A red light-emitting subcopper complex and a preparation method and application thereof
By synthesizing cuprous complexes and introducing N^P ligands, the problems of high cost and severe pollution of precious metal materials have been solved, enabling the preparation of efficient and inexpensive red luminescent materials for application in the OLED field.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHENGZHOU UNIV
- Filing Date
- 2023-07-10
- Publication Date
- 2026-05-19
AI Technical Summary
Among existing OLED luminescent materials, precious metal materials are expensive and cause serious pollution, making it difficult to prepare efficient and inexpensive red luminescent materials.
Cuprous complexes were used as luminescent materials and synthesized at room temperature using a simple and mild method. Aromatic N^P ligands were introduced to increase the spatial rigidity of the complexes, forming a stable tetrahedral configuration and improving optical performance.
A red cuprous complex with excellent luminescence properties was prepared, with a photoluminescence quantum yield of 35.2% and a luminescence lifetime of 5.8 μs, which is suitable for the field of high-efficiency OLEDs.
Smart Images
Figure CN116947893B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of luminescent material synthesis technology, specifically a red-luminescent cuprous complex, its preparation method, and its application. Background Technology
[0002] In the 21st century, the information age, displays have become increasingly important as a crucial medium for information exchange. Organic light-emitting diodes (OLEDs), with their superior characteristics such as low power consumption, high efficiency, thinness, high contrast, and rich color emission, are becoming the mainstream development direction of new display technologies worldwide. The light-emitting material is key to the performance of OLEDs and can generally be divided into small molecules and polymers. Small molecule light-emitting materials can be further divided into organic compounds and complexes. Complexes combine the stability of inorganic materials with the modifiability of organic materials, increasing their practicality and application range.
[0003] In phosphorescent materials, the heavy metals in transition series noble metals such as Ir, Pt, and Os exhibit strong spin-orbit coupling (SOC) effects, allowing triplet states and increasing the intersystem crossing (ISC) rate. This efficient utilization of 25% singlet excitons and 75% triplet excitons enhances the material's photophysical properties. However, these materials are expensive, and their mining causes significant environmental pollution, limiting their practical application. Therefore, designing and synthesizing novel, efficient, and inexpensive luminescent materials has significant scientific research and application value.
[0004] Among numerous OLED luminescent materials, cuprous complexes are considered excellent alternatives to noble metals due to their abundant resources, low cost, low pollution, diverse coordination modes, and easily tunable emission color. Therefore, research on cuprous complexes is of great significance in developing novel, inexpensive, and high-performance luminescent materials. Since the excited-state structure of monovalent copper complexes is easily deformable, leading to increased nonradiative transitions and decreased photoluminescence quantum yield, the introduction of N^P ligands with aromatic systems can not only increase the spatial rigidity of the complex but also effectively stabilize monovalent copper, thereby maintaining the tetrahedral configuration of the complex and improving its optical performance. Summary of the Invention
[0005] This invention provides a red luminescent cuprous complex, its preparation method, and its application. The aim is to prepare a cuprous complex with excellent luminescent properties under room temperature conditions using a simple and mild method, simplifying the operation process, reducing production costs, and eliminating the need for expensive equipment. The obtained cuprous complex has excellent luminescent properties and is an excellent pure red phosphorescent material that can be used in the field of high-efficiency OLEDs.
[0006] One objective of this invention is to provide a red-luminescent cuprous complex with the molecular formula C0.70 H 51 Cu4S4N 19 P2, with a molecular weight of 1601.64, has the structural formula shown in Formula I:
[0007]
[0008] Its structural unit belongs to the triclinic crystal system, with space group P-1 and cell parameters as follows: α = 100.433(17)°, β = 92.74(2)°, γ = 111.458(17)°; its unit cell volume is
[0009] Furthermore, the optimal excitation wavelength of the red-emitting cuprous complex at 298K is 450nm, the optimal emission wavelength is 630nm, and it exhibits red emission with a photoluminescence quantum yield of 35.2% and a luminescence lifetime of 5.8μs.
[0010] Furthermore, the red-luminescent cuprous complex has a maximum emission wavelength of 621 nm and a luminescence lifetime of 37.41 μs at 77 K, making it a pure red phosphorescent material.
[0011] The present invention also aims to provide a method for preparing a red-luminescent cuprous complex, which specifically includes the following steps:
[0012] (1) Add ligand A and auxiliary ligand 1-phenyl-1H-tetrazole-5-thiol to a mixed solvent of CH2Cl2 and CH3OH in a molar ratio of 1:4, 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, filter into a culture flask, and slowly evaporate the filtrate in the culture flask at room temperature to obtain crystals; wherein, the molar ratio of [Cu(CH3CN)4]PF6 to ligand A is 4:1;
[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 orange solid powder, which is the red luminescent cuprous complex.
[0015] The structural formula of ligand A in step (1) is shown in formula II:
[0016]
[0017] The molecular formula of the obtained red-luminescent cuprous complex is C 70 H 51 Cu4S4N19 P2, with a molecular weight of 1601.64, belongs to the triclinic crystal system, space group P-1, and its unit cell parameters are: α = 100.433(17)°, β = 92.74(2)°, γ = 111.458(17)°; its unit cell volume is
[0018] Furthermore, the volume ratio of CH2Cl2 to CH3OH in the mixed solvent of CH2Cl2 and CH3OH is 4:1.
[0019] Furthermore, with ligand A as a reference, the molar yield of the red-luminescent cuprous complex was 77%.
[0020] Furthermore, the prepared red-luminescent cuprous complex exhibits an optimal excitation wavelength of 450 nm and an optimal emission wavelength of 630 nm at 298 K, displaying red emission with a photoluminescence quantum yield of 35.2% and a luminescence lifetime of 5.8 μs. At 77 K, its maximum emission wavelength is 621 nm and its luminescence lifetime is 37.41 μs, making it a pure red phosphorescent material.
[0021] Another object of the present invention is to provide the application of the above-mentioned red luminescent cuprous complex in the field of high-efficiency OLEDs. The red luminescent cuprous complex is a pure red phosphorescent material with very good photoluminescence properties.
[0022] The present invention has the following beneficial effects:
[0023] (1) The red-luminescent cuprous complex solid powder prepared in this invention exhibits red luminescence under ultraviolet light excitation, with a broad emission spectrum and no fine structure, indicating the presence of charge-transfer transition characteristics. The photoluminescence quantum yield of the cuprous complex R is 35.2%.
[0024] (2) The red luminescent cuprous complex R prepared in this invention belongs to the triclinic crystal system, space group P-1, and contains one main ligand A, four copper atoms with a tetrahedral configuration, and four auxiliary ligands. Each copper atom of Cu2, Cu3, and Cu4 is connected to three auxiliary ligands. The N and S atoms on each auxiliary ligand are connected to two different Cu atoms in a bidentate chelate manner. Cu1 is connected to three S atoms, forming a unique triangular configuration with Cu1, Cu2, and S1 as vertices. All Cu atoms are tetracoordinated, but there are three different coordination modes. These three coordination modes result in three different Cu…Cu bond lengths in the complex. There is basically no interaction between the center of Cu1 and Cu3 and Cu4, while there is a strong Cu…Cu interaction between Cu1 and Cu2.
[0025] (3) The red luminescent cuprous complex prepared by the present invention has an optimal excitation wavelength of 450 nm and an optimal emission wavelength of 630 nm under 298 K conditions, exhibits red luminescence, and has a luminescence lifetime of 5.8 μs; its maximum emission wavelength under 77 K conditions is 621 nm and its luminescence lifetime is 37.41 μs, which is a pure red phosphorescent material.
[0026] (4) The preparation method of this invention is mild, simple, and easy to operate. It can be prepared at room temperature without requiring strict reaction conditions or expensive reaction equipment. The prepared red luminescent cuprous complex is a class of highly efficient pure red phosphorescent materials that can be used in the field of high-efficiency OLEDs. Attached Figure Description
[0027] Figure 1 This is the crystal structure of complex R (hydrogen atoms and solvent molecules are not shown).
[0028] Figure 2 These are the intramolecular and intermolecular interaction forces of the complex R.
[0029] Figure 3 This is the liquid UV-Vis absorption spectrum of ligand A and complex R.
[0030] Figure 4 This is the excitation and emission spectrum of the solid powder of the complex R at 298 K.
[0031] Figure 5 This is the excitation and emission spectrum of the solid powder of the complex R at 77 K. Detailed Implementation
[0032] 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.
[0033] The method for preparing a red luminescent cuprous complex provided by the present invention specifically includes the following steps:
[0034] (1) Add 0.05 mmol (0.032 g) of ligand A 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, and stir until homogeneous to obtain a mixed solution. The volume ratio of CH2Cl2 to CH3OH in the mixed solvent is 4:1.
[0035] (2) Add 0.2 mmol (0.0745 g) [Cu(CH3CN)4]PF6 (copper hexafluorophosphate tetraacetonitrile (I)) to the above mixed solution, stir at room temperature for 10 min, filter into a culture flask, and allow the filtrate to slowly evaporate at room temperature in the culture flask to obtain complex crystals.
[0036] (3) Collect the complex 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 an orange solid powder. The orange solid powder is the tetranuclear cuprous complex R. With ligand A as a reference, the molar yield of the product tetranuclear cuprous complex R is 77%.
[0037] The structural formula of ligand A mentioned in step (1) is shown in formula II:
[0038]
[0039] The reaction equation for step (2) is:
[0040]
[0041] The structural formula of the product cuprous complex R is shown in Formula I below:
[0042]
[0043] The prepared tetranuclear cuprous complex R was characterized and tested below:
[0044] (1) Single-crystal structure analysis of tetranuclear cuprous complex R
[0045] Single-crystal data for the prepared tetranuclear cuprous complex were collected using a Bruker AMART APEXⅡ CCD X-ray single-crystal diffractometer, followed by absorption correction using the SADABS multiple scan procedure. The structure was solved using a direct method, and the results were obtained using the SHELXTL and Olex2 programs based on F... 2 The matrix was refined using the full-matrix least squares method. Anisotropic refinement was performed for non-hydrogen atoms, with hydrogen atoms theoretically hydrogenated. The crystal structure parameters of the prepared tetranuclear cuprous complex R are shown in Tables 1 and 2.
[0046] Table 1. Crystal structure parameters of cuprous complex R
[0047]
[0048]
[0049] Table 2. Main bond lengths of complex R Bond angle (°)
[0050]
[0051]
[0052] Cuprous complex R (R is C 70 H 51 Cu4S4N 19 Single-crystal structure analysis of P2) shows that: complex C 70 H 51 Cu4S4N 19 P2 belongs to the triclinic crystal system, space group P-1, and contains one main ligand A, four tetrahedral copper atoms, and four auxiliary ligands. Each copper atom in Cu2, Cu3, and Cu4 is connected to three auxiliary ligands. The N and S atoms on each auxiliary ligand are connected to two different Cu atoms in a bidentate chelate manner. Cu1 is connected to three S atoms in a rare coordination mode, forming a unique triangular configuration with Cu1, Cu2, and S1 as vertices. The bond angles of S1-Cu1-Cu2, S1-Cu2-Cu1, and Cu2-S1-Cu1 are 52.423 (2), 55.097 (21), and 55.097 (21), respectively. All Cu atoms have a tetracoordinate configuration, but there are three different coordination modes. Cu3 coordinates with one phosphorus atom (P2) in the main ligand A, two sulfur atoms (S2 and S4) in the two auxiliary ligands, and one nitrogen atom (N16) in one auxiliary ligand. Cu4 coordinates with one phosphorus atom (P1) in the main ligand A, two sulfur atoms (S3 and S4) in the two auxiliary ligands, and one nitrogen atom (N7) in one auxiliary ligand. Cu2 coordinates with Cu1, two nitrogen atoms (N11 and N12) in the two auxiliary ligands, and one sulfur atom (S1) in one auxiliary ligand. Cu1 coordinates with Cu2 and three sulfur atoms (S1, S2, and S3) in the three auxiliary ligands. These three coordination modes result in three different Cu…Cu bond lengths in the complex, namely, the distances between Cu1 and Cu4 and between Cu1 and Cu3 are respectively… and The distance is greater than the van der Waals radius of copper, indicating that there is essentially no interaction between the center of Cu1 and Cu3 and Cu4, while the distance between Cu1 and Cu2 is... There is a strong Cu…Cu interaction.
[0053] The lengths of the two Cu-S bonds surrounding the center of Cu3 are respectively (Cu3-S2) (Cu3-S4), the lengths of the two Cu-S bonds surrounding the center of Cu4 are respectively (Cu4-S3) (Cu4-S4) are all similar, while the three Cu-S bonds surrounding the center of Cu1 are respectively (Cu1-S1) (Cu1-S2) (Cu1-S3), compared to the Cu-S complexes reported in the literature that utilize S as a monodentate ligand in monovalent copper complexes, The short Cu-S bond length is speculated to be due to the weak interaction between Cu1 and Cu4 and the bidentate chelation of N and S, which shortens the Cu-S bond. The Cu-P bond length varies from 2.2383 (13)- The distance of the Cu-N bond is 1.928(4)- Within this range, the bond lengths are consistent with those reported in the literature for such cuprous complexes. Furthermore, the distance between the S atom in complex R and the H atom on the auxiliary ligand 1-phenyl is... There is a weak CH…S interaction, and from Figure 2 It can also be seen that the distance between the pyridyl planes of the two molecules is There are weak π…π interactions.
[0054] (2) UV-Vis absorption spectroscopy analysis of tetranuclear cuprous complex
[0055] The prepared tetranuclear cuprous complex R (R is C 70 H 51 Cu4S4N 19 P2) and main ligand A were tested at room temperature to obtain their liquid UV-Vis absorption spectra, as shown in the figure. Figure 3 As shown, the UV absorption of the tetranuclear cuprous complex mainly originates from the absorption contribution of ligand A. Both ligand A and the cuprous complex R exhibit strong absorption peaks in the 225-309 nm range, primarily attributed to the intra-intra-phase charge transfer (ILCT) transition within the pyridine-imidazole ligand A. Furthermore, all complexes exhibit additional absorption beyond the ligand in the 360-440 nm range; this weak absorption can be attributed to the intra-intra-phase charge transfer (MLCT) transition from metallic copper to the ligand.
[0056] (3) Photoluminescence properties of tetranuclear cuprous complex
[0057] At room temperature (298 K), the cuprous complex R solid powder exhibits red luminescence under ultraviolet light excitation, and its excitation and emission spectra are as follows: Figure 4 As shown, the optimal excitation wavelength of the complex is 450 nm, and the optimal emission wavelength is 630 nm. The broad emission spectrum and lack of fine structure indicate the presence of charge-transfer transition characteristics. The photoluminescence quantum yield of the cuprous complex R is 35.2%. As discussed in the structural section, this may be due to the enhanced structural rigidity of the complex through π…π interactions between the cuprous complex molecules, which improves its luminescence performance. Complex R exhibits a luminescence lifetime of 5.8 μs at room temperature (298 K).
[0058] Further testing of the emission spectrum of the cuprous complex R at a low temperature of 77K is shown in the figure. Figure 5 As shown in Table 3, the luminescence data of the cuprous complex R solid powder are shown in Table 3.
[0059] Table 3. Luminescence data of solid powder of complex R
[0060]
[0061] The low-temperature (77K) spectrum of complex R Figure 5 It can be seen that the maximum emission wavelength is 621 nm, which is a 9 nm blue shift compared to room temperature, with little change in lifetime. Based on the large Stokes shift of the complex and the microsecond-level lifetime of the excited state, the luminescence of this complex in the excited state may mainly originate from... 3 MLCT transition. The above results indicate that complex R is a pure red phosphorescent material.
[0062] 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 red-luminescent cuprous complex, characterized in that... Its molecular formula is C 70 H 51 Cu4S4N 19 P2, with a molecular weight of 1601.64, has the structural formula shown in Formula I: Formula I; Its structural unit belongs to the triclinic crystal system, and its space group is . P -1, the unit cell parameters are: a = 13.781(10) Å, b = 15.741(11) Å, c = 21.036(15) Å, α=100.433(17)°, β=92.74(2)°, γ=111.458(17)°; its unit cell volume is 4144(5) Å. 3 .
2. The red-luminescent cuprous complex as described in claim 1, characterized in that... Its optimal excitation wavelength at 298K is 450 nm, and its optimal emission wavelength is 630 nm. It exhibits red emission, with a photoluminescence quantum yield of 35.2% and a luminescence lifetime of 5.8 μs.
3. The red-luminescent cuprous complex as described in claim 1, characterized in that... Its maximum emission wavelength at 77 K is 621 nm, and its luminescence lifetime is 37.41 μs. It is a pure red phosphorescent material.
4. A method for preparing a red-luminescent cuprous complex, characterized in that... Includes the following steps: (1) Add ligand A and auxiliary ligand 1-phenyl-1H-tetrazole-5-thiol to a mixed solvent of CH2Cl2 and CH3OH in a molar ratio of 1:4, 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, filter into a culture flask, and slowly evaporate the filtrate in the culture flask at room temperature to obtain crystals; wherein, the molar ratio of [Cu(CH3CN)4]PF6 to ligand A is 4:1; (3) Collect the crystals obtained in step (2), wash the crystals with anhydrous ethanol, and then dry them in a vacuum drying oven at 45°C. o C. Drying yields an orange solid powder, which is the red-luminescent cuprous complex. The structural formula of ligand A in step (1) is shown in formula II: Formula II; The molecular formula of the obtained red-luminescent cuprous complex is C 70 H 51 Cu4S4N 19 P2, with a molecular weight of 1601.64, has the structural formula shown in Formula I: Formula I; Its structural unit belongs to the triclinic crystal system, and its space group is . P -1, the unit cell parameters are: a = 13.781(10) Å, b = 15.741(11) Å, c = 21.036(15) Å, α=100.433(17)°, β=92.74(2)°, γ=111.458(17)°; its unit cell volume is 4144(5) Å. 3 .
5. The method for preparing the red luminescent cuprous complex as described in claim 4, characterized in that... In a mixed solvent of CH2Cl2 and CH3OH, the volume ratio of CH2Cl2 to CH3OH is 4:
1.
6. The method for preparing the red luminescent cuprous complex as described in claim 4, characterized in that... With ligand A as a reference, the molar yield of the red-luminescent cuprous complex was 77%.
7. The method for preparing the red luminescent cuprous complex as described in claim 4, characterized in that... The prepared red-luminescent cuprous complex exhibits an optimal excitation wavelength of 450 nm and an optimal emission wavelength of 630 nm at 298 K, displaying red luminescence. Its photoluminescence quantum yield reaches 35.2%, and its luminescence lifetime is 5.8 μs. Its maximum emission wavelength at 77 K is 621 nm, and its luminescence lifetime is 37.41 μs. It is a pure red phosphorescent material.
8. The application of the red-emitting cuprous complex of claim 1 or 4 in the field of high-efficiency OLEDs.