One-dimensional ring chain manganese coordination polymer as well as preparation method and application thereof

Abstract

The invention discloses a one-dimensional ring chain manganese coordination polymer as well as a preparation method and application thereof, and belongs to the technical field of complex synthesis and fluorescence detection. The preparation method comprises the following steps: reacting a bivalent manganese salt and 2-{2-[5-(4-pyridyl)-1H-1, 2, 4-triazole-3-yl] phenoxy} benzoic acid in a solvent, so as to prepare the one-dimensional ring chain type manganese coordination polymer. A solvothermal method is adopted for synthesis, the synthesis process is simple, the efficiency is high, the conditions are mild, and the obtained coordination polymer has good crystal stability and thermal stability, shows high-specificity and sensitive detection performance on furacilin and tetracycline, has application potential as an NFZ and TC specific fluorescent probe, and has wide application prospects. The problem that a rapid, convenient and economical nitrofurazone and tetracycline detection method is lacked in the prior art is solved, and experimental data and theoretical support are provided for designing and developing efficient fluorescent sensing materials for antibiotic pollutants.

Description

Technical Field

[0001] This invention relates to the field of coordination compound synthesis and fluorescence detection technology, specifically to a one-dimensional cyclic chain manganese coordination polymer and its preparation method and application. Background Technology

[0002] With industrial development and population growth, human life faces multiple challenges. Excessive emissions of pollutants rapidly spread into the air, soil, and water, becoming a major global problem threatening environmental and biological health. Among these, heavy metal pollution, due to its high carcinogenicity, has attracted significant attention and has a substantial impact on global health. Traditional detection methods include inductively coupled plasma mass spectrometry (ICP-MS), high-performance liquid chromatography (HPLC), chemiluminescence immunoassay, atomic absorption spectrometry (AAS), and electrochemical analysis. However, these methods suffer from drawbacks such as high cost, complex and time-consuming pretreatment steps, and the need for regular precision calibration and maintenance of the instruments.

[0003] Coordination polymers (CPs) are crystalline materials formed through coordination interactions between organic ligands and metal ions or metal clusters, exhibiting ordered arrangement and controllable molecular structures. Due to their unique structures and diverse topologies, these materials have attracted considerable attention. Their structural types are determined by a variety of factors, including the properties of the metal ions, organic ligands, counter ions, coordination solvents or co-crystallization solvents, as well as the ratio of metal to ligands and temperature. As the main components constructing coordination polymers, metal ions and organic ligands are interconnected through coordination covalent bonds, forming one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) network structures. Regulating these factors is crucial for adjusting the structure and endowing coordination polymers with application value in fields such as gas storage, molecular recognition, catalysis, magnetism, and fluorescence sensing. In recent years, research on the fluorescence properties of coordination polymers has been increasing, showing great potential in the detection of organic / inorganic pollutants in aqueous solutions.

[0004] Furazolidone, tetracycline, and related antibiotics are not only significant environmental pollutants but also pose a threat to human health. Currently, the detection methods for furazolidone and tetracycline generally still rely on traditional instrumental methods. Therefore, developing rapid, convenient, and economical detection methods based on coordination polymer technologies remains a pressing challenge. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a one-dimensional cyclic manganese coordination polymer, its preparation method, and its application, thereby solving the problem of the lack of rapid, convenient, and economical detection methods for furazolidone and tetracycline.

[0006] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: In a first aspect, the present invention provides a method for preparing a one-dimensional cyclic manganese coordination polymer, comprising the following steps: One-dimensional cyclic manganese coordination polymers were prepared by reacting divalent manganese salts and 2-{2-[5-(4-pyridyl)-1H-1,2,4-triazol-3-yl]phenoxy}benzoic acid in a solvent.

[0007] The beneficial effects of this invention are as follows: This invention employs a solvothermal method to synthesize one-dimensional cyclic chain manganese coordination polymers. The synthesis process is simple, efficient, and mild. The resulting coordination polymers exhibit good crystal stability and thermal stability, demonstrating highly specific and sensitive detection performance for furazolidone and tetracycline. Specifically, furazolidone's fluorescence quenching of the one-dimensional cyclic chain manganese coordination polymer is mainly static quenching, supplemented by an internal filtering effect. In the ground state, the two form a non-fluorescent complex through hydrogen bonding, and the internal filtering effect induced by spectral overlap synergistically leads to quenching. Tetracycline, on the other hand, exhibits a dominant internal filtering effect with supplementary static quenching. Its absorption spectrum significantly overlaps with the excitation / emission spectrum of the one-dimensional cyclic chain manganese coordination polymer, thus doubly intercepting light energy. Simultaneously, it forms a weakly interacting complex through polar groups.

[0008] Furthermore, the molar ratio of divalent manganese salt to 2-{2-[5-(4-pyridyl)-1H-1,2,4-triazol-3-yl]phenoxy}benzoic acid is (0.05-0.15):(0.02-0.06).

[0009] Preferably, the molar ratio of divalent manganese salt to 2-{2-[5-(4-pyridyl)-1H-1,2,4-triazol-3-yl]phenoxy}benzoic acid is 0.1:0.04.

[0010] Furthermore, divalent manganese salts include manganese sulfate.

[0011] Furthermore, the mass-to-volume ratio of 2-{2-[5-(4-pyridyl)-1H-1,2,4-triazol-3-yl]phenoxy}benzoic acid to the solvent is 10-20 mg: 1.5-12 mL.

[0012] Furthermore, the solvent is a mixed solvent composed of N,N-dimethylformamide and water, with a volume ratio of N,N-dimethylformamide to water of (0.5-2):(1-10).

[0013] Preferably, the solvent is a mixed solvent composed of N,N-dimethylformamide and water, wherein the volume ratio of N,N-dimethylformamide to water is 1:5.

[0014] Furthermore, the mixture of divalent manganese salt, 2-{2-[5-(4-pyridyl)-1H-1,2,4-triazol-3-yl]phenoxy}benzoic acid and solvent was ultrasonically treated for 5-20 min before the reaction.

[0015] Furthermore, the reaction temperature is 100-150 °C, and the time is 24-72 h.

[0016] Preferably, the reaction temperature is 120 °C and the reaction time is 48 h.

[0017] In a second aspect, the present invention provides a one-dimensional cyclic manganese coordination polymer, which is prepared by the above-described preparation method.

[0018] A third aspect of the present invention provides the application of the above-described one-dimensional cyclic coordination polymer in the detection of furazolidone and tetracycline.

[0019] The present invention has the following beneficial effects: 1. This invention successfully synthesized a manganese-based coordination polymer [Mn(PTPBA)2(H2O)2] via a solvothermal method. n This coordination polymer assembles into a three-dimensional supramolecular framework through CH···π interactions and OH···O hydrogen bonds, and possesses good crystal stability and thermal stability.

[0020] 2. The one-dimensional cyclic coordination polymer prepared in this invention exhibits highly specific fluorescence quenching responses to furazolidone and tetracycline, with Stern-Volmer constants of 1.10 × 10⁻⁶. 4 M -1 and 8.18 × 10 4 M -1 With detection limits as low as 12.088 μmol / L and 11.671 μmol / L, it exhibits excellent detection sensitivity and selectivity, demonstrating its potential as a specific fluorescent probe for NFZ and TC. This provides experimental data and theoretical support for the design and development of highly efficient fluorescent sensing materials for antibiotic pollutants. Attached Figure Description

[0021] Figure 1 The infrared spectrum of a one-dimensional cyclic manganese coordination polymer; Figure 2 The diagram shows the coordination environment of a one-dimensional cyclic manganese coordination polymer, where (a) represents the coordination environment of Mn. 2+ The coordination environment of the ions, symmetry codes: #1: -1+x, y, z; #2: 1+x, y, z; #3: 1-x, 1-y, -z; (b) is Mn 2+ (c) is a one-dimensional chain structure diagram; (d) is a three-dimensional supramolecular structure diagram (pink represents CH···π, green represents OH···O). Figure 3 Powder X-ray diffraction pattern of a one-dimensional cyclic manganese coordination polymer; Figure 4 Thermogravimetric analysis diagram of a one-dimensional cyclic manganese coordination polymer; Figure 5 The images show the excitation and emission spectra of a one-dimensional cyclic manganese coordination polymer and the ligand HPTPBA, ​​where (a) is the ligand HPTPBA and (b) is the one-dimensional cyclic manganese coordination polymer. Figure 6 Fluorescence spectra of a one-dimensional cyclic manganese coordination polymer in different solvents; Figure 7 Fluorescence spectra of one-dimensional cyclic manganese coordination polymers in aqueous solutions of different antibiotics; Figure 8 The images show the fluorescence titration diagrams and fitting curves of one-dimensional cyclic manganese coordination polymers for NFZ and TC. In the images, (a) and (b) are the fluorescence titration diagram and fitting curve of NFZ, respectively, and (c) and (d) are the fluorescence titration diagram and fitting curve of TC, respectively. Detailed Implementation

[0022] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0023] Example 1: Preparation of one-dimensional cyclic manganese coordination polymer A method for preparing a one-dimensional cyclic manganese coordination polymer includes the following steps: Manganese sulfate (0.10 mmol, 15.4 mg, Tianjin Damao Chemical Reagent Factory), 2-{2-[5-(pyridin-4-yl)-1H-1,2,4-triazol-3-yl]phenoxy}benzoic acid (HPTPBA, ​​0.04 mmol, 14.3 mg, Jinan Henghua Technology Co., Ltd.), 1 mL N,N-dimethylformamide (DMF), and 5 mL water were mixed and placed in a 25 mL Teflon-lined autoclave. The mixture was then sonicated for 10 min and heated at 120 °C for 48 h. After cooling to room temperature, a colorless, blocky, one-dimensional cyclic chain manganese coordination polymer [Mn(PTPBA)2(H2O)2] was obtained. n (Complex 1), yield 57% (based on HPTPBA).

[0024] The elemental analysis result is C. 40 H 30 MnN8O8: C, 44.89%; H, 2.54%; N, 5.27%. Measured results: C, 44.53%; H, 2.76%; N, 5.31%.

[0025] Example 2: Structural characterization of one-dimensional cyclic manganese coordination polymers The one-dimensional cyclic manganese coordination polymer (complex 1) obtained in Example 1 was characterized by Fourier transform infrared spectroscopy (FT-IR), single crystal X-ray diffraction, powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA).

[0026] Experimental results are as follows Figures 1-4 As shown in Tables 1-3.

[0027] Table 1 Crystal data and structural refinement of coordination compound 1

[0028] Table 2. Partial bond lengths (nm) and bond angles (°) of coordination compound 1

[0029] Table 3. OH···O and CH···II data for complex 1

[0030] FT-IR results show ( Figure 1 ), 1619 cm -1 and 1579 cm -1 The strong absorption peak at 764 cm⁻¹ corresponds to the antisymmetric and symmetric stretching vibrations of the carboxyl group, indicating that the carboxyl group in the ligand has participated in coordination. -1 The strong peak at that point is a characteristic peak of the benzene ring skeleton vibration, further indicating that the HPTPBA ligand was successfully introduced into the complex structure.

[0031] Single-crystal X-ray diffraction analysis results (Tables 1-3) confirmed that complex 1 is a two-dimensional layered coordination polymer, Mn 2+ The nodes are connected by HPTPBA via a double-tooth bridging mode to form an extended structure. The results indicate that coordination compound 1 crystallizes in a monoclinic system with space group [space group missing]. P twenty one / c Its asymmetric unit contains half of Mn 2+ An ion, a completely deprotonated organic ligand, and a coordinated water molecule ( Figure 2 (Figure a) Center Mn 2+ The ions exhibit an octahedral coordination environment, consisting of two oxygen atoms (O1, O1#2) from two different PTPBA ligands, two coordinated water molecules (O1W, O1W#2), and nitrogen atoms (N4#1, N4#3) from two other different PTPBA ligands. Figure 2 (Figure b). These ligands act as bridging structures, connecting the metal center along the b-axis to form a one-dimensional (1D) cyclic chain structure. Figure 2(Figure c) Adjacent one-dimensional ring chains further extend and assemble through CH···π interactions and hydrogen bonds (OH···O), ultimately forming a three-dimensional (3D) supramolecular framework. Figure 2 (Figure d)

[0032] Powder X-ray diffraction analysis results ( Figure 3 The results show that the PXRD pattern of complex 1 prepared in Example 1 of the present invention is highly consistent with the pattern obtained from the simulation of single crystal X-ray diffraction data in terms of peak position and relative intensity. No obvious impurity peaks were detected, indicating that complex 1 has good phase purity.

[0033] Thermogravimetric analysis results showed that complex 1 exhibited excellent thermal stability below 140 °C, with no significant structural decomposition. The initial intermediate loss of 4.46% in the 140-175 °C range was attributed to the loss of two coordinated water molecules, a value highly consistent with the theoretical value (4.63%). No significant weight change was observed in the 180-350 °C range (weight loss <1%), indicating that its coordination framework remained stable within this temperature range. The main framework of complex 1 began to thermally decompose from approximately 350 °C, accompanied by the gradual breakage and combustion of the organic ligand PTPBA, ​​suggesting a collapse of the framework structure. Figure 4 ).

[0034] Example 3: Fluorescence properties of one-dimensional cyclic manganese coordination polymers (1) Solid-state excitation and emission spectra of the one-dimensional cyclic manganese coordination polymer and its ligand HPTPBA prepared in Example 1 were measured. The experimental results are as follows: Figure 5 As shown.

[0035] The results showed that for HPTPBA ( Figure 5 (Figure (a)) The significant absorption peak at 351 nm in its excitation spectrum corresponds to the effective excitation wavelength (light of this wavelength can cause molecules to transition from the ground state to the excited state). After excitation, the emission spectrum shows a strong blue light emission band centered at 440 nm (the excited-state molecule releases energy when returning to the ground state, and 440 nm belongs to the blue light band, and the "strong emission" indicates that its solid-state fluorescence efficiency is high); while complex 1 ( Figure 5 The maximum absorption peak of the excitation spectrum in Figure (b) is located at 320 nm (requiring higher energy ultraviolet light excitation), while the emission spectrum shows a blue light emission peak at 446 nm (slightly longer than HPTPBA). These results indicate that both compounds exhibit blue light emission in the solid state. The slight shift in their excitation / emission wavelengths is essentially due to differences in molecular structure (such as the length of the conjugated system and the type of substituents) modulating the electronic energy levels (the energy difference between the ground and excited states), thus leading to changes in photophysical behavior.

[0036] (2) The fluorescence response behavior of complex 1 in different solvent environments at room temperature was detected. The fluorescence characteristics of different solvents were detected under the following conditions: 2 mg of complex 1 was dispersed in 5 mL of different solvents, and after sonication for 15 min, a stable suspension was obtained. 391 nm was selected as the excitation wavelength, and its fluorescence emission spectrum in different solvents was measured. The different solvents included N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), dimethyl sulfoxide (DMSO), deionized water (H2O), methanol (CH3OH), acetonitrile (CH3CN), and ethanol (EtOH). The experimental results are as follows: Figure 6 As shown.

[0037] The results showed that the fluorescence intensity of complex 1 was significantly solvent-dependent, with the fluorescence intensity order being: DMSO > CH3OH > CH3CN > EtOH > H2O > DMF > DMA. Complex 1 exhibited the strongest fluorescence emission in DMSO, mainly due to the strong polarity and aprotic properties of DMSO. Furthermore, suspensions prepared with all solvents maintained good dispersion stability during the testing period, ensuring the repeatability and reliability of subsequent experiments.

[0038] Example 4: Antibiotic fluorescence detection based on one-dimensional cyclic manganese coordination polymers (1) Selectivity One-dimensional cyclic manganese coordination polymers were used as fluorescent probes for antibiotics to evaluate their selectivity by detecting their detection performance against different antibiotics.

[0039] The specific steps were as follows: 20 mg of the complex 1 sample obtained in Example 1 was uniformly dispersed in 50 mL of DMSO to prepare several stable suspensions. Then, appropriate amounts of 0.1 mol / L different antibiotic solutions were added dropwise, including ornidazole (ORN), metronidazole (DMZ), nitrofurantoin (NFT), nitrofurazone (NFZ), sulfamethoxypyrimidine (SMD), sulfadiazine (SD), thiamphenicol (TAP), metronidazole (MNZ), roxithromycin (ROX), chloramphenicol (CHL), norfloxacin (NOR), tetracycline (TC), and ceftriaxone sodium (CRO). Suspensions without added antibiotics served as a blank control group. After all samples were shaken well and allowed to stand for 5 min, the fluorescence emission spectra were measured at an excitation wavelength of 391 nm. The experimental results are as follows: Figure 7 As shown.

[0040] The results showed that, compared with the blank control group, complex 1 exhibited highly selective fluorescence quenching only in the presence of nitrofurazone (NFZ) and tetracycline (TC), demonstrating specific fluorescence quenching behavior. This indicates that complex 1 achieves highly sensitive antibiotic recognition through a fluorescence quenching response mechanism and exhibits excellent selectivity for NFZ and TC, showing potential application as a specific fluorescent probe for NFZ and TC.

[0041] (2) Sensitivity One-dimensional cyclic manganese coordination polymers were used as fluorescent probes for antibiotics. Fluorescence detection of NFZ and TC at different concentration gradients was performed to characterize their detection sensitivity. Experimental results are as follows: Figure 8 As shown.

[0042] The results showed that when NFZ and TC were dispensed at 0-85 μL (1.0×10⁻⁶ μL), the effect was significantly reduced. -3 mol / L) and 0-90 μL (1.0×10⁻⁶ ... -3 When a concentration gradient of (mol / L) is gradually added to the detection system, the fluorescence intensity of the system exhibits an exponential decay, with fluorescence quenching efficiencies reaching 95.25% and 98.13%, respectively (e.g., mol / L). Figure 8 (Figures (a) and (c) in the middle).

[0043] The Stern-Volmer (SV) equation was used to quantitatively analyze the fluorescence response, using fluorescence intensity ratios... I 0 / I ( I 0 represents the fluorescence intensity of the blank group. I The fluorescence intensity after adding the analyte was fitted to the molar concentration of the analyte [A], and the equation is as follows: I 0 / I =1+ K sv [A] (wherein) K sv (This refers to the Stern-Volmer quenching constant).

[0044] The results showed that in the low concentration range (NFZ: 0-12 μmol / L; TC: 0-15 μmol / L), I 0 / I It shows a good linear relationship with [A] (R) 2 >0.99), indicating that the quenching mechanism is mainly a single mode within this concentration range; the curve deviates slightly from linearity at high concentrations, suggesting the possible coexistence of static and dynamic quenching. Through linear fitting, the corresponding values ​​for NFZ and TC were calculated. K sv The values ​​are 1.10 × 10 4 M -1 and 8.18 × 104 M -1 According to the formula LOD = 3σ / K sv The calculated limits of detection (LODs) for complex 1 for NFZ and TC were 12.088 μmol / L and 11.671 μmol / L, respectively.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a one-dimensional cyclic manganese coordination polymer, characterized in that, Includes the following steps: One-dimensional cyclic manganese coordination polymers were prepared by reacting divalent manganese salts and 2-{2-[5-(4-pyridyl)-1H-1,2,4-triazol-3-yl]phenoxy}benzoic acid in a solvent.

2. The method for preparing the one-dimensional cyclic chain manganese coordination polymer according to claim 1, characterized in that, The molar ratio of the divalent manganese salt to the 2-{2-[5-(4-pyridyl)-1H-1,2,4-triazol-3-yl]phenoxy}benzoic acid is (0.05-0.15):(0.02-0.06).

3. The method for preparing the one-dimensional cyclic manganese coordination polymer according to claim 1 or 2, characterized in that, The divalent manganese salt includes manganese sulfate.

4. The method for preparing the one-dimensional cyclic chain manganese coordination polymer according to claim 1, characterized in that, The solvent is a mixed solvent composed of N,N-dimethylformamide and water, wherein the volume ratio of N,N-dimethylformamide to water is (0.5-2):(1-10).

5. The method for preparing the one-dimensional cyclic manganese coordination polymer according to claim 1, characterized in that, The reaction is carried out at a temperature of 100-150 °C for a time of 24-72 h.

6. A one-dimensional cyclic manganese coordination polymer, characterized in that, It is prepared by the preparation method according to any one of claims 1-5.

7. The application of the one-dimensional cyclic coordination polymer of claim 6 in the detection of furazolidone and tetracycline.

Images