A kind of five-core copper (I) complex of core-shell structure and its preparation method and application

Abstract

The present application relates to a kind of core-shell structure five-core copper (I) complex and its preparation method and application, the molecular formula of the core-shell structure five-core copper (I) complex is [C 112 H 82 Cu5S4N 22 P4]PF6, molecular weight is 2469.78, its preparation method includes: pyridine and imidazole bisphosphine ligand L and auxiliary ligand 1-phenyl-1H-tetrazole-5-thiol are added to the mixed solvent of CH2Cl2 And CH3OH, stirring is uniformly obtained mixed solution;[Cu (CH3CN) 4]PF6 is added to mixed solution, filter after stirring at room temperature to culture bottle, the filtrate is slowly volatilized in culture bottle at room temperature, obtain transparent light yellow crystal;The obtained crystal is washed with anhydrous ethanol and vacuum dried, and the core-shell structure five-core copper (I) complex is obtained.The preparation method of the present application has mild conditions, and the preparation process is simple, and the operation is simple, and it can be prepared at room temperature.The obtained core-shell structure five-core copper (I) complex has excellent luminescent performance, and is an excellent orange phosphor material.

Description

Technical Field

[0001] This invention belongs to the field of electroluminescent materials and their preparation technology, specifically a core-shell structured pentanuclear copper (I) complex, its preparation method, and its application. Background Technology

[0002] With social development and continuous advancements in science and technology, various luminescent materials with excellent structures and performance have been invented. Substances capable of absorbing energy and converting it into light radiation in a certain way are called luminescent materials. According to the mode of emission, they can be classified into photoluminescence, electroluminescence, and radiative emission. Photoluminescence refers to the phenomenon where an object, when irradiated by an external light source, gains energy, becomes excited, and ultimately emits light. Electroluminescence refers to the phenomenon where luminescent materials emit light when excited by current and an electric field. Materials with these properties can be made into electrically controlled light-emitting devices, such as light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs). Due to its numerous advantages, including energy saving, thinness, no glare, no ultraviolet radiation, no infrared radiation, low driving voltage, short response time, good low-temperature characteristics, high luminous efficiency, simple manufacturing process, good all-solid-state shock resistance, almost no viewing angle issues, ability to be manufactured on substrates of different materials, and the ability to be made into flexible products, OLEDs have attracted much attention from the scientific and industrial communities in recent years.

[0003] Most OLED materials require transition metals such as Ir(III), Pt(II), and Ru(II) as raw materials for guest materials. Although transition metal complexes have shown good performance in OLEDs, these metals are expensive and cause significant environmental pollution, which hinders the industrialization and commercialization of OLEDs. Therefore, a pressing issue in the field of OLED materials is to find a class of high-performance, cost-effective, and environmentally friendly metal-organic materials with excellent photophysical properties, low material cost, and environmental friendliness, thereby obtaining high-performance and inexpensive OLEDs.

[0004] Among numerous OLED luminescent materials, monovalent copper coordination compounds are considered a good alternative to precious metals, possessing advantages such as abundant resources, low cost, and low pollution. Furthermore, monovalent copper coordination compounds exhibit good stability, diverse coordination modes, and easily tunable emission color. Therefore, research on monovalent copper coordination compounds is of great significance in developing novel, inexpensive, and high-performance luminescent materials. Summary of the Invention

[0005] This invention provides a core-shell structured pentanuclear copper (I) complex, its preparation method, and its application. The aim is to prepare a pentanuclear copper (I) complex with excellent luminescence performance under simple and mild methods at room temperature, simplifying the operation process, reducing production costs, and eliminating the need for expensive equipment. The obtained core-shell structured pentanuclear copper (I) complex is an excellent orange phosphorescent material that can be used in the field of high-efficiency OLEDs.

[0006] One objective of this invention is to provide a core-shell-like pentanuclear copper(I) complex with the molecular formula [C 112 H 82 Cu5S4N 22 P4]PF6, with a molecular weight of 2469.78, has the structural formula shown in Formula I:

[0007]

[0008] Its structural unit belongs to the monoclinic crystal system, with space group P2 / n and cell parameters as follows: α = 90°, β = 100.121(2)°, γ = 90°; its unit cell volume is

[0009] Furthermore, the core-shell-like pentanuclear copper(I) complex exhibits an optimal excitation wavelength of 403 nm and an optimal emission wavelength of 605 nm at 298 K, displaying orange luminescence with a photoluminescence quantum yield of 51.2% and a luminescence lifetime of 3.81 μs.

[0010] Furthermore, the core-shell-like pentanuclear copper(I) complex exhibits a maximum emission wavelength of 570 nm and a luminescence lifetime of 76.66 μs at 77 K, making it an orange phosphorescent material.

[0011] The present invention also aims to provide a method for preparing a core-shell-like pentanuclear copper(I) complex, which specifically includes the following steps:

[0012] (1) Add ligand L and auxiliary ligand 1-phenyl-1H-tetrazole-5-thiol to a mixed solvent of CH2Cl2 and CH3OH, stir until homogeneous, and obtain a mixed solution;

[0013] (2) Add [Cu(CH3CN)4]PF6 to the above mixed solution, stir at room temperature for 10 min, and then filter into a single crystal culture flask. The filtrate slowly evaporates in the culture flask at room temperature to obtain transparent pale yellow crystals.

[0014] (3) Collect the crystals obtained in step (2), wash the crystals with anhydrous ethanol and dry them in a vacuum drying oven at 45°C to obtain the target product - a pentanuclear copper (I) complex with a core-shell structure;

[0015] The structural formula of ligand L in step (1) is shown in formula II:

[0016]

[0017] The molecular formula of the product, a core-shell structured pentanuclear copper (I) complex, is C1. 112 H 82 Cu5S4N 22 P4·PF6, with a molecular weight of 2469.78, belongs to the monoclinic crystal system, has a space group of P2 / n, and its unit cell parameters are: α = 90°, β = 100.121(2)°, γ = 90°; its unit cell volume is

[0018] Furthermore, in step (1), the molar ratio of ligand L to auxiliary ligand 1-phenyl-1H-tetrazole-5-thiol is 1:2.

[0019] Furthermore, the molar ratio of [Cu(CH3CN)4]PF6 to ligand L is 2.5:1.

[0020] Furthermore, the volume ratio of CH2Cl2 to CH3OH in the mixed solvent of CH2Cl2 and CH3OH is 4:1.

[0021] Furthermore, with reference to ligand L, the molar yield of the core-shell-like pentanuclear copper (I) complex was 61%.

[0022] Furthermore, the prepared core-shell-like pentanuclear copper(I) complex exhibits an optimal excitation wavelength of 403 nm and an optimal emission wavelength of 605 nm at 298 K, displaying orange luminescence with a photoluminescence quantum yield of 51.2% and a luminescence lifetime of 3.81 μs. At 77 K, its maximum emission wavelength is 570 nm and its luminescence lifetime is 76.66 μs, making it an orange phosphorescent material.

[0023] Another object of the present invention is to provide the application of the above-mentioned core-shell pentanuclear copper (I) complex in the field of high-efficiency light-emitting OLEDs. The core-shell pentanuclear copper (I) complex is an orange phosphorescent material with high-efficiency photoluminescence properties.

[0024] The present invention has the following beneficial effects:

[0025] (1) The core-shell-like pentanuclear copper (I) complex prepared in this invention exhibits a strong absorption peak at around 230 nm; a moderate absorption peak at 295-315 nm; and a weak absorption not present in ligand L in the 350-460 nm range, which may originate from metal-to-ligand charge transfer (MLCT) transitions. The solid-state UV-Vis absorption spectrum of the core-shell-like pentanuclear copper (I) complex shows a broad and strong absorption peak at 395 nm, indicating that the complex has intermolecular interactions.

[0026] (2) The core-shell structured pentanuclear copper(I) complex [C] prepared in this invention 112 H 82 Cu5S4N 22 P4]PF6 (For ease of description, C) 112 H 82 Cu5S4N 22 The P4 group (denoted as R) includes cationic complexes [R]. +1 And anionic complex [PF6] -1 The molecular formula of the complex [R]PF6 is [C 112 H 82 Cu5S4N 22 P4]PF6, Cu5S4 is located at the center of the crystal structure, making it a cationic complex [R] +1 Forming a core-shell-like structure. The cationic complex R includes 5 copper (I) centers ( Figure 1 In this structure, each of the four outer copper (I) groups coordinates with one p atom of the pyridine-imidazolium bisphosphine ligand L, one nitrogen atom of the three deprotonated 1-phenyl-1H-tetrazole-5-thiol, and two sulfur atoms, forming a deformed tetrahedral coordination structure. See details... Figure 1 and [C 112 H 82 Cu5S4N 22 The structural formula of P4]PF6 is I.

[0027] In this type of core-shell pentanuclear copper (I) complex, the auxiliary ligands bridge copper (I) via tetrazolium and μ3-S bridging, respectively, forming a unique pentanuclear structure. The host ligand L coordinates with two copper atoms using bisphosphine groups, providing high spatial rigidity around the core Cu5S4. The overall molecular structure of the complex is conducive to achieving high-performance luminescence.

[0028] (3) The core-shell structured pentanuclear copper (I) complex prepared by this invention has an optimal excitation wavelength of 403 nm and an optimal emission wavelength of 605 nm under 298 K conditions, exhibiting orange luminescence. Its photoluminescence quantum yield reaches 51.2%, and its luminescence lifetime is 3.81 μs. Its maximum emission wavelength under 77 K conditions is 570 nm, and its luminescence lifetime is 76.66 μs. It is an orange phosphorescent material.

[0029] (4) The preparation method of this invention is mild, simple, and easy to operate. It can be prepared at room temperature without strict reaction conditions or expensive reaction equipment. The prepared core-shell-like pentanuclear copper (I) complex is a highly efficient orange phosphorescent material that can be used in the field of high-efficiency light-emitting OLEDs. Attached Figure Description

[0030] Figure 1 It is a pentanuclear copper(I) complex with a core-shell structure [C 112 H 82 Cu5S4N 22 Crystal structure of P4]PF6.

[0031] Figure 2 This is the liquid UV-Vis absorption spectrum of ligand L and its complex [R]PF6, where R represents C 112 H 82 Cu5S4N 22 P4.

[0032] Figure 3 This is the solid UV-Vis absorption spectrum of the complex [R]PF6.

[0033] Figure 4 The solid powder excitation and emission spectra of the complex [R]PF6 are shown in (a) and its emission color coordinates at 298 K (b). Detailed Implementation

[0034] To better understand the content of this invention, it will be further described below with reference to specific embodiments and accompanying drawings. The following embodiments are based on the technology of this invention and provide detailed implementation methods and operating steps, but the scope of protection of this invention is not limited to the following embodiments.

[0035] The method for preparing the core-shell-like pentanuclear copper(I) complex provided by this invention includes the following steps:

[0036] (1) Add 0.1 mmol (0.0639 g) of pyridine-imidazolium bisphosphine ligand L and 0.2 mmol (0.0356 g) of auxiliary ligand 1-phenyl-1H-tetrazole-5-thiol (Hppt) to 12 mL of a mixed solvent of CH2Cl2 and CH3OH, stir well to obtain a mixed solution.

[0037] (2) Add 0.25 mmol (0.0932 g) [Cu(CH3CN)4]PF6 (copper hexafluorophosphate tetraacetonitrile (I)) to the above mixed solution, stir at room temperature for 10 min, and then filter into a single crystal culture flask. The filtrate slowly evaporates in the culture flask at room temperature to obtain transparent pale yellow crystals.

[0038] (3) Collect the crystals obtained in step (2), wash the crystals with 0.5 mL of anhydrous ethanol and dry them in a vacuum drying oven at 45 °C to obtain the target product - a core-shell structured pentanuclear copper (I) complex; with ligand L as a reference, the molar yield of the product is 61%.

[0039] The structural formula of the pyridine-imidazolium bisphosphine ligand L described in step (1) is shown in Formula II:

[0040]

[0041] The volume ratio of CH2Cl2 to CH3OH in the mixed solvent of CH2Cl2 and CH3OH is 4:1.

[0042] The reaction equation for step (2) is:

[0043]

[0044] Product [C] 112 H 82 Cu5S4N 22 The structural formula of P4]PF6 is shown in Equation I:

[0045]

[0046] It includes cationic complexes [C 112 H 82 Cu5S4N 22 P4] +1 And anionic complex [PF6] -1 Product [C] 112 H 82 Cu5S4N 22 The crystal structure of P4]PF6 is as follows Figure 1 As shown, Figure 1 In this context, Cu5S4 is located at the center of the crystal structure, making [C] 112 H 82 Cu5S4N 22 P4]PF6 forms a core-shell-like structure.

[0047] The obtained core-shell-like pentanuclear copper(I) complex was characterized and tested below:

[0048] (1) Single-crystal structure analysis of pentanuclear copper (I) complexes with a core-shell structure

[0049] Single-crystal data of the complex were collected using a Bruker AMART APEXⅡ CCD X-ray diffractometer, and then the data were restored and the structure was analyzed using the SHELXTL program. The position of the metal center was determined by the direct method, and the coordinates of non-hydrogen atoms were obtained by the difference function method and the least squares method. Anisotropic corrections were made for the non-hydrogen atoms, and the hydrogen atoms were theoretically hydrogenated. The crystal structure parameters of the prepared core-shell-like pentanuclear copper(I) complex are shown in Table 1.

[0050] Table 1. Crystal structure parameters of pentanuclear copper(I) complexes with core-shell-like structures

[0051]

[0052] X-ray single-crystal diffraction results show that the cationic complex [C 112 H 82 Cu5S4N 22 P4] +1 It includes 5 copper (I) centers ( Figure 1 The four outer copper (I) groups each coordinate with one p atom of the pyridine-imidazolium bisphosphine ligand L, one nitrogen atom and two sulfur atoms of the three deprotonated 1-phenyl-1H-tetrazole-5-thiol, forming a deformed tetrahedral coordination structure; wherein the Cu-N bond length ranges from [missing information]. The bond length range of Cu1-S is The bond length of Cu1-P1 is 2.2224(11), and the bond length of Cu2-P2 is... It is noteworthy that the S atom on each auxiliary ligand is also coordinated with the central Cu(I), and the Cu-S bond length around the central Cu3 varies within a range of... The distance between adjacent copper...copper is within the range of The radius is smaller than the sum of the van der Waals radii of copper atoms; therefore, there are significant intermetallic interactions in the complex.

[0053] As the above analysis shows, in this complex, the auxiliary ligands bridge copper (I) through tetrazolium and μ3-S bridging, forming a unique pentanuclear structure. The central Cu(I) is not only connected to the S atoms of the four auxiliary ligands, but also has weak Cu…Cu interactions with the four surrounding copper atoms, thus achieving spatial confinement of the central copper (I). The main ligand L coordinates to the two surrounding copper (I) atoms using bisphosphine groups, providing high spatial rigidity around the core Cu5S4. The overall molecular structure of the complex is conducive to achieving high-performance luminescence.

[0054] (2) Ultraviolet-Vis absorption spectroscopy analysis of pentanuclear copper(I) complexes with core-shell structure

[0055] Ultraviolet-visible absorption spectroscopy analysis was performed using a UV-Vis spectrophotometer. At room temperature, the prepared core-shell-like pentanuclear copper(I) complex and the main ligand L were added to a certain amount of dichloromethane solution to prepare a solution with a concentration of 1×10⁻⁶. -5 The measurements were performed using a mol / L solution, and the liquid UV-Vis absorption spectra of both at room temperature are shown below. Figure 2 As shown, from Figure 2 As can be seen, the UV absorption of the core-shell-like pentanuclear copper(I) complex mainly originates from the absorption contribution of ligand L. A strong absorption peak is observed around 230 nm, which is attributed to the allowed π→π* transition within the ligand. The moderately strong absorption peak in the 295-315 nm range is attributed to the charge transfer (ILCT) transition within the pyridine-imidazole ligand. Furthermore, the core-shell-like pentanuclear copper(I) complex exhibits a weak absorption in the 350-460 nm range not found in ligand L, which is attributed to the metal-to-ligand charge transfer (MLCT) transition.

[0056] The solid UV-Vis absorption spectrum of a core-shell-like pentanuclear copper(I) complex is shown below. Figure 3 As shown, from Figure 3 As can be seen, the complex has a broad and strong absorption peak at 395 nm. The absorption here mainly comes from the mixing of ILCT and MLCT transitions, indicating that the complex has intermolecular interactions.

[0057] (3) Photoluminescence properties of pentanuclear copper (I) complexes with core-shell structure

[0058] like Figure 4 As shown, at room temperature (298 K), the solid powder of the pentanuclear copper(I) complex with a core-shell structure exhibits bright orange luminescence under ultraviolet light excitation, and its excitation and emission spectra are as follows. Figure 4 As shown in (a), the optimal excitation wavelength of the complex is 403 nm, and the optimal emission wavelength is 605 nm, exhibiting orange luminescence. Figure 4 (b) It is noteworthy that the emission spectrum is a broad single peak, indicating that the luminescent excited state of the complex exhibits charge-transfer transition characteristics. More importantly, the photoluminescence quantum yield of the complex reaches 51.2%, while the luminescence lifetime is only 3.81 μs; it is an excellent orange luminescent material.

[0059] Further testing at a low temperature of 77K yielded an emission spectrum that still lacked fine structure, such as... Figure 4 (a) The maximum emission wavelength is 570 nm, a blue shift of 35 nm compared to room temperature, and the lifetime increases to 76.66 μs, suggesting that its luminescence is phosphorescence. Therefore, the complex [C112 H 82 Cu5S4N 22 P4]PF6 is an excellent type of orange phosphorescent material.

[0060] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. The present invention can also have other embodiments based on the above structure and function, which will not be listed hereafter. Therefore, any simple modifications, equivalent changes, and alterations made by those skilled in the art to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A pentanuclear copper(I) complex with a core-shell structure, characterized in that... Its molecular formula is [C 112 H 82 Cu5S4N 22 P4]PF6, with a molecular weight of 2469.78, has a monoclinic crystal system and a space group of [missing information]. P 2 / n, with unit cell parameters: a = 17.1632(8) Å, b = 13.0184(7) Å, c = 26.4129(14) Å, α = 90°, β = 100.121(2)°, γ = 90°; its unit cell volume is 5809.8(5) Å. 3 Its structural formula is shown in Formula I: Formula I.

2. The pentanuclear copper(I) complex with a core-shell structure as described in claim 1, characterized in that... Its optimal excitation wavelength at 298K is 403 nm, and its optimal emission wavelength is 605 nm. It exhibits orange emission, with a photoluminescence quantum yield of 51.2% and a luminescence lifetime of 3.81 μs.

3. The pentanuclear copper(I) complex with a core-shell structure as described in claim 1, characterized in that... It has a maximum emission wavelength of 570 nm and a luminescence lifetime of 76.66 μs at 77 K, and is an orange phosphorescent material.

4. The application of the core-shell structured pentanuclear copper (I) complex as described in claim 1 in the field of high-efficiency light-emitting OLEDs.

5. A method for preparing a core-shell-like pentanuclear copper(I) complex, characterized in that... Includes the following steps: (1) Add ligand L and auxiliary ligand 1-phenyl-1H-tetrazole-5-thiol to a mixed solvent of CH2Cl2 and CH3OH in a molar ratio of 1:2, stir until homogeneous, and obtain a mixed solution; (2) Add [Cu(CH3CN)4]PF6 to the above mixed solution, stir at room temperature for 10 min and filter into a culture flask. The filtrate slowly evaporates in the culture flask at room temperature to obtain transparent pale yellow crystals; wherein, the molar ratio of [Cu(CH3CN)4]PF6 to ligand L is 2.5:1; (3) Collect the crystals obtained in step (2), wash the crystals with anhydrous ethanol and dry them in a vacuum drying oven at 45°C to obtain the target product - a pentanuclear copper (I) complex with a core-shell structure; The structural formula of ligand L mentioned in step (1) is shown in formula II: Formula II; The molecular formula of the resulting core-shell-like pentanuclear copper(I) complex is [C 112 H 82 Cu5S4N 22 P4]PF6, with a molecular weight of 2469.78, has a monoclinic crystal system and a space group of [missing information]. P 2 / n, with unit cell parameters: a = 17.1632(8) Å, b = 13.0184(7) Å, c = 26.4129(14) Å, α = 90°, β = 100.121(2)°, γ = 90°; its unit cell volume is 5809.8(5) Å. 3 Its structural formula is shown in Formula I: Formula I.

6. The method for preparing the core-shell-like pentanuclear copper(I) complex as described in claim 5, characterized in that... In a mixed solvent of CH2Cl2 and CH3OH, the volume ratio of CH2Cl2 to CH3OH is 4:

1.

7. The method for preparing the core-shell-like pentanuclear copper(I) complex as described in claim 5, characterized in that... With ligand L as a reference, the molar yield of the core-shell-like pentanuclear copper (I) complex was 61%.

8. The method for preparing the core-shell-like pentanuclear copper(I) complex as described in claim 5, characterized in that... The prepared core-shell-like pentanuclear copper(I) complex exhibited an optimal excitation wavelength of 403 nm and an optimal emission wavelength of 605 nm at 298 K, displaying orange luminescence with a photoluminescence quantum yield of 51.2% and a luminescence lifetime of 3.81 μs. It has a maximum emission wavelength of 570 nm and a luminescence lifetime of 76.66 μs at 77K, and is an orange phosphorescent material.

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