Ligand-containing conjugated microporous polymer and use thereof

Abstract

The present invention relates to a ligand-containing conjugated microporous polymer, which is obtained by covalent coupling of a conjugated microporous polymer and a uranium complexing ligand. The conjugated microporous polymer comprises an aromatic ring and/or a heterocyclic ring. The uranium complexing ligand is selected from the group consisting of a compound with a group containing phosphorus, a compound with a group containing nitrogen, and a compound with a group containing sulfur. The invention further provides use of the ligand-containing conjugated microporous polymer as a uranium adsorbent. The ligand-containing conjugated microporous polymer the invention is capable of adsorbing the radioactive element uranium in strongly acidic and strong-radiation environments.

Claims

1. A ligand-containing conjugated microporous polymer, obtained by covalent coupling of a conjugated microporous polymer and a uranium complexing ligand, wherein the conjugated microporous polymer comprises an aromatic ring and/or a heterocyclic ring, and the uranium complexing ligand is selected from a compound with a group containing phosphorus, a compound with a group containing nitrogen, a compound with a group containing sulfur and any combination thereof, wherein the uranium complexing ligand comprises one or more of the following groups: ##STR00015## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are independently selected from alkyl, hydrogen, phenyl and a heterocyclic group.

2. The ligand-containing conjugated microporous polymer as claimed in claim 1, wherein the conjugated microporous polymer is obtained by copolymerization of a first monomer and a second monomer, the first monomer and the second monomer being independently selected from the group consisting of benzene, a benzene derivative, fluorene, a fluorene derivative, porphyrin, a porphyrin derivative, pyridine, a pyridine derivative, thiophene and a thiophene derivative.

3. The ligand-containing conjugated microporous polymer as claimed in claim 2, wherein the group containing phosphorus is selected from a phosphonic acid group, a phosphate ester group, a phosphonooxy group and any combination thereof.

4. The ligand-containing conjugated microporous polymer as claimed in claim 2, wherein the group containing nitrogen is an amido group and/or a propanediamido group.

5. The ligand-containing conjugated microporous polymer as claimed in claim 1, wherein the compound with a group containing phosphorus has a structure of ##STR00016## ##STR00017##

6. The ligand-containing conjugated microporous polymer as claimed in claim 1, wherein the compound with a group containing nitrogen has a structure of ##STR00018## wherein R is CH.sub.2CH.sub.3, CH.sub.2CH.sub.2CH.sub.3, or phenyl.

7. The ligand-containing conjugated microporous polymer as claimed in claim 2, wherein the polymer is synthesized by the step of: copolymerizing the first monomer and the second monomer, and then reacting with the uranium complexing ligand compound, to obtain the ligand-containing conjugated microporous polymer, wherein the uranium complexing ligand compound is phosphonic acid, a phosphate ester, a phosphonooxy compound, an amide or a propanediamide compound.

8. The ligand-containing conjugated microporous polymer as claimed in claim 2, wherein the polymer is synthesized by the step of: reacting the first monomer with the uranium complexing ligand compound, and then copolymerizing with the second monomer, to obtain the ligand-containing conjugated microporous polymer, wherein the uranium complexing ligand compound is phosphonic acid, a phosphate ester, a phosphonooxy compound, an amide or a propanediamide compound.

9. A uranium adsorbent comprising the ligand-containing conjugated microporous polymer as claimed in claim 1.

10. The uranium adsorbent as claimed in claim 9, wherein the adsorbent is used in acidic and radiation environments.

11. The uranium adsorbent as claimed in claim 10, wherein the acidic and radiation environments comprise an acid with a concentration of 4-6 mol/L and a radiation intensity of 200-1,000 KGy.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a Solid-State NMR (SSNMR) spectrum of a ligand-containing conjugated microporous polymer according to embodiment 1 of the invention;

(2) FIG. 2 shows an IR spectrum and an X-ray photoelectron spectrum of the ligand-containing conjugated microporous polymer according to embodiment 1 of the invention;

(3) FIG. 3 shows the effect of different conditions on the adsorption efficiency of the adsorbent according to embodiment 2 of the invention;

(4) FIG. 4 illustrates the effect of different salt concentrations on the adsorption capacity of the adsorbent according to embodiment 2 of the invention; the K.sub.d value of CMP-EP for U (VI) and competing metal ions before irradiation, after irradiation of 500 kGy in 6 M HNO.sub.3 and after irradiation of 1,000 kGy in 6 M HNO.sub.3; The reusability of CMP-EP.

(5) FIG. 5 illustrates the effect of different salt concentrations on the adsorption capacity of the adsorbent according to embodiment 2 of the invention; the K.sub.d value of CMP-EP for U (VI) and competing metal ions before irradiation, after irradiation of 500 kGy in air and after irradiation of 500 kGy in 6 M HNO.sub.3; The reusability of CMP-EP.

(6) FIG. 6 shows Solid-State NMR spectra and the adsorption capacities of the adsorbent before irradiation, after irradiation of 500 kGy in 6 M HNO.sub.3 and after irradiation of 1,000 kGy in 6 M HNO.sub.3 according to embodiment 3.

(7) FIG. 7 shows Solid-State NMR spectra and the adsorption capacities of the adsorbent before irradiation, after irradiation of 500 kGy in air and after irradiation of 500 kGy in 6 M HNO.sub.3 according to embodiment 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(8) The invention will be further illustrated in more detail with reference to the accompanying drawings and embodiments. It is noted that, the following embodiments only are intended for purposes of illustration, but are not intended to limit the scope of the present invention.

Embodiment 1

(9) Preparation of a Conjugated Microporous Polymer Containing a Phosphate Ester Ligand

(10) In this example, the synthesis of a conjugated microporous polymer modified with a phosphate ligand is exemplarily described. The process is specifically as follows.

(11) To a mixture of 1,3,5-tribromobenzene (790 mg), potassium acetate (1.47 g), and bis(pinacolato)diboron (2.285 g), DMF (20 ml) was added, and N.sub.2 was bubbled therethrough for 20 min. The catalyst tetrakis(triphenylphosphine)palladium (Pd(PPh.sub.3).sub.4, 89 mg) was added, to obtain a mixed solution. The mixed solution was reacted at 100 C. for 24 hrs with stirring, and then cooled to room temperature. Then, the reaction solution was extracted with dichloromethane and water. The organic layer was washed thrice with water, dried over anhydrous sodium sulfate, and then purified by chromatography on silica gel (eluant: 10% EtOAc/petroleum ether), to obtain the monomer TDB as a white solid. The reaction route for the above reaction is shown below:

(12) ##STR00005##

(13) (2) Potassium hydroxide (50 g) was dissolved in water (50 ml), and then 2, 7-dibromofluorene (1.23 g) and tetrabutylammonium bromide (370 mg) were added, followed by 1, 3-dibromopropane (5 ml). The mixture was reacted for 25 min at room temperature with stirring under nitrogen atmosphere, and then extracted twice with dichloromethane. The organic layer was washed with water and then with 1 M HCl and saturated saline, and finally dried over anhydrous magnesium sulfate. After the solvent was removed, the residue was purified by chromatography on silica gel (eluant: 5% CH.sub.2Cl.sub.2/n-hexane) to obtain F-1 as a white solid. F-1 (250 mg) was dispersed in triethyl phosphite (3 ml), and refluxed at 170 C. for 4 hrs under nitrogen atmosphere. Excessive triethyl phosphite was evaporated under reduced pressure, and the resulting solid was purified by chromatography on silica gel (4% EtOH/CH.sub.2Cl.sub.2) to obtain the monomer F2. .sup.1H NMR (CDCl.sub.3, 400 MHz), 7.47 (6H, m), 3.92 (8H, m), 1.47 (4H, m), 1.17 (12H, t, J=7.0 Hz), 0.85 (4H, m). The reaction route for the above reactions was shown as below:

(14) ##STR00006##

(15) (3) TDB (131.8 mg) and F2 (295 mg) were dissolved in DMF (50 ml), and nitrogen was bubbled therethrough for 30 min. A Na.sub.2CO.sub.3 solution (5 ml, 1 M) was added, and then the catalyst tetrakis(triphenylphosphine)palladium (Pd(PPh.sub.3).sub.4, 25 mg) was added. Under nitrogen atmosphere, the mixture was reacted at 90 C. for 24 hrs with stirring and then at 120 C. for 72 hrs with stirring. Then, the reaction solution was cooled, washed thrice respectively with DMF and dichloromethane, dialyzed against water, and then lyophilized, to obtain a ligand-containing conjugated microporous polymer (hereafter referred to as CMP-EP). The reaction route for the above reaction is shown below:

(16) ##STR00007##

(17) The physical and chemical properties of the synthesized CMP-EP were characterized by Solid-State NMR (SSNMR), IR spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results are shown in FIGS. 1-2. FIG. 1(A) is a .sup.13C Solid-State NMR spectrum of CMP-EP, and FIG. 1(B) is a .sup.31P Solid-State NMR spectrum of CMP-EP. As can be seen from FIG. 1, a corresponding peak can be found on the .sup.13C Solid-State NMR spectrum for each carbon atom of the product CMP-EP, and a peak corresponding to the phosphorous in the phosphate ester group can also be found on the .sup.31P Solid-State NMR spectrum of CMP-EP. FIG. 2(A) is an IR spectrum of CMP-EP, and FIG. 2(B) is an X-ray photoelectron spectrum of CMP-EP. In FIG. 2(A), a CC stretching vibration peak occurs at 2940 cm.sup.1; and stretching vibration peaks corresponding to a phosphorus-oxygen double bond and a phosphorus-oxygen single bond in the phosphate ester group occur respectively at 1250 cm.sup.1 and 1030 cm.sup.1. In FIG. 2(B), besides the peaks attributing to O 1s and C 1s, a peak corresponding to P 2p is additionally observed at 133.2 eV. The above results indicate that a conjugated microporous polymer CMP-EP modified with a phosphate ester can be successfully obtained by the above method.

Embodiment 2

(18) Adsorption for Uranium in a Strongly Acidic Environment

(19) (1) CMP-EP (1 mg) prepared in embodiment 1 was weighed and dispersed in uranyl solutions with various concentrations of nitric acid. The adsorbent was removed by filtration after adsorption equilibrium was reached at 25 C. The uranium content in the solution was detected by ICP-MS, and the adsorption efficiency was calculated. Various weights of CMP-EP were weighed and dispersed in a uranyl solution containing 6 M HNO.sub.3. The adsorbent was removed by filtration after adsorption equilibrium was reached. The uranium content in the solution was detected. The results are shown in FIG. 3. FIG. 3(A) illustrates the effect of nitric acid concentration on the adsorption efficiency, and FIG. 3(B) illustrates the effect of the amount of the adsorbent CMP-EP on the adsorption efficiency. FIG. 3 shows that the conjugated microporous polymer modified with a phosphate ester prepared in the invention has an excellent adsorption performance in the acidity range of spent fuel (4-6M HNO.sub.3), with the adsorption efficiency reaching about 90%. With the increase of the amount of the adsorbent used, the adsorption efficiency is increased accordingly.

(20) (2) CMP-EP prepared in embodiment 1 was dispersed in uranyl solutions with various concentrations of sodium nitrate. The adsorbent was removed by filtration after adsorption equilibrium was reached. The uranium content in the solution was detected. FIGS. 4(A), 5(A) illustrate the effect of different salt concentrations on the adsorption capacity of the adsorbent. The results show that the metal salt does not affect the adsorption performance of the adsorbent, and the concentration of the metal salt has little effect on the adsorption performance of the adsorbent.

(21) (3) A mixed ion solution containing the elements U, Zr, Sr, La, Co, Na, Nd, Sm, Cs, Ce, Cr, Zn, Gd, Ba, and Ni (in which the concentration of each ion was about 100 ppm) was formulated by simulating the acidity environment of and the ion species in spent fuel.

(22) A certain weight of CMP-EP was weighed and dispersed in the above mixed ion solution (where the concentration of the adsorbent was 1 mg/mL in the mixed solution). The adsorbent was removed by filtration after adsorption equilibrium was reached (in about 2 hrs). The concentration of each ion in the solution was detected. FIG. 4(B) shows the partition coefficients K.sub.d of CMP-EP for various ions. The results show that the partition coefficient of CMP-EP for uranium is as high as 2375 mL/g, which is much larger than the partition coefficients for other metal ions, and this suggests that CMP-EP can selectively separate and adsorb uranium in a strongly acidic solution with various ions.

(23) (4) Moreover, the recyclability of the material was also investigated. CMP-EP (20 mg) was weighed and dispersed in a uranyl solution containing nitric acid (where in the mixed solution, the concentration of the adsorbent was 1 mg/mL, the concentration of uranyl was 0.04 mmol/L, and the concentration of nitric acid was 6 mol/L). After adsorption equilibrium was reached, the mixed solution was centrifuged (at 4000 rpm for 20 min) to separate the CMP-EP after adsorption. The supernatant was diluted and detected for the adsorption efficiency by ICP-MS. The adsorbent was washed with water three times, added with an eluant (20 mL) (5% NaOH solution or 1 mol/L Na.sub.2CO.sub.3 solution), and stirred overnight. The sample was separated by centrifugation, washed to neutrality with water, and then a uranyl solution was added to for a second adsorption. The above process was repeated 4 times. The result is shown in FIG. 4(C). The recyclability test shows that CMP-EP can effectively maintain the high adsorption efficiency of the adsorbent for uranium after being eluted with a alkaline eluant, and this confirms that the material has excellent recycling performance.

Embodiment 3

(24) Adsorption for Uranium in a Strong-Radiation Environment

(25) CMP-EP prepared in embodiment 1 was irradiated by ray of 500 KGy in air. Also, CMP-EP prepared in embodiment 1 was dispersed in a 6 M nitric acid solution and irradiated by ray of 500 KGy and 1,000 KGy. After irradiation, the radiation resistance of CMP-EP was investigated by solid-state NMR and adsorption experiment as follows. The irradiated CMP-EP was added to a uranyl solution, and the adsorbent was removed by filtration after adsorption equilibrium was reached at 25 C. The adsorption capacity was determined. The results are shown in FIGS. 6-7. FIGS. 6(A), 7(A) show .sup.13C Solid-State NMR spectra of CMP-EP before and after irradiation; FIGS. 6(B), 7(B) show .sup.31P Solid-State NMR spectra of CMP-EP before and after irradiation; and FIGS. 6(C),7(C)shows the adsorption capacities of CMP-EP before and after irradiation. It can be found, by comparison of the Solid-State NMR spectra, the adsorption capacities and the selectivity (FIGS. 4 (B), 5 (B),) of the material before and after irradiation, that CMP-EP has excellent radiation resistance, and the adsorption performance does not change significantly after ray irradiation of 1,000 KGy.

Embodiment 4

(26) Synthesis of a Conjugated Microporous Polymer CMP-N Containing an Amide Ligand

(27) A conjugated microporous polymer CMP-N was obtained by Suzuki coupling polymerization with an amide as a ligand.

(28) (1) Synthesis of Monomer F3

(29) 2, 7-dibromofluorene (3.3 g, 10 mmol) was dispersed in a mixed solution of a 50% aqueous NaOH solution (8 mL) and DMSO (80 mL), and a solution of ethyl bromoacetate (5 g, 30 mmol) in DMSO (10 mL) was added dropwise at 0 C. After addition, the mixed solution was stirred for 12 hrs at room temperature. After the reaction was completed, a 10 N HCl solution (18 ml) was added in an ice bath, and the resulting solution was stirred for 30 min. The precipitate was collected, washed with water three times, and then dried under vacuum. The precipitate was recrystallized in ethanol and dichloromethane, to obtain F3 as a white crystalline solid. The reaction route is shown as below, where R=CH.sub.2CH.sub.3, CH.sub.2CH.sub.2CH.sub.3, or phenyl:

(30) ##STR00008##

(31) (2) Synthesis of CMP-N

(32) TDB (1 eq) prepared in embodiment 1 and F3 (1.5 eq) were dissolved in DMF (50 ml). Nitrogen was bubbled therethrough for 30 min, and 1 M Na.sub.2CO.sub.3 solution (5 ml) and tetrakis(triphenylphosphine)palladium (Pd(PPh.sub.3).sub.4, 3% based on the mole number of the monomer) were added. Under nitrogen atmosphere, the mixture was reacted at 90 C. for 24 hrs with stirring, and then at 120 C. for 72 hrs with stirring. After cooling, the resulting product was washed respectively with DMF (3) and dichloromethane (3), dialyzed against water and then freeze-dried, to obtain a ligand-containing conjugated microporous polymer CMP-N. The reaction route is shown as below:

(33) ##STR00009##

Embodiment 5

(34) Synthesis of a Conjugated Microporous Polymer CMP-CP Containing a Phosphonic Acid Ligand By Post-Modification

(35) A conjugated microporous polymer CMP-CP containing a phosphonic acid ligand was synthesized by post-modification. A reaction route was shown as below.

(36) (1) Synthesis of CMP-C

(37) 2,2-bipyridine (1 eq), bis(1,5-cyclooctadiene)nickel [Ni(COD).sub.2, 1 eq], and 1,5-cyclooctadiene (COD, 1 eq) were dissolved in a mixed solvent of anhydrous THF and 1,4-dioxane, and then TDB and F3 were added. The resulting solution was stirred overnight at room temperature under nitrogen atmosphere. After reaction, a 6 M HCl solution was added dropwise to the solution in an ice bath and stirring is performed for 6 hrs. The precipitate was collected by filtration, washed sequentially with chloroform, THF, methanol, and water, and dried under vacuum to obtain CMP-C.

(38) (2) Synthesis of CMP-CC1

(39) CMP-C (200 mg), paraformaldehyde (0.5 g), hydrochloric acid (37%, 10 ml), phosphonic acid (85%, 2 ml), and acetic acid (3 ml) were sequentially added to an ampoule, sealed, and reacted at 90 C. for three days. After reaction, the precipitate was collected by filtration, washed three times with water and methanol, and then dried under vacuum to obtain CMP-CC1.

(40) (3) Synthesis of CMP-CEP

(41) CMP-CC1 (200 mg) was weighed and dispersed in triethyl phosphite (10 ml). The resulting suspension was refluxed for 24 hrs under nitrogen atmosphere. After reaction, the resulting mixture was cooled to room temperature. The precipitate was collected, washed three times with THF, methanol, and water, and then dried under vacuum, to obtain CMP-CEP.

(42) (4) Synthesis of CMP-CP

(43) CMP-CEP (200 mg) was weighed and dispersed in water (100 g) and concentrated hydrochloric acid (20 ml). The resulting suspension was refluxed for two days under nitrogen atmosphere. The precipitate was collected, washed to neutrality with water, then washed three times with methanol, and dried under vacuum to obtain CMP-CP.

(44) ##STR00010## ##STR00011## ##STR00012##

Embodiment 6

(45) Synthesis of a Conjugated Microporous Polymer CMP-P Containing a Phosphonooxy Compound as a Ligand

(46) A conjugated microporous polymer CMP-P containing a phosphonooxy compound as a ligand was synthesized. A specific reaction route was shown as below.

(47) ##STR00013## ##STR00014##

(48) In this example, a conjugated polymer backbone was synthesized firstly, and then a phosphonooxy compound ligand was attached by post-modification.

(49) (1) Synthesis of F-3

(50) 2,7-dibromofluorene (1 eq) and tetrabutylammonium bromide (2 eq) were added to a mixed solution of DMSO (15 ml), 50% (w/w) NaOH (15 ml) and allyl bromide (10 eq) that was degassed with argon, and the resulting solution was stirred for two hours at room temperature under argon atmosphere. After reaction, tert-butyl methyl ether (125 ml) and deionized water (50 ml) were added, and stirred for 15 min. The organic layer was separated, and the solvent was removed by rotary evaporation, and then the resulting product was purified by chromatography on silica gel (eluting with cyclohexane). The solid was recrystallized in chloroform to give the monomer F-3.

(51) (2) Synthesis of CMP-V

(52) 1,3,5-trialkynylbenzene (1 eq), F-3 (1.5 eq), CuI (10% based on the mole number of F-3) and tetrakis(triphenylphosphine)palladium (5% based on the mole number of F-3) were placed to a two-neck flask, and then DMF (10 ml) and triethyl amine (10 ml) were added. The resulting solution was stirred at 90 C. for 24 hrs under nitrogen atmosphere. After reaction, the reaction solution was cooled to room temperature. The precipitate was collected and washed three times with chloroform, methanol and acetone, rinsed with methanol in a Soxhlet extractor for three days, and then dried under vacuum to give CMP-V.

(53) (3) Synthesis of CMP-P

(54) CMP-V (200 mg) was weighed and dispersed in anhydrous toluene (20 ml), and AIBN (20 mg) and R.sub.2PH(O) (0.05 mol) were added, the resulting solution was stirred at 125 C. for 12 hrs under argon atmosphere. After reaction, the reaction solution was cooled to room temperature. The precipitate was collected, washed three times with ethanol and water, and then dried under vacuum, to obtain CMP-P. The above description is only preferred embodiments of the present invention and not intended to limit the present invention, it should be noted that those of ordinary skill in the art can further make various modifications and variations without departing from the technical principles of the present invention, and these modifications and variations also should be considered to be within the scope of protection of the present invention.