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

Abstract

The invention belongs to the technical field of organic luminescent materials and semiconductors, and discloses a platinum-based tetradentate ligand derivative, a preparation method thereof and an electroluminescent device. The structural formula of the platinum-based tetradentate ligand derivative is shown as a general formula I. The platinum-based tetradentate ligand derivative disclosed by the invention is applied to a luminescent layer of an OLED (Organic Light Emitting Diode) device as a guest luminescent material, and an electroluminescent device with lower starting voltage, better luminous efficiency and longer service life of the device and emitting light in a green-blue light range is obtained. Meanwhile, the platinum-based tetradentate ligand derivative disclosed by the invention can also be used as an electron transport material to be applied to an electron transport layer of an OLED (Organic Light Emitting Diode) device, and the device structure can be simplified. # imgabs0 #

Description

Technical Field

[0001] The invention relates to the field of organic luminescent materials and semiconductor technology, and in particular to a platinum-based tetradentate ligand derivative and 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 the core of the OLED field. Phosphorescent guest materials play a decisive role in the efficiency of phosphorescent electroluminescent devices. The performance of the device can be adjusted by designing different types of organic ligands. Currently, the heavy metal phosphorescent organic complex molecules that can meet commercial applications are basically cyclometallated iridium (III) complex molecules, but the price of metal iridium is high and the quantity is limited. The preparation process of platinum (II) complex phosphorescent materials has a high utilization rate of platinum elements, so platinum (II) complex phosphorescent materials have become an alternative material to iridium (III) complex phosphorescent materials.

[0004] Compared with bidentate ligand cyclometal platinum (II) complexes and tridentate ligand cyclometal platinum (II) complexes, the rigid molecular structure of tetradentate ligand cyclometal platinum (II) complexes can inhibit vibration coupling and reduce non-radiative transitions, thereby improving quantum efficiency. At the same time, tetradentate ligands have high chemical and thermal stability, making them ideal molecules for the development of new OLED phosphorescent materials. Conventional OLED devices require materials that emit red, green, and blue light to achieve full-color display.

[0005] However, compared with red and green luminescent materials, excellent blue light emitting materials are relatively scarce, especially high-efficiency blue phosphorescent material molecules with stable structure and suitable emission spectrum have greater commercial value. Therefore, designing and developing new phosphorescent blue light materials with long life and high luminescence efficiency has always been a long-term goal of the development of this 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 and its preparation method and electroluminescent device of the present invention are realized by the following technical scheme: The present invention provides a platinum-based tetradentate ligand derivative, and its structural formula is shown in general formula I.

[0008] .

[0009] 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 the general formula II. Z1 is a C atom or a N atom.

[0010] 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 heteroatom in the heteroaryl group contains 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.

[0011] 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 an H atom, R is bonded to the 2-position of the pyridine ring.

[0012] The "substituted C3~C 15 In the "heteroaryl" group, "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 alkyl, C1~C6 halogenated alkyl, and phenyl substitution.

[0013] The platinum-based tetradentate ligand derivative of the present invention can be regarded as a tetradentate ligand derivative having a tetradentate ligand ... With the right The structure of the left side and the structure of the right side are respectively referred to as the left structure and the right structure. Wherein, "#" indicates the position of the O bonding in the left structure and the right structure. It should be noted that the two Pt atoms shown in the above-mentioned left structure and the right structure are the same Pt ​​atom in the same complex. Just for the convenience of understanding, the same Pt ​​atom is shown in the two structures respectively.

[0014] Preferably, the ring formed by bonding A to the main structure is any one of the groups Y1 to Y13: .

[0015] 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 bonding to the main structure and the benzene ring in the general formula I bond.

[0016] Table 1 Structures of compounds r1 to r42

[0017] More preferably, when Z1 in the right structure is an N atom, the ring formed by the bonding of A and the main structure in the left structure is Y1 or Y2. It should also be noted that the above-mentioned left structure and right structure of the present invention are provided by L series intermediates and M series intermediates, respectively, 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~Y13, respectively, the L series intermediates shown by L1~L13 are selected to provide the corresponding left structure. When B in the right structure is a phenyl group, the M series intermediate shown by M1 is selected to provide the main structure of the corresponding right structure. When B in the right structure is an H atom and Z1 is a C atom, the M series intermediate shown by M2 is selected to provide the main structure of the corresponding right structure. When B in the right structure is an H atom and Z1 is a C atom, the M series intermediate shown by M2 is selected to provide the main structure of the corresponding right structure. When B in the right structure is an H atom and Z1 is an N atom, the M series intermediate shown by M3 is selected to provide the main structure of the corresponding right 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.

[0018] 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 general reaction formula 1: ; Reaction formula 1.

[0019] Step 1, using the M series intermediate as the raw material of the main structural framework on the right side, and compound r as the raw material of 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. The Suzuki coupling reaction is also called Suzuki reaction, which will be referred to as Suzuki reaction hereinafter.

[0020] Step 2, using the L series intermediate as the raw material of the main framework of the left structure, coupling the L series intermediate with the intermediate 1 through the Williamson ether synthesis reaction to obtain the intermediate 2. The Williamson ether synthesis reaction is also called the Williamson etherification reaction, which will be referred to as the Williamson etherification reaction hereinafter.

[0021] Step 3, using intermediate 2 as a ligand through a coordination reaction, Pt is coordinated with the middle position of intermediate 2 in a tetradentate chelation manner to obtain a platinum-based tetradentate ligand derivative: It should be noted that the M series intermediate is selected from any one of M1 to M3: .

[0022] L series intermediates are selected from any one of L1~L13: .

[0023] 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: .

[0024] The 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 on the anode layer from bottom to top. 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 on the anode layer from bottom to top. The light-emitting layer comprises the above-mentioned platinum-based tetradentate ligand derivative of the present invention.

[0025] 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 above-mentioned 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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, totaling 100%.

[0030] More preferably, the first host material is any one of compounds RH1-1 to RH1-4: .

[0031] Preferably, the second host material is any one of compounds RH2-1 to RH2-4: .

[0032] Preferably, the electron transport layer material is the above-mentioned platinum-based tetradentate ligand derivative of the present invention.

[0033] Preferably, a substrate can be used below the anode layer or above the cathode layer, and the substrate is made of glass or polymer material with excellent mechanical strength, thermal stability, water resistance and transparency. In addition, a display substrate can also be made with a thin film transistor array and a specific display image formed by a combination of the transistor array. Preferably, the material of the anode layer is one or more of indium tin oxide, indium zinc oxide, tin dioxide and zinc oxide.

[0034] Preferably, the cathode layer is made of a metal element or 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 one 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.

[0035] Preferably, the hole transport layer can be a single-layer hole transport layer, including a hole transport material mode containing only one compound, a single-layer hole transport layer having both hole injection function and hole transport effect, or a composite hole transport layer mode containing multiple compounds. The composite hole transport layer is mainly an organic combination of the hole injection layer, the hole transport layer and the electron blocking layer in the general arrangement mode in the art.

[0036] A fourth object of the present invention is to provide an electroluminescent device for use in the fields of luminous illumination, image display or optoelectronic signal transmission.

[0037] Compared with the prior art, the present invention has the following beneficial effects: The platinum-based tetradentate ligand derivative of the present invention is shown in general formula I, and its molecule has a spatial cross conformation, which is beneficial to improving the solubility of the material in an organic solvent. The final products are prepared by purification through silica gel column chromatography, which can effectively improve the poor solubility 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 derivative of the present invention is designed to inhibit the accumulation of luminescent molecules, thereby improving the external quantum efficiency of the device and inhibiting 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 derivative 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.

[0038] The platinum-based tetradentate ligand derivative of the present invention is applied to the light-emitting layer as a guest luminescent material, and the obtained device has a good improvement in both luminous efficiency and life, and is an organic light-emitting material with good performance. And it has been verified by experiments that the color coordinates of the OLED device prepared based on the platinum-based tetradentate ligand derivative of the present invention are in the range of green light to blue light, which lays a certain foundation for the later research of OLED blue light materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic structural diagram of the electroluminescent device of the present invention. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention are 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 main materials, second main materials and platinum-based tetradentate ligand derivatives involved in the following embodiments are shown in the content of the invention. The structures of other organic materials involved in the present invention are as follows:

[0041] The purity data involved in the following L series intermediates of the present invention are all measured by gas chromatography, and the molecular weight data are measured by gas chromatography-mass spectrometry; the purity data involved in the M series intermediates and the final compounds are all measured by high performance liquid chromatography, and the molecular weight data are measured by liquid chromatography-mass spectrometry. The above test methods belong to conventional technical means in the field, so they are not repeated here.

[0042] 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".

[0043] 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: ; Reaction formula 2.

[0044] 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.

[0045] 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 with 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 mole of Ag2CO3 from K2CO3, the solvent was replaced by an equal volume of acetonitrile from DMSO, and the reaction temperature was reduced to 65°C. The preparation conditions of the L series intermediates and their yields and yields are summarized in Table 2.

[0046] Table 2 Preparation conditions, yields and yields of L series intermediates

[0047] 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: ; Reaction formula 1.

[0048] 1) Preparation of intermediate M1-1: Under argon protection, 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 temperature was raised to 80°C and the reaction was continued for 11 h until the reaction was complete, then cooled to room temperature, the reaction solution was acidified with 2 L of 6 mol / L HCl aqueous solution to produce a solid, filtered, the filter cake was dissolved in 5 L of dichloromethane, extracted with pure water, post-treated, and quickly washed to obtain intermediate M1-1, 301 g, with a yield of 76%, a purity of 98%, and a molecular weight of 265.1.

[0049] 2) Preparation of intermediate M1-2: Under argon, 1.1 mol of M1-1 and 16.5 mol of phosphorus oxychloride were mixed and heated to 110°C. The reaction was continued for 15 hours, then cooled to room temperature. The reaction solution was alkalized with 3 L of 5.0 mol / L sodium hydroxide aqueous solution, and extracted with 6 L of dichloromethane for 3 times, 2 L each time. The organic phases were combined and post-treated to obtain intermediate M1-2, totaling 175 g, with a yield of 60%, a purity of 98%, and a molecular weight of 265.0.

[0050] 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, reacted at 80°C for 11 h, and then concentrated under reduced pressure to remove the solvent. 2 L of pure water was added to dilute the residue. A large amount of precipitate was generated. After filtering, it was rinsed with a large amount of water and dried in vacuum at 40°C to obtain intermediate M1-3, 163 g, with a yield of 88%, a purity of 98%, and a molecular weight of 281.0.

[0051] 4) Preparation of intermediate M1-4: Under argon, 0.55 mol of M1-3, 1.5L of dichloromethane and 0.28 mol of DMF were mixed, and 0.66 mol of tribromide phosphorus was slowly added at 0°C. After the addition was complete, the temperature was raised to room temperature and the reaction was continued for 10 hours until the reaction was complete. Then, saturated sodium carbonate solution was slowly added to adjust the pH of the solution to 7-8. The liquid was separated, the organic phase was retained, and the aqueous phase was extracted with 6L of dichloromethane for 3 times, 2L each time. The organic phases were combined and post-treated to obtain intermediate M1-4, 121 g, with a yield of 64%, a purity of 98%, and a molecular weight of 345.0.

[0052] 5) Preparation of intermediate M1-5: Under argon, 0.35 mol of M1-4, 4.0 mmol of CuI, 7.0 mmol of ligand 8-hydroxy-2-methylquinoline, 1.05 mol of tetrabutylammonium hydroxide pentahydrate, 500 mL of DMSO and 750 mL of water were mixed, refluxed at 130°C for 14 h, cooled to room temperature, extracted the reaction solution with 3 L of ethyl acetate 3 times, 1 L each time, and combined the organic phases. The solvent was concentrated and recrystallized from ethyl acetate-n-heptane to obtain intermediate M1-5, totaling 88 g, with a yield of 90%, a purity of 99%, and a molecular weight of 281.0.

[0053] 6) Preparation of intermediate M1 based on intermediate M1-5: Under argon protection, 0.3 mol of M1-5, 0.36 mol of diboric acid pinacol ester, 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, refluxed at 110°C for 15 h and then cooled to room temperature. After alkalization with 0.5 L of 2.0 mol / L sodium hydroxide aqueous solution, the mixed solution was extracted with 3 L of dichloromethane 3 times, 1 L each time. The organic phases were combined and 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.

[0054] 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 Formula 2: ; Reaction formula 2.

[0055] 1) Preparation of intermediate M2-1: Under argon protection, 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 temperature was raised to 90°C and the reaction was continued for 6 hours, then filtered while hot, and the filter cake was rinsed with a small amount of tetrahydrofuran. After concentrating the filtrate, 2 L of dichloromethane was added to dissolve it, and it 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.

[0056] 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.

[0057] 3) Preparation of intermediate M2-3: Under argon protection, 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 diatomaceous earth, 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.

[0058] 4) Preparation of intermediate M2-4: Refer to the preparation of M1-3, except that M1-2 is replaced by 0.6 mol of M2-3, and the intermediate M2-4 is 127 g, with a yield of 89%, a purity of 98%, and a molecular weight of 230.0.

[0059] 5) Preparation of intermediate M2-5: Refer to the preparation of M1-4, except that M1-3 is replaced by 0.6 mol of M2-4, and the intermediate M2-5 is 165 g, with a yield of 69%, a purity of 98%, and a molecular weight of 435.1.

[0060] 6) Preparation of intermediate M2-6: Under argon protection, 0.35 mol of M2-5, 0.42 mol of bipyralidone, 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, refluxed at 110 °C for 15 h, cooled to room temperature, alkalized with 1 L of 2.0 mol / L sodium hydroxide aqueous solution, and extracted with 6 L of dichloromethane for 3 times, 2 L each time. The organic phases were combined and 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.

[0061] 7) Preparation of intermediate M2 based on intermediate M2-6: Refer to the preparation of M1-5, except that M1-4 is replaced by 0.1 mol of M2-6. Intermediate M2 is obtained in an amount of 29 g, with a yield of 89%, a purity of 99%, and a molecular weight of 322.2.

[0062] 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: ; Reaction formula 3.

[0063] 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.

[0064] 2) Preparation of intermediate M3-2: Refer to the preparation of M1-3, except that M1-2 is replaced by 0.85 mol of M3-1, and the intermediate M3-2 is 161 g, with a yield of 89%, a purity of 98%, and a molecular weight of 213.1.

[0065] 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.

[0066] 4) Preparation of intermediate M3 based on intermediate M3-3: Refer to the preparation of M1-5 to M1, except that M1-5 is replaced by 0.3 mol of M3-3, and 66 g of intermediate M3 is obtained, with a yield of 68%, a purity of 98%, and a molecular weight of 323.2.

[0067] The present invention uses compound r, L series intermediates and M series intermediates as raw materials to synthesize a platinum-based tetradentate ligand derivative, and 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: Step 1, introduce the R group on the main framework of the right structure through Suzuki reaction: Under argon protection, 0.2 mol of 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 and stirred and heated to 40°C. After the solution was clarified, 0.01 mmol of Pd(PPh3)4 was added, the temperature was raised to 80°C for reaction for 12 h, and then cooled to room temperature. The reaction solution was extracted with 1.5 L of ethyl acetate three times, the organic phases were combined, dried, concentrated, and purified by silica gel column chromatography to obtain intermediate 1.

[0068] Step 2, introduce the main structure on the left side through Williamson etherification reaction: Under argon protection, 0.1 mol of intermediate 1, 0.1 mol of 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, stirred at 90°C~100°C for 3 days and then cooled 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 organic phases were combined and washed three times with distilled water, then dried with anhydrous sodium sulfate, filtered, concentrated, and the residue was purified by silica gel column to obtain intermediate 2.

[0069] Step 3, introducing Pt atoms through coordination reaction: Using intermediate 2 as a 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, filled with nitrogen and quickly sealed, then heated to 120°C and stirred for 44 hours, cooled to room temperature and distilled under reduced pressure, and the residue was purified by silica gel column to obtain a platinum-based tetradentate ligand derivative. The solvent used for silica gel column purification was toluene / n-heptane with a volume ratio of 1:10 to 10:1.

[0070] In order to verify the above-mentioned synthesis route of the present invention, the present invention takes compound 1, compound 123 and compound 105 as examples, and the reaction conditions of the synthesis methods of compound 1, compound 123 and compound 105 and the obtained products are summarized as shown in Table 3 below.

[0071] Table 3 Reaction conditions and products obtained in Examples 1 to 3

[0072] It should be noted that the final product in Table 3 above refers to the product obtained in step 3, -6 Torr, and then further sublimed in a four-zone thermal gradient sublimator at 280°C, 275°C, 190°C and 150°C for purification to obtain a solid product. 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: ; Reaction formula 4.

[0073] ; Reaction formula 5.

[0074] ; Reaction formula 6.

[0075] In Example 1, since it is difficult for intermediate 1-2 to carry out coordination reaction with Pt(COD)Cl2 and NaOAc in acetonitrile, it may be because the C atom between the two N atoms of the imidazole ring in intermediate 1-2 is positively charged, and the coordinating metal Pt is also positively charged, making the coordination reaction impossible. Therefore, in Example 1, intermediate 1-2 is first subjected to the following steps to convert it into intermediate 1-3: 0.04 mol of intermediate 1-2, 100 mL of toluene and 0.046 mol of CH3I are mixed and sealed, stirred at 100°C for 2 days, cooled to room temperature, and the solvent is removed by distillation under reduced pressure. 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.

[0076] As in the case of intermediate 1-2, since it is also difficult for intermediate 105-2 to coordinate with Pt(COD)Cl2 and NaOAc in acetonitrile, in Example 3, intermediate 105-2 is first converted into intermediate 105-3, and the conversion steps refer to the steps of converting intermediate 1-2 into intermediate 1-3, except that intermediate 1-2 is replaced by intermediate 105-2. The intermediate compound 105-3 obtained in Example 3 is 21.8 g, with a total yield of 74%, a purity of 98%, and a molecular weight of 737.3.

[0077] 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.

[0078] Table 4 Mass spectrometry and elemental analysis characterization results of some platinum-based tetradentate ligand derivatives of the present invention

[0079] Example 4 This embodiment provides an electroluminescent device. Figure 1 The electroluminescent device of this embodiment includes an anode layer 02 arranged 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.

[0080] In this embodiment, the platinum-based tetradentate ligand derivative is used in the light-emitting layer as a guest light-emitting material for evaluating the performance of the electroluminescent device; or the platinum-based tetradentate ligand derivative is used in electron transport as an electron transport material for evaluating the performance of the electroluminescent device.

[0081] After the preparation of the above-mentioned main functional layers for realizing organic light emission is completed, the device is packaged using the currently common packaging device method in the industry, and the test device is prepared into a 30mm×30mm sample, and then the various luminescence performance indicators of the above-mentioned sample are tested and detected. The present invention adopts the currently recognized preparation process technology in the industry to prepare the electroluminescent device, which should be known to those skilled in the art, so the present invention will not be repeated here.

[0082] Example 5 This embodiment provides an electroluminescent device, and the electroluminescent device is prepared by the following steps: See also Figure 1 , using clean conductive glass as substrate 01, under high vacuum conditions, 25nm thick indium tin oxide as anode layer 02, 20nm thick F4CNQ as hole injection layer 03, and 90nm thick NPD as hole transport layer 04 were sequentially deposited on substrate 01. RH1-3 was used as the first main luminescent material, RH2-2 was used as the second main luminescent material, and compound 1 was used as the guest luminescent material. The mass ratio of RH1-3:RH2-2:compound 1 was 40:60:1 for co-evaporation, and a 36nm thick luminescent layer 05 was formed on the hole transport layer 04. On the luminescent layer 05, 30nm thick BCP was evaporated as electron transport layer 06. Subsequently, a 16nm thick LiF layer was evaporated by a vacuum evaporation device as electron injection layer 07. By vacuum sputtering technology, a Mg-Al alloy layer with a thickness of 50 nm is formed on the electron injection layer 07 according to a molar ratio of Mg to Al of 1:9 as the cathode layer 08, and the cover layer material is evaporated and packaged to obtain an electroluminescent device.

[0083] That is, the electroluminescent device of this embodiment includes: Substrate 01: conductive glass; and the following components arranged on the conductive glass: Anode layer 02: Indium tin oxide layer with a thickness of 25 nm.

[0084] Hole injection layer 03: F4CNQ with a thickness of 20 nm.

[0085] Hole transport layer 04: NPD with a thickness of 90 nm.

[0086] Light-emitting layer 05: a composite layer with a thickness of 36 nm 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".

[0087] Electron transport layer 06: BCP with a thickness of 30 nm.

[0088] Electron injection layer 07: LiF with a thickness of 16 nm.

[0089] Cathode layer 08: Mg-Al alloy layer with a thickness of 50 nm.

[0090] The difference between Example 6 to Example 14 and Example 5 is only that: 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.

[0091] The difference between Example 15 to Example 18 and Example 5 is only that: 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.

[0092] 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, respectively.

[0093] Comparative Example 1 The difference between this comparative example and Example 5 is only that: In this comparative example, the guest luminescent material compound 1 in the luminescent layer is replaced by Ir(ppy)3.

[0094] Comparative Example 2 The difference between this comparative example and Example 5 is only that: In this comparative example, the guest luminescent material Ir(ppy)3 in the luminescent layer is replaced by p-PF-ph.

[0095] 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.

[0096] Table 5 Performance data of the electroluminescent devices of Examples 5 to 18 and Comparative Examples 1 to 2

[0097] Table 6 Performance data of the electroluminescent devices of Examples 19 to 56

[0098] In Table 5 and Table 6, in the light-emitting layer, the material before “-” indicates the main light-emitting material, i.e., the main light-emitting material formed by RH1-3 and RH2-2, and the material after “-” indicates 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 color corresponding to 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.

[0099] It can be seen from the test results in Tables 5 and 6 that the electroluminescent devices of Comparative Examples 1 and 2 both emit green light. Compared with the electroluminescent devices of Comparative Examples 1 and 2, the driving voltage of the electroluminescent devices prepared using the compounds of Examples 5 to 56 as the guest luminescent materials is significantly reduced, the half-peak width is significantly narrowed, the life is extended by about 2 times, and the wavelength moves toward the short-wave direction, which indicates that the overall efficiency of the electroluminescent device prepared using the platinum-based tetradentate ligand derivative of the present invention is high. Compared with the electroluminescent devices prepared in Examples 6 to 14, the emission spectra of the electroluminescent devices in Examples 15 to 18 are obviously blue-shifted. It is possible that the substituents of the right-side structures of the corresponding compounds in Examples 15 to 18 all contain electron-withdrawing groups such as pyridazine groups, and the R groups contained in the compounds r used in Examples 6 to 14 all contain flexible alkyl chains, so that the substituents of the right-side structures of the platinum-based tetradentate ligand derivatives obtained in Examples 6 to 14 all contain flexible alkyl chains, which indicates that the electron-withdrawing substituents reduce the electron cloud density around the competing ligand and the metal Pt element, which helps to stabilize 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 guest luminescent materials or electron transport materials, which helps to simplify the device structure and save costs.

[0100] In summary, compared with Comparative Examples 1 and 2, the platinum-based tetradentate ligand derivative of the present invention is used as the guest luminescent material in the luminescent layer in the electroluminescent device, and an electroluminescent device with lower starting voltage, better luminous efficiency and device life can be obtained, indicating that the metal platinum complex of the present invention has certain application value. And the color coordinates of the electroluminescent device prepared by the present invention are in the range of green light to blue light, which lays a certain foundation for the later research of OLED blue light materials.

[0101] Obviously, the above embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without 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 a substituted or unsubstituted C3~C 15 A heteroaryl group, wherein the heteroatom contains at least one of N, O and S; A is bonded to the main structure to form a ring; the main structure is shown in the 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 contains 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; B is a phenyl group or an H atom; when B is a phenyl group, B is cyclically bonded to the main structure to form a ring, and R is bonded to the 4-position of the pyridine ring; when B is an H atom, R is bonded to the 2-position of the pyridine ring.

2. The platinum-based tetradentate ligand derivative according to claim 1, characterized in that: The ring formed by bonding A to 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, It indicates the position where the ring formed by A bonding to the main structure and the benzene ring in the general formula I bond.

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

4. The platinum-based tetradentate ligand derivative according to claim 1, characterized in that: Replaced C3~C 15 In heteroaryl, the substituent is D atom, cyano group, C1~C 12 Any one of alkyl, C1~C6 alkyl, and phenyl substitution; Substituted C6~C 30 In the aromatic group, the substituent is a D atom, a cyano group, a C1~C 12 Any one of alkyl, C1~C6 alkyl, and phenyl substitution; Substituted C4~C 30 In heteroaryl, the substituent is D atom, cyano group, C1~C 12 Any one of alkyl, C1~C6 halogenated alkyl, and phenyl substitution.

5. A method for preparing the platinum-based tetradentate ligand derivative according to any one of claims 1 to 4, characterized in that: The method comprises the following steps, and its synthesis route is shown in reaction formula 1: ； Reaction formula 1; Using the M series intermediate as the raw material of the main structural framework on the right side, and compound r as the raw material of 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 of 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 through a coordination reaction, Pt is coordinated with the middle position of intermediate 2 in a tetradentate chelation 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~L13: ； Compound r is a compound containing an R group.

6. An electroluminescent device, characterized in that: It comprises an anode layer, and an organic layer and a cathode layer which are sequentially stacked 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 which are sequentially stacked from bottom to top on the anode layer; Wherein, the light-emitting layer comprises the platinum-based tetradentate ligand derivative according to any one of claims 1 to 3.

7. The electroluminescent device according to claim 6, characterized in that The light-emitting layer is formed by 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.

8. The electroluminescent device according to claim 7, characterized in that 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: 。 9. The electroluminescent device according to claim 6, characterized in that The electron transport layer material is the platinum-based tetradentate ligand derivative.

10. The electroluminescent device according to claim 6, characterized in that The electroluminescent device is used in the fields of luminous illumination, image display or photoelectric signal transmission.

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