A three-dimensional binuclear terbium coordination polymer and its preparation method and application

Abstract

The present invention provides a three-dimensional binuclear terbium coordination polymer, the molecular formula of which is: [Tb 2 (μ 3 ‑HIA) 3 ·2H 2 O] n , of which HIA 2‑ It is a form of 5-(hydroxymethyl)isophthalic acid without two protons, and n represents the degree of polymerization. The metal coordination polymer crystal is in the monoclinic system, the space group is C2 / c, and the unit cell parameters are #imgabs0#α=γ=90°, β=115.0037(16)°. The terbium coordination polymer provided by the invention is obtained under hydrothermal conditions, has a simple preparation process, and a high yield, and can be used as a quenching fluorescent probe for efficiently detecting acetone molecules and hexavalent chromium ions.

Description

Technical Field

[0001] The invention belongs to the field of rare earth metal coordination polymers, and in particular relates to a three-dimensional binuclear terbium coordination polymer and a preparation method and application thereof. Background Art

[0002] Lanthanide complexes have attracted extensive attention due to their long luminescence lifetime, large Stokes shift, sharp emission lines, etc. In addition, lanthanide complexes are also used as fluorescent probes to detect small organic molecules and harmful ions, with advantages such as high sensitivity, high selectivity, and rapid response.

[0003] In recent years, people have focused more and more attention on the effective detection of chemical pollutants such as volatile organic compounds and toxic metals, because these substances seriously threaten human health and the living environment. Volatile organic compounds evaporate easily at room temperature and enter the human body through normal breathing. They have a wide range of sources, such as release from building materials, cleaning products, adhesives, coatings, and office equipment, and are difficult to eliminate. Acetone, as one of the highly volatile organic solvents, is easily absorbed by organisms. The absorbed acetone is distributed throughout the body, especially in organs with high water content, which can cause metabolic disorders and toxic side effects to organisms. From the perspective of physical properties and applications, the qualitative and quantitative detection of acetone in aqueous solutions is very important. On the other hand, hexavalent chromium ions are very important for industrial production and modern life, and their use in industries such as leather tanning, paint manufacturing, and steel manufacturing is increasing. In addition, hexavalent chromium is also one of the most common toxic heavy metal pollutants, and the anion CrO4 2– / Cr2O7 2– They are environmentally non-degradable substances that are harmful to human health. When they are enriched in the body, they can cause skin allergies, ulcers, rhinitis, lung cancer and renal failure, and can induce gene mutations when they are concentrated. So far, the existing detection methods include: ion mobility spectrometry, inductively coupled plasma, electrochemical analysis, atomic absorption spectroscopy, etc., but these methods are time-consuming, costly, and require complex pretreatment. In contrast, metal complex fluorescent probes can monitor these substances simply, quickly, accurately, and cost-effectively, so their design, synthesis, and application have been rapidly developed. Summary of the invention

[0004] The object of the present invention is to provide a three-dimensional binuclear terbium coordination polymer and a preparation method thereof, and use of the coordination polymer as a fluorescent probe for detecting acetone and hexavalent chromium ions in aqueous solution based on the above technical status.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions:

[0006] In the first aspect, the present invention provides a three-dimensional binuclear terbium coordination polymer, the molecular formula of which is [Tb2(μ3-HIA)3·2H2O] n , of which HIA 2- It is the form of 5-(hydroxymethyl)isophthalic acid carboxyl group without two protons, and n represents the degree of polymerization; its structural formula is:

[0007]

[0008] in Represents coordination bonds outside the asymmetric unit.

[0009] Furthermore, the three-dimensional binuclear terbium coordination polymer crystal belongs to the monoclinic system, the space group is C2 / c, and the unit cell parameters are α=γ=90°, β=115.0037(16)°.

[0010] Furthermore, the asymmetric unit of the three-dimensional binuclear terbium coordination polymer comprises a Tb(III) atom, a carboxyl deprotonated ligand (HIA 2- ) and one-half free H2O molecule. Each Tb 3+ The ion is coordinated with eight oxygen atoms, presenting a distorted dodecahedral {TbO8} geometry. 3+ The eight coordinated oxygen atoms come from four different COO atoms of the two ligands. - The Tb-O bond lengths range from 2.263(5) to Adjacent Tb(Ⅲ) ions are connected by ligand carboxyl groups with a distance of

[0011] In a second aspect, the present invention provides a method for preparing the three-dimensional binuclear terbium coordination polymer described in the first aspect, comprising the following steps: mixing Tb(NO3)3·6H2O and 5-(hydroxymethyl)isophthalic acid, adding a mixture of CH3CN and water, and obtaining the three-dimensional binuclear terbium coordination polymer through a hydrothermal reaction.

[0012] Furthermore, the molar ratio of Tb(NO3)3·6H2O to 5-(hydroxymethyl)isophthalic acid is 0.9:2.0 to 1.1:2.0.

[0013] Furthermore, the volume ratio of CH3CN to water in the mixture of CH3CN and water is 0.9:1.0 to 1.2:1.0.

[0014] Furthermore, the temperature of the hydrothermal reaction is 138-142° C., and the time is 71-72 hours.

[0015] In a second aspect, the present invention provides the use of the three-dimensional binuclear terbium coordination polymer described in the first aspect as a fluorescent probe material for detecting acetone small molecules and hexavalent chromium ions in aqueous solution.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The terbium coordination polymer provided by the invention is obtained under hydrothermal conditions, has a simple preparation process, and has high yield and purity. Thermogravimetric analysis shows that the structure decomposes above 324°C, and the practical temperature range is below 324°C.

[0018] The three-dimensional binuclear terbium coordination polymer provided by the present invention is constructed based on the ligand 5-(hydroxymethyl)isophthalic acid, and the fluorescence emission spectrum of the aqueous suspension of the complex is measured under room temperature. When the excitation wavelength is 247nm, under the condition of Tris-HCl buffer solution with pH=1-14, the complex has strong acid resistance. At the same time, it has high stability and strong fluorescence intensity in a wide range of medium and strong acids (pH=3-7). When acetone molecules and hexavalent chromium ions are added, the fluorescence of the complex is quenched. The complex of the present invention can be used as a fluorescent probe for efficiently detecting acetone and hexavalent chromium ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The coordination environment diagram of Tb(III) in the terbium coordination polymer of the present invention (ellipsoidality is 30%; wherein symmetry operations i=x, -y+1, z+1 / 2; ii=-x+1, -y+1, -z+1; iii=-x+1, y, -z+3 / 2; iv=-x+1 / 2, -y+3 / 2, -z+1; v=x, y, -z);

[0020] Figure 2 The X-ray powder diffraction pattern of the terbium coordination polymer of the present invention at 298K (experimental and simulation patterns);

[0021] Figure 3 is a thermogravimetric analysis diagram of the terbium coordination polymer of the present invention;

[0022] Figure 4 The fluorescence spectrum intensity diagram is after adding various organic small molecules into the aqueous solution of the terbium coordination polymer of the present invention.

[0023] Figure 5 (a) is the fluorescence spectrum of the terbium coordination polymer of the present invention when different concentrations of acetone molecules are added to the aqueous solution; (b) is the Stern-Volmer curve of I0 / I of the terbium complex aqueous suspension and acetone concentration (the inset is the linear relationship diagram of low concentration acetone).

[0024] Figure 6It is a fluorescence spectrum intensity diagram after adding various anions into the aqueous solution of the terbium coordination polymer of the present invention.

[0025] Figure 7 Different concentrations of CrO4 are added to the aqueous solution of the terbium coordination polymer of the present invention. 2- Fluorescence spectra of ions and fluorescence linear calibration curves.

[0026] Figure 8 Different concentrations of Cr2O7 are added to the aqueous solution of the terbium coordination polymer of the present invention. 2- Fluorescence spectra of ions and fluorescence linear calibration curves. DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the present invention, the present invention will be described more fully below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0028] Example 1 Preparation of Terbium Coordination Polymer

[0029] A mixture of H2HIA (39.2 mg, 0.2 mmol), Tb(NO3)3·6H2O (45.3 mg, 0.1 mmol), H2O (5.00 mL) and acetonitrile (CH3CN, 5.00 mL) was mixed in a 25 mL polytetrafluoroethylene-lined stainless steel container. The mixture was sealed and heated at 140°C for 72 hours and then cooled naturally to room temperature. The orange-yellow block crystals were collected by filtration, washed with H2O, and dried in air to obtain a three-dimensional binuclear terbium coordination polymer with a yield of 52.71% (based on Tb 3+ count).

[0030] Example 2 Determination of the crystal structure of terbium coordination polymer

[0031] The crystal structure was determined by X-ray diffraction, using a Bruker D8Venture detector with Mo-Kα rays monochromated by a graphite monochromator, scanning mode ω, and the data collection temperature was 298K. The raw data was reduced by SAINT and then corrected for absorption using SADABS. The crystal structure was solved by the SHELXL-2014 direct method. Detailed crystal determination data are shown in Table 1, and the crystal structure is shown in Figure 1 .

[0032] Table 1 Crystallographic data of terbium coordination polymers

[0033]

[0034]

[0035] Example 3 Powder diffraction analysis of phase

[0036] The X-ray powder diffraction results show that the two experimental diffraction patterns are basically consistent with the simulated patterns, indicating that the terbium coordination polymer of the present invention is a pure phase. Figure 2 .

[0037] Example 4 Thermal Stability Analysis of Terbium Coordination Polymers

[0038] Thermogravimetric analysis shows that the main structure of the coordination polymer material decomposes when the temperature is above 324°C, indicating that the terbium coordination polymer of the invention is suitable for temperatures below 324°C. Figure 3 .

[0039] Example 5 Selective recognition of acetone molecules in water by the terbium coordination polymer of the present invention

[0040] 5 mg of the coordination polymer was ultrasonically treated in 50 ml of water for 30 minutes and then allowed to settle for three days. 2 ml of the supernatant was taken and 200 μl of different organic small molecules [acetone, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), dimethyl sulfoxide (DMSO), methanol, ethanol, ethylene glycol, acetonitrile, dichloromethane] were added respectively. The fluorescence emission spectrum intensity was measured under the conditions of excitation wavelength of 247 nm and slit width of 3.5 nm, as shown in FIG. Figure 4 As shown in the figure, the complex has a unique fluorescence selectivity for acetone molecules. The detection limit of the coordination polymer was calculated to be 1.15×10 -4 M( Figure 5 ), the above experiments show that the binuclear terbium coordination polymer can be used to detect acetone molecules in aqueous solution.

[0041] Example 6 Selective recognition of anions by the terbium coordination polymer of the present invention in water

[0042] First, prepare a concentration of 1×10 -3 mol / L common anion solutions, (the anions are F - ,Cl - ,Br - ,I - ,SO4 2- ,CO3 2- ,HCO3 - ,C2O4 2- ,CH3COO - ,HPO4 2- ,H2PO4 - ,Cr2O7 2- ,CrO4 2-). 5 mg of the coordination polymer was placed in 50 ml of water and ultrasonically treated for 30 minutes, and then precipitated for three days. 2 ml of the supernatant was taken and 200 μl of different anion solutions were added respectively. Under the conditions of excitation wavelength of 247 nm and slit width of 3.5 nm, the intensity of the fluorescence emission spectrum was measured. Figure 6 As shown, the complex has 2- and CrO4 2- ions have unique fluorescence selectivity. The coordination polymer was calculated to detect Cr2O7 2- and CrO4 2- The detection limits were 2.5×10 -9 M and 6.8×10 -9 M( Figure 7 and Figure 8 ), the above experiments show that the binuclear terbium coordination polymer can be used to detect hexavalent chromium ions in aqueous solution.

[0043] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0044] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A three-dimensional binuclear terbium coordination polymer, characterized in that: The three-dimensional binuclear terbium coordination polymer crystal belongs to the monoclinic system, and the space group is C 2 / c , the unit cell parameters are a =15.1635(10) Å, b = 16.0462(10) Å ，c = 8.4393(5) Å ，α = γ = 90° ，β = 115.0037(16)º; The preparation method of the three-dimensional binuclear terbium coordination polymer comprises the following steps: mixing Tb(NO3)3·6H2O and 5-(hydroxymethyl)isophthalic acid in proportion, adding a mixed solution of CH3CN and water, and performing a hydrothermal reaction to obtain the three-dimensional binuclear terbium coordination polymer; The molar ratio of Tb(NO3)3·6H2O to 5-(hydroxymethyl)isophthalic acid is 0.9:2.0 to 1.1:2.0; The volume ratio of CH3CN to water in the mixture of CH3CN and water is 0.9:1.0~1.2:1.0; The temperature of the hydrothermal reaction is 138-142° C. and the time is 71-72 hours.

2. A method for preparing the three-dimensional binuclear terbium coordination polymer as claimed in claim 1, characterized in that: The method comprises the following steps: mixing Tb(NO3)3·6H2O and 5-(hydroxymethyl)isophthalic acid in proportion, adding a mixed solution of CH3CN and water, and performing a hydrothermal reaction to obtain the three-dimensional binuclear terbium coordination polymer; The molar ratio of Tb(NO3)3·6H2O to 5-(hydroxymethyl)isophthalic acid is 0.9:2.0 to 1.1:2.0; The volume ratio of CH3CN to water in the mixture of CH3CN and water is 0.9:1.0~1.2:1.0; The temperature of the hydrothermal reaction is 138-142° C. and the time is 71-72 hours.

3. An application of the three-dimensional binuclear terbium coordination polymer as claimed in claim 1, characterized in that: The three-dimensional binuclear terbium coordination polymer is used as a fluorescent probe material to detect acetone small molecules and hexavalent chromium ions in aqueous solution.

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