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[Electronic Supplementary Information]

Facile synthesis of –C=N– linked covalent organic

frameworks under ambient conditions

San-Yuan Ding,ab Xiao-Hui Cui,b Jie Feng,b Gongxuan Lu,*a and Wei Wang*b

aState Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of

Chemical Physics, Chinese Academy of Science, Lanzhou 730000, China.

E-mail: gxlu@lzb.ac.cnbState Key Laboratory of Applied Organic Chemistry, College of Chemistry and

Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, China.

E-mail: wang_wei@lzu.edu.cn

A. Summary of Tables and Figures S2

B. General Information S3

C. Synthetic Procedures S4

D. Structural Modeling and Powder X-Ray Diffraction Analysis S7

E. 13C CP/MAS NMR Spectra S14

F. N2 Adsorption-Desorption Analysis S16

G. Scanning Electron Micrographs S22

H. FT-IR Spectra S23

I. References S25

Electronic Supplementary Material (ESI) for Chemical Communications.This journal is © The Royal Society of Chemistry 2017

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A. Summary of Tables and FiguresTable S1 Fractional atomic coordinates for the unit cell of Pr-COF-42 S8Fig. S1 PXRD patterns of Pr-COF-42 observed and calculated (eclipsed) S9Fig. S2 PXRD patterns of Pr-COF-42 observed and calculated (staggered) S9Fig. S3 Observed and Pawley-refined PXRD patterns of Pr-COF-42 S10Fig. S4 PXRD patterns of COF-42 samples prepared with different solvents S10Fig. S5 PXRD patterns of COF-42 samples prepared without the acid S11Fig. S6 PXRD pattern of bulky COF-42 prepared under ambient conditions S11Fig. S7 PXRD pattern of COF-LZU1 prepared in EtOH/6 M HOAc (5/1) S12Fig. S8 PXRD pattern of bulky COF-LZU1 prepared under ambient conditions S12Fig. S9 PXRD patterns of COF-43, Pr-COF-42, and COF-LZU1 prepared by using

different amounts of HOAc under ambient conditions S13Fig. S10 PXRD patterns of COF-42, COF-43, Pr-COF-42, and COF-LZU1 prepared

by using 6 M hydrochloric acid (HCl), 6 M nitric acid (HNO3), and 6 Mformic acid (HCOOH) under ambient conditions S13

Fig. S11 13C CP/MAS NMR spectrum of COF-43 prepared at ambient conditions S14Fig. S12 13C CP/MAS NMR spectrum of Pr-COF-42 prepared at ambient conditions S14Fig. S13 13C CP/MAS NMR spectrum of COF-LZU1 prepared at ambient conditions S15Fig. S14 N2 isotherms of COF-42 prepared under ambient conditions S16Fig. S15 N2 isotherms of COF-43 prepared under ambient conditions S16Fig. S16 N2 isotherms of Pr-COF-42 prepared under ambient conditions S17Fig. S17 N2 isotherms of COF-LZU1 prepared under ambient conditions S17Fig. S18 BET surface area plot for COF-42 prepared under ambient conditions S18Fig. S19 BET surface area plot for COF-43 prepared under ambient conditions S18Fig. S20 BET surface area plot for Pr-COF-42 prepared under ambient conditions S19Fig. S21 BET surface area plot for COF-LZU1 prepared under ambient conditions S19Fig. S22 The pore size distribution of COF-42 prepared under ambient conditions S20Fig. S23 The pore size distribution of COF-43 prepared under ambient conditions S20Fig. S24 The pore size distribution of Pr-COF-42 prepared under ambient conditions S21Fig. S25 The pore size distribution of COF-LZU1 prepared under ambient conditions S21Fig. S26 SEM images of COF-42 prepared under ambient conditions S22Fig. S27 SEM images of COF-43 prepared under ambient conditions S22Fig. S28 FT-IR spectrum of COF-42 prepared under ambient conditions S23Fig. S29 FT-IR spectrum of COF-43 prepared under ambient conditions S23Fig. S30 FT-IR spectrum of Pr-COF-42 prepared under ambient conditions S24Fig. S31 FT-IR spectrum of COF-LZU1 prepared under ambient conditions S24

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B. General Information

Materials

All chemical reagents were purchased from commercial sources and used withoutfurther purification.

Instrumentation

Powder X-ray diffraction (PXRD) data were collected with a PANalytical X'Pert

Pro diffractometer operated at 40 kV and 40 mA with Cu K radiation (step size:0.017o, step time: 10.34 s). Solid-state NMR experiments were performed on a BrukerWB Avance II 400 MHz spectrometer. The 13C cross-polarization (CP) MAS NMRspectra were recorded with a 4-mm double-resonance MAS probe and with a samplespinning rate of 10.0 kHz. The 13C CP/MAS NMR measurements applied a contacttime of 2 ms (ramp 100) and a pulse delay of 3 s. The nitrogen adsorption anddesorption isotherms were measured at 77 K using a Micromeritics ASAP 2020Msystem. The samples were outgassed at 120 oC for 8 h before the measurements.Surface areas were calculated from the adsorption data using Brunauer-Emmett-Teller(BET) methods. The pore-size-distribution curves were obtained from the adsorptionbranches using the non-local density functional theory (NLDFT) method. Fieldemission scanning electron microscopy (SEM) observations were performed on aHitachi S-4800 microscope operated at an accelerating voltage of 5.0 kV. FT-IRspectra were recorded with a Nicolet NEXUS 670 instrument.

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C. Synthetic Procedures

1,3,5-Triformylbenzene1,2, 2,5-diethoxy-terephthalohydrazide3, 2,5-dipropoxyterep-

hthalohydrazide3, and 1,3,5-tris(4-formylphenyl)benzene4 were synthesized accordingto the reported procedures.

Synthesis of COF-42 under ambient conditions

2,5-Diethoxy-terephthalohydrazide (17 mg, 0.06 mmol) and 1,3,5-triformylbenzene(6 mg, 0.04 mmol) were weighed into a vial and suspended in a mixture of1,4-dioxane (1.5 mL) and mesitylene (1.0 mL). To the mixture were dropwise added0.2 mL of HOAc (6.0 M) under ambient conditions (about 20 oC, 1 atm). Afterkeeping still for 3 days, the faint yellow solid was isolated by centrifugation, washedwith acetone (3 × 5 mL) and tetrahydrofuran (3 × 5 mL). The final purified COF-42was obtained as a faint yellow powder. Yield: 15 mg, 72%.

Bulky production of COF-42 under ambient conditions

The procedure was almost the same as that mentioned above.2,5-Diethoxy-terephthalohydrazide (1.01 g, 3.6 mmol) and 1,3,5-triformylbenzene(0.39 g, 2.4 mmol) were weighed into a flask and suspended in a mixture of1,4-dioxane (60.0 mL) and mesitylene (40.0 mL). Then 12.0 mL of HOAc (6.0 M)were added dropwise to the mixture under ambient conditions (about 20 oC, 1 atm).After keeping still for 3 days, the faint yellow solid was isolated by filtration andwashed with acetone. Further purification was carried out by Soxhlet extraction inTHF for 24 h. The weight of final purified COF-42 was 1.3 g.

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Synthesis of COF-43 under ambient conditions

2,5-Diethoxy-terephthalohydrazide (17 mg, 0.06 mmol) and1,3,5-tris(4-formylphenyl)benzene (16 mg, 0.04 mmol) were weighed into a vial andsuspended in a mixture of 1,4-dioxane (0.5 mL) and mesitylene (1.5 mL). To themixture were dropwise added 0.2 mL of HOAc (6.0 M) under ambient conditions(about 20 oC, 1 atm). After keeping still for 3 days, the faint yellow solid was isolatedby centrifugation and washed with acetone (3 × 5 mL) and tetrahydrofuran (3 × 5 mL).The final purified COF-43 was obtained as a faint yellow powder. Yield: 19 mg, 62%.

Synthesis of Pr-COF-42 under ambient conditions

2,5-Dipropoxyterephthalohydrazide (19 mg, 0.06 mmol) and1,3,5-triformylbenzene (6 mg, 0.04 mmol) were weighed into a vial and suspended ina mixture of 1,4-dioxane (1.5 mL) and mesitylene (1.0 mL). To the mixture weredropwise added 0.2 mL of HOAc (6.0 M) under ambient conditions (about 20 oC, 1atm). After keeping still for 3 days, the faint yellow solid was isolated bycentrifugation and washed with acetone (3 × 5 mL) and tetrahydrofuran (3 × 5 mL).The final purified Pr-COF-42 was obtained as a faint yellow solid. Yield: 16 mg, 70%.Anal. Cald for (C10H11N2O2)n: C 62.82; H 5.76; N 14.66. Found: C 59.58; H 4.84; N13.42. The structure of Pr-COF-42 was elucidated by PXRD analysis (Figs. S1−S3),N2 adsorption and desorption isotherms (Fig.16), and 13C CP/MAS NMR spectrum(Fig. S12).

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Synthesis of COF-LZU1 under ambient conditions

1,3,5-Triformylbenzene (16 mg, 0.10 mmol) and 1,4-diaminobenzene (16 mg, 0.15mmol) were weighed into a vial and dissolved in 1,4-dioxane (1.0 mL) to obtain aclear solution. Then 0.2 mL of 3.0 M HOAc was added dropwise to the solution underambient conditions (about 20 oC, 1 atm). After keeping still for 3 days, the yellowsolid was isolated by centrifugation, washed with DMF (3 × 5 mL) and acetone (3 × 5mL). Further purification of COF-LZU1 was carried out by Soxhlet extraction in THFfor 24 h. The final purified COF-LZU1 was obtained as a yellow powder. Yield: 24mg, 91%. Note: COF-LZU1 could also be successfully synthesized in other solventsunder ambient conditions, such as in ethanol [EtOH/HOAc (6.0 M) = 5/1] (see FigureS7).

Bulky Synthesis of COF-LZU1 under ambient conditions

The procedure was almost the same as that mentioned above.1,3,5-Triformylbenzene (1.3 g, 8.0 mmol) and 1,4-diaminobenzene (1.3 g, 12.0 mmol)were weighed into a vial and dissolved in 1,4-dioxane (80.0 mL) to obtain a clearsolution. Then 16.0 mL of 3.0 M HOAc was added dropwise to the clear solution atambient conditions (about 20 oC, 1 atm). After keeping still for 3 days, the yellowsolid was isolated by filtration, washed with DMF and acetone. Further purificationwas carried out by Soxhlet extraction in THF for 24 h. The final purified COF-LZU1was 2.0 gram.

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D. Structural Modeling and Powder X-Ray Diffraction Analysis

Molecular modeling of Pr-COF-42 was generated with the Materials Studio (ver.6.0) suite of programs.5 The proposed structure of Pr-COF-42 is similar to that ofCOF-42,3 while the edge of the hexagonal ring was substituted by(N'1E,N'4E)-N'1,N'4-dibenzylidene-2,5-dipropoxyterephthalohydrazide. The proposedmodel was geometry-optimized using the MS Forcite molecular dynamics module(universal force fields, Ewald summations) to obtain the optimized lattice parametersof a = b = 30.735 Å and c = 3.934 Å. Pawley refinement produced the latticeparameters of a = b = 35.835 (± 2.984) Å and c = 4.907 (± 0.405) Å. The wRp and Rpvalues converged to 5.61 % and 4.33 %, respectively. Overlay of the observed andrefined profiles showed excellent agreement (see Fig. S3).

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Table S1. Fractional atomic coordinates for the unit cell of Pr-COF-42.

Pr-COF-42: Space group symmetry P-3

a = b = 30.735 Å c = 3.934 Åα = β = 90º γ = 120º

Atom x (Å) y (Å) z (Å)C1 -0.05159 -1.51582 -0.51848C2 -0.03428 -1.54754 -0.64173C3 0.01746 -1.53122 -0.61931O4 0.06945 -1.40631 -0.20775C5 0.05353 -1.37155 -0.11292C6 0.09879 -1.32306 0.01432C7 0.08494 -1.28274 0.08804C8 -0.10554 -1.53094 -0.53034N9 0.14184 -1.42161 -0.55936N10 0.19281 -1.40780 -0.55123C11 0.22803 -1.36195 -0.60690C12 0.28139 -1.34809 -0.60196C13 -0.29580 -1.61523 -0.39778O14 -0.11750 -1.50011 -0.61382H15 0.03212 -1.55430 -0.71511H16 0.02499 -1.38788 0.09219H17 0.03709 -1.36278 -0.33529H18 0.12929 -1.30852 -0.17806H19 0.11344 -1.33104 0.24891H20 0.05228 -1.29731 0.26266H21 0.07532 -1.27036 -0.15113H22 0.11736 -1.24976 0.20788H23 0.13159 -1.39591 -0.64663H24 0.21838 -1.33300 -0.65286H25 -0.26754 -1.57573 -0.39547

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Fig. S1 PXRD patterns of Pr-COF-42, observed (black) and calculated with theeclipsed (green) stacking model. Comparison of the observed and the simulatedPXRD patterns suggested that the preferable structure of Salen-COF is the eclipsedarrangement. Inset: Eclipsed model of Pr-COF-42. C, gray; N, blue; O, red; H atomsomitted for clarity.

Fig. S2 PXRD patterns of Pr-COF-42, observed (black) and calculated with thestaggered (green) stacking model. For clarity, C (gray), N (blue), and O (red) atomsare shown only on the top layer and the next layer is presented in yellow.

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Fig. S3 Observed PXRD pattern (black), the Pawley-refined pattern (green), and thedifference plot (blue) of Pr-COF-42.

Fig. S4 Comparison of the observed PXRD patterns of COF-42 prepared underambient conditions with indicated ratios of dioxane/mesitylene (v/v) [3/1 (green), 3/2(red), 1/1 (purple), 2/3 (blue), and 1/3 (black)]. The optimized ratio ofdioxane/mesitylene (v/v) is 3/2, which results in the material with the highest PXRDpeak intensity (red).

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Fig. S5 Comparison of the observed PXRD patterns of COF-42 samples preparedunder ambient conditions without the addition of acid (red) and the starting material[2,5-diethoxy-terephthalohydrazide (black)], which indicates that no condensationproduct was obtained under these conditions.

Fig. S6 PXRD pattern of bulky COF-42 prepared under ambient conditions.

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Fig. S7 PXRD pattern of COF-LZU1 prepared in ethanol/6.0 M HOAc (5/1) underambient conditions.

Fig. S8 PXRD pattern of bulky COF-LZU1 prepared under ambient conditions.

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Fig. S9 PXRD patterns of COF-43, Pr-COF-42, and COF-LZU1 prepared by usingdifferent amounts of HOAc under ambient conditions.

Fig. S10 PXRD patterns of COF-42, COF-43, Pr-COF-42, and COF-LZU1 preparedby using 6 M hydrochloric acid (HCl), 6 M nitric acid (HNO3), and 6 M formic acid(HCOOH) under ambient conditions. Note: No solid was obtained when 6 M HNO3

was used to synthesize COF-LZU1.

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E. 13C CP/MAS NMR Spectra

Fig. S11 13C CP/MAS NMR spectrum of COF-43 prepared under ambient conditions.Asterisks indicate the spinning sidebands. The assignments of 13C NMR chemicalshifts were indicated in the chemical structure.

Fig. S12 13C CP/MAS NMR spectrum of Pr-COF-42 prepared under ambientconditions. Asterisks indicate the spinning sidebands. The assignments of 13C NMRchemical shifts were indicated in the chemical structure.

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Fig. S13 13C CP/MAS NMR spectrum of COF-LZU1 prepared under ambientconditions. Asterisks indicate the spinning sidebands. The assignments of 13C NMRchemical shifts were indicated in the chemical structure.

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F. N2 Adsorption-Desorption Analysis

Fig. 14 Nitrogen adsorption (filled symbols) and desorption (empty symbols)isotherms of COF-42 prepared under ambient conditions.

Fig. S15 N2 adsorption (filled symbols) and desorption (empty symbols) isotherms ofCOF-43 prepared under ambient conditions. The adsorption isotherms exhibited atypical type-IV shape, indicating that COF-43 possesses a mesoporous structure.

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Fig. 16 Nitrogen adsorption (filled symbols) and desorption (empty symbols)isotherms of Pr-COF-42 prepared under ambient conditions.

Fig. 17 Nitrogen adsorption (filled symbols) and desorption (empty symbols)isothermals of COF-LZU1 prepared under ambient conditions.

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Fig. S18 BET surface area plot for COF-42 prepared under ambient conditionscalculated from the N2 isotherms.

Fig. S19 BET surface area plot for COF-43 prepared under ambient conditionscalculated from the N2 isotherms.

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Fig. S20 BET surface area plot for Pr-COF-42 prepared under ambient conditionscalculated from the N2 isotherms.

Fig. S21 BET surface area plot for COF-LZU1 prepared under ambient conditionscalculated from the N2 isotherms.

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Fig. S22 COF-42 prepared under ambient conditions showed a pore-size-distributioncentered at 2.0 nm, which is close to that of COF-42 prepared via the solvothermalmethod in a sealed vessel (2.3 nm).3

Fig. S23 COF-43 prepared under ambient conditions showed a pore-size-distributioncentered at 3.2 nm, which is close to that of COF-43 prepared via the solvothermalmethod in a sealed vessel (3.8 nm).3

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Fig. S24 Pr-COF-42 prepared under ambient conditions showed apore-size-distribution centered at 1.8 nm, which is close to that calculated from theeclipsed model of Pr-COF-42 (2.0 nm).

Fig. S25 COF-LZU1 prepared under ambient conditions showed apore-size-distribution centered at 1.2 nm, which is identical to that of COF-LZU1prepared via the solvothermal method in a sealed vessel (1.2 nm).6

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G. Scanning Electron Micrographs

Fig. 26 SEM images of COF-42 prepared under ambient conditions.

Fig. 27 SEM images of COF-43 prepared under ambient conditions.

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H. FT-IR Spectra

Fig. 28 FT-IR spectrum of COF-42 prepared under ambient conditions.

Fig. 29 FT-IR spectrum of COF-43 prepared under ambient conditions.

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Fig. 30 FT-IR spectrum of Pr-COF-42 prepared under ambient conditions.

Fig. 31 FT-IR spectrum of COF-LZU1 prepared under ambient conditions.

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I. References

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2. P. Pandey, A. P. Katsoulidis, I. Eryazici, Y. Y. Wu, M. G. Kanatzidis, S. T.Nguyen, Chem. Mater. 2010, 22, 4974.

3. F. J. Uribe-Romo, C. J. Doonan, H. Furukawa, K. Oisaki, O. M. Yaghi, J. Am.Chem. Soc. 2011, 133, 11478.

4. H. Konno, S. Aoyama, K. Nosaka, K. Akaji, Synthesis, 2007, 2007, 3666.

5. Materials Studio v.6.0 (Accelrys Software, San Diego, 2013).

6. S.-Y. Ding, J. Gao, Q. Wang, Y. Zhang, W.-G. Song, C.-Y. Su, W. Wang, J. Am.Chem. Soc., 2011, 133, 19816;