1. An organic electroluminescent compound of the formula La or Lb, having the formula:

wherein R1, R2, R3 are selected from C6-C30 aryl, 3-30 membered aromatic heterocyclic group;

x1, X2, X3, X4 and X5 are selected from C or N, up to three N being present simultaneously.

2. The organic electroluminescent compound according to claim 1, wherein Lb further comprises ring G, which is a substituted or unsubstituted 6-18 membered aromatic heterocyclic group having the following formula:

3. an organic electroluminescent compound according to claim 2, wherein when X1 ═ X3 ═ X5 ═ N, R1 is selected from one of phenyl and biphenyl;

when the X1 ═ X2 ═ N, the R1 is selected from one of phenyl and biphenyl;

when the X1 ═ X5 ═ N, the R1 is selected from one of phenyl, biphenyl, or 6-to 18-membered aryl;

when the X1 is equal to N, the G ring is a pyridine ring, and the R1 is one selected from phenyl, biphenyl or 6-18-membered aryl.

4. A method for producing an organic electroluminescent compound according to any one of claims 1 to 3, comprising the steps of:

weighing the compound A, the compound B, tris (dibenzylideneacetone) dipalladium, tri-tert-butylphosphine and sodium tert-butoxide in a reaction vessel under the protection of nitrogen, continuously adding toluene, reacting under the protection of nitrogen, cooling to room temperature, leaching the precipitate after the precipitate is separated out, and purifying by column chromatography to obtain the compound La or Lb.

Wherein, compound a:

compound B:

one kind of (1).

5. The method according to claim 4, wherein the molar ratio of compound A, compound B, tris (dibenzylideneacetone) dipalladium, tri-tert-butylphosphine and sodium tert-butoxide is 1: 1.05: 0.01: 0.022: 2.

6. the method according to claim 5, wherein the molar volume ratio of the compound A to the toluene is (24-26) mmol: 100 mL.

7. The method of claim 5, wherein the reaction temperature is 120 ℃ and the reaction time is 8-12 h.

8. Use of the organic electroluminescent compound according to any one of claims 1 to 3 or the organic electroluminescent compound produced by the production process according to any one of claims 4 to 7 for the production of organic electroluminescent devices.

Background

In the early 60 s of the 20 th century, organic electroluminescence was observed. In 1963, Pope et al at university of New York, USA, discovered that when several hundred volts of voltage is applied to anthracene crystal, the crystal has weak blue light emission phenomenon, which opens up the way for developing photoelectric materials. However, this finding has not been considered to be important because the required driving voltage is too high and the light emission efficiency is low. In 1987, doctor Deng Qingyun reported an electroluminescent diode technology based on organic luminescent materials, and mainly adopts a vacuum evaporation mode to prepare a double-layer device with a transmission layer and a luminescent layer, so that the quantum efficiency is improved to 1%, and the quantum efficiency can reach 1000cd/m under the working voltage lower than 10V²The brightness of the organic electroluminescent device is attracted by the wide attention of scientific enthusiasts in the world, and the organic electroluminescent technology is pushed to move to the practical stage.

With the continuous development of Organic Light-Emitting diode technology, Organic Light-Emitting devices (OLEDs for short) are widely used in the fields of information display and illumination by virtue of their advantages of self-luminescence, wide Light-Emitting viewing angle, thinness, low driving voltage, fast response speed, flexibility, folding, and the like. The light-emitting layer is an important component of OLEDs and is composed of three organic electroluminescent materials, namely red, green and blue, among which organic materials can be used as materials required for illumination and are also particularly important materials in display technology. Although the organic electroluminescent material has been found for a long time, all properties of the organic materials disclosed in the prior art do not fully satisfy the requirements of mass production and applications, and it is difficult to provide high luminous efficiency at low voltage.

Therefore, the search for high-performance and stable organic electroluminescent materials is a problem that needs to be solved by those skilled in the art.

Disclosure of Invention

In view of the above, the present invention provides an organic electroluminescent compound of formula La or Lb, which has the following structural formula:

wherein R1, R2, R3 are selected from C6-C30 aryl, 3-30 membered aromatic heterocyclic group;

x1, X2, X3, X4 and X5 are selected from C or N, up to three N being present simultaneously.

The invention has the beneficial effects that: the invention provides a heterocyclic luminescent material, wherein a heterocyclic unit has higher ionization potential and higher electron mobility, five-membered rings and six-membered rings are combined to reduce the symmetry of molecules and increase the conformational isomers of the molecules, and a group has a rigid plane structure, so that the molecules are not easy to crystallize and aggregate, therefore, the electronic transmission material can improve the characteristics of luminous efficiency, driving voltage, service life and the like in an organic luminescent device.

Preferably, the formula Lb further includes ring G, which is a substituted or unsubstituted 6-to 18-membered aromatic heterocyclic group having the following formula:

preferably, when X1 ═ X3 ═ X5 ═ N, R1 is selected from one of phenyl and biphenyl;

when the X1 ═ X2 ═ N, the R1 is selected from one of phenyl and biphenyl;

when the X1 ═ X5 ═ N, the R1 is selected from one of phenyl, biphenyl, or 6-to 18-membered aryl;

when the X1 is equal to N, the G ring is a pyridine ring, and the R1 is one selected from phenyl, biphenyl or 6-18-membered aryl.

Preferably, the chemical structural formula of the organic light-emitting compound is one of formula L001-formula L080:

the invention also provides a preparation method of the organic electroluminescent compound, which comprises the following steps:

weighing a compound A, a compound B, tris (dibenzylideneacetone) dipalladium, tri-tert-butylphosphine and sodium tert-butoxide in a reaction vessel under the protection of nitrogen, continuously adding toluene, reacting under the protection of nitrogen, cooling to room temperature, leaching a precipitate after the precipitate is separated out, and purifying by column chromatography to obtain the compound La or Lb;

wherein, compound a:

compound B:

one kind of (1).

Preferably, the molar ratio of the compound A, the compound B, the tris (dibenzylideneacetone) dipalladium, the tri-tert-butylphosphine and the sodium tert-butoxide is 1: 1.05: 0.01: 0.022: 2.

preferably, the molar volume ratio of the compound a to the toluene is (24-26) mmol: (100) and (mL).

Preferably, the reaction temperature is 120 ℃ and the reaction time is 8-12 h.

The invention also provides an application of the organic electroluminescent compound or the compound prepared by the preparation method in an organic electroluminescent device.

According to the technical scheme, compared with the prior art, the organic electroluminescent compound, the preparation method and the application are disclosed and provided, and the organic electroluminescent compound has the advantages of short synthetic route, simple process, easily obtained raw materials, low cost and suitability for industrial production; in addition, the compound prepared by the preparation method has the advantages of high performance and good stability, and can be applied to an organic electroluminescent device to provide high luminous efficiency under the condition of low voltage.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

An organic light-emitting compound of formula L002, the reaction route of the preparation method of the organic light-emitting compound is as follows:

the preparation method comprises the following steps:

under the protection of nitrogen, a compound represented by a formula 002-A (25.7mmol, 10.00g), a compound represented by a formula 002-B (26.9mmol, 9.15g), tris (dibenzylideneacetone) dipalladium (0.26mm ol, 0.24g), tri-tert-butylphosphine (0.51mmol, 0.21g) and sodium tert-butoxide (51.4mmol, 4.93g) are weighed in a reaction system, 100mL of toluene is added, the reaction is carried out for 10 hours under the protection of nitrogen and at 120 ℃, then the reaction system is cooled to room temperature, after precipitation, the precipitation is filtered by suction, and the product is purified by column chromatography (column height is 8cm) to obtain a compound L002, namely an organic luminescent compound (11.33g, yield is 68%).

The purity of the organic luminescent compound is 99.9 percent by HPLC detection;

the calculated mass spectrum value of the organic luminescent compound is 648.77, and the mass spectrum test value is 649.62;

elemental analysis

The calculated values are: 87.01 percent of C; 4.35 percent of H; 8.64 percent of N;

the test values are: 87.02 percent of C; 4.34 percent of H; 8.65 percent of N.

Example 2

An organic luminescent compound of formula L017, the reaction route of the preparation method of the organic luminescent compound is as follows:

the preparation method comprises the following steps:

weighing a compound represented by a formula 017-A (25.7mmol, 10.03g), a compound represented by a formula 017-B (26.9mmol, 9.15g), tris (dibenzylideneacetone) dipalladium (0.26mmol, 0.24g), tri-tert-butylphosphine (0.51mmol, 0.21g) and sodium tert-butoxide (51.4mmol, 4.93g) in a nitrogen protective atmosphere, adding 100mL of toluene, reacting at 120 ℃ for 10 hours, cooling to room temperature, filtering the precipitate after precipitation, and purifying by using column chromatography (8 cm high column height) to obtain a compound L017 which is an organic luminescent compound (11.75g, 69 percent).

The purity of the organic luminescent compound is 99.9 percent by HPLC detection;

the calculated mass spectrum value of the organic luminescent compound is 662.75, and the mass spectrum test value is 663.52;

elemental analysis

The calculated values are: 85.18 percent of C; 3.95 percent of H; 8.45 percent of N; 2.41 percent of O;

the test values are: 85.19 percent of C; h, 3.96 percent; 8.44 percent of N; 2.40 percent of O.

Example 3

An organic light-emitting compound of formula L022, the reaction scheme of the preparation method of the organic light-emitting compound is as follows:

the preparation method comprises the following steps:

under the protection of nitrogen, a compound shown as a formula 022-A (25.7mmol, 9.95g), a compound shown as a formula 022-B (26.9mmol, 9.15g), tris (dibenzylideneacetone) dipalladium (0.26mmol, 0.24g), tri-tert-butylphosphine (0.51mmol, 0.21g) and sodium tert-butoxide (51.4mmol, 4.93g) are weighed in a reaction system, 100mL of toluene is added, the reaction system is reacted for 10 hours under the protection of nitrogen and at 120 ℃, then the reaction system is cooled to room temperature, after precipitation, the precipitate is filtered by suction and purified by column chromatography (column height is 8cm), and a compound L022, namely an organic luminescent compound (11.82g, yield is 71%), is obtained.

The purity of the organic luminescent compound is 99.9 percent by HPLC detection;

the calculated mass spectrum value of the organic luminescent compound is 647.78, and the mass spectrum test value is 648.81;

elemental analysis

The calculated values are: 89.00 percent of C; 4.51 percent of H; 6.49 percent of N;

the test values are: 89.01 percent of C; 4.50 percent of H; and 6.49 percent of N.

Example 4

An organic light-emitting compound of formula L039, the reaction scheme of the process for the preparation of the organic light-emitting compound is as follows:

the preparation method comprises the following steps:

under the protection of nitrogen, a compound shown as a formula 039-A (25.7mmol, 12.26g), a compound shown as a formula 039-B (26.9mmol, 9.15g), tris (dibenzylideneacetone) dipalladium (0.26mmol, 0.24g), tri-tert-butylphosphine (0.51mmol, 0.21g) and sodium tert-butoxide (51.4mmol, 4.93g) are weighed out in a reaction system, 100mL of toluene is added, the reaction system is reacted for 10 hours at 120 ℃ under the protection of nitrogen, then the reaction system is cooled to room temperature, after precipitation, the precipitation is filtered by suction, and the product is purified by column chromatography (column height is 8cm) to obtain a compound L039, namely an organic luminescent compound (12.70g, yield is 67%).

The purity of the organic luminescent compound is 99.9 percent by HPLC detection;

the calculated mass spectrum value of the organic luminescent compound is 737.86, and the mass spectrum test value is 738.57;

elemental analysis

The calculated values are: 87.90 percent of C; 4.23 percent of H; 6.69 percent of N; 2.17 percent of O;

the test values are: 87.91 percent of C; 4.22 percent of H; 6.68 percent of N; 2.18 percent of O.

Example 5

An organic light-emitting compound of formula L042, the reaction scheme of the method for preparing the organic light-emitting compound is as follows:

the preparation method comprises the following steps:

under the protection of nitrogen, a compound shown as a formula 042-A (25.7mmol, 9.61g), a compound shown as a formula 042-B (26.9mmol, 9.15g), tris (dibenzylideneacetone) dipalladium (0.26mmol, 0.24g), tri-tert-butylphosphine (0.51mmol, 0.21g) and sodium tert-butoxide (51.4mmol, 4.93g) are weighed in a reaction system, 100mL of toluene is added, the reaction system is reacted for 10 hours under the protection of nitrogen and at 120 ℃, then the reaction system is cooled to room temperature, after precipitation, the precipitation is filtered by suction, and the product is purified by column chromatography (column height is 8cm) to obtain a compound L042, namely an organic luminescent compound (11.90g, yield is 73%).

The purity of the organic luminescent compound is 99.9 percent by HPLC detection;

the calculated mass spectrum value of the organic luminescent compound is 634.78, and the mass spectrum test value is 635.62;

elemental analysis

The calculated values are: 90.82 percent of C; 4.76 percent of H; 4.41 percent of N;

the test values are: c, 90.81 percent; 4.75 percent of H; n is 4.42 percent.

Example 6

The organic luminescent compound has a formula of L061, and the reaction route of the preparation method of the organic luminescent compound is as follows:

the preparation method comprises the following steps:

weighing a compound represented by a formula 061-A (25.7mmol, 10.57g), a compound represented by a formula 061-B (26.9mmol, 9.15g), tris (dibenzylideneacetone) dipalladium (0.26mmol, 0.24g), tri-tert-butylphosphine (0.51mmol, 0.21g) and sodium tert-butoxide (51.4mmol, 4.93g) in a nitrogen protective atmosphere, adding 100mL of toluene, reacting at 120 ℃ for 10 hours, cooling to room temperature, filtering the precipitate after the precipitate is separated out, and purifying by using column chromatography (column height 8cm) to obtain a compound L061, namely an organic luminescent compound (11.22g, yield 65%).

The purity of the organic luminescent compound is 99.9 percent by HPLC detection;

the calculated mass spectrum value of the organic luminescent compound is 671.80, and the mass spectrum test value is 672.58;

elemental analysis

The calculated values are: 89.39 percent of C; 4.35 percent of H; 6.25 percent of N;

the test values are: 89.38 percent of C; 4.34 percent of H; and 6.25 percent of N.

The synthesis methods of other compounds are the same as the above examples, which are not repeated herein, and the mass spectra and molecular formulas of other synthesis examples are shown in table 1 below:

TABLE 1 Mass Spectrometry data for examples 7-16

In order to further illustrate the application effect of the organic electroluminescent compound prepared by the present disclosure in an electroluminescent device, the inventors further performed the following test experiments, specifically as follows:

device example 1

Coating with a thickness ofThe ITO glass substrate is put in distilled water for cleaning for 2 times, ultrasonically cleaned for 30 minutes, repeatedly cleaned for 2 times by distilled water, ultrasonically cleaned for 10 minutes, and after the cleaning by distilled water is finished, solvents such as isopropanol, acetone, methanol and the like are ultrasonically cleaned in sequence, dried, transferred into a plasma cleaning machine, cleaned for 5 minutes and sent into an evaporation plating machine;

first, vapor deposition is carried out on the ITO (anode)Followed by evaporationThe organic luminescent compound with the chemical structural formula of L002 and the doping material Ir (ppy)3 are mixed according to the weight ratio of 95:5, and an electron injection layer is evaporatedEvaporation cathodePreparing an organic electroluminescent device;

the inventor adopts a KEITHLEY 2400 type source measuring unit and a CS-2000 spectral radiance luminance meter to test the light-emitting characteristics of the obtained organic electroluminescent device so as to evaluate the driving voltage, the service life and the current efficiency of the device;

referring to the preparation method of the organic electroluminescent device, the organic iridium metal complex L002 is replaced by L013, L017, L022, L023, L026, L039, L040, L042, L044, L048, L052, L057, L061, L063 and L078 respectively, and the organic electroluminescent device of the corresponding organic iridium metal complex is prepared.

Comparative example 1:

an organic electroluminescent device was prepared in the same manner as in device example 1, wherein the compound structural formula of the light-emitting layer host was as follows:

the prepared organic electroluminescent device was tested in the same manner as in device example 1, and the results are shown in table 2 below.

As can be seen from Table 2, the organic electroluminescent device prepared by using the compound provided by the present invention as the luminescent material of the host of the luminescent layer is superior to the organic electroluminescent device of the compound of the comparative example, the driving voltage is significantly reduced, and the current efficiency and the lifetime are significantly improved.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.