Urea Metal Organic Frameworks as Effective and Size Selective Hydrogen Bond Catalysts

Transcription

1 J. Am. Chem. Soc. Supporting Information. Page S1 Urea tal Organic Frameworks as Effective and Size Selective ydrogen Bond Catalysts John M. Roberts,, Branden M. Fini,, Amy A. Sarjeant, Omar K. Farha,,, * Joseph T. upp,,, * and Karl A. Scheidt,,, * Department of Chemistry, International Institute for anotechnology, and Center for Molecular Innovation and Drug Discovery, orthwestern University 2145 Sheridan Rd., Evanston, IL Supporting Information General Information... S1 Scheme for the Synthesis of 1:... S2 Experimental Procedures of 1 4:... S2 Experimental Procedure for U S4 Experimental Procedures for Catalysis Reactions and Conversion Plots.... S4 Modeling of Product 7 in U S10 Characterization of U S11 PXRD of U S11 TGA of U S14 MR Comparisons between strut and U-601 in D 2 SO 4... S15 General Information All reactions were carried out under a nitrogen atmosphere in flame-dried glassware with magnetic stirring unless otherwise stated. All reagents were purchased from Aldrich unless otherwise stated and used as received unless otherwise stated. Analytical thin layer chromatography was performed on EM Reagent 0.25 mm silica gel 60-F plates. Visualization was accomplished with UV light. 1 -MR spectra were recorded on a Bruker AVACE III 500 (500 Mz) spectrometer and are reported in ppm using solvent as an internal standard (CDCl 3 at 7.26 ppm, DMSO-d 6 at 2.50 ppm, and D 2 SO 4 at 10.5 ppm). Data are reported as (ap = apparent, s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet, b = broad; coupling constant(s) in z; integration. Proton-decoupled 13 C-MR spectra were recorded on a Bruker AVACE III 500 (125 Mz) spectrometer and are reported in ppm using solvent as an internal standard (CDCl 3 at ppm and DMSO-d 6 at ppm). Mass spectra data was obtained on an Agilent 1100 Series LC/MSD. FTIR spectra data was obtained on a Bruker Tensor 37 FTIR using an ATR attachment.

2 J. Am. Chem. Soc. Supporting Information. Page S2 Scheme for the Synthesis of 1: Scheme S1: Synthesis of MOF strut 1. CO 2 CO t 2 Bu CO t 2 Bu O t Bu, DCC, DMAP Pd/C, 2 O 2 C O t 2 60% BuO 2 C O 2 95% t BuO 2 C CDI 97% CO 2 CO 2 O TFA O O 2 C 1 CO 2 90% t BuO 2 C 4 Experimental Procedures of 1 4: t BuO 2 C O 2 di-tert-butyl 5-nitroisophthalate (2): This compound was prepared using a modified literature procedure. 1 5-nitroisophthalic acid (6.33g, 30.0 mmol) was dissolved in a 1:1 mixture of DMF:DCM (160 ml) in a 500 ml round bottom flask. To the stirred mixture was added tertbutyl alcohol (8.6 ml, 90.0 mmol) and DMAP (1.266g, 20% w/w based on 5-nitroisophthalic acid), and the solution was cooled to 0 C. Then, DCC (13.61g, 66.0 mmol) was added to the flask and the mixture was allowed to warm to room temperature and stir overnight at 23 C. After stirring overnight, the precipitate was filtered off and the filtrate was washed with 1 M Cl (2 x 100 ml) and brine (2 x 100 ml). The combined organics were then dried with sodium sulfate, concentrated under reduced pressure, and the resulting solid was recrystallized from methanol to give white needles. These needles were dried under high vacuum, yielding 2 (6.2g, 64%). Analytical data for 2: IR (ATR) 3338, 3098, 2978, 1725, 1539, 1322, 1144, 842, 726 cm - 1 ; 1 MR (500 Mz, CDCl 3 ) δ 8.92 (s, 2), 8.86 (s, 1), 1.63 (s, 18); 13 C (125 Mz, CDCl 3 ) δ 163, 148.4, 135.8, 134.2, 127.8, 83.3, 28.2; RMS (CI): Exact mass calcd for C O 6 [M+a] +, Found: Drewe, W. C.; anjunda, R.; Gunaratnum, M.; Beltran, M.; Parkinson, G..; Reszka, A. P.; Wilson, W. D.; eidle, S. J. d. Chem. 2008, 51,

3 J. Am. Chem. Soc. Supporting Information. Page S3 t BuO 2 C 2 di-tert-butyl 5-aminoisophthalate (3): To a 250 ml round bottom flask was added O (95 ml) and 2 (6.2g, 19.7 mmol). The reaction vessel was stirred and purged with 2 gas over a period of 5 minutes. After purging for 5 minutes 10% w/w palladium on carbon (Strem, 1g, mmol) was added. The flask was purged with 2 balloons of 2 gas, fitted with 2 balloons of 2 gas, and stirred overnight at 23 C. TLC analysis (30% EtOAc/ex) after stirring overnight showed conversion of 2 to the aniline (3) (R f = 0.9 for 2 and 0.47 for 3). The suspension was filtered through celite, washed with DCM, concentrated under reduced pressure, and dried under high vacuum to yield 3 as a white solid (5.49g, 95%). Analytical data for 3: IR (ATR) 3460, 3373, 2971, 1695, 1349, 1254, 1162, 852, 758 cm -1 ; 1 MR (500 Mz, CDCl 3 ) δ 7.95 (s, 1), 7.43 (s, 2), 3.87 (s, 2), 1.58 (s, 18); 13 C (125 Mz, CDCl 3 ) δ 165.4, 133.3, 120.7, 119.4, 81.4, 28.3; RMS (CI): Exact mass calcd for C O 4 [M+] +, Found: O t BuO 2 C tetra-tert-butyl 5,5'-(carbonylbis(azanediyl))diisophthalate (4): This compound was prepared using a modified literature procedure. 1 To a 25 ml pear flask was added 3 (0.586g, 2 mmol), CDI (0.194g, 1.2 mmol), and TF (5 ml). The reaction mixture was refluxed overnight. After heating overnight, the mixture was cooled to room temperature and concentrated under reduced pressure. The resulting residue was taken up in DCM (25 ml) and washed with 1M Cl (25 ml) and brine (25 ml). The combined organics were dried with sodium sulfate, concentrated under reduced pressure, and dried under high vacuum to yield 4 as a white foam (0.595g, 97%). Analytical data for 4: IR (ATR) 3346, 2978, 1710, 1568, 1339, 1270, 1160, 850, 755 cm -1 ; 1 MR (500 Mz, CDCl 3 ) δ 8.29 (s, 2), 8.18 (s, 4), 1.58 (s, 36); 13 C (125 Mz, CDCl 3 ) δ 164.9, 152.6, 138.5, 133.2, 128.4, 125.8, 125, 82, 28.3; RMS (CI): Exact mass calcd for C O 9 2 [M+] +, Found: CO 2 CO 2 O O 2 C CO 2 5,5'-(carbonylbis(azanediyl))diisophthalic acid (1): This compound was prepared using a modified literature procedure. 1 To a 50 ml pear flask was added 4 (1.572g, 2.56 mmol) and TFA (10 ml). The mixture was stirred vigorously at 23 C, and after ~1 min a white precipitate appeared. The suspension stirred for 2 hours before being diluted with DCM and filtered through a fritted funnel. The precipitate was washed with DCM and the resulting white solid

4 J. Am. Chem. Soc. Supporting Information. Page S4 was dried under high vacuum yielding 1 (0.89g, 90%). Analytical data for 1: IR (ATR) 3094, 2574, 1698, 1569, 1439, 1274, 1217, 906, 759 cm -1 ; 1 MR (500 Mz, DMSO-d 6 ) δ 9.30 (s, 2), 8.32 (s, 4), 8.10 (s, 2); 13 C (125 Mz, DMSO-d 6 ) δ 166.6, 152.7, 140.4, 131.8, 123.1, 122.2; RMS (CI): Exact mass calcd for C O 9 2 [M+] +, Found: Experimental Procedure for U-601. A single crystal of U-601 was synthesized via the solvothermal reaction of 2.2 equiv. Zn(O 3 ) 6 2 O (1.026 mmol, 0.305g), 1.0 equiv. 1 (0.466 mmol, 0.181g), and 2.0 equiv. 4,4 - bipyridine (4-4 BIPY) in 36 ml of DMF. The reagents and solvent were added to a 125 ml Erlenmeyer flask and sonicated until the solution was homogeneous. This flask was capped with a rubber septum and placed in an oven set to 90 C. After 2 days light yellow needle crystals were visible. The solvent was replaced with fresh DMF (50 ml), which had been warmed to 90 C. The flask was then allowed to cool to room temperature. The crystals were isolated by vacuum filtration and exchanged with O 2 by suspending the crystals in a fresh O 2 solution and exchanging the solution every day for 4 days. After four days of exchanging MR spectroscopy (500 Mz, D 2 SO 4 ) was used to confirm all of the DMF had been removed (Figure S8). From Figure S9, one can see there are 3.4 O 2 molecules per strut 1, corresponding to 3.4 O 2 molecules per unit cell. If a unit cell has one molecule of 1 (minus 4 hydrogen atoms), two 4-4 BIPY molecules, 2 zinc atoms, and 3.4 O 2 molecules (mw unit cell = 384+(166*2)+(65*2)+(61*3.4) = 1053) then the unit cell is 36.46% 1 w/w (384/1053 = ). Total amount of U-601 isolated was 280 mg, so with a theoretical mass of 496 mg (0.181g of 1/0.3646), the % yield is 56.5%. IR (ATR) 3385, 1611, 1555, 1415, 1373, 1219, 782, 725, 631 cm -1. Experimental Procedures for Catalysis Reactions and Conversion Plots. A stock solution of (E)-1-nitroprop-1-ene (6) in 1:1 TF:O 2 with mesitylene as an internal standard was prepared by mixing 5ml of TF, 5ml of O 2, ml 6, and ml of mesitylene (Stock Solution A). A similar stock solution was prepared in the same manner, but instead of using 6, 1.772g of (E)-(4-nitrobut-3-en-1-yl)benzene 2 (9) was used (Stock Solution B). % conversion and % yield calculations were done using 5 μl of mesitylene/reaction as an internal standard. GC measurements were made using an Agilent Systems 6890 etwork GC with a 7683 Series Injector. P CORE Chemstation software was used on the GC, and we employed a Agilent 19091J-413 column using a method ramping from 30 C to C/min and following the ramp a 10 min 170 C. We employed a 10:1 split ratio, 22.2 ml/min 9.52 psi and used 2 μl injections. MR yields were calculated using mesitylene as an internal standard. Preparative PLC was preformed using a 1200 Agilent PLC with a 6130 MS quadrapole analyzer and a IFC-PAL Fraction Collector/Autosampler and Chemstation software (B 04.02). 2 Taylor, E. C.; Liu, B. J. Org. Chem. 2003, 68,

5 J. Am. Chem. Soc. Supporting Information. Page S5 General Procedure for Catalysis Reactions: A Stock solution (corresponding to 0.4 mmol of nitroalkene, 0.4 ml solvent, and 5 μl mesitylene) was added to a 1 dram vial containing 0.04 mmol catalyst (5 or 10 mol %). Then, 0.6 mmol of pyrrole was added. The thread of the vial was wrapped in Teflon and the top screwed on tightly. The vial was placed in a KEM-Labs Vortex mixer (in a scintillation vial holder to facilitate increased agitation) with an attached J-KEM KEM-Labs controller. The mixer was heated to 60 C and shook for 36 h or 2 days. For conversion plots, aliquots were taken at 6, 18, 24, and 48 hours (Figure S1) or every hour for 12 hours and then at 18, 24, and 36 hours (Figure 4) and run on GC using mesitylene as an internal standard. After 2 days GC or MR was used to determine the % yield, employing the mesitylene internal. All reactions were run in duplicate. Pure analytical samples were obtained by preparative PLC. O 2 1-methyl-2-(1-nitropropan-2-yl)-1-pyrrole (7): Reaction set up according to the general procedure. Stock solution A (437 μl, corresponding to 0.4 mmol of 6, 0.4 ml solvent, and 5 μl mesitylene) was added to a 1 dram vial containing 43 mg mmol (0.04 mmol of U-601, corresponding to U-601 being 36% w/w urea strut 1). Then, 53 μl (0.6 mmol) of freshly distilled -methyl pyrrole (5) was added via syringe. The thread of the vial was wrapped in Teflon and the top screwed on tightly. The vial shook at 60 C for 2 days. After 2 days GC analysis showed a 39% yield. Pure analytical sample was obtained by preparative PLC. Analytical data for 7: IR (ATR) 2971, 2933, 2884, 1467, 1379, 1309, 1161, 1129, 952, 817 cm -1 ; 1 MR (500 Mz, CDCl 3 ) δ 6.57 (s, 1), 6.08 (s, 1), 5.97 (s, 1), (dd, J = 12.2, 5.6 z, 1), (dd, J = 12.2, 9 z, 1), (dt, J = 8.9, 6.6, z, 1), 3.62 (s, 3), 1.35 (d, J = 6.9 z, 3)δ; 13 C (125 Mz, CDCl 3 ) 132, 122.6, 107.3, 103.2, 80.9, 33.7, 30.3, 18.7; RMS (CI): Exact mass calcd for C 8 12 O 2 2 [M+1] +, Found: O 2 1-methyl-2-(1-nitro-3-phenylpropan-2-yl)-1-pyrrole (10): Reaction set up according to the general procedure. Stock solution B (405 μl, corresponding to 71 mg (0.4 mmol) of 9, 0.4 ml solvent, and 5 μl mesitylene) was added to a 1 dram vial containing U-601 (42 mg, 0.04 mmol) and then 53 μl of freshly distilled 5 (0.6 mmol) was added via syringe. The thread of the vial was wrapped in Teflon and the top screwed on tightly. The vial shook at 60 C for 2 days. After 2 days, ~1% yield was observed (<5% by MR). Pure analytical sample was obtained by preparative PLC. Analytical data for 10: IR (ATR) 2968, 2930, 1551, 1454, 1378, 1266, 946, 767, 700 cm -1 ; 1 MR (500 Mz; CDCl 3 ): δ (m, 2), (m, 1), 7.08 (dd, J

6 J. Am. Chem. Soc. Supporting Information. Page S6 = 7.8, 0.9 z, 2), 6.55 (dd, J = 2.6, 1.8 z, 1), 6.12 (t, J = 3.2 z, 1), 6.03 (dd, J = 3.7, 1.7 z, 1), 4.48 (dd, J = 7.5, 2.3 z, 2), 3.56 (ddt, J = 9.8, 4.9, 2.4 z, 1), 3.48 (s, 3), 2.64 (ddd, J = 14.0, 9.1, 5.1 z, 1), 2.53 (ddd, J = 13.8, 9.3, 7.2 z, 1), (m, 2) δ; 13 C MR (126 Mz; CDCl3): δ 140.9, 130.3, 128.7, 128.4, 126.3, 122.5, 107.5, 105.9, 80.2, 34.7, 33.8, 32.8RMS (CI): Exact mass calcd for C O 2 2 [M+1] +, Found: Pure analytical samples of 11 and 12 were synthesized according to ref. 14 in the manuscript to calculate MR yields. The samples were purified by prep. PLC. Analytical data is provided below: O 2 2-(1-nitropropan-2-yl)-1-phenethyl-1-pyrrole (11): Analytical data for 11: IR (ATR) 2970, 2934, 2879, 1550, 1382, 1292, 1074, 899, 700 cm -1 ; 1 MR (500 Mz; CDCl 3 ): δ (m, 3), (m, 2), 6.64 (t, J = 1.4 z, 1), 6.14 (s, 1), 5.93 (t, J = 1.8 z, 1), 4.26 (dd, J = 12.4, 9.3 z, 1), (m, 3), (m, 1), 3.05 (t, J = 7.1 z, 2), 1.21 (d, J = 6.8 z, 3); 13 C MR (126 Mz; CDCl3): δ 138.2, 131.9, , , 127.0, 120.7, 107.9, 105.0, 80.9, 48.0, 38.6, 30.0, 19.0; RMS (CI): Exact mass calcd for C O 2 2 [M+1] +, Found: O 2 2-(1-nitro-4-phenylbutan-2-yl)-1-phenethyl-1-pyrrole (12): Analytical data for 12: IR (ATR) cm -1 ; 1 -MR (500 Mz; CDCl 3 ): δ (m, 9), (m, 2), (m, 2), (m, 2), 6.63 (dd, J = 2.8, 1.7 z, 1), 6.17 (t, J = 3.2 z, 1), 5.99 (dd, J = 3.6, 1.7 z, 1), 4.35 (dd, J = 12.6, 8.7 z, 1), (m, 3), 3.44 (dt, J = 10.0, 4.5 z, 1), 2.97 (t, J = 7.2 z, 2), 2.56 (dd, J = 9.6, 5.2 z, 1), 2.46 (ddd, J = 13.8, 9.8, 6.6 z, 1), (m, 1), (m, 1).; 13 C MR (126 Mz; CDCl3): δ 140.9, 138.2, 130.0, , , , 128.4, 126.9, 126.3, 120.9, 108.1, 105.6, 79.9, 48.0, 38.5, 35.0, 34.6, 32.8; RMS (CI): Exact mass calcd for C O 2 2 [M+1] +, Found:

7 J. Am. Chem. Soc. Supporting Information. Page S7 Reused U-601 Conversion Plots and Removal After 6 hours: Shown below are conversion plots for U-601 (5 mol%), U-601 (5 mol %, removed after 6 h), U-601 (5 mol% reused once), U-601 (5 mol % reused 5 times), and a control. For the reaction where U-601 was removed after 6 h, the reaction mixture was filtered through a 20 µm filter and the filtrate added to a new dram vial. Shown below Figure S1 is a table detailing conversion and yield data. PXRD data for U-601 that had been recycled once and 5 times is shown below in Figures S5 and S6 respectively. One potential reason for the drop in reactivity after 5 cycles is the possibility of surface defects incurred after multiple uses but not visible by PXRD. Catalyst, 1:1 TF:O 2 + O 2 60 C (1.5 equiv.) O 2 Figure S1. Conversion of 6 using various MOF catalysts. All reactions were set up according to the general procedure. Table S1. Yield and Conversion data. Catalyst % 48 h % 48 h U-601 (5 mol %) U h (5 mol %) U-601 Reused once (5 mol %) U-601 Reused 5 times (5 mol %) Control 21 7

8 J. Am. Chem. Soc. Supporting Information. Page S8 Conversion Plots of Small Vs. Large Substrates in omogeneous Reactions: Shown below are conversion plots of large vs. small substrates (both nitroalkenes and pyrroles). These plots show both small and large substrates have similar reactivity in homogeneous reaction settings. R + (1.5 equiv.) O 2 (10 mol%) Cat, O 2 23 C R 1 O 2 CF 3 CF 3 Cat = O F 3 C CF 3 Figure S2. Comparison between 5 and 8 s reactivity. Red line is consumption of the 6 when 5 is the nucleophile, and the blue line is consumption of 6 when 8 is the nucleophile. Reaction was set up using the general procedure (except the reaction was run at 23 C and nitromethane (1.0M) was used as the solvent) and monitored via GC using mesitylene as an internal standard.

9 J. Am. Chem. Soc. Supporting Information. Page S9 + R O 2 Cat (10 mol%), 1:1 TF:O 2 (1.5 equiv.) 23 C R O 2 Cat = O t BuO 2 C Figure S3. Comparison between 6 and 9 s reactivity. Red line is consumption of 6, and the blue line is consumption of 9. Reaction was set up using the general procedure (except the reaction was run at 23 C) and monitored via GC using mesitylene as an internal standard. Competition Experiment: A competition reaction was set up using 1 equiv. of 5, 1 equiv. of 6, 1 equiv. of 9, 5 mol % of U-601, and this was run in a 1:1 mixture of O 2 :TF for 48 h. % yield of 7 was 13% (GC) and no 10 was observed (MR).

10 J. Am. Chem. Soc. Supporting Information. Page S10 Modeling of Product 7 in U-601 With U-601 as the BD catalyst, when product molecule 7 is bound to a urea active site, another catalyst site proximal to the bound product molecule is obstructed. This unfavorable interaction decreases the number of possible catalyst sites ~50% of all possible sites available. In our model, made using VMD, the bond distances between the nitro group on 7 and the hydrogen atoms on the urea nitrogen atoms (atom center to atom center) is 2.25 Å, which is consistent with crystallographic data. 3 By placing two molecules of product 7 in neighboring unit cells, the distance between one product molecule and another can be estimated. Using the van der Waals radii of oxygen (1.5 Å) and hydrogen (1.2 Å), the distance between van der Waals surfaces of the molecules (the pyrrole hydrogen on the left molecule to the nitro group oxygen on the right molecule) is 1.6 Å, which would preclude two product molecules being next to each other at the same time. Shown below in Figure S4 is a graphical representation of the two product molecules hydrogen bound in U-601. Figure S4. Two molecules of product 7 bound to adjacent urea sites in U-601. The distance between the pyrrole hydrogen of the left product molecule to the front nitro group oxygen of the product on the right (VDW surface to VDW surface) is 1.6 Å. 3 Etter, M. C.; Urbanczyk-Lipkowska, Z.; Zia-Ebrahimi, M.; Panunto, T. W. J. Am. Chem. Soc. 1990, 112,

11 J. Am. Chem. Soc. Supporting Information. Page S11 Characterization of U-601 A single crystal of U-601 was mounted in oil on glass a fiber and placed under a nitrogen cold stream at 100K on a Bruker AXS APEX2 diffractometer equipped with a CCD detector and a CuKα IμS microsource with MX optics. The crystal used for data collection was twinned, therefore scaling and an absorption correction were applied via TWIABS. The detwinned KLF4 format data yielded the best refinement model. All solvent molecules, though highly disordered, were refined. See supporting CIF files for further refinement details. Powder X-ray diffraction (PXRD) patterns for U-601 were collected using a Rigaku XDS 2000 diffractometer using CuKα radiation (λ = Å). Predicted PXRD spectra were generated using rcury v. 2.4 for Mac OsX. Samples were mounted on quartz sample holders as a slurry of ground U-601 and DMF. Thermogravimetric analysis (TGA) was recorded on a ttler Toledo TGA/SDTA851e interfaced with a PC using Star software. The heating range was from 25 C to 600 C. The heating rate was 10 ºC/min under a nitrogen atmosphere. All samples were filtered directly from DMF solutions before the experiment. PXRD of U-601. Figure S4. PXRD of U-601 with experimental in red and predicted in blue.

12 J. Am. Chem. Soc. Supporting Information. Page S12 Figure S5. PXRD of U-601 after the 1 st cycle of catalysis experiment in red and predicted in blue.

13 J. Am. Chem. Soc. Supporting Information. Page S13 Figure S6. PXRD of U-601 after the 5 th cycle of catalysis experiment in red and predicted in blue.

14 J. Am. Chem. Soc. Supporting Information. Page S14 TGA of U-601. Figure S7. TG spectrum of U-601.

15 J. Am. Chem. Soc. Supporting Information. Page S15 MR Comparisons between strut and U-601 in D 2 SO 4 D 2 SO 4 MR samples were prepared by dissolving a small quantity of U-601 (~5mg) in D 2 SO 4 and then running the sample on a Bruker AVACE III 500 Mz with a D 2 SO 4 solvent setting. Using a D 2 O solvent setting also works for this technique. ppm Figure S8. U-601 as synthesized: strut 1 (top in purple), 4-4 BIPY (middle in red) and U-601 as synthesized (bottom in blue).

16 J. Am. Chem. Soc. Supporting Information. Page S ppm Figure S9. U-601 after exchange with O 2.