A class of binuclear ring metal platinum complexes based on aromatic heterocycle and indole-aryl cyano isoquinoline and application thereof

Abstract

The application discloses a kind of binuclear ring metal platinum complexes based on aromatic heterocycle and indole-aryl cyanide isoquinoline and near-infrared electroluminescent device thereof.This kind of binuclear ring metal platinum complexes is with aromatic heterocycle and indole as main ligand, aryl cyanide isoquinoline as auxiliary ligand.This kind of binuclear ring metal platinum complexes is prepared into organic electroluminescent device with light-emitting layer dopant, so that the maximum emission peak of device is located in the near-infrared region of about 840 nm, so that the spectral range of organic near-infrared electroluminescent device completely covers the near-infrared region, and luminescent performance has obvious improvement.

Description

Technical Field

[0001] This invention relates to a class of platinum complexes of binuclear cyclic metals with aromatic heterocyclic indole as the main ligand and arylcyanoisoquinoline as the auxiliary ligand, their preparation methods, and their applications in organic near-infrared electroluminescent devices, belonging to the field of organic electroluminescent materials and devices. Background Technology

[0002] Near-infrared (NIR) light is an electromagnetic wave with an emission range from 700 nm to 2500 nm. [1] It is invisible to the naked eye, has low interference, and strong penetrability, thus possessing significant research value in areas such as bioimaging, photodynamic therapy, in vivo detection, fiber optic communication, near-infrared emitting devices, and nighttime displays. [2-7] In recent years, near-infrared luminescent materials and their devices have attracted increasing attention from researchers. Early research focused primarily on inorganic near-infrared luminescent materials, but now organic near-infrared luminescent materials are gaining widespread attention due to their diverse molecular structures, low cost, good processability, ease of control, simple fabrication processes, large-area flexible fabrication capabilities, and high resolution. [8-10] .

[0003] With continuous research by scientists, near-infrared luminescent materials based on mononuclear cyclic platinum(II) complexes have seen some development. It is worth noting that, except for porphyrin platinum(II) complexes which exhibit intrinsic emission, the emission of other high-efficiency mononuclear cyclic platinum(II) complex devices mainly originates from intermolecular excimer emission. Due to metallophilicity, mononuclear cyclic platinum(II) complexes have relatively close intermolecular distances, enabling the formation of excimers and the generation of MMLCT transitions. MMLCT transitions can shorten the luminescence lifetime of the complexes (…). t ), increase the radiative transition constant ( k r )and F PLQY This can improve the electroluminescence efficiency of the device. However, excimer emission also makes the device stability heavily dependent on OLED solid-state packaging technology, which poses challenges to device fabrication conditions and optimization. Therefore, how to design and construct solution-processable, high-efficiency, long-wavelength emitting cyclic platinum(II) complex near-infrared electroluminescent materials and devices has become a key problem that urgently needs to be solved in this field.

[0004] Appendix: Main References

[0005] [1] Zhang Y, Wang Y, Song J, et al. Near-infrared emitting materialsvia harvesting triplet excitons: molecular design, properties, andapplication in organic light emitting diodes[J]. Advanced Optical Materials,2018, 6(18):1800466-1800466.

[0006] [2] Zampetti A, Minotto A, Cacialli F. Near-infrared (NIR) organiclight‐emitting diodes (OLEDs): challenges and opportunities[J]. AdvancedFunctional Materials, 2019, 29(21):1807623.

[0007] [3] Chuang Y J, Zhen Z, Zhang F, et al. Photostimulable near-infraredpersistent luminescent nanoprobes for ultrasensitive and longitudinal deep-tissue bio-imaging[J]. Theranostics, 2014, 4(11):1112-1122.

[0008] [4] Bai Q L, Zhang C H, Song J J, et al. Metal-free phthalocyaninesingle crystal: solvothermal synthesis and near-infrared electroluminescence[J]. Chinese Chemical Letters 2016, 27(5): 764-768.

[0009] [5] Chernov K G, Redchuk T A, Omelina E S, et al. Near-infraredfluorescent proteins, biosensors, and optogenetic tools engineered fromphytochromes[J]. Chemical Reviews, 2017,117(9):6423-6446.

[0010] [6] Zhu Z, Zou Y, Hu W, et al. Near-infrared plasmonic 2D semimetalsfor applications in communication and biology[J]. Advanced FunctionalMaterials, 2016, 26(11): 1793-1802.

[0011] [7] Tan H, Fan C, Ma L, et al. Single-crystalline InGaAs nanowiresfor room temperature high-performance near-infrared photodetectors[J]. Nano-micro letters, 2016, 8(1): 29-35.

[0012] [8] Xiang H, Cheng J, Ma X, et al. Near-infrared phosphorescence:materials and applications[J]. Chemical Society Reviews, 2013, 42(14): 6128-6185.

[0013] [9] Templier F. Overview of OLED displays[J]. OLED microdisplays:technology and applications, 2014, 35-51.

[0014]

[10] Liu J, Chen CT, Chen C H. Introduction to organic light-emitting Diode (OLED)[J]. Handbook Of Digital Imaging, 2015, 1-49.. Summary of the Invention

[0015] This invention discloses a class of binuclear cyclic platinum metal complexes based on aromatic heterocyclic indole-arylcyanoisoquinoline, their preparation methods, and their applications in organic near-infrared electroluminescent devices. Due to the close intramolecular Pt-Pt distance, binuclear cyclic platinum (II) metal complexes can form intramolecular MMLCT transitions, thereby achieving efficient and stable intrinsic emission. This indicates that binuclear cyclic platinum (II) metal complex near-infrared electroluminescent materials have greater development potential. One objective of this invention is to construct binuclear cyclic platinum metal complexes using aromatic heterocyclic indole as the main ligand and arylcyanoisoquinoline as the auxiliary ligand. These materials possess near-infrared photoluminescence properties and can be used in solution-processed organic near-infrared electroluminescent devices. Another objective of this invention is to provide an application of the aromatic heterocyclic indole-arylcyanoisoquinoline-based binuclear cyclic platinum metal complex, using it as a light-emitting layer dopant material in the preparation of organic electroluminescent devices to achieve near-infrared light emission and improve the luminous efficiency of the devices.

[0016] To achieve the above objectives, the present invention provides a class of binuclear cyclic platinum metal complexes based on aromatic heterocyclic indole-arylcyanoisoquinoline, having the structure shown in Formula 1 below:

[0017] (Formula I)

[0018] In Formula I, X is either a carbon atom or a nitrogen atom; It is either benzene or naphthalene. In Formula I, the a-position bond of the aromatic ring is connected to the 2-position of the isoquinoline; the above-mentioned binuclear cyclic platinum metal complex is preferably one of the following compounds:

[0019]

[0020] This invention also provides an application of the aforementioned binary cyclic platinum complex of aromatic heterocyclic indole-arylcyanoisoquinoline in near-infrared organic electroluminescent materials, specifically using this complex to prepare organic near-infrared electroluminescent devices. In particular, the aforementioned binary cyclic platinum complex of aromatic heterocyclic indole-arylcyanoisoquinoline serves as a dopant for the emitting layer of the organic near-infrared electroluminescent device.

[0021] The preferred embodiment is an organic near-infrared electroluminescent device emitting layer prepared by combining the aforementioned heterocyclic indole-arylcyanoisoquinoline binuclear cyclic platinum complex with the host material.

[0022] In a preferred embodiment, the mass of the binuclear cyclic platinum complex of the aromatic heterocyclic indole-arylcyanoisoquinoline is 13.0% to 17.0% of the mass of the host material.

[0023] In a further preferred embodiment, the main material is a mixture of TCTA and PO-T2T (in this invention, TCTA is tris(4-carbazolyl-9-ylphenyl)amine; PO-T2T is 2,4,6-tris[3-(diphenylphosphino)phenyl]-1,3,5-triazole, and the mass ratio of the two is 5:5).

[0024] Compared with the prior art, the beneficial effects of this invention are as follows: a class of near-infrared electroluminescent materials of binuclear cyclic platinum metal complexes of aromatic heterocyclic indole-arylcyanoisoquinoline were synthesized for the first time, and the maximum emission wavelength is above 800 nm. Compared with the existing materials, the main advantages of this type of material are: (1) introducing cyano groups with strong electron-withdrawing properties into binuclear cyclic platinum metal (II) complexes, and combining them with aromatic heterocyclic indole-arylcyanoisoquinoline to extend the conjugation length of the ligands, to construct near-infrared electroluminescent materials of binuclear cyclic platinum metal (II) complexes with a maximum emission wavelength of above 800 nm. (2) binuclear cyclic platinum metal (II) complexes have non-planar geometric properties, which can effectively suppress the aggregation state quenching of molecules; at the same time, they also have unique intramolecular MMLCT emission. By regulating the structure of the main ligand and the intramolecular platinum-platinum interaction, a shorter emission lifetime (τ) and a higher radiative transition constant (k) can be obtained. r This improves the luminescence quantum efficiency (Ф). PLQY (3) The emission peak of the binuclear cyclic platinum(II) complex is intrinsic emission. Near-infrared light emission can be obtained by preparing doped devices, and the device preparation and optimization methods are simpler. Attached Figure Description

[0025] Figure 1 The complex (PhIqCN)2Pt2 obtained in Example 1 of this invention m Single crystal diagram of -CzI)2;

[0026] Figure 2 The complex (PhIqCN)2Pt2 obtained in Example 1 of this invention m UV-Vis absorption spectrum of -CzI)2 in dichloromethane (DCM) solution;

[0027] Figure 3The complex (PhIqCN)2Pt2 obtained in Example 1 of this invention m Photoluminescence spectrum of -CzI)2 in dichloromethane (DCM) solution;

[0028] Figure 4 The complex (PhIqCN)2Pt2 obtained in Example 1 of this invention m -CzI)2 Electroluminescent device structure diagram;

[0029] Figure 5 The complex (PhIqCN)2Pt2 obtained in Example 1 of this invention m Electroluminescence spectrum (EL) of CzI)2 doped device;

[0030] Figure 6 The complex (PhIqCN)2Pt2 obtained in Example 1 of this invention m External quantum efficiency curve of -CzI)2 doped device ( EQE );

[0031] Figure 7 The complex (PhIqCN)2Pt2 obtained in Example 1 of this invention m -CzI)2 doped device current density-voltage-irradiance ( JVR ). Detailed Implementation

[0032] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further clarifies the invention. Those skilled in the art should understand that the specific details described below are illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0033] In this invention, the preparation methods are conventional unless otherwise specified. All raw materials used are available from publicly available commercial sources unless otherwise specified. Example 1

[0034] A binuclear cyclic platinum complex of aromatic heterocyclic indole-arylcyanoisoquinoline (PhIqCN)2Pt2( m The synthetic route for the preparation of -CzI)2 is as follows (the raw materials 1-chloroisoquinoline-4-carboxynitrile, phenylboronic acid and 9H-pyrido[2,3-B]indole were purchased from Bide Pharmaceutical Technology Co., Ltd.):

[0035] .

[0036] Preparation of compound piq

[0037] 750 mg (3.98 mmol) of 1-chloro-4-cyanoisoquinoline, 1.21 g (9.95 mmol) of phenylboronic acid, 6 mL of 2 M potassium carbonate solution, 139 mg (0.012 mmol) of Pd(PPh3)4, 6.5 mL of anhydrous ethanol, and 25 mL of toluene were added to a 100 mL round-bottom flask. The mixture was stirred at 95 °C for 10 h under Ar protection. The heat source was removed, and the reaction mixture was allowed to cool to room temperature. The mixture was extracted with ethyl acetate (EA) (3 × 15 mL), washed with saturated brine (3 × 25 mL), and the organic layer was dried over anhydrous MgSO4 for 6 h. The mixture was filtered, and the filtrate was collected. The solvent was removed by vacuum distillation. The residue was separated by silica gel column chromatography using EA:petroleum ether (PE) = 1:25 (V / V) as the eluent to give 871 mg of a white solid (compound piq), with a yield of 95%. 1 H NMR (500 MHz, CDCl3), δ (ppm): 8.98 (s, 1H), 8.25 (dd, J = 17.4, 8.5 Hz, 2H), 7.93 (t, J = 7.7 Hz, 1H), 7.72 (d, J = 7.1 Hz, 3H), 7.58 (d, J = 4.6 Hz, 3H).

[0038] Complex (PhIqCN)2Pt2( m Preparation of -CzI)2

[0039] 280 mg (1.22 mmol) of compound piq, 506 mg (1.22 mmol) of potassium chloroplatinate, 30 mL of ethylene glycol monoethyl ether, and 10 mL of distilled water were added to a 100 mL round-bottom flask. The mixture was reacted at 120 °C for 24 h under Ar protection. The heat source was removed, and the mixture was cooled to room temperature. The reaction suspension was filtered under reduced pressure, and the resulting filter cake was washed successively with distilled water and n-hexane. The filter cake was then dried under vacuum to obtain 500 mg of a brownish-red solid (chlorinated bridged product). Then, 500 mg (0.54 mmol) of the chlorinated bridged product, 227 mg (1.35 mmol) of 9H-pyrido[2,3-B]indole, 224 mg (1.62 mmol) of anhydrous potassium carbonate, and 20 mL of 1,2-dichloroethane were added to a 100 mL single-necked flask, and the mixture was reacted at 80 °C for 24 h. Remove the heat source and cool to room temperature. Pour the reaction solution into 100 mL of distilled water, extract with DCM, wash with saturated brine, and dry the collected organic phase with anhydrous MgSO4. Filter, collect the filtrate, remove the solvent by vacuum distillation, and separate the residue by silica gel column chromatography (PE:EA = 2:1). V / V Using chloroform as the eluent, a dark green solid was obtained. The product was then recrystallized from chloroform:anhydrous methanol (10:1) to give 307 mg of dark green solid, with a yield of 51%. 1 H NMR (500 MHz, CDCl3), d (ppm): 8.52 (d, J = 6.9 Hz, 2H), 8.26-8.18 (m, 6H), 8.07 (d, J = 9.7 Hz, 2H), 7.94 (t, J = 11.7 Hz, 4H), 7.82 (t, J = 9.4 Hz, 2H), 7.50-7.44 (m, 4H), 7.22 (t, J = 9.3 Hz, 2H), 7.04 (d, J = 10.0Hz, 2H), 6.95 (d, J = 9.1 Hz, 2H), 6.80-8.73 (m, 4H), 6.34 (d, J = 9.2 Hz, 2H).

[0040] All the heterocyclic benzoindole-arylcyanoisoquinoline binuclear cyclic platinum complexes involved in this invention can be synthesized using a method similar to that shown in Example 1. The compound (NphIqCN)2Pt2 was synthesized using 1-chloroisoquinoline-4-carboxynitrile, naphthoic acid, and 9H-pyrido[2,3-B]indole as starting materials. m -CzI)2; The compound (PhIqCN)2Pt2 was synthesized using 1-chloroisoquinoline-4-carboxynitrile, phenylboronic acid, and 5H-pyrazino[2,3-b]indole as starting materials. m -PzI)2; The compound (NphIqCN)2Pt2 was synthesized using 1-chloroisoquinoline-4-carboxynitrile, naphthoic acid, and 5H-pyrazino[2,3-b]indole as starting materials. m -PzI)2. Example 2

[0041] This invention also provides characterization and photophysical property testing of the binuclear cyclic platinum metal complexes of aromatic heterocyclic indole-arylcyanoisoquinoline involved:

[0042] Nuclear magnetic resonance (NMR) spectra were recorded at 298 K in deuterated chloroform solution using tetramethylsilane as an internal standard on a Bruker DRX 500 spectrometer. Single-crystal X-ray diffraction experiments were performed using a Bruker D8 VENTURE diffractometer with a copper target (CuKα, λ=1.54178) at temperatures of 193.00 K or 173.00 K. UV-Vis absorption and photoluminescence spectra were measured using a Varian Cray 50 absorption spectrometer and a Perkin-Elmer LS50B emission spectrometer. Example 3

[0043] Complex (PhIqCN)2Pt2( m Single-crystal diffraction of -CzI)2

[0044] Single crystals were grown at room temperature using solvent diffusion. 5 mg of the compound was weighed and placed in a clean test tube. 2 mL of chloroform was added for dissolution. Using a 2 mL syringe, 1 mL of buffer solvent with a chloroform / anhydrous methanol volume ratio of 1:1, 1:2, 1:4, and 1:8 was slowly added dropwise along the test tube wall. Finally, the test tube was filled with n-hexane, sealed with plastic wrap, and placed in a quiet, light-protected environment. The complex (PhIqCN)₂Pt₂ was obtained using the test method described in Example 2. m Single-crystal diffraction pattern of -CzI)2 ( Figure 1 ) and data (Table 1, Table 2). Example 4

[0045] Complex (PhIqCN)2Pt2( m-CzI)2 UV-Vis absorption spectrum

[0046] The complex (PhIqCN)2Pt2( m -CzI)2 was dissolved in dichloromethane to prepare a 10 -5 Solution M was tested for its UV-Vis absorption spectrum. Figure 2 The complex (PhIqCN)2Pt2( m UV-Vis absorption spectrum of -CzI)₂ in dichloromethane (DCM) solution. Figure 2 It can be seen that the complex (PhIqCN)2Pt2( m The strong absorption peak of -CzI)2 below 350 nm is attributed to the spin-allowed in-ligand (IL) π-π* transition absorption; the intermediate absorption peak in the 350-460 nm range is mainly attributed to MLCT absorption, and to some extent LLCT absorption; the weak absorption peak in the range above 460 nm is attributed to the unique MMLCT absorption of binuclear cyclic platinum(II) complexes. Example 5

[0047] Complex PhIqCN)2Pt2( m Photoluminescence spectrum of -CzI)2

[0048] The complex PhIqCN)2Pt2( m -CzI)2 was dissolved in dichloromethane to prepare a 10 -5 Solution M was tested for its photoluminescence spectrum. Figure 3 For the complex PhIqCN)2Pt2( m Photoluminescence spectrum of PhIqCN)2 in dichloromethane (DCM) solution. Excitation wavelength at 640 nm. m -CzI)2 emission peak is located in the near-infrared region at 820 nm.

[0049] The present invention also provides an organic near-infrared electroluminescent device based on the above-mentioned binuclear cyclic platinum metal complex of aromatic heterocyclic indole-arylcyanoisoquinoline. Example 6

[0050] Based on the complex PhIqCN)2Pt2( mThe structure of the organic near-infrared electroluminescent device (OLED) of -CzI)2 is as follows: ITO / PEDOT:PSS (35 nm) / TCTA (30 nm) / TCTA:PO-T2T (5:5): X wt% Pt-1 (50 nm) / PO-T2T (45 nm) / LiF (0.5 nm) / Al (120 nm). Wherein, the hole injection layer is PEDOT:PSS; the hole transport layer is TCTA; the main material is a blend of hole transport material TCTA and electron transport material PO-T2T in a mass ratio (TCTA:PO-T2T=5:5); the light-emitting layer is the preferred PhIqCN)2Pt2 of this invention. m -CzI)2 material is mixed with the host material in a blend coating (X=13, 15 and 17, i.e. the dopant material is 13%~17% of the mass of the host material); the electron transport layer is PO-T2T, and the metal electrode is composed of aluminum and LiF. Figure 4 For the complex PhIqCN)2Pt2( m Structure diagram of organic near-infrared electroluminescent device (-CzI)2. Example 7

[0051] Based on the complex PhIqCN)2Pt2( m Performance testing of organic near-infrared electroluminescent devices (-CzI)2.

[0052] The electroluminescence spectrum and irradiance of the electroluminescent device were measured using a PR-735 spectral scanning spectrophotometer (PhotoResearch). The current-voltage characteristics were determined using a Kethiey 2400 semiconductor performance testing system. The electroluminescence efficiency was calculated by combining current density, luminance, and electroluminescence spectrum.

[0053] Based on the complex PhIqCN)2Pt2( m Electroluminescence (EL) spectra of CzI)2-doped devices are shown below. Figure 5 As shown, the device exhibits the largest emission peak at 842 nm, while the weak emission peak at 550 nm is the emission peak of the host material.

[0054] External quantum efficiency curve ( EQE )like Figure 6 As shown, current density-voltage-irradiance ( JVR (The curve is as follows) Figure 7 As shown, the startup voltage of the devices is 6.0-6.8 V. The maximum irradiance is 10479 mW / Sr / m² at a doping concentration of 13 wt%. 2 The maximum external quantum efficiency is 0.52%.

[0055] Complex PhIqCN)2Pt2( m Table 3 summarizes the luminescence performance data of -CzI)2 in electroluminescent devices.

[0056] Table 1 (CNpiq)2Pt2( m Structural parameters and crystal data of CZI-2 single crystal

[0057]

[0058] Table 2 (CNpiq)2Pt2( m Partial bond lengths and bond angles of CZI-2 single crystal

[0059]

[0060] Table 3 PhIqCN)2Pt2( m -CzI)2 Luminescent performance data in electroluminescent devices

[0061]

[0062] Although the invention has been described in conjunction with preferred embodiments, the invention is not limited to the above embodiments, and it should be understood that the appended claims summarize the scope of the invention. Guided by the inventive concept, those skilled in the art should recognize that any modifications made to the various embodiments of the invention will be covered by the spirit and scope of the claims.

[0063] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A class of binuclear cyclic platinum metal complexes based on aromatic heterocyclic benzoindole-arylcyanoisoquinoline, characterized in that: It has the following structure: 。 2. The application of a binuclear cyclic platinum metal complex of aromatic heterocyclic indole-arylcyanoisoquinoline as described in claim 1, characterized in that: The binuclear cyclic platinum complex of aromatic heterocyclic indole-arylcyanoisoquinoline is used as a dopant for the emitting layer of organic near-infrared electroluminescent devices.

3. The application of the binuclear cyclic platinum metal complex of aromatic heterocyclic indole-arylcyanoisoquinoline according to claim 2, characterized in that, The aforementioned binuclear cyclic platinum complex of aromatic heterocyclic indole-arylcyanoisoquinoline is used to dope the host material to prepare the emitting layer of an organic near-infrared electroluminescent device.

4. The application of the binuclear cyclic platinum metal complex of aromatic heterocyclic indole-arylcyanoisoquinoline according to claim 3, characterized in that, The doping amount of the aforementioned binuclear cyclic platinum metal complex of aromatic heterocyclic indole-arylcyanoisoquinoline is 13.0% to 17.0% of the mass of the host material.

5. The application of the binuclear cyclic platinum metal complex of aromatic heterocyclic indole-arylcyanoisoquinoline according to claim 3, characterized in that, The main material is a mixture of TCTA:PO-T2T in a mass ratio of 5:5.

Images