Method for synergistically preparing reversible water response fluorescent discoloration copper cluster from main group metals Mg < 2 + > and H2O
By using the coordination effect of 2-thioureacil and Mg2+ and the H2O-induced hydrogen bond, CuNCs are aggregated, and the problem of low fluorescence intensity of CuNCs is solved, and the effect of reversible water-responsive fluorescence discoloration and intensity enhancement is achieved. This process can be stable and cycled multiple times.
Patent Information
- Application Number
- CN202510365380.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-26
- Publication Date
- 2025-06-24
AI Technical Summary
Existing copper nanoclusters (CuNCs) have low fluorescence intensity, and few studies have been conducted on the induced aggregation of main group metal ions.
The coordination effect of 2-thioureacil as ligand with Mg2+ and H2O-induced hydrogen bonds were used to aggregate CuNCs to generate CuNCs with reversible water-responsive fluorescence discoloration properties.
The reversible fluorescence discoloration and enhancement between R-CuNCs and Y-CuNCs is achieved by adding H2O and drying, and the fluorescence intensity is increased by about 10 times, and the process can be stable and cycled about 11 times.
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Figure CN120192767A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of fluorescent nanomaterials, and relates to a method for synthesizing monodisperse copper nanoclusters (CuNCs) using 2-thiouracil as a ligand, and obtaining CuNCs with reversible water-responsive fluorescence color-changing performance by utilizing the coordination of the ligand with Mg 2+ and the hydrogen bond induced by H2O to aggregate CuNCs. Background Art
[0002] Metal nanoclusters are composed of several to hundreds of metal atoms. Due to the quantum size effect, the continuous energy levels split to form discrete energy levels similar to molecules, endowing them with photoluminescence properties. Compared with traditional organic luminescent materials and semiconductor quantum dots, metal nanoclusters have the advantages of simple synthesis, large Stokes shift, and low toxicity. Compared with noble metal nanoclusters such as gold, silver, and platinum, the precursors of copper nanoclusters (CuNCs) are more abundant and cheaper. However, at present, CuNCs have the shortcoming of low fluorescence intensity.
[0003] Aggregation-Induced Emission (AIE) is an effective method to improve the fluorescence intensity of CuNCs. Among them, the aggregation of CuNCs induced by metal ions is a common method. However, at present, most of them choose transition metal ions, such as Co 2+ 、Ni 2+ 、Zn 2+ etc., and there are few studies on the aggregation induced by main group metal ions. Compared with other light metals, Mg is more similar to 3d elements (such as Zn), and Mg 2+ is similar to Co 2+ 、Ni 2+ 、Zn 2+ in radius and hydration energy, and shows better coordination stability compared with other alkali metals and alkaline earth metals. Therefore, Mg 2+ has great potential in inducing the aggregation and luminescence of CuNCs.
[0004] The present invention selects 2-thiouracil as a ligand to synthesize almost non-fluorescent monodisperse CuNCs, and uses the coordination of the ligand with Mg 2+ and the hydrogen bond induced by H2O to aggregate CuNCs to generate a precipitate of CuNCs (Y-CuNCs) with bright yellow fluorescence. After centrifugation, washing, and drying, a powder of CuNCs (R-CuNCs) emitting red fluorescence is obtained. When water is added to the R-CuNCs powder, the fluorescence wavelength blue-shifts from 612 nm to 568 nm and turns yellow again (Y-CuNCs), and the fluorescence intensity increases by about 10 times. Therefore, R-CuNCs and Y-CuNCs can be reversibly transformed through the process of adding H2O - drying, and this reversible transformation process can be cycled about 11 times. Summary of the Invention
[0005] The object of the present invention is to propose a method for synthesizing almost non-fluorescent monodisperse copper nanoclusters (CuNCs) using 2-thiouracil as a ligand, and utilizing the coordination of the ligand with Mg 2+ and the hydrogen bonds induced by H2O to cause the aggregation of CuNCs to form Y-CuNCs precipitate. After centrifugation, washing, and drying, R-CuNCs powder is obtained. After adding H2O, the fluorescence wavelength blue-shifts from 612 nm to 568 nm, and the fluorescence intensity increases by about 10 times, and it turns into Y-CuNCs again. The reversible fluorescence color change and enhancement between R-CuNCs and Y-CuNCs can be achieved through the processes of adding H2O and drying, and this reversible fluorescence color change and enhancement process can be stably cycled about 11 times.
[0006] The technical solution of the present invention:
[0007] A method for co-preparing reversible water-responsive fluorescence color-changing copper clusters with main group metal Mg 2+ and H2O, the steps are as follows:
[0008] Step 1: Dissolve 2-thiouracil in sodium hydroxide solution, and dissolve Cu(NO3)2 in ultrapure water, stir evenly until completely dissolved, and prepare 2-thiouracil alkaline solution and Cu(NO3)2 solution;
[0009] Step 2: Mix the 2-thiouracil alkaline solution and the Cu(NO3)2 solution, stir at room temperature for 10 min to obtain a light yellow-green CuNCs stock solution.
[0010] Step 3: Add MgCl2 solution to the CuNCs stock solution, stir at room temperature for 7 h to form a white Y-CuNCs precipitate with yellow fluorescence. After centrifugation, washing, and drying, a yellow-green R-CuNCs powder with red fluorescence is obtained.
[0011] Further, the concentration of the 2-thiouracil solution described in Step 1 is 75-175 mM;
[0012] Further, the concentration of the Cu(NO3)2 solution described in Step 1 is 25 mM;
[0013] Further, the concentration of the sodium hydroxide solution described in Step 1 is 0.2 M;
[0014] Further, the volume ratio of the 2-thiouracil alkaline solution and the Cu(NO3)2 solution described in Step 2 is 1:1;
[0015] Further, the concentration of the MgCl2 solution described in Step 3 is 0.1-0.3 M, and the volume ratio of the MgCl2 solution to the CuNCs stock solution is 1:5;
[0016] Further, replace 2-thiouracil in Step 1 with 6-methyl-2-thiouracil;
[0017] Further, replace MgCl2 in Step 3 with NaCl, AlCl3, KCl, CaCl2, and CsCl in sequence;
[0018] Further, add ultrapure water dropwise onto the R-CuNCs powder to obtain Y-CuNCs. Then, after drying Y-CuNCs at 60 °C for 30 min, it is transformed back into R-CuNCs again.
[0019] Advantages of the present invention: The present invention uses 2-thiouracil as a protecting agent and Cu(NO3)2 as a copper source to synthesize CuNCs with almost no fluorescence. Utilizing the coordination effect between the ligand and Mg 2+ and the H2O-induced hydrogen bond, CuNCs aggregate to form Y-CuNCs precipitate. After centrifugation, washing, and drying, R-CuNCs powder is obtained. After adding H2O, the fluorescence intensity increases by about 10 times, and the fluorescence wavelength blue-shifts from 612 nm to 568 nm. R-CuNCs are re-transformed into Y-CuNCs. Through the processes of adding H2O and drying, the water-responsive reversible fluorescence color change and enhancement of R-CuNCs and Y-CuNCs can be achieved. R- / Y-CuNCs are reversible water-responsive fluorescence color-changing materials, and this reversible fluorescence color change process can be stably cycled about 11 times. Description of the Drawings
[0020] Figure 1 It is the fluorescence spectrum diagram of the R-CuNCs synthesized in Examples 1 to 5 under excitation at 278 nm.
[0021] Figure 2 It is the fluorescence spectrum diagram of the R-CuNCs synthesized in Examples 6 to 10 under excitation at 278 nm.
[0022] Figure 3 It is the transmission electron microscope image of the CuNCs stock solution synthesized in Example 4.
[0023] Figure 4 It is the scanning electron microscope image of R- / Y-CuNCs in Example 11; a is the scanning electron microscope image of R-CuNCs; b is the scanning electron microscope image of Y-CuNCs.
[0024] Figure 5 It is the best excitation and best emission spectrum diagrams of R- / Y-CuNCs in Example 11; (a) is the best excitation and best emission spectrum diagrams of R-CuNCs; (b) is the best excitation and best emission spectrum diagrams of Y-CuNCs.
[0025] Figure 6 It is the fluorescence intensity comparison diagram of R- / Y-CuNCs in Example 11.
[0026] Figure 7 It is the fluorescence change diagram of the cycle of R-CuNCs during the addition of H2O-drying in Example 11.
[0027] Figure 8 It is the fluorescence intensity comparison diagram of CuNCs-1 / -2 in Comparative Example 1.
[0028] Figure 9 It is the fluorescence intensity comparison diagram of CuNCs after adding different main group metal ions in Comparative Example 2. Detailed implementation manners
[0029] The following further illustrates the detailed implementation manners of the present invention in conjunction with the attached drawings and technical solutions.
[0030] Examples 1 to 5
[0031] A method for preparing R-CuNCs by the coordination of a ligand and Mg 2+ and the induction of hydrogen bonds by H2O, the method comprises the following steps:
[0032] (1) Dissolve 2-thiouracil in sodium hydroxide solution, dissolve Cu(NO3)2 in ultrapure water, stir evenly until completely dissolved, and prepare 2-thiouracil alkaline solutions with different concentrations and a 25 mM Cu(NO3)2 solution.
[0033] (2) Mix the 2-thiouracil alkaline solution and the Cu(NO3)2 solution obtained in step (1) in equal volume, stir at room temperature for 10 min to obtain a light yellow-green CuNCs stock solution.
[0034] (3) Take 10 mL of the CuNCs stock solution in step (2), add 2 mL of 0.3 M MgCl2 solution, stir at room temperature for 7 h to form a white Y-CuNCs precipitate with yellow fluorescence. After centrifugation, washing and drying, a light yellow-green R-CuNCs powder with red fluorescence is obtained. The concentrations of the 2-thiouracil solutions in Examples 1 to 5 are shown in Table 1.
[0035] Table 1 Concentrations of 2-thiouracil solutions in Examples 1 to 5
[0036] Example 1 Example 2 Example 3 Example 4 Example 5 Concentration (mM) 75 100 125 150 175
[0037] As Figure 1 can be seen, with the increase of the concentration of the 2-thiouracil solution, the fluorescence wavelength of the obtained R-CuNCs does not change, the emission wavelength is 612 nm, which is in the red light wavelength range; when the concentration of the 2-thiouracil solution is increased to 150 mM, that is, when the ligand and Cu 2+The fluorescence intensity of CuNCs obtained when the molar ratio is 6:1 is the highest; when the concentration of the 2-thiouracil solution is continuously increased to 175 mM, the fluorescence intensity of the obtained CuNCs decreases. Therefore, the optimal concentration of the 2-thiouracil solution is 150 mM.
[0038] Examples 5 - 8
[0039] A method for preparing R-CuNCs by the coordination of a ligand and Mg 2+ and the induction of hydrogen bonds by H2O, the method comprises the following steps:
[0040] (1) Dissolve 2-thiouracil in sodium hydroxide solution, dissolve Cu(NO3)2 in ultrapure water, stir evenly until completely dissolved, and prepare a 150 mM 2-thiouracil alkaline solution and a 25 mM Cu(NO3)2 solution.
[0041] (2) Mix the 2-thiouracil alkaline solution and the Cu(NO3)2 solution obtained in step (1) in equal volumes, and stir at room temperature for 10 min to obtain a light yellow-green CuNCs stock solution.
[0042] (3) Take 10 mL of the CuNCs stock solution in step (2), add 2 mL of MgCl2 solutions with different concentrations, stir at room temperature for 7 h to generate a white Y-CuNCs precipitate with yellow fluorescence, and obtain a yellow-green R-CuNCs powder with red fluorescence after centrifugation, washing, and drying. The different copper sources in Examples 6 - 10 are shown in Table 3.
[0043] Table 2 Concentrations of MgCl2 solutions in Examples 6 - 10
[0044] Example 6 Example 7 Example 8 Example 9 Example 10 Concentration 0.1M 0.15M 0.2M 0.25M 0.3M
[0045] It can be seen from Figure 2 that as the concentration of the MgCl2 solution increases, the fluorescence intensity of the obtained R-CuNCs shows a trend of first increasing and then decreasing. When the concentration of the MgCl2 solution is increased from 0.15 M to 0.25 M, the fluorescence intensity of the obtained CuNCs gradually increases, and reaches the highest when the concentration of the MgCl2 solution is 0.25 M; when the concentration of the MgCl2 solution is continuously increased to 0.3 M and 0.35 M, the fluorescence intensity of the obtained CuNCs gradually decreases. Therefore, the optimal concentration of the MgCl2 solution is 0.25 M.
[0046] Example 11
[0047] Interconversion between R-CuNCs and Y-CuNCs:
[0048] Ultra-pure water was added dropwise to the R-CuNCs powder obtained in Example 8. After several seconds, the fluorescence color of the CuNCs changed from red to yellow, and Y-CuNCs were obtained. After drying the Y-CuNCs at 60 °C for 15 min, they changed back to R-CuNCs again.
[0049] It can be seen from Figure 3 that the transmission electron micrograph of the CuNCs stock solution before adding Mg 2+ showed that their sizes were uniform and the dispersibility was good. It can be seen from Figure 4 that after adding Mg 2+ the CuNCs aggregated. It was observed that the R-CuNCs had a lamellar structure, while the Y-CuNCs had a block structure formed by stacking of lamellae, indicating that the lamellae were connected by hydrogen bonds formed by water molecules.
[0050] It can be seen from Figure 5 that the optimal excitation peaks of both R-CuNCs and Y-CuNCs were 278 nm. The optimal emission peak of R-CuNCs was 612 nm, while the optimal emission peak of Y-CuNCs was 568 nm, indicating that the fluorescence wavelength blue-shifted by 44 nm after adding H2O. Further, the fluorescence intensities of Y- / R-CuNCs were compared. It can be seen from Figure 6 that the fluorescence intensity of Y-CuNCs was about 10 times that of R-CuNCs.
[0051] It can be seen from Figure 7 that when the R-CuNCs were cycled during the process of adding H2O-drying, it was observed that at the 11th cycle, neither the fluorescence wavelength nor the fluorescence intensity of R- / Y-CuNCs changed significantly. When the cycle reached 13 times, the fluorescence intensity of Y-CuNCs changed significantly, decreasing by about 1 / 3, but the fluorescence wavelength of R- / Y-CuNCs still did not change significantly. Therefore, the reversible fluorescence color change process between R-CuNCs and Y-CuNCs could be stably cycled about 11 times.
[0052] Comparative Example 1
[0053] A method for preparing CuNCs by the coordination of a ligand and Mg 2+ and the induction of hydrogen bonds by H2O, the method comprises the following steps:
[0054] (1) 6-Methyl-2-thiouracil was dissolved in sodium hydroxide solution, and Cu(NO3)2 was dissolved in ultra-pure water. After stirring evenly until completely dissolved, a 150 mM 6-methyl-2-thiouracil solution and a 25 mM Cu(NO3)2 solution were prepared.
[0055] (2) Mix the 26-methyl-2-thiouracil alkaline solution obtained in step (1) and the Cu(NO3)2 solution in equal volumes, and stir for 10 min at room temperature to obtain a light yellowish-green CuNCs stock solution.
[0056] (3) Take 10 mL of the CuNCs stock solution in step (2), add 2 mL of 0.3 M MgCl2 solution, and stir for 7 h at room temperature to form a white CuNCs-1 precipitate with orange fluorescence. After centrifugation, washing, and drying, a yellowish-green CuNCs-1 powder with orange fluorescence is obtained. Dry it at 60 °C for 1 h to obtain a yellowish-green CuNCs-2 powder with weak orange fluorescence.
[0057] As Figure 8 can be seen, the best emission peaks of both CuNCs-1 and CuNCs-2 are 588 nm, and the fluorescence intensity of CuNCs-1 is about 20 times that of CuNCs-2. Therefore, there is only a difference in fluorescence intensity between CuNCs-1 / -2, and no fluorescence color change occurs. This is because compared with 2-thiouracil, 6-methyl-2-thiouracil has an additional methyl group, which hinders the formation of hydrogen bonds between adjacent ligands on the surface of CuNCs induced by H2O. The formation and destruction of hydrogen bonds between adjacent ligands are the main reasons for fluorescence color change.
[0058] Comparative Example 2
[0059] A method for preparing CuNCs by the coordination of a ligand and a main group metal ion and H2O-induced hydrogen bonding, the method comprising the following steps:
[0060] (1) Dissolve 2-thiouracil in sodium hydroxide solution, dissolve Cu(NO3)2 in ultrapure water, stir evenly until completely dissolved, and prepare a 150 mM 2-thiouracil alkaline solution and a 25 mM Cu(NO3)2 solution.
[0061] (2) Mix the 2-thiouracil alkaline solution obtained in step (1) and the Cu(NO3)2 solution in equal volumes, and stir for 10 min at room temperature to obtain a light yellowish-green CuNCs stock solution.
[0062] (3) Take 6 portions of 10 mL of the CuNCs stock solution in step (2), and add 2 mL of 0.3 M MgCl2, NaCl, AlCl3, KCl, CaCl2, CsCl solutions respectively, and stir for 7 h at room temperature.
[0063] As Figure 9 can be seen, except for adding Mg 2+ outside, adding other main group metal ions fails to significantly enhance the fluorescence intensity of CuNCs. Therefore, CuNCs with 2-thiouracil as the ligand are sensitive to Mg 2+Selectively, during the formation of R- / Y-CuNCs, the coordination of Mg 2+ is crucial.
Claims
1. A main group metal Mg 2+ A method for preparing a reversible water-responsive fluorescent color-changing copper cluster in collaboration with H2O, characterized in that: Here are the steps: Step 1, dissolving 2-thiouracil in a sodium hydroxide solution, dissolving Cu(NO3)2 in ultrapure water, stirring evenly until completely dissolved, to prepare a 2-thiouracil alkaline solution and a Cu(NO3)2 solution; Step 2, mix the 2-thiouracil alkaline solution and the Cu(NO3)2 solution, and stir at room temperature for 10 min to obtain a light yellow-green CuNCs stock solution; Step 3: Add MgCl2 solution to the CuNCs stock solution and stir at room temperature for 7 h to generate a white Y-CuNCs precipitate with yellow fluorescence. After centrifugation, washing and drying, a yellow-green R-CuNCs powder with red fluorescence was obtained.
2. The main group metal Mg according to claim 1 2+ A method for preparing a reversible water-responsive fluorescent color-changing copper cluster in collaboration with H2O, characterized in that: The concentration of the 2-thiouracil solution in step 1 is 75-175 mM.
3. The main group metal Mg according to claim 1 2+ A method for preparing a reversible water-responsive fluorescent color-changing copper cluster in collaboration with H2O, characterized in that: The concentration of the Cu(NO3)2 solution described in step 1 is 25mM.
4. The main group metal Mg according to claim 1 2+ A method for preparing a reversible water-responsive fluorescent color-changing copper cluster in collaboration with H2O, characterized in that: The concentration of the sodium hydroxide solution in step 1 is 0.2M.
5. The main group metal Mg according to claim 1 2+ A method for preparing a reversible water-responsive fluorescent color-changing copper cluster in collaboration with H2O, characterized in that: The volume ratio of the 2-thiouracil alkaline solution and the Cu(NO3)2 solution in step 2 is 1:
1.
6. The main group metal Mg according to claim 1 2+ A method for preparing a reversible water-responsive fluorescent color-changing copper cluster in collaboration with H2O, characterized in that: The concentration of the MgCl2 solution in step 3 is 0.1-0.3 M, and the volume ratio of the MgCl2 solution to the CuNCs stock solution is 1:
5.
7. The main group metal Mg according to claim 1 2+ A method for preparing a reversible water-responsive fluorescent color-changing copper cluster in collaboration with H2O, characterized in that: The 2-thiouracil in step 1 was replaced with 6-methyl 2-thiouracil.
8. The main group metal Mg according to claim 1 2+ A method for preparing a reversible water-responsive fluorescent color-changing copper cluster in collaboration with H2O, characterized in that: The MgCl2 in step 3 was replaced with NaCl, AlCl3, KCl, CaCl2 or CsCl in turn.
9. The main group metal Mg according to claim 1 2+ A method for preparing a reversible water-responsive fluorescent color-changing copper cluster in collaboration with H2O, characterized in that: Ultrapure water was dropped onto the R-CuNCs powder to obtain Y-CuNCs; after drying the Y-CuNCs at 60°C for 30 min, they were transformed into R-CuNCs again.