KR101591484B1 - Rare earth europium coordination complex and application using same as light emitting material - Google Patents

Abstract

The present invention relates to a rare earth europium complex and its application as a light emitting material. The europium complex structure formula is Eu (ND) _x A _y L _m . Wherein ND is a 4-hydroxy-1,5-naphthyridine based anionic ligand, A is other anionic ligand, L is a neutral ligand, x = 1, 2 or 3, y = 0, 1 or 2 X + y = 3; m = 1, 2 or 3; Such a europium complex has a high efficiency in light emitting quantum yield, excellent thermal stability, excellent carrier transfer effect, and can be used as a light emitting and electroluminescent material.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare earth europium complex,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare earth complex light emitting material, and more particularly, to a rare earth europium complex having high efficiency light emission and electroluminescence.

As we all know, energy is a task that must be solved for the development of human society in the 21st century. It is also important for people to save energy while developing new energy. In everyday life, energy consumption alone accounts for about 20% of total energy consumption. However, the utilization rate of the energy of the current illumination source still has not obtained a satisfactory effect. Light-emitting diode (LED) light sources are attracting much attention because of their high efficiency of energy conversion. Particularly, organic light-emitting diodes (OLEDs) have potential advantages such as large area and thinness, and theoretically, the efficiency of light emission is high, which is a problem to be studied.

In full-color displays, the use of OLEDs is also noteworthy. Currently, most of the color displays that people use are cathode ray tubes or liquid crystal displays. Cathode ray tubes are large in volume, slow in response, low in efficiency, and are rarely used at present. Liquid crystal displays, which are widely used today, have a small volume and improved performance, but they are passive light sources, narrow viewing angles, and slow response times. Organic electroluminescence has a very large attractive force and has the following characteristics. 1. Full color active light, color is clear (liquid crystal screen requires backlight). 2. Ultra-thin display is possible, and it can be smoothly softened. 3. The response speed is fast (100 times of liquid crystal), wide viewing angle range is 180 ° (LCD screen is only 45 °). 4. Since the driving voltage is low, only a DC voltage of 3 to 10 volts is required, and the luminous efficiency is high. 5. Easy to manufacture and low cost.

Thus, in an illumination or a display, an organic molecular light emitting material has a very high applicability. Among them, rare-earth luminescent materials can be most preferably used because of their unique properties. The advantages of the rare earth complex light emitting material are mainly realized in the following aspects.

1. Narrow-band firing, good monochromaticity. This is very advantageous for display devices having high color purity. Rare earth elements have a unique electronic arrangement and energy level structure. Particularly, the 4f electron layer is enriched in energy level, and the rare earth element emits light between these 4f layer energy levels. Since the rare earth complex luminescent material has a high energy level and the inner layer electrons and the outer layer electrons have a blocking action, they are less affected by external factors during light emission. This enables narrow-band firing. In using the organic small molecule electroluminescence for a color display, some energy is wasted because a basic color of red, green, and blue (RGB) must be obtained by a filter or other method. Since rare-earth compounds are capable of narrow-band emission with a color coordinate of less than 10 nm, it is important to use them in organic electroluminescent materials.

2. High quantum efficiency in theory. Pure organic fluorescent light emitting materials are subject to rotational statistics, and there is a theoretical limit on their maximum internal quantum efficiency (less than 25%). On the other hand, the light emitting process of the rare earth complexes intersystem crossing from excited singlet states of the organic ligand to the triplet excited state, and then the energy is again transferred to the rare earth ions to excite 4f electrons , And returns to the ground state to emit light. Theoretically, the internal quantum efficiency can reach 100%, because both the singlet state and the triplet state can carry energy.

3. The ligand modification does not affect the emission wavelength. In order to achieve good energy level matching and carrier conductivity, various modifications are generally made to the ligand. Since the light emitter of the rare earth complex is a central rare earth ion, the ligand modification does not cause a shift in the spectral peak. Thus, in terms of material design modification, the rare earth complex luminescent material has unique advantages.

孟濂) 등은 카바졸을 함유한 β-디케톤 리간드의 희토류 Eu착물을 합성하였으며, 이러한 착물을 다운 컨버젼 발광 형광 분말로서 근자외선광을 발사하는 InGaN기질에 도포하여 적색광을 발사하는 LED소자(M.L.Gong et al, Appl. Phys. B, 2010，99, 757)를 제조하였다. 그러나, 이러한 Eu착물 발광을 이용한 LED소자에서 퀸칭 및 전압의 변화에 따라 혼색이 나타나는 불안정한 문제가 발생하였다.As can be seen from the above, the rare earth complex has excellent light emitting performance and can be widely applied in the field of light emission and electroluminescence. In the field of luminescence, in general, a down-converted luminescent material of red light europium and green light terbium can be used as a fluorescent powder. At present, the three most commonly used fluorescent color powders used in illumination fluorescent lamps are rare earth green powder (Ce, Tb) MgAl ₁₁ O ₁₉ , blue powder (Ba, Mg, Eu) ₃ Al ₁₆ 0 ₂₇ and red powder Y ₂ O ₃ : Eu ³⁺ . These are inorganic solid light emitting materials containing rare earths. The rare earth organic complexes have higher luminous efficiency but lower chemical stability and fluorescent thermal stability than inorganic materials. Therefore, by developing an organic complex fluorescent material which is stable against heat and ultraviolet radiation, the amount of rare earth used can be reduced and the cost can be reduced. The trivalent europium complex can effectively absorb ultraviolet rays, emit clear red light, and can be used as an organic red light downconversion material. Zhongshan University of China

Meng, et al.) Synthesized a rare earth-Eu complex of a β-diketone ligand containing carbazole, and applied this complex to an InGaN substrate emitting near-ultraviolet light as a down-conversion luminescent fluorescent powder to emit red light MLGong et al, Appl. Phys. B, 2010, 99, 757). However, an unstable problem has arisen in the LED device using this Eu complex emission, in which color mixture appears due to quenching and voltage change.

In the field of electroluminescence, the application of rare earth Eu complex to OLED has already been studied by many people. Currently, the europium ligand substrates used are all? -Diketone compounds. In 1991, Kido et al. First fabricated an organic electroluminescent device using rare earth europium complex Eu (TTA) ₃ .2H ₂ O as a light emitting material, thereby realizing narrow band red light emission. Not long ago, the present inventors synthesized Eu (TTA) ₃ PhO using a phenanthroline derivative containing oxadiazole as a neutral second ligand, and further fabricated an OLED device. Such an OLED device can emit pure europium red light having a maximum luminance of 1086 cd / m ² and can reach a maximum power efficiency of 5.5 LPW, so that the Eu (TTA) ₃ light emitting material is used in OLED devices at a high level (Zhuqi Chen et al, New J. Chem., 2010, 34, 487).

At present, rare-earth europium complexes used in the research basically use an? -Diketone compound as an antenna ligand, among which a compound having a very high photoluminescence quantum yield is not sufficient, but a down conversion LED material Or the application to the electroluminescent OLED is not performed smoothly. The main reason is that 1. β-diketone structure complex is prone to quenching at the time of light emission, and 2. β-diketone structure complex exhibits relatively poor carrier transport performance upon electroluminescence. These defects seriously affect the electroluminescent efficiency of the? -Diketone-based europium complex and the stability against temperature rise during operation of the device.

It is an object of the present invention to provide a rare earth europium complex with a 4-hydroxy-1,5-naphthyridine based ligand used for light emitting and electroluminescent islands.

The structural formula of the europium complex of the present invention is Eu (ND) _x A _y L _m .

In the structural formula, ND is a 4-hydroxy-1,5-naphthyridine based anion ligand represented by the formula (I), A is other anion ligand other than ND, L is a neutral ligand; x = 1, 2 or 3, y = 0, 1 or 2, and x + y = 3; m = 0, 1, 2 or 3; m is determined by different neutral ligands.

Formula I

Wherein R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen substituted alkyl group, an alkenyl group, an alkynyl group, A substituted amino group, an alkoxy group, a carboxy group, an ester group, an acyl group, an acylamino group, an N-substituted acylamino group, an aryl group or a heteroaryl group.

Here, the halogen atom represents F, Cl, or the like.

The alkyl group is preferably a straight-chain or branched alkyl group having 1 to 24 carbon atoms, more preferably a straight or branched alkyl group having 1 to 6 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, 3 Sec-butyl, tert-butyl, pentyl, neopentyl, hexyl, and the like. Particularly preferably a straight or branched alkyl of C1-C4.

The halogen-substituted alkyl group is preferably a C1-C24 linear or branched halogen-substituted alkyl group, more preferably a C1-C6 linear or branched halogen substituted alkyl group, and examples thereof include halogenated methyl, halogenated ethyl, Isopropyl, halogenated butyl, isobutyl halide, tert-butyl halide, and secondary butyl halide. Particularly preferably a straight-chain or branched-chain halogenated alkyl group of C1-C3, for example, trifluoromethyl or pentafluoroethyl.

The alkenyl group or the alkynyl group is preferably a C2-C24 linear or branched alkenyl group or an alkynyl group, more preferably a C2-C6 linear or branched alkenyl group or an alkynyl group, particularly preferably a C2-C4 A straight chain or branched alkenyl group or an alkynyl group. For example, ethylene, ethynyl, 1-propylene, 1-propargyl, 1-butylene, 1-butyne, butadiene and the like.

The N-substituted amino group is preferably a C1-C6 alkyl group-substituted amino group, and is, for example, a dimethylamino group.

The alkoxy group is preferably a straight-chain or branched alkoxy group of C1-C24, more preferably a straight-chain or branched alkoxy group of C1-C6, particularly preferably a straight-chain or branched alkoxy group of C1-C4. For example, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, and an isobutoxy group.

The ester is a carboxylate of structure -COOR. R is preferably a linear or branched alkyl group or halogen-substituted alkyl group of C1-C24, more preferably R is a C1-C6 linear or branched alkyl group or halogen substituted alkyl group, particularly preferably R is C1-C4 linear or branched A branched alkyl group or a halogen-substituted alkyl group. The esters are, for example, methyl carboxylate, ethyl carboxylate, propyl carboxylate, isopropyl carboxylate, butyl carboxylate, methyltrifluorocarboxylate, ethyl perfluorocarboxylate, and the like.

The acyl group structure is a -COR group, wherein R is preferably a linear or branched alkyl group having 1 to 24 carbon atoms, more preferably a linear or branched alkyl group having 1 to 6 carbon atoms, particularly preferably a linear or branched alkyl group having 1 to 4 carbon atoms Or a branched alkyl group. The acyl group includes, for example, an acetyl group, a propionyl group, an isopropionyl group, and a butyryl group.

The N-substituted acylamino group is preferably an N-phase substituent preferably an acylamino group of a straight-chain or branched alkyl group of C1-C24, more preferably an N-phase substituent is an acylamino group of a C1-C6 linear or branched alkyl group , Particularly preferably the substituent on the N-phase is an acylamino group of C1-C4 linear or branched alkyl group. For example, N, N-dimethylformamide, N, N-diethylformamide and the like.

The aryl group or the heteroaryl group is preferably an unsubstituted aryl group, a heteroaryl group or an aryl group or a heteroaryl group containing a substituent. For example, phenyl, furan, pyrazolyl, pyridyl, oxadiazole, and the like.

When R ₅ is not a nitrogen or oxygen coordination-point containing group, the 4-hydroxy-1,5-naphthyridine based europium complex structure of the present invention can be represented as follows (formula (II)

(II)

In formula Ⅱ, R _1, R _2, R _3, R ₄ and R ₅ are each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen-substituted alkyl group, an alkenyl group, an alkynyl group, an amino group, N- An amino group, a substituted amino group, an alkoxy group, a carboxy group, an ester group, an acyl group, an acylamino group, an N-substituted acylamino group, an aryl group or a heteroaryl group, and R ₅ is a nitrogen or oxygen-free coordination point; A is other anionic ligand other than ND, L is a neutral ligand; x = 1, 2 or 3, y = 0, 1 or 2, x + y = 3; m = 0, 1, 2 or 3; m is determined by different neutral ligands, and the preferred range of each group is as described above.

Specifically, when, for example, R ₁ and R ₃ are methyl groups and R ₂ , R ₄ and R ₅ are hydrogen atoms, the following complex formula is obtained.

When R ₁ is cyano, R ₃ is a methyl group, and R ₂ , R ₄ and R ₅ are hydrogen atoms, the structure of the complex is as follows.

When R ₁ is trifluoromethyl, R ₃ is a fluorine atom, and R ₂ , R ₄ , and R ₅ are hydrogen atoms, the following formula is shown.

When the anion ligand A is a? -Diketone-based ligand, the structure of the complex is as follows.

In the above formulas, R _a and R _b are each independently an aromatic group such as a phenyl group or a naphthyl group, or a heteroaryl group such as thienyl, furan, or pyridyl, or a fluoroalkyl group such as trifluoromethyl or pentafluoroethyl. Preferably, the? -Diketone anion ligand is selected from the group consisting of dibenzoylmethane (DBM), decanoyl trifluoroacetone (TTA), dinaphthyl methane formyl group (DNM), methane triflouroacetyl naphthoyl group have. x = 1 or 2, y = 1 or 2, x + y = 3; m = 0, 1, 2 or 3;

The neutral ligand L may be water molecules, alcohol molecules, coordination small molecules such as acetone, and molecules and derivatives of phenanthroline (phen), bipyridine (bpy), and triarylphosphine oxide (ArPO) system structures.

In particular, R ₅ is nitrogen or oxygen, if contained date coordinated regard, the 4-hydroxy-1,5-naphthyridin-ligand (ND) is the anion of a tridentate ligand, complexes formed structural formula is Eu (ND) _x A _y L _m . Where A is other anionic ligand other than ND and L is a neutral ligand; x = 1, 2 or 3, y = 0, 1 or 2, x + y = 3; m = 0, 1 or 2, and m is determined by a different neutral ligand. This type of tridentate anion ligand is a new ligand that has advantages such as stable coordination, good complex sublimation, three tridentate anion ligands with one trivalent europium ion and no need for neutral ligand have. Accordingly, both of these new tridentate anion ligands and the synthesized europium complexes fall within the scope of protection of the present invention.

In the nitrogen-containing point-containing group, an aza five-membered ring aromatic group such as pyrrolyl, imidazole, pyridyl or oxazolyl, and an aza 6-membered ring aryl group are the most common. When R5 is a pyridyl group, the structure of the complex formed with the tridentate ligand and Eu is represented by the following formula (III).

(III)

As described above, the tridentate ligand has a resonance structure of an enol type and a keto type. Here, R ₁ , R ₂ , R ₃ and R ₄ are as described above. R _6, R _7, R ₈ and R ₉ are each independently selected from a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen-substituted alkyl group, an amino group, N- substituted amino group or an alkoxy group. The preferable range of each group is as described above. A is other anion ligand other than ND, and L is a neutral ligand. x = 1, 2 or 3, y = 0, 1 or 2, x + y = 3; m = 0, 1 or 2, m is determined by different neutral ligands.

When the oxygen-coordination-point-containing group is mainly a carbonyl-containing group, and when R ₅ is a carbonyl group-containing group, the complex of the tridentate ligand and Eu is represented by the following formula (IV).

(IV)

As described above, the tridentate ligand has a resonance structure of an enol type and a keto type. Here, R ₁ , R ₂ , R ₃ and R ₄ are as described above. R ₁₀ is selected from a hydroxyl group, an alkyl group, a halogen-substituted alkyl group, an amino group, an N-substituted amino group or an alkoxy group. The preferable range of each group is as described above. A is other anion ligand other than ND, and L is a neutral ligand. x = 1, 2 or 3, y = 0, 1 or 2, x + y = 3; m = 0, 1 or 2, m is determined by different neutral ligands.

For a complex of formula (III), R ₁ is cyano, R ₂ , R ₃ , R ₄ , R ₆ , R ₇ , When R ₈ and R ₉ are hydrogen atoms, the following is a structural formula of the complex.

Further, when x = 3, y = 0 and m = 0, the structure of the complex is as follows.

For a complex of formula (IV), R ₁ is cyano, R ₂ , R ₃ , When R ₄ is a hydrogen atom and R ₁₀ is a methyl group, the following is a structural formula of the complex.

Further, when x = 3, y = 0 and m = 0, the structure of the complex is as follows.

The 4-hydroxy-1,5-naphthyridine-based ligand of the present invention is similar to the 8-hydroxyquinoline structure in the star molecule Alq ₃ in a conventional electroluminescent material, and Alq ₃ Has the best electron transporting ability. Since the HOMO energy level of the 4-hydroxy-1,5-naphthyridine based ligand is low and the LUMO energy level is kept almost unchanged, as compared to 8-hydroxyquinoline, the electrons are well injected and conducted at the LUMO energy level The hole can greatly enhance the conduction capability at the HOMO energy level. An electroluminescent element of red light europium can be produced by using a complex formed of a trivalent europium ion and the ligand by the good electron and hole transporting ability of a 4-hydroxy-1,5-naphthyridine based ligand.

The photoluminescence quantum yield is another important parameter of photoluminescent and electroluminescent materials. Europium complex Eu (8mCND) ₃ L of the invention geochimyeon the sublimation can be obtained Eu (8mCND) _3. The yield of the photoluminescence quantum obtained by measurement with an aqueous solution of dipyridyl lutetium as a reference is about 40% (oxygen is not removed in the acetonyltriyl solution) and is at a high level in the europium complex.

The 4-hydroxy-1,5-naphthyridine based europium complex of the present invention has advantages such as compact structure stiffness, good thermal stability and strong carrier transport ability as compared with the? - diketone based europium complex of a typical ligand And is very suitable as an electroluminescent material and a photoluminescent material.

1 is a photoluminescence spectrum of Eu (8mCND) ₃ measured in Example 5 of the present invention.
2 is a view showing a structure of an electroluminescent device manufactured in Example 5 of the present invention.
3 is an electric field emission spectrum according to a voltage change of an electroluminescent device of Example 5 of the present invention.
4 is a power efficiency-current efficiency-voltage diagram of an electroluminescent device according to Embodiment 5 of the present invention.

Hereinafter, the product and the production method of the present invention will be described in detail with reference to specific examples. However, the scope of protection of the present invention is not limited by these specific embodiments.

Example 1

The synthesis method according to this embodiment is as follows.

(1) Synthesis of 8mCND (3-cyano-4-hydroxy-8-methyl-1,5-naphthyridine-3-carbonitrile)

In a 100 mL round-bottomed flask, 3.24 g (30 mmol) of 4-methyl-3-aminopyridine and 5.07 g (30 mmol) of 2-cyano-ethyl 3-ethoxyacrylate were added, Are mixed, 30 mL of toluene is added, and refluxed for 15 minutes under argon protection. Most of the toluene is evaporated to dryness and petroleum ether is added to precipitate the product. After filtration, dichloromethane / petroleum ether (volume ratio 1: 3) was recrystallized to obtain 6.51 g of pale yellow intermediate pre-8mCND crystal with a yield of 95%. _{1H NMR (400MHz, CDCI 3,} δ): 10.84 (br, d, J = 12.8Hz, 1H), 8.48 (s, 1H), 8.36 (d, J = 5.2Hz, 1H), 7.91 (d, J = J = 7.2 Hz, 3H), 2.39 (s, 3H), 1.38 (t, J = 7.2 Hz, 3H) (m / z, ESI): calcd for C 12 H 13 N 3 0 2 231, found232 (+ H +).

After drying in vacuo, 3.25 g of the intermediate is added to 250 mL of diphenyl ether and refluxed under argon protection for 4 hours. Upon cooling, the product precipitates, washed with a small amount of dichloromethane and then vacuum dried. The crude product is purified by sublimation (10-1 Pa, 220 [deg.] C) to give 1.66 g of a light yellow product, 8 mCND, with a yield of 65%. _{1H NMR (300MHz, D 2 O} , Na 2 C0 3, δ): 8.11 (dJ = 4.5Hz, 1H), 7.93 (s, 1H), 7.04 (d, J = 4.5Hz, 1H), 2.10 (s, 3H) .MS (m / z, ESI): calcd for C 10 H 7 N 3 O 185, found186 (+ H +) .EAforC 10 H 7 N 3 O: C, 64.86; H, 3.81; N, 22.69Found C, 64.86; H, 3.89; N, 22.60.

(2) Synthesis of europium complex Eu (8mCND) 3phen

366 mg (1 mmol) of europium chloride hexahydrate was dissolved in 20 mL of methanol, a methanol solution (30 mL) of phenanthroline (198 mg, lmmol) was added dropwise, and the mixture was stirred for 30 minutes. Then, a methanol solution of 8 mCND of sodium salt (555 mg of 8 mCND, 3 mmol, 3 mmol of NaOH, 100 mL of methanol) was slowly added dropwise and reacted at 50 ° C. for 2 hours. The reaction solution was concentrated to 30 mL, and the precipitated white solid was filtered. Washed with a small amount of water and methanol, and dried in vacuo to give 724 mg of the europium complex target product. The yield is 82%. MS (m / z, ESI): calcd for C ₄₂ H ₂₆ EuN ₁₁ O ₃ 885, found 886 (+ H ⁺ ).

Example 2

The synthesis method according to this embodiment is as follows.

(1) Synthesis of 3m8mND (3-methyl-4-hydroxyl-8-methyl-1,5naphthyridine, 3,8-dimethyl-1,5-naphthyridin-4-ol)

The synthesis of 3m8mND is similar to 8mCND and only the source 2-cyano-ethyl 3-ethoxyacrylate is replaced with 2-methyl-3-methoxyacrylate. In a 100 mL round bottom flask, 5.16 g (46 mmol) of 4-methyl-3-aminopyridine and 6.5 g (50 mmol) of 2-methyl-methyl 3-methoxyacrylate were mixed, 20 mL of toluene was added, Protected for 36 hours under protection. The toluene was evaporated to dryness and the precipitated unreacted starting material 4-methyl-3-aminopyridine was collected by filtration (3.5 g). The filtrate was able to separate the intermediate pre-3m8mND by column chromatography (eluent: dichloromethane / petroleum ether = 1: 1, volume ratio), and at the same time, 4.5 g of the raw material 2-methyl-3-methoxyacrylate Recall.

488 mg of a white solid intermediate pre-3m8mND is obtained, the yield being 5%. _{1H NMR (400MHz, CDCI 3,} δ): 9.82 (br, d, J = 12.8Hz, 1H), 8.36 (s, 1H), 8.12 (d, J = 4.8Hz, 1H), 7.24 (d, J = (S, 3H), 1.88 (s, 3H). MS (m / z, ESI): calcd for C ₁₁ H ₁₄ N ₂ O ₂ 206, found 207 (+ H ⁺ ).

The method for obtaining 3m8mND from the intermediate pre-3m8mND is the same as in Example 1, and the product 3m8mND is a pale yellow solid (300mg) and the yield is 77%. _{1H NMR (300MHz, D 2 O} , Na 2 CO 3, δ): 8.61 (d, J = 4.5Hz, 1H), 8.00 (s, 1H), 7.60 (d, J = 4.5Hz, 1H), 2.67 ( s, 3H), 2.24 (s , 3H) .MS (m / z, ESI): calcd for C 10 H 10 N 2 O 174, found 175 (+ H +) .EA for C 10 H 10 N 2 O: N: 16.1; C: 68.95; H: 5.8 Found N: 16.0; C: 68.8; H: 5.8.

(2) Synthesis of europium complex Eu (3m8mND) 3phen

Complex of Eu (3m8mND) 3phen The europium complex Eu (3m8mND) 3phen was obtained by replacing 8mCND with a 3m8mND complex, and the yield was 95%. MS (m / z, ESI): calcd for C ₄₂ H ₃₅ EuN ₈ O ₃ 852, found 853 (+ H ⁺ ).

Example 3

The synthesis method according to this embodiment is as follows.

(1) Synthesis of Ac-CND (3-cyano-4-hydroxy-1,5-naphthyridine-3-carbonitrile)

Synthesis of Ac-CND is similar to 8Mcnd and only 4-methyl-3-aminopyridine is replaced with 2-acetyl-5-aminopyridine. 2-Acetyl-5-aminopyridine is obtained by reacting 2-cyano-5-aminopyridine with methyl Grignard reagent.

The yield of the intermediate pre-AcCND is 63%. _{1H NMR (300MHz, CDCI 3,} δ): 10.96 (br, d, J = 12.8Hz, 1H), 8.47 (d, J = 2.7Hz, 1H), 8.12 (d, J = 8.7Hz, 1H), 7.93 (d, J = 13.2 Hz, 1H), 7.54 (dd, J = 8.7, 2.7 Hz, 1H), 4.34 (q, J = 7.2 Hz, 2H) 7.2Hz, 3H) .MS (m / z, ESI): calcd for C 13 H 13 N 3 O 3 259, found 260 (+ H +).

The yield of the product Ac-CND is 40%. J = 8.7 Hz, 1H), 8.19 (d, J = 8.7 Hz, 1H), 8.28 (d, J = 2.71 (s, 3H) .MS ( m / z, ESI): calcd for C 11 H 7 N 3 O 2 213, found 214 (+ H +).

3.2 Synthesis of europium complex Eu (Ac-CND) 3

366 mg (1 mmol) of europium chloride hexahydrate was dissolved in 10 mL of methanol, and a methanol solution of sodium salt of Ac-CND (Ac-CND 642 mg, 3 mmol, NaOH 3 mmol, methanol 100 mL) was slowly dropped and reacted at 50 ° C for 2 hours And the solvent is evaporated to dryness. The salts are removed with a small amount of water, washed with a small amount of methanol, and then vacuum dried to obtain the target product of the europium complex. The yield is 90%. MS (m / z, ESI): calcd for C ₃₃ H ₁₈ Eu ₉ O ₆ 789, found 790 (+ H ⁺ ).

Example 4

The synthesis method according to this embodiment is as follows.

(1) Synthesis of pyND (6- (pyridin-2-yl) -4hydroxyl-1,5 naphthyridine, 6- (pyridin- 2- yl) -1,5- naphthyridin-

A mixture of 2 g (11.7 mmol) of 5-amino-2,2'-dipyridyl, 2.52 g (17.5 mmol, 1.5 gq) of ISOPROPYLIDENE MALONATE, 8.65 g (58.4 mmol, When methoxymethane is mixed and heated to 100 DEG C under argon gas protection, a white slurry-like substance appears immediately. After 5 minutes, stop the heating, cool and add 50 ml of methanol. The white solid powder is filtered and washed several times with methanol. Drying yielded an intermediate product, pre-pyND, with a yield of 92%. _{1H NMR (400MHz, CDCI 3,} δ): 11.34 (br, d, J = 14.0Hz, 1H), 8.71 ~ 8.67 (m, 2H), 8.63 (d, J = 2.7Hz, 1H), 8.54 (d, J = 8.6 Hz, 1H), 8.40 (d, J = 7.9 Hz, 1H), 7.87-7.83 (m, 1H), 7.74 (dd, J = 8.9, 2.7 Hz, 1H), 7.36-7.34 ), 1.78 (s, 6H) .MS (m / z, ESI): calcd for C 17 H 15 N 3 O 4 325, found 326 (+ H +).

The method of synthesizing the product pyND from the intermediate is the same as that of 8 mCND, and the yield is 84%. (M, 2H), 8.60 (d, J = 7.9 Hz, 1H), 8.12 (d, J = 9.1 Hz, 1H) ), 7.94 ~ 7.88 (m, 2H), 7.42 ~ 7.40 (m, 1H), 6.36 (d, J = 7.2Hz, 1H) .MS (m / z, ESI): calcd for C 13 H 9 N 3 0 ^{223, found 224 (+ H +} ) .EA for C 13 H 9 N 3 O: N: 18.82; C: 69.95; H: 4.06 Found N: 18.86; C: 70.12; H: 4.10.

(2) Synthesis of europium complex Eu (pyND) 3:

(Ac-CND) ₃ , Ac-CND is substituted for the ligand pyND, and the yield is 90%. MS (m / z, ESI) calcd for C ₃₉ H ₂₄ EuN ₉ O ₃ 819, found 820 (+ H ⁺ ) .EA for C ₃₉ H ₂₄ EuN ₉ O ₃ .2H ₂ O: N: 14.75; C: 54.81; H: 3.30 Found N: 14.74; C: 55.45; H: 3.40.

Example 5

(1) Photoluminescence property

Taking europium complex Eu (8mCND) ₃ as an example, the photoluminescence quantum yield obtained by measurement using a dipyridyl lutetium aqueous solution as a reference ratio is about 40% (oxygen is not removed in the acetonyltri solution) I'm in a level. As shown in FIG. 1, in view of the excitation spectrum (EuL ₃ -ex) and the emission spectrum (EuL ₃ -em) of the complex, this type of europium complex can not only absorb ultraviolet rays but also down- conversion, and can be used as a red fluorescent powder in an LED. (For example, Y ₂ O ₃ : Eu ³⁺ ), the fluorescent quantum yield is higher than that of the inorganic red fluorescent powder which is currently used. In addition, the complex molecular structure is relatively compact, quenching is difficult to occur, and the light emitting thermal stability is good. When such a europium complex is used for the LED fluorescent powder, the capacity of the rare earth Eu can be effectively reduced, and the cost can be greatly reduced.

(2) Fabrication of electroluminescent device

The material used in the rare earth-europium complex electroluminescent device of this embodiment includes a conductive glass (ITO) base layer and the hole transport layer is made of N, N'-diphenyl-N, N'-bis (1-naphthyl) -1 (NPB), Eu (8mCND) ₃ was used as a light emitting layer, and 2,9-dimethyl-4,7-diphenyl-1, 10-phenanthroline (BCP) is used, the electron transport layer is 8-hydroxyquinolinate aluminum (AIQ), and the cathode layer is magnesium silver alloy. The device structure can be expressed by ITO / NPB (30 nm) / Eu: BCPO (1: 1, 20 nm) / BCP (10 nm) / AIQ (30 nm) /Mg0.9Ag0.1.

The electroluminescent device can be manufactured by a method known in the art and can be produced, for example, by the method disclosed in the reference (Appl. Phys. Lett. 1987, 51, 913). Specifically, a hole transporting material, a light emitting material, an electron transporting material, and a cathode material are sequentially deposited on a conductive glass (ITO) substrate cleaned under a high vacuum (lower than 8 × 10 ^-5 Pa).

ITO glass sheet (effective area of 3 × 3mm ²⁾ each using a crystal oscillator, under the three ultrasonic cleaning with an organic solvent and then dried, after washing with ozone into a vacuum film coating, is lower than 8 × 10 ^-5 Pa vacuum conditions (Mg _0.9 Ag _0.1 ) are sequentially deposited on the conductive glass to control the thickness of the layer, the hole transporting material, the organic small molecule, the electron transporting material, and the metal cathode magnesium. The thickness of each organic layer can be changed.

When measuring device performance and electroluminescence spectrum, the ITO electrode is always connected to the anode. The measurement of the electroluminescence spectrum is performed by applying a positive pressure (usually between 3 and 30 volts) to the device in the PR650 spectrometer or Hitachi F4500 fluorescence spectrometer and recording the emission spectrum (see FIG. 3).

The voltage-current (I-V) curves and the voltage-luminance (L-V) curves are measured with a Keithley 2400 source meter unit controlled by a computer and the luminance is controlled by a silicon photodiode (see FIG.

The europium complex electroluminescent device starts to light up at 9V and becomes bright at 100 cd m ^-2 at 15.5V. The power efficiency at this time is 0.34 lm W ^-1 , the current efficiency is 1.67 cd A ^-1 , and the maximum luminance is 868 cd m ^-2 . This device is a moderate level in europium complex electroluminescence as a result of unoptimized. It is believed that the light emitting performance will be further enhanced by performing the optimization process.

Claims (10)

A europium complex characterized in that the structural formula is Eu (ND) _x A _y L _m :
ND is a 4-hydroxy-1,5-naphthyridine based anion ligand represented by the formula (I), A is a? -Diketone-based ligand, L is a coordination small molecule selected from water molecules, alcohol molecules, A neutral ligand selected from molecules of phenanthroline (phen), bipyridine (bpy), triarylphosphine oxide (ArPO) based structures and derivatives thereof; x = 1, 2 or 3, y = 0, 1 or 2, x + y = 3; m = 0, 1, 2 or 3;

Formula I
Wherein R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen substituted alkyl group, an alkenyl group, an alkynyl group, A substituted amino group, an alkoxy group, a carboxy group, an ester group, an acyl group, an acylamino group, an N-substituted acylamino group, an aryl group or a heteroaryl group. The method according to claim 1,
A europium complex having the structure represented by the formula (II):

(II)
In formula Ⅱ, R _1, R _2, R _3, R ₄ and R ₅ are each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen-substituted alkyl group, an alkenyl group, an alkynyl group, an amino group, N- A substituted or unsubstituted amino group, an alkoxy group, a carboxy group, an ester group, an acyl group, an acylamino group, an N-substituted acylamino group, an aryl group or a heteroaryl group, R ₅ does not contain a nitrogen or oxygen coordination point; A is a? -Diketone-based ligand, L is a neutral ligand selected from water molecules, alcohol molecules, coordination small molecules selected from acetone, molecules of phenanthroline, bipyridine, triarylphosphine oxide structure and derivatives thereof; x = 1, 2 or 3, y = 0, 1 or 2, x + y = 3; m = 0, 1, 2 or 3; 3. The method of claim 2,
A europium complex having one of the following structures:

In the formula, A, L, x, y and m are as defined in claim 2. 3. The method of claim 2,
A europium complex having the structure:

Wherein R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen substituted alkyl group, an alkenyl group, an alkynyl group, A substituted or unsubstituted amino group, an alkoxy group, a carboxy group, an ester group, an acyl group, an acylamino group, an N-substituted acylamino group, an aryl group or a heteroaryl group, and R ₅ does not contain a nitrogen or oxygen coordination point; R _a and R _b are each independently an aryl group, a heteroaryl group or a fluorine alkyl group; L is a neutral ligand selected from water molecules, alcohol molecules, coordination small molecules selected from acetone, molecules of phenanthroline, bipyridine, triarylphosphine oxide structure and derivatives thereof; x = 1 or 2, y = 1 or 2, x + y = 3; m = 0, 1, 2 or 3; The method according to claim 1,
Wherein R ₅ in the general formula (1) is a nitrogen or oxygen coordination-point containing group and the 4-hydroxy-1,5-naphthyridine based ligand is a tridentate anion ligand. In the complex Eu (ND) _x A _y L _m , -Diketone-based ligand, L is a neutral ligand selected from water molecules, alcohol molecules, coordination small molecules selected from acetone, molecules of phenanthroline, bipyridine, triarylphosphine oxide structure and derivatives thereof; x = 1, 2 or 3, y = 0, 1 or 2, x + y = 3; and m is 0, 1 or 2. 6. The method of claim 5,
Wherein said R < ₅ > is an aza five-membered ring aromatic group, an aza-6-membered ring aryl group or a carbonyl-containing group. The method according to claim 6,
A europium complex represented by the following formula (III) or (IV):

R ₁ , R ₂ , R ₃ and R ₄ each independently represents a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen-substituted alkyl group, an alkenyl group, an alkynyl group, A substituted amino group, an alkoxy group, a carboxy group, an ester group, an acyl group, an acylamino group, an N-substituted acylamino group, an aryl group or a heteroaryl group; R ₆ , R ₇ , R ₈ and R ₉ are each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen substituted alkyl group, an amino group, an N-substituted amino group or an alkoxy group; R ₁₀ is a hydroxyl group, an alkyl group, a halogen-substituted alkyl group, an amino group, an N-substituted amino group or an alkoxy group; A is a? -Diketone-based ligand, L is a neutral ligand selected from water molecules, alcohol molecules, coordination small molecules selected from acetone, molecules of phenanthroline, bipyridine, triarylphosphine oxide structure and derivatives thereof; x = 1, 2 or 3, y = 0, 1 or 2, x + y = 3; m = 0, 1 or 2. The method according to claim 1,
Wherein the europium complex is one of the following complexes:

A tridentate ligand having a structure represented by the following formula (1a) or (1b):

The tridentate ligands represented by the formulas la and lb all have a resonance structure of an enol type and a keto type. Wherein R ₁ , R ₂ , R ₃ and R ₄ are each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen substituted alkyl group, an alkenyl group, an alkynyl group, A carboxyl group, an ester group, an acyl group, an acylamino group, an N-substituted acylamino group, an aryl group or a heteroaryl group; R ₆ , R ₇ , R ₈ and R ₉ are each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group, a halogen substituted alkyl group, an amino group, an N-substituted amino group or an alkoxy group; R ₁₀ is a hydroxyl group, an alkyl group, a halogen-substituted alkyl group, an amino group, an N-substituted amino group or an alkoxy group. 9. A light-emitting material comprising a europium complex according to any one of claims 1 to 8.

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