Light-Harvesting Metal-Organic Frameworks (MOFs): Efficient Strut-to-Strut Energy Transfer in Bodipy and Porphyrin-based MOFs.

Transcription

1 S1 Supplementary Information to accompany Light-Harvesting Metal-Organic Frameworks (MOFs): Efficient Strut-to-Strut Energy Transfer in Bodipy and Porphyrin-based MOFs. Chang Yeon Lee, Omar K. Farha,* Bong Jin Hong, Amy A. Sarjeant, SonBinh T. Nguyen,* and Joseph T. Hupp* Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States Table of Content S1. Materials and synthesis S1 S2. Powder X-ray diffraction of BOB, BOP and pyridine-treated BOP MOFs. S2 S3. TGA data for BOB and BOP MOFs. S3 S4. CO 2 isotherms for BOB and BOP MOFs S3 S5. Confocal laser scanning microscope (CLSM) of BOB and BOP MOFs S4 S6. UV-Vis absorption, emission and excitation spectroscopy S4 S7. Elimination of L3 from the BOP MOF. S5 S8. X-ray crystallographic data for BOB and BOP MOFs. S7 References S8 S1. Materials and synthesis Material. 3,6-Dibromo-1,2,4,5-tetrakis(4-carboxyphenyl)benzene (L1), S1 Zn-L2, S2 6-diiodo-1,3,5,7-tetramethyl-8-phenyl- 4,4-difluoroboradiazaindacene S3 were synthesized according to published procedures. Dichlorobis(triphenylphosphine) palladium was purchased from Strem Chemicals and used as received. Toluene, pyridine, N,N -dimethylformamide, and ethanol were purchased from Aldrich Chemicals and used as received. 4-Trimethylstannylpyridine was purchased from TCI America Fine Chemicals and used as received. All deuterated solvents were purchased from either Cambridge Isotope Laboratories or Sigma-Aldrich and used as received. Deionized water was provided as a part of the building facility at Northwestern University. NMR spectra were recorded on a Varian INOVA 500 FT-NMR instrument (499.6 MHz for 1 H, MHz for 13 C). 1 H chemical shifts are referenced to the residual proton resonances of solvents. Synthesis of L3 (Eq S1). 2,6-Diiodo-1,3,5,7-tetramethyl-8-phenyl-4,4-difluoroboradiazaindacene (0.35 g, 0.61 mmol), 4- (trimethylstannyl)pyridine (0.34 g, 1.39 mmol), and toluene (20 ml) were combined in a 100 ml two-neck round-bottom flask equipped with a Teflon-coated magnetic stir bar and a water-cooled reflux condenser. The resulting red-purple solution was allowed to degas with N 2 stream for 10 min before adding PdCl 2 (PPh 3 ) 2 (0.084g, 0.12 mmol). The resulting reaction mixture was refluxed for 48 h and then cooled down to room temperature before the solvent was removed by using rotary evaporator. CH 2 Cl 2 (4 ml) was added to the remaining sticky dark purple solid to dissolve the organic component. The resulting mixture was directly subjected to flash column chromatography on silica gel, using a 30-mm inner diameter column containing 150 cm 3 of silica under a positive pressure of lab air, with ethyl acetate as eluent. The collected fractions were analyzed using silica TLC; the fractions that showed a single spot with R f = 0.35 were combined and evaporated to dryness to give a red solid (130 mg, 45 %). 1 H NMR (500 MHz, CDCl 3 ): δ 8.66 (d, 4H, J = 6 Hz ArH), (m, 3H, ArH), 7.37 (d, 2H, J = 9 Hz, ArH), 7.13 (d, 4H, J = 6 Hz, ArH), 2.60 (s, 6H, CH 3 ), 1.36 (s, 6H, CH 3 ). 13 CNMR (500 MHz, CDCl 3 ): δ 154.2, 149.9, 143.3, 141.8, 140.0, 134.8, 131.6, 131.2, 129.5, 129.4, 127.7, 125.0, 13.4, Synthesis of BOB MOF. A mixture of L1 (20.5 mg, mmol), L3 (13 mg, mmol), and Zn(NO 3 ) 2 6H 2 O (16 mg, mmol) were suspended in DMF (1.2 ml) in 1 dram vial. The resulting suspension was sonicated for 5 min and an aliquot of HNO 3 in EtOH (0.5 ml of a 0.03 M solution) was added. The vial was then capped with Teflon-lined caps and placed in an 80 C oven for 12 h to give rectangular plate, orange crystals ~0.5 mm in length that were suitable for analysis with single-crystal X-ray diffraction. After cooling to room temperature, the crystals were isolated by decantation and rinsed with DMF (~20 ml). The crystals were filtered to give 45 mg of the as-synthesized materials. Yield calculated from activated sample = 25 mg (66 %) based on L1.

2 Lee et al., Supporting Information to accompany J. Am. Chem. Soc. manuscript # ja a S2 Synthesis of BOP MOF. A solid mixture of L2 (5.1 mg, mmol) and Zn(NO 3 ) 2 6H 2 O (5.8 mg, mmol) was dissolved in DMF (1 ml) in 1dram vial. The vial was sonicated for 5 min and then capped with Teflon-lined caps and placed in an 80 C oven for 2 h. While the solution was warm, solid L3 (12 mg, mmol) and an aliquot of HNO 3 in EtOH (1 ml of a 0.03M solution) were added. The vial was then recapped and the resulting suspension was heated in an oven at 80 C for 12 h. After cooling to room temperature, the solvent was decanted and replaced with fresh DMF (2 ml). The mixture was gently swirled and allowed to settle before the solution was decanted. This process was repeated until the solution was colorless. The remaining dark brown crystals were then stored in DMF until ready for use. The aforementioned synthesis was repeated three times to obtain large amount of BOP MOF. Three identical reactions were carried at the same time to obtain 22 mg of the as-synthesized material. Yield calculated from activated sample = 13 mg (50 %) based on L2. S2. Powder X-ray diffraction of BOB, BOP and pyridine-treated BOP MOFs Powder X-Ray Diffraction. Powder patterns for BOB, BOP, and pyridine-treated BOP MOFs (see section S7) were collected on a Bruker AXS APEX2 diffractometer equipped with a CCD detector and a CuKα IµS microfocus source with MX optics. Samples were loaded into glass capillaries with a small amount of mother liquor, and mounted on a goniometer head. Data were collected with an area detector as rotation frames over 180 in φ at 2θ values of 12, 24, and 36 and exposed for 10 minutes for each frame. At a distance of 150mm, the detector area covers 24 in 2θ. Overlapping sections of data were matched and the resulting pattern integrated using the Bruker APEX2 Phase ID program. Powder pattern data were treated for amorphous background scatter (using the Bruker Diffract Plus EVA software, Copyright Bruker-AXS ). Figure S1. PXRD data for BOB MOF: simulated (bottom) and as-synthesized (top).

3 Lee et al., Supporting Information to accompany J. Am. Chem. Soc. manuscript # ja a S3 Figure S2. PXRD data for BOP MOF (both simulated and as-synthesized) and as synthesized pyridine-treated BOP MOF. S3. TGA data for BOB and BOP MOFs. Thermogravimetric analysis (TGA). TGA experiments were carried out on a Mettler Toledo TGA/DSC 1 instrument that is interfaced with a PC using STARe software. Samples were heated at a rate of 10 ºC/min under a nitrogen atmosphere. Figure S3. TGA data for as-synthesized BOB and BOP MOFs. S4. CO 2 isotherms for BOB and BOP MOFs CO 2 Adsorption Isotherms. Low-pressure carbon dioxide adsorption measurements were performed using an Autosorb 1-MP instrument (Quantachrome Instruments, Boynton Beach, FL, USA). Ultra-high purity grade He, and CO 2 was used

4 Lee et al., Supporting Information to accompany J. Am. Chem. Soc. manuscript # ja a S4 for adsorption measurements. Prior to analysis, materials were activated by removing the solvent via supercritical CO2 processing. Supercritical CO2 processing was performed with a TousimisTM Samdri PVT-30 critical-point dryer Tousimis Research Corp., Rockville, MD, USA). After activation, the sample and tube were re-weighed to obtain the precise mass of the evacuated sample. Low-pressure CO2 adsorption isotherms were measured at 273K, the temperature was held constant using an ice-water bath. Surface areas were calculated by applying non-local density functional theory (NLDFT) in the range of P 1.0 atm. Figure S4. CO2 adsorption-desorption isotherms at 273 K for BOB and BOP MOFs. Closed symbols, adsorption; open symbols, desorption. S5. Confocal laser scanning microscope (CLSM) of BOB and BOP MOFs A confocal laser scanning microscope (CLSM) study was performed on a LSM 510 META microscope (Carl Zeiss MicroImaging, LLC, Thornwood, NY). CLSM images were collected with an excitation wavelength of 543 nm (He-Ne laser) using a water-immersion objective (Ec PInN 10 /0.3 DICI). Obtained images were converted to TIFF format with ZEN 2009 software (Carl Zeiss MicroImaging, LLC). S6. UV-vis absorption, emission, and excitation spectroscopy. The UV-vis absorption spectra of Zn-L2 and L3 in DMF were collected on a Varian Cary 5000 UV-vis-NIR spectrophotometer (Varian Medical Systems, Inc., Palo Alto, CA). The steady-state fluorescence spectrum and solid-state fluorescence spectra were obtained on a HORIBA Jobin Yvon Fluorolog fluorometer (HORIBA Jobin Yvon Inc., Edison, NJ, USA). Solid samples for fluorescence spectra were prepared according to published procedure.s4 The excitation spectrum was also collected with the aforementioned HORIBA Jobin Yvon Fluorolog fluorometer. Ground powder of as-synthesized sample for the excitation spectrum was sprinkled onto a glass slide and spread evenly on the glass slide by rubbing with a glove-covered index finger to minimize scattering during the excitation measurement.

5 Lee et al., Supporting Information to accompany J. Am. Chem. Soc. manuscript # ja a S5 Figure S5. The UV-vis absorption spectra of Zn-L2 and L3 in DMF and the emission spectrum of L3 (inset) in DMF. Figure S6. The emission spectra of BOB MOF, BOP MOF, and a mixture of [BOB MOF + pyridine-treated BOP MOF]. All samples were excited at 520 nm. S7. Elimination of L3 from the BOP MOF. In a 1dram vial, as-synthesized BOP MOF (10 mg) was combined with pyridine (2 ml) and the mixture was left at room temperature. Over time, the mother liquor becomes red orange, indicating the exchange of L3 in the solid with pyridine in solution. The pyridine was replaced every 2 h over 6 h when the supernatant became clear (Figure S7). After the final aliquot of pyridine was decanted, the resulting solid was filtered and washed with fresh pyridine (10 ml) and EtOH (10mL). The collected sample of pyridine-treated BOP MOF was then stored in EtOH until further analysis.

6 Lee et al., Supporting Information to accompany J. Am. Chem. Soc. manuscript # ja a S6 Figure S7. Digital images of vials containing a sample of BOP MOF in EtOH (left) and a sample of BOP MOF that was exposed to pyridine over 6 h. The mother liquor was replaced with fresh pyridine every 2 h. Figure S8. 1H-NMR spectra of L3 (TOP), BOP (middle), and pyridine-treated BOP MOF (bottom) in D2SO4 (aq). Figure S7. Digital images of three vials containing samples BOB MOF, BOP MOF, and pyridine-treated BOP MOF in EtOH.

7 Lee et al., Supporting Information to accompany J. Am. Chem. Soc. manuscript # ja a S7 S7. X-ray crystallographic data for BOB MOF and BOP MOF. Single-crystal X-ray structure determination of MOFs. Single crystals of BOB MOF and BOP MOF were mounted in oil on glass fibers and placed in the nitrogen cold stream (100 K) of a Bruker AXS APEX2 diffractometer equipped with a CCD detector and an IµS CuKα microfocus source with MX optics. All data were corrected for absorption via SADABS. Structures were solved and refined using the SHELXTL suite of software. The program SQUEEZE (Platon) was used to remove electronic contributions from solvent molecules for each structure. See supporting CIF files for further refinement details. Table S1. Summary of crystallographic data for BOB MOF and BOP MOF. BOB MOF BOP MOF empirical formula C 189 H 107 B 3 Br 6 F 6 N 12 O 24 Zn 6 C 77 H 49 BF 2 N 8 O 9 Zn 3 formula weight crystal color, habit orange, plate red, plate crystal dimensions (mm 3 ) crystal system Monoclinic Tetragonal space group P2/m P4/mmm a (Å) (13) (16) b (Å) (19) (16) c (Å) (19) (4) α (deg) β (deg) (5) 90 γ (deg) V (Å 3 ) (15) (13) Z 1 1 ρ (calcd, g/cm 3 ) µ (cm -1 ) goodness-of-fit on F R Rw References (S1) Farha, O. K.; Malliakas, C. D.; Kanatzidis, M. G.; Hupp, J. T. J. Am. Chem. Soc. 2010, 132, 950. (S2) Rochford, J.; Chu, D.; Hagfeldt, A.; Galoppini, E. J. Am. Chem. Soc. 2007, 129, (S3) Zhang, D.; Wen, Y.; Xiao, Y.; Yu, G.; Liu, Y.; Qian, X. Chem. Commun. 2008, (S4) Pramanik, S.; Zheng, C.; Zhang, X.; Emge, T. J.; Li, J. J. Am. Chem. Soc. 2011, 133, Complete Citation of Reference 13b (13b) Horcajada, P.; Chalati, T.; Serre, C.; Gillet, B.; Sebrie, C.; Baati, T.; Eubank, J. F.; Heurtaux, D.; Clayette, P.; Kreuz, C.; Chang, J.-S.; Hwang, Y. K.; Marsaud, V.; Bories, P.-N.; Cynober, L.; Gil, S.; Férey, G.; Couvreur, P.; Gref, R. Nat. Mater. 2010, 9, 172