DOI: 10.1002/asia.201501105
Full Paper
Gas Uptake
Microporous Polymers from a Carbazole-Based Triptycene Monomer: Synthesis and Their Applications for Gas Uptake Tian-Long Zhai,[a] Liangxiao Tan,[b] Yi Luo,[a] Jun-Min Liu,*[c] Bien Tan,*[b] Xiang-Liang Yang,[a] Hui-Bi Xu,[a] and Chun Zhang*[a] Abstract: Two kinds of novel organic microporous polymers TCPs (TCP-A and TCP-B) were prepared by two cost-effective synthetic strategies from the monomer of tricarbazolyltriptycene (TCT). Their structure and properties were characterized by FT-IR, solid 13C NMR, powder XRD, SEM, TEM, and
gas absorption measurements. TCP-B displayed a high surface area (1469 m2 g¢1) and excellent H2 storage (1.70 wt % at 1 bar/77 K) and CO2 uptake abilities (16.1 wt % at 1 bar/ 273 K), which makes it a promising material for potential application in gas storage.
Introduction
in gas storage,[13] separations,[14] catalysis,[15] sensors,[16] and energy storage.[17] However, multistep synthesis processes, expensive catalysts, and rigorous experimental conditions of these OMPs may limit their scale-up applications. Easy availability, low cost, and high surface area are keys for OMPs to be applied in gas storage and capture of CO2. Recently, Tan and co-workers developed a low-cost knitting synthetic strategy for HCPs by employing a simple one-step Friedel–Crafts reaction using formaldehyde dimethyl acetal (FDA) as an external cross-linker.[18] Moreover, Han’s group[13, 19] prepared porous polycarbazoles through a simple and convenient way by FeCl3-catalyzed oxidative coupling polymerization, and furthermore proved that carbazole is an efficient building block for producing OMPs, which has also been confirmed by other groups.[20] Inspired by these interesting works, we envisioned that the introduction of triptycenes into a polycarbazole scaffold by low-cost synthetic strategies would result in novel porous copolymers, which may combine the advantages of triptycene with carbazole, and thus afford new materials for scale-up applications in gas storage and capture of CO2. Herein, we employed two cost-effective synthetic strategies to polymerize the tricarbazolyltriptycene (TCT) monomer and prepared two kinds of microporous polymers (TCP-A and TCPB), which displayed a high surface area, high gas-uptake capacity, thermal stability, good CO2 adsorption, and a good selectivity toward CO2 over N2.
With their three-dimensional rigid structure, triptycene and its derivatives have attracted great interest in supramolecular chemistry and materials science because of their perfect C3 symmetry and ease of functionalization.[1] For example, interlocked structures,[2] supramolecular hosts,[3] cage compounds[4] and conjugated polymers[5] have been synthesized by using triptycenes as main building blocks. Recently, our[6] and other groups[7] have proved that triptycene derivatives could also be utilized as useful building blocks for developing novel organic microporous polymers (OMPs). In the field of OMPs, different kinds of polymers, such as covalent organic frameworks (COFs),[8] hypercross-linked polymers (HCPs),[9] polymers of intrinsic microporosity (PIMs),[10] conjugated microporous polymers (CMPs),[11] and porous aromatic frameworks (PAF)[12] have been developed by templatefree chemical processes because of their potential applications [a] T.-L. Zhai,+ Y. Luo, Prof. X.-L. Yang, Prof. H.-B. Xu, Dr. C. Zhang Key Laboratory of Molecular Biophysics of the Ministry of Education College of Life Science and Technology Huazhong University of Science and Technology National Engineering Research Center for Nanomedicine Hubei, 430074 (China) E-mail: [email protected]
[b] Dr. L. Tan,+ Prof. Dr. B. Tan School of Chemistry and Chemical Engineering Huazhong University of Science and Technology Hubei, 430074 (China) E-mail: [email protected]
Results and Discussion With three carbazole moieties, the TCT monomer was synthesized easily by a copper-catalyzed N-arylation reaction between carbazole and 2,6,14-triiodotriptycene[21] (Scheme S1, Supporting Information). The synthesis of polymers TCP-A and TCP-B is outlined in Scheme 1. For TCP-A, oxidative coupling polymerization of TCT catalyzed by anhydrous FeCl3 in dry chloroform at room temperature afforded a pale yellow
[c] Dr. J.-M. Liu School of Chemistry and Chemical Engineering Sun Yat-Sen University Guangzhou, 510275 (China) E-mail: [email protected] [+] These authors contributed equally to this work. Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/asia.201501105. Chem. Asian J. 2016, 11, 294 – 298
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Full Paper the IR spectra (Supporting Information, Figure S3), the symmetric and asymmetric C-H stretching bands of methylene were observed at 2856 and 2927 cm¢1 in the framework of TCP-B. Field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were employed to investigate the morphology of TCPs. As shown in Figure 2, both
Scheme 1. Synthesis of TCPs. Reagents and conditions: (i) FeCl3, chloroform, 25 8C, 24 h; (ii) FDA, FeCl3, 1,2-dichloroethane, 80 8C, 24 h.
powder in a yield of 85.0 %. For TCP-B, the polymerization of TCT with 6 equivalents of formaldehyde dimethyl acetal (FDA) produced a brown powder in yield of 88.0 %. The obtained polymers were insoluble in common organic solvents. The structures of TCPs were characterized by 13C CP/ MAS NMR (CP/MAS = cross-polarization magic angle spinning) and FT-IR spectroscopies. As shown in Figure 1, the resonance peaks at d = 141, 130, 120, 106 and 51 ppm can be assigned to the substituted phenyl carbons, the unsubstituted phenyl carbons, and the methylidyne bridge carbons in the triptycene scaffold, respectively. For TCP-B, the small peaks at d = 67 and 36 ppm can be assigned to carbons in the unreacted hydroxymethyl groups (o) and the methylene linker (n), respectively. In
Figure 2. SEM and TEM images of TCP-A (a and c) and TCP-B (b and d). Scale bars: 1 mm (a and b) and 500 nm (c and d).
polymers were composed of amorphous rough particles similar to those observed in triptycene microporous networks.[6] From the broad peaks in the powder X-ray diffraction spectrum (Supporting Information, Figure S4), both polymers are noncrystalline. Thermogravimetric analysis (TGA) showed that TCPs are stable up to 550 8C in air (Supporting Information, Figure S5). To analyze the porous properties of TCPs, nitrogen sorption analyses at 77 K were utilized. The Brunauer–Emmett–Teller (BET) surface areas were determined to be 893 and 1469 m2 g¢1 (Langmuir surface areas are 1180 and 1812 m2 g¢1), and the total volumes were 0.59 and 0.76 cm3 g¢1 for TCP-A and TCP-B, respectively. As shown in Figure 3 a, the nitrogen adsorption isotherms indicate a steep nitrogen gas uptake at low relative pressure (P/P0 < 0.001), thus reflecting the abundant micropore structure in the networks of TCPs. Low pressure hysteresis was observed to extend to the lowest attainable pressure, and this phenomenon is associated with the irreversible uptake of gas molecules in the mesopores (or through pore entrances). In the desorption isotherm, low pressure unclosed hysteresis was observed owing to the elastic deformation or swelling effect of the polymer skeleton, which commonly exists in amorphous microporous polymer networks. The pore size distribution (Figure 3 b) calculated using nonlocal density functional theory (NLDFT) methods also confirmed the presence of primary micropores and a spot of mes-
Figure 1. 13C MAS NMR spectra of TCP-A (a) and TCP-B (b). Asterisks denote spinning sidebands. Chem. Asian J. 2016, 11, 294 – 298
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Figure 3. Nitrogen sorption isotherms at 77 K (a), pore size distributions calculated using NLDFT methods (b), H2 adsorption isotherms and desorption isotherms up to 1.0 bar at 77 K (c) and CO2 adsorption isotherms and desorption isotherms at 273 K (d) of TCP-A and TCP-B.
Clapeyron equation,[26] were 27 and 24 kJ mol¢1, respectively (Supporting Information, Figure S7). The selectivity of TCPs toward CO2 over N2 was investigated by single-component gas sorption experiments at 273 K. Calculating the initial slopes of adsorption isotherms (Supporting Information, Figures S8 and S9), the CO2/N2 selectivities were 26 and 19 for TCP-A and TCP-B, respectively.
opores. Compared with TCP-A, the greatly improved porosity properties of TCP-B suggested that the use of an external cross-linker with FDA to cross-link networks might result in polymer chains that possess more abundant micropores. Hydrogen sorption and desorption measurements of TCPs were carried out at 77 K. As shown in Figure 3 c, TCP-A can absorb 1.27 wt % of H2 at 1.0 bar. TCP-B can absorb 1.70 wt % H2 at 1.0 bar, a value that is larger than that determined for most triptycene-based polymers. As shown in Figure 3 d, TCPA and TCP-B can absorb CO2 (273 K, 1.0 bar) with the capabilities of 12.5 wt % and 16.1 wt %, respectively. The good CO2 uptake capacity of TCP-B is higher than that of a reported porous aromatic framework (PAF-1) (9.1 wt %) with an ultrahigh BET surface area of 5600 m2 g¢1,[22] commercially available BPL carbon (9.2 wt %),[23] and some heteroatom (nitrogen)-containing polymeric skeleton like TBI with an uptake capacity of 11.8 wt %[7a] and reported triptycene-based cages (11.0 wt %) with a high BET surface area of 1700 m2 g¢1,[24] and is comparable to Trçger’s-base-derived polymer TB-MOP under the same conditions.[25] At 298 K, the CO2 uptake capacities were 7.1 wt % and 9.0 wt % for TCP-A and TCP-B, respectively (Supporting Information, Figure S6). The excellent CO2 adsorption property of TCP-B may result from the perfect match of the microporous structure with the size of CO2. To understand the adsorption process, the isosteric enthalpy (Qst) values of TCP-A and TCP-B toward CO2, calculated from the adsorption isotherms at 273 and 298 K using the Clausius– Chem. Asian J. 2016, 11, 294 – 298
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Conclusions In summary, we synthesized two kinds of porous polymers, TCP-A and TCP-B, from low-cost reactions, using carbazolebased triptycene as monomer. With high thermal stability and high surface area, the porous polymers based on TCT are promising candidate materials for hydrogen storage and carbon dioxide capture. Further functionalization of these TCPs to improve the porous properties and to achieve the uptake of a catalyst are undergoing in our lab.
Experimental Section Characterization Methods and Instruments The 13C CP/MAS NMR spectra were recorded with a contact time of 2 ms (ramp 100) and pulse delay of 3 s. SEM measurements were performed on a Sirion 200 field-emission scanning electron microscope. TEM studies were conducted on a Tecnai G220 electron mi-
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Full Paper Acknowledgements
croscope. TGA measurements were performed on a Pyrisl TGA instrument. Materials were obtained commercially and used without further purification.
This work is supported by the National Natural Science Foundation of China (20902031, 21272292 and J1103514), the National Basic Research Program (2012CB932500), and the Fundamental Research Funds for the Central Universities (HUST 2015TS086). We thank the Analytical and Testing Center of Huazhong University of Science and Technology for related analysis. We also thank to the facility support of the Center for Nanoscale Characterization and Devices, Wuhan National Laboratory for Optoelectronics (WNLO).
Synthesis of TCT Under nitrogen atmosphere, a 25 mL flask was charged with anhydrous potassium carbonate (575 mg, 4.2 mmol), copper iodide (134 mg, 0.7 mmol), 1,10-phenanthroline (13 mg, 0.06 mmol), carbazole (578 mg, 3.5 mmol), 2,6,14-triiodotriptycene (430 mg, 0.68 mmol), and dry N,N-dimethylformamide (10 mL). The reaction mixture was stirred for 30 min at room temperature and then heated at 110 8C for 5 days. After cooling to room temperature, the resulting mixture was added to 120 mL of water and the suspension was filtered. The solid was washed with water, dried at 60 8C in vacuo for 12 h, and purified by flash column chromatography on silica gel (petroleum ether/dichloromethane 7:1) to give 300 mg (58.8 % yield) of white product. 1H NMR (400 MHz, [D6]DMSO): d = 8.25 (t, J = 6.8 Hz, 6 H), 7.92–7.83 (m, 6 H), 7.42–7.37 (m, 15 H), 7.31–7.26 (m, 6 H), 6.19 (s, 1 H), 6.16 ppm (s, 1 H); 13C NMR (100 MHz, CDCl3): d = 146.76, 146.63, 143.82, 143.68, 140.98, 140.95, 135.21, 135.17, 125.94, 125.25, 125.17, 124.28, 124.22, 123.38, 122.72, 122.68, 120.36, 120.02, 109.96, 109.92, 53.74, 53.54 ppm. EIMS: m/z 749 (M + ). Anal. calcd for C56H35N3 : C, 89.69; H, 4.70; N, 5.60; found: C, 89.82; H, 4.90; N, 5.36.
Keywords: gas adsorption · polymers · synthesis · triptycene
TCT (200 mg, 0.27 mmol) was dissolved in 15 mL of anhydrous chloroform and then transferred dropwise to a suspension of anhydrous FeCl3 (1.8 g, 11 mmol) in 10 mL of anhydrous chloroform. The solution mixture was stirred at room temperature for 1 d, and then 100 mL of methanol was added to the above reaction mixture. The resulting suspension was collected by filteration and washed with MeOHl until the filtrate became clear. The product was then Soxhlet extracted with MeOH for 24 h, and then with THF for another 24 h. Subsequently, the obtained product was dried in vacuo at 80 8C for 1 d. Yield: 170 mg (85.0 %).
Synthesis of TCP-B Anhydrous FeCl3 (9.75 g, 0.06 mol) was added to a solution of TCT (130 mg, 0.17 mmol) and FDA (93 mL, 1.04 mmol) in 10 mL 1, 2-dichloroethane. The resulting mixture was stirred for 5 min at room temperature. Subsequently, it was heated to 80 8C and stirred for 24 h at this temperature. After cooling to room temperature, the resulting suspension was collected by filtration and washed with MeOH until the filtrate became clear. The product was then Soxhlet extracted with MeOH for 36 h. The obtained product was dried in vacuo at 80 8C for 2 d. Yield: 127 mg (88.0 %).
Gas Sorption Analysis of TCPs Surface areas and pore size distributions were measured by nitrogen adsorption and desorption at 77 K using a Micromeritics ASAP 2020 volumetric adsorption analyzer. Samples were degassed at 110 8C for 15 h under vacuum before analysis. Hydrogen isotherms were measured at 77 K up to 1 bar, and CO2 isotherms were measured at 273 K and 298 K up to 1 bar using a Micromeritics ASAP 2020 volumetric adsorption analyzer with the same degassing procedure. www.chemasianj.org
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Synthesis of TCP-A
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Manuscript received: October 11, 2015 Accepted Article published: November 13, 2015 Final Article published: November 26, 2015
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Gas Uptake
Microporous Polymers from a Carbazole-Based Triptycene Monomer: Synthesis and Their Applications for Gas Uptake Tian-Long Zhai,[a] Liangxiao Tan,[b] Yi Luo,[a] Jun-Min Liu,*[c] Bien Tan,*[b] Xiang-Liang Yang,[a] Hui-Bi Xu,[a] and Chun Zhang*[a] Abstract: Two kinds of novel organic microporous polymers TCPs (TCP-A and TCP-B) were prepared by two cost-effective synthetic strategies from the monomer of tricarbazolyltriptycene (TCT). Their structure and properties were characterized by FT-IR, solid 13C NMR, powder XRD, SEM, TEM, and
gas absorption measurements. TCP-B displayed a high surface area (1469 m2 g¢1) and excellent H2 storage (1.70 wt % at 1 bar/77 K) and CO2 uptake abilities (16.1 wt % at 1 bar/ 273 K), which makes it a promising material for potential application in gas storage.
Introduction
in gas storage,[13] separations,[14] catalysis,[15] sensors,[16] and energy storage.[17] However, multistep synthesis processes, expensive catalysts, and rigorous experimental conditions of these OMPs may limit their scale-up applications. Easy availability, low cost, and high surface area are keys for OMPs to be applied in gas storage and capture of CO2. Recently, Tan and co-workers developed a low-cost knitting synthetic strategy for HCPs by employing a simple one-step Friedel–Crafts reaction using formaldehyde dimethyl acetal (FDA) as an external cross-linker.[18] Moreover, Han’s group[13, 19] prepared porous polycarbazoles through a simple and convenient way by FeCl3-catalyzed oxidative coupling polymerization, and furthermore proved that carbazole is an efficient building block for producing OMPs, which has also been confirmed by other groups.[20] Inspired by these interesting works, we envisioned that the introduction of triptycenes into a polycarbazole scaffold by low-cost synthetic strategies would result in novel porous copolymers, which may combine the advantages of triptycene with carbazole, and thus afford new materials for scale-up applications in gas storage and capture of CO2. Herein, we employed two cost-effective synthetic strategies to polymerize the tricarbazolyltriptycene (TCT) monomer and prepared two kinds of microporous polymers (TCP-A and TCPB), which displayed a high surface area, high gas-uptake capacity, thermal stability, good CO2 adsorption, and a good selectivity toward CO2 over N2.
With their three-dimensional rigid structure, triptycene and its derivatives have attracted great interest in supramolecular chemistry and materials science because of their perfect C3 symmetry and ease of functionalization.[1] For example, interlocked structures,[2] supramolecular hosts,[3] cage compounds[4] and conjugated polymers[5] have been synthesized by using triptycenes as main building blocks. Recently, our[6] and other groups[7] have proved that triptycene derivatives could also be utilized as useful building blocks for developing novel organic microporous polymers (OMPs). In the field of OMPs, different kinds of polymers, such as covalent organic frameworks (COFs),[8] hypercross-linked polymers (HCPs),[9] polymers of intrinsic microporosity (PIMs),[10] conjugated microporous polymers (CMPs),[11] and porous aromatic frameworks (PAF)[12] have been developed by templatefree chemical processes because of their potential applications [a] T.-L. Zhai,+ Y. Luo, Prof. X.-L. Yang, Prof. H.-B. Xu, Dr. C. Zhang Key Laboratory of Molecular Biophysics of the Ministry of Education College of Life Science and Technology Huazhong University of Science and Technology National Engineering Research Center for Nanomedicine Hubei, 430074 (China) E-mail: [email protected]
[b] Dr. L. Tan,+ Prof. Dr. B. Tan School of Chemistry and Chemical Engineering Huazhong University of Science and Technology Hubei, 430074 (China) E-mail: [email protected]
Results and Discussion With three carbazole moieties, the TCT monomer was synthesized easily by a copper-catalyzed N-arylation reaction between carbazole and 2,6,14-triiodotriptycene[21] (Scheme S1, Supporting Information). The synthesis of polymers TCP-A and TCP-B is outlined in Scheme 1. For TCP-A, oxidative coupling polymerization of TCT catalyzed by anhydrous FeCl3 in dry chloroform at room temperature afforded a pale yellow
[c] Dr. J.-M. Liu School of Chemistry and Chemical Engineering Sun Yat-Sen University Guangzhou, 510275 (China) E-mail: [email protected] [+] These authors contributed equally to this work. Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/asia.201501105. Chem. Asian J. 2016, 11, 294 – 298
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Full Paper the IR spectra (Supporting Information, Figure S3), the symmetric and asymmetric C-H stretching bands of methylene were observed at 2856 and 2927 cm¢1 in the framework of TCP-B. Field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were employed to investigate the morphology of TCPs. As shown in Figure 2, both
Scheme 1. Synthesis of TCPs. Reagents and conditions: (i) FeCl3, chloroform, 25 8C, 24 h; (ii) FDA, FeCl3, 1,2-dichloroethane, 80 8C, 24 h.
powder in a yield of 85.0 %. For TCP-B, the polymerization of TCT with 6 equivalents of formaldehyde dimethyl acetal (FDA) produced a brown powder in yield of 88.0 %. The obtained polymers were insoluble in common organic solvents. The structures of TCPs were characterized by 13C CP/ MAS NMR (CP/MAS = cross-polarization magic angle spinning) and FT-IR spectroscopies. As shown in Figure 1, the resonance peaks at d = 141, 130, 120, 106 and 51 ppm can be assigned to the substituted phenyl carbons, the unsubstituted phenyl carbons, and the methylidyne bridge carbons in the triptycene scaffold, respectively. For TCP-B, the small peaks at d = 67 and 36 ppm can be assigned to carbons in the unreacted hydroxymethyl groups (o) and the methylene linker (n), respectively. In
Figure 2. SEM and TEM images of TCP-A (a and c) and TCP-B (b and d). Scale bars: 1 mm (a and b) and 500 nm (c and d).
polymers were composed of amorphous rough particles similar to those observed in triptycene microporous networks.[6] From the broad peaks in the powder X-ray diffraction spectrum (Supporting Information, Figure S4), both polymers are noncrystalline. Thermogravimetric analysis (TGA) showed that TCPs are stable up to 550 8C in air (Supporting Information, Figure S5). To analyze the porous properties of TCPs, nitrogen sorption analyses at 77 K were utilized. The Brunauer–Emmett–Teller (BET) surface areas were determined to be 893 and 1469 m2 g¢1 (Langmuir surface areas are 1180 and 1812 m2 g¢1), and the total volumes were 0.59 and 0.76 cm3 g¢1 for TCP-A and TCP-B, respectively. As shown in Figure 3 a, the nitrogen adsorption isotherms indicate a steep nitrogen gas uptake at low relative pressure (P/P0 < 0.001), thus reflecting the abundant micropore structure in the networks of TCPs. Low pressure hysteresis was observed to extend to the lowest attainable pressure, and this phenomenon is associated with the irreversible uptake of gas molecules in the mesopores (or through pore entrances). In the desorption isotherm, low pressure unclosed hysteresis was observed owing to the elastic deformation or swelling effect of the polymer skeleton, which commonly exists in amorphous microporous polymer networks. The pore size distribution (Figure 3 b) calculated using nonlocal density functional theory (NLDFT) methods also confirmed the presence of primary micropores and a spot of mes-
Figure 1. 13C MAS NMR spectra of TCP-A (a) and TCP-B (b). Asterisks denote spinning sidebands. Chem. Asian J. 2016, 11, 294 – 298
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Figure 3. Nitrogen sorption isotherms at 77 K (a), pore size distributions calculated using NLDFT methods (b), H2 adsorption isotherms and desorption isotherms up to 1.0 bar at 77 K (c) and CO2 adsorption isotherms and desorption isotherms at 273 K (d) of TCP-A and TCP-B.
Clapeyron equation,[26] were 27 and 24 kJ mol¢1, respectively (Supporting Information, Figure S7). The selectivity of TCPs toward CO2 over N2 was investigated by single-component gas sorption experiments at 273 K. Calculating the initial slopes of adsorption isotherms (Supporting Information, Figures S8 and S9), the CO2/N2 selectivities were 26 and 19 for TCP-A and TCP-B, respectively.
opores. Compared with TCP-A, the greatly improved porosity properties of TCP-B suggested that the use of an external cross-linker with FDA to cross-link networks might result in polymer chains that possess more abundant micropores. Hydrogen sorption and desorption measurements of TCPs were carried out at 77 K. As shown in Figure 3 c, TCP-A can absorb 1.27 wt % of H2 at 1.0 bar. TCP-B can absorb 1.70 wt % H2 at 1.0 bar, a value that is larger than that determined for most triptycene-based polymers. As shown in Figure 3 d, TCPA and TCP-B can absorb CO2 (273 K, 1.0 bar) with the capabilities of 12.5 wt % and 16.1 wt %, respectively. The good CO2 uptake capacity of TCP-B is higher than that of a reported porous aromatic framework (PAF-1) (9.1 wt %) with an ultrahigh BET surface area of 5600 m2 g¢1,[22] commercially available BPL carbon (9.2 wt %),[23] and some heteroatom (nitrogen)-containing polymeric skeleton like TBI with an uptake capacity of 11.8 wt %[7a] and reported triptycene-based cages (11.0 wt %) with a high BET surface area of 1700 m2 g¢1,[24] and is comparable to Trçger’s-base-derived polymer TB-MOP under the same conditions.[25] At 298 K, the CO2 uptake capacities were 7.1 wt % and 9.0 wt % for TCP-A and TCP-B, respectively (Supporting Information, Figure S6). The excellent CO2 adsorption property of TCP-B may result from the perfect match of the microporous structure with the size of CO2. To understand the adsorption process, the isosteric enthalpy (Qst) values of TCP-A and TCP-B toward CO2, calculated from the adsorption isotherms at 273 and 298 K using the Clausius– Chem. Asian J. 2016, 11, 294 – 298
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Conclusions In summary, we synthesized two kinds of porous polymers, TCP-A and TCP-B, from low-cost reactions, using carbazolebased triptycene as monomer. With high thermal stability and high surface area, the porous polymers based on TCT are promising candidate materials for hydrogen storage and carbon dioxide capture. Further functionalization of these TCPs to improve the porous properties and to achieve the uptake of a catalyst are undergoing in our lab.
Experimental Section Characterization Methods and Instruments The 13C CP/MAS NMR spectra were recorded with a contact time of 2 ms (ramp 100) and pulse delay of 3 s. SEM measurements were performed on a Sirion 200 field-emission scanning electron microscope. TEM studies were conducted on a Tecnai G220 electron mi-
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croscope. TGA measurements were performed on a Pyrisl TGA instrument. Materials were obtained commercially and used without further purification.
This work is supported by the National Natural Science Foundation of China (20902031, 21272292 and J1103514), the National Basic Research Program (2012CB932500), and the Fundamental Research Funds for the Central Universities (HUST 2015TS086). We thank the Analytical and Testing Center of Huazhong University of Science and Technology for related analysis. We also thank to the facility support of the Center for Nanoscale Characterization and Devices, Wuhan National Laboratory for Optoelectronics (WNLO).
Synthesis of TCT Under nitrogen atmosphere, a 25 mL flask was charged with anhydrous potassium carbonate (575 mg, 4.2 mmol), copper iodide (134 mg, 0.7 mmol), 1,10-phenanthroline (13 mg, 0.06 mmol), carbazole (578 mg, 3.5 mmol), 2,6,14-triiodotriptycene (430 mg, 0.68 mmol), and dry N,N-dimethylformamide (10 mL). The reaction mixture was stirred for 30 min at room temperature and then heated at 110 8C for 5 days. After cooling to room temperature, the resulting mixture was added to 120 mL of water and the suspension was filtered. The solid was washed with water, dried at 60 8C in vacuo for 12 h, and purified by flash column chromatography on silica gel (petroleum ether/dichloromethane 7:1) to give 300 mg (58.8 % yield) of white product. 1H NMR (400 MHz, [D6]DMSO): d = 8.25 (t, J = 6.8 Hz, 6 H), 7.92–7.83 (m, 6 H), 7.42–7.37 (m, 15 H), 7.31–7.26 (m, 6 H), 6.19 (s, 1 H), 6.16 ppm (s, 1 H); 13C NMR (100 MHz, CDCl3): d = 146.76, 146.63, 143.82, 143.68, 140.98, 140.95, 135.21, 135.17, 125.94, 125.25, 125.17, 124.28, 124.22, 123.38, 122.72, 122.68, 120.36, 120.02, 109.96, 109.92, 53.74, 53.54 ppm. EIMS: m/z 749 (M + ). Anal. calcd for C56H35N3 : C, 89.69; H, 4.70; N, 5.60; found: C, 89.82; H, 4.90; N, 5.36.
Keywords: gas adsorption · polymers · synthesis · triptycene
TCT (200 mg, 0.27 mmol) was dissolved in 15 mL of anhydrous chloroform and then transferred dropwise to a suspension of anhydrous FeCl3 (1.8 g, 11 mmol) in 10 mL of anhydrous chloroform. The solution mixture was stirred at room temperature for 1 d, and then 100 mL of methanol was added to the above reaction mixture. The resulting suspension was collected by filteration and washed with MeOHl until the filtrate became clear. The product was then Soxhlet extracted with MeOH for 24 h, and then with THF for another 24 h. Subsequently, the obtained product was dried in vacuo at 80 8C for 1 d. Yield: 170 mg (85.0 %).
Synthesis of TCP-B Anhydrous FeCl3 (9.75 g, 0.06 mol) was added to a solution of TCT (130 mg, 0.17 mmol) and FDA (93 mL, 1.04 mmol) in 10 mL 1, 2-dichloroethane. The resulting mixture was stirred for 5 min at room temperature. Subsequently, it was heated to 80 8C and stirred for 24 h at this temperature. After cooling to room temperature, the resulting suspension was collected by filtration and washed with MeOH until the filtrate became clear. The product was then Soxhlet extracted with MeOH for 36 h. The obtained product was dried in vacuo at 80 8C for 2 d. Yield: 127 mg (88.0 %).
Gas Sorption Analysis of TCPs Surface areas and pore size distributions were measured by nitrogen adsorption and desorption at 77 K using a Micromeritics ASAP 2020 volumetric adsorption analyzer. Samples were degassed at 110 8C for 15 h under vacuum before analysis. Hydrogen isotherms were measured at 77 K up to 1 bar, and CO2 isotherms were measured at 273 K and 298 K up to 1 bar using a Micromeritics ASAP 2020 volumetric adsorption analyzer with the same degassing procedure. www.chemasianj.org
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Manuscript received: October 11, 2015 Accepted Article published: November 13, 2015 Final Article published: November 26, 2015
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