Supplementary information

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1 Supplementary information Supplementary Information for Exceptional Ammonia Uptake by a Covalent Organic Framework Christian J. Doonan, David J. Tranchemontagne,T. Grant Glover, Joseph R. Hunt, Omar M. Yaghi* Center for Reticular Chemistry, Department of Chemistry and Biochemistry, University of California-Los Angeles, 607 Charles E. Young Drive East, Los Angeles, CA, 90095, USA nature chemistry 1 S1

2 Supporting Information Table of Contents Section S1 Materials and general procedures. S3 Section S2 X-ray Data Collection S3 Section S3 Gas Adsorption and Surface Area Data, COF-10, COF-102, COF-6 S4 Section S4 Pore Size Distribution Calculations S6 Section S5 Solid state 13 C CP/MAS nuclear magnetic resonance spectroscopy S7 S2 nature chemistry 2

3 Section S1: Materials and general procedures. All reagents unless otherwise stated were obtained from commercial sources (Alfa Aesar, Cambridge isotope laboratories, Sigma Aldrich) and were used without further purification. Yields reported were unoptimized. Elemental microanalyses were performed at the University of California, Los Angeles, Department of Chemistry and Biochemistry. Section S2: X-ray Data Collection Powder X-ray data were collected using a Bruker D8-Discover -2 diffractometer in reflectance Bragg-Brentano geometry employing Ni filtered Cu K line focused radiation at 1600 W (40 kv, 40 ma) power and equipped with a Vantec Line detector. Radiation was focused using parallel focusing Gobel mirrors. The system was also outfitted with an antiscattering shield which prevents incident diffuse radiation from hitting the detector, preventing the normally observed large background at 2 < 3º. Given that the particle size of the as synthesized samples were already found to be quite mono-disperse no sample grinding or sieving was used prior to analysis; we note, however, that the micron sized crystallites lead to peak broadening. S3 nature chemistry 3

4 Section S3: Gas Adsorption and Surface Area Data Gas adsorption analyses were performed on a Micromeritics ASAP 2020 with micropore option. N 2 analyses were performed at 77K using a liquid N 2 bath, and ammonia analyses were performed at 298K using a cryostatic water bath. N 2 and ammonia gases were both % purity. Table S1. Summary of surface areas and ammonia loadings for COF-10 sample employed for ammonia adsorption/desorption cycling studies. Material Surface Area BET (m 2 /g) Ammonia Loading (mol/kg) COF COF-10 post NH 3 run COF-10 post NH 3 run COF-10 post NH 3 run Adsorption isotherms of COF-102, COF-6 Ammonia adsorption isotherms were obtained for three members of the COF family. They were selected based on their representative structural properties, COF-6, 2D microporous, COF-10 2D mesoporous, and COF-102, 3D microporous. Both COF-10 and COF-102 display exceptionally high ammonia uptake capacity (Figure S2). However, S4 nature chemistry 4

5 as shown in Figure S3 the recyclability of COF-102 is poor compared to COF-10. Thus COF-10 was selected for further study Figure S1. Ammonia adsorption isotherms of COF-10 (black), COF-102 (red) and COF- 6 (blue). nature chemistry 5

6 Figure S2. Ammonia adsorption isotherms for COF 102. Cycle 1 (red) and cycle 2 (green) Section S4: Pore Size Distribution Calculations. Pore size distributions were calculated using non-local density functional theory NLDFT, and a cylindrical pore oxide surface model was used to approximate the COF-10 structure in the absence of a complete COF NLDFT model. This model was chosen because it gave the best fit to the experimental isotherm relative to other commercially available DFT models, such as a carbon slit pore models. Furthermore, this model has also been shown to accurately produce pore size distributions of mesoporous materials such as MCM-41 and can capture the distribution of pores from 3.8 to 38.7 Å. 1 Given the wide range of pore sizes that can be examined with this model it provides a strong means of investigating the evolution of meso and microporosity in the materials over the ammonia adsorption cycles. nature chemistry 6 S6

7 Figure S3: Pore size distributions. Section S5: Solid state 13 C CP/MAS nuclear magnetic resonance spectroscopy. High Resolution solid-state nuclear magnetic resonance (NMR) spectra were recorded at ambient pressure on a Bruker DSX-300 spectrometer using a standard Bruker magic angle-spinning (MAS) probe with 4 mm (outside diameter) zirconia rotors. The magic angle was adjusted by maximizing the number and amplitudes of the signals of the rotational echoes observed in the 79 Br MAS FID signal from KBr. Cross-polarization with MAS (CP/MAS) was used to acquire 13 C data at MHz. The 1 H and 13 C ninetydegree pulse widths were both 4 ms. The CP contact time varied from 1.5 to 5 ms. High power two-pulse phase modulation (TPPM) 1 H decoupling was applied during data acquisition. The decoupling frequency corresponded to 72 khz. The MAS samplespinning rate was 10 khz. Recycle delays between scans varied between 3 and 10 s, S7 nature chemistry 7

8 depending upon the compound as determined by observing no apparent loss in the 13 C signal from one scan to the next. The 13 C chemical shifts are given relative to tetramethylsilane as zero ppm, calibrated using the methylene carbon signal of adamantane assigned to ppm as secondary reference. Figure S4 Conservation of COF-10 bond-connectivity within the framework after ammonia uptake and release. 13 C CP/MAS NMR spectra of COF-10 without exposure to ammonia (top), and subsequent to 3 ammonia adsorption/desorption cycles (bottom). nature chemistry 8

9 References 1 S9 nature chemistry 9