Mn (II)-based halide based on fluorescence lifetime temperature measurement, gel film and preparation method thereof

Abstract

The invention belongs to the technical field of luminescent materials and temperature sensing, and particularly relates to Mn (II)-based halide based on fluorescence lifetime temperature measurement, a gel film and a preparation technology thereof. The chemical composition formula of the Mn (II)-based metal halide is CTP2MnCl3Br1, wherein CTP is cyanomethyl triphenyl phosphonium chloride. According to the preparation method, Mn (II)-based metal halide is integrated with a polymer network through in-situ precipitation, and the problems that a traditional film preparation process is highly dependent on a supporting material and the process is tedious are solved. The Mn (II)-based metal halide temperature sensor prepared on the basis of the method shows ultrahigh relative sensitivity (Sr) which can reach 26.368% K <-1 >, and has the advantages of long fluorescence lifetime, strong luminous intensity, excellent test cycle stability and highly repeatable lifetime. The obtained gel film retains the excellent performance of the Mn (II)-based metal halide, and has good flexibility and machinability at the same time. The invention provides a new material and a new way for the development of high-performance and integratable optical temperature sensors.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of luminescent materials and temperature sensing technology, and particularly relates to Mn(II)-based halide, gel film based on fluorescence lifetime thermometry and a preparation method thereof. BACKGROUND

[0002] Temperature measurement plays a crucial role in scientific research, industrial production, daily life, and many other fields. In recent years, with the growing demand for non-contact temperature measurement, fluorescence thermometry has attracted widespread attention due to its unique advantages such as high spatial resolution, remote detection capability, and resistance to electromagnetic interference. This technology is particularly suitable for temperature measurement in harsh environments (such as high-current fields, high-magnetic fields, flammable and explosive fields, and easily-corroded products) and micro-scale targets. Traditional temperature sensing methods, including contact thermometers (such as thermal resistors and thermocouples) and non-contact infrared radiation thermometry, often have significant limitations. These limitations include susceptibility to environmental and electromagnetic interference, limited measurement accuracy (especially for low-cost sensors), the need for frequent calibration, long response time, and poor performance when dealing with sub-micron scale objects, fast-moving targets, or visually obstructed environments. In addition, traditional fluorescence intensity thermometry is susceptible to factors such as excitation light source power fluctuations, sample concentration, light bleaching effects, scattering, and differences in absorption at different wavelengths. Fluorescence lifetime thermometry measures the time constant of the decay of emitted light after excitation to infer temperature. Since fluorescence lifetime is a physical constant, this method effectively avoids the dependence on absolute signal intensity, making it less sensitive to the above interference factors and more reliable and accurate. Li et al. proposed a method for constructing a Te 4+ doped Cs2ScCl5·H2O microcrystals (Li G, Chen X, Wang M, et al. Regulating exciton de‐trapping of Te 4+doped zero-dimensional scandium-halide perovskite for fluorescence thermometry with record high time-resolved thermal sensitivity[J]. Advanced Materials, 2023, 35(44): 2305495.). The strong electron-phonon coupling in the 0D soft lattice results in bright orange STE emission. The rapid asymmetric expansion of the lattice with increasing temperature leads to additional defects, strong exciton-phonon coupling, and low thermal activation energy, which endow the STE with a fast untrapping process and a strong temperature-dependent PL lifetime, which varies by several orders of magnitude from 300 K to 370 K. And the lifetime-based detection is used to monitor the temperature of internal electronic components in a USB flash drive under different working conditions. These results show that low-dimensional luminescent metal halides are ideal candidates for the next generation of fluorescent thermometers, opening up new opportunities for designing high-sensitivity thermometry materials.

[0003] However, achieving high-sensitivity fluorescence lifetime thermometry usually relies on luminescent centers with long fluorescence lifetimes (such as Mn 2+ ions), but traditional host materials (especially inorganic rare-earth fluorescent powders) face challenges in accommodating these luminescent centers. Ion radius mismatch is a key issue, which often leads to luminescent centers being able to be doped at a lower concentration, and too high a concentration will trigger concentration quenching effect - that is, the distance between luminescent centers is too close, through cross-relaxation and other ways to convert excited state energy into non-radiative transitions, resulting in a significant decrease in luminescent efficiency.

[0004] Organic-inorganic hybrid metal halides (OIMHs) are a new class of luminescent materials, which exhibit structural diversity, high photoluminescence quantum yield (PLQY), and easy synthesis. Their unique "host-guest" structure and soft lattice characteristics show great potential in minimizing the ion radius mismatch between the metal lattice and the dopant ions, which is expected to suppress concentration quenching and achieve efficient and even heavy doping of luminescent centers, thus providing an ideal material design idea for high-performance fluorescent temperature measurement. In addition, combining functional luminescent materials with a polymer matrix to form composite films or gels is considered an effective strategy to improve the processing flexibility, environmental stability, and device compatibility of the devices. However, how to uniformly integrate high-sensitivity fluorescent temperature measurement materials into a polymer network through a simple and efficient preparation method while maintaining their excellent temperature measurement performance remains a technical challenge. Therefore, developing a new type of fluorescent lifetime temperature sensing material based on organic-inorganic hybrid metal halides, which should be able to take advantage of the long fluorescence lifetime characteristics to avoid the complex instrument problems required for short lifetime detection, and through successful compounding with a polymer matrix to achieve high sensitivity, high stability, and good device integration, is of great significance for promoting the application of non-contact precise temperature measurement in medical diagnosis, industrial process control, and electronic device monitoring. SUMMARY

[0005] One of the purposes of the present application is to provide a fluorescent lifetime temperature sensing material based on organic-inorganic hybrid metal halides, which should have high luminescence intensity, excellent relative temperature sensitivity, good fluorescence lifetime cycle stability, and good measurement repeatability.

[0006] The second purpose of the present application is to provide an efficient light-cured film preparation method. This method can synthesize a flexible self-supporting gel film suitable for device integration in a very short time (20 s), to solve the problems of complex traditional film preparation process and dependence on support substrates To achieve the above-mentioned purposes of the application, the following technical solutions are adopted: The present application provides a Mn(II)-based halide based on fluorescent lifetime temperature measurement, and the chemical composition formula of the Mn(II)-based halide is CTP2MnCl3Br1, wherein CTP (CyanoMethylTriPhenylPhosphonium Chloride) is cyano-methyl triphenyl phosphonium chloride, 20 H 17 ClNP) is cyano-methyl triphenyl phosphonium chloride C 20 H 17 ClNP.

[0007] The present application also provides a preparation method of the above-mentioned Mn(II)-based halide based on fluorescent lifetime temperature measurement, comprising the following steps: (1) Mixing raw materials: mixing ligand cyano-methyl triphenyl phosphonium chloride C 20 H 17ClNP, MnBr2 and MnCl2 are dissolved in dichloromethane solution in a certain molar ratio; (2) Stirring and dissolving: the mixed solution is stirred and fully reacted until a uniform and clear precursor solution is formed; (3) Crystal growth: the above mixed uniform solution is placed in a constant temperature environment, and green block crystals are precipitated by standing; (4) Post-processing: the crystals are collected by filtration, and washed with ethanol to remove the surface residual solvent, and finally dried in an oven to obtain Mn(II) based halide.

[0008] Further, in step (1), C 20 H 17 The molar ratio of ClNP, MnBr2 and MnCl2 is 4:1:1.

[0009] Further, in step (2), the stirring temperature is ≥60 ℃, and the stirring speed is ≥500 rpm.

[0010] Further, in step (3), the constant temperature is 60-65 ℃.

[0011] The application also provides a gel film, which is an organic-inorganic hybrid metal halide self-supporting gel film based on the principle of fluorescence lifetime for optical temperature sensing, wherein the metal halide is Mn(II) based halide, and the gel film successfully retains the temperature sensing optical properties of the original crystal.

[0012] The application also provides a preparation method of the above gel film, comprising the following steps: (1) Dissolve the ligand C 20 H 17 ClNP, MnBr2 and MnCl2 are dissolved in a hydroxyethyl acrylate HEA monomer solution in a molar ratio of 4:1:1; (2) After sufficient stirring, add a photoinitiator and a crosslinking agent, and then undergo in-situ photopolymerization under ultraviolet light irradiation to form a uniform and transparent gel film.

[0013] Further, in step (2), the photoinitiator is 2,4,6-trimethylbenzoyl-phenyl ethyl phosphonate (TPO).

[0014] Further, in step (2), the crosslinking agent is N,N'-methylene bisacrylamide (MBA).

[0015] Further, in step (2), the wavelength of the ultraviolet light is 365 nm.

[0016] Further, the dissolution temperature is ≥70 ℃, and the stirring speed is ≥600 rpm, and by increasing the dissolution temperature and stirring speed, the dissolution of C20 H 17 Solubility and doping concentration of ClNP, MnBr2 and MnCl2 in HEA monomer.

[0017] Compared with the prior art, the present application has the following advantages: 1. Excellent fluorescence temperature measurement performance: the temperature sensor based on the crystal material exhibits ultra-high relative sensitivity (S r ) up to 26.368% K - -1, and also has long fluorescence lifetime, strong luminescence intensity, excellent test cycle stability and highly repeatable lifetime test results, which makes it possible to provide high-precision and high-reliability optical temperature sensing.

[0018] 2. Preparation process: the preparation method has the characteristics of simple operation, mild conditions, low equipment cost and environmental friendliness, is easy to scale up, and is expected to bring significant social and economic benefits, and has broad application prospects.

[0019] 3. Excellent material integration and application potential: the obtained gel thin film successfully retains the excellent temperature sensing optical properties of the original crystal, and also has good flexibility and processability. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Crystal structure of CTP2MnCl3Br1 prepared in Example 1.

[0021] Figure 2 XRD of CTP2MnCl3Br1 crystal prepared in Example 1 and gel thin film prepared in Example 4.

[0022] Figure 3 Excitation spectrum and emission spectrum of CTP2MnCl3Br1 crystal prepared in Example 1 and gel thin film prepared in Example 4.

[0023] Figure 4 Lifetime decay spectrum of CTP2MnCl3Br1 crystal prepared in Example 1 and gel thin film prepared in Example 4.

[0024] Figure 5 Temperature-dependent emission spectrum of CTP2MnCl3Br1 prepared in Example 1.

[0025] Figure 6 Temperature-dependent lifetime decay spectrum of CTP2MnCl3Br1 prepared in Example 1.

[0026] Figure 7 Absolute sensitivity S a and relative sensitivity Sr Temperature-dependent emission spectra.

[0027] Figure 8 Temperature-dependent emission spectra of the gel thin film prepared in Example 4.

[0028] Figure 9 Temperature-dependent lifetime decay profiles of the gel thin film prepared in Example 4.

[0029] Figure 10 Photograph of the gel thin film prepared in Example 4. DETAILED DESCRIPTION

[0030] The present application will be further clarified by the following examples, which should be considered as merely illustrative of the present application and not limiting thereof. Modifications of the various embodiments of the present application, as well as other embodiments of the present application, which are apparent to those of ordinary skill in the art, are to be considered within the scope of the present application as defined by the appended claims.

[0031] Example 1 According to the organic cation cyanomethyltriphenylphosphonium chloride C 20 H 17 The molar feed ratio of ClNP, MnBr2and MnCl2was 4:1:1. Each reactant was accurately weighed and dissolved in an inert dichloromethane solvent. The mixed solution was placed in a 60 °C constant temperature environment and reacted under continuous mechanical stirring at 500 rpm until a uniform and clear precursor solution was formed. Subsequently, the precursor solution was transferred to a 60 °C constant temperature table and left to stand for 12 hours, and the green block crystals were precipitated by inducing crystal nucleation and growth through slow solvent evaporation. After the crystal product was separated by filtration, it was washed with ethanol to remove the residual solvent and soluble impurities on the surface, and finally dried in a 60 °C oven to obtain the final product with high purity.

[0032] Example 2 According to the organic cation cyanomethyltriphenylphosphonium chloride C 20 H 17 The molar feed ratio of ClNP, MnBr2and MnCl2was 4:1:1. Each reactant was accurately weighed and dissolved in an inert dichloromethane solvent. The mixed solution was placed in a 60 °C constant temperature environment and reacted under continuous mechanical stirring at 500 rpm until a uniform and clear precursor solution was formed. Subsequently, the precursor solution was transferred to a 60 °C constant temperature table and left to stand for 12 hours, and the green block crystals were precipitated by inducing crystal nucleation and growth through slow solvent evaporation. After the crystal product was separated by filtration, it was washed with ethanol to remove the residual solvent and soluble impurities on the surface, and finally dried in a 60 °C oven to obtain the final product with high purity.

[0033] Example 3 According to the organic cation cyanomethyltriphenylphosphonium chloride C 20 H 17 ClNP, MnBr2and MnCl24:1:1 molar feed ratio, each reactant was accurately weighed and dissolved in an inert dichloromethane solvent. The mixed solution was placed in a 70 °C constant temperature environment and reacted under continuous mechanical stirring at 700 rpm until a uniform and clear precursor solution was formed. Subsequently, the precursor solution was transferred to a 65 °C constant temperature table and left to stand for 12 hours to induce crystal nucleation and growth by slow solvent evaporation, and green block crystals were precipitated. After the crystal product was separated by filtration, it was washed with ethanol to remove surface residual solvent and soluble impurities, and finally dried in a 60 °C oven to obtain a high-purity final product.

[0034] The crystals grown in Examples 1 and 2 were transparent, but the crystals in Example 3 were whitish, and the constant temperature table temperature was too high to grow crystals.

[0035] The crystal structure of CTP2MnCl3Br1 prepared in Example 1 is shown in Figure 1 , and the crystal space group is P21 / n, belonging to 0 D structure. The XRD pattern Figure 2 shows that the diffraction peaks of the obtained crystal are highly consistent with the theoretical diffraction spectrum obtained by single crystal analysis, indicating that the product has high crystallinity and phase purity; the optical properties of the crystal were analyzed by fluorescence spectrum test Figure 3 . Under 450 nm light excitation, the crystal showed a narrow band emission at 520 nm, which was attributed to the Mn 2+ ion 4 T1→ 6 A1 transition, with typical manganese ion characteristic emission properties. The fluorescence lifetime decay curve Figure 4 shows that the crystal has a long fluorescence lifetime (τ>1 ms) at room temperature, which is consistent with the luminescence behavior of Mn 2+ in a rigid lattice, laying a foundation for its application in fluorescence lifetime thermometry. To evaluate the temperature sensing properties of the crystal, variable-temperature fluorescence spectrum and variable-temperature lifetime tests were performed. Figure 5 As shown, the emission spectrum of the material does not show a more obvious broadening or emission peak shift with temperature change, indicating that the material is mainly characterized by Mn 2+ emission, and there is no self-trapped exciton emission. Figure 6 The PL lifetime of the material also shows strong temperature dependence. By analyzing the relationship between fluorescence lifetime and temperature, the absolute sensitivity (S a ) and relative sensitivity (S r ) of the material were calculated. As Figure 7As shown, the crystal exhibits the highest relative sensitivity at 463 K, with a S value of 26.368% K -1 , indicating that it has excellent temperature response performance and is suitable for high-precision optical temperature sensing.

[0036] Example 4 For the pure polymer poly(hydroxyethyl acrylate) (PHEA), the preparation process includes: dissolving the photoinitiator 2,4,6-trimethylbenzoyl-phenyl ethyl phosphonate (TPO) and the crosslinking agent N,N'-methylene bisacrylamide (MBA) in the hydroxyethyl acrylate (HEA) monomer solution at 70 °C and 800 rpm, and performing curing polymerization under 365 nm ultraviolet light irradiation.

[0037] For the preparation of the functionalized gel film, the ligand C 20 H 17 ClNP (cyanomethyltriphenylphosphonium chloride), MnBr2 and MnCl2 are dissolved in the HEA monomer solution, and after thorough stirring, the photoinitiator TPO and the crosslinking agent N,N'-methylene bisacrylamide (MBA) are added, followed by in-situ photopolymerization under ultraviolet light irradiation to form a uniform transparent gel film.

[0038] The ligand cyanomethyltriphenylphosphonium chloride (C 20 H 17 ClNP), MnBr2 and MnCl2 are accurately weighed in a molar ratio of 4:1:1, dissolved in the HEA monomer solution at 70 °C and 800 rpm, and after thorough stirring, the photoinitiator TPO and the crosslinking agent MBA are added, and after thorough mixing, in-situ photopolymerization is performed under 365 nm ultraviolet light irradiation to form an organic-inorganic hybrid metal halide / polymer composite gel film.

[0039] To improve the solubility and doping concentration of C 20 H 17 ClNP and MnX2 in HEA, the solubility temperature or stirring speed can be increased (temperature ≥ 70 °C, speed ≥ 600 rpm). Example 5 For the pure polymer poly(hydroxyethyl acrylate) (PHEA), the preparation process includes: dissolving the photoinitiator 2,4,6-trimethylbenzoyl-phenyl ethyl phosphonate (TPO) and the crosslinking agent N,N'-methylene bisacrylamide (MBA) in the hydroxyethyl acrylate (HEA) monomer solution at 80 °C and 900 rpm, and performing curing polymerization under 365 nm ultraviolet light irradiation.

[0040] For the preparation of the functionalized gel film, the ligand C20 H 17 ClNP (cyanomethyltriphenylphosphonium chloride), MnBr2 and MnCl2 were dissolved in HEA monomer solution, after fully stirring, the photoinitiator TPO and crosslinking agent N,N'-methylene bisacrylamide (MBA) were added, then in-situ photopolymerization reaction occurred under UV light irradiation, forming a uniform transparent gel film.

[0041] The ligand cyanomethyltriphenylphosphonium chloride (C 20 H 17 ClNP), MnBr2 and MnCl2 were dissolved in HEA monomer solution at 80 ℃ and 900 rpm, after fully stirring, the photoinitiator TPO and crosslinking agent MBA were added, after fully mixing, in-situ photopolymerization reaction was carried out under 365 nm UV light irradiation, forming an organic-inorganic hybrid metal halide / polymer composite gel film.

[0042] Example 6 For pure polymer polyhydroxyethyl acrylate (PHEA), the preparation process includes: dissolving the photoinitiator 2,4,6-trimethylbenzoyl-phenyl ethyl phosphonate (TPO) and the crosslinking agent N,N'-methylene bisacrylamide (MBA) in the hydroxyethyl acrylate (HEA) monomer solution at 90 ℃ and 1000 rpm, and curing polymerization under 365 nm wavelength UV light irradiation.

[0043] For the preparation of functionalized gel film, first, the ligand C 20 H 17 ClNP (cyanomethyltriphenylphosphonium chloride), MnBr2 and MnCl2 were dissolved in HEA monomer solution, after fully stirring, the photoinitiator TPO and crosslinking agent N,N'-methylene bisacrylamide (MBA) were added, then in-situ photopolymerization reaction occurred under UV light irradiation, forming a uniform transparent gel film.

[0044] The ligand cyanomethyltriphenylphosphonium chloride (C 20 H 17 ClNP), MnBr2 and MnCl2 were dissolved in HEA monomer solution at 90 ℃ and 1000 rpm, after fully stirring, the photoinitiator TPO and crosslinking agent MBA were added, after fully mixing, in-situ photopolymerization reaction was carried out under 365 nm UV light irradiation, forming an organic-inorganic hybrid metal halide / polymer composite gel film.

[0045] Increasing the stirring speed and temperature is conducive to obtaining the precursor solution faster, but too high solution temperature is not conducive to subsequent operation, and good experimental protection needs to be done.

[0046] The phase composition of the gel film prepared in Example 4 was analyzed using X-ray diffraction (XRD). Figure 2 As shown, the XRD pattern of the gel film retains the main diffraction peaks of the original crystal, indicating that the hybrid metal halide was successfully embedded in the polymer network and maintained its crystal structure integrity. Figure 3 The emission spectrum showed that the gel film exhibited significant Mn content at 520 nm. 2+ The characteristic emission peaks and the fact that its fluorescence lifetime is similar to that of the original crystal confirm that the gel film has good luminescence retention capabilities. Fluorescence lifetime decay curve ( Figure 4 The results show that the gel film exhibits a long fluorescence lifetime (τ>1 ms) at room temperature, preserving the luminescence behavior characteristics of the original crystal, thus laying the foundation for its application in fluorescence lifetime thermometry. Furthermore, as... Figure 8 , 9 As shown, the temperature-dependent emission spectrum and lifetime of the gel film were tested. The gel film retained the excellent temperature-sensitive properties of the crystal; within the tested temperature range, the lifetime value was similar to that of the corresponding crystal, exhibiting strong temperature dependence. For practical applications, the flexibility of the gel film is also crucial, such as... Figure 10 As shown, the gel film has good flexibility.

[0047] In summary, compared with the prior art, the present invention has the following advantages: 1. Superior fluorescence thermometry performance: Temperature sensors based on this crystal material exhibit ultra-high relative sensitivity (S0). r It can reach 26.368% K -1 It also features long fluorescence lifetime and excellent temperature dependence, making it possible to achieve high-precision and high-reliability optical temperature sensing.

[0048] 2. Preparation process: The preparation method is characterized by simple operation, mild conditions, low equipment cost and environmental friendliness. It is easy to scale up production and is expected to bring significant social and economic benefits, and has broad prospects for promotion and application.

[0049] 3. Excellent material integration and application potential: The obtained gel film successfully retains the excellent temperature sensing optical properties of the original crystal, while also possessing good flexibility.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A Mn(II)-based halide based on fluorescence lifetime thermometry, characterized in that, The chemical formula of the Mn(II)-based halide is CTP2MnCl3Br1, where CTP is cyanomethyltriphenylphosphine chloride C. 20 H 17 ClNP.

2. A method for preparing Mn(II)-based halides based on fluorescence lifetime thermometry as described in claim 1, characterized in that, Includes the following steps: (1) Raw material mixing: The ligand cyanomethyltriphenylphosphine chloride C 20 H 17 ClNP, MnBr2 and MnCl2 are dissolved in a dichloromethane solution in a certain molar ratio; (2) Stirring and dissolving: Stir the mixed solution to allow it to react fully until a homogeneous and clear precursor solution is formed; (3) Crystal growth: The above-mentioned uniformly mixed solution is placed in a constant temperature environment and left to stand, and green blocky crystals precipitate out; (4) Post-processing: The crystals were collected by filtration and washed with ethanol to remove residual solvent on the surface. Finally, they were dried in an oven to obtain Mn(II)-based halides.

3. The preparation method according to claim 2, characterized in that, In step (1), the C 20 H 17 The molar ratio of ClNP, MnBr2 and MnCl2 is 4:1:

1.

4. The preparation method according to claim 2, characterized in that, In step (2), the stirring temperature is ≥60 ℃ and the stirring speed is ≥500 rpm.

5. The preparation method according to claim 2, characterized in that, In step (3), the constant temperature is 60-65℃.

6. A gel film, characterized in that, The gel film is an organic-inorganic hybrid metal halide self-supporting gel film based on the fluorescence lifetime principle for optical temperature sensing, wherein the metal halide is a Mn(II)-based halide; the gel film successfully retains the temperature-sensing optical properties of the original crystalline Mn(II)-based halide.

7. A method for preparing a gel film as described in claim 6, characterized in that, Includes the following steps: (1) Ligand C 20 H 17 ClNP, MnBr2 and MnCl2 are dissolved in a hydroxyethyl acrylate (HEA) monomer solution in a molar ratio of 4:1:1 and stirred thoroughly. (2) After thorough stirring, add photoinitiator and crosslinking agent, and then conduct in-situ photopolymerization reaction under ultraviolet light irradiation to form a uniform and transparent gel film.

8. The preparation method according to claim 7, characterized in that, In step (1), the dissolution temperature is ≥70 ℃ and the stirring speed is ≥600 rpm. Increasing the dissolution temperature and stirring speed can effectively increase C. 20 H 17 Solubility and doping concentration of ClNP, MnBr2 and MnCl2 in HEA monomer.

9. The preparation method according to claim 7, characterized in that, In step (2), the photoinitiator is ethyl 2,4,6-trimethylbenzoyl-phenylphosphonate (TPO); the crosslinking agent is N,N'-methylenebisacrylamide (MBA).

10. The preparation method according to claim 7, characterized in that, In step (2), the ultraviolet light wavelength is 365nm.

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