Nickel-based double-ligand coordination polymer crystal material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of crystalline materials, and relates to a metal-organic coordination polymer crystal material, in particular to a nickel-based double-ligand coordination polymer crystal material as well as a preparation method and application thereof. The chemical formula of the nickel-based double-ligand coordination polymer crystal material is {[Ni (1, 4-bib) (BDC) (H2O) 2]. (1, 4-bib) 0.5. H2O} n, and the preparation method comprises the following steps: dissolving NiCl2. 6H2O, H2BDC and 1, 4-bib in a DMF / water mixed solution with a volume ratio of 1: 1, sealing, carrying out a solvothermal reaction, heating at a constant temperature of 90.0 DEG C for 3 days, and slowly cooling the system to room temperature to obtain a green bulk crystal G-Ni. The nickel-based double-ligand coordination polymer crystal material can be applied to Ag < + > recognition and antibiotic detection.

Description

Technical Field

[0001] This invention belongs to the technical field of crystalline materials, and relates to metal-organic coordination polymer crystal materials, specifically a nickel-based dual-ligand coordination polymer crystal material, its preparation method, and its application. Background Technology

[0002] Silver ions (Ag) + As a core raw material in electronics manufacturing, electroplating processes, and medical antibacterial applications, silver's industrial application scale continues to expand. However, the resulting environmental pollution and health risks cannot be ignored. Globally, soluble Ag is released into the environment annually through industrial wastewater, electronic waste (such as 0.3-0.5g of silver per discarded mobile phone), and antibacterial products. + The total amount exceeds 10,000 tons. At the same time, the overuse of antibiotics has also brought serious environmental problems. Large quantities of incompletely metabolized antibiotics (such as sulfonamides and nitroimidazoles) enter the environment through medical wastewater, aquaculture emissions, and pharmaceutical wastewater, inducing the emergence of drug-resistant bacteria, disrupting the balance of aquatic ecosystems, and threatening human health through the food chain. These Ag... + And residual antibiotics exhibit significant biotoxicity in the natural environment: extremely low concentrations of Ag in water bodies + Antibiotics can inhibit algal photosynthesis, damaging the primary productivity of aquatic ecosystems; and the continued presence of antibiotics, due to their strong biotoxicity and potential carcinogenicity, poses a serious threat to ecological security and public health. Ag in soil + When the content reaches a certain threshold, it directly affects soil fertility and agricultural sustainability. Even more serious is the impact of Ag... + After entering the human body through drinking water and the food chain, antibiotics specifically bind to thiol groups, disrupting the antioxidant system. Long-term exposure can lead to liver and kidney damage, neurodegenerative diseases, and psoriasis, posing a direct threat to human health. Human exposure to antibiotics is associated with gut microbiota dysbiosis, allergic reactions, and potential chronic toxicity risks.

[0003] Currently, Ag + The detection techniques for various environmental antibiotics mainly rely on inductively coupled plasma mass spectrometry (ICP-MS), high-performance liquid chromatography-mass spectrometry (HPLC-MS), and atomic absorption spectrometry (AAS). While ICP-MS offers high sensitivity, its cost per detection is high; HPLC-MS, although capable of accurately quantifying multiple antibiotics, suffers from expensive equipment and complex pretreatment, hindering its widespread application in real-time monitoring; AAS is primarily used for the quantitative analysis of metal ions and has limited application in antibiotic detection. Traditional fluorescent probes (such as organic dyes and quantum dots), while possessing rapid response characteristics, generally suffer from complex synthesis processes and poor photostability, making them unsuitable for complex industrial environments such as high temperatures and high ionic strength.

[0004] To address this bottleneck, metal-organic coordination polymers (CPs) have shown unique potential. Due to their designable and controllable structures, coordination compounds have become a hot topic in materials research in recent years. The structure of coordination compounds can be modulated not only by changing the metal cations and organic ligands, but also by altering the synthesis conditions. Therefore, coordination polymers have significant potential applications in the field of fluorescence recognition. Among the ligands used to synthesize coordination compounds, nitrogen-containing heterocyclic carboxylic acid ligands possess advantages such as strong coordination ability, flexible coordination modes, and ease of controllable assembly of coordination polymers with diverse structures by changing experimental conditions. Therefore, research on the structure and properties of coordination polymers constructed from these ligands has attracted considerable attention. Furthermore, the addition of auxiliary ligands can enrich the structural types of coordination polymers. Because nickel (Ni... 2+ [Ar]3d complexes have attracted much attention in the field of materials research, due to their unique electronic configuration. 8 4s 2 This endows it with special properties. And Ni 2+ With coordination flexibility, fluorescence properties can be modulated through metal-ligand charge transfer (MLCT) or ligand central luminescence (LC) mechanisms, exhibiting good recognition potential for specific analytes (such as metal ions and small organic molecules). Based on the advantages of CPs in fluorescence sensing and Ni… 2+ Given the central characteristics of this study, we aim to develop a novel and stable nickel-based complex fluorescent probe, with the goal of detecting typical environmental pollutants (such as heavy metal Ag). + It enables efficient and rapid identification of antibiotic residues. Summary of the Invention

[0005] One of the objectives of this invention is to provide a nickel-based dual-ligand coordination polymer crystal material.

[0006] The chemical formula of the nickel-based dual-ligand coordination polymer crystal material is {[Ni(1,4-bib)(BDC)(H2O)2]·(1,4-bib)} 0.5 H2O n (named G-Ni), where BDC 2- The chemical structure of H2BDC, which is deprotonated terephthalic acid, is shown below: ; 1,4-bib is 1,4-bis(imidazol-1-yl)benzene (CAS: 25372-07-0), and its chemical structure is shown below: .

[0007] Furthermore, from the perspective of structural connection construction, the nickel-based dual-ligand coordination polymer crystal material G-Ni is a two-dimensional network structure that can form a three-dimensional supramolecular structure through H-bond interactions. The crystal structure belongs to the triclinic crystal system. P Space group -1, cell parameters are: a=10.4561(4) Å, b=11.3069(5) Å, c=12.1837(6) Å, α =79.546(2), β =76.815(2), γ =65.4270(10).

[0008] Furthermore, the asymmetric structural unit of G-Ni contains two distinct Ni(II), Ni1 and Ni2, both with a coordination number of 6. Both Ni1 and Ni2 are coordinated with two N atoms and four O atoms, with the two N atoms originating from different 1,4-bib ligands, and the two O atoms from different BDCs. 2- The ligands, with the other two O atoms coming from two water molecules; both Ni1 and Ni2 are simultaneously bonded to two ligands L. 2- Each L 2- Then, two Ni(II) groups are connected; and Ni1 and Ni2 are directly connected through the 1,4-bib ligand. Therefore, Ni1 and Ni2 form a 1D chain structure with the 1,4-bib ligand, and then are connected through the L ligand. 2- The connections form a 2D mesh structure; In G-Ni, there are intermolecular H bonds between the 2D network structures formed by Ni1 and Ni2, namely O3—H3B···O6 and O4—H4B···O2. Through these H bonds, the 2D network structures stack up to form a 3D supramolecular structure.

[0009] This invention also provides a method for preparing nickel-based dual-ligand coordination polymer crystal materials, comprising the following steps: NiCl2·6H2O, H2BDC, and 1,4-bib were dissolved in a 1:1 DMF / water mixture, sealed, and subjected to a solvothermal reaction at 90.0℃ for 3 days. After the system slowly cooled to room temperature, green blocky crystals {[Ni(1,4-bib)(BDC)(H2O)2]·(1,4-bib)} were obtained. 0.5 H2O n ,G-Ni.

[0010] Furthermore, the molar ratio of NiCl2·6H2O, 1,4-bib ligand, and H2BDC was 4:2:1.

[0011] Furthermore, the volume ratio of DMF to water is 1:1, and the amount of DMF / water mixed solution added is limited to 8.0 mL of mixed solution for every 0.10 mmol.

[0012] Furthermore, the solvothermal reaction was carried out under constant temperature heating at 90.0℃ for 3 days.

[0013] Furthermore, the present invention also provides coordination polymer crystal materials of the nickel-based dual ligands in Ag. + Applications in identification and detection.

[0014] Furthermore, the present invention also provides the application of the coordination polymer crystal material of the nickel-based dual ligand in antibiotic detection.

[0015] Beneficial technical effects of the present invention: (1) Coordination polymers with good thermal stability are more suitable as recognition materials and are easier to apply in high-temperature and complex environments. The thermal degradation process of coordination polymers is often accompanied by the breaking of coordination bonds and the combustion of ligands. Therefore, the thermal stability of coordination polymers is generally related to the strength of coordination bonds and the number of nodal ligands. Common Ni 2+ The coordination numbers are 4 and 6, and Ni in the G-Ni complex of this invention 2+ The coordination number of all three compounds in the G-Ni complex is 6, with both Ni1 and Ni2 in the G-Ni complex carrying two coordinated water molecules. Therefore, even if Ni1 and Ni2 lose their two coordinated water molecules and the coordination number becomes 4, the structure in the G-Ni complex can still maintain its integrity. Although the G-Ni complex has a 2D layered structure, intermolecular forces such as hydrogen bonds exist between adjacent chains, which increases the stability of the complex structure. Thermogravimetric analysis shows that the substance exhibits good thermal stability with minimal weight change in the temperature range of 30℃ to 420℃. However, when the temperature exceeds 420℃ and reaches 490℃, the weight decreases significantly by 54.67%, indicating structural collapse. Therefore, the structure of G-Ni remains stable below 420℃. This good thermal stability contributes to the widespread application of G-Ni.

[0016] (2) Guided by the synthesis of novel nickel complex fluorescent probes, this invention selects terephthalic acid (H2BDC) and 1,4-bis(imidazol-1-yl)benzene (1,4-bib) as ligands to precisely design and synthesize a probe that can be used for rapid identification of Ag. + Thermogravimetric analysis showed that G-Ni remains stable below 420℃, exhibiting excellent thermal stability. Combined with its superior fluorescence properties and structural stability, this material is suitable for use in high-concentration Ag+ leaching solutions from industrial wastewater and electronic waste. +The application scenarios are highly adaptable. Preliminary studies show that G-Ni exhibits differential fluorescence responses to various antibiotics in the aquatic environment, with a significant quenching effect on nitroimidazole antibiotics, demonstrating its potential for specific recognition of this type of pollutant. Compared to traditional detection techniques, G-Ni shows significant advantages in industrial-grade Ag... + It exhibits the following advantages in antibiotic residue monitoring: low raw material cost, high detection efficiency, convenient operation, and provides an economical and efficient innovative solution for real-time monitoring of high-concentration pollution sources. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the Ni(II) coordination environment in G-Ni of the present invention (symmetric code: i 1- x , 2- y , 1- z ; ii 1- x , 1- y , 1- z ; iii 3-x, -y, 2-z; iv 3-x, -1-y, 2-z.

[0018] Figure 2 This refers to the 2D network structure present in G-Ni of the present invention.

[0019] Figure 3 This is the 3D structure present in G-Ni of the present invention, with hydrogen bonds between adjacent network structures. Green dashed line: O4—H4B···O2; Purple dashed line: O3—H3B···O6.

[0020] Figure 4 This is the thermogravimetric analysis diagram of G-Ni in this invention.

[0021] Figure 5 This is the infrared spectrum of G-Ni according to the present invention.

[0022] Figure 6 The fluorescence emission spectra of G-Ni, H2BDC, and 1,4-bib of this invention are shown.

[0023] Figure 7 This is the fluorescence emission spectrum of G-Ni in common solvents according to the present invention.

[0024] Figure 8 The fluorescence emission spectra of G-Ni before and after immersion in aqueous solution for 6 days are shown.

[0025] Figure 9 For the present invention, G-Ni in 10 -3Fluorescence emission spectra of non-rare earth metal salts (NaNO3, KNO3, Al(NO3)3, Cr(NO3)3, Mn(NO3)2, Fe(NO3)3, Co(NO3)2, Ni(NO3)2, Cu(NO3)2, Zn(NO3)2, Pb(NO3)2, AgNO3, Cd(NO3)2, Bi(NO3)3) in solutions at mmol / mL.

[0026] Figure 10 For the present invention, G-Ni in 10 -3 The intensity bar chart of the strongest emission peak at 377 nm in solutions of non-rare earth metal salts (NaNO3, Al(NO3)3, KNO3, Fe(NO3)3, Co(NO3)2, Ni(NO3)2, Cu(NO3)2, Zn(NO3)2, AgNO3, Cd(NO3)2, Pb(NO3)2) at mmol / mL.

[0027] Figure 11 For the present invention, G-Ni in 10 -3 Fluorescence emission spectrum in mmol / mL rare earth salt solution.

[0028] Figure 12 For the present invention, G-Ni in 10 -3 Bar graph of the strongest emission peak intensity in mmol / mL rare earth salt solution.

[0029] Figure 13 For the G-Ni blank and Ag addition of this invention + The image was then taken under ultraviolet light at a wavelength of 254nm.

[0030] Figure 14 This invention relates to G-Ni at different concentrations of Ag. + Fluorescence emission spectrum of the solution.

[0031] Figure 15 Ag of G-Ni in this invention + Biphasic response curves of concentration logarithm versus fluorescence enhancement rate.

[0032] Figure 16 The present invention relates to G-Ni and Ag + Bar graph of anti-interference experiment.

[0033] Figure 17 For the present invention, G-Ni in 10 -3 Fluorescence emission spectrum of antibiotic solution at mmol / mL.

[0034] Figure 18 For the present invention, G-Ni in 10 -3 Bar graph showing the intensity of the strongest emission peak near 380 nm in mmol / mL antibiotic solution.

[0035] Figure 19 Images of G-Ni before and after the addition of metronidazole (MNZ) under ultraviolet light at a wavelength of 254 nm, as shown in this invention.

[0036] Figure 20 Images of G-Ni before and after the addition of dimethylnitroimidazole (DMZ) under ultraviolet light at a wavelength of 254 nm, as shown in this invention.

[0037] Figure 21 The fluorescence emission spectra of G-Ni in metronidazole (MNZ) solutions of different concentrations are shown.

[0038] Figure 22 This is a standard curve of fluorescence quenching rate versus concentration logarithm of G-Ni in metronidazole (MNZ) solutions of different concentrations according to the present invention.

[0039] Figure 23 The fluorescence emission spectra of G-Ni in dimethylnitroimidazole (DMZ) solutions of different concentrations are shown in this invention.

[0040] Figure 24 This is a standard curve of fluorescence quenching rate versus concentration logarithm of G-Ni in dimethylnitroimidazole (DMZ) solutions of different concentrations.

[0041] Figure 25 Bar graph showing the anti-interference effect of G-Ni on metronidazole (MNZ).

[0042] Figure 26 Bar graph showing the anti-interference experiment of G-Ni against dimethylnitroimidazole (DMZ). Detailed Implementation

[0043] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0044] Example 1 NiCl₂·6H₂O (23.8 mg, 0.10 mmol), 1,4-bib ligand (10.0 mg, 0.05 mmol), and H₂BDC (4.2 mg, 0.025 mmol) were mixed and then added to DMF / H₂O (1:1, v / v) (8.0 mL). The resulting solution was sealed in a 20.0 mL flask and heated at 90°C for three days. After cooling to room temperature, green bulk crystals of G-Ni were obtained in 45% yield.

[0045] See below for details: (1) Determination of crystal structure: Crystals with good growth and few cracks were selected and adhered to thinned glass wires. Diffraction data of G-Ni were collected at room temperature under Mo-Kα radiation (λ=0.71073Å) using a Bruker APEX-II CCD single-crystal diffractometer. The structure was solved using the XS structure solver and optimized using the SHELXTL software package using the least squares method. Anisotropic shift parameters of non-hydrogen atoms were provided during the improvement process. The positions of hydrogen atoms on the ligands were determined using the theoretical hydrogenation method. Crystallographic data are shown in Table 1.

[0046] Table 1. Crystallographic data of G-Ni materials

[0047] The structural diagram of G-Ni is as follows: Figure 1-3 As shown, Figure 1 This indicates the coordination environment of Ni(II). Figure 2 This indicates that it is composed of 1,4-bib, BDC 2- A network structure composed of Ni(II), Figure 3 This indicates that the H-bond interactions between adjacent networks enable G-Ni to form a 3D supramolecular structure.

[0048] Figure 4 The thermogravimetric analysis results show that G-Ni has good thermal stability and can maintain the stability of the framework structure below 420℃.

[0049] Figure 5 The Fourier transform infrared spectrum shows that, using a Shimadzu FTIR-8400S spectrometer, the wavelength range is 4000-500 cm⁻¹. -1 FT-IR spectra of G-Ni were collected within the range of [missing information], and the corresponding characteristic absorption peaks were characterized, confirming the coordination between the metal and the ligand.

[0050] Figure 6This is the solid-state fluorescence emission spectrum of G-Ni and its ligands according to the present invention. The solid-state emission spectra of G-Ni and its ligands were studied at room temperature. The strongest emission peak of H₂BDC at an excitation wavelength of 318 nm is at 381 nm; the strongest emission peak of the 1,4-bib ligand at an excitation wavelength of 300 nm corresponds to a wavelength of 334 nm; in the test, the strongest emission peak of the complex G-Ni appears at 375 nm when the excitation wavelength is set to 339 nm. Compared with H₂BDC, the strongest excitation peak of G-Ni shows a slight blue shift; compared with the 1,4-bib ligand, G-Ni shows a red shift. This change in the shift of the strongest emission peak is related to the coordination between the ligand and the metal ion. The position of the strongest emission peak of Ni is between the positions of the strongest emission peaks of the two ligands, so the luminescence of the complex G-Ni mainly comes from ligand luminescence, primarily due to electronic transitions between ligands.

[0051] At room temperature, a powder sample (3 mg) of complex G-Ni was immersed in 3 mL of different organic solvents: anhydrous methanol (MeOH), anhydrous ethanol (EtOH), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), and water (H2O). The above mixed solutions were then sonicated for 15 min to obtain a suspension for fluorescence detection. Figure 7 The fluorescence emission spectrum of G-Ni in common solvents is shown. It shows that compared with solid fluorescence, the shift of its strongest emission peak does not change much (the strongest peak is at 377 nm), but the fluorescence intensity varies greatly in different solvents. The intensity of the strongest emission peak decreases in the following order: water > DMA > MeOH > EtOH > DMF > DMSO > NMP. The above phenomenon can be attributed to the interaction between the complex and solvents with different polarities. This phenomenon is due to the intermolecular interaction caused by the difference in solvent polarity. Water was chosen as the detection solvent based on three advantages: (1) Optimal fluorescence response: The fluorescence intensity of G-Ni in the aqueous phase (5177 au) is significantly better than that in organic solvents, reaching 3.27 times that in the DMA phase; (2) Environmental friendliness: Eliminates the toxicity risk of organic solvents and meets the standards of green chemistry; (3) Adaptability to practical scenarios: It can directly detect complex matrices such as environmental water samples and industrial wastewater.

[0052] To test the fluorescence stability of G-Ni in aqueous solution, its fluorescence intensity was measured at the initial stage and after a 6-day interval. The results are shown in the table below. Figure 8 In aqueous solution, the fluorescence emission spectra of the samples showed no significant changes at the initial stage and after a 6-day interval, indicating that the complex G-Ni has good fluorescence stability in aqueous solution.

[0053] G-Ni was added to 0.001 mmol / mL solutions of NaNO3, KNO3, Al(NO3)3, Cr(NO3)3, Mn(NO3)2, Fe(NO3)3, Co(NO3)2, Ni(NO3)2, Cu(NO3)2, Zn(NO3)2, Pb(NO3)2, AgNO3, Cd(NO3)2, Bi(NO3)3, and rare earth metal salts Y(NO3)3, La(NO3)3, Ce(NO3)3, Pr(NO3)3, Nd(NO3)3, Sm(NO3)3, Eu(NO3)3, Gd(NO3)3, Tb(NO3)3, Dy(NO3)3, Ho(NO3)3, Er(NO3)3, Tm(NO3)3, Yb(NO3)3, and Lu(NO3)3 prepared in water as solvent. The fluorescence emission spectra were measured, and the results are shown below. Figure 9-12 .

[0054] Figure 9 The fluorescence emission spectra of G-Ni in solutions containing different non-rare earth metal ions are shown. The results indicate that the emission spectra are similar in shape, with the strongest emission peak of G-Ni around 380 nm in all solutions containing different rare earth metal ions, but the fluorescence intensity varies. When Ag is added... + In solution, this leads to enhanced fluorescence, approximately a fourfold increase. The addition of other metal ions results in varying degrees of fluorescence attenuation. Therefore, for Ag... + It has fluorescence recognition capabilities.

[0055] Figure 10 This is a bar chart showing the intensity of the strongest emission peak of G-Ni in different non-rare earth metal ion solutions. The fluorescence intensity of the strongest emission peak of G-Ni varies in different non-rare earth metal ion solutions, particularly in Ag... + The highest strength is found in the medium-strength Fe. 3+ The lowest intensity is medium.

[0056] Figure 11 The images show the fluorescence emission spectra of G-Ni in solutions containing different rare earth metal ions. The fluorescence emission spectra of G-Ni in these solutions are similar in shape, with the strongest emission peak around 380 nm, but the fluorescence intensities differ. Compared to the blank sample, the peaks are weakened in all rare earth ion solutions.

[0057] Figure 12 This is a bar graph showing the intensity of the strongest emission peak of G-Ni in different rare earth metal ion solutions. The fluorescence intensity of G-Ni varies in different rare earth metal ion solutions, especially in La... 3+ The highest strength is in the medium range, Ce. 3+ The lowest intensity is medium.

[0058] In summary, compared with the sample without metal salt, the position of the strongest emission peak of G-Ni remained largely unchanged, both around 380 nm, but the fluorescence intensity changed significantly. Notably, the fluorescence intensity of G-Ni increased significantly after the addition of AgNO3 solution, reaching 392.5% of the intensity of the blank control sample. This indicates that the complex G-Ni has a significant effect on Ag... + It has strong fluorescence recognition effect and can be used as Ag. + The potential of fluorescence sensors.

[0059] Figure 13 G-Ni blank and Ag addition + The image was then taken under ultraviolet light at a wavelength of 254nm.

[0060] Given the effect of complex G-Ni on Ag + Exhibiting significant fluorescence response characteristics, we quantitatively analyzed it using a fluorescence titration experiment. Different concentrations of Ag were added to the aqueous system of the complex. + Subsequently, the fluorescence intensity at specific characteristic wavelengths showed significant changes, and with Ag + The changes in concentration exhibit regular fluctuations, which can be used to assess Ag. + The effect of concentration on the fluorescence emission intensity of the complex.

[0061] A series of Ag concentrations were prepared using water as a solvent. + Solution (concentration gradient: 10) -6 M~10 -3 M), and a detection system was constructed by mixing with the complex. Fluorescence intensity at characteristic wavelengths was measured using a fluorescence spectrophotometer, and the enhancement rate was calculated using the formula: Enhancement rate (%) = (I / I0-1)×100%. Where I0 is the fluorescence intensity of the blank group (aqueous system containing only G-Ni), and I is the fluorescence intensity of the sample group (G-Ni + Ag). + Fluorescence intensity.

[0062] Experimental results show that silver ions (Ag) + The detection system exhibits a unique concentration-dependent biphasic fluorescence response, a key characteristic of its specific interaction with the probe. Specifically, when Ag... + At lower concentrations (approximately -6 to -5 logarithmic values), the system exhibits fluorescence quenching (manifested as a negative fluorescence enhancement rate). However, when Ag... + The concentration exceeds a specific threshold (lgC = -5.0, corresponding to a concentration of 10). -5 After M), the system response undergoes a characteristic reversal, with the fluorescence signal changing from quenching to a strong enhancement effect. Figure 14 Its enhancement rate increases exponentially with increasing concentration, and reaches a maximum at lgC = -3.0 (corresponding to a concentration of 10). -3The fluorescence enhancement rate peaked at 292.3% at point M. This critical concentration point of lgC = -5 was clearly defined as the key threshold for the transition from fluorescence quenching to enhancement (i.e., the "quenching → enhancement transition point"), and is crucial for distinguishing Ag from other fluorescence sources. + The core characteristic of the biphasic feedback effect. This unique phenomenon manifests as: as Ag... + Concentration from extremely low levels (e.g., 10) -6 As M gradually increases, the fluorescence intensity first undergoes a certain degree of decay (manifested as quenching); upon reaching the critical concentration point (10), the fluorescence intensity... -5 After M), if the concentration continues to increase, the fluorescence intensity will show a significant upward trend (increase). Figure 15 Ag of G-Ni in this invention + A biphasic response curve of concentration logarithm versus fluorescence enhancement rate. This reveals the Ag-dependent fluorescence of G-Ni. + The biphasic response of concentration logarithm to fluorescence enhancement rate is visually illustrated by this curve. + The changes in fluorescence enhancement rate following the logarithmic change in concentration are used to investigate the interaction between G-Ni and Ag. + The interactions and related properties provide crucial visualization evidence.

[0063] In addition, anti-interference experiments were also conducted. Figure 16 The present invention relates to G-Ni and Ag + Bar graph of anti-interference experiment. At room temperature, the addition of G-Ni to or from Na was tested. + K + Co 2+ Ni 2+ 、Zn 2+ Cd 2+ Ag + Solution fluorescence emission spectrum. The position of the strongest emission peak remained unchanged, indicating no Ag was added. + At that time, G-Ni in Na + K + Co 2+ Ni 2+ 、Zn 2+ Cd 2+ The fluorescence intensity is lower than that without the addition of metal ions ( Figure 10 ). In Na + K + Co 2+ Ni 2+ 、Zn 2+ Cd 2+ Add Ag to the solution + The fluorescence intensity then significantly increased. Therefore, in the detection of Ag by G-Ni... + Is there Na in the middle? + K + Co2+ Ni 2+ 、Zn 2+ Cd 2+ The effect on the test results was minimal, with all phenomena showing fluorescence enhancement. The results indicate that G-Ni significantly affects Ag... + It has a certain degree of selectivity and anti-interference ability.

[0064] It is worth noting that the multifunctional recognition properties of G-Ni have been further extended to the field of antibiotic detection. G-Ni (3 mg) was dispersed in an aqueous solution containing 0.001 mmol / mL of 10 different antibiotics, which were mainly: sulfamethoxazole (SMZ), erythromycin (EM), sulfadiazine sodium (SDM-Na), amoxicillin (AMX), florfenicol (FFC), sulfathiazole (ST), sulfadiazine (SD), chloramphenicol CAP, metronidazole (MNZ), and dimetronidazole (DMZ). Figure 17 The images show the fluorescence emission spectra of G-Ni in different antibiotic solutions. The fluorescence emission spectra are similar in shape, with the strongest emission peak around 380 nm. However, nitroimidazole antibiotics (metronidazole MNZ and dimetronidazole DMZ) induce a significant fluorescence quenching effect. Compared to the blank control sample without antibiotics, the fluorescence intensity quenching rate of the metronidazole MNZ system is as high as 99.2%, and that of the dimetronidazole DMZ system is over 99.5%. The changes in fluorescence intensity enhancement or weakening for other antibiotics are not significant. Figure 18 This is a bar chart showing the intensity of the strongest emission peak of G-Ni in different antibiotic ion solutions. The fluorescence intensity of the strongest emission peak varies, with the highest intensity in sulfamethoxazole (MNZ) and the lowest intensity in dimetronidazole (DMZ). Therefore, it has a fluorescent recognition effect on metronidazole (MNZ) and dimetronidazole (DMZ). Images of G-Ni before and after the addition of metronidazole (MNZ) under 254nm ultraviolet light are shown below. Figure 19 As shown, images of G-Ni before and after the addition of dimetronidazole (DMZ) under 254nm ultraviolet light are as follows. Figure 20 As shown.

[0065] Given the excellent fluorescence quenching effect of G-Ni on metronidazole (MNZ) and dimetridazole (DMZ), quantitative analysis was performed using fluorescence titration experiments. The addition of these two nitroimidazole antibiotics significantly reduced the fluorescence intensity at 380 nm, and the change in concentration of the nitroimidazole antibiotics showed a certain regularity. The effects of increasing concentrations of metronidazole (MNZ) and dimetridazole (DMZ) on the emission intensity of the G-Ni fluorescence sensor were evaluated. A series of concentration solutions of MNZ and DMZ were prepared using water as the solvent (concentration gradient: 10). -6 M~10 -3M), and G-Ni were mixed to construct the detection system. Fluorescence intensity at a characteristic wavelength of 380 nm was measured using a fluorescence spectrophotometer, and the quenching rate was calculated using the formula: Quenching rate (%) = (I0 - I) / I * 100%. Where I0 is the fluorescence intensity of the blank group (aqueous system containing only G-Ni), and I is the fluorescence intensity of the sample group (G-Ni + target antibiotic). Through a series of experiments, a good linear correlation was found between the quenching rate and the concentrations of MNZ and DMZ. The key data of the concentration-quenching rate standard curves of MNZ and DMZ are as follows: MNZ system: see Figure 21 and 22 The concentration is 10 -6 At M, the quenching rate was -16.8% (fluorescence enhancement, reflecting the unique interaction between the antibiotic and G-Ni at low concentrations); when the concentration increased to 10... -5 At M, the quenching rate turned to 16.0% (fluorescence decay); when the concentration increased to 10... -4 At M, the quenching rate reached 52.7%; at a concentration of 10... -3 At time M, the quenching rate rises sharply to 99.4%. The standard curve fitting equation is y = 38.536x + 211.232 (R²). 2 =0.98996), linear interval coverage 10 -6 M~10 -3 M proves that the concentration of an unknown sample can be inferred from the quenching rate, thus enabling quantitative detection.

[0066] DMZ system: see Figure 23 and 24 The concentration response trend is consistent with MNZ, at a concentration of 10. -6 At M, the quenching rate was -16.82% (fluorescence enhancement); when the concentration increased to 10... -5 At M, the quenching rate turned to 19.3% (fluorescence decay); when the concentration increased to 10... -4 At M, the quenching rate reached 56.5%; at a concentration of 10... -3 The accuracy reached 99.6% at time M. The standard curve fitting equation is y = 35.91x + 203.52 (R²). 2 =0.98486), indicating good linearity and supporting the feasibility of quantitative detection.

[0067] Good anti-interference performance is an important prerequisite for the practical application of fluorescence sensing materials. To evaluate the specific recognition ability of G-Ni for MNZ and DMZ, the influence of other antibiotics within the test range on its detection results was investigated, and its anti-interference performance was analyzed.

[0068] Taking the anti-interference experiment of MNZ as an example, the changes in fluorescence intensity before and after adding MNZ to other antibiotic solutions were compared. In the experimental group, multiple 3mg portions of G-Ni solid were accurately weighed and added to 1.5mL of 8 different antibiotic solutions (2×10⁻⁶). -3 mmol / mL, including sulfamethoxazole SMZ, erythromycin EM, sulfadiazine sodium SDM-Na, amoxicillin AMX, florfenicol FFC, sulfathiazole ST, sulfadiazine SD, chloramphenicol CAP, plus 1.5 mL of MNZ stock solution (2 × 10 mmol / mL). -3 A test system with a total volume of 3 mL was constructed, containing 1.0 × 10 mmol / mL MNZ. -3 mmol / mL. The control group consisted of other antibiotic solutions without MNZ. Fluorescence intensity was measured after 30 min of sonication. The interference resistance test for DMZ was performed using the same procedure as for MNZ. Results are shown below. Figure 25 and 26 , Figure 25 The bar graph shows the anti-interference effect of G-Ni on metronidazole (MNZ). At room temperature, after adding metronidazole MNZ, the fluorescence intensity of G-Ni was significantly quenched in solutions containing other antibiotics (sulfamethoxazole SMZ, erythromycin EM, sulfadimidine sodium SDM-Na, amoxicillin AMX, florfenicol FFC, sulfathiazole ST, sulfadiazine SD, and chloramphenicol CAP). Therefore, the quenching effect of G-Ni on metronidazole (MNZ) was not significantly affected by the presence or absence of other antibiotics (sulfamethoxazole SMZ, erythromycin EM, sulfadimidine sodium SDM-Na, amoxicillin AMX, florfenicol FFC, sulfathiazole ST, sulfadiazine SD, and chloramphenicol CAP), and quenching was still significant, with quenching rates exceeding 98.2%. The results indicate that G-Ni has good selectivity and anti-interference ability against metronidazole MNZ.

[0069] Figure 26 This is a bar graph showing the anti-interference effect of G-Ni on dimetridazole (DMZ). At room temperature, after the addition of dimetridazole (DMZ), the fluorescence intensity of G-Ni in solutions of other antibiotics (sulfamethoxazole SMZ, erythromycin EM, sulfadimidine sodium SDM-Na, amoxicillin AMX, florfenicol FFC, sulfathiazole ST, sulfadiazine SD, and chloramphenicol CAP) was significantly quenched, with quenching rates exceeding 98.8%. The results indicate that G-Ni exhibits good selectivity and anti-interference ability against dimetridazole DMZ.

Claims

1. A nickel-based dual-ligand coordination polymer crystal material, characterized in that: The chemical formula of the nickel-based dual-ligand coordination polymer crystal material is {[Ni(1,4-bib)(BDC)(H2O)2]·(1,4-bib)} 0.5 H2O n， Named G-Ni, where BDC 2- It is terephthalic acid, and its chemical structural formula is shown below: ； 1,4-bib is 1,4-bis(imidazol-1-yl)benzene, and its chemical structural formula is shown below: 。 2. The nickel-based dual-ligand coordination polymer crystal material according to claim 1, characterized in that: From the perspective of structural connection construction, the nickel-based dual-ligand coordination polymer crystal material G-Ni is a two-dimensional network structure that can form a three-dimensional supramolecular structure through H-bonding. The crystal structure belongs to the triclinic crystal system. P Space group -1, cell parameters are: a=10.4561(4) Å, b=11.3069(5) Å, c=12.1837(6) Å, α =79.546(2), β =76.815(2), γ =65.4270(10).

3. The nickel-based dual-ligand coordination polymer crystal material according to claim 2, characterized in that: The asymmetric structural unit of G-Ni contains two distinct Ni(II) atoms, Ni1 and Ni2, both with a coordination number of 6. Both Ni1 and Ni2 are coordinated with two N atoms and four O atoms, with the two N atoms originating from different 1,4-bib ligands and the two O atoms from different BDCs. 2- The ligands, with the other two O atoms coming from two water molecules; both Ni1 and Ni2 are simultaneously bonded to two ligands L. 2- Each L 2- Then, two Ni(II) groups are connected; and Ni1 and Ni2 are directly connected through the 1,4-bib ligand. Therefore, Ni1 and Ni2 form a 1D chain structure with the 1,4-bib ligand, and then are connected through the L ligand. 2- The connections form a 2D mesh structure; In G-Ni, there are intermolecular H bonds between the 2D network structures formed by Ni1 and Ni2, namely O3—H3B···O6 and O4—H4B···O2. Through these H bonds, the 2D network structures stack up to form a 3D supramolecular structure.

4. A method for preparing a nickel-based dual-ligand coordination polymer crystal material as described in any one of claims 1-3, characterized in that: The steps include: NiCl2·6H2O, H2BDC, and 1,4-bib were dissolved in a 1:1 DMF / water mixture, sealed, and subjected to a solvothermal reaction at 90.0℃ for 3 days. After the system slowly cooled to room temperature, green blocky crystals {[Ni(1,4-bib)(BDC)(H2O)2]·(1,4-bib)} were obtained. 0.5 H2O n ,G-Ni.

5. The method for preparing the nickel-based dual-ligand coordination polymer crystal material according to claim 4, characterized in that: The molar ratio of NiCl2·6H2O, 1,4-bib ligand, and H2BDC is 4:2:

1.

6. The method for preparing the nickel-based dual-ligand coordination polymer crystal material according to claim 4, characterized in that: The volume ratio of DMF to water is 1:1, and the amount of DMF / water mixed solution added is limited to 8.0 mL of mixed solution for every 0.10 mmol.

7. The method for preparing the nickel-based dual-ligand coordination polymer crystal material according to claim 4, characterized in that: The solvothermal reaction was carried out under constant temperature heating at 90.0℃ for 3 days.

8. A coordination polymer crystal material with nickel-based dual ligands as described in any one of claims 1-3 in Ag + Applications in identification and detection.

9. The application of a nickel-based dual-ligand coordination polymer crystal material as described in any one of claims 1-3 in the detection of metronidazole MNZ and dimetronidazole DMZ.

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