Supporting Information. Room Temperature Synthesis of Covalent Organic Framework Films by Vapor Assisted Conversion

Transcription

1 Supporting Information Room Temperature Synthesis of Covalent Organic Framework Films by Vapor Assisted Conversion Dana D. Medina, Julian M. Rotter, Yinghong Hu, Mirjam Dogru, Veronika Werner, Florian Auras, John T. Markiewicz, Paul Knochel*, Thomas Bein* Department of Chemistry and Center for NanoScience (CeNS), University of Munich (LMU), Butenandtstrasse 5-13 (E), München, Germany Section 1. Materials and methods Section 2. TEM of BDT-COF films Section 3. BDT-COF films with different thickness and on different surfaces Section 4. COF-5 film structure analysis Section 5. Gas chromatography of vapor compositions Section 6. Pyrene-COF via room temperature vapor assisted conversion 1

2 Section 1. Materials and Methods Materials: General. All materials (if not noted otherwise) were purchased from Aldrich, Fluka or Acros in the common purities purum and puriss. 2,3,6,7,10,11-Hexahydroxytriphenylene (HHTP) was purchased from TCI Europe. All materials were used as received without further purification, and were handled in air. The benzodithiophene diboronic acid BDTBA was synthesized according to a reported procedure. 1 Room temperature vapor assisted conversion synthesis of COF films: Clean substrates were prepared by cutting commercial glass microscope slides, fluorine-doped tin oxide (TEC7, Pilkington), glass-coated gold substrates 1 and silicon substrates into pieces of 20 mm 15 mm in size, and washing with soap and water. Afterwards, the glass substrates were rinsed twice with acetone and dried under a nitrogen stream. Benzene diboronic acid, BDBA (4.14 mg, mmol) or BDTBA (6.18 mg, mmol) and HHTP (5.55 mg, mmol) were dissolved in 1.0 ml and 1.5 ml, respectively, of a 1:1 (v/v) solution of dry acetone and absolute EtOH. After 5 min treatment in an ultrasonic bath at maximum power, the solution was passed through a syringe filter (0.45 µm) to remove potential undissolved material. 200 µl of the BDBA / HHTP solution or 150 µl of the BDTBA / HHTP solution were drop-cast on a clean glass substrate. Subsequently the substrate was placed into a desiccator having an approximate volume of 2 L that contained a glass vessel filled with 20 ml of a 1:1 (v/v) mixture of mesitylene and 1,4- dioxane. The desiccator was closed and after 1 3 days at room temperature (~23 C, 30% humidity) a film was obtained on the glass substrate. With this approach up to five films were prepared in each room temperature vapor assisted conversion synthesis. Room temperature vapor assisted conversion synthesis of BDT-COF films with different thickness: BDT-COF films were prepared according to the procedure described above with certain modifications. A porous film with 2 µm thickness was obtained by drop-casting 60 µl of the solution with the same initial concentration as described above on a glass substrate. To obtain a dense film of 300 nm thickness, the precursor solution was diluted to 1/3 of the initial concentration, and 60 µl of this solution was drop-cast on a glass substrate. Following the same general procedure, the substrates were placed into a desiccator having an approximate volume of 2

3 2 L that contained a vessel filled with 20 ml of a 1:1 (v/v) mixture of mesitylene and dioxane. The desiccator was closed and after 3 days at room temperature (~23 C) films were obtained on the glass substrate at the end of the process. Room temperature vapor assisted conversion synthesis of pyrene boroxine films: Film preparation was carried out according to the procedure in Section 1. Pyrene-2,7-diboronic acid (15.0 mg, mmol) was dissolved in 1.0 ml of a 1:1 mixture (v/v) of dry acetone and absolute EtOH. 150 µl of this solution was used as the drop-casting volume. Following the above general procedure, the substrates were placed into a desiccator having an approximate volume of 2 L that contained a vessel filled with 10 ml of anisole. The desiccator was closed for 24 h at room temperature (~23 C). A homogeneously covered, pale yellow film was obtained at the end of the reaction. 2 Methods: X-ray diffraction was carried out in reflection mode using a Bruker D8 Discover with Ni-filtered Cu K -radiation ( Å) and a position-sensitive detector (LynxEye). Scanning electron microscope images were recorded with a Jeol 6500F instrument at acceleration voltage of 2-5 kv. Cross section samples were prepared by cutting and breaking the substrates along the back-side and revealing a fresh cross section. The cut fragment was sandwiched between two metal screws and the holders. Prior to the SEM analysis the samples were coated with a thin layer of carbon by carbon fiber flash evaporation at high vacuum. Transmisson electron microscopy data were obtained with a FEI Titan microscope at an acceleration voltage of 80 kv. TEM samples of the COF films were prepared by gentle removal of material with a fine blade from the glass substrate. Subsequently, the film fragments were placed onto a copper grid supporting a thin, electron transparent carbon film. Kr sorption experiments were carried out with an Autosorb iq from Quantachrome Instruments at 77.3 K (liquid nitrogen temperature), assuming a saturation vapor pressure of p 0 = 217 Pa for Kr. Sample out-gassing was performed in vacuum for 12 h at room temperature. For the BET surface area calculation, a saturation vapor pressure of the supercooled liquid (321 Pa at 77.3 K) and a molecular cross-sectional area of nm 2 were assumed. Infrared (IR) spectra were recorded on a Thermo Scientific Nicolet in10 FT-IR microscope in ATR mode with a germanium crystal. IR data are reported based on wavenumbers (cm 1 ). Vapor composition analysis was performed using a HP 6890 Series gas chromatography system, a flame ionization detector and an Optima 5 capillary column (15 m 3

4 0.25 mm 0.25 µm) with N 2 as the carrier gas. 100 µl of the desiccator atmosphere were extracted with a gas-tight syringe and injected onto the 40 C warm column. Directly after injection the oven temperature was increased to 200 C within 3.5 minutes and kept at this temperature for 1.5 minutes. Retention time for dioxane = 1.2 min and for mesitylene = 2.3 min. 4

5 Section 2. TEM of BDT-COF films Figure S1. TEM micrographs of (a) polycrystalline BDT-COF material removed from a film showing the general COF morphology. (b) Higher magnification of a different area showing the typical hexagonal COF pattern viewed along different orientations. The BDT-COF film was grown in the presence of mesitylene / dioxane 1:1 (v/v) solvent mixture, exposure time of 72 h. 5

6 Section 3. BDT-COF films with different thickness and on different surfaces Figure S2. SEM micrographs of BDT-COF films prepared by room temperature vapor-assisted conversion on a glass substrate. (a) Cross-section of a film with 7 µm thickness represents the porous character of the entire film. (b) BDT-COF film of 2 µm thickness, top view (left), cross section (middle), X-ray diffraction pattern of the obtained film (right). (c) Thin BDT-COF film of 300 nm thickness, top view (left), cross-section (middle), X-ray diffraction pattern (right; detector scan geometry). The BDT-COF films were grown in the presence of mesitylene / dioxane 1:1 (v/v) solvent mixture, exposure time of 72 h. 6

7 Figure S3: SEM micrographs of BDT-COF films prepared by room temperature vapor-assisted conversion on a variety of substrates. (a) BDT-COF film grown on gold substrate, cross section (left) and top view, (middle), X-ray diffraction pattern of the obtained film (right). (b) BDT-COF film grown on FTO substrate, cross section (left) and top view, (middle), X-ray diffraction pattern of the obtained film (right). (c) BDT-COF film grown on silicon substrate, cross section (left) and top view, (middle), X-ray diffraction pattern of the obtained film (right). The BDT- COF films were grown in the presence of mesitylene / dioxane 1:1 (v/v) solvent mixture, exposure time of 24 h. 7

8 Section 4. COF-5 film structure analysis Figure S4. SEM micrograph of a cross section of a COF-5 film grown on a glass substrate by room temperature vapor-assisted conversion (different magnifications). The COF-5 films were grown in the presence of mesitylene / dioxane 1:1 (v/v) solvent mixture, exposure time of 72 h. Figure S5. X-ray diffraction pattern (detector scan geometry) of COF-5 films grown on a glass substrate, in the presence of a vapor source (red) and without the precence of a vapor source (black). The COF-5 films were grown with or without the presence of mesitylene / dioxane 1:1 (v/v) solvent mixture, for 72 h. 8

9 Figure S6. (Left) X-ray diffraction patterns of COF-5 films grown on a glass substrate in the presence of different vapor compositions. (Right) X-ray diffraction pattern of COF-5 films grown on a glass substrate (black) by exposing the COF-5 precursor solution to a vapor of mesitylene and dioxane solvent mixture 1:1 (v/v), the same film removed from the substrate and measured as powder (red). 9

10 Figure S7. FT-IR spectra of COF-5 monomer reagents blended as film, compared with grown COF-5 film after 8 h of vapor exposure, indicating the progress of the condensation reactions, mainly expressed by the characteristic stretching modes typical for boroxoles, B-O cm -1 and C-O cm The COF-5 film was grown in the presence of mesitylene / dioxane 1:1 (v/v) solvent mixture. The reagent blend film was prepared by drop casting and fast drying of the reagents solution on a glass substrate. 10

11 Figure S8. COF-5 growth monitored in the presence of a mesitylene / dioxane 1:1 (v/v) solvent vapor atmosphere. (a) X-ray diffractograms of COF-5 taken after different vapor exposure times. (b) SEM cross section of a drop-cast film on glass consisting of a blend of COF-5 reagents dried outside of the reactor. We note that at time = 0 when no condensation is observed, the reflections appearing in the pattern can be attributed to crystalline building units. (c) COF-5 film after the first stages of formation, following vapor exposure of 1 h. (d) COF-5 film after 8 h of vapor exposure. 11

12 Section 5. Gas chromatography of vapor compositions Figure S9. Vapor analysis of different solvent compositions in the reactor by gas chromatography. 12

13 Figure 10. X-ray diffraction patterns of COF-5 films grown under pure solvent atmospheres. 13

14 Section 6. Pyrene-COF via room temperature vapor assisted conversion Figure 11. Synthesis of pyrene-cof films by room temperature vapor assisted conversion on a glass substrate. (a) Reaction scheme of the self-condensation of pyrene di-boronic acid building blocks. (b) X-ray diffraction pattern of the obtained films, which is in line with the reported diffraction pattern. 2 (c), (d) SEM micrographs of the pyrene-cof films in cross-section and topview. The boroxine-based pyrene-cof films were grown in the presence of anisole, exposure time of 24 h. REFERENCES 1) Medina, D. D.; Werner, V.; Auras, F.; Tautz, R.; Dogru, M.; Schuster, J.; Linke, S.; Doeblinger, M.; Feldmann, J.; Knochel, P.; Bein, T. Acs Nano 2014, 8, ) Wan, S.; Guo, J.; Kim, J.; Ihee, H.; Jiang, D. Angew. Chem., Int. Ed. 2009, 48, ) Côté, A. P.; Benin, A. I.; Ockwig, N. W.; O'Keeffe, M.; Matzger, A. J.; Yaghi, O. M. Science 2005, 310,