Long-wave sensitized rare earth complex, preparation method and application thereof

Abstract

The application discloses a long-wave sensitized rare earth complex luminescent material and a preparation method and application thereof. The long-wave sensitized rare earth complex is an ionic rare earth complex based on a dipyrinyl triazine ring ligand, and a structural general formula is (TPy2)Ln(L)3, wherein TPy2 is a dipyrinyl triazine ring neutral ligand; Ln represents a trivalent rare earth ion, including europium, terbium and ytterbium ions; and L represents a negative one valence counter anion, including nitrate anions, halogen anions, acetic acid anions, trifluoroacetic acid anions, trifluoromethane sulfonic acid anions, beta-diketone anions or 4-hydroxy-1,5 naphthylidine anions. The long-wave sensitized rare earth complex can be excited by long-wave near ultraviolet or blue light, the excitation wavelength can be controlled, the long-wave sensitized rare earth complex also has a high efficient photoluminescence quantum yield and good ultraviolet light resistance, and can be used as a photoluminescence material.

Description

Technical Field

[0001] This invention belongs to the field of luminescent materials technology, specifically relating to a long-wavelength sensitized rare-earth complex luminescent material, its preparation method, and its application. Background Technology

[0002] Rare earth ions possess unique luminescent properties such as narrow-band emission, vibrant colors, and high efficiency, making them promising for applications in lighting, displays, signage, light-converting films, and bioimaging. However, rare earth ions themselves have relatively low absorption coefficients and poor luminescence intensity, thus typically requiring a sensitizing matrix to transfer energy. Organic molecules have large molar absorption coefficients; by coordinating rare earth ions with organic ligands, the energy absorbed by the ligands can be effectively transferred to the rare earth ions, significantly increasing their luminescence intensity. Therefore, rare earth complexes are high-performance luminescent materials that have attracted considerable attention and extensive research.

[0003] In the field of fluorescent anti-counterfeiting, rare-earth luminescent materials capable of being excited by long-wavelength near-ultraviolet light (terbium complexes for green light >360nm) or blue-violet light (europium complexes for red light >400nm) are scarce, effectively forming a technological barrier. In the lighting and display fields, lighting and display devices composed of long-wavelength near-ultraviolet chips (e.g., 395nm InGaN chips) paired with full-color phosphors are becoming a research hotspot. Therefore, sensitized rare-earth complex luminescent materials that can be excited by long-wavelength near-ultraviolet or blue light are having increasingly wide-ranging application value.

[0004] In the field of rare-earth luminescent complexes, the sensitization mechanism is typically a triplet pathway. The ligand first absorbs energy to reach the excited singlet state, then undergoes intersystem crossing to reach the excited triplet state. Energy is then transferred from the triplet state to the rare-earth ion, and finally, luminescence is generated by the transition of the central rare-earth ion. Due to the two gradually decreasing energy processes—singlet-triplet intersystem crossing and triplet-rare-earth ion energy transfer—the luminescence of rare-earth complexes exhibits a large Stocks shift. That is, typically only ligands with absorption ranges in the short-wavelength ultraviolet region (absorption peak of red europium complexes <380 nm, absorption peak of green terbium complexes <340 nm) can achieve high-efficiency rare-earth ion-sensitized luminescence. To achieve long-wavelength near-ultraviolet or blue light excitation, the singlet-triplet energy level difference or the triplet-rare-earth ion energy level difference must be reduced. However, considering that the energy transfer process can only be effectively guaranteed when the excited triplet state is above the 2500 wavenumber of the excited state of rare earth ions, regulating the energy level between the excited triplet and excited singlet states of the ligand is an important approach. The idea of ​​reducing the energy level difference between the excited singlet and excited triplet states of the ligand can be drawn upon thermally activated delayed fluorescence (TADF) materials. The design concept of this type of material is that the excited state is usually a charge-transfer state, and through molecular design, the spatial overlap between the highest occupied orbital (HOMO) and lowest unoccupied orbital (LUMO) of the molecule is minimized.

[0005] In 2004, Wang Yuan's team designed and synthesized a novel rare-earth complex, [Eu(tta)3dpbt] (dpbt = 2-(N,N-diethylaniline-4-yl)-4,6-bis(3,5-dimethylpyrazol-1-yl)-1,3,5-triazine, tta being the thiophenecarboxyltrifluoroacetone anion). The dpbt ligand in this complex exhibits a typical structure of TADF materials. The HOMO orbitals are mainly distributed in the electron-donating diethylaminobenzene moiety, while the LUMO orbitals are primarily located in the electron-withdrawing bispyrazolyltriazine structure. The spatial overlap between the HOMO and LUMO orbitals is minimal, resulting in a small energy difference between the singlet and triplet states, enabling long-wavelength (blue-violet) sensitized luminescence of rare-earth europium ions. This complex (in toluene solution, concentration 10) -5 The excitation edge of M is 441 nm, and it has a high luminescence quantum yield (0.52) (Y. Wang, et al., Angew. Chem. Int. Ed. 2004, 43, 5010).

[0006] Common rare earth complexes have large Stokes shifts, making it difficult to excite europium complexes with blue LEDs (400-460nm) or terbium complexes with long-wavelength near-ultraviolet light (360-400nm). Therefore, developing more ligand structures to achieve long-wavelength (defined as 360-400nm ultraviolet light, 400-460nm blue-violet light) sensitization of rare earth complexes is of great significance. Summary of the Invention

[0007] To address the above technical problems, this invention provides a rare earth complex that can be sensitized by long wavelengths and its preparation method. This rare earth complex is based on a dipyridyl triazine ring ligand, which can be excited by near-ultraviolet light (360-400nm) or blue-violet light (400-460nm). This solves the problem of large Stokes shift in traditional rare earth complexes and yields a luminescent material that can effectively sensitize rare earth ions by long wavelengths.

[0008] Specifically, the technical solution of the present invention is as follows:

[0009] A long-wavelength sensitized rare-earth complex, wherein the long-wavelength sensitized rare-earth complex is an ionic rare-earth complex based on a dipyridyltriazine ring ligand, with the general structural formula (TPy2)Ln(L)3, wherein TPy2 is the dipyridyltriazine ring neutral ligand shown in Formula I, Ln represents a trivalent rare-earth ion, and L represents a monovalent counter anion; the structure of the ionic rare-earth complex based on the dipyridyltriazine ring ligand is shown in Formula II.

[0010]

[0011] In Formulas I and II, R1 is a hydrogen atom, methyl, methoxy, methylthio, carbazolyl, 3,6-diphenylcarbazolyl, 3,6-dimethylcarbazolyl, 3,6-di-tert-butylcarbazolyl, dimethylamino, diphenylamino, or 9,9-dimethyl-9,10-dihydroacridyl; R2 and R3 are each independently a hydrogen atom or a methyl group.

[0012] Ln represents trivalent rare earth ions, including europium, terbium, and ytterbium ions;

[0013] L can be a nitrate anion, a halogen anion, an acetate anion, a trifluoroacetic acid anion, a trifluoromethanesulfonic acid anion, a β-diketone anion, or a 4-hydroxy-1,5-naphthidine anion.

[0014] The structures of the β-diketone anion or the 4-hydroxy-1,5-naphthidine anion are shown in Formula III and Formula IV:

[0015]

[0016] In Equations III and IV, R a and R b Each of them is independently phenyl, thienyl, pyridyl, methyl, ethyl, trifluoromethyl, or pentafluoroethyl; R1, R2, R3, R4, and R5 are selected from any one of hydrogen atom, halogen atom, cyano, methyl, ethyl, trifluoromethyl, or pentafluoroethyl;

[0017] Preferably, the β-diketone anion is selected from 2-thiophenecarboxyltrifluoroacetone anion (TTA). - ), dibenzoylmethane anion (DBM) - ), acetylacetone anion (acac) - ) or hexafluoroacetylacetone anion (HFAc) - The structure is as follows:

[0018]

[0019] Preferably, the 4-hydroxy-1,5-naphthidine anion is selected from 4-hydroxy-1,5-naphthidine anion (ND). - ), 3-cyano-4-hydroxy-1,5-naphthidine anion (CND) - ), 3-cyano-4-hydroxy-8-methyl-1,5-naphthidine anion (8mCND) - The structure is as follows:

[0020]

[0021] The present invention also provides a method for preparing the long-wavelength sensitized rare earth complex, namely, the method for preparing the ionic rare earth complex based on the dipyridyl triazine ring ligand is to react the TPy2 type ligand of Formula I with rare earth salts and the negative monovalent counter anion shown by L in a solvent to obtain the ionic rare earth complex shown by Formula II.

[0022] Preferably, the rare earth salts include rare earth halogen salts, nitrates, acetates, trifluoroacetates, and trifluoromethanesulfonates.

[0023] Preferably, the molar ratio of the TPy2-type ligands, rare earth salts, and L-anions in Formula I is 1:1:3, or close to this molar ratio.

[0024] Preferably, the reaction temperature of the preparation method is -10 to 120°C, and the reaction time is 10 minutes to 24 hours.

[0025] Preferably, the solvent is any one of water, methanol, ethanol, isopropanol, acetone, and tetrahydrofuran, or a mixture of two or more of them.

[0026] This invention also provides the application of the long-wavelength sensitized rare earth complex, namely the application of the rare earth complex based on the dipyridyltriazine ring ligand, wherein the rare earth complex is used as a luminescent material in the field of photoluminescence.

[0027] In the field of photoluminescence, the aforementioned long-wavelength sensitized rare-earth complexes can be used as organic phosphors excited by near-ultraviolet light (360-400nm) or blue-violet light (400-460nm). Specific applications include: a) dissolving in solvents such as acetone, toluene, and dichloromethane; b) using in solid form, such as solid powder, or forming a thin film after solvent removal via solution spraying; c) doping into a matrix, such as in inks, ionic liquids, polymer plastics, or other solid materials.

[0028] To achieve long-wavelength near-ultraviolet or blue-violet light excitation, this invention first selects a dipyridyltriazine ring (TPy2) as the main structure, ensuring that the ligand has a clear and strong electron-deficient structure. Simultaneously, the dipyridyltriazine ring can form a stable tridentate coordination structure with rare earth ions. Secondly, electron-donating groups are introduced onto the triazine ring to achieve charge transfer (CT) transitions within the molecule. The energy of the CT transition is controlled by adjusting different electron-donating groups, and the energy difference between the excited singlet and triplet states is adjusted by adjusting the torsion angle. Furthermore, the electron-deficient nature of the electron-deficient portion is modulated by using counter anions with different inductive abilities, thereby controlling the CT transition energy. Finally, dispersing the complex in media of different polarities, such as solutions, thin films, or their solid states, also allows for the control of its energy levels and luminescence efficiency.

[0029] The energy levels of the dipyridyltriazine ring (TPy2) ligands described in this invention vary with the electron-donating group R1, ranging from 23866 to 16556 wavenumbers. Some ligands with energy levels higher than 19760 wavenumbers can sensitize Eu. 3+ Ions (wavenumber 17260) emit bright red light, and those with higher energy levels can also sensitize Tb. 3+ Ions (20400 wavenumber) emit green light, reacting with low-energy Yb 3+ Ion coordination (at a wavenumber of 10,000) can produce infrared emission. Therefore, the rare earth complexes described in this invention can produce characteristic luminescence of different colors, making them a type of material with practical value and development prospects.

[0030] The rare earth complexes described in this invention have the following advantages and beneficial effects: (1) The electron-donating groups in the ligands have a wide range of selection. By adjusting different electron-donating groups to control the energy of the CT transition, the energy level of the complex can be adjusted, thereby achieving absorption from long-wave near-ultraviolet to visible blue light; (2) By adjusting the torsion angle of the donor unit and the acceptor unit, the energy levels of the excited singlet and excited triplet states can be adjusted, thereby achieving regulation of the absorption range and luminescence efficiency of the rare earth complexes; (3) By selecting appropriate molecular structures and adjusting suitable triplet energy levels, long-wave near-ultraviolet (360-400nm) sensitized terbium ion luminescence and blue-violet (400-460nm) sensitized europium ion luminescence can be achieved, with longer absorption sides and high luminescence efficiency. Attached Figure Description

[0031] Figure 1 The rare earth europium complex dichloromethane solution (1×10⁻⁶) shown in formulas II-1, II-2, II-3, II-4, II-5, and II-6 in Examples 6-11 of this invention. -5 The excitation spectrum of M (detection wavelength 616 nm).

[0032] Figure 2 The rare earth europium complex dichloromethane solution (1×10⁻⁶) of formulas II-1, II-2, II-3, II-4, II-5, and II-6, as measured in Examples 6-11 of this invention, is... -5 The emission spectrum of M).

[0033] Figure 3 The rare earth europium complex toluene solution (1×10⁻⁶) shown in formulas II-7, II-8, II-9, II-10 and II-11 in Examples 12-16 of this invention. -5 The excitation spectrum of M (detection wavelength 616 nm).

[0034] Figure 4 The rare earth europium complex toluene solution (1×10⁻⁶) shown in formulas II-7, II-8, II-9, II-10 and II-11 in Examples 12-16 of this invention. -5 The emission spectrum of M).

[0035] Figure 5 These are the emission spectra of rare earth terbium complexes of formulas II-12 and II-13 and shown in examples 18 and 19 of this invention in polymethyl methacrylate (PMMA).

[0036] Figure 6 The emission spectrum (excitation wavelength 450 nm) of the toluene solution of the rare earth ytterbium complex of Formula II-18 was measured in Example 20 of this invention. Detailed Implementation

[0037] The following specific embodiments further illustrate the products, preparation methods, and applications of the present invention, but these specific embodiments do not limit the scope of protection of the present invention in any way.

[0038] The rare earth complexes of this invention are prepared by reacting TPy2 ligands, rare earth salts, and counter anionic salts in an organic solvent. The TPy2 ligands are shown in Formula I. The synthesis method of the naphthidine ligands can be found in CN201110139842.1, and other reagents are commercially available.

[0039] <Synthesis of Different Ligands>

[0040] Example 1. Synthesizing the ligand shown in Formula I-1 (i.e., R1 = R2 = R3 = H in Formula I)

[0041]

[0042] Add 150 mL of anhydrous diethyl ether to a round-bottom flask to replace the gas in the flask with N2. Add 8.3 mL of 2 M HNMe2 (16.5 mmol, 1.1 eq) tetrahydrofuran solution, then slowly add 10.3 mL of 1.6 M n-butyllithium (16.5 mmol, 1.1 eq) n-hexane solution. A white solid precipitates, and the mixture is stirred at room temperature for 20 min. Add 1.55 g of benzonitrile solid (15 mmol, 1.0 eq) under N2 purging, and the solution turns bright yellow. Stir at room temperature for 30 min. The solution turns pale green with a solid suspension. Add 3.13 g of liquid 2-cyanopyridine (30.0 mmol) under N2 purging, and stir overnight at room temperature. A large amount of white solid precipitates during this process. Dilute with 100 mL of a water:ethanol = 1:1 (v / v) mixture, remove the diethyl ether using a rotary evaporator, add 75 mL of n-hexane, and stir again overnight. After filtration, washing with a 1:1 (v / v) mixture of water and ethanol (10 mL × 2) and n-hexane (20 mL × 2), and drying, 2.96 g of the white target ligand was obtained. ¹H NMR (400 MHz, CDCl₃) showed δ 8.97 (d, J = 4.0 Hz, 2H), 8.91–8.74 (m, 4H), 7.98 (td, J = 7.8, 1.6 Hz, 2H), 7.70–7.49 (m, 5H). ESI-MS analysis revealed a molecular ion peak at M / Z = 312.1, [M+H]. + .

[0043] Example 2. Synthesis of the ligand shown in Formula I-2 (i.e., R1 = methoxy, R2 = R3 = H in Formula I)

[0044]

[0045] The synthesis procedure was the same as in Example 1, except that benzonitrile was replaced with p-methoxybenzonitrile (1.33 g, 10 mmol, 1.0 eq), the HNMe2 tetrahydrofuran solution and n-butyllithium n-hexane solution were 1.1 eq, and 2-cyanopyridine was 2.0 eq, yielding 1.37 g of a pale yellow solid, with a yield of 40.1%. ¹H NMR (400 MHz, CDCl3): δ 9.05 (d, J = 4.5 Hz, 2H), 8.97 (d, J = 7.8 Hz, 2H), 8.90 (d, J = 8.8 Hz, 2H), 8.10 (t, J = 7.6 Hz, 2H), 7.69–7.60 (m, 2H), 7.09 (d, J = 9.0 Hz, 2H), 3.94 (s, 3H). Mass spectrometry (ESI-MS) analysis revealed a molecular ion peak with an M / Z ratio of 342.1, [M+H]. + M / Z = 364.1, [M + Na] + .

[0046] Example 3. Synthesis of the ligand shown in Formula I-3 (i.e., R1 = carbazole group, R2 = R3 = H in Formula II)

[0047]

[0048] The synthesis procedure was the same as in Example 1, except that benzonitrile was replaced with 4-carbazolebenzonitrile (2.68 g, 10 mmol, 1.0 eq) (4-carbazolebenzonitrile was synthesized from p-fluorobenzonitrile and carbazole at high temperature in the presence of a base), the HNMe2 tetrahydrofuran solution and n-butyllithium n-hexane solution were 1.1 eq, and 2-cyanopyridine was 2.0 eq, yielding 3.74 g of white solid, with a yield of 78.6%. ¹H NMR (400 MHz, CDCl₃) δ 9.10–9.03 (m, 2H), 8.99 (ddd, J = 4.8, 1.8, 0.9 Hz, 2H), 8.87 (dt, J = 8.0, 1.0 Hz, 2H), 8.17 (dd, J = 7.8, 1.1 Hz, 2H), 8.00 (td, J = 7.8, 1.7 Hz, 2H), 7.88–7.80 (m, 2H), 7.62–7.52 (m, 4H), 7.46 (ddd, J = 8.2, 7.1, 1.2 Hz, 2H), 7.39–7.30 (m, 2H). ESI-MS analysis revealed a molecular ion peak at M / Z = 477.2, [M+H]. + M / Z = 499.2, [M + Na] + .

[0049] Example 4. Synthesis of the ligand shown in Formula I-4 (i.e., R1 = carbazole group, R2 = CH3, R3 = H in Formula I)

[0050]

[0051] The synthesis procedure was the same as in Example 1, except that benzonitrile was replaced with 4-(9-carbazolyl)-3-methylbenzonitrile (2.82 g, 10 mmol, 1.0 eq). (4-(9-carbazolyl)-3-methylbenzonitrile was synthesized from 4-fluoro-3-methylbenzonitrile and carbazole at high temperature in the presence of a base). The concentrations of HNMe2 tetrahydrofuran solution and n-butyllithium n-hexane solution were 1.1 eq, and the concentration of 2-cyanopyridine was 2.0 eq. 4.14 g of a pale yellow solid was obtained, with a yield of 84.5%. ¹H NMR (400MHz, CDCl₃) δ 9.01–8.97 (m, 2H), 8.91 (d, J = 2.0Hz, 1H), 8.88 (dd, J = 7.9, 1.4Hz, 2H), 8.83 (dd, J = 8.2, 2.0Hz, 1H), 8.19 (d, J = 7.7Hz, 2H), 8.00 (td, J = 7.8, 1.8Hz, 2H), 7.63–7.53 (m, 3H), 7.43 (ddd, J = 8.2, 7.2, 1.2Hz, 2H), 7.36–7.29 (m, 2H), 7.10 (d, J = 8.2Hz, 2H), 2.17 (s, 3H). ESI-MS analysis revealed a molecular ion peak M / Z = 491.2, [M+H]. + .

[0052] Example 5. Synthesis of the ligand shown in Formula I-5 (i.e., R1 = 3,6-di-tert-butylcarbazole, R2 = R3 = H in Formula I)

[0053]

[0054] The synthesis procedure was the same as in Example 1, except that benzonitrile was replaced with 4-(3,6-di-tert-butylcarbazole)benzonitrile (3.04 g, 8 mmol, 1.0 eq). (4-(3,6-di-tert-butylcarbazole)benzonitrile was synthesized from 4-fluorobenzonitrile and 3,6-di-tert-butylcarbazole at high temperature in the presence of a base). The concentrations of HNMe2 tetrahydrofuran solution and n-butyllithium n-hexane solution were 1.1 eq, and the concentration of 2-cyanopyridine was 2.0 eq. 4.78 g of a pale yellow solid was obtained, with a yield of 100%. ¹H NMR (400MHz, CDCl₃) δ 9.05–9.01 (m, 2H), 8.98 (ddd, J = 4.7, 1.7, 0.9Hz, 2H), 8.89 (dt, J = 7.9, 1.1Hz, 2H), 8.16 (t, J = 1.3Hz, 2H), 8.00 (td, J = 7.7, 1.8Hz, 2H), 7.86–7.80 (m, 2H), 7.57 (ddd, J = 7.6, 4.7, 1.2Hz, 2H), 7.51 (d, J = 1.3Hz, 4H), 1.49 (s, 18H). ESI-MS analysis revealed a molecular ion peak M / Z = 589.3, [M+H].+ .

[0055] Synthesis of Rare Earth Complexes with Different Ligands

[0056] Example 6. Synthesis of rare earth complexes as shown in Formula II-1 (i.e., R1 = CH3, R2 = R3 = H, Ln = Eu, L = NO3 in Formula II) - )

[0057]

[0058] 1 mmol of MePhTPy2 (i.e., R1 = CH3, R2 = R3 = H in Formula I) and 1 mmol of europium nitrate hexahydrate were heated under reflux in an ethanol solution for 1 hour. After filtration, the mixture was washed with a small amount of ethanol and dried under vacuum. Recrystallization from ethanol yielded 0.47 g of the grayish-white europium complex.

[0059] Mass spectrometry (ESI-MS) analysis revealed a molecular ion peak with M / Z = 602.1, [M-NO3]. + Elemental analysis (mass percentage): C, 34.72 (34.35); H, 2.87 (2.74); N, 15.84 (16.02), with theoretical values ​​in parentheses. The complex shown in Formula II-1, dissolved in dichloromethane or in solid powder form, exhibits bright red light emission under UV excitation. The excitation spectrum of its dichloromethane solution (detection wavelength 616 nm) is as follows... Figure 1 As shown, the emission spectrum (excitation wavelength 360 nm) is as follows: Figure 2 As shown. Figure 1 It can be seen that the excitation wavelength range of the complex shown in Formula II-1 is 300-360 nm. Figure 2 The emission spectrum shows only emission from the central europium ion (no ligand emission), indicating that the ligand has good coordination with the rare earth ion (no obvious dissociation) and can transfer energy efficiently.

[0060] Example 7. Synthesis of rare earth complexes as shown in Formula II-2 (i.e., R1 = methoxy, R2 = R3 = H, Ln = Eu, L = NO3 in Formula II) - )

[0061]

[0062] The synthesis steps were the same as in Example 6, except that the ligand was replaced with MeOPhTPy2 (i.e., R1 = methoxy, R2 = R3 = H in Formula I). ​​0.41 g of the pale yellow target europium complex was obtained. Elemental analysis (mass percentage %): C, 34.72 (34.45); H, 2.56 (2.46); N, 15.94 (16.07), with theoretical values ​​in parentheses. The complex shown in Formula II-2, dissolved in dichloromethane or in solid powder form, exhibits bright red light emission under UV excitation. The excitation spectrum of its dichloromethane solution (detection wavelength 616 nm) is shown below. Figure 1 As shown, the emission spectrum (excitation wavelength 390 nm) is as follows: Figure 2 As shown. Figure 1 It can be seen that the excitation wavelength range of the complex shown in Formula II-2 is 300-400 nm. Figure 2 The emission spectrum shows only emission from the central europium ion (no ligand emission), indicating that the ligand has good coordination with the rare earth ion (no obvious dissociation) and can transfer energy efficiently.

[0063] Example 8. Synthesis of rare earth complexes as shown in Formula II-3 (i.e., R1 = methylthio, R2 = R3 = H, Ln = Eu, L = NO3 in Formula II) - )

[0064]

[0065] The synthesis procedure was the same as in Example 6, except that the ligand was replaced with MeSPhTPy2 (i.e., R1 = methylthio, R2 = R3 = H in Formula I). ​​0.33 g of the target europium complex as a yellow solid was obtained. Mass spectrometry (ESI-MS) analysis revealed a molecular ion peak at M / Z = 634.0, [M-NO3]. + Elemental analysis (mass percentage): C, 33.57 (33.67); H, 2.62 (2.40); N, 15.55 (15.71), with theoretical values ​​in parentheses. The complex shown in Formula II-3, dissolved in dichloromethane or in solid powder form, exhibits bright red light emission under blue LED excitation. The excitation spectrum of its dichloromethane solution (detection wavelength 616 nm) is as follows... Figure 1 As shown, the emission spectrum (excitation wavelength 425 nm) is as follows: Figure 2 As shown. Figure 1 It can be seen that the excitation wavelength range of the complex shown in Formula II-3 is 300-430 nm. Figure 2 The emission spectrum shows only emission from the central europium ion (no ligand emission), indicating that the ligand has good coordination with the rare earth ion (no obvious dissociation) and can transfer energy efficiently.

[0066] Example 9. Synthesis of rare earth complexes as shown in Formula II-4 (i.e., R1 = carbazole group, R2 = R3 = H, Ln = Eu, L = NO3 in Formula II) - )

[0067]

[0068] The synthesis procedure was the same as in Example 6, except that the ligand was replaced with CzPhTPy2 (i.e., R1 = carbazole group, R2 = R3 = H in Formula I). ​​0.60 g of the target europium complex orange-yellow powder was obtained. Mass spectrometry (ESI-MS) analysis revealed a molecular ion peak M / Z = 753.1, [M-NO3]. + Elemental analysis (mass percentage): C, 44.98 (44.72); H, 2.71 (2.66); N, 14.84 (15.14), with theoretical values ​​in parentheses. The complex shown in Formula II-4, dissolved in toluene or in solid powder form, emits bright red light upon excitation by a blue LED. The excitation spectrum of its toluene solution (detection wavelength 616 nm) is as follows... Figure 1 As shown, the emission spectrum (excitation wavelength 450 nm) is as follows: Figure 2 As shown. Figure 1 It can be seen that the excitation wavelength range of the complex shown in Formula II-4 is 300-470 nm. Figure 2 The emission spectrum shows only emission from the central europium ion (no ligand emission), indicating that the ligand has good coordination with the rare earth ion (no obvious dissociation) and can transfer energy efficiently.

[0069] Example 10. Synthesis of rare earth complexes shown in Formula II-5 (i.e., R1 = carbazole group, R2 = CH3, R3 = H, Ln = Eu, L = NO3 in Formula II) - )

[0070]

[0071] The synthesis procedure was the same as in Example 6, except that the ligand was replaced with CzMePhTPy2 (i.e., R1 = carbazole group, R2 = CH3, R3 = H in Formula I). ​​0.63 g of the target europium complex yellow powder was obtained. Mass spectrometry (ESI-MS) analysis revealed a molecular ion peak M / Z = 767.1, [M-NO3]. + Elemental analysis (mass percentage): C, 46.50 (46.69); H, 3.10 (3.23); N, 14.54 (14.41), with theoretical values ​​in parentheses. The complex shown in Formula II-5, dissolved in toluene or in solid powder form, emits bright red light upon excitation by a blue LED. The excitation spectrum of its toluene solution (detection wavelength 616 nm) is as follows... Figure 1As shown, the emission spectrum (excitation wavelength 450 nm) is as follows: Figure 2 As shown. Figure 1 It can be seen that the excitation wavelength range of the complex shown in Formula II-5 is 300-460 nm. Figure 2 The emission spectrum shows only emission from the central europium ion (no ligand emission), indicating that the ligand has good coordination with the rare earth ion (no obvious dissociation) and can transfer energy efficiently.

[0072] Example 11. Synthesis of rare earth complexes as shown in Formula II-6 (i.e., R1 = carbazole group, R2 = R3 = CH3, Ln = Eu, L = NO3 in Formula II) - )

[0073]

[0074] The synthesis procedure was the same as in Example 6, except that the ligand was replaced with CzDMePhTPy2 (i.e., R1 = carbazole group, R2 = R3 = CH3 in Formula I). ​​0.61 g of the target europium complex orange-red powder was obtained. Mass spectrometry (ESI-MS) analysis revealed a molecular ion peak M / Z = 781.1, [M-NO3]. + Elemental analysis (mass percentage): C, 45.81 (45.58); H, 3.16 (3.13); N, 14.31 (14.50), with theoretical values ​​in parentheses. The complex shown in Formula II-6, dissolved in toluene or in solid powder form, emits bright red light upon excitation by a blue LED. The excitation spectrum of its toluene solution (detection wavelength 616 nm) is as follows. Figure 1 As shown, the emission spectrum (excitation wavelength 450 nm) is as follows: Figure 2 As shown. Figure 1 It can be seen that the excitation wavelength range of the complex shown in Formula II-6 is 300-450 nm. Figure 2 The emission spectrum shows only emission from the central europium ion (no ligand emission), indicating that the ligand has good coordination with the rare earth ion (no obvious dissociation) and can transfer energy efficiently.

[0075] Table 1 shows the absorption spectra, singlet and triplet energy levels of the europium complexes in Examples 6-11 in solution.

[0076] Table 1

[0077]

[0078] λ abs Indicates the absorption peak value (in nanometers), [ε(M -1 cm -1 E represents the molar absorptivity (unit: liters / mol / cm). grepresents the singlet energy level (estimated from the absorption edge, unit: wavenumber), E T represents the triplet energy level (measured from low-temperature phosphorescence spectroscopy of the corresponding gadolinium complex, unit: wavenumber), ΔE ST represents the energy difference between the singlet and triplet states (unit: wavenumber).

[0079] It can be seen from Table 1 that as the electron-donating property of the R1 substituent increases, the peak position of the CT transition of the ligand shifts to longer wavelengths (320-432 nm), in the order of pMePh-Eu < MeO-Eu < MeS-Eu < CzPh-Eu; on the other hand, when the R1 position is all a carbazole group, as the R2 and R3 positions become methyl-substituted, the electron-donating carbazole group cannot easily become coplanar with the benzene-triazine ring, which also weakens the CT transition and shifts the absorption peak to shorter wavelengths (432-415 nm). That is, by using different substituents and adjusting the torsion angle between the donor unit and the acceptor unit, the absorption wavelength of the compound in the technical solution of the present invention can be conveniently regulated.

[0080] Table 2 Photoluminescence quantum yield (PLQY) of the europium complexes of Examples 6-11 in solution state

[0081]

[0082] a: dichloromethane solution (1×10 -5 M); b: toluene solution (1×10 -5 M). The quantum yield was measured by the absolute method, and the instrument used was the C9920-02 absolute luminescence quantum yield testing system from Hamamatsu.

[0083] Table 2 shows the photoluminescence quantum yield (PLQY) of the europium complexes of Examples 6-11 in solution state. It can be seen from the test results of luminescence quantum yield in Table 2 that by selecting appropriate substituents, the excitation wavelength of the rare earth complex of the present invention can be conveniently regulated. When the singlet and triplet energy levels are adjusted to appropriate values, near-ultraviolet (360-400 nm) excitation of red-emitting europium complexes can be achieved. The europium complexes represented by Formulas II-1, II-2 and II-3 can emit bright red light under 330-395 nm near-ultraviolet excitation, and the luminescence efficiency in solution state reaches 29-45%.

[0084] When the R1 position is adjusted to a carbazole group, due to the enhanced electron-donating property, the CT transition absorption can be red-shifted to 450 nm. Moreover, since carbazole and the triazine group are not coplanar, the triplet energy level is not significantly reduced. Therefore, under 450 nm blue light excitation, the luminescence quantum yield of the europium complexes represented by Formulas II-4, II-5 and II-6 in solution state can still reach 30-44%, realizing high-efficiency red light emission excited by blue light.

[0085] <Modifying the Synthesis of Rare Earth Complexes that Counteract Anions>

[0086] Example 12. Synthesis of the rare earth complex shown in Formula II-7 (CzPh-TTA-Ln, i.e., R1 = carbazole group, R2 = R3 = H, Ln = Eu, L = TTA)

[0087]

[0088] 1 mmol of CzPhTPy2 (i.e., R1 = Cz, R2 = R3 = H in Formula I) and 1 mmol of europium chloride hexahydrate were heated under reflux in ethanol solution for 15 minutes. 3 mmol of sodium 2-thiophenecarboxylic acid trifluoroacetone was added, and the mixture was heated under reflux for 1 hour. After filtration, the mixture was washed with a small amount of ethanol and water, and then dried under vacuum. Recrystallization from ethanol yielded 0.953 g of the orange-yellow target europium complex. Elemental analysis (mass percentage): C, 51.10 (51.13); H, 2.59 (2.50); ​​N, 6.58 (6.50), with theoretical values ​​in parentheses. The complex shown in Formula II-7, dissolved in toluene or in solid powder form, emitted bright red light under blue LED excitation. The excitation spectrum of its toluene solution (detection wavelength 616 nm) is shown below. Figure 3 As shown, the emission spectrum (excitation wavelength 450 nm) is as follows: Figure 4 As shown. Figure 3 It can be seen that the excitation wavelength range of the complex shown in Formula II-7 is 300-450 nm. Figure 4 The emission spectrum shows only emission from the central europium ion (no ligand emission), indicating that the ligand has good coordination with the rare earth ion (no obvious dissociation) and can transfer energy efficiently.

[0089] Example 13. Synthesis of the rare earth complex shown in Formula II-8 (CzMePh-TTA-Ln, i.e., R1 = carbazole group, R2 = CH3, R3 = H, Ln = Eu, L = TTA)

[0090]

[0091] The synthesis steps were the same as in Example 12, except that the ligand was replaced with CzMePhTPy2 (i.e., R1 = carbazole group, R2 = CH3, R3 = H in Formula I). ​​0.98 g of the target europium complex orange-red powder was obtained. Elemental analysis (mass percentage %): C, 51.48 (51.29); H, 2.63 (2.61); N, 6.44 (6.41), with theoretical values ​​in parentheses. The complex shown in Formula II-8, dissolved in toluene or in solid powder form, emitted bright red light under blue LED excitation. The excitation spectrum of its toluene solution (detection wavelength 616 nm) is as follows... Figure 3 As shown, the emission spectrum (excitation wavelength 450 nm) is as follows: Figure 4 As shown. Figure 3 It can be seen that the excitation wavelength range of the complex shown in Formula II-8 is 300-435 nm. Figure 4 The emission spectrum shows only emission from the central europium ion (no ligand emission), indicating that the ligand has good coordination with the rare earth ion (no obvious dissociation) and can transfer energy efficiently.

[0092] Example 14. Synthesis of the rare earth complex shown in Formula II-9 (CzDMePh-TTA-Ln, i.e., R1 = carbazole group, R2 = R3 = CH3, Ln = Eu, L = TTA)

[0093]

[0094] The synthesis steps were the same as in Example 12, except that the ligand was replaced with CzDMePhTPy2 (i.e., R1 = carbazole group, R2 = R3 = CH3 in Formula I). ​​1.186 g of the target europium complex orange-red powder was obtained. Elemental analysis (mass percentage %): C, 51.89 (51.86); H, 2.91 (2.75); N, 6.36 (6.37), with theoretical values ​​in parentheses. The complex shown in Formula II-9, dissolved in toluene or in solid powder form, emitted bright red light under blue LED excitation. The excitation spectrum of its toluene solution (detection wavelength 616 nm) is shown below. Figure 3 As shown, the emission spectrum (excitation wavelength 450 nm) is as follows: Figure 4 As shown. Figure 3 It can be seen that the excitation wavelength range of the complex shown in Formula II-9 is 300-425 nm. Figure 4 The emission spectrum shows only emission from the central europium ion (no ligand emission), indicating that the ligand has good coordination with the rare earth ion (no obvious dissociation) and can transfer energy efficiently.

[0095] Example 15. Synthesis of the rare earth complex shown in Formula II-10 (tBuCzPh-TTA-Ln, i.e., R1 = 3,6-di-tert-butylcarbazole, R2 = R3 = H, Ln = Eu, L = TTA)

[0096]

[0097] The synthesis steps were the same as in Example 12, except that the ligand was replaced with tBuCzPhTPy2 (i.e., R1 = dimethylamino, R2 = R3 = H in Formula I). ​​0.951 g of the target europium complex orange-red powder was obtained. Elemental analysis (mass percentage %): C, 53.72 (53.89); H, 3.49 (3.45); N, 5.91 (5.98), with theoretical values ​​in parentheses. The complex shown in Formula II-10, dissolved in toluene or in solid powder form, emitted bright red light under blue LED excitation. The excitation spectrum of its toluene solution (detection wavelength 616 nm) is shown below. Figure 3 As shown, the emission spectrum (excitation wavelength 450 nm) is as follows: Figure 4 As shown. Figure 3 It can be seen that the excitation wavelength range of the complex shown in Formula II-10 is 300-470 nm. Figure 4 The emission spectrum shows only emission from the central europium ion (no ligand emission), indicating that the ligand has good coordination with the rare earth ion (no obvious dissociation) and can transfer energy efficiently.

[0098] Example 16. Synthesis of the rare earth complex shown in Formula II-11 (i.e., R1 = dimethylamino, R2 = R3 = H, Ln = Eu, L = TTA in Formula II)

[0099]

[0100] The synthesis steps were the same as in Example 12, except that the ligand was replaced with Me2NPhTPy2 (i.e., R1 = dimethylamino, R2 = R3 = H in Formula I). ​​0.951 g of the target europium complex orange-red powder was obtained. Elemental analysis (mass percentage %): C, 53.72 (53.89); H, 3.49 (3.45); N, 5.91 (5.98), with theoretical values ​​in parentheses. The complex shown in Formula II-11, dissolved in toluene or in solid powder form, emitted bright red light under blue LED excitation. The excitation spectrum of its toluene solution (detection wavelength 616 nm) is shown below. Figure 3 As shown, the emission spectrum (excitation wavelength 450 nm) is as follows: Figure 4 As shown. Figure 3 It can be seen that the excitation wavelength range of the complex shown in Formula II-7 is 300-460 nm. Figure 4The emission spectrum shows only emission from the central europium ion (no ligand emission), indicating that the ligand has good coordination with the rare earth ion (no obvious dissociation).

[0101] Example 17. Synthesis of the rare earth complex shown in Formula II-11 (tBuCzPh-ND-Ln, i.e., R1 = 3,6-di-tert-butylcarbazole, R2 = R3 = H, Ln = Eu, L = 8mCND)

[0102]

[0103] The synthesis steps are the same as in Example 12, except that the neutral ligand is replaced with tBuCzPhTPy2 (i.e., R1 = 3,6-di-tert-butylcarbazole, R2 = R3 = H in Formula I), and the anionic ligand is replaced with sodium 3-cyano-4-hydroxy-8-methyl-1,5-naphthidine (8mCND). - 0.911 g of the target europium complex orange-red powder was obtained. Elemental analysis (mass percentage %): C, 63.92 (64.08); H, 4.49 (4.21); N, 16.21 (16.25), with theoretical values ​​in parentheses. The complex shown in Formula II-11, dissolved in toluene or in solid powder form, emits bright red light upon excitation by a blue LED. PLQY (solid): 48.2% (450 nm excitation).

[0104] Table 3. Quantum efficiency (PLQY) of europium complex solids in Examples 12-16 under different wavelength excitations.

[0105]

[0106] Note: Quantum yield was measured using the absolute method, and the instrument used was the Hamamatsu C9920-02 absolute luminescent quantum yield testing system.

[0107] Table 3 shows the quantum efficiency (PLQY) of the europium complex solids in Examples 12-16 under different wavelength excitations. As can be seen from the luminescence quantum efficiency test results in Table 3, the luminescence efficiency of the rare earth complexes of this invention can be improved and optimized by selecting appropriate counter anion ligands. The europium complexes shown in Formulas II-7, II-8, II-9, and II-10 are based on cases where the R1 position has a carbazole group, and the counter anion is changed from nitrate ion to 2-thiophenecarboxyltrifluoroacetone anion (TTA). - Due to the adjustment of the counter anion, the electron-deficient properties of the centrally electron-deficient rare-earth europium ion are weakened (nitrate is a strong electron-withdrawing group, TTA). -The ions have a certain electron-donating property, and the CT transition from the electron-donating carbazole group to the central electron-deficient site is suppressed to a certain extent, which increases the triplet energy level, so the luminescence efficiency is further improved to 30-82%.

[0108] Especially for formulas II-8 and II-9, due to the steric hindrance effect of methyl substitution at the R2 and R3 positions, a twisted structure exists in the ligand, ΔE ST The energy difference between the singlet and triplet states is relatively small, and the triplet state can remain at a higher energy level, thus effectively sensitizing europium ion luminescence. Even under blue light excitation at 450-475 nm, it can emit bright red light, achieving a solid-state luminescence efficiency of 64-82%.

[0109] Synthesis of rare earth complexes with different rare earth ions

[0110] Example 18. Synthesis of rare earth complexes as shown in Formula II-12 (i.e., R1 = CH3, R2 = R3 = H, Ln = Tb, L = NO3 in Formula II)

[0111]

[0112]

[0113] The synthesis procedure was the same as in Example 6, except that europium chloride hexahydrate was replaced with terbium chloride hexahydrate. 0.52 g of the grayish-white target terbium complex was obtained. Mass spectrometry (ESI-MS) analysis revealed a molecular ion peak at M / Z = 608.0, [M-NO3]. + Elemental analysis (mass percentage): C, 34.14 (34.10); H, 2.77 (2.71); N, 15.89 (15.86), with theoretical values ​​in parentheses. The complex shown in Formula II-12, dissolved in toluene or in solid powder form, exhibits bright green light emission upon excitation by a UV lamp. The emission spectrum of its PMMA film (excitation wavelength 360 nm) is as follows... Figure 5 As shown. From Figure 5 As can be seen, the emission spectrum of the complex shown in Formula II-12 only shows emission of the central terbium ion (no ligand emission), indicating that the ligand has good coordination with the rare earth ion (no obvious dissociation) and can transfer energy efficiently.

[0114] Example 19. Synthesis of the rare earth complex shown in Formula II-13 (i.e., R1 = methoxy, R2 = R3 = H, Ln = Tb, L = NO3 in Formula II)

[0115]

[0116] The synthesis steps were the same as in Example 7, except that europium chloride hexahydrate was replaced with terbium chloride hexahydrate. 0.40 g of the pale yellow target terbium complex was obtained. Elemental analysis (mass percentage %): C, 34.02 (33.84); H, 2.92 (2.98); N, 15.28 (15.03), with theoretical values ​​in parentheses. The complex shown in Formula II-13, dissolved in toluene or in solid powder form, exhibits bright green light emission under UV excitation. The emission spectrum of its PMMA film (excitation wavelength 390 nm) is as follows... Figure 5 As shown. From Figure 5 As can be seen, the emission spectrum of the complex shown in Formula II-13 only shows emission of the central terbium ion (no ligand emission), indicating that the ligand has good coordination with the rare earth ion (no obvious dissociation) and can transfer energy efficiently.

[0117] Table 4. Quantum yields of the complexes in solution from the examples.

[0118]

[0119] Note: Quantum yield was measured using the absolute method, and the instrument used was the Hamamatsu C9920-02 absolute luminescent quantum yield testing system.

[0120] Table 4 shows the quantum yields of the complexes from Examples 18 and 19 in solution. The luminescence quantum efficiency test results in Table 4 show that by changing the central rare-earth ion, the technical solution of this invention can achieve luminescence in various colors. Formulas II-12 and II-13 use two high-energy dipyridyltriazine ligands (methyl and methoxy at R1 positions, respectively), which can sensitize terbium ions to produce bright green light emission. Under 330 nm excitation, the luminescence quantum efficiency can reach a maximum of 81%.

[0121] Example 20. Synthesis of the rare earth complex shown in Formula II-18 (i.e., R1 = dimethylamino, R2 = R3 = H, Ln = Yb, L = TTA in Formula II)

[0122]

[0123] The synthesis steps were the same as in Example 16, except that europium chloride hexahydrate was replaced with ytterbium chloride hexahydrate. 0.46 g of the orange-red target ytterbium complex was obtained. Elemental analysis (mass percentage %): C, 45.21 (45.38); H, 2.59 (2.54); N, 7.09 (7.06), with theoretical values ​​in parentheses. The complex shown in Formula II-18 was dissolved in toluene, and the emission spectrum of the toluene solution (excitation wavelength 450 nm) is as follows. Figure 6As shown. When the central rare earth ion becomes an infrared-emitting ytterbium ion, the dipyridyltriazine ligand in this invention can form good coordination with the ytterbium ion and efficiently sensitize the ytterbium ion to emit infrared light.

[0124] <Applications of Rare Earth Complexes>

[0125] Example 21. The rare earth complex (tBuCzPhTPy2)Eu(TTA)3 shown in Formula II-10 (i.e., R1 = 3,6-di-tert-butylcarbazole, R2 = R3 = H, Ln = Eu, L = TTA) was dispersed in high molecular weight polystyrene as a luminescent film.

[0126] Rare earth complex (tBuCzPhTPy2)Eu(TTA)3 and high molecular weight polystyrene resin were mixed at a mass ratio of 1:50 and dissolved in toluene. The resulting mixture was then spin-coated onto a clean quartz glass surface to form a uniform polymer film.

[0127] The resulting thin film emits bright red light visible to the naked eye when illuminated by a blue LED. The absolute quantum yield of photoluminescence, measured using an integrating sphere, reaches 62%, making it a highly efficient light-converting thin film material.

[0128] This embodiment achieved a molar extinction coefficient of 11000 L mol at 450 nm. -1 cm -1 The quantum efficiency is 62%. 5 D0→ 7 A europium complex red light emitting thin film with an F2 transition half-maximum width of 9 nm and CIE coordinates x = 0.672.

[0129] The rare earth europium complex (CzMePhTPy2)Ln(TTA)3 in Example 13 (i.e., R1 = carbazole group, R2 = CH3, R3 = H, Ln = Eu, L = TTA in Formula II) has a solid powder photoluminescence quantum yield (PLQY) of 82.8% under 450 nm excitation, which is at a higher level than the europium complex PLQY reported in the literature.

[0130] As can be seen from the above embodiments, the rare earth complexes based on dipyridyltriazine ring ligands prepared by the present invention can be excited by long-wavelength near-ultraviolet or blue light, the excitation wavelength can be tuned, and they also have a high efficiency of photoluminescence quantum yield, and can be used as photoluminescent materials.

[0131] The embodiments described above are merely some preferred embodiments of the present invention, and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A long-wavelength sensitized rare-earth complex, characterized in that, The long-wavelength sensitized rare earth complex is a rare earth complex based on dipyridyltriazine cyclic ligands; The general structural formula of the rare earth complex based on the dipyridyltriazine ring ligand is (TPy2)Ln(L)3, where TPy2 is the neutral dipyridyltriazine ring ligand shown in Formula I, Ln represents a trivalent rare earth ion, and L represents a monovalent counter anion; the structure of the rare earth complex based on the dipyridyltriazine ring ligand is shown in Formula II. ； In Formulas I and II, R1 is methyl, methoxy, methylthio, carbazolyl, 3,6-diphenylcarbazolyl, 3,6-dimethylcarbazolyl, 3,6-di-tert-butylcarbazolyl, dimethylamino, or diphenylamino; R2 and R3 are each independently a hydrogen atom or a methyl group. Ln represents europium and terbium ions with a positive trivalent charge; L represents nitrate anion, halogen anion, acetate anion, trifluoroacetic acid anion, trifluoromethanesulfonic acid anion, β-diketone anion, or 4-hydroxy-1,5-naphthidine anion; The structure of the β-diketone anion is shown in Formula III, and the structure of the 4-hydroxy-1,5-naphthidine anion is shown in Formula IV. ； In Equations III and IV, R a and R b Each of them is independently phenyl, thienyl, pyridyl, methyl, ethyl, trifluoromethyl, or pentafluoroethyl; R1, R2, R3, R4, and R5 are selected from any one of hydrogen atom, halogen atom, cyano, methyl, ethyl, trifluoromethyl, or pentafluoroethyl.

2. The long-wavelength sensitized rare earth complex as described in claim 1, characterized in that, The β-diketone anion is selected from 2-thiophenecarboxyltrifluoroacetone anion, dibenzoylmethane anion, acetylacetone anion, or hexafluoroacetylacetone anion, and its structure is shown below: ； The 4-hydroxy-1,5-naphthidine anion is selected from 4-hydroxy-1,5-naphthidine anion, 3-cyano-4-hydroxy-1,5-naphthidine anion, and 3-cyano-4-hydroxy-8-methyl-1,5-naphthidine anion, with the following structure: 。 3. The method for preparing long-wavelength sensitized rare earth complexes as described in claim 1, characterized in that, The long-wavelength sensitized rare earth complex is an ionic rare earth complex based on dipyridyltriazine ring ligands. The preparation method is to react the TPy2 type ligands shown in Formula I with rare earth salts and the monovalent counter anion shown in L in a solvent to obtain the ionic rare earth complex based on dipyridyltriazine ring ligands shown in Formula II.

4. The method for preparing long-wavelength sensitized rare earth complexes as described in claim 3, characterized in that, The rare earth salts mentioned are selected from rare earth halogen salts, nitrates, acetates, trifluoroacetates, and trifluoromethanesulfonates.

5. The method for preparing long-wavelength sensitized rare earth complexes as described in claim 3, characterized in that, The molar ratio of the TPy2-type ligands, rare earth salts, and L-anions described in Formula I is 1:1:

3.

6. The method for preparing long-wavelength sensitized rare earth complexes as described in claim 3, characterized in that, The preparation method involves a reaction temperature of -10 to 120°C and a reaction time of 10 minutes to 24 hours.

7. The method for preparing long-wavelength sensitized rare earth complexes as described in claim 3, characterized in that, The solvent is any one or a mixture of two or more of water, methanol, ethanol, isopropanol, acetone, and tetrahydrofuran.

8. The application of the long-wavelength sensitized rare earth complex as described in claim 1, characterized in that, The long-wavelength sensitized rare-earth complexes are used as luminescent materials in the field of photoluminescence.

9. The application of the long-wavelength sensitized rare earth complex as described in claim 8, characterized in that, In terms of photoluminescence, the long-wavelength sensitized rare-earth complex can be used as an organic phosphor excited by near-ultraviolet light (360-400nm) or blue-violet light (400-460nm).

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