Indazole europium complex and application thereof

Abstract

The invention discloses an indazole europium complex and application thereof, and particularly relates to the field of rare earth complexes and luminescent materials. The general structural formula of the europium complex is Eu (IZ) xAyLm, IZ is an indazole-3-formic acid anion ligand, A is other anion ligands except IZ, and L is a neutral ligand; x is selected from 1 or 2 or 3 or 4, y is selected from 0 or 1 or 2, x + y = 3 or x + y = 4, and m is selected from 0 or 1 or 2; and the neutral ligand L is selected from a bidentate ligand containing pyridine, a tridentate ligand containing pyridine or a monodentate ligand containing phosphine. The europium complex provided by the invention has efficient photoluminescence efficiency, relatively high thermal stability and low cost, and effectively solves the problems existing in the prior art.

Description

Technical Field

[0001] The present invention relates to the field of rare earth complexes and luminescent materials, and particularly to an indazole-based europium complex and its application. Background Art

[0002] Rare earth luminescent materials have unique advantages such as high luminous efficiency, high color purity, and large Stokes shift, and have important application prospects in the fields of lighting, display, light conversion film, biomedicine, etc. For a long time, it has been one of the key directions of national scientific and technological development. Rare earth luminescent materials can be divided into inorganic luminescent materials and organic complex luminescent materials according to their composition. Compared with inorganic phosphors, rare earth complexes have a larger molar extinction coefficient and can exhibit very high luminous brightness at low concentrations or with very little usage. In addition, rare earth complexes also have good compatibility and can be incorporated into polymers to prepare highly transparent luminescent films, such as light conversion films for agriculture and light conversion films for solar cells, which have advantages that inorganic luminescent materials cannot match. However, in terms of stability, the stability of organic complex luminescent materials is slightly inferior. Finding a solution to overcome this major drawback in the research of organic complexes has always been the research focus and a huge challenge in this field.

[0003] Generally speaking, the research of organic ligands is the research of organic complexes. The ligand not only acts as an "antenna" to sensitize the excited metal ions to emit characteristic fluorescence, but also has to provide a compact and enclosed coordination environment to reduce luminescence quenching, such as solvent quenching. Common ligands include nitrogen-containing aromatic rings containing carboxylic acid or hydroxyl groups, bipyridine-based compounds, β-diketone-based compounds, etc. Among them, β-diketone-based compounds are often used as luminescence sensitizing ligands for lanthanide europium ions. After being sensitized by β-diketone-based ligands, europium metal emits orange-red light with high color purity and excellent luminous efficiency. Due to its good volatility, it is commonly used in the field of electroluminescence. However, the europium complexes formed by such ligands usually have poor photo-stability and thermal stability, such as being easily damaged by high-energy ultraviolet rays, which severely restricts the commercial application of its organic complex luminescent materials.

[0004] Therefore, at the present stage, developing rare earth organic luminescent materials with high luminous efficiency, high stability and low cost is a great challenge, and the research of ligands is an important breakthrough point. Summary of the Invention

[0005] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide an indazole-based europium complex and its application. The provided europium complex has high photoluminescence efficiency, high thermal stability and low cost, effectively solving the problems existing in the prior art.

[0006] In order to achieve the above purpose or other purposes, the present invention is realized by the following technical solutions.

[0007] An indazole-based europium complex with the general structural formula Eu(IZ) x A y L m , where IZ is an indazole-3-carboxylic acid-based anionic ligand, A is another anionic ligand other than IZ, and L is a neutral ligand; x is selected from 1, 2, 3, or 4, y is selected from 0, 1, or 2, and x + y = 3 or x + y = 4, and m is selected from 0, 1, or 2; the neutral ligand L is selected from a pyridine-containing bidentate ligand, a pyridine-containing tridentate ligand, or a phosphine-containing monodentate ligand;

[0008] The structural formula of IZ is shown in formula (a),

[0009]

[0010] The structural formula of the indazole-based europium complex is shown in Figure (Ⅰ),

[0011]

[0012] where R1, R2, R3, R4, and R5 are each independently selected from a hydrogen atom, a halogen atom, a cyano group, a straight-chain or branched-chain alkyl group having 1 to C 24 , a straight-chain or branched-chain halogen-substituted alkyl group having 1 to C 24 , and a straight-chain or branched-chain aryl-substituted alkyl group having 1 to C 24 .

[0013] In an example of the present invention, the neutral ligand L is selected from a phosphine-containing monodentate ligand: triphenylphosphine oxide or tri-n-octylphosphine oxide.

[0014] In an example of the present invention, the neutral ligand L is selected from a pyridine-containing bidentate ligand or a pyridine-containing tridentate ligand having the following structures:

[0015]

[0016] In an example of the present invention, A is a β-diketone ligand, and its structural formula is shown in formula (b),

[0017]

[0018] where R a , R b are each independently selected from an aryl group, a heteroaryl group, or a fluoroalkyl group.

[0019] In an example of the present invention, each aryl group is independently selected from a phenyl group or a naphthyl group;

[0020] Each heteroaryl group is independently selected from a thiophenyl group, a furyl group, or a pyridyl group;

[0021] Each fluoroalkyl group is independently selected from a trifluoromethyl group or a pentafluoroethyl group.

[0022] In an example of the present invention, the β-diketone ligand shown in the structural formula (b) is selected from any one of the following structures:

[0023]

[0024] In an example of the present invention, the indazole europium complex shown in the structural formula diagram (Ⅰ) is the europium complex shown in the general formula (Ⅱ),

[0025]

[0026] wherein x, y, m, A, and L are as described above.

[0027] In an example of the present invention, the indazole europium complex shown in the structural formula diagram (Ⅰ) is the europium complex shown in the general formula (Ⅲ),

[0028]

[0029] wherein x, y, m, A, and L are as described above.

[0030] In an example of the present invention, the indazole europium complex shown in the structural formula diagram (Ⅰ) is the europium complex shown in the general formula (IV),

[0031]

[0032] wherein x, y, m, A, and L are as described above.

[0033] In an example of the present invention, the indazole europium complex shown in the structural formula diagram (Ⅰ) is the europium complex shown in the general formula (V),

[0034]

[0035] wherein x, y, m, A, and L are as described above.

[0036] In an example of the present invention, the indazole europium complex shown in the structural formula diagram (Ⅰ) is the europium complex shown in the general formula (VI),

[0037]

[0038] wherein x, y, m, A, L, R2, R3, R4, and R5 are as described in any one of claims 1 to 3, and R6, R7, R8, and R9 are each independently selected from a hydrogen atom, a halogen atom, a cyano group, a C1-C 24 linear or branched substituted alkyl group, a C1-C 24 linear or branched halogen-substituted alkyl group.

[0039] In an example of the present invention, the indazole-based europium complex shown in Structural Formula Diagram (I) is the europium complex shown in General Formula (VII),

[0040]

[0041] wherein x, y, m, A, L, R2, R3, R4, R5 are as described in any one of Claims 1 to 3, and R 10 is selected from a hydroxyl group, a linear or branched substituted alkyl group having C1-C 24 a linear or branched halogen-substituted alkyl group having C1-C 24 an amino group, or a linear or branched alkoxy group having C1-C 24 .

[0042] In an example of the present invention, the indazole-based europium complex shown in Structural Formula Diagram (I) is the europium complex shown in General Formula (VIII),

[0043]

[0044] In an example of the present invention, the indazole-based europium complex shown in Structural Formula Diagram (I) is the europium complex shown in General Formula (IX),

[0045]

[0046] In an example of the present invention, the indazole-based europium complex shown in Structural Formula Diagram (I) is the europium complex shown in General Formula (X),

[0047]

[0048] In an example of the present invention, the indazole-based europium complex shown in Structural Formula Diagram (I) is the europium complex shown in General Formula (XI),

[0049]

[0050] In an example of the present invention, the indazole-based europium complex shown in Structural Formula Diagram (I) is the europium complex shown in General Formula (XII),

[0051]

[0052] On the other hand, the present invention also provides the application of the above indazole-based europium complex in the field of luminescent materials.

[0053] In the present invention, two kinds of anion ligands with excellent luminescent properties are used to coordinate with europium ions to synthesize a double-anion europium complex. One of the anions is a β-diketone ligand with excellent luminescent properties, and the other is an indazole carboxylic acid anion ligand. By utilizing the excellent thermal stability of the indazole carboxylic acid anion ligand and the π-π stacking interaction existing between indazole aromatic rings, it can interact with the β-diketone ligand with an aromatic ring and better exert the sensitization effect of both; moreover, the preparation method of the selected indazole carboxylic acid anion ligand is simple, easy to operate, easy to obtain and low in cost. The europium complex provided by the present invention has high photoluminescence efficiency, high thermal stability and low cost, effectively solving the problems existing in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 The crystal structure of the single crystal of the europium complex prepared in Example 3 of the present invention (hydrogen atoms are ignored for clarity): where Figure a) is the ball-and-stick diagram of the single crystal crystal structure of the europium complex prepared in Example 3 (hydrogen atoms are ignored); Figure b) labels each atom in Figure a).

[0055] Figure 2 The emission spectrum of the europium complex prepared in Example 3 of the present invention obtained at an excitation wavelength of 395 nm.

[0056] Figure 3 The excitation spectrum of the europium complex prepared in Example 3 of the present invention obtained at an emission wavelength of 618 nm.

[0057] Figure 4 The ultraviolet-visible absorption spectrum of the europium complex prepared in Example 3 of the present invention.

[0058] Figure 5 The infrared spectra of the europium complex prepared in Example 3 of the present invention, ligand TTA, and 1mIZ.

[0059] Figure 6 The infrared spectrum of the europium complex prepared in Example 6 of the present invention.

[0060] Figure 7 The ultraviolet-visible absorption spectrum of the europium complex prepared in Example 6 of the present invention.

[0061] Figure 8 The emission spectrum of the europium complex prepared in Example 6 of the present invention obtained at an excitation wavelength of 307 nm.

[0062] Figure 9 The excitation spectrum of the europium complex prepared in Example 6 of the present invention obtained at an emission wavelength of 616 nm. DETAILED DESCRIPTION OF THE INVENTION

[0063] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. It should also be understood that the terms used in the embodiments of the present invention are for describing specific implementation manners and are not intended to limit the protection scope of the present invention. The test methods without specific conditions noted in the following embodiments are generally carried out under conventional conditions or according to the conditions recommended by each manufacturer.

[0064] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of clear description and are not intended to limit the scope of implementation of the present invention. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope of implementation of the present invention.

[0065] In the specification and claims of the present application, compounds are named according to their chemical structural formulas. If there is a discrepancy between the naming of a compound and its chemical structural formula when representing the same compound, the chemical structure shall prevail.

[0066] In the present invention, unless otherwise specified, the scientific and technical terms used herein have the meanings commonly understood by those skilled in the art. However, for a better understanding of the present invention, the definitions of some terms are provided below. When the definitions and explanations of the terms provided by the present invention are inconsistent with the meanings commonly understood by those skilled in the art, the definitions and explanations provided by the present invention shall prevail.

[0067] As used herein, "halogen" refers to a fluorine atom, a chlorine atom, a bromine atom or an iodine atom.

[0068] As used herein, "optionally substituted" means two situations where one or more atoms on the substituent can be "substituted" or "not substituted" by one or more substituents.

[0069] In the present invention, "-----" are each independently selected from a single bond or a double bond, and two adjacent "-----" are not both double bonds at the same time.

[0070] In the present invention, C1-C 24 The straight-chain or branched-chain alkyl group refers to a straight-chain or branched-chain alkyl group containing 1-24 carbon atoms, including C1-C 10 The straight-chain or branched-chain alkyl group, the straight-chain or branched-chain alkyl group of C1-C5, the straight-chain or branched-chain alkyl group of C1-C6, C1-C 20 The straight-chain or branched-chain alkyl group, C5-C24 linear or branched alkyl groups having from C1 to C 24 linear or branched alkyl groups having from C1 to C, etc. The above-mentioned "linear or branched alkyl groups having from C1 to C 10 linear or branched alkyl groups having from C1 to C" refers to specific examples of linear or branched alkyl groups having from C1 to C 10 and having from 1 to 10 carbon atoms. Specific examples include, but are not limited to: methyl, ethyl, n-propyl (propyl), isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, 2-methylbutyl, neopentyl, 1-ethylpropyl, n-hexyl, isohexyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,3-dimethylbutyl, 2-ethylbutyl, 1,2-dimethylpropyl, etc.

[0071] In the present invention, the linear or branched halogen-substituted alkyl groups having from C1 to C 24 refers to those in which one or more hydrogens in the linear or branched alkyl groups having from C1 to C 24 are replaced by one or more halogens. The "linear or branched alkyl groups having from C1 to C 24 " is as defined above.

[0072] In the present invention, the linear or branched aryl-substituted alkyl groups having from C1 to C 24 refers to those in which one or more hydrogens in the linear or branched alkyl groups having from C1 to C 24 are replaced by one or more aryl groups. The "linear or branched alkyl groups having from C1 to C 24 " is as defined above.

[0073] In the present invention, aryl groups include monocyclic aryl groups and polycyclic aryl groups. Monocyclic aryl groups include, but are not limited to, phenyl, tolyl, etc., preferably phenyl. Polycyclic aryl groups refer to cyclic groups containing two or more benzene rings, and these benzene rings are fused together by sharing two adjacent carbon atoms. Polycyclic aryl groups include, but are not limited to, naphthyl.

[0074] In the present invention, the heteroaryl includes "5- to 8-membered monocyclic heteroaryl" and "8- to 10-membered fused heteroaryl". The "5- to 8-membered monocyclic heteroaryl" in the present invention refers to a monocyclic ring group with aromaticity containing 5 to 8 ring atoms (wherein at least one (e.g., 1, 2, 3, 4 or 5) ring atoms are heteroatoms, such as nitrogen atom, oxygen atom or sulfur atom). Optionally, the ring atoms (such as carbon atom, nitrogen atom or sulfur atom) in the ring structure can be oxo-substituted. The "5- to 8-membered monocyclic heteroaryl" includes, for example, "5- to 7-membered monocyclic heteroaryl", "5- to 6-membered monocyclic heteroaryl", "5- to 6-membered nitrogen-containing monocyclic heteroaryl", "6-membered nitrogen-containing monocyclic heteroaryl", etc. The heteroatoms in the "nitrogen-containing heteroaryl" contain at least one (e.g., 1, 2, 3, 4 or 5) nitrogen atoms. For example, it contains only 1 or 2 nitrogen atoms, or contains one nitrogen atom and 1 or 2 other heteroatoms (such as oxygen atom and / or sulfur atom), or contains 2 nitrogen atoms and 1 or 2 other heteroatoms (such as oxygen atom and / or sulfur atom). Specific examples of the "5- to 8-membered monocyclic heteroaryl" include but are not limited to furyl, thienyl, pyrrolyl, etc. The "8- to 10-membered fused heteroaryl" in the present invention refers to an unsaturated aromatic cyclic structure formed by two or more cyclic structures sharing two adjacent atoms with each other and containing 8 to 10 ring atoms (wherein at least one (e.g., 1, 2, 3, 4 or 5) ring atoms are heteroatoms, such as nitrogen atom, oxygen atom or sulfur atom).

[0075] In the present invention, the fluoroalkyl refers to that one or more hydrogens in the alkyl are respectively replaced by one or more fluorines. Specific examples include but are not limited to trifluoromethyl, pentafluoroethyl, etc.

[0076] In the present invention, the C1-C 24 linear or branched alkoxy refers to "C1-C 24 linear or branched substituted alkyl - O -".

[0077] The technical solutions of the present invention will be described in detail below through several specific examples and comparative examples. Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available products or can be prepared by conventional methods in the art. Unless otherwise specified in the examples of the present invention, the detection methods used are conventional detection methods in the industry. The preparation methods adopted in the present invention are conventional methods in the art.

[0078] Example 1

[0079] The synthetic route involved in this example is shown as follows:

[0080]

[0081] (1) Preparation of europium complex Eu(1mIZ)3phen:

[0082] Synthesis of 3-methylindazole

[0083] In 100 mL of ethanol, add 16.9 g (260 mmol) of hydrazine hydrate, heat to 70 °C, and slowly add 30 g (254 mmol) of o-hydroxyacetophenone dropwise over 40 - 60 minutes. After dropping, react at the same temperature for 1 h, cool to 50 °C, and add 31.6 g (260 mmol) of 30% hydrochloric acid dropwise. After the addition is complete, heat to reflux for 2 h, cool to 10 °C, filter by suction, wash with water, and dry. 28.3 g of yellow crystals are obtained with a yield of 97%.

[0084] Synthesis of indazole-3-carboxylic acid

[0085] In 100 mL of water, add 10 g (76 mmol) of 3-methylindazole, heat to 70 °C, and then add 26.4 g (167 mmol) of potassium permanganate in portions, stir for 2 h. After the color has completely faded, filter while hot, wash the filter cake with hot water, pour the mother liquor into a 500 mL three-necked flask, add 10 g of 30% hydrochloric acid, adjust the pH to about 2, and cool to 5 °C. Filter to obtain 14.28 g of crude indazole-3-carboxylic acid, and recrystallize with 30 mL of ethanol to obtain 10.58 g of pure product with a yield of 86%.

[0086] Synthesis of 1-methylindazole-3-carboxylic acid (can also be purchased commercially directly)

[0087] In 100 mL of ethanol, add 20 g (123 mmol) of dimethyl sulfate, slowly add 31.0 g (246 mmol) of dimethyl sulfate dropwise, add 20 g (250 mmol) of 50% sodium hydroxide solution, heat to reflux for 2.5 h, and stop the reaction when no raw materials are detected by TLC. Distill off the ethanol, cool to room temperature, adjust the pH to 2 with hydrochloric acid, cool to 5 °C, filter by suction to obtain 23.5 g of crude product, recrystallize with ethanol to obtain a yellow crystalline powder, and after vacuum drying, obtain 19.3 g (HPLC: 99.6%) with a yield of 88.9%. Take the product for 1H NMR detection, and the results are as follows: 1 1H NMR (CDCl3): 12.8 (s, -COOH), 7.5 (m, ArH), 4.2 (s, -CH).

[0088] Preparation of europium complex Eu(1mIZ)3phen

[0089] In 100 mL of methanol, 2 g (11.36 mmol) of 1-methylindazole-3-carboxylic acid, 2.05 g (11.36 mmol) of o-phenanthroline, and 0.91 g (11.36 mmol) of sodium hydroxide were added. After ultrasonic oscillation, the mixture was refluxed and stirred for 15 mins. Then, a solution of europium salt (2.09 g, 5.68 mmol) dissolved in methanol was slowly added dropwise. The mixture was refluxed and stirred for 1 h. After the reaction was completed, the magnetic stirrer was removed, and the reaction solution was evaporated to dryness. Dichloromethane was added and stirred for 15 mins. The mixture was filtered to obtain a clear filtrate, which was then evaporated to dryness to obtain 3.7 g of europium complex product (Eu(1mIZ)3phen) with a yield of 83%.

[0090] The europium complex product (Eu(1mIZ)3phen) was subjected to mass spectrometry: MS (m / z, ESI): calcd for C 39 H 29 EuN8NaO6 881.1320, found 881.1298; EA for C 39 H 29 EuN8O6 C 54.62; H 3.41; N 13.07 Found C 54.59; H 3.38; N 13.10.

[0091] Example 2

[0092] The synthetic route involved in this example is as follows:

[0093]

[0094] (II) Preparation of europium complex Eu(1m7CFIZ)3bpy

[0095] Synthesis of 1-[6-bromo-2-fluoro-3-(trifluoromethyl)phenyl]ethanol

[0096] 6-Bromo-2-fluoro-3-(trifluoromethyl)benzaldehyde (24.4 g, 90 mmol) was dissolved in 300 mL of anhydrous tetrahydrofuran. Under nitrogen protection, the solution was cooled to -5 °C, and 1 mol / L methylmagnesium bromide (108 mL, 108 mmol) was added dropwise. After the addition was completed, the reaction was continued for 0.5 h. After the reaction was completed, saturated ammonium chloride solution was added to quench the reaction. Then, the mixture was extracted with ethyl acetate, and the organic phase was concentrated and purified by column chromatography to obtain 23.8 g of pale yellow oily 1-[6-bromo-2-fluoro-3-(trifluoromethyl)phenyl]ethanol with a yield of 92%.

[0097] Synthesis of 1-[6-bromo-2-fluoro-3-(trifluoromethyl)phenyl]ethanone

[0098] Dissolve 1-[6-bromo-2-fluoro-3-(trifluoromethyl)phenyl]ethanol (23.8 g, 82.8 mmol) in 480 mL of dichloromethane, add manganese dioxide (72 g, 828 mmol), heat up to 40 °C, and keep the reaction at this temperature for 6 h. After the reaction is completed, filter the reaction solution through diatomaceous earth by suction. After concentrating the filtrate, purify it by column chromatography to obtain 21.5 g of pale yellow liquid 1-[6-bromo-2-fluoro-3-(trifluoromethyl)phenyl]ethanone with a yield of 91%. Directly use it for the next step.

[0099] Synthesis of 3-methyl-4-bromo-7-(trifluoromethyl)-1H-indazole

[0100] Add 350 mL of 80% by mass methylhydrazine solution to a reaction flask containing 1-[6-bromo-2-fluoro-3-(trifluoromethyl)phenyl]ethanone (21.5 g, 75.4 mmol), heat up to 100 °C, and keep the reaction at this temperature for 6 h. After the reaction is completed, filter by suction while it is hot. Wash with water, and dry the filter cake to obtain 18.9 g of white solid 3-methyl-4-bromo-7-(trifluoromethyl)-1H-indazole with a yield of 90%. Conduct 1H NMR inspection, and the results are as follows: 1 1H NMR (d6-DMSO): 13.55 (s, 1H), 7.60 (d, J = 7.8 Hz, 1H), 7.47 (d, J = 7.7 Hz, 1H), 2.71 (s, 3H).

[0101] Preparation of europium complex Eu(1m7CFIZ)3bpy

[0102] In 100 mL of methanol, add 2 g (8.2 mmol) of 3-methyl-4-bromo-7-(trifluoromethyl)-1H-indazole, 1.28 g (8.2 mmol) of bipyridine, and 0.91 g (11.36 mmol) of caustic soda. After ultrasonic oscillation, reflux and stir for 15 mins. Then dropwise add a solution of europium salt (2.09 g, 5.68 mmol) dissolved in methanol. Reflux and stir for 1 h. After the reaction is completed, remove the magnetic stir bar and spin-dry the reaction solution. Add dichloromethane and stir for 15 mins. Filter by suction to obtain a clear filtrate, and spin-dry to obtain 3.68 g of europium complex product (Eu(1m7CFIZ)3bpy). The yield is 73%.

[0103] Take the europium complex product (Eu(1m7CFIZ)3bpy) for mass spectrometry detection, and the results are as follows: MS (m / z, ESI): calcd for C 40 H 26 EuN8NaO6 1061.0937, found 1061.0923; EA for C 40 H 26EuN8NaO6: C 46.30; H 2.53; N 10.80. Found: C 46.23; H 2.49; N 10.82.

[0104] Example 3

[0105] The synthetic route involved in this example is as follows:

[0106]

[0107] (III) Preparation of europium complex Eu(1mIZ)2TTA2 (all ligand raw materials are commercially available)

[0108] In 100 mL of methanol, add 2 g (11.36 mmol) of 1-methyl-3-indazolecarboxylic acid, 2.52 g (11.36 mmol) of 2-thiophenecarbonyltrifluoroacetone, and 1.82 g (11.36 mmol) of caustic soda. After ultrasonic oscillation, reflux and stir for 15 mins. Then dropwise add a solution of europium salt (2.09 g, 5.68 mmol) dissolved in methanol. Reflux and stir for 1 h. After the reaction is completed, remove the magnetic stirrer and spin-dry the reaction solution. Add dichloromethane and stir for 15 mins. Filter to obtain a clear filtrate, and spin-dry to obtain 3.9 g of europium complex product (Eu(1mIZ)2TTA2). The yield is 86%.

[0109] Take the europium complex product (Eu(1mIZ)2TTA2) for mass spectrometry test, and the results are as follows: MS (m / z, ESI): calcd for C 34 H 22 EuF6N4Na2O8S2 990.9786, found 990.9790; EA for C 34 H 22 EuF6N4NaO8S2: C 42.20; H 2.29; N 5.79. Found: C 42.23; H 2.31; N 5.81.

[0110] Use the single crystal cultivation method to cultivate the single crystal of Eu(1mIZ)2TTA2, and conduct X-ray diffraction measurement on the obtained single crystal. The structure is as Figure 1 shown. Figure a) is the ball-and-stick diagram of the single crystal structure of the europium complex (ignoring hydrogen). To further clearly show the crystal structure, Figure b) labels each atom in Figure a). It can be determined from the figure that the obtained product is the chemical structure of the europium complex product (Eu(1mIZ)2TTA2) of the present invention.

[0111] Take the europium complex powder (Eu(1mIZ)2TTA2) for emission spectrum detection at an excitation wavelength of 395 nm, and the results are as Figure 2As shown, it can be seen from the figure that the maximum emission wavelength of the europium complex product (Eu(1mIZ)2TTA2) is 618 nm.

[0112] The excitation spectrum of europium complex powder (Eu(1mIZ)2TTA2) was detected at an emission wavelength of 618 nm, and the results are as Figure 3 shown. It can be seen from the figure that the maximum excitation wavelength of the europium complex product (Eu(1mIZ)2TTA2) is 392 nm.

[0113] The ultraviolet-visible absorption spectrum of europium complex powder (Eu(1mIZ)2TTA2) was tested, and the results are as Figure 4 shown. It can be seen from the figure that the maximum absorption wavelength of Eu(1mIZ)2TTA2 is 394.5 nm.

[0114] The infrared spectra of europium complex powder (Eu(1mIZ)2TTA2), ligand TTA, and 1mIZ were tested respectively, and the results are as Figure 5 shown. It can be seen from the figure that after the ligand compound coordinates with the metal, the characteristic peaks shift. For example, the β-diketo enol form on TTA: 1645 cm -1 shifts to 1625 cm -1 ; the carboxyl -OH on 1mIZ: 3438 cm -1 shifts to 3444 cm -1 ; the -C=N- on 1mIZ: 1595 cm -1 shifts to 16,41 cm -1 .

[0115] Example 4

[0116] The synthetic route involved in this example is as follows:

[0117]

[0118] (IV) Preparation of europium complex Eu(1pyIZ)3

[0119] Synthesis of 2,6-dichloro-4-trifluoromethylphenyl diazonium tetrafluoroborate

[0120] In a 25 mL reactor, 10 mmol of 2,6-dichloro-4-trifluoromethylaniline, 3 mL of water, 2 mL of ethanol, and 3 mL of aqueous tetrafluoroboric acid solution (48%, w / w) were added. The mixture was stirred at 25 °C for 0.5 h and then cooled to 0 °C. A mixed solution of 11 mmol of sodium nitrite and 2 mL of water was added dropwise, and the mixture was stirred at 0 °C for 1 h. A white precipitate was formed and filtered at low temperature. The filter cake was washed successively with 5 mL of ice water and 5 mL of ethyl acetate, and dried at room temperature to obtain 2,6-dichloro-4-trifluoromethylphenyl diazonium tetrafluoroborate with a yield of 80%.

[0121] In a 25 mL reaction flask, 0.3 mmol of 3-phenyl-1,1,1-trifluoroacetone and 2 mL of acetonitrile were added. The mixture was cooled to 0 °C, and 0.3 mmol of 1,4-diazabicyclo[2.2.2]octane and 0.2 mmol of 2,6-dichloro-4-(trifluoromethyl)phenyl diazonium tetrafluoroborate were successively added. The reaction mixture was stirred at 25 °C for 0.5 h, water was added, and the reaction solution was extracted with ethyl acetate. The solvent was removed by rotary evaporation under reduced pressure, and then the product was separated and purified by column chromatography. The eluent used for column chromatography was a mixed solvent of petroleum ether:ethyl acetate with a volume ratio of 10:1, and the product was obtained with a yield of 75%.

[0122] In a 25 mL reactor, 0.3 mmol of 3-[2-(2,6-dichloro-4-(trifluoromethyl)phenyl)hydrazono]-1,1,1-trifluoro-3-phenylpropan-2-one and 2 mL of hexafluoroisopropanol were added. 0.45 mmol of bis(trifluoroacetoxy)iodobenzene was added, and the reaction mixture was stirred at 25 °C for 12 h. Water was added, and the reaction solution was extracted with ethyl acetate. The solvent was removed by rotary evaporation under reduced pressure to obtain a crude product, and the target product 1-(pyridin-2-yl)-1H-indazole-3-carboxylic acid was obtained by column chromatography purification with a yield of 73%.

[0123] In 100 mL of methanol, 1.25 g of 1-(pyridin-2-yl)-1H-indazole-3-carboxylic acid and 568 mg of sodium hydroxide were added. After ultrasonic oscillation, the mixture was refluxed and stirred for 15 mins. Then, 622 mg / 50 mL of europium solution dissolved in methanol was added dropwise, and the mixture was refluxed and stirred for 1 h. After the reaction was completed, the magnetic stirrer was removed, and the reaction solution was dried by rotary evaporation. A dichloromethane / ethanol mixed solution was added and stirred for 15 mins, and the filtrate was filtered to obtain a filter cake, which was dried to obtain the europium complex product (Eu(1pyIZ)3) with a yield of 81%.

[0124] The europium complex product (Eu(1pyIZ)3) was subjected to mass spectrometry testing, and the results were as follows: MS (m / z, ESI): calcd for C 39 H 24 EuN9NaO6 890.0955, found 890.0943; EA for C 39 H 24 EuN9O6 C 54.05; H 2.79; N 14.55, Found C 54.13; H 2.81; N 14.56.

[0125] Example 5

[0126] The synthetic route involved in this example is as follows:

[0127]

[0128] (V) Preparation of europium complex Eu(TTA)4

[0129] In 100 mL of methanol, 1.114 g of 2-thenoyltrifluoroacetone and 200 mg of caustic soda were added. After ultrasonic oscillation, the mixture was refluxed and stirred for 15 mins. Then, 458 mg / 50 mL of europium solution dissolved in methanol was dropped in. The mixture was refluxed and stirred for 1 h. After the reaction ended, the magnetic stirrer was removed and the reaction solution was dried by rotation. A dichloromethane / ethanol mixed solution was added and stirred for 15 mins. The filtrate was obtained by suction filtration and dried by rotation to obtain the europium complex product (Eu(TTA)4) with a yield of 93%.

[0130] The europium complex product (Eu(TTA)4) was taken for mass spectrometry test, and the results were as follows: MS(m / z, ESI): calcd for C 32 H 16 EuF 12 N 12 NaO8S4 1082.8539, found 1082.8541; EA for C 32 H 16 EuF 12 N 12 Na2O8S4 C 36.27; H 1.52; S 12.10, Found C 36.29; H 1.56; S 12.31.

[0131] Example 6

[0132] The synthetic route involved in this example is as follows:

[0133]

[0134] (VI) Preparation of europium complex Eu(1mIZ)4

[0135] In 100 mL of methanol, 1 g of 1-methylindazole-3-carboxylic acid and 227 mg of caustic soda were added. After ultrasonic oscillation, the mixture was refluxed and stirred for 15 mins. Then, 520 mg / 50 mL of europium solution dissolved in methanol was dropped in. The mixture was refluxed and stirred for 1 h. After the reaction ended, the magnetic stirrer was removed and the reaction solution was dried by rotation. A dichloromethane / ethanol mixed solution was added and stirred for 15 mins. The filtrate was obtained by suction filtration and dried by rotation to obtain the europium complex product Eu(1mIZ)4 with a yield of 91%.

[0136] The europium complex (Eu(1mIZ)4) was taken for mass spectrometry test, and the results were as follows: MS(m / z, ESI): calcd for C 36 H 28 EuN8NaO8 899.1033, found 899.1029; EA for C 36 H 28EuN8Na2O8 C 49.38; H 3.22; N 12.80. Found C 49.40; H 3.21; N 12.75.

[0137] The europium complex (Eu(1mIZ)4) was subjected to infrared spectroscopy test, and the results are as Figure 6 shown. It can be seen from the figure that the carboxyl hydroxyl group -OH on IZ: 3438 cm -1 shifts to 3450 cm -1 ; the -C=N- on IZ: 1595 cm -1 shifts to 1631 cm -1 .

[0138] The europium complex (Eu(1mIZ)4) was subjected to ultraviolet-visible absorption spectroscopy test, and the results are as Figure 7 shown. It can be seen from the figure that the maximum absorption wavelength of Eu(1mIZ)2TTA2 is 298 nm.

[0139] The europium complex (Eu(1mIZ)4) was subjected to emission spectrum detection at an excitation wavelength of 307 nm, and the results are as Figure 8 shown. It can be seen from the figure that the highest emission wavelength of the europium complex (Eu(1mIZ)4) is 616 nm.

[0140] The europium complex (Eu(1mIZ)4) was subjected to excitation spectrum detection at an emission wavelength of 616 nm, and the results are as Figure 9 shown. It can be seen from the figure that the highest excitation wavelength of the europium complex (Eu(1mIZ)4) is 307 nm.

[0141] Example 7

[0142] The synthetic route involved in this example is as follows:

[0143]

[0144] (VII) Preparation of europium complex Eu(IZ)4

[0145] In 100 mL of methanol, 920.5 mg of 1H-indazole-3-carboxylic acid and 227 mg of caustic soda were added. After ultrasonic oscillation, the mixture was refluxed and stirred for 15 mins. Then, 520 mg / 50 mL of europium solution dissolved in methanol was dropped in. The mixture was refluxed and stirred for 1 h. After the reaction was completed, the magnetic stirrer was removed and the reaction solution was rotary evaporated to dryness. A dichloromethane / ethanol mixed solution was added and stirred for 15 mins. The mixture was filtered to obtain a filter cake, which was dried to obtain the europium complex product with a yield of 93%.

[0146] The europium complex product (Eu(IZ)4) was subjected to mass spectrometry test, and the results are as follows: MS(m / z, ESI): calcd for C 32H 20 EuN8Na2O8 843.0407, found 843.0411; EA for C 32 H 20 EuN8NaO8 C 46.90; H 2.46; N 13.67, Found C 46.92; H 2.49; S 13.49.

[0147] Example 8

[0148] The synthetic route involved in this example is as follows:

[0149]

[0150] (VIII) Preparation of europium complex Eu(IZ)2TTA2 (ligand raw materials are all commercially available)

[0151] In 100 mL of methanol, add 1.87 g (11.36 mmol) of 3-indazolecarboxylic acid, 2.52 g (11.36 mmol) of 2-thenoyltrifluoroacetone, and 1.82 g (11.36 mol) of caustic soda. After ultrasonic oscillation, reflux and stir for 15 mins. Then dropwise add a solution of europium salt (2.09 g, 5.68 mmol) dissolved in methanol. Reflux and stir for 1 h. After the reaction is completed, remove the magnetic stirrer and spin-dry the reaction solution. Add dichloromethane and stir for 15 mins. Filter to obtain a clear filtrate, and spin-dry to obtain 3.87 g of europium complex product (Eu(IZ)2TTA2). The yield is 86%.

[0152] Take the europium complex product (Eu(IZ)2TTA2) for mass spectrometry test, and the results are as follows: MS (m / z, ESI): calcd for C 32 H 18 EuF6N4Na2O8S2 764.0470, found 764.0481; EA for C 32 H 18 EuF6N4NaO8S2 C 50.27; H 2.37; N 7.33, Found C 50.33; H 2.31; N 7.31.

[0153] Performance test

[0154] Separate samples of Eu(1mIZ)2TTA2 prepared in Example 3, Eu(TTA)4 prepared in Example 5, Eu(1mIZ)4 prepared in Example 6, Eu(IZ)4 prepared in Example 7, and Eu(IZ)2TTA2 prepared in Example 8 were taken. A fluorescence spectrometer equipped with an integrating sphere was used to measure the quantum yield (measurement conditions: excitation wavelength range of 300 nm - 320 nm, emission spectral wavelength range of 530 nm - 800 nm, and finally quantum yield data were obtained). A thermogravimetric analyzer was used to measure the decomposition temperature (measurement conditions: after drying the sample, the temperature was increased by 10 °C per minute from 25 °C to 500 °C, and when the weight of the sample lost 5%, the temperature at this time was the decomposition temperature). An ultraviolet aging chamber experiment was used to test the ultraviolet radiation aging change (measurement conditions: irradiance (W / m 2 / nm): 0.51; temperature: 65 °C; test duration: 24 h). The obtained luminescence quantum yield, decomposition temperature (TGA), and ultraviolet radiation aging change are shown in Table 1. It can be seen from the table that the complex with the highest luminescence quantum yield is Eu(TTA)4 prepared in Example 5, with a luminescence quantum yield of 73%; the complex with the highest decomposition temperature is Eu(IZ)2TTA2 prepared in Example 8, with a decomposition temperature of 323 °C; there is no obvious change in the light decay after ultraviolet radiation for Eu(1mIZ)2TTA2 prepared in Example 3 and Eu(IZ)2TTA2 prepared in Example 8. Among them, the 70% luminescence quantum yield of Eu(1mIZ)2TTA2 prepared in Example 3 is slightly lower than the 73% of Eu(TTA)4 prepared in Example 5, but the decomposition temperature (255 °C) is slightly higher than the 237 °C of Eu(TTA)4 prepared in Example 5. Eu(IZ)2TTA2 prepared in Example 8 has the highest decomposition temperature of 323 °C, a luminescence quantum yield of 65%, and no obvious change in the light decay after ultraviolet irradiation. It can be seen from this that the novel double-anion complex can significantly improve its stability without significantly reducing the luminescence efficiency.

[0155] Table 1 Comparison of Luminescence Quantum Yield, Thermal Stability, and Ultraviolet Tolerance of Different Europium Complexes

[0156]

[0157]

[0158] The above embodiments merely exemplarily illustrate the principles and effects of the present invention, rather than limiting the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. Indazole-based europium complex, with the general structural formula Eu(IZ) x A y L m , where IZ is an indazole-3-carboxylic acid-based anionic ligand, A is an anionic ligand other than IZ, and L is a neutral ligand; x is selected from 1 or 2 or 3 or 4, y is selected from 0 or 1 or 2, and x + y = 3 or x + y = 4 is satisfied, and m is selected from 0 or 1 or 2; The neutral ligand L is selected from a pyridine-containing bidentate ligand or a pyridine-containing tridentate ligand or a phosphine-containing monodentate ligand; The structural formula of IZ is as shown in formula (a), The structural formula of the indazole-based europium complex is as shown in Figure (Ⅰ), Among them, R1, R2, R3, R4 and R5 are each independently selected from a hydrogen atom, a halogen atom, a cyano group, a linear or branched alkyl group having 1 to C 24 linear or branched alkyl group, C1-C 24 linear or branched halogen-substituted alkyl group, C1-C 24 linear or branched aryl-substituted alkyl group.

2. The indazole-based europium complex according to claim 1, wherein, A is a β-diketone-based ligand, and its structural formula is as shown in formula (b), Among them, R a , R b are each independently selected from aryl, heteroaryl or fluoroalkyl.

3. The indazole-based europium complex according to claim 2, wherein, Each aryl group is independently selected from a phenyl group or a naphthyl group; Each heteroaryl group is independently selected from a thiophenyl group, a furyl group or a pyridyl group; Each fluoroalkyl group is independently selected from a trifluoromethyl group or a pentafluoroethyl group.

4. The indazole-based europium complex according to any one of claims 1 to 3, which has a structure represented by the following general formula (Ⅱ), Among them, x, y, m, A, L are as described in any one of claims 1 to 3.

5. The indazole-based europium complex according to any one of claims 1 to 3, which has a structure represented by the following general formula (Ⅲ), Among them, x, y, m, A, L are as described in any one of claims 1 to 3.

6. The indazole-based europium complex according to any one of claims 1 to 3, which has a structure represented by the following general formula (IV), Among them, x, y, m, A, L are as described in any one of claims 1 to 3.

7. The indazole-based europium complex according to any one of claims 1 to 3, which has a structure represented by the following general formula (V), Among them, x, y, m, A, L are as described in any one of claims 1 to 3.

8. The indazole-based europium complex according to any one of claims 1 to 3, which has a structure represented by the following general formula (VI), Among them, x, y, m, A, L, R2, R3, R4, R5 are as described in any one of claims 1 to 3, and R6, R7, R8, and R9 are each independently selected from a hydrogen atom, a halogen atom, a cyano group, a linear or branched substituted alkyl group having 1 to 24 carbon atoms, or a linear or branched halogen-substituted alkyl group having 1 to 24 carbon atoms.

9. The indazole-based europium complex according to any one of claims 1 to 3, which has a structure represented by the following general formula (VII), Among them, x, y, m, A, L, R2, R3, R4, R5 are as described in any one of claims 1 to 3, and R 10 is selected from hydroxy, C1-C 24 linear or branched alkyl, C1-C 24 linear or branched halogen-substituted alkyl, amino or C1-C 24 linear or branched alkoxy.

10. Use of the indazole-based europium complex according to any one of claims 1 to 9 in the field of luminescent materials.

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