A Copper(I) Fluorescent Sensing Material, Its Preparation Method and Application

Abstract

The present invention belongs to the technical field of the development of fluorescent active substances, and particularly relates to a copper(I) fluorescent sensing material, a preparation method thereof and an application. The molecular formula of the copper(I) fluorescent sensing material is {[Cu(EIBA)]·4.6DMF}<subgt;n< / subgt>, which forms a four-connected topological network structure with copper(I) ions as connection nodes and EIBA ligands as bridging ligands bridging each other; wherein, EIBA is 4-(2-ethylimidazol-1-yl)benzoic acid, and n is a positive integer. The present invention can prepare a monovalent copper ion fluorescent sensing material by a one-pot solvothermal reaction. The preparation method has the advantages of simple process, convenient operation, high yield, good reproducibility, etc.; the fluorescence emission spectrum intensity of the copper(I) fluorescent sensing material of the present invention is strong, and it can be applied to fields such as molecular fluorescence probes and metal ion detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of the development of fluorescent active substances, and particularly relates to a copper(I) fluorescent sensing material, a preparation method thereof, and an application thereof. Background Art

[0002] The excessive emission of pollutants in the environment has become a very serious international problem. Approximately 20% of diseases are related to heavy metal ions and organic pollutants, and the excessive intake of some antibiotics will cause the body to develop drug resistance. In addition, polluting gases such as nitrogen oxides, SO2, and CO2 are the main factors for the formation of acid rain, the generation of photochemical smog, and the destruction of the ozone layer.

[0003] At present, the means for detecting environmental pollutants vary. High-performance gas-liquid chromatography, mass spectrometry, Raman spectroscopy and other detection methods mainly rely on expensive instruments. These analytical techniques have certain disadvantages, such as the need for trained professionals, high costs, and complex equipment. MOFs, as fluorescent sensing materials, have been widely favored by scientific researchers due to their advantages such as simple operation, high selectivity, and fast detection speed. There are three factors that cause MOFs to emit light. The conjugated effect generated by the organic ligand, the central metal ion, and the MOFs formed by metals with d 10 valence electrons will all cause them to emit light. Due to the characteristics of high specific surface area and pore structure of MOFs materials, they exhibit high adsorption capacity and better selectivity. Therefore, they perform excellently in the adsorption of heavy metal ions and the detection of organic pollutants and pesticides. MOFs have a detection effect on Fe 3+ , Cd 2+ , Cr 3+ , Ag + , K + , Mn 2 + , Pb 2+ . Therefore, the excessive emission of organic pollutants, heavy metal ions, and pesticides in the environment can be qualitatively and even quantitatively detected by detecting the fluorescence changes before and after their contact with organic pollutants, heavy metal ions, and pesticides. Summary of the Invention

[0004] To overcome the shortcomings and deficiencies of the prior art, the primary object of the present invention is to provide a copper(I) fluorescent sensing material.

[0005] The object of the present invention is to provide a preparation method of the above copper(I) fluorescent sensing material, aiming to overcome the problems of low yield, very low repeatability, and excessive influence of reaction conditions in the existing preparation methods of copper(I) fluorescent sensing materials.

[0006] Another object of the present invention is to provide the application of the above copper(I) fluorescent sensing material in detecting the pollution of organic solvents in the environment.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A copper(I) fluorescent sensing material, the molecular formula of the copper(I) fluorescent sensing material is {[Cu(EIBA)]·4.6DMF} n , which uses copper(I) ions as connection nodes and EIBA ligands as bridging ligands to bridge each other to form a four-connected topological network structure; wherein, EIBA is 4-(2-ethylimidazol-1-yl)benzoic acid, and n is a positive integer.

[0009] The copper(I) fluorescent sensing material is a coordination polymer crystal belonging to the hexagonal crystal system and the P6522 space group, and has a four-connected single-node network structure with the symbol (6 4 .8 2 ); wherein, the unit cell parameters are α = β = 90°, γ = 120°,

[0010] The structure of the EIBA is shown in the following formula (Ⅱ):

[0011]

[0012] Furthermore, the copper(I) fluorescent sensing material uses copper(I) as the central ion, and coordinates with two nitrogen atoms on the imidazole ring of 2 deprotonated EIBA ligands and two carboxyl oxygen atoms in 2 deprotonated EIBA ligands to form a distorted tetrahedral geometry. The copper(I) ion can be regarded as a four-connected tetrahedral node, and the EIBA ligands are used as bridging ligands to bridge each other, connecting copper(I) atoms to form a 3D porous framework structure, which can be simplified to a four-connected topological network structure. To minimize large voids and stabilize the framework structure, the potential voids formed by a single 3D network show another identical void, thus providing a 2-fold parallel interpenetrating array. When looking down along the crystallographic c-axis, it can be found that there is a large 1D channel.

[0013] A preparation method of a copper(I) fluorescent sensing material:

[0014] (1) Add copper salt and EIBA to DMF and mix. After mixing, adjust the pH of the system to 4-5, and then react at a constant temperature of 120 °C for 72-96 hours in a closed environment

[0015] (2) Cool and crystallize the reaction product, and after washing, filtering and drying the crystallization product in sequence, a copper(I) fluorescent sensing material is obtained.

[0016] The molar volume ratio of the copper salt, EIBA and DMF is 1.0 mmol: 1.0 mmol: 2 mL.

[0017] The copper salt is any one of cuprous chloride, cuprous iodide, and cuprous bromide.

[0018] The DMF is an organic solvent molecule N,N'-dimethylformamide, and its structure is shown in the following formula (I):

[0019]

[0020] In the step (1), the pH value of the system is adjusted by an alkali, where the alkali is a sodium hydroxide solution with a concentration of 0.3 - 0.8 mol / L.

[0021] The crystallization product in the step (2) is rinsed with deionized water, filtered under reduced pressure, and dried at a constant temperature of 60 °C for 2 - 4 hours.

[0022] An application of the copper(I) fluorescence sensing material as described above, the application of the material in detecting organic pollutants.

[0023] The application of the material in a fluorescence sensor for detecting organic pollutants.

[0024] The organic pollutant is nitrobenzene (NB).

[0025] Compared with the disadvantages and deficiencies of the prior art, the present invention has the following beneficial effects:

[0026] (1) The present invention can prepare a monovalent copper ion fluorescence sensing material by a one-pot solvothermal reaction. This preparation method has the advantages of simple process, convenient operation, high yield, good reproducibility, etc.;

[0027] (2) The fluorescence emission spectrum intensity of the copper(I) fluorescence sensing material of the present invention is strong, and it can be applied to fields such as molecular fluorescence probes and metal ion detection;

[0028] (3) The detection method of the copper(I) fluorescence sensing material of the present invention has the advantages of simple operation, low cost, high selectivity, fast detection speed, etc. Description of the Drawings

[0029] Figure 1 It is a single molecule diagram of the copper(I) fluorescence sensing material prepared in the embodiment of the present invention;

[0030] Figure 2 It is the three-dimensional porous framework structure of the copper(I) fluorescence sensing material prepared in the embodiment of the present invention;

[0031] Figure 3 It is a view of the double interpenetrating structure of the copper(I) fluorescence sensing material prepared in the embodiment of the present invention;

[0032] Figure 4 The copper(I) fluorescence sensing material prepared in the embodiment of the present invention has a 3D porous framework structure with 1D channels in the C-axis direction;

[0033] Figure 5 IR diagram of the copper(I) fluorescence sensing material 1 prepared in the embodiment of the present invention;

[0034] Figure 6 XRD diagram of the copper(I) fluorescence sensing material 1 prepared in the embodiment of the present invention;

[0035] Figure 7 Fluorescence spectrum diagram of the copper(I) fluorescence sensing material 1 prepared in the embodiment of the present invention;

[0036] Figure 8 Fluorescence emission intensity diagram of the copper(I) fluorescence sensing material 1 prepared in the embodiment of the present invention dispersed in 11 organic solvents;

[0037] Figure 9 Relationship diagram of the fluorescence spectrum of the copper(I) fluorescence sensing material 1 prepared in the embodiment of the present invention changing with the concentration of the organic solvent NB in methanol solvent. Detailed implementation manners

[0038] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] Example 1

[0040] (1) 0.1 mmol of cuprous chloride, 0.1 mmol of 4-(2-ethylimidazol-1-yl)benzoic acid and 2 mL of N,N'-dimethylformamide were adjusted to a pH of 4.27 with 0.3 mol . L -1 sodium hydroxide, and the mixture was subjected to a solvothermal reaction at 120 °C for 72 hours in a glass scintillation vial;

[0041] (2) The reaction product was naturally cooled and crystallized, the crystals were rinsed with deionized water, and the blue needle-like crystals were obtained by vacuum filtration. After being placed in an oven at 60 °C for 3 hours, the copper(I) fluorescence sensing material was obtained, and the yield was about 71.2%.

[0042] Example 2

[0043] (1) 0.1 mmol of cuprous chloride, 0.1 mmol of 4-(2-ethylimidazol-1-yl)benzoic acid and 2 mL of N,N'-dimethylformamide were adjusted to a pH of 4.27 with 0.3 mol . L-1 Adjust its pH to 4.73 with sodium hydroxide, and the mixture is subjected to a solvothermal reaction at 120 °C in a glass scintillation vial for 72 hours;

[0044] (2) Naturally cool the reaction product to crystallize, rinse the crystals with deionized water, and obtain blue needle-like crystals by vacuum filtration. Place them in an oven at 60 °C for 3 hours to obtain the copper(I) fluorescent sensing material, with a yield of approximately 73.5%.

[0045] Take the copper(I) fluorescent sensing material prepared in Example 1 for characterization, and the process is as follows:

[0046] (1) Crystal structure determination of the copper(I) fluorescent sensing material

[0047] Select a single crystal with a suitable size of 0.12×0.11×0.1 mm under a microscope for X-ray diffraction experiments at room temperature. Collect diffraction data on a Bruker P4 CCD single crystal diffractometer, using Mo-Kα radiation monochromatized by a graphite monochromator 3 Collect diffraction points in a scanning mode. In addition, use the SADABS program to perform absorption correction and factor correction on Lp. Use the SHELX-97 program to perform full matrix least squares refinement on all non-hydrogen atoms and their anisotropic thermal parameters. The detailed crystal determination data are shown in Table 1, and the important bond length and bond angle data are shown in Table 2. The crystal structure is as shown. The Cu(I) ion can be regarded as a four-connected tetrahedral node, and the EIBA ligand acts as a bridging ligand to bridge with the Cu(I) ion to form a 3D porous framework structure, as shown. To minimize large voids and stabilize the framework structure, the potential voids formed by a single 3D network show another identical void, thus providing a 2-fold parallel interpenetrating array, as Figure 1 shown. When observed from the crystallographic c-axis downward, a large 1D channel can be found, as Figure 2 shown. Figure 3 shown. Figure 4 shown.

[0048] Table 1 Main crystallographic data of the copper(I) fluorescent sensing material 1

[0049]

[0050] Table 2 Important bond lengths and bond angles (°)

[0051]

[0052] (1) IR spectrum characterization of the copper(I) fluorescent sensing material

[0053] Figure 5 The IR spectrum of the copper(I) fluorescent sensing material 1, and the sample infrared spectrum collection data was 400 - 4000 cm -1 , and KBr pellet pressing was used. From Figure 5 , it can be seen that the copper(I) fluorescent sensing material presented a strong and broad absorption peak at 3445 cm -1 , which was the stretching vibration peak of the O - H group, and the asymmetric and symmetric stretching vibrations of the carbonyl group were at 1608 - 1562 cm -1 .

[0054] The molecular formula of the copper(I) fluorescent sensing material 1 was {[Cu(EIBA)]·4.6DMF} n , and n was a positive integer.

[0055] (2) Phase purity characterization of the copper(I) fluorescent sensing material

[0056] Using a Bruker / D8 Advance X - ray diffractometer, the powder XRD characterization results of the copper(I) fluorescent sensing material showed its reliable phase purity, providing a guarantee for its use as a fluorescent probe to detect excessive organic pollutants, pesticides, and heavy metal ions in the environment, as Figure 6 shown.

[0057] (3) Solid fluorescence characterization of the copper(I) fluorescent sensing material

[0058] Using an Edinburgh instruments / FLS 1000 fluorescence spectrometer, the solid fluorescence properties of the copper(I) fluorescent sensing material were tested. The copper(I) fluorescent sensing material had a strong fluorescence emission peak at 412 nm with an excitation wavelength of 370 nm, and its ligand also had a strong fluorescence emission peak at 433 nm when excited at 370 nm, as Figure 7 shown.

[0059] Comparative example

[0060] (1) 0.1 mmol of cuprous chloride, 0.1 mmol of 4-(2 - ethylimidazol - 1 - yl)benzoic acid, and 2 mL of N,N’ - dimethylformamide were adjusted to a pH of 5.5 with 0.3 mol . L -1 sodium hydroxide, and the mixture was subjected to a solvothermal reaction at 120 °C in a glass scintillation vial for 72 hours;

[0061] (2) The reactants were naturally cooled to obtain a light blue solution. The reason for no crystallization was that the pH of the reaction system did not match.

[0062] Application example 1

[0063] Weigh 2.0 mg of the crystal powder of the copper(I) fluorescence sensing material prepared in Example 1 after sufficient grinding and place it separately in 10 kinds of 3 mL organic solvents. After ultrasonic treatment for half an hour and standing for one hour, take the supernatant and place it in a cuvette. At an excitation wavelength of 260 nm, measure its fluorescence emission intensity in suspensions with methanol (MeOH), ethanol (EtOH), acetonitrile (CAN), n-propanol (1-Pro), isopropanol (IPA), N,N'-dimethylacetamide (DMA), dichloromethane (CHCl2), N,N'-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), aniline, and nitrobenzene (NB) as solvents (see Figure 8 ). As can be seen from Figure 8 , the copper(I) fluorescence sensing material has the strongest fluorescence intensity in methanol solvent and the lowest fluorescence intensity in NB solvent.

[0064] Application Example 2

[0065] Take 2 mg of the crystal powder of the copper(I) fluorescence sensing material prepared in Example 1 after sufficient grinding and place it in 4 mL of methanol solvent. After ultrasonic treatment for half an hour and standing for one hour, take 3 mL of the supernatant and place it in a cuvette. At an excitation wavelength of 260 nm, add NB in different amounts (i.e., different amounts are 0 - 2.14 μL, and the concentration difference between two amounts is 0.1 - 0.2 μL) to the supernatant of the copper(I) fluorescence sensing material in sequence, and measure its corresponding fluorescence emission spectrum (see Figure 9 ). As can be seen from Figure 9 , as the concentration of NB increases, the fluorescence intensity in its supernatant gradually decreases. When the concentration of NB increases to 2.14 μL, the fluorescence intensity decreases to 5.8% of the original. At the same time, the inset shows the linear relationship between the relative fluorescence intensity and the organic solvent within a certain concentration range.

[0066] Based on further analysis of the above experimental data, the linear regression equation of the I / I0 value (I represents the fluorescence intensity of the copper(I) fluorescence sensing material in methanol solvent after adding the organic solvent; I0 represents the fluorescence intensity of the copper(I) fluorescence sensing material in methanol solvent without adding the organic solvent) of the methanol supernatant of the copper(I) fluorescence sensing material and NB is obtained, and the calculation results are shown in Table 3. As can be seen from Table 3, within the range of NB concentration from 4.0×10 -5 ~3.0×10 -4 mol / L, there is a good linear relationship between its methanol supernatant and the concentration of NB. The lowest detection limit concentration of NB is calculated to be 2.6×10 -4 mol / L by the formula LOD = 3σ / S (σ represents the blank standard deviation; S = Ksv).

[0067] Table 3 Relationship between I0 / I of Copper(I) Fluorescent Sensing Material and Concentration of Analyte in Methanol Solvent

[0068]

[0069] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A copper(I) fluorescent sensing material, characterized in that: The molecular formula of the copper(I) fluorescent sensing material is {[Cu(EIBA)]·4.6DMF} n , which uses copper(I) ions as connection nodes and EIBA ligands as bridging ligands to bridge each other to form a four-connected topological network structure; where EIBA is 4-(2-ethylimidazol-1-yl)benzoic acid, and n is a positive integer; The copper(I) fluorescent sensing material is a coordination polymer crystal belonging to the hexagonal crystal system and the P6522 space group, and has symbol (6 4 .8 2 ) of the four-connected single-node network structure; among them, the unit cell parameters are α = β = 90°, γ = 120°, 2. A preparation method of the copper(I) fluorescent sensing material according to claim 1, characterized in that: (1) Add copper salt and EIBA into DMF and mix. After mixing, adjust the pH of the system to 4-5, and then carry out a constant-temperature reaction at 120 °C for 72-96 hours in a closed environment. (2) Cool and crystallize the reaction product, and after washing, filtering and drying the crystallization product in sequence, obtain the copper(I) fluorescent sensing material.

3. The preparation method according to claim 2, characterized in that: The molar volume ratio of the copper salt, EIBA and DMF is 1.0 mmol: 1.0 mmol: 2 mL.

4. The preparation method according to claim 2, characterized in that: The copper salt is any one of cuprous chloride, cuprous iodide and cuprous bromide.

5. The preparation method according to claim 2, characterized in that: In the step (1), the pH value of the system is adjusted by an alkali, wherein the alkali is a sodium hydroxide solution with a concentration of 0.3-0.8 mol / L.

6. The preparation method according to claim 2, characterized in that: The crystallization product in the step (2) is washed with deionized water, filtered under reduced pressure and dried at 60 °C for 2-4 hours.

7. Use of the copper(I) fluorescent sensing material according to claim 1, characterized in that: The application of the material in detecting organic pollutants.

8. Use of the copper(I) fluorescent sensing material according to claim 7, characterized in that: The application of the material in a fluorescent sensor for detecting organic pollutants.

9. Use of the copper(I) fluorescent sensing material according to claim 7, characterized in that: The organic pollutant is nitrobenzene (NB).

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