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SUPPLEMENTARY INFORMATIONDOI: 10.1038/NCHEM.1272

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Supplementary Information

Imparting Functionality to a Metal-Organic Framework Material by Controlled Nanoparticle Encapsulation

Guang Lu1, Shaozhou Li1, Zhen Guo3, Omar K. Farha2, Brad G. Hauser2, Xiaoying Qi1, Yi Wang3, Xin Wang3,

Sanyang Han4, Xiaogang Liu4,5, Joseph S. DuChene6, Hua Zhang1, Qichun Zhang1, Xiaodong Chen1, Jan Ma1,

Say Chye Joachim Loo1,7, Wei D. Wei6, Yanhui Yang3, Joseph T. Hupp2★ and Fengwei Huo1★

1. School of Materials Science and Engineering, Nanyang Technological University, 50

Nanyang Avenue, Singapore 639798, Singapore

2. Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston,

Illinois 60208, USA

3. School of Chemical and Biomedical Engineering, Nanyang Technological University, 50


4. Department of Chemistry, National University of Singapore, Singapore 117543,

Singapore

5. Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602,

Singapore

6. Department of Chemistry and Center for Nanostructured Electronic Materials,

University of Florida, Gainesville, Florida 32611, USA

7. Solar Fuels Laboratory, Nanyang Technological University, Singapore 639798, Singapore

★To whom correspondence should be addressed. Email: [email protected]; j-hupp@

northwestern.edu

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Illinois 60208, USA




Singapore


Singapore





northwestern.edu

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Illinois 60208, USA




Singapore


Singapore





northwestern.edu

S1









Illinois 60208, USA




Singapore


Singapore





northwestern.edu

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β-FeOOH nanorods (22 × 160 nm): An aqueous solution of FeCl3 (0.2 M) was prepared and its pH was adjusted to 1.5 with dilute HCl. The resulting solution was heated at 70 oC for 5 hours. The product was collected by centrifugation and washed with water before drying overnight in an oven at 80 oC. As-synthesized nanorods (2 mg) were dispersed in water (10 ml) by sonication. An aqueous solution of PVP (2.5%, Mw = 55,000, 10 ml) was added to the nanorod suspension and the mixture was stirred at room temperature for 24 hours. The PVP-stabilized nanorods were collected by centrifugation at 14,800 rpm for 5 minutes, washed three times with methanol, and finally redispersed in methanol (0.2 mg/ml). Doped NaYF4 rods (50×310 nm) and nanoparticles (24 nm)8: Doped NaYF4 (30%Gd, 18%Yb, 2%Er) rods and NaYF4 (20%Yb, 0.2%Tm) nanoparticles were synthesized using the previously reported procedure8. The rods or nanoparticles were collected by centrifugation, washed with ethanol several times, and redispersed in 10 ml of chloroform (0.5 mg/ml). A solution of PVP (50 mg, Mw = 10,000) in chloroform (2 ml) was added into the rod or nanoparticle suspension and the mixture was stirred at room temperature for 24 hours. The PVP-stabilized rods were collected by centrifugation at 6,000 rpm for 5 minutes, washed three times with methanol, and finally redispersed in methanol. The PVP-stabilized NPs were precipitated with hexane and collected by centrifuging at 6,000 rpm for 5 minutes. The sample was cleaned with chloroform and hexane to remove the excess free PVP. Finally, the PVP-stabilized NPs were redispersed in methanol. References:

1. Frens, G. Controlled nucleation for the regulation of the particle size in monodisperse gold suspensions. Nat. Phys. Sci. 241, 20-22 (1973).

2. Teranishi, T., Hosoe, M., Tanaka, T. & Miyake, M. Size control of monodispersed Pt nanoparticles and their 2D organization by electrophoretic deposition. J. Phys. Chem. B 103, 3818-3827 (1999).

3. Sun, Y. & Xia, Y. Shape-controlled synthesis of gold and silver nanoparticles. Science 298, 2176-2179 (2002).

4. Li, L., Ding, J. & Xue, J. Macroporous Silica Hollow Microspheres as Nanoparticle Collectors. Chem. Mater. 21, 3629-3637 (2009).

5. Park, J. et al. Ultra-large-scale syntheses of monodisperse nanocrystals. Nature Mater. 3, 891-895 (2004).

6. Zhang, H. et al. From water-soluble CdTe nanocrystals to fluorescent nanocrystal-polymer transparent composites using polymerizable surfactants. Adv. Mater. 15, 777-780 (2003).

7. Tang, Z., Kotov, N. A. & Giersig, M. Spontaneous organization of single CdTe nanoparticles into luminescent nanowires. Science 297, 237-240 (2002).

8. Wang, F. et al. Simultaneous phase and size control of upconversion nanocrystals through lanthanide doping. Nature 463, 1061-1065 (2010).

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Illinois 60208, USA




Singapore


Singapore





northwestern.edu

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Encapsulation of various nanostructured objects in ZIF-8

Figure S6. TEM images of hybrid crystals containing 2.5 nm Pt nanoparticles (3.5%) (a), 4.1 nm Pt nanoparticles (3.0%) (b), 8 nm Fe3O4 nanoparticles (c), 24 nm lanthanide-doped NaYF4 nanoparticles (d), 180 nm PS spheres at a low contents (e), 180 nm PS spheres at a high contents (f), chains organized from CdTe nanoparticles (g), β-FeOOH nanorods (22 nm × 160 nm) (h), and lanthanide-doped NaYF4 rods (50 nm × 310 nm) (i), respectively.

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Section S8. Catalytic performances of Pt/ZIF-8 composite Preparation of catalysts 3.3 nm Pt/ZIF-8 composite was prepared via the encapsulation method reported in this paper, vacuum-dried overnight at room temperature, and used for all catalytic reactions. Pt content of 2% was determined by ICP and corresponding PVP content of ~1.9% was estimated based on Pt content and TGA measurement (in air) of Pt/PVP composite (see Figure S12b). However, it should be worth noting that small amounts of volatile matter (presumably unreacted methyl-imidazole) remains in samples activated at room temperature, as indicated by TGA measurements (see Figure S12c, a weight loss of ~0.6% at 200 oC was observed of Pt/ZIF-8 catalyst), therefore a ‘pure‘ material activated at higher temperature shoud be prefered. Three other catalysts were used as controls in the catalytic experiments: 1) pure ZIF-8 crystals; 2) Templating-method-prepared Pt/ZIF-8 composite (termed T-Pt@ZIF-8, Pt content of 2%); 3) Pt nanoparticles supported on carbon nanotubes (termed Pt/CNT, Pt content of 5%). ZIF-8 crystals: Methanolic solutions of zinc nitrate (25 mM, 15 ml) and 2-methylimidazole (25 mM, 15 ml) were mixed and allowed to react at room temperature for 24 hours without stirring. The product was collected by centrifugation, washed several times with methanol, and vacuum-dried overnight at room temperature. T-Pt@ZIF-8 composite: Dried ZIF-8 crystals (50 mg) were immersed in a solution of H2PtCl6∙6H2O (2.6 mg) in methanol (1 ml) and the mixture was sonicated for 5 minutes. After the mixture was vacuum-dried at room temperature for 2 hours, hexane (10 ml) was added. The mixture was sonicated for 5 minutes and then a solution of NaBH4 (19 mg) in methanol (0.5 ml) was added quickly to the mixture under strong stirring. The reaction was allowed to proceed for another 30 minutes. The product was collected by centrifugation, washed with methanol several times, and vacuum-dried at room temperature. TEM measurements reveal that Pt nanoparticles are formed both outside and within ZIF-8 crystals. The Pt nanoparticles on or in ZIF-8 crystals have an average particle size of ~2.4 nm. The as-synthesized catalyst was termed T-Pt/ZIF-8, and the Pt content is about 2% according to the amount of H2PtCl6. Pt/CNT composite: Multi-walled carbon nanotubes (CNTs, >95%) were purchased from Cnano. To remove the amorphous carbonaceous and metallic impurities, the pristine CNTs were treated with concentrated nitric acids (65%) at 393 K for 4 hours. To deposit Pt precursors onto pretreated CNTs, CNTs (0.1 g) were immersed in a aqueous solution of H2PtCl6∙6H2O (20 mg/ml, 722 μl) and vacuum-dried at 373 K. Ethylene glycol (40 ml) was added to the above-mentioned Pt-CNT composite and the mixture was sonicated for 10 minutes to afford a homogenous suspension. The resulting suspension was transferred into a three-neck flask with a condenser which was

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Table of contents

Section S1. General information S3

Section S2. Synthesis and surface modification of nanoparticles (NPs) S4

Section S3. Procedure for encapsulating nanoparticles in ZIF-8 S9

Section S4. X-ray diffraction measurements S15

Section S5. Fourier transform infrared (FT-IR) spectroscopy measurements S17

Section S6. Thermogravimetric analyses (TGA) S18

Section S7. Gas sorption analyses S19

Section S8. Catalytic performances of Pt/ZIF-8 composite S20

Section S9. Photoluminescence quenching of CdSe/ZIF-8 composite S29




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Section S1. General information Commercial reagents were purchased from Sigma-Aldrich (ACS grade) and used as received unless otherwise noted. Powder X-ray diffraction (XRD) patterns were recorded with a Bruker AXS D8 Advance diffractometer using nickel-filtered Cu Kα radiation (λ= 1.5406 Å). Fourier-transform infrared (FT-IR) spectra were collected on a JASCO FT-IR 480 Plus spectrophotometer. Inductively coupled plasma (ICP) spectroscopy was conducted on a Dual-view Optima 5300 DV ICP-OEM system. Scanning electron microscope (SEM) images were taken by a JEOL JSM-7600 field-emission SEM with an accelerating voltage of 5 kV. Transmission electron microscope (TEM) images were taken by a JEOL JEM 2010F at an accelerating voltage of 200 kV. The JEOL JEM 2010F is also equipped with an energy dispersive X-ray spectrometer (EDX) system and allows the elemental analysis of samples. UV-visible spectra were recorded on a Shimadzu UV-2501 spectrophotometer. Photoluminescence spectra were obtained with a Shimadzu RF-5301 spectrofluorophotometer or with a DM150i monochromator equipped with a R928 photon counting photomultiplier tube (PMT), in conjunction with a 980 nm diode laser. The luminescence images were obtained on an Olympus BX51 microscope with the xenon lamp adapted to a diode laser. Thermogravimetric analyses (TGA) were performed on a Q500 TGA (TA Instruments). Magnetization curves were measured using a LakeShore 7400 vibrating sample magnetometer (VSM) at room temperature. Nitrogen sorption studies were performed in a Micromeritics ASAP 2020 adsorption apparatus at 77 K up to 1 bar. The pore textural properties including specific Langmuir and Brunauer-Emmett-Teller (BET) surface area, pore volume, and pore size were obtained by analyzing nitrogen adsorption and desorption isotherms with Micromeritics ASAP 2020 built-in software. Hydrogen sorption studies were done on a Micromeritics Tristar II 3020 at 77 K up to 1 bar. Before starting the adsorption measurements, each sample was activated by heating under vacuum at 373 K for 12 hours unless otherwise noted.




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Section S2. Synthesis and surface modification of nanoparticles (NPs) PVP-stabilized Au NPs 1: Au nanoparticles were prepared by a sodium citrate reduction method of HAuCl4. In a typical procedure for the synthesis of 13 nm Au NPs, an aqueous solution of HAuCl4 (0.01%, 150 ml) was brought to a vigorous boil with rapid stirring in a round bottom flask (250 ml) fitted with a reflux condenser. When the solution started to boil, an aqueous solution of trisodium citrate (1%, 4.5 ml) was added. The mixture was refluxed with stirring for another 20 minutes. The resulting deep red suspension and was then removed from the heat. After the Au NP sol was cooled to room temperature, a solution of PVP (0.5 g, Mw = 55,000) in water (20 ml) was added dropwise to the Au NP sol with stirring, and the mixture was further stirred at room temperature for 24 hours. The PVP-stabilized Au NPs were collected by centrifugation at 14,000 rpm for 30 minutes, washed by methanol for three times, and final dispersed in methanol (absorbance at 520 nm, ~ 1). 34 nm Au NPs were synthesized by using 13 nm Au NPs as seeds and then modified with PVP using the same procedure decribed above. PVP-stabilized Pt NPs 2: 2.5 nm PVP-stablized Pt NPs were prepared by refluxing a mixture of PVP (533 mg, Mw=29,000), methanol (180 ml), and aqueous solution of H2PtCl6 (6.0 mM, 20 ml) in a flask (500 ml) for 3 hours under air. Methanol was removed by rotary evaporator. The NPs in the remaining solution were precipitated by acetone and then collected by centrifugation at 6,000 rpm for 5 minutes. The sample was cleaned with chloroform and hexane to remove excess free PVP. 3.3 nm PVP-stablized Pt NPs were prepared using the same procedure decribed above except that 133 mg of PVP was used. 4.1 nm PVP-stablized Pt NPs were prepared by using 3.3 nm Pt NPs as seeds. Briefly, a mixture of methanol (90 ml), freshly prepared 3.3 nm Pt NP sol (100 ml), and aqueous solution of H2PtCl6 (6.0 mM, 10 ml) was refluxed for 3 hours under air. All Pt NPs were finally dispersed in methanol (90 ml) to give a Pt content of 0.26 mg/ml according to the amount of H2PtCl6. 160 nm PVP-stabilized Ag nanocubes 3: Anhydrous ethylene glycol (5 ml) was heated at 160°C for 1 hour. An ethylene glycol solution of AgNO3 (0.25 M, 3 ml) and an ethylene glycol solution of PVP (0.375 M, Mw=55,000, 3 ml) were simultaneously added to the heated ethylene glycol using a two-channel syringe pump at a rate of 0.375 ml/min. The reaction mixture was heated at 160°C for 45 minutes. The mixture was then diluted with water and filtered through a 1 μm membrane. Silver nanocubes were collected by centrifugation, washed three times with methanol, and finally redispersed in methanol (0.2 mg/ml). 180 nm PVP-modified polystyrene (PS) spheres 4: A mixture of PVP (1.5 g, Mw=55,000), 4,4-azobis(4-cyano-valeic acid) (0.2 g), water (5 g), ethanol (22.5 g), and styrene (2 g) was bubbled with nitrogen for 30 minutes and then heated




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to 70 oC for 24 hours with stirring (~375 rpm). The as-prepared spheres were washed six times with methanol by centrifugation and finally redispersed in methanol (0.25 mg/ml). Immobilization of 13 nm Au NPs on PVP-modified polystyrene (PS) spheres: A methanolic solution of 180 nm PVP-modified PS spheres (0.25 mg/ml, 2 ml) was centrifuged at 14,800 rpm for 1 minute. The precipittate was redispersed in an aqueous solution (1 ml) of unmodified Au NPs (13 nm) by sonication for 1 minute and the suspension was kept undisturbed for 5 minutes. The sample was collected by centrifugation at 14,800 rpm for 1 minute, washed three times with methanol, and finally redispersed in methanol (10 ml). 8 nm Fe3O4 NPs 5: 8 nm Fe3O4 NPs were synthesized following the procedure of Hyeon et al. The as-synthesized NPs were precipitated with ethanol, collected by centrifugation at 6,000 rpm, and washed several times with ethanol. Fe3O4 NPs were dipersed in 20 ml of chloroform (0.5 mg/ml). A solution of PVP (250 mg, Mw = 10,000) in chloroform (10 ml) was then added. After the mixture was stirred for 24 hours, the PVP-stabilized NPs were precipitated with hexane and collected by centrifugation at 6,000 rpm for 5 minutes. The sample was cleaned with chloroform and hexane to remove the excess free PVP. Finally, the PVP-stabilized NPs were redispersed in methanol (0.25 mg/ml). CdTe NPs 6: A aqueous solution (740 ml) containing CdCl2 (1.27 mM) and mercaptopropionic acid (3.05 mM) was prepared and its pH was adjusted to 9.6 using a dilute NaOH solution. After the resulting solution was bubbled with N2 for 20 minutes, an aqueous solution of NaHTe (0.67 M, 0.56 ml), freshly prepared by reacting Te powder in an aqueous solution of NaBH4, was added quickly. The mixture was stirred for 5 minutes and then refluxed for 1 hour to produce ~2.8 nm CdTe nanoparticles. A methanolic solution of PVP (5%, Mw = 10,000, 1.25 ml) was added into a CdTe NP solution (20 ml) and the pH of the mixture was adjusted to 9. The resulting mixture was shielded from light and stirred at room temperature for 24 hours. The PVP-stabilized CdTe NPs were precipitated by adding acetone and collected by centrifuging at 6,000 rpm for 5 minutes. The sample was cleaned with chloroform and hexane to remove the excess free PVP. Finally, the nanoparticles were redispersed in methanol (0.5 mg/ml). It is worth noting that CdTe nanoparticles were found to organize into nanochains after PVP modification, which is similar to the organized structures of CdTe nanoparticles reported previously 7. 4 nm CdSe NPs: 4 nm oleic acid-capped CdSe NPs were synthesized using hot injection method. The as-synthesized NPs were precipitated with ethanol, collected by centrifugation at 6,000 rpm, and washed several times with ethanol. Oleic acid-capped CdSe NPs were modified with PVP using the same procedure used for 8 nm Fe3O4 NPs. The sample was cleaned with chloroform and hexane to remove the excess free PVP. Finally, the PVP-stabilized NPs were redispersed in methanol (0.25 mg/ml).




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β-FeOOH nanorods (22 × 160 nm): An aqueous solution of FeCl3 (0.2 M) was prepared and its pH was adjusted to 1.5 with dilute HCl. The resulting solution was heated at 70 oC for 5 hours. The product was collected by centrifugation and washed with water before drying overnight in an oven at 80 oC. As-synthesized nanorods (2 mg) were dispersed in water (10 ml) by sonication. An aqueous solution of PVP (2.5%, Mw = 55,000, 10 ml) was added to the nanorod suspension and the mixture was stirred at room temperature for 24 hours. The PVP-stabilized nanorods were collected by centrifugation at 14,800 rpm for 5 minutes, washed three times with methanol, and finally redispersed in methanol (0.2 mg/ml). Doped NaYF4 rods (50×310 nm) and nanoparticles (24 nm)8: Doped NaYF4 (30%Gd, 18%Yb, 2%Er) rods and NaYF4 (20%Yb, 0.2%Tm) nanoparticles were synthesized using the previously reported procedure8. The rods or nanoparticles were collected by centrifugation, washed with ethanol several times, and redispersed in 10 ml of chloroform (0.5 mg/ml). A solution of PVP (50 mg, Mw = 10,000) in chloroform (2 ml) was added into the rod or nanoparticle suspension and the mixture was stirred at room temperature for 24 hours. The PVP-stabilized rods were collected by centrifugation at 6,000 rpm for 5 minutes, washed three times with methanol, and finally redispersed in methanol. The PVP-stabilized NPs were precipitated with hexane and collected by centrifuging at 6,000 rpm for 5 minutes. The sample was cleaned with chloroform and hexane to remove the excess free PVP. Finally, the PVP-stabilized NPs were redispersed in methanol. References:

1. Frens, G. Controlled nucleation for the regulation of the particle size in monodisperse gold suspensions. Nat. Phys. Sci. 241, 20-22 (1973).

2. Teranishi, T., Hosoe, M., Tanaka, T. & Miyake, M. Size control of monodispersed Pt nanoparticles and their 2D organization by electrophoretic deposition. J. Phys. Chem. B 103, 3818-3827 (1999).

3. Sun, Y. & Xia, Y. Shape-controlled synthesis of gold and silver nanoparticles. Science 298, 2176-2179 (2002).

4. Li, L., Ding, J. & Xue, J. Macroporous Silica Hollow Microspheres as Nanoparticle Collectors. Chem. Mater. 21, 3629-3637 (2009).

5. Park, J. et al. Ultra-large-scale syntheses of monodisperse nanocrystals. Nature Mater. 3, 891-895 (2004).

6. Zhang, H. et al. From water-soluble CdTe nanocrystals to fluorescent nanocrystal-polymer transparent composites using polymerizable surfactants. Adv. Mater. 15, 777-780 (2003).

7. Tang, Z., Kotov, N. A. & Giersig, M. Spontaneous organization of single CdTe nanoparticles into luminescent nanowires. Science 297, 237-240 (2002).

8. Wang, F. et al. Simultaneous phase and size control of upconversion nanocrystals through lanthanide doping. Nature 463, 1061-1065 (2010).




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Figure S1. TEM images of Au nanoparticles (13±1 nm) (a), Pt nanoparticles (2.5±0.3 nm) (b), Pt nanoparticles (3.3±0.4 nm) (c), Pt nanoparticles (4.1±0.5 nm) (d), Fe3O4 nanoparticles (8±0.5 nm) (e), Au nanoparticles (34±4 nm) (f), Ag cubes (160±20 nm) (g), polystyrene (PS) spheres




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(180±7 nm) (h), 180 nm PS spheres coated with unmodified 13 nm Au nanoparticles (i), β-FeOOH nanorods (22±3 nm in diameter, 160±25 nm in length) (j), lanthanide-doped NaYF4 rods (50±10 nm in diameter, 310±60 nm in length) (k), and chains organized from 2.8 nm CdTe nanoparticles (l).




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Section S3. Procedure for encapsulating nanoparticles in ZIF-8 General encapsulation procedure All solutions used methanol as solvent. Nanoparticle dispersions (except Ag cubes, PS nanospheres, β-FeOOH nanorods, and doped NaYF4 rods) were filtered through a 200 nm membrane to remove large aggregates. Typically, a 1 ml NP solution of desired concentration, 5 ml (15 ml for Pt/ZIF-8) solution of 2-methylimidazole (25 mM), and 5 ml (15 ml for Pt/ZIF-8) solution of Zn(NO3)2⋅6H2O (25 mM) were mixed and then allowed to react at room temperature for 24 hours without stirring. The product was collected by centrifugation, washed several times with methanol, and vacuum-dried overnight.

Figure S2. a-c, UV-visible absorption spectra of the mixture of the methanolic solution of 13 nm Au nanoparticles and the methanolic solution of zinc nitrate (a), the mixture of the methanolic solution of 13 nm Au nanoparticles and the methanolic solution of 2-methylimidazole (b), and the reaction solution at 0 min and the supernatant obtained after the 24-hour product was collected by centrifugation (c). d, Photograph of the initial reaction solution (left) and the 24-hour reaction solution (right). SEM image (e) and TEM image (f) of 24-hour product described in the text.




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Optimization of encapsulation procedure The encapsulation efficiency was optimized with 13 nm Au nanoparticles by varying the concentration of 2-methylimidazole stock solution while fixing the concentrations of zinc nitrate stock solution (25 mM) and Au nanoparticles under investigation. When the molar ratio of ligand to metal ion ranged from 1 to 1.6, each crystal in the resulting product contained Au nanoparticles. If the ratio was higher than 1.6, the final product consisted of both hybrid crystals and nanoparticle-free crystals. Accordingly, we carried out the encapsulation experiments with the zinc nitrate concentration of 25 mM (in stock solution) and the metal ion/ ligand molar ratio of 1 for all nanostructured objects unless otherwise noted.

Figure S3. TEM images of products obtained from reactions with different molar ratios of 2-methylimidazole to zinc nitrate: 1:1 (a), 1.2:1 (b), 1.4:1 (c), 1.6:1 (d), 1.8:1 (e), and 2:1 (f).




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Controlling the spatial distribution of incorporated Au nanoparticles within ZIF-8 crystals by tuning their addition time

Figure S4. a, TEM image of coordination-polymer spheres formed after 15 minutes of reaction in the absence of Au nanoparticles. b, TEM image of hybrid crystals consisting of Au nanoparticle-free cores as shown in (a), nanoparticle-rich transitional layers, and nanoparticle-free shells prepared by resuming the above reaction with the addition of Au nanoparticles at the fifteenth minute. c, Low magnification TEM image of the same sample as in (b). Effect of the addtion of excess free PVP on encapsulation process In this control experiment, PVP (13.8 mg, 0.124 mmol, Mw=55,000) was added to the reaction described above by dissolving it in a methanolic solution of 2-methylimidazole (25 mM, 5 ml) prior to reaction. The product was collected by centrifugation, washed several times with methanol, and characterized by TEM, whereas the supernatant was checked by UV-visible absorption measurements.

Figure S5. a, Photograph of reaction solutions after 24 hours, without (left) and with (right) excess free PVP. b, UV-visible absorption spectra of the corresponding supernatants obtained after the products were harvested by centrifugation.




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Encapsulation of various nanostructured objects in ZIF-8

Figure S6. TEM images of hybrid crystals containing 2.5 nm Pt nanoparticles (3.5%) (a), 4.1 nm Pt nanoparticles (3.0%) (b), 8 nm Fe3O4 nanoparticles (c), 24 nm lanthanide-doped NaYF4 nanoparticles (d), 180 nm PS spheres at a low contents (e), 180 nm PS spheres at a high contents (f), chains organized from CdTe nanoparticles (g), β-FeOOH nanorods (22 nm × 160 nm) (h), and lanthanide-doped NaYF4 rods (50 nm × 310 nm) (i), respectively.




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Figure S7. Photographs of dried, homogeneously colored, samples. White ZIF-8, pink Au/ZIF-8 composite, and grey Pt/ZIF-8 composite (a). CdTe/ZIF-8 composite under illumination with ambient light (left) and 354 nm UV light (right) (b). Controlled encapsulation of two types of nanoparticles in ZIF-8

Figure S8. TEM images of hybrid crystals containing two types of nanoparticles. a-c, Encapsulation of 13 nm Au nanoparticles and 34 nm Au nanoparticles: Low magnification image of hybrid crystals containing homogeneously distributed 13 nm and 34 nm Au nanoparticles prepared by simultaneously adding these two types of nanoparticles at the beginning of reaction (a); Low magnification image (b) and high magnification image (c) of hybrid crystals consisting of 34 nm Au nanoparticle-rich cores and 13 nm Au nanoparticle-rich transition layers prepared by sequentially adding 34 nm Au nanoparticles at the beginning of reaction and 13 nm Au nanoparticles after 40 minutes. d-f, Encapsulation of 3.3 nm Pt nanoparticles and 13 nm Au




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nanoparticles: Hybrid crystals containing homogeneously distributed 3.3 nm Pt nanoparticles and 13 nm Au nanoparticles prepared by simultaneously adding these two types of nanoparticles at the beginning of reaction (d); Hybrid crystals consisting of 3.3 nm Pt nanoparticle-rich cores and 13 nm Au nanoparticle-rich transition layers prepared by sequentially adding Pt nanoparticles at the beginning of reaction and Au nanoparticles after 40 minutes (f). The 3.3 nm Pt nanoparticle-rich cores are shown in (e).




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Section S4. X-ray diffraction measurements

Figure S9. a. Powder X-ray diffraction (XRD) patterns of Au/ZIF-8 samples arrested at different reaction time. b. The same XRD patterns shown in (a), but with the intensity scale adjusted to enable observation of a weak and broadened peak associated with diffraction by Au nanoparticles. c. XRD patterns of ZIF-8 and nanoparticle/ZIF-8 composites (products of 24-hour reactions) containing 13 nm Au nanoparticles, 3.3 nm Pt nanoparticles, 160 nm Ag cubes, 8 nm Fe3O4 nanoparticles, 24 nm lanthanide-doped NaYF4 nanoparticles, and 180 nm PS spheres, respectively.




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Figure S10. A representative energy dispersive X-ray (EDX) spectrum for hybrid crystals consisting of 3.3 nm Pt nanoparticle-rich cores and 13 nm Au nanoparticle-rich transition layers prepared by sequentially adding Pt nanoparticles at the beginning of the MOF-formation reaction and Au nanoparticles after 40 minutes as shown in Fig. S8f.




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Section S5. Fourier transform infrared (FT-IR) spectroscopy measurements

Figure S11. Fourier transform infrared (FT-IR) spectra of PVP, PVP-modified Pt nanoparticles, ZIF-8, and Pt/PVP/ZIF-8 composite.




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Section S6. Thermogravimetric analyses (TGA) Thermogravimetric analyses indicate that nanoparticle/ZIF-8 composites are less thermally stable than pure ZIF-8, perhaps because of PVP chain movement and decomposition (PVP glass transition temperature, 175 oC; decomposition temperature, 435 oC). Typically, decreasing the sizes of nanoparticles, or increasing their concentration within a composite, leads to diminished thermal stability of the composite – presumably reflecting the increased PVP content in the sample. For example, a composite containing 3.5% Pt (2.5 nm in diameter) began to decompose slowly from 175 oC and lose ~17% in its weight at 500 oC at which point only 2.4% weight loss was observed for pure ZIF-8. However, high thermal stability (>400 oC) can still be achieved as exhibited by samples containing 1.3% (13 nm) Au or 0.7% Pt (3.3 nm).

Figure S12. Thermogravimetric analysis (TGA) curves of PVP in nitrogen (a), 3.3 nm PVP-modified Pt nanoparticles in nitrogen and air (b), and ZIF-8 and nanoparticle/ZIF-8 composites containing 1.3% (13 nm) Au nanoparticles, 3.5% (2.5 nm) Pt nanoparticles , 3.4% (3.3 nm) Pt nanoparticles, 2.0% (3.3 nm) Pt nanoparticles, and 0.7% (3.3 nm) Pt nanoparticles, respectively, in nitrogen (c).




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Section S7. Gas sorption analyses

Figure S13. a. Nitrogen sorption isotherms for ZIF-8 and 1.3% (13 nm) Au/ZIF-8 composite at 77 K up to 1 bar. b. Hydrogen uptake for ZIF-8 and nanoparticle/ZIF-8 composites containing 3.5% (2.5 nm), 3.4% (3.3 nm), and 0.7% (3.3 nm) Pt nanoparticles at 77 K up to 1 bar. Table S1. Surface area and gas sorption data for ZIF-8, Au/ZIF-8 composite, and Pt/ZIF-8 composites.

Sample M content† BET SA 77 K H2 uptake‡

(wt %) (m2 g

-1) (mg g

-1)

ZIF-8 0 1643 12.5

13 nm Au/ZIF-8 1.3 1567 N/A

2.5 nm Pt/ZIF-8 3.5 1501 11.9

3.3 nm Pt/ZIF-8 3.4 1500 12.0

3.3 nm Pt/ZIF-8 0.7 1568 11.9 †M (Au or Pt) contents were determined by inductively coupled plasma (ICP) analysis. ‡Maximum value at pressure up to 1 bar. BET SA: Brunauer-Emmett-Teller (BET) surface areas.




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Section S8. Catalytic performances of Pt/ZIF-8 composite Preparation of catalysts 3.3 nm Pt/ZIF-8 composite was prepared via the encapsulation method reported in this paper, vacuum-dried overnight at room temperature, and used for all catalytic reactions. Pt content of 2% was determined by ICP and corresponding PVP content of ~1.9% was estimated based on Pt content and TGA measurement (in air) of Pt/PVP composite (see Figure S12b). However, it should be worth noting that small amounts of volatile matter (presumably unreacted methyl-imidazole) remains in samples activated at room temperature, as indicated by TGA measurements (see Figure S12c, a weight loss of ~0.6% at 200 oC was observed of Pt/ZIF-8 catalyst), therefore a ‘pure‘ material activated at higher temperature shoud be prefered. Three other catalysts were used as controls in the catalytic experiments: 1) pure ZIF-8 crystals; 2) Templating-method-prepared Pt/ZIF-8 composite (termed T-Pt@ZIF-8, Pt content of 2%); 3) Pt nanoparticles supported on carbon nanotubes (termed Pt/CNT, Pt content of 5%). ZIF-8 crystals: Methanolic solutions of zinc nitrate (25 mM, 15 ml) and 2-methylimidazole (25 mM, 15 ml) were mixed and allowed to react at room temperature for 24 hours without stirring. The product was collected by centrifugation, washed several times with methanol, and vacuum-dried overnight at room temperature. T-Pt@ZIF-8 composite: Dried ZIF-8 crystals (50 mg) were immersed in a solution of H2PtCl6∙6H2O (2.6 mg) in methanol (1 ml) and the mixture was sonicated for 5 minutes. After the mixture was vacuum-dried at room temperature for 2 hours, hexane (10 ml) was added. The mixture was sonicated for 5 minutes and then a solution of NaBH4 (19 mg) in methanol (0.5 ml) was added quickly to the mixture under strong stirring. The reaction was allowed to proceed for another 30 minutes. The product was collected by centrifugation, washed with methanol several times, and vacuum-dried at room temperature. TEM measurements reveal that Pt nanoparticles are formed both outside and within ZIF-8 crystals. The Pt nanoparticles on or in ZIF-8 crystals have an average particle size of ~2.4 nm. The as-synthesized catalyst was termed T-Pt/ZIF-8, and the Pt content is about 2% according to the amount of H2PtCl6. Pt/CNT composite: Multi-walled carbon nanotubes (CNTs, >95%) were purchased from Cnano. To remove the amorphous carbonaceous and metallic impurities, the pristine CNTs were treated with concentrated nitric acids (65%) at 393 K for 4 hours. To deposit Pt precursors onto pretreated CNTs, CNTs (0.1 g) were immersed in a aqueous solution of H2PtCl6∙6H2O (20 mg/ml, 722 μl) and vacuum-dried at 373 K. Ethylene glycol (40 ml) was added to the above-mentioned Pt-CNT composite and the mixture was sonicated for 10 minutes to afford a homogenous suspension. The resulting suspension was transferred into a three-neck flask with a condenser which was




S21

subsequently placed in a microwave reactor (Sineo, MAS-II). The suspension was agitated by a magnetic stirrer and the temperature inside the flask was monitored by an infrared sensor. The suspension was heated to 438 K in 30 seconds and kept at the same temperature for 1.5 minute. After the reaction mixture was cooled to room temperature, the powder was filtrated out, washed with deionized water, and finally vacuum-dried at 373 K. The as-synthesized catalyst was denoted as Pt/CNT, and the expected Pt content is 5 wt.% and confirmed by ICP measurements.

Figure S14. TEM images of ZIF-8 crystals (a), T-Pt@ZIF-8 composite prepared using ZIF-8 as template to generate Pt nanoparticles in its cavities at low magnification (b) and at high magnification (c). Catalytic oxidation of CO The catalytic activity of Pt/ZIF-8 for CO oxidation was tested in a fixed-bed flow reactor with ~100 mg catalysts and with a gas flow mixed of CO (2 sccm), O2 (10 sccm), and He (20 sccm). The composition of the effluent gas was analyzed using a gas chromatograph (Agilent, 6890N) equipped with a Carbosieve SII column. Catalytic hydrogenation of alkenes Hydrogenation of alkenes (n-hexene >99%, trans-2-hexene >97%, or cis-cyclooctene 95%) was carried out in ethyl acetate solution in a static hydrogen atmosphere (1 bar). In a typical experiment, the catalyst (0.01g) was loaded in a reactor and residual air in the reactor was expelled by flushing sevral times with hydrogen. Ethyl acetate (0.5 ml) was added in the reactor and the mixture was sonicated for 5 minutes to afford a homogeneous suspension. Alkene (0.5 ml) was then added in the reactor and the mixture was sonicated again for 5 minutes. After the reactor was again flushed one time with hydrogen, the reaction was allowed to proceed at 1 atm of hydrogen and 35 oC for 24 hours. After the reaction, the catalyst powder was filtered off and the filtrate was analyzed using a gas chromatograph (Agilent, 6890N) equipped with a HP-5 column (Agilent) and FID. It is worth noting that the commercial chemical of 95% cis-cyclooctene (Aldrich, Cat No. 125482) contains ~3.6% cyclooctane as detected by the gas chromatograph analysis.




S22

Figure S15. CO oxidation catalyzed by 2% (3.3 nm) Pt/ZIF-8 composite. a. Conversion versus temperature; b. Conversion at 200 oC versus time.

Figure S16. a,b, TEM images of 2% (3.3 nm) Pt/ZIF-8 composite before (a) and after (b) catalyzing hydrogenation of n-hexene for three consecutive runs. Corresponding XRD patterns (c) and FT-IR spectra (d).




S23

Gas chromatograph results: Hydrogenation of n-hexene: Pt/ZIF-8 1st run

min3.8 4 4.2 4.4 4.6

pA

0

100

200

300

400

500

FID1 A, (LUHEX\29PTZIFHEXWS.D)

4.17

6

4.26

0

4.67

1

4.73

9

# Time Area Height Width Area% Symmetry 2 4.176 743.4 333.3 0.035 0.611 0.917 hexene 3 4.26 57.8 26.2 0.0337 0.048 0.922 hexane 4 4.671 120767.3 14536.5 0.1039 99.247 12.409 5 4.739 18.7 8.5 0.0336 0.015 0.618 Conversion: 7.3% Hydrogenation of n-hexene: Pt/ZIF-8 2nd run

min3.8 4 4.2 4.4 4.6

pA

0

200

400

600

800

1000

FID1 A, (LUHEX\HEPTZIF2ND.D)

4.16

6

4.25

0

4.66

7

4.73

4

# Time Area Height Width Area% Symmetry 4 4.166 1936.4 874.5 0.0348 1.505 0.93 hexene 5 4.25 204.5 92.5 0.0338 0.159 0.898 hexane 6 4.667 126305 14902.4 0.1069 98.173 13.02 7 4.734 18.2 8.4 0.0322 0.014 0.589 Conversion: 9.6%




S24

Hydrogenation of n-hexene: Pt/ZIF-8 3rd run

min3.8 4 4.2 4.4 4.6

pA

0

100

200

300

400

500

600

700

FID1 A, (LUHEX\HEAPTZIF3RD.D)

4.15

1

4.23

4

4.66

4

4.72

8

# Time Area Height Width Area% Symmetry 3 4.151 1630.8 656 0.039 1.160 0.775 hexene 4 4.234 123.4 50.1 0.0367 0.088 0.703 hexane 5 4.664 138474.3 15373.1 0.1121 98.539 13.561 6 4.728 19.9 9.3 0.0321 0.014 0.574 Conversion: 7.1% Hydrogenation of n-hexene: ZIF-8

min3.8 3.9 4 4.1 4.2 4.3 4.4 4.5 4.6 4.7

pA

0

200

400

600

800

1000

FID1 A, (LUHEX\HEZIF.D)

4.17

0

4.66

4

4.73

4

# Time Area Height Width Area% Symmetry 4 4.17 1944.6 863.8 0.0353 1.592 0.907 hexene 5 4.664 120135.8 14453.1 0.106 98.356 11.372 6 4.734 19.2 8.5 0.0333 0.016 0.599 Conversion: 0




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Hydrogenation of n-hexene: T-Pt@ZIF-8

min3.8 4 4.2 4.4

pA

0

500

1000

1500

2000

2500

FID1 A, (LUGUANG\PTOUTZIFC24HT03.D)

3.796

3.874

3.948

4.296

4.351

# Time Area Height Width Area% Symmetry 2 3.796 5352.6 2325.7 0.0349 2.917 0.863 Hexene 3 3.874 820.3 361.7 0.0345 0.447 0.826 Hexane 4 3.948 131.7 52.1 0.0375 0.072 0.818 5 4.296 176955.3 18808.3 0.1148 96.435 16.484 6 4.351 34.2 14.9 0.0337 0.019 0.479 Conversion: 13.3% Hydrogenation of n-hexene: Pt/CNT

min3.8 4 4.2 4.4 4.6

pA

0

100

200

300

400

500

600

FID1 A, (LUHEX\HEPTCNT.D)

4.17

0

4.25

4

4.33

5

4.64

9

4.72

4

# Time Area Height Width Area% Symmetry 2 4.17 1265.3 539.8 0.0363 1.062 1.019 hexene 3 4.254 252.1 110.5 0.0356 0.212 0.989 hexane 4 4.335 6.2 2.7 0.0351 0.005 0.985 5 4.649 117542.7 13664.9 0.1104 98.628 12.073 6 4.724 16.4 7.4 0.0337 0.014 0.625 Conversion: 16.6%




S26

Commercial cyclooctene: raw material

min7.5 8 8.5 9 9.5

pA

0

100

200

300

400

500

600

700

FID1 A, (LUHEX\OC.D)

8.22

0

9.36

0

# Time Area Height Width Area% Symmetry 12 8.22 2603.6 586.3 0.0628 2.230 2.236 cyclooctene 13 9.36 96.7 22.5 0.0671 0.083 0.879 cyclooctane Cyclooctane content: 3.6% Hydrogenation of cyclooctene: ZIF-8

min7.5 8 8.5 9 9.5

pA

0

200

400

600

800

FID1 A, (LUHEX\OCZIF.D)

8.25

3

9.37

1

# Time Area Height Width Area% Symmetry 12 8.253 3880.9 780.2 0.071 2.966 3.101 cyclooctene 13 9.371 144.9 33.5 0.0665 0.111 0.936 cyclooctane Cyclooctane content: 3.6% Conversion: 0




S27

Hydrogenation of cyclooctene: Pt/ZIF-8

min7.5 8 8.5 9 9.5

pA

0

100

200

300

400

500

600

700

FID1 A, (LUHEX\OCPTZIF.D)

8.24

3

9.36

8

# Time Area Height Width Area% Symmetry 12 8.243 3406.8 715.4 0.0666 2.708 2.831 cyclooctene 13 9.368 127 29.5 0.0682 0.101 0.908 cyclooctane Cyclooctane content: 3.6% Conversion: 0 Hydrogenation of cyclooctene: T-Pt@ZIF-8

min6.5 7 7.5 8 8.5 9 9.5

pA

0

200

400

600

800

1000

1200

1400

FID1 A, (LUGUANG\PTOUTZIFC24H002.D)

7.572

8.541

# Time Area Height Width Area% Symmetry 12 7.572 9662.2 1493.9 0.0835 6.330 6.161 Cyclooctene 13 8.541 535.8 130.4 0.065 0.351 1.156 Cyclooctane Cyclooctane content: 5.3% Conversion: 1.7%




S28

Hydrogenation of cyclooctene: Pt/CNT

min7.5 8 8.5 9 9.5

pA

0

100

200

300

400

500

600

700

800

FID1 A, (LUHEX\OCPTCNT.D)

8.24

5

9.37

6

# Time Area Height Width Area% Symmetry 13 8.245 3458.8 721.5 0.0669 2.697 2.829 cyclooctene 14 9.376 435.7 101 0.0673 0.340 1.026 cyclooctane Cyclooctane content: 11.2% Conversion: 7.6%




S29

Section S9. Photoluminescence quenching of CdSe/ZIF-8 composite

CdSe/ZIF-8 composite or PVP-modified CdSe nanoparticles (as control) were dispersed in 2.5 ml methanol and placed in a quartz cuvette. Suspensions were excited at 400 nm and the intensity of emission at 544 nm was recorded before and after adding 20 μl of 100 mM methanolic solutions of 2-mercaptoethanol or cyclohexanethiol.

Figure S17. a. TEM image of CdSe/ZIF-8 composite. b. Photographs of CdSe/ZIF-8 composite suspended in methanol illuminated with ambient light (left) and 354 nm UV light (right).

Figure S18. a. Normalized photoluminescence intensity at 544 nm (excitation at 400 nm) of CdSe/ZIF-8 composite suspended in methanol versus time after addition of thiol molecules. b-e. Normalized photoluminescence spectra with excitation at 400 nm for PVP-modified CdSe nanoparticles (b-c) and CdSe/ZIF-8 composites (d-e) in methanol before (red) and after (blue) addition of thiol molecules.


supplementary information section s8. … infrared (ft-ir) spectra were collected on a jasco ft-ir...

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