CN112457274A

CN112457274A - N- (2' -morpholinoethyl) -N- (pyrene formyl) amine and application thereof in pH detection

Info

Publication number: CN112457274A
Application number: CN202011332869.8A
Authority: CN
Inventors: 马立军; 王莎; 黄子杰; 刘鸿; 张中岩; 雷晓兰
Original assignee: South China Normal University
Current assignee: South China Normal University
Priority date: 2020-11-24
Filing date: 2020-11-24
Publication date: 2021-03-09
Anticipated expiration: 2040-11-24
Also published as: CN112457274B

Abstract

The invention relates to the technical field of analysis and detection, in particular to N- (2' -morpholine ethyl) -N- (pyrene formyl) amine and application thereof in pH detection, the compound obtained by the invention has good water solubility, is easy to prepare aqueous solution, has quick response and stable fluorescence, and can conveniently detect the pH value in the aqueous solution; MPA is a pH fluorescent probe with high sensitivity and wide detection range, has identification effect on pH within the range of 0.52-8.19, and common ions do not influence the specific identification of MPA on pH; the MPA as a pH fluorescent probe under an acidic condition has the characteristics of wide application range, strong identification, good accuracy and the like, and is suitable for popularization and application.

Description

N- (2' -morpholinoethyl) -N- (pyrene formyl) amine and application thereof in pH detection

Technical Field

The invention relates to the technical field of analysis and detection, and particularly relates to N- (2' -morpholine ethyl) -N- (pyrene formyl) amine and application thereof in pH detection.

Technical Field

The pH value is an important parameter in the processes of chemical production condition formulation, environmental assessment, biological metabolism and the like, and plays an extremely important role in production and life of people. The acidic industrial wastewater easily causes the large-scale growth and development abnormity and even death of aquatic animals and plants, reduces the yield of irrigated crops and aquatic animals, gradually becomes a global problem, and brings huge pressure to the irrigation agriculture and aquaculture industry. In addition, acidic water can dissolve more harmful heavy metals, thereby causing various diseases such as chronic poisoning, alzheimer's disease, brain death and skin cancer. Therefore, the development of a pH detection method with high sensitivity and wide application range has important significance. Methods for detecting pH generally include electrochemical methods, colorimetry, gas chromatography, biological and nanosensor means. These test methods have a common disadvantage in that complicated and various sample preparation and sophisticated laboratory instruments are required, resulting in high analysis cost and difficulty in real-time detection. The fluorescent probe method has the characteristics of high sensitivity, simple sample preparation, low cost and the like, is concerned in many years, and develops many pH fluorescent probes with high sensitivity and strong anti-interference capability, but the pH fluorescent probes usually have only one pKa value and cannot respond stage by stage, so that the application requirements of high sensitivity and wide detection range are difficult to meet at the same time.

Disclosure of Invention

The invention aims to overcome the technical problems in the prior art and provides a novel compound N- (2' -morpholine ethyl) -N- (pyrene formyl) amine.

Another object of the present invention is to provide a process for the preparation of the above compounds

Another object of the present invention is the use of the above compounds for pH detection.

The purpose of the invention is realized by the following technical scheme:

n- (2' -morpholinoethyl) -N- (pyrene formyl) amine with the structure as shown in formula (I)

Abbreviated as MPA.

The preparation method of the N- (2' -morpholine ethyl) -N- (pyrene formyl) amine comprises the steps of dissolving pyrene formic acid and N- (2-aminoethyl) morpholine into CH₂Cl₂In a solvent; and adding EDC & HCl, stirring at room temperature for 20-30 h, and purifying after stirring is finished to obtain the catalyst. The mass ratio of pyrene formic acid to N- (2-aminoethyl) morpholine is 1: (0.5-5).

The preparation of pyrene formic acid comprises the following steps:

1) dissolving KMnO by deionized water solution₄A solid;

2) dissolving pyrene formaldehyde in acetone, and adding into the mixture containing KMnO₄The solution is added dropwise and stirred, and after the dropwise addition is finished, the solution is heated to 70 ℃ and stirred until the reaction is complete;

3) adding a large amount of deionized water for dilution, adjusting the pH value of the solution to be strong alkaline by using sodium hydroxide, filtering, adjusting the pH value of the filtrate to be strong acidic by using concentrated hydrochloric acid, immediately separating out a large amount of yellow solid, performing vacuum filtration and drying the solid to obtain a crude product pyrene formic acid, and directly using the crude product pyrene formic acid in the next reaction.

Pyrene formaldehyde and KMnO in step 2)₄The mass ratio of (1): (2-10).

Preferably, the purification treatment comprises: after the stirring is finished, CH is removed by reduced pressure distillation₂Cl₂The solvent is passed through a column with a dichloromethane/ethanol mixed developing agent and then evaporated to dryness by a reduced pressure distillation method.

The N- (2' -morpholine ethyl) -N- (pyrene formyl) amine is applied to pH detection.

The application of the N- (2' -morpholine ethyl) -N- (pyrene formyl) amine in pH detection comprises the following steps:

s01, drawing a standard curve

Preparing a pH standard solution, adding the standard solutions with different pH values into an N- (2' -morpholinoethyl) -N- (pyrene formyl) amine solution, and recording the fluorescence intensity and the emission peak wavelength of the solution; MPA has an excitation wavelength of 280nm and an emission wavelength of 413 nm. Drawing a standard curve by taking the fluorescence intensity and the pH at the same wavelength as coordinate axes;

s02, adding a solution to be detected into an N- (2' -morpholinoethyl) -N- (pyrene formyl) amine solution, and recording the solution intensity and the emission peak wavelength;

and S03, calculating according to the fluorescence emission peak wavelength and the corresponding standard curve to obtain the pH value of the liquid to be detected.

s11, preparing pH detection test paper

Uniformly coating a specific N- (2' -morpholinoethyl) -N- (pyrene formyl) amine solution on a filter paper;

s12, manufacturing a standard colorimetric card

Dripping a solution with known pH on filter paper soaked with the N- (2' -morpholinoethyl) -N- (pyrene formyl) amine solution, and shooting and recording the color of the test paper;

s13, dropwise adding the solution to be detected on the detection test paper prepared in the step S11, and comparing the solution to be detected with the standard colorimetric card prepared in the step S12 to obtain the pH value of the solution to be detected.

The concentration of MPA in the detection method is (5-30) x 10^-6mol/L。

And (3) a pH test paper containing the N- (2' -morpholinoethyl) -N- (pyrene formyl) amine.

Compared with the prior art, the invention has the following technical effects:

1) the MPA of the invention has good water solubility, can be easily prepared into aqueous solution, can conveniently detect the pH value in the aqueous solution, and is a sensitive fluorescent probe for identifying the pH value.

2) In the invention, when MPA is used for detecting pH, the pH range of the solution is 0.52-8.19, the pH has two pKa values of 1.88 and 5.81, the pH shows different colors of staged response, and the probe has high sensitivity, wide application range and high accuracy in recognition effect.

3) The MPA of the present invention exhibits a strong fluorescence response signal to pH: the fluorescence spectrum of MPA shows sensitive fluorescence emission intensity and emission peak shift with pH change when the excitation wavelength is 280 nm.

4) The method for directly detecting the pH value in the aqueous solution by adopting the fluorescent probe has the advantages of strong operability, wide detection range, high sensitivity, strong anti-interference capability and the like.

5) The method can be used for preparing the pH test paper with obvious fluorescence change, and has the advantages of simple operation, high accuracy and wide detection range.

Drawings

FIG. 1 shows the molecular structure of MPA obtained by the present invention;

FIG. 2 is a graph showing the results of MPA cation mass spectrometry performed according to the present invention;

FIG. 3 is a graph of nuclear magnetic test results for MPA obtained by the present invention;

FIG. 4 shows the concentration of 2.0X 10 under the conditions of extreme acidity of 0.52, 1.04, 1.37, 1.54, 1.85, 2.45, 3.3 and 4.05 (FIG. 4a) and weak acidity of 4.05, 4.71, 5.4, 6.02, 6.56, 7.03, 7.58 and 8.19 (FIG. 4b)^-5The change curve of the fluorescence emission intensity in the MPA solution of mol/L (the excitation wavelength is 280 nm);

FIG. 5 MPA solutions (concentration 2.0X 10) at different pH^-5mol/L), change of fluorescence emission intensity at 413 nm;

FIG. 6 MPA solutions (concentration 2.0X 10) at different pH^-5mol/L), a standard curve change chart of a fluorescence emission peak;

FIG. 7 is a time chart of the MPA obtained by the present invention versus the color change in pH;

FIG. 8 shows a control card of pH indicator paper containing MPA obtained by the present invention;

FIG. 9 with addition of 2.0X 10, respectively^-6mol/L of Ba²⁺、Ni²⁺、Ag⁺、Mn²⁺、Hg²⁺、K⁺、Zn²⁺、 Cu²⁺、Fe³⁺、Fe²⁺、Al³⁺、NO₃ ^-、F^-After the common ion, 2.0X 10^-6Fluorescence intensity of mol/L MPA solution under 280nm ultraviolet irradiation.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below with reference to specific examples and comparative examples. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.

Unless otherwise specified, the devices used in this example are all conventional experimental devices, the materials and reagents used are commercially available, and the experimental method without specific description is also a conventional experimental method.

Example 1

N- (2' -morpholinoethyl) -N- (pyrene formyl) amine (MPA) with the structure as shown in formula (I)

Synthetic route of MPA:

1) synthesis of pyrenecarboxylic acid pyreneformaldehyde (1.0934g, 4.75mM) and 20ml of acetone were added to a round bottom flask, 20ml of an aqueous solution containing potassium permanganate (2.5g, 15.82mM) was poured, stirred at 70 ℃ for 3.5 hours until the reaction was substantially complete, diluted with a large amount of deionized water and adjusted to pH 11-12 with sodium hydroxide. After filtration, adjusting the pH of the filtrate to 1-2 by using concentrated hydrochloric acid, separating out a large amount of yellow solids, carrying out vacuum filtration and drying the solids to obtain a crude product pyrenecarboxylic acid, and directly using the crude product pyrenecarboxylic acid in the next reaction;

2) the pyrenecarboxylic acid (0.616g,0.25mmol) was dissolved in 15mL of CH₂Cl₂In (5), N- (2-aminoethyl) morpholine (0.1295g, 0.995mmol) was poured in 2ml CH₂Cl₂EDC & HCl solid (0.2460g, mmol) was added to the solution, and the mixture was stirred at room temperature for 24 h. The method comprises the following steps of (1) using 5: 1 dichloromethane: the ethanol was passed through the column and dried in vacuo to give 0.0901g of a pale yellow solid product in 39% yield.

As shown in fig. 2, the mass spectrometric detection results for MPA: ESI-MS m/z is 359.18, as shown in FIG. 2, MPA (C)₃₀H₃₀N₅O₆S₂) The relative molecular mass of (2) is 358.44, which are substantially identical.

MPA was subjected to nuclear magnetic resonance test, as shown in FIG. 3, which¹H NMR Spectrum (400MHz, CDCl)₃) The medium chemical shifts and corresponding proton type assignments are:¹HNMR (600MHz, DMSO-d6, δ/ppm,)8.62(dd, J ═ 10.2,6.4Hz,2H),8.35(dt, J ═ 15.5,7.8Hz,3H), 8.30-8.19 (m,3H),8.12(dd, J ═ 15.4,7.7Hz,2H),3.67(t, J ═ 4.5Hz,4H), 3.60-3.43 (m,2H),2.61(t, J ═ 6.6Hz,2H), 2.56-2.48 (m,4H), as shown in fig. 2. (wherein s represents a singlet, d represents a doublet, dd represents a doublet, t represents a triplet, m represents a multiplet, and the number preceding "H" represents the number of hydrogen protons).

Example 2 method of pH value detection

(1) MPA identification of pH value of extreme acid solution

Adding MPA into extremely acidic aqueous solutions with different pH values to prepare solutions with pH values of 0.52, 1.04, 1.37, 1.54, 1.85, 2.45, 3.3 and 4.05 respectively, but MPA concentration of 2.0 × 10^-5In mol/L of the solution, the fluorescence intensity value at 413nm and the emission peak wavelength (excitation wavelength is 280nm) are respectively recorded and plotted, as shown in FIG. 4a, in the solution of MPA with the pH value increased from 0.52 to 4.05, the fluorescence intensity at 413nm is enhanced by 24 times, and the solution is changed from bright blue to purple along with the emission peak shift (as shown in FIG. 6) from 467nm to 413nm (54 nm).

(2) Identification of MPA on pH value of weak acid solution

Adding MPA into weakly acidic aqueous solution with different pH values to prepare solutions with pH values of 4.05, 4.71, 5.4, 6.02, 6.56, 7.03, 7.58, and 8.19 respectively, but MPA concentration of 2.0 × 10^-5The fluorescence intensity and emission peak wavelength at 413nm (excitation wavelength of 280nm) were recorded and plotted in mol/L solution, and MPA was shown in FIG. 4b in acidity from pH 8.19In the process of increasing to 4.05, the fluorescence intensity at 413nm is increased by 2.4 times, interestingly, the fluorescence emission peak is increased to 413nm of the visible region from 405nm close to the invisible region, the fluorescence color of the probe solution is changed from colorless to purple, the fluorescence background is small, and the color change is obvious.

According to the above test results, a standard curve of fluorescence emission intensity at 413nm at various pH values (see FIG. 5) and a standard curve of emission peak (see FIG. 6) were prepared. Preparing a to-be-measured aqueous solution with the pH value of 7.00, measuring under the above conditions to obtain that the fluorescence emission wavelength of the to-be-measured aqueous solution is 405nm, judging that the solution is weakly acidic, measuring to obtain that the fluorescence emission intensity of the to-be-measured aqueous solution at 413nm is 1065, calculating according to a standard curve shown in figure 4 to obtain that the pH value of the to-be-measured aqueous solution is 6.56, and having a small error, so that the method can be applied to the measurement of the pH value of the.

In conclusion, the MPA solution has high sensitivity for pH detection.

(3) Experiment of interference immunity

Preparing several aqueous solutions with pH values of 4.04 and 7.00 respectively, repeating the above pH fluorescence measurement experiment at 2.0 × 10^-5Adding 2.0 × 10 mol/L MPA solution^-5mol/L of Ba²⁺、Ni²⁺、Ag⁺、Mn²⁺、 Hg²⁺、K⁺、Zn²⁺、Cu²⁺、Fe³⁺、Fe²⁺、Al³⁺、NO₃ ^-、F^-After the common ions, the fluorescence intensity of the solution was measured under 280nm UV irradiation, and the fluorescence emission intensity at 413nm was recorded and plotted in a histogram as shown in FIG. 9.

As can be seen from FIG. 9, except for Fe³⁺In addition to a slight quenching at pH 4.04, other ions at pH 4.04 and 7.00 did not have any effect on the fluorescence emission properties of MPA, which were only related to the pH of the solution.

Example 3 preparation of MPA-based pH paper

Through experimental exploration and summary, the MPA has the outstanding advantages of multiple fluorescence color change, quick response (shown in figure 7), high sensitivity, wide corresponding range, strong anti-interference performance and the like, and has great potential in the aspect of manufacturing test paper for simple pH measurement, so that the pH test paper is prepared and a standard card is manufactured, as shown in figure 8.

Specifically, cut filter paper sheets are soaked in MPA methanol stock solution (5mM), taken out after being sufficiently wetted and dried, then respectively soaked in aqueous solutions with pH values of 0.53, 1.12, 2.23, 3.30, 4.71, 5.40, 6.27 and 7.28, taken out and photographed under the irradiation of an ultraviolet lamp at 365nm to record fluorescence colors, and then finished into standard cards.

As can be seen from FIG. 8, when the MPA-based pH test paper is immersed in solutions of different acidity, a significant fluorescence color change occurs, and the MPA-based pH test paper can be well applied to rapid detection of the pH value of an aqueous solution. Compared with the traditional multi-probe ultraviolet colorimetric pH test paper, the pH test paper has more obvious response in extreme acidity, and is beneficial to application in different scenes.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the protection scope of the present invention, although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

N- (2' -morpholinoethyl) -N- (pyreneformyl) amine having the formula (I)
2. The method for preparing N- (2' -morpholinoethyl) -N- (pyreneformyl) amine according to claim 1, wherein pyrenecarboxylic acid and N- (2-aminoethyl) morpholine are dissolved in CH₂Cl₂In a solvent; and adding EDC & HCl, stirring at room temperature for 20-30 h, and purifying after stirring is finished to obtain the catalyst.
3. N- (2' -morpholine) according to claim 2The preparation method of the ethyl) -N- (pyrene formyl) amine is characterized in that the purification treatment comprises the following steps: after the stirring was completed, CH was removed by distillation under reduced pressure₂Cl₂The solvent is passed through a column with a dichloromethane/ethanol mixed developing agent and then evaporated to dryness by a reduced pressure distillation method.
4. The use of N- (2' -morpholinoethyl) -N- (pyrene formyl) amine of claim 1 in a pH detection probe.
5. The use of N- (2' -morpholinoethyl) -N- (pyrene formyl) amine in pH detection according to claim 4, comprising the steps of:

s01, drawing a standard curve

Preparing a pH standard solution, adding the standard solutions with different pH values into an N- (2' -morpholinoethyl) -N- (pyrene formyl) amine solution, and recording the fluorescence intensity and the emission peak wavelength of the solution; drawing a standard curve by taking the fluorescence intensity and the pH at the same wavelength as coordinate axes;

s02, adding a solution to be detected into an N- (2' -morpholinoethyl) -N- (pyrene formyl) amine solution, and recording the solution intensity and the emission peak wavelength;

and S03, calculating according to the fluorescence emission peak wavelength and the corresponding standard curve to obtain the pH value of the liquid to be detected.
6. Use of N- (2' -morpholinoethyl) -N- (pyrene formyl) amine according to claim 4 in pH, comprising the steps of:

s11, preparing pH detection test paper

Uniformly coating a specific N- (2' -morpholinoethyl) -N- (pyrene formyl) amine solution on a filter paper;

s12, manufacturing a standard colorimetric card

Dripping a solution with known pH on filter paper soaked with the N- (2' -morpholinoethyl) -N- (pyrene formyl) amine solution, and shooting and recording the color of the test paper;

s13, dropwise adding the solution to be detected on the detection test paper prepared in the step S11, and comparing the solution to be detected with the standard colorimetric card prepared in the step S12 to obtain the pH value of the solution to be detected.
7. A pH test paper containing the N- (2' -morpholinoethyl) -N- (pyreneformyl) amine of claim 1.