and its ionic radius is small, and its electronic configuration and valence state are similar to those of lead, manganese ions can replace lead ions and occupy the same lattice position. Therefore, designing Mn(II)-based organic-inorganic hybrid halide multifunctional molecular materials with magneto-optical-electric triple response to achieve multifunctional coupling is considered a promising research direction. Mn(II)-based halides have paramagnetism, which is due to the presence of unpaired electrons caused by the high spin configuration of Mn(II) d orbital electrons. At the same time, Mn(II)-based halides exhibit good fluorescence properties under ultraviolet light irradiation, which is due to the unique electronic transition process of Mn(II), which can emit visible light fluorescence under ultraviolet light excitation.

[0004] Studies have shown that compared with traditional metal cations, organic cations are rich in variety and diverse in performance, and low-dimensional organic-inorganic hybrid metal halide materials also perform well in terms of photoelectric performance (Journal of Materials Chemistry C, 2023, 11 (48), 16890-16911.). The synthesis of new organic-inorganic hybrid metal halides by self-assembly of organic and inorganic molecules can not only have the excellent thermal stability and other physical properties of inorganic components, but also bring the structural diversity provided by organic molecules (Journal of Alloys and Compounds, 2024, 972.). Therefore, the synthesis of environmentally friendly low-dimensional organic-inorganic hybrid metal halides and the study of their performance are of great significance for promoting the application of such materials in optoelectronic devices and other fields.

[0005] As a substitute for lead-based metal halide luminescent materials, researchers face many unknown challenges in preparing organic-inorganic hybrid metal halide materials with better performance, mainly the following issues:

[0006] 1. Mn2+ The luminescence research of ions is still controversial because of its complex mechanism. 2+ -Mn 2+ The magnetic coupling related to the optical distance, known as spin-spin correlation (Materials Today Chemistry 2024, 38.), is difficult to discuss in organic-inorganic hybrid metal halides containing relatively large organic molecules, and its luminescence mechanism still needs further research and exploration to better understand the optical properties of the materials.

[0007] 2. The growth environment of organic-inorganic hybrid metal halides needs to be dry and stable, which is conducive to the growth of large, high-quality crystals and has a positive effect on improving performance. Regulating the growth quality of crystals is still the goal to be pursued.

[0008] 3. Growing crystals with high phase transition temperature remains a pressing issue. Summary of the invention

[0009] Based on this, the main purpose of the present invention is to provide an organic-inorganic hybrid manganese-based halide crystal, which has fluorescent properties and the ability to emit green light under ultraviolet light. It is a new type of single-molecule crystal with flexible structure, small molecular weight and excellent thermal stability.

[0010] Another object of the present invention is to provide a method for preparing the organic-inorganic hybrid manganese-based halide crystals, selecting isoquinoline as an organic cation source and manganese bromide metal salt as a metal ligand, and adopting a room temperature slow evaporation method to prepare a new type of halide crystal with flexible structure, small molecular weight and excellent performance. The synthesis process is simple and environmentally friendly.

[0011] Another object of the present invention is to provide an application of the organic-inorganic hybrid manganese-based halide crystal in a photoluminescent device. 2+ Ion aggregation, structural distortion and Mn 2+ -Mn 2+ The spacing between the two electrodes can cause the photoluminescence properties of the corresponding material to change, thereby obtaining photoluminescence of a specific frequency or enhancing its intensity.

[0012] To achieve the above object, the present invention adopts the following technical solution:

[0013] In a first aspect of the present invention, there is provided an organic-inorganic hybrid manganese-based halide crystal having a molecular formula of IQ 2 MnB 4 , wherein IQ is isoquinolinyl, that is, the molecular formula is (C 9 H 7 N) 2 MnB 4 .

[0014] Preferably, the organic-inorganic hybrid manganese-based halide crystal has a reversible crystal phase transition characteristic and can be converted between centrosymmetric and non-centrosymmetric structures.

[0015] Preferably, the organic-inorganic hybrid manganese-based halide crystal has a photoluminescence effect and emits green fluorescence under 365nm ultraviolet irradiation.

[0016] The second aspect of the present invention provides a method for preparing the organic-inorganic hybrid manganese-based halide crystal, using isoquinoline as an organic cation source and manganese bromide tetrahydrate as a manganese metal ligand, and preparing the crystal by slow evaporation at room temperature, comprising the following steps:

[0017] S1, dissolving the organic cation source in a medium solvent to obtain an organic solution;

[0018] S2, dissolving the manganese metal ligand in hydrobromic acid to obtain an acid solution;

[0019] S3, mixing the organic solution and the acid solution to obtain a light green mixed solution;

[0020] S4, placing the mixed solution in a volatile solvent, and observing small crystals, thereby obtaining organic-inorganic hybrid manganese-based halide crystals.

[0021] Preferably, in step S1, the medium solvent is deionized water, and the molar volume ratio of isoquinoline to deionized water is 2 mmol:3 mL.

[0022] Preferably, in step S2, the molar ratio of the manganese bromide tetrahydrate to hydrobromic acid is 1:2.

[0023] Preferably, step S4 further includes the steps of separating, drying and collecting the light green block crystals into the target product.

[0024] The third aspect of the present invention provides the use of the organic-inorganic hybrid manganese-based halide crystal in a photoluminescent device.

[0025] The photoluminescence mechanism of manganese-based halide crystals involves a complex energy transfer process. 2+ As the luminescence center, it plays a vital role in the whole process. Under the magnetic coupling effect, Mn 2+ Ion aggregation, structural distortion and Mn 2+ -Mn 2+ The distance between them can cause the photoluminescence properties of the corresponding materials to change (Materials Today Chemistry 2024, 38.), and Mn 2+ -Mn 2+Different positions and bond angles also show different magnetic couplings. Studying its properties makes Mn 2+ Manganese-based halide crystals have high application potential in photoluminescent materials by generating specific wavelengths to obtain photoluminescence of specific frequencies or enhance their intensity.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention proposes an organic-inorganic hybrid manganese-based halide crystal, wherein isoquinoline is selected as an organic cation source and manganese bromide metal salt is selected as a metal ligand. The nitrogen atom in the molecular structure of isoquinoline contains arc pairs of electrons and has a strong coordination ability, which can react with MnBr 4 The manganese ions in the metal form a stable complex structure. At the same time, due to the metallic properties of manganese and its ability to adapt to a variety of coordination environments, a new type of single-molecule crystal with flexible structure, small molecular weight and excellent thermal stability was successfully prepared.

[0028] 2. The present invention adopts a slow evaporation method at room temperature to prepare single crystals, which requires simple and mild experimental conditions, relatively stable crystal growth, and a moderate growth rate, which is conducive to the preparation of high-quality, uniformly composed organic-inorganic hybrid manganese-based halide single crystals.

[0029] 3. The organic-inorganic hybrid manganese-based halide crystals of the present invention can emit green light and have high application potential in photoluminescent devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The product obtained in the example (C 9 H 7 N) 2 MnB 4 Single crystal X-ray diffraction (SC-XRD) test results of the crystal, left: crystal structure (223K); right: crystal structure (293K).

[0031] Figure 2 The product obtained in the example (C 9 H 7 N) 2 MnB 4 Thermogravimetric analysis (TGA) results of crystals.

[0032] Figure 3 The product obtained in the example (C 9 H 7 N) 2 MnB 4 Differential scanning calorimetry (DSC) results of the crystals.

[0033] Figure 4 The product obtained in the example (C9 H 7 N) 2 MnB 4 Fluorescence image of the crystal under 365nm ultraviolet light. DETAILED DESCRIPTION

[0034] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] Unless otherwise specified, the reagents used in the following examples are all commercially available reagents, and the detection means and methods used are all conventional technical means and methods in the art unless otherwise specified.

[0036] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0037] Example 1

[0038] (C 9 H 7 N) 2 MnB 4 Crystal preparation:

[0039] 2 mmol of isoquinoline was dissolved in 3 mL of deionized water to obtain an aqueous solution; 1 mmol of copper bromide tetrahydrate was dissolved in 2 mL of hydrobromic acid to obtain an acid solution; the aqueous solution and the acid solution were then fully mixed together to obtain a light green mixed solution; the mixed solution was placed in a fume hood at room temperature to evaporate slowly, and light green small crystals were observed after two weeks, indicating that single crystals of the target product had been obtained, and the target product was continuously collected by separation and drying.

[0040] The above-obtained product was subjected to characterization performance tests, and the results are as follows:

[0041] Figure 1 For (C 9 H 7 N) 2 MnB 4 From the single crystal XRD test results of the crystal, it can be seen that the isoquinoline group interacts with the tetrahedron through hydrogen bonds to form a polyhedral model unit cell. Figure 1 As shown on the left, at 223K, the crystal crystallized in the monoclinic noncentrosymmetric space group of Cc, with unit cell parameters a = 12.2233 (2), b = 9.9500 (2), c = 19.32790 (4), α = γ = 90°, β = 102.060° (1), Br - Ions and Mn 2+ The average bond length of ions is 2.4882(4), Br - The average bond angle of the ions is 110.048°(16).

[0042] like Figure 1As shown on the right, at 293K, the crystals crystallized in the monoclinic centrosymmetric space group of C2 / c, with unit cell parameters a=12.2820(3), b=10.0130(3), c=19.3680(5), α=γ=90°, β=101.688(13), Br - Ions and Mn 2+ The average bond length of ions is 2.4892(10), Br - The average bond angle of the ions is 110.080°(3).

[0043] Figure 1 The XRD test results show that (C 9 H 7 N) 2 MnB 4 The structural changes of crystals at different temperatures are mainly manifested in slight adjustments in symmetry, unit cell parameters and metal-halogen bonding relationships. This temperature-induced phase transition process and crystal structure change may be related to hydrogen bonds, metal-halogen interactions and the effect of temperature on the crystal lattice.

[0044] The pyrolysis process was studied by TGA and DTG. Figure 2 As shown, (C 9 H 7 N) 2 MnB 4 The crystals begin to lose weight at around 358K, and the water molecules in the crystals begin to disappear; at around 450K, the halide crystals begin to dissolve, and the rapid drop in the DTG curve at 358K and 450K can also confirm these two points.

[0045] Depend on Figure 3 C 9 H 7 N) 2 MnB 4 The DSC graph of the crystal shows that the crystal undergoes phase transition during the heating and cooling process. When heated, the crystal changes from a non-centrosymmetric structure to a centrosymmetric structure at about 278K; and when cooled, the crystal changes from a centrosymmetric structure to a non-centrosymmetric structure at 238K. The Jan-Taylor distortion may affect the symmetry of the crystal through the deformation of the local structure in this phase transition, resulting in a change in structure. The substance has a reversible crystal phase transition characteristic, and this change is a mutual conversion between centrosymmetric and non-centrosymmetric structures.

[0046] Depend on Figure 4 Middle (C 9 H 7 N) 2 MnB 4 The fluorescence reaction diagram of the crystal under 365nm ultraviolet light shows that (C 9 H7 N) 2 MnB 4 The crystal has a photoluminescence effect and emits green fluorescence under 365nm ultraviolet light.

[0047] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An organic-inorganic hybrid manganese-based halide crystal, the molecular formula of which is IQ2MnBr4, wherein IQ is isoquinoline, that is, the molecular formula is (C9H7N)2MnBr4.

2. The organic-inorganic hybrid manganese-based halide crystal according to claim 1, characterized in that: The organic-inorganic hybrid manganese-based halide crystal has a reversible crystal phase transition characteristic and can be mutually converted between a centrosymmetric structure and a non-centrosymmetric structure.

3. The organic-inorganic hybrid manganese-based halide crystal according to claim 1, characterized in that: The organic-inorganic hybrid manganese-based halide crystal has a photoluminescence effect and emits green fluorescence under 365nm ultraviolet irradiation.

4. The method for preparing the organic-inorganic hybrid manganese-based halide crystal according to any one of claims 1 to 3, characterized in that: The method uses isoquinoline as an organic cation and manganese bromide tetrahydrate as a manganese metal ligand, and is prepared by a slow evaporation method at room temperature, comprising the following steps: S1, dissolving the organic cation source in a medium solvent to obtain an organic solution; S2, dissolving the manganese metal ligand in hydrobromic acid to obtain an acid solution; S3, the organic solution and the acid solution are mixed to obtain a light green mixed solution; S4. The mixed solution is placed in a volatile solvent, and small crystals are observed, thereby obtaining organic-inorganic hybrid manganese-based halide crystals.

5. The method for preparing the organic-inorganic hybrid manganese-based halide crystal according to claim 4, characterized in that: In step S1, the medium solvent is deionized water, and the molar volume ratio of isoquinoline to deionized water is 2 mmol:3 mL.

6. The method for preparing the organic-inorganic hybrid manganese-based halide crystal according to claim 4, characterized in that: In step S2, the molar ratio of the manganese bromide tetrahydrate to hydrobromic acid is 1:

2.

7. The method for preparing the organic-inorganic hybrid manganese-based halide crystal according to claim 4, characterized in that: Step S4 also includes the steps of separating, drying and collecting the target product from the light green block crystals.

8. Use of the organic-inorganic hybrid manganese-based halide crystal according to any one of claims 1 to 3 in a photoluminescent device.

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