A layered scandium hydroxide composite material with luminescent properties, a preparation method thereof, and applications thereof

Abstract

The present invention relates to the field of luminescent materials, and discloses a layered scandium hydroxide composite material with luminescent properties, a preparation method thereof, and an application thereof. It conforms to the chemical general formula RE 2‑a Sc a (OH)5DS b X 1‑b ·nH2O; wherein, 1.85 ≤ a ≤ 1.9; 0.7 < b < 0.9; RE is any one of terbium or europium; X is any one of 4-biphenylacetate or terephthalate. The Tb 0.1 Sc 1.9 (OH)5DS 0.8 BPA 0.2 ·H2O colloid of the present invention can rapidly detect Fe 3+ in real time, and the operation is simple. The colloids of Tb 0.1 Sc 1.9 (OH)5DS 0.8 TA 0.2 ·H2O and Eu 0.14 Sc 1.86 (OH)5DS 0.8 TA 0.2 ·H2O achieve color change by adjusting the volume ratio of the two, and the operation is simple and rapid prototyping, providing a new idea for the preparation of luminescent hydrogels.

Description

Technical Field

[0001] The present invention relates to the field of luminescent materials, and particularly to a layered scandium hydroxide composite material with luminescent properties, a preparation method thereof, and an application thereof. Background Art

[0002] Luminescent materials have been widely used in fields such as lighting sources, ion detection, gene reporting, and biological labeling. Most luminescent materials are composed of a matrix and an activator, and the two complement each other to endow the luminescent materials with more excellent properties. Due to their rich interlayer chemistry, such as intercalation and ion exchange capabilities, layered inorganic materials have been widely and deeply studied in the fields of electricity, magnetism, and optics. Among them, layered rare earth hydroxides (LREHs) are a class of novel inorganic layered compounds composed of positively charged host layers and negatively charged guest anion layers, with typical two-dimensional structures, variable chemical compositions, and adjustable interlayer spacings, which provide many opportunities for the design of multifunctional luminescent materials.

[0003] Iron is one of the most common heavy metals in daily life and plays an important role in production and life. Even the human body cannot lack iron. However, the rapid development of industrialization has led to a huge impact of iron on the environment. Especially iron in water bodies can enter the human body through drinking, thus triggering diseases such as anemia, cancer, mental decline, and diabetes. Therefore, it is very necessary to seek a highly sensitive and selective iron ion monitoring and analysis technology. At present, methods for detecting iron ions include voltammetry, electrochemistry, fluorescence spectroscopy, and flame atomic absorption spectroscopy, etc. Among them, fluorescence spectroscopy has the characteristics of rapid response, simple operation method, and does not require expensive instruments, and has more advantages than other methods. Therefore, designing a detection material with fast response, simple operation, and low cost is of great significance for realizing the rapid detection of iron ions in real time. Summary of the Invention

[0004] Aiming at the technical problems in the prior art that the detection of iron ions still requires large-scale instruments, the operation is complex and cumbersome, the cost is relatively high, and it cannot respond quickly, the present invention provides a layered scandium hydroxide composite material with luminescent properties. The composite material makes a rapid response to iron ions through the obvious change in fluorescence intensity before and after binding iron ions, has simple operation, does not require expensive instruments, and reduces the production cost. Moreover, the layered scandium hydroxide composite material provided by the present invention can also be applied to the preparation of luminescent hydrogels, providing new ideas for the design of functional luminescent materials.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] In the first aspect of the present invention, there is provided a layered scandium hydroxide composite material with luminescent properties, and the chemical general formula of the layered scandium hydroxide composite material is: RE 2-a Sca (OH)5DS b X 1-b ·nH2O;

[0007] Wherein, 1.85 ≤ a ≤ 1.9; 0.7 < b < 0.9;

[0008] RE is any one of terbium or europium; X is 4-biphenylacetate or terephthalate.

[0009] The second aspect of the present invention provides a method for preparing the layered scandium hydroxide composite material with luminescence properties, which at least includes the following steps:

[0010] Step 1: Dissolve soluble rare earth metal salts, sodium dodecyl sulfonate and hexamethylenetetramine in deionized water, mix evenly to obtain a first mixed solution;

[0011] Step 2: Dissolve an organic ligand and a strong base in deionized water, mix evenly to obtain a second mixed solution;

[0012] Step 3: Mix the first mixed solution and the second mixed solution evenly, carry out a hydrothermal reaction at 85 °C - 95 °C for 11.5 h - 12.5 h, wash and dry to obtain a layered scandium hydroxide composite material with luminescence properties;

[0013] Wherein, the soluble rare earth metal salts include a first rare earth metal salt and a second rare earth metal salt, the first rare earth metal salt is a soluble scandium salt; the second rare earth metal salt is a soluble terbium salt or a soluble europium salt;

[0014] The organic ligand is 4-biphenylacetic acid or terephthalic acid.

[0015] Compared with the prior art, the layered scandium hydroxide composite material with luminescence properties provided by the present invention uses a non-lanthanide element scandium (Sc) with a smaller radius to prepare a series of layered scandium hydroxide composite phosphors inserted with organic ligand anions. By inserting organic ligand anions as light absorbers between the layers, the energy absorbed by them is effectively transferred to the emission energy levels of rare earth activator ions, thereby enhancing the luminescence intensity of rare earth activators. In addition, a surfactant dodecyl sulfonate anion (DS - ) can also be added between the layers as a support agent. Since the size of DS - is relatively long, it will increase the layer spacing of layered rare earth scandium hydroxide (LScH), making it easier to exfoliate into two-dimensional monolayer nanosheets with a two-dimensional morphology. The organic ligand anions (BPA - or TA 2- ) as light absorbers and DS - as a support agent are co-inserted into the interlayer of LScH by a hydrothermal synthesis method. In DS -Supported by this, it is beneficial for more ligand ions BPA - / TA 2- to enter the interlayer, so as to better interact with Tb 3+ / Eu 3+ and undergo effective energy transfer, significantly enhancing the green and red luminescence of Tb 3+ and Eu 3+ Thus, high-purity luminescent colors can be obtained, which lays a foundation for the preparation of multifunctional luminescent materials and expands the application fields of layered scandium hydroxide composites.

[0016] Preferably, the molar ratio of the soluble scandium salt to the second rare earth metal salt is 1.85 - 1.9:0.1 - 0.15.

[0017] Preferably, the total molar amount of the organic ligand and sodium dodecyl sulfonate is 2 mmol - 5 mmol.

[0018] Preferably, the molar ratio of the organic ligand to sodium dodecyl sulfonate is 0.15 - 0.25:0.75 - 0.85.

[0019] Preferably, the molar ratio of sodium dodecyl sulfonate, hexamethylenetetramine to the soluble rare earth metal salt is 2.1 - 2.7:0.9 - 1.1:0.9 - 1.1.

[0020] Preferably, the strong base is sodium hydroxide or potassium hydroxide.

[0021] Preferably, the molar ratio of the strong base to the organic ligand is 1 - 2:1.

[0022] The present invention also provides the application of the layered scandium hydroxide composite material with the chemical formula RE 2-a Sc a (OH)5DS 0.8 BPA 0.2 ·nH2O in the field of ion detection.

[0023] The present invention also provides the application of the layered scandium hydroxide composite material with the chemical formula RE 2-a Sc a (OH)5DS 0.8 TA 0.2 ·nH2O in the field of luminescent hydrogels.

[0024] Preferably, in the present invention, the layered scandium hydroxide composite material with luminescent properties is added to n-butanol and dispersed evenly to form a colloidal solution of the layered scandium hydroxide composite material with luminescent properties.

[0025] Preferably, the mass ratio of the solid composite material to n-butanol is 0.1 - 0.3:30 - 50.

[0026] In the process of detecting iron ions using the layered scandium hydroxide composite material with luminescent properties provided by the present invention, after the iron ions combine with the colloidal solution of the composite material, under the condition that the excitation wavelength is 290 nm, it is tested that obvious luminescence quenching appears at 545 nm for this composite material. And through testing, it is known that the degree of this luminescence quenching is linearly correlated with the concentration of iron ions, and the correlation coefficient can reach 0.9985. In the range of concentrations from 1 to 200 μM, accurate quantitative detection of iron ions can be achieved, the detection limit is as low as 0.15 μM, and the response is relatively fast, enabling on-site real-time detection, with simple operation and being convenient for industrial application.

[0027] When the colloidal solution of the layered scandium hydroxide composite material with luminescent properties provided by the present invention is mixed with agar powder, unique optical properties can be generated, thereby obtaining a hydrogel with multicolor photoluminescence. Moreover, the composite material provided by the present invention can, under the same excitation wavelength, by adjusting the colloidal ratio of 3+ Tb 3+ and

[0028] Eu 3+ , achieve various luminescent colors from the green region to the red region, providing a new idea for the preparation of multicolor luminescent hydrogels. - DS - ), and 4-biphenylacetate (BPA 2- ) or terephthalate (TA 3+ ) are co-inserted into the layered scandium hydroxide activated by 3+ Tb - or - Eu 3+ through a hydrothermal synthesis method to obtain three composite luminescent materials, and they are exfoliated into corresponding nanosheet sols. Among them, the colloidal solution co-intercalated with 3+ BPA 2- and - DS 3+ can be used to prepare a "turn-off" type fluorescence sensor to detect metal 3+ Fe 3+ , and can detect 3+ Fe BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 XRD patterns of the solid composites obtained in Examples 1-3 and Comparative Examples 1-2. Among them, (a) are the XRD patterns of the solid composites of Comparative Example 1 and Comparative Example 2; (b) are the XRD patterns of the solid composites of Examples 1-3.

[0030] Figure 2 Schematic structural diagrams of the composites obtained in Example 1, Example 3 and Comparative Example 1.

[0031] Figure 3 Photoluminescence spectra of the composites obtained in Examples 1-3 and Comparative Examples 1-2. Among them, (a) are the excitation spectra of the solid composites obtained in Example 1, Example 2 and Comparative Example 1; (b) are the emission spectra of the solid composites obtained in Example 1, Example 2 and Comparative Example 1; (c) are the photoluminescence spectra of the solid composites obtained in Example 3 and Comparative Example 2.

[0032] Figure 4 Ion detection application spectra of the composite colloid obtained in Example 1. Among them, (a) is the photoluminescence spectrum of the composite colloid obtained in Example 1; (b) is the comparison chart of the luminescence intensity of the composite colloid obtained in Example 1 after adding aqueous solutions of different metal ions; (c) is the emission spectrum diagram of the composite colloid obtained in Example 1 containing different concentrations of Fe 3+ (0 - 200 μM); (d) is the linear relationship diagram between F0 / F and Fe concentration of the composite colloid obtained in Example 1. 3+ Concentration linear relationship diagram.

[0033] Figure 5 Photoluminescence spectra of the composite colloid obtained in Example 2 and the composite colloid obtained in Example 3, as well as the emission spectrum diagram and chromaticity coordinate spectrum diagram of their mixed sol. Among them, (a) is the photoluminescence spectrum of the composite colloid obtained in Example 2; (b) is the photoluminescence spectrum of the composite colloid obtained in Example 3; (c) is the emission spectrum diagram of the composite colloid obtained in Example 2 and the composite colloid obtained in Example 3 after mixing in different volume ratios; (d) is the chromaticity coordinate spectrum diagram of the composite colloid obtained in Example 2 and the composite colloid obtained in Example 3 after mixing in different volume ratios.

[0034] Figure 6 Pictures of the hydrogels prepared in Test Example 1 and Test Example 2.

[0035] Figure 7XRD patterns and photoluminescence spectra of the composite materials obtained in Comparative Example 1, Comparative Example 4, and Comparative Example 5, where (a) are the XRD patterns of the composite materials obtained in Comparative Example 1, Comparative Example 4, and Comparative Example 5; (b) are the photoluminescence spectra of the composite materials obtained in Comparative Example 1, Comparative Example 4, and Comparative Example 5. Detailed implementation manners

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] Example 1

[0038] This example provides a layered scandium hydroxide composite material with luminescent properties, and the specific steps are as follows:

[0039] Step 1: Take 4.75 mL of 0.2 mol / L Sc(NO3)3, 0.25 mL of 0.2 mol / L Tb(NO3)3, 0.14 g (1 mmol) of hexamethylenetetramine (HMT), and 0.65 g (2.4 mmol) of sodium dodecyl sulfate (SDS), dissolve them in deionized water, and mix evenly to obtain a first mixed solution;

[0040] Step 2: Weigh 0.1274 g (0.6 mmol) of 4-biphenylacetic acid (BPA) and 0.02 g of NaOH, add 75 mL of deionized water, stir and dissolve to obtain a second mixed solution.

[0041] Step 2: Take the first mixed solution and the second mixed solution in a polytetrafluoroethylene high-pressure reaction kettle and react at 90 °C for 12 h. After the reaction, wash with deionized water and dry to obtain a solid composite material Tb 0.1 Sc 1.9 (OH)5DS 0.8 BPA 0.2 ·H2O.

[0042] Step 3: Take 0.1 g of Tb 0.1 Sc 1.9 (OH)5DS 0.8 BPA 0.2 ·H2O solid powder and disperse it in 50 mL of n-butanol, ultrasonically treat it at 40 KHz for 4 h, and then centrifuge it at a speed of 5000 r / min for 10 min to obtain a transparent Tb 0.1 Sc 1.9(OH)5DS 0.8 BPA 0.2 ·H2O colloid solution, which can be used as a fluorescent sensing material for detecting Fe 3+ .

[0043] Example 2

[0044] This example provides a layered scandium hydroxide composite material with luminescent properties. The specific steps are as follows:

[0045] Step 1: Take 4.75 mL of 0.2 mol / L Sc(NO3)3, 0.25 mL of 0.2 mol / L Tb(NO3)3, 0.14 g (1 mmol) of hexamethylenetetramine (HMT), and 0.65 g (2.4 mmol) of sodium dodecyl sulfate (SDS), dissolve them in deionized water, and mix evenly to obtain a first mixed solution;

[0046] Step 2: Weigh 0.12 g (0.6 mmol) of terephthalic acid (TA) and 0.04 g of NaOH, add 75 mL of deionized water, stir and dissolve to obtain a second mixed solution.

[0047] Step 3: Take the first mixed solution and the second mixed solution in a polytetrafluoroethylene high-pressure reaction kettle and react at 90 °C for 12 h. After the reaction, wash with deionized water and dry to obtain a solid composite material Tb 0.1 Sc 1.9 (OH)5DS 0.8 TA 0.2 ·H2O.

[0048] Step 4: Take 0.1 g of Tb 0.1 Sc 1.9 (OH)5DS 0.8 TA 0.2 ·H2O solid powder and disperse it in 50 mL of n-butanol, ultrasonically treat it at 40 KHz for 4 h, and then centrifuge it at a speed of 5200 r / min for 8 min to obtain a transparent Tb 0.1 Sc 1.9 (OH)5DS 0.8 TA 0.2 ·H2O colloid solution, which can be used as a raw material for preparing a multicolor luminescent hydrogel.

[0049] Example 3

[0050] This example provides a layered scandium hydroxide composite material with luminescent properties. The specific steps are as follows:

[0051] Step 1: Take 4.65 mL of 0.2 mol / L Sc(NO3)3, 0.35 mL of 0.2 mol / L Eu(NO3)3, 0.14 g (1 mmol) of hexamethylenetetramine (HMT), and 0.65 g (2.4 mmol) of sodium dodecyl sulfate (SDS), dissolve them in deionized water, and mix evenly to obtain a first mixed solution;

[0052] Step 2: Weigh 0.12 g (0.6 mmol) of terephthalic acid (TA) and 0.04 g of NaOH, add 75 mL of deionized water, stir and dissolve to obtain a second mixed solution.

[0053] Step 2: Take the first mixed solution and the second mixed solution in a polytetrafluoroethylene high-pressure reaction kettle and react at 90 °C for 12 h. After the reaction is completed, wash with deionized water and dry to obtain a solid composite material Eu 0.14 Sc 1.86 (OH)5DS 0.8 TA 0.2 ·H2O.

[0054] Step 3: Take 0.1 g of TA 0.2 DS 0.8 -LScH:Eu solid powder and disperse it in 50 mL of n-butanol, ultrasonically treat it at 40 KHz for 4 h, and then centrifuge it at a speed of 5000 r / min for 10 min to obtain a transparent Eu 0.14 Sc 1.86 (OH)5DS 0.8 TA 0.2 ·H2O colloidal solution, and this colloidal solution can be used as a raw material for preparing a multicolor luminescent hydrogel.

[0055] Comparative Example 1

[0056] This comparative example provides a layered scandium hydroxide composite material with luminescent properties, and the specific steps are as follows:

[0057] Step 1: Take 4.75 mL of 0.2 mol / L Sc(NO3)3, 0.25 mL of 0.2 mol / L Tb(NO3)3, 0.14 g (1 mmol) of hexamethylenetetramine (HMT), and 0.82 g (3 mmol) of sodium dodecyl sulfate (SDS), dissolve them in deionized water, and mix evenly to obtain a mixed solution;

[0058] Step 2: Take the mixed solution in a polytetrafluoroethylene high-pressure reaction kettle and react at 90 °C for 12 h. After the reaction is completed, wash with deionized water and dry to obtain a solid composite material Tb 0.1 Sc 1.9 (OH)5DS·H2O.

[0059] Comparative Example 2

[0060] This comparative example provides a layered scandium hydroxide composite material with luminescent properties. The specific steps are as follows:

[0061] Step 1: Take 4.65 mL of 0.2 mol / L Sc(NO3)3, 0.35 mL of 0.2 mol / L Eu(NO3)3, 0.14 g (1 mmol) of hexamethylenetetramine (HMT), and 0.82 g (3 mmol) of sodium dodecylsulfonate (SDS), dissolve them in deionized water, and mix evenly to obtain a mixed solution;

[0062] Step 2: Take the mixed solution in a polytetrafluoroethylene high-pressure reaction kettle and react at 90 °C for 12 h. After the reaction, wash with deionized water and dry to obtain the solid composite material Eu 0.14 Sc 1.86 (OH)5DS·H2O.

[0063] Comparative Example 3

[0064] The difference between this comparative example and Example 1 is only that BPA is replaced by 1,3,5-benzenetricarboxylic acid (BTC), and other components and preparation methods remain unchanged.

[0065] This comparative example provides a layered scandium hydroxide composite material BTC 0.2 DS 0.8 -LScH:Tb. The specific steps are as follows:

[0066] Step 1: Take 4.75 mL of 0.2 mol / L Sc(NO3)3, 0.25 mL of 0.2 mol / L Tb(NO3)3, 0.14 g (1 mmol) of hexamethylenetetramine (HMT), and 0.82 g (3 mmol) of sodium dodecylsulfonate (SDS), dissolve them in deionized water, and mix evenly to obtain a first mixed solution;

[0067] Step 2: Weigh 0.13 g (0.6 mmol) of 1,3,5-benzenetricarboxylic acid (BTC) and 0.07 g of NaOH, add 75 mL of deionized water, stir and dissolve to obtain a second mixed solution.

[0068] Step 2: Take the first mixed solution and the second mixed solution in a polytetrafluoroethylene high-pressure reaction kettle and react at 90 °C for 12 h. After the reaction, wash with deionized water and dry to obtain the solid composite material Tb 0.1 Sc 1.9 (OH)5DS 0.8 BTC 0.2 ·H2O.

[0069] Step 3: Take 0.1 g of Tb0.1 Sc 1.9 (OH)5DS 0.8 BTC 0.2 ·H2O solid powder was dispersed in 50 mL of n-butanol and sonicated for 4 h at 40 KHz, and then centrifuged at 5000 r / min for 10 min to obtain a transparent Tb 0.1 Sc 1.9 (OH)5DS 0.8 BTC 0.2 ·H2O colloidal solution. After testing, Fe could not be detected in this colloidal solution 3+ 。

[0070] Comparative Example 4

[0071] This comparative example provides a layered lanthanum hydroxide composite material with luminescent properties. The specific steps are as follows:

[0072] Step 1: Take 4.75 mL of 0.2 mol / L La(NO3)3, 0.25 mL of 0.2 mol / L Tb(NO3)3, 0.14 g (1 mmol) of hexamethylenetetramine (HMT), and 0.82 g (3 mmol) of sodium dodecyl sulfate (SDS), dissolve them in deionized water, and mix well to obtain a mixed solution;

[0073] Step 2: Take the mixed solution in a polytetrafluoroethylene high-pressure reaction kettle and react at 90 °C for 12 h. After the reaction is completed, wash with deionized water and dry to obtain a solid composite material Tb 0.1 La 1.9 (OH)5DS·H2O.

[0074] Comparative Example 5

[0075] This comparative example provides a layered yttrium hydroxide composite material with luminescent properties. The specific steps are as follows:

[0076] Step 1: Take 4.75 mL of 0.2 mol / L Y(NO3)3, 0.25 mL of 0.2 mol / L Tb(NO3)3, 0.14 g (1 mmol) of hexamethylenetetramine (HMT), and 0.82 g (3.0 mmol) of sodium dodecyl sulfate (SDS), dissolve them in deionized water, and mix well to obtain a mixed solution;

[0077] Step 2: Take the mixed solution in a polytetrafluoroethylene high-pressure reaction kettle and react at 90 °C for 12 h. After the reaction is completed, wash with deionized water and dry to obtain a solid composite material Tb 0.1 Y 1.9 (OH)5DS·H2O.

[0078] Test Example 1

[0079] Step 1: Take 2.5 g of agar powder and add it to deionized water at 95 °C, stir to obtain an agar powder sol.

[0080] Step 2: Mix the colloidal solution obtained in Example 2 and the agar powder sol evenly according to a volume ratio of 1:3, drop it into a mold, and cool to obtain hydrogels of different shapes.

[0081] Test Example 2

[0082] Replace the colloidal solution obtained in Example 2 in Test Example 1 with the colloidal solution obtained in Example 3, and keep the others unchanged.

[0083] To further illustrate the performance of the layered scandium hydroxide composite material with luminescence properties provided by the present application, the present invention conducts relevant optical tests on the composite materials obtained in the examples and comparative examples, and the test results are shown in Table 1 and the attached drawings.

[0084] Material Characterization

[0085] According to Figure 1 It can be seen that the composite materials provided in Examples 1-3 and Comparative Examples 1-2 all show a series of strong and ordered (00l) diffraction peaks, indicating that the prepared composite materials form the characteristic structure of LREHs. Taking the sample of Comparative Example 1 in Figure (a) as an example, diffraction peaks of three crystal planes, namely (001), (002), and (003), are observed at 3.1°, 6.2°, and 9.4° respectively, and the basal layer spacing d is about 2.78 nm. For Example 1 in Figure (b), similar to the diffraction peaks of Comparative Example 1, it shows a similar layer spacing d of about 2.74 nm; while the overall diffraction peaks of the samples of Example 2 and Example 3 shift slightly towards the lower 2θ angle direction, and the corresponding basal layer spacing becomes larger, d is about 3.00 nm and 2.96 nm, because DS - has a relatively large proportion in the layer, so the value of the layer spacing d is mainly determined by DS - This indicates that the interlayer space of the composite material is mainly supported by DS - and is also related to the number, size, and arrangement of the inserted organic anions.

[0086] According to the XRD test pattern, the present invention simulated the structures of the composite materials of Comparative Example 1, Example 1, and Example 3, as Figure 2 shown. For the sample of Comparative Example 1, the basal layer spacing d = 2.78 nm, and the thickness of the main layer in LScHs is about 0.65 nm, then the height of the interlayer is 2.13 nm (=2.78 nm - 0.65 nm). Since the straight-chain length of DS - is 1.7 nm, so DS -It should be arranged in an alternating antiparallel single layer. For the sample of Example 1 and the sample of Comparative Example 3, considering the thickness of the main layer and the size and proportion of the inserted anions, in the sample of Example 1, DS - is supported in a nearly vertical single layer between the layers, and BPA - is arranged in a double layer between the layers in a direction inclined to the main layer, while TA 2- is smaller in size than BPA - . Therefore, in the sample of Example 2, TA 2- is inserted into the interlayer in a double layer perpendicular to the main layer, but at this time DS - is supported in the interlayer in an alternating double layer in an inclined manner.

[0087] Moreover, the present invention also carried out photoluminescence tests on the composite materials provided in Examples 1-3 and Comparative Examples 1-2, and the results are as Figure 3 shown. Figure 3 (a) The excitation spectrum obtained by monitoring the characteristic emission of Tb 3+ at a wavelength of 545 nm for the 5 D4→ 7 F5 shows that there is an obvious broadband at 250 nm - 340 nm for the samples of Example 1 and Example 2, and the maximum excitation positions are approximately at 297 nm and 322 nm respectively. This broadband is attributed to the transitions of BPA - and TA 2- from the ground state S0 to the excited state S1 (S0→S1). In addition to the strong and broad excitation peaks, a series of weak peaks can be observed in the range of 340 - 400 nm, corresponding to the characteristic transitions of Tb 3+ for the 7 F6→ 5 D2 (350 nm), 7 F6→ 5 L 10 (368 nm) and 7 F6→ 5 G6 (377 nm).

[0088] Figure 3 (b) is the emission spectrum obtained for the three composite materials of Comparative Example 1, Example 1, and Example 2 at their respective optimal excitation wavelengths. All materials exhibit the typical 3+ emission of Tb 5 for the 7 D4→ J (J = 6, 5, 4, and 3) at 491 nm, 545 nm, 586 nm, and 622 nm, where the maximum emission peak is at 545 nm, which is the 3+ emission of Tb 5 for the 7The F5 transition corresponds to an obvious green emission. For the sample of Comparative Example 1, the green fluorescence is too weak to be hardly observed. Therefore, after forming the composite material co-intercalated with BPA - or TA 2- and DS - compared with the material with DS - single-intercalated, the green luminescence of Tb 3+ is greatly enhanced, about 100 times stronger than the previous luminescence intensity. This is obviously attributed to the effective sensitization of the BPA - or TA 2- organic anions in the layer. That is to say, the triplet energy level of BPA or TA matches the excited state energy level of the activator Tb 3+ , and good energy transfer can occur, thus greatly enhancing the green emission of the activator Tb 3+ .

[0089] Figure 3 (c) shows the excitation and emission spectra of the samples of Comparative Example 2 and Example 3 in the solid state. In the excitation spectrum (under the condition that the emission wavelength is 617 nm), four sharp excitation peaks can be observed in the range of 350 nm - 510 nm, which are the 3+ F0→ 7 L6, 5 F0→ 7 D3, 5 F0→ 7 D2 and 5 F0→ 7 D1 characteristic transitions of Eu 5 . For the sample of Example 3, a broadband excitation peak centered at 322 nm also appears, corresponding to the S0→S1 transition of TA 2- . In the emission spectra of Comparative Example 2 (excitation wavelength is 394 nm, excited by the 3+ F0→ 7 L6 characteristic transition of Eu 5 ) and Example 3 (excitation wavelength is 322 nm, excited by the S0→S1 transition of TA 2- ), emissions at 595 nm( 5 D0→ 7 F1), 617 nm( 5 D0→ 7 F2), 654 nm( 5 D0→ 7 F3) and 700 nm( 5 D0→ 7 F4) of Eu 3+ are shown, among which the 5 D0→7 The characteristic emission of F2 dominates. For the sample of Comparative Example 2, under excitation at 394 nm, the luminescence is extremely weak and almost undetectable. However, TA 2- and DS - The co-intercalated composite material significantly enhances the red emission at 617 nm, with the luminescence intensity increased by about 600 times compared to before, emitting strong red light. This is due to the insertion of TA in the middle of the layer 2- . TA 2- has a triplet energy level of 25160 cm -1 , Eu 3+ 's 5 D0 energy level is 17250 cm -1 , 5 D2 energy level is 21500 cm -1 . It is found that the triplet energy level of TA 2- is closer to the 3+ D2 energy level of Eu 5 . Therefore, it is possible that the ultraviolet light absorbed by TA 2- is transferred to the 3+ D2 energy level of Eu 5 to a greater extent first, and then transferred to the 5 D0 energy level to greatly improve the red emission of Eu 3+ , proving that TA 2- has a good sensitization effect on the luminescence of Eu 3+ .

[0090] To further confirm, the sample provided in Example 1 can be applied to the efficient detection of Fe 3+ . The present invention conducted relevant ion detection tests on it. According to Figure 4 (a), it can be seen that the photoluminescence diagram of the colloidal solution of Example 1 (tested at λem = 545 nm and λex = 290 nm), the Tyndall effect generated, and the picture under irradiation with a 254 nm ultraviolet lamp. In the excitation spectrum, only a strong broadband from 230 to 300 nm is observed, and this broadband must come from the absorption peak of BPA - , because it is almost the same as the peak shape in the solid state ( Figure 3 ), but the position of the best excitation peak has shifted from 297 nm in the solid state to 290 nm now, which is related to the addition of organic solvents during exfoliation. The emission spectrum of the colloidal solution consists of four characteristic emission peaks of Tb 3+ . In addition, the co-intercalated composite material of BPA - and DS - can be well dispersed in n-butanol to form a transparent colloidal solution. This colloidal solution can produce an obvious Tyndall effect under laser lamp irradiation and emit bright green light under irradiation with a 254 nm ultraviolet lamp. Figure 4(b) is a comparison chart of the fluorescence intensities of the blank colloidal solution in Example 1 and the mixed colloidal solution when different metal ions are added.

[0091] To study the recognition characteristics of the colloidal solution in Example 1 for metal ions, Zn 2+ , Na + , Ba 2+ , Cd 2+ , Li + , Mg 2+ , Ni 2+ , Co 2+ , Cu 2+ , Al 3+ and Fe 3+ eleven metal ions were selected as target ions. Aqueous solutions of these metal ions were obtained by dissolving their corresponding chlorides. 0.1 mL (50 mM) of aqueous solutions of different metal ions were respectively added to 3.4 mL of the colloidal solution, and the luminescence properties of the mixed colloids were tested at an excitation wavelength of 290 nm, and then their fluorescence intensities at the optimal emission wavelength of 545 nm were compared. It can be found from the figure that after adding the aqueous solutions of different metal ions, compared with the blank colloidal solution, the fluorescence intensity of the mixed colloidal solution decreased. This indicates that these metal ions can all quench the fluorescence of the colloidal solution, but different metal ions have different effects on its fluorescence intensity. If the fluorescence intensity of the initial colloidal solution is set to 100, the fluorescence intensities of the mixed colloidal solutions are respectively reduced to 92.6 (Zn 2+ ), 88.9 (Na + ), 87.0 (Ba 2+ ), 84.0 (Cd 2 + ), 81.4 (Li + ), 75.0 (Mg 2+ ), 64.2 (Ni 2+ ), 56.6 (Co 2+ ), 30.8 (Cu 2+ ), 18.3 (Al 3+ ) and 1.1 (Fe 3+ ). It can be known that the Fe 3+ metal ion has the strongest quenching effect on its fluorescence emission, in sharp contrast to other metal ions, which may be due to the interaction between Fe 3+ and the BPA 0.2 DS 0.8 -LScH:Tb composite material. Therefore, the BPA 0.2 DS 0.8 -LScH:Tb colloidal solution can be used as a "turn-off" type fluorescence sensing material for detecting Fe 3+ .

[0092] Since the colloid of Example 1 exhibits extremely high selectivity for Fe 3+ it is necessary to further study the effect of different concentrations of Fe 3+ on the fluorescence intensity of the mixed colloid. First, the concentration range of Fe 3+ was set to 1 - 200 μM, and a series of aqueous solutions containing metal Fe 3+ ions were prepared. Then, 0.2 mL of aqueous solutions of Fe 3+ ions with different concentrations were added to 1.8 mL of the colloid solution respectively. Finally, their emission spectra were measured with an excitation wavelength of 290 nm, as shown in Figure 4 (c). The results show that as the concentration of Fe 3+ increases, the fluorescence intensity of the mixed colloid gradually weakens. This confirms that the sensitivity of the colloid solution for detecting Fe 3+ is relatively high. According to the Stern - Volmer equation:

[0093] F0 / F = 1 + K sv [Q]

[0094] the linear relationship between the relative fluorescence intensity value F0 / F of the mixed colloid solution and the concentration of Fe 3+ can be obtained, as shown in Figure 4 (d). Among them, F0 represents the fluorescence intensity of the colloid solution of Standard Example 1, F represents the fluorescence intensity of the mixed colloid solution in the presence of Fe 3+ , K sv represents the quenching constant, and [Q] represents the concentration of Fe 3+ . From Figure 4 (d), it can be seen that a good linear relationship (R 3+ = 0.9985) can be observed when the concentration of Fe 2 is in the range of 1 - 200 μM. Based on this, we can obtain the value of K sv as 7.13×10 3 M -1 . The detection limit 3σ / K sv (σ is the standard deviation of the blank sample) can reach 0.15 μM.

[0095] To further confirm that the two composite materials provided in Example 2 and Example 3 can be applied to the preparation of multicolor luminescent hydrogels, the present invention conducted relevant tests on the colloid solutions of the two composite materials, as shown in Figure 5 (a) and (b). For the two colloid solutions of the sample of Example 2 (a) and the sample of Example 3 (b), the 547 nm ([[]] 3+ D4→ 5 F5 transition) of Tb 7 and the 617 nm ([[]] 3+ of Eu5 D0→ 7 F2 transition) as the emission wavelength, the excitation spectra of the two colloidal solutions were measured. Only a broadband centered at 312 nm was present in the spectra. Compared with the solid state, the shape of the excitation peak hardly changed, and the position of the peak center changed from 322 nm to 312 nm, which was due to the influence of the organic solvent during ultrasonic exfoliation into nanosheets. In the emission spectra of the two colloids excited at 312 nm wavelength, Tb 3+ 's 5 D4→ 7 F J (J = 6, 5, 4, and 3) characteristic peaks and Eu 3+ 's 5 D0→ 7 F J (J = 1, 2, 3, and 4) characteristic peaks were produced, and strong green and red emissions were shown under irradiation with a 254 nm ultraviolet lamp. The two colloidal solutions of the prepared Sample 2 (green light source) and Sample 3 (red light source) were mixed in different volume ratios, and the emission spectra of the mixed colloidal solutions were measured at an excitation wavelength of 312 nm, as shown in Figure 5 (c). The volume ratios of the two colloidal solutions were Tb 3+ :Eu 3+ = 5:1 (b), Tb 3+ :Eu 3+ = 4:2 (c), Tb 3+ :Eu 3+ = 3:3 (d), Tb 3+ :Eu 3+ = 2:4 (e), and Tb 3+ :Eu 3+ = 1:5 (f), where (a) is the colloidal solution containing only Tb 3+ , and (g) is the colloidal solution containing only Eu 3+ . The emission spectra of the mixed colloidal solutions were jointly composed of the characteristic emissions of Tb 3+ and Eu 3+ . With the increase in the content of the Eu 3+ colloid, the 5 D4→ 7 F5 green emission at 545 nm gradually weakened, while the 5 D0→ 7 F2 characteristic emission in the red light region gradually strengthened (see the upper left inset in Figure 5 (c)), and the emission color of the colloidal solution gradually changed from green to yellowish green, yellow, orange yellow, orange red, and red.

[0096] Moreover, the present invention also performs chromaticity coordinate tests on the colloidal solutions of Example 2 and Example 3 with different volume ratios, and the results are shown in Table 1 and Figure 5 (d). It can be seen that at the same excitation wavelength, by adjusting the volume ratio of the two composite materials, various luminescent colors from the green to the red region can be achieved.

[0097] Table 1. Chromaticity coordinate table of Example 2 and Example 3 with different volume ratios

[0098]

[0099] According to Figure 6 it can be known that the hydrogel prepared by the present invention presents milky white under daylight, but has various colors under ultraviolet light of 254 nm.

[0100] Figure 7 Figures of XRD and photoluminescence spectra of the three composite materials of Comparative Example 1, Comparative Example 4 and Comparative Example 5 are shown. By comparison, it is found that compared with the other two homologous rare earth systems (layered rare earth lanthanum hydroxide composite material and layered rare earth yttrium hydroxide composite material), the layered rare earth scandium hydroxide composite material shows better performance, especially in terms of crystallinity and fluorescence intensity. The layered rare earth scandium hydroxide composite material is significantly superior to the layered rare earth lanthanum hydroxide composite material and the layered rare earth yttrium hydroxide composite material. Therefore, the present invention has carried out research and development work on the layered rare earth scandium hydroxide composite material.

[0101] In summary, the present invention provides three kinds of composite luminescent materials based on layered scandium hydroxide. Among them, the colloidal solution of Example 1 with BPA - and DS - co-intercalated can be used to prepare a "turn-off" type fluorescence sensor to detect metal Fe 3+ , and it can detect Fe in the fields of environment and biomedicine, etc. 3+ ; The colloidal solutions of Example 2 and Example 3 with TA 2- and DS - co-intercalated can achieve color change by adjusting the contents of Tb 3+ and Eu 3+ in the mixed colloid. For preparing a hydrogel with multicolor luminescence, this method is simple to operate and can be quickly formed.

[0102] The above are only the preferred embodiments of the present invention, and they are not intended to limit the present invention. Any modifications, equivalent replacements or improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Use of a layered scandium hydroxide composite material in the detection of iron ions for non-diagnostic or non-disease treatment, characterized in that: The layered scandium hydroxide composite material is Tb 0.1 Sc 1.9 (OH)5DS 0.8 BPA 0.2 ·H2O.

2. Use of the layered scandium hydroxide composite material according to claim 1 in the detection of iron ions for non-diagnostic or non-disease treatment purposes, characterized in that: The preparation method of the layered scandium hydroxide composite material at least includes the following steps: Step 1: Dissolve a soluble rare earth metal salt, sodium dodecyl sulfonate, and hexamethylenetetramine in deionized water, and mix evenly to obtain a first mixed solution; Step 2: Dissolve an organic ligand and a strong base in deionized water, and mix evenly to obtain a second mixed solution; Step 3: Mix the first mixed solution and the second mixed solution evenly, carry out a hydrothermal reaction at 85°C - 95°C for 11.5 h - 12.5 h, wash, and dry to obtain the layered scandium hydroxide composite material; Among them, the soluble rare earth metal salt includes a first rare earth metal salt and a second rare earth metal salt. The first rare earth metal salt is a soluble scandium salt; the second rare earth metal salt is a soluble terbium salt; The organic ligand is 4-biphenylacetic acid.

3. Use of the layered scandium hydroxide composite material according to claim 2 in the detection of iron ions for non-diagnostic or non-disease treatment, characterized in that: The molar ratio of the soluble scandium salt to the soluble terbium salt is 1.9:0.

1.

4. Use of the layered scandium hydroxide composite material according to claim 2 in the detection of iron ions for non-diagnostic or non-disease treatment, characterized in that: The total molar amount of the 4-biphenylacetic acid and sodium dodecyl sulfonate is 3 mmol.

5. Use of the layered scandium hydroxide composite material according to claim 4 in the detection of iron ions for non-diagnostic or non-disease treatment, characterized in that: The molar ratio of the 4-biphenylacetic acid to sodium dodecyl sulfonate is 0.2:0.

8.

6. Use of the layered scandium hydroxide composite material according to claim 2 in the detection of iron ions for non-diagnostic or non-disease treatment, characterized in that: The molar ratio of the sodium dodecyl sulfonate, hexamethylenetetramine to the soluble rare earth metal salt is 2.4:1:

1.

7. Use of the layered scandium hydroxide composite material according to claim 2 in the detection of iron ions for non-diagnostic or non-disease treatment, characterized in that: The strong base is sodium hydroxide or potassium hydroxide.

8. Use of the layered scandium hydroxide composite material according to claim 2 in the detection of iron ions for non-diagnostic or non-disease treatment, characterized in that: The molar ratio of the organic ligand to the strong base is 1.2:1.

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