Self-calibration fluorescent temperature sensing material suitable for low temperature, and preparation method and application thereof

Abstract

The application discloses a kind of self-calibration fluorescent temperature sensing materials suitable for low temperature and preparation method and application thereof, belong to temperature sensing, coordination chemistry and numerous technical fields such as organic luminescent dye.The structure general formula of this material is: [AlO5C8H5·X n ], wherein AlO5C8H5 is metal organic framework MIL-53 (Al), X is luminescent dye, 0 < n ≤ 6;Its preparation method is simple, using metal framework and luminescent dye is completed in one step, reaction condition is mild, and luminescent efficiency is high, simultaneously has the double excimer emission peak of dye, and the intensity ratio of two peaks has good function relationship with temperature, and sensitivity can reach 1.2%K ‑1 , can realize self-calibration temperature detection, can avoid the influence generated by excitation light source and detector such as experimental factor, and can be used as a kind of new temperature sensing material in low temperature sensing field and obtain practical application.

Description

Technical Field

[0001] This invention belongs to many technical fields such as temperature sensing, coordination chemistry and organic light-emitting dyes, and specifically relates to a self-calibrating fluorescent temperature sensing material suitable for low temperature and its preparation method. Background Technology

[0002] Temperature is a crucial physical parameter in scientific research and industrial production. Traditional temperature detectors often fall short in various extreme environments (strong electromagnetic fields, extremely low fields, high-speed moving targets, etc.), leading researchers to actively develop novel temperature detection methods that have gained significant attention in recent years. Compared to traditional temperature detectors, fluorescence temperature detectors offer advantages such as high sensitivity, high response, resistance to electromagnetic interference, and non-contact measurement, making them promising candidates for meeting the requirements of extreme low-temperature environments, biological conditions, and high-speed moving target temperature detection.

[0003] Metal-organic frameworks (MOFs) are a rapidly developing class of novel porous crystalline materials formed by the self-assembly of metal ions or metal clusters with organic bridging ligands through coordination interactions. MOFs combine the characteristics of both inorganic and organic materials, thus exhibiting a wider variety of physicochemical properties. Researchers have obtained luminescent MOFs by introducing luminescent metal centers and organic ligands. Luminescent MOFs are highly promising functional materials with potential applications in nonlinear optics, photocatalysis, electroluminescent devices, biomedical imaging, and fluorescence sensors. Compared to purely organic or inorganic luminescent materials, luminescent MOFs exhibit exceptional luminescent performance. Structurally, this is due to the crystalline porous structure of MOFs, allowing for rich combinations by adjusting pore size and altering ligand structure.

[0004] By rationally selecting organic dyes as luminescent centers, metal-organic framework-dye composite materials exhibiting dye multiple exciton association emission that are temperature-sensitive can be obtained. This provides a new and convenient approach for developing novel fluorescent temperature-sensing materials with self-calibrating properties. Currently, there are few reports exploring the fluorescent temperature-sensing characteristics of related materials, and there is significant room for improvement in their similar temperature sensitivity ranges. Summary of the Invention

[0005] The purpose of this invention is to provide a self-calibrating fluorescence sensing material with high sensitivity, suitable for low-temperature detection. Another technical problem to be solved by this invention is to provide a method for preparing a self-calibrating fluorescence temperature sensing material, which is simple, green, safe and environmentally friendly.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A self-calibrating fluorescence temperature sensing material suitable for low temperatures, the general structural formula of which is: [AlO5C8H5·X n In the formula, AlO5C8H5 is a metal-organic framework MIL-53(Al), X is a luminescent dye, and 0 <n≤6。

[0008] Preferably, the luminescent dye is selected from any one of fluoranthene, tetraphenylene, pentaphenylene, phenazine, perylene, pyrene, triphenylene, fluorene, 9,9-dimethylfluorene, oxofluorene, thiofluorene, 2,3-benzo[a]fluorene, 1,2-benzo[a]fluorene, and 6,12-dihydroindeno[1,2-b]fluorene, with the following structural formula:

[0009]

[0010] A method for preparing a self-calibrating fluorescent temperature sensing material suitable for low temperatures involves uniformly mixing a luminescent dye with a metal-organic framework MIL-53(Al), placing the mixture in a vacuum or a solvent of a certain volume, immersing the mixture in a sealed reaction tube for full reaction, and cooling it to room temperature to obtain a metal-organic framework-dye composite material.

[0011] Preferably, the solvent is selected from one or two of water, methanol, ethanol, n-propanol, isopropanol, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0012] Preferably, the molar ratio between the luminescent dye and the metal-organic framework MIL-53(Al) is 0.5 to 10:1.

[0013] Preferably, the reaction temperature is 50–200°C and the reaction time is 1–3 days.

[0014] Preferably, the solvent dosage is 1–100 mL / g MIL-53(Al).

[0015] The method for preparing a self-calibrating fluorescent temperature sensing material suitable for low temperatures, and the resulting self-calibrating fluorescent temperature sensing material.

[0016] The application of the self-calibrated fluorescence intensity sensing material in fluorescence temperature detection in the low-temperature region.

[0017] The application of the self-calibrated fluorescence intensity sensing material in fluorescence temperature detection in the low-temperature region is as follows: the spectrum of the fluorescence temperature sensing material coated on the surface of the object to be tested is obtained by a fiber optic spectrometer, and the spectrometer further converts the ratio of luminescence intensity into absolute temperature.

[0018] Compared with existing technologies, the advantages of this invention are:

[0019] (1) The metal-organic framework-dye composite material of the present invention has a simple structure and excellent performance, and does not require the use of rare earth metals and complex organic dyes.

[0020] (2) The metal-organic framework-dye composite material of the present invention has a simple preparation process, does not require harsh conditions, and has low energy consumption;

[0021] (3) The metal-organic framework-dye composite material of the present invention has high luminescence efficiency and also has the emission peaks of the dual excito-association of dyes. The intensity ratio of the two peaks has a clear functional relationship with temperature, and the relative sensitivity of temperature measurement can reach up to 1.01% K. -1 It can achieve self-calibrated temperature detection, avoid the influence of experimental factors such as excitation light source and detector, and can be used as a new type of temperature sensing material in the field of low temperature sensing. Attached Figure Description

[0022] Figure 1 The powder diffraction pattern of the fluorescent temperature sensing material prepared in this invention;

[0023] Figure 2 Thermogravimetric curve of the fluorescent temperature sensing material prepared in this invention;

[0024] Figure 3 Nitrogen adsorption / desorption curves of the fluorescent temperature sensing material prepared in this invention;

[0025] Figure 4 The Raman spectrum of fluorene@MIL-53 in the fluorescent temperature sensing material of Example 1;

[0026] Figure 5 The Raman spectrum of fluoranthene@MIL-53 in the fluorescent temperature sensing material of Example 2;

[0027] Figure 6 The Raman spectrum of benzene@MIL-53 in the metal-organic framework-dye composite material of Example 3 is shown.

[0028] Figure 7 The graph shows the relationship between the ratio of the luminescence intensity at the two maximum emission wavelengths of the metal-organic framework-dye composite material prepared in Example 1 and temperature.

[0029] Figure 8 The graph shows the relative sensitivity of the metal-organic framework-dye composite material prepared in Example 1 at different temperatures. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below with reference to specific embodiments. Unless otherwise specified, the technical means used in the following embodiments are all conventional means well known to those skilled in the art.

[0031] Example 1

[0032] (1) Mix 0.1 mmol of fluorene and 0.1 mmol of MIL-53 (Al) and grind them to make them evenly mixed. Then put the mixture into a vacuum reaction tube and remove the air in the tube to keep it under vacuum.

[0033] (2) The reaction vessel was placed at 100°C for 3 days. After cooling, it was washed with solvent and dried to obtain a milky white powdery metal-organic framework-fluoranthene composite material with a yield of 80%.

[0034] Example 2

[0035] (1) Add 0.1 mmol of fluoranthene and 0.5 mmol of MIL-53(Al) to 6 mL of ethanol, and after they are evenly dispersed, add 0.5 mL of dimethylformamide.

[0036] (2) Stir the solution to make the solvent evenly mixed and MIL-53(Al) fully dispersed, then put the solution into a hydrothermal reactor and seal the reactor; place the reactor at 200℃ for 1 day, and after cooling, filter to obtain a light yellow powder metal-organic framework-fluoranthene composite material with a yield of 90%.

[0037] Example 3

[0038] (1) Add 0.1 mmol of benzene and 0.5 mmol of MIL-53(Al) to 6 mL of N-methylpyrrolidone and sonicate to disperse the mixture evenly.

[0039] (2) The solution was placed in a hydrothermal reactor and the reactor was sealed. The reactor was placed at 120°C for 2 days. After cooling, it was filtered to obtain a yellow powdery metal-organic framework-benzene composite material with a yield of 75%.

[0040] like Figure 1 As shown, the obtained fluorescent thermometric material still has the same framework structure as MIL-53(Al).

[0041] like Figure 2 and Figure 3 As shown, it can be determined that the luminescent dye enters the channels of MIL-53(Al) in the fluorescent thermometric material, and the content of the luminescent dye is also indicated.

[0042] like Figure 4 , Figure 5 and Figure 6 As shown, the fluorescent material exhibits Raman peaks of both MIL-53(Al) and the corresponding luminescent dye, which, in another respect, indicates that the fluorescent material is indeed composed of these two components.

[0043] comprehensive Figures 1-6 This can explain the structure of the fluorescent thermometric material. It is not a simple mixture of MIL-53(Al) and the corresponding luminescent dye, but a composite material formed by the luminescent dye entering the pores of MIL-53(Al).

[0044] In Examples 1-3, the emission peak at 560 nm in the excimer spectrum of the dye exhibited high luminescence efficiency at 77 K, while the opposite was true at room temperature. The luminescence intensity of the emission peak at 560 nm decreased rapidly with increasing temperature, while the luminescence intensity of the emission peak at 500 nm decreased slowly with increasing temperature. Figure 7 As shown, the ratio of the integral areas of these two emission peaks exhibits a good functional relationship with temperature, where T is the absolute temperature and I... 560 I represents the intensity of the emission peak at 560 nm. 500 The intensity of the emission peak at 500 nm can be fitted to this function using the following formula:

[0045] I 560 / I 500 =62.2T -0.776

[0046] like Figure 8 As shown, the sensitivity at the corresponding temperature gradually decreases with increasing temperature. Within the range of 77-353 K, the sensitivity of the bimodal intensity ratio of this metal-organic framework-dye composite material to temperature can reach 1.01% K. -1 Therefore, this material can achieve fluorescence temperature detection in the low-temperature region.

[0047] 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 should be included within the scope of protection of the present invention.

Claims

1. A self-calibrating fluorescent temperature sensing material suitable for low temperatures, characterized in that, The general structural formula for self-calibrating fluorescent temperature sensing materials is: [AlO5C8H5·X] n In the formula, AlO5C8H5 is a metal-organic framework MIL-53(Al), X is a luminescent dye, and 0 < n ≤ 6; The luminescent dye is selected from any one of fluoranthene, tetraphenyl, pentaphenyl, benzoxene, perylene, pyrene, triphenylene, fluorene, 9,9-dimethylfluorene, oxyfluorene, thiofluorene, 2,3-benzo[a]fluorene, 1,2-benzo[a]fluorene and 6,12-dihydroindo[1,2-b]fluorene; The self-calibrating fluorescent temperature sensing material suitable for low temperature is prepared by the following steps: uniformly mixing the luminescent dye with the metal-organic framework MIL-53(Al), placing it in a vacuum or solvent, placing the mixture in a sealed reaction tube for full reaction, and cooling it to room temperature to obtain the metal-organic framework-dye composite material; wherein, the reaction temperature is 50-200℃ and the reaction time is 1-3 days.

2. A method for preparing a self-calibrating fluorescent temperature sensing material suitable for low temperatures as described in claim 1, characterized in that, The luminescent dye is uniformly mixed with the metal-organic framework MIL-53(Al) and placed in a vacuum or solvent. The mixture is then placed in a sealed reaction tube for full reaction and cooled to room temperature to obtain the metal-organic framework-dye composite material. The reaction temperature is 50–200°C and the reaction time is 1–3 days.

3. The method for preparing a self-calibrating fluorescent temperature sensing material suitable for low temperatures according to claim 2, characterized in that, The solvent is selected from one or two of water, methanol, ethanol, n-propanol, isopropanol, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylformamide, N-methylpyrrolidone, and dimethyl sulfoxide.

4. The method for preparing a self-calibrating fluorescent temperature sensing material suitable for low temperatures according to claim 2, characterized in that, The molar ratio between the luminescent dye and the metal-organic framework MIL-53(Al) is 0.5 to 10:

1.

5. The method for preparing a self-calibrating fluorescent temperature sensing material suitable for low temperatures according to claim 2, characterized in that, The solvent dosage is 1–100 mL / g MIL-53(Al).

6. The self-calibrating fluorescent temperature sensing material prepared by the method according to any one of claims 2-5.

7. The application of the self-calibrating fluorescence intensity sensing material according to claim 6 in fluorescence temperature detection in the low-temperature region.

8. The application according to claim 7, characterized in that, The process is as follows: the spectrum of the fluorescent temperature sensing material coated on the surface of the object to be tested is obtained by a fiber optic spectrometer, and the spectrometer then converts the ratio of luminescence intensity into absolute temperature.

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