Electronic Supplementary Information. Brønsted Basicity in Metal-organic Framework-808 and Its Application in Base-free Catalysis

Transcription

1 Electronic Supplementary Information Brønsted Basicity in Metal-organic Framework-808 and Its Application in Base-free Catalysis Xiaodan Yan, Kai Wang, Xiaocheng Xu, Shuhua Wang*, Qian Ning, Weiming Xiao, Ning Zhang, Zijuan Chen, Chao Chen* Institute of Applied Chemistry, College of Chemistry, Nanchang University, Nanchang, , P. R. China Table of Contents Section S1. Experimental details 2-5 General materials, Preparation, Catalysis reaction, and Material characterizations Section S2. Figures 6-11 Structural representation, PXRD patterns, SEM and TEM images, NMR spectra, Acid-base titration curves, Reusability of catalyst, NH 3 -TPD-MS profiles, and N 2 adsorption/desorption isotherms curves Section S3. Table Heck coupling reaction of different substrates, Tandem reaction oxidation of benzyl alcohol, the oxidation and Aldol condensation reactions Section S4. References 14 1 / 15

2 Section S1. Experimental details 1. General materials. Starting materials and solvents were purchased and used without further purification from commercial suppliers (Sigma-Aldrich, TCI, ACROS etc.). DMF and chloroform were dried using molecular sieves. 2. Preparation. 2.1 Synthesis and activation of MOF-808a MOF-808a was synthesized according to the previous reports [1,2] of MOF-808 with slight modifications, and then activated by heating it in fresh DMF and ethylene glycol (EG) for 24 h. Typically, a mixture of Trimesic acid (H 3 BTC, 0.28g, 1.33 mmol) and Zirconium oxychloride octahydrate (ZrOCl 2 8H 2 O, 1.293g, 4 mmol) in 60 ml of DMF and 60mL of formic acid were packed in 200ml hot water kettle reaction at 130 o C for 48 h, the resulting white solid was collected by filtration and was washed with DMF. Then, the as-synthesized MOF-808 was activated by introducing the material in hydrothermal bomb with 50 ml DMF and 5 ml EG at 130 o C for 24 h. The solid was collected by filtration, rinsed three times per day with DMF for three days, and immersed in 10 ml of anhydrous acetone for three days, during which time the acetone was replaced three times per days. Acetone exchanged material was evacuated at 150 o C for 24 h to yield MOF-808a. 2.2 Synthesis of Pd/MOF-808a A mixture of MOF-808a (1.0g) and palladium acetate (0.167 mmol) in 60 ml of DMF was stirred at 130 o C for 6 hours, and then treated under a stream of 100% H 2 at 150 o C for 2 hours. The resulting black solid was collected by centrifugation and washed with DMF and ethanol, finally was heated at 70 o C for 24 h under vacuum. 2 / 15

3 3. Catalytic reactions Typical procedures for Heck coupling reaction:iodobenzene (0.5 mmol) olefin (0.6 mmol),ethylene glycol (0.6 mmol) as a co-catalyst, dodecane as internal standard (46ul),and supported palladium catalyst 100mg (Ca. 3% mmol of Pd) were added to 4 ml of DMF. The reaction mixture was stirred at 130 o C for 24 h. Upon reaction completion, the catalyst particles were removed from the solution by filtration through a 0.45 μm filter and washed with DMF. The liquid phase was subsequently analyzed by GC 7890B (equipped with a 0.25 mm 30 m HP-5 capillary column). Typical procedure for alcohol oxidation tandem reaction:benzyl alcohol (1.0 mmol),dodecane as internal standard (46ul) and supported palladium catalyst 60 mg (1.8% mmol of Pd) were added to 5 ml of methanol. The reaction mixture was stirred at 80 o C under 1 MPa oxygen atmosphere for 24 h. The liquid phase was subsequently analyzed by GC 7890B (equipped with a 0.25 mm 30 m HP-5 capillary column). 4. Material characterizations 1 H NMR Digestion and Analysis. Approximately 10 mg of microcrystalline sample was digested by sonication in 570 μl of d 6 -DMSO and 30 μl of HF. After complete dissolution of the material, the solution was used to collect a 1 H NMR spectrum. 1 H NMR spectra were recorded on an Aglient NMR spectrometer (DD2 400-MR, 400 MHz). Powder X-ray diffraction (PXRD) Analysis. PXRD data were collected at ambient temperature on a Puxi DX-3 diffractometer at 40 kv, 40 ma for Cu Kα (λ = Å), with a scan speed of 1 /min, a step size of 0.02 in 2θ, and a 2θ range of N 2 Sorption. BET surface area (m 2 /g) measurements were collected at 77 K with dinitrogen on a Micromeritics ASAP 2020 Adsorption Analyzer using volumetric technique. Approximately mg of activated samples were evacuated on a 3 / 15

4 vacuum line for 12 h, then transferred to a pre-weighed sample tube and degassed at 130 C for approximately 18 h or until the outgas rate was < 5 μmhg. The sample tube was reweighed to obtain a consistent mass for the degassed samples. Inductive Coupled Plasma Emission Spectrometer Analysis (ICP). Approximately 5 mg of crystalline sample was dried in a 50 C oven for 3 h, and the sample was digested by sonication in 3 ml of aqua regia. Then the solution is collected by filtration and diluted to 10 ml. Metal Pd content was analyzed on the Aglient 5100 ICP-OES. In situ DRIFTS Analysis. The measurement was conducted on Bruker TENSOR II FT-IR spectrometer equipped with a situ cell (PIKE) with KBr window film and mercury cadmium (MCT) detector. The sample was placed into the cell attached to a closed circulation system. Prior to measurement, the disk was purged by Ar (100 ml/min) and heated at 200 o C for 2 h to remove physisorbed water and gases. After gaseous CO 2 (100ml/min) had been introduced on to the sample in the cell at room temperature for 1 h, the system was purged by Ar (100 ml/min) for 2h to remove the physisorbed CO 2. Finally, the diffuse reflectance infrared spectra were detected at different temperatures. CO 2 -TPD-MS and NH 3 -TPD-MS Analyses. The overall surface basicity and acidity of the samples were determined by temperature programmed desorption of CO 2 and ammonia, respectively (CO 2 -TPD and NH 3 -TPD, Micromeritics AutoChem 2920 instrument). A multichannel mass spectrometer (MS, THERMO Star TM ) was employed for on-line analysis of the released gas. Prior to gaseous sorption the sample was pretreated in He (30 ml/min) at 150 o C for 2 h. A mixture of adsorption gas (CO 2 or NH 3 ) in N 2 (0.5 vol%) was passed (30 ml/min) at 30 o C for 1 h. Then, the sample was flushed with He (30 ml/min) for 2 h. desorption was carried out by raising the temperature from 30 o C to 250 o C at a linear heating rate of 10 o C/min. Desorption of CO 2 and NH 3 were studied by monitoring the signals at m/z = 44 and 17, respectively. 4 / 15

5 Acid-base Potentiometric Titration Analyses. Potentiometric titrations were carried out with a Metrohm Titrando Ti-916 equipped with Dosino ml and 10 ml dosing units. The procedures are similar to those reported for MOFs and others acid-base materials (J. Mater. Chem. A, 2016, 4, and Acta Chimica Sinica, 2012, 6, ). Calibration was performed with commercial ph buffers 2.00, 4.00, 7.00, and 9.00 (Metrohm). Prior to titration, the samples were ground with a mortar and pestle, and then approximately 50mg of sample was dispersed in approximately 60mL of 0.01Maq. NaNO 3 solution, covered with parafilm, and allowed to equilibrate for 24 h. For acid titration, the ph was adjusted to 3 with 0.1 M hydrochloric acid solution under magnetic stirring, and then titrated to ph with 0.1 M sodium hydroxide solution using a single 0.025ml injection volume, dynamic intelligent drip rate. For base titration, the mixture was titrated to ph 2-3 with 0.1 M hydrochloric. Equivalence points were obtained from the first derivative of the resulting titration curve of ph as a function of volume of titrant added, where the maximum points in the derivative curve correspond to inflection points and indicate equivalence points. The pk b value was determined as the ph at one-half of the volume of titrant added to reach the equivalence point. 5 / 15

6 Section S2. Figures Figure S1. A description of the structural fashion of MOF-808: each Zr 6 (µ 3 -O) 4 (µ 3 -OH) 4 (HCOO) 6 (CO 2 ) 6 SBU is interconnected to six BTC 3- ligands and each BTC 3- ligand coordinates with three SBUs, leading to the formation of spn topological 3D framework. Zr atoms, blue polyhedral; yellow spheres (site occupancy of 0.25) and earthy yellow spheres (site occupancy of 0.5), other C atoms, gray spheres, O atoms, red spheres, BTC ligand, green triangle. Figure S2. PXRD patterns of the simulated MOF-808 on the basis of the single-crystal structure analysis (a), the as-synthesized MOF-808a (b), the Pd/MOF-808a (c), the recovered sample of Pd/MOF-808a after tenth cycles for heck coupling reaction (d), and the recovered sample of Pd/MOF-808a after third cycles for catalyzing the oxidation of benzyl alcohol as a one pot tandem reaction (e). 6 / 15

7 Figure S3. SEM image of MOF-808a (a), TEM image of Pd/MOF-808a, and the inserted bar chart shows the particle distribution of Pd NPs (b), HR-TEM image of Pd/MOF-808a, and the measurement of d-spacing of crystals according to the reported value for Pd nanoparticle (d pd(100) = 0.23 nm) (c), and TEM image of recovered Pd/MOF-808a after tenth cycles for Heck reaction, and the inserted bar chart shows the particle distribution of Pd NPs (d). Figure S4. 1 H NMR spectra upon digestion of the samples of MOF-808a and MOF-808 in HF/DMSO-d 6 solution. Note that the peak of formate of MOF-808a disappears after the activation. 7 / 15

8 Figure S5 Acid titration curve of MOF-808a. Figure S6. TEM images of Pd/UiO-66 (a) and Pd/ZrO 2 (b). 8 / 15

9 Figure S7. Reusability of Pd/MOF-808a for heck coupling reaction. Figure S8. Heck coupling reaction over (a) Pd/MOF-808a and (b) filtration solution (Pd/MOF-808a filtered-off after 6 h reaction time). 9 / 15

10 Figure S9. NH 3 -TPD-MS profiles over a blank sample MOF-808a without adsorbing NH 3 and a sample with adsorbing CO 2 initially. Figure S10. Base titration curve of MOF-808a (red) and first derivative curve (blue), which is consistent with the previous report of ref. [3]. 10 / 15

11 Figure S11. CO 2 -TPD-MS profiles over ZrO 2 and UiO-66. Figure S12. The nitrogen adsorption/desorption isotherms curves of MOF-808a and Pd/MOF-808a. The BET surface areas for them were ~2100 and 1000 m 2 /g, respectively. 11 / 15

12 Section S3 Table Table S1. The heck coupling reaction of different substrates a Entry Cat. R Yield(%) b 1 Pd/MOF-808a Pd/MOF-808a 85 3 Pd/MOF-808a Pd/MOF-808a 97.8 a Reaction was carried out in 0.5mmol of iodobenzene, 0.6mmol olefin, 100 mg of Pd/MOF-808a (Ca. 3 mmol% equiv of Pd), and 0.6 mmol ethylene glycol as a co-catalyst, in 4 ml DMF at 130 o C for 24 h unless otherwise noted. b The yields were determined by GC on a HP-5column, dodecane as internal standard. 12 / 15

13 Table S2. Tandem reaction oxidation of benzyl alcohol a Entry Cat. Conv. (%) PhCHO Yield (%) b PhCHO 2 Me 1 Pd/MOF-808a > Pd/MOF-808a (2 nd ) c Pd/MOF-808a (3 rd ) Pd/MIL Pd/UiO None a Reaction was carried out in 1.0 mmol benzyl alcohol and 60 mg catalyst (Ca. 1.8 mmol% equiv of Pd) at 80 o C under 1 MPa O 2 for 24 h. The yields were determined by GC on a HP-5column. c The second time recovered Pd/MOF-808a catalyst. 13 / 15

14 Table S3. The oxidation reaction from benzyl alcohol to benzaldehyde a Entry Cat. Conv.(%) b 1 Pd/MOF-808a Pd/UiO a Reaction was carried out in 1.0 mmol benzyl alcohol, 60 mg catalyst (Ca. 1.8 mmol% equiv of Pd), and 5 ml acetonitrile, at 80 o C under 1 MPa O 2 for 24 h. on a HP-5column. b The yields were determined by GC Table S4. The Aldol condensation reaction from benzaldehyde to methylbenzoate a Entry Cat. Conv.(%) b 1 Pd/MOF-808a Pd/UiO a Reaction was carried out in 1.0 mmol benzaldehyde, 60 mg catalyst (Ca. 1.8 mmol% equiv of Pd), and 5 ml methanol, at 80 o C under 1 MPa O 2 for 24 h. on a HP-5column. b The yields were determined by GC 14 / 15

15 References: [1] Jiang, J.; Gandara, F.; Zhang, Y. B.; Na, K.; Yaghi, O. M.; Klemperer, W. G., Superacidity in sulfated metal-organic framework-808. J. Am. Chem. Soc. 2014, 136, [2] Moon, S. Y.; Liu, Y.; Hupp, J. T.; Farha, O. K., Instantaneous hydrolysis of nerve-agent simulants with a six-connected zirconium-based metal-organic framework. Angew. Chem. Int. Ed. 2015, 54, [3] Klet, R. C.; Liu, Y.; Wang, T. C.; Hupp, J. T.; Farha, O. K., Evaluation of Brønsted acidity and proton topology in Zr- and Hf-based metal organic frameworks using potentiometric acid base titration. J. Mater. Chem. A 2016, 4, / 15