CN113121410A

CN113121410A - Organic circular polarization luminescent material and preparation method and application thereof

Info

Publication number: CN113121410A
Application number: CN202110315424.7A
Authority: CN
Inventors: 许炳佳; 郑奕涛; 左凌琪; 黄梓濠; 张乐天; 吴可傲; 石光; 宋子存
Original assignee: South China Normal University
Current assignee: South China Normal University
Priority date: 2021-03-24
Filing date: 2021-03-24
Publication date: 2021-07-16
Anticipated expiration: 2041-03-24
Also published as: CN113121410B

Abstract

The invention discloses an organic circular polarization luminescent material and a preparation method and application thereof. The organic circular polarization luminescent material simultaneously has the characteristics of circular polarization luminescence, aggregation-induced delayed fluorescence and photoluminescence. The organic circular polarization luminescent material provided by the invention is simple in preparation method and low in preparation cost. The two organic circular polarization luminescent materials prepared by the invention have obviously improved luminescent performance, and are more suitable to be used as luminescent layer materials for preparing high-performance luminescent devices.

Description

Organic circular polarization luminescent material and preparation method and application thereof

Technical Field

The invention belongs to the technical field of organic luminescent materials, and particularly relates to an organic circular polarization luminescent material and a preparation method and application thereof.

Background

Organic light-emitting diodes (OLEDs) have the advantages of wide viewing angle, rich colors, low driving voltage, fast response speed, thin and light volume, flexibility, even folding and the like, and are expected to be widely applied to electronic products such as mobile phones, televisions, tablet computers, wearable intelligent devices and the like. Therefore, OLEDs are highly regarded by the scientists and governments of all countries, and are one of the hot and key areas for current research and development.

However, most of the organic light-emitting materials reported at present are transient fluorescent molecules based on singlet transition luminescence, and the theoretical limit of the quantum efficiency in the OLEDs prepared by using the transient fluorescent molecules as light-emitting layers is only 25% (tag.al., adv.mater.2010,22,2159; tag.al., chem.commun.,2010,46, 2221); the room temperature phosphorescent material is usually an organic metal complex containing noble metals such as Ir, Pt and the like, the preparation cost is high, and the phosphorescent material has long exciton life, is easy to cause triplet-triplet annihilation, and leads the efficiency to be seriously reduced. Whereas a Thermally Activated Delayed Fluorescence (TADF) material can effectively utilize triplet excitons through reverse intersystem crossing, and the theoretical limit of quantum efficiency in an OLED device prepared with it as a light emitting layer can also reach 100% (advanced. Compared with phosphorescent materials, the TADF materials belong to pure organic micromolecules, have adjustable luminescent colors, simple preparation process and low production cost, and simultaneously make up the defects of the traditional instantaneous fluorescent and phosphorescent materials. Therefore, TADF materials are considered to be third generation OLEDs luminescent materials following transient fluorescence and phosphorescence.

However, most of the existing TADF compounds are affected by an aggregate-emitted Quenching (ACQ) effect, that is, the compounds emit light in an aggregate state to be weakened or even not emit light, as in the conventional organic light emitting materials. In 2001, the Tang Benzhou professor of hong Kong science university proposed Aggregation-induced luminescence (Aggregation-Indu)cedemision, AIE) concept, which can overcome the effect of ACQ effect and ensure that the material emits light efficiently in the solid state (tang.al., chem.commun.2001, 1740). In 2015, the pool professor of the university in zhongshan organically combines the AIE and TADF properties for the first time, and a TADF material capable of emitting light efficiently in the solid state was developed (chiet.al., angelw.chem.int.ed., 2015,54, 874); subsequently, a series of organic materials having Aggregation-induced delayed fluorescence (AIDF) properties were internationally and sequentially reported (chiet. al., chem. soc. rev.,2017,46, 915). To date, research on aggregation-induced delayed fluorescence materials has become a very active area of research. The method is expected to overcome the problem of the ACQ of the TADF material and develop a non-doped organic material with high-efficiency luminescence, thereby breaking through the key technical bottleneck of OLEDs. In addition, the display effect of the simple OLEDs is greatly influenced by ambient light, and in order to effectively resist the ambient light and reduce the interference in display, most OLEDs are mounted with a circular polarizer composed of a polarizer and 1/4 wave plates. However, the organic materials used in the OLEDs display screen at present do not have the property of circular polarized light emission, i.e. cpl (circular polarized luminescence), and 50% of the emitted light is absorbed by the polarizer after passing through the 1/4 wave plate, resulting in serious energy loss (leeet. Recently, some organic circularly polarized light emitting materials having a thermally activated delayed fluorescence characteristic have been reported internationally. However, most materials have asymmetric factors (| g) of circular polarization luminescence_lumAll at 5X 10 |)^-3The improvement of the performance of the materials and the OLEDs is severely restricted.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art described above. To this end, a first aspect of the present invention proposes an organic circularly polarized light emitting material belonging to an organic circularly polarized light emitting material having aggregation-induced delayed fluorescence characteristics and Mechanoluminescence characteristics (ML).

The second aspect of the invention provides a preparation method of the organic circular polarization luminescent material, which is simple and has low preparation cost.

The third aspect of the present invention provides an application of the above organic circularly polarized light emitting material.

According to a first aspect of the present invention, an organic circularly polarized light emitting material is provided, which has a structural formula shown in formula (I) or formula (II):

wherein, the formula (I) is R type, and the formula (II) is S type.

According to a second aspect of the present invention, there is provided a method for preparing the above organic circularly polarized light emitting material, comprising the following steps:

under inert atmosphere, 3, 6-dibromophthalic anhydride and (R) -1,2,3, 4-tetrahydro-1-naphthylamine carry out reflux reaction to obtain a compound (III), and then 9H-carbazole (CAS number: 86-74-8) and the compound (III) carry out coupling reaction to obtain a compound of a formula (I); or

Under inert atmosphere, carrying out reflux reaction on 3, 6-dibromophthalic anhydride and (S) -1,2,3, 4-tetrahydro-1-naphthylamine to obtain a compound (IV), and then carrying out coupling reaction on 9H-carbazole and the compound (IV) to obtain a compound in a formula (II);

the reaction formula is as follows:

in some embodiments of the invention, the molar ratio of the 3, 6-dibromophthalic anhydride, the (R) -1,2,3, 4-tetrahydro-1-naphthylamine, and the 9H-carbazole in the preparation of the compound of formula (I) is 1: 1: (2-3).

In some preferred embodiments of the present invention, the molar ratio of the 3, 6-dibromophthalic anhydride, the (S) -1,2,3, 4-tetrahydro-1-naphthylamine and the 9H-carbazole in the preparation of the compound of formula (II) is 1: 1: (2-3).

In some more preferred embodiments of the present invention, the solvent in the reflux reaction is selected from at least one of N, N-dimethylformamide, N-dimethylacetamide, glacial acetic acid, and dimethylsulfoxide; further preferably, the reaction solvent is selected from at least one of N, N-dimethylformamide and glacial acetic acid; still more preferably, the reaction solvent is N, N-dimethylformamide.

In some more preferred embodiments of the present invention, the temperature of the reflux reaction is 130 ℃ to 160 ℃ and the time is 12h to 18 h.

In some more preferred embodiments of the present invention, the catalyst for the coupling reaction comprises 2-dicyclohexylphosphine-2 ',6' -diisopropoxybiphenyl, potassium phosphate and tris (dibenzylideneacetone) dipalladium.

In some more preferred embodiments of the present invention, the molar ratio of the 2-dicyclohexylphosphine-2 ',6' -diisopropoxybiphenyl, the potassium phosphate and the tris (dibenzylideneacetone) dipalladium is 1: (6-8): (0.03-0.05).

In some more preferred embodiments of the present invention, the solvent of the coupling reaction is at least one of toluene, tetrahydrofuran, 1, 4-dioxane; further preferably, the solvent for the coupling reaction is toluene.

In some more preferred embodiments of the present invention, the temperature of the coupling reaction is between 110 ℃ and 130 ℃ and the time is between 18h and 36 h.

In some more preferred embodiments of the present invention, the method further comprises precipitating a crude product after the coupling reaction, and separating, purifying and drying the crude product to obtain the compound of formula (I) or the compound of formula (II).

In some more preferred embodiments of the invention, the crude product is isolated by adding absolute ethanol to the reaction mass and spin-drying in vacuo.

In some more preferred embodiments of the present invention, the separation and purification is performed by silica gel column chromatography separation followed by precipitation purification; further preferably, the eluent for silica gel column chromatography separation is a medium-polarity solvent and a low-polarity solvent, and the volume ratio of the medium-polarity solvent to the low-polarity solvent is 1: (0.5-5).

In some more preferred embodiments of the present invention, the volume ratio of the medium-polar solvent to the low-polar solvent is 1: 2.

in some more preferred embodiments of the present invention, the medium polar solvent is selected from at least one of dichloromethane, chloroform, ethyl acetate, tetrahydrofuran; the low-polarity solvent is at least one selected from hydrocarbon solvents such as petroleum ether, cyclohexane and hexane.

According to the third aspect of the present invention, the application of the organic circular polarization light emitting material or the organic circular polarization light emitting material prepared by the preparation method of the organic circular polarization light emitting material in a light source device is provided.

In some embodiments of the present invention, the light source device is selected from one of an OLED device, a pressure sensing device, a stress imaging device, and a pressure sensitive illumination device.

The technical scheme of the invention has the beneficial effects that:

1. the compound of formula (I) and the compound of formula (II) both have circular polarized luminescence, aggregation-induced delayed fluorescence and photoluminescence characteristics.

2. The TADF lifetime of the compound of formula (I) and the compound of formula (II) of the invention is two orders of magnitude shorter than that of the related art, respectively 24.34 mus and 28.67 mus, and the CPL asymmetry factor is improved by one order of magnitude relative to the related art, respectively 1.46 multiplied by 10^-2and-1.39X 10^-2. The two organic circular polarization luminescent materials prepared by the invention are obviously improved in luminescent performance, and are more suitable to be used as luminescent layer materials for preparing high-performance luminescent devices.

Drawings

The invention is further described with reference to the following figures and examples, in which:

FIG. 1 shows the NMR spectrum of a compound of formula (I) in example 1 of the present invention.

FIG. 2 shows the NMR spectrum of the compound of formula (II) in example 2 of the present invention.

FIG. 3 is a high resolution mass spectrum of the compound of formula (I) in example 1 of the present invention.

FIG. 4 is a high resolution mass spectrum of the compound of formula (II) in example 2 of the present invention.

FIG. 5 is a graph showing the property of aggregation-induced delayed fluorescence of the compound of formula (I) in example 1 and the compound of formula (II) in example 2 in a pure tetrahydrofuran solution in the solid state, respectively.

FIG. 6 is a graph of the aggregation-induced delayed fluorescence properties of the compound of formula (I) in example 1 and the compound of formula (II) in example 2 under air conditions.

FIG. 7 is a graph showing the aggregation-induced delayed fluorescence properties of the compound of formula (I) in example 1 and the compound of formula (II) in example 2 in a pure tetrahydrofuran solution, respectively, after addition of water as a poor solvent.

FIG. 8 shows the CPL spectra and the asymmetry factor plots for the compound of formula (I) in example 1 and the compound of formula (II) in example 2.

FIG. 9 is a photograph showing ML phenomena of the compound of the formula (I) in example 1 and the compound of the formula (II) in example 2.

Detailed Description

The concept and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments to fully understand the objects, features and effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention.

Example 1

This example prepares a compound of formula (I), namely (R) -4, 7-bis (9H-carbazol-9-yl) -2- (1,2,3, 4-tetrahydronaphthalen-1-yl) isoindoline-1, 3-dione, by the following process:

s1: synthesizing a compound (III), namely (R) -4, 7-dibromo-2- (1,2,3, 4-tetrahydronaphthalene-1-yl) isoindoline-1, 3-dione, with the reaction formula:

under the protection of argon, 3, 6-dibromophthalic anhydride (0.60g, 1.96mmol) is added into a three-necked flask, stirred and dissolved by 8mL of DMF, then (R) - (-) -1,2,3, 4-tetrahydro-1-naphthylamine (0.29g, 1.97mmol) is added, and the mixture is heated to 150 ℃ for reflux reaction for 16 h. And cooling the reaction solution to room temperature, pouring the reaction solution into 50mL of ice saturated saline to precipitate a solid, and performing suction filtration to obtain a crude product, wherein the volume ratio of the crude product is 1:1, and performing silica gel column chromatography separation and purification by taking a dichloromethane and petroleum ether mixed solution as an eluent, and drying the product in vacuum to obtain 0.50g of yellow solid with the yield of 58%.

S2: synthesis of a Compound of formula (I), (R) -4, 7-bis (9H-carbazol-9-yl) -2- (1,2,3, 4-tetrahydronaphthalen-1-yl) isoindoline-1, 3-dione, the reaction formula:

to a three-necked flask, under argon protection, compound III (0.20g, 0.46mmol), 9H-carbazole (0.19g, 1.14mmol), 2-dicyclohexylphosphorus-2 ',6' -diisopropoxy-1, 1' -biphenyl (Ruphos, 0.16g, 0.34mmol), and potassium phosphate (0.49g, 2.31mmol) were added in this order and dissolved with 10mL of toluene. Bubbling was carried out for 40min, and after adding 0.01g of Pd2(dba)3, the mixture was heated to 120 ℃ to react for 24 hours. After the reaction was cooled to room temperature, 20mL of ethanol was added, sonicated and vacuum dried in a rotary evaporator. And (3) separating and purifying the crude product by using a silica gel column chromatography by using a mixed solution of dichloromethane and petroleum ether with a volume ratio of 1:1 as an eluent, re-precipitating the obtained product by using dichloromethane and methanol for further purification, and drying the product in vacuum to obtain 0.17g of yellow solid with the yield of 60%.

Example 2

This example prepares a compound of formula (II), namely (S) -4, 7-bis (9H-carbazol-9-yl) -2- (1,2,3, 4-tetrahydronaphthalen-1-yl) isoindoline-1, 3-dione, by the following process:

s1: synthesizing a compound (IV), namely (S) -4, 7-dibromo-2- (1,2,3, 4-tetrahydronaphthalene-1-yl) isoindoline-1, 3-dione, with the reaction formula:

under the protection of argon, 3, 6-dibromophthalic anhydride (0.20g, 0.65mmol) was charged into a three-necked flask, and stirred and dissolved in 3mL of DMF, and (S) - (+) -1,2,3, 4-tetrahydro-1-naphthylamine (0.10g, 0.68mmol) was added thereto, and the mixture was heated to 150 ℃ for reflux reaction for 16 hours. Cooling the reaction liquid to room temperature, pouring the reaction liquid into 20mL of ice saturated salt solution to separate out a solid, performing suction filtration, performing silica gel column chromatography separation and purification on the obtained crude product by using a mixed solution of dichloromethane and petroleum ether with a volume ratio of 2:3 as an eluent, and performing vacuum drying on the product to obtain 0.11g of a yellow solid with the yield of 40%.

S2: synthesis of a Compound of formula (II), namely (S) -4, 7-bis (9H-carbazol-9-yl) -2- (1,2,3, 4-tetrahydronaphthalen-1-yl) isoindoline-1, 3-dione, the reaction formula is:

to a three-necked flask, under argon protection, compound IV (0.23g, 0.53mmol), 9H-carbazole (0.22g, 1.32mmol), 2-dicyclohexylphosphorus-2 ',6' -diisopropoxy-1, 1' -biphenyl (Ruphos, 0.16g, 0.34mmol), and potassium phosphate (0.56g, 2.64mmol) were added in this order, and dissolved with 10mL of toluene. Bubbling was carried out for 40min, and 0.01g of Pd2(dba)3 was added thereto, followed by heating to 120 ℃ for reaction for 24 hours. After the reaction was cooled to room temperature, 20mL of ethanol was added, sonicated and vacuum dried in a rotary evaporator. And (3) separating and purifying the crude product by using a silica gel column chromatography by using a mixed solution of dichloromethane and petroleum ether with a volume ratio of 1:2 as an eluent, re-precipitating the obtained product by using dichloromethane and methanol for further purification, and drying the product in vacuum to obtain 0.12g of yellow solid with the yield of 37%.

Test example 1

The nuclear magnetic resonance hydrogen spectra of the compound of formula (I) in example 1 and the compound of formula (II) in example 2 are shown in figures 1 and 2 respectively; the high resolution mass spectra of the compound of formula (I) in example 1 and the compound of formula (II) in example 2 are shown in fig. 3 and 4, respectively; the AIDF properties of the compound of formula (I) in example 1 and the compound of formula (II) in example 2 are shown in FIGS. 5-7, wherein FIG. 5 is a graph of the aggregation-induced delayed fluorescence properties of the compound of formula (I) in example 1 and the compound of formula (II) in example 2 in solid state in pure tetrahydrofuran solution, respectively; FIG. 6 is a graph of the aggregation-induced delayed fluorescence properties of the compound of formula (I) in example 1 and the compound of formula (II) in example 2 under air conditions; FIG. 7 is a graph showing the aggregation-induced delayed fluorescence properties of the compound of formula (I) in example 1 and the compound of formula (II) in example 2 in a pure tetrahydrofuran solution, respectively, after addition of water as a poor solvent; the CPL spectra and the asymmetry profiles of the compound of formula (I) in example 1 and the compound of formula (II) in example 2 are shown in FIG. 8; the photographs of the ML phenomenon of the compound of formula (I) in example 1 and the compound of formula (II) in example 2 are shown in FIG. 9.

As can be seen from FIG. 5, in the pure tetrahydrofuran solution, the compound of formula (I) in example 1 and the compound of formula (II) in example 2 both emitted very little light; however, in the solid state, there was a significant increase in fluorescence for both compound of formula (I) in example 1 and compound of formula (II) in example 2, indicating that both compound of formula (I) and compound of formula (II) have aggregation-induced emission characteristics.

As can be seen from fig. 6, under air conditions, both the compound of formula (I) in example 1 and the compound of formula (II) in example 2 have a short lifetime in the solid state on the nanosecond scale and a long lifetime on the microsecond scale, which indicates that both the compound of formula (I) and the compound of formula (II) have TADF characteristics.

As can be seen from fig. 7, the compounds of formula (I) in example 1 and the compounds of formula (II) in example 2 only present a short lifetime in the order of nanoseconds in a pure tetrahydrofuran solution; when the poor solvent water was added to the solution, the compound began to aggregate, with a long lifetime on the order of microseconds, indicating that aggregation induces the compound to produce TADF.

As can be seen from fig. 8, the compound of formula (I) in example 1 and the compound of formula (II) in example 2 exhibit mirror-symmetric CPL signals with high asymmetry factor, indicating that the compounds of formula (I) and formula (II) of the present invention have excellent CPL luminescence properties.

As can be seen from fig. 9, solid samples of the compound of formula (I) in example 1 and the compound of formula (II) in example 2 fluoresce yellow when scratched with an iron spoon, indicating that both the compound of formula (I) and the compound of formula (II) have ML properties.

Test example 2

This test example was conducted separatelyThe CPL, aid f and ML properties of the compound of formula (I) in example 1 and the compound of formula (II) in example 2 are shown. Wherein: maximum fluorescence emission wavelength (lambda) of a sample in a solid state by using Edinburgh FLS980 steady-state transient fluorescence spectrometer_PL,max) And AIDF performance is measured, CPL performance of the sample is measured by a CPL-300 spectrometer of JACSO, and ML performance of the sample is measured by QE65 Pro of ocean optics.

The results are shown in table 1:

TABLE 1

Note: the "-" preceding the CPL asymmetry factor value in table 1 indicates the direction.

As can be seen from Table 1, the compound of formula (I) and the compound of formula (II) synthesized by the present invention both have circular polarization luminescence, aggregation-induced delayed fluorescence and photoluminescence properties.

Specifically, the TADF lifetimes of the compounds of formula (I) of example 1 and the compounds of formula (II) of example 2 of the present invention are two or more orders of magnitude shorter than those of the related art, 24.34 μ s and 28.67 μ s, respectively, and the CPL asymmetry factor is improved by one order of magnitude, 1.46X 10, respectively, relative to the related art^-2and-1.39X 10^-2. The two organic circular polarization luminescent materials prepared by the invention are obviously improved in luminescent performance, and are more suitable to be used as luminescent layer materials for preparing high-performance luminescent devices.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.

Claims

1. An organic circularly polarized light emitting material, characterized in that: the structural formula is shown as formula (I) or formula (II):

wherein, the formula (I) is R type, and the formula (II) is S type.

2. A method for preparing the organic circularly polarized light emitting material as claimed in claim 1, wherein: the method comprises the following steps:

under inert atmosphere, carrying out reflux reaction on 3, 6-dibromophthalic anhydride and (R) -1,2,3, 4-tetrahydro-1-naphthylamine to obtain a compound (III), and then carrying out coupling reaction on 9H-carbazole and the compound (III) to obtain a compound of a formula (I); or

the reaction formula is as follows:

3. the method for preparing an organic circularly polarized light emitting material according to claim 2, wherein: in preparing the compound of formula (I), the molar ratio of the 3, 6-dibromophthalic anhydride, the (R) -1,2,3, 4-tetrahydro-1-naphthylamine, and the 9H-carbazole is 1: 1: (2-3).

4. The method for preparing an organic circularly polarized light emitting material according to claim 2, wherein: in preparing the compound of formula (II), the molar ratio of the 3, 6-dibromophthalic anhydride, the (S) -1,2,3, 4-tetrahydro-1-naphthylamine, and the 9H-carbazole is 1: 1: (2-3).

5. The method for preparing an organic circularly polarized light emitting material according to claim 2, wherein: in the preparation of the compound of formula (I) or the compound of formula (II), the coupling reaction, the catalyst comprises 2-dicyclohexylphosphine-2 ',6' -diisopropoxybiphenyl, potassium phosphate and tris (dibenzylideneacetone) dipalladium.

6. The method for preparing an organic circularly polarized light emitting material according to claim 2, wherein: the temperature of the reflux reaction is 130-160 ℃, and the time is 12-18 h.

7. The method for preparing an organic circularly polarized light emitting material according to claim 2, wherein: the temperature of the coupling reaction is 110-130 ℃, and the time is 18-36 h.

8. The method for preparing an organic circularly polarized light emitting material according to claim 2, wherein: the solvent in the reflux reaction is at least one selected from N, N-dimethylformamide, N-dimethylacetamide, glacial acetic acid and dimethyl sulfoxide.

9. The method for preparing an organic circularly polarized light emitting material according to claim 2, wherein: and further comprising precipitating a crude product after the coupling reaction, and separating, purifying and drying the crude product to obtain the compound of the formula (I) or the compound of the formula (II).

10. An application of the organic circular polarization luminescent material as claimed in claim 1 or the organic circular polarization luminescent material prepared by the preparation method of the organic circular polarization luminescent material as claimed in claims 2 to 9 in a light source device.