CN114591512A - Functionalized zirconium-based metal organic cage and preparation method and application thereof - Google Patents
Functionalized zirconium-based metal organic cage and preparation method and application thereof Download PDFInfo
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Abstract
The invention provides a functionalized zirconium-based metal organic cage and a preparation method and application thereof. The preparation method of the functionalized zirconium-based metal organic cage comprises the following steps: s1: dissolving (S, S) -2, 5-bis- (2-hydroxypropyl sulfanyl) -terephthalic acid and zirconium salt in an organic solvent to obtain a mixture; s2: carrying out a solvothermal reaction on the mixture to obtain a reaction mixture; s3: and cooling, crystallizing, washing and solvent exchanging the reaction mixture to obtain the functionalized zirconium-based metal organic cage. The functionalized zirconium-based metal organic cage is simple in preparation method, good in stability, high in detection efficiency, high in sensitivity and strong in anti-interference performance, can realize specific identification of various environmental pollutants including sulfonamides, nitrofurans and toxic heavy metals under different concentrations, and has good universality.
Description
Technical Field
The invention relates to the technical field of metal organic cages, in particular to a functionalized zirconium-based metal organic cage and a preparation method and application thereof.
Background
Antibiotics and toxic heavy metal species are widely used in different industries such as clinical treatment, aquaculture, leather manufacturing, electroplating and the like. However, antibiotics remaining in rivers, lakes, groundwater, and soil enter human bodies through food chains, and toxic heavy metal species, which are mainly represented by dichromate, are easily dissolved in water and are listed as carcinogens due to their high toxicity. Therefore, in the face of the potential threat of antibiotics and toxic heavy metals to the environment and human life health, the development of a convenient, reliable and high-selectivity analysis and detection method is urgently needed.
At present, among the feasible detection technologies, the fluorescence sensing technology has become a promising method for detecting antibiotics and toxic heavy metals due to the advantages of high sensitivity, easy visualization, simple operation, fast sensing response, low cost and the like. Metal-organic cages (MOCs) are discrete molecular structures formed by coordinated self-assembly of organic ligands and metal ions or clusters, and are another rapidly developing porous material following metal-organic frameworks (MOFs). MOCs have permanent porosity, suitable cavity size, good dispersion, and abundant forms of luminescence (including ligand-centered luminescence, metal-centered luminescence, charge transfer luminescence, guest-induced luminescence, etc.). In addition, the permanent porosity of the MOCs also allows reversible absorption and release of analytes, ensuring the regeneration and reuse of MOCs. These all provide theoretical basis for MOCs as fluorescent probe to be applied to detecting environmental pollutants.
Although MOCs have attracted research attention in adsorption, catalysis, membranes, gas separation, biopharmaceuticals, etc., there are still few reports in the field of fluorescence detection of environmental pollutants. In particular, the conventional fluorescence sensing mode requires a single fluorescent probe to identify one antibiotic, and it is difficult to selectively identify multiple antibiotics simultaneously using one probe. Therefore, there is a need to develop a method capable of selectively detecting a variety of environmental pollutants.
In view of this, the invention is particularly proposed.
Disclosure of Invention
The invention aims to provide a functionalized zirconium-based metal organic cage and a preparation method and application thereof, and the functionalized zirconium-based metal organic cage can realize specific identification of various environmental pollutants including sulfonamides, nitrofurans and toxic heavy metals under different concentrations.
The invention provides a preparation method of a functionalized zirconium-based metal organic cage, which comprises the following steps:
s1: dissolving (S, S) -2, 5-bis- (2-hydroxypropyl sulfanyl) -terephthalic acid and zirconium salt in an organic solvent to obtain a mixture;
s2: carrying out a solvothermal reaction on the mixture to obtain a reaction mixture;
s3: and cooling, crystallizing, washing and exchanging a solvent for the reaction mixture to obtain the functional zirconium-based metal organic cages (Zr-MOCs for short).
Specifically, step S1 may include: adding (S, S) -2, 5-bis- (2-hydroxypropyl sulfanyl) -terephthalic acid and zirconium salt into an organic solvent, performing ultrasonic treatment until the solution is completely dissolved, adding deionized water, and performing continuous ultrasonic treatment until the solution is clear to obtain a mixture.
The zirconium salt used in the present invention is not particularly limited, and for example, zirconocene dichloride (Cp)2ZrCl2) Etc.; in particular, in step S1, the molar ratio of (S, S) -2, 5-bis- (2-hydroxypropylsulfanyl) -terephthalic acid to zirconium salt may be 1: (1.5-2.5), preferably 1: 2; the organic solvent used may be N, N-Dimethylformamide (DMF) or N, N-Dimethylacetamide (DMA), preferably DMA; in dissolving, the volume ratio of the organic solvent to the deionized water may be 1: (1.5-2.5), preferably 1: 2; further, the ultrasound conditions may be: the ultrasonic power is 200-300w, preferably 250 w; the ultrasonic treatment time is 10-15 min.
In step S2 of the present invention, the reaction temperature may be 60 to 65 ℃, preferably 60 ℃; the reaction time may be 10-12h, preferably 10 h.
In step S3 of the present invention, the cooling is specifically cooling to room temperature in air; the washing can be centrifugal washing 2-4 times, such as 3 times, by using N, N-dimethylformamide or N, N-dimethylacetamide, the centrifugal rotation speed during the centrifugal washing can be 8000-10000rpm, and the centrifugal time can be 2-3 min; the solvent exchange may comprise soaking the crystals with dichloromethane or acetone, preferably dichloromethane, for a solvent exchange time of 2-4 days, and the solvent exchange may be performed 2-4 times a day.
In one embodiment, the method for preparing a functionalized zirconium-based metal organic cage according to the present invention may comprise the following steps:
1) taking certain amount of (S, S) -2, 5-bis- (2-hydroxypropyl sulfanyl) -terephthalic acid and zirconocene dichloride (Cp)2ZrCl2) Dissolving in N, N-Dimethylformamide (DMF) or N, N-Dimethylacetamide (DMA), and performing ultrasonic treatment until the solution is completely dissolved;
2) dropwise adding a proper amount of deionized water into the solution obtained in the step 1), and carrying out ultrasonic treatment until the mixture is in a clear state;
3) the preparation by a solvothermal method comprises the following steps: transferring the mixture obtained in the step 2) into a heat-resistant container, sealing, placing in a preheated oven, and heating and reacting at 60-65 ℃ for 10-12 h;
4) crystallization under static conditions: cooling the reaction mixture obtained in the step 3) to room temperature in the air to obtain yellow cubic crystals;
5) solvent exchange: washing the crystals obtained in the step 4) with DMF or DMA by centrifugation for 2-4 times, and soaking the crystals with Dichloromethane (DCM) or acetone for solvent exchange.
In the present invention, the preparation method of (S, S) -2, 5-bis- (2-hydroxypropylsulfanyl) -terephthalic acid may comprise:
A) mixing 2, 5-dimercapto-1, 4-phthalic acid and methanol, adding concentrated H under stirring2SO4Reacting, adding deionized water into the reaction mixture for precipitation, filtering, washing and drying to obtain 2, 5-dimercapto dimethyl terephthalate;
B) dissolving dimethyl 2, 5-dimercaptoterephthalate, triethylamine and S-epoxypropane in absolute ethyl alcohol under a protective atmosphere, stirring overnight at room temperature, and performing rotary evaporation and purification to obtain (S, S) -dimethyl 2, 5-bis- (2-hydroxypropyl sulfanyl) -terephthalate;
C) adding NaOH solution into (S, S) -2, 5-bis- (2-hydroxypropyl sulfanyl) -terephthalic acid dimethyl ester, stirring and refluxing overnight, adding methanol into the reaction mixture, then adding concentrated HCl under stirring to adjust the pH value to be lower than 2, adding deionized water after rotary evaporation, filtering and washing to obtain (S, S) -2, 5-bis- (2-hydroxypropyl sulfanyl) -terephthalic acid.
Specifically, in the step A), the reaction temperature is 75-85 ℃, and the reaction time is 46-50 h; 2, 5-dimercapto-1, 4-phthalic acid, methanol and concentrated H2SO4The dosage ratio of the components is 1 g: (70-90) mL: (0.8-1.2) mL; in the step B), the dosage proportion of the 2, 5-dimercaptodimethyl terephthalate, the triethylamine and the S-epoxypropane is 1: (1.0-1.3) mL: (0.5-0.8) g; in the step C), the temperature of stirring reflux is 75-85 ℃, the NaOH solution is 8-12% of NaOH methanol solution, and the dosage ratio of (S, S) -2, 5-bis- (2-hydroxypropyl sulfanyl) -dimethyl terephthalate to the NaOH solution is 1 g: (20-30) mL.
The invention also provides a functionalized zirconium-based metal organic cage which is prepared according to the preparation method.
The three-dimensional structure of the crystal of the functionalized zirconium-based metal organic cage of the invention is shown in figure 1.
The invention also provides the application of the functionalized zirconium-based metal organic cage in the detection of environmental pollutants; specifically, the environmental pollutants include dichromate (Cr)2O7 2-) At least one of Sulfamethazine (SMZ), Carbamazepine (CBZ), Nitrofurantoin (NFT), Nitrofurazone (NFZ), p-nitrophenol (4-NP), Diniconazole (DTZ), florfenicol (FFC), and Thiamphenicol (THI).
The invention also provides an environmental pollutant detection method, which comprises the following steps: preparing the functional zirconium-based metal organic cage into Zr-MOCs suspension, and then carrying out fluorescence detection on environmental pollutants by adopting the Zr-MOCs suspension; in particular, the concentration of the Zr-MOCs suspension may be 10-9mol/L to 10-4mol/L; the concentration of the environmental pollutants is more than 0.747 mu M.
In particular, a concentration of 10 may be used-6Detection of Sulfadimidine (SMZ) and dichromate (C) by mol/L Zr-MOCs suspensionr2O7 2-) (ii) a A concentration of 10 may be used-9The suspension of Zr-MOCs in mol/L is used for detecting Nitrofurantoin (NFT) and Nitrofurazone (NFZ).
In one embodiment, the method for detecting environmental pollutants of the present invention comprises the following steps:
the method comprises the following steps: and (3) performing fluorescence spectrum test on Zr-MOCs:
testing the fluorescence properties of the Zr-MOCs dispersed in a series of different solvents, and selecting the solvent with the strongest relative emission intensity and good stability of the Zr-MOCs in the solvent for subsequent fluorescence testing; then, preparing ground Zr-MOCs powder materials, preparing Zr-MOCs suspension liquid with different concentrations, and testing the solid and liquid luminescence characteristics of the Zr-MOCs at room temperature;
step two, performing fluorescence detection on environmental pollutants by Zr-MOCs:
selecting two representative groups of Zr-MOCs suspensions (10) with different concentrations, wherein the two representative groups of Zr-MOCs suspensions have large difference between excitation spectrum and emission spectrum and strong relative emission intensity-6mol/L and 10-9mol/L) of the raw materials, and nine environmental pollutants of 0.1mM, including dichromate (Cr) are added in groups2O7 2-) Sulfadimethy pyrimidine (SMZ), Carbamazepine (CBZ), Nitrofurantoin (NFT), Nitrofurazone (NFZ), p-nitrophenol (4-NP), dinaphthyl imidazole (DTZ), florfenicol (FFC), Thiamphenicol (THI), and testing the emission spectrum after 2-3 minutes of ultrasound;
step three, testing the sensitivity of the Zr-MOCs:
performing further fluorescence titration test on the environmental pollutants with the obvious quenching effect in the second step, fitting a Stern-Volme equation, and calculating fluorescence quenching constants (Ksv) and detection Limits (LOD) of the Zr-MOCs on the analytes so as to represent the detection sensitivity of the Zr-MOCs;
step four, selective testing of Zr-MOCs:
adding the environmental pollutants with the obvious quenching effect in the second step into Zr-MOCs suspension containing other coexisting pollutants, and further detecting the emission intensity of the obtained mixed solution to represent the anti-interference performance of the Zr-MOCs;
step five, testing the cycling stability of the Zr-MOCs:
centrifuging the Zr-MOCs by using DMF (dimethyl formamide) and DCM (DCM) for 3 times, drying and grinding, preparing a Zr-MOCs suspension again, testing the emission spectrum of the environmental pollutants with remarkable quenching effects in the second step, and verifying the repeatability of the Zr-MOCs; in addition, powder X-ray diffraction (PXRD) patterns of the Zr-MOCs after 5 cycles were tested to characterize the structural stability of the Zr-MOCs after cycles.
Specifically, in the first step, the Zr-MOCs concentration in different solvents is 10-6mol/L, in fluorescence spectrum test, the excitation wavelength is 299nm, and the slit width is 5 nm.
In the fluorescence titration test of the third step, the concentration of the analyte is 0.007-0.099 mM; in addition, the Zr-MOCs suspension had a concentration of 10-6In the mol/L test group, during fluorescence spectrum test, the excitation wavelength is 288nm, the maximum emission wavelength of an emission spectrum is 490nm, the slit width is 1.5nm, and Ksv and LOD are calculated by using the fluorescence intensity at the 490nm wavelength; the Zr-MOCs suspension concentration is 10-9And in the mol/L test group, during fluorescence spectrum test, the excitation wavelength is 362nm, the maximum emission wavelength of an emission spectrum is 413nm and 436nm, the slit width is 1.5nm, and the Ksv and LOD are calculated by using the fluorescence intensity at the wavelength of 436 nm.
In addition, the solvents used in steps one to five are all N, N-Dimethylformamide (DMF); the concentration of the analytes in the fourth step is 0.1 mM; and the analyte in the fifth step is selected from Sulfamethazine (SMZ).
The implementation of the invention has at least the following advantages:
1. the preparation method of the functional zirconium-based metal organic cages (Zr-MOCs) is simple, good in stability, high in detection efficiency, high in sensitivity, strong in anti-interference performance and practical and generalizable;
2. the functionalized zirconium-based metal organic cages (Zr-MOCs) can realize specific identification of various environmental pollutants including sulfonamides, nitrofurans and toxic heavy metals under different concentrations, and have universality in detection;
3. the functionalized zirconium-based metal organic cages (Zr-MOCs) are combined with the luminous characteristics of ligands and the topological structures of the metal-organic cages, and combined with a fluorescence analysis technology, the excitation wavelength/emission wavelength of the functionalized zirconium-based metal organic cages can be changed by adjusting the concentration of the same material, so that the functionalized zirconium-based metal organic cages (Zr-MOCs) can be used as a fluorescence probe to selectively detect various environmental pollutants.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a crystal three-dimensional structure of functionalized zirconium-based metal organic cages (Zr-MOCs) prepared in example 1;
FIG. 2 is a map of Zr-MOCs powder prepared in example 1; wherein: a is an X-ray diffraction spectrum; b is an infrared spectrogram;
FIG. 3 is a graph showing fluorescence emission spectra (excitation wavelength 299nm) of Zr-MOCs prepared in example 1 dispersed in various solvents;
FIG. 4 is a graph of DMF suspensions of varying concentrations of Zr-MOCs; wherein: a is excitation spectrum; b is an emission spectrum;
FIG. 5 is the fluorescence emission spectra of DMF suspensions of Zr-MOCs at different concentrations for different contaminants (0.1 mM); wherein: a is 10-6DMF suspension of mol/L Zr-MOCs (excitation wavelength 288 nm); b is 10-9DMF suspension of Zr-MOCs in mol/L (excitation wavelength 362 nm);
FIG. 6 is 10-6Spectra of mol/L DMF suspensions of Zr-MOCs (excitation wavelength 288nm) at different concentrations of SMZ titration; wherein: a is fluorescence emission spectrum; b is a Stern-Volmer graph;
FIG. 7 is 10-9Plot of the fluorescence intensity of mol/L of a DMF suspension of Zr-MOCs (excitation wavelength 362nm) at the addition of 0.1mM of different analytes and the addition of a mixture of 0.1mM NFT and 0.1mM of competing analytes;
FIG. 8 is a graph of cycle stability test fluorescence intensity for Zr-MOCs prepared in example 1.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms also include the plural forms unless the context clearly dictates otherwise, and further, it is understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of the stated features, steps, operations, devices, components, and/or combinations thereof.
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
EXAMPLE 1 preparation of Zr-MOCs
The functionalized zirconium-based metal organic cages (Zr-MOCs) of this example use (S, S) -2, 5-bis- (2-hydroxypropylsulfanyl) -terephthalic acid as a ligand, the ligand being coupled with zirconocene dichloride (Cp)2ZrCl2) Coordination self-assembly; the preparation method comprises the following steps:
firstly, preparing ligand (S, S) -2, 5-bis- (2-hydroxypropyl sulfanyl) -terephthalic acid
1) Preparation of the Compound dimethyl 2, 5-dimercaptoterephthalate (intermediate 1)
A250 mL round bottom flask was taken, 2, 5-dimercapto-1, 4-phthalic acid (DMBD, 1g, 4.34mmol), methanol (80mL) were added to the flask, and concentrated H was added with stirring2SO4(1.0 mL). The flask was connected to a condenser, heated to 80 ℃ and stirred for 48 hours (TLC monitoring). After the reaction was completed and cooled to room temperature, deionized water was added to the reaction mixture(100mL), a pale yellow precipitate was produced. Suction filtration, washing well with water and drying under vacuum at 70 ℃ gave the product as a pale yellow solid (0.95g, 84.7% yield based on DMBD).1H NMR(400MHz,CDCl3):δ(ppm):7.95(s,2H,CHAr),4.66(s,2H,SHAr),3.94(s,6H,CH3)
2) Preparation of the Compound (S, S) -2, 5-bis- (2-hydroxypropylsulfanyl) -dimethyl terephthalate (intermediate 2)
Taking a 100mL Schlenk bottle, repeatedly vacuumizing and introducing nitrogen for three times to form an anhydrous oxygen-free system, dissolving the intermediate 1 (anhydrous, 0.44g and 1.71mmol) in anhydrous ethanol (20mL) under the condition of keeping introducing nitrogen, adding the solution into the reaction bottle, and adding the solution into the reaction bottle by using N2Bubbling for 15 minutes. Triethylamine (0.51mL) and (S) - (-) -propylene oxide (99%, 0.289g, 4.85mmol, dissolved in 5mL of absolute ethanol), N2After degassing, the mixture was added to the reaction flask by syringe. The reaction flask was sealed and stirred at room temperature overnight (TLC monitoring). After the reaction was completed, it was rotary evaporated to give a yellow solid, which was purified by silica gel column (eluent n-hexane/ethyl acetate, V/V ═ 1:1) to give the product as yellow crystalline material (0.42g, yield 65.6% based on intermediate 1).1H NMR(400MHz,DMSO-d6):δ(ppm):7.79(s,2H,CHAr),4.98-5.00(d,2H,OH),3.86(s,6H,CH3),3.78-3.83(m,2H,CH),2.91-2.99(m,4H,SCH2),1.16-1.18(d,6H,CH3)。
3) Preparation of (S, S) -2, 5-bis- (2-hydroxypropylsulfanyl) -terephthalic acid
A25 mL round bottom flask was taken and intermediate 2(0.2g, 0.53mmol) was added to 5mL 10% NaOH in methanol, heated to 80 deg.C and refluxed overnight with stirring. After the reaction was complete and cooled to room temperature, 5mL of methanol was added to the reaction mixture, followed by the slow addition of concentrated HCl (36%) with vigorous stirring to a pH below 2. Rotovap to give a yellow solid, and add 30mL of water. Suction filtration and water washing gave the yellow product (167mg, 90.3% yield based on intermediate 2).1H NMR(400MHz,CD3OD):7.94(s,2H,CHAr),6.91(s,2H,OH),3.93-4.00(m,2H,CH),2.97-3.08(m,4H,SCH2),1.30-1.31(d,6H,CH3). The resulting product is e.g.1H NMR showed pure and was used for crystal growth without further purification.
Secondly, preparing functional zirconium-based metal organic cages (Zr-MOCs)
(S, S) -2, 5-bis- (2-hydroxypropylsulfanyl) -terephthalic acid (7mg,0.02mmol) and zirconocene dichloride (11.7mg,0.04mmol) were weighed out and dissolved in N, N-dimethylacetamide (0.2mL) and sonicated until completely dissolved. Subsequently, deionized water (0.4mL) was added and sonicated for 10-15 minutes until the mixture was clear. The mixture was transferred to a heat-resistant glass vial (3mL), sealed and placed in a preheated 60 ℃ oven and heated for 10 hours. After the reaction is finished, cooling in the air, and standing for 12 hours to obtain yellow cubic crystals. And centrifuging and washing the obtained crystal with DMA for three times, soaking the crystal in DCM for 3 days for solvent exchange, and replacing the solvent 3 times a day to obtain the functional zirconium-based metal organic cages (Zr-MOCs).
FIG. 1 shows the three-dimensional structure of the crystals of the functionalized zirconium-based metal organic cages (Zr-MOCs) prepared in this example; FIG. 2 shows the X-ray diffraction pattern and the infrared spectrum of the functionalized zirconium-based metal organic cages (Zr-MOCs) prepared in this example.
EXAMPLE 2 preparation of Zr-MOCs
The functionalized zirconium-based metal organic cages (Zr-MOCs) of this example were prepared using (S, S) -2, 5-bis- (2-hydroxypropylsulfanyl) -terephthalic acid prepared in example 1 as ligand, ligand and zirconocene dichloride (Cp)2ZrCl2) Coordination self-assembly; the preparation method comprises the following steps:
0.02mmol of (S, S) -2, 5-bis- (2-hydroxypropylsulfanyl) -terephthalic acid and 0.03mmol of zirconocene dichloride were dissolved in 0.2mL of N, N-dimethylacetamide and sonicated until completely dissolved. Subsequently, 0.3mL of deionized water was added and sonicated for 10-15 minutes until the mixture was clear. The mixture was transferred to a heat-resistant glass vial (3mL), sealed and placed in a preheated 65 ℃ oven and heated for 12 hours. After the reaction is finished, cooling in the air, and standing for 12 hours to obtain yellow cubic crystals. And centrifuging and washing the obtained crystal with DMA for three times, soaking the crystal in DCM for 3 days for solvent exchange, and replacing the solvent 3 times a day to obtain the functional zirconium-based metal organic cages (Zr-MOCs).
EXAMPLE 3 preparation of Zr-MOCs
The functionalized zirconium-based metal organic cage (Zr-MOCs) the (S, S) -2, 5-bis- (2-hydroxypropylsulfanyl) -terephthalic acid prepared in example 1 was used as ligand with zirconocene dichloride (Cp)2ZrCl2) Coordination self-assembly; the preparation method comprises the following steps:
0.02mmol of (S, S) -2, 5-bis- (2-hydroxypropylsulfanyl) -terephthalic acid and 0.05mmol of zirconocene dichloride were dissolved in 0.2mL of N, N-dimethylacetamide and sonicated until completely dissolved. Subsequently, 0.5mL of deionized water was added and sonicated for 10-15 minutes until the mixture was clear. The mixture was transferred to a heat-resistant glass vial (3mL), sealed and placed in a preheated 60 ℃ oven and heated for 12 hours. After the reaction is finished, cooling in the air, and standing for 12 hours to obtain yellow cubic crystals. And centrifuging and washing the obtained crystal with DMA for three times, soaking the crystal in DCM for 3 days for solvent exchange, and replacing the solvent 3 times a day to obtain the functional zirconium-based metal organic cages (Zr-MOCs).
EXAMPLE 4 measurement of fluorescence Properties of Zr-MOCs
The Zr-MOCs prepared in example 1 were immersed in a series of different solvents to test the fluorescence spectra as follows: 5mg of the ground Zr-MOCs powder is added with 5mL of DMA, the mixture is dispersed evenly by ultrasonic, and then 50 mu L of the dispersion is added into 2mL of different solvents respectively under continuous stirring.
The fluorescence emission spectra of Zr-MOCs dispersed in different solvents are shown in FIG. 3. As can be seen from FIG. 3, Zr-MOCs have slight solvent dependence, with the strongest fluorescence intensity in DMF and the weakest fluorescence intensity in water and acetone. Based on the results of the solvent fluorescence detection and the requirement for the stability of the Zr-MOCs material therein, DMF was selected to disperse the Zr-MOCs and used as a solvent to formulate the analyte solution.
Further, formulation 10-9mol/L to 10-4The six concentrations of Zr-MOCs in mol/L in DMF suspension were tested for fluorescence excitation and emission spectra, and the results are shown in FIG. 4. As can be seen from FIG. 4, there is a large difference in fluorescence properties of the Zr-MOCs at different concentrations; wherein the maximum emission wavelength of the emission spectrum is from 510nm (10)-4mol/L) to 422nm (10)-9mol/L), which enables the Zr-MOCs to have the characteristic of realizing the fluorescence detection of different pollutants at different concentrations. Simultaneously, selecting excitation spectrum and excitationTwo groups of Zr-MOCs suspensions (10) with relatively large difference of emission spectra and relatively strong emission intensity and relatively representative concentration-6mol/L and 10-9mol/L) for subsequent fluorescence tests.
EXAMPLE 5 fluorescent detection of antibiotics and toxic heavy metals by Zr-MOCs
This example uses Zr-MOCs prepared in example 1 for fluorescence detection, test 10-6mol/L and 10- 9DMF suspension of two groups of Zr-MOCs in mol/L (chromium dichromate)2O7 2-) The fluorescence detection capability of nine different pollutants, Sulfamethazine (SMZ), Carbamazepine (CBZ), Nitrofurantoin (NFT), Nitrofurazone (NFZ), p-nitrophenol (4-NP), Dimethylnitroimidazole (DTZ), florfenicol (FFC) and Thiamphenicol (THI); the method comprises the following steps:
2.5mL of the Zr-MOCs suspension was taken with stirring, 140uL of a 1.86mM DMF solution of the analyte (giving an analyte concentration of 0.1mM each) was added, and after 2-3 minutes of sonication, the emission spectrum was measured, and the results are shown in FIG. 5. As can be seen in FIG. 5, 10- 6mol/L test group to SMZ and Cr2O7 2-Has a significant fluorescence quenching effect, and 10-9The mol/L test group shows obvious fluorescence quenching phenomenon in the presence of NFT and NFZ.
EXAMPLE 6Zr-MOCs fluorescence detection sensitivity test
This example uses a fluorescence titration experiment on the Zr-MOCs versus SMZ, Cr prepared in example 12O7 2-NFT and NFZ. Taking SMZ as an example, 10uL, 20uL, 30uL, 40uL, 60uL, 80uL, 100uL, 120uL and 140uL of DMF solution of SMZ are added into 2.5mL of DMF suspension of Zr-MOCs in sequence, after 2-3 minutes of ultrasonic treatment, the excitation wavelength is set to be 288nm, the slit width is set to be 1.5nm, and the change of fluorescence intensity of the Zr-MOCs is tested. As shown in FIG. 6a, the fluorescence intensity of Zr-MOCs decreased significantly after the addition of SMZ.
The quenching constants (Ksv) and detection Limits (LOD) of the Zr-MOCs to the SMZ were calculated. The quenching efficiency can be quantified using the Stern-Volmer equation, i.e.:
I0/I＝KSV[C]+1
in the formula: i is0Is the original intensity; i is the intensity after addition of the analyte; ksv is the Stern-Volmer constant; c is the analyte concentration.
As shown in FIG. 6b, in the SMZ concentration range of 0-0.05mM, I0the/I showed a good linear relationship with SMZ concentration (R)20.9937) calculated Ksv value of 3.3615 × 10 for Zr-MOCs versus SMZ4M-1(ii) a In addition, the detection limit of SMZ is calculated by using 3 sigma/Ksv (sigma: standard difference of fluorescence intensity of five blank samples), the estimated value of the detection limit is 0.747 mu M, and the detection limit is at a higher level in the existing SMZ fluorescence detection.
EXAMPLE 7Zr-MOCs Selectivity test
The Zr-MOCs prepared in example 1 were used for selectivity testing as follows:
mixing SMZ and Cr2O7 2-And respectively adding the NFT and the NFZ into Zr-MOCs suspension liquid containing other coexisting pollutants, and detecting the emission intensity of the mixed solution to represent the selectivity and the anti-interference capability of the Zr-MOCs. Taking NFT as an example, 2.5mL of a Zr-MOC suspension in DMF was taken with stirring, with the excitation wavelength set at 362nm and the slit width set at 1.5 nm.
1) Firstly, testing the fluorescence intensity of a blank solution;
2) then respectively adding 140uL of 1.86mM Cr2O7 2-SMZ, CBZ, 4-NP, DTZ, FFC, THI in DMF (all at 0.1mM analyte concentration), sonicated for 2-3 minutes, and measured for fluorescence intensity;
3) further, 150uL of NFT in DMF (so that the NFT concentration is also 0.1mM) was added to the solution in 2), and the fluorescence intensity was measured by sonication for 2 to 3 minutes.
As shown in FIG. 7, most analytes have a certain degree of fluorescence quenching in the absence of NFT, but after the addition of NFT, strong fluorescence quenching appears, demonstrating that Zr-MOCs have excellent selectivity and anti-interference capability.
Example 8Zr-MOCs cycling stability test
Cycling stability tests were performed using the Zr-MOCs prepared in example 1 as follows:
the used Zr-MOCs suspension was collected by centrifugation, washed thoroughly 3 times with DMF and DCM, dried under vacuum at 60 ℃ and then ground carefully to reconstitute the Zr-MOCs suspension, and the fluorescence detection effect of 5 cycles of recovered Zr-MOCs on SMZ was tested and the results are shown in FIG. 8. The results show that: the Zr-MOCs have repeatability. In addition, powder X-ray diffraction (PXRD) patterns of the Zr-MOCs after 5 times of test circulation show that the Zr-MOCs after the circulation have good structural stability.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A preparation method of a functionalized zirconium-based metal organic cage is characterized by comprising the following steps:
s1: dissolving (S, S) -2, 5-bis- (2-hydroxypropyl sulfanyl) -terephthalic acid and zirconium salt in an organic solvent to obtain a mixture;
s2: carrying out a solvothermal reaction on the mixture to obtain a reaction mixture;
s3: and cooling, crystallizing, washing and solvent exchanging the reaction mixture to obtain the functionalized zirconium-based metal organic cage.
2. The method according to claim 1, wherein step S1 includes: adding (S, S) -2, 5-bis- (2-hydroxypropyl sulfanyl) -terephthalic acid and zirconium salt into an organic solvent, performing ultrasonic treatment until the solution is completely dissolved, adding deionized water, and performing continuous ultrasonic treatment until the solution is clear to obtain a mixture;
preferably, the zirconium salt is zirconocene dichloride;
preferably, the molar ratio of (S, S) -2, 5-bis- (2-hydroxypropylsulfanyl) -terephthalic acid to zirconium salt is 1: (1.5-2.5), more preferably 1: 2;
preferably, the organic solvent is N, N-dimethylformamide or N, N-dimethylacetamide;
preferably, the volume ratio of the organic solvent to the deionized water is 1: (1.5-2.5), more preferably 1: 2;
preferably, the ultrasound conditions are: the ultrasonic power is 200-300w, and more preferably 250 w; the ultrasonic treatment time is 10-15 min.
3. The method according to claim 1, wherein the reaction temperature is 60 to 65 ℃, preferably 60 ℃ in step S2; the reaction time is 10-12h, preferably 10 h.
4. The method according to claim 1, wherein in step S3, the cooling is carried out by leaving the mixture in air to cool the mixture to room temperature; washing is carried out by adopting N, N-dimethylformamide or N, N-dimethylacetamide for 2-4 times of centrifugal washing; solvent exchange involves soaking the crystals with dichloromethane or acetone;
preferably, the centrifugal speed during centrifugal washing is 8000-10000rpm, and the centrifugal time is 2-3 min;
preferably, the solvent used for solvent exchange is dichloromethane; the solvent exchange time is 2-4 d; during the solvent exchange process, the solvent is changed 2-4 times per day.
5. The method according to claim 1, wherein the (S, S) -2, 5-bis- (2-hydroxypropylsulfanyl) -terephthalic acid is prepared by a method comprising:
A) mixing 2, 5-dimercapto-1, 4-phthalic acid and methanol, adding concentrated H under stirring2SO4Reacting, adding deionized water into the reaction mixture for precipitation, filtering, washing and drying to obtain 2, 5-dimercapto dimethyl terephthalate;
B) dissolving dimethyl 2, 5-dimercaptoterephthalate, triethylamine and S-epoxypropane in absolute ethyl alcohol under a protective atmosphere, stirring overnight at room temperature, and performing rotary evaporation and purification to obtain (S, S) -dimethyl 2, 5-bis- (2-hydroxypropyl sulfanyl) -terephthalate;
C) adding NaOH solution into (S, S) -2, 5-bis- (2-hydroxypropyl sulfanyl) -terephthalic acid dimethyl ester, stirring and refluxing overnight, adding methanol into the reaction mixture, then adding concentrated HCl under stirring to adjust the pH value to be lower than 2, adding deionized water after rotary evaporation, filtering and washing to obtain (S, S) -2, 5-bis- (2-hydroxypropyl sulfanyl) -terephthalic acid.
6. The process according to claim 5, wherein in step A), the reaction temperature is 75-85 ℃ and the reaction time is 46-50 h; 2, 5-dimercapto-1, 4-phthalic acid, methanol and concentrated H2SO4The dosage ratio of the components is 1 g: (70-90) mL: (0.8-1.2) mL; in the step B), the dosage proportion of the 2, 5-dimercaptoterephthalic acid dimethyl ester, the triethylamine and the S-epoxypropane is 1: (1.0-1.3) mL: (0.5-0.8) g; in the step C), the temperature of stirring reflux is 75-85 ℃, the NaOH solution is 8-12% of NaOH methanol solution, and the dosage ratio of (S, S) -2, 5-bis- (2-hydroxypropyl sulfanyl) -dimethyl terephthalate to the NaOH solution is 1 g: (20-30) mL.
7. A functionalized zirconium-based metal organic cage, characterized in that it is obtained by a process according to any one of claims 1 to 6.
8. Use of the functionalized zirconium-based metal organic cage of claim 7 in the detection of environmental contaminants;
preferably, the environmental contaminant comprises at least one of dichromate, sulfamethazine, carbamazepine, nitrofurantoin, nitrofurazone, p-nitrophenol, dinitomidazole, florfenicol, and thiamphenicol.
9. An environmental contaminant detection method, comprising: preparing the functionalized zirconium-based metal organic cage of claim 7 into a suspension of Zr-MOCs, and then performing fluorescence detection on environmental pollutants by using the suspension of Zr-MOCs;
preferably, the Zr-MOCs suspension has a concentration of 10-9mol/L to 10-4mol/L；
Preferably, the concentration of the environmental contaminant is greater than 0.747 μ M.
10. The method of detecting environmental contaminants of claim 9, wherein a concentration of 10 is used-6Detecting sulfamethazine and dichromate by using a mol/L Zr-MOCs suspension; with a concentration of 10-9And (3) detecting nitrofurantoin and nitrofurazone by using a Zr-MOCs suspension of mol/L.
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| CN117143350A (en) * | 2023-08-29 | 2023-12-01 | 广东工业大学 | Dissimilar metal organic molecular cage material, preparation method and application thereof, and preparation method for oxidizing thioether into sulfone |
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| CN115253611A (en) * | 2022-07-23 | 2022-11-01 | 大连理工大学盘锦产业技术研究院 | Mixed matrix membrane CO accurately regulated and controlled by using specific surface area of filler2Method for separating properties |
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| CN117143350A (en) * | 2023-08-29 | 2023-12-01 | 广东工业大学 | Dissimilar metal organic molecular cage material, preparation method and application thereof, and preparation method for oxidizing thioether into sulfone |
| CN117143350B (en) * | 2023-08-29 | 2024-03-12 | 广东工业大学 | Dissimilar metal organic molecular cage material, preparation method and application thereof, and preparation method for oxidizing thioether into sulfone |
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