A Manganese-Based Pyridine Fluorescent Crystal Material, Preparation Method and Application

Abstract

The present invention belongs to the technical field of fluorescent crystal materials, and discloses a manganese-based pyridine fluorescent crystal material, a preparation method and an application. At room temperature, MnCl2·4H2O, 2-dimethylaminopyridine, and 4-dimethylaminopyridine are used as raw materials, and water, methanol, acetonitrile, etc. are used as solvents; the solvent evaporation method is adopted to synthesize 4 examples of manganese-based pyridine organic-inorganic hybrid compounds; the properties of compounds 1-4 are systematically detected by methods such as infrared testing, X-single crystal diffraction, thermogravimetric analysis, dielectric testing, and fluorescence testing. Compounds 1-3 all belong to the monoclinic system, and the space group is C2 / c. Compounds 2-4 all belong to the triclinic system, and the space group is P-1. Compounds 1-4 all start to decompose at about 376K, proving to have good thermal stability. In the temperature-rising dielectric test, compounds 1-4 start to show dielectric anomalies at 220K, 220K, 220K, and 237K respectively.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluorescent crystal materials, and particularly relates to a manganese-based pyridine fluorescent crystal material, a preparation method and an application thereof. Background Technique

[0002] At present, transition metal halide-based organic-inorganic hybrid fluorescent crystal materials have the characteristics of simple synthesis and no energy consumption. In terms of structure, the fluorescence properties of the materials are regulated by changing the types and coordination numbers of small molecule nitrogen-containing organisms and transition metals. Among them, organic amine cations will respond to external stimuli and undergo structural phase changes, enabling such materials to exhibit optoelectronic and other multifunctional properties, and having broad application prospects in the fields of photoelectric conversion, switches, flexible wearable devices, etc.

[0003] The dielectric anomaly-fluorescent crystal material synthesized from manganese halide and organisms breaks the limitations and singularity of the synthesis of traditional fluorescent materials, and at the same time promotes the application of organic-inorganic hybrid materials in the fields of optoelectronics and photoluminescence. The outermost electrons of metallic manganese are 3d 5 4s 2 It is easy to generate electronic transitions through hydrogen bond assembly with organisms, resulting in the fluorescence properties of the materials. The achievements of many scientific researchers at home and abroad show that in most cases, manganese ligands with a coordination number of six emit red light under ultraviolet light irradiation, and manganese ligands with a coordination number of four emit green light.

[0004] Through the above analysis, the problems and defects existing in the prior art are: in the prior art, the outermost electrons of metallic manganese are 3d 5 4s 2 It is easy to generate electronic transitions through hydrogen bond assembly with organisms, resulting in the fluorescence properties of the materials.

[0005] Now, more metallic manganese materials produce fluorescence properties mainly by forming coordination sites through oxygen atoms, nitrogen atoms, carbon atoms, etc. in organic ligands. Such materials need to be synthesized under high temperature and high pressure, and the required conditions are relatively harsh, belonging to a high-energy-consuming synthesis method. Especially, the subsequent treatment of the materials is difficult and heavy metal pollution is likely to occur. And the functions of metallic manganese materials are relatively single, mainly fluorescence-based, while the development of multifunctional properties is weak.

[0006] The difficulty in solving the above problems and defects is: Most of the currently synthesized metallic manganese fluorescent materials are synthesized under high temperature and high pressure conditions, belonging to high-energy-consuming materials. Especially, the yield in the synthesis process is low, and the subsequent treatment of the synthesis solution and materials is difficult, with a strong potential risk of environmental pollution.

[0007] The significance of solving the above problems and defects is as follows: This patent aims at the defects of current metal manganese complex fluorescent materials and provides a synthesis method at room temperature. By means of small ligands, four manganese-based pyridine application-type crystal materials are synthesized under normal temperature and pressure conditions through slow evaporation of the solvent. The synthesis conditions of this material are simple, it belongs to a low-energy-consuming fluorescent material, has a high yield, is easy to process, and there is no environmental pollution problem. At the same time, this metal manganese fluorescent material has multiple functions, especially has dielectric properties, and is a new type of photoluminescence-dielectric anomaly functional material. Summary of the Invention

[0008] In view of the problems existing in the prior art, the present invention provides a preparation method and application of a manganese-based pyridine fluorescent crystal material.

[0009] The present invention is realized as follows. A preparation method of a manganese-based pyridine fluorescent crystal material, the preparation method of the manganese-based pyridine fluorescent crystal material, the specific process is as follows:

[0010] Step 1, at room temperature, select MnCl2·4H2O, 2-dimethylaminopyridine, and 4-dimethylaminopyridine as raw materials, and water, methanol, acetonitrile, etc. as solvents;

[0011] Step 2, adopt the solvent evaporation method to synthesize 4 examples of manganese-based pyridine organic-inorganic hybrid compounds;

[0012] Step 3, systematically detect the properties of Compounds 1-4 by methods such as infrared testing, X-single crystal diffraction, thermogravimetric analysis, dielectric testing, and fluorescence testing.

[0013] Further, in the above Step 2, the 4 examples of manganese-based pyridine organic-inorganic hybrid compounds are respectively:

[0014] Compound 1 is: [(C7H 11 N2) + 2][(MnCl4) 2- , Compound 2 is: [(C7H 11 N2) + 2][(MnCl4) 2- , Compound 3: [(C7H 11 N2) + 2][(MnBr4) 2- , Compound 4, [(C7H 11 N2) + 2][(MnBr4) 2- .

[0015] Further, the above Compound 1 [(C7H 11 N2) + 2][(MnCl4) 2- is synthesized by the solvent evaporation method:

[0016] Using MnCl2·4H2O and 2-dimethylaminopyridine (DMAP) as raw materials, react in a mixed solution at a molar ratio of 1:2. Weigh 0.600 g (3.030 mmol) of manganese chloride and dissolve it in 2.0 mL of distilled water. After complete dissolution, add 1 mL of hydrochloric acid, let it stand for 20 min, and then add 15.0 mL of acetonitrile solution for use. Weigh another 0.185 g (1.514 mmol) of 2-dimethylaminopyridine and dissolve it in 10.0 mL of acetonitrile.

[0017] Slowly drip the prepared manganese chloride mixed solution into the 2-dimethylaminopyridine solution, place it in a cool and ventilated place to stand, and slowly evaporate. After 20 days, a light green block crystal compound one is obtained.

[0018] Furthermore, the manganese chloride is 0.600 g (3.030 mmol); the 2-dimethylaminopyridine is 0.185 g (1.514 mmol).

[0019] Furthermore, the compound two [(C7H 11 N2) + 2][(MnCl4) 2- is synthesized by the solvent evaporation method:

[0020] Using MnCl2·4H2O and 4-dimethylaminopyridine as raw materials, react in a mixed solution at a molar ratio of 1:1. Weigh 0.600 g (3.030 mmol) of manganese chloride and dissolve it in 2.0 mL of distilled water. After complete dissolution, add 1 mL of hydrochloric acid, let it stand for 20 min, and then add 15.0 mL of methanol solution for use. Weigh another 0.369 g (3.020 mmol) of 4-dimethylaminopyridine and dissolve it in 10.0 mL of methanol.

[0021] Slowly drip the above-prepared manganese chloride mixed solution into the 4-dimethylaminopyridine solution, place it in a cool and ventilated place to stand, and after 15 days, a light green block crystal compound two is obtained.

[0022] Furthermore, the manganese chloride is 0.600 g (3.030 mmol), and the 4-dimethylaminopyridine is 0.369 g (3.020 mmol).

[0023] Furthermore, the compound three [(C7H 11 N2) + 2][(MnBr4) 2-Synthesis by solvent evaporation method: Using MnCl2·4H2O and 2-dimethylaminopyridine (DMAP) as raw materials, reacting in a mixed solution with a molar ratio of 2:2. Weigh 0.399 g (2.976 mmol) of manganese chloride and dissolve it in 3.0 mL of distilled water. After complete dissolution, add 1.0 mL of hydrobromic acid, heat it in a constant temperature water bath at 80 °C for 10 min, then add 10 mL of acetonitrile solution. Weigh another 0.388 g (3.176 mmol) of 2-dimethylaminopyridine and dissolve it in 10.0 mL of acetonitrile. Slowly drop the above-prepared manganese chloride mixed solution into the 2-dimethylaminopyridine solution, place it in a cool and well-ventilated place to stand still. Through the slow evaporation of the mixed solution, a light green block crystal compound III is obtained after 5 days.

[0024] Furthermore, the manganese chloride is 0.399 g (2.976 mmol), and the 2-dimethylaminopyridine is 0.388 g (3.176 mmol).

[0025] Furthermore, the compound IV [(C7H 11 N2) + 2][(MnBr4) 2- Synthesis by solvent evaporation method:

[0026] Using MnCl2·4H2O and 4-dimethylaminopyridine as raw materials, reacting in a mixed solution with a molar ratio of 3:2. Weigh 0.600 g (4.476 mmol) of manganese chloride and dissolve it in 2.0 mL of distilled water. After complete dissolution, add 1.0 mL of hydrobromic acid, heat it in a constant temperature water bath at 80 °C for 10 min, then add 15 mL of methanol solution. Weigh another 0.365 g (2.988 mmol) of 4-dimethylaminopyridine and dissolve it in 10.0 mL of methanol.

[0027] Slowly drop the above-prepared manganese chloride mixed solution into the 4-dimethylaminopyridine solution, place it in a cool and well-ventilated place to stand still. A light green block crystal compound IV is obtained after 15 days.

[0028] Furthermore, the manganese chloride is 0.600 g (4.476 mmol), and the 4-dimethylaminopyridine is 0.365 g (2.988 mmol).

[0029] Another object of the present invention is to provide a manganese-based pyridine fluorescent crystal material prepared by using the preparation method of the manganese-based pyridine fluorescent crystal material.

[0030] Another object of the present invention is to provide an application of the manganese-based pyridine fluorescent crystal material in promoting the preparation of organic-inorganic hybrid materials in the fields of optoelectronics and photoluminescence.

[0031] Combining all the above technical solutions, the advantages and positive effects possessed by the present invention are as follows:

[0032] The present invention has developed a synthesis method for a new type of metal manganese fluorescent material, and only needs to synthesize the fluorescent material under normal temperature and pressure conditions.

[0033] Regarding the current high-energy-consuming manganese metal fluorescent materials, especially the way of directly coordinating organic ligands with manganese metal, the technology of the present invention synthesizes a new type of manganese metal inorganic-organic hybrid fluorescent material with halogen ions as ligands under normal temperature and pressure. The synthesis of this material is simple, and the waste treatment is simple without causing secondary environmental pollution.

[0034] The technical solution of the present invention synthesizes a multifunctional material, which not only has good fluorescence performance but also has good dielectric performance, and is a new type of photoluminescence-dielectric anomaly functional material.

[0035] Compounds 1-3 all belong to the monoclinic system, and their space groups are all C2 / c. Compounds 2-4 all belong to the triclinic system, and their space groups are all P-1. Thermogravimetric test analysis shows that compounds 1-4 all start to decompose at about 376K, indicating that they have good thermal stability. In the temperature-rising dielectric test, compounds 1-4 start to show dielectric anomalies at 220K, 220K, 220K, and 237K respectively. Fluorescence spectrum test analysis shows that the maximum emission wavelengths of compounds 1-4 are 525nm, 530nm, 517nm, and 519nm respectively, and these compounds all emit green fluorescence under ultraviolet irradiation. The above analysis shows that compounds 1-4 are new types of photoluminescence-dielectric anomaly functional materials. Description of the Drawings

[0036] Figure 1 It is a flow chart of the preparation method of the manganese-based pyridine fluorescent crystal material provided by the embodiment of the present invention.

[0037] Figure 2 It is a schematic diagram of the synthesis of Compound 1 provided by the embodiment of the present invention.

[0038] Figure 3 It is a schematic diagram of the synthesis of Compound 2 provided by the embodiment of the present invention.

[0039] Figure 4 It is a schematic diagram of the synthesis of Compound 3 provided by the embodiment of the present invention.

[0040] Figure 5 It is a schematic diagram of the synthesis of Compound 4 provided by the embodiment of the present invention.

[0041] Figure 6 It is a combined infrared spectrum diagram of Compounds 1-4 provided by the embodiment of the present invention.

[0042] Figure 7 It is a schematic diagram of the powder diffraction pattern of Compounds 1-4 provided by the embodiment of the present invention.

[0043] Figure 7 In which: Figure a, Compound 1; Figure b, Compound 2; Figure c, Compound 3; Figure d, Compound 4.

[0044] Figure 8 It is a schematic diagram of the minimum asymmetric unit of the compound provided by the embodiment of the present invention.

[0045] Figure 8 Among them: Figure a, Compound 1; Figure b, Compound 2; Figure c, Compound 3; Figure d, Compound 4.

[0046] Figure 9 It is a packing diagram of the compound provided by the embodiment of the present invention.

[0047] Figure 9 Among them: Figure a, Compound 1; Figure b, Compound 2; Figure c, Compound 3; Figure d, Compound 4.

[0048] Figure 10 It is a thermogravimetric test chart of the compound provided by the embodiment of the present invention.

[0049] Figure 10 Among them: Figure a, Compound 1; Figure b, Compound 2; Figure c, Compound 3; Figure d, Compound 4.

[0050] Figure 11 It is a heating dielectric test chart of the compound provided by the embodiment of the present invention.

[0051] Figure 11 Among them: Figure a, Compound 1; Figure b, Compound 2; Figure c, Compound 3; Figure d, Compound 4.

[0052] Figure 12 It is a schematic fluorescence spectrum diagram of Compounds 1 to 4 provided by the embodiment of the present invention.

[0053] Figure 12 Among them: Figure a, Compound 1; Figure b, Compound 2; Figure c, Compound 3; Figure d, Compound 4. Detailed implementation manners

[0054] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0055] In view of the problems existing in the prior art, the present invention provides a preparation method of a manganese-based pyridine fluorescent crystal material, which will be described in detail below with reference to the accompanying drawings.

[0056] Those of ordinary skill in the art can also implement the preparation method of the manganese-based pyridine fluorescent crystal material provided by the present invention by using other steps. Figure 1 The preparation method of the manganese-based pyridine fluorescent crystal material provided by the present invention is only a specific embodiment.

[0057] As Figure 1 shown, the preparation method of the manganese-based pyridine fluorescent crystal material provided by the embodiment of the present invention specifically includes the following steps:

[0058] S101: At room temperature, MnCl2·4H2O, 2-dimethylaminopyridine, and 4-dimethylaminopyridine are selected as raw materials, and water, methanol, acetonitrile, etc. are used as solvents.

[0059] S102: Four manganese-based pyridine organic-inorganic hybrid compounds are synthesized by the solvent evaporation method.

[0060] S103: The properties of Compounds 1-4 are systematically detected by methods such as infrared testing, X-single crystal diffraction, thermogravimetric (TG) analysis, dielectric testing, and fluorescence testing.

[0061] In S102 provided by the embodiment of the present invention, the four manganese-based pyridine organic-inorganic hybrid compounds are respectively:

[0062] Compound 1 is: [(C7H 11 N2) + 2][(MnCl4) 2- , Compound 2 is: [(C7H 11 N2) + 2][(MnCl4) 2- , Compound 3 is: [(C7H 11 N2) + 2][(MnBr4) 2- , Compound 4 is: [(C7H 11 N2) + 2][(MnBr4) 2- .

[0063] Compound 1 [(C7H 11 N2) + 2][(MnCl4) 2- provided by the embodiment of the present invention is synthesized by the solvent evaporation method:

[0064] Using MnCl2·4H2O and 2-dimethylaminopyridine (DMAP) as raw materials, reacting in a mixed solution at a molar ratio of 1:2. Weigh 0.600 g (3.030 mmol) of manganese chloride and dissolve it in 2.0 mL of distilled water. After complete dissolution, add 1 mL of hydrochloric acid, let it stand for 20 min, and then add 15.0 mL of acetonitrile solution for use. Another 0.185 g (1.514 mmol) of 2-dimethylaminopyridine is weighed and dissolved in 10.0 mL of acetonitrile. The above-prepared manganese chloride mixed solution is slowly dropped into the 2-dimethylaminopyridine solution, placed in a cool, ventilated place and left to stand, and slowly evaporated. After 20 days, a light green block crystal, Compound 1, is obtained.

[0065] The compound bis[(C7H 11 N2) + 2][(MnCl4) 2- provided by the embodiment of the present invention is synthesized by the solvent evaporation method: Using MnCl2·4H2O and 4-dimethylaminopyridine as raw materials, reacting in a mixed solution with a molar ratio of 1:1. Weigh 0.600 g (3.030 mmol) of manganese chloride and dissolve it in 2.0 mL of distilled water. After complete dissolution, add 1 mL of hydrochloric acid, let it stand for 20 min, and then add 15.0 mL of methanol solution for use. Another 0.369 g (3.020 mmol) of 4-dimethylaminopyridine is weighed and dissolved in 10.0 mL of methanol. Slowly drop the above-prepared manganese chloride mixed solution into the 4-dimethylaminopyridine solution, place it in a cool and ventilated place to stand, and after 15 days, obtain the light green block crystal compound 2.

[0066] The compound tris[(C7H 11 N2) + 2][(MnBr4) 2- provided by the embodiment of the present invention is synthesized by the solvent evaporation method: Using MnCl2·4H2O and 2-dimethylaminopyridine (DMAP) as raw materials, reacting in a mixed solution with a molar ratio of 2:2. Weigh 0.399 g (2.976 mmol) of manganese chloride and dissolve it in 3.0 mL of distilled water. After complete dissolution, add 1.0 mL of hydrobromic acid, heat it in a constant temperature water bath at 80 °C for 10 min, then add 10 mL of acetonitrile solution. Another 0.388 g (3.176 mmol) of 2-dimethylaminopyridine is weighed and dissolved in 10.0 mL of acetonitrile. Slowly drop the above-prepared manganese chloride mixed solution into the 2-dimethylaminopyridine solution, place it in a cool and ventilated place to stand, and through the slow evaporation of the mixed solution, after 5 days, obtain the light green block crystal compound 3. The synthesis method is as Figure 4 .

[0067] The compound tetrakis[(C7H 11 N2) + 2][(MnBr4) 2- provided by the embodiment of the present invention is synthesized by the solvent evaporation method: Using MnCl2·4H2O and 4-dimethylaminopyridine as raw materials, reacting in a mixed solution with a molar ratio of 3:2. Weigh 0.600 g (4.476 mmol) of manganese chloride and dissolve it in 2.0 mL of distilled water. After complete dissolution, add 1.0 mL of hydrobromic acid, heat it in a constant temperature water bath at 80 °C for 10 min, then add 15 mL of methanol solution. Another 0.365 g (2.988 mmol) of 4-dimethylaminopyridine is weighed and dissolved in 10.0 mL of methanol. Slowly drop the above-prepared manganese chloride mixed solution into the 4-dimethylaminopyridine solution, place it in a cool and ventilated place to stand, and after 15 days, obtain the light green block crystal compound 4.

[0068] The technical solution of the present invention will be described in detail below in combination with experiments.

[0069] 1 Experimental part

[0070] 1.1 Instruments and reagents

[0071] Instruments: Nicolet Fourier transform infrared spectrometer (Thermo Fisher Scientific Inc., USA); X-ray single crystal diffractometer (Rigaku Corporation, Japan); X-ray powder diffractometer (Bruker Corporation, Germany); fluorescence tester (Bruker Corporation, Germany); Q 50 thermogravimetric analyzer (TA Instruments, USA); Tonghui TH 2828A precision LCR digital bridge (Changzhou Tonghui Electronics); electronic balance (Changzhou Ohaus Instruments Co., Ltd.).

[0072] Reagents: MnCl2·4H2O (commercially available analytical grade), 2-dimethylaminopyridine (TCI), 4-dimethylaminopyridine (TCI), hydrochloric acid (commercially available analytical grade), hydrobromic acid (commercially available analytical grade).

[0073] 1.2 Synthesis methods of compounds

[0074] Compound 1 was synthesized by the solvent evaporation method: Using MnCl2·4H2O and 2-dimethylaminopyridine (DMAP) as raw materials, reacting in a mixed solution at a molar ratio of 1:2. Weigh 0.600 g (3.030 mmol) of manganese chloride and dissolve it in 2.0 mL of distilled water. After complete dissolution, add 1 mL of hydrochloric acid, let it stand for 20 min, then add 15.0 mL of acetonitrile solution for use. Separately, weigh 0.185 g (1.514 mmol) of 2-dimethylaminopyridine and dissolve it in 10.0 mL of acetonitrile. Slowly drip the above-prepared manganese chloride mixed solution into the 2-dimethylaminopyridine solution, place it in a cool and well-ventilated place to stand, and slowly evaporate. After 20 days, a light green block crystal compound 1 was obtained. The synthesis method is as Figure 2 .

[0075] Compound 2 was synthesized by the solvent evaporation method: Using MnCl2·4H2O and 4-dimethylaminopyridine as raw materials, reacting in a mixed solution at a molar ratio of 1:1. Weigh 0.600 g (3.030 mmol) of manganese chloride and dissolve it in 2.0 mL of distilled water. After complete dissolution, add 1 mL of hydrochloric acid, let it stand for 20 min, then add 15.0 mL of methanol solution for use. Separately, weigh 0.369 g (3.020 mmol) of 4-dimethylaminopyridine and dissolve it in 10.0 mL of methanol. Slowly drip the above-prepared manganese chloride mixed solution into the 4-dimethylaminopyridine solution, place it in a cool and well-ventilated place to stand, and after 15 days, a light green block crystal compound 2 was obtained. The synthesis method is as Figure 3 .

[0076] Compound 3 was synthesized by the solvent evaporation method: Using MnCl2·4H2O and 2-dimethylaminopyridine (DMAP) as raw materials, reacting in a mixed solution with a molar ratio of 2:2. Weigh 0.399 g (2.976 mmol) of manganese chloride and dissolve it in 3.0 mL of distilled water. After complete dissolution, add 1.0 mL of hydrobromic acid, and heat it in a constant temperature water bath at 80 °C for 10 min. Then add 10 mL of acetonitrile solution. Weigh another 0.388 g (3.176 mmol) of 2-dimethylaminopyridine and dissolve it in 10.0 mL of acetonitrile. Slowly drip the prepared manganese chloride mixed solution into the 2-dimethylaminopyridine solution, and place it in a cool and well-ventilated place to stand still. Through the slow evaporation of the mixed solution, a light green block crystal compound 3 was obtained after 5 days. The synthesis method is as Figure 4 .

[0077] Compound 4 was synthesized by the solvent evaporation method: Using MnCl2·4H2O and 4-dimethylaminopyridine as raw materials, reacting in a mixed solution with a molar ratio of 3:2. Weigh 0.600 g (4.476 mmol) of manganese chloride and dissolve it in 2.0 mL of distilled water. After complete dissolution, add 1.0 mL of hydrobromic acid, and heat it in a constant temperature water bath at 80 °C for 10 min. Then add 15 mL of methanol solution. Weigh another 0.365 g (2.988 mmol) of 4-dimethylaminopyridine and dissolve it in 10.0 mL of methanol. Slowly drip the prepared manganese chloride mixed solution into the 4-dimethylaminopyridine solution, and place it in a cool and well-ventilated place to stand still. After 15 days, a light green block crystal compound 4 was obtained. The synthesis method is as Figure 5 .

[0078] 2 Results and Discussion

[0079] 2.1 Infrared Spectral Determination of Compounds 1 - 4

[0080] In the range of 4000 cm -1 -400 cm -1 , infrared tests were carried out on compounds 1 - 4 using KBr tablets dried at high temperature to preliminarily determine the main components of the compounds. As Figure 6 shown, through analysis, the attribution of each vibration peak is as follows: In compound 1, the characteristic peaks of the amino group are at 3235 cm -1 and 3131 cm -1 . The unsaturated C-H stretching vibration peak on the pyridine ring is at 3077 cm -1 . The saturated C-H stretching vibration peak on the methyl group is at 2977 cm -1 . The vibration peaks at 1649 cm -1 , 1611 cm -1 , 1546 cm -1 , and 1495 cm -1is the stretching vibration peak of the pyridine ring skeleton. It can be preliminarily inferred from the infrared spectrum that compound 1 contains 2-dimethylaminopyridine (DMAP). In compound 2, the range from 3670 cm -1 to 3308 cm -1 is the characteristic peak of N-H···Cl hydrogen bond. The peak at 3221 cm -1 is the stretching vibration peak of N-H of secondary amine. The peak at 3061 cm -1 is the stretching vibration peak of unsaturated C-H on the pyridine ring. The peak at 2962 cm -1 is the stretching vibration peak of saturated C-H on methyl. The peaks at 1651 cm -1 , 1566 cm -1 , 1441 cm -1 , 1402 cm -1 are the stretching vibration peaks of the pyridine ring skeleton. It can be preliminarily inferred from the figure that compound 2 contains 4-dimethylaminopyridine. In compound 3, the range from 3677 cm -1 to 3306 cm -1 is the characteristic peak of N-H···Br hydrogen bond. The peaks at 3141 cm -1 and 3240 cm -1 are the stretching vibration peaks of N-H of amino group. The peak at 2973 cm -1 is the stretching vibration peak of saturated C-H on methyl. The peaks at 1649 cm -1 , 1614 cm -1 , 1546 cm -1 , 1501 cm -1 are the stretching vibration peaks of the pyridine ring skeleton. It can be preliminarily inferred from the figure that compound 3 contains 2-dimethylaminopyridine (DMAP). In compound 4, the range from 3664 cm -1 to 3327 cm -1 is the characteristic peak of N-H···Br hydrogen bond. The peaks at 3224 cm -1 and 3133 cm -1 are the stretching vibration peaks of N-H of amino group. The peak at 2960 cm -1 is the stretching vibration peak of saturated C-H on methyl. The peaks at 1649 cm -1 , 1565 cm -1 , 1440 cm -1 , 1401 cm -1 are the stretching vibration peaks of the pyridine ring skeleton. It can be preliminarily inferred from the figure that compound 4 contains 4-dimethylaminopyridine.

[0081] 2.2 X-ray powder diffraction analysis of compounds 1-4

[0082] Select an appropriate amount of crystal materials with good crystal forms, conduct X-ray powder diffraction tests on compounds 1-4 in the angular range of 5° < 2θ < 50°, and draw comparative spectrograms using Origin8, as Figure 7 shown.Figure 7 The middle test values are the experimental data of the powder samples of Compounds 1-4 at a temperature of 293 K, while the fitted values are the XRD spectra of these compounds simulated at room temperature using Mercury 3.3 software. By comparing the two spectra, it is found that the peak positions and intensities of the experimental spectrum and the simulated spectrum are basically in agreement, proving that Compounds 1-4 are all single pure samples.

[0083] 2.3 Single Crystal Structure Analysis of Compounds 1-4

[0084] The test was carried out using a Bruker smart apexⅡ single crystal diffractometer with Mo-Kα (λ = 0.071073 nm) as the light source. Continuous structure tests were performed on the same single crystal sample at low temperature T = 100 K (LT) and room temperature T = 293 K (RT). All diffraction data were obtained through absorption correction. The single crystal structure was solved using the direct method and the continuous Fourier synthesis method. In the process of crystal structure analysis, the Patterson method and the direct method were used to determine the atomic positions. The hydrogen atom positions of water molecules were confirmed by means of electron clouds. The non-hydrogen atom coordinates and their anisotropic temperature factors were refined by full-matrix least-squares method. The anisotropic refinement of F was carried out using the SHELXTL-97 program. The structure data and refinement parameters of Compounds 1-4 are presented in Tables 1 and 2. 2 The anisotropic refinement was carried out. The structure data and refinement parameters of Compounds 1-4 are presented in Tables 1 and 2.

[0085] Table 1 Crystallographic Data of Compounds 1-2

[0086]

[0087]

[0088] Table 2 Crystallographic Data of Compounds 3-4

[0089]

[0090] At room temperature of 293 K, Compound 1 belongs to the monoclinic system, with the space group C2 / c and the unit cell parameters α = 90°, β = 102.43(9)°, γ = 90°. Compound 2 belongs to the triclinic system, with the space group P-1 and the unit cell parameters α = 100.444(8)°, β = 100.143(8)°, γ = 96.225(7)°. Compound 3 belongs to the monoclinic system, with the space group C2 / c and the unit cell parameters α = 90°, β = 102.459(10)°, γ = 90°. Compound 4 belongs to the triclinic system, with the space group P-1 and the unit cell parameters α = 95.406(12)°, β = 100.656(13)°, γ = 95.014(9)°.

[0091] There have been some reports and applications on recent functional materials of manganese complexes that can be used as fluorescent materials. More of the reported materials belong to stable metal complexes formed by the direct coordination of manganese with oxygen, nitrogen, carbon atoms, etc. of organic molecules. The synthesis of this type of manganese metal fluorescent material needs to be carried out under high temperature and high pressure conditions. Especially, the synthesis process belongs to a high-energy-consuming and high-risk synthesis method. Moreover, after the disposal of this type of material, it is difficult to degrade in the environment. Due to the direct coordination of manganese ions with organic molecules, it is difficult to degrade autonomously in the environment. And the function of the manganese complex fluorescent material is relatively single, and its multifunctional application is weak. According to the problems of difficult synthesis and high pollution of the current manganese complex fluorescent functional materials, the technical solution of the present invention innovatively explores according to the synthesis scheme of manganese complexes. First, the synthesis method adopts the method of slow solvent evaporation at normal temperature and pressure. Four ligands of manganese ions are replaced by halogen ions to form a tetrahedral structure of manganese ions with halogen ions as ligands ( Figure 8 ). The synthesis yield of this type of manganese metal fluorescent material is relatively high, the post-treatment after disposal is simple, and it is not easy to cause secondary pollution to the environment. Especially, while this material has good fluorescent properties, it has obvious dielectric properties and is a new type of photoluminescence-dielectric anomaly multifunctional material

[0092] As Figure 8 shown, the minimum asymmetric units of compounds 1-4 all contain two molecules of protonated pyridine derivative cations and one anionic manganese complex. The coordinating atoms of the manganese complex in compounds 1-2 are Cl, and the coordinating atoms of the manganese complex in compounds 3-4 are Br, all of which are distorted tetrahedral structures.

[0093] From Figure 9 it can be seen that 2-dimethylaminopyridine and 4-dimethylaminopyridine in compounds 1-4 are all embedded in the cavities of the manganese complex chain, and the protonated organic body and manganese halide are self-assembled into a molecular-based crystal material through hydrogen bond interaction.

[0094] 2.4 Thermogravimetric test of compounds 1-4

[0095] As Figure 10 shown, under the protection of flowing nitrogen, the thermal stability of compounds 1-4 was analyzed in the temperature range of 350K - 850K. Compound 1 started to decompose at 388K, compound 2 started to decompose at 417K, compound 3 started to decompose at 350K, and compound 4 started to decompose at 350K, indicating that compounds 1-4 have good thermal stability.

[0096] 2.5 Dielectric test of compounds 1-4

[0097] The dielectric properties of Compounds 1-4 were tested by powder pressing. They were fixed on a test stand with silver paste and copper wire for testing. The dielectric properties were tested on a pressed crystal capacitor using a TH2828A tester from Tonghui Company under the conditions of a frequency range of 500 Hz - 100 KHz and a temperature range of 160 K - 280 K. During the heating process, the dielectric constant decreased with the increase of the electric field frequency. As can be seen from Figure 11 , for Compound 1, the dielectric constant suddenly increased significantly at 220 K, reached the maximum value at 260 K and then decreased, showing an obvious dielectric anomaly peak. For Compound 2, the dielectric constant suddenly increased significantly at 220 K, reached the maximum value at 255 K and then decreased, showing an obvious λ-type dielectric anomaly peak. For Compound 3, the dielectric constant began to increase at 220 K, reached the maximum value at around 265 K and then decreased, showing an obvious dielectric anomaly peak. For Compound 4, the dielectric constant suddenly increased significantly at 237 K, showing an obvious dielectric anomaly peak. In summary, the maximum values of the dielectric constants of Compounds 3-4 are 10 times those of Compounds 1-2. Compounds 1-4 all exhibited dielectric anomalies at around 220 K and reached the maximum values at around 265 K.

[0098] 2.6 Fluorescence Tests of Compounds 1-4

[0099] The solid photoluminescence spectra of Compounds 1-4 were tested at room temperature. The test results are as shown in Figure 12 . When irradiated with an ultraviolet lamp, these compounds all emitted green fluorescence. Figure 12 The excitation spectra of Compounds 1-4 in g were the spectra obtained by testing at the monitoring wavelengths of 525 nm, 530 nm, 517 nm, and 519 nm respectively, and the emission spectra were the spectra obtained by testing at the optimal excitation wavelengths of 350 nm, 320 nm, 367 nm, and 321 nm respectively. The maximum emission wavelengths were 525 nm, 530 nm, 517 nm, and 519 nm respectively. In Compounds 1-4, the manganese ions are tetracoordinated. The outermost electrons in the manganese ions undergo transitions between the (e g ) 2 (t 2g ) 3 and (e g ) 1 (t 2g ) 4 energy levels, enabling the compounds to exhibit photoluminescence properties. Through comprehensive analysis of the structure and properties, it is shown that Compounds 1-4 are a new type of photoluminescence-dielectric anomaly functional material.

[0100] 3. Under room temperature conditions, the present invention selects MnCl2·4H2O, 2-dimethylaminopyridine, and 4-dimethylaminopyridine as raw materials, and water, methanol, acetonitrile, etc. as solvents, and synthesizes 4 examples of manganese-based pyridine organic-inorganic hybrid compounds by the solvent evaporation method. The properties of Compounds 1-4 are systematically studied by methods such as infrared testing, X-single crystal diffraction, thermogravimetric (TG) analysis, dielectric testing, and fluorescence testing. The following conclusions are obtained: Compounds 1-3 all belong to the monoclinic system, and the space group is C2 / c; Compounds 2-4 all belong to the triclinic system, and the space group is P-1. Thermogravimetric test analysis shows that Compounds 1-4 all start to decompose at about 376K, indicating that they have good thermal stability. In the temperature-rising dielectric test, Compounds 1-4 respectively show dielectric anomalies at 220K, 220K, 220K, and 237K. Fluorescence spectrum test analysis shows that the maximum emission wavelengths of Compounds 1-4 are 525nm, 530nm, 517nm, and 519nm respectively, and these compounds all emit green fluorescence under the irradiation of an ultraviolet lamp. The above analysis shows that Compounds 1-4 are novel photoluminescence-dielectric anomaly type functional materials.

[0101] According to the realistic conditions of high temperature, high pressure, and high energy consumption of existing metal manganese fluorescent materials, the technical solution of the present invention obtains a novel metal manganese fluorescent material by the slow evaporation of metal manganese ions and organic complexes at normal temperature and pressure. This material uses four halogen ions as ligands to form a tetrahedral structure, has good fluorescence as shown by its fluorescence properties, and at the same time has dielectric anomaly properties, proving that this compound is a novel photoluminescence-dielectric anomaly type multifunctional material.

[0102] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A manganese-based pyridine fluorescent crystal material, characterized in that, The manganese-based pyridine fluorescent crystal material is selected from Compound 1, Compound 2, Compound 3, and Compound 4; The structural formula of Compound 1 is as follows: Compound 1 belongs to the monoclinic system, with the space group C2 / c and the unit cell parameters α = 90°, β = 102.43(9)°, γ = 90°; The structural formula of Compound 2 is as follows: Compound 2 belongs to the triclinic system, with the space group P-1 and unit cell parameters α = 100.444(8)°, β = 100.143(8)°, γ = 96.225(7)°; The structural formula of Compound 3 is as follows: Compound 3 belongs to the monoclinic system, with the space group C2 / c and unit cell parameters α = 90°, β = 102.459(10)°, γ = 90°; The structural formula of Compound 4 is as follows: Compound 4 belongs to the triclinic system, with the space group P-1 and unit cell parameters α = 95.406(12)°, β = 100.656(13)°, γ = 95.014(9)°.

2. A method for preparing the manganese-based pyridine fluorescent crystal material according to claim 1, characterized in that, The said Compound 1 is synthesized by the solvent evaporation method: Using MnCl2·4H2O and 2-dimethylaminopyridine (DMAP) as raw materials, react in a mixed solution at a molar ratio of 1:

2. Weigh manganese chloride and dissolve it in 2.0 mL of distilled water. After complete dissolution, add 1 mL of hydrochloric acid, let it stand for 20 min, and then add 15.0 mL of acetonitrile solution for use. Weigh another 2-dimethylaminopyridine and dissolve it in 10.0 mL of acetonitrile; Slowly drip the prepared manganese chloride mixed solution into the 2-dimethylaminopyridine solution, place it in a cool and well-ventilated place to stand, and slowly evaporate. After 20 days, obtain light green block crystals of Compound 1.

3. The preparation method of the manganese-based pyridine fluorescent crystal material according to claim 2, characterized in that, The amount of manganese chloride is 0.600 g; the amount of 2-dimethylaminopyridine is 0.185 g.

4. A method for preparing the manganese-based pyridine fluorescent crystal material as described in claim 1, characterized in that, The compound 2 is synthesized by the solvent evaporation method: Using MnCl2·4H2O and 4-dimethylaminopyridine as raw materials, react in a mixed solution at a molar ratio of 1:

1. Weigh manganese chloride and dissolve it in 2.0 mL of distilled water. After complete dissolution, add 1 mL of hydrochloric acid, let it stand for 20 min, and then add 15.0 mL of methanol solution for use. Weigh another 4-dimethylaminopyridine and dissolve it in 10.0 mL of methanol; Slowly drip the above-prepared manganese chloride mixed solution into the 4-dimethylaminopyridine solution, place it in a cool and well-ventilated place to stand, and after 15 days, obtain light green block crystals of Compound 2.

5. The preparation method of the manganese-based pyridine fluorescent crystal material according to claim 4, characterized in that, The amount of manganese chloride is 0.600 g, and the amount of 4-dimethylaminopyridine is 0.369 g.

6. A preparation method of the manganese-based pyridine fluorescent crystal material as described in claim 1, characterized in that, The said compound 3 Synthesized by the solvent evaporation method: Using MnCl2·4H2O and 2-dimethylaminopyridine (DMAP) as raw materials, reacting in a mixed solution with a molar ratio of 2:

2. Weigh manganese chloride and dissolve it in 3.0 mL of distilled water. After complete dissolution, add 1.0 mL of hydrobromic acid, and heat it in a constant temperature water bath at 80 °C for 10 min. Then add 10 mL of acetonitrile solution. Weigh 2-dimethylaminopyridine and dissolve it in 10.0 mL of acetonitrile. Slowly drip the above-prepared manganese chloride mixed solution into the 2-dimethylaminopyridine solution, place it in a cool and well-ventilated place for static settlement. Through the slow evaporation of the mixed solution, a light green block crystal compound 3 is obtained after 5 days. The amount of manganese chloride is 0.399 g, and the amount of 2-dimethylaminopyridine is 0.388 g.

7. A preparation method of the manganese-based pyridine fluorescent crystal material as described in claim 1, characterized in that, The said Compound 4 is synthesized by the solvent evaporation method: Using MnCl2·4H2O and 4-dimethylaminopyridine as raw materials, react in a mixed solution at a molar ratio of 3:

2. Weigh manganese chloride and dissolve it in 2.0 mL of distilled water. After complete dissolution, add 1.0 mL of hydrobromic acid, heat it in a constant temperature water bath at 80 °C for 10 min, then add 15 mL of methanol solution. Weigh another 4-dimethylaminopyridine and dissolve it in 10.0 mL of methanol; Slowly drip the above-prepared manganese chloride mixed solution into the 4-dimethylaminopyridine solution, place it in a cool and well-ventilated place to stand, and after 15 days, obtain light green block crystals of Compound 4; The amount of manganese chloride is 0.600 g, and the amount of 4-dimethylaminopyridine is 0.365 g.

8. The application of the manganese-based pyridine fluorescent crystal material as described in Claim 1 in the preparation of organic-inorganic hybrid materials in the fields of optoelectronics and photoluminescence.

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