Method for regulating luminescent properties of polynuclear rare earth supermolecular complex and application thereof

Abstract

This application discloses a method and application for regulating the luminescence properties of polynuclear rare-earth supramolecular complexes, belonging to the field of luminescent rare-earth materials technology. The method includes the following steps: providing a C2-symmetric tetrazine bridging ligand; assembling the C2-symmetric tetrazine bridging ligand with rare-earth ions to obtain a polynuclear rare-earth supramolecular complex; then performing an IEDDA reaction between the polynuclear rare-earth supramolecular complex and a dienophile to obtain a pyridazine-based polynuclear rare-earth supramolecular complex; or, providing a C2-symmetric tetrazine bridging ligand; performing an IEDDA reaction between the tetrazine bridging ligand and a dienophile to obtain a pyridazine-based ligand; then assembling the pyridazine-based ligand with rare-earth ions to obtain a pyridazine-based polynuclear rare-earth supramolecular complex. This application achieves luminescence regulation through post-assembly covalent modification of polynuclear rare-earth supramolecular complexes, allowing for on-demand activation of rare-earth luminescence and realizing the regulation of rare-earth luminescence from scratch.

Description

Technical Field

[0001] This application relates to a method and application for regulating the luminescence properties of polynuclear rare earth supramolecular complexes, belonging to the field of luminescent rare earth materials technology. Background Technology

[0002] Due to the shielding effect of 4f electrons, rare earth elements possess unique photophysical properties, such as sharp linear emission bands, long lifetimes, and large Stokes / anti-Stokes shifts, and have been widely used in the manufacture of phosphors, light-emitting diodes, optical probes, and biomarkers. However, limited by the ff orbital transition forbidden effect, the absorption capacity of rare earth elements is very weak (molar absorption coefficient less than 10). 2 M -1 cm -1 Therefore, inorganic rare-earth nanoparticles / clusters typically have insufficient brightness and require high-power laser sources for excitation. To overcome the inherent weakness of rare-earth elements in absorption, organic ligands with strong chromophores are designed to construct rare-earth complexes. The "antenna effect" is an effective strategy to achieve efficient luminescence, and the structure of the ligands plays a crucial role in the luminescence performance of the rare-earth complexes.

[0003] Compared to mononuclear rare-earth complexes with limited structure and function, polynuclear rare-earth supramolecular complexes formed through coordination-driven self-assembly exhibit significant advantages and promising prospects in terms of structural and performance diversity, attracting increasing attention. A series of structurally elegant and high-performance polynuclear rare-earth supramolecular complexes have been designed and synthesized. Achieving luminescence modulation of polynuclear rare-earth supramolecular complexes undoubtedly plays a crucial role in expanding their applications, particularly in anti-counterfeiting, information encryption, and sensing detection. Currently, the methods for luminescence modulation of polynuclear rare-earth supramolecular complexes remain limited, mainly relying on non-covalent modification to adjust the coordination between ligands and rare-earth ions, thereby quenching or enhancing the luminescence of rare-earth ions. On the other hand, due to the variable coordination number and coordination configuration of rare-earth ions, orthogonal covalent modification of the relatively fragile and more dynamic polynuclear rare-earth supramolecular complexes remains a very challenging task. No reports have yet documented the use of orthogonal covalent modification on polynuclear rare-earth supramolecular complexes to achieve complete control over their optical properties. Summary of the Invention

[0004] To address the challenge of achieving luminescence modulation of polynuclear rare-earth supramolecular complexes through orthogonal covalent modification in existing technologies, this application proposes a novel strategy for luminescence modulation via post-assembly covalent modification. The significance of this technology lies primarily in the following aspects: ① It is the first time that luminescence modulation of polynuclear rare-earth supramolecular complexes has been achieved through post-assembly covalent modification; ② Compared to other technologies, this technology enables luminescence modulation of polynuclear rare-earth supramolecular complexes from scratch; ③ This application develops a novel strategy for designing luminescent rare-earth materials, providing new insights for the development of intelligent luminescent rare-earth functional materials.

[0005] The technical solution adopted in this application is as follows:

[0006] According to a first aspect of this application, a method for regulating the luminescence properties of polynuclear rare-earth supramolecular complexes is provided, comprising the following steps:

[0007] A C2-symmetric tetrazine-bridged ligand is provided. This C2-symmetric tetrazine-bridged ligand is then assembled with rare earth ions to obtain a polynuclear rare earth supramolecular complex. The polynuclear rare earth supramolecular complex is then subjected to an IEDDA reaction with a dienophile to obtain a pyridazine-based polynuclear rare earth supramolecular complex; or...

[0008] A tetrazine-bridged ligand with C2 symmetry is provided. The tetrazine-bridged ligand is reacted with a dienophile via IEDDA to obtain a pyridazine-based ligand. Then, the pyridazine-based ligand is assembled with rare earth ions to obtain a pyridazine-based polynuclear rare earth supramolecular complex.

[0009] Both the polynuclear rare earth supramolecular complexes and the pyridazine-based polynuclear rare earth supramolecular complexes are Ln 2n L 3n (n=1,2,3) type rare earth complexes; when n=1, both the polynuclear rare earth supramolecular complexes and the pyridazine-based polynuclear rare earth supramolecular complexes are helical assemblies.

[0010] L is a C2-symmetric tetrazine-bridged ligand, and Ln is a rare earth ion.

[0011] In this application, the IEDDA reaction, or Inverse-Electron-DemandDiels-Alder Reaction, is an important chemical reaction.

[0012] C2-symmetric tetrazine-bridged ligands can form Ln with rare earth ions (Ln). 2n L 3n Rare earth complexes.

[0013] ligands L and Ln 2n L3n All rare earth complexes can undergo IEDDA reaction with diephiles to generate the corresponding pyridazine products L' and Ln. 2n L' 3n Rare earth complexes.

[0014] Optionally, the tetrazine-bridged ligand has the structure shown in Formula I;

[0015]

[0016] in, Selected from one of the groups shown in Formula II;

[0017]

[0018] Selected from one of the groups shown in Formula III;

[0019]

[0020] In the above-mentioned groups, dashed lines indicate that a bond connection, such as a covalent bond, can be formed at the corresponding position. In the following text, dashed lines drawn in similar cases have the same meaning.

[0021] Optionally, the dienophile is selected from one of the structures shown in Formula IV;

[0022]

[0023] Optionally, the rare earth ions are selected from at least one of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

[0024] Optionally, the method for regulating the luminescence properties of the polynuclear rare-earth supramolecular complex includes the following steps:

[0025] Rare earth trifluoromethanesulfonate salt is added to a suspension containing the C2-symmetric tetraazine-bridged ligand and acetonitrile, and the mixture is heated to react. Then, a dienophile is added to the reaction system to carry out an IEDDA reaction, yielding a pyridazine-based polynuclear rare earth supramolecular complex; or,

[0026] IEDDA reaction was carried out by adding dienophiles to a solution containing the C2-symmetric tetraazine-bridged ligand, dichloromethane, and methanol, followed by the addition of rare earth trifluoromethanesulfonate salt and heating to obtain pyridazine-based polynuclear rare earth supramolecular complexes.

[0027] In the technical solution of this application, the tetraazine rare earth complex Ln 2n L 3nDue to the presence of the lower-energy tetrazine group, the emission of rare earth ions can be quenched through cross-bond energy transfer, thus preventing the emission of rare earth ions. The IEDDA reaction product, the pyridazine rare earth complex Ln, is different. 2n L' 3n Rare earth complexes, due to the enhancement of ligand energy levels, can sensitize rare earth ions through the "antenna effect" and exhibit the characteristic emission of rare earth ions.

[0028] Optionally, the conditions for the IEDDA reaction include: stirring the reaction at 0–100°C for 0.5–72 h.

[0029] Optionally, the tetrazine-bridged ligand is prepared using the following method:

[0030] A mixture of a raw material containing the structure shown in Formula III-b, a raw material containing the structure shown in Formula II-b, a catalyst, an acid-binding agent, and a solvent is subjected to an amide condensation reaction to obtain the tetraazine-bridged ligand with the structure shown in Formula I.

[0031] The structure shown in III-b is selected from one of the following structures:

[0032]

[0033] The structure shown in Equation II-b is selected from one of the following structures:

[0034]

[0035] Optionally, to ensure complete reaction of the raw materials in the structure shown in Formula II-b, the molar ratio of the raw materials in the structure shown in Formula III-b to those in the structure shown in Formula II-b should be greater than 2:1.

[0036] Optionally, the molar ratio of the raw material in the structure shown in Formula III-b to the raw material in the structure shown in Formula II-b is 2.1:1.

[0037] Optionally, the molar ratio of the feedstock to the catalyst in the structure shown in II-b is 1:2.5 to 4.0.

[0038] Optionally, the molar ratio of the raw material to the acid-binding agent in the structure shown in II-b is 1:2.5 to 10.

[0039] Optionally, the ratio of raw material to solvent in the structure shown in II-b is 1 mol: 5 to 50 L.

[0040] Optionally, the reaction conditions include: the reaction is carried out under ice bath conditions, and the reaction time is 6 to 24 hours.

[0041] Optionally, the catalyst is selected from N,N,N',N'-tetramethyl-O-(7-azabenzotriazol-1-yl)hexafluorophosphate.

[0042] Optionally, the acid-binding agent is selected from triethylamine.

[0043] Optionally, the solvent is selected from at least one of DMF and THF.

[0044] The preparation of the raw materials with the structure shown in III-b and the raw materials with the structure shown in II-b are not strictly limited in this application. Those skilled in the art can select raw materials as needed and combine them with existing technology to prepare the raw materials or purchase commercial products. For example, the preparation of 3,6-di(3-aminophenyl)-1,2,4,5-tetraazine (1) with the structure shown in II-b and 6-(isopropylcarbamoyl)pyridinecarboxylic acid (2) with the structure shown in III-b can be prepared with reference to the literature (J.Am.Chem.Soc.2020,142,9752-9762, J.Am.Chem.Soc.2017,139,8237-8244).

[0045] Optionally, the C2-symmetric tetrazine-bridged ligand has the structural formula shown in Formula V:

[0046]

[0047] Optionally, the method for regulating the luminescence properties of the multinuclear rare-earth supramolecular complex includes the following steps:

[0048] The polynuclear rare earth supramolecular complex formed by the compound shown in Formula V was reacted with norbornadiene by IEDDA reaction to obtain the pyridazine polynuclear rare earth supramolecular complex.

[0049] According to a second aspect of this application, an application is provided of the method for regulating the luminescence properties of the above-mentioned polynuclear rare earth supramolecular complex in the preparation of intelligent luminescent rare earth functional materials.

[0050] Optionally, the application includes the modulation of the luminescence of polynuclear rare-earth supramolecular complexes from scratch.

[0051] The beneficial effects of this application include:

[0052] The method for regulating the luminescence properties of polynuclear rare earth supramolecular complexes provided in this application has achieved the following three technical effects: (1) By introducing tetrazine groups into the backbone of ligands in polynuclear rare earth supramolecular complexes, and utilizing the good IEDDA reactivity of tetrazine groups, the orthogonal regulation of the luminescence properties of polynuclear rare earth supramolecular complexes after assembly by IEDDA reaction modification has been realized for the first time; (2) Compared with other quenching or enhancement-type regulation of the luminescence properties of polynuclear rare earth supramolecular complexes, this method realizes the activation type of polynuclear rare earth supramolecular complexes, that is, the luminescence regulation from nothing to something; (3) It provides a new idea for the development of intelligent luminescent rare earth functional materials. Based on the aforementioned technical effects, the method for regulating the luminescence properties of polynuclear rare earth supramolecular complexes in this application can activate the luminescence of rare earth complexes as needed, realizing the regulation of rare earth luminescence from nothing to something. It is expected to be applied in fields such as anti-counterfeiting and information encryption. In particular, considering the good applications of rare earth luminescent materials in fields such as sensing and detection and bioimaging, this method can significantly improve detection sensitivity and accuracy, reduce detection costs, and provide new tools and methods for food safety detection, production safety detection, and disease diagnosis. Attached Figure Description

[0053] Figure 1 This is a flowchart illustrating the method for regulating the luminescence properties of multinuclear rare-earth supramolecular complexes.

[0054] Figure 2 This is a single crystal structure diagram of Eu2(L1)3: for clarity, only ΛΛ-P-Eu2(L1)3 is shown, ignoring the counter anion and solvent molecules; the organic framework is represented by sticks, and metal ions are represented by spheres; only one ligand is represented in color (green represents carbon, white represents hydrogen, red represents oxygen, blue represents nitrogen, and pink sphere represents europium), and the other two ligands are represented in gray.

[0055] Figure 3 This is a single crystal structure diagram of Eu2(L1')3: for clarity, only ΛΛ-P-Eu2(L1')3 is shown, ignoring the counter anion and solvent molecules; the organic framework is represented by sticks, and metal ions are represented by spheres; only one ligand is represented in color (green represents carbon, white represents hydrogen, red represents oxygen, blue represents nitrogen, and pink sphere represents europium), and the other two ligands are represented in gray.

[0056] Figure 4 These are the UV-Vis absorption spectra of L1, L1', Eu2(L1)3, and Eu2(L1')3.

[0057] Figure 5 This is the excitation and emission spectrum of Eu2(L1')3.

[0058] Figure 6This is a schematic diagram of the IEDDA reaction regulation process for the formation of L1 from L1' and the formation of Eu2(L1)3 from Eu2(L1)3. Detailed Implementation

[0059] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0060] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased commercially. The deuterated solvent was purchased from Adamas, Bailingwei Technology Co., Ltd., etc.

[0061] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.

[0062] One-dimensional and two-dimensional NMR spectra were measured using a Bruker Biospin Avance III (400 MHz) NMR analyzer. The chemical shift values ​​in the proton NMR spectrum were determined based on the residual peaks of the deuterated solvent. High-resolution mass spectrometry was performed using a Bruker Impact II UHR-TOF mass spectrometer. The single-crystal structure was determined using a Bruker D8 VENTURE photon II single-crystal diffractometer. Excitation and emission spectra were measured using an Edinburgh FS5 spectrometer. The fluorescence quantum yield was determined using an Edinburgh SC-30 integrating sphere.

[0063] According to one embodiment of this application, a method for regulating the luminescence properties of multinuclear rare-earth supramolecular complexes is shown in the flowchart below. Figure 1 As shown, it includes the following steps:

[0064] A C2-symmetric tetrazine-bridged ligand is provided, and the C2-symmetric tetrazine-bridged ligand is assembled with rare earth ions to obtain a polynuclear rare earth supramolecular complex. Then, the polynuclear rare earth supramolecular complex is subjected to an IEDDA reaction with a diephile to obtain a pyridazine-based polynuclear rare earth supramolecular complex. Alternatively, a C2-symmetric tetrazine-bridged ligand is provided, and the tetrazine-bridged ligand is subjected to an IEDDA reaction with a diephile to obtain a pyridazine-based ligand. Then, the pyridazine-based ligand is assembled with rare earth ions to obtain a pyridazine-based polynuclear rare earth supramolecular complex.

[0065] Both the polynuclear rare earth supramolecular complexes and the pyridazine-based polynuclear rare earth supramolecular complexes are assemblies Ln 2n L 3n Rare earth complexes of type n, when n=1, such as Figure 1 As shown, both the polynuclear rare earth supramolecular complex and the pyridazine-based polynuclear rare earth supramolecular complex are helical assemblies.

[0066] L is a C2-symmetric tetrazine-bridged ligand, and Ln is a rare earth ion.

[0067] Preparation Example 1: Synthesis of Organic Ligand L1

[0068] Ligand L1 is obtained in the following ways:

[0069]

[0070] The synthesis of 3,6-di(3-aminophenyl)-1,2,4,5-tetraazine (1) and 6-(isopropylcarbamoyl)pyridinecarboxylic acid (2) is described in reference (J.Am.Chem.Soc.2020,142,9752-9762, J.Am.Chem.Soc.2017,139,8237-8244).

[0071] Under ice-bath stirring, N,N,N',N'-tetramethyl-O-(7-azabenzotriazol-1-yl)hexafluorophosphate urea (HATU, 3.58 g, 9.42 mmol, 3.0 eq) and triethylamine (TEA, 3 mL, 21.60 mmol, 7.0 eq) were added to a DMF (50 mL) solution of 3,6-bis(3-aminophenyl)-1,2,4,5-tetraazine (1, 0.82 g, 3.10 mmol, 1.0 eq) and 6-(isopropylcarbamoyl)pyridinecarboxylic acid (2, 1.36 g, 6.52 mmol, 2.1 eq). The reaction mixture was stirred overnight and then concentrated under reduced pressure. Subsequently, it was purified by column chromatography (silica gel, with DCM / MeOH = 100 / 1 as eluent) to give ligand L1 (1.86 g, 93%) as a purple powder. 1 H NMR (400MHz, d6-DMSO, 298K) δ11.12(s,2H),9.13(d,J=5.6Hz,2H),8.61(d,J=6Hz,4H),8.35(d,J=4Hz,2H), 8.27 (d, J = 4Hz, 2H), 8.23 ​​(t, J = 5.2Hz, 2H), 8.2 (d, J = 5.2Hz, 4H), 4.20-4.15 (m, 2H), 1.29 (d, J = 4.4Hz, 12H). C 34 H 32 N 10 High-resolution mass spectra of O4: m / z [C 34 H 32 N 10 O4+Na] + The simulated value is 667.2500, and the measured value is 667.2491.

[0072] Preparation Example 2: Synthesis of Eu2(L1)3 Helices

[0073] Eu2(L1)3 spirochetes are obtained through the following methods:

[0074]

[0075] L1 (12.15 mg, 18.85 μmol, 1.0 eq) was suspended in CD3CN solution (500 μL), and then Eu(OTf)3 (7.62 mg, 12.72 μmol, 0.67 eq) was added. The suspension was heated at 50 °C for 1 hour to obtain a homogeneous purple-red solution, which could be characterized without further treatment. NMR spectroscopy and high-resolution mass spectrometry showed the formation of Eu2(L1)3(OTf)6. 1 HNMR (600MHz, CD3CN, 298K) Eu2(L1)3(OTf)6: δ8.07(s,8H),7.51(t,J=8Hz,2H),7.28(s,2H),6.79(d ,J=8Hz,2H),6.64(d,J=8Hz,2H),4.58(s,2H),3.96(s,2H),1.37(d,J=4Hz,6H),0.92(d,J=4Hz,6H). 13 C10 NMR (400MHz, CD3CN): 162.78, 161.86, 156.08, 146.80, 144.74, 140.54, 130.63, 129.29, 123.24, 93.33, 92.91, 21.96, 21.73. High-resolution mass spectra of Eu2(L1)3(OTf)6: m / z [Eu2(L1)3-H] 5+ The simulated value was 447.3232, and the measured value was 447.3224; [Eu2(L1)3-2H] 4+ The simulated value was 558.9022, and the measured value was 558.9012 [Eu2(L1)3(OTf)1-H]. 4+ The simulated value was 596.6423, and the measured value was 596.6418; [Eu2(L1)3-3H] 3+ The simulated value was 744.8672, and the measured value was 744.8670; [Eu2(L1)3(OTf)1-2H] 3+ The simulated value was 795.1873, and the measured value was 795.1859; [Eu2(L1)3-4H] 2+ The simulated value was 1116.7972, and the measured value was 1116.7943.

[0076] Figure 2 This is a single crystal structure diagram of Eu2(L1)3.

[0077] L1 energy and Eu 3+A binuclear helix of the Eu2(L1)3 type is formed. Both the ligand L1 and the helical assembly Eu2(L1)3 can react with norbornene (NBD) to generate a pyridazine ligand L1' and a pyridazine helical assembly Eu2(L1')3. The method for regulating the luminescent properties of the Eu2(L1)3 assembly and the subsequent IEDDA reaction is as follows... Figure 6 As shown.

[0078] Example 1: IEDDA reaction of organic ligand L1 and Eu2(L1)3 spirochete

[0079] (1) IEDDA reaction of organic ligand L1

[0080] The reaction diagram is as follows Figure 6 As shown, L1 (100 mg, 155.27 μmol, 1.0 eq) was dissolved in a solution of V(DCM):V(MeOH) = 10:1 (800 mL), and then NBD (73.1 mg, 776.35 μmol, 5.0 eq) was added. The solution was heated at 50 °C for 2 days to obtain a homogeneous yellow solution. Subsequently, the solution was concentrated under reduced pressure and purified by column chromatography (silica gel, with DCM / MeOH = 50 / 1 as eluent) to obtain a yellow powdery ligand L1' (95 mg, 95.3%). 1 H NMR (400MHz, d6-DMSO, 298K) δ11.05 (s, 2H), 9.18 (d, J = 8Hz, 2H), 8.38 (s, 2H), 8.37 (d, J = 6.8Hz, 4H) ,8.36(d,2H),8.31-8.24(m,4H),8.12(d,J=8.4Hz,4H),4.26-4.18(m,2H),1.33(d,J=6.4Hz,12H). 13 C NMR (101MHz, d6-DMSO, 298K) δ162.19,161.93,156.21,149.25,148.41,139. 66,139.61,131.51,127.18,125.04,124.81,124.16,121.24,41.09,22.24. C 36 H 34 High-resolution mass spectra of N8O4: m / z [C 36 H 34 N8O4+Na] + The simulated value is 665.2595, and the measured value is 665.2591.

[0081] (2) IEDDA reaction of Eu2(L1)3 spirosome

[0082] The reaction diagram is as follows Figure 6As shown, L1 (12.15 mg, 18.85 μmol, 1.0 eq) was suspended in CD3CN solution (500 μL), and then Eu(OTf)3 (7.62 mg, 12.72 μmol, 0.67 eq) was added. The suspension was heated at 50 °C for 1 hour, and then NBD (5.32 mg, 56.55 μmol, 3.0 eq) was added. The mixture was heated and stirred for 8 hours to obtain a homogeneous yellow solution, which could be characterized without further treatment. 1H NMR (400MHz, CD3CN) δ8.13(s,4H),7.89(s,2H),7.7(d,J=6Hz,4H),7.55(t,J=7.6Hz,2H),7.40(s,2H),6.88 (d, J=8Hz, 2H), 6.71 (d, J=8Hz, 2H), 4.72 (s, 2H), 4.00 (s, 2H), 1.40 (d, J=5.2Hz, 6H), 0.96 (d, J=5.2Hz, 6H). 13 C10 NMR (400MHz, CD3CN): 164.93, 162.13, 161.05, 155.76, 146.04, 144.43, 138.82, 128.0, 122.78, 92.97, 92.70, 43.98, 26.89, 21.66, 21.43. High-resolution mass spectrometry of Eu2(L1')3(OTf)6: [Eu2(L1')3-2H] after reaction. 4+ The simulated value was 557.4094, and the measured value was 557.4085; [Eu2(L1')3(OTf)1-H] 4+ The simulated value was 595.1495, and the measured value was 595.1487; [Eu2(L1')3-3H] 3+ The simulated value was 742.8768, and the measured value was 742.8764; [Eu2(L1')3(OTf)1-2H] 3+ The simulated value was 793.1969, and the measured value was 793.1958.

[0083] Figure 3 This is a single crystal structure diagram of Eu2(L1')3.

[0084] Test Example 1: Optical Performance Testing of Eu2(L1')3

[0085] The ligands L1, L1' and the assemblies Eu2(L1)3, Eu2(L1')3 were subjected to UV-Vis absorption and fluorescence spectroscopy measurements, such as... Figure 4As shown in the figure, the maximum absorption wavelength of ligand L1 is located at 355 nm, while the maximum absorption wavelength of the reacted ligand L1' exhibits a blue shift, with the maximum absorption wavelength located at 334 nm. Furthermore, absorption peaks belonging to the tetrazine group were observed around 545 nm for both ligand L1 and Eu2(L1)3. At an excitation wavelength of 365 nm, the characteristic emission peaks of europium (593, 614, 694 nm) were observed. Figure 5 The corresponding absolute fluorescence quantum yield, measured using an integrating sphere, was 0.43%, and the fluorescence lifetimes were concentrated in the microsecond range, with the longest lifetime being 631.42 μs.

[0086] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for regulating the luminescence properties of multinuclear rare-earth supramolecular complexes, characterized in that, Includes the following steps: A C2-symmetric tetrazine-bridged ligand is provided. This C2-symmetric tetrazine-bridged ligand is then assembled with rare earth ions to obtain a polynuclear rare earth supramolecular complex. The polynuclear rare earth supramolecular complex is then subjected to an IEDDA reaction with a dienophile to obtain a pyridazine-based polynuclear rare earth supramolecular complex; or... A tetrazine-bridged ligand with C2 symmetry is provided. The tetrazine-bridged ligand is reacted with a dienophile via IEDDA to obtain a pyridazine-based ligand. Then, the pyridazine-based ligand is assembled with rare earth ions to obtain a pyridazine-based polynuclear rare earth supramolecular complex.

2. The method according to claim 1, characterized in that, The tetrazine-bridged ligand has the structure shown in Formula I; in, Selected from one of the groups shown in Formula II; Selected from one of the groups shown in Formula III; 3. The method according to claim 1, characterized in that, The dienophile is selected from one of the structures shown in Formula IV; 4. The method according to claim 1, characterized in that, The rare earth ions are selected from at least one of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

5. The method according to claim 1, characterized in that, The method for modulating the luminescence properties of the multinuclear rare-earth supramolecular complex includes the following steps: Rare earth trifluoromethanesulfonate salt is added to a suspension containing the C2-symmetric tetraazine-bridged ligand and acetonitrile, and the mixture is heated to react. Then, a dienophile is added to the reaction system to carry out an IEDDA reaction, yielding a pyridazine-based polynuclear rare earth supramolecular complex; or, IEDDA reaction was carried out by adding dienophiles to a solution containing the C2-symmetric tetraazine-bridged ligand, dichloromethane, and methanol, followed by the addition of rare earth trifluoromethanesulfonate salt and heating to obtain pyridazine-based polynuclear rare earth supramolecular complexes.

6. The method according to claim 1, characterized in that, The conditions for the IEDDA reaction include: stirring the reaction at 0–100°C for 0.5–72 h.

7. The method according to claim 1, characterized in that, The tetrazine-bridged ligand was prepared using the following method: A mixture of a raw material containing the structure shown in Formula III-b, a raw material containing the structure shown in Formula II-b, a catalyst, an acid-binding agent, and a solvent is subjected to an amide condensation reaction to obtain the tetraazine bridged ligand with the structure shown in Formula I. The structure shown in III-b is selected from one of the following structures: The structure shown in Equation II-b is selected from one of the following structures: Preferably, the molar ratio of the raw material to the catalyst in the structure shown in II-b is 1:2.5 to 4.0; Preferably, the molar ratio of the raw material to the acid-binding agent in the structure shown in II-b is 1:2.5 to 10; Preferably, the ratio of raw material to solvent in the structure shown in II-b is 1 mol: 5-50 L; Preferably, the reaction conditions include: the reaction is carried out under ice bath conditions, and the reaction time is 6 to 24 hours; Preferably, the catalyst is selected from N,N,N',N'-tetramethyl-O-(7-azabenzotriazol-1-yl)hexafluorophosphate urea; Preferably, the acid-binding agent is selected from triethylamine; Preferably, the solvent is selected from at least one of DMF and THF.

8. The method according to claim 7, characterized in that, The C2-symmetric tetrazine-bridged ligand has the structural formula shown in formula V: Preferably, the method for regulating the luminescence properties of the polynuclear rare-earth supramolecular complex includes the following steps: The polynuclear rare earth supramolecular complex formed by the compound shown in Formula V was subjected to an IEDDA reaction with norbornene to obtain the pyridazine polynuclear rare earth supramolecular complex.

9. The application of the method for regulating the luminescence properties of polynuclear rare earth supramolecular complexes according to any one of claims 1 to 8 in the preparation of intelligent luminescent rare earth functional materials.

10. The application according to claim 9, characterized in that, The applications include the modulation of luminescence from scratch in polynuclear rare-earth supramolecular complexes.

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