CN106084188A - A kind of preparation method of imidazole radicals porous organic ionic polymer elasticity - Google Patents

Abstract

The invention relates to a preparation method of an imidazole-based porous organic ion polymer. The preparation method is as follows: 1,3-bis(4-bromophenyl)imidazolium bromide and tetrakis(4-bromophenyl)ethylene are added to an organic solvent to dissolve them, then Ni(0) catalyst is added, and the react under conditions. After cooling to room temperature, aqueous HBr solution was added. After the reaction, the resulting precipitate was filtered and washed, and the obtained yellow powder was further extracted with dichloromethane Soxhlet, and vacuum-dried to obtain a powder sample of the imidazole-based porous organic ionic polymer (POP-Im) of the present invention. The tetraphenylethylene unit contained in the imidazole-based porous organic ion polymer provided by the invention has fluorescent properties and can be used to detect the presence of Cr ₂ O ₇ ^2‑ ; the polymer has high enrichment of Cr ₂ O ₇ ^2‑ in water The ability and good selectivity are also suitable for the capture of anions of heavy metal pollutants in water like ionomers and other types.

Description

A kind of preparation method of imidazole-based porous organic ion polymer

technical field

The invention belongs to the field of preparation of porous organic ion polymer materials, in particular to a preparation method of an imidazole-based porous organic ion polymer used for capturing and detecting Cr ₂ O ₇ ^2- in water.

Background technique

The problem of water pollution has attracted much attention, especially the discharge of wastewater containing heavy metal ions. Cr(VI) is widely used in electroplating, printing, dyestuff and leather processing industries. It is a common toxic heavy metal in industrial wastewater. It mainly exists in the form of oxyanions such as chromate and dichromate. Hexavalent chromium is very stable, even at very low concentrations, it can endanger human health after bioaccumulation in the food chain. Various methods for the capture and detection of Cr(VI), such as chemical precipitation, electrolysis, liquid-liquid extraction, liquid membrane separation, activated carbon adsorption, biosorption, and resin treatment, have been reported. But they usually suffer from one or more problems such as low adsorption capacity, slow adsorption process, low selectivity, and poor chemical stability. Therefore, the development of new materials that are suitable for different conditions and can effectively detect and capture Cr(VI) is a problem that needs to be solved urgently.

As an important class of porous materials, Porous Organic Polymers (POPs) are connected by relatively stable covalent bonds. They usually have good chemical stability, simple synthesis, and easy functionalization. Modification and modification at the molecular level. The structure and pore properties of POPs materials can be well adjusted by using the modular synthesis strategy of POPs. For example, by choosing different building blocks and synthesis methods, luminescent groups and other functional groups can be introduced at the molecular level, endowing POPs with unique properties. For cationic framework POPs, positive charges are completely in the host framework, and charge-balanced anions such as halogens exist in the cavities and channels of POPs. The weak electrostatic interaction between the halide ions and the host framework facilitates the dispersion of the cationic POPs in water, thus enabling the rapid exchange of Cr(VI) oxoacid anions with halide ions in water. At the same time, the interaction between the main framework of POPs and different anions will produce different fluorescence properties, and the presence of Cr(VI) oxyacid anions can be detected by fluorescence quenching. Although cationic POPs are widely used in gas adsorption and separation, catalysis, etc., POPs for dichromate ion and chromate ion detection and trapping have not been reported yet.

Contents of the invention

The object of the present invention is to provide a preparation method of imidazolium-based Porous Organic Polymer (POP-Im for short). The polymer has good enrichment ability and high selectivity for Cr ₂ O ₇ ^2- , and can effectively capture Cr ₂ O ₇ ^2- in waste water to meet discharge standards. In addition, the polymer can be used for the fluorescence detection of Cr ₂ O ₇ ^2- .

The imidazole-based porous organic ion polymer of the invention is obtained by polymerizing brominated 1,3-bis(4-bromophenyl)imidazolium salt and tetrakis(4-bromophenyl)ethylene through Yamamoto reaction. Concrete preparation method is as follows:

In the glove box, add 1,3-bis(4-bromophenyl)imidazolium bromide and tetrakis(4-bromophenyl)ethylene to the organic solvent to dissolve completely, then add Ni(0) catalyst, remove from the glove box . React for 10-24 hours under the condition of 60-100°C oil bath. After cooling the resultant to room temperature, HBr aqueous solution was added, and stirring was continued for 6-8 hours. After the reaction is over, filter the resulting precipitate and wash it with N,N -dimethylformamide, methanol, dichloromethane and cyclohexane in sequence, and the obtained yellow powder is further extracted with dichloromethane and dried in vacuo to obtain A powder sample of the imidazole-based porous organic ionomer (POP-Im) described in the present invention.

In the above steps, the molar ratio of tetrakis(4-bromophenyl)ethylene to 1,3-bis(4-bromophenyl)imidazolium bromide is 1:1.0-6.0.

The Ni(0) catalyst described in the above steps is prepared by the following process: in a glove box in an N atmosphere, bis(1,5 _- cyclooctadiene)nickel(0), 1,5-cyclooctadiene Octadiene and 2,2'-bipyridine were added to the organic solvent in a molar ratio of 1:1:1, and shaken for 5-10 minutes to obtain a dark purple turbid solution.

The organic solvent mentioned in the above steps refers to N,N -dimethylformamide or tetrahydrofuran.

In the above-mentioned steps, the amount of Ni(0) catalyst used is the sum of brominated 1,3-bis(4-bromophenyl)imidazolium salt and tetrakis(4-bromobenzene)ethylene in terms of Ni(0) moles. 1 to 1.3 times of that.

The concentration of the HBr aqueous solution in the above steps is 1-5 mol L ^-1 , and the molar amount used is 2-3 times the molar amount of the Ni(0) catalyst.

The imidazole-based porous organic ionic polymer (POP-Im) material provided by the present invention has the following advantages in the detection and separation of Cr ₂ O ₇ ^2- :

1) The tetraphenylethylene unit contained has fluorescence properties, which will produce fluorescence quenching after ion exchange with Cr ₂ O ₇ ^2- in aqueous solution, which can be used to detect the presence of Cr ₂ O ₇ ^2- ;

2) The imidazolium ion group is located in the main skeleton of the ionic polymer, and bromine is used as an anion to make it well dispersed in water and easy to ion exchange with Cr ₂ O ₇ ^2- , thereby effectively capturing Cr ₂ in aqueous solution O ₇ ^2- ;

3) The polymer has good selectivity for Cr ₂ O ₇ ^2- ; the polymer has high enrichment capacity, and can quickly capture Cr ₂ O ₇ ^2- in acidic electroplating wastewater to meet the discharge standard , has good sewage treatment ability, while the analogue without ionic groups has no ability to capture Cr ₂ O ₇ ^2- ;

4) The polymer has good universality in treating wastewater, and is also suitable for the capture of similar ion polymers and other types of anions of heavy metal pollutants in water.

Description of drawings

Fig. 1 is a comparison effect diagram of the Cr ₂ O ₇ ^2- capture ability of POP-Im and POP-TBE respectively prepared in Example 1 of the present invention.

Fig. 2 is the ultraviolet-visible spectrum before and after the ion exchange of diluted K ₂ Cr ₂ O ₇ aqueous solution and excess POP-Im prepared in Example 1.

Fig. 3 is the ultraviolet-visible spectrum before and after the POP-Im ion exchange that electroplating waste water and excess embodiment 1 prepares.

Fig. 4 is a study on the selective capture of Cr ₂ O ₇ ^2- by POP-Im prepared in Example 1 of the present invention.

Fig. 5 is the fluorescence spectrum of POP-Im prepared in Example 1 of the present invention before and after capturing Cr ₂ O ₇ ^2- and the color change under ultraviolet light.

detailed description

In order to have a further understanding of the method of the present invention, a specific description will now be made in conjunction with the accompanying drawings in the form of an embodiment. The following examples are only specific preparation methods of the present invention, and do not limit the scope of the present invention.

In Fig. 1, POP-Im and POP-TBE respectively prepared in Example 1 of the present invention have a comparative effect on the capture ability of Cr ₂ O ₇ ^2- , and the upper curve shows that POP-Im has a high capture capacity for Cr ₂ O ₇ ^2- Efficiency, the lower curve shows that POP-TBE has no capture ability for Cr ₂ O ₇ ^2- .

In Fig. 2, the ultraviolet-visible spectrum (the upper curve is 0 minutes, the middle curve is 2 minutes, and the lower curve is 30 minutes) before and after the excess POP-Im prepared by Example 1 of the present invention and the diluted potassium dichromate aqueous solution ion exchange ), the test results show that after 2 minutes, the Cr ₂ O ₇ ^2- in the water has been completely captured.

In Fig. 3, the ultraviolet-visible spectrum (the upper curve is 0 minutes, the middle curve is 5 minutes, and the lower curve is 30 minutes) before and after the excess POP-Im prepared by Example 1 of the present invention and electroplating wastewater ion exchange, the test results show: After 5 minutes, the Cr ₂ O ₇ ^2- in the electroplating wastewater has been completely captured.

In Fig. 4, the effect diagram of the selective capture of Cr ₂ O ₇ ^2- by excess POP-Im prepared in Example 1 of the present invention shows that the presence of Cl ^- , NO ₃ ^- and SO ₄ ^2- interfering ions has a significant impact on Cr ₂ O ₇ ^{2 -} Capture has no big impact.

In Fig. 5, the fluorescence spectrum of the POP-Im prepared in Example 1 of the present invention before and after capturing Cr ₂ O ₇ ^2- and the color change under the ultraviolet light (a curve is before capture, b curve is after capture), the test results show : After Cr ₂ O ₇ ^2- is captured, the imidazole-based porous organic ion polymer undergoes fluorescence quenching, which can then be used to detect Cr ₂ O ₇ ^2- in water.

Example 1

1. Preparation of imidazole-based porous organic ionic polymer (POP-Im).

In a glove box, mix 1000 mg bis(1,5-cyclooctadiene)nickel(0), 450 μL 1,5-cyclooctadiene, 565 mg 2,2'-bipyridine, 20 mL N,N -bis Methylformamide was added to a 250 mL round bottom flask and shaken for 10 minutes to obtain a dark purple turbid solution.

Dissolve 367 mg of 1,3-bis(4-bromophenyl)imidazolium bromide and 259 mg of tetrakis(4-bromophenyl)ethylene in 20 mL of N,N -dimethylformamide and add to the above dark purple solution , remove from the glove box. Heated in an oil bath at 100°C for 10 hours, cooled to room temperature, added 20 mL of 3 mol L ^-1 HBr aqueous solution, and continued to stir for 8 hours. After the reaction is finished, filter and wash with N,N -dimethylformamide, methanol, dichloromethane and cyclohexane in sequence, and the obtained yellow powder is further extracted with dichloromethane Soxhlet, and dried under vacuum to obtain the present invention The imidazole-based porous organic ion polymer. The sample synthesized in this embodiment is marked as POP-Im. Elemental analysis data (%): C 72.58, H 4.13, N 6.05. ¹³ C NMR solid-state nuclear magnetic data: δ 140, 127. Infrared spectrum data (KBr sheet, cm ^{− 1} ): 3634 (w), 3022 (vw), 1601(s) , 1493 (vs), 1394 (w), 1335 (vw), 1311 (vw), 1285 (vw ), 1249(m), 1185(w), 1105(w), 1066(vw), 1002(m), 951(w), 829(s), 764(m), 697(m), 610(vw ), 512 (vw).

2. Preparation of porous organic polymer (POP-TBE) without imidazole groups.

In a glove box, mix 1000 mg bis(1,5-cyclooctadiene)nickel(0), 450 μL 1,5-cyclooctadiene, 565 mg 2,2'-bipyridine, 20 mL N,N -bis Add methylformamide into a 250 mL round bottom flask and shake for 5-10 minutes to obtain a deep purple turbid solution.

Dissolve 515 mg of tetrakis(4-bromophenyl)ethylene bromide in 20 mL of N,N -dimethylformamide and add it to the above dark purple solution, plug it with a rubber stopper, and remove it from the glove box. Heat in a pre-heated 100°C oil bath for 10 hours, and after cooling to room temperature, add 20 mL of 3 mol L ^-1 HBr aqueous solution, and continue stirring for 8 hours. After the reaction, filter and wash with N,N -dimethylformamide, methanol, dichloromethane and cyclohexane successively, the obtained light yellow powder is further extracted with dichloromethane Soxhlet, heated and dried under vacuum to obtain Porous organic polymers containing imidazole groups. The sample synthesized through the above steps is labeled as POP-TBE. Elemental analysis data (%): C 95.09, H 4.91. ¹³ C NMR solid-state nuclear magnetic data: δ 140, 129, 124. Infrared spectrum data (KBr sheet, cm ^-1 ): 3662 (vw), 3025 (s), 2938 (w), 2859(vw), 1903 (vw), 1683 (m), 1609 (m), 1492 (vs ), 1449 (vw), 1396 (m), 1272(w), 1186 (vw), 1116 (w), 1080 (vw), 1004 (s), 971 (vw), 805 (vs), 749(s ), 701 (m), 621 (vw), 581 (w), 501 (w).

3. Capability test of Cr ₂ O ₇ ^2- .

1) The capture ability test of Cr ₂ O ₇ ^2- under the equivalent ratio of imidazole and chromium

The POP-Im and POP-TBE prepared in Example 1 were respectively immersed in an equivalent amount of potassium dichromate aqueous solution and shaken at room temperature. The ion exchange process can be monitored by liquid UV-Vis spectroscopy based on the characteristic absorption peak of Cr ₂ O ₇ ^2- at 257 nm. Within a certain period of time, draw 1.0 mL of potassium dichromate aqueous solution, dilute it with 4.0 mL of distilled water, and test the ultraviolet-visible absorption intensity. The test results are shown in Figure 1 of the description.

2) Enrichment experiment test

Immerse the excess POP-Im prepared in Example 1 into the diluted potassium dichromate aqueous solution, shake at room temperature, after a certain period of time, filter the turbid liquid, and absorb the filtrate to test the ultraviolet-visible absorption intensity. The test results are shown in Figure 2 of the description.

3) Test in electroplating wastewater treatment

Immerse the excess POP-Im prepared in Example 1 into 3 mL of electroplating wastewater, shake it at room temperature, filter the turbid solution after a certain period of time, and absorb the filtrate to test the ultraviolet-visible absorption intensity. The test results are shown in Figure 3 of the description.

4) Selective experimental test

Immerse the POP-Im prepared in Example 1 into an aqueous solution containing an equivalent amount of dichromate and n times as many interfering ions (n=2, 4, 8, 12, 20, 40), and the interfering ions are Cl ^- , Selective exchange effect of NO ₃ ^- and SO ₄ ^2- on Cr ₂ O ₇ ^2- . The test results are shown in Figure 4 of the description.

Example 2

In the glove box, add 1000 mg bis(1,5-cyclooctadiene)nickel(0), 450 μL 1,5-cyclooctadiene, 565 mg 2,2'-bipyridine, 20 mL THF to 250 mL round-bottomed flask, shake for 5-min to obtain dark purple turbid solution.

243mg of 1,3-bis(4-bromophenyl)imidazolium bromide and 343mg of tetrakis(4-bromophenyl)ethylene were added to the above dark purple solution, and removed from the glove box. Heated in an oil bath at 60°C for 10 hours, cooled to room temperature, added 20 mL of 3 mol L ^-1 HBr aqueous solution, and continued to stir for 6 hours. After the reaction is finished, filter and wash with N,N -dimethylformamide, methanol, dichloromethane and cyclohexane in sequence, and the obtained yellow powder is further extracted with dichloromethane Soxhlet, and dried under vacuum to obtain the present invention The imidazole-based porous organic ion polymer.

Example 3

In a glove box, mix 1000 mg bis(1,5-cyclooctadiene)nickel(0), 450 μL 1,5-cyclooctadiene, 565 mg 2,2'-bipyridine, 20 mL N,N -bis Add methylformamide into a 250 mL round bottom flask and shake for 5-10 minutes to obtain a dark purple turbid solution.

147mg of 1,3-bis(4-bromophenyl)imidazolium bromide and 414mg of tetrakis(4-bromophenyl)ethylene were added to the above dark purple solution and removed from the glove box. Heated in an oil bath at 80°C for 18 hours, cooled to room temperature, added 20 mL of 3 mol L ^-1 HBr aqueous solution, and continued to stir for 7 hours. After the reaction is finished, filter and wash with N,N -dimethylformamide, methanol, dichloromethane and cyclohexane in sequence, and the obtained yellow powder is further extracted with dichloromethane Soxhlet, and dried under vacuum to obtain the present invention The imidazole-based porous organic ion polymer.

Example 4

In the glove box, add 1000 mg bis(1,5-cyclooctadiene)nickel(0), 450 μL 1,5-cyclooctadiene, 565 mg 2,2'-bipyridine, 20 mL THF to 250 mL round bottom flask, shake for 5-10 minutes to obtain dark purple turbid liquid.

243mg of 1,3-bis(4-bromophenyl)imidazolium bromide and 343mg of tetrakis(4-bromophenyl)ethylene were added to the above dark purple solution, and removed from the glove box. Heated in an oil bath at 60°C for 20 hours, cooled to room temperature, added 20 mL of 3 mol L ^-1 HBr aqueous solution, and continued to stir for 6 hours. After the reaction is finished, filter and wash with N,N -dimethylformamide, methanol, dichloromethane and cyclohexane in sequence, and the obtained yellow powder is further extracted with dichloromethane Soxhlet, and dried under vacuum to obtain the present invention The imidazole-based porous organic ion polymer.

The above descriptions are only representative embodiments of the present invention, and all modifications and changes made within the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (6)

1. a preparation method of imidazole-based porous organic ionic polymer is characterized in that described method is as follows: In the glove box, add 1,3-bis(4-bromophenyl)imidazolium bromide and tetrakis(4-bromophenyl)ethylene to the organic solvent to dissolve completely, then add Ni(0) catalyst, remove from the glove box ;React for 10~24 hours under the condition of 60~100℃ oil bath; after cooling the product to room temperature, add HBr aqueous solution, and continue to stir for 6~8 hours; , washed with N -dimethylformamide, methanol, dichloromethane and cyclohexane, and the obtained yellow powder was further extracted with dichloromethane Soxhlet, and vacuum-dried to obtain the imidazole-based porous organic ion polymer. 2. the preparation method of a kind of imidazole-based porous organic ionic polymer according to claim 1 is characterized in that tetrakis (4-bromophenyl) ethylene and brominated 1,3-bis (4-bromobenzene) imidazolium salt The molar ratio is 1:1.0～6.0. 3. the preparation method of a kind of imidazole-based porous organic ionic polymer according to claim 1 is characterized in that Ni(0) catalyst consumption is brominated 1,3-bis(4) in terms of Ni(0) moles - 1 to 1.3 times the sum of the moles of substituted bromine in bromophenyl) imidazolium salt and tetrakis (4-bromophenyl) ethylene. 4. the preparation method of a kind of imidazole-based porous organic ionic polymer according to claim 1 is characterized in that the Ni(0) catalyst described in the above-mentioned steps is prepared by the following process: in a glove box under N ₂ In the atmosphere, bis(1,5-cyclooctadiene)nickel(0), 1,5-cyclooctadiene and 2,2'-bipyridine were added to the organic In the solvent, shake for 5-10 minutes to obtain a deep purple turbid solution. 5. the preparation method of a kind of imidazole-based porous organic ion polymer according to claim 1 is characterized in that described organic solvent refers to N,N -dimethylformamide or tetrahydrofuran. 6. The preparation method of a kind of imidazole-based porous organic ionic polymer according to claim 1, characterized in that the HBr aqueous solution has a concentration of 1 to 5 mol L ^-1 and the molar amount used is Ni(0) 2 to 3 times the molar weight of the catalyst.