A Fe 3+ Ion probes, their preparation methods and applications

Abstract

This invention discloses a Fe 3+ Ion probes, their preparation methods, and applications: Based on the Schiff reaction, 5-formylsalicylic acid and p-aminobenzenesulfonic acid are mixed with EtOH, and the mixture is subjected to reflux reaction and vacuum distillation to obtain a crude product. The crude product is then purified by column chromatography to obtain a pale yellow solid, which is Fe. 3+ Ion probe, Fe 3+ Ion probe for Fe 3+ It exhibits excellent recognition and sensing performance, with absorbance exceeding that of the commercial colorimetric reagent SSal under the same conditions. In the aqueous phase, Fe... 3+ Ion probe in Fe 3+ In the presence of [a substance], it changes from colorless to orange-red, exhibiting good color development, and also shows good Fe [color development] under corrosive conditions. 3+ The ion detection effect shows promise for application in various corrosive environments.

Description

Technical Field

[0001] This invention belongs to Fe 3+ In the field of ion detection technology, specifically involving an Fe 3+ Ion probes, their preparation methods, and applications. Background Technology

[0002] o-phenanthroline, potassium ferricyanide, and potassium thiocyanate are all common Fe compounds in existing technologies. 3+ Ion probes are significantly affected by pH levels in their detection performance, and they are also subject to interference from zinc ions to varying degrees. In contrast, sulfosalicylic acid not only develops color rapidly in acidic environments, but also forms complexes with high stability and good reproducibility, making it suitable for rapid and accurate determination of iron content over a wide range, thus becoming the preferred colorimetric reagent for iron ion detection.

[0003] However, despite its excellent performance in meeting basic experimental requirements, sulfosalicylic acid still has some significant limitations: the maximum absorption wavelength of its complexes shifts with pH, ​​from 505 nm in acidic media to 420 nm in alkaline solutions; and sulfosalicylic acid, as a bidentate ligand, reacts with Fe... 3+ Complexes with different ratios can be formed, and these complexes exhibit different spectral characteristics, which can introduce certain errors into experimental analysis; with Fe 3+ The formed complex exhibits low molar absorbance in different media, with fluctuations ranging from 10. 2 Up to 10 4 L·cm -1 ·mol -1 Therefore, it is difficult to obtain a low detection limit.

[0004] Given the aforementioned limitations, developing new iron ion colorimetric reagents to adapt to various corrosive environments has become an urgent research need. The development of new colorimetric reagents must meet the following key conditions: Given the advantages of visible light spectrophotometry, such as high cost-effectiveness, good anti-interference performance, and long equipment life, the absorption wavelength of the new colorimetric reagent L should be similar to that of Fe... 3+ The resulting FeL complex should have a response wavelength greater than 380 nm and should conform to Beer's Law over a wide wavelength range. To achieve a lower detection limit, according to Beer's Law, the molar absorbance of the chromogenic reagent should be relatively high, which helps in detecting lower concentrations of Fe. 3+ Ions; good water solubility of the colorimetric reagent is crucial. The new colorimetric reagent should possess strong anti-interference capabilities, maintaining its effectiveness against Fe even under a wide range of pH values, in the presence of oxidants, and interference from other metals and anions. 3+ High affinity.

[0005] In summary, while sulfosalicylic acid demonstrates reliability in current iron ion detection, developing new colorimetric reagents to meet more stringent detection standards is of paramount importance. This would not only improve the accuracy and sensitivity of detection but also provide strong support for rapid and accurate monitoring of iron ion levels in various corrosive environments, further advancing corrosion science research. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0008] Therefore, the object of the present invention is to overcome the shortcomings of the prior art and provide a Fe 3+ Ion probe.

[0009] To solve the above technical problems, the present invention provides the following technical solution: the Fe 3+ The structural formula of the ion probe is shown in formula (I);

[0010]

[0011] Another object of the present invention is to provide a Fe 3+ Methods for preparing ion probes.

[0012] To solve the above technical problems, the present invention provides the following technical solution: the Fe 3+ The ion probes are synthesized based on the Schiff reaction, and the synthetic route is referenced in formula (II);

[0013]

[0014] As described in this invention, Fe 3+ A preferred embodiment of the method for preparing an ion probe includes:

[0015] 5-Formylsalicylic acid and p-aminobenzenesulfonic acid were mixed with EtOH and refluxed. The crude product was obtained by vacuum distillation, and then purified by column chromatography to give a pale yellow solid, which was Fe. 3+ Ion probe.

[0016] As described in this invention, Fe 3+ A preferred embodiment of the method for preparing an ion probe, wherein the molar ratio of 5-formylsalicylic acid to p-aminobenzenesulfonic acid is 0.0062 mol: 0.0070 mol.

[0017] As described in this invention, Fe 3+ A preferred embodiment of the method for preparing an ion probe, wherein the amount of EtOH used for each 1g of 5-formylsalicylic acid is 25ml.

[0018] As described in this invention, Fe 3+ A preferred embodiment of the method for preparing an ion probe, wherein the reflux reaction is carried out at a temperature of 70°C for 4 hours.

[0019] As described in this invention, Fe 3+ A preferred embodiment of the method for preparing ion probes, wherein the eluent for column chromatography purification is CH2Cl2 / CH3OH in a volume ratio of 5:1.

[0020] Another object of the present invention is to provide a Fe 3+ Ion probes for detecting Fe 3+ Applications in [the field].

[0021] To solve the above technical problems, the present invention provides the following technical solution: the Fe 3+ Ion probe for Fe 3+ It has identification sensing capabilities.

[0022] As described in this invention, Fe 3+ Ion probes for detecting Fe 3+ A preferred embodiment of the application, wherein: in the aqueous phase, Fe 3+ Ion probe in Fe 3+ In its presence, it changes from colorless to orange-red.

[0023] As described in this invention, Fe 3+ Ion probes for detecting Fe 3+ A preferred embodiment of the application in, wherein: the Fe 3 + In the aqueous phase, Fe 3+ Ion probe in Fe 3+ In its presence, it changes from colorless to orange-red, for Fe 3+ The linear detection range is 1.12–11.2 mg / L, for Fe 3+ The detection limit is 1.45 mg / L.

[0024] As described in this invention, Fe 3+ Ion probes for detecting Fe 3+ A preferred embodiment of the application in, wherein: the Fe 3 + Ion probe under corrosive solution conditions, Fe 3+ Ion probe for Fe3+ The linear detection range is 2.64–7.08 mg / L, for Fe 3+ The detection limit is 1.14 mg / L, wherein the composition of the corrosive solution is 5% HAc + 0.05% NaNO3 + 0.8% Na2S2O8 + 5% NaCl.

[0025] Beneficial effects of this invention:

[0026] This invention provides a Fe 3+ Ion probes, their preparation methods, and applications: Based on the Schiff reaction, 5-formylsalicylic acid and p-aminobenzenesulfonic acid are mixed with EtOH, and the mixture is subjected to reflux reaction and vacuum distillation to obtain a crude product. The crude product is then purified by column chromatography to obtain a pale yellow solid, which is Fe. 3+ Ion probe, Fe 3+ Ion probe for Fe 3+ It exhibits excellent recognition and sensing performance, with absorbance exceeding that of the commercial colorimetric reagent SSal under the same conditions. In the aqueous phase, Fe... 3+ Ion probe in Fe 3+ In the presence of [a substance], it changes from colorless to orange-red, exhibiting good color development, and also shows good Fe [color development] under corrosive conditions. 3+ The ion detection effect shows promise for application in various corrosive environments. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0028] Figure 1 The image shows the 1H NMR spectrum of Fe-4#, the product of Example 1 of this invention.

[0029] Figure 2 In Example 2 of this invention, Fe was added to an aqueous solution with pH = 7. 3+ Changes in absorbance of the colorimetric reagent before and after.

[0030] Figure 3 This is a comparison chart of the acid and alkali stability of Fe-4# and the conventional colorimetric agent sulfosalicylic acid (SSal) in Example 3 of the present invention.

[0031] Figure 4 This is a graph showing the results of measuring Fe-4#'s resistance to interference from zinc ions and other metals in Example 4 of the present invention.

[0032] Figure 5This is a graph showing the results of measuring the color development time stability of Fe-4# in Example 5 of the present invention.

[0033] Figure 6 This is a diagram showing the results of optimizing the dosage of different colorimetric agents in Example 6 of the present invention.

[0034] Figure 7 This invention relates to the effects of different color-developing agents on Fe in an etching solution in Example 6. 3+ The linear relationship between the absorption spectrum and the response intensity is shown in the graph.

[0035] Figure 8 This is a graph showing the monitoring results of different colorimetric agents during the dynamic corrosion process in Example 6 of this invention.

[0036] Figure 9 This is a comparison chart of the detection performance of different colorimetric agents using a continuous corrosion device in Example 6 of this invention.

[0037] Figure 10 This is the synthesis circuit diagram of Fe-1# in Comparative Example 1 of the present invention.

[0038] Figure 11 This is the hydrogen nuclear magnetic resonance spectrum of Fe-1# in Comparative Example 1 of this invention.

[0039] Figure 12 This is the synthesis circuit diagram of Fe-2# in Comparative Example 2 of the present invention.

[0040] Figure 13 This is the 1H NMR spectrum of Fe-2# in Comparative Example 2 of this invention.

[0041] Figure 14 This is the synthesis circuit diagram of Fe-3# in Comparative Example 3 of the present invention.

[0042] Figure 15 The above is the 1H NMR spectrum of Fe-3# in Comparative Example 3 of this invention. Detailed Implementation

[0043] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0044] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0045] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0046] Unless otherwise specified, all raw materials used in this invention are commercially available in the field. The list of pharmaceuticals used is shown in Table 1, and the list of experimental instruments is shown in Table 2.

[0047] Table 1

[0048]

[0049]

[0050] Table 2

[0051] Heated magnetic stirrer Shanghai Sile Instruments Co., Ltd. Ultraviolet spectrophotometer American VARIAN Fluorescence spectrophotometer Hitachi F-4500

[0052] Unless otherwise specified, the ultraviolet and fluorescence titration experiments conducted in this invention to test the absorption and fluorescence properties of Fe-4# are as follows:

[0053] Accurately weigh 11.6 mg of Fe-4# into a 2 ml glass reagent bottle, dissolve it in 2.00 ml of DMSO to obtain a 0.02 mol / L standard stock solution. During testing, pipette 20 μL of the stock solution into a cuvette, add 2 ml of deionized water to obtain a 0.2 mM working solution. Simultaneously, prepare aqueous solutions of common metal ions with a concentration of 0.1 mol / L, including Na+, using deionized water. + K + Ba 2+ Co 2+ Hg 2+ Ca 2+ Cu 2+ N 2+ Zn 2+ Fe 2+ Fe 3+ In addition, HCl (1.0M) and NaOH (1.0M) were prepared to adjust the pH of the solution in order to investigate the effect of pH on the experiment.

[0054] The calculation of the detection limit (DL) of the ion probe (chromogenic reagent) in this invention is based on:

[0055] DL = 3σ / K;

[0056] In the formula, σ is the average standard deviation of 10 blank measurements, and K is the slope of the linear fit. The average standard deviation σ is determined.

[0057] In this study, the mean standard deviation σ was determined by the following method:

[0058] Take 20 μl 1×10 -3 Add mol / L of iron ion colorimetric reagent Fe-4#, followed by 1600 μL of deionized water, and finally add 20 μL of 1×10⁻⁶ mol / L iron ion colorimetric reagent. -3 mol / L Fe 3+ The test system was mixed by pipetting and then placed in a UV spectrophotometer for testing. The concentration of Fe-4# and Fe at 500 nm was recorded. 3+ The absorbance of the complexation peak (the concentration of the complexation peak) is recorded. Repeat the above test steps 10 times and record the results in the table below.

[0059] Table 3

[0060]

[0061] In this study, the K value was determined using the following method:

[0062] The iron ion colorimetric reagent SSal was used to determine the iron ion concentration in the range of 0.5–3 mg / L Fe. 3+ Under the conditions of absorbance at 505 nm, Fe-4# is in the range of 0.5–3 mg / L Fe. 3+ Under the conditions of absorbance at 500 nm, Fe-4# is in the range of 0.5–3 mg / L Fe. 3+ Under the given conditions, a linear curve was plotted at the absorbance at 505 nm, and the K value was obtained through linear fitting.

[0063] Example 1

[0064] This embodiment provides a Fe 3+ The synthesis method and route for the ion probe (chromogenic agent) are shown in formula (II):

[0065]

[0066] 1 g (0.0062 mol) of 5-formylsalicylic acid and 1.2123 g (0.0070 mol) of p-aminobenzenesulfonic acid were added to a 50 mL side-necked flask, followed by 25 mL of EtOH. The mixture was refluxed at 70 °C for 4 h, and the crude product was obtained by vacuum distillation. The crude product was purified by column chromatography using CH2Cl2 / CH3OH (5:1, v / v) as the eluent to obtain a pale yellow solid, which is the Fe prepared in this example. 3+ The ion probe (chromogenic agent) is designated Fe-4#.

[0067] Figure 1 The 1H NMR spectrum of the product in this embodiment is shown below, along with the characterization data: 1¹H NMR (400MHz, DM₂SO₆-d₆) δ 8.39 (s, 1H), 8.16 (dd, J = 9.9, 2.3Hz, 1H), 7.74 (d, J = 8.2Hz, 1H), 7.56 (m, 1H), 7.24 (d, J = 8.2Hz, 4H), 7.16 (dd, J = 8.4, 2.3Hz, 1H). The singlet at chemical shift 8.39 ppm is attributed to hydrogen on the carbon-nitrogen double bond, 7.24 ppm to the four hydrogens on the benzene ring of benzenesulfonic acid, and 7.56 ppm to the hydrogen on the sulfonyl group. The three hydrogens on the benzene ring of salicylic acid are observed at 8.16, 7.74, and 7.16 ppm, respectively, indicating the successful preparation of Fe-4# in this example.

[0068] Example 2

[0069] This embodiment is used for application testing of Fe-4#, specifically, to test its effect on Fe. 3+ Identification:

[0070] Dissolving Fe-4# in deionized water produces a pale yellow aqueous solution, indicating that the colorant absorbs in the ultraviolet region. Adding 1 eq of Fe... 3+ Afterwards, Fe-4# turned orange-red, indicating that the colorant was added to Fe. 3+ Later with Fe 3+ The complex of Fe4# is absorbed in the visible light region, thereby enabling the absorption of Fe4# in aqueous solution. 3+ Convenient color recognition.

[0071] Figure 2 Add Fe to an aqueous solution with pH=7 3+ Changes in absorbance of the colorimetric reagent before and after (black line without Fe) 3+ Fe was added to the red line. 3+ (The illustration shows the addition of Fe) 3+ The color change diagram before and after shows the addition of Fe. 3+ A new absorption peak then appeared at 500 nm, which was due to the reaction between the colorimetric agent and Fe. 3+ It exhibits a complexation peak and an absorbance of 0.49, demonstrating strong absorbance and promising application potential.

[0072] Example 3

[0073] This example compares the acid and alkali stability of Fe-4# and the conventional colorimetric reagent sulfosalicylic acid (SSal). The results are as follows: Figure 3 As shown, Figure 3 a) Color changes of SSal and Fe-4# in response to iron ions at pH = 2 to 12 (top image is SSal, bottom image is Fe-4#); Figure 3b) pH = 2-12, the interference of pH value on SSal; Figure 3 c) Absorbance variation curve of SSal at 490 nm for pH = 2-12; Figure 3 d) pH = 2-12, the interference of pH on Fe-4#; Figure 3 e) Absorbance change curve of Fe-4# at 500nm with pH = 2 to 12.

[0074] from Figure 3 a) It is visible to the naked eye that the color developer Fe-4# affects Fe in a wide pH range of 2–12. 3+ There is a response, and as the alkalinity increases, the color of SSal gradually fades, from... Figure 3 c. It can also be clearly seen that the absorbance of SSal at 490 nm decreases with increasing pH value. We then tested the acid and alkali resistance of the new colorimetric reagent Fe-4#. Figure 3 As can be seen from d and e, the absorbance of Fe-4# does not change much in the pH range of 2–4, and Fe-4# can stably identify Fe in a wide range of pH values ​​from 5 to 10. 3+ Furthermore, within the pH range of 2–12, the absorbance of the colorimetric reagent Fe-4# was higher than that of SSal.

[0075] Example 4

[0076] This embodiment is used to determine the resistance of Fe-4# to interference from zinc ions and other metals. The results are as follows: Figure 4 As shown, Figure 4 a) Add 5 eq of different metal ions (Na) to an aqueous solution of Fe-4# (10 μM). + Ba 2+ Co 2+ Hg 2+ Ca 2+ Cu 2+ Ni 2 + Zn 2+ Mg 2+ Cd 2+ Cr 3+ Fe 3+ The ultraviolet absorption spectrum of ) Figure 4 b) Fe-4# (10 μM) was added to an aqueous solution with 5 eq of different metal ions (Fe... 3+ Na + Ba 2+ Co 2+ Hg 2+ Ca 2+ Cu 2+ Ni 2+ Zn 2+ Mg2+ Cd 2+ Cr 3+ The absorbance histogram of ) Figure 4 c) Zn containing 1, 2, 5, 10, 20, 50, 100, 200, 500, 1000 eq 2+ Fe-4# under interference to Fe 3+ The ultraviolet absorption spectrum; Figure 4 d) In Zn containing 1, 2, 5, 10, 20, 50, 100, 200, 500, 1000 eq 2+ Fe-4# under interference to Fe 3+ Absorbance histogram.

[0077] from Figure 4 a) It can be seen that the addition of Fe 3+ A new absorption peak then appears at 500 nm, while other metal ions, such as Na, exhibit absorption at 500 nm. + Ba 2+ Co 2+ Hg 2+ Ca 2+ Cu 2+ Ni 2+ Zn 2+ Mg 2+ Cd 2+ Cr 3+ The fact that no response occurs indicates that Fe-4# can specifically recognize iron.

[0078] Subsequently, tests were conducted on different metal ions (Na). + Ba 2+ Co 2+ Hg 2+ Ca 2+ Cu 2+ Ni 2+ Zn 2+ Mg 2+ Cd 2+ Cr 3 + ) Identification of Fe-4# 3+ Interference, such as Figure 4 As shown in b, the absorbance did not change after adding 5 eq of other metal ions, followed by the addition of 1 eq of Fe. 3+ The absorbance increased to about 0.45, indicating that the Fe-4# synthesized in this invention has excellent resistance to interference from coexisting metal ions.

[0079] This embodiment further demonstrates Fe-4# in different Zn 2+ At concentrations of Fe 3+ Interference, the result is as follows Figure 4As shown in c and d, the results indicate the presence of Zn ranging from 1 to 50 eq. 2+ At that time, the absorbance of the system did not change significantly, and the fluctuation range was very small. 2+ At concentrations ≥100 eq, the absorption intensity decreases slightly compared to the lower equivalence conditions, but the overall fluctuation is small, and the absorption intensity tends to stabilize. Overall, Zn... 2+ The presence of Fe does not recognize the colorimetric reagent. 3+ There is significant interference. The colorimetric reagent Fe-4# has specific recognition for Fe3+ and exhibits excellent anti-interference properties.

[0080] Example 5

[0081] This embodiment is used to determine the colorimetric stability of Fe-4#, and the results are as follows: Figure 5 As shown, Figure 5 (Left) is the time response curve of Fe-4# in aqueous solution. Figure 5 (Right) is a bar chart of the time response of Fe-4#. The results show that the absorbance of Fe-4# prepared by this invention does not change much within 10 hours, and the colorimetric agent can stably develop color for a long time, indicating that the colorimetric agent has good properties.

[0082] Example 6

[0083] This embodiment is used to investigate the effect of Fe-4# prepared in this invention on Fe in a corrosive solution system. 3+ The recognition effect was compared with that of the conventional colorimetric reagent sulfosalicylic acid (SSal). Specifically:

[0084] S1: Preparation of experimental reagents;

[0085] (1) Preparation of 1:1 hydrochloric acid

[0086] Transfer 250 mL of deionized water to a 500 mL volumetric flask, slowly add 250 mL of hydrochloric acid, shake well to obtain 1:1 hydrochloric acid, and label.

[0087] (2)Fe 3+ Standard stock solution

[0088] FeFe 3+ Standard stock solution [ρ(Fe)=0.2g / L]: Weigh 0.0172g of ferric ammonium sulfate [FeNH4(SO4)2·12H2O] and dissolve it in 10mL of 1:1 hydrochloric acid solution. Transfer the solution to a 100mL volumetric flask and dilute it to the mark with water. The iron ion content of this solution is 0.2g / L.

[0089] (3)Fe 3+ Standard working solution

[0090] Use a pipette to transfer 20 μL of iron ion standard stock solution into a 2 mL glass reagent bottle, and dilute with deionized water to the mark. At this point, the concentration of the colorimetric reagent is 2 mg / L, which is the working solution.

[0091] (4) Colorimetric reagent standard solution

[0092] Colorimetric reagent standard stock solution of sulfosalicylic acid [ρ=100g / L]: Weigh 0.2g of sulfosalicylic acid into a 2ml glass reagent bottle, add 2.00ml of DMSO to dissolve, and obtain a standard stock solution of 100g / L.

[0093] Fe-4# [ρ=100g / L]: Weigh 0.2g of Fe-4# into a 2ml glass reagent bottle, add 2.00ml of DMSO to dissolve, and obtain a 100g / L standard stock solution.

[0094] (5) Experimental steps

[0095] Transfer 20 μL of sulfosalicylic acid standard solution into a 5 mL cuvette, add iron ion solutions of different concentrations, and measure the absorbance at a wavelength of 430 nm using a reagent blank solution as a reference.

[0096] For other SSal colorimetric reagents, the solubility is determined by transferring the colorimetric reagent sample according to Table 4.

[0097] Table 4

[0098] Fixed volume / mL 2 2 2 2 2 Colorimetric reagent concentration (g / L) 1 2 3 4 5

[0099] (6) The colorimetric reagent Fe-4# was measured in the same way as (5).

[0100] (7) Drawing the working curve

[0101] Transfer 5, 10, 15, 20, 25, and 30 μL of iron standard working solution to colorimetric reagent solutions of different concentrations. The iron content corresponding to these standard solutions is 0.5, 1, 1.5, 2, 2.5, and 3 mg, respectively. Measure the absorbance of each solution and subtract the absorbance of the reagent blank solution. Plot the working curve with the iron content on the x-axis and the absorbance on the y-axis.

[0102] (8) Calculation of analysis results

[0103] The iron content w(Fe) is calculated using the following formula:

[0104] w(Fe)=(A / kb)×V

[0105] In the formula:

[0106] A—Solution absorbance, in units of 1;

[0107] V—Volume of the test solution, in milliliters (mL);

[0108] b—thickness of the cuvette, in centimeters (cm);

[0109] k—molar absorbance, expressed in liters per gram per centimeter (L / (g·cm)).

[0110] This step allows for the optimization of the dosage of the colorimetric reagent, with results as follows: Figure 6 As shown, Figure 6 a) Standard curves for different SSal solubilities; Figure 6 b) Standard curves for different Fe-4# solubilities; Figure 6 c) Detecting the same concentration of Fe using colorimetric reagents SSal with different solubilities. 3+ Line graph; Figure 6 d) Detecting Fe of the same solubility using colorimetric reagent Fe-4# with different solubilities. 3+ Line graph.

[0111] 1-10 mg Fe 3+ The corresponding molar equivalent is 1.79 × 10⁻⁶. -5 ~1.79×10 -4 In GB / T 12689.5-2004, the amount of SSal used to detect the solubility is 20 g / L (0.0786 mol / L). The solubility of this colorimetric reagent is two orders of magnitude greater than the required colorimetric reagent. Although SSal detects Fe... 3+ The mechanism is to detect its interaction with Fe. 3+ The absorbance at 480 nm is optimal, but excessive concentration of the colorimetric reagent may increase the blank absorbance, reduce the signal-to-noise ratio, and result in a significant waste of the colorimetric reagent. Therefore, this study optimizes the colorimetric reagent concentration based on GB / T12689.5-2004.

[0112] Figure 6 c. Figure 6 The results showed that at 1 g / L (SSal was 4.1 × 10⁻⁶), the concentration was 4.1 × 10⁻⁶. -3 mol / L, Fe-4# is 3.1×10 -3 It still has a good response at a colorimetric reagent concentration of mol / L.

[0113] S2: Corrosion condition simulation test;

[0114] 1) Prepare the etching solution by dissolving 0.5g NaNO3, 8g Na2S2O8, 50g NaCl and 50g HAc (51.9ml) in 891.5g (891ml) of distilled water to prepare the etching solution. The composition is 5% HAc + 0.05% NaNO3 + 0.8% Na2S2O8 + 5% NaCl (w%).

[0115] 2) Pour 200 mL of etching solution into a 1 L beaker. Wipe the surface of a 40 μm galvanized steel sheet with anhydrous ethanol, then place it upright in the 1 L beaker. Add the etching solution prepared in 1). Immerse the galvanized steel sheet to a depth of 2 cm. React at room temperature (25 °C). Adjust the acidity of the sampled system back to pH 3 and continue etching. To determine the etching status in the etching solution, take 2 mL × 4 samples of the etching solution every 30 minutes. Add SSal and the new colorimetric reagent Fe-4# respectively, and measure the absorbance at 490 nm and 510 nm to determine the degree of etching.

[0116] 3) Continue corrosion for 1 hour after the corrosion system turns colored.

[0117] 4) Add the prepared sample dropwise to 1 mol / L Na2S2O8 to completely oxidize it to Fe. 3+ And then perform subsequent colorimetric titration and absorbance tests.

[0118] 5) Corrosion condition simulation test;

[0119] Accurately weigh 10.8 mg of Fe-4# into a 2 ml glass reagent bottle, add 2.00 ml of DMSO to dissolve, yielding 0.02 mol·L⁻¹. -1 The standard stock solution was prepared. During the test, 20 μL of the stock solution was pipetted into a cuvette, and 2 ml of the prepared etching solution was added to obtain a 0.2 mM working solution. 0.2–2 eq of Fe was then added. 3+ The absorbance was measured by gradually adding the solution.

[0120] 6) Calculation of detection limits under corrosive conditions;

[0121] Calculation of the limit of detection (DL): DL = 3σ / K

[0122] In the formula, σ is the average standard deviation of 10 blank measurements.

[0123] K is the slope of the linear fit.

[0124] In this embodiment, σ = 0.02189.

[0125] This step revealed that the colorimetric reagent Fe-4# affects Fe... 3+ It exhibits excellent recognition and sensing performance, and Fe-4# in the aqueous phase is found in Fe 3+ In its presence, it will change from colorless to purplish-red, exhibiting good color rendering effect.

[0126] Figure 7 a) To test the effects of SSal on different equivalents of Fe in the corrosive solution 3+ Absorption spectrum; Figure 7 b) SSal in the corrosive solution for Fe 3+Linear relationship of response intensity at 510 nm; Figure 7 c) Fe-4# in corrosive solutions with different equivalents of Fe 3+ Ultraviolet absorption spectrum; Figure 7 d) Fe-4# in the corrosive solution on Fe 3+ The linear relationship of the response intensity at 500 nm shows that the addition of Fe... 3+ Subsequently, the UV absorption of SSal gradually increased at 495 nm, and the absorption peak of Fe-4# at 500 nm increased with the increase of Fe. 3+ The strength gradually increases with increasing concentration, especially after adding 2 eq Fe. 3+ The absorbance reached saturation and showed a good linear relationship in the range of 0.2-2 eq.

[0127] By comparing the working curves under corrosive conditions, it was found that Fe-4# has a significant effect on Fe under corrosive conditions. 3+ The detection is sensitive and the properties are good. Based on the formula 3σ / K (σ = 0.02189 under corrosive conditions, K is the slope of the standard curve), the effect of Fe-4# on Fe under corrosive conditions can be calculated. 3+ The UV detection limit was 20.3 μM (2.31 mg / L), which is lower than that of SSal for Fe. 3+ The detection limit is 71.1 μM (3.99 mg / L), demonstrating good detection performance.

[0128] According to the formula, the molar absorbance of Fe-4# under corrosive conditions is 3372 mol / (L·cm), which is much higher than that of SSal (961.8 mol / (L·cm). Furthermore, its linear detection range (3.24~9.08 mg / L) is better than that of SSal (4.16-10.72 mg / L), indicating better properties. It is more in line with actual detection needs and can be used for field operations.

[0129] S3: Continuous corrosion testing of the equipment and ICP-MS combined testing;

[0130] The experimental conditions were set as follows: a base corrosion solution of 0.1% Fe-4# + 5% HAc + 0.05% NaNO3 + 0.8% Na2S2O8 + 5% NaCl. During the reaction, 0.1% Fe-4# + 20% HAc + 5% Na2S2O8 was used as a makeup solution to adjust the pH of the solution. The initial pH was between 2.8 and 3.1, and the flow rate was 0.35 ml / min.

[0131] The experimental control group was prepared using a base etching solution of 0.1% SSal + 5% HAc + 0.05% NaNO3 + 0.8% Na2S2O8 + 5% NaCl. During the reaction, 0.1% SSal + 20% HAc + 5% Na2S2O8 was used as a makeup solution to adjust the pH of the solution, with an initial pH between 2.8 and 3.1. The flow rate was 0.35 ml / min. Samples were taken at the mutation points during the etching process, and the samples were diluted 100 times before ICP-MS analysis.

[0132] This step further explored the monitoring capability of Fe-4# on the corrosion process during dynamic corrosion and compared it with SS al. Figure 8 a) A diagram showing the continuous corrosion phenomenon of galvanized steel sheet under corrosive liquid conditions from 0 to 4 hours; Figure 8 b) Add 1×10 to the galvanized sheet during continuous corrosion of 0–4 h. -4 mol / L SSal monitoring colorimetric diagram; Figure 8 c) Add 1×10 to the galvanized sheet during continuous corrosion of 0–4 h. - 4 mol / L Fe-4# monitoring colorimetric diagram; Figure 8 d) is a graph showing the change in absorbance.

[0133] Figure 8 a) It can be seen that as the corrosion time increases, the corrosion system begins to turn yellow when the corrosion time reaches 180 min, indicating that Fe... 3+ The concentration has reached a certain level. Continuous monitoring of the system through sampling is shown in the figure. Figure 8 In images b and c, we can clearly see that the sample solution with added SSal colorimetric reagent began to develop color at 100 min, while Fe-4# was detected in the system at 60 min. 3+ The emergence of this data can also be seen from Figure 8 d shows that monitoring the Fe in the same system 3+ It was found that Fe-4# colorimetric reagent developed color faster and eluted earlier than SSal, and Fe-4# was more sensitive under corrosive conditions.

[0134] Figure 9 The comparison chart shows the detection performance of Fe-4# and SSal under continuous corrosion apparatus. The results indicate that Fe-4# is highly sensitive, detecting iron as early as 5800 s, while SSal only detects iron at 9100 s, exhibiting relatively poor sensitivity. This is likely due to the masking effect of the large number of zinc ions in the corrosion solution, which strongly interferes with the colorimetric reagent. Furthermore, Fe-4# quickly reaches saturation, demonstrating fast response, excellent anti-interference properties, and high sensitivity. ICP-MS analysis of the corrosion solution at the peak elution and saturation points is shown in Tables 5 and 6.

[0135] Table 5. ICP-MS analysis report of Fe-4# and SSal peaks and saturation time points corresponding to corrosion samples.

[0136]

[0137] Table 6. Actual working test results of colorimetric reagents Fe-4# and SSal.

[0138] Peak SSal 3.8 4.47 0.67 14.9％ Saturated SSA 9.97 12.64 2.67 11.7％ Peak Fe-4# 1.08 1.17 0.09 7.69％ Saturated Fe-4# 7.9 8.64 0.74 8.56％

[0139] The table results show that the error between the content and the actual value of the colorimetric agent Fe-4# in the working curve is relatively small. However, the error between the content and the actual value of the colorimetric agent SSal in the working curve is relatively large. Therefore, in practical applications, colorimetric agent Fe-4# performs better than SSal.

[0140] Table 7 compares the performance of colorimetric agents Fe-4# and SSal under corrosive conditions.

[0141] Table 7

[0142] SSal 3.98 mg / L 3.24~9.08mg / L 961.8 mol / (L·cm) shallower Fe-4# 1.14 mg / L 2.64~7.08mg / L 3372 mol / (L·cm) obvious

[0143] As can be seen from Table 7, the colorimetric reagent Fe-4# itself determines the effect of Fe... 3+ It exhibits excellent recognition and sensing performance, and Fe-4# in the aqueous phase is found in Fe 3+ In the presence of [a specific substance], it changes from colorless to orange-red, exhibiting good color development. The novel color developer Fe-4# has a higher absorbance than SSal under the same conditions. Based on the 3σ / K formula, the absorbance of Fe-4# under corrosive conditions can be calculated for Fe [a specific substance]. 3+ The detection limit for + is 20.3 μM, which is much lower than that for Fe by SSal. 3+ The detection limit was 71.1 μM, the linear correlation coefficient reached 0.99974, and the molar absorbance of Fe-4# under corrosive conditions was calculated to be 3372 mol / (L·cm), which is much higher than the molar absorbance of SSal (961.8 mol / (L·cm).

[0144] Comparative Example 1

[0145] Reference Figure 10 This comparative example provides another Fe 3+ The specific methods for synthesizing ion probes (chromogenic agents) are as follows:

[0146] (1) Synthesis of Compound 1

[0147] In a 50 mL round-bottom flask, 2.50 g (5.30 mmol) of Rhodamine B was weighed and dissolved in 20 mL of anhydrous ethanol. After the solution was completely dissolved by stirring at room temperature, 5 mL of a solution containing 0.30 g (5.30 mmol) of ethylenediamine in ethanol was slowly added dropwise. The mixture was then refluxed at 80 °C for 10 hours. After concentration and drying, a light pink solid compound 1 (2.40 g, yield 86%) was obtained.

[0148] (2) Synthesis of compound Fe-1#

[0149] Compound 1 (0.50 g, 1.00 mmol) and salicylic acid (0.14 g, 1.00 mmol) were dissolved in a flask containing 25 mL of dichloromethane. After stirring for 15 min, EDCl (0.23 g, 1.20 mmol) and DMAP (0.10 g, 0.80 mmol) were added, and the reaction was carried out at room temperature for 16 h. After the reaction was completed, the crude product was concentrated and purified by column chromatography using CH2Cl2 / CH3OH (10:1, v / v) as the eluent to obtain a white solid Fe-1# (0.55 g, 90% yield), which is the colorimetric reagent Fe-1# of this comparative example.

[0150] Figure 11 The 1H NMR spectrum of Fe-1# is shown below, and the characterization data are as follows: 1 ¹H NMR (400MHz, CDCl₃) δ: 12.85 (s, 1H), 8.36 (s, 1H), 7.76 (dd, J = 7.4, 2.4Hz, 1H), 7.51 (d, J = 8.2Hz, 2H), 7.46–7.34 (m, 2H), 7.08 (dd, J = 6.2, 2.2Hz, 1H), 6.67–6.25 (m, 8H), 3.56–3.14 (m, 12H), 1.17 (t, 7.3Hz, 12H). The single hydrogen at the 12.85 ppm chemical shift can be attributed to the hydroxyl hydrogen on salicylic acid, the hydrogen at the 8.36 ppm shift to the amide, and the hydrogen at the 1.15 ppm shift to the -CH₃ group on Rhodamine B. These findings indicate the successful preparation of the colorant Fe-1#.

[0151] Application tests were conducted on Fe-1# according to the methods described in Examples 2-5. The results showed that although the Fe-1# colorimetric reagent exhibited good performance in neutral and weakly acidic / alkaline environments, it did not significantly affect Fe... 3+ While exhibiting good fluorescence detection capabilities, its performance under strongly acidic conditions is unsatisfactory. This is because the spontaneous ring-opening of the spironolactone ring in rhodamine under these conditions turns the solution pink, thus interfering with the detection of Fe. 3+ Fluorescence determination.

[0152] Comparative Example 2

[0153] Reference Figure 12 This comparative example provides another Fe 3+ The specific methods for synthesizing ion probes (chromogenic agents) are as follows:

[0154] 1 g (0.0062 mol) of 5-formylsalicylic acid and 1.1806 g (0.0065 mol) of 8-aminofluorene were added to a 50 ml side-necked flask, followed by the addition of 25 ml of EtOH. The mixture was refluxed at 70 °C for 4 h and passed through a column to obtain the colorimetric reagent Fe-2# for this comparative example.

[0155] Figure 13 The 1H NMR spectrum of Fe-2# is shown below, and the characterization data are as follows: 1 H NMR 1H NMR (400MHz, CD3Cl): δ13.38(s,1H),8.71(s,1H),7.80(dd,J=9.7,7.8Hz,2H),7.55(dd,J=7.6,1.1Hz, 1H),7.49(d,J=1.8Hz,1H),7.43–7.36(m,3H),7.34–7.29(m,2H),7.04(d,J=8.3Hz,1H),6.95(t,J=7.5 The concentrations of hydrogen atoms at 1 ppm (Hz, 1H) and 3.94 ppm (s, 2H) are as follows: 1 ppm is 1 ppm (Hz, 1H); 2 ppm is 3.94 ppm (s, 2H); 1 ppm is 1 ppm (s); 2 ppm is 3.94 ppm (s); 3 ppm is 3.94 ppm (s); 2 ppm is 3.94 ppm (s); and 2 ppm is 3.94 ppm (s); and 2 ppm is 3.94 ppm (s); and 3 ...

[0156] The application tests of Fe-2# were conducted according to the methods in Examples 2-5. The results showed that Fe-2# has a good effect on Fe in the organic phase. 3 It has good color development properties, but the color developer is not very water-soluble and requires DMSO to help dissolve it. However, it will also produce flocculent matter under pH>7 conditions. Moreover, Fe-2# is greatly affected by pH value and is unstable under strongly acidic conditions. It is not suitable for qualitative and quantitative analysis of the degree of corrosion of galvanized steel in corrosion systems.

[0157] Comparative Example 3

[0158] Reference Figure 14 This comparative example provides another Fe 3+ The specific methods for synthesizing ion probes (chromogenic agents) are as follows:

[0159] 1.35 g (6.2 mmol) of 5-sulfosalicylic acid and 0.9371 g (6.5 mmol) of 8-aminoquinoline were added to a 50 mL side-necked flask and dissolved in a flask containing 25 mL of dichloromethane. After stirring for 15 min, DCC (0.23 g, 1.20 mmol) and DMAP (0.10 g, 0.80 mmol) were added, and the reaction was carried out at room temperature for 16 h. After the reaction was completed, the crude product was concentrated and purified by column chromatography using CH2Cl2 / CH3OH (10:1, v / v) as the eluent to obtain a brown solid Fe-3#.

[0160] Figure 15 The 1H NMR spectrum of Fe-2# is shown below, and the characterization data are as follows: 1 ¹H NMR (400MHz, Chlor oform-d) δ 9.79 (s, 1H), 8.81 (d, J = 1.6Hz, 1H), 8.78–8.72 (m, 1H), 8.70 (s, 1H), 8.17 (d, J = 8.3Hz, 1H), 7.55 (d, J = 3.7Hz, 2H), 7.47 (dd, J = 8.3, 4.2Hz, 2H). The compound exhibits a singlet at chemical shift 8.17, which is the characteristic hydrogen of the carbon in the carbon-nitrogen double bond. The hydrogens of the quinoline ring itself are present at chemical shifts of 7.55, 7.47, 8.3, and 9.79 ppm, while the hydrogens of the salicylic acid benzene ring are present at chemical shifts of 8.81, 8.78–8.72, and 8.7 ppm. These data clearly indicate the successful synthesis of the colorant Fe-3#.

[0161] Application tests were conducted on Fe-2# according to the methods in Examples 2 to 5. The results showed that although Fe-3#, a novel colorimetric agent developed using salicylic acid as the parent material, has good water solubility and certain anti-interference properties, its complexation peak absorption intensity is low and the signal-to-noise ratio is small, making it inconvenient for detection.

[0162] Fe prepared in Comparative Example 1 and Comparative Examples 1-3 3+ The detection performance of the ion probe (chromogenic reagent) is shown in Table 8.

[0163] Table 8

[0164] Fe-1# √ √ √ √ 0.6~2.4mg / L 5.77ng / L Fe-2# √ × √ × — — Fe-3# √ × — — — — Fe-4# √ √ √ √ 1.12~11.2mg / L 1.45 mg / L

[0165] As can be seen from Table 8, the colorimetric reagent Fe-1# has a significant effect on Fe... 3+ It has excellent recognition and sensing performance, and Fe-1# in the aqueous phase is in Fe 3+ In the presence of Fe, it will change from colorless to pink, and at the same time, it affects Fe. 3+It has a good fluorescence enhancement response and excellent selectivity and anti-interference properties. However, because the rhodamine spironolactam ring in the colorimetric reagent Fe-1# will spontaneously open under strong acid conditions, turning the solution pink, its applicable conditions are not suitable for field operations.

[0166] Color developer Fe-2# for Fe 3+ It possesses colorimetric properties, but it lacks water solubility, making it unsuitable for qualitative and quantitative testing. The colorimetric reagent Fe-3#, in Fe... 3+ In the presence of Fe, it will change from colorless to brown; the color developer Fe-3# affects Fe. 3+ It has excellent acid and alkali resistance, but poor water solubility, low intensity of complex absorption peak, and overall properties far inferior to sulfosalicylic acid. Obviously, it is not suitable as a high-efficiency colorimetric agent.

[0167] The colorimetric agent Fe-4# prepared in Example 1 of this application has a positive effect on Fe... 3+ It exhibits excellent recognition and sensing performance, and Fe-4# in the aqueous phase is found in Fe 3+ In the presence of Fe, it changes from colorless to orange-red, exhibiting good color rendering. Fe-4# reacts with Fe... 3+ It has high detection sensitivity, a relatively wide detection linear range, and overall properties that are superior to SSal.

[0168] In summary, this invention provides a Fe 3+ Ion probes, their preparation methods, and applications: Based on the Schiff reaction, 5-formylsalicylic acid and p-aminobenzenesulfonic acid are mixed with EtOH, and the mixture is subjected to reflux reaction and vacuum distillation to obtain a crude product. The crude product is then purified by column chromatography to obtain a pale yellow solid, which is Fe. 3+ Ion probe, Fe 3+ Ion probe for Fe 3+ It exhibits excellent recognition and sensing performance, with absorbance exceeding that of the commercial colorimetric reagent SSal under the same conditions. In the aqueous phase, Fe... 3+ Ion probe in Fe 3+ In the presence of [a substance], it changes from colorless to orange-red, exhibiting good color development, and also shows good Fe [color development] under corrosive conditions. 3+ The ion detection effect shows promise for application in various corrosive environments.

[0169] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A Fe 3+ Ion probe, characterized in that: The Fe 3+ The structural formula of the ion probe is shown in formula (I); Equation (I).

2. The Fe as described in claim 1 3+ A method for preparing ion probes, characterized in that: The Fe 3+ The ion probes were synthesized based on the Schiff reaction, and the synthetic route is referenced in formula (II). Equation (II).

3. The Fe as described in claim 1 3+ A method for preparing ion probes, characterized in that: include, 5-Formylsalicylic acid and p-aminobenzenesulfonic acid were mixed with EtOH and refluxed. The crude product was obtained by vacuum distillation, and then purified by column chromatography to give a pale yellow solid, which was Fe. 3+ Ion probe.

4. The Fe as described in claim 3 3+ A method for preparing ion probes, characterized in that: The molar ratio of 5-formylsalicylic acid to p-aminobenzenesulfonic acid is 0.0062 mol: 0.0070 mol.

5. The Fe as described in claim 3 3+ A method for preparing ion probes, characterized in that: Each 1g of 5-formylsalicylic acid corresponds to 25ml of EtOH.

6. The Fe as described in claim 3 3+ A method for preparing ion probes, characterized in that: The reflux reaction was carried out at a temperature of 70°C for 4 hours.

7. The Fe as described in claim 3 3+ A method for preparing ion probes, characterized in that: The eluent for column chromatography purification was CH2Cl2 / CH3OH, with a volume ratio of 5:

1.

8. The Fe as described in claim 1 3+ Ion probes for detecting Fe 3+ The application of this technology is characterized by: The Fe 3+ Ion probe for Fe 3+ It has identification sensing capabilities; Fe 3+ In the aqueous phase, Fe 3+ Ion probe in Fe 3+ In its presence, it changes from colorless to orange-red, for Fe 3+ The linear detection range is 1.12–11.2 mg / L, for Fe 3+ The detection limit is 1.45 mg / L; The Fe 3+ Ion probe under corrosive solution conditions, Fe 3+ Ion probe for Fe 3+ The linear detection range is 2.64–7.08 mg / L, for Fe 3+ The detection limit is 1.14 mg / L, wherein the composition of the corrosive solution is 5% HAc + 0.05% NaNO3 + 0.8% Na2S2O8 + 5% NaCl.

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