A ratiometric temperature sensor based on 1R2R-ZnSm complex, its preparation method and temperature detection method

Abstract

This invention discloses a ratiometric temperature sensor based on a 1R2R-ZnSm complex, wherein the 1R2R-ZnSm complex is composed of a Schiff base ligand R,R-H2L and Zn 2+ and Sm 3+ The 1R2R-ZnSm complex was obtained by coordination crystallization within a single molecule, and its molecular structure is [R,R-ZnLSm(OAc)(NO3)2]. This invention also discloses a temperature detection method for the aforementioned ratiometric temperature sensor. The ratiometric temperature sensor of this invention has low manufacturing cost, a simple synthesis method, high fluorescence intensity, a wide temperature measurement range, high sensitivity, and a wide range of applications. Its fluorescence color undergoes a significant change, from green to yellowish-green, then to orange, and finally to red, which is observable to the naked eye, exhibiting good fluorescence ratiometric temperature response characteristics.

Description

Technical Field

[0001] This invention relates to the field of materials preparation and analysis technology, and mainly provides a ratiometric temperature sensor based on 1R2R-ZnSm complex, its preparation method and temperature detection method. Background Technology

[0002] Temperature, as a statistical physical quantity reflecting the thermal motion of physical, chemical, and biological processes at different scales, can only be measured by measuring changes in related physicochemical properties. However, industries such as fluid dynamics, microenvironments, marine research, subsurface geochemistry, wind tunnels, automotive, and aerospace often require in-situ measurements of large areas or temperature gradients with high spatial resolution, posing a significant challenge to traditional thermometers. Therefore, molecular ratio fluorescence temperature sensing systems have become a focus of attention. They can provide high visualization and eliminate errors caused by background fluorescence, sensor concentration, and source intensity, while also overcoming the shortcomings of ratio fluorescence thermometers based on widely used doped materials, avoiding complex manufacturing steps or inhomogeneities, and improving temperature sensitivity. Therefore, the development of molecular ratio fluorescence materials is crucial.

[0003] Currently, a wide variety of fluorescence temperature sensors have been discovered, mainly consisting of metal salts, oxides, metal-organic frameworks, nanoclusters / nanocrystals, quantum dots (QDs), organometallic compounds, organic dyes, and polymers. A large portion of these fluorescence thermometry schemes rely on the decrease in emission intensity with increasing temperature, or are based on the temperature response of a single excited state. They are susceptible to factors such as concentration variations and fluctuations in excitation light intensity, and it is difficult to guarantee that changes in fluorescence intensity are entirely due to temperature changes. Furthermore, the synthesis processes are complex, the materials have poor uniformity, the temperature measurement range is narrow, and the sensitivity needs improvement. Summary of the Invention

[0004] In order to overcome the shortcomings of the existing technology, the purpose of this invention is to provide a ratiometric temperature sensor based on 1R2R-ZnSm complex, which avoids the influence of factors such as concentration changes or excitation light intensity fluctuations, and has high accuracy and high sensitivity.

[0005] Another objective of this invention is to provide a method for preparing a ratiometric temperature sensor based on a 1R2R-ZnSm complex.

[0006] Another objective of this invention is to provide a temperature detection method based on a ratiometric temperature sensor of 1R2R-ZnSm complex.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A ratiometric temperature sensor based on a 1R2R-ZnSm complex, wherein the 1R2R-ZnSm complex is composed of Schiff base ligand R,R-H2L and Zn 2+ and Sm 3+ The complex was obtained by coordination crystallization in one molecule; the molecular structure of the 1R2R-ZnSm complex is [R,R-ZnLSm(OAc)(NO3)2].

[0009] Preferably, the ratiometric temperature sensor based on the 1R2R-ZnSm complex contains fluorescence emission peaks from two different sources, namely Zn 2+ fluorescence emission peak and Sm 3+ The fluorescence emission peak of the Sm; 3+ The intensity of the fluorescence emission peak at 644 nm is I 644 With the Zn 2+ The intensity of the fluorescence emission peak at 485 nm is I 485 The relationship between temperature and temperature follows a curve.

[0010] Preferably, the applicable temperature range is 233K-333K.

[0011] Preferably, within the temperature range of 263K-333K, ln(I 644 / I 485 The relationship between temperature and the reciprocal 1 / T is linear. A method for fabricating a ratiometric temperature sensor based on a 1R2R-ZnSm complex includes the following steps:

[0012] Schiff base ligand R,R-H2L was placed in a reaction vessel with samarium nitrate and zinc acetate. After adding methanol, the reaction vessel was sealed and heated in a metal bath. After crystal formation, the crystals were filtered out to obtain the 1R2R-ZnSm complex, which is a ratiometric temperature sensor based on the 1R2R-ZnSm complex.

[0013] Preferably, the molar ratio of the Schiff base ligand R,R-H2L to samarium nitrate and zinc acetate is 1:1:1.

[0014] Preferably, the heating reaction in the metal bath specifically includes:

[0015] Heat to 60℃-80℃ in a metal bath and react overnight.

[0016] Preferably, the following steps are also included:

[0017] The 1R2R-ZnSm complex was prepared into a thin film to obtain a ratiometric temperature sensor based on the 1R2R-ZnSm-PMMA thin film.

[0018] More preferably, the preparation of the 1R2R-ZnSm complex into a thin film specifically involves:

[0019] A ratiometric temperature sensor based on a 1R2R-ZnSm complex was mixed with PMMA using toluene as a solvent and stirred at room temperature to obtain a mixture. A glass plate was placed on a hot stage at 65–75°C, and the mixture was uniformly coated onto the glass plate. After it naturally peeled off, a 1R2R-ZnSm-PMMA thin film was obtained, thus obtaining a ratiometric temperature sensor based on a 1R2R-ZnSm-PMMA thin film.

[0020] A temperature detection method based on a ratiometric temperature sensor of 1R2R-ZnSm complex includes the following steps:

[0021] (1) The fluorescence intensity I of the ratiometric temperature sensor based on the 1R2R-ZnSm complex under 365nm excitation was measured at different temperatures in the range of 233K-333K. 485 and I 644 ;

[0022] (2) Within the temperature range of 233-333K, the ratio of fluorescence intensity I 644 / I 485 By fitting the curve with temperature, a standard regression equation is obtained;

[0023] (3) Ensure the sample to be tested is in full contact with the ratiometric temperature sensor based on the 1R2R-ZnSm complex. After the temperature stabilizes, measure the fluorescence intensity I of the sample under 365nm excitation. 485 and I 644 The ratio of fluorescence intensity I 644 / I 485 The temperature of the sample to be tested is obtained by comparing it with the standard regression equation.

[0024] Preferably, the standard regression equation for a ratiometric temperature sensor based on the 1R2R-ZnSm complex is y = A1exp(X / 28.05) + 0.0405, R 2 =0.9950, where X is the temperature and the detection range is 233K-333K.

[0025] Preferably, the standard regression equation for the ratiometric temperature sensor based on the 1R2R-ZnSm thin film is y=A1exp(X / 74.15)+0.77562, R 2 =0.9983, where X is the temperature and the detection range is 223K-333K.

[0026] The present invention has the following advantages and beneficial effects compared with the prior art:

[0027] This invention relates to a method of coordinating Schiff base ligand R,R-H2L with Zn via crystallization. 2+ Ions and Sm 3+ Ions crystallize within a molecule via coordination bonds, forming a temperature-sensitive molecular complex, 1R2R-ZnSm. The prepared ratiometric temperature sensor based on the 1R2R-ZnSm complex exhibits structural stability and is not easily decomposed. Under excitation light at 365 nm, its fluorescence emission spectrum displays two fluorescence emission peaks from different sources, corresponding to Zn... 2+ The singlet emission peak (485nm) and Sm 3+ The triple fluorescence emission peaks of Zn (550nm, 599nm, 644nm) are observed; as the temperature gradually increases, Zn... 2+ The fluorescence intensity of Sm continued to decrease, while 3+ The fluorescence intensity at 644 nm gradually increases; and the ratio of the two fluorescence intensities (I0) is greater than that of the fluorescence intensity at 644 nm. 644 / I 485 The fluorescence exhibits a favorable curve relationship with temperature (233K-333K). The fluorescence color changes significantly with temperature, from green to yellowish-green, then to orange, and finally to red, demonstrating good ratiometric temperature response characteristics. A ratiometric temperature sensor based on a 1R2R-ZnSm-PMMA thin film was fabricated by dispersing the 1R2R-ZnSm complex in PMMA, expanding its application range.

[0028] Based on the above advantages of this temperature sensor, the 1R2R-ZnSm complex and thin film exhibit good fluorescence ratiometric temperature response characteristics. This makes the ratiometric temperature sensor based on the 1R2R-ZnSm complex and thin film less susceptible to factors such as concentration changes or fluctuations in excitation light intensity, resulting in high sensitivity and accurate temperature measurement. Furthermore, the ratiometric temperature sensor based on the 1R2R-ZnSm complex and thin film also features low preparation cost, simple synthesis method, high fluorescence intensity, wide temperature measurement range, and broad application range. Attached Figure Description

[0029] Figure 1 This is the molecular structure diagram of the 1R2R-ZnSm complex.

[0030] Figure 2 This is the solid-state fluorescence emission spectrum of the 1R2R-ZnSm complex at room temperature.

[0031] Figure 3 The fluorescence emission spectrum of the 1R2R-ZnSm complex liquid (toluene) at room temperature is shown.

[0032] Figure 4 The fluorescence emission spectrum of the 1R2R-ZnSm complex ratiometric temperature sensor varies at different temperatures (K) (λex = 365 nm).

[0033] Figure 5 The ratio of the fluorescence emission peak intensities of the 1R2R-ZnSm complex at different temperatures (I) 644 / I 485 The fitted curves of Zn and temperature; where a is the fluorescence intensity at 485 nm as a function of temperature, b is the fluorescence intensity at 644 nm as a function of temperature, and c is the fluorescence intensity at 644 nm as a function of temperature. 2+ and Sm 3+ The ratio of the intensity (I) 644 / I 485 The graph shows the change of Zn with temperature, where d represents Zn. 2+ and Sm 3+ The ratio of the intensity (I) 644 / I 485 Linear relationship between temperature and temperature.

[0034] Figure 6 Sensitivity test results for the 1R2R-ZnSm complex.

[0035] Figure 7 Cyclic test diagram of 1R2R-ZnSm complex.

[0036] Figure 8 The fluorescence emission spectrum of the 1R2R-ZnSm-PMMA thin film varies at different temperatures (K) (λex = 365 nm).

[0037] Figure 9 The ratio of the fluorescence emission peak intensities of 1R2R-ZnSm-PMMA thin films at different temperatures (I) 644 / I 485 The fitted curve of temperature.

[0038] Figure 10 This is a schematic diagram of the synthesis of a ratiometric temperature sensor based on a 1R2R-ZnSm complex.

[0039] Figure 11 The fluorescence emission spectrum of the 1R2R-ZnSm-PVDF film varies at different temperatures (λex = 365 nm). Detailed Implementation

[0040] The invention's objective will be further described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described in detail here, but the implementation of the invention is not limited to the following embodiments.

[0041] Example 1

[0042] 0.0338 g of Schiff base ligand R,R-H₂L, 0.0200 g of samarium nitrate, and 0.0200 g of zinc acetate were placed in a sealed tube, 5 ml of methanol was added, and the tube stopper was tightened. The tube was heated overnight in a metal bath at 75°C. When crystals formed on the rock wall of the sealed tube, the crystals on the rock wall were filtered out to obtain the 1R₂R-ZnSm complex S1, thus obtaining a ratiometric temperature sensor based on the 1R₂R-ZnSm complex. The structure is as follows. Figure 1 As shown.

[0043] Weigh 2 mg of S1 obtained from the reaction and dissolve it in 3 ml of toluene. Sonicate for 30 min, take 30 μL, dissolve it in 3 ml of toluene, and thus obtain a concentration of 10. -5 M is the test sample solution S2.

[0044] Take sample S1, and measure its fluorescence spectrum using 365 nm as the excitation wavelength. Figure 2 As shown. Sample S2 was placed in a 5 mL cuvette, and its fluorescence spectrum was measured using 365 nm as the excitation wavelength, as shown. Figure 3 As shown.

[0045] Depend on Figure 2 and Figure 3 It can be seen that the temperature sensor sample exhibits fluorescence emission peaks at 485nm, 560nm, 599nm, and 644nm, respectively.

[0046] Place S2 in a 5 mL cuvette (with lid), and measure its fluorescence spectrum at different temperatures (233-333 K) using 365 nm as the excitation wavelength. Figure 4 As shown. By Figure 4 It can be seen that the fluorescence emission peaks of the two different sources are Zn 2+ The emission peak (485nm) and Sm 3+ The fluorescence emission peaks of Zn are observed at 560 nm, 599 nm, and 644 nm. As the temperature gradually increases, Zn... 2+ The fluorescence intensity of Sm continued to decrease, while 3+ The fluorescence intensity at 644 nm gradually increases, indicating that the 1R2R-ZnSm complex has a significant temperature response.

[0047] The ratio of the two fluorescence intensities in S1 (I) 644 / I 485 Curve fitting was performed between ) and temperature (233K-333K) to obtain a line I 644 / I 485 Temperature-related curves, such as Figure 5 As shown. By Figure 5It can be seen that the standard regression equation for the 1R2R-ZnSm complex ratiometric temperature sensor is y=A1exp(X / 28.05)+0.0405,(R 2 =0.9950), where X is the temperature (K), and the detection range is 233K-333K. This ratio fluorescence thermometer can effectively avoid interference from external factors such as photoelectric fluctuations from the excitation source and detector, and accurately measure the temperature.

[0048] The obtained I 644 / I 485 By calculating the correlation curve with temperature, the sensitivity of the sample to temperature can be obtained, such as... Figure 6 As shown. By Figure 6 It can be seen that the temperature sensitivity of this sample can reach 3.4%. It can be used as a thermometer to achieve accurate temperature measurement.

[0049] Place S2 in a 5 mL cuvette (with lid). First, lower the temperature to 233 K, let it stand for 5 min, and then measure the fluorescence emission spectrum. Next, raise the temperature to 333 K, let it stand for 5 min, and then measure the fluorescence spectrum. Repeat this cycle 6 times. Plot the ratio of 485 nm to 644 nm in each spectrum as a curve, as shown below. Figure 7 As shown, by Figure 7 It can be seen that the 1R2R-ZnSm complex ratio temperature sensor has excellent recyclability.

[0050] A schematic diagram of the synthesis of a ratiometric temperature sensor based on a 1R2R-ZnSm complex is shown below. Figure 10 As shown, by Figure 10 It can be seen that the present invention uses crystallization coordination to combine the Schiff base ligand R,R-H2L with Zn. 2+ Ions and Sm 3+ Ions crystallize within a molecule through coordinate bonds, forming a temperature-sensitive ratiometric temperature sensor based on a 1R2R-ZnSm complex.

[0051] Example 2

[0052] 0.0338 g of Schiff base ligand R,R-H₂L, 0.0200 g of samarium nitrate, and 0.0200 g of zinc acetate were placed in a sealed tube, 5 ml of methanol was added, and the tube stopper was tightened. The tube was heated overnight in a metal bath at 75°C. When crystals formed on the rock wall of the sealed tube, the crystals on the rock wall were filtered out to obtain the 1R₂R-ZnSm complex ratiometric temperature sensor S1, with the structure shown below. Figure 1 As shown.

[0053] Take 2 mg of sample S1 and 1200 mg of PMMA, add 3 ml of toluene, stir at room temperature for 1 h to obtain mixture S3, then heat the hot table to 70 °C, place a glass plate on it, drop S3 onto the glass plate, and let it fall off naturally to obtain 1R2R-ZnSm-PMMA film.

[0054] A suitable-sized, uniformly thick 1R2R-ZnSm-PMMA thin film was selected. Its fluorescence spectra at different temperatures (223-333 K) were measured using 365 nm as the excitation wavelength. Figure 8 As shown; by Figure 8 It can be seen that the 1R2R-ZnSm-PMMA film contains two different fluorescence emission peaks, namely Zn 2+ The emission peak (485nm) and Sm 3+ The fluorescence emission peaks (560 nm, 599 nm, 644 nm) were observed. The same effect was observed when the 1R2R-ZnSm complex was dispersed in PMMA; as the temperature gradually increased, Zn... 2+ The fluorescence intensity of Sm continued to decrease, while 3+ The fluorescence intensity at 644 nm gradually increases, indicating that the 1R2R-ZnSm-PMMA film has a significant temperature response.

[0055] Zn 2+ and Sm 3+ The ratio of the two fluorescence intensities (I) 644 / I 485 Curve fitting was performed between ) and temperature (223K-333K) to obtain an I 644 / I 485 Temperature-related curves, such as Figure 9 As shown. By Figure 9 It can be seen that the standard regression equation is y = A1 exp(X / 74.15) + 0.77562(R). 2 =0.9983), where X is the temperature (K), and the detection range is 223K-333K.

[0056] Comparative Example 1

[0057] 0.0338 g of Schiff base ligand R,R-H₂L, 0.0200 g of samarium nitrate, and 0.0200 g of zinc acetate were placed in a sealed tube, 5 ml of methanol was added, and the tube stopper was tightened. The tube was heated overnight in a metal bath at 75°C. When crystals formed on the rock wall of the sealed tube, the crystals on the rock wall were filtered out to obtain the 1R₂R-ZnSm complex ratiometric temperature sensor S1, with the structure shown below. Figure 1 As shown.

[0058] Take 2 mg of sample S1 and 1200 mg of PVDF, add 3 ml of toluene, stir at room temperature for 1 h to obtain mixture S3, then heat the hot table to 70 °C, place a glass plate on it, drop S3 onto the glass plate, and let it fall off naturally to obtain 1R2R-ZnSm-PVDF film.

[0059] A suitable-sized, uniformly thick 1R2R-ZnSm-PVDF film was selected. Its fluorescence spectra at different temperatures (233-333 K) were measured using 365 nm as the excitation wavelength. Figure 11 As shown; by Figure 11 It can be seen that although the 1R2R-ZnSm-PVDF film contains two different sources of fluorescence emission peaks, namely Zn 2+ The emission peak (485nm) and Sm 3+ The fluorescence emission peaks (560 nm, 599 nm, 644 nm) were observed. When the 1R2R-ZnSm complex was dispersed in PVDF, the fluorescence positions did not change. The fluorescence intensity at 485 nm weakened, and with increasing temperature, Zn... 2+ The fluorescence intensity of Sm continued to decrease, while 3+ The fluorescence intensity at 644 nm also decreased with increasing temperature. This indicates that although the 1R2R-ZnSm-PVDF film is temperature-responsive, it does not exhibit the changing trend of the fluorescence peaks found in 1R2R-ZnSm or 1R2R-ZnSm-PMMA, and therefore cannot effectively improve the material's sensitivity and self-calibration capability.

[0060] The above-described specific embodiments are preferred embodiments of the present invention and are not intended to limit the present invention. Any other changes or equivalent substitutions made without departing from the technical solution of the present invention are included within the protection scope of the present invention.

Claims

1. A ratiometric temperature sensor based on a 1R2R-ZnSm complex, characterized in that, The 1R2R-ZnSm complex is composed of Schiff base ligand R,R-H2L and Zn 2+ and Sm 3+ The complex was obtained by coordination crystallization into a single molecule; the molecular structural formula of the 1R2R-ZnSm complex is [R,R-ZnLSm(OAc)(NO3)2]; The Schiff base ligand R,R-H2L has the following structure: The 1R2R-ZnSm complex has the following structure:

2. A ratiometric temperature sensor based on a 1R2R-ZnSm complex according to claim 1, characterized in that, The ratiometric temperature sensor based on the 1R2R-ZnSm complex contains fluorescence emission peaks from two different sources, namely Zn 2+ fluorescence emission peak and Sm 3+ The fluorescence emission peak of the Sm; 3+ The intensity of the fluorescence emission peak at 644 nm is I 644 With the Zn 2+ The intensity of the fluorescence emission peak at 485 nm is I 485 The ratio I 644 / I 485 The relationship between temperature and temperature follows a curve.

3. A ratiometric temperature sensor based on a 1R2R-ZnSm complex according to claim 1, characterized in that, The applicable temperature range is 233K-333K.

4. A ratiometric temperature sensor based on a 1R2R-ZnSm complex according to claim 1, characterized in that, Within the temperature range of 263K-333K, ln(I 644 / I 485 It exhibits a linear relationship with the change of the reciprocal of temperature, 1 / T.

5. A method for preparing a ratiometric temperature sensor based on a 1R2R-ZnSm complex according to any one of claims 1 to 4, characterized in that, Includes the following steps: Schiff base ligand R,R-H2L was placed in a reaction vessel with samarium nitrate and zinc acetate. After adding methanol, the reaction vessel was sealed and heated in a metal bath. After crystal formation, the crystals were filtered out to obtain the 1R2R-ZnSm complex, which is a ratiometric temperature sensor based on the 1R2R-ZnSm complex.

6. The method for fabricating a ratiometric temperature sensor based on a 1R2R-ZnSm complex according to claim 5, characterized in that, The molar ratio of the Schiff base ligand R,R-H2L to samarium nitrate and zinc acetate is 1:1:

1.

7. The method for fabricating a ratiometric temperature sensor based on a 1R2R-ZnSm complex according to claim 5, characterized in that, The heating reaction in the metal bath specifically involves: Heat to 60℃-80℃ in a metal bath and react overnight.

8. A method for preparing a ratiometric temperature sensor based on a 1R2R-ZnSm complex according to any one of claims 5 to 7, characterized in that, It also includes the following steps: The 1R2R-ZnSm complex was prepared into a thin film to obtain a ratiometric temperature sensor based on the 1R2R-ZnSm-PMMA thin film.

9. The method for fabricating a ratiometric temperature sensor based on a 1R2R-ZnSm complex according to claim 8, characterized in that, The preparation of the 1R2R-ZnSm complex into a thin film specifically involves: A ratiometric temperature sensor based on a 1R2R-ZnSm complex was mixed with PMMA using toluene as a solvent and stirred at room temperature to obtain a mixture. A glass plate was placed on a hot stage at 65–75°C, and the mixture was uniformly coated onto the glass plate. After it naturally peeled off, a 1R2R-ZnSm-PMMA thin film was obtained, thus obtaining a ratiometric temperature sensor based on a 1R2R-ZnSm-PMMA thin film.

10. A temperature detection method based on a ratiometric temperature sensor of a 1R2R-ZnSm complex as described in any one of claims 1 to 4, characterized in that, Includes the following steps: (1) The fluorescence intensity I of the ratiometric temperature sensor based on the 1R2R-ZnSm complex under 365nm excitation was measured at different temperatures in the range of 233K-333K. 485 and I 644 ; (2) Within the temperature range of 233-333K, the ratio of fluorescence intensity I 644 / I 485 By fitting the curve with temperature, a standard regression equation is obtained; (3) Ensure the sample to be tested is in full contact with the ratiometric temperature sensor based on the 1R2R-ZnSm complex. After the temperature stabilizes, measure the fluorescence intensity I of the sample under 365nm excitation. 485 and I 644 The ratio of fluorescence intensity I 644 / I 485 The temperature of the sample to be tested is obtained by comparing it with the standard regression equation.

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