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Journal of Materials Chemistry A
Page 2 of 11
ARTICLE
Journal Name
chemically cross-linked with polymeric chitosan binder via was recrystallized in diethyl ether-methanol mixtuVierwe A(r1tic:1le,Ovn/linve)
DOI: 10.1039/C8TA12046C
photoinduced thiol-ene reaction and followed by a facile to obtain IL-ADH as white crystalline solids (0.223 g, 49 %). FT-
templated freeze-drying step. Besides selective CO2 separation, IR (KBr, cm−1): 3432 (w), 3311 (w), 3258 (m), 3146 (m), 1661
the generated COF-IL@chitosan aerogel can be a simplified (s), 1640 (s), 1528 (m), 1491 (m), 1333 (s), 1150 (s), 959 (m),
1
fixed-bed reactor model to highly promote the scale-up CO2 874 (m), 846 (m), 744 (m), 642 (m). H NMR (400MHz, DMSO-
catalytic cycloaddition in a recycling way.
d6, δ): 4.59 (4H, s, -NHNH2), 4.87 (2H, q, -NCH2CH-), 5.19-5.37
(2H, d, -CHCH2), 5.56 (2H, s, -ArCH2N-), 6.01-6.05 (1H, m, -
CH2CHCH2),7.77 (2H, d, -NCHCHN-), 7.75 (1H, s, -Ar), 7.82-7.90
(2H, d, -Ar), 9.23 (1H, s, -NCHN-), 9.88-9.94 (2H, d, -NHNH2).
ESI-MS: Calcd for C15H19N6O2 M+, m/z 315.16; found, m/z
315.15; 13C NMR (400 MHz, DMSO-d6, δ): 166.95 (-NHCOAr-),
165.08 (-NHCOAr-), 137.25 (-COAr-), 137.06 (-COAr-), 135.65 (-
NCHN-), 133.32 (-ArCH2-), 132.19 (-CH2CHCH2), 129.72 (-Ar),
128.67 (-Ar), 127.8 (-Ar), 123.37 (-NCHCH-), 123.07 (-CHCHN-),
120.7 (-CHCH2), 51.39 (-ArCH2N-), 50.36 (-NCH2CH-).
Experimental
Materials and method
The CO2 cycloaddition reactions were carried out under a
prepurified CO2 atmosphere using vacuum line techniques. All
chemicals were obtained from commercial sources and used
without further purification. 1,3,5-Triformylphloroglucinol (Tp)
was synthesized according to our reported method.31 The thiol
group-modified chitosan (termed as chitosan-SH) was
synthesized according to the literature method.32 The
precursors of A, B, and C for IL-ADH were synthesized
according to our previous report with slight modification.14 All
the characterization data for the known compounds provided
in ESI were well consistent with those reported results. Proton
Synthesis and characterization of COF-IL
A mesitylene (5 mL) and 1,4-dioxane (5 mL) mixed solution of IL-
ADH (472 mg, 1.5 mmol), Tp (210 mg, 1.0 mmol), and acetic acid
(1.0 mL, 6 M) in a pyrex tube was flash frozen in a liquid nitrogen
bath and degassed. Upon warming to room temperature, the tightly
nuclear magnetic resonance (1H-NMR) data were obtained on capped tube was heated at 120 °C for 3 days. The obtained
a
Bruker Avance-400 HD spectrometer with the
precipitate was collected by centrifugation and completely washed
with acetone, THF, and ethanol. The collected solids were dried in
vacuum at 80 °C for 12 h to generate the as-synthesized COF-IL
crystals as brownish red crystalline solids (556 mg, 82 % yield).
Elemental analysis: calcd for (C24H23N6O7Br)n (desolvated) (%): C
49.06, H 4.00, N 14.31, Br, 13.62; found (%): C 49.24, H 4.08, N
14.09, Br, 13.24. FT-IR (KBr, cm-1): 3391 (w), 2974 (w), 1628 (s),
1590 (s), 1557 (m), 1454 (s), 1286 (s), 1188 (m), 1155 (m), 1045 (m),
875 (m), 636 (w). Solid-state 13C CP-MAS NMR (500 MHz, δ): 167.4,
163.3, 147.1, 141.2, 138.1, 134.9, 132.3, 129.7-127.6, 124.34, 123.0,
120.6, 100.4, 53.5, 51.9.
tetramethylsilane (TMS) as the internal tagging. Fourier
transform infrared spectrometry (FT-IR) spectra were
performed in the 400-4000 cm-1 range using a Bruker ALPHA
spectrometer. High-resolution mass spectrometry analysis was
carried out on a Bruker maXis ultrahigh resolution mass
spectrometer. Elemental analyses were performed on a
PerkinElmer model 2400 analyser. Inductively coupled plasma
(ICP) measurement was performed on an IRIS Intrepid (II) XSP
and Nu AttoM. The solid-state 13C cross-polarization magic
angle spinning (CP-MAS) NMR spectra were obtained on
Bruker AVANCE III 400 spectrometer. Scanning electron
microscopy (SEM) was conducted on a Gemini Zeiss SUPRA
scanning electron microscope equipped with an energy-
dispersive X-ray detector. The X-ray diffraction pattern was
measured on a D8 Advance X-ray powder diffractometer with
the Cu Kα radiation (λ = 1.5405 Å). The N2, CO2, CH4, and H2
adsorption-desorption isotherms were performed on an ASAP
2020/TriStar 3000 (Micromeritics), after exchanged with
acetone and ethanol for 48 h, centrifugation and drying
thoroughly, about 300 mg sample was loaded in a sample tube
and dried under high vacuum at 383 K for 12 h to remove the
residual solvent molecules in the channels as previously
described.13 Thermogravimetric analysis (TGA) were performed
on a TA Instrument Q5 simultaneous TGA at a heating rate of
10 °C min-1 from 25 to 650 °C under a 60 mL/min flowing
nitrogen. A lyophilizer (CHRIST ALPHA 1-2) was used to dry the
sample. The compressive curve of the cylindrical aerogel was
determined using an AGS-H 5kN instrument from Shimadzu,
Japan.
Fabrication of COF-IL@chitosan hybrid aerogel
COF-IL@chitosan was prepared by mixing crystalline COF-IL
(1.35 g) and photo-initiator of HMPP (150 μL) with acidic
chitosan aqueous solution (0.33 g of chitosan-SH, 120 μL of
HOAc, and 10 mL of deionized water) with ultrasonic shaking.
After that, the sticky composite dispersion was immediately
transferred into suitable mould, which was allowed to stand at
room temperature for several hours until the robust hydrogel
formed. After a photo-initiated thiol-ene click reaction (365
nm, 300 W, 0.5 h), the obtained hydrogel was transferred into
a cooler for 12 h to generate and fix the ice crystals. After
freeze-drying at -50°C for 24 h to remove the ice crystals, a 3D
macroporous COF-IL@chitosan hybrid aerogel with 80 wt %
COF-IL content was obtained. For fabrication of the COF-
IL@chitosan based cuplike reactor, similar procedure was
conducted except a split-flask template was used.
Catalytic cycloaddition of CO2 with epoxides
Synthesis of IL-ADH
Reaction conditions. Epoxide substrate (13.0 mmol) was
stirred under CO2 atmosphere (1 atm) in the presence of COF-
A mixture of C (0.456 g, 1.45 mmol) and hydrazine hydrate
(0.425 mL, 8.7 mmol) in methanol (6 mL) was stirred for 14 h
at 30 °C. After removal of the solvent in vacuum, the residue
1
IL (3.0 mol%) at 80 °C for 48 h (monitored by H NMR). The
1
yield was determined by H NMR data. After reaction, COF-IL
2 | J. Name., 2012, 00, 1-3
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