Supramolecular material with capability of efficiently adsorbing and separating benzene as well as preparation method and application of supramolecular material

Abstract

The invention discloses a supramolecular material with efficient benzene adsorption and separation capacity and a preparation method and application thereof, and the preparation process of the supramolecular material comprises the following steps: synthesizing three ligands L-H, L-OCH3 and L-F, and then assembling with metal Zn (II) to synthesize novel metal organic supramolecular cages: T-H, T-OCH3 and T-F. The supermolecular cages show unique selective adsorption characteristics on benzene molecules, and a novel solution is provided for effective separation of benzene in a mixed system. The invention not only opens up a brand new path for designing a benzene adsorbing material with high performance and high selectivity, but also plays a role in efficiently separating benzene from cyclohexane in the field of industrial chemistry so as to improve the production efficiency, and contributes important power to promoting the progress and sustainable development of related industries.

Description

Technical Field

[0001] The invention relates to the field of supramolecular materials, and in particular to a supramolecular material with high-efficiency benzene adsorption and separation capability, and a preparation method and application thereof. Background Art

[0002] Benzene is a core raw material in the manufacture of nylon, synthetic rubber, pesticides and medicines, and its hydrogenated derivative cyclohexane is a key cornerstone in the production of nylon fibers. However, the traditional benzene separation process not only consumes a lot of energy, but also has a significant carbon footprint and will have an impact on the environment. What is more worrying is that benzene, as a member of the volatile organic compounds, has been classified as a human carcinogen, and its safe handling is particularly important. In previous studies, porous materials and non-porous adaptive crystals have shown the potential for effective capture and separation of benzene, but the operational complexity and processing difficulties faced in practical applications have limited their widespread promotion. For a long time, non-porous amorphous solids have been marginalized due to their inferior performance compared to porous adsorbents, which has greatly hindered their practical application in this field.

[0003] Metal-organic cages (MOCs), as a class of adsorbents with well-defined shapes and sizes, have shown great potential in the field of benzene adsorption. However, MOCs still face many challenges in practical applications, such as limited adsorption capacity due to low binding rate and easy dissociation under high temperature or low concentration conditions, which seriously restrict their widespread application. In recent years, nonporous amorphous metal-organic supramolecular materials have gradually attracted attention as a new type of adsorbent material. Their unique rigidity and polyaromatic structure can form stable non-covalent bonds with benzene, such as [CH··π] interactions and [π··π] stacking, providing a strong driving force for the efficient adsorption and separation of benzene. In addition, their internal cavities and crack and channel structures provide more possibilities for the accommodation of guest molecules, further enhancing their adsorption performance. However, nonporous amorphous metal-organic supramolecular materials with high adsorption capacity and high selectivity are currently in the early stages of research and development, and their potential in practical applications needs to be further explored.

[0004] Compared with traditional benzene purification technology, adsorption method has significant advantages in capturing and separating benzene in mixtures due to its simplicity, speed, low energy consumption, safety, stability and environmental protection. Therefore, the development and application of non-porous amorphous solid metal-organic cage materials with high adsorption capacity and high selectivity will not only break through the limitations of traditional benzene separation technology, but also provide new possibilities for achieving environmentally friendly and efficient benzene separation and recovery. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention aims to provide a supramolecular material with high efficiency in benzene adsorption and separation, a preparation method and its application in benzene adsorption and separation, and adopts new components, proportions and processes to prepare a supramolecular material containing unsubstituted tpy-Zn 2+ -tpy group, methoxy-modified tpy-Zn 2+ -tpy group and fluorine-modified tpy-Zn 2+ When the supramolecular materials TH, T-OCH3, and TF with -tpy groups are used as adsorbents, they can efficiently adsorb and separate benzene from a mixture of equimolar amounts of benzene and cyclohexane, and have good recyclability and high stability. This expands the application range of 3D supramolecular materials and also provides a new direction for the separation and purification of mixtures with similar boiling points, thereby further realizing industrial preparation and application to solve the above-mentioned technical problems.

[0006] The purpose of the present invention is achieved by the following technical solutions:

[0007] In a first aspect, the present invention provides a supramolecular material having the ability to efficiently adsorb and separate benzene, wherein the unit structure of the supramolecular material is as shown in formula (I), formula (II) and formula (III):

[0008]

[0009] In a second aspect, the present invention provides a method for preparing a supramolecular material having the ability to efficiently adsorb and separate benzene, comprising the following steps:

[0010] (1) Preparation of terpyridine metal organic ligands as shown in formula (IV) to formula (VI):

[0011]

[0012] (2) adding a solvent to the three ligands prepared in step (1) respectively to dissolve them, then dropping a metal salt solution, heating to react, adding an anion replacement agent after the reaction is completed, filtering to obtain a precipitate, and then assembling to synthesize the unsubstituted tpy-Zn 2+ -tpy group supramolecular materials, methoxy-modified tpy-Zn 2+ -tpy group-based supramolecular materials and fluorine-modified tpy-Zn 2+ -tpy group-containing supramolecular materials.

[0013] Preferably, the terpyridine metal organic ligand obtained in step (1) is a three-arm terpyridine ligand, which has a unique geometric angle and configuration and can spontaneously assemble with metal Zn ions in a solution system into a precise, ordered and unique structure.

[0014] Preferably, in step (2), the anion displacer is ammonium hexafluorophosphate. The anion displacer is used to displace anions such as nitrate or bistrifluoromethanesulfonyl imide introduced during the assembly process. Under the action of ammonium hexafluorophosphate, the supramolecular material can be better precipitated from the solvent, which is beneficial to the subsequent separation and purification of the precipitate.

[0015] Preferably, in step (2), the solvent is at least one of alcohol, chloroform and ether.

[0016] More preferably, in step (2), the solvent is a mixture of alcohol and chloroform.

[0017] More preferably, in step (2), the solvent is a mixed solution of methanol and chloroform, wherein the volume ratio of methanol to chloroform is 2: 1. The mixed solvent of methanol and chloroform plays an important role in the formation of the supramolecular material, the terpyridine ligand has good solubility in the mixed solvent of chloroform and methanol, and the generated supramolecular material can also be well dissolved in acetonitrile.

[0018] Preferably, in step (2), the heating reaction temperature is 40-70° C., and the reaction time is 5-10 h.

[0019] More preferably, in step (2), the heating reaction temperature is 45-55° C., and the reaction time is 6-10 h.

[0020] In a third aspect, the present invention provides a supramolecular material having the ability to efficiently adsorb and separate benzene. The supramolecular material is a tpy-Zn 2+ The supramolecular cage of -tpy group can be used as an adsorbent for benzene and can efficiently and selectively adsorb and separate benzene in a mixed phase in an atmosphere of equimolar benzene and cyclohexane.

[0021] Preferably, the tpy-Zn 2+ The tpy in the -tpy group may be unsubstituted, methoxy-substituted or fluorine-substituted.

[0022] Preferably, the tpy-Zn 2+ The supramolecular materials of -tpy group are TH (Formula (IV)), T-OCH3 (Formula (V)), and TF (Formula (VI)).

[0023] Preferably, the supramolecular material is used for the adsorption separation of benzene and cyclohexane as follows: benzene in a mixed phase can be efficiently and selectively adsorbed and separated in an atmosphere of equimolar benzene and cyclohexane.

[0024] Preferably, the supramolecular material can form non-covalent bonds with aromatic structures such as benzene, such as [CH··π] interactions and [π··π] stacking, which serve as driving forces for adsorption and separation.

[0025] Preferably, the supramolecular material has a high benzene adsorption capacity at 298K in a powder state. For example, the benzene adsorption capacity of the supramolecular material TF is 110 cm 3 / g, supramolecular material TH: 120cm 3 / g, supramolecular material T-OCH3: 70cm 3 / g.

[0026] Preferably, the supramolecular material will not be completely released during desorption even under reduced pressure, and will still contain about 40 cm 3 / g of benzene, which indicates that the storage of benzene in supramolecular materials is particularly stable.

[0027] Preferably, the powders of the supramolecular material TF and supramolecular material TH have high selectivity when separating a benzene / cyclohexane mixture in a gas phase. The purity of the supramolecular material TF can reach 99.5%, and the purity of the supramolecular material TH can reach 93.83%.

[0028] The beneficial effects of the present invention are:

[0029] 1. The present invention first provides an unsubstituted tpy-Zn 2+ -tpy group, methoxy-modified tpy-Zn 2+ -tpy group and fluorine-modified tpy-Zn 2+ The application of supramolecular materials TH, T-OCH3, and TF with -tpy groups as adsorbents for efficient adsorption and separation of benzene, and the use of three different modified ligands to coordinate with transition metal Zn to obtain unsubstituted tpy-Zn 2+ -tpy group, methoxy-modified tpy-Zn 2+ -tpy group and fluorine-modified tpy-Zn 2+ -tpy group supramolecular materials TH, T-OCH3, TF preparation method, second supramolecular materials can be able to form non-covalent bonds such as [CH··π] interaction, [π··π] stacking with aromatic structures such as benzene, as the driving force for adsorption and separation. These supramolecular materials have shown strong targeting in the adsorption and storage of benzene, among which the highest adsorption capacity of metal cage TH for benzene can reach 120cm 3 / g. Supplement the vacancy state of the current non-porous amorphous metal organic cages with high adsorption capacity and selectivity, and achieve efficient adsorption and separation of benzene and cyclohexane.

[0030] 2. The three unsubstituted tpy-Zn 2+ -tpy group, methoxy-modified tpy-Zn 2+-tpy group and fluorine-modified tpy-Zn 2+ The method of preparing supramolecular materials TH, T-OCH3, and TF with -tpy groups is to construct them by self-assembly guided by coordination bonds of terpyridine organic ligands modified with different groups and transition metal Zn, and the structure is stable.

[0031] 3. The three supramolecular materials provided by the present invention studied the adsorption and separation effects of supramolecular materials containing different groups on benzene and cyclohexane, further highlighting that the supramolecular material TH has an excellent ability to adsorb benzene.

[0032] 4. The supramolecular materials TF and TH provided by the present invention have high selectivity in separating benzene / cyclohexane mixture in gas phase. The purity of benzene after separation reaches 99.5% and 93.83% respectively, which provides a new idea for designing benzene adsorbents with high performance and high selectivity.

[0033] 5. The preparation method of the supramolecular material provided by the present invention is simple, the reaction conditions are mild, and it is conducive to large-scale industrial production. The desired supramolecular material can be assembled and synthesized by reacting a specific ligand with a metal salt solution and then adding an anion replacement agent.

[0034] 6. The supramolecular material provided by this invention not only opens up a new path for designing high-performance and highly selective benzene adsorption materials, but will also play a role in the efficient separation of benzene and cyclohexane in the field of industrial chemistry, thereby improving production efficiency, and make important contributions to promoting the progress and sustainable development of related industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention is further described using the accompanying drawings, but the embodiments in the accompanying drawings do not constitute any limitation to the present invention. A person skilled in the art can obtain other drawings based on the following drawings without creative work.

[0036] Figure 1 Flow chart for preparing ligand L-OCH3 of the present invention;

[0037] Figure 2 This is a flow chart of preparing ligand LF in Example 3 of the present invention;

[0038] Figure 3 The ESI-MS and TWIM-MS spectra of supramolecular T-OCH3 of Example 2 of the present invention;

[0039] Figure 4 This is the one-dimensional NMR spectrum of the intermediate when preparing the ligand LF in Example 3 of the present invention;

[0040] Figure 5The one-dimensional NMR spectrum of the ligand LF prepared in Example 3 of the present invention;

[0041] Figure 6 The one-dimensional NMR spectrum of the supramolecular material TF prepared in Example 3 of the present invention;

[0042] Figure 7 The ESI-MS and TWIM-MS spectra of supramolecular TF of Example 3 of the present invention;

[0043] Figure 8 The nitrogen adsorption spectra of supramolecular TH, T-OCH3 and TF prepared in Example 4 of the present invention;

[0044] Fig. 9 XRD patterns of supramolecular TH, T-OCH3 and TF prepared in Example 4 of the present invention;

[0045] Fig.10 The adsorption-desorption spectra of supramolecular TH, T-OCH3 and TF prepared in Examples 1-3 of the present invention on benzene and cyclohexane are shown;

[0046] Fig.11 The one-dimensional NMR spectra of the adsorption of benzene and cyclohexane by the supramolecular TH, T-OCH3 and TF prepared in Examples 1-3 of the present invention;

[0047] Fig.12 The variation of the adsorption amount of the supramolecular TH, T-OCH3 and TF prepared in Examples 1-3 of the present invention on the vapor of an equimolar mixture of benzene and cyclohexane over time;

[0048] Fig.13 The relative absorption of benzene and cyclohexane adsorbed on the supramolecular materials TH, T-OCH3 and TF prepared in Examples 1-3 of the present invention for 6 hours by headspace gas chromatography is calculated.

[0049] Fig.14 This is a cyclic test of the supramolecular material TH prepared in Example 1 of the present invention on the adsorption of benzene;

[0050] Fig.15 This is a cyclic test of the supramolecular material TF prepared in Example 3 of the present invention on the adsorption of benzene;

[0051] Fig.16 The crystal structure of the supramolecular materials T-OCH3 and TF obtained in benzene and the analysis of the interaction force with benzene obtained in Example 2-3 of the present invention;

[0052] Fig.17 The crystal structure of the supramolecular material TH prepared in Example 1 of the present invention in benzene and the analysis of the interaction force with benzene.

[0053] Fig.18 Schematic diagram of the adsorption of benzene by the supramolecular materials TH, T-OCH3 or TF prepared in Examples 1-3 of the present invention. DETAILED DESCRIPTION

[0054] The technical solution of the present invention is described below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combination step or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to limit the scope of the present invention. The change or adjustment of the relative relationship thereof shall also be regarded as the scope of the present invention without substantially changing the technical content.

[0055] In order to better understand the above technical scheme, the exemplary embodiments of the present invention are described in more detail below. Although exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0056] The present invention will be further described below in conjunction with the following examples.

[0057] The three unsubstituted tpy-Zn compounds provided in the embodiments of the present invention are 2+ -tpy group, methoxy-modified tpy-Zn 2 + -tpy group and fluorine-modified tpy-Zn 2+ -tpy group supramolecular materials TH, T-OCH3, TF as adsorbents for efficient adsorption and separation of benzene and cyclohexane, including three containing unsubstituted tpy-Zn 2+ -tpy group, methoxy-modified tpy-Zn 2+ -tpy group and fluorine-modified tpy-Zn 2+ -tpy group metal organic supramolecular materials TH, T-OCH3, TF, based on different groups modified ligands and the same transition metal Zn assembled into the same configuration of supramolecular materials, the supramolecular materials have a unit structure shown in formula (I) to formula (III):

[0058]

[0059] The above three contain unsubstituted tpy-Zn 2+-tpy group, methoxy-modified tpy-Zn 2+ -tpy group and fluorine-modified tpy-Zn 2+ The preparation methods of supramolecular materials TH, T-OCH3, and TF containing -tpy groups are shown in Examples 1-3, respectively. The synthesis methods of ligands LH and L-OCH3 are similar and have been patented. LF is described in Example 3. Figure 1-17 And a plurality of specific embodiments are further described to further describe the technical solution of the present invention.

[0060] Embodiment 1:

[0061]

[0062] The preparation method of supramolecular TH comprises:

[0063] The ligand LH (12 mg, 9.7 μmol) was dissolved in CHCl3 (6 mL), MeOH (6 mL) was added, and the solution was heated to 60°C. Zn(NO3)2·6H2O (4.33 mg, 14.5 μmol) in MeOH (1 mg / mL) was added to ensure that no precipitation was precipitated, and the mixture was stirred at 55°C for 6 h. After the reaction was completed, the mixture was cooled to room temperature, and 10 times excess NH4PF6 was added for anion exchange to form a precipitate, which was stirred for 30 min. After the conversion was complete, the solution was transferred to a 15 mL centrifuge tube for centrifugation, the solid was retained, the supernatant was discarded, distilled water and a small amount of MeOH were added, the mixed solution was fully shaken and centrifuged again, and the above operation was repeated 3 times, and the solid was vacuum dried to obtain the product (16.00 mg, 98.0%).

[0064] ESI-TOF(m / z):864.53[M-7PF6 - ] 7+ (calcd m / z:864.53),1029.26[M-6PF6 - ] 6+ (calcd m / z:1029.26),1264.69[M-5PF6 - ] 5+ (calcd m / z:1264.69),1616.35[M-4PF6 - ] 4+ (calcd m / z:1616.35),2203.47[M-3PF6 - ] 3+ (calcd m / z:2203.47); 1 H NMR(500MHz,CD3OD)δ8.87(s,18H,Tpy-H 3’5’),8.48(d,J=8.0Hz,18H,Tpy-H b ),8.31(d,J=8.0Hz,18H,Tpy-H 3 ,3” ),7.85(t,18H,Tpy-H 4,4” ),7.77(d,J=8.0Hz,18H,Tpy-H a ),7.69(d,J=5.0Hz,18H,Tpy-H 6,6” ),7.55(d,J=8.0Hz,9H,Ph-H c ),7.43–7.39(m,18H,Ph-H d,e ),7.33(d,J=8.5Hz,9H,Ph-H f ),7.17–7.13(m,18H,Tpy-H 5,5” ),7.04(s,9H,Ph-H g )

[0065] Embodiment 2:

[0066]

[0067] The preparation method of supramolecular T-OCH3 comprises:

[0068] The ligand L-OCH3 (12 mg, 9.1 μmol) was dissolved in CHCl3 (6 mL), MeOH (6 mL) was added, and the solution was heated to 60°C. Zn(NO3)2·6H2O (4.06 mg, 13.6 μmol) in MeOH (12 mL) was added without precipitation, and the mixture was stirred for 8 hours, and then cooled to room temperature. 10-fold excess NH4PF6 was added for anion exchange, and the precipitate was washed with water and methanol and centrifuged three times, and dried in a vacuum drying oven to obtain a solid product (12.5 mg, 95.2%).

[0069] ESI-TOF(m / z):913.03[M-7PF6 - ] 7+ (calcd m / z:913.03),1089.35[M-6PF6 - ] 6+ (calcd m / z:1089.35),1336.21[M-5PF6 - ] 5+ (calcd m / z:1336.21),1706.52[M-4PF6 - ] 4+(calcd m / z:1706.52),2323.69[M-3PF6 - ] 3+ (calcd m / z:2323.69); 1 H NMR(500MHz,CD3OD,300K,ppm)δ8.9(s,24H,tpy-H 3’,5’ ),8.50-8.48(d,24H,Ph-H a ),8.36-8.34(d,24H,tpy-H 3 ,3” ),7.89-7.86(t,24H,tpy-H 4,4” ),7.79-7.77(d,24H,Ph-H b ),7.27-7.25(d,12H,tpy-H 6 ,6” ),7.19-7.17(t,24H,Ph-H d ),7.07-7.06(d,12H,Ph-H 5,5” ),7.01-6.99(d,24H,Ph-H c ),6.91(s,24H,Ph-H c ),3.82(s,36H,Ph-H f ).

[0070] Embodiment 3:

[0071] The preparation method of supramolecular TF includes:

[0072] (1) Synthesis of intermediate 1:

[0073]

[0074] 2-Bromo-5-fluoroacetophenone (1.00 g, 4.60 mmol) was added to a three-necked round-bottom flask, and trifluoromethanesulfonic acid (0.041 mL, 0.460 mmol) was then added dropwise to the stirred solution. Stirring and heating to 140 ° C was carried out under nitrogen protection for 6 hours. The black mixture was cooled to ambient temperature, quenched by adding water (20 mL), and the mixture was extracted with CH2Cl2 (3×20 mL). The combined organic layer was washed with brine (20 mL), dried over MgSO4, filtered and concentrated. The residue was purified by column chromatography on silica gel (n-hexane / ethyl acetate, 95:5) to obtain yellow solid intermediate 1 (0.50 g, 55%).

[0075] 1H NMR (500MHz, CDCl3) δ7.65 (d, J = 5.0Hz, 1H, Ph-H d ),7.49(s,1H,Ph-H a ),7.19(d,J=9.0Hz,1H,Ph-H d ),6.98(t,J=8.0Hz,1H,Ph-H c ).

[0076] (2) Synthesis of ligand LF:

[0077]

[0078] In a round-bottom flask, intermediate 1 (504 mg, 1.05 mmol), para-phenylboronic acid terpyridine (1.59 g, 4.50 mmol), Pd(PPh3)2Cl2 (123.3 mg, 0.15 mmol) and Na2CO3 (810 mg, 9.0 mmol) were added, and then 75 mL of toluene, 20 mL of water and 15 mL of tert-butyl alcohol were added. The mixture was stirred at 85°C for 3 days. After cooling to room temperature, the mixture was extracted with CH2Cl2 and saturated brine and rotary evaporated. The red solid mixture was purified by dry column chromatography (silica gel) and recrystallized with CH2Cl2 and CH3OH to obtain 932 mg of the product ligand LF as a white solid (yield 73%). 1 H NMR(500MHz,CDCl3)δ8.78(s,2H,tpy-H 3’,5’ ),8.60(d,J=8.0Hz,2H,tpy-H 6.6” ),8.54(d,J=5.0Hz,2H,tpy-H 3,3” ),8.05(d,J=8.0Hz,2H,Ph-H a ),7.80(t,J=8.0Hz,2H,tpy-H 4,4” ),7.35–7.31(m,1H,Ph-H c ),7.25–7.21(m,4H,tpy-H 5,5” ,Ph-H b ),6.96(t,J=9.5Hz,1H,Ph-H d ),6.84(s,1H,Ph-H e ),6.54(d,J=9.5Hz,1H,Ph-H f ).

[0079] (3) Synthesis of supramolecular TF:

[0080]

[0081] The ligand LF (12 mg, 9.4 μmol) was dissolved in CHCl3 (6 mL), MeOH (6 mL) was added, and the solution was heated to 60 ° C. Zn (NO3) 2·6H2O (4.17 mg, 14.0 μmol) in MeOH (1 mg / mL) was added without precipitation, and stirred for 8 hours, and then cooled to room temperature. A 10-fold excess of NH4PF6 was added for anion exchange, and the precipitate was washed with water and methanol and centrifuged three times, and dried in a vacuum drying oven to obtain a solid product (15.68 mg, 97.0%). ESI-TOF (m / z): 892.37 [M-7PF6 - ] 7+ (calcd m / z:892.37),1065.27[M-6PF6 - ] 6+ (calcd m / z:1065.27),1307.33[M-5PF6 - ] 5+ (calcd m / z:1307.33),1670.41[M-4PF6 - ] 4+ (calcd m / z:1670.41),2275.55[M-3PF6 - ] 3+ (calcd m / z:2275.55); 1 H NMR(500MHz,CD3OD,300K,ppm)δ8.88(s,2H,tpy-H 3’,5’ ),8.49(d,2H,J=9.0Hz,tpy-H 3,3” ),8.33(d,2H,J=8.0Hz,Ph-H a ),7.86(t,2H,J=8.0Hz,tpy-H 4,4” ),7.72(d,1H,J=10.0Hz,Ph-H e ),7.68(d,2H,J=6.0Hz,tpy-H 6,6” ),7.59–7.54(m,1H,Ph-H d ),7.21–7.13(m,4H,tpy-H 5,5” ,Ph-H b ),7.11(d,J=8.7Hz,Ph-H d ),7.07(s)

[0082] Experimental Example 4

[0083] The performance and application of the supramolecular materials prepared in Examples 1-3 were tested and verified:

[0084] (1) Porosity, crystallinity, thermal stability and hydrophobicity of supramolecular materials:

[0085] Nitrogen adsorption studies were performed at 77 K to evaluate the porosity of the synthesized samples after evacuation at 120 °C under high vacuum for 24 h. A typical type III isotherm was obtained and showed a low apparent Brunauer-Emmett-Teller surface area (SBET) of 13.98 m 2 / g(TF),11.49m 2 / g(TH) and 25.74m 2 / g(T-OCH3), indicating that there are no pores in MOCs solid. Next, the solid samples of these supramolecular materials were analyzed by powder X-ray diffraction (PXRD), and the results showed only a weak broadening signal, indicating that they have amorphous properties. In addition, the contact angle test also showed that the supramolecular materials have good hydrophobicity ( Figure 8 , Fig. 9 ).

[0086] (2) Adsorption of benzene and cyclohexane

[0087] Through the adsorption and desorption test of benzene and cyclohexane, the specific adsorption and storage capacity of the two can be quantitatively analyzed. Under the saturated vapor pressure of 298K, the adsorption gravity values ​​of TF, TH and T-OCH3 for benzene are 110cm 3 / g, 120cm 3 / g, 70cm 3 / g. From Fig.10 It can be clearly seen that the adsorption capacity of the three for benzene is much greater than that for cyclohexane. The adsorption capacity of TF and TH for benzene is close to Carboxen1000 (a commercial carbon molecular sieve used for separation of light hydrocarbons in gas chromatography columns and volatile organic compound sampling in air analysis). This also shows that these supramolecular materials can be used as an adsorption material for both at standard temperature and pressure, and because they show a stronger storage capacity for benzene, this material is expected to play a role in the application of separation of benzene and cyclohexane ( Fig.10 ).

[0088] In addition, the adsorption and storage capacity of benzene and cyclohexane at room temperature and pressure were investigated. The specific operation was as follows: 10 mg of the sample was accurately weighed, ground in a mortar, and evenly spread on the bottom of a 1.5 mL vial. The sample was activated at 180 ° C in a vacuum state for 6 hours to remove impurities in the adsorbent and make the adsorbent surface more active. After the activation was completed, 2 mL of cyclohexane and 1.86 mL of benzene (the amount of substance was 1:1) were added to a 20 mL large bottle, and the 1.5 mL vial containing the adsorbent sample after activation was placed in a 20 mL large bottle for 4 hours of adsorption. Through nuclear 1 HNMR characterizes the selective adsorption performance of the adsorbent for benzene. It can be seen from the figure that before adsorption, the nuclear magnetic resonance of MOCs only has the peak of the metal organic cage itself, at 7.33ppm (benzene in CD3OD solvent). 1 HNMR peak position) and 1.45 ppm (cyclohexane in CD3OD solvent 1 There are no peaks at the HNMR peak position, and after adsorption, obvious peaks can be observed at 1.45ppm and 7.33ppm, indicating that the supramolecular material can be used as an adsorbent to capture both volatile organic compounds ( Fig.11 ). 1 HNMR experiments show that the adsorbent has the ability to capture both benzene and cyclohexane, but its storage capacity for benzene is stronger than that for cyclohexane, and it can be used as an adsorbent for selective adsorption and separation of benzene.

[0089] We further conducted a solid-benzene vapor adsorption experiment with time. The adsorption saturation of the three supramolecular materials was reached at about 4.5 hours. The adsorption amount of benzene can be calculated based on the integral ratio of supramolecular materials and benzene molecules. Fig.12 As shown, when the saturation point is reached, the number of benzene molecules adsorbed by each supramolecular material is 27 (TF), 26 (TH) and 15 (T-OCH3), respectively.

[0090] (3) Separation of benzene and cyclohexane

[0091] GC experiments are mainly used to separate and quantitatively analyze complex mixtures of multiple components. The headspace injection method is used to test the sample. 20 mg of the sample after adsorption and desorption at room temperature and pressure is placed at the bottom of a 20 mL crimp headspace injection bottle. The sample is heated at 100 ° C for 10 minutes in the injector, and the headspace sample is set to 1 mL. The GC operation is: the oven is programmed to start at 50 ° C and the temperature is set to 10 ° C min. -1 The internal temperature was raised to 200°C; the injection temperature was 250°C; the detector temperature was 280°C; the nitrogen, air and make-up flow rates were 35, 350 and 35 mL min, respectively. -1 , helium (carrier gas) flow rate is 3.0 mL min -1The samples were injected in splitless mode (30:1). The results of the GC experiments on benzene and cyclohexane were as follows: Fig.13 As shown in the figure, the integration with benzene (peak position: 6.18) and cyclohexane (peak position: 6.68) shows that the adsorbent has a stronger adsorption capacity for benzene, and the adsorption storage capacity of benzene accounts for 99.5%, 99.83% and 66.34% of the total, respectively, which is also in good agreement with the adsorption isotherm ( Fig.13 ). In addition, after 5 cycles, the adsorption of benzene by supramolecular materials TF and TH can still be maintained at a high level, which shows that the supramolecular materials have a stable structure and can be used as good adsorption materials ( Fig.14 , Fig.15 ).

[0092] (4) Study on the binding sites of adsorbed benzene molecules in supramolecular materials

[0093] In order to understand the high adsorption performance and selectivity of supramolecular materials for benzene, the single crystal structures of benzene@TF, benzene@TH and benzene@T-OCH3 cocrystals were determined. The structural analysis of benzene@TF, benzene@TH and benzene@T-OCH3 showed completely different frameworks. In the benzene@TF framework, benzene molecules cannot compete with the negatively charged PF6-s and interact with T-Fs through multiple CH...F hydrogen bonds and electrostatic interactions. In addition, various non-covalent interactions are formed, including π-π stacking (average ), CH---π interaction and CH-F hydrogen bonds ( As shown in the figure, TH forms a compact hierarchical structure with negligible intermolecular channels, where two adjacent THs adopt a "head-to-head" mode. The adsorbed benzene molecules are trapped in the molecular gaps, and the main driving force comes from π-π stacking (average ) and CH---π interactions As for T-OCH3, only CH-π interactions were detected between the adsorbed benzene molecules and MOC, which reasonably explains the poor benzene adsorption capacity and separation selectivity of T-OCH3 ( Fig.16 , Fig.17 ).

[0094] The present invention first provides the application of three supramolecular materials TH, T-OCH3 and TF, which respectively contain unsubstituted tpy-Zn 2+ -tpy group, methoxy-modified tpy-Zn 2+ -tpy group and fluorine-modified tpy-Zn 2+-tpy group as an adsorbent for efficient adsorption and separation of benzene. At the same time, the present invention also introduces a method for preparing these supramolecular materials, namely, by using three differently modified ligands to coordinate with the transition metal Zn, thereby obtaining TH, T-OCH3, and TF containing corresponding groups. In addition, these supramolecular materials can form non-covalent bonds with aromatic structures such as benzene, such as [CH··π] interactions and [π··π] stacking, which is the main driving force for their adsorption and separation. In terms of the adsorption and storage of benzene, these supramolecular materials show strong specificity, especially the metal cage TH, whose maximum adsorption capacity for benzene can reach 120cm 3 / g. The invention fills the gap of the current non-porous amorphous metal organic cage with high adsorption capacity and selectivity, and provides a new solution for the efficient adsorption and separation of benzene and cyclohexane.

[0095] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily being directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0096] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A supramolecular material having high efficiency in adsorption and separation of benzene, characterized in that: The unit structure of the supramolecular material is shown in formula (I), formula (II) and formula (III):

2. A method for preparing a supramolecular material having high-efficiency benzene adsorption and separation capabilities according to claim 1, characterized in that: The following steps are involved: (1) Preparation of terpyridine metal organic ligands as shown in formula (IV) to formula (VI): (2) adding a solvent to the three ligands prepared in step (1) respectively to dissolve them, then dropping a metal salt solution, heating to react, adding an anion replacement agent after the reaction is completed, filtering to obtain a precipitate, and then assembling to synthesize the unsubstituted tpy-Zn 2+ -tpy group supramolecular materials, methoxy-modified tpy-Zn 2+ -tpy group-based supramolecular materials and fluorine-modified tpy-Zn 2+ -tpy group-containing supramolecular materials.

3. The method for preparing a supramolecular material having high-efficiency benzene adsorption and separation capability according to claim 2, characterized in that: In step (2), the anion displacer is ammonium hexafluorophosphate.

4. The method for preparing a supramolecular material having high-efficiency benzene adsorption and separation capability according to claim 2, characterized in that: In step (2), the solvent is at least one of alcohol, chloroform and ether.

5. The method for preparing a supramolecular material having high-efficiency benzene adsorption and separation capability according to claim 4, characterized in that: In step (2), the solvent is a mixed solution of methanol and chloroform, wherein the volume ratio of methanol to chloroform is 2:

1. The mixed solvent of methanol and chloroform plays an important role in the formation of the supramolecular material, the terpyridine ligand has good solubility in the mixed solvent of chloroform and methanol, and the generated supramolecular material can also be well dissolved in acetonitrile.

6. The method for preparing a supramolecular material having high-efficiency benzene adsorption and separation capability according to claim 2, characterized in that: In step (2), the heating reaction temperature is 40-70°C and the reaction time is 5-10h.

7. The method for preparing a supramolecular material having high-efficiency benzene adsorption and separation capability according to claim 2, characterized in that: In step (2), the heating reaction temperature is 45-55°C, and the reaction time is 6-10h.

8. An application of the supramolecular material having high efficiency in adsorbing and separating benzene according to claim 1, characterized in that: The supramolecular material contains tpy-Zn 2+ The supramolecular cage of -tpy group was used as adsorbent for benzene.

9. The use of a supramolecular material having high-efficiency adsorption and separation capability of benzene according to claim 8, characterized in that: In an atmosphere of equimolar benzene and cyclohexane, the supramolecular material can efficiently and selectively adsorb and separate benzene in a mixed phase.

10. The use of a supramolecular material having high-efficiency adsorption and separation capability of benzene according to claim 8, characterized in that: The adsorption capacity of the supramolecular material for benzene in the powder state and at 298K includes: the benzene adsorption capacity of the supramolecular material TF is 110cm 3 / g, supramolecular material TH: 120cm 3 / g, supramolecular material T-OCH3: 70cm 3 / g.

Images