CN107382994A - Oxadiazole loop coil aromatic hydrocarbons steric hindrance type bipolarity luminescent material of 2,5 diphenyl 1,3,4 and preparation method thereof - Google Patents

Abstract

The 2,5-diphenyl-1,3,4-oxadiazole spiro aromatic hydrocarbon sterically hindered bipolar light-emitting material and its preparation method relate to the third generation of light-emitting display materials and technologies, because of its 2,5-di Phenyl‑1,3,4‑oxadiazole has good electron transport properties and spiro aromatic hydrocarbons have excellent hole transport properties, bulky steric hindrance effect and its non-conjugated connection with high triplet energy level, This type of compound has excellent bipolar transport properties, and the introduction of large-volume spiro aromatic hydrocarbon functional groups enables this type of material to have a three-dimensional large-volume steric hindrance effect, which can greatly improve the stability of the material's amorphous state, so it can be widely used in Organic Light Emitting Diodes. This type of material has the following characteristics: (1) high triplet energy level; (2) high luminous efficiency, high thermal decomposition temperature and glass transition temperature; (4) bipolar transport characteristics; (3) three-dimensional large Volume steric hindrance effect; (5) The synthesis method is simple and easy.

Description

2,5-Diphenyl-1,3,4--Oxadiazole spiro aromatic hydrocarbon sterically hindered bipolar luminescent material and its preparation method

technical field

The present invention specifically relates to a preparation method based on the functional modification of 2,5-diphenyl-1,3,4-oxadiazole using spiro aromatic hydrocarbons, and relates to the steps and raw materials used in the preparation process of these materials .

Background technique

Since the pioneering work first reported by Tang et al. in 1987, organic light-emitting diodes (OLEDs) have been favored due to their light weight, wide viewing angle, high contrast, wide and cheap source of raw materials, self-illumination, large-area flexible display, and fast response. Applications are gaining increasing attention in the areas of flat panel displays and solid state lighting. However, traditional fluorescent organic light-emitting diodes are limited by a maximum internal quantum efficiency of 25% because they can only use singlet excitons to emit light, and their external quantum efficiency can only reach a maximum of 5%. Phosphorescent organic light-emitting devices (PhOLEDs) can use singlet and triplet excitons due to heavy metal spin-orbit coupling, so that the internal quantum efficiency can theoretically reach 100%. Compared with traditional fluorescent organic light-emitting diodes with an internal quantum efficiency of 25%, phosphorescent organic light-emitting diodes (PhOLEDs) have greater commercial application value, so they are regarded as the most potential full-color display and solid-state lighting technologies.

In order to meet the needs of full-color display, organic electroluminescent devices with many fluorescent and phosphorescent guest materials have been developed one after another. Phosphorescent organic light-emitting diodes have aroused great interest among scientists because of the spin-orbit coupling effect of heavy metals, which makes their internal quantum efficiency theoretically reach 100%.

However, the long lifetime of excitons in phosphorescent guest materials makes it easy to produce concentration quenching, triplet annihilation and other phenomena under the condition of high doping concentration. In order to solve this problem, scientists usually adopt a host-guest doping system to uniformly disperse the guest material into the host material, so as to effectively solve the above problem and make the phosphorescent organic light-emitting diode emit light efficiently. In addition, due to the imbalance of hole and electron injection/transport in unipolar host materials, the exciton recombination region is narrow and the device efficiency is reduced; in order to improve device performance, people often use complex multilayer device structure design to improve device efficiency. However, this will increase or decrease the device manufacturing difficulty, increase the cost, and do not take advantage of the commercialization of organic light-emitting diodes. Therefore, the design and synthesis of host materials with bipolar transport characteristics can expand the recombination area of the machine, simplify the structure of the device, and reduce the cost because it can transport both electrons and holes. In order to enable effective energy transfer between the host and guest materials, the triplet energy level of the host material is usually higher than that of the guest material, so that the triplet excitons can be confined in the light-emitting layer to effectively recombine and emit light. Finally, materials with high thermal stability and amorphous stability are the key to the preparation of long-life, stable and efficient light-emitting devices.

Although many host materials with high triplet energy level, thermal stability and shape stability and their low-concentration doped high-efficiency phosphorescent devices have been reported, due to the inherent concentration quenching and triplet annihilation of phosphorescent materials, high-concentration doped Phosphorescent devices with excellent heterogeneous properties are rarely reported. Although the low-concentration doping mechanism can effectively suppress high-concentration aggregation quenching, its fabrication process is cumbersome and time-consuming. In addition, in the case of low concentration doping, the performance of the device is greatly affected by the concentration of the guest material, which increases the difficulty of device fabrication, reduces the yield of device products, and thus increases the production cost. Obviously, designing and synthesizing bipolar spirocyclic compounds with bulky steric hindrance as host materials is one of the effective methods to solve the above problems. In order to synthesize a host material with high thermal stability and shape stability to make the device emit light efficiently, the introduction of spiro aromatic hydrocarbons into the host material can not only control the intermolecular π-π interaction, but also make it have high thermal stability and shape. appearance stability, and because of its unique three-dimensional large-volume steric hindrance conjugated blocking structure, it has a high triplet energy level.

2,5-diphenyl-1,3,4--oxadiazole spiro aromatic hydrocarbon sterically hindered bipolar luminescent material has a large three-dimensional steric hindrance effect and stable The amorphous state and high thermal stability can effectively suppress the concentration quenching and triplet annihilation of the guest phosphorescent material in a high concentration state. In addition, fluorene has a higher triplet state energy level (2.95eV) and good hole transport properties, and the fluorenyl spiro ring with hole transport properties is modified to 2,5-diphenyl-1 with electron transport properties ,3,4--oxadiazole, which has both electron-transporting properties and hole-transporting properties, and can adjust its topology and triplet energy level by modifying different positions. As a result, this kind of material not only has good bipolar transport characteristics, but also has high triplet energy level, high thermal stability and stable amorphous state, which can expand the recombination area of the machine, simplify the device structure, and improve the quality of the product. rate and reduce costs. Based on this idea, the present invention prepares a series of 2,5- Diphenyl-1,3,4--oxadiazole spiro aromatic hydrocarbon sterically hindered bipolar luminescent material.

In a word, the present invention is based on a comprehensive understanding of current organic electroluminescent materials, tracking the frontier dynamics of organic electronic devices, and developing around the synthesis of organic electroluminescent materials and its related mechanism of action.

Contents of the invention

Technical problem: The purpose of this invention is to provide a 2,5-diphenyl-1,3,4-oxadiazole spiro aromatic hydrocarbon sterically hindered bipolar luminescent material and its preparation method, and design and synthesize 2,5- Diphenyl-1,3,4--oxadiazole spiro aromatic hydrocarbon sterically hindered bipolar luminescent material is used to prepare stable and effective sterically hindered bipolar host materials, which are widely used in electroluminescence and storage devices application.

Technical solution: The present invention specifically relates to a preparation method based on the functionalization of 2,5-diphenyl-1,3,4-oxadiazole with a spiro aromatic hydrocarbon, and involves the steps used in the preparation process of these materials As well as the raw material, the material is functionalized by replacing the hydrogen atoms at different positions on the benzene ring in 2,5-diphenyl-1,3,4--oxadiazole with different spiro aromatic hydrocarbon functional groups, which have the following structure:

In the general formula I, X is an oxygen atom, a sulfur atom or sulfur dioxide, R and R' are the same or different spiro aromatic hydrocarbon functional groups, and * represents the linking position, which is specifically as the following structure:

in,

The compounds represented by general formula I all contain 2,5-diphenyl-1,3,4--oxadiazole and spiro arene, and all introduced spiro arene R, R' are connected at 2,5-di On the benzene ring in phenyl-1,3,4--oxadiazole.

The preparation method of 2,5-diphenyl-1,3,4-oxadiazole spiro aromatic hydrocarbon sterically hindered bipolar luminescent material of the present invention is:

a. Dissolve bromophenylacetyl chloride in tetrahydrofuran, through a constant-pressure low-liquid funnel, slowly add it dropwise to the tetrahydrofuran hydrazine hydrate solution at -20-20°C to react, then react at room temperature, saturated sodium bicarbonate solution Wash until alkaline, filter with suction to obtain a white solid, wash with water, and dry to obtain the dibromo-diphenyl-1,3,4--oxadiazole product;

b. Add brominated spiro aromatic hydrocarbon and tetrahydrofuran into the reactor, stir under the protection of dry ice acetone and nitrogen, slowly add n-butyllithium into the reactor, react at low temperature, take isopropanol pinacol borate ester Add dropwise into the reactor to continue the reaction, and then react at room temperature; quench with water, extract with dichloromethane, combine the organic phases and dry with anhydrous magnesium sulfate, concentrate, and column chromatography to obtain the spiroaromatic borate ester product;

c. the dibromo-2,5-diphenyl-1,3,4--oxadiazole obtained in step a, the spiro aromatic hydrocarbon borate ester obtained in step b, tetrakistriphenylphosphopalladium, potassium carbonate solution and Add toluene into another reactor, heat and stir the reaction under nitrogen protection and light-shielding conditions, then wait for the reaction to cool to room temperature, evaporate and concentrate through a rotary evaporator, wash with water, and extract with dichloromethane for several times, combine the organic phases with free dried over magnesium sulphate;

d. After drying, filter under reduced pressure and wash the desiccant with dichloromethane, and concentrate the resulting filtrate with a rotary evaporator to remove most of the solvent to obtain a concentrated crude product; then column chromatography, with ethyl acetate and petroleum ether It is a detergent, and after purification, a white solid product is obtained, that is, the 2,5-diphenyl-1,3,4-oxadiazole spiro aromatic hydrocarbon sterically hindered bipolar luminescent material.

in,

Slowly add bromophenylacetyl chloride dropwise to the tetrahydrofuran hydrazine hydrate solution at -20-20°C, react for 0.5-10 hours, and then react at room temperature.

Stir under the protection of dry ice acetone and nitrogen, slowly add n-butyllithium into the reactor, react at low temperature for 0.5-8 hours, take isopropanol pinacol borate ester dropwise into the reactor, and react at low temperature for 1 -6 hours, then react at room temperature for 5-72 hours.

In the step c, the heating and stirring reaction time is 5-72 hours.

The time for the reaction at room temperature is 0.5-10 hours.

Beneficial effects: the complex 2,5-diphenyl-1,3,4--oxadiazole spirocycle is characterized by infrared spectroscopy (FTIR), elemental analysis, nuclear magnetic resonance (NMR), and chromatography-mass on-line (LC-MS) The structure of aromatic hydrocarbon sterically hindered bipolar luminescent materials was tested by thermogravimetric analysis and differential thermal analysis, and their optical and electrochemical properties were characterized by ultraviolet fluorescence spectroscopy and cyclic voltammetry. Such materials show good thermal stability in thermogravimetric analysis and differential thermal analysis, and UV, fluorescence and electrochemical analysis show that they have good photoelectric properties. Therefore, such materials can be widely used in organic light-emitting diodes, organic lasers, organic electrical storage devices, organic field effect transistors, etc.

The main advantages of the present invention are:

1. The synthesis steps are simple and the conditions are mild;

2. With bipolar transmission characteristics;

3. Maintain high thermal stability and glass transition temperature;

4. Has an appropriate triplet energy level;

5. Have suitable HOMO and LUMO energy levels;

6. Has a large steric hindrance effect.

Description of drawings

Figure 1. The mass spectrum of 2,5-bis(2-bromophenyl)-1,3,4--oxadiazole;

Figure 2. The mass spectrum of 2,5-bis(2-(spiro-9,9′-xanthene fluorene)phenyl)-1,3,4--oxadiazole; where 833.2962 is the M+1 ion peak of the molecule ;

Figure 3. The hydrogen spectrum of 2,5-bis(2-(spiro-9,9'-xanthene fluorene)phenyl)-1,3,4--oxadiazole;

Figure 4. The carbon spectrum of 2,5-bis(2-(spiro-9,9'-xanthenefluorene)phenyl)-1,3,4-oxadiazole.

detailed description

The technical scheme of the present invention is further described below in conjunction with the examples, but these examples do not limit the implementation manner of the present invention. The present invention has many different embodiments, and is not limited to the content described in this specification. Under the situation that those skilled in the art do not deviate from the spirit of the invention of the present application, the solutions completed should be within the scope of the present invention.

Example 1: Synthesis of 2,5-bis(2-(spiro-9,9'-oxanthrene fluorene)phenyl)-1,3,4--oxadiazole

The first step: 2,5-bis(2-bromophenyl)-1,3,4--oxadiazole

Dissolve 5.0 mL of 2-bromophenylacetyl chloride in 40 mL of tetrahydrofuran, and slowly add it dropwise to 0.85 mL of 80% hydrazine hydrate solution in 0.85 mL of tetrahydrofuran (20 mL) through a constant-pressure low-liquid funnel at 0°C, and react for 1 hour. Then react at room temperature for 2 hours, wash with saturated sodium bicarbonate solution until alkaline, filter with suction to obtain a white solid, wash with water, and dry to obtain 2,5-bis(2-bromophenyl)-1,3,4-oxo Oxadiazole product, (Yield: 91%), LC-MS (EI) m/z 380.9127 [M ⁺ ].

The second step: Synthesis of 2-spiro-9,9′-xanthene fluorenyl-4,4,5,5-tetramethyl-1,3,2-dioxaborane

Add 2-bromo-spiro-9,9′-xanthene fluorene (0.4110g, 1.0mmol) and 50mL tetrahydrofuran into a single-necked round bottom flask, stir at low temperature under the protection of dry ice, acetone and nitrogen, and take n-butyllithium Slowly add to the reactor, react at low temperature for 0.5-8 hours, take isopropanol pinacol borate ester (1.0mL, 5.0mmol) dropwise into the reactor, react at low temperature for 1-6 hours, and then react at room temperature for 5- 72 hours; Quenched with water, extracted with dichloromethane, combined the organic phases and dried with anhydrous magnesium sulfate, concentrated, and column chromatography to obtain the product 2-spiro-9,9'-xanthene fluorenyl-4,4,5, 5-Tetramethyl-1,3,2-dioxaborane, (Yield: 51%).

Step 3: Synthesis of 2,5-bis(2-(spiro-9,9′-oxanthrene)phenyl)-1,3,4--oxadiazole

2,5-bis(2-bromophenyl)-1,3,4-oxadiazole (0.3800g, 1.0mmol), 2-spiro-9,9′-oxanthene fluorenyl-4,4 , 5,5-tetramethyl-1,3,2-dioxaborane (0.9160g, 2.0mmol), tetrakistriphenylphosphopalladium (0.2311g, 0.2mmol), potassium carbonate solution (10.0mL, 2.0mol /L) and toluene were added to a three-necked round bottom flask, heated and stirred for 5-72 hours under nitrogen protection and light-proof conditions, and then the reaction was cooled to room temperature, evaporated and concentrated by a rotary evaporator, washed with water, and extracted with dichloromethane Multiple times, the organic phases were combined and dried with anhydrous magnesium sulfate; after drying, the desiccant was filtered under reduced pressure and washed with dichloromethane, and the obtained filtrate was concentrated under reduced pressure with a rotary evaporator to remove most of the solvent to obtain a concentrated crude product; then Column chromatography, using ethyl acetate and petroleum ether as detergents, after purification, the white solid product 2,5-bis(2-(spiro-9,9'-oxanthene fluorene)phenyl)-1,3, 4--Oxadiazole. (Yield: 53%, LC-MS (EI) m/z 833.2962 [M ⁺ ]).

Example 2: Synthesis of 2,5-bis(2-(spiro-9,9'-thiaxanthene fluorene)phenyl)-1,3,4--oxadiazole

The first and second steps are the same as the first and second steps of Example 1,

The third step: 2,5-bis(2-bromophenyl)-1,3,4-oxadiazole (0.3800g, 1.0mmol), 2-spiro-9,9′-thioxanthene fluorenyl -4,4,5,5-tetramethyl-1,3,2-dioxaborane (0.9480g, 2.0mmol), tetrakistriphenylphosphopalladium (0.2311g, 0.2mmol), potassium carbonate solution (10.0 mL, 2.0mol/L) and toluene into a three-necked round-bottomed flask, heated and stirred for 5-72 hours under nitrogen protection and light-proof conditions, and then cooled to room temperature after the reaction was evaporated and concentrated by a rotary evaporator, washed with water, Dichloromethane was extracted several times, and the organic phase was combined and dried with anhydrous magnesium sulfate; Crude product; then column chromatography, using ethyl acetate and petroleum ether as detergents, after purification, white solid product 2,5-bis(2-(spiro-9,9'-thioxanthene fluorene)phenyl)- 1,3,4--Oxadiazole (Yield: 57%).

Example 3: Synthesis of 2,5-bis(2-(spiro-9,9'-dioxathioxanthene fluorene)phenyl)-1,3,4--oxadiazole

The first and second steps are the same as the first and second steps of Example 1,

The third step: 2,5-bis(2-bromophenyl)-1,3,4-oxadiazole (0.3800g, 1.0mmol), 2-spiro-9,9′-dioxathioxanthene Fluorenyl-4,4,5,5-tetramethyl-1,3,2-dioxaborane (1.0120g, 2.0mmol), tetrakistriphenylphosphopalladium (0.2311g, 0.2mmol), potassium carbonate solution (10.0mL, 2.0mol/L) and toluene were added to a three-necked round-bottomed flask, under nitrogen protection and light-shielding conditions, heated and stirred for 5-72 hours, and then the reaction was cooled to room temperature, evaporated and concentrated by a rotary evaporator, Washing with water and extracting with dichloromethane several times, combining the organic phases and drying with anhydrous magnesium sulfate; after drying, suction filtration under reduced pressure and washing the desiccant with dichloromethane, and concentrating the obtained filtrate with a rotary evaporator to remove most of the solvent to obtain Concentrated crude product; then column chromatography, using ethyl acetate and petroleum ether as detergents, after purification, white solid product 2,5-bis(2-(spiro-9,9'-dioxathioxanthene fluorene) Phenyl)-1,3,4-oxadiazole (Yield: 63%).

Claims (7)

1. A 2,5-diphenyl-1,3,4--oxadiazole spiro aromatic hydrocarbon sterically hindered bipolar luminescent material, characterized in that the material is 2,5-diphenyl-1 ,3,4--The hydrogen atoms at different positions on the benzene ring in oxadiazole are substituted with different spiro aromatic hydrocarbon functional groups to make it functional, which has the following structure: In the general formula I, X is an oxygen atom, a sulfur atom or sulfur dioxide, R and R' are the same or different spiro aromatic hydrocarbon functional groups, and * represents the linking position, which is specifically as follows: 2. 2,5-diphenyl-1 according to claim 1,3,4--oxadiazole spiro aromatic hydrocarbon steric hindrance type bipolar luminescent material, it is characterized in that the compound represented by general formula I is Containing 2,5-diphenyl-1,3,4--oxadiazole and spiro arene, all introduced spiro arene R, R' are connected in 2,5-diphenyl-1,3,4 -- On the benzene ring in oxadiazole. 3. A preparation method of 2,5-diphenyl-1,3,4--oxadiazole spiro aromatic hydrocarbon sterically hindered bipolar luminescent material as claimed in claim 1, characterized in that the preparation method for: a. Dissolve bromophenylacetyl chloride in tetrahydrofuran, through a constant-pressure low-liquid funnel, slowly add it dropwise to the tetrahydrofuran hydrazine hydrate solution at -20-20°C to react, then react at room temperature, saturated sodium bicarbonate solution Wash until alkaline, filter with suction to obtain a white solid, wash with water, and dry to obtain the dibromo-diphenyl-1,3,4--oxadiazole product; b. Add brominated spiro aromatic hydrocarbon and tetrahydrofuran into the reactor, stir under the protection of dry ice acetone and nitrogen, slowly add n-butyllithium into the reactor, react at low temperature, take isopropanol pinacol borate ester Add dropwise into the reactor to continue the reaction, and then react at room temperature; quench with water, extract with dichloromethane, combine the organic phases and dry with anhydrous magnesium sulfate, concentrate, and column chromatography to obtain the spiro aromatic borate ester product; c. the dibromo-2,5-diphenyl-1,3,4--oxadiazole obtained in step a, the spiro aromatic hydrocarbon borate ester obtained in step b, tetrakistriphenylphosphopalladium, potassium carbonate solution and Add toluene into another reactor, heat and stir the reaction under nitrogen protection and light-shielding conditions, then wait for the reaction to cool to room temperature, evaporate and concentrate through a rotary evaporator, wash with water, extract with dichloromethane several times, combine the organic phases with dried over magnesium sulphate; d. After drying, filter under reduced pressure and wash the desiccant with dichloromethane, and concentrate the resulting filtrate with a rotary evaporator to remove most of the solvent to obtain a concentrated crude product; then column chromatography, with ethyl acetate and petroleum ether It is a detergent, and after purification, a white solid product is obtained, that is, the 2,5-diphenyl-1,3,4-oxadiazole spiro aromatic hydrocarbon sterically hindered bipolar luminescent material. 4. The preparation method of 2,5-diphenyl-1,3,4--oxadiazole spiro aromatic hydrocarbon sterically hindered type bipolar luminescent material according to claim 3, characterized in that -20 Slowly add bromophenylacetyl chloride dropwise to the tetrahydrofuran hydrazine hydrate solution at -20°C, react for 0.5-10 hours, and then react at room temperature. 5. 2,5-diphenyl-1 according to claim 3, 3,4--the preparation method of oxadiazole spiro aromatic hydrocarbon steric hindrance type bipolar luminescent material, is characterized in that described in dry ice acetone Stir under the protection of nitrogen, slowly add n-butyllithium into the reactor, react at low temperature for 0.5-8 hours, take isopropanol pinacol borate ester dropwise into the reactor, react at low temperature for 1-6 hours, and then React at room temperature for 5-72 hours. 6. The preparation method of 2,5-diphenyl-1,3,4-oxadiazole spiro aromatic hydrocarbon sterically hindered bipolar luminescent material according to claim 3, characterized in that in the step c , The heating and stirring reaction time is 5-72 hours. 7. the preparation method of 2,5-diphenyl-1,3,4--oxadiazole spiro aromatic hydrocarbon sterically hindered type bipolar luminescent material according to claim 4, it is characterized in that described at room temperature Reaction under the condition, its time is 0.5-10 hour.