CN106749094A - 42 (2` hydroxy phenyls) benzoxazole compounds and its preparation method and purposes containing substituted base - Google Patents

Abstract

The invention belongs to the field of organic semiconductor optoelectronic technology, and provides a 2-(2'-hydroxyphenyl) benzoxazole compound containing a substituent at the 4-position and its preparation and application. The general formula of the 2-(2'-hydroxyphenyl) benzoxazole compound containing a substituent in the 4 position is: Wherein X is S, O or NH, and Ar is a conjugated structural unit containing aromatic hydrocarbons. The compound is prepared by Suzuki reaction between 2-(2'-4-bromophenol) benzoxazole and polycyclic aromatic hydrocarbon compound with bromine. The compound disclosed herein has the four-level transition fluorescent property of the excited-state intramolecular proton transfer compound, and can be used as a light-emitting material in organic white light diode devices. The compound of the invention has the advantages of large Stokes shift, good luminescence quantum efficiency, simple preparation, high synthesis yield and the like.

Description

2-(2'-hydroxyphenyl) benzoxazole compound containing substituent at 4-position and its preparation method and use

technical field

The invention belongs to the technical field of organic semiconductor optoelectronics, and in particular relates to a 2-(2'-hydroxyphenyl) benzoxazole compound containing a substituent at the 4-position and its preparation and application.

Background technique

In 1987, C.W.Tang and others in the United States invented a multi-layered organic light-emitting diode (OLED) by vacuum evaporation, which made the research on organic electroluminescent devices highly valued by scientists from all over the world. The development of OLED technology has produced earth-shaking changes in the field of optoelectronic display. Nowadays, the development of material science and the maturity of theory and technology play a vital role in the development of new OLEDs, making researchers in the field of materials have great interest in the exploration of luminescent materials. White organic light-emitting diodes (WOLEDs) have excellent properties such as high efficiency, high brightness, low power consumption, wide viewing angle, fast response speed, active light emission, ultra-thin, ultra-light, and flexibility, and have wide applications in the fields of display and lighting. The prospect has been widely valued by scholars and the industry and has become a research hotspot.

In 1994, Professor Kido of Yamagata University in Japan first prepared the world's first WOLED device. Although the maximum power efficiency of the device was only 0.83lm/W and the maximum brightness was only 3400cd/M ² at that time, it was still in the organic electroluminescent device. A breakthrough has been achieved in the field.

In 2003, WOLED device efficiency reached 15lm/W and surpassed incandescent lamps for the first time. In 2006, the Nobuhiro Ide research group of the University of San Diego used all-phosphorescent materials to prepare a color-tunable stacked multi-layer WOLED with a device efficiency of 62.8lm/W. In 2008, the James Esler research group of the University of San Diego in the United States prepared a WOLED with a maximum power efficiency of 100 lm/W and a multi-emitting layer structure. Its operating voltage was 3.6V and the external quantum efficiency reached 20%.

The efficiency of multi-emitting layer WOLED is usually high, but the structure and process conditions are relatively complex, the voltage is high, resulting in relatively high cost, there are heterojunctions between each emitting layer, and the stability of color coordinates is generally poor. How to reasonably control the exciton generation area, exciton recombination area, energy transfer and exciton diffusion between the light-emitting layers is the guarantee of high performance.

At present, in the field of WOLEDs, the development of a single-layer white light device with high device efficiency, simple process, low cost and good stability is the key to realize the commercialization of white light organic light emitting diodes.

Contents of the invention

Aiming at the technical problems such as complex device preparation process, high production cost and poor repeatability in current white light organic light-emitting diodes, the present invention provides a new organic fluorescent material, that is, 2-(2 '-Hydroxyphenyl) benzoxazole compound, its preparation method and application. The organic fluorescent material is a series of 2-(2'-hydroxyphenyl) benzoxazoles with the four-level transition property of the excited-state intramolecular proton transfer compound, and is connected with a variety of new aromatic hydrocarbon conjugated structural units. Material. This type of material has the advantages of high fluorescence quantum yield, large Stokes shift, simple synthesis, and high yield. By mixing commercially available blue light materials to form binary complementary colors, a single-layer white light device with simple process can be fabricated. The technical scheme adopted in the present invention is as follows.

The invention provides a 2-(2'-hydroxyphenyl) benzoxazole compound containing a substituent at the 4-position.

The 2-(2'-hydroxyphenyl) benzoxazole compound containing a substituent at the 4-position of the present invention has a general structural formula:

In the formula: X is S, O or NH, and Ar is a conjugated structural unit containing aromatic hydrocarbons.

The arene-containing conjugated structural unit is selected from one of the following substituent structures:

The present invention also provides a preparation method of the above-mentioned 2-(2'-hydroxyphenyl)benzoxazole compound containing a substituent at the 4-position.

The preparation method of the 2-(2'-hydroxyphenyl) benzoxazole compound containing a substituent in the 4 position of the present invention comprises the following steps:

(1) Borylation of aromatic compounds with conjugated structures: under the protection of nitrogen, bromoarenes are dissolved in dry organic solvents, and n-butyllithium is added at a temperature lower than -40°C. After stirring for 2 to 4 hours, add The boric acid compound is borated and reacted for 15-20 hours after the temperature is raised to normal temperature. After the reaction, extract the organic phase, combine and dry the organic phase to obtain the product.

(2) Dissolve the product of step (1) and 2-(2'-4-bromophenol) benzoxazole and palladium catalyst in an organic solvent, then add a strong alkali aqueous solution, and react under nitrogen protection. After the reaction, the organic phase is extracted, combined and concentrated, and after separation and purification, the final product is obtained, which is the product of the present invention.

In the above step (1), the low temperature reaction can be cooled with a dry ice acetone bath; the boric acid compound is n-tributyl borate; the organic phase is extracted with water and dichloromethane; the organic solvent is tetrahydrofuran.

In the above step (2), the palladium catalyst is tetrakis(triphenylphosphine)palladium, bis(dibenzylideneacetone)palladium, 1,1-bis(diphenylphosphino)ferrocene dichloride, strong base It is one or more of potassium carbonate, potassium chloride, and potassium fluoride, and the organic solvent is a mixed solvent with a volume ratio of tetrahydrofuran and toluene of 1:1. The reaction temperature is 80-120° C., and the reaction time is 24-60 hours. The general formula of the described 2-(2'-4-bromophenol) benzoxazole compound is:

Wherein, X is S, O or NH.

In the above preparation method, in terms of molar ratio, in step (1), the ratio of brominated aromatic hydrocarbon to n-butyllithium is 1:0.9～1.5, preferably 1:1.2; in step (2), the borated aromatic brominated hydrocarbon The ratio to 2-(2'-4-bromophenol)benzoxazole is 1:0.5~1.5, preferably 1:1

The addition ratio of the brominated aromatic hydrocarbon and the organic solvent is 1 mole: 2-8 liters. The preferred ratio is 1 mole: 4-6 liters.

Another object of the present invention is to provide a use of 2-(2'-hydroxyphenyl)benzoxazole compounds containing substituents at the 4-position for preparing white-light organic light-emitting diodes.

The 2-(2'-hydroxyphenyl) benzoxazole compound containing a substituent at the 4-position of the present invention can be used as a light emitting material in an organic white light diode device. By mixing commercially available blue light materials to form binary complementary colors, a single-layer white light device with simple process can be fabricated.

The present invention has the following beneficial effects: 1. The 2-(2'-hydroxyphenyl) benzoxazole compound containing a substituent at the 4-position of the present invention has a high fluorescence quantum yield and a large Stokes shift; 2. The preparation method has the advantages of simple synthesis and high yield, which is beneficial to expand the production scale; 3. The above-mentioned compound can be used as a light-emitting material in an organic white light diode device.

Description of drawings

The carbon spectrogram of Fig. 1 embodiment 2 compound of the present invention;

The carbon spectrogram of Fig. 2 embodiment 3 compounds of the present invention;

Fig. 3 is the fluorescence absorption-emission diagram of the compound of Example 2 of the present invention;

The fluorescence absorption-emission figure of the compound of Fig. 4 embodiment 3 of the present invention;

Fig. 5 is the oxidation-reduction curve of the compound of Example 2 of the present invention.

detailed description

In order to better understand the content of the patent of the present invention, the technical solution of the present invention will be further described through specific examples below. However, these implementation examples do not limit the present invention.

The material 2-(2'-4-bromophenol) benzoxazole connects the electron-donating groups of various aromatic hydrocarbon conjugated structural units through the Suzuki reaction, and the material has the following general formula:

In the formula: X is S, O or NH.

Embodiment 1,

First, the preparation of 2-(2'-4-bromophenol)benzothiazole:

Get diaminophenol (4.4g, 20mmol, 1equiv) and p-aminobenzoic acid (2.5g, 20mmol, 1equiv) and add in 130ml polyphosphoric acid, heat to 168 ℃ in N ₂ environment, and reflux for 6 hours. After the reaction was complete, the product was dissolved in 100 ml of ice-water mixture after cooling, and saturated NaOH aqueous solution was added thereto for neutralization. When the pH value is adjusted to about 6, add NaHCO ₃ and stir while adding until no CO ₂ bubbles are produced. The neutralized solution was left to stand until the solution was clarified and then suction filtered. The filtered solid was added to saturated NaHCO ₃ aqueous solution and extracted three times with ethyl acetate, the organic layers were combined, dried with anhydrous Na ₂ SO ₄ and rotary evaporated to obtain 5 g of green product with a yield of 83%. (In the following examples, the preparation method of 2-(2'-4-bromophenol)benzothiazole is the same as this, and will not be repeated here).

Secondly, the preparation of 2-(2'-benzothiazole)-4-(9'-phenanthrene)phenol

(1) Borylation of compounds containing aromatic hydrocarbon conjugated structures: under the protection of nitrogen, 9-bromophenanthrene was dissolved in dry tetrahydrofuran, cooled in a dry ice acetone bath (-78°C), and n-butyllithium was added at low temperature, The addition ratio of 9-bromophenanthrene and n-butyllithium is 1:0.9. After stirring for 2 hours, add n-butyl borate, borate, continue the reaction for 0.5 hours, remove the dry ice acetone bath, heat up to room temperature and react for 15 hours. After the reaction was completed, the reaction was quenched in an ice-water bath, and then the organic phase was extracted with water and dichloromethane, and the organic phases were combined, dried and spin-dried to obtain the product.

(2) Take 9-phenanthrene borate (0.18g, 0.75mmol, 1 equivalent) and 2-(2'-4-bromophenol) benzothiazole (0.12g, 0.38mmol, 0.5 equivalent) and dissolve in 20ml tetrahydrofuran and toluene in a mixed solution with a volume ratio of 1:1. Catalyst Pd(pph ₃ ) ₄ was added. Protect from light and ventilate with nitrogen, and then add 10 ml of an aqueous solution of potassium carbonate and potassium fluoride with a concentration of 2 mol/L. The reaction was carried out at 80° C. for 24 hours. After the reaction, the organic phase was extracted, combined and concentrated, and separated and purified by a chromatographic column to obtain a yellow powdery final product.

Embodiment 2,

Preparation of 2-(2'-benzothiazole)-4-(9'-phenanthrene)phenol

(1) Borylation of compounds containing aromatic hydrocarbon conjugated structures: under the protection of nitrogen, 9-bromophenanthrene was dissolved in dry tetrahydrofuran, placed in a dry ice acetone bath and cooled to -78°C, and n-butyllithium was added at low temperature, 9 -The addition ratio of phenanthrene bromide and n-butyllithium is 1:1.2. After stirring for 3 hours, add n-butyl borate, borate, continue the reaction for 0.5 hours, remove the dry ice acetone bath, heat up to room temperature and react for 18 hours. After the reaction was completed, the reaction was quenched in an ice-water bath, and then the organic phase was extracted with water and dichloromethane, and the organic phases were combined, dried and spin-dried to obtain the product.

(2) Take 9-phenanthrene borate (0.18g, 0.75mmol, 1 equivalent) and 2-(2'-4-bromophenol) benzothiazole (0.24g, 0.75mmol, 1 equivalent) and dissolve in 20ml tetrahydrofuran and toluene in a mixed solution with a volume ratio of 1:1. Catalyst Pd(pph ₃ ) ₄ was added. Protect from light and ventilate with nitrogen, and then add 10 ml of an aqueous solution of potassium carbonate and potassium fluoride with a concentration of 2 mol/L. The reaction was carried out at 90° C. for 48 hours. After the reaction, the organic phase was extracted, combined and concentrated, and separated and purified by a chromatographic column to obtain 0.31 g of a yellow powdery final product with a yield of 82%.

The final product was detected by NMR and redox curve, as shown in Figure 1 and Figure 5 respectively

Embodiment 3,

Preparation of 2-(2'-benzothiazole)-4-(1'-pyrene)phenol

9-phenanthrene borate in embodiment 2 is changed into 1-pyrene borate, and concrete steps are:

(1) Borylation of compounds containing aromatic hydrocarbon conjugated structures: under the protection of nitrogen, 1-bromopyrene was dissolved in dry tetrahydrofuran, placed in a dry ice acetone bath and cooled to -78 ° C, and n-butyllithium was added at low temperature, 1 - The addition ratio of bromopyrene and n-butyllithium is 1:1.2. After stirring for 3 hours, add n-butyl borate, borate, continue the reaction for 0.5 hours, remove the dry ice acetone bath, heat up to room temperature and react for 18 hours. After the reaction was completed, the reaction was quenched in an ice-water bath, and then the organic phase was extracted with water and dichloromethane, and the organic phases were combined, dried and spin-dried to obtain the product.

(2) Take 9-pyrene borate (0.6g, 2.2mol, 1 equivalent) and 2-(2'-4-bromophenol) benzothiazole (0.7g, 2.2mmol, 1 equivalent) and dissolve in 30ml tetrahydrofuran and toluene in a mixed solution with a volume ratio of 1:1. Catalyst Pd(pph ₃ ) ₄ was added. Protect from light and ventilate with nitrogen, and then add 10 ml of an aqueous solution of potassium carbonate and potassium fluoride with a concentration of 2 mol/L. The reaction was carried out at 90° C. for 48 hours. After the reaction, the organic phase was extracted, combined and concentrated, and separated and purified by a chromatographic column to obtain 0.86 g of a yellow powdery final product with a yield of 73%.

The final product was detected by nuclear magnetic resonance, as shown in Figure 2.

Embodiment 4,

Preparation of 2-(2'-benzothiazole)-4-(1'-pyrene)phenol

(1) Borylation of compounds containing aromatic hydrocarbon conjugated structures: under the protection of nitrogen, 1-bromopyrene was dissolved in dry tetrahydrofuran, placed in a dry ice acetone bath and cooled to -78 ° C, and n-butyllithium was added at low temperature, 1 -The addition ratio of bromopyrene and n-butyllithium is 1:1.5. After stirring for 4 hours, add n-butyl borate, borate, continue the reaction for 0.5 hours, remove the dry ice acetone bath, heat up to room temperature and react for 20 hours. After the reaction was completed, the reaction was quenched in an ice-water bath, and then the organic phase was extracted with water and dichloromethane, and the organic phases were combined, dried and spin-dried to obtain the product.

(2) Take 9-pyrene borate (0.6g, 2.2mol, 1 equivalent) and 2-(2'-4-bromophenol) benzothiazole (0.36g, 3.3mmol, 1.5 equivalent) and dissolve in 30ml tetrahydrofuran and toluene in a mixed solution with a volume ratio of 1:1. Catalyst Pd(pph ₃ ) ₄ was added. Protect from light and ventilate with nitrogen, and then add 10 ml of an aqueous solution of potassium carbonate and potassium fluoride with a concentration of 2 mol/L. The reaction was carried out at 120° C. for 60 hours. After the reaction, the organic phase was extracted, combined and concentrated, and separated and purified by a chromatographic column to obtain a yellow powdery final product.

Embodiment 5,

Preparation of 3-(2'-benzothiazole)-4'-(1,2,2-triphenylethylene)-4'-[1,1'-biphenyl]

(1) Borylation of compounds containing aromatic hydrocarbon conjugated structures: under the protection of nitrogen, bromotetraphenylethylene was dissolved in dry tetrahydrofuran, placed in a dry ice acetone bath and cooled to -78°C, and n-butyl lithium and bromine were added at low temperature The addition ratio of tetraphenylethylene and n-butyllithium is 1:1.2. After stirring for 3 hours, add n-butyl borate, borate, continue the reaction for 0.5 hours, remove the dry ice acetone bath, heat up to room temperature and react for 18 hours. After the reaction was completed, the reaction was quenched in an ice-water bath, and then the organic phase was extracted with water and dichloromethane, and the organic phases were combined, dried and spin-dried to obtain the product.

(2) Take tetraphenylethylene borate (0.5g, 1.9mol, 1 equivalent) and 2-(2'-4-bromophenol) benzothiazole (0.65g, 1.9mmol, 1 equivalent) and dissolve in 40ml THF and toluene in a mixed solution with a volume ratio of 1:1. Catalyst Pd(pph ₃ ) ₄ was added. Protect from light and ventilate with nitrogen, and then add 10 ml of an aqueous solution of potassium carbonate and potassium fluoride with a concentration of 2 mol/L. The reaction was carried out at 90° C. for 48 hours. After the reaction, the organic phase was extracted, combined and concentrated, and separated and purified by a chromatographic column to obtain a light yellow powdery final product.

Embodiment 6,

This example is the determination of the spectra of the compounds prepared in Example 2 and Example 3.

The compounds of Example 2 and Example 3 were formulated into a standard 1 μM tetrahydrofuran solution. The absorption and emission spectra were measured by Shimadzu-3150 UV-Vis spectrometer and RF-520XPC fluorescence spectrometer. Photoluminescence spectra were measured at the absorbance maximum of the UV absorbance. As shown in Figure 3 and Figure 4, it can be seen from the figures that the overlapping ranges of absorption and fluorescence of the two compounds are small or even non-existent, indicating that the two materials have the advantage of large Stokes shifts.

Embodiment 6,

This example is an electrochemical measurement of the compounds prepared in Example 2 and Example 3.

The electrochemical cyclic voltammetry (CV) experiment was completed on an Eco Chemie BVAUTOLABpotentiostat voltammetry analyzer, using a three-electrode system, including a platinum carbon electrode, Ag/Ag ⁺ as a reference electrode, and a platinum wire as a counter electrode. Dichloromethane was used as a solvent in the oxidation process, tetrahydrofuran was used as a solvent in the reduction process, tetrabutylammonium hexafluorophosphine (Bu ₄ N ⁺ PF ₆ ^- ) was used as a supporting electrolyte, and the concentration was 0.1M. All electrochemical experiments were carried out in a nitrogen atmosphere at room temperature, and the voltage scanning speed was 0.1V/S. Using ferrocene (FOC) as a benchmark, the HOMO and LUMO energy levels of the material can be calculated by measuring the onset voltages of the oxidation and reduction processes.

From the electrochemical test results in Figure 5, it can be seen that the position of the redox peak of the material, and then through the formula:

HOMO＝-[E _OX –E _Fe/Fe+ +4.8]

LUMO＝-[E _RE –E _Fe/Fe+ +4.8]

It can be calculated that the HOMO and LUMO energy levels of the material in Example 2 are -5.44eV and -3.40eV, respectively. The HOMO and LUMO energy levels of the material of Example 3 are -5.26eV and -3.44eV, respectively.

Claims (10)

1. a kind of 4 2- (2'- hydroxy phenyls) benzoxazole compounds containing substituted base, it is characterised in that the compound formula For：

In formula：X is S, O or NH, and Ar is the unit of conjugated structure containing aromatic hydrocarbons, and the unit of conjugated structure containing aromatic hydrocarbons is selected from following substitution One kind in based structures：

2. a kind of 4 as claimed in claim 1 containing substituted base 2- (2'- hydroxy phenyls) benzoxazole compound preparation side Method, it is characterised in that the preparation method is concretely comprised the following steps：

(1) preparation of the unit of conjugated structure containing aromatic hydrocarbons：Under nitrogen protection, aryl bromide is dissolved in dry organic solvent, temperature Degree adds n-BuLi under the conditions of being less than -40 DEG C, after stirring 2 to 4 hours, boration, and continuation reaction 15 is arrived after being warming up to normal temperature 20 hours.After reaction terminates, organic phase is extracted, organic phase is merged into drying is spin-dried for, and obtains product；

(2) by product and 2- (2'-4- bromophenols) benzothiazole of step (1), palladium catalyst is dissolved in organic solvent, is subsequently adding one Quantitative strong alkali aqueous solution, the lower reaction of nitrogen protection, after reaction terminates, extracts organic phase, merges organic phase and concentrates, and separation is carried After pure, end-product is obtained.

3. preparation method according to claim 2, it is characterised in that：According to the molar ratio, in step (1), aryl bromide and The ratio of n-BuLi is 1：0.9~1.5；In step (2), polycyclic aromatic hydrocarbon and 2- (2'-4- bromophenols) benzo of the bromo The ratio of azoles is 1：0.5~1.5.

4. preparation method according to claim 3, it is characterised in that：According to the molar ratio, in step (1), aryl bromide and The ratio of n-BuLi is 1：1.2；In step (2), the ratio of the aryl bromide and 2- (2'-4- bromophenols) benzothiazole is 1： 1。

5. the preparation method according to claim 2,3 or 4, it is characterised in that：Described 2- (2'-4- bromophenols) benzothiazole The formula of compound is：

Wherein X is S, O or NH.

6. preparation method according to claim 2, it is characterised in that：Reaction dissolvent in step (1) is tetrahydrofuran；Step Suddenly the reaction dissolvent in (2) is that the volume ratio of tetrahydrofuran and toluene is 1:1 mixed solvent.

7. preparation method according to claim 2, it is characterised in that：The adding proportion of the aryl bromide and organic solvent It is 1 mole：2~8 liters.

8. preparation method according to claim 7, it is characterised in that：The adding proportion of the aryl bromide and organic solvent It is 1 mole：4~6 liters.

9. a kind of purposes of the arene compounds of 2- according to claim 1 (2'- hydroxy phenyls) benzothiazole, its feature It is：Described compound can be used in white light organic diode device.

10. purposes according to claim 9, it is characterized in that：Described compound mixing blue light material composition binary is complementary Color, can be with the single layer white light device of preparation process is simple.