CN116731335B - For As 5+ Ratio fluorescent probe RhB@UiO-67-NH with high selectivity 2 Preparation method and application thereof - Google Patents

Abstract

The invention belongs to the technical field of metal-organic framework materials, and in particular relates to a ratiometric fluorescent probe RhB@UiO-67-NH ₂ with high selectivity for As ⁵⁺ and its preparation method and application. Through a direct synthesis method, organic dyes are Rhodamine B was introduced, so that the two mixtures of RhB and ZrCl ₄ were combined with the organic ligand 2-amino-4,4´-biphenyl dicarboxylic acid in DMF solvent to obtain the ratiometric fluorescent probe RhB@UiO loaded with rhodamine B. ‑67‑NH ₂ material, by introducing a second fluorophore into the UiO‑67‑NH ₂ structure, the fluorescence sensing performance of the UiO‑67‑NH ₂ metal organic framework material in 90% methanol is improved, thereby making the metal The organic framework has fast and accurate specific recognition ability, strong anti-interference ability, low detection limit and good reproducible performance for As ⁵⁺ ions in 90% methanol solution.

Description

Ratio fluorescent probe RhB@UiO-67-NH2 with high selectivity for As5+ and its preparation Preparation methods and applications

Technical field

The invention belongs to the technical field of metal organic framework materials, and in particular relates to a ratiometric fluorescent probe RhB@UiO-67-NH ₂ with high selectivity for As ⁵⁺ and its preparation method and application.

Background technique

Arsenic mainly exists in the form of inorganic and organic arsenic, such as arsenite (As ³⁺ ) and arsenate (As ⁵⁺ ). As a pollutant that widely exists in nature, arsenic is easily accumulated in the human body through the food chain. The As ⁵⁺ ions absorbed by the human body will be converted into As ³⁺ ions, which interact with enzymes and receptors with adjacent sulfhydryl pairs. And coenzyme binding, inhibiting its biochemical function, thereby producing toxicity.

However, the content of As ⁵⁺ in real environments is often very low, and traditional detection techniques such as high-performance liquid chromatography (HPLC), atomic absorption spectrometry (AAS), ultraviolet spectrophotometry (UV), and hydride generation-atomic absorption Even if arsenic ions can be detected at trace or trace levels by spectroscopic methods (HG-AAS) and inductively coupled plasma mass spectrometry (ICP-MS), they often cannot be used in a timely and effective manner due to shortcomings such as expensive equipment, time-consuming, and poor portability. Detect arsenic ions. Therefore, it is of great significance to invent a fluorescent probe material that can quickly detect As ⁵⁺ ions.

Contents of the invention

The purpose of the present invention is to provide a ratiometric fluorescent probe RhB@UiO-67-NH ₂ with high selectivity for As ⁵⁺ ions and its preparation method and application, which effectively solves the low efficiency, time-consuming, and Susceptible to interference, poor portability and other issues.

In order to achieve the above object, the technical solution adopted by the present invention is:

A method for preparing the ratiometric fluorescent probe RhB@UiO-67-NH ₂ with high selectivity for As ⁵⁺ , including the following steps: combining Zr ⁴⁺ chloride salt, rhodamine B (RhB) and 2-amino -4,4′-biphenyldicarboxylic acid (BPDC-NH ₂ ) is directly mixed together, and DMF organic solvent is used as the reaction medium to form a UiO-67-NH ₂ modified material containing rhodamine B loaded through a self-assembly process.

Further, the reaction temperature is 100°C and the reaction time is 24 hours; the ratio of the amounts of rhodamine B to the ligand BPDC-NH ₂ is 1:2 to 1:6.

Further, the ratio of the amounts of Rhodamine B, Zr ⁴⁺ chloride, 2-amino-4,4′-biphenyldicarboxylic acid (BPDC-NH ₂ ) and DMF is 1:2:2: 900~1:6:6:2719.

The probe prepared using the preparation method of the ratiometric fluorescent probe RhB@UiO-67-NH ₂ with high selectivity for As ⁵⁺ has a BET specific surface area of 363~ ^414m2 /g and a Langmuir specific surface area of 472~ ^545m2 /g, the pore volume is 0.344~0.388cm ³ /g, the micropore volume is 0.088~0.104cm ³ /g, and the average pore diameter is 3.342~3.878nm.

RhB@UiO-67- _NH, a ratiometric fluorescent probe with high selectivity for As ⁵⁺ , is used for micro or trace detection of As ⁵⁺ ions, and its detection limit for As ⁵⁺ in 90% methanol solution is as low as 0.52 μM.

Mechanism: The present invention introduces rhodamine B into the reaction system of Zr ⁴⁺ chloride and 2-amino-4,4′-biphenyldicarboxylic acid through a direct synthesis method to obtain a metal-organic framework with ratiometric fluorescence . By introducing the second fluorophore rhodamine B into the UiO-67-NH ₂ structure, the present invention can improve the fluorescence sensing performance of the UiO-67-NH ₂ metal organic framework material in 90% methanol, thereby making RhB@UiO -67- _NH2 nanoscale metal-organic framework material has fast and accurate specific recognition ability for ^{As5 +} ions in 90% methanol solution, strong anti-interference ability, low detection limit and excellent regeneration performance. The ratiometric fluorescent probe RhB@UiO-67-NH ₂ material provided by the present invention has a detection limit of As ⁵⁺ ions in 90% methanol solution to 0.52 μM.

The advantages of the present invention are: the ratiometric fluorescent probe RhB@UiO-67-NH ₂ metal-organic framework material of the present invention has selective fluorescence detection ability for As ⁵⁺ ions, and has a lower detection limit, while using solvothermal The method and direct synthesis method are simple to operate, easy to synthesize, suitable for large-scale industrial production, and have high research and application value. It also has the advantages of good thermal stability, good chemical stability, and good repeatability.

Description of drawings

Figure 1 is a comparison diagram of the nitrogen adsorption-desorption isotherms of the ratiometric fluorescent probe prepared in Examples 1-3 of the present invention under the condition of 77K.

Figure 2 is a comparison chart of the infrared spectra (4000cm ^-1 -400cm ^-1 ) of the ratiometric fluorescent probe prepared in Examples 1-3 of the present invention and the original UiO-67-NH ₂ .

Figure 3 is a magnified infrared spectrum comparison chart (1700cm ^-1 -400cm ^-1 ) of the ratiometric fluorescent probe prepared in Examples 1-3 of the present invention and the original UiO-67-NH ₂ .

Figure 4 is a thermal stability comparison chart of the ratiometric fluorescent probe prepared in Examples 1-3 of the present invention and the original UiO-67- _NH2 .

Figure 5 is a fluorescence emission spectrum diagram of the ratiometric fluorescent probe prepared in Example 2 of the present invention after fluorescence sensing of As ⁵⁺ ions at different concentrations.

Figure 6 is a linear fitting diagram of the ratiometric fluorescent probe prepared in Example 2 of the present invention when fluorescence sensing As ⁵⁺ ions at low concentrations.

Figure 7 is a fluorescence intensity diagram of the ratiometric fluorescent probe prepared in Example 2 of the present invention after fluorescence sensing of different metal ions.

Figure 8 is a regeneration intensity diagram after fluorescence sensing of As ⁵⁺ ions by the ratiometric fluorescent probe prepared in Example 2 of the present invention.

Detailed ways

Example 1

Dissolve 133.33mg zirconium chloride (ZrCl ₄ , 0.573mmoL), 147.47mg 2-amino-4,4'-biphenyldicarboxylic acid (BPDC-NH ₂ , 0.573mmoL), 137.47mg rhodamine B (0.287mmoL) in Dissolve in 20mL of DMF by sonication. Transfer the solution to a 100mL polytetrafluoroethylene reactor, put it into an electric constant-temperature blast drying oven, raise the temperature from room temperature to 100°C in 30 minutes, keep it at 100°C for 24 hours, cool to room temperature naturally, and take out the reaction The solution in the kettle was centrifuged and immersed in 50 mL of DMF. After repeating three times, change to fresh DMF every 24 hours. Then, change the soaking solvent to methanol. Change to fresh methanol every 24 hours. Repeat three times. Finally, the pink crystals obtained were centrifuged again. After simple drying, the purified MOF was dried in a vacuum drying oven at 100°C for 12 hours to obtain the purified RhB@UiO-67-NH ₂ compound. Denoted as RhB@UiO-67-NH ₂ (1:2).

Example 2

Dissolve 133.33mg zirconium chloride (ZrCl ₄ , 0.573mmoL), 147.47mg 2-amino-4,4'-biphenyldicarboxylic acid (BPDC-NH ₂ , 0.573mmoL), 68.49mg rhodamine B (0.143mmoL) in Dissolve in 20mL of DMF by sonication. Transfer the solution to a 100mL polytetrafluoroethylene reactor, put it into an electric constant-temperature blast drying oven, raise the temperature from room temperature to 100°C in 30 minutes, keep it at 100°C for 24 hours, cool to room temperature naturally, and take out the reaction The solution in the kettle was centrifuged and immersed in 50 mL of DMF. After repeating three times, change to fresh DMF every 24 hours. Then, change the soaking solvent to methanol. Change to fresh methanol every 24 hours. Repeat three times. Finally, the pink crystals obtained were centrifuged again. After simple drying, the purified MOF was dried in a vacuum drying oven at 100°C for 12 hours to obtain the purified RhB@UiO-67-NH ₂ compound. Denoted as RhB@UiO-67-NH ₂ (1:4).

Example 3

Dissolve 133.33mg zirconium chloride (ZrCl ₄ , 0.573mmoL), 147.47mg 2-amino-4,4'-biphenyldicarboxylic acid (BPDC-NH ₂ , 0.573mmoL), 45.74mg rhodamine B (0.095mmoL) in Dissolve in 20mL of DMF by sonication. Transfer the solution to a 100mL polytetrafluoroethylene reactor, put it into an electric constant-temperature blast drying oven, raise the temperature from room temperature to 100°C in 30 minutes, keep it at 100°C for 24 hours, cool to room temperature naturally, and take out the reaction The solution in the kettle was centrifuged and immersed in 50 mL of DMF. After repeating three times, change to fresh DMF every 24 hours. Then, change the soaking solvent to methanol. Change to fresh methanol every 24 hours. Repeat three times. Finally, the pink crystals obtained were centrifuged again. After simple drying, the purified MOF was dried in a vacuum drying oven at 100°C for 12 hours to obtain the purified RhB@UiO-67-NH ₂ compound. Denoted as RhB@UiO-67-NH ₂ (1:6).

Performance Testing:

(1) N ₂ adsorption-desorption analysis

Nitrogen adsorption-desorption tests were performed on the synthesized UiO-67- _NH2 and the ratiometric fluorescent probe synthesized in Examples 1-3 at 77K. The obtained specific surface area, micropore volume, total pore volume and average pore diameter results are shown in Table 1.

Table 1 Pore structure parameters of UiO-67-NH _and different proportions of RhB@UiO-67- _NH

It can be seen from Figure 1 that at relatively low pressure, the nitrogen adsorption amount of UiO-67-NH ₂ and the ratiometric fluorescent probe RhB@UiO-67-NH ₂ rises rapidly. After reaching a certain relative pressure, the adsorption reaches saturation. This is a typical type I isotherm, which reflects the micropore filling phenomenon of microporous materials. This shows that the UiO-67-NH ₂ and the ratiometric fluorescent probe RhB@UiO-67-NH ₂ synthesized in this experiment are microporous materials. . Among them, for the ratiometric fluorescent probe RhB@UiO-67-NH ₂ , when the relative pressure is greater than 0.9, the nitrogen adsorption amount continues to increase, which is due to the new pores formed by the agglomeration and accumulation of material particles. Among them, for RhB@UiO-67-NH ₂ , the specific surface area shows a trend of first increasing and then decreasing, reaching the maximum when the ratio is 1:4. Therefore, when the doped RhB content is not very high, the RhB and Zr ions It can achieve a suitable coordination rate, form a coordination pattern that is conducive to the generation of coordination bonds, and finally reach the optimal coordination structure of RhB and Zr ions at a suitable ratio. When the content of RhB ions increases, on the one hand, it may be blocked. Partial pores, on the other hand, may lead to structural defects, causing partial skeleton collapse and ultimately causing a decrease in specific surface area. In summary, combined with other pore structure parameters such as micropore volume and total pore volume, the ratio of the fluorescent probe RhB@UiO-67-NH ₂ (1:4) with the largest specific surface area and total pore volume was selected as the most optimal. Optimized materials and applied them in subsequent fluorescence sensing experiments.

(2) Infrared spectrum analysis

Figures 2 and 3 show the infrared spectra of UiO-67-NH ₂ and RhB@UiO-67-NH ₂ . It can be seen from the figure that UiO-67-NH ₂ is consistent with what has been reported in the literature. The characteristic peak at 3425cm ^-1 corresponds to the stretching vibration peak of NH in UiO-67-NH ₂ , and the characteristic peaks at 1536cm ^-1 and 1415cm ^-1 Corresponding to the stretching vibration peak of the carboxyl group on the benzene ring, the characteristic peaks at 776cm ^-1 and 662cm ^-1 correspond to the stretching vibration peak of Zr-O on the UiO-67-NH ₂ skeleton, and the characteristic peak at 1085cm ^-1 corresponds to Zr- OH stretching vibration peak. Compared with UiO-67-NH ₂ , RhB@UiO-67-NH ₂ has smaller wave number changes, and no new peaks were found. The results indicate that RhB may be encapsulated in the channels of UiO-67-NH ₂ . , this host-guest encapsulation has little impact on the structure of UiO-67- _NH2 .

(3) Thermal stability analysis

Figure 4 shows the thermal stability analysis chart of UiO-67-NH ₂ and ratiometric fluorescent probe RhB@UiO-67-NH ₂ materials. It can be seen that the ratiometric fluorescent probe RhB@UiO-67-NH ₂ has good thermal stability. When the temperature is from room temperature to 380°C, the ratiometric fluorescent probe RhB@UiO-67-NH ₂ material loses its first mass (about 10%), mainly due to combined water and solvent molecules; when the temperature is 460-608°C , the ratiometric fluorescent probe RhB@UiO-67-NH ₂ material experienced a second mass loss (about 20%), and the material structure collapsed at this temperature. As for UiO-67-NH ₂ before modification, the material structure begins to collapse at 400°C. The above shows that the ratiometric fluorescent probe RhB@UiO-67-NH ₂ material has good thermal stability.

(4) Fluorescence sensitivity analysis

As ⁵⁺ 90% methanol solutions of different concentrations were titrated, and a fluorescence spectrophotometer was used to test the fluorescence sensing performance of the RhB@UiO-67-NH ₂ (1:4) nanoscale material of the present invention for As ⁵⁺ ions. As shown in Figure 5, with the increase of As ⁵⁺ ion concentration, the relative fluorescence intensity I ₄₅₂ /I ₅₇₈ of RhB@UiO-67-NH ₂ (1:4) material gradually increases. In the low concentration range, the two The linear correlation can be analyzed using the equation I ₄₅₂ /I ₅₇₈ =S·[C]+1. I ₄₅₂ is the fluorescence intensity of the material at 452 nm after adding the analyte. I ₅₇₈ is the fluorescence intensity of the material at 578 nm after adding the analyte. The fluorescence intensity, C is the concentration of the added analyte in μM, and S is the slope of the linear curve fitting at low concentration. As shown in Figure 6, at low concentrations, there is a good linear relationship between I ₄₅₂ /I ₅₇₈ and As ⁵⁺ ion concentration (correlation coefficient R ² =0.99191), which shows that the fluorescence enhancement effect of As ⁵⁺ ions is very Good fit to the equation model. The slope S is 1.2812×10 ⁵ M ^-1 , which shows that As ⁵⁺ ions have a strong fluorescence enhancement effect on the RhB@UiO-67-NH ₂ (1:4) material, with high sensitivity and meeting the ratiometric fluorescence conditions. By testing the fluorescence intensity of RhB@UiO-67-NH ₂ (1:4) in 90% methanol solution after multiple measurements, it can be found that RhB@UiO-67-NH ₂ (1:4) in 90% methanol solution The luminescence intensity remains basically stable, and the standard deviation is calculated to be about 0.022. The detection limit is calculated using the formula reported in the literature: LOD=3δ/S=0.52μM

Furthermore, for UiO-67-NH ₂ , LOD=3δ/S=118.3 μM. From this, we can find that after the introduction of rhodamine B, the detection limit was reduced from 118.3 μM to 0.52 μM, and the sensitivity was significantly improved.

(5) Fluorescence selectivity analysis

In As ³⁺ , Li ⁺ , Cd ²⁺ , Zn ²⁺ , Pb ²⁺ , Mn ⁴⁺ , Co ²⁺ , Ni ²⁺ , Ag ⁺ , K ⁺ , Cr ³⁺ , Na ⁺ , Cu ²⁺ , Fe The fluorescence sensing performance of the ratiometric fluorescent probe RhB@UiO-67-NH ₂ (1:4) for As ⁵⁺ ions in the presence of ³⁺ plasma is shown in Figure 7. It can be seen from the figure that even in the presence of other common metal ions and harmful elements, the ratiometric fluorescent probe RhB@UiO-67-NH ₂ (1:4) of the present invention still has good detection performance for As ⁵⁺ ion fluorescence. Selectivity, which shows that it has good anti-interference ability against most common metal ions or harmful elements, and can be used for As ⁵⁺ ion fluorescence sensing.

(6) Regeneration performance analysis

The reversibility of material fluorescence is a key factor in evaluating sensor performance. In order to explore the reusability of the ratiometric fluorescent probe RhB@UiO-67-NH ₂ (1:4) for As ⁵⁺ ion detection, it was recycled Research. The MOFs sample that sensed As ⁵⁺ was centrifuged, and then washed continuously with 90% methanol to remove as much metal ions as possible adhered to the surface. After sufficient drying, proceed to the next step of fluorescence sensing. As shown in Figure 8, it can be seen that after 4 cycles, the material's ability to detect As ⁵⁺ ions has almost no change, showing that the ratiometric fluorescent probe RhB@UiO-67-NH ₂ (1 :4) Good reproducibility in applications of detecting As ⁵⁺ .

Claims (3)

1. A method for preparing the ratiometric fluorescent probe RhB@UiO-67- _NH with high selectivity for As ⁵⁺ , which is characterized in that it includes the following steps: combining the chloride salt of Zr ⁴⁺ , rhodamine B and 2-Amino-4,4´-biphenyldicarboxylic acid is directly mixed together, using DMF organic solvent as the reaction medium, and forms a UiO-67-NH _modified material containing the organic dye RhB through a self-assembly process; the reaction temperature is 100 ℃, the reaction time is 24-30 hours; the material amount ratio of the chloride salt of rhodamine B, Zr ⁴⁺ , 2-amino-4,4´-biphenyldicarboxylic acid and DMF is 1:2: 2:900~1:6:6:2719. 2. The probe prepared by the preparation method of the ratiometric fluorescent probe RhB@UiO-67-NH with high selectivity for As ⁵⁺ according to claim ₁ , characterized in that: its BET specific surface area is 363~414 m ² /g, the Langmuir specific surface area is 472~545 m ² /g, the pore volume is 0.344~0.388 cm ³ /g, the micropore volume is 0.088~0.104 cm ³ /g, and the average pore diameter is 3.342~3.878 nm. 3. The probe according to claim 2 is used for micro or trace detection of As ⁵⁺ ions, and its detection limit for As ⁵⁺ in 90% methanol solution is as low as 0.52 μM.