Asymmetric imine molecular sensor with solvent-regulated six-detection function as well as preparation method and application of asymmetric imine molecular sensor

Abstract

The invention relates to the technical field of organic small molecule material detection, in particular to an asymmetric imine molecular sensor with a solvent-regulated six-detection function as well as a preparation method and application of the asymmetric imine molecular sensor. The imine molecular sensor shows different fluorescent'on-off 'detection responses to Cu < 2 + > / Co < 2 + > / Mn < 2 + > in a 90% CH3CN aqueous solution, and shows fluorescent'on-off' and absorption change double-signal responses to acid environment changes; in a 90% DMF aqueous solution, different fluorescence on-off responses are shown to Fe < 3 + > / Cu < 2 + >, and fluorescence on-off and absorption double-signal detection performance is shown to alkaline environment change; the imine molecular sensor and Co < 2 + > / Mn < 2 + > form a binary system which has different fluorescence on-off detection performance on Cu < 2 + >, and the detection is fast and sensitive. The imine molecular sensor provided by the invention has the advantages of mild synthesis conditions, simple preparation and the like, and creates favorable conditions for popularization and application of the imine molecular sensor.

Description

Technical Field

[0001] The present invention relates to the technical field of organic small molecule material detection, in particular to a method for detecting Fe 3+ 、Cu 2+ 、Co 2+ 、Mn 2+ Asymmetric imine molecular sensors and applications with sensitive detection capabilities for changes in acidic and alkaline environments. Background Art

[0002] While scientific and technological progress has driven the rapid development of my country's metals industry, the associated environmental pollution it generates has also constrained its sustainable development. The metals industry is complex, with numerous processes and numerous pollutants. Smelting processes emit significant amounts of heavy metal pollutants. Because metal ions are difficult to degrade and easily accumulate and expand within the food chain, coupled with their hidden, cumulative, and irreversible nature, once released into the environment, they can form a complex, dynamic, and long-term migration system, posing significant risks to ecosystems and the human environment. Irrigating land with wastewater containing excessive levels of heavy metal ions can not only reduce crop yields and quality, but can even cause plants to wither and die. While metals that enter the soil are not easily decomposed or lost, they are easily absorbed by organisms, causing food contamination. Once consumed, metal ion-contaminated water and food can accumulate in the body, causing serious harm. In pollution prevention and control, precise and rapid detection of metal ion contaminants, particularly at the source, is crucial for effectively preventing and controlling heavy metal pollution and safeguarding public health.

[0003] Current methods for metal ion detection include atomic absorption spectroscopy, atomic fluorescence spectroscopy, high-performance liquid chromatography and gas chromatography, and inductively coupled plasma mass spectrometry. While these analytical methods can accurately detect metal ion content, most suffer from limitations such as expensive instrumentation, complex operation, lengthy testing times, high requirements for analytical personnel, and high testing costs. Fluorescent molecular sensors rely on photosensitizers to respond to changes in fluorescence in the analyte, enabling qualitative and visual detection of the analyte at the molecular level. These precise and sensitive results have made them a key technology for detecting metal ions and have been widely used in industrial and agricultural production, environmental engineering, and other fields. However, most current fluorescent molecular sensors only offer sensitive detection performance for specific metal ions, have relatively limited functionality, and have significant application limitations. Furthermore, they often suffer from complex preparation processes, low yields, and high costs, making them difficult to meet the growing market demand. Multifunctional fluorescent molecular sensors not only avoid the need to prepare multiple single-molecule sensors but also offer higher detection efficiency compared to the sequential detection of single-function molecular sensors. However, relatively few multifunctional fluorescent molecular sensors have been developed, and their application in metal pollution detection, particularly in on-site pollution source analysis, is even rarer.

[0004] Furthermore, with rapid social development, the discharge of various waste acids and alkalis from industrial and agricultural production processes is increasing. When these untreated acids or alkalis are directly released into the soil, they can cause changes in the acidity or alkalinity of the surrounding environment, leading to plant wilt and animal death, posing significant risks to human production and daily life. Therefore, sensitive analytical testing technologies are needed in industrial and agricultural production to continuously monitor acid and alkali emissions that can pollute the water and soil resources on which people depend. Furthermore, efficient pH measurement technologies are needed to track industrial and agricultural production processes that require specific acidic or alkaline environments to function properly, thereby improving product quality and work efficiency. Fluorescent molecular sensors, due to their high sensitivity, good selectivity, and ease of operation, have become powerful tools for detecting pH changes in various fields. However, the fluorescence signals of most reported pH molecular sensors exhibit a single directional change: an "off-on" or "on-off" pattern with increasing or decreasing acidity. However, the demand for sensitive detection of dynamic pH changes in our daily lives and work is increasing. Therefore, the development of pH molecular sensors that are easy to prepare, sensitive, rapid, and widely applicable is urgently needed in various monitoring fields.

[0005] The easily synthesized imine -C=N- group has strong proton complexing ability. After connecting with the fluorophore, the p-π conjugation can increase the conjugation of the fluorescent molecule. When the nitrogen atom in the -C=N- group is complexed with the proton, it can induce sensitive fluorescence intensity or dual-channel spectral changes. Diaminomaleonitrile as a multi-site modified bridging group, the construction of imine molecular sensors has also attracted increasing attention [Y. Kang, Z. Liao, M. Wu, S. Li, D.-C. Fang, X.-J.Zheng, L.-P. Jin, Dalton Trans ., 2018, 47, 13730–13738; H. Zhou a, J. Wang, Y.Chen, W. Xi, Z. Zheng, D. Xu, Y. Cao, G. Liu, W. Zhu, J. Wu, Y. Tian, ​​Dyes and Pigments, 2013, 98, 1-10]. However, at present, the Fe 3+ 、Cu 2+ 、Co 2+ 、Mn 2+ Molecular sensors with six-fold detection functions, such as changes in acid-base environment, have not yet been developed. Summary of the Invention

[0006] In view of the problems existing in the prior art, the present invention provides a solvent-regulated Fe3+ 、Cu 2+ 、Co 2+ 、Mn 2+ A molecular sensor with six detection functions for changes in acid and alkaline environments is provided. The molecular sensor is an asymmetric trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule.

[0007] The present invention is achieved through the following technical solutions: A solvent-regulated molecular sensor with six detection functions, wherein the sensor is an asymmetric trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule, and its structure is: .

[0008] The molecular sensor is easy to prepare and has good sensitivity to Fe 3+ 、Cu 2+ 、Co 2+ 、Mn 2+ , acid and alkaline environment changes have different optical detection signals, which can realize different systems Fe 3+ 、Cu 2+ 、Co 2+ 、Mn 2+ , acid and alkaline environment changes quickly and accurately detect.

[0009] Another object of the present invention is to provide a method for preparing the asymmetric trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule, comprising the following steps: S1. Diaminomaleonitrile was placed in a round-bottom flask containing anhydrous ethanol, followed by the addition of 4-diethylamino salicylaldehyde and glacial acetic acid, and the reaction temperature was raised to reflux for 4 hours; the reaction mixture was filtered, washed with anhydrous ethanol, and dried to obtain a flesh-red monoaminomaleonitrile-4-diethylamino salicylic acid compound; S2. The monoaminomaleonitrile-4-diethylamino salicylate obtained in step S1 is placed in a dichloromethane-anhydrous ethanol mixed solvent, 4-trifluoromethylbenzaldehyde and concentrated sulfuric acid are added, and the temperature is raised to reflux for 4-6 hours. The resulting reaction mixture is filtered, washed with anhydrous ethanol, and dried to obtain a dark green trifluoromethylbenzene-maleonitrile-diethylamino salicylate compound.

[0010] Furthermore, in step S2, the molar ratio of the monoaminomaleonitrile-4-diethylamino salicylic compound and 4-trifluoromethylbenzaldehyde is 1:1, the volume ratio of dichloromethane and anhydrous ethanol in the mixed solvent is 1:4, the amount of the mixed solvent added is limited to 30 mL of the mixed solvent for every 1 mmol of monoaminomaleonitrile-4-diethylamino salicylic compound, and the amount of the concentrated sulfuric acid added is 100 μL of concentrated sulfuric acid for every 1 mmol of 4-trifluoromethylbenzaldehyde.

[0011] The preparation reaction formula of the trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecular sensor is: .

[0012] The third object of the present invention is to provide the trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule on Cu 2+ 、Co 2+ 、Mn 2+ Application of detection.

[0013] The specific performance is as follows: in 90% CH3CN aqueous solution, the molecular sensor has a strong maximum fluorescence emission near 623 nm; when 10 times Co 2+ After adding 10 times of Mn 2+ After adding 10 times of Cu 2+ After the addition of other metal ions, the maximum fluorescence emission of the asymmetric molecular sensor did not show obvious changes.

[0014] The fourth object of the present invention is to provide the trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule Fe 3+ 、Cu 2 + Application of detection.

[0015] The specific performance is as follows: in 90% DMF aqueous solution, the asymmetric molecular sensor has a strong maximum fluorescence emission near 633 nm; when 10 times Fe 3+ After adding 10 times of Cu 2+ After the addition of other metal ions, the maximum fluorescence emission intensity of the molecular sensor did not show obvious changes.

[0016] The fifth object of the present invention is to provide the application of the trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule in acidic environment detection.

[0017] The specific performance is as follows: in a 90% CH3CN aqueous solution, as the amount of HCl added gradually increases, the maximum fluorescence emission of the asymmetric molecular sensor near 623 nm red-shifts to near 629 nm, accompanied by an 80% decrease in emission intensity. At the same time, its maximum absorption at 560 nm gradually decreases and disappears, and a weak absorption peak appears near 350 nm, giving the asymmetric molecular sensor the performance of fluorescence "off-on" and ultraviolet absorption dual signal detection in acidic environments.

[0018] The sixth object of the present invention is to provide the application of the trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule in alkaline environment detection.

[0019] The specific performance is as follows: in a 90% DMF aqueous solution, as the amount of NaOH added gradually increases, the maximum fluorescence emission of the asymmetric molecular sensor near 633 nm red-shifts to near 640 nm, and the fluorescence emission intensity gradually decreases by 76%. At the same time, its maximum absorption at 570 nm red-shifts to near 600 nm, giving the asymmetric molecular sensor the performance of fluorescence "off-on" and absorption dual-signal detection in acidic environments.

[0020] Compared with the prior art, the present invention has the following technical effects: the trifluoromethylbenzene-maleonitrile-diethylamino-based salicylic acid molecular sensor has a strong coordination ability for metal ions through multiple sites such as imine and hydroxyl groups, and the imine group can induce sensitive optical signal changes after participating in the coordination, so that it can react with Cu in 90% CH3CN aqueous solution. 2+ / Co 2+ / Mn 2+ The fluorescence emission showed different "on-off" detection responses to Fe in 90% DMF aqueous solution. 3+ / Cu 2+ The imine molecular sensor exhibits different fluorescence emission "on-off" signal responses; the imine molecular sensor exhibits fluorescence "on-off" and absorption change dual signal detection performance in an acidic environment in a 90% CH3CN aqueous solution, and exhibits fluorescence "on-off" and absorption change dual signal detection performance in an alkaline environment in a 90% DMF aqueous solution; the imine molecular sensor and Co 2+ / Mn 2+ The formed binary system has a great influence on Cu 2+ The different fluorescence "on-off" signal detection properties endow the imine single molecule sensor with Fe 3+ / Cu 2+ / Co 2+ / Mn 2+ / acid / alkali six-target detection function and Cu 2+ It exhibits four-analysis detection characteristics, is quick and sensitive in detection, and has high application value; the preparation process of the trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecular sensor provided by the present invention has the advantages of high yield and mild synthesis conditions, is suitable for industrial implementation, and creates favorable conditions for the promotion and application of the trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecular sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the NMR image of trifluoromethylbenzene-maleonitrile-diethylamino salicylate molecule.

[0022] Figure 2The fluorescence emission detection performance of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule for different metal ions in 90% CH3CN aqueous solution.

[0023] Figure 3 These are photos of trifluoromethylbenzene-maleonitrile-diethylamino salicylate molecules under ultraviolet light after reacting with different metal ions in 90% CH3CN aqueous solution.

[0024] Figure 4 This is the fluorescence emission spectrum of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecules interacting with different concentrations of copper in 90% CH3CN aqueous solution.

[0025] Figure 5 These are photos of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecules reacting with different concentrations of copper in 90% CH3CN aqueous solution under ultraviolet light.

[0026] Figure 6 The trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule reacts with Co in 90% CH3CN aqueous solution. 2+ Competes with other metal ions for selectivity.

[0027] Figure 7 The reaction of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecules with Mn in 90% CH3CN aqueous solution 2+ Competes with other metal ions for selectivity.

[0028] Figure 8 The reaction of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecules with Cu in 90% CH3CN aqueous solution was investigated. 2+ Compete with other metal ions for selective properties.

[0029] Figure 9 The fluorescence emission detection performance of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule for different metal ions in 90% DMF aqueous solution.

[0030] Figure 10 The fluorescence emission properties of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecules in 90% CH3CN aqueous solution reacted with different concentrations of HCl.

[0031] Figure 11 The UV absorption properties of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecules in 90% CH3CN aqueous solution reacted with different concentrations of HCl.

[0032] Figure 12 The fluorescence emission properties of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecules in 90% DMF aqueous solution reacted with different concentrations of HCl.

[0033] Figure 13The UV absorption properties of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecules reacting with different concentrations of HCl in 90% DMF aqueous solution.

[0034] Figure 14 The fluorescence emission properties of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecules in 90% DMF aqueous solution reacted with different concentrations of NaOH.

[0035] Figure 15 This is the UV absorption performance of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecules in 90% DMF aqueous solution with different concentrations of NaOH. DETAILED DESCRIPTION

[0036] The present invention discloses a trifluoromethylbenzene-maleonitrile-diethylamino-based salicylic acid molecular sensor with six detection functions controlled by solvent, and its molecular structure is: .

[0037] It can be prepared by a two-step polymerization reaction using 4-diethylamino salicylaldehyde, diaminomaleonitrile and 4-trifluoromethylbenzaldehyde as reaction raw materials. The synthesis reaction formula is: .

[0038] Example 1 Preparation of Compound A: Place 1 mmol of 4-diethylaminosalicylaldehyde in a round-bottom flask containing 15 mL of anhydrous ethanol, followed by 1 mmol of diaminomaleonitrile and 100 μL of glacial acetic acid. Heat to reflux and react for 4 hours. Filter the reaction mixture, wash with anhydrous ethanol, and dry to obtain a flesh-red monoaminomaleonitrile-4-diethylaminosalicylaldehyde compound.

[0039] 1 mmol of monoaminomaleonitrile-4-diethylamino salicylate was placed in 30 mL of a 1:4 dichloromethane-ethanol mixed solvent, 1 mmol of 4-trifluoromethylbenzaldehyde and 100 μL of concentrated sulfuric acid were added, and the temperature was raised to reflux for 4 hours. The reaction mixture was filtered, washed with anhydrous ethanol, and dried to obtain a black-green trifluoromethylbenzene-maleonitrile-diethylamino salicylate compound A (276.7 mg) with a yield of 63%.

[0040] Preparation of Compound B: Place 1 mmol of 4-diethylaminosalicylaldehyde in a round-bottom flask containing 15 mL of anhydrous ethanol, followed by 1 mmol of diaminomaleonitrile and 100 μL of glacial acetic acid. Heat to reflux and react for 4 hours. Filter the reaction mixture, wash with anhydrous ethanol, and dry to obtain a flesh-red monoaminomaleonitrile-4-diethylaminosalicylaldehyde compound.

[0041] 1 mmol of monoaminomaleonitrile-4-diethylamino salicylate was placed in 30 mL of a 1:4 dichloromethane-ethanol mixed solvent. 1 mmol of 4-trifluoromethylbenzaldehyde and 100 μL of concentrated sulfuric acid were added, and the reaction was heated to reflux for 6 hours. The reaction mixture was filtered, washed with anhydrous ethanol, and dried to obtain 285.4 mg of a black-green trifluoromethylbenzene-maleonitrile-diethylamino salicylate compound B in a 65% yield.

[0042] Compounds A and B obtained in Examples 1 and 2 were analyzed and determined by NMR. Figure 1 To, see Figure 1 , the NMR data are as follows: 1 H NMR (400 MHz, CDCl3) δ 12.85 (s, 1H), 8.55 (d, 2H), 7.26 (m,4H), 6.43 (t, 3H), 3.49 (m, 4H), 3.28 (t, 2H), 1.28 (m, 6H); MS: ion peak m / z 439.45, [theoretical calculation value M + 439.16]; indicating that the theoretical values ​​of compound A / B are basically consistent with those of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid compound. Therefore, the molecular structures of compound A and B can be confirmed as follows: , that is, trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule.

[0043] Example 3 Fluorescence detection function of trifluoromethylbenzene-maleonitrile-diethylamine-based salicylic acid molecular sensor for different metal ions in 90% CH3CN aqueous solution: In 90% CH3CN aqueous solution, the concentration is 1×10 -5 mol / L trifluoromethylbenzene-maleonitrile-diethylamine-based salicylic acid molecular sensor has a maximum fluorescence emission near 623 nm; 10 times Co 2+ After addition, the maximum fluorescence emission intensity decreased by 51%; 10-fold Mn 2+ After addition, the maximum fluorescence emission intensity decreased by 75%; 10 times Cu 2+ After addition, its maximum fluorescence emission is quenched; other metal ions such as K + Mg 2+ 、Li + Cr 3+ 、Cd 2+ 、Al 3+ 、Hg 2+ , Pb 2+ 、Zn 2+ , Ca 2+ 、Ba 2+ 、Na+ and Ni 2+ After addition, the fluorescence emission spectrum of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecules did not change significantly. For specific results, see Figure 2 Under 365 nm ultraviolet (UV) light, the trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecular sensor solution emits red fluorescence. 2+ 、Mn 2+ After adding, its red fluorescence emission weakened, Cu 2+ After adding, its red fluorescence emission disappears, and after adding other metal ions, its red fluorescence emission remains basically unchanged. For specific results, see Figure 3 These results indicate that the trifluoromethylbenzene-maleonitrile-diethylamine-based salicylic acid molecular sensor is effective for Co 2+ 、Mn 2+ 、Cu 2+ It has the potential for sensitive and intuitive fluorescence "off-on" detection.

[0044] Example 4 The trifluoromethylbenzene-maleonitrile-diethylamino-based salicylic acid molecular sensor reacts with different concentrations of Cu 2+ Fluorescence detection function of ions: In 90% CH3CN aqueous solution, the concentration is 1×10 -5 mol / L trifluoromethylbenzene-maleonitrile-diethylamine-based salicylic acid molecular sensor and different concentrations of Cu 2+ The fluorescence emission spectrum in the presence of Cu is as follows: 2+ When the concentration increased from 0 to 4 times the molar amount, the maximum fluorescence emission intensity of the compound at around 623 nm gradually decreased or was even completely quenched; 2+ Even when the concentration reaches 10 times the molar amount, the fluorescence emission spectrum remains basically unchanged. For specific results, see Figure 4 ; Under 365 nm ultraviolet (UV) light, with the addition of Cu 2+ As the concentration increases from 0 to 4 times the molar amount, the red fluorescence emission of the trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecular sensor solution gradually weakens and disappears. For specific results, see Figure 5 , indicating that trifluoromethylbenzene-maleonitrile-diethylamine-based salicylic acid molecular sensor is sensitive to Cu 2+ It has the potential for sensitive and intuitive fluorescence "off-on" identification.

[0045] Example 5 Co in trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecular sensor 2+ Optical competition performance with other metal ions: In 90% CH3CN aqueous solution, the concentration is 1×10 -510 times Co was added to the trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule at the same time. 2+ The fluorescence emission spectrum of the mixed system of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule after adding 10 times Co 2+ After that, the binary system has a weak maximum fluorescence emission near 623 nm; when K + Mg 2+ 、Li + 、Co 2+ Cr 3+ 、Cd 2+ 、Al 3+ 、Hg 2+ , Pb 2+ , Ca 2+ 、Ba 2+ 、Na + and Ni 2+ Other metal ions and Co 2+ After adding trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecular solution at the same time, the ternary mixed system and the molecular sensor-Co 2+ The fluorescence emission spectra of the binary system are similar; however, the molecular sensor-Co 2+ Adding Cu to the binary system 2+ After that, the fluorescence emission of the mixed system was quenched. For detailed results, see Figure 6 These results indicate that trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecules not only 2+ showed good selective detection performance, which was consistent with Co 2+ Binary system for Cu 2+ With fluorescence "on-off" detection performance.

[0046] Example 6 Mn in trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecular sensor 2+ Competitive performance of spectroscopy with other metal ions: In 90% CH3CN aqueous solution, the concentration is 1×10 -5 10 times the amount of Mn was added to the trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule. 2+ The fluorescence emission spectrum of the mixed system of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule after adding 10 times of Mn 2+ After that, the binary system has a weak maximum fluorescence emission near 622 nm; when K + Mg 2+ 、Li + 、Co 2+ Cr 3+ 、Cd 2+ 、Al 3+ 、Hg2+ , Pb 2+ , Ca 2+ 、Ba 2+ 、Na + and Ni 2+ Other metal ions and Mn 2+ After adding trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule solution at the same time, the fluorescence emission spectrum of the ternary system is similar to that of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule-Mn 2+ The fluorescence spectra of the binary system are similar; however, when Cu 2+ After that, the fluorescence emission of the mixed system was quenched. For detailed results, see Figure 7 These results indicate that trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecules not only 2+ It showed good selective detection performance, which was consistent with Mn 2+ Binary system for Cu 2+ With fluorescence "on-off" detection performance.

[0047] Example 7 Cu in trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecular sensor 2+ Competitive performance of spectroscopy with other metal ions: In 90% CH3CN aqueous solution, the concentration is 1×10 -5 10 times of Cu was added to the trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule at the same time. 2+ The fluorescence emission spectrum of the mixed system of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule after adding 10 times Cu 2+ After that, the fluorescence emission of the molecular sensor was almost completely quenched; when K + Mg 2+ 、Li + 、Co 2+ Cr 3+ 、Cd 2+ 、Al 3+ 、Hg 2+ , Pb 2+ , Ca 2+ 、Ba 2+ 、Na + and Ni 2+ Metal ions such as Cu 2+ After adding trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule solution at the same time, the ternary system has almost no fluorescence emission, and the trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule-Cu 2+ The fluorescence spectra of the binary system are similar. For detailed results, see Figure 8 These results indicate that trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecules can be used to treat Cu 2+Shows good selection detection performance.

[0048] Example 8 Fluorescence detection function of trifluoromethylbenzene-maleonitrile-diethylamine-based salicylic acid molecular sensor for different metal ions in 90% DMF aqueous solution: In 90% DMF aqueous solution, the concentration is 1×10 -5 mol / L trifluoromethylbenzene-maleonitrile-diethylamine-based salicylic acid molecular sensor has a maximum fluorescence emission near 633 nm; 10 times Fe 3+ After addition, the maximum fluorescence emission intensity decreased by 65%; 10 times Cu 2+ After addition, the maximum fluorescence emission intensity decreased by 82%; other metal ions such as K + Mg 2+ 、Li + Cr 3+ 、Cd 2+ 、Al 3+ 、Hg 2+ , Pb 2+ 、Zn 2+ 、Mn 2+ 、Co 2+ , Ca 2+ 、Ba 2+ 、Na + and Ni 2+ After addition, the fluorescence emission of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecules changed slightly. For specific results, see Figure 9 These results indicate that the trifluoromethylbenzene-maleonitrile-diethylamine-based salicylic acid molecular sensor is sensitive to Fe 3+ 、Cu 2+ With different fluorescence "on-off" detection potential.

[0049] Example 9 Optical detection function of trifluoromethylbenzene-maleonitrile-diethylamine-based salicylic acid molecular sensor in 90% CH3CN aqueous solution for different acidic environments: In 90% CH3CN aqueous solution, the concentration is 1×10 -5 The fluorescence emission spectra of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecules in the presence of different concentrations of HCl are as follows: As the concentration of HCl added increases from 0 to 100 times the molar equivalent, the maximum fluorescence emission of the molecular sensor near 623 nm red-shifts to 629 nm, and the fluorescence emission intensity decreases by 80%. The specific results are shown in Figure 10The UV absorption spectrum showed that as the HCl concentration increased from 0 to 100 times the molar amount, the maximum absorption of the molecular sensor at around 560 nm disappeared, and a new weak absorption appeared at around 350 nm. When the HCl concentration was further increased to 300 times the molar amount, the UV absorption spectrum remained basically unchanged. For specific results, see Figure 11 These results indicate that the trifluoromethylbenzene-maleonitrile-diethylamine-based salicylic acid molecular sensor has the potential for sensitive fluorescence "on-off" and UV absorption double-peak ratio dual-signal detection in response to changes in acidic environment in 90% CH3CN aqueous solution.

[0050] Example 10 Optical detection function of trifluoromethylbenzene-maleonitrile-diethylamine-based salicylic acid molecular sensor in 90% DMF aqueous solution for different acidic environments: In 90% DMF aqueous solution, the concentration is 1×10 -5 The fluorescence emission spectra of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecules in the presence of different concentrations of HCl are as follows: As the concentration of HCl increases from 0 to 300 times the molar equivalent, the maximum fluorescence emission intensity of the molecular sensor near 633 nm decreases by 25%. The specific results are shown in Figure 12 The UV absorption spectrum showed that the maximum absorption absorbance of the molecular sensor at 570 nm decreased slightly as the HCl concentration increased from 0 to 300 times the molar amount. Figure 13 ; It shows that the trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecular sensor has no sensitive optical signal detection response to changes in acidic environment in 90% DMF aqueous solution.

[0051] Example 11 Optical detection function of trifluoromethylbenzene-maleonitrile-diethylamine-based salicylic acid molecular sensor in 90% DMF aqueous solution in different alkaline environments: In 90% DMF aqueous solution, the concentration is 1×10 -5 The fluorescence emission spectra of trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecules in the presence of different concentrations of NaOH are as follows: As the concentration of NaOH increases from 0 to 150 times the molar equivalent, the maximum fluorescence emission of the molecular sensor near 633 nm red-shifts to 640 nm, and the fluorescence emission intensity decreases by 76%. The specific results are shown in Figure 14 The UV absorption spectrum shows that as the NaOH concentration increases from 0 to 150 times the molar amount, the maximum absorption of the molecular sensor near 570 nm shifts red to around 600 nm. Figure 15 In 90% CH3CN aqueous solution, the concentration is 1×10 -5After adding 300 molar equivalents of NaOH to a 1.5 mol / L trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule, its maximum fluorescence emission near 623 nm remained almost unchanged, and the corresponding UV absorption spectrum changed slightly. These results demonstrate the potential of the trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecular sensor for dual-signal detection of both the "on-off" fluorescence and the ratio of the UV absorption double peaks in alkaline environments in 90% DMF aqueous solution.

Claims

1. A solvent-regulated asymmetric imine molecular sensor with six detection functions, wherein the sensor is an asymmetric trifluoromethylbenzene-maleonitrile-diethylamino salicylic acid molecule, and its structure is: 。 2. A method for preparing an asymmetric imine molecular sensor according to claim 1, characterized in that: The steps include: S1. Place diaminomaleonitrile in a round-bottom flask containing anhydrous ethanol, add 4-diethylamino salicylaldehyde and glacial acetic acid in sequence, and heat to reflux for 4 hours; filter the reaction mixture, wash with anhydrous ethanol, and dry to obtain a flesh-red monoaminomaleonitrile-4-diethylamino salicylic acid compound; S2. The monoaminomaleonitrile-4-diethylamino salicylate compound obtained in step S1 is placed in a dichloromethane-anhydrous ethanol mixed solvent, 4-trifluoromethylbenzaldehyde and concentrated sulfuric acid are added, and the temperature is raised to reflux for reaction for 4-6 hours; the reaction mixture is filtered, washed with anhydrous ethanol, and dried to obtain a black-green trifluoromethylbenzene-maleonitrile-diethylamino salicylate molecular sensor.

3. The method for preparing the imine molecular sensor according to claim 2, characterized in that: In step S2, the molar ratio of the monoaminomaleonitrile-4-diethylamino salicylic compound and 4-trifluoromethylbenzaldehyde is 1:1, the volume ratio of dichloromethane and anhydrous ethanol in the mixed solvent is 1:4, the amount of the mixed solvent added is limited to 30 mL of the mixed solvent per 1 mmol of monoaminomaleonitrile-4-diethylamino salicylic compound, and the amount of concentrated sulfuric acid added is 100 μL of concentrated sulfuric acid per 1 mmol of 4-trifluoromethylbenzaldehyde.

4. An asymmetric imine molecular sensor as claimed in claim 1 on Cu 2+ 、Co 2+ 、Mn 2+ Applications in detection, which do not involve the diagnosis and treatment of diseases, are characterized by: In 90% CH3CN aqueous solution, the molecular sensor has a strong maximum fluorescence emission near 623 nm; when Cu 2+ 、Co 2+ 、Mn 2+ After that, its maximum fluorescence emission showed different degrees of "on-off" detection response.

5. The asymmetric imine molecular sensor according to claim 4 is used in Cu 2+ The application in detection is characterized by: In 90% CH3CN aqueous solution, the asymmetric imine molecular sensor was reacted with Co 2+ The constructed binary system is used for fluorescence "on-off" detection and recognition of Cu 2+ ; In 90% CH3CN aqueous solution, the asymmetric imine molecular sensor was reacted with Mn 2+ The constructed binary system is used for fluorescence "on-off" detection and recognition of Cu 2+ .

6. Use of the asymmetric imine molecular sensor according to claim 1 in acidic environment detection, characterized in that: In a 90% CH3CN aqueous solution, as the acidic environment increases, the maximum fluorescence emission intensity of the asymmetric imine molecular sensor at 623 nm decreases and red-shifts, while its maximum absorption gradually decreases to disappear, showing a fluorescence "on-off" and ultraviolet absorption dual signal detection response to changes in the acidic environment.

7. An asymmetric imine molecular sensor as claimed in claim 1 in Fe 3+ 、Cu 2+ Applications in detection, which do not involve the diagnosis and treatment of diseases, are characterized by: In 90% DMF aqueous solution, the asymmetric molecular sensor has a strong maximum fluorescence emission near 633 nm. 3 + 、Cu 2+ After addition, it exhibits different fluorescence emission "on-off" signal detection functions.

8. Use of the asymmetric imine molecular sensor according to claim 1 in alkaline environment detection, characterized in that: In a 90% DMF aqueous solution, as the alkaline environment increases, the maximum fluorescence emission intensity of the imine molecular sensor at 633 nm red-shifts, and its maximum absorption red-shifts, showing a fluorescence "on-off" and ultraviolet absorption dual signal detection response to changes in the alkaline environment.

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