Supporting Information Benzotrithiophene-based Covalent Organic Frameworks: Construction and Structure Transformation under Ionothermal Condition Hongtao Wei,
†,§
Jing Ning,
†,§
Xingdi Cao,
†,§
†
Xuehui Li, Long Hao*,
†
†College of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University, No.700 Changcheng Road, Qingdao, 266109, China §
These authors contribute equally to this work.
Corresponding author: L.H., E-mail:
[email protected]
Experimental Section: Materials: 1,3,5-Trichlorobenzene (99%), aluminium chloride (AlCl3, 99%), p-dithiane-2,5-diol (98%), 4,4’-diaminodiphenyl (DADP, 98%), 1,4-diaminobenzene (DAB, 98%), 1,3,5-tris(4-aminophenyl)benzene (TAB, 97%), and 4-tert-butyl benzenamine (99%) were purchased from Energy Chemical, Sun Chemical Technology (Shanghai) Co.. Carbon black (Super P conductive) was purchased from Alfa Aesar Company. Anhydrous zinc chloride (ZnCl2), polytetrafluoroethylene (PTFE, 60% dispersed in water) were purchased from Aldrich Company. These reagents were used as received. 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4, 97%) was purchased from aladdin®, and used after dryed at 120℃ in a vacuum oven for 12h. The glass microfiber separator (934-AHTM) for supercapacitors was purchased from WhatmanTM. The other reagents or solvents were of analytical purity, and used without further purification. Characterizations: The 1H, and 13C nuclear magnetic resonance (NMR) spectra were recorded on a Avance III HD 500MHz Superconducting FT NMR Spectrometer. The high resolution mass spectrum (MS) was collected from Thermo ScientificTM Q ExactiveTM. Powder X-ray diffraction (XRD) data were collected on a D8 Advance diffractometer in reflection geometry operating with a Cu Kα anode (λ = 1.54178 Å) at 30 kV and 40 mA. The attenuated total feflection Flourier transformed infrared (FT-IR) spectra of the samples were collected on a Nicolet iS50 spectrometer. The Ultraviolet–visible diffuse reflectance spectra (UV/vis DRS) were collected on a U-3900 UV-Vis Spectrophotometer. The X-ray photoelectron spectroscopy (XPS) measurements were carried out on a Thermo SCIENTIFIC ESCALAB 250Xi apparatus at base pressure of 1×10-9 mbar and X-ray source of Al Kα. Transmission electron microscopy (TEM) images were got from a Tecnai G2 F20 U-TWIN microscope. Nitrogen adsorption/desorption isotherms were measured at 77 K with an ASAP 2020 plus HD88 analyzer. The Brunauer-Emmett-Teller (BET) method and density functional theory (DFT) pore model were utilized to calculate the specific surface areas (SSAs) and pore size distributions, respectively. The electrochemical measurements were carried out on a CHI660 or Biologic VSP electrochemical workstation at room temperature. Experimental details:
Compounds 1 and 2 were prepared according to the previously literature with a little modification.S1 1,3,5-trichloro-2,4,6-tris(dichloromethyl)benzene (1) : 1,3,5-trichlorobenzene (3 g , 16.6 mmol), AlCl3 (2.6 g , 19.6 mmol), and CHCl3 (60 ml) were added to a high-pressure autoclave (100 ml), which was heated with stiring at 125℃ for 72 h. During the heating period, the autoclave was cooled to room temperature twice at 6 h and 18 h after the
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reaction started and opened to release the pressure. After 72 h, the reaction was cooled to room temperature, 60 mL of CHCl3 was added, and all the reaction mixture was poured into concentrated HCl/ice mixture and stirred for 1 h. Then, the organic layer separated was washed with NaHCO3, brine, and dried over MgSO4. After concentration, the brown solid was roughly purified by filtration through a silica plug (in hexane) to get 1 (5.16 g, 73%), which was used for the next synthesis of the compound 2. 2,4,6-trichlorobenzene-1,3,5-tricarbaldehyde (2). 1 (2.5 g, 5.8mmol) was added along with 18 ml of fuming sulfuric acid (20% SO3) into a 250ml three-neck round bottom flask, and stirred at 40℃ for 1 hour. Then, NaHCO3 (20g, 0.24mmol) and ice water were added slowly with the reaction flask immersed in an ice bath, carefully maintaining the temperature of the reaction mixture lower than 5℃. The formed precipitate was filtered off, washed with water, and then purified by filtration through a silica plug to get the light yellow product 2 (0.97g, 63%). 1H NMR (δ, CDCl3): 10.42 (s).
benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarbaldehyde (BTT). 2 (1.17 g, 4.4 mmol) and p-dithiane-2,5-diol (1 g, 6.6 mmol) were dispersed into 15 ml DMF in a three-necked flask at room temperature, then triethylamine (3.67ml, 26.4 mmol) was added, and the reaction system was heated at 35℃ with stirring for 8 h. Then, the reaction mixture was poured into ice water, the precipitate was centrifuged and washed constantly with water and THF respectively, yielding dark yellow BTT (1.06 g, 73%). M.P.>300℃. FT-IR: 1670 cm-1, 1600 cm-1, 1500 cm-1, 1335 cm-1, 1250 cm-1, 1175 cm-1, 850 cm-1, 740 cm-1, 720 cm-1, 660 cm-1, 500 cm-1. The BTT had bad solubility in any common solvents, consequently further characterization was not carried out. Its structure was indirectly proved through the systematically characterization of its Schiff-based condensation product with 4-tert-Butyl benzenamine (see the following reaction for details).
(1E,1'E,1''E)-1,1',1''-(benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-triyl)tris(N-(4-(tert-butyl)phenyl)methanimin e) (the model compound, MC). BTT (16.7 mg, 0.05 mmol), 4-tert-butyl benzenamine (26 ul, 0.163 mmol), 0.05 ml of 6M AcOH, 1.5 ml of 1,4-dioxane were charged into a 5ml Shlenk reaction tube. After sonication for 5min, degassed by three freeze-pump-thaw cycles, the reaction system was heated at 120℃ for 5 h. After cooling to room temperature, the precipitate was filtered off and recrystallized in 1,4-dioxiane to yield the yellow needle MC (31mg, 85%). M.P.>300℃. FT-IR: 2950 cm-1, 2900 cm-1, 2870 cm-1, 1620 cm-1, 1580cm-1, 1490 cm-1, 1370 cm-1, 1270 cm-1, 1170 cm-1, 1110 cm-1, 1080 cm-1, 1015 cm-1, 950 cm-1, 865 cm-1, 835 cm-1, 735cm-1, 690 cm-1, 640 cm-1, 570 cm-1, 530 cm-1,
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485 cm-1. 1H NMR (δ, DMSO-d6): 9.06 (s, 3H, N=CH), 8.44 (s, 3H, thiophene), 7.49 (d, 6H, Ph), 7.34 (d, 6H, Ph), 1.33 (s, 27H, CH3) (see details in the following figure). 13C NMR (δ, CDCl3): 151.88 , 149.99, 148.08 , 142.89 , 135.60 , 131.60 , 126.76, 126.18 , 120.91 , 34.63, 31.42 (see details in the following figure). TOF MS ES+: 724.2845 ([M+H] + ), Calcd. for C45H46N3S3+: 724.28484. 1
H NMR of MC:
13
C NMR of MC:
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Benzotrithiophene-based covalent organic frameworks (BTT-DADP COF, BTT-DAB COF and BTT-TAB COF). A 20 ml pyrex tube was charged with BTT (66.1 mg, 0.2 mmol), amines (55.3 mg, 0.3 mmol 4,4’-diaminodiphenyl (DADP) or 32.4 mg, 0.3 mmol 1,4-Diaminobenzene (DAB), or 70.3 mg, 0.2 mmol 1,3,5-Tris(4-aminophenyl)benzene (TAB)), 0.3 ml of 6M AcOH, 3 ml of ortho-dichlorobenzene (o-DCB) and 3 ml of n-butyl alcohol (n-BuOH). The mixture was sonicated for five minutes, degassed through three freeze-pump-thaw cycles, sealed under vacuum and heated at 120°C for 72 h. After cooling to room temperature, the precipitate was centrifuged and washed constantly with THF until the supernatant was clear. After dried in the vacuum oven at 120℃ over night, the corresponding COFs were synthesized.
Further cross-linked COFs (COF-700s, including BTT-DADP COF-700, BTT-DAB COF-700 and BTT-TAB COF-700). The as-prepared COF (200 mg, BTT-DADP COF, or BTT-DAB COF or BTT-TAB COF) and anhydrous ZnCl2 (1 g) were mixed uniformly in a glove box (argon with 0.1 ppm water), transferred into a 20 ml quartz ampoule, sealed under vacuum, and heated at 700℃ for 20 h. After cooled to room temperature, the ampoule was opened, the black complex inside was grinded and washed thoroughly with hot (80℃) 3M HCl, de-ionized water and THF. After dried under vacuum at 120℃ for 12 h, the COF-700 (BTT-DADP COF-700, or BTT-DAB COF-700 or BTT-TAB COF-700) was prepared. Note 1: During the workup of BTT-TAB COF-700, if only room temperature (instead of 80℃) HCl was used to wash the sample or the sample was not washed adequately, the prepared sample would contain ZnS2 impurity (see the XRD pattern in Figure 3a), which was named as BTT-TAB COF-700-untreated. Note 2: If ZnCl2 was not added, the prepared 700℃-treated COF would had very low BET specific surface area and irregular
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pore size distribution (Figure S5). Here, the ZnCl2 might have the function of padding and supporting the pore structures of the materials during the high-temperature treatment. Electrochemical measurements and calculations. A symmetric supercapacitor system (a CR2032 coin-type cell) was used with an ionic liquid, EMIMBF4 as the electrolyte, and all the supercapacitors were assembled at the same procedures. Typically, COF-700 (85 wt.%, about 100 mg), carbon black (10 wt.%, Super P conductive) and polytetrafluoroethylene (5 wt.%, 60 wt.% dispersion in water, and diluted to 6 wt. % before use) were mixed into a paste with an agate mortar, rolled into a uniform sheet, dried under vacuum at 120°C for 12 h, and cut to circular tablets of 12 mm (2.6-3.2 mg). Then two tablets with exactly the same mass were picked out and pressed on a stainless steel wire mesh (316L, 400 meshes, diameter of 15 mm) respectively as the two symmetric working electrodes, which were then separated by a glass fibre film separator, soaked into EMIMBF4 electrolyte to assemble the coin-type cell. Cyclic voltammetry (CV) curves, galvanostatic charge-discharge curves (GC), and Nyquist plots were collected on a electrochemical workstation at room temperature. The specific capacitance (C, F/g) was calculated from the slop of discharge curve using the formula:
C=
2 It mV
, where I (unit: A) is the discharge current, m (unit: g) is the mass of
COF-700 in one electrode, t (unit: s) is the discharge time, and V (unit: V) is the discharge voltage.
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Figure S1-S10:
Figure S1. The possible synthetic methods for BTT. The method used in this work is obviously the most facile one.
Figure S2. The supposed mechanism for the synthesis of BTT: the reaction procedure may include a Et3N-catalytic SNAr reaction followed by an intramolecular Adol reaction.
Figure S3. Schematic for the staggered structures of BTT-based COFs.
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Figure S4. (a) Nitrogen adsorption-desorption isotherms and (b) pore size distribution profiles of the typical 700℃ -treated BTT-DAB COF without ZnCl2 (the other preparation procedures are exactly the same as BTT-DAB COF-700), which shows the very low BET SSA of 15.6 m2/g and irregular pore size distribution. Here, the ZnCl2 might have the function of padding and supporting the pore structures of the materials during the high-temperature treatment.
Figure S5. (b) Typical TEM image of COF-700s (from BTT-DAB COF-700): COF-700s change to amorphous structures in contrast with the crystalline structures of the COFs (typically in Figure 2b).
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Figure S6. (a) XPS C1s spectra of COF-700s with ratios of sp2 hybridized carbon inserted. (b) The deconvolution results of the XPS C1s spectra of COF-700s. The peak at 284.6 eV is corresponding to the graphite-like sp2 hybridized carbon. The peaks at 285.7 eV and 286.9 eV are corresponding to the N-sp2 C and N-sp3 C, respectively. The peak at 288.8 eV is attributed to C-O type bond.S2 The ratios of sp2 hybridized carbon were calculated based on the following equation: the ratio of sp2 carbon =
Asp 2 Asp 2 + AN − sp2C + AN − sp3C + AC −O
×100% ,
in which A is the integrated peak areas of different kinds of carbon configurations.
Figure S7. CV curves of the COF-700-based supercapacitors at scan speeds of 25, 50, 100 mV/s.
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Figure S8. GC curves of the COF-700-based supercapacitors at different current densities.
Figure S9. (a) Nyquist plots of COF-700-based supercapacitors (AC frequency ranges from 100 000 to 0.01 Hz) with the enlarged parts inserted. The equivalent series resistances (extracted at 10 Hz) gradually increase from 6.51 ohm for BTT-DADP COF-700, 6.80 ohm for BTT-DAB COF-700 to 8.84 ohm for BTT-TAB COF-700.S3
Figure S10. Typical cycling performance of the COF-700-based supercapacitor at current density of 10 A/g.
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Table S1-S5:
Table S1. Fractional atomic coordinates for BTT-DADP-COF: space group P 6/m; a=b=35.916 Å, c=3.433 Å; alpha=beta=90°, gamma=120°.
Table S2. Fractional atomic coordinates for BTT-DAB-COF: space group P 6/m; a=b=28.582 Å, c=3.490 Å; alpha=beta=90°, gamma=120°.
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Table S3. Fractional atomic coordinates for BTT-TAB-COF: space group P-6; a=b=21.350 Å, c=3.505 Å; alpha=beta=90°, gamma=120°.
Table S4. Summary of the nitrogen adsorption/desorption measurement results of all the BTT-based materials.
Table S5. The element contents of the COF-700s from XPS measurements compared with the calculated element contents of the COFs.
Supplementary References: S1 Taerum, T.; Lukoyanova, O.; Wylie, R. G.; Perepichka, D. F. Org. Lett. 2009, 11, 3230. S2 Zhang, C.; Fu, L.; Liu, N.; Liu, M.; Wang, Y.; Liu, Z. Adv. Mater. 2011, 23, 1020. S3 Ra, E. J.; Raymundo-Piñero, E.; Lee, Y. H.; Béguin, F. Carbon 2009, 47, 2984.
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