Zinc complex crystal material for fluorescence detection of Cr (III) ions as well as preparation method and application of zinc complex crystal material

Abstract

The invention discloses a zinc complex crystal material for fluorescence detection of Cr (III) ions as well as a preparation method and application of the zinc complex crystal material. The simple formula of the composition structure of the crystal material is [Zn4 (L) 3 (OH) (EtO) (H2O) (DMF) 2] n.2DMF, the chemical formula is C107H108N4O19Zn4, the crystal material belongs to a monoclinic system, the space group is P21 / C, the cell parameters alpha are equal to 90 degrees, the cell parameters beta are equal to 106.271 (12) degrees, and the cell parameters gamma are equal to 90 degrees. The crystal material has a clear space structure and an accurate molecular formula, can efficiently and rapidly detect Cr < 3 + > ions, and has a wide application prospect as a fluorescence sensor. The technology has the advantages of simplicity in operation, low cost, stable performance and the like.

Description

Technical Field

[0001] This invention belongs to the fields of crystal material chemistry and fluorescence sensing materials, specifically relating to a zinc complex crystal material for fluorescence detection of Cr(III) ions, its preparation method, and its applications. Background Technology

[0002] Metal coordination compound crystal materials, also known as metal-organic frameworks (MOFs), are organic-inorganic hybrid materials that form intramolecular pores through the self-assembly of organic ligands and metal ions or clusters via coordination bonds. MOF materials have been widely used in gas adsorption and separation, catalysis, and ion detection. Heavy metals are ubiquitous in human life. Although some heavy metals, such as iron, chromium, and manganese, are essential trace elements for life, like most other non-living heavy metals, they can cause significant harm to the body when their concentration exceeds a certain level. Therefore, the detection of metal ions in water bodies is crucial for the timely treatment of polluted water.

[0003] MOF (Metal-Organic Fluorescent Probes) are a special type of sensor that has attracted attention in analytical sensing and optical imaging due to their high sensitivity, fast response time, and simple technology. Furthermore, fluorescence-based compounds possess strong electronic conjugation, which translates to large electron delocalization and high fluorescence efficiency. In recent years, anthraquinones, pyrene derivatives, biphenyls, styrene, imidazoles, and polyurethanes have become the main raw materials for fluorescent probes. Summary of the Invention

[0004] This invention addresses the problems existing in the prior art by providing a zinc complex crystal material for the fluorescence detection of Cr(III) ions, its preparation method, and its applications. This invention synthesizes a zinc complex crystal material using a fluorenylcarboxylic acid ligand and a zinc salt, enabling rapid detection of chromium ions via fluorescence emission spectroscopy.

[0005] The technical solution adopted by this invention to solve the above-mentioned technical problems is as follows: the simplified structural formula of the zinc complex crystal material is [Zn4(L)3(OH)(EtO)(H2O)(DMF)2]. n ·2DMF(L 2- To remove two protons from 3,3'-(9,9-diethyl-9H-fluorene-2,7-diyl)dibenzoate, DMF = N,N'-dimethylformamide, EtO - (For an ethanol molecule that has lost one proton), this crystal belongs to the monoclinic crystal system, space group P21 / C, and chemical formula C. 107 H 108 N4O19 Zn4, chemical formula weight 2015.65, unit cell parameters α = 90°, β = 106.271(12)°, γ = 90°; the asymmetric structural unit of the crystal includes four Zn(II) ions and three L ions. 2- Ligand, two coordinated DMF molecules, one coordinated water molecule, and one coordinated hydroxyl group (OH) - An ethanol molecule that has lost one proton (EtO) - ) and two free DMF molecules ( Figure 1 The four zinc ions (Zn1 to Zn4) in the asymmetric structural unit exhibit different coordination configurations: Zn(1) adopts a five-coordinate geometry, with one oxygen atom coming from a hydroxyl group, one oxygen atom coming from an ethanol molecule, and three oxygen atoms coming from L. 2- The carboxyl group of the ligand; Zn(2) has a tetrahedral coordination configuration, with one oxygen atom coming from the hydroxyl group and three oxygen atoms coming from the L group. 2- The carboxyl group of the ligand; Zn(3) exhibits a six-coordinate octahedral configuration, with one oxygen atom from an ethanol molecule, one oxygen atom from a DMF molecule, one oxygen atom from a coordinated water molecule, and three oxygen atoms from L. 2- The ligand carboxyl group; Zn(4) exhibits a five-coordinate geometry, with one oxygen atom derived from the hydroxyl group of the water molecule, one oxygen atom from the ethanol molecule, and three oxygen atoms from L. 2- The ligand carboxyl group; through carboxyl bridging, μ3-OH bridging, and μ3-OCH2CH3 bridging of Zn(II) ions, a unique tetranuclear cluster structure secondary unit Zn4O is formed. 16 ( Figure 2 The shortest distance between Zn(II) and Zn(II) in the secondary unit is... The secondary unit uses ligand L 2- The bridges connect to form a one-dimensional chain structure. Figure 3 Between the chains, a three-dimensional stacked structure is formed through the interaction of hydrogen bonds and intermolecular forces. Figure 4 ).

[0006] The present invention also provides a method for preparing the crystal material, the method comprising the following steps:

[0007] A certain amount of ligand H2L and zinc salt were weighed and placed in a glass bottle. The solution was dissolved by stirring in a mixed solution of N,N-dimethylformamide (DMF), ethanol and distilled water. The bottle containing the solution was heated at 75-95°C for 48-72 hours and then cooled to room temperature to obtain colorless and transparent blocky crystals, which is the zinc complex crystal material mentioned above.

[0008] The zinc salt is one or more of Zn(NO3)2·6H2O, Zn(CH3COO)2·2H2O, and ZnSO4·7H2O;

[0009] The molar ratio of the ligand H2L to the zinc salt is 1:2;

[0010] The ligand H2L has the English name 3,3'-(9,9-diethyl-9H-fluorene-2,7-diyl)dibenzoic acid and the molecular formula C2. 31 H 26 O4, with a molecular weight of 462.55, has the structural formula shown in formula (Ⅰ):

[0011]

[0012] All substances or solvents participating in the reaction are chemically pure.

[0013] The present invention also provides the use of the zinc complex crystal material, which, as a fluorescent detection crystal material, can efficiently and rapidly detect chromium ions and has broad application prospects as a fluorescent sensor.

[0014] Compared with the prior art, the present invention is characterized by:

[0015] A zinc complex crystalline material was synthesized using a solvothermal method via a mixed ligand approach. This crystalline material exhibits specific composition, structure, and fluorescence response properties. The fluorescence emission properties of this crystalline material are influenced by the trivalent metal Cr. 3+ The ions exhibit highly sensitive and selective responses in Cr 3+ When present, the crystalline material exhibits a specific fluorescence "on" reaction.

[0016] Fluorene is a rigid planar compound consisting of a five-membered ring connecting two benzene rings, and is a fluorescent group with strong fluorescence. The ligand L used in this invention has a fluorene group and a unique spatial structure, which determines that the prepared crystal material has high stability, specific fluorescence properties, and unique fluorescence response to specific metal ions, making the prepared crystal material a promising candidate for use as a fluorescent detection reagent or as a fluorescent sensor. Attached Figure Description

[0017] Figure 1 The asymmetric basic structural unit of the zinc complex crystal material described in this invention is represented by hydrogen atoms, which are ignored for clarity.

[0018] Figure 2 Zn4O is the tetranuclear cluster secondary unit in the zinc complex crystal material described in this invention. 16To make them clearly visible, hydrogen atoms are ignored;

[0019] Figure 3 The zinc complex crystal material described in this invention has a one-dimensional chain structure along the a-axis direction. For clarity, hydrogen atoms are ignored.

[0020] Figure 4 The three-dimensional stacked structure of the zinc complex crystal material described in this invention along the a-axis direction is shown. For clarity, hydrogen atoms are ignored.

[0021] Figure 5 Thermogravimetric spectrum of the zinc complex crystal material described in this invention;

[0022] Figure 6 This is a fluorescence response diagram of the zinc complex crystal material described in this invention in the presence of different metal ions;

[0023] Figure 7 This is a fluorescence response anti-interference test image of the zinc complex crystal material described in this invention, showing a comparison of the fluorescence intensity of the crystal material under different cation interferences with and without Cr(III) ions. The probe is a zinc complex crystal suspension, and the interfering ion is K. + Na + Ag + Co 2+ ,Ba 2+ Cu 2+ Ni 2 +,Zn 2+ Cd 2 +,Mg 2+ ,Pb 2 +;

[0024] Figure 8 This is a sensitivity test diagram of the zinc complex crystal of the present invention. Figure 8 Part (a) in the figure shows the fluorescence intensity spectrum of the crystal material with different concentrations of chromium ions. Figure 8 Part (b) in the figure shows the linear fitting curves of the crystal material under different concentrations of chromium ions. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the embodiments.

[0026] Example 1:

[0027] Zn(NO3)2·6H2O (5.95 mg, 0.02 mmol) and H2L (4.63 mg, 0.01 mmol) were placed in 5 mL glass bottles and dissolved in a mixed solution of N,N-dimethylformamide (DMF) (1.5 mL), ethanol (1 mL), and distilled water (1 mL) by stirring. The small bottle containing the solution was heated at 90 °C for 48 hours and then cooled to room temperature to obtain colorless and transparent blocky crystals.

[0028] Example 2:

[0029] Zinc acetate dihydrate Zn(CH3COO)2·2H2O (2.20 mg, 0.02 mmol) and H2L (4.63 mg, 0.01 mmol) were placed in 5 mL glass bottles respectively and dissolved in a mixed solution of DMF (1.5 mL), ethanol (1 mL), and distilled water (1 mL) by stirring. The resulting solution was heated at 75 °C for 72 hours and then cooled to room temperature to obtain colorless and transparent blocky crystals.

[0030] Example 3:

[0031] ZnSO4·7H2O (5.76 mg, 0.02 mmol) and H2L (4.63 mg, 0.01 mmol) were placed in 5 mL glass bottles respectively, and dissolved in a mixed solution of DMF (1.5 mL), anhydrous ethanol (1 mL), and distilled water (1 mL) by stirring. The resulting solution was heated at 95 °C for 60 hours and then cooled to room temperature to obtain colorless and transparent blocky crystals.

[0032] The colorless, transparent, blocky crystals prepared in Example 1 were subjected to single-crystal X-ray diffraction analysis. Crystals of suitable size and regular shape were selected at room temperature and fixed to the test needle with epoxy resin. The test needle was then placed on a Rigaku Oxford XtaLAB PRO diffractometer, and monochromatic MoKα graphite X-rays were used. The samples were tested, and data were acquired using CrysAlis Pro-Agilent software. Diffraction points were screened, lattice type was determined, and absorption correction and data restoration were performed. The crystal structure was solved directly using the ShelXS program, and anisotropic refinement was performed using ShelXL. 2The structure was refined and corrected using the full matrix least squares method. The coordinates of non-hydrogen atoms were gradually determined and anisotropically refined through Fourier peak synthesis. Hydrogen atoms were obtained through theoretical hydrogenation, and all hydrogen atoms underwent isotropic refinement. X-ray single-crystal diffraction analysis showed that the structural formula of the prepared zinc complex crystal material was [Zn₄(L)₃(OH)(EtO)(H₂O)(DMF)₂]. n ·2DMF(L 2- To remove two protons from 3,3'-(9,9-diethyl-9H-fluorene-2,7-diyl)dibenzoate, DMF = N,N'-dimethylformamide, EtO - (For an ethanol molecule that has lost one proton), this crystal belongs to the monoclinic crystal system, space group P21 / C, and chemical formula C. 107 H 108 N4O 19 Zn4, chemical formula weight 2015.65, unit cell parameters α = 90°, β = 106.271(12)°, γ = 90°; the asymmetric structural unit of the crystal includes four Zn(II) ions and three L ions. 2- Ligand, two coordinated DMF molecules, one coordinated water molecule, and one coordinated hydroxyl group (OH) - An ethanol molecule that has lost one proton (EtO) - ) and two free DMF molecules ( Figure 1 The four zinc ions (Zn1 to Zn4) in the asymmetric structural unit exhibit different coordination configurations: Zn(1) adopts a five-coordinate geometry, with one oxygen atom coming from a hydroxyl group, one oxygen atom coming from an ethanol molecule, and three oxygen atoms coming from L. 2- The carboxyl group of the ligand; Zn(2) has a tetrahedral coordination configuration, with one oxygen atom coming from the hydroxyl group and three oxygen atoms coming from the L group. 2- The carboxyl group of the ligand; Zn(3) exhibits a six-coordinate octahedral configuration, with one oxygen atom from an ethanol molecule, one oxygen atom from a DMF molecule, one oxygen atom from a coordinated water molecule, and three oxygen atoms from L. 2- The ligand carboxyl group; Zn(4) exhibits a five-coordinate geometry, with one oxygen atom derived from the hydroxyl group of the water molecule, one oxygen atom from the ethanol molecule, and three oxygen atoms from L. 2- The ligand carboxyl group; through carboxyl bridging, μ3-OH bridging, and μ3-OCH2CH3 bridging of Zn(II) ions, a unique tetranuclear cluster structure secondary unit Zn4O is formed. 16 ( Figure 2 The shortest distance between Zn(II) and Zn(II) in the secondary unit is... Secondary units are connected via ligand L. 2-The bridges connect to form a one-dimensional chain structure. Figure 3 Between the chains, a three-dimensional stacked structure is formed through the interaction of hydrogen bonds and intermolecular forces. Figure 4 ).

[0033] The zinc complex crystal material prepared in Example 1 above was subjected to thermogravimetric analysis. Figure 5 The results showed that the framework of the prepared crystal material remained stable at 400℃, indicating that the crystal has good thermal stability.

[0034] Fluorescence detection analysis. 10 mg of the crystals prepared in Example 1 was dissolved in 50 mL of deionized water to obtain a suspension with a concentration of 100 μM; subsequently, 200 μL of a solution of different metal cations M(NO3) was added. n (Mn n+ =K + Na + Ag + Co 2+ Ba 2+ Cu 2+ Ni 2+ Zn 2+ Cd 2+ Mg 2+ Pb 2+ Cr 3+ The concentration of each ion is 10⁻⁶. 4 M) was added to 1800 μL of crystal suspension, and then fluorescence analysis was performed, recording the fluorescence spectrum; the test results showed that when Cr was present in the prepared crystal material suspension... 3+ When ions were applied, the tested fluorescence intensity was significantly enhanced, increasing by approximately 2.3 times, indicating that the prepared crystal material exhibits good fluorescence response to Cr. 3+ Ions possess specific fluorescence response properties ( Figure 6 ).

[0035] Anti-interference test Figure 7 In real-world aquatic environments, interference resistance testing is required to assess the selectivity of material detection. + Na + Ag + Co 2+ Ba 2+ Cu 2+ Ni 2+ Zn 2+ Cd 2+ Mg 2+ Pb 2+ Selected as the interfering ion; test results show that, under the condition of the presence of interfering ions, Cr 3+The fluorescence enhancement remains significant, indicating that the crystal material (i.e., the crystal material prepared in Example 1) has high selectivity for chromium ions. This crystal material, as a fluorescence sensor, can selectively detect chromium ions in complex environments.

[0036] The sensitivity of the zinc complex crystal material (i.e., the crystal material prepared in Example 1) was tested using quantitative fluorescence titration. Figure 8 Test results show that with Cr 3+ With increasing concentration, the fluorescence absorption intensity increased significantly. In the low concentration range, the fluorescence intensity showed a good linear relationship with the ion concentration. The Cr... 3+ The detection limit was 4.39 μM. The test results confirmed that this crystalline material exhibits good adhesion to Cr. 3+ Ion recognition has high sensitivity.

Claims

1. A zinc complex crystal material for fluorescence detection of Cr(III) ions, characterized in that, The simplified structural formula of the zinc complex crystal material is [Zn4(L)3(OH)(EtO)(H2O)(DMF)2]. n ·2DMF, this crystal belongs to the monoclinic crystal system, space group P21 / C, and chemical formula C. 107 H 108 N4O 19 Zn4, chemical formula weight 2015.65, unit cell parameters α = 90°, β = 106.271(12)°, γ = 90°; the asymmetric structural unit of the crystal includes four Zn(II) ions and three L ions. 2- The structure consists of a ligand, two coordinated DMF molecules, one coordinated water molecule, one coordinated hydroxyl group, one ethanol molecule that has lost a proton, and two free DMF molecules. The four zinc ions Zn1 to Zn4 in the asymmetric structural unit exhibit different coordination configurations: Zn(1) adopts a five-coordinate geometry, with one oxygen atom from the hydroxyl group, one oxygen atom from the ethanol molecule, and three oxygen atoms from the L group. 2- The carboxyl group of the ligand; Zn(2) has a tetrahedral coordination configuration, with one oxygen atom coming from the hydroxyl group and three oxygen atoms coming from the L group. 2- The carboxyl group of the ligand; Zn(3) exhibits a six-coordinate octahedral configuration, with one oxygen atom from an ethanol molecule, one oxygen atom from a DMF molecule, one oxygen atom from a coordinated water molecule, and three oxygen atoms from L. 2- The ligand carboxyl group; Zn(4) exhibits a five-coordinate geometry, with one oxygen atom derived from the hydroxyl group of the water molecule, one oxygen atom from the ethanol molecule, and three oxygen atoms from L. 2- The ligand carboxyl group; through carboxyl bridging, μ3-OH bridging, and μ3-OCH2CH3 bridging of Zn(II) ions, a unique tetranuclear cluster structure secondary unit Zn4O is formed. 16 The shortest distance between Zn(II) and Zn(II) in the secondary unit is The secondary unit uses ligand L 2- The bridging links form a one-dimensional chain structure; between the chains, through the interaction of hydrogen bonds and intermolecular forces, a three-dimensional stacked structure is formed. The DMF is N,N'-dimethylformamide; the EtO - An ethanol molecule that has lost one proton; The ligand L is H2L with two protons removed. H2L's English name is 3,3'-(9,9-diethyl-9H-fluorene-2,7-diyl)dibenzoic acid, and its molecular formula is C2. 31 H 26 O4, with a molecular weight of 462.55, has the structural formula shown in formula (Ⅰ):

2. A method for preparing a zinc complex crystal material for fluorescence detection of Cr(III) ions as described in claim 1, characterized in that, The preparation method includes the following steps: A certain amount of ligand H2L and zinc salt were weighed and placed in a glass bottle. They were dissolved by stirring in a mixed solution of DMF, ethanol and distilled water to obtain a solution. The bottle containing the solution was heated at 75-95°C for 48-72 hours and then cooled to room temperature to obtain anhydrous transparent block crystals, which is the zinc complex crystal material described above. The zinc salt is one or more of Zn(NO3)2·6H2O, Zn(CH3COO)2·2H2O and ZnSO4·7H2O; The molar ratio of the ligand H2L to the zinc salt is 1:

2.

3. The use of the zinc complex crystal material according to claim 1 or the zinc complex crystal material prepared by the preparation method according to claim 2, characterized in that, This zinc complex crystal material, when used for fluorescence detection, can efficiently and rapidly detect Cr. 3+ Ions, which have applications as fluorescence sensors.

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