Heteronuclear complexes sensitized by rare earth ions and their use as luminescent materials

Abstract

A luminescent material is a complex with the following structural formula: wherein R and R' are independently selected from oxygen, amino, C1-C18 straight-chain or branched alkyl-substituted amino, phosphin, C1-C18 straight-chain or branched alkyl-substituted phosphin, sulfur, and selenium; R1, R2, R3, R4, R5, and R6 are independently selected from hydrogen, C1-C18 straight-chain or branched alkyl or halogen-substituted C1-C18 straight-chain or branched alkyl, aromatic... Aromatic groups such as benzene, thiophene, and furan, n = 1–3, are used to construct cyclic ligand skeletons with different half-ring numbers. Ln is one of the following: cerium trivalent ion, europium divalent ion, ytterbium divalent ion, and samarium divalent ion. M is one of the following: manganese divalent ion, cobalt trivalent ion, chromium trivalent ion, vanadium trivalent ion, and ferric trivalent ion. X is a monovalent ion, such as halogen, cyanide, thiocyanate, isothiocyanate, etc., m = 0–3, l = 3–6. X acts as a monodentate ligand or as a bridging bidentate ligand.

Description

Technical Field

[0001] This invention belongs to the field of luminescent materials. Specifically, it relates to a rare-earth-transition-metal heteronuclear complex and its application as a luminescent material. Background Technology

[0002] The transition elements of the third period are abundant in the Earth's crust and can achieve a wide range of colors through 3d-3d transitions, making them ideal elements for preparing visible light-emitting materials. Among these metallic elements, manganese (Mn) has been the most extensively studied in luminescent materials, particularly when doped with Mn. 4+ Red inorganic phosphor K2SiF6:Mn 4+ It has been industrialized, but it is expensive, and the core patents are held by foreign applicants. 2+ The light emission is based on 4 T1- 6 The single-peak emission of the A1 transition is significantly influenced by the ligand field; it typically emits green light in a tetrahedral field and red light in an octahedral field. Research on metals such as chromium, cobalt, and titanium in the field of luminescence is relatively limited. Their central ion emission can cover the spectrum from blue to near-infrared light, demonstrating potential as luminescent materials. Co 3+ The complexes of Cr exhibit low dd transition energy levels under weak fields, easily forming nonradiative relaxation channels, resulting in poor luminescence performance and limited related reports. 3+ It emits light primarily in the near-infrared region and is typically used as an activating ion in inorganic phosphors. The luminescence of its complexes is easily quenched by the high-frequency vibrations of the covalent bonds of hydrogen atoms in organic ligands. In addition, there is V... 3+ Fe 3+ etc. 3d-3d transitions are selection-forbidden transitions, and their oscillator strength is in the range of 10. -5 With an absorption rate of around the order of magnitude, it exhibits low absorbance and a long excited-state lifetime, which is unfavorable for preparing high-performance fluorescent materials with high optical density. The long excited-state lifetime also makes it prone to quenching of the excited-state centers by nonradiative transitions caused by defects in the matrix, thereby reducing the luminescence quantum efficiency of the luminescent material.

[0003] Among the lanthanides, there is a class of rare-earth luminescent ions, such as Ce. 3+ Eu 2+ Yb 2+ and Sm 2+ Eu can emit light through a 5d-4f transition, which is parity allowed. The oscillator strength of this electric dipole transition can reach 0.01-1, and the absorbance can be thousands of times that of a forbidden transition, while also exhibiting a relatively short excited-state lifetime. As early as the 1970s, researchers attempted to co-dope Eu in inorganic matrices. 2 + / Ce 3+ and Mn 2+Using rare earth ions as sensitizers, Mn 2+ As an activator, it enables the use of Eu 2+ / Ce 3+ Sensitized Mn 2+ Ultimately, a more characteristic Mn is achieved. 2+ Emission. The inorganic matrices they selected included calcium halides, calcium aluminosilicates, alkaline earth metal salts of silicates, and alkaline earth metal salts of phosphates. However, in these materials, the energy transfer efficiency between the two metal ions is significantly affected by the interionic distance (concentration), generally resulting in incomplete energy transfer. This leads to the simultaneous emission of rare earth ions and manganese ions, thus affecting luminescence performance and hindering its practical application. Therefore, the preparation of Mn with high luminescence efficiency, high absorbance, and single-peak emission is crucial. 2+ Compounds are a technical challenge that urgently needs to be solved. Besides Mn... 2+ Co 3+ Cr 3+ The introduction of [element name] can expand the emission spectrum and has potential application prospects. Summary of the Invention

[0004] This invention is the first to utilize rare-earth ions with 5d-4f transitions and 3d transition metals to prepare heteronuclear bimetallic luminescent complexes, integrating the advantages of strong absorbance of these rare-earth ions and rich luminescence colors of 3d transition metal ions. In the structure of the complex, the rare-earth ion encapsulated by a cyclic neutral ligand forms a large cation, while the 3d transition metal ion encapsulated by a monovalent anion forms a large anion. Although both are metal ions, the ligand design forms positive and negative charge centers, successfully preparing a heteronuclear complex luminescent material with a short distance between the two ions and high energy transfer efficiency. The structural formula of the luminescent material is shown below:

[0005]

[0006] R and R' are independently selected from oxygen, amino group, C1-C18 straight-chain or branched alkyl-substituted amino group, phosphine group, C1-C18 straight-chain or branched alkyl-substituted phosphine group, sulfur, and selenium. R1, R2, R3, R4, R5, and R6 are independently selected from hydrogen, C1-C18 straight-chain or branched alkyl group or halogen-substituted C1-C18 straight-chain or branched alkyl group, and aromatic groups such as benzene, thiophene, and furan. n = 1 to 3, thereby constructing a cyclic ligand skeleton with different half-ring numbers. Ln is one of cerium trivalent ion, europium divalent ion, ytterbium divalent ion, and samarium divalent ion. M is one of divalent manganese ion, trivalent cobalt ion, trivalent chromium ion, trivalent vanadium ion, and trivalent iron ion. X is a negative monovalent ion, such as halogen, cyanide, thiocyanate, isothiocyanate, etc. m = 0 to 3, and l = 3 to 6. X can be used as a monodentate ligand or as a bridging bidentate ligand.

[0007] According to one embodiment of the present invention, for example, the organic ligand of the luminescent material includes at least one of the following compounds:

[0008]

[0009] According to one embodiment of the present invention, for example, the luminescent material comprises at least one of the following compounds:

[0010]

[0011] Embodiments of the present invention provide a luminescent material that serves as a light-converting material for deep blue light, near-ultraviolet light, or X-rays.

[0012] According to one embodiment of the present invention, for example, a light-emitting conversion layer is formed by mixing a luminescent material and a polymeric material, wherein the luminescent material is the luminescent material as described above, and the polymeric material is a high-transparency industrially produced polymer;

[0013] Preferably, the wavelength of the excitation source is between 280-480 nm;

[0014] Preferably, the doping concentration of the luminescent material in the light-emitting conversion layer is 0.01wt%-60wt%, more preferably 0.1wt%-30wt%, where the doping concentration is the percentage of the mass of the luminescent material to the total mass of the polymer.

[0015] Preferably, the polymer material is selected from at least one of polymethyl methacrylate (PMMA), polyethylene (PE), ethylene-butene / octene polymer (POE), ethylene-vinyl acetate copolymer (EVA), polystyrene (PS), and polydimethylsiloxane (PDMS);

[0016] More preferably, the polymer material is PS. Attached Figure Description

[0017] Figure 1 This is the ellipsoidal model (50% probability) single crystal structure of the complexes [Ce(N8)Br]MnBr4(a) and [Eu(N2O6)]MnBr4(b) in Example 2 of this invention. All hydrogen atoms have been omitted, and some representative atoms have been labeled.

[0018] Figure 2 The complexes [Ce(N8)Br]MnBr4 and [Eu(N2O6)]MnBr4 in Example 3 of this invention are in methanol solution (1×10⁻⁶). -3 The ultraviolet-visible absorption spectrum of M).

[0019] Figure 3The photoluminescence spectra of methanol solutions of the complexes [Ce(N8)Br]MnBr4 and [Eu(N2O6)]MnBr4 in Example 3 of this invention are shown.

[0020] Figure 4 The photoluminescence spectra of the solid complexes [Ce(N8)Br]MnBr4 and [Eu(N2O6)]MnBr4 in Example 3 of this invention are shown.

[0021] Figure 5 This is the ellipsoidal model (50% probability) molecular structure of the complex [Ce(N2O6)(H2O)3][Co(CN)6] in Example 4 of this invention. All hydrogen atoms have been omitted, and some representative atoms have been labeled.

[0022] Figure 6 This is the photoluminescence spectrum of the solid powder of the complex [Ce(N2O6)(H2O)3][Co(CN)6] in Example 5 of the present invention.

[0023] Figure 7 This is the emission spectrum of the light-converting LED device using [Eu(N2O6)]MnBr4 as the light-converting material in Embodiment 8 of the present invention (driving current is 6mA).

[0024] Figure 8 These are the a) current-voltage-luminous flux curves and b) lumen efficiency-current-external quantum efficiency curves of the optimal light-converting LED device using [Eu(N2O6)]MnBr4 as the light-converting material (w% = 26%) in Embodiment 8 of the present invention.

[0025] Figure 9 This is the emission spectrum of the [Ce(N2O6)Br]MnBr4 scintillator under X-ray excitation in Embodiment 10 of the present invention. Detailed Implementation

[0026] The following will further illustrate the rare-earth ion-sensitized heteronuclear complexes of the present invention and their application as luminescent materials with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0027] The following will further illustrate the application of the heteronuclear luminescent complex of the present invention as a photoconverter with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0028] The full name of the compound corresponding to the abbreviation:

[0029] N2O6: 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane

[0030] N8: 1,4,7,10,13,16,21,24-octaazabicyclo[8.8.8]hexadecane

[0031] Given that Ce(III) and Eu(II) complexes are theoretically excellent electroluminescent materials, but reports on the luminescence of highly stable Ce(III) and Eu(II) complexes are very rare, the inventors of this invention synthesized a series of rare-earth-manganese heteronuclear luminescent complexes (the structures of the four compounds are shown above) and conducted corresponding research on their photoluminescence and photoconversion devices. The excitation of these complexes mainly originates from the df transition of the central rare-earth ion, and different excitation spectra were obtained by changing the ligand structure and thus altering the ligand field around the rare-earth ion. The distance between the rare-earth ion and the Mn(II) ion is... Within this system, extremely efficient energy transfer can be achieved. Actual research revealed that energy transfer occurs from higher-energy-level excitation centers to lower-energy-level excitation centers. To achieve rare-earth ion sensitization of Mn(II), the energy difference between the 5d and 4f levels of the rare-earth ions must be greater than the lowest excited state energy level of Mn(II). 4 T1(G). Generally, the energy level emission of Ce(III) centers mainly covers the ultraviolet-blue light region, which is sufficient to sensitize Mn(II) that emits red or green light. Eu(II) centers can also achieve efficient sensitization of Mn(II) through ligand selection.

[0032] Reported molecular-level ion sensitization methods include the use of noble metal complexes such as iridium and platinum as antennas to sensitize rare earth trivalent ions such as Eu. 3+ Yb 3+ 、Nd 3+ The antenna metals used in these sensitization systems are precious metals, which are expensive and have low overall efficiency, making them unsuitable for application.

[0033] Currently, there are no reports on rare-earth ion molecular-level sensitization of transition metals. The luminescent material provided in this invention has advantages such as low cost, high energy transfer efficiency, and easily tunable absorption edge, and has a very broad application prospect in the field of photoluminescence. In addition, since the system has a large number of halogen atoms, the absorption rate of the complex material to X-rays can be improved by introducing heavy halogen atoms such as iodine and bromine, which has the potential to be used in the preparation of scintillators.

[0034] Example 1: Preparation and Characterization of the Complex

[0035]

[0036] Synthetic route of the complex [Ce(N8)Br]MnBr4

[0037] Synthesis of Ce(N8)Br3: Cerium tribromide (378.5 mg, 0.997 mmol) and N8 (400 mg, 1.08 mmol) were dissolved separately in 2.5 mL of ultradry methanol in a glove box, and the mixture was stirred overnight. After the reaction was complete, the methanol was removed under reduced pressure. The resulting solid was washed with ultradry acetonitrile (~5 mL), filtered, and the solvent was evaporated to give 579 mg of white powder, yield 77%. Elemental analysis (%) Calculated values: C 18 H 42 Br3CeN8: C 28.81, H 5.64, N 14.93; Measured values: C 29.10, H 5.41, N 14.94.

[0038] Synthesis of [Ce(N8)Br]MnBr4: Ce(N8)Br3 (200.1 mg, 0.267 mmol) was dissolved in 2.5 mL of ultra-dry methanol in a glove box for later use. Manganese dibromide (57.0 mg, 0.265 mmol) was dissolved in 2.5 mL of ultra-dry methanol for later use. The manganese dibromide methanol solution was filtered through a syringe filter (0.22 μm, organic system) and then added to the Ce(N8)Br3 methanol solution. After shaking well, the mixture was allowed to stand to crystallize. After complete crystallization, the crystals were broken up with a scraper, and the solid was washed with redistilled n-hexane (~5 mL), filtered, and the solvent was evaporated to obtain 245 mg of a light yellow-green powder, with a yield of 96%. Elemental analysis (%) Calculated values: C 18 H 42 Br5CeMnN8·CH3OH·H2O: C 22.48, H 4.77, N 11.04; Measured values: C 22.48, H 4.82, N 10.58.

[0039]

[0040] Synthetic route of the complex [Eu(N2O6)]MnBr4

[0041] Synthesis of Eu(N₂O₆)Br₂: N₂O₆ (217.9 mg, 0.579 mmol) was dissolved in 1.0 mL of ultra-dry methanol in a glove box for later use. Europium dibromide (168.9 mg, 0.542 mmol) was dissolved in 2.0 mL of ultra-dry methanol for later use. The europium dibromide methanol solution was filtered through a 0.22 μm syringe filter (organic system) and then added to the N₂O₆ methanol solution. The mixture was stirred overnight. After the reaction was complete, methanol was removed under reduced pressure. The residue was treated with ultra-dry acetonitrile (~1 mL) and the acetonitrile was removed under reduced pressure. The resulting white precipitate was washed with redistilled n-hexane (~5 mL), filtered, and the solvent was evaporated to obtain 310 mg of white powder, yield 83%. Elemental analysis (%) Calculated values: C18 H 36 Br2EuN2O6: C 31.41, H 5.27, N 4.07; Measured values: C 31.26, H 5.38, N 4.04.

[0042] Synthesis of [Eu(N2O6)]MnBr4: Eu(N2O6)Br2 (100.1 mg, 0.145 mmol) was dissolved in 0.8 mL of ultra-dry methanol in a glove box for later use. Manganese dibromide (31.2 mg, 0.145 mmol) was dissolved in 0.6 mL of ultra-dry methanol for later use. The manganese dibromide methanol solution and the Eu(N2O6)Br2 methanol solution were filtered through a 0.22 μm syringe filter (organic system), mixed, shaken well, and allowed to crystallize. After complete crystallization, the crystals were broken up with a scraper, the solid was washed with redistilled n-hexane (~5 mL), filtered, and the solvent was evaporated to obtain 95.7 mg of a light green powder, yield 68%. Elemental analysis (%) Calculated values: C 20 H 44 Br4EuMnN2O6: C 24.84, H 4.59, N 2.90; Measured values: C 24.52, H 4.14, N 3.02.

[0043] Crystal structure of the complex in Example 2

[0044] Single crystals of the complexes [Ce(N8)Br]MnBr4 and [Eu(N2O6)]MnBr4 were obtained by evaporating their methanol or methanol-ethanol mixtures. The single crystals were characterized by X-ray diffraction, and the crystal structure data are listed in Table 1. For detailed crystal structures, please refer to [link to table]. Figure 1 .

[0045] In the complex [Ce(N8)Br]MnBr4, the central Ce 3+ The coordination structure of the ion is a nine-coordinate "hula hoop" configuration, where ligand N8 provides eight nitrogen atom coordination sites, and the last coordination site is Br. - Ions. Due to Ce 3+ The small ionic radius and coordination interactions cause significant distortion of the N8 ligand, affecting its interaction with Br. - The line connecting the two nitrogen atoms in the ion is no longer basically parallel to the line connecting the nitrogen atoms at the bridgehead, but forms a large angle (~60°).

[0046] In the complex [Eu(N2O6)]MnBr4, the central Eu 2+ The ion is decacoordinate, with two nitrogen atom coordination sites and six oxygen atom coordination sites provided by the ligand N₂O₆, and the final two oxygen atom coordination sites provided by two solvent molecules (methanol / ethanol). Eu 2+The relatively large radius of the ion provides a good match with the cavity of the N₂O₆ ligand, resulting in a highly symmetrical four-capped triangular prism coordination structure: two bridgehead nitrogen atoms coordinate from the top and bottom faces of the prism, while two solvent molecules coordinate from the two sides. This solvent coordination increases the overall size of the complex ion [Eu(N₂O₆)]. 2+ The steric hindrance of the [MnBr4] anion makes it possible for the [MnBr4] to be 2- It cannot approach the cation as closely as it does in the complex [Ce(N8)Br]MnBr4, therefore Eu 2+ Center and Mn 2+ The shortest distance to the center is Greater than Ce 3+ Center and Mn 2+ shortest distance from the center

[0047] Table 1. Crystal data of the complexes [Ce(N8)Br]MnBr4 and [Eu(N2O6)]MnBr4

[0048]

[0049] For comparison with the data in Table 1, see attached... Figure 1 This is an ellipsoidal model (50% probability) single-crystal structure of the complexes [Ce(N8)Br]MnBr4(a) and [Eu(N2O6)]MnBr4(b). All hydrogen atoms have been omitted, and some representative atoms have been labeled.

[0050] Example 3: Photophysical properties of rare earth-manganese complexes

[0051] The complexes [Ce(N8)Br]MnBr4 and [Eu(N2O6)]MnBr4 in methanol solution (1×10⁻⁶) -3 The ultraviolet-visible absorption spectrum of M) is as follows Figure 2 As shown, the absorption spectrum of the complex [Ce(N8)Br]MnBr4 has multiple peaks, which can be simply divided into two groups: one is a single peak at 361 nm, and the other is multiple peaks with wavelengths below 300 nm. Both groups of peaks are attributed to Ce. 3+ The absorption spectrum of the central 4f-5d transition is relatively simpler. The main peak is located at 258 nm, and there is a shoulder peak at 318 nm. Similarly, both peaks are attributed to Eu. 2+ The 4f-5d transition absorption at the center.

[0052] Both complexes in methanol solution emit blue light upon ultraviolet excitation, but their emission spectra are significantly different. For example... Figure 3As shown, the emission spectrum of the complex [Ce(N8)Br]MnBr4 exhibits a multi-peak, broad-packed characteristic, with the main peaks at 399 nm, 439 nm, and 500 nm. After Gaussian peak fitting, wavenumbers of 25470 cm⁻¹ were obtained. -1 23760cm -1 22160cm -1 and 19940cm -1 The four peaks. According to Ce 3+ The bimodal emission characteristics of ion df transitions provide a preliminary indication of the presence of Ce in the solution. 3+ The ions may exist in two coordination environments, with their emissions corresponding to two high-energy peaks and two low-energy peaks in the spectrum, respectively. Solution lifetime characterization further supports this hypothesis: the lifetime at 393 nm is 50.2 ns, while the lifetime at 500 nm is 108.0 ns. The emission spectrum of the complex [Eu(N₂O₆)]MnBr₄ is very typical of Eu. 2+ The df transition of the ions exhibits single-peak emission at 468 nm with a lifetime of 395 ns. The excitation spectra of the two complexes are very similar to their respective absorption spectra, indicating that the excitation originates from the df transition of rare-earth ions. The photoluminescence quantum yields (PLQY) of the two complexes in solution are 73% and 42%, respectively. The vibrational quenching effect of solvent molecules on the emission of rare-earth ions is the main factor contributing to the low PLQY.

[0053] Compared to their solution state, the photophysical behavior of the two complexes in the solid state is more unique and interesting. In solution, the anions and cations are separated by solvent molecules and are far apart, with the system mainly exhibiting the properties of the rare-earth central complex ion. However, when the solvent molecules are removed and the anions and cations combine to form crystals, the distance between the rare-earth center and the manganese center is significantly shortened, sufficient for them to interact. Simultaneously, the luminescence of the tetrabromomanganese ion is no longer quenched by solvent molecules, and the system exhibits the photophysical behavior of a synergistic effect between the rare-earth complex ion and the tetrabromomanganese ion. For example... Figure 4 As shown, the emission peaks of both solid complex samples are located in the green region. The main peak of the complex [Ce(N8)Br]MnBr4 is at 523 nm, while that of the complex [Eu(N2O6)]MnBr4 is at 515 nm, with peak lifetimes of 304 μs and 528 μs, respectively. Such emission is typical of Mn in tetrabromomanganese ions. 2+ dd transition ( 4 T1- 6A1) Phosphorescence emission. The change in emission spectrum from solution to solid indicates an energy transfer process from rare earth centers to manganese centers in the solid. Further comparison of the emission spectra reveals that the emission spectrum of the complex [Ce(N8)Br]MnBr4 has a small peak around 410 nm, with energy nearly identical to the high-energy peak emitted from the solution, and a very short lifetime, measured to 1.04 ns after deconvolution fitting. In contrast, the emission spectrum of the complex [Eu(N2O6)]MnBr4 shows no peak in the high-energy region. This phenomenon directly indicates that energy transfer is incomplete in the former, while it is complete in the latter. The excitation spectrum also corroborates this conclusion: in the excitation spectrum of the complex [Ce(N8)Br]MnBr4, the two excitation peaks at 278 nm and 368 nm belong to Ce. 3+ The ion is excited by fd transition, and the excitation peak at 451 nm corresponds to Mn. 2+ The dd transition excitation of the ion itself is essentially of the same order of magnitude. Considering that the fd transition is allowed by the selection law while the dd transition is forbidden by the selection law, this indicates that Ce... 3+ To Mn 2+ The low energy transfer efficiency of the excitation material flattens out the performance of both excitation methods; and in the excitation spectrum of the complex [Eu(N2O6)]MnBr4, only the wavelengths at 291 nm and 367 nm, which belong to Eu, are observed. 2 + The broad peak of the fd transition, without a significant excitation peak around 450 nm, indicates that the energy of the green emission mainly originates from Eu. 2+ The excitation of the center indirectly explains Eu 2+ To Mn 2+ The difference in energy transfer efficiency between the two complexes is ultimately reflected in the difference in their PLQY: the PLQY of [Ce(N8)Br]MnBr4 is 62%, while the PLQY of [Eu(N2O6)]MnBr4 is close to 100%.

[0054] Although [Ce(N8)Br]MnBr4 has slightly lower efficiency, its stability is significantly better than [Eu(N2O6)]MnBr4: the PLQY of the solid powder remained unchanged after being placed in air for more than 15 days, and the methanol solution could also be stored in air for about 1 day. The stability of [Ce(N8)Br]MnBr4 makes its processing and utilization in various applications more convenient and also extends the service life of the material.

[0055] Example 4 Ce III -Co III Synthesis, structure and photophysical properties of heteronuclear complexes

[0056]

[0057] The synthetic route for the complex [Ce(N2O6)(H2O)3][Co(CN)6] is shown above.

[0058] Synthesis of Ce[Co(CN)6]·5H2O: Under light-protected conditions, a solution of cerium trichloride heptahydrate (1.13 g, 3.03 mmol, dissolved in 7 mL of water) was added dropwise to a solution of potassium hexacyanocobalaminate (1.01 g, 3.04 mmol, dissolved in 5 mL of water). After stirring for 3 h, the mixture was filtered, and the precipitate was washed twice each with water, ethanol, and diethyl ether to obtain 911 mg of a white powder, with a yield of 66%. Elemental analysis (%) Calculated values: C6H 10 CeCoN6O5: C 16.19, H 2.26, N 18.88; Measured values: C 16.14, H 2.10, N 19.16.

[0059] Synthesis of [Ce(N2O6)(H2O)3][Co(CN)6]: Under light-protected conditions, Ce[Co(CN)6]·5H2O (106 mg, 0.238 mmol), N2O6 (97 mg, 0.258 mmol), and water (40 mL) were mixed, heated to reflux, and stirred for 24 h. After removing most of the water under reduced pressure, ethanol (20 mL) was added, filtered, and the precipitate was washed twice each with ethanol and diethyl ether to obtain 187 mg of white powder, yield 94%. Elemental analysis (%) Calculated values: C 24 H 42 CeCoN8O9·3H2O: C 34.33, H 5.76, N 13.34; Measured values: C 34.72, H 5.76, N 13.06.

[0060] Single crystals of the complex [Ce(N₂O₆)(H₂O)₃][Co(CN)₆] were obtained by evaporating its aqueous solution. The single crystals were characterized by X-ray diffraction, and the crystal structure data are listed in Table 2. The molecular structure is as follows: Figure 5 As shown. In the complex [Ce(N2O6)(H2O)3][Co(CN)6], the central Ce 3+ The coordination number of the ion is eleven. Besides the two nitrogen atoms and six oxygen atoms provided by the ligand N₂O₆, three water molecules participate in coordination, providing the remaining three oxygen atoms, forming a five-capped triangular prism structure. The crystal has high symmetry; the six cyano groups can interconvert through symmetry operations, interacting with Co. 3+ The coordinate bond lengths formed by the ions are all the same.

[0061] Table 2 Crystal data for the complex [Ce(N2O6)(H2O)3][Co(CN)6]

[0062]

[0063]

[0064] Referring to the crystal structure data in Table 2, Figure 5 An ellipsoidal model (50% probability) molecular structure of the complex [Ce(N₂O₆)(H₂O)₃][Co(CN)₆] is shown. All hydrogen atoms have been omitted, and some representative atoms have been labeled.

[0065] Example 5 Ce III -Co III Photophysical properties of heteronuclear complexes

[0066] The excitation and emission spectra of the solid powder of the complex [Ce(N2O6)(H2O)3][Co(CN)6] are as follows: Figure 6 As shown, its emission exhibits a broad peak characteristic, with a maximum emission wavelength of 684 nm and an emission lifetime of 35.4 μs, significantly different from the 5d-4f emission of Ce(III) complexes, and conforming to the 3d-3d transition emission of Co(III). 3 T1→ 1 The characteristics of A1). The excitation spectrum of the complex shows only a broad band below 400 nm, which can be attributed to the 4f-5d transition absorption of Ce(III) centers and the 3d-3d transition absorption of Co(III) centers. 1 A1→ 1 The combined results of T1). Due to the presence of coordinated water molecules in the complex, the quantum yield of the solid powder of the complex is only 2%.

[0067] Example 6 Characterization of the thermal stability and UV resistance of rare earth-manganese complexes

[0068] The technical effects of this invention are mainly reflected in the emission spectrum, luminescence quantum yield, thermal stability, and UV tolerance of the heteronuclear complexes in the embodiments. The luminescence quantum yield was tested using an integrating sphere; thermal stability was measured by the thermal decomposition temperature obtained from thermogravimetric analysis under N2 atmosphere; and UV tolerance was measured by the attenuation of the luminescence intensity of the rare-earth complex-doped polymer film under UV irradiation. The quantum yield was measured using a C9920-02 integrating sphere absolute photoluminescence quantum yield analyzer manufactured by Hamamatsu Photonics Co., Ltd., Japan. Thermogravimetric analysis was performed using a Q600SDT spectrometer manufactured by TA Instruments, Inc., USA. UV aging was performed using a UVA340 lamp with a power of 40 watts, and the irradiation intensity was 25–30 W / m² during testing.

[0069] The rare earth complexes in this invention have similar complex structures, and their luminescence properties, thermal stability, and UV resistance are also similar. Therefore, in the property characterization of the following examples, only the test results of several representative complexes are listed, as shown in Table 3.

[0070] Table 3. Emission peak, PLQY, decomposition temperature, and UV resistance time of the complexes.

[0071]

[0072] Example 7: Study on the dispersed luminescence properties of [Ce(N8)Br]MnBr4

[0073] The complex [Ce(N8)Br]MnBr4 dispersed in the polymer PMMA is used as a luminescent film.

[0074] The complex [Ce(N8)Br]MnBr4 was doped into a high-molecular-weight PMMA resin at a mass ratio of 15% and dissolved in an acetone / methanol mixture. The resulting mixture was then deposited onto a clean quartz glass surface to form a polymer film.

[0075] The resulting thin film emits a bright green light visible to the naked eye under ultraviolet light. The absolute quantum yield of photoluminescence, measured using an integrating sphere, reaches 65%, making it a highly efficient luminescent material.

[0076] Example 8: Research on [Eu(N2O6)]MnBr4 Optical Transformation Device

[0077] The heteronuclear complex [Eu(N2O6)]MnBr4 shown can be dispersed in commercial silicone sealant and used as a light-converting coating material for light-emitting diodes (LEDs). The photoelectric properties of the resulting light-converting LED device were measured using a C9920-02 integrating sphere absolute external quantum yield tester manufactured by Hamamatsu Photonics Co., Ltd., Japan.

[0078] Commercial silicone sealant components A and B were mixed in a 1:1 mass ratio. Then, the heteronuclear complex [Eu(N₂O₆)]MnBr₄ was incorporated into the silicone sealant at a mass ratio (w%) of 10%-30%, and the mixture was thoroughly mixed. One to two drops of the resulting mixture were coated onto a commercial UV LED chip (405nm, 1W, 3V). The chip was then heated at 150°C for 1 hour to cure the silicone sealant, resulting in a light-converting LED device. Device fabrication and testing were performed inside a nitrogen-filled glove box.

[0079] like Figure 7 As shown, the emission peak of the LED chip gradually decreases with increasing doping concentration. When the doping concentration is 26%, the violet light of the chip is almost completely converted into Mn. 2+The device exhibits green phosphorescence. Lower doping concentrations lead to incomplete light conversion, while higher doping concentrations reduce the light extraction efficiency (Table 4). At the same driving current (6 mA), the external quantum efficiency (EQE) of the converting device and the blank device are 11.6% and 14.0%, respectively. Therefore, the light conversion efficiency is 83%, which is very close to the PLQY (86%) of the complex under 405 nm excitation, indicating that the fabricated device has very high light extraction efficiency.

[0080] Table 4. Photoelectric properties of light-converting LED devices using [Eu(N2O6)]MnBr4 as the light-converting material.

[0081]

[0082] Ultimately, in a fully optically converted device, embodiments of the present invention achieved a luminous efficiency of 52.8 lm / W and an external quantum efficiency of 15.6% (see [link to original text]). Figure 8 (and Table 4). This result fully demonstrates the potential of rare-earth ion-sensitized heteronuclear complexes in optical conversion applications.

[0083] Example 9: Study on electroluminescence properties

[0084] The preparation process employs solution deposition of the hole transport layer and the light-emitting layer, offering the advantage of low cost. This material shows promise as a novel optoelectronic material. The device structure is as follows (ITO—Indium Tin Oxide; PEDOT:PSS—3,4-Ethylenedioxythiophene-polystyrene sulfonate copolymer; TFB—Poly[(9,9-Dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine)]; PVK—Polyvinylcarbazole; TmPyPB—1,3,5-Tris[(3-pyridyl)-phenyl-3-yl]benzene):

[0085] D1:ITO / PEDOT:PSS(45nm) / TFB(30nm) / [Ce(N8)Br]MnBr4(20nm) / TmPyPB(40nm) / LiF / Al

[0086] D2:ITO / PEDOT:PSS(45nm) / TFB(30nm) / PVK:[Ce(N8)Br]MnBr4(3:1,20nm) / TmPyPB(40nm) / LiF / Al

[0087] The main performance parameters of devices D1 to D2 are listed in Table 5. As can be seen from Table 5, the maximum EQE of device D2 is 2.9%, which is higher than that of device D1, while the maximum brightness is comparable, indicating that the carrier transport performance of the main material improves the efficiency of the device.

[0088] Table 5. Performance parameters of OLED devices D1-D2 using [Ce(N8)Br]MnBr4 as the luminescent material

[0089]

[0090] Example 10: Scintillator Performance Study

[0091] The complex [Ce(N2O6)Br]MnBr4 was mixed with sucrose octaacetate at a mass ratio of 0.1%-20%, a small amount of methanol was added to aid dissolution, and the mixture was melted at 160°C and stirred thoroughly. The mixture was then dropped onto a piece of quartz glass and covered with another piece of quartz glass. After cooling and solidification, a sandwich structure scintillator was formed.

[0092] The emission spectrum of the scintillator material under X-ray excitation is as follows: Figure 9 As shown, compared with the other two rare earth complexes (CeL and EuL'), the heteronuclear complex [Ce(N2O6)Br]MnBr4 exhibits significantly stronger emission, with a photon conversion efficiency 7.4 times that of complex CeL and 3.3 times that of complex EuL', fully demonstrating the potential of rare earth ion-sensitized heteronuclear complexes in scintillator applications.

[0093] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A luminescent material, characterized in that, The luminescent material is one of the complexes shown in the following structural formula:

2. A light-emitting film, characterized in that, The luminescent film comprises the luminescent material and the polymer material as described in claim 1, wherein the mass ratio of the luminescent material to the polymer material is 0.1%-60%.

3. A light conversion device, characterized in that, The light conversion device includes a blue-ultraviolet LED chip coated with a light conversion adhesive, wherein the light conversion adhesive includes the luminescent material as described in claim 1 and a silicone sealant, and the luminescent material has a mass percentage content of 1%-50% in the light conversion adhesive.

4. An electroluminescent device, characterized in that, The electroluminescent device includes an indium tin oxide glass substrate and a hole transport layer, a light-emitting layer, an electron transport layer, and a metal electrode sequentially deposited on the indium tin oxide glass substrate by solution deposition; wherein the light-emitting layer contains 1%-50% by mass of the light-emitting material and the host material as described in claim 1.

5. A scintillator, characterized in that, The scintillator comprises a dispersion medium and the luminescent material of claim 1 dispersed therein; the mass percentage of the luminescent material in the scintillator is 0.1%-20%.

6. The light-emitting film according to claim 2, characterized in that, The polymer material is selected from at least one of PMMA, PE, POE, EVA, PS and PDMS.

7. The light-emitting film according to claim 2, characterized in that, The mass ratio of the luminescent material to the polymer material is 1%-20%, and the polymer material is PMMA and / or PS.

8. The optical conversion device according to claim 3, characterized in that, The luminescent material accounts for 15-30% of the mass of the light-converting adhesive.

9. The electroluminescent device according to claim 4, characterized in that, The main material is PVK.

10. The electroluminescent device according to claim 4, characterized in that, The luminescent material accounts for 5-15% of the mass percentage in the luminescent layer.

11. The scintillator according to claim 5, characterized in that, The dispersion medium is sucrose octaacetate.

12. The scintillator according to claim 5, characterized in that, The mass percentage of luminescent material in the scintillator is 1-10%.

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