TWI469976B - A pyrrole compound substituted with an aryl group containing a pyridyl group - Google Patents

Description

Pyrrole compound substituted with a pyridyl group-containing aryl group

The present invention relates to a compound which is a phosphorescent main emitter of an organic light-emitting diode, and more particularly to a pyrrole compound substituted with a pyridyl group-containing aryl group, wherein the pyridyl compound substituted with a pyridyl group-containing aryl group is A pyrrole compound substituted with an aryl group is formed with a pyridyl group.

The organic light-emitting diode device includes an organic light-emitting diode (OLED) and a driving element, wherein the organic light-emitting diode includes a light-emitting layer. In today's technology, the luminescent layer is almost always a host-guest illuminant system, that is, a phosphorescent guest is doped in the main illuminator, and the energy is transmitted to the illuminant by the main illuminator with higher energy. Luminescence, so the color and luminous efficiency emitted by the organic light-emitting diode are controlled by the interaction of the energy levels of the host and guest illuminants, and the host-guest illuminant system can avoid the concentration of the phosphorescent illuminant being too high. The triplet-triplet annihilation phenomenon avoids the reduction of component efficiency.

In order to avoid the phenomenon of phosphorescent energy return of phosphorescent luminescence, the main illuminant with high triplet energy is the focus of today's development. In addition, many materials used as phosphorescent main emitters vary greatly in hole transfer rate (about 10 ^-5 cm ² /Vs) and electron transfer rate (about 10 ^-6 to 10 ^-7 cm ² /Vs). The recombination rate of the hole and the electron in the luminescent layer is low, so that the OLED luminous efficiency is not good. The electron injection efficiency of the phosphorescent main emitter has a great influence on the operating voltage of the device. If the electron injection efficiency is low, a high operating voltage is required for the operation of the device, which leads to a decrease in the lifetime of the device. In order to solve the problem that the recombination rate of the hole and the electron is low, it can be achieved by increasing the electron injection/transfer rate of the main illuminant to improve the luminous efficiency of the OLED. In general, increasing the electron transfer rate also increases the efficiency of electron injection, thereby avoiding the problem of requiring high operating voltage and reduced component life.

"Synthesis and Photophysical Properties of Pyrrole/Polycyclic Aromatic Units Hybrid Fluorophores", published in the journal J. Org. Chem. in 2010, discloses an aryl-substituted pyrrole compound which is represented by formula (A): Medium, Ar represents

The compound represented by the formula (A) is a blue-emitting fluorescent compound, and the energy transfer by the central pyrazole and the peripheral substituent is promoted to increase the quantum efficiency of the fluorescent light, and the substitution by the steric effect is large. The base, as well as the rigid structure and large molecular weight, enhance the glass transition temperature and thermal cracking temperature of the compound, and have good thermal stability. At the same time, when the compound represented by the formula (A) is used as a phosphorescent main illuminant, the phosphorescent illuminant can be effectively dispersed, and at the same time, since the triplet energy is sufficiently large, the phosphorescent illuminant can be avoided due to the triplet-triple The states destroy each other and cause phosphorescence quenching. However, the compound represented by the formula (A) has a disadvantage that the electron transport rate is not satisfactory.

It can be seen from the above that if the electron transfer rate of the phosphorescent main illuminator can be increased, a phosphorescent main illuminator having a similar hole transport rate and electron transport rate is developed, which solves the low recombination rate of the hole and the electron in the luminescent layer. The problem is very helpful for the development of the organic light-emitting diode industry.

Accordingly, it is an object of the present invention to provide a pyrrole compound substituted with a pyridyl group-containing aryl group which has a high triplet energy and which can be used as a phosphorescent main illuminator and has similar electron transport rate and hole transport. rate.

Thus, the pyrrole compound substituted with a pyridyl group-containing aryl group of the present invention is represented by the following formula (I):

In the formula (I), G ¹ represents X ¹ -R ¹ or R ³ ; G ² represents X ² -R ¹ or R ² , with the proviso that at least one of G ¹ and G ² includes R ¹ ; and R represents C ₁ to C ₂₀ alkyl, wherein R ¹ represents X ¹ represents R ¹¹ and R ¹² each represent H or a C ₁ to C ₂₀ alkyl group, and R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ and R ¹⁷ each represent H or CH ₃ , provided that R ¹⁶ and R ^{17 are} not simultaneously CH ₃ ; R ³ means R ³¹ and R ³² each represent H or a C ₁ to C ₂₀ alkyl group, and R ³³ , R ³⁴ , R ³⁵ , R ³⁶ and R ³⁷ each represent H or CH ₃ , provided that R ³⁶ and R ^{37 are} not simultaneously CH ₃ ; X ² means ; and R ² means

The effect of the present invention is that the pyridyl group-containing aryl-substituted pyrrole compound having a novel structural design is introduced at a suitable substituent position to increase the electron transporting ability of R ¹ in the mutual interaction of G ¹ and G ² . The coordination length and the appropriate orientation selection control the resonance length of the pyrrole compound substituted by the pyridyl group-containing aryl group of the present invention, and is a phosphorescence having not only a high triplet energy but also a similar electron transport rate and a hole transport rate. The main illuminant, and at the same time a blue-violet fluorescent compound.

A pyrrole compound substituted with a pyridyl group-containing aryl group is represented by the following formula (I):

In the formula (I), G ¹ represents X ¹ -R ¹ or R ³ ; G ² represents X ² -R ¹ or R ² , with the proviso that at least one of G ¹ and G ² includes R ¹ ; and R represents C ₁ to C ₂₀ alkyl, wherein R ¹ represents X ¹ represents R ¹¹ and R ¹² each represent H or a C ₁ to C ₂₀ alkyl group, and R ¹³ , R ¹⁴ , R ¹⁵ , R ¹⁶ and R ¹⁷ each represent H or CH ₃ , provided that R ¹⁶ and R ^{17 are} not simultaneously CH ₃ ; R ³ means R ³¹ and R ³² each represent H or a C ₁ to C ₂₀ alkyl group, and R ³³ , R ³⁴ , R ³⁵ , R ³⁶ and R ³⁷ each represent H or CH ₃ , provided that R ³⁶ and R ^{37 are} not simultaneously CH ₃ ; X ² means ;and R ² represents

Preferably, R represents a C ₁ to C ₁₀ alkyl group.

Preferably, G ¹ represents X ¹ -R ¹ and G ² represents R ² . More specifically, the first preferred aspect of the pyrrole compound substituted with a pyridyl group-containing aryl group of the present invention is represented by the formula (I-1):

In the first preferred embodiment, preferably, X ¹ represents , R ¹ represents , R ² means

Preferably, G ¹ represents R ³ and G ² represents X ² -R ¹ . More specifically, a second preferred aspect of the pyrrole compound substituted with a pyridyl group-containing aryl group of the present invention is represented by the formula (I-2):

In a second preferred embodiment, preferably, R ³ represents , X ² means And R ¹ represents

Preferably, G ¹ represents X ¹ -R ¹ and G ² represents X ² -R ¹ . More specifically, a third preferred aspect of the pyrrole compound substituted with a pyridyl group-containing aryl group of the present invention is represented by the formula (I-3):

In the third preferred embodiment, preferably, wherein X ¹ and X ^{2 are both} represented , R ¹ represents

The structures of the first, second and third preferred examples of the pyrrole-containing aryl-substituted pyrrole compound of the present invention are as follows:

The pyrrole compound substituted by the pyridyl group-containing aryl group of the present invention can be prepared according to the change of X ¹ , X ² , R ¹ , R ² and R ³ by using appropriate reactants and reaction conditions, and the reaction preparation method can be based on the industry. The well-known techniques change. In a specific example of the present invention, the pyrrole compound substituted with a pyridyl group-containing aryl group is obtained by first synthesizing an aryl-substituted pyrrole compound by the Paal-Knorr condensation method [formula (I ₀ ) in the following reaction formula], followed by According to the following reaction formula, pyridine-3-boronic acid is reacted with the aryl-substituted pyrrole compound represented by formula (I ₀ ) to obtain a pyridyl group-containing aromatic group of the present invention. Substituted pyrrole compound [formula (I)]: Wherein G ¹⁰ represents X ¹ -Y or R ³ and G ²⁰ represents X ² -Y or R ² , Y represents a halogen atom or OSO ₂ CF ₃ , and X ¹ , X ² , R ² and R ³ are as defined above Defined. In the above reaction formula, pyridine-3-boronic acid can be replaced by other boronic acid derivatives, such as, but not limited to, pyridine-3-boronic acid pinacol ester, pyridine-3-borate B. Pyridine-3-boronic acid ethanediol ester, pyridine-3-boronic acid 1,3-propanediol ester. Palladium (II) acetate, Pd(OAc) ₂ can be replaced by other palladium catalysts, such as but not limited to: Tetrakis (triphenylphosphine) palladium (0), abbreviated as Pd (PPh) ₃ ) ₄ ] or tris(dibenzylideneacetone) dipalladium (0), abbreviated as Pd ₂ (dba) ₃ ]. 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (Sphos for short) can be replaced by other ligands such as, but not limited to, triphenyl Triphenylphosphine (PPh ₃ ), 2-dicyclohexylphosphino-2', 4', 6'-triisopropylbiphenyl (Xphos) , Tricyclohexylphosphine (PCy ₃ ), 2-dicyclohexylphosphino-2'-(N,N-dimethylamino)biphenyl (2-Dicyclohexylphosphino-2'-(N,N-dimethylamino) Biphenyl, abbreviated as BPCy ₂ ), 2,2'-bisdiphenylphosphino-1,1'-diphenylphosphino-1,1'-binaphthyl, BINAP for short, or 1,1 '-1,1'-bis(diphenylphosphanyl)ferrocene, abbreviated as DPPF. Potassium phosphate (K ₃ PO ₄ ) can be replaced with other bases such as, but not limited to, potassium fluoride (KF) or potassium carbonate (K ₂ CO ₃ ).

The pyrrole compound substituted by the pyridyl group-containing aryl group of the invention has the following characteristics: (1). It has a good performance in the triplet energy and can be used as a phosphorescent host material, and can be used as a sky blue phosphorescent illuminant, green light. The main illuminant material of the phosphorescent guest and the red phosphorescent guest. The pyrrole compound substituted with a pyridyl group has a preferred triplet energy for two reasons. First, the molecular structure of the pyrrole compound substituted with a pyridyl group-containing aryl group can effectively limit the resonance length extension, and thus can Has a high triplet energy. Second, by using the orientation selectivity, the resonance of the nitrogen atom on R ¹ with X ¹ (or X ² ) is shifted in a meta position, so that the resonance effect of the nitrogen atom on the triplet energy can be limited; (2). The nitrogen atom of R ¹ is easily oxidized to lose electrons and can serve as an electron donor. R ¹ itself lacks electrons and can also act as an electron acceptor. Therefore, G ¹ and G ² can simultaneously serve as electron donors and electron acceptors. The ability to simultaneously transfer electrons and holes; (3). In addition to introducing R ¹ , the electron transfer rate of the pyridyl group-substituted azole compound can be improved, and the pyridyl group-containing aryl group can also be substituted. The LUMO energy level of the pyrrole compound can reduce the energy barrier of electrons injected into the electron transport layer from the electrode when applied to the OLED device, thereby improving the efficiency of electron injection; (4) by the positions of G ¹ and G ² Selectively controlling the resonance length of the pyridyl compound substituted with a pyridyl group-containing aryl group to adjust the light-emitting wavelength to emit blue-violet fluorescence; (5) the glass capable of stabilizing the film due to sufficient steric effect Type.

The present invention will be further illustrated by the following examples, but it should be understood that this embodiment is intended to be illustrative only and not to be construed as limiting.

<Example>

[Example 1] 1-ethyl-2,5-bis[4-(pyridin-3-yl)phenyl]-3,4-di(naphthalen-2-yl)-1 H -pyrrole (hereinafter referred to as PPN) Preparation

3 g (3.76 mmol) of 1-ethyl-2,5-bis[4-(trifluoromethylsulfonate)phenyl]-3,4-di(naphthalen-2-yl)-1 H -1-ethyl-2,5-bis(4-trifluoromethanesulfonylphenyl-3,4-bis(naphthalen-2-yl)-1 H- pyrrole, for the synthesis method, see J. Org. Chem. , 2010, 75 , 4004.] After placing in a one-neck round bottom flask, the flask was dehydrated using a vacuum system, followed by the addition of 1 g (7.9 mmol) of pyridine-3-boronic acid, 0.033 g (0.15 mmol) under argon. Palladium acetate (Palladium (II) acetate, SIGMA-ALDRICH, purity 99.9%], 0.18 g (0.45 mmol) of 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (2-dicyclohexylphosphino) -2',6'-dimethoxybiphenyl (SPhos), after deoxidation by vacuum system, 6 ml of anhydrous tetrahydrofuran (tetrahydrofuran, manufactured by Merck) was added to the side neck round bottom flask. Another 5.7 ml of a 2 M aqueous solution of depleted potassium phosphate (K ₃ PO ₄ ) (containing about 11.28 mmol of tripotassium phosphate) was added to the side neck round bottom flask and heated to reflux for 48 hours. The tetrahydrofuran was removed by a rotary concentrator to obtain a crude product. The crude product was dissolved in ethyl acetate, and the crude product was washed with water, and then the ethyl acetate solution was collected, and the ethyl acetate solution was dried over anhydrous magnesium sulfate, and then purified by column chromatography ( The extract was n-hexane: ethyl acetate = 2:1) to give 1.5 g of white powdery product (PPN), yield 61%.

Spectral analysis of PPN: ¹ H-NMR (500 MHz, CD ₂ Cl ₂ ), δ (ppm): 1.07 (t, J = 8.5 Hz, 3H), 4.04 (q, J = 8.5 Hz, 2H), 7.16 ( d, d, J = 10.5 Hz, 2H), 7.38 (m, 6H), 7.55 (m, 10H), 7.63 (d, J = 8 Hz, 4H), 7.68 (d, t, J = 8 Hz, 2H ), 7.92 (d, 12 Hz, 2H), 8.56 (d, d, J = 6 Hz, 2H), 8.87 (s, d, J = 1.5 Hz, 2H); ¹³ C-NMR (75 MHz, CDCl _{3 )} ), δ (ppm): 17.1, 40.0, 123.0, 123.8, 125.3, 125.6, 127.1, 127.2, 127.6, 128.0, 129.5, 129.8, 131.4, 131.7, 132.3, 133.2, 133.2, 133.5, 134.5, 136.2, 136.9, 148.4 , 148.8.

[Example 2] 1-ethyl-2,5-di(naphthalen-2-yl)-3,4-bis[4-(pyridin-3-yl)phenyl]-1 H -pyrrole (hereinafter referred to as NPP) Preparation

0.5 g (0.76 mmol) of 1-ethyl-2,5-di(naphthalen-2-yl)-3,4-bis(4-bromophenyl)-1 H -pyrrole [1-ethyl-2, 5-bis (naphthalen-2- yl) -3,4-bis (4-bromophenyl) -1 H -pyrrole, synthetic methods see Tetrahedron, 2007, 63, 7086] the neck round bottom flask was placed side by The flask was dewatered by a vacuum system, then 0.2 g (1.6 mmol) of pyridine-3-boronic acid, 0.018 g (0.03 mmol) of palladium acetate, 0.1 g (0.09 mmol) of SPhos were added under argon, and the vacuum was again utilized. After the system was deoxygenated, 6 ml of anhydrous tetrahydrofuran was added to the side neck round bottom flask. Another 1.2 ml of a 2 M aqueous solution of depleted potassium phosphate (K ₃ PO ₄ ) (containing about 2.4 mmol of tripotassium phosphate) was added to the side neck round bottom flask and heated to reflux for 48 hours. The tetrahydrofuran was removed by a rotary concentrator to obtain a crude product. The crude product was dissolved in ethyl acetate, and the crude product was washed with water, and then ethyl acetate was evaporated. The crude product was purified by column chromatography (ethyl acetate) to yield 0.5 g of white powder (NPP).

Spectroscopic analysis of NPP: ¹ H-NMR (500 MHz, CD ₂ Cl ₂ ), δ (ppm): 0.97 (t, J = 7 Hz, 3H), 3.99 (q, J = 7 Hz, 2H), 7.16 ( d, J = 8.5 Hz, 4H), 7.27 (d, d, J = 5 Hz, 2H), 7.33 (d, J = 8.5 Hz, 4H), 7.52 (m, 6 H), 7.80 (d, J = 8 Hz, 2H), 7.88 (m, 6 H), 7.96 (s, 2 H), 8.47 (d, J = 5 Hz, 2H), 8.73 (s, 1 H); ¹³ C-NMR (75 MHz, CDCl ₃ ), δ (ppm): 17.1, 39.9, 122.0, 123.6, 126.4, 126.5, 126.6, 128.0, 128.2, 128.4, 129.5, 130.7, 130.7, 131.6, 131.7, 132.8, 133.4, 134.2, 134.4, 135.8, 136.5 , 148.2.

[Example 3] Preparation of 1-ethyl-2,3,4,5-tetrakis[4-(pyridin-3-yl)phenyl]-1H-pyrrole (hereinafter abbreviated as PPP)

(1). 1-Ethyl-2,5-bis[4-(trifluoromethylsulfonate)phenyl]-3,4-di(4-bromophenyl)-1 H -pyrrole [1 Synthesis of -ethyl-2,5-bis(4-trifluoromethanesulfonylphenyl)-3,4-bis(4-bromophenyl)-1 H -pyrrole]

0.5 g (0.8 mmol) of 1-ethyl-2,5-bis(4-methoxyphenyl)-3,4-bis(4-bromophenyl)-1 H -pyrrole [1-ethyl- 2,5-bis (4-methoxyphenyl) -3,4-bis (4-bromophenyl) -1 H -pyrrole, synthetic methods see Tetrahedron, 2007, 63, 7086] after unilateral neck round bottom flask was placed, was added 27 ml of anhydrous dichloromethane to dissolve 1-ethyl-2,5-bis(4-methoxyphenyl)-3,4-di(4-bromophenyl)-1 H -pyrrole to form a The solution was then slowly dropped into the side neck round bottom flask with 2.43 ml of boron tribromide (concentration: 1 M in DCM) using an addition funnel in an ice bath, at which time the solution gradually changed from deep yellow to Dark brown, after adding boron tribromide for one hour, then remove the ice bath, and then react at 25 ° C for 9 hours, at which time some products will precipitate, and the side neck round bottom flask is moved to the ice bath. Ice water was added dropwise to terminate the reaction, and then dichloromethane was distilled off by distillation under reduced pressure. The extraction was carried out with ethyl acetate and deionized water, and the aqueous layer was changed from acidic to neutral by using a wide test paper to complete the extraction, and the collected ethyl acetate solution (organic layer) was dehydrated with anhydrous magnesium sulfate. After drying, it was reprecipitated with ethyl acetate and n-hexane (ethyl acetate: n-hexane = 1: 20) to give a white solid. The white solid was dissolved in 15.8 mL of anhydrous dichloromethane, and then 0.234 g (2.4 mmol) of triethylamine was added to form a mixture. Then, 0.668 g (2.4 mmol) of trifluoromethanesulfonic anhydride was slowly added dropwise to the mixture under ice bath, at which time the mixture turned from dark yellow to dark green and then reacted at room temperature. After 12 hours, 10 ml of a 1 M aqueous solution of ammonium chloride was added dropwise to terminate the reaction, followed by distilling off the dichloromethane under reduced pressure and extracting with ethyl acetate and deionized water. The ethyl ester solution (organic layer) was dried over anhydrous magnesium sulfate, and then purified by column chromatography (hexane: ethyl acetate = 4:1) to give 0.45 g of white powdery solid [ 1-ethyl-2,5-bis[4-(trifluoromethylsulfonate)phenyl]-3,4-di(4-bromophenyl)-1 H -pyrrole], yield 66 %.

(2). Synthesis of PPP

1.9 g (2.22 mmol) of 1-ethyl-2,5-bis(4-(trifluoromethylsulfonate)phenyl)-3,4-bis(4-bromophenyl)-1 H After the pyrrole was placed in a one-neck round bottom flask, water was removed by a vacuum system, followed by addition of 1.22 g (9.76 mmol) of pyridine-3-boronic acid, 0.02 g (0.09 mmol) of palladium acetate, 0.11 under argon. Grams (0.26 mmol) of SPhos, and 23 ml of anhydrous tetrahydrofuran. Another 6.9 ml of a 2 M aqueous solution of deoxygenated tripotassium phosphate (containing about 13.8 mmol of tripotassium phosphate) was added to the side neck round bottom flask and heated to reflux for 120 hours. The tetrahydrofuran was removed by a rotary concentrator, and then purified by column chromatography (eluent ethyl acetate) to give 1.34 g of white powdery product (PPP).

Spectroscopic analysis of PPP: ¹ H-NMR (500 MHz, CD ₂ Cl ₂ ), δ (ppm): 1.04 (t, J = 8.5 Hz, 3H), 3.95 (q, J = 8.5 Hz, 2H), 7.16 ( d, J = 8.5 Hz, 4H), 7.30 (q, J = 8 Hz, 2H), 7.38 (m, 6H), 7.54 (d, J = 8 Hz, 4H), 7.67 (d, J = 8 Hz, 4H), 7.84 (d, t, J = 8 Hz, 2H), 7.96 (d, t, J = 8 Hz, 2H), 8.49 (d, d, J = 6 Hz, 2H), 8.58 (d, d , J = 6 Hz, 2H), 8.76 (s, d, J = 2 Hz, 2H), 8.90 (s, d, J = 2 Hz, 2H); ¹³ C-NMR (75 MHz, CDCl ₃ ), δ (ppm): 17.063, 39.93, 122.19, 123.71, 123.89, 126.49, 127.26, 131.25, 131.66, 132.28, 132.96, 134.2, 134.5, 134.5, 135.6, 136.2, 136.5, 137.1, 148.2, 148.2, 148.4, 148.8.

[evaluation project]

To facilitate the description of the measurement procedure, the compounds of Examples 2 to 3 were all measured in the same manner as described below for the nature of the compounds of Example 1. The test results of the properties of the compounds of Examples 1 to 3 are shown in Table 1.

Ultraviolet/visible absorption spectroscopy

The compound of Example 1 was first dissolved in methylene chloride (concentration: 1.0 × 10 ^-5 M), and the compound of Example 1 was measured in a solution by an ultraviolet/visible spectrometer (label: Hitachi, model: U-3010). Absorption spectrum in the state (measurement conditions: concentration: 1.0 × 10 ^-5 M, measurement range: 200 nm to 700 nm, scanning rate: 1200 nm/min.), the maximum absorption wavelength and secondary absorption of the compound of Example 1 were obtained. wavelength.

Fluorescence emission spectrum:

After dissolving the compound of Example 1 in methylene chloride (concentration: 1.0 × 10 ^-6 M), the compound of Example 1 was measured in a solution state by a fluorescence spectrometer (label: Hitachi, model: F-4500). The emission spectrum (measurement conditions: concentration: 1.0 × 10 ^-6 M, measurement range: 200 nm to 700 nm, scanning rate: 1200 nm/min.), the maximum fluorescence emission wavelength of the compound of Example 1 was obtained.

Fluorescence quantum efficiency

9,10-diphenylanthrance was used as a standard (the fluorescence quantum efficiency of 9,10-diphenylfluorene in dichloromethane was 0.9). The compound of Example 1 and 9,10-diphenylfluorene were respectively dissolved in dichloromethane, and the ultraviolet/visible absorption spectrum of the compound of Example 1 and 9,10-diphenylfluorene was measured (concentration: 1.0×10). ^-5 M) and fluorescence emission spectrum (concentration: 1.0 × 10 ^-6 M), and taking the absorption of the maximum absorption wavelength and the integral area of the fluorescence emission spectrum, and then using the following formula (Formula I) to obtain an example 1 Fluorescence quantum efficiency of the compound (Φ _p1 ).

Φ _p1 =(F _s /F _r )×(A _r /A _s )×Φ _s (Formula I)

Φ _p1 : fluorescence quantum efficiency of the analyte

F _s : integral area of the fluorescence spectrum of the analyte

F _r : integral area of the standard fluorescence spectrum

A _s : absorbance of the analyte at the maximum absorption wavelength

A _r : absorbance of the standard at the maximum absorption wavelength

Φ _s : Fluorescence quantum efficiency of the standard

Triplet energy (triplet energy, E _T ):

The emission peak (λ) having the shortest wavelength (i.e., the largest energy) was found from the phosphorescence spectrum of the compound of Example 1, and was calculated by the following formula (II) to obtain the triplet energy (E _T ) of the compound of Example 1:

Thermal stability:

(1). Melting point (T _m ) and glass transition temperature (T _g )

The melting point (T _m ) and glass transition temperature (T _g ) of the compound of Example 1 were measured using Differential Scanning Calorimetry (DSC, brand: Perkin Elmer, model: Pyris 6 DSC). The thermal stability was measured in four stages under a nitrogen atmosphere. The operating conditions for each stage were: a heating rate of 10 ° C / min., a temperature increase from 30 ° C to 350 ° C, and a cooling rate of 10 ° C / Min., from 350 ° C to 30 ° C.

(2). Thermal cracking temperature (T _d )

The thermal cracking temperature (T _d ) of the compound of Example 1 was measured using a Thermogravimetry Analyzer (TGA, label: Perkin Elmer, model: Pyris 1 TGA). The compound of Example 1 was placed in a nitrogen atmosphere at 30 ° C for 1 minute, followed by a temperature increase rate of 10 ° C / min., from 30 ° C to 120 ° C and maintained for 10 minutes to remove the moisture and residual of the compound of Example 1. After the solvent, the temperature was lowered to room temperature of 30 ° C, and then the temperature was raised to 10 ° C / min., and the temperature was raised to 900 ° C, and the temperature at which the compound of Example 1 was subjected to 5% weight loss was measured, which is the thermal cracking temperature of the compound of Example 1. (T _d ).

The higher the melting point (T _m ), glass transition temperature (T _g ) and thermal cracking temperature (T _d ) temperature of the compound, the better the thermal stability of the compound.

Electrochemical properties:

(1). Oxidation reduction potential

The oxidation-reduction potential of the compound of Example 1 was measured using a cyclic voltammetry (Cyclic Voltammetry, CV, brand name: CHI 611A Electrochemical Analyzer), and the oxidation potential indicates that the compound received a hole. Capacity, the reduction potential indicates the ability of a compound to receive electrons, so it is known whether a compound has the ability to transfer electrons/holes.

When the oxidation potential was measured, the compound of Example 1 was dissolved in a 0.1 M solution of tetrabutylammonium hexafluorophosphate (TBAP) in a dichloromethane electrolyte solution using dichloromethane as a solvent to prepare 1×10. a solution of ^-3 M with a glassy carbon as a working electrode, an Ag/Ag ⁺ electrode as a reference electrode, and a platinum electrode as a counter electrode with a measurement range of 0 V Up to 1.7 V, the scan rate is 0.05 V/s. When the reduction potential was measured, the compound of Example 1 was dissolved in a 0.1 M solution of tetramethylphosphonium hexafluoride in dimethylformamide, using dimethylformamide as a solvent, to prepare a 1×10 solution. ^-3 M solution with a measurement range of 0 V to 1.7 V and a scan rate of 0.1 V/s.

(2). HOMO and LUMO values

The measured oxidation potential is calculated by using ferrocene (oxidation potential: -4.8 eV) as the reference potential, and the HOMO energy level is calculated. The reduction potential is TPBi (reduction potential: -2.7 eV) as the reference potential, and the LUMO energy level is calculated. .

HOMO=-(E _ox -E _1/2 , _ferrocene )+(-4.8)

LUMO=-(E _red -E _1/2 , _TPBi )+(-2.7)

Electron transfer rate and hole transfer rate:

After depositing a first silver electrode (film thickness: 30 nm) on a glass substrate, the compound of Example 1 was evaporated on the first silver electrode as a light-emitting layer (film thickness L: 1800 nm), and then A second silver electrode (film thickness: 150 nm) was deposited on the light-emitting layer to form a test element. The laser light is excited by the laser light, and the electric field intensity (E) and the transient photocurrent of the test element are measured by applying a bias voltage, and the charge drift time (t _τ ) is obtained from the change of the transient photocurrent. The film thickness (L) of the light-emitting layer and the electric field strength (E) of the test element, that is, the electron transport rate and the hole transport rate (μ) were obtained.

It can be seen from the data in Table 1 that: (1) The compounds of Examples 1 to 3 can be used as a sky blue phosphorescent guest, a green phosphorescent guest, and a red phosphorescent guest due to a triplet energy of 2.43 to 2.56 eV. The main illuminant of the body can effectively avoid the phenomenon of phosphorescent energy return; (2) The compounds of Examples 1 and 2 have similar electron transfer rate and hole transfer rate (all grades of 10 ^-5 power) It can improve the recombination rate of electrons and holes in the luminescent layer. While the compound of Example 3 is known by cyclic voltammetry to have an oxidation-reduction potential, and thus has the ability to simultaneously transport electrons and holes, the compound of Example 3 includes both -X ¹ -R ¹ and -X ² -R ¹ Therefore, it is also possible to determine from the electron transport rate and the hole transport rate of the compounds of Examples 1 and 2 that the compound of Example 3 should also have similar electron transport rate and hole transport rate; (3) Compounds of Examples 1 to 3 It has excellent performance at melting point, glass transition temperature and thermal cracking temperature, and therefore has good thermal stability; (4). The fluorescence emission wavelengths of the compounds of Examples 1 to 3 are 423 to 439 nm, and can be used as A dark blue/blue-violet fluorescent compound.

In summary, the pyrrole compound substituted with a pyridyl group-containing aryl group of the present invention, by introducing R ¹ at a suitable substituent position to increase electron transporting ability, in the mutual coordination of G ¹ and G ² and an appropriate position To select and control the resonance length of the pyrrole compound substituted by the pyridyl group-containing aryl group of the present invention, so that not only has high triplet energy, but also has similar electron transfer rate and hole transfer rate, and is currently a small number of simultaneously transmitting electrons and Phosphorescent main illuminator with hole capability. The pyrrole compound substituted by the pyridyl group-containing aryl group of the present invention is simultaneously a blue-violet fluorescent compound, has good thermal stability, and the formed film has a stable glass form.

The above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto, that is, the simple equivalent changes and modifications made by the patent application scope and patent specification content of the present invention, All remain within the scope of the invention patent.

Claims (7)

A pyrrole compound substituted with a pyridyl group-containing aryl group is represented by the following formula (I): In the formula (I), G ¹ represents -X ¹ -R ¹ or R ³ ; G ² represents -X ² -R ¹ or R ² , with the proviso that at least one of G ¹ and G ² includes R ¹ ; R represents a C ₁ to C ₂₀ alkyl group, wherein R ¹ represents , , , , or X ¹ represents , , , R ³ means , , , X ² indicates ; and R ² means , , , The pyrrole group-substituted aryl-substituted pyrrole compound according to claim 1, wherein G ¹ represents -X ¹ -R ¹ , and G ² represents R ² . The pyrrole group-substituted aryl-substituted pyrrole compound according to claim 2, wherein X ¹ represents , R ¹ represents , R ² means The pyrrole group-substituted aryl-substituted pyrrole compound according to claim 1, wherein G ¹ represents R ³ and G ² represents -X ² -R ¹ . The pyrrole group-substituted aryl-substituted pyrrole compound according to claim 4, wherein R ³ represents , X ² means And R ¹ represents . The pyrrole group-substituted aryl-substituted pyrrole compound according to claim 1, wherein G ¹ represents -X ¹ -R ¹ , and G ² represents -X ² -R ¹ . The pyrrole group-substituted aryl-substituted pyrrole compound according to claim 6, wherein both X ¹ and X ² represent , R ¹ represents .