Background
Porous Organic Polymers (POPs) are obtained from light elements (C, H, O, N) by covalent bonding. The POPs material has excellent porosity and stable covalent bond, so that the POPs material has high hydrothermal stability, and an expanded conjugated system, so that the POPs material has wide application prospects in important fields of energy gas storage and separation, catalysts, fluorescence sensing, semiconductor photoelectric application, new energy storage and conversion, biological medicine and the like (chem. Soc. Rev,2020,49(12), 3981-. According to the difference of pore-forming mechanism of porous organic polymer, the porous organic polymer which has been reported at present can be mainly divided into four major classes, namely, intrinsic microporous Polymers (PIMs), Conjugated Microporous Polymers (CMPs), hypercrosslinked polymers (HCPs) and Covalent Organic Frameworks (COFs).
The structure and the property of the organic porous material can be realized by adjusting the construction element, and the reaction and the structural building block for constructing the organic porous polymer have diversity. To diversify the function of the organic skeleton, inorganic groups may be introduced into the framework. Polyhedral oligomeric siloxane (POSS) is one of representative and ideal inorganic building blocks due to its rigid, highly symmetrical, highly connectable structure and easy functionalization, and can be used for building conjugated microporous polymers and for fluorescent sensing picric acid (Polym. chem.,2015,6, 917-.
The cyclic compounds are introduced into the structure of the conjugated microporous polymer due to the hydrophobic cavity, which is easily functionalized. For example, calixarene (chem. Eur.J.2018,24(34), 8648-. Conjugated macrocyclic polymer materials prepared by the yankee theme group at the university of gilin are useful as fluorescent sensors for metal ions and organic molecules (adv. mater.2018,30,1800177). Eight-membered ring siloxanes belong to the middle ring molecule, Piero Sozzani and Tatsuya Okubo prepare eight-membered ring siloxane based hypercrosslinked polymers and use for gas adsorption (J.Mater. chem.A., 2017,5, 10328-. Reports on the preparation and application research of the eight-membered cyclosiloxane based conjugated microporous polymer are not seen yet.
2, 4-Dinitrophenol (DNP) is both an environmental pollutant and an explosive hazard (J.Am.chem.Soc.121(1999) 1743-174), has great toxic and side effects as an oral anti-obesity drug, and even causes death (J.Med.Toxicol.7(2011) 205-21). Therefore, the research and development of a rapid and sensitive DNP detection method has important significance. Fluorescence sensing technology has attracted considerable attention due to its simplicity of operation and low cost (chem.Commun.54(2018) 2308-2311; New J.chem.44(2020) 19663-19671; New J.chem.45(2021) 3007-3013). However, no research on the application of the eight-membered cyclosiloxane-based conjugated microporous polymer to the fluorescence sensing of 2, 4-dinitrophenol is found at present.
Disclosure of Invention
Based on the technical problems in the background art, the invention provides an eight-membered ring siloxane-based conjugated microporous polymer, and a preparation method and application thereof, the invention enlarges the varieties of the existing conjugated microporous polymers, has good solvent tolerance and thermal stability and higher specific surface area, and can selectively perform fluorescence sensing on 2, 4-dinitrophenol in the presence of other substances; the detection method has the advantages of simple and convenient operation, visual signal, high sensitivity and good selectivity, and can carry out real-time in-situ detection.
The invention provides an eight-membered ring siloxane-based conjugated microporous polymer, which has a structure shown as a formula (I):
the invention also provides a preparation method of the eight-membered cyclosiloxane-based conjugated microporous polymer, which comprises the following steps: taking 2,4,6, 8-tetramethyl-2, 4,6, 8-tetraphenyl tetrasiloxane and cyanuric chloride, and carrying out Friedel-crafts arylation reaction in the presence of a Lewis acid catalyst to obtain the eight-membered ring siloxane based conjugated microporous polymer.
Preferably, the friedel-crafts arylation reaction is carried out in an inert gas atmosphere.
Preferably, the temperature of the Friedel-crafts arylation reaction is between 40 and 100 ℃.
Preferably, the time for the Friedel-crafts-alkylation reaction is 5-30 h.
Preferably, the molar ratio of the Lewis acid catalyst, 2,4,6, 8-tetramethyl-2, 4,6, 8-tetraphenyltetrasiloxane and cyanuric chloride is (1-99): (0.2-20): (0.3-30).
Preferably, the molar ratio of the Lewis acid catalyst, the 2,4,6, 8-tetramethyl-2, 4,6, 8-tetraphenyl tetrasiloxane and the cyanuric chloride is 1 (0.2-0.25) to (0.25-0.3).
Preferably, the lewis acid catalyst comprises: at least one of aluminum trichloride, boron trifluoride and iron tribromide.
Preferably, the reaction solvent is at least one of dichloromethane, 1, 2-dichloroethane, and chloroform.
After the Friedel-crafts arylation reaction, the eight-membered ring siloxane-based conjugated microporous polymer is obtained by purification, and the purification method comprises the following steps: after Friedel-crafts arylation reaction, carrying out solid-liquid separation, washing the solid, extracting and drying to obtain the octatomic ring siloxane-based conjugated microporous polymer; the drying mode is preferably vacuum drying, and the drying temperature is preferably 50-120 ℃; the extraction time can be 24h and the like.
The washing solvent may be methanol, acetone, etc.; the solvent for extraction may be methanol, tetrahydrofuran, acetone, etc.
The invention also provides application of the eight-membered cyclosiloxane-based conjugated microporous polymer as a fluorescent sensing material.
Preferably, the eight-membered cyclosiloxane-based conjugated microporous polymer is used as a fluorescence sensing material for selectively sensing 2, 4-dinitrophenol.
Has the advantages that:
the octatomic ring siloxane-based conjugated microporous polymer prepared by the invention has good solvent tolerance and thermal stability, higher specific surface area and fluorescence property, and can well sense 2, 4-dinitrophenol by fluorescence; 2, 4-dinitrophenol can be selectively fluorescence sensed in the presence of other substances (such as elemental iodine and other Nitroaromatics (NACs)); the detection method has the advantages of simple and convenient operation, visual signal, high sensitivity and good selectivity, and can carry out real-time in-situ detection.
Detailed Description
The technical solution of the present invention will be described in detail below with reference to specific examples.
Example 1
A preparation method of an eight-membered cyclosiloxane based conjugated microporous polymer comprises the following steps:
compound 2,4,6, 8-tetramethyl-2, 4,6, 8-tetraphenyl tetrasiloxane (1.6348g, 3.0mmol), cyanuric chloride (0.7376g, 4mmol), anhydrous AlCl3(1.9201g, 14.4mmol) was added to dry dichloromethane (40mL) and stirred well at room temperature; introducing nitrogen, heating to 60 deg.C in oil bath, reacting for 24 hr, and cooling to room temperatureAnd (3) carrying out suction filtration, washing the solid product for 3 times by using methanol and acetone respectively, extracting the solid product for 24 hours by using methanol, tetrahydrofuran and acetone respectively in a Soxhlet extractor, and finally carrying out vacuum drying for 24 hours at 50 ℃ to obtain the eight-membered ring siloxane-based conjugated microporous polymer, which is marked as TMPS.
Example 2
A preparation method of an eight-membered cyclosiloxane based conjugated microporous polymer comprises the following steps:
compound 2,4,6, 8-tetramethyl-2, 4,6, 8-tetraphenyl tetrasiloxane (1.6348g, 3.0mmol), cyanuric chloride (0.7376g, 4mmol), anhydrous AlCl3(1.9201g, 14.4mmol) was added to chloroform (40mL) and stirred well at room temperature; introducing nitrogen, placing the mixture in an oil bath, heating the mixture to 80 ℃, reacting for 20 hours, cooling the mixture to room temperature, carrying out suction filtration, washing the solid product for 3 times by using methanol and acetone respectively, extracting the solid product for 24 hours by using methanol, tetrahydrofuran and acetone in a Soxhlet extractor respectively, and finally carrying out vacuum drying for 24 hours at the temperature of 60 ℃ to obtain the eight-membered ring siloxane-based conjugated microporous polymer.
Example 3
A preparation method of an eight-membered cyclosiloxane based conjugated microporous polymer comprises the following steps:
compound 2,4,6, 8-tetramethyl-2, 4,6, 8-tetraphenyl tetrasiloxane (1.6348g, 3.0mmol), cyanuric chloride (0.7376g, 4mmol), anhydrous AlCl3(1.9201g, 14.4mmol) was added to dry dichloroethane (40mL) and stirred well at room temperature; introducing nitrogen, placing the mixture in an oil bath, heating the mixture to 100 ℃, reacting for 16 hours, cooling the mixture to room temperature, carrying out suction filtration, washing the solid product for 3 times by using methanol and acetone respectively, extracting the solid product for 24 hours by using methanol, tetrahydrofuran and acetone in a Soxhlet extractor respectively, and finally carrying out vacuum drying for 24 hours at 80 ℃ to obtain the eight-membered ring siloxane-based conjugated microporous polymer.
Experiment 1
The eight-membered cyclosiloxane-based conjugated microporous polymer prepared in example 1 was dispersed in solvents with different polarities under the action of ultrasonic waves to make the concentration of the dispersion liquid 0.5mg/mL, wherein the polar solvents include: acetonitrile, acetone, N-Dimethylformamide (DMF), 1, 4-Dioxane (DOX), chloroform, Tetrahydrofuran (THF), and ethanol; then, under the excitation of an excitation wavelength of 374nm, the emission spectrum is recorded, as shown in FIG. 1, and FIG. 1 is the emission spectrum of the eight-membered cyclosiloxane based conjugated microporous polymer in example 1 in different solvents.
As can be seen from FIG. 1, the eight-membered cyclosiloxane-based conjugated microporous polymer has the highest fluorescence intensity in the tetrahydrofuran dispersion.
The dispersion of experiment 1 was irradiated with an ultraviolet lamp (365 nm wavelength of ultraviolet), and the result is shown in FIG. 2. FIG. 2 is a fluorescent image of the dispersion of the eight-membered cyclosiloxane based conjugated microporous polymer of example 1 in different solvents under the ultraviolet lamp.
As can be seen from FIG. 2, the eight-membered cyclosiloxane-based conjugated microporous polymer emits bright blue fluorescence in some organic solvents (e.g., acetone, N-dimethylformamide, 1, 4-dioxane, and tetrahydrofuran).
Experiment 2
Taking the eight-membered ring siloxane-based conjugated microporous polymer prepared in example 1, and carrying out fluorescence sensing on elemental iodine and nitroaromatic compounds (NACs for short), wherein the nitroaromatic compounds comprise: p-nitrotoluene (p-NT), o-nitrophenol (o-NP), p-nitrophenol (p-NP), Dinitrotoluene (DNT), m-dinitrobenzene (m-DNB), Nitrobenzene (NB), p-dinitrobenzene (p-DNB), Picric Acid (PA), m-nitrophenol (m-NP), 2, 4-Dinitrophenol (DNP).
The specific detection method comprises the following steps:
s1 fluorescence emission spectrum of tetrahydrofuran dispersion of 0.5mg/mL octatomic cyclosiloxane-based conjugated microporous polymer with excitation wavelength of lambda was measured using a fluorescence spectrophotometerex374nm and the fluorescence emission spectrum and the intensity of the fluorescence at its peak emission are recorded as I0;
S2, dropwise adding a proper amount of elemental iodine or nitroaromatic compound solution with the concentration of 0.1mol/L into tetrahydrofuran dispersion liquid of the eight-membered cyclosiloxane-based conjugated microporous polymer with the concentration of 0.5mg/mL, and uniformly mixing to ensure that the concentration of the elemental iodine or the nitroaromatic compound in the dispersion liquid is 2.5 multiplied by 10-4mol/L, at the same excitation wavelength, the fluorescence emission spectrum is testedRecording the fluorescence emission spectrum and the fluorescence intensity at the highest emission peak as I; as a result, as shown in FIG. 3, FIG. 3 shows the relative fluorescence intensities (I) of the eight-membered cyclosiloxane-based conjugated microporous polymer in example 1 in the presence of different substances0I) comparative bar graph, in which Free is 0.5mol/L tetrahydrofuran dispersion of eight-membered cyclosiloxane-based conjugated microporous polymer.
As can be seen from FIG. 3, 2, 4-dinitrophenol significantly quenches the eight-membered cyclosiloxane-based conjugated microporous polymer; except for p-nitrophenol, picric acid and iodine, other substances have smaller fluorescence quenching on the eight-membered cyclosiloxane based conjugated microporous polymer. The octatomic ring siloxanyl conjugated microporous polymer has better selectivity to dinitrophenol.
Experiment 3
The octatomic ring siloxane-based conjugated microporous polymer prepared in example 1 was taken, tetrahydrofuran dispersion liquid with the concentration of 0.5mg/mL was prepared, and 2, 4-dinitrophenol was added to make the concentration of 2.5X 10 of 2, 4-dinitrophenol-4mol/L; as a result of irradiating the dispersion before and after addition of 2, 4-dinitrophenol with an ultraviolet lamp having a wavelength of 365nm, FIG. 4 shows the fluorescence effect of 2, 4-dinitrophenol under an ultraviolet lamp measured by the eight-membered cyclosiloxane-based conjugated microporous polymer in example 1, in which TMPS is a tetrahydrofuran dispersion of the eight-membered cyclosiloxane-based conjugated microporous polymer and TMPS + DNP is a tetrahydrofuran dispersion of the eight-membered cyclosiloxane-based conjugated microporous polymer to which 2, 4-dinitrophenol is added.
As can be directly observed from FIG. 4, 2, 4-dinitrophenol significantly quenches the fluorescence of the eight-membered cyclosiloxane-based conjugated microporous polymer.
Experiment 4
The octatomic ring siloxane-based conjugated microporous polymer prepared in example 1 was taken, tetrahydrofuran dispersion liquid with the concentration of 0.5mg/mL was prepared, and 2, 4-dinitrophenol, other nitroaromatic compounds or I was added2Reacting 2, 4-dinitrophenol, another nitroaromatic compound or I2Has a concentration of 2.5X 10-4mol/L, and then measuring the fluorescence emission spectrum of each solution at an excitation wavelength of 374nm, wherein other nitroaromatics arep-NT、DNT、o-NP、m-NP、p-NP、m-DNB、p-DNB、NB、PA。
As shown in FIG. 5, FIG. 5 shows the selective fluorescence sensing of 2, 4-dinitrophenol by the octacyclic cyclosiloxane-based conjugated microporous polymer of example 1, where TMPS is tetrahydrofuran dispersion of the octacyclic siloxane-based conjugated microporous polymer, TMPS + other NACs or I2For adding other NACs or I2Tetrahydrofuran dispersion of eight-membered cyclosiloxane-based conjugated microporous polymers, TMPS + other NACs or I2+ DNP for adding other NACs or I2And a tetrahydrofuran dispersion of an eight-membered cyclosiloxane-based conjugated microporous polymer to which 2, 4-dinitrophenol is added.
As can be seen from FIG. 5, when 2.5X 10 is added-4When mol/L of other nitroaromatic compound or iodine is added, the fluorescence intensity of the eight-membered cyclosiloxane-based conjugated microporous polymer is almost unchanged, but when 2.5X 10 is added-4When the molecular weight is 2, 4-dinitrophenol mol/L, the fluorescence intensity of the eight-membered ring siloxane-based conjugated microporous polymer is obviously reduced. The eight-membered cyclosiloxane-based conjugated microporous polymer can selectively fluoresce and sense 2, 4-dinitrophenol in the presence of other nitroaromatic compounds or iodine.
As a result of irradiating each dispersion described in experiment 4 above with an ultraviolet lamp (ultraviolet ray having a wavelength of 365nm), FIG. 6 is a graph showing the effect of the eight-membered cyclosiloxane-based conjugated microporous polymer on the selective fluorescence sensing of 2, 4-dinitrophenol in example 1, wherein TMPS is a tetrahydrofuran dispersion of the eight-membered cyclosiloxane-based conjugated microporous polymer, TMPS + NACs or I2For adding other NACs or I2Tetrahydrofuran dispersions of eight-membered cyclosiloxane-based conjugated microporous polymers, TMPS + NACs or I2+ DNP for adding other NACs or I2And a tetrahydrofuran dispersion of an eight-membered cyclosiloxane-based conjugated microporous polymer to which 2, 4-dinitrophenol is added.
As can be seen from FIG. 6, other nitroaromatics and iodine do not quench the fluorescence of the eight-membered cyclosiloxane-based conjugated microporous polymer, whereas 2, 4-dinitrophenol selectively quenches the fluorescence of the eight-membered cyclosiloxane-based conjugated microporous polymer in the presence of the above-mentioned substances.
In the above experiment, the concentration of the dispersion of the eight-membered cyclosiloxane-based conjugated microporous polymer material may be 0.1 to 1.0 mg/mL; the test voltage of the fluorescence spectrophotometer can be 220-700V, and the slit width can be 5-20 nm.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.