PREPARATION AND USE OF TETRADENTATE PLATINUM(II) COMPLEX

Abstract

The present invention relates to preparation and application of a novel quadridentate platinum (II) complex, and belongs to the field of OLED organic electroluminescent materials. The complex of the present invention has NCNC chelating coordination, a stable structure, a spiro ring structure in the skeleton, a strong molecular stereoscopic property, and weak intermolecular interaction, so that mutual stacking between complex molecules is avoided, the formation of an excimer is greatly inhibited, and thus the efficiency of an OLED device is improved. The complex of the present invention has high fluorescence quantum efficiency, great thermal stability and low quenching constant, and can be used for manufacturing a red-light OLED device with high luminescence efficiency and low roll-off.

##STR00001##

Claims

1. A quadridentate platinum (II) complex, having the structure as shown in the following formula: ##STR00018## wherein R.sub.1-R.sub.22 are independently selected from hydrogen, deuterium, sulfur, halogen, hydroxyl, acyl, alkoxy, acyloxy, amino, nitro, acyl amino, cyano, carboxyl, styryl, amino carbonyl, carbamoyl, benzyl carbonyl, aryloxy, diarylamino, saturated alkyl containing 1-30 C atoms, unsaturated alkyl containing 2-20 C atoms, substituted or unsubstituted aryl containing 5-30 C atoms, and substituted or unsubstituted heteroaryl containing 5-30 C atoms; or adjacent R.sub.1-R.sub.21 are mutually connected into a ring by a covalent bond; the substituted refers to substitution with halogen, deuterium, C.sub.1-C.sub.20 alkyls, C.sub.1-C.sub.10 silyls, and cyano; and a heteroatom in the heteroaryl comprises one or more of N, O, and S.

2. The complex according to claim 1, wherein the R.sub.1-R.sub.21 are independently selected from hydrogen, halogen, amino, nitro, cyano, diarylamino, saturated alkyl containing 1-10 C atoms, aryl containing 5-20 C atoms unsubstituted or substituted with halogen or one or more of C.sub.1-C.sub.4 alkyls, and heteroaryl containing 5-20 C atoms unsubstituted or substituted with halogen or one or more of C.sub.1-C.sub.4 alkyls; or adjacent R.sub.1-R.sub.21 are mutually connected into a ring by a covalent bond; and the halogen comprises F, Cl, and Br.

3. The complex according to claim 2, wherein among 22 groups, namely the R.sub.1-R.sub.22, 0-3 groups are independently represented as diarylamino, aryl containing 5-10 C atoms unsubstituted or substituted with halogen or 1-3 C.sub.1-C.sub.4 alkyls, and N-heteroaryl containing 5-10 C atoms unsubstituted or substituted with halogen or 1-3 C.sub.1-C.sub.4 alkyls; the other groups are independently represented as hydrogen or saturated alkyl containing 1-8 C atoms; and the halogen comprises F and Cl.

4. The complex according to claim 3, wherein among the 22 groups, namely the R.sub.1-R.sub.22, 0-3 groups are independently represented as diphenylamino, phenyl unsubstituted or substituted with halogen or 1-3 C.sub.1-C.sub.4 alkyls, pyridyl unsubstituted or substituted with halogen or 1-3 C.sub.1-C.sub.4 alkyls, and carbazolyl unsubstituted or substituted with halogen or 1-3 C.sub.1-C.sub.4 alkyls; and the other groups are independently represented as hydrogen, fluorine, or saturated alkyl containing 1-4 C atoms.

5. The complex according to claim 1, having the structure as shown in the following formula: ##STR00019## wherein R.sub.1′-R.sub.5′ are independently selected from hydrogen, halogen, diarylamino, saturated alkyl containing 1-10 C atoms, aryl containing 5-20 C atoms unsubstituted or substituted with halogen or one or more of C.sub.1-C.sub.4 alkyls, and heteroaryl containing 5-20 C atoms unsubstituted or substituted with halogen or one or more of C.sub.1-C.sub.4 alkyls; or adjacent R.sub.1′-R.sub.5′ are mutually connected into a ring by a covalent bond; the halogen comprises F, Cl, and Br; and a heteroatom in the heteroaryl comprises any one of N, O, and S.

6. The complex according to claim 5, wherein among 5 groups, namely the 0-3 groups are independently represented as diarylamino, aryl containing 5-10 C atoms unsubstituted or substituted with halogen or 1-3 C.sub.1-C.sub.4 alkyls, and heteroaryl containing 5-10 C atoms unsubstituted or substituted with halogen or 1-3 C.sub.1-C.sub.4 alkyls; the other groups are independently represented as hydrogen, halogen, or saturated alkyl containing 1-8 C atoms; and the halogen comprises F and Cl.

7. The complex according to claim 6, wherein among the 5 groups, namely the R.sub.1′-R.sub.5′, 0-3 groups are independently represented as diphenylamino, phenyl unsubstituted or substituted with C.sub.1-C.sub.4 alkyls, pyridyl unsubstituted or substituted with C.sub.1-C.sub.4 alkyls, and carbazolyl unsubstituted or substituted with C.sub.1-C.sub.4 alkyls; and the other groups are independently represented as hydrogen, fluorine, or saturated alkyl containing 1-4 C atoms.

8. The complex according to claim 1, having one of the following structures: ##STR00020## ##STR00021## ##STR00022## ##STR00023##

9. A precursor, that is ligand, of the complex according to any one of claims 1 to 8, having the following structural formula: ##STR00024## wherein R.sub.1-R.sub.22 are independently selected from hydrogen, deuterium, sulfur, halogen, hydroxyl, acyl, alkoxy, acyloxy, amino, nitro, acyl amino, cyano, carboxyl, styryl, amino carbonyl, carbamoyl, benzyl carbonyl, aryloxy, diarylamino, saturated alkyl containing 1-30 C atoms, unsaturated alkyl containing 2-20 C atoms, substituted or unsubstituted aryl containing 5-30 C atoms, and substituted or unsubstituted heteroaryl containing 5-30 C atoms; or adjacent R.sub.1-R.sub.21 are mutually connected into a ring by a covalent bond; the substituted refers to substitution with halogen, deuterium, C.sub.1-C.sub.20 alkyls, C.sub.1-C.sub.10 silyls, and cyano; and a heteroatom in the heteroaryl comprises one or more of N, O, and S.

10. A method for synthesizing the quadridentate platinum (II) complex according to claim 5, comprising the following steps: subjecting initial substrates S1 and S2 to a Suzuki coupling reaction to obtain a substrate S3; subjecting the S3 and S4 to a Buchwald-Hartwig coupling reaction to obtain a substrate S5; subjecting the S5 and S6 to a reaction to obtain a substrate S7; and subjecting the S7 and K.sub.2PtCl.sub.4 to a chelating reaction to obtain the target platinum (II) complex TM. ##STR00025## ##STR00026##

11. Application of the complex according to any one of claims 1 to 8 in an OLED light-emitting device.

12. The application according to claim 11, wherein the complex according to any one of claims 1 to 8 is used as a phosphorescent doping material with a photon emission effect in a light-emitting layer.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0041] FIG. 1 a structural schematic diagram of an organic electroluminescent device of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

[0042] The present invention is further described in detail with reference to embodiments.

[0043] A method for preparing the above-mentioned complex includes the following steps.

[0044] As shown below, initial substrates S1 and S2 undergo a Suzuki coupling reaction to obtain a substrate S3. The S3 and S4 undergo a Buchwald-Hartwig coupling reaction to obtain a substrate S5. The S5 and S6 undergo a reaction to obtain a substrate S7. The S7 and K2PtCl.sub.4 undergo a chelating reaction to obtain the target platinum (II) complex TM.

##STR00009## ##STR00010##

[0045] All reagents such as initial substrates, intermediates and solvents involved in the synthesis of compounds in the present invention were purchased from Energy Chemical, J&K Scientific, Aladdin, and other suppliers known to persons skilled in the art.

Example 1

[0046] ##STR00011## ##STR00012##

[0047] Synthesis of a compound 3: 24.6 g (0.10 mol) of a compound 1, 14.8 g (0.12 mol) of a compound 2, 3.46 g (0.03 eq., 3.0 mmol) of tetra-(triphenylphosphine) palladium, and 27.6 g (2.0 eq., 0.20 mol) of potassium carbonate were put into a flask, and then 150 mL of dioxane and 50 mL of water were added for a reaction by heating reflux for 8 hours under the protection of nitrogen. After the reaction was stopped, cooling was conducted to room temperature, and rotary evaporation was conducted to remove the solvent. Appropriate amounts of water and ethyl acetate were added for extraction, and an organic phase was collected and dried. After the solvent was removed by rotary evaporation, separation was conducted by using a silica gel flash chromatography column (a mobile phase includes n-hexane and ethyl acetate at a ratio of 10:1), and then recrystallization was conducted to obtain 21.0 g of a target product compound 3 with a yield of 86% and a purity of 99.9%.

[0048] Synthesis of a compound 5: 12.2 g (50 mmol) of the compound 3, 13.0 g (50 mmol) of a compound 4, 450 mg (0.04 eq., 2 mmol) of palladium acetate, 0.40 g (0.08 eq., 4 mmol) of tri-tert-butylphosphine, and 11.22 g (2.0 eq., 0.10 mol) of potassium tert-butoxide were put into a flask, and then 150 mL of toluene was added for a reaction by heating reflux for 8 hours under the protection of nitrogen. After the reaction was stopped, cooling was conducted to room temperature, and rotary evaporation was conducted to remove the solvent. Appropriate amounts of water and ethyl acetate were added for extraction, and an organic phase was collected and dried. After the solvent was removed by rotary evaporation, separation was conducted by using a silica gel flash chromatography column (a mobile phase includes n-hexane and ethyl acetate at a ratio of 10:1), and then recrystallization was conducted to obtain 17.6 g of a target product compound 5 with a yield of 83% and a purity of 99.9%.

[0049] Synthesis of a compound 7: 8.5 g (20 mmol) of the compound 5, 4.7 g (20 mmol) of a compound 6, 225 mg (0.02 eq., 1 mmol) of palladium acetate, 0.20 g (0.04 eq., 2 mmol) of tri-tert-butylphosphine, and 4.5 g (2.0 eq., 0.04 mol) of potassium tert-butoxide were put into a flask, and then 100 mL of toluene was added for a reaction by heating reflux for 8 hours under the protection of nitrogen. After the reaction was stopped, cooling was conducted to room temperature, and rotary evaporation was conducted to remove the solvent. Appropriate amounts of water and ethyl acetate were added for extraction, and an organic phase was collected and dried. After the solvent was removed by rotary evaporation, a crude product was obtained, dissolved in 50 mL of acetic acid and 10 mL of concentrated sulfuric acid, and then heated to 80° C. for a reaction for 3 hours. After the reaction was stopped, cooling was conducted to room temperature, and 200 mL of water was added to the system to precipitate a product. The product was filtered to obtain a crude product. Separation was conducted by using a silica gel flash chromatography column (a mobile phase includes n-hexane and ethyl acetate at a ratio of 10:1), and then recrystallization was conducted to obtain 6.7 g of a target product compound 7 with a yield of 60% and a purity of 99.9%.

[0050] Synthesis of a compound Pt-1: 1.2 g (2.0 mmol) of the compound 7, 160 mg (0.25 eq., 0.5 mmol) of tetrabutylammonium bromide, and 930 mg (1.2 eq., 2.4 mmol) of potasium tetrachloroplatinate were dissolved in 50 mL of acetic acid, vacuumization was conducted, nitrogen was introduced for replacement several times, and then stirring heating was conducted to 130° C. for a reaction for 12 hours. After the reaction was stopped, cooling and rotary evaporation were conducted to remove the solvent. Appropriate amounts of water and ethyl acetate were added for extraction, an organic phase was collected and dried with anhydrous magnesium sulfate, and then the solvent was removed by rotary evaporation. Separation was conducted by using a silica gel flash chromatography column (a mobile phase includes n-hexane and dichloromethane at a ratio of 10:1), and then recrystallization with methanol was conducted to obtain a crude product. The crude product obtained was sublimated under vacuum to obtain 550 mg of a red solid with a total yield of 33% and a purity of 99.95%. Based on mass spectrometry (ESP) ([M+H].sup.−), a theoretical value of C.sub.41H.sub.23N.sub.3OPt was 752.15; and a measured value was 752.10.

Example 2

[0051] ##STR00013##

[0052] A method for preparing Pt-2 was the same as the synthesis route of the Pt-1, except that a compound 9 was used to replace the compound 6. A molecular formula of the compound 9 is shown as follows:

##STR00014##

Example 3

[0053] ##STR00015##

[0054] A method for preparing Pt-3 was the same as the synthesis route of the Pt-1, except that a compound 9 and a compound 10 were used to replace the compound 6 and the compound 2, respectively. A molecular formula of the compound 10 is shown as follows:

##STR00016##

[0055] An application example of the compound of the present invention is described below.

[0056] ITO/TAPC (70 nm)/TCTA:Pt (II) (40 nm)/TmPyPb (30 nm)/LiF (1 nm)/Al (90 nm)

[0057] A method for preparing a device is as follows.

[0058] A transparent anode indium tin oxide (ITO) (10 Ω/sq) glass substrate was ultrasonically cleaned with acetone, ethanol, and distilled water in sequence, and then treated with oxygen plasma for 5 minutes.

[0059] Next, the ITO substrate was installed on a substrate fixator of a vacuum gas phase evaporation apparatus. The system pressure of the evaporation apparatus was controlled at 10.sup.−6 torr.

[0060] After that, TAPC, as a material for a hole transport layer (HTL), was evaporated on the ITO substrate and had a thickness of 70 nm.

[0061] Then, TCTA, as a material for a light-emitting layer (EML), was evaporated and had a thickness of 40 nm, in which a platinum (II) complex with a mass fraction of 10% was doped.

[0062] Then, TmPyPb, as a material for an electron transport layer (ETL), was evaporated and had a thickness of 30 nm.

[0063] Then, LiF with a thickness of 1 nm was evaporated as an electron injection layer (EIL).

[0064] At last, Al with a thickness of 90 nm was evaporated as a cathode, and a device was packaged, as shown in FIG. 1.

##STR00017##

[0065] A device 1, a device 2, and a device 3 were prepared in sequence. Structures and manufacturing methods of the devices were exactly the same, except that the platinum (II) complexes Pt-1, Pt-2, and Pt-3 were sequentially used as a dopant in the light-emitting layer.

TABLE-US-00001 Current Power Voltage Brightness efficiency efficiency EQE λ.sub.m Entry (V) (cd/m.sup.2) (cd/A) (lm/W) (%) (nm) Pt-1 3.87 9450 38.10 35.13 9.07 617 Pt-2 3.78 9680 39.60 36.78 9.76 618 Pt-3 3.72 9850 40.20 38.39 10.91 618

[0066] As shown in the above table, all the organic electroluminescent devices prepared based on the platinum (II) complexes of the present invention have great luminescence properties, in which the device prepared based on the Pt-3 has the best properties including the maximum brightness of 9,850 cd/m.sup.2, the maximum current efficiency of 40.20 cd/A, the maximum power efficiency of 38.39 lm/W, and the maximum external quantum efficiency of 10.91%. Such novel Pt (II) complex of the present invention has NCNC chelating coordination among molecules, a stable structure, a spiro ring structure in the skeleton, a strong molecular stereoscopic property, and weak intermolecular interaction, so that mutual stacking between complex molecules is avoided, the formation of an excimer is greatly inhibited, and thus the efficiency of an OLED device is improved. In summary, compared with a reference device, the properties of an organic electroluminescent device prepared in the present invention are greatly improved, and the novel quadridentate platinum (II) complex metal-organic material involved has a great application value.