Chiral inorganic bismuth oxyhalide material and preparation method thereof
By preparing chiral inorganic bismuth halide materials, the problems of lack of intrinsic chirality and insufficient photostability of upconversion luminescent materials were solved, achieving strong CD signal and controllable circularly polarized luminescence performance, which is suitable for deep tissue imaging.
Patent Information
- Application Number
- CN202511934252.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-20
- Publication Date
- 2026-02-17
AI Technical Summary
Existing upconversion luminescent materials lack intrinsic chirality, have weak circular polarization luminescence activity, and poor photostability, which limits their application in fields such as polarization light detection and chiral photocatalysis.
Chiral inorganic bismuth oxide materials were prepared by hydrothermal reaction and annealing of achiral Bi4O5Br2 nanosheets with Yb2O3, Er2O3 and the chirality inducer D-sorbitol under specific conditions.
The prepared material has an intrinsic chiral structure, can directly generate circularly polarized light, has good photostability, and its luminescence performance is controllable, making it suitable for deep tissue imaging.
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Figure CN121536960A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of chiral inorganic luminescent materials, and particularly relates to a chiral inorganic bismuth oxyhalide material and a preparation method of the chiral inorganic bismuth oxyhalide material. BACKGROUND
[0002] Chiral materials have great application potential in the fields of optoelectronics, catalysis, sensing and enantioselective reactions due to their characteristics that they cannot coincide with their mirror images in three-dimensional space. Circular dichroism (CD) and circularly polarized luminescence (CPL) are important optical properties of chiral materials. At present, CPL active materials mainly rely on organic systems or surface-modified non-chiral inorganic materials, which have problems such as poor light stability and complex preparation.
[0003] Upconversion luminescence (UCL) materials can convert low-energy photons into high-energy photons, especially emit visible light or ultraviolet light under near-infrared excitation, and have unique advantages in biological imaging, optoelectronic devices and other aspects. However, existing upconversion materials generally lack chiral structures, and it is difficult to directly produce circularly polarized light, which limits their application in polarized light detection, chiral photocatalysis and other fields.
[0004] In recent years, the development of CPL active materials has made significant progress, which has been extended from organic systems to inorganic systems. These include D- / L-amino acid-coated quantum dots and rods, metal nanoclusters and supramolecular co-assembled upconversion nanoparticles (UCNPs). It must be emphasized that chiral induction and transfer are the main strategies to endow non-chiral inorganic nanomaterials with chiral properties. UC-CPL active materials prepared from organic molecules usually have high luminescence quantum yield, but they often exhibit poor light stability. On the contrary, UC-CPL materials made of inorganic nanomaterials perform well in exciting visible light and near-infrared circularly polarized light, while also showing significant light stability. However, the synthesis of chiral organic ligands or chiral inorganic nanoparticles is necessary. The general method of realizing UC-CPL in inorganic nanomaterials without introducing any chiral species constitutes a major challenge.
[0005] Therefore, the application provides a preparation method of a chiral inorganic bismuth oxyhalide material, which is prepared by subjecting non-chiral Bi4O5Br2 nanosheets to a hydrothermal reaction with Yb2O3, Er2O3 and a chiral inducer, and then annealing. SUMMARY
[0006] The application aims to provide a preparation method of a chiral inorganic bismuth oxyhalide material, and solves the problems of lack of intrinsic chirality, weak circularly polarized luminescence activity and poor light stability of upconversion luminescence materials.
[0007] The application also aims to provide a chiral inorganic bismuth oxyhalide material.
[0008] The application aims to achieve the above-mentioned purpose through the following technical solutions.
[0009] A preparation method of a chiral inorganic bismuth oxyhalide material, comprising the following steps:
[0010] (1) dissolving Bi(NO3)3·5H2O and a halide salt in a solvent, stirring, adjusting the pH to 2-10, performing a first hydrothermal reaction, centrifuging and drying after cooling to obtain non-chiral Bi4O5Br2 nanosheets;
[0011] (2) mixing the non-chiral Bi4O5Br2 nanosheets with Yb2O3, Er2O3 and a chiral inducer in a solvent, performing a second hydrothermal reaction and annealing treatment to obtain the chiral inorganic bismuth oxyhalide material.
[0012] In the application, the halide salt is one of sodium bromide or potassium bromide.
[0013] Preferably, the pH is 8.
[0014] In the application, the molar ratio of Bi(NO3)3·5H2O and the halide salt is 1-2:1.
[0015] In the application, the temperature of the first hydrothermal reaction in step (1) is 120-180℃, and the reaction time is 3-24h.
[0016] In the application, the drying temperature in step (1) is 60-80℃, and the drying time is 10-18h.
[0017] Further, the drying temperature in step (1) is 70℃, and the drying time is 10h.
[0018] In the application, the chiral inducer is D-sorbitol.
[0019] In the application, the solvent is ethylene glycol or a mixed solution of ethylene glycol and water.
[0020] In the application, the molar ratio of the non-chiral Bi4O5Br2 nanosheets, Yb2O3, Er2O3 and the chiral inducer is 0.3-0.6:0.04-0.1:0.04-0.1:1-4.
[0021] Further, the molar ratio of the non-chiral Bi4O5Br2 nanosheets, Yb2O3, Er2O3 and the chiral inducer is 0.6:0.1:0.04:3.
[0022] In the application, the temperature of the second hydrothermal reaction in step (2) is 120-180℃, and the reaction time is 3-24h.
[0023] In the present application, the annealing temperature in step (2) is 300-450 DEG C, the heating rate is 5 DEG C / min, and the annealing time is 0.5-5 hours.
[0024] A chiral inorganic bismuth oxyhalide material is prepared by the above method.
[0025] Compared with the prior art, the present application has the following beneficial effects:
[0026] (1) The chiral inorganic bismuth oxyhalide material prepared by the chiral inorganic bismuth oxyhalide material preparation method of the present application has intrinsic chiral structure and strong CD signal, and can directly generate circularly polarized light without an external polarization device.
[0027] (2) The method of the present application can realize controllable adjustment of chiral signal and luminescent performance by adjusting pH value and chiral agent concentration, and has simple preparation method and controllable conditions, and is suitable for batch preparation and morphology control.
[0028] (3) The chiral inorganic bismuth oxyhalide material of the present application has upconversion luminescent performance, can emit visible circularly polarized light under near-infrared light excitation, and is suitable for deep tissue imaging. BRIEF DESCRIPTION OF DRAWINGS
[0029] Figure 1 is a crystal structure diagram of Bi4O5Br2 material;
[0030] Figure 2 is an XRD pattern of Bi4O5Br2:Yb 3+ ,Er 3+ material prepared by the un-complexed chiral material and the complexed chiral material in Example 1 and 2 under different pH values;
[0031] Figure 3 is a SEM morphology diagram of Bi4O5Br2:Yb 3+ ,Er 3+ material prepared by the un-complexed chiral material and the complexed chiral material in Example 1;
[0032] Figure 4 is an absorption spectrum of Bi4O5Br2:Yb 3+ ,Er 3+ material prepared by the un-complexed chiral material and the complexed chiral material in Example 1;
[0033] Figure 5 is an absorption spectrum of Bi4O5Br2:Yb 3+ ,Er 3+ material prepared by the complexed chiral material under different pH values in Example 2;
[0034] Figure 6The CD signal spectra of the uncomposite chiral materials and the composite chiral materials in Examples 1 and 2 at different pH values are shown.
[0035] Figure 7 Bi4O5Br2:Yb prepared in Example 1 with and without chiral material composites 3+ Er 3+ CPL spectrum of the material;
[0036] Figure 8 Bi4O5Br2:Yb prepared after combining chiral materials in Example 1 3+ Er 3+ The material DP8-Bi4O5Br2:Yb is excited at 980 nm with polarizer and quarter-wave plate optical axis angles of α = 45° (LL) or α = -45° (RR). 3+ Er 3+ The photoluminescence spectrum of the sample;
[0037] Figure 9 Bi4O5Br2:Yb prepared after combining chiral materials in Example 1 3+ Er 3+ The material is excited at 980 nm with an angle of α = 45° between the polarizer and the QWP optical axis, and an angle of α = -45° between the depolarizer and the QWP optical axis. The QWP optical axis direction is α = -45° (LR), or the angle between the polarizer and the QWP optical axis is α = -45° (RL), and the angle between the depolarizer and the QWP optical axis is α = 45° (RL). 3+ Er 3+ The photoluminescence spectrum of the sample;
[0038] Figure 10 Bi4O5Br2:Yb prepared in Example 1 without chiral material and with different amounts of chiral material. 3+ Er 3+ The upconversion photoluminescence spectrum of the material;
[0039] Figure 11 Bi4O5Br2:Yb prepared from the composite chiral material in Example 2 at different pH values 3+ Er 3+ The upconversion photoluminescence spectrum of the material. Detailed Implementation
[0040] The present invention will be further described below with reference to specific embodiments, so that those skilled in the art can better understand and implement the technical solutions of the present invention.
[0041] The application provides an inorganic chiral bismuth oxyhalide upconversion circularly polarized luminescent material, which has a general chemical formula of D x P n -Bi4O5Br2:Yb 3+ ,Er 3+ , wherein D x represents a chiral configuration and a concentration, X represents a D-sorbitol (D-Sor) concentration of 0-4 mmol, P n represents n in a synthesis process (n=0-12), Yb 3+ and Er 3+ are doped rare earth ions, and the concentrations are 0.05-0.5 mmol and 0.01-0.05 mmol respectively.
[0042] In the application, the material has a two-dimensional sheet structure, obvious chiral CD signals and upconversion circularly polarized luminescent performance. The chiral Bi4O5Br2 material with upconversion circularly polarized luminescent performance is a two-dimensional sheet structure powder material.
[0043] Example 1
[0044] A chiral inorganic bismuth oxyhalide material preparation method comprises the following steps:
[0045] (1) 10 mmol of Bi (NO3) 3.5H2O and 5 mmol of KBr are weighed and dissolved in 30 mL of ethylene glycol (EG) to be stirred for 30 min; 13 mL of a mixture of deionized water and 1 mL of ammonia water is slowly added to adjust pH=8, and the stirring is continued for 30 min; the mixture is transferred into a 100 mL polytetrafluoroethylene reaction kettle, and reaction is carried out at 180℃ for 3 h; after cooling, centrifugal washing and drying at 70℃ for 12 h, non-chiral Bi4O5Br2 nanosheets (AP n -Bi4O5Br2, A represents no chiral material) are obtained;
[0046] (2) 0.6 mmol of AP n -Bi4O5Br2, 0.04 mmol of Er2O3 and 0.1 mmol of Yb2O3 are dissolved in 40 mL of concentrated nitric acid, and after cooling, 16 mL of EG and 4 mL of water are added, and the stirring is continued for 30 min; 2 mmol, 3 mmol and 4 mmol of D-sorbitol are respectively added, and the stirring is continued for 30 min; the mixture is transferred into a reaction kettle to be reacted at 160℃ for 12 h; after the product is centrifugally washed, annealing is carried out in air at 410℃ for 3.5 h, and a chiral inorganic bismuth oxyhalide material (DP8-Bi4O5Br2:Yb 3+ ,Er 3+ ) is obtained.
[0047] In the above process, Bi(NO3)3.5H2O, D-sorbitol (D-SOR) and NaBr are used as raw materials, and are configured in a molar ratio of Bi ion:D-SOR:Br ion = 1:3.5:1. All raw materials are dissolved in an aqueous solution of ethylene glycol, and the above solution is added to a container and stirred to be uniformly mixed, and then transferred into a hydrothermal reactor with a polytetrafluoroethylene lining, and the filling degree is 0.8.
[0048] Performance test 1
[0049] The material structure, morphology, chirality and luminescent performance are verified by XRD, SEM, CD, UCL, CPL, PL and other characterization methods.
[0050] Bi4O5Br2 belongs to a monoclinic system, and presents a layered staggered structure: the positively charged (Bi2O2) 2+ layer and the double Br - layer are alternately arranged by van der Waals force, and form a periodic two-dimensional layered morphology along the c-axis direction of the crystal (as shown in Figure 1 , the purple polyhedron represents a Bi-O coordination unit, and the light purple sphere corresponds to a Br atom). The characteristics of this structure are: there is a built-in electric field between the layers, which can promote the separation of photo-generated carriers; at the same time, it is easy to form an ultrathin nanosheet morphology, and the exposed high-activity crystal face provides rich reaction sites, and the narrow band gap of about 2.3 eV makes it exhibit excellent performance in the fields of optics and catalysis.
[0051] X-ray diffraction is used to analyze the Bi4O5Br2:Yb 3+ , Er 3+ materials prepared before and after modification of the chiral material, and the XRD spectrum is as shown in Figure 2 . From the XRD results, it can be seen that the standard diffraction peaks of Bi4O5Br2:Yb 3+ , Er 3+ appear before and after modification of the chiral material, and the peak positions correspond to the standard PDF card. After modification of the chiral material, the standard diffraction peaks of Bi4O5Br2:Yb 3+ , Er 3+ are more sharp and have higher peak intensity, and the crystallinity of the Bi4O5Br2:Yb 3+ , Er 3+ material is better.
[0052] As shown in Figure 3 , the SEM images of the Bi4O5Br2:Yb 3+ , Er 3+ material before and after modification of the chiral material. It can be seen that the material before modification of the chiral material presents an unordered nanosheet layered structure as shown in Figure 3 a, and after modification of the chiral material, the Bi4O5Br2:Yb 3+ , Er3+ The morphology of the material is a nano-sheet structure which is thinner, more stereoscopic, ordered and grows in the same direction as shown in Figure 3
[0053] Compared with A-Bi4O5Br2:Yb 3+ ,Er 3+ , D3-Bi4O5Br2:Yb 3+ ,Er 3+ shows red shift of the absorption band edge and absorption enhancement in the whole wavelength range. This phenomenon may be attributed to the complexation of chiral materials, resulting in distortion of the Bi4O5Br2 structure as shown in Figure 4
[0054] The chiral-modified and unmodified Bi4O5Br2:Yb 3+ ,Er 3+ materials were tested by a circular dichroism instrument. It was found that the Bi4O5Br2:Yb 3+ ,Er 3+ material without chiral modification had no CD signal, and the CD signal of the inorganic material Bi4O5Br2:Yb 3+ ,Er 3+ after chiral modification was negative and the peak value was obvious, which proved that the chiral modification endowed the inorganic material Bi4O5Br2:Yb 3+ ,Er 3+ with the properties of chirality, and made the inorganic material Bi4O5Br2:Yb 3+ ,Er 3+ have upconversion circularly polarized luminescence performance as shown in Figure 6
[0055] Figure 7 CPL spectra of Bi4O5Br2:Yb 3+ ,Er 3+ materials before and after modification by chiral material D-SOR. It can be seen that there is no circularly polarized luminescence phenomenon in Bi4O5Br2:Yb 3+ ,Er 3+ material without doping chiral D-SOR, and after modification by chiral material D-SOR, Bi4O5Br2:Yb 3+ ,Er 3+ exists obvious circularly polarized luminescence phenomenon. It is proved that chiral D-SOR and inorganic material Bi4O5Br2:Yb 3 + ,Er 3+ are successfully complexed, and the inorganic nanomaterial is endowed with circularly polarized performance by chiral material modification.
[0056] When the angle between the polarizer and the optical axis of the quarter-wave plate (QWP) is α = 45° (LL) or α = -45° (RR), the luminescence intensity of LL is obviously lower than that of RR for the DP8-Bi4O5Br2 sample. When the angle between the polarizer and the optical axis of the quantum optical element is α = 45°, the angle between the analyzer and the optical axis of the quantum optical element is α = -45° (LR). Conversely, when the angle between the polarizer and the optical axis of the QWP is α = -45°, the angle between the analyzer and the optical axis of the QWP is α = 45° (RL). The luminescence intensity of DP8-Bi4O5Br2 of RL is higher than that of LR under 980 nm excitation, as shown in Figure 8 and Figure 9 .
[0057] As shown in Figure 10 , the upconversion luminescence of the inorganic material Bi4O5Br2:Yb 3+ ,Er 3+ is weak without modification by the chiral material D-SOR, and the upconversion luminescence performance is enhanced after the addition of the chiral material D-SOR, and the upconversion luminescence of 3 mmol DP8-Bi4O5Br2:Yb 3+ ,Er 3+ is the strongest.
[0058] Example 2
[0059] A method for preparing a chiral inorganic bismuth oxyhalide material, comprising the following steps:
[0060] The step of Example 1 is repeated, and different pH values are adjusted respectively, to prepare a series of DP n -Bi4O5Br2:Yb 3+ ,Er 3+ materials under the conditions of pH 3, 6, 8, 9 and 10.
[0061] Performance test 2
[0062] The structure, morphology, chirality and luminescence performance of the material are verified by characterization methods such as XRD, SEM, CD, UCL and CPL.
[0063] The chiral Bi4O5Br2:Yb 3+ ,Er 3+ materials prepared under different pH values are analyzed by X-ray diffraction, and the XRD pattern is shown in Figure 2 From the XRD results, it can be seen that Bi4O5Br2:Yb 3+ ,Er 3+ materials are synthesized under different pH values, and the diffraction peak positions match the standard PDF card. The crystallinity of DP8-Bi4O5Br2 prepared under the condition of pH 8 is the best.
[0064] DP n -Bi4O5Br2:Yb 3+ Er 3+ absorption spectrum such as Figure 5 As shown, DP prepared at different pH values can be observed. n -Bi4O5Br2:Yb 3+ Er 3+ The absorption is somewhat shifted; at pH 8, DP8-Bi4O5Br2:Yb 3+ Er 3+ The absorption band edge red-shifts and the band gap decreases, DP8-Bi4O5Br2:Yb 3+ Er 3+ It has the strongest absorption and the largest absorption range.
[0065] Figure 6 DP prepared at different pH values n -Bi4O5Br2:Yb 3+ Er 3+ The CD spectrum of the material shows that the chiral modified Bi4O5Br2:Yb 3+ Er 3+ All exhibited significant CD signals, with DP8-Bi4O5Br2 showing the most pronounced CD signal, indicating that the Bi4O5Br2:Yb prepared at pH 8... 3+ Er 3+ The material exhibits the strongest chirality and the best polarization performance.
[0066] After modification with the chiral molecule D-SOR, it was found that the Bi4O5Br2:Yb prepared at pH 8... 3+ Er 3+ The upconversion luminescence properties of the material were superior to those prepared under other pH conditions, indicating that pH 8 is the optimal environment for chiral materials and Bi4O5Br2:Yb 3+ Er 3+ The combination of these factors provides more suitable conditions, enabling a simultaneous improvement in both the upconversion luminescence and circular polarization properties of the material, which is corroborated by the XRD and CD test results. Furthermore, the upconversion luminescence performance of the material is more pronounced under these pH conditions, further demonstrating the optimizing effect of chiral modification on the optical properties of materials in specific environments, such as… Figure 11 As shown.
[0067] The above embodiments of the present application are described in detail, but the embodiments of the present application are not limited to this, and the ordinary skilled in the art can realize the purpose of the present application according to the disclosure of the present application, and any improvement and deformation based on the concept of the present application falls within the protection scope of the present application, and the specific protection scope is recorded in the claims.
Claims
1. A method for preparing chiral inorganic bismuth halide materials, Includes the following steps, characterized in that, Includes the following steps: (1) Dissolve Bi(NO3)3·5H2O and halide salt in solvent, stir and adjust pH to 2-10, carry out a hydrothermal reaction, cool and centrifuge to dry to obtain achiral Bi4O5Br2 nanosheets. (2) Chiral inorganic bismuth oxide material was obtained by mixing non-chiral Bi4O5Br2 nanosheets with Yb2O3, Er2O3 and chiral inducer in a solvent, followed by a second hydrothermal reaction and annealing.
2. The method for preparing chiral inorganic bismuth halide materials according to claim 1, characterized in that, Preparation method of chiral inorganic bismuth halide materials.
3. The method for preparing chiral inorganic bismuth halide materials according to claim 2, characterized in that, The molar ratio of Bi(NO3)3·5H2O to the halide is 1-2:
1.
4. The method for preparing chiral inorganic bismuth halide materials according to claim 3, characterized in that, The temperature of the hydrothermal reaction in step (1) is 120℃~180℃ and the reaction time is 3~24 hours.
5. The method for preparing chiral inorganic bismuth halide materials according to claim 4, characterized in that, In step (1), the drying temperature is 60-80℃ and the drying time is 10-18 hours.
6. The method for preparing chiral inorganic bismuth halide materials according to claim 1, characterized in that, The chiral inducer is D-sorbitol; the solvent is ethylene glycol or a mixture of ethylene glycol and water.
7. The method for preparing chiral inorganic bismuth halide materials according to any one of claims 1-6, characterized in that, The molar ratio of the non-chiral Bi4O5Br2 nanosheets, Yb2O3, Er2O3 and the chiral inducer is 0.3-0.6:0.04-0.1:0.04-0.1:1-4.
8. The method for preparing chiral inorganic bismuth halide materials according to claim 7, characterized in that, The temperature of the secondary hydrothermal reaction in step (2) is 120℃~180℃, and the reaction time is 3~24 hours.
9. The method for preparing chiral inorganic bismuth halide materials according to claim 8, characterized in that, In step (2), the annealing temperature is 300-450℃, the heating rate is 5℃ / min, and the annealing time is 0.5-5 hours.
10. A chiral inorganic bismuth halide material, prepared by the method described in any one of claims 1-9.