Supporting Information For the manuscript Catalyst-free Preparation of Melamine-based Microporous Polymer Networks through Schiff Base Chemistry by Matthias Georg Schwab, + Birgit Faßbender, + Hans Wolfgang Spiess, + Arne Thomas, #,* Xinliang Feng +,* and Klaus Müllen +,* + Max Planck Institute for Polymer Research Ackermannweg 1, D-55128 Mainz, Germany feng@mpip-mainz.mpg.de muellen@mpip-mainz.mpg.de # Max Planck Institute of Colloids and Interfaces Research Campus Golm, D-14424 Potsdam, Germany arne.thomas@mpikg.mpg.de S1
Materials and methods Melamine, terephthalaldeyde and isophthalaldehyde were received from Sigma-Adrich. 4,4'- biphenyldicarboxaldehyde was received from Acros Organics. Anhydrous dimethyl sulfoxide was purchased from Riedel-de Haën Chemicals. All chemicals were used without further purification. Tris(4-formylphenyl)benzene was synthesized in 76 % yield according to a literature procedure 1. Elemental composition was determined with a Foss Heraeus Vario EL instrument. Fourier transform infrared (FTIR) spectra were collected with a Nicolet 73 spectrometer, equipped with an attenuated total reflection (ATR) setup. The 13 C {1H} cross-polarization magic angle spinning (CP-MAS) NMR spectrum was obtained on a Bruker ASX 5 MHz at 125.8 MHz and a MAS frequency of 25 khz. The 15 N { 1 H} CP-MAS spectrum was obtained on a Bruker DSX 3 MHz at 21.7 MHz employing a MAS frequency of 1 khz. The 13 C and 15 N cross-polarization were performed using a contact time of 3 ms and 7 ms, respectively, and a high-power 1 H decoupling two-pulse, phasemodulation (TPPM) 2 of 1 khz. Both the 13 C and 15 N NMR spectra were referenced with respect to tetramethyl silane 3 using adamantane ( 13 C, 29.456 ppm) 4 and nitromethane ( 15 N, - 358.4 ppm) 5 as secondary standards. All spectra were acquired at room temperature. TGA measurements were performed on a Mettler TGA/SDTA 851e thermobalance at a heating rate of 1 K/min under nitrogen. SEM measurements were performed on a LEO 153 field emission scanning electron microscope. Nitrogen sorption experiments and micropore analysis were conducted at -195.8 C using an Autosorb-1 from Quantachrome Instruments. Before sorption measurements, the samples were degassed in vacuum overnight at 15 C. NLDFT pore-size distributions were determined using the carbon/slit-cylindrical pore model of the Quadrawin software. Pore volumes at p/p =.1 and p/p =.8 were converted into the corresponding liquid volumes using a nitrogen density of 1.25 1-3 g/cm 3 (gaseous) and 8.1 1-1 g/cm 3 (liquid). S2
Experimental section General considerations To ensure consistency between syntheses and to exclude concentration effects, the SNW networks were synthesized at fixed overall molar concentration of.4 M, a constant reaction temperature of 18 C as well as a molar ratio of amine to aldehyde groups of 1:1. Synthesis of SNW-1 A flame dried Schlenk flask fitted with a condenser and a magnetic stirring bar was charged with melamine (313 mg, 2.485 mmol), terephthalaldehyde (5 mg, 3.728 mmol) and dimethyl sulfoxide (15.5 ml). After degassing by argon bubbling the mixture was heated to 18 C for 72 h under an inert atomosphere. After cooling to room temperature the precipitated SNW network was isolated by filtration over a Büchner funnel and washed with excess acetone, tetrahydrofurane and dichloromethane. The solvent was removed under vacuum at room temperature to afford the materials as off-white powders in 61 % yield. Elemental analysis: for C36H32N24, calculated: C, 53.99; H, 4.3; N, 41.98 %. Found: C, 39.5 ; H, 4.55; N, 39.39; S, 1.52 %. Synthesis of SNW-2 In a fashion similar to the preparation of SNW-1 melamine (2 mg, 1.586 mmol) and 4,4'- biphenyldicarboxaldehyde (5 mg, 2.378 mmol) were reacted in dimethyl sulfoxide (9.9 ml) at 18 C for 72 h to afford SNW-2 in 62 % yield. Elemental analysis: for C48H36N12, calculated: C, 63.15; H, 4.12; N, 32.73 %. Found: C, 4.31; H, 4.57; N, 35.94; S, 3.44 %. Synthesis of SNW-3 In a fashion similar to the preparation of SNW-1 melamine (313 mg, 2.485 mmol) and isophthalaldehyde (5 mg, 3.728 mmol) were reacted in dimethyl sulfoxide (15.5 ml) at 18 C for 72 h to afford SNW-3 in 62 % yield. Elemental analysis: for C3H26N12, calculated: C, 53.99; H, 4.3; N, 41.98 %. Found: C, 41.31; H, 4.77; N, 4.42; S, 3.85 %. Synthesis of SNW-4 In a fashion similar to the preparation of SNW-1 melamine (125 mg,.981 mmol) and tris(4- formylphenyl)benzene (383 mg,.981 mmol) were reacted in dimethyl sulfoxide (4.9 ml) at 18 C for 72 h to afford SNW-3 in 66 % yield. Elemental analysis: for C3H23N6, calculated: C, 67.11; H, 4.44; N, 28.46 %. Found: C, 46.57; H, 4.41; N, 41.73; S,.6 %. S3
Pyrolysis of SNW-1 A sample of SNW-1 (6 mg) was placed in a quartz boat and heated to 45 C during 1 h under an argon flow. The sample was held at this temperature for 6 h. After cooling, the sample (29 mg) was recovered as a black powder. Elemental analysis: C, 46,96 ; H, 1,26; N, 38,28; S,,1 %. S4
Fourier transform infrared (FTIR) spectroscopy % transmission / a.u. 287 344 169 155 SNW-1 SNW-2 SNW-3 SNW-4 148 4 35 3 25 2 15 5 wavenumber / cm -1 Figure S1. Fourier transform infrared (FTIR) spectra of SNW-1 (blue), SNW-2 (red), SNW-3 (green) and SNW-4 (purple). 1 99 98 97 96 95 94 % Extinktion transmission 93 92 91 9 89 88 87 86 85 84 83 35 3 25 Wellenzahlen (cm-1) wavenumber / cm -1 2 15 Figure S2. Fourier transform infrared (FTIR) spectra of SNW-1. S5
1 98 96 94 92 9 88 % transmission Extinktion 86 84 82 8 78 76 74 72 7 35 3 25 Wellenzahlen wavenumber /(cm-1) 2 15 Figure S3. Fourier transform infrared (FTIR) spectra of SNW-2. 1 95 9 85 8 % transmission Extinktion 75 7 65 6 55 35 3 25 2 Wellenzahlen wavenumber /(cm-1) 15 Figure S4. Fourier transform infrared (FTIR) spectra of SNW-3. S6
1 98 96 94 92 9 88 86 % transmission Extinktion 84 82 8 78 76 74 72 7 68 66 64 35 3 25 2 wavenumber Wellenzahlen / cm(cm-1) 15 Figure S5. Fourier transform infrared (FTIR) spectra of SNW-4. 98 96 94 92 9 88 86 %T 84 82 8 78 76 74 72 7 68 35 3 25 Wellenzahlen (cm-1) 2 15 Figure S6. Fourier transform infrared (FTIR) spectra of SNW-1 after pyrolysis at 45 C. S7
Solid-state NMR spectroscopy Figure S7. Cross-polarization (CP) 13 C MAS natural abundance NMR spectrum of SNW-1. S8
Figure S8. Cross-polarization (CP) 15 N MAS natural abundance NMR spectrum of SNW-1. S9
Thermogravimetric analysis (TGA) 1 9 8 7 weight / % 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 temperature / C Figure S9. Thermogravimetric analysis of SNW-1 (blue), SNW-2 (red), SNW-3 (green) and SNW-4 (purple). S1
Scanning electron microscopy (SEM) Figure S1. Scanning electron micrograph of SNW-1. Figure S11. Scanning electron micrograph of SNW-2. S11
Figure S12. Scanning electron micrograph of SNW-3. Figure S13. Scanning electron micrograph of SNW-4. S12
Nitrogen sorption analysis Composition S BET [m 2 /g] PV [cm 3 /g] MPV 1 [cm 3 /g] MPV 2 [cm 3 /g] SNW-1 1+2 1377 1.1.56.41 SNW-1 (45 C) 1+2 382.38.15.9 SNW-2 1+3 842.62.36.28 SNW-3 1+4 1133.84.48.35 SNW-4 1+5 1213.69.48.41 Table S1. BET surface area (S BET ), pore volume (PV, calculated at p/p =.8), micropore volume (MPV 1, calculated at p/p =.1), NLDFT micropore volume (MPV 2 ) of the SNW materials. 25 adsorbed volume / cm -3 g -1, STP 2 15 5,,1,2,3,4,5,6,7,8,9 1, Figure S14. Nitrogen sorption (filled symbols) and desorption (empty symbols) isotherms of SNW-1. p/p S13
14 12 adsorbed volume / cm 3 g -1, STP 8 6 4 2,,1,2,3,4,5,6,7,8,9 1, Figure S15. Nitrogen sorption (filled symbols) and desorption (empty symbols) isotherms of SNW-2. p/p 3 adsorbed volume / cm 3 g -1, STP 25 2 15 5,,1,2,3,4,5,6,7,8,9 1, p/p Figure S16. Nitrogen sorption (filled symbols) and desorption (empty symbols) isotherms of SNW-3. S14
16 14 adsorbed volume / cm 3 g -1, STP 12 8 6 4 2,,1,2,3,4,5,6,7,8,9 1, Figure S17. Nitrogen sorption (filled symbols) and desorption (empty symbols) isotherms of SNW-4. p/p 2 18 adsorbed volume cm 3 /g, STP 16 14 12 8 6 4 2,,1,2,3,4,5,6,7,8,9 1, Figure S18. Nitrogen sorption (filled symbols) and desorption (empty symbols) isotherms of SNW-1 after pyrolysis at 45 C. p/p S15
5 45 adsorbed volume cm 3 /g, STP 4 35 3 25 2 15 1 5-5 -4,5-4 -3,5-3 -2,5-2 -1,5-1 log(p/p ) Figure S19. Semi-logarithmic plot of the nitrogen sorption isotherms in the low pressure region of SNW-1 (blue), SNW-2 (red), SNW-3 (green), SNW-4 (purple) and SNW-1 after pyrolysis at 45 C (black).,1,9,8,7 dv(w) / cm 3 g -1 Å -1,6,5,4,3,2,1 1 2 3 4 5 6 7 8 9 1 pore with / Å Figure S2. NLDFT pore size distribution of SNW-1 (blue), SNW-2 (red), SNW-3 (green), SNW-4 (purple) and SNW-1 after pyrolysis at 45 C (black). Data calculated using the carbon slit pore model. S16
,18,16,14 dv(w) / cm 3 g -1 Å -1,12,1,8,6,4,2 2 4 6 8 1 12 14 16 18 2 pore width / Å Figure S21. Horvarth-Kawazoe pore size distribution of SNW-1 (blue), SNW-2 (red), SNW- 3 (green) and SNW-4 (purple) and SNW-1 after pyrolysis at 45 C (black). References (1) Kotha, S.; Shah, V. R. Synthesis 28, 23, 3653-3658. (2) Benett, A. E.; Rienstra, C. M.; Auger, M.; Lakshmi, K. V.; Griffin, R. G. J. Chem. Phys. 1995, 13, 6951-6958. (3) Muntean, J. V.; Stock, L. M.; Botto, R. E. J. Magn. Reson. 1988, 76, 54-542. (4) Morkombe, C. R.; Zilm, K. J. Magn. Reson. 23, 162, 479-486. (5) Goward, G. R.; Schnell, I.; Brown, S.P.; Spiess, H. W.; Kim, H.-D.; Ishida, H. Magn. Reson. Chem. 21, 39, S5-S17. S17