A platinum-based tetradentate ligand derivative, preparation method thereof, and electroluminescent device

Abstract

This invention belongs to the field of organic light-emitting materials and semiconductor technology, and discloses a platinum-based tetradentate ligand derivative, its preparation method, and an electroluminescent device. The structural formula of the platinum-based tetradentate ligand derivative is shown in General Formula I. The platinum-based tetradentate ligand derivative of the present invention is applied as a guest luminescent material in the light-emitting layer of an OLED device, resulting in an electroluminescent device with a lower startup voltage, improved device luminous efficiency and device life, and emission in the green to blue range. Furthermore, the platinum-based tetradentate ligand derivative of the present invention can also be applied as an electron transport material in the electron transport layer of an OLED device, which can help streamline the device structure. #imgabs0#

Description

Technical Field

[0001] The present invention relates to the field of organic luminescent materials and semiconductor technology, and in particular to a platinum-based tetradentate ligand derivative, a preparation method thereof, and an electroluminescent device. Background Art

[0002] Compared with liquid crystal displays, organic light-emitting diodes, also known as OLEDs, have the advantages of being foldable or bendable, self-luminous, high contrast, wide operating temperature range, low material cost, high luminous efficiency and low power consumption. OLED displays are expected to become the mainstream display in the future.

[0003] The design and development of luminescent materials is at the core of the OLED field. Phosphorescent guest materials play a decisive role in the efficiency of phosphorescent electroluminescent devices, and device performance can be tuned by designing different types of organic ligands. Currently, the only heavy metal phosphorescent organic complexes suitable for commercial applications are primarily cyclometallated iridium(III) complexes, but iridium metal is expensive and limited in quantity. Platinum(II) complex phosphorescent materials, however, have a high platinum utilization rate in their preparation, making them an attractive alternative to iridium(III) complex phosphorescent materials.

[0004] Compared to cyclometallated platinum (II) complexes with bidentate and tridentate ligands, the rigid molecular structure of cyclometallated platinum (II) complexes based on tetradentate ligands can suppress vibrational coupling and reduce non-radiative transitions, thereby improving quantum efficiency. Furthermore, tetradentate ligands possess high chemical and thermal stability, making them ideal molecules for developing new OLED phosphorescent materials. Conventional OLED devices require materials that emit red, green, and blue light to achieve full-color display.

[0005] However, compared to red and green luminescent materials, excellent blue light emitting materials are relatively scarce. In particular, high-efficiency blue phosphorescent material molecules with stable structures and suitable emission spectra have greater commercial value. Therefore, the design and development of new phosphorescent blue light emitting materials with long lifespans and high luminescence efficiency has been a long-term goal in the field. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides a platinum-based tetradentate ligand derivative, a preparation method thereof, and an electroluminescent device.

[0007] The platinum-based tetradentate ligand derivative, its preparation method, and electroluminescent device of the present invention are achieved through the following technical solutions:

[0008] The present invention provides a platinum-based tetradentate ligand derivative, and its structural formula is shown in general formula I.

[0009] .

[0010] In the general formula I, A is a substituted or unsubstituted C3~C 15 Heteroaryl, C3~C 15 The first heteroatom in the heteroaryl group contains at least one of N, O and S. 15 The heteroaryl group is bonded to the main structure to form a ring; the main structure is shown in Formula II. Z1 is a C atom or a N atom.

[0011] R is substituted or unsubstituted C6~C 30 Aryl, C3~C 12 Alkyl, or substituted or unsubstituted C4~C 30 Heteroaryl; C4~C 30 The heteroatoms in the heteroaryl group contain at least one of N, O and S; and C4~C 30 The heteroaryl group is a monocyclic heteroaryl group, a polycyclic heteroaryl group or a condensed-ring heteroaryl group.

[0012] B is a phenyl group or an H atom. When B is a phenyl group, B and the main structure form a ring in a cyclic bonding manner, and R is bonded to the 4-position of the pyridine ring. When B is a H atom, R is bonded to the 2-position of the pyridine ring.

[0013] The present invention "substituted C3~C 15 Heteroaryl”, “substituted C6~C 30 "Aryl", and "substituted C4~C 30 In the heteroaryl group, the substituents are selected from D atoms, cyano groups, C1~C 12 Any one of a C1~C6 alkyl group, a C1~C6 halogenated alkyl group, and a phenyl group.

[0014] The platinum-based tetradentate ligand derivative of the present invention can be regarded as consisting of the left With the right The left and right structures are respectively referred to as the left structure and the right structure. The "#" indicates the position of the O bonding in the left and right structures. It should be noted that the two Pt atoms shown in the left and right structures are the same Pt atom in the same complex. The same Pt atom is shown in the two structures for ease of understanding.

[0015] Preferably, the ring formed by bonding A to the main structure is any one of the groups Y1 to Y13:

[0016] .

[0017] In Y1~Y13, * represents the position where the ring formed by A and the main structure is bonded to the Pt atom in the general formula I. It indicates the position where the ring formed by A and the main structure is bonded to the benzene ring in the general formula I.

[0018] Table 1 Structures of compounds r1 to r42

[0019] More preferably, when Z1 in the right-hand structure is a N atom, the ring formed by the bonding of A and the main structure in the left-hand structure is Y1 or Y2. It should also be noted that the above-mentioned left-hand structure and right-hand structure of the present invention are respectively provided by L series intermediates and M series intermediates, that is, the platinum-based tetradentate ligand derivative of the present invention is obtained by reacting L series intermediates and M series intermediates. Among them, when the rings formed by the bonding of A and the main structure are Y1 to Y13, the L series intermediates represented by L1 to L13 are respectively selected to provide the corresponding left-hand structure. When B in the right-hand structure is a phenyl group, the M series intermediate represented by M1 is selected to provide the main structure of the corresponding right-hand structure. When B in the right-hand structure is an H atom and Z1 is a C atom, the M series intermediate represented by M2 is selected to provide the main structure of the corresponding right-hand structure. When B in the right-hand structure is an H atom and Z1 is a N atom, the M series intermediate represented by M3 is selected to provide the main structure of the corresponding right-hand structure. The R group in the right structure is introduced through compound r, and compound r is selected from any one of compound r1 to compound r42, and the structures of compound r1 to compound r42 are shown in Table 1.

[0020] Therefore, based on the above, the second object of the present invention is to provide a method for preparing a platinum-based tetradentate ligand derivative, comprising the following steps, and its synthesis route is shown in the reaction formula 1:

[0021] ;

[0022] Reaction formula 1.

[0023] Step 1: Using the M series intermediate as the raw material for the main structural framework on the right side and compound r as the raw material for the R group, the R group is introduced into the main structural framework on the right side through a Suzuki coupling reaction to obtain intermediate 1. The Suzuki coupling reaction is also called the Suzuki reaction, hereinafter referred to as the Suzuki reaction.

[0024] Step 2: Using the L series intermediate as the raw material for the main structural framework on the left, the L series intermediate is coupled with intermediate 1 via a Williamson ether synthesis reaction to obtain intermediate 2. The Williamson ether synthesis reaction is also called the Williamson etherification reaction, hereinafter referred to as the Williamson etherification reaction.

[0025] Step 3: Using intermediate 2 as a ligand, a coordination reaction is performed to coordinate Pt with the middle position of intermediate 2 in a tetradentate chelate manner to obtain a platinum-based tetradentate ligand derivative:

[0026] It should be noted that the M series intermediate is selected from any one of M1 to M3:

[0027] .

[0028] L series intermediates are selected from any one of L1 to L13:

[0029] .

[0030] The platinum-based tetradentate ligand derivative obtained based on the above-mentioned compound r, L series intermediates and M series intermediates of the present invention is any one of compound 1 to compound 252:

[0031] .

[0032] A third object of the present invention is to provide an electroluminescent device comprising an anode layer, and an organic layer and a cathode layer stacked sequentially from bottom to top on the anode layer. The organic layer comprises a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer stacked sequentially from bottom to top on the anode layer. The light-emitting layer comprises the platinum-based tetradentate ligand derivative described above.

[0033] Preferably, the light-emitting layer is formed by a host light-emitting material and a guest light-emitting material; the guest light-emitting material comprises the platinum-based tetradentate ligand derivative of the present invention, and the mass of the guest light-emitting material accounts for 0.5% to 3% of the total mass of the light-emitting layer.

[0034] Preferably, the platinum-based tetradentate ligand derivative as the guest light-emitting material and the platinum-based tetradentate ligand derivative as the electron transport layer are respectively selected from one of Compound 1, Compound 7, Compound 47, Compound 65, Compound 105, Compound 123, Compound 24, Compound 58, Compound 82 and Compound 116.

[0035] More preferably, the platinum-based tetradentate ligand derivative as the guest light-emitting material and the platinum-based tetradentate ligand derivative as the electron transport layer are respectively selected from one of Compound 38, Compound 59, Compound 96 and Compound 113.

[0036] The platinum-based tetradentate ligand derivative used as the guest light-emitting material and the platinum-based tetradentate ligand derivative used as the electron transport layer are selected from the same platinum-based tetradentate ligand derivative or different platinum-based tetradentate ligand derivatives.

[0037] More preferably, the host luminescent material includes a first host material and a second host material, the first host material accounts for 40% to 60% of the mass of the host luminescent material, and the rest is the second host material, which is 100% in total.

[0038] More preferably, the first host material is any one of compounds RH1-1 to RH1-4:

[0039] .

[0040] Preferably, the second host material is any one of compounds RH2-1 to RH2-4:

[0041] .

[0042] Preferably, the electron transport layer material is the above-mentioned platinum-based tetradentate ligand derivative of the present invention.

[0043] Preferably, a substrate can be used below the anode layer or above the cathode layer. The substrate is made of glass or a polymer material with excellent mechanical strength, thermal stability, water resistance, and transparency. Furthermore, the substrate used for a display can also be used to embed a thin-film transistor array and a specific display image formed by the transistor array. Preferably, the anode layer is made of one or more of indium tin oxide, indium zinc oxide, tin dioxide, and zinc oxide.

[0044] Preferably, the cathode layer is made of a single metal or an alloy. More preferably, the cathode layer is made of one or more of magnesium, silver, aluminum, aluminum-lithium alloy, calcium, magnesium-indium alloy, and magnesium-aluminum alloy. Preferably, the organic layer can be formed on the electrode by any of vacuum thermal evaporation, spin coating, and inkjet printing, and the compound used as the organic functional layer is one or more of organic small molecules, organic macromolecules, and organic polymers.

[0045] Preferably, the hole transport layer can be a single-layer structure, including a hole transport material containing only one compound, a single-layer hole transport layer that has both hole injection and hole transport effects, or a composite hole transport layer containing multiple compounds. The composite hole transport layer is mainly an organic combination of a hole injection layer, a hole transport layer, and an electron blocking layer in a commonly used arrangement in the art.

[0046] A fourth object of the present invention is to provide an electroluminescent device for use in the fields of luminous lighting, image display or photoelectric signal transmission.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The platinum-based tetradentate ligand derivatives of the present invention are shown in general formula I. The molecules have a spatial cross conformation, which is beneficial to improving the solubility of the material in organic solvents. The final products are prepared by purification through silica gel column chromatography, which can effectively improve the insoluble property of the metal coordination compound. Such materials can be used to prepare OLED flexible display screens. Due to the presence of a spatial cross conformation and a large steric hindered group, the platinum-based tetradentate ligand derivatives of the present invention are designed to suppress the accumulation of luminescent molecules, thereby improving the external quantum efficiency of the device and suppressing the red shift of the spectrum; at the same time, such materials have the characteristics of narrow-band luminescence, which can effectively improve the color purity of the device. The strong spin-orbit coupling between the singlet and triplet excited states of the platinum metal atoms in the platinum-based tetradentate ligand derivatives of the present invention can effectively enhance intersystem crossing, showing the potential for simultaneous utilization of singlet and triplet excitons, achieving 100% internal quantum efficiency, and thus improving the luminous efficiency of the device.

[0049] The platinum-based tetradentate ligand derivatives of the present invention, when used as guest luminescent materials in the light-emitting layer, produce devices that significantly improve both luminous efficiency and lifetime, making them excellent organic light-emitting materials. Experimental verification has also shown that the color coordinates of OLED devices prepared using the platinum-based tetradentate ligand derivatives of the present invention fall within the green-to-blue range, laying a foundation for future research into blue-emitting OLED materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic diagram of the structure of the electroluminescent device of the present invention. DETAILED DESCRIPTION

[0051] The technical solutions in the embodiments of the present invention will be described clearly and completely below. It should be noted that, in order to avoid redundancy, the structures of compound r, M series intermediates, L series intermediates, first host materials, second host materials, and platinum-based tetradentate ligand derivatives involved in the following embodiments are shown in the Summary of the Invention. The structures of other organic materials involved in the present invention are as follows:

[0052]

[0053] The purity data involved in the following L series intermediates of the present invention were all measured by gas chromatography, and the molecular weight data were measured by gas chromatography-mass spectrometry; the purity data involved in the M series intermediates and final compounds were all measured by high performance liquid chromatography, and the molecular weight data were measured by liquid chromatography-mass spectrometry. The above test methods are conventional technical means in the art and will not be repeated here.

[0054] In order to avoid redundancy, the present invention refers to the following steps of "drying the organic phase with anhydrous magnesium sulfate, filtering, and concentrating, and purifying the residue by silica gel column chromatography" as "post-treatment".

[0055] The L series intermediates used in the present invention are all prepared by the following steps, and the reaction route is shown in Reaction Formula 2:

[0056] ;

[0057] Reaction formula 2.

[0058] Under argon, 0.3 mol of 1,3-dibromobenzene, 0.3 mol of reactant Y, 0.03 mol of catalyst CuI, 0.6 mol of K2CO3, 0.06 mol of ligand trans-1,2-cyclohexanediamine and 1.0 L of DMSO were mixed and refluxed at 110°C for 72 h. After cooling to room temperature, the reaction solution was filtered through diatomaceous earth and washed with 2 L of ethyl acetate. The filtrate was concentrated and passed through a silica gel column with n-hexane and ethyl acetate to obtain L series intermediates.

[0059] It should be noted that when preparing L12 and L13, 1,3-dibromobenzene in reaction formula 2 was replaced by m-bromoiodobenzene, and the catalyst was replaced by 0.03 mol of CuI to 0.05 mol of Pd(dppf)Cl2. . CH2Cl2, the ligand was replaced by 0.06 mol of trans-1,2-cyclohexanediamine with 0.03 mol of PPh3, the base was replaced by an equal molar amount of Ag2CO3 from K2CO3, the solvent was replaced by an equal volume of acetonitrile from DMSO, and the reaction temperature was lowered to 65°C. The preparation conditions, yields, and yields of the L series intermediates are summarized in Table 2.

[0060] Table 2 Preparation conditions, yields and rates of L series intermediates

[0061]

[0062] It should also be noted that the intermediate M1 used in the present invention is synthesized by the following steps, and its reaction route is shown in Reaction Formula 1:

[0063] ;

[0064] Reaction formula 1.

[0065] 1) Preparation of intermediate M1-1: Under argon, 1.5 mol of 2-bromobenzoic acid, 1.5 mol of 8-aminoquinoline, 0.75 mol of copper powder, 3.0 mol of potassium carbonate, and 5.0 L of isopropanol were mixed. The mixture was heated to 80°C and the reaction was continued for 11 h until the reaction was complete. The mixture was then cooled to room temperature and acidified with 2 L of 6 mol / L aqueous HCl to produce a solid. The solid was filtered and the filter cake was dissolved in 5 L of dichloromethane and extracted with pure water. After post-treatment and rapid rinsing, 301 g of intermediate M1-1 was obtained, with a yield of 76%, a purity of 98%, and a molecular weight of 265.1.

[0066] 2) Preparation of intermediate M1-2: Under argon, 1.1 mol of M1-1 and 16.5 mol of phosphorus oxychloride were mixed, heated to 110°C, and the reaction was continued for 15 h. The mixture was then cooled to room temperature and basified with 3 L of 5.0 mol / L aqueous sodium hydroxide solution. The mixture was then extracted three times with 6 L of dichloromethane (2 L each time). The combined organic phases were post-processed to obtain 175 g of intermediate M1-2, with a yield of 60%, a purity of 98%, and a molecular weight of 265.0.

[0067] 3) Preparation of intermediate M1-3: 0.66 mol of M1-2, 2.0 L of acetic acid, and 3.3 mol of 35% hydrogen peroxide were mixed and reacted at 80°C for 11 h. The solvent was then removed by concentration under reduced pressure. 2 L of pure water was added to dilute the residue. A large amount of precipitate was formed. After filtration, the precipitate was rinsed with plenty of water and dried in vacuo at 40°C to obtain 163 g of intermediate M1-3, with a yield of 88%, a purity of 98%, and a molecular weight of 281.0.

[0068] 4) Preparation of intermediate M1-4: Under argon, 0.55 mol of M1-3, 1.5 L of dichloromethane, and 0.28 mol of DMF were mixed. 0.66 mol of phosphorus oxybromide was slowly added dropwise at 0°C. After complete addition, the mixture was warmed to room temperature and the reaction continued for 10 hours until completion. Saturated sodium carbonate solution was then slowly added to adjust the pH to 7-8. The organic phase was separated, and the aqueous phase was extracted three times with 6 L of dichloromethane (2 L each time). The combined organic phases were post-processed to yield 121 g of intermediate M1-4, with a yield of 64%, a purity of 98%, and a molecular weight of 345.0.

[0069] 5) Preparation of intermediate M1-5: Under argon, 0.35 mol of M1-4, 4.0 mmol of CuI, 7.0 mmol of the ligand 8-hydroxy-2-methylquinoline, 1.05 mol of tetrabutylammonium hydroxide pentahydrate, 500 mL of DMSO, and 750 mL of water were mixed. The mixture was refluxed at 130°C for 14 h, then cooled to room temperature. The reaction solution was extracted three times with 3 L of ethyl acetate, 1 L each time, and the organic phases were combined. The solvent was concentrated and recrystallized from ethyl acetate-n-heptane to obtain 88 g of intermediate M1-5, with a yield of 90%, a purity of 99%, and a molecular weight of 281.0.

[0070] 6) Preparation of intermediate M1 based on intermediate M1-5: Under argon, 0.3 mol of M1-5, 0.36 mol of pinacol diboronate, 0.015 mol of catalyst Pd(dba)2, 0.030 mol of ligand Pcy3, 0.6 mol of KOAc, and 1000 mL of 1,4-dioxane were mixed. The mixture was refluxed at 110°C for 15 h and then cooled to room temperature. The mixture was basified with 0.5 L of 2.0 mol / L aqueous sodium hydroxide solution, and the mixture was extracted with 3 L of dichloromethane (3 times, 1 L each time). The organic phases were combined, dried over anhydrous magnesium sulfate, filtered, and concentrated. The residue was purified by silica gel column chromatography to obtain 76 g of intermediate M1 with a yield of 68%, a purity of 98%, and a molecular weight of 373.2.

[0071] It should also be noted that the intermediate M2 used in the present invention is synthesized by the following steps, and its reaction route is shown in Reaction Scheme 2:

[0072] ;

[0073] Reaction formula 2.

[0074] 1) Preparation of intermediate M2-1: Under argon, 1.0 mol of 2-bromopyridine, 1.1 mol of 2-bromo-5-chlorophenylboronic acid, 0.05 mol of Pd(PPh3)2Cl2, 2.0 mol of sodium hydroxide, 1.5 L of tetrahydrofuran, and 0.5 L of water were mixed. The mixture was heated to 90°C and reacted for 6 h. The mixture was then filtered while hot and the filter cake was rinsed with a small amount of tetrahydrofuran. The filtrate was concentrated and dissolved in 2 L of dichloromethane. The mixture was extracted with purified water. The organic phase was dried over anhydrous magnesium sulfate, filtered, and concentrated. The residue was purified by silica gel column chromatography to obtain 215 g of intermediate M2-1, with a yield of 80%, a purity of 98%, and a molecular weight of 269.5.

[0075] 2) Preparation of intermediate M2-2: Under argon protection, 0.8 mol of M2-1, 0.04 mol of Pd(PPh3)2Cl2, 0.04 mol of CuI, 0.96 mol of trimethylsilylacetylene and 2.0 L of 2,6-diisopropylaniline DIPA were mixed, the temperature was raised to 80°C and the reaction was continued for 5 h. The reaction solution was spin-dried and purified by silica gel column chromatography to obtain 201 g of intermediate M2-2 with a yield of 88%, a purity of 98%, and a molecular weight of 286.1.

[0076] 3) Preparation of intermediate M2-3: Under argon, 0.7 mol of M2-2, 0.7 mol of potassium carbonate, 2.0 L of dichloromethane, and 1.0 L of methanol were mixed and stirred at room temperature for 1 hour until the reaction was complete. The reaction solution was filtered through celite, the filtrate was concentrated, and the residue was purified by silica gel column chromatography to obtain 133 g of intermediate M2-3, with a yield of 89%, a purity of 98%, and a molecular weight of 214.0.

[0077] 4) Preparation of intermediate M2-4: Refer to the preparation of M1-3, except that M1-2 was replaced by 0.6 mol of M2-3 to obtain 127 g of intermediate M2-4 with a yield of 89%, a purity of 98%, and a molecular weight of 230.0.

[0078] 5) Preparation of intermediate M2-5: Refer to the preparation of M1-4, except that M1-3 was replaced by 0.6 mol of M2-4 to obtain 165 g of intermediate M2-5 with a yield of 69%, a purity of 98%, and a molecular weight of 435.1.

[0079] 6) Preparation of intermediate M2-6: Under argon, 0.35 mol of M2-5, 0.42 mol of pinacol diboronate, 0.018 mol of catalyst Pd(dba)2, 0.035 mol of ligand Pcy3, 0.7 mol of KOAc, and 2.0 L of 1,4-dioxane were mixed and refluxed at 110°C for 15 h. The mixture was cooled to room temperature and basified with 1 L of 2.0 mol / L aqueous sodium hydroxide solution. The mixed solution was extracted with 6 L of dichloromethane (3 times, 2 L each time). The organic phases were combined, dried over anhydrous magnesium sulfate, filtered, and concentrated. The residue was purified by silica gel column chromatography to obtain 129 g of intermediate M2-6 with a yield of 69%, a purity of 98%, and a molecular weight of 340.1.

[0080] 7) Preparation of intermediate M2 from intermediate M2-6: Refer to the preparation of M1-5, except that M1-4 was replaced with 0.1 mol of M2-6. Intermediate M2 was obtained, 29 g, with an 89% yield, 99% purity, and a molecular weight of 322.2.

[0081] It should also be noted that the intermediate M3 used in the present invention is synthesized by the following steps, and its reaction route is shown in Reaction Scheme 3:

[0082] ;

[0083] Reaction formula 3.

[0084] 1) Preparation of intermediate M3-1: Refer to the preparation of M1-5, except that M1-4 is replaced by 1.0 mol of 2-bromo-1,10-phenanthroline to obtain 173 g of intermediate M3-1 with a yield of 88%, a purity of 98%, and a molecular weight of 197.1.

[0085] 2) Preparation of intermediate M3-2: Refer to the preparation of M1-3, except that M1-2 was replaced by 0.85 mol of M3-1 to obtain 161 g of intermediate M3-2 with a yield of 89%, a purity of 98%, and a molecular weight of 213.1.

[0086] 3) Preparation of intermediate M3-3: Refer to the preparation of M1-4, except that M1-3 is replaced by 0.50 mol of M3-2 to obtain intermediate M3-3 with a molecular weight of 275.0.

[0087] 4) Preparation of intermediate M3 based on intermediate M3-3: Refer to the preparation of M1-5 to M1, except that M1-5 was replaced by 0.3 mol of M3-3 to obtain 66 g of intermediate M3, with a yield of 68%, a purity of 98%, and a molecular weight of 323.2.

[0088] The present invention uses compound r, L series intermediates and M series intermediates as raw materials to synthesize platinum-based tetradentate ligand derivatives. The synthesis is carried out according to the synthesis route shown in the above reaction formula 1, and the specific synthesis steps are as follows:

[0089] Step 1: Introduce the R group on the main framework of the right structure through Suzuki reaction:

[0090] Under argon, 0.2 mol of the M-series intermediate, 0.2 mol of compound r, 400 mL of THF, 100 mL of water, and 0.4 mol of K2CO3 were mixed, stirred, and heated to 40°C. After the solution became clear, 0.01 mmol of Pd(PPh3)4 was added. The temperature was raised to 80°C for 12 h and then cooled to room temperature. The reaction solution was extracted three times with 1.5 L of ethyl acetate. The organic phases were combined, dried, concentrated, and purified by silica gel column chromatography to obtain intermediate 1.

[0091] Step 2: Introduce the main structure on the left side through Williamson etherification reaction:

[0092] Under argon, 0.1 mol of intermediate 1, 0.1 mol of the L-series intermediate, 0.01 mol of CuI, 0.02 mol of picolinic acid, 0.3 mol of K₃PO₄, and 200 mL of DMSO were mixed and stirred at 90°C–100°C for 3 days before cooling to room temperature. After adding 500 mL of water and stirring, the reaction solution was extracted with 1.5 L of ethyl acetate three times. The combined organic phases were washed three times with distilled water, dried over anhydrous sodium sulfate, filtered, and concentrated. The residue was purified on a silica gel column to yield intermediate 2.

[0093] Step 3: Introduce Pt atoms through coordination reaction:

[0094] Using intermediate 2 as the ligand, 0.02 mmol of intermediate 2, 0.021 mmol of Pt(COD)Cl2, and 0.06 mmol of NaOAc were dispersed in 50 mL of acetonitrile. The mixture was immediately sealed after nitrogen aeration and heated to 120°C with stirring for 44 hours. After cooling to room temperature, the mixture was distilled under reduced pressure. The residue was purified on a silica gel column to obtain a platinum-based tetradentate ligand derivative. The solvent used for silica gel column purification was toluene / n-heptane in a volume ratio of 1:10 to 10:1.

[0095] In order to verify the above-mentioned synthetic route of the present invention, the present invention takes compound 1, compound 123 and compound 105 as examples, and summarizes the reaction conditions and the obtained products of the synthetic methods of compound 1, compound 123 and compound 105 as shown in Table 3 below.

[0096] Table 3 Reaction conditions and products obtained in Examples 1 to 3

[0097]

[0098] It should be noted that the final product in Table 3 is the product obtained in step 3, -6 Under the conditions of 100-250°C (170-180°C), the solid product was further purified by sublimation in a four-zone thermal gradient sublimator at 280°C, 275°C, 190°C and 150°C. It should also be noted that the synthetic routes of compound 1, compound 123 and compound 105 are shown in reaction formula 4, reaction formula 5 and reaction formula 6, respectively:

[0099] ;

[0100] Reaction formula 4.

[0101] ;

[0102] Reaction formula 5.

[0103] ;

[0104] Reaction formula 6.

[0105] In Example 1, since the coordination reaction between the intermediate 1-2 and Pt(COD)Cl2 and NaOAc in acetonitrile is difficult, it may be because the C atom between the two N atoms of the imidazole ring in the intermediate 1-2 is positively charged, and the coordinating metal Pt is also positively charged, making the coordination reaction impossible. Therefore, in Example 1, the intermediate 1-2 is first subjected to the following steps to convert it into the intermediate 1-3: 0.04 mol of the intermediate 1-2, 100 mL of toluene and 0.046 mol of CH3I are mixed and sealed, and the reaction is stirred at 100°C for 2 days and then cooled to room temperature. The solvent is removed by distillation under reduced pressure, and the residue is quickly purified by silica gel column to obtain 20 g of solid. The solid was added to a mixture of 60 mL of methanol and 40 mL of water, stirred until the solid was completely dissolved, and then 0.044 mol of NH4PF6 was added. The mixture was stirred at room temperature for 3 days, diluted with pure water, filtered, washed with pure water and ether, and the filter cake was dried to obtain intermediate compound 1-3, totaling 18 g, with a total yield of 72.%, a purity of 98%, and a molecular weight of 625.2.

[0106] Similar to Intermediate 1-2, since the coordination reaction between Intermediate 105-2 and Pt(COD)Cl2 and NaOAc in acetonitrile is also difficult, in Example 3, Intermediate 105-2 was first converted to Intermediate 105-3. The conversion steps were similar to those for converting Intermediate 1-2 to Intermediate 1-3, with the only difference being that Intermediate 1-2 was replaced with Intermediate 105-2. The intermediate compound 105-3 obtained in Example 3 was 21.8 g, with an overall yield of 74%, a purity of 98%, and a molecular weight of 737.3.

[0107] The present invention also synthesized other platinum-based tetradentate ligand derivatives according to reaction formula 1, and characterized them by mass spectrometry and elemental analysis, and the characterization results of mass spectrometry and elemental analysis are summarized as shown in Table 4.

[0108] Table 4 Mass spectrometry and elemental analysis characterization results of some platinum-based tetradentate ligand derivatives of the present invention

[0109]

[0110] Example 4

[0111] This embodiment provides an electroluminescent device. Figure 1 The electroluminescent device of this embodiment includes an anode layer 02 provided on a substrate 01, and a hole injection layer 03, a hole transport layer 04, a light-emitting layer 05, an electron transport layer 06, an electron injection layer 07 and a cathode layer 08 stacked in sequence from bottom to top on the anode layer 02.

[0112] In this embodiment, the platinum-based tetradentate ligand derivative is used in the light-emitting layer as a guest light-emitting material for electroluminescent device performance evaluation; or the platinum-based tetradentate ligand derivative is used in electron transport as an electron transport material for electroluminescent device performance evaluation.

[0113] After the preparation of the above-mentioned main functional layers for achieving organic light emitting diodes, the devices were packaged using the currently common packaging method in the industry. The test devices were prepared into 30mm×30mm samples, and the various luminescence performance indicators of these samples were tested. The present invention uses currently recognized industry-recognized preparation technology to prepare electroluminescent devices, which will be known to those skilled in the art and will not be described in detail here.

[0114] Example 5

[0115] This embodiment provides an electroluminescent device, which is manufactured by the following steps:

[0116] See also Figure 1 Using a clean conductive glass substrate as substrate 01, a 25nm thick indium tin oxide (ITO) was deposited on substrate 01 under high vacuum conditions as anode layer 02, a 20nm thick F4CNQ (F4CNQ) was deposited as hole injection layer 03, and a 90nm thick NPD (NPD) was deposited as hole transport layer 04. RH1-3 was used as the first host luminescent material, RH2-2 was used as the second host luminescent material, and compound 1 was used as the guest luminescent material in a mass ratio of RH1-3:RH2-2:compound 1 of 40:60:1. A 36nm thick luminescent layer 05 was formed on hole transport layer 04. On luminescent layer 05, a 30nm thick BCP was deposited as electron transport layer 06. Subsequently, a 16nm thick LiF layer was deposited using a vacuum evaporation apparatus as electron injection layer 07. By vacuum sputtering technology, a Mg-Al alloy layer with a thickness of 50 nm was formed on the electron injection layer 07 according to a molar ratio of Mg to Al of 1:9 as the cathode layer 08. After evaporation of the cover layer material, the layer was packaged to obtain an electroluminescent device.

[0117] That is, the electroluminescent device of this embodiment includes:

[0118] Substrate 01: conductive glass; and arranged on the conductive glass in sequence:

[0119] Anode layer 02: an indium tin oxide layer with a thickness of 25 nm.

[0120] Hole injection layer 03: F4CNQ with a thickness of 20 nm.

[0121] Hole transport layer 04: NPD with a thickness of 90 nm.

[0122] Light-emitting layer 05: A 36 nm thick composite layer formed by co-evaporation of RH1-3:RH2-2:Compound 1 at a mass ratio of 40:60:1. "RH1-3:RH2-2:Compound 1" is referred to as "Main Light-emitting Compound 1".

[0123] Electron transport layer 06: BCP with a thickness of 30 nm.

[0124] Electron injection layer 07: LiF with a thickness of 16 nm.

[0125] Cathode layer 08: Mg-Al alloy layer with a thickness of 50 nm.

[0126] The only difference between Example 6 to Example 14 and Example 5 is that:

[0127] The guest light-emitting material compound 1 in the light-emitting layer was replaced with compound 7, compound 47, compound 65, compound 105, compound 123, compound 24, compound 58, compound 82 and compound 116 in sequence.

[0128] The only difference between Examples 15 to 18 and Example 5 is that:

[0129] The guest light-emitting material compound 1 in the light-emitting layer and the electron transport material BCP in the electron transport layer were replaced with compound 38, compound 59, compound 96 and compound 113 in sequence.

[0130] The only difference between Examples 19 to 56 and Comparative Example 1 is that the guest luminescent material Ir(ppy)3 in the luminescent layer is replaced with Compound 2, Compound 5, Compound 6, Compound 13, Compound 14, Compound 16, Compound 19, Compound 20, Compound 21, Compound 22, Compound 23, Compound 25, Compound 26, Compound 27, Compound 28, Compound 29, Compound 30, Compound 31, Compound 32, Compound 33, Compound 34, Compound 35, Compound 36, Compound 37, Compound 39, Compound 40, Compound 41, Compound 42, Compound 248, Compound 239, Compound 240, Compound 247, Compound 243, Compound 242, Compound 180, Compound 181, Compound 202 and Compound 203, in sequence.

[0131] Comparative Example 1

[0132] The difference between this comparative example and Example 5 is only that:

[0133] In this comparative example, the guest luminescent material compound 1 in the luminescent layer is replaced by Ir(ppy)3.

[0134] Comparative Example 2

[0135] The difference between this comparative example and Example 5 is only that:

[0136] In this comparative example, the guest luminescent material Ir(ppy)3 in the luminescent layer is replaced by p-PF-ph.

[0137] The present invention tests the electroluminescent devices prepared in Examples 5 to 18 and Comparative Examples 1 to 2, and the test data are shown in Table 5.

[0138] Table 5 Performance data of the electroluminescent devices of Examples 5 to 18 and Comparative Examples 1 to 2

[0139]

[0140] Table 6 Performance data of the electroluminescent devices of Examples 19 to 56

[0141]

[0142] In Tables 5 and 6, the light-emitting layer is preceded by a "-" and represents the host light-emitting material, i.e., the host light-emitting material formed by RH1-3 and RH2-2, and the light-emitting material after a "-" represents the guest light-emitting material used in each embodiment or comparative example. EQE refers to the external quantum efficiency of the electroluminescent device, FWHM is the half-maximum width of the emission spectrum, which refers to the width at half the peak intensity of the spectrum and is used to describe the purity of the corresponding color of the spectrum; T95 refers to the current density at 20 mA / cm 2 The decay time of the device brightness from the initial brightness to 95% brightness under certain conditions.

[0143] The test results in Tables 5 and 6 show that the electroluminescent devices of Comparative Examples 1 and 2 both emitted green light. Furthermore, compared to the electroluminescent devices of Comparative Examples 1 and 2, the electroluminescent devices prepared using the compounds of Examples 5 to 56 as guest luminescent materials exhibited significantly lower driving voltages, narrower half-peak widths, and approximately two-fold longer lifetimes. Furthermore, the wavelength shifted toward shorter wavelengths, demonstrating the overall high efficiency of electroluminescent devices prepared using the platinum-based tetradentate ligand derivatives of the present invention. Compared to the electroluminescent devices prepared in Examples 6 to 14, the emission spectra of the electroluminescent devices of Examples 15 to 18 were significantly blue-shifted. This may be because the substituents on the right side of the corresponding compounds in Examples 15 to 18 all contain electron-withdrawing groups such as pyridazine groups, while the R groups contained in the compounds r used in Examples 6 to 14 all contain flexible alkyl chains, resulting in the substituents on the right side of the platinum-based tetradentate ligand derivatives obtained in Examples 6 to 14 all containing flexible alkyl chains. This indicates that the electron-withdrawing substituents reduce the electron cloud density around the competing ligand, the metal Pt element, and contribute to the stabilization of the highest occupied molecular orbital level of the compound, thereby blue-shifting the emission wavelength of the device. Compounds 38, 59, 96, and 113 can be used as both guest luminescent materials and electron transport materials, which helps to streamline the device structure and save costs.

[0144] In summary, compared to Comparative Examples 1 and 2, the use of the platinum-based tetradentate ligand derivative of the present invention as the guest luminescent material in the light-emitting layer of an electroluminescent device can produce an electroluminescent device with a lower starting voltage, improved luminous efficiency, and longer device life, demonstrating the application value of the metal platinum complex of the present invention. Furthermore, the color coordinates of the electroluminescent device prepared in this manner fall within the green to blue range, laying a foundation for future research on blue-emitting materials for OLEDs.

[0145] Obviously, the above embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

Claims

1. A platinum-based tetradentate ligand derivative, characterized in that: The structural formula of the platinum-based tetradentate ligand derivative is shown in general formula I: ； In the general formula I, A is bonded to the main structure to form a ring; the ring formed by A and the main structure is any one of Y1 to Y13: ； In Y1~Y13, * represents the position where the ring formed by A and the main structure is bonded to the Pt atom in the general formula I. Indicates the position where the ring formed by A and the main structure is bonded to the benzene ring in the general formula I; The main structure is shown in general formula II; Z1 is a C atom or a N atom; R is substituted or unsubstituted C6~C 30 Aryl, C3~C 12 Alkyl, substituted or unsubstituted C4~C 30 One of the heteroaryl groups; C4~C 30 The heteroatom in the heteroaryl group is selected from at least one of N, O and S; and C4~C 30 The heteroaryl group is a monocyclic heteroaryl group, a polycyclic heteroaryl group or a condensed ring heteroaryl group; the substituent is selected from D atoms, cyano groups, C1~C 12 Any one of an alkyl group, a C1~C6 halogenated alkyl group, and a phenyl group; B is a phenyl group, and B is cyclically bonded to the main structure to form a ring.

2. The platinum-based tetradentate ligand derivative according to claim 1, characterized in that: When Z1 is a nitrogen atom, the ring formed by bonding A to the main structure is Y1 or Y2.

3. A method for preparing the platinum-based tetradentate ligand derivative according to claim 1 or 2, characterized in that: The process comprises the following steps, and the synthesis route is shown in the general reaction formula 1: ； Reaction formula 1; Using the M series intermediate as the raw material for the main structural framework on the right side and compound r as the raw material for the R group, the R group is introduced into the main structural framework on the right side through the Suzuki coupling reaction to obtain intermediate 1; Using the L series intermediate as the raw material for the main framework of the left structure, the L series intermediate is coupled with intermediate 1 through Williamson ether synthesis reaction to obtain intermediate 2; Using intermediate 2 as a ligand, a coordination reaction is carried out to coordinate Pt with the middle position of intermediate 2 in a tetradentate chelate manner to obtain a platinum-based tetradentate ligand derivative; Among them, the M series intermediate is selected from any one of M1~M3: ； L series intermediates are selected from any one of L1 to L13: ； Compound r is a compound containing an R group.

4. An electroluminescent device, characterized in that It includes an anode layer, and an organic layer and a cathode layer stacked in sequence from bottom to top on the anode layer; The organic layer includes a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer and an electron injection layer stacked in sequence from bottom to top on the anode layer; Wherein, the light-emitting layer comprises the platinum-based tetradentate ligand derivative according to claim 1 or 2.

5. The electroluminescent device according to claim 4, wherein The light-emitting layer is formed of a host light-emitting material and a guest light-emitting material; The guest luminescent material is the platinum-based tetradentate ligand derivative, and the mass of the guest luminescent material accounts for 0.5% to 3% of the total mass of the luminescent layer.

6. The electroluminescent device according to claim 5, wherein The host luminescent material includes a first host material and a second host material; the first host material accounts for 40% to 60% of the mass of the host luminescent material, and the rest is the second host material, totaling 100%; Wherein, the first host material is any one of compounds RH1-1 to RH1-4: ； The second host material is any one of compounds RH2-1 to RH2-4: 。 7. The electroluminescent device according to claim 4, wherein The electron transport layer material is the platinum-based tetradentate ligand derivative.

8. The electroluminescent device according to claim 4, wherein The electroluminescent device is used in the fields of luminous illumination, image display or photoelectric signal transmission.

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