A cadmium-based metal-organic framework material, a preparation method and application thereof

Abstract

The application discloses a cadmium-based metal-organic framework material and a preparation method and application thereof. 60 H 34 Cd2N 12 O8S, and the preparation method comprises the following steps: uniformly mixing cadmium nitrate tetrahydrate, 2,6-bis(benzimidazole-1-yl)pyridine, 5,5 ' -benzothiadiazole-4,7-diisophthalic acid, N,N'-dimethylformamide, methanol, ultrapure water and nitric acid according to a predetermined proportion; the mixture is warmed to 115-125 DEG C and reacted for 70-75 hours to obtain yellow flaky crystals; the collected crystals are washed with ethanol and dried in air. The cadmium-based metal-organic framework material can be applied to the preparation of a fluorescent probe or a fluorescent sensor for detecting anthrax biomarker DPA, realizes selective recognition of anthrax biomarker DPA through fluorescence blue shift, and the detection limit is 1.5 mu M.

Description

Technical Field

[0001] This invention relates to the field of functional complex fluorescent materials; more specifically, it relates to a cadmium-based metal-organic framework material capable of selectively fluorescently recognizing the anthrax biomarker DPA, its preparation method, and its application. Background Technology

[0002] Bacillus anthracis is a Gram-positive, rod-shaped, spore-forming bacterium whose spores are highly toxic and lethal. DPA (2,6-pyridinedicarboxylic acid) is commonly designated as a major biomarker for Bacillus anthracis; therefore, developing sensitive, efficient, and rapid DPA detection technologies is crucial for eliminating the potential threat of anthrax and maintaining public health and food safety. DPA detection methods have been developed over several decades, with common methods including polymerase chain reaction (PCR), fluorescence, electrochemical analysis, surface-enhanced Raman spectroscopy (SERS), high-performance liquid chromatography (HPLC), mass spectrometry (MS), and surface plasmon resonance (SPR). However, sample preparation and time / cost constraints limit their application.

[0003] Metal-organic frameworks (MOFs) are a class of organic-inorganic hybrid materials that have attracted widespread attention from materials and chemistry researchers due to their unique structure and applications in environmental protection and human health. Compared with other detection techniques, MOF fluorescence detection has advantages such as good selectivity, high sensitivity, short response time, low cost, and ease of operation. Therefore, developing MOF fluorescence sensing materials for detecting dihydropyridine (DPA) is particularly important.

[0004] Fluorescence sensing exhibits various forms, such as ratiometric fluorescence sensing, fluorescence quenching, fluorescence enhancement, and emission color change. Among these, ratiometric fluorescence sensing is generally dual-emission and has self-calibration capabilities, and has been reported extensively in recent years, typically using rare-earth MOFs. Single-emission fluorescence enhancement offers advantages over fluorescence quenching in terms of high sensitivity and ease of identification. Emission color change can be visually identified with the naked eye, especially for sensors exhibiting significant color shifts, which usually involve fluorescence shifts (red or blue shifts).

[0005] In recent years, numerous fluorescent sensing materials for DPA based on rare-earth MOFs have been reported, but MOF sensing materials based on fluorescence shift are relatively few. Currently, only two examples of fluorescence blue-shift MOF sensing materials for DPA detection have been reported, one of which is described in the literature by L. Wang, YL Zhu, TF Zheng, ZH Zhu, Y. Peng, YQ Wu, JL Chen, SJ Liu, HR Wen. Dalton Trans., 2023, 52Eu-MOF reported in (30), 10567-10573, and another example is Zn-MOF reported in J. Huang, JJ Wang, C. Cao, L. Cao, TF Zheng, HR Wen, SJLiu, Inorg. Chem., 2025, 64 (3), 1551-1560, while no cadmium-based fluorescent blue-shifted MOFs have been reported. Summary of the Invention

[0006] The present invention aims to further develop the existing technology and provide a novel cadmium-based metal-organic framework material with high sensitivity and selective recognition of DPA, as well as its preparation method and application.

[0007] The first aspect of the present invention provides a cadmium-based metal-organic framework material having the chemical formula C 60 H 34 Cd2N 12 O8S, crystal system is triclinic, space group is The unit cell parameters are: a=10.4657(3) Å, b=11.4898(4) Å, c=15.4090(5) Å, α=101.342(3)°, β=98.829(3)°, γ=111.959(3)°.

[0008] Furthermore, the cadmium-based metal-organic framework material can selectively identify the anthrax biomarker DPA through a fluorescent blue shift.

[0009] A second aspect of the present invention provides a method for preparing the cadmium-based metal-organic framework material, comprising the following steps:

[0010] Step 1: Mix cadmium nitrate tetrahydrate, 2,6-bis(benzimidazol-1-yl)pyridine, 5,5'-benzothiadiazole-4,7-diisophthalic acid, N,N'-dimethylformamide, methanol, ultrapure water and nitric acid in a predetermined ratio until homogeneous.

[0011] Step 2: Heat the mixture obtained in Step 1 to 115-125℃ and react for 70-75 hours, then cool it down to 25-35℃ to obtain yellow flaky crystals;

[0012] Step 3: Collect the above-mentioned plate-like crystals, wash them with ethanol, and dry them in air to obtain the cadmium-based metal-organic framework material.

[0013] According to a specific embodiment of the present invention, in step one, the amounts of cadmium nitrate tetrahydrate, 2,6-bis(benzimidazol-1-yl)pyridine, 5,5'-benzothiadiazole-4,7-diisophthalic acid, N,N'-dimethylformamide, methanol, ultrapure water, and nitric acid are in the following order: 0.04-0.06 mmol : 0.04-0.06 mmol : 0.02-0.03 mmol : 3-5 mL : 0.5-1.5 mL : 0.5-1.5 mL : 90-110 μL.

[0014] Furthermore, in step one, the ratio of cadmium nitrate tetrahydrate, 2,6-bis(benzimidazol-1-yl)pyridine, 5,5'-benzothiadiazole-4,7-diisophthalic acid, N,N'-dimethylformamide, methanol, ultrapure water, and nitric acid is 0.05 mmol: 0.05 mmol: 0.025 mmol: 4 mL: 1 mL: 1 mL: 100 μL.

[0015] According to a specific embodiment of the present invention, in step two, the mixture is heated to 120°C, reacted for 72 hours, and then cooled to 30°C within 24 hours to obtain yellow flaky crystals.

[0016] A third aspect of the present invention discloses the application of the cadmium-based metal-organic framework material in the fabrication of fluorescent probes or fluorescent sensors for detecting the anthrax biomarker DPA.

[0017] The present invention has the following beneficial effects:

[0018] The cadmium-based metal-organic framework material provided by this invention can selectively recognize DPA via fluorescence blue shift and exhibits high sensitivity and anti-interference ability, with a detection limit of 1.5 μM, far below the human infectious dose (60 μM). It can be used to fabricate fluorescent probes or fluorescent sensors for detecting the anthrax biomarker DPA. The preparation method provided by this invention is based on Cd... 2+ The strong coordination ability of ions and the synergistic coordination of specific acid-base organic ligands point to a new direction for the preparation of cadmium-based metal-organic frameworks with selective fluorescent recognition of DPA. Attached Figure Description

[0019] Figure 1 Crystal structure diagram of cadmium-based metal-organic framework material provided in the embodiments of the present invention;

[0020] Figure 2 Fluorescence emission patterns of cadmium-based metal-organic framework materials provided in embodiments of the present invention, tested under conditions containing DPA and different interfering substances;

[0021] Figure 3 The fluorescence titration spectra of cadmium-based metal-organic framework materials with different concentrations of DPA provided in the embodiments of the present invention;

[0022] Figure 4 The graph shows the linear relationship between the fluorescence intensity ratio I / I0 and the DPA concentration of the cadmium-based metal-organic framework material provided in the embodiments of the present invention. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] This invention provides a cadmium-based metal-organic framework material with the chemical formula C. 60 H 34 Cd2N 12 O8S belongs to the triclinic crystal system. The space group and cell parameters are: a=10.4657(3) Å, b=11.4898(4) Å, c=15.4090(5) Å, α=101.342(3)°, β=98.829(3)°, γ=111.959(3)°. This cadmium-based metal-organic framework material can selectively identify the anthrax biomarker DPA by fluorescence blue shift, with a detection limit far below the human infection dose (60 μM).

[0025] The present invention also provides a method for preparing the above-mentioned cadmium-based metal-organic framework material, comprising the following steps:

[0026] Step 1: Add cadmium nitrate tetrahydrate, 2,6-bis(benzimidazol-1-yl)pyridine, 5,5'-benzothiadiazole-4,7-diisophthalic acid, N,N'-dimethylformamide, methanol, ultrapure water and nitric acid to a high-pressure reactor and sonicate to mix them evenly.

[0027] Step 2: Heat the above mixture to 115-125℃ and react for 70-75 hours, then cool it down to 25-35℃ to obtain yellow flaky crystals.

[0028] Step 3: Collect the above-mentioned plate-like crystals, wash them with ethanol, and dry them in air to obtain a cadmium-based metal-organic framework material that can selectively recognize DPA by fluorescence blue shift.

[0029] In some embodiments of the present invention, the amounts of cadmium nitrate tetrahydrate, 2,6-bis(benzimidazol-1-yl)pyridine, 5,5'-benzothiadiazole-4,7-diisophthalic acid, N,N'-dimethylformamide, methanol, ultrapure water, and nitric acid can be in the following ratios: 0.04-0.06 mmol: 0.04-0.06 mmol: 0.02-0.03 mmol: 3-5 mL: 0.5-1.5 mL: 0.5-1.5 mL: 90-110 μL.

[0030] Preferably, the ratio of cadmium nitrate tetrahydrate, 2,6-bis(benzimidazol-1-yl)pyridine, 5,5'-benzothiadiazole-4,7-diisophthalic acid, N,N'-dimethylformamide, methanol, ultrapure water, and nitric acid is 0.05 mmol: 0.05 mmol: 0.025 mmol: 4 mL: 1 mL: 1 mL: 100 μL.

[0031] In some embodiments of the present invention, the reaction temperature of the mixture in step two may be, but is not limited to, 115°C, 120°C or 125°C, and the reaction time may be, but is not limited to, 70 hours, 72 hours or 75 hours.

[0032] The technical solution of the present invention will be further described below through embodiments and comparative examples.

[0033] Example

[0034] Step 1: Add cadmium nitrate tetrahydrate, 2,6-bis(benzimidazol-1-yl)pyridine, 5,5'-benzothiadiazole-4,7-diisophthalic acid, N,N'-dimethylformamide, methanol, ultrapure water, and nitric acid to a 25 mL high-pressure reactor and sonicate for 15 min to ensure homogeneity. The amounts of cadmium nitrate tetrahydrate, 2,6-bis(benzimidazol-1-yl)pyridine, 5,5'-benzothiadiazole-4,7-diisophthalic acid, N,N'-dimethylformamide, methanol, ultrapure water, and nitric acid used are 0.05 mmol, 0.05 mmol, 0.025 mmol, 4 mL, 1 mL, 1 mL, and 100 μL, respectively.

[0035] Step 2: Heat the above mixture to 120°C and react for 72 hours. Then, cool it down to 30°C within 24 hours to obtain yellow flaky crystals.

[0036] Step 3: Collect the above-mentioned plate-like crystals, wash them with ethanol, and dry them in air to obtain a cadmium-based metal-organic framework material that can selectively recognize DPA by fluorescence blue shift.

[0037] Comparative Example

[0038] The difference between the comparative example and the embodiments is that the 2,6-bis(benzimidazol-1-yl)pyridine ligand used in the comparative example was replaced with a structurally similar 1,3-bis(benzimidazolyl)benzene ligand, and the same method was used for preparation, but no crystals were obtained. It is evident that the choice of ligand is a key factor in the preparation of the cadmium-based metal-organic framework material of this invention. The preparation method provided by this invention is based on specific acid-base organic ligands (2,6-bis(benzimidazol-1-yl)pyridine and 5,5'-benzothiadiazole-4,7-diisophthalic acid) and Cd. 2+ The coordinated coordination of ions points to a new direction for the preparation of cadmium-based metal-organic frameworks with selective fluorescent recognition of DPA.

[0039] Example: Characterization and testing of cadmium-based metal-organic framework materials:

[0040] Select a size of (0.30 × 0.26 × 0.25) mm. 3 The crystal was used for single-crystal structure analysis. Single-crystal diffraction data were collected on a diffractometer and monochromated using a graphite monochromator. α X-rays (λ = 0.71073 Å) confirmed that the cadmium-based metal-organic framework material belongs to the triclinic crystal system with space group . Its unit cell parameters are: a=10.4657(3) Å, b=11.4898(4) Å, c=15.4090(5) Å, α=101.342(3)°, β=98.829(3)°, γ=111.959(3)°. Figure 1 This is the crystal structure diagram of the cadmium-based metal-organic framework material (all H atoms are omitted for clarity), and its chemical formula is C. 60 H 34 Cd2N 12 O8S, the structure is {[Cd(bbip)(btdi)} 0.5 ]·solvents} n , where bbip = 2,6-bis(benzimidazol-1-yl)pyridine, H4btdi = 5,5'-benzothiadiazole-4,7-diisophthalic acid, and solvents represent free solvent molecules.

[0041] Fluorescence data of the cadmium-based metal-organic framework (Cd-MOF) obtained in the examples were measured using a Hitachi F-4600 fluorescence spectrometer. Figure 2 The image shows the fluorescence emission of this Cd-MOF under DPA and various interfering substances, plotted using Origin software. The image reveals a significant blue shift in fluorescence for DPA, which is visually identifiable (green to blue). Furthermore, this Cd-MOF exhibits very high interference resistance, showing excellent fluorescence emission under Na+ conditions. +K + Ca 2+ Mg 2+ Cl - HCO3 - HPO4 2- It showed good selectivity in valine, arginine, glutamic acid, alanine, glucose, urea, and uric acid. Figure 3 The fluorescence spectra of Cd-MOF titrated with different concentrations of DPA were plotted using Origin software. It can be seen that with increasing DPA concentration, the fluorescence intensity and blue shift of Cd-MOF increase accordingly. Figure 4 As shown, the method based on the linear relationship between fluorescence intensity ratio I / I0 and concentration is obtained through formula 3σ / k ( k The detection limit for DPA fluorescence recognition is 1.5 μM, calculated from the linear slope (σ: standard error).

[0042] In summary, the cadmium-based metal-organic framework material provided by this invention can selectively recognize the anthrax biomarker DPA with high sensitivity through fluorescence blue shift, and can be applied to the fabrication of fluorescent probes or fluorescent sensors for detecting the anthrax biomarker DPA; furthermore, the preparation method provided by this invention is based on Cd 2+ The strong coordination ability of ions and the synergistic coordination of specific acid-base organic ligands point to a new direction for the preparation of cadmium-based metal-organic frameworks with selective fluorescent recognition of DPA.

[0043] The embodiments described above only illustrate some implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A cadmium-based metal-organic framework material, characterized in that: The chemical formula of the cadmium-based metal-organic framework material is C. 60 H 34 Cd2N 12 O8S, crystal system is triclinic, space group is The unit cell parameters are: a = 10.4657(3) Å, b = 11.4898(4) Å, c = 15.4090(5) Å, α = 101.342(3)°, β = 98.829(3)°, γ = 111.959(3)°; The cadmium-based metal-organic framework material can selectively identify the anthrax biomarker DPA by fluorescent blue shift. The preparation method of the cadmium-based metal-organic framework material includes the following steps: Step 1: Mix cadmium nitrate tetrahydrate, 2,6-bis(benzimidazol-1-yl)pyridine, 5,5'-benzothiadiazole-4,7-diisophthalic acid, N,N'-dimethylformamide, methanol, ultrapure water and nitric acid in a predetermined ratio until homogeneous. Step 2: Heat the mixture obtained in Step 1 to 115-125℃ and react for 70-75 hours, then cool it down to 25-35℃ to obtain yellow flaky crystals; Step 3: Collect the above-mentioned plate-like crystals, wash them with ethanol, and dry them in air to obtain the cadmium-based metal-organic framework material.

2. The cadmium-based metal-organic framework material according to claim 1, characterized in that: In step one, the volume ratios of cadmium nitrate tetrahydrate, 2,6-bis(benzimidazol-1-yl)pyridine, 5,5'-benzothiadiazole-4,7-diisophthalic acid, N,N'-dimethylformamide, methanol, ultrapure water, and nitric acid are as follows: 0.04-0.06 mmol: 0.04-0.06 mmol: 0.02-0.03 mmol: 3-5 mL: 0.5-1.5 mL: 0.5-1.5 mL: 90-110 μL.

3. The cadmium-based metal-organic framework material according to claim 1, characterized in that: In step one, the ratio of cadmium nitrate tetrahydrate, 2,6-bis(benzimidazol-1-yl)pyridine, 5,5'-benzothiadiazole-4,7-diisophthalic acid, N,N'-dimethylformamide, methanol, ultrapure water, and nitric acid is 0.05 mmol: 0.05 mmol: 0.025 mmol: 4 mL: 1 mL: 1 mL: 100 μL.

4. The cadmium-based metal-organic framework material according to claim 1, characterized in that: In step two, the mixture is heated to 120°C and reacted for 72 hours, then cooled to 30°C within 24 hours.

5. The application of the cadmium-based metal-organic framework material according to claim 1, characterized in that: The cadmium-based metal-organic framework material is used to fabricate fluorescent probes or fluorescent sensors for detecting the anthrax biomarker DPA.

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