Supporting Information for. Nitrides and NMR-based Evidence of Hydrogenbonding. Assisted Two-dimensional Assembly

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1 Supporting Information for Synthesis of 13 C, 15 N-labeled Graphitic Carbon Nitrides and NMR-based Evidence of Hydrogenbonding Assisted Two-dimensional Assembly Yichen Hu a, Yeonjun Shim b, Junghoon Oh b, Sunghee Park b, Sungjin Park b*, and Yoshitaka Ishii a,c* a Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, United States b WCSL (World Class Smart Lab) Green Energy Battery Lab., Department of Chemistry and Chemical Engineering, Inha University, Incheon, 22212, Republic of Korea c School of Life Science and Technology, Tokyo Institute of Technology, Nagatsuta 4259, Midori-ku, Yokohama , Japan These authors equally contributed. * To whom the correspondence should be addressed. ishii@bio.titech.ac.jp; sungjinpark@inha.ac.kr Phone: ;

2 Supplementary Data: 15 N- 1 H REDOR 1 Experiment for Identifying Protonation States of 15 N Species Supplementary Figure N 1 H constant-time REDOR for assignment of NH and NH 2 groups. (a) Constant time REDOR pulse sequence. (b) Dephasing curves of three 15 N species. (c) SIMPSON simulations of the corresponding dephasing curves for an 15 N 1 H group with three varied bond distances in comparison with experimental data for 137 ppm species. In the 15 N CPMAS spectrum in Fig. 2d, we noticed that the 15 N i peak at 157 ppm was suppressed. Thus, we further identified protonation states of all the 15 N species by 15 N 1 H dipolar dephasing experiments using a 15 N- 1 H REDOR scheme. In this experiment, within one rotor period, two π-pulses were placed symmetrically relative to the center of a rotor period (see Supplementary Fig. 1a) and the duration between the two π-pulses was changed from 0 to µs, where each pulse is equally spaced from the center of the rotor period by τ/2, where τ denotes a period of (14.73N/9) µs for an integer number N (0 N 9). The 1 H π-pulse widths were 8.0 µs while the 15 N π-pulse width was 12 µs. A total of 128 scans were accumulated for each experiment using recycle delay was 5 s. The carrier frequencies for the 15 N and 1 H channels were settled at 50 and 3.5 ppm, respectively. The spectra were processed without line broadening. The REDOR signal intensities of S and S 0 were recorded with and without the proton dephasing π pulses, respectively. As the 1 H π-pulse separation τ was increased in the range defined above, 2

3 the 1H-15N dipolar dephasing should be increased. A plot of S/S0 versus this τ period (Supplementary Fig. 1b) clearly shows that the 15N species observed at 200 ppm did not show significant dephasing. The result is consistent with the notion that Nc is not protonated. On the other hand, notable dephasing was observed for the species at 137 ppm. Our simulations by the SIMPSON software well reproduced this dephasing curve for an N H two-spin system with bond length of 1.12 Å (Supplementary Fig. 1c). The result is consistent with our assignment of the 15Nt H species at 137 ppm. Interestingly, the 15N species observed at 110 ppm was completely dephased even for the shortest separation (i.e. τ = 0 µs). Our simulation using the SIMPSON software2 for a NH2 group with the geometry extracted from the stabilized model in ab initio calculations suggested the same behavior at the short separation periods (data not shown). Hence, the data overall supported our spectral assignments. Supplementary Figure 2. NH, NH2 and Nc contacts by NHHN SSNMR and schematic illustration. (a) 2D NHHN SSNMR experiments with 0.2 ms NàH CP contact time, 0.5 ms 1H 1H mixing time and HàN contact times of 0.2 ms (black)/ 2 ms (red). (b) Hydrogen bonding network of the two interacting triangular melem oligomers with long-range 1H 15N inter-unit contacts. Additional 2D NHHN Experimental Data In order to find direct evidence on the formation of hydrogen bonding from amide or amine 1H to Nc, we performed an additional NHHN experiment using the same 1H 1H mixing time of 0.5 ms but elongated the third CP contact time for polarization transfer from 1H to 15N from 0.2 ms (Supplementary Fig. 2a, black) to 2 ms (red). In the spectrum with longer H N CP time, additional cross peaks indicated contacts of Nc with protons of NH and NH2 groups. These contacts could originate from either inter- or intraoligomer contacts. Although the results do not exclusively offer evidence of inter-oligomer contacts (red arrows in Supplementary Fig. 2b), the results are still largely consistent with the formation of hydrogen bonding network. 3

4 Chemical Analysis of Isotope-Labeled and Natural Abundant G-C 3 N 4 Samples The deconvoluted XPS N1s spectrum of the natural abundant sample showed characteristic peaks of g- C 3 N 4 at 398.8, and ev, corresponding to C=N C groups, tertiary N atoms, and amino functions, respectively 3-7 (Supplementary Fig. 3a). The XPS C1s spectrum was also in a typical pattern, showing a major peak at ev corresponding to the N=C N moieties in the triazine building units 3-9 (Supplementary Fig. 3b). Peaks for heptazine-derived repeating units in a C 3 N 4 network were observed at 1641, 1568, 1424, and 1320 cm -1 5, in an FT-IR spectrum of the g-c 3 N (Supplementary Fig. 3c). Fully condensed C N moieties and partially condensed C NH moieties were observed at 1320 and 1247 cm 1, respectively. XRD measurements of the g-c 3 N 4 show a broad peak around 27-28, which belong to an inter-planar distance between C 3 N 4 layers 3, 5-7, 16-17, (Supplementary Fig. 3d). A very small and broad peak was found around 13, corresponding to an in-planar structural packing motif of tri-s-triazine. The observation of these two peaks in XRD measurements is common for g-c 3 N 4 samples. All XPS spectra of 13 C, 15 N-lableld g-c 3 N 4 sample were identical with those of natural abundant g-c 3 N 4 sample as shown in Supplementary Fig. 3a,b. Overall shape of the FT-IR spectrum of the latter was similar to that of the former, however, peak positions were slight shifted to lower wavenumber. Since 13 C and 15 N isotopes are heavier than 12 C and 14 N and FT-IR measurements detect vibrations of bonds between the atoms, the variation of atomic mass can shift the FT-IR peak positions However, peak assignments for the labeled sample were identical to the natural abundant sample. An Raman spectrum of g-c 3 N 4 showed three broad peaks at 1250 and 1583 cm -1, corresponding to D and G peaks respectively (Supplementary Fig. 4) The D and G peaks are related with structural disorder and in-plane stretching of sp 2 C-N network, respectively. A C/N ratio of g-c 3 N 4, which was measured by EDX spectroscopy (Supplementary Fig. 5), is 0.63, which is close to that (0.67) of ideal g-c 3 N 4. All these characterizations clearly confirmed that g-c 3 N 4 was successfully produced by our procedure. 4

5 Supplementary Figure 3. Chemical analysis spectra. (a) Deconvoluted N1s XPS, (b) Deconvoluted C1s XPS and (c) FT-IR spectra of g-c3n4 and 13C, 15N-labelled g-c3n4 samples. (d) An XRD pattern of g-c3n4 sample. 5

6 1250 cm -1 g-c 3 N cm -1 Intens ity Raman shift (cm -1 ) Supplementary Figure 4. A Raman spectrum of g-c 3 N 4 sample. Supplementary Figure 5. An EDX data of g-c 3 N 4 sample. Ab Initio Fully Optimized Structure After geometry optimization by ab initio method, the structural model of the interacting oligomers as displayed in Fig. 5 shows planar surface and parallel alignment along the interacting edges in the perspective of the top of the model s plane (Supplementary Fig. 6a). The modulated 2D plane with corrugation characteristic was more evidently seen from the side views (Supplementary Fig. 6b,c), which should give rise to the long-range corrugation of the polymer. The result is consistent with the observation in an STEM micrograph (Fig. 1a). 6

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