Preparation method of fluorescence sensitive MOF molecular probe capable of rapidly recognizing magnesium ions

Abstract

The invention discloses a preparation method of a fluorescent sensitive MOF molecular probe for rapidly recognizing magnesium ions. The preparation method comprises the following steps: firstly, synthesizing an organic template H3L for skeleton support; mixing calcium salt, an organic template H3L and deionized water, carrying out ultrasonic treatment on the obtained mixed aqueous solution for a period of time, transferring the mixed aqueous solution into a reaction kettle with a polytetrafluoroethylene lining, sealing, and carrying out heating reaction in a drying oven for a certain period of time; and after the reaction is finished, cooling to room temperature to obtain a cubic colorless transparent crystal, namely the calcium carboxylate {(H3O). [Ca (HL)] 2. Cl. 2H2O} n MOF molecular fluorescent probe (CCDC number: 1953728). The preparation method has the beneficial effects of simplicity, short time consumption, atom economy, energy conservation and environment friendliness; the prepared product can realize high-sensitivity rapid identification and detection on magnesium ions (Mg < 2 + >) existing in a solution through a fluorescence enhancement effect.

Description

Technical Field

[0001] The present invention belongs to the field of molecular sensors. Specifically, it relates to a preparation method of a fluorescent sensitive MOF molecular probe for rapid identification of magnesium ions. Background Art

[0002] Water quality detection is an essential basic task in daily life and environmental protection. In terms of drinking water, an appropriate amount of magnesium ions is an essential mineral for the human body, but excessive intake may cause health problems such as diarrhea; in the industrial field (such as boilers, cooling systems), high-concentration magnesium ions are prone to form scale (such as forming MgCO with carbonate radicals), reducing thermal efficiency and corroding equipment; in environmental monitoring, changes in magnesium ion concentration can reflect water pollution or geological activities. Therefore, it is necessary to detect magnesium ions in water quality.

[0003] Traditional methods for magnesium ion detection mainly include: chemical analysis methods (EDTA complexometric titration method, spectrophotometry) and instrumental analysis methods (atomic absorption spectrometry, inductively coupled plasma mass spectrometry, ion selective electrode), etc. These methods are highly dependent on laboratories, have weak anti-interference ability, high cost, complex operation, high instrument maintenance cost, are not suitable for on-line monitoring, and the detection accuracy and reproducibility are not very ideal, making it difficult to meet the on-site rapid, low-cost, and highly selective detection requirements.

[0004] In view of the above problems, the present invention proposes to design and synthesize a MOF molecular fluorescence probe that is low-cost, highly efficient and specific, rapid, and sensitive for detecting magnesium ions. Metal-organic framework (MOF) materials have received extensive attention from scholars in recent years. As functional materials, MOFs have the advantages of high specific surface area and adjustable pore structure, structural designability and functionalization, high sensitivity and low detection limit, good stability and reproducibility, biocompatibility and low toxicity, and environmental adaptability, making them show great potential in the fields of sensing, bioimaging, and environmental monitoring. Preparing a molecular fluorescence probe with metal-organic framework (MOF) is an ideal molecular sensor material because of its environmental friendliness and excellent fluorescence sensitive performance. Summary of the Invention

[0005] In view of this, aiming at the limitations of traditional detection methods, the present invention provides a preparation method of a fluorescent sensitive MOF molecular probe for rapid identification of magnesium ions. The present invention first prepares an organic template H3L, and then uses a calcium salt and the organic template H3L as reaction sources to obtain a calcium carboxylate MOF molecular fluorescence probe through a hydrothermal reaction. This preparation method has the advantages of simple preparation process, short time consumption, atomic economy, energy conservation and environmental protection; the calcium carboxylate MOF molecular material prepared by the present invention can be used in the field of water quality detection for rapid identification of target metal ions. To achieve the above object, the present application discloses a preparation method of a fluorescent sensitive MOF molecular probe for rapid identification of magnesium ions, including the following steps:

[0006] (1) Synthesis of the organic template H3L: 1-[(2′-carboxybiphenyl-4-yl)methyl]-2-propylimidazole-4,5-dicarboxylic acid;

[0007] (2) A mixture containing 1.49 g (8.0 mmol) of Ca(CH3COO)2·H2O, 0.82 g (2.0 mmol) of H3L, and 30 mL of deionized water was ultrasonically treated at 20°C - 60°C for 0.5 - 1.5 h and then sealed in a 50 mL reaction kettle lined with polytetrafluoroethylene and heated at 120°C - 160°C for 114 - 126 h;

[0008] (3) After the reaction, it was cooled to room temperature to obtain cubic block-shaped colorless transparent crystals, which were calcium carboxylate {(H3O)·[Ca(HL)]2·Cl·2H2O} n MOF molecular fluorescence probe (CCDC No.: 1953728).

[0009] Preferably, in step (2), the mixture was ultrasonically treated at 30°C - 50°C for 0.8 - 1.5 h.

[0010] Preferably, the mixture was ultrasonically treated at 40°C for 1 h.

[0011] Preferably, the ultrasonic frequency was 200 - 1000 KHz.

[0012] Preferably, in step (2), it was heated in the reaction kettle at 130°C - 150°C for 116 - 123 h.

[0013] Preferably, it was heated at 140°C for 120 h.

[0014] The present invention also discloses a cubic block-shaped colorless transparent crystal calcium carboxylate {(H3O)·[Ca(HL)]2·Cl·2H2O} prepared by the above preparation method n MOF molecular fluorescence probe (CCDC No.: 1953728).

[0015] Compared with the prior art, the present invention can achieve the following technical effects:

[0016] (1) The present invention utilizes hydrothermal synthesis technology to self-assemble and construct a two-dimensional layered calcium carboxylate metal-organic framework (MOF) molecule {(H3O)·[Ca(HL)]2·Cl·2H2O} n fluorescence probe.

[0017] (2) The calcium carboxylate metal-organic framework (MOF) molecule {(H3O)·[Ca(HL)]2·Cl·2H2O} prepared by the present invention n The fluorescent probe can be used for highly sensitive and rapid identification of magnesium ions Mg in water 2+ .

[0018] (3) The calcium carboxylate metal-organic framework (MOF) molecule {(H3O)·[Ca(HL)]2·Cl·2H2O} prepared by the present invention n The lowest linear concentration value for the fluorescent probe to identify magnesium ions in water is 2.5×10 -5 mol·L -1 .

[0019] Of course, it is not necessary for any product implementing the present invention to achieve all the above-mentioned technical effects simultaneously. The MOF molecule fluorescent probe analysis method is an analysis method established by using the different fluorescence responses of MOF molecules before and after the addition of a certain metal ion. Compared with conventional detection techniques, the new MOF molecule fluorescent probe is superior to conventional detection techniques in terms of both preparation cost and use efficiency (short time, high selectivity, good sensitivity and reproducibility, and easy to operate).

[0020] Compared with the prior art, the beneficial effects of the present invention are: simple preparation process, short time consumption, atom economy, energy conservation and environmental protection; the prepared product can achieve highly sensitive and rapid identification and detection of magnesium ions (Mg 2+ ) in the solution through the fluorescence enhancement effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the molecular structural formula of a fluorescent-sensitive MOF molecule probe for rapid identification of magnesium ions according to the present invention;

[0022] Figure 2 is the fluorescence emission spectra of the blank solution and competitive metal ions of a fluorescent-sensitive MOF molecule probe for rapid identification of magnesium ions according to the present invention under the excitation wavelength of 315 nm;

[0023] Figure 3 is the corresponding graph of magnesium ion concentration-fluorescence intensity in the detection of a fluorescent-sensitive MOF molecule probe for rapid identification of magnesium ions according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0025] Example 1:

[0026] A preparation method of a fluorescence-sensitive MOF molecular probe for rapid identification of magnesium ions, comprising the following steps:

[0027] (1) Synthesize the organic template H3L: 1-[(2′-carboxybiphenyl-4-yl)methyl]-2-propylimidazole-4,5-dicarboxylic acid;

[0028] (2) A mixture containing 1.49 g (8.0 mmol) of Ca(CH3COO)2·H2O, 0.82 g (2.0 mmol) of H3L and 30 mL of deionized water was sonicated at 40 °C for 1 h and then sealed in a 50 mL reaction kettle lined with polytetrafluoroethylene, and heated at 140 °C for 120 h;

[0029] (3) After the reaction, it was cooled to room temperature to obtain cubic block-shaped colorless transparent crystals, which were calcium carboxylate {(H3O)·[Ca(HL)]2·Cl·2H2O} n MOF molecular fluorescence probe (CCDC No.: 1953728).

[0030] Calcium carboxylate {(H3O)·[Ca(HL)]2·Cl·2H2O} n The molecular structural formula of the MOF molecular fluorescence probe is as Figure 1 shown, and the infrared data (IR, cm -1 ): 3369(m), 3023(w), 2964(w), 2930(w), 2872(w), 1543(s), 1440(s), 1398(s), 1270(m), 1180(w), 1094(w), 1070(w), 1005(w), 970(w), 904(w), 755(w), 709(w), 615(w), 537(w), 445(w).

[0031] Example 2

[0032] Calcium carboxylate {(H3O)·[Ca(HL)]2·Cl·2H2O} n Selectivity of the MOF molecular fluorescence probe for different metal ions in solution: Take an appropriate amount of the molecular fluorescence probe and dissolve it in blank deionized water. After sonication for 1.0 h, a 1×10 -3 mol·L -1 molecular fluorescence probe stock solution was obtained. Take 1 mL of the molecular fluorescence probe stock solution into a 5 mL volumetric flask, add competitive metal ions respectively, and make up to 5 mL to obtain a mixed solution (the solution concentration is 1×10-4 mol·L -1 )。Competitive ion M x+ are respectively: Ba 2+ , Ca 2+ , Mg 2+ , K + , Na + , Zn 2+ , Cd 2+ , Co 2+ , Ni 2+ , Mn 2+ , Cu 2+ (1×10 -2 mol·L -1 chloride salt solution). Dissolve the prepared molecular fluorescent probe in the blank stock solution to prepare a fluorescent reagent with a concentration of 1×10 -4 mol·L -1 as the control solution. Fluorescent excitation is performed on both the control solution and 11 mixed solutions under the condition of a wavelength of 315 nm, and the test results are as Figure 2 shown. As Figure 2 can be seen, compared with other metal ions, Mg 2+ causes the largest increase in the fluorescence intensity of this MOF molecular fluorescent probe at 390 nm, showing a significant fluorescence enhancement effect, indicating that this fluorescent probe has good selectivity for magnesium ion Mg 2+ and can be used to rapidly identify magnesium ion Mg 2+ .

[0033] Example 3

[0034] Effect of magnesium ion concentration on fluorescence intensity when the MOF molecular fluorescent probe is used to identify magnesium ions: Prepare an analyte concentration c(Mg 2+ ) = 1.0×10 -3 mol·L -1 . Respectively take 30 μL, 50 μL, 100 μL, 200 μL, 500 μL, 1100 μL, 1500 μL, 2600 μL, 3000 μL and add them to the substrate (MOF molecular fluorescent probe), and the substrate concentration is kept at 1.0×10 -4 mol·L -1 . Dissolve the prepared molecular fluorescent probe in the blank stock solution to prepare a fluorescent reagent with a concentration of 1×10 -4 mol·L -1A fluorescent reagent was used as a control solution. The control solution and each mixed solution were subjected to fluorescence excitation at a wavelength of 315 nm. When the addition amount of magnesium ions increased from 30 μL to 100 μL, the fluorescence intensity emitted at 390 nm remained basically unchanged and reached the maximum value. As the concentration of magnesium ions continued to increase, the fluorescence intensity of the MOF molecular fluorescent probe gradually decreased until the fluorescence intensity emitted when the addition amount of magnesium ions was 2600 μL was the same as that without adding magnesium ions. At this time, the detection limit for the MOF molecular fluorescent probe to recognize magnesium ions was 0.28 μM. The fluorescence intensities of the above 11 mixed solutions were measured at 390 nm respectively. Taking the magnesium ion concentration in the mixed solution as the abscissa and the fluorescence intensity of the MOF molecular fluorescent probe at 390 nm as the ordinate, a linear regression equation was established, and it was obtained that the magnesium ion concentration in the mixed solution was in the range of 2.5×10 -5 mol·L -1 ~1.5×10 -3 mol·L -1 Within this range, the fluorescence intensity was linearly correlated with the magnesium ion concentration, and the linear relationship equation was y = 781.498 - 285029.60128x, and the linear correlation coefficient R 2 = 0.99863. Therefore, the lowest linear concentration value for the quantitative analysis of magnesium ions was 2.5×10 -5 mol·L -1 .

[0035] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a fluorescence-sensitive MOF molecular probe for rapid recognition of magnesium ions, characterized in that, It includes the following steps: (1) Synthesize the organic template H3L for skeleton support: 1-[(2′-carboxybiphenyl-4-yl)methyl]-2-propylimidazole-4,5-dicarboxylic acid; (2) Seal a mixture containing 1.49 g (8.0 mmol) of Ca(CH3COO)2·H2O, 0.82 g (2.0 mmol) of H3L, and 30 mL of deionized water in a 50 mL reaction kettle lined with polytetrafluoroethylene after ultrasonic treatment at 20°C - 60°C for 0.5 - 1.5 h, and heat it at 120°C - 160°C for 114 - 126 h; (3) After the reaction is completed, the temperature is lowered to room temperature to obtain cubic colorless transparent crystals, namely calcium carboxylate {(H3O)·[Ca(HL)]2·Cl·2H2O} n MOF molecular fluorescent probe (CCDC No.: 1953728).

2. The preparation method of a fluorescent sensitive MOF molecular probe for rapid identification of magnesium ions according to claim 1, characterized in that In step (2), the mixture is ultrasonically treated at 30°C - 50°C for 0.8 - 1.5 h.

3. The preparation method of a fluorescent sensitive MOF molecular probe for rapid identification of magnesium ions according to claim 2, characterized in that, The mixture is ultrasonically treated at 40°C for 1 h.

4. The preparation method of a fluorescence-sensitive MOF molecular probe for rapid magnesium ion recognition according to claim 2, wherein The ultrasonic frequency is 200 - 1000 KHz.

5. The preparation method of a fluorescence-sensitive MOF molecular probe for rapid identification of magnesium ions according to claim 1, wherein In step (2), heat it in the reaction kettle at 130°C - 150°C for 116 - 123 h.

6. The preparation method of a fluorescence-sensitive MOF molecular probe for rapid magnesium ion recognition according to claim 5, characterized in that, Heat it at 140°C for 120 h.

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