A structurally adjustable triazine-based metal organic cage and its preparation method and application

Abstract

The application discloses a structure-adjustable triazine-based metal organic cage and a preparation method and application thereof, belongs to the technical field of air pollution treatment, and discloses a series of structure-adjustable triazine-based metal organic cage materials and a preparation method thereof. By changing the chemical structure of the third component sodium tetracarboxylate, the structure of the triazine-based metal organic cage can be controlled to change from a pentahedron to an I-type expanded octahedron and then to a II-type expanded octahedron. The triazine-based metal organic cage synthesized by the application has good SO2 adsorption recyclability and can still maintain good adsorption performance after 5 cycles. Meanwhile, the triazine-based metal organic cage has higher SO2 selectivity compared with CO2 and N2. Further, the triazine-based metal organic cage can effectively promote the chemical conversion of trace SO2 in a mixed gas as an SO2 concentrator under trace conditions.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of air pollution treatment, and particularly relates to a triazine-based metal organic cage with adjustable structure and a preparation method and application thereof. BACKGROUND

[0002] Sulfur dioxide (SO2) is a gas with pungency and corrosiveness, which has great harm to the environment, buildings, human health, etc. The combustion of fossil fuels further aggravates the harm caused by SO2 pollution. Therefore, it is of great significance to develop effective materials for SO2 capture and conversion for global environmental protection. At present, the materials for desulfurization are mostly porous materials such as molecular sieves, zeolites, metal organic frameworks, or ionic liquids containing N elements with rich adsorption sites. These materials still have the following two problems: (1) the structure of the materials cannot be accurately controlled at the molecular level, and it is difficult to establish an accurate adsorption-desorption theoretical model; (2) for metal organic framework materials, in most metal organic framework systems, the adsorption of SO2 is attributed to the coordination of sulfur atoms and metal centers, and this extrinsic coordination may compete with the metal coordination bonds that constitute the metal organic framework itself, thereby causing the structure of the material to collapse during the desorption of SO2.

[0003] Metal organic cages, as a kind of discrete supramolecular complexes, are increasingly applied in the field of gas adsorption due to their structure design at the molecular level. Specifically, the use of metal organic cages as SO2 adsorbents has the following advantages: (1) the cavity structure can be accurately designed and adjusted, thereby optimizing the SO2 adsorption performance of the material at the molecular level; (2) compared with the infinite continuous network structure, the discrete metal organic cage can accurately introduce adsorption sites, avoiding the structural damage caused by competing metal coordination; (3) the discrete structure reduces the difficulty of theoretical simulation calculation, greatly improves the accuracy of the metal organic cage adsorption model, and can better guide the structure design of the material.

[0004] However, metal organic cages as SO2 adsorbents still have the following problems: (1) The metal node as the only adsorption site will cause the recyclability of adsorption to deteriorate. For example, Ibarra combined a Pd-based metal organic cage, which adsorbs SO2 by coordinating with SO2 through the Pd metal site. However, due to the overly strong coordination effect of Pd-S, the adsorption process behaves as chemical adsorption, and the performance drops significantly after one adsorption cycle. (2) The desulfurization performance of metal organic cages reported so far has only been tested on pure SO2 adsorption, while SO2 in actual air pollutant flue gas is in a state of mixing with CO2 and N2, and the proportion of SO2 is very small. Compared with other gases in flue gas, especially CO2 and N2, the selective adsorption of SO2 by metal organic cages has never been reported. (3) The use of metal organic cages to further convert trace amounts of SO2 into high-value-added compounds has never been achieved. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a structurally adjustable triazine-based metal organic cage and its preparation method and application, so as to solve the problem in the prior art that the performance of SO2 deteriorates after one SO2 adsorption cycle and it is difficult to selectively adsorb SO2 from air pollutant flue gas.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing a structurally adjustable triazine-based metal organic cage comprises the following steps: dissolving Pt metal and a triazine-based pyridine ligand in a mixed solvent, adding a sodium salt of a tetracarboxylic acid to obtain a mixture; ultrasonically treating the mixture, transferring the mixture to a metal bath, stirring the mixture by a solvothermal method, and purifying the product obtained by the solvothermal method to obtain a triazine-based metal organic cage having a cavity structure;

[0008] The sodium salt of tetracarboxylic acid is any one of bis(3,5-dicarboxylic acid sodium phenyl)azo, 1,1-ethynylbiphenyl-3,3,5,5,-tetracarboxylic acid sodium, [1,1':4',1"-terphenyl]-3,3",5,5"-tetracarboxylic acid sodium, 9,10-bis(3',5'-dicarboxylic acid sodium phenyl)naphthalene or 9,10-bis(3',5'-dicarboxylic acid sodium phenyl)anthracene; one sodium salt of tetracarboxylic acid corresponds to one triazine-based metal organic cage with a cavity structure.

[0009] A further improvement of the present invention is:

[0010] Preferably, the Pt metal is any one of Pt(PEt3)2(OTf)2, Pt(en)(NO3)2 or Pt(2,2'-bpy)(NO3)2.

[0011] Preferably, the triazine-pyridine ligand is any one of 2,4,6-tris(4-pyridine)-1,3,5-triazine and 2,4,6-tris(2-pyridine)-1,3,5-triazine.

[0012] Preferably, the molar ratio of triazine pyridine ligand, sodium tetracarboxylate and Pt metal is (1.5-2.5):1:(4.5-5.5).

[0013] Preferably, the solvent thermal reaction temperature is 40-80° C., and the reaction time is 5-16 h.

[0014] Preferably, the mixed solvent is a mixture of acetone and water.

[0015] Preferably, the purification process is to sequentially subject the reaction product to drying, filtration, recrystallization and drying to obtain a triazine-based metal organic cage with a cavity structure.

[0016] A structure-adjustable triazine-based metal organic cage prepared by any one of the above preparation methods consists of a sodium tetracarboxylate ligand, a tripyridine ligand and an organic platinum metal ion.

[0017] An application of the above-mentioned structurally adjustable triazine-based metal organic cage as an adsorbent for SO2.

[0018] Preferably, it is used as a SO2 gas collector to improve the cycloaddition chemical conversion performance of SO2.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] This invention discloses a method for preparing a structurally tunable multi-component triazine-based metal-organic cage material. The cage is composed of sodium tetracarboxylate ligands, tripyridine ligands, and organoplatinum metal ions. This method, for the first time, allows for precise structural tuning of the metal-organic cage through a non-covalent approach. By simply modifying the chemical structure of the sodium tetracarboxylate (all carboxylates are purchased and directly reacted with a base to obtain the desired sodium carboxylates, without the need for separate synthesis), such as the length and the deflection angle of the intermediate groups, the three-dimensional structure of the metal-organic cage can be controlled and adjusted. Uncommon pentahedral and extended octahedral metal-organic cage configurations have been achieved for the first time.

[0021] The application also discloses a structure-adjustable multi-component triazine-based metal organic cage, selects triazine group-containing pyridine as a ligand, a triethyl phosphine-modified Pt as a metal site, and a series of structure continuously controllable multi-component triazine-based metal organic cages are obtained by changing a chemical structure of a third component sodium tetracarboxylate.

[0022] The application also discloses application of the triazine-based metal organic cage as an SO2 adsorbent: the prepared series of triazine-based metal organic cages show excellent SO2 adsorption activity and selectivity, wherein, the preferred 4e metal organic cage material of the application can adsorb SO2 in an amount of 4.66 mmol·g-1 at 298 K and 1.0 bar. -1 The selectivity to SO2 is as high as 538 under the condition that the volume ratio of SO2 / CO2 is 0.1, and is in the highest selectivity range reported. Moreover, the 4e still maintains the adsorption performance without decline after 5 cycles, and exhibits better adsorption recyclability compared with a framework material and a discrete material using a metal node as an adsorption site.

[0023] Further, as a micro SO2 concentrator, the addition of the 4e significantly promotes the SO2 conversion reaction, and the yield of the ring addition product of SO2 is increased by nearly 4 times under the condition that the reaction is carried out at 70 DEG C for 24 h without the metal organic cage, which is beneficial to prove the role of the triazine-based metal organic cage in the SO2 conversion reaction. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a nuclear magnetic chart of the multi-component triazine-based metal organic cage prepared in Example 1;

[0025] Figure 2 It is a crystal structure chart of the multi-component triazine-based metal organic cage prepared in Example 1;

[0026] Wherein: (a) is 4a; (b) is 4c; (c) is 4d; (d) is 4e.

[0027] Figure 3 It is an SO2, CO2 and N2 adsorption and desorption curve and an SO2 selectivity curve of each multi-component triazine-based metal organic cage in Example 2;

[0028] Wherein: (a) is the adsorption curve of 4a; (b) is the adsorption curve of 4b; (c) is the adsorption curve of 4c; (d) is the adsorption curve of 4d; (e) is the adsorption curve of 4e; (f) is the SO2 selectivity curve.

[0029] Figure 4 The selectivity calculation under the simulated flue gas of 4e in Example 1;

[0030] Figure 5 The SO2 five adsorption-desorption cycles of 4e in Example 1; DETAILED DESCRIPTION

[0031] Firstly, the application discloses a preparation method of a structure-adjustable triazine-based metal organic cage: Pt metal and triazine-based pyridine ligand are dissolved in a mixed solvent, different chemical structure sodium tetracarboxylate is added, the mixture is ultrasonically treated for 20s and then transferred to a metal bath pot, and a series of triazine-based metal organic cages with different cavity structures are obtained by solvent thermal method long-time stirring. The specific chemical reaction process is shown in the following formula:

[0032]

[0033] The crystal structures of 4a-4e metal organic cages both exist two coordination modes, i.e. homonuclear coordination of Pt with two pyridine N and heteronuclear coordination of Pt with one pyridine N and one sodium carboxylate oxygen. Among them, the pentahedral structure vertexes of 4a and 4b are homonuclear coordination, and the four Pt on the bottom surface is heteronuclear coordination; the crystal structures of 4c and 4d are I-type expanded octahedron, which are characterized by upper and lower homonuclear coordination vertexes, middle eight points as heteronuclear coordination, and horizontally placed sodium carboxylate; the crystal structure of 4e is II-type expanded octahedron, which is characterized by upper and lower homonuclear coordination vertexes, middle eight points as heteronuclear coordination, and vertically placed sodium carboxylate.

[0034] Specifically, the triazine-based pyridine ligand is 2,4,6-tris(4-pyridine)-1,3,5-triazine or 2,4,6-tris(2-pyridine)-1,3,5-triazine, preferably 2,4,6-tris(4-pyridine)-1,3,5-triazine, and specifically, the substance is the substance numbered 1 in the above formula (I).

[0035]

[0036]

[0037] Specifically, the Pt metal is Pt(PEt3)2(OTf)2, Pt(en)(NO3)2 or Pt(2,2'-bpy)(NO3)2, preferably Pt(PEt3)2(OTf)2, and specifically, the substance is the one numbered 2 in the above formula (I). This is because Pt(PEt3)2(OTf)2 has a charge separation effect, which can provide a controllable coordination mode.

[0038]

[0039] Specifically, the sodium tetracarboxylate ligand is bis(3,5-sodium dicarboxylate phenyl) azo (3a), 1,1-ethynyl biphenyl-3,3,5,5,-sodium tetracarboxylate (3b), [1,1':4',1"-terphenyl]-3,3",5,5"-sodium tetracarboxylate (3c), 9,10-bis(3',5'-sodium dicarboxylate phenyl) naphthalene (3d) or 9,10-bis(3',5'-sodium dicarboxylate phenyl) anthracene (3e). The resulting metal-organic cage is named 4a, 4b, 4c, 4d, 4e, respectively, and the chemical structure is shown in the following formula.

[0040]

[0041] Specifically, the molar ratio of triazine-based pyridine ligand: sodium tetracarboxylate: Pt is (1.5-2.5):1:(4.5-5.5), preferably 2:1:5.

[0042] As one of the preferred solutions, the mixed solvent is a mixture of acetone and water, and the volume ratio of acetone to water in the mixture is (3-6):1, and more preferably 4:1.

[0043] As one of the preferred solutions, the specific conditions of the solvothermal method are that the heating temperature is 40-80°C, and more preferably, the heating temperature is 50°C. The reaction time is 5-16h, and preferably, the reaction time is 12h.

[0044] As one of the preferred solutions, the triazine-based metal-organic cage is prepared by purification after the solvothermal reaction; further, the purification step includes drying, filtering, recrystallization and drying.

[0045] The drying method is N2 blowing drying or vacuum rotary evaporation, and preferably N2 blowing drying. The filtering is dissolution and filtering with acetone or acetonitrile, and preferably acetone. The recrystallization is with diethyl ether or isopropyl ether, and preferably diethyl ether. The obtained precipitate is centrifuged and then vacuum dried at 50-80°C, and further, the optimal temperature is 50°C, and the drying time is 10-14h, and further, the drying time is 12h.

[0046] One of the embodiments of the present application discloses a structure-adjustable triazine-based metal organic cage, which is composed of sodium tetracarboxylate ligand, tripyridine ligand and organic platinum metal ion. By changing the chemical structure of sodium tetracarboxylate ligand, the configuration of the obtained triazine-based metal organic cage can have different controllable changes of pentahedron (4a / 4b)→type I expanded octahedron (4c / 4d)→type II expanded octahedron (4d / 4e). Among them, the transition from pentahedron→type I expanded octahedron is affected by the ligand length, and the transition from type I expanded octahedron→type II expanded octahedron is affected by the packing mode of the metal organic cage.

[0047] Secondly, the present application discloses the application of the structure-adjustable triazine-based metal organic cage as an SO2 adsorbent.

[0048] Preferably, the application is the application of the series of triazine-based metal organic cages synthesized by the present application as an SO2 adsorbent. The five synthesized metal organic cages (4a-4e) respectively exhibit adsorption performances of 4.26, 3.76, 3.48, 3.21, 3.61 and 4.66 mmol·g-1 at 298 K and 1.0 bar. -1 And, due to N as an adsorption site, the metal organic cage 4e preferably still has good adsorption performance after 5 cycles, realizing the reversible adsorption of SO2.

[0049] Further, the application is the application of the triazine-based metal organic cage synthesized by the present application as an SO2 / CO2 / N2 mixed gas micro SO2 adsorbent. The metal organic cage 4e preferably exhibits a high SO2 selectivity of 538 at an SO2 / CO2 molar ratio of 0.1, which is located in the highest selectivity range reported.

[0050] Further, in the SO2 / CO2 / N2 simulated flue gas with a molar fraction of SO2 of 0.05%, the metal organic cage 4e still exhibits good SO2 / CO2 adsorption performance selectivity, the value of which is 86, because there are rich basic N sites in the metal organic cage, and the acidity of SO2 is higher than that of CO2, so the metal organic cage exhibits more selective adsorption of SO2, which can be applied to actual flue gas desulfurization.

[0051] Finally, the present application discloses the application of the synthesized triazine-based metal organic cage, preferably the metal organic cage 4e, as an SO2 gas collector, which can improve the performance of SO2 cycloaddition chemical conversion.

[0052] The triazine-based metal organic cage synthesized in this invention is used to enhance the performance of SO2 cycloaddition reactions by dispersing the triazine-based metal organic cage 4e into an acetonitrile solution containing the reaction substrate 2,3-dimethylbutadiene. A SO2 / N2 mixture with a volume ratio of 1:99 is bubbled into the solution for 3 minutes, after which the atmosphere is maintained with a balloon. Samples are taken at various times, and SO2 conversion data is obtained by nuclear magnetic resonance.

[0053] In the embodiment of the present invention, eight different reaction environments were adopted, namely, room temperature for 48 hours (with / without metal-organic cages), 50°C for 48 hours (with / without metal-organic cages), 70°C for 24 hours (with / without metal-organic cages), and 90°C for 4 hours (with / without metal-organic cages). Without exception, under each reaction environment, the addition of metal-organic cages can effectively improve the conversion efficiency and selectivity of the SO2 conversion reaction. Among them, in the presence of 4e metal-organic cages, the conversion rate was 40% and the selectivity was as high as 99% at 70°C for 24 hours.

[0054] Example 1

[0055] This embodiment discloses a method for preparing a structure-adjustable multi-component triazine-based metal organic cage, comprising the following steps:

[0056] (1) 2,4,6-tris(4-pyridine)-1,3,5-triazine (1) (2.00 mg, 6.40 μmol), Pt(PEt3)2(OTf2

[0057] (2) (11.68 mg, 16.01 μmol) was mixed in a molar ratio of 2:5 and dissolved in acetone / water (5 ml, 4:1, v / v);

[0058] (2) Bis(3,5-dicarboxylic acid sodium phenyl)azo (3a) (1.43 mg, 3.20 μmol) was added and the mixture was sonicated for 20 s. The entire reaction mixture was heated at 50 °C for 12 h and then cooled to room temperature.

[0059] (3) The solvent was removed with a nitrogen stream. The residue was redissolved in CH3CN (1.0 mL), filtered, and then precipitated with ether (4 mL). The resulting precipitate was centrifuged to yield the metal-organic cage 4a.

[0060] Example 2

[0061] This embodiment discloses a method for preparing a structure-adjustable multi-component triazine-based metal organic cage, comprising the following steps:

[0062] (1) 2,4,6-tris(4-pyridine)-1,3,5-triazine (1) (2.00 mg, 6.40 μmol), Pt(PEt3)2(OTf2

[0063] (2) (11.68 mg, 16.01 μmol) was mixed in a molar ratio of 2:5 and dissolved in acetone / water (5 ml, 4:1, v / v);

[0064] (2) Sodium 1,1-ethynylbiphenyl-3,3,5,5,-tetracarboxylate (3b) (1.42 mg, 3.20 μmol) was added, and the mixture was sonicated for 20 s. The entire reaction mixture was heated at 50 °C for 12 h and then cooled to room temperature.

[0065] (3) The solvent was removed with a nitrogen stream. The residue was redissolved in CH3CN (1.0 mL), filtered, and then precipitated with ether (4 mL). The resulting precipitate was centrifuged to yield the metal-organic cage 4b.

[0066] Example 3

[0067] This embodiment discloses a method for preparing a structure-adjustable multi-component triazine-based metal organic cage, comprising the following steps:

[0068] (1) 2,4,6-tris(4-pyridine)-1,3,5-triazine (1) (2.00 mg, 6.40 μmol), Pt(PEt3)2(OTf2

[0069] (2) (11.68 mg, 16.01 μmol) was mixed in a molar ratio of 2:5 and dissolved in acetone / water (5 ml, 4:1, v / v);

[0070] (2) Sodium [1,1':4',1"-terphenyl]-3,3",5,5"-tetracarboxylate (3c) (1.58 mg, 3.20 μmol) was added, and the mixture was sonicated for 20 s. The entire reaction mixture was heated at 50 °C for 12 h and then cooled to room temperature.

[0071] (3) The solvent was removed with a nitrogen stream. The residue was redissolved in CH3CN (1.0 mL), filtered, and precipitated with ether (4 mL). The resulting precipitate was centrifuged to yield the metal-organic cage 4c.

[0072] Example 4

[0073] This embodiment discloses a method for preparing a structure-adjustable multi-component triazine-based metal organic cage, comprising the following steps:

[0074] (1) 2,4,6-tris(4-pyridine)-1,3,5-triazine (1) (2.00 mg, 6.40 μmol), Pt(PEt3)2(OTf2

[0075] (2) (11.68 mg, 16.01 μmol) was mixed in a molar ratio of 2:5 and dissolved in acetone / water (5 ml, 4:1, v / v);

[0076] (2) 9,10-bis(3',5'-dicarboxysodiumphenyl)naphthalene (3d) (1.74 mg, 3.20 μmol) was added, and the mixture was sonicated for 20 s. The entire reaction mixture was heated at 50 °C for 12 h and then cooled to room temperature.

[0077] (3) The solvent was removed with a nitrogen stream. The residue was redissolved in CH3CN (1.0 mL), filtered, and then precipitated with ether (4 mL). The resulting precipitate was centrifuged to yield the metal organic cage 4d.

[0078] Example 5

[0079] This embodiment discloses a method for preparing a structure-adjustable multi-component triazine-based metal organic cage, comprising the following steps:

[0080] (1) 2,4,6-tris(4-pyridine)-1,3,5-triazine (1) (2.00 mg, 6.40 μmol), Pt(PEt3)2(OTf2

[0081] (2) (11.68 mg, 16.01 μmol) was mixed in a molar ratio of 2:5 and dissolved in acetone / water (5 ml, 4:1, v / v);

[0082] (2) 9,10-bis(3',5'-dicarboxysodiumphenyl)anthracene (3e) (1.90 mg, 3.20 μmol) was added, and the mixture was sonicated for 20 s. The entire reaction mixture was heated at 50 °C for 12 h and then cooled to room temperature.

[0083] (3) The solvent was removed with a nitrogen stream. The residue was redissolved in CH3CN (1.0 mL), filtered, and precipitated with ether (4 mL). The resulting precipitate was centrifuged to yield the metal organic cage 4e.

[0084] The NMR spectra results in Examples 1 to 5 are as follows Figure 1 As shown, see also Figure 2, indicating the successful synthesis of the metal-organic cage, and the similar characteristic peaks of 4a and 4b indicate that they have the same pentahedral configuration; the crystal structure of 4c confirms its three-dimensional structure of type I extended octahedron; the phosphorus spectrum and hydrogen spectrum of 4d both show that it coexists with type I extended octahedron and type II extended octahedron in the solid state; the NMR spectrum and crystal structure diagram of 4e show that it has a single type II extended octahedron structure.

[0085] The following further performs performance verification calculations for the above five embodiments:

[0086] 1. Gas adsorption experiments and selectivity calculations of triazine-based metal organic cages, including the following steps:

[0087] (1) After the sample was vacuum dried at 90 °C for 3 h, the adsorption and desorption curves of SO2 were measured using a 3Flex5.02 analyzer. The adsorption-desorption curves of CO2 and N2 were obtained using a BELMaster7.3.2.0 analyzer and a BELSORP-miniII analyzer, respectively.

[0088] (2) IAST calculation of adsorption selectivity: The selectivity of SO2 / CO2 in a mixed gas can be defined as:

[0089]

[0090] Where x1 and y1 (x2 and y2) represent the mole fractions of SO2 (CO2) in the adsorbed and bulk phases, respectively. The values ​​of x1 and x2 were calculated using the ideal adsorption solution theory (IAST) of Myers and Prausnitz.

[0091] Based on the above results, see Figure 3 , indicating that triazine-based metal organic cages exhibit different degrees of SO2 adsorption performance, among which 4e shows the best adsorption amount and SO2 selectivity.

[0092] 2. Considering that the concentration of sulfur dioxide in actual flue gas is very low, the molecular fraction of N2 is kept at 89.50%, and the content of SO2 in the SO2 / CO2 / N2 ternary mixture is changed from 0.05% to 0.30% to study the adsorption of SO2 / CO2. Figure 4 , it can be seen that even when the molar fraction of SO2 is 0.05%, the 4e metal-organic cage still exhibits considerable SO2 / CO2 adsorption selectivity in the three-component mixed gas (86), indicating that the metal-organic cage can be applied to actual flue gas desulfurization.

[0093] 3. Cyclic experiment: After each adsorption-desorption cycle, the 4e sample was vacuum treated at 363K for 3h before the next adsorption cycle was performed, for a total of five cyclic experiments. Figure 5, it can be seen that 4e still maintains good adsorption performance after 5 cycles, indicating that it can be used as a recyclable adsorbent.

[0094] 4. Performance Testing

[0095] SO2 conversion experiment

[0096] (1) Test method:

[0097] SO2 conversion tests were conducted in glass vials sealed with rubber stoppers. Two needles were inserted into the top of the vials: one below the liquid level to allow the SO2 / N2 mixture to flow, and the other above the liquid level to allow the gas to escape. After a 3-minute flow, the needles were removed and replaced with a needle containing a balloon containing the mixture to maintain the gas atmosphere.

[0098] 2,3-Dimethylbutadiene (10 μmol), hydroquinone (10 μmol), 4e (10 mg), 1% SO2 (SO2 / N2=1:99, v / v), CD3CN as the reaction solvent. 1,3,5-Trimethylbenzene was used as the internal standard. 1 The yield was determined by HNMR.

[0099] (2) Test results:

[0100] The performance comparison of different triazine-based metal organic cages prepared in Example 1 in promoting SO2 conversion is shown in Table 1.

[0101] Table 1 Cycloaddition reaction of SO2 and 2,3-dimethylbutadiene in the presence of metal organic cage 4e

[0102]

[0103]

[0104] Table 1 shows that the addition of 4e improves SO2 conversion performance to varying degrees under different reaction conditions. Specifically, when the reaction temperature is 70°C for 24 hours, the addition of 4e increases the yield by nearly fourfold. These results provide insights into the selection of highly efficient metal-organic cage materials as adsorbents and converters for corrosive gaseous pollutants.

[0105] Example 6

[0106] This embodiment discloses a method for preparing a structure-adjustable multi-component triazine-based metal organic cage, comprising the following steps:

[0107] (1) 2,4,6-Tris(4-pyridine)-1,3,5-triazine (1) (6.40 μmol) and Pt(en)(NO3)2 (16.01 μmol) were mixed in a molar ratio of 2:5 and dissolved in acetone / water (5 ml, 4:1, v / v);

[0108] (2) Bis(3,5-dicarboxylic acid sodium phenyl)azo (3a) (3.20 μmol) was added and the mixture was sonicated for 20 s. The entire reaction mixture was heated at 50 °C for 12 h and then cooled to room temperature.

[0109] (3) The solvent was removed with a nitrogen stream. The residue was redissolved in CH3CN (1.0 mL), filtered, and then precipitated with ether (4 mL). The resulting precipitate was centrifuged to yield the metal-organic cage 4a.

[0110] Example 7

[0111] This embodiment discloses a method for preparing a structure-adjustable multi-component triazine-based metal organic cage, comprising the following steps:

[0112] (1) 2,4,6-Tris(2-pyridine)-1,3,5-triazine (6.40 μmol) and Pt(PEt3)2(OTf)2(2) (11.68 mg, 16.01 μmol) were mixed in a molar ratio of 2:5 and dissolved in acetone / water (5 ml, 4:1, v / v);

[0113] (2) Sodium 1,1-ethynylbiphenyl-3,3,5,5,-tetracarboxylate (3b) (1.42 mg, 3.20 μmol) was added, and the mixture was sonicated for 20 s. The entire reaction mixture was heated at 50 °C for 12 h and then cooled to room temperature.

[0114] (3) The solvent was removed with a nitrogen stream. The residue was redissolved in CH3CN (1.0 mL), filtered, and then precipitated with ether (4 mL). The resulting precipitate was centrifuged to yield the metal-organic cage 4b.

[0115] Example 8

[0116] This embodiment discloses a method for preparing a structure-adjustable multi-component triazine-based metal organic cage, comprising the following steps:

[0117] (1) 2,4,6-Tris(4-pyridine)-1,3,5-triazine (1) (6.40 μmol) and Pt(2,2'-bpy)(NO3)2 (16.01 μmol) were mixed in a molar ratio of 2:5 and dissolved in acetone / water (5 ml, 4:1, v / v);

[0118] (2) Sodium [1,1':4',1"-terphenyl]-3,3",5,5"-tetracarboxylate (3c) (3.20 μmol) was added, and the mixture was sonicated for 20 s. The entire reaction mixture was heated at 50 °C for 12 h and then cooled to room temperature.

[0119] (3) The solvent was removed by a stream of nitrogen. The residue was redissolved in CH3CN (1.0 mL) and precipitated by adding diethyl ether (4 mL) after filtration. The resulting precipitate was obtained by centrifugation as metalloorganic cage 4c.

[0120] Example 9

[0121] This example discloses a method for preparing a structurally tunable multi-component triazine-based metalloorganic cage, comprising the following steps:

[0122] (1) 2,4,6-tris(4-pyridinio)-1,3,5-triazine (1) (8 μmol), Pt(PEt3)2(OTf)2 (2) (17.6 μmol) were mixed in a molar ratio of 2.5:5.5 and dissolved in acetone / water (5 mL, 4:1, v / v);

[0123] (2) 9,10-bis(3',5'-dicarboxylato sodium phenyl)anthracene (3e) (3.20 μmol) was added and the mixture was sonicated for 20 s. The whole reaction mixture was heated at 50 °C for 12 h and then cooled to room temperature.

[0124] (3) The solvent was removed by a stream of nitrogen. The residue was redissolved in CH3CN (1.0 mL) and precipitated by adding diethyl ether (4 mL) after filtration. The resulting precipitate was obtained by centrifugation as metalloorganic cage 4c.

[0125] Example 10

[0126] This example discloses a method for preparing a structurally tunable multi-component triazine-based metalloorganic cage, comprising the following steps:

[0127] (1) 2,4,6-tris(4-pyridinio)-1,3,5-triazine (1) (8 μmol), Pt(PEt3)2(OTf)2 (2) (17.6 μmol) were mixed in a molar ratio of 2.5:5.5 and dissolved in acetone / water (5 mL, 4:1, v / v);

[0128] (2) 9,10-bis(3',5'-dicarboxylato sodium phenyl)anthracene (3e) (3.20 μmol) was added and the mixture was sonicated for 20 s. The whole reaction mixture was heated at 50 °C for 12 h and then cooled to room temperature.

[0129] (3) The solvent was removed by a stream of nitrogen. The residue was redissolved in CH3CN (1.0 mL) and precipitated by adding diethyl ether (4 mL) after filtration. The resulting precipitate was obtained by centrifugation as metalloorganic cage 4c.

[0130] Example 11

[0131] This embodiment discloses a method for preparing a structure-adjustable multi-component triazine-based metal organic cage, comprising the following steps:

[0132] (1) 2,4,6-Tris(4-pyridine)-1,3,5-triazine (1) (6.40 μmol) and Pt(en)(NO3)2 (16.01 μmol) were mixed in a molar ratio of 2:5 and dissolved in acetone / water (5 ml, 3:1, v / v);

[0133] (2) Bis(3,5-dicarboxylic acid sodium phenyl)azo (3a) (3.20 μmol) was added and the mixture was sonicated for 20 s. The entire reaction mixture was heated at 50 °C for 12 h and then cooled to room temperature.

[0134] (3) The solvent was removed with a nitrogen stream. The residue was redissolved in CH3CN (1.0 mL), filtered, and then precipitated with ether (4 mL). The resulting precipitate was centrifuged to yield the metal organic cage 4a.

[0135] Example 12

[0136] This embodiment discloses a method for preparing a structure-adjustable multi-component triazine-based metal organic cage, comprising the following steps:

[0137] (1) 2,4,6-Tris(2-pyridine)-1,3,5-triazine (1) (6.40 μmol) and Pt(PEt3)2(OTf)2 (2) (11.68 mg, 16.01 μmol) were mixed in a molar ratio of 2:5 and dissolved in acetone / water (5 ml, 6:1, v / v);

[0138] (2) Sodium 1,1-ethynylbiphenyl-3,3,5,5,-tetracarboxylate (3b) (1.42 mg, 3.20 μmol) was added, and the mixture was sonicated for 20 s. The entire reaction mixture was heated at 50 °C for 12 h and then cooled to room temperature.

[0139] (3) The solvent was removed with a nitrogen stream. The residue was redissolved in CH3CN (1.0 mL), filtered, and then precipitated with ether (4 mL). The resulting precipitate was centrifuged to yield the metal-organic cage 4b.

[0140] Example 13

[0141] This embodiment discloses a method for preparing a structure-adjustable multi-component triazine-based metal organic cage, comprising the following steps:

[0142] (1) 2,4,6-Tris(4-pyridine)-1,3,5-triazine (1) (6.40 μmol) and Pt(2,2'-bpy)(NO3)2 (16.01 μmol) were mixed in a molar ratio of 2:5 and dissolved in acetone / water (5 ml, 4:1, v / v);

[0143] (2) Sodium [1,1':4',1"-terphenyl]-3,3",5,5"-tetracarboxylate (3c) (3.20 μmol) was added, and the mixture was sonicated for 20 s. The entire reaction mixture was heated at 40 °C for 12 h and then cooled to room temperature.

[0144] (3) The solvent was removed with a nitrogen stream. The residue was redissolved in CH3CN (1.0 mL), filtered, and precipitated with ether (4 mL). The resulting precipitate was centrifuged to yield the metal-organic cage 4c.

[0145] Example 14

[0146] This embodiment discloses a method for preparing a structure-adjustable multi-component triazine-based metal organic cage, comprising the following steps:

[0147] (1) 2,4,6-Tris(4-pyridine)-1,3,5-triazine (1) (4.80 μmol) and Pt(PEt3)2(OTf)2 (2) (14.4 μmol) were mixed in a molar ratio of 1.5:4.5 and dissolved in acetone / water (5 ml, 4:1, v / v);

[0148] (2) 9,10-bis(3',5'-dicarboxysodiumphenyl)naphthalene (3d) (3.20 μmol) was added, and the mixture was sonicated for 20 s. The entire reaction mixture was heated at 60 °C for 12 h and then cooled to room temperature.

[0149] (3) The solvent was removed with a nitrogen stream. The residue was redissolved in CH3CN (1.0 mL), filtered, and precipitated with ether (4 mL). The resulting precipitate was centrifuged to yield the metal organic cage 4d.

[0150] Example 15

[0151] This embodiment discloses a method for preparing a structure-adjustable multi-component triazine-based metal organic cage, comprising the following steps:

[0152] (1) 2,4,6-Tris(4-pyridine)-1,3,5-triazine (1) (8 μmol) and Pt(PEt3)2(OTf)2 (2) (17.6 μmol) were mixed in a molar ratio of 2.5:5.5 and dissolved in acetone / water (5 ml, 4:1, v / v);

[0153] (2) 9,10-bis(3',5'-dicarboxysodiumphenyl)anthracene (3e) (3.20 μmol) was added, and the mixture was sonicated for 20 s. The entire reaction mixture was heated at 80 °C for 12 h and then cooled to room temperature.

[0154] (3) The solvent was removed with a nitrogen stream. The residue was redissolved in CH3CN (1.0 mL), filtered, and then precipitated with ether (4 mL). The resulting precipitate was centrifuged to yield the metal organic cage 4e.

[0155] The present invention discloses a series of triazine-based metal-organic cage materials with adjustable structures and a preparation method thereof. By changing the chemical structure of the third component, sodium tetracarboxylate, the structure of the triazine-based metal-organic cage can be controllably transformed from a pentahedron to a type I extended octahedron to a type II extended octahedron. The triazine-based metal-organic cage synthesized by the present invention has good SO2 adsorption recyclability and can maintain good adsorption performance after 5 cycles. At the same time, it exhibits high SO2 selectivity relative to CO2 and N2, and shows considerable SO2 selective adsorption under simulated flue gas conditions, indicating its potential for adsorbing SO2 in actual flue gas. Furthermore, the triazine-based metal-organic cage can be used as a SO2 enricher under trace conditions to effectively promote the chemical conversion of trace SO2 in mixed gases. The addition of the metal-organic cage increases the product yield by nearly four times compared to a blank experiment without the metal-organic cage.

[0156] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a structurally adjustable triazine-based metal organic cage, characterized in that: The following steps are involved: Pt metal and triazine-pyridine ligand are dissolved in a mixed solvent, and sodium tetracarboxylate is added to obtain a mixture; the mixture is ultrasonically treated and then transferred to a metal bath, and stirred by a solvothermal method. The product obtained by the solvothermal method is purified to obtain a triazine-based metal organic cage having a cavity structure; The sodium salt of tetracarboxylic acid is any one of the following structural formulas: A sodium salt of a tetracarboxylic acid corresponds to a triazine-based metal organic cage with a cavity structure; Pt metal is either Pt(PEt3)2(OTf)2 or Pt(en)(NO3)2; The triazinylpyridine ligand is 2,4,6-tris(4-pyridine)-1,3,5-triazine; The molar ratio of triazine pyridine ligand, sodium tetracarboxylate and Pt metal is (1.5-2.5):1:(4.5-5.5).

2. The method for preparing a structure-adjustable triazine-based metal organic cage according to claim 1, characterized in that: The solvent thermal reaction temperature is 40~80℃, and the reaction time is 5~16 h.

3. The method for preparing a structure-adjustable triazine-based metal organic cage according to claim 1, characterized in that: The mixed solvent is a mixture of acetone and water.

4. The method for preparing a structure-adjustable triazine-based metal organic cage according to claim 1, characterized in that: The purification process is to sequentially subject the reaction product to drying, filtering, recrystallization and drying to obtain a triazine-based metal organic cage with a cavity structure.

5. A structure-adjustable triazine-based metal organic cage prepared by the preparation method according to any one of claims 1 to 4.

6. An application of the structure-adjustable triazine-based metal organic cage according to claim 5, characterized in that: As an adsorbent for SO2.

7. The use according to claim 6, characterized in that Used as a SO2 gas collector to improve the cycloaddition chemical conversion performance of SO2.

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