Double-Solvent Method to Pd Nanoclusters Encapsulated inside the

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Double-Solvent Method to Pd Nanoclusters Encapsulated Inside the Cavity of NH-Uio-66(Zr) for Efficient Visible-Light-Promoted Suzuki Coupling Reaction 2

Dengrong Sun, and Zhaohui Li J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.6b06710 • Publication Date (Web): 24 Aug 2016 Downloaded from http://pubs.acs.org on August 30, 2016

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The Journal of Physical Chemistry

Double-Solvent Method to Pd Nanoclusters Encapsulated inside

the

Cavity

of

NH2-Uio-66(Zr)

for

Efficient

Visible-Light-Promoted Suzuki Coupling Reaction Dengrong Sun and Zhaohui Li*

Research Institute of Photocatalysis, State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou, 350002 (P.R. China)

1

ACS Paragon Plus Environment


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Abstract Active Pd nanoclusters smaller than 1.2 nm encapsulated inside the cage of NH2-Uio-66(Zr) (Pd@NH2-Uio-66(Zr)) were prepared via a double-solvent approach combined with a photo-reduction process. The resultant Pd@NH2-Uio-66(Zr) showed excellent performance for Suzuki coupling reaction under visible light irradiations as a result of the efficient electron transfer from the light-excited NH2-Uio-66(Zr) to the confined Pd nanoclusters and the presence of large amounts of catalytic active Pd species. The successful coupling of MOF-based photocatalysis with metal-based catalysis over metal@MOFs is expected to bring about vast opportunities for developing active catalysts for a variety of light-induced organic transformations attributed to the diversified MOF structures and their tunable characteristics.

2


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Introduction Metal nanoparticles have received enormous attention due to their great potential in various kinds of applications, especially in catalysis.1-3 The particle size of the nanoparticles is one of the important factors that great influence on their properties. Size shrinkage of the nanoparticles to subnanometer scale such as nanoclusters can significant increase their catalytic efficiency due to the high surface-to-volume ratio, great ratio of atoms remaining at the large surface area and the high density of the coordination unsaturated sites.4-5 However, a size-controllable synthesis of metal nanoclusters on the surface of the support is usually difficult since aggregation of the metal nanoclusters readily occurs due to their high surface energy. An effective strategy to obtain nanoclusters is employing the nanopores of porous materials as nano-reactors to confine the growth of the nanoclusters.6-7 Metal-organic frameworks (MOFs) is a class of crystalline micro-mesoporous hybrid materials with extended 3D networks.8-13 The uniform and ordered nanopores in MOFs provide well-defined micro environments that could induce size control on the confined nanoclusters, while in the mean time the organic ligands can act as anchors to stabilize these metal nanoclusters.14-17 Due to the highly porous structure of MOFs, which can ensure the efficient accessibility of reactant molecules to the active metal site, the thus-developed metal nanoclusters encapsulated MOFs (metal@MOFs) have already shown to be promising in heterogeneous catalysis.18-29 After decades of development, different strategies for the synthesis of metal@MOFs have been developed, among which the double-solvent method reported by Xu and co-workers has attracted much attention due to its high generality and easy operability.30-31 However, strong reducing agents such as H2 and NaBH4 are involved in the synthesis process, which may compromise the stability of MOFs. Therefore, development of complementary approach for the synthesis of metal@MOFs without using strong reducing agent is highly desirable. Herein, we reported for the first time the synthesis of Pd nanoclusters (smaller than

1.2

nm)

encapsulated

NH2-Uio-66(Zr)

(Pd@NH2-Uio-66(Zr))

3


via

a


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double-solvent method combined with a photoreduction process. By successful coupling of the MOF-based photocatalysis with Pd catalysis, the as-prepared Pd@NH2-Uio-66(Zr) showed excellent performance for the visible-light-promoted Suzuki coupling reaction due to the presence of large amounts of catalytic active Pd sites and the efficient electron transfer from the light-excited NH2-Uio-66(Zr) to the confined Pd nanoclusters. This work demonstrated an effective, mild and facile way for the encapsulating of the metal nanoclusters inside the cavity of MOFs. The successful coupling of the MOF-based photocatalysis with metal-based catalysis is anticipated to bring infinite possibilities for developing multifunctional catalysts for various light-induced organic transformations attributed to the diversified MOF structures and their tunable characteristics. Experimental Section Materials 2-aminoterephthalate (H2ATA) were purchased from Alfa Aesar Co. Pd(NO3)2·2H2O and ZrCl4 were purchased from Shanghai Chemical Reagent Co. Anhydrous N,N-dimethylformamide (DMF) and n-hexane was purchased from Sigma Aldrich Co. All the reagents were analytical grade and used without further purification. Synthesis of NH2-Uio-66(Zr) NH2-Uio-66(Zr) was prepared following a previous reported procedure with a slight modifications.32 Typically, ZrCl4 (0.240 g, 1.029 mmol) and 2-aminoterephthalate (H2ATA)

(0.1860

g, 1.029 mmol) were

dissolved in anhydrous N,N- dimethylformamide (DMF) (60 ml) at room temperature. De-ionized water (0.19 ml) was dropped to the mixture. The obtained mixture was stirred at room temperature for 10 min and was transferred to a 100 ml Teflon liner and heated at 120 °C for 24 h. After hydrothermal treatment, the resultant suspension was filtered, washed with DMF and methanol respectively, extracted by Soxhlet extractor with methanol and vacuum dried to obtain the product. Synthesis of Pd2+@NH2-Uio-66(Zr) The Pd2+@NH2-Uio-66(Zr) was prepared according to the previous reported double-solvent method with a slight modifications.30-31 Before the encapsulation, NH2-Uio-66(Zr) was activated at 150 °C under vacuum to remove the residual solvent in the pores. After that, 100 mg of 4


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activated NH2-Uio-66(Zr) was suspended in 20 ml of anhydrous n-hexane, which acts as hydrophobic solvent. The obtained mixture was sonicated for about 1 h until it became homogeneous. After that, 12.5 µl of hydrophilic Pd(NO3)2·2H2O aqueous (0.75 M) was added dropwise over a period of several min under constant vigorous stirring. Subsequently, the resultant suspension was continuously stirred for another 2 h. After stirring, the solid which settled down to the bottom of the sample vial was isolated from the supernatant by decanting and washed with ethanol and dried under vacuum to obtain the Pd2+@NH2-Uio-66(Zr). Synthesis of Pd@NH2-Uio-66(Zr) The activated Pd2+@NH2-Uio-66(Zr) was suspended in degassed ethylene glycol (EG, 6 ml) and irradiated under visible light for 6 h. The resultant solid was washed with ethanol and water for several times and dried under vacuum to obtain the Pd@NH2-Uio-66(Zr). Synthesis of Pd/NH2-Uio-66(Zr) Pd/NH2-Uio-66(Zr) was synthesized by employing a conventional single-solvent impregnation process. Typically, 12.5 µl of Pd(NO3)2·2H2O aqueous (0.75 M) was added into the ethylene glycol (EG, 6ml) suspension of NH2-Uio-66(Zr) (100 mg) under N2. The obtained suspension was irradiated under visible light irradiations for 6 h. The resultant solid was washed with ethanol and water for several times and dried under vacuum to obtain the Pd/NH2-Uio-66(Zr). Characterizations X-ray diffraction (XRD) patterns were collected on a D8 Advance X-ray diffractometer (Bruker, Germany) with Cu Kα radiation. The accelerating voltage and the applied current were 40 KV and 40 mA, respectively. Data were recorded at a scanning rate of 0.02 ° 2θ s-1 in the 2θ range of 5 ° to 60 °. UV-visible diffuse reflectance spectra (UV-DRS) of the powders were obtained with the BaSO4 used as a reflectance standard in the UV-visible diffuse reflectance experiment. BET surface area was carried out on an ASAP 2020M apparatus (Micromeritics Instrument Corp., USA). The samples were degassed in vacuum at 200 °C for 6h and then measured at 77 K. The transmission electron microscopy (TEM) images were obtained in a JEOL model JEM 2010 EX instrument. Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) was performed on 5



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Optima 8000 (Perkin-Elmer). Before ICP-OES experiment, the solid sample was digested in mixture of HNO3 and milli-Q water. The photocatalytic reaction was performed with a 300 W Xe arc lamp (Beijing Perfectlight, PLS-SXE300c). Photocatalytic reaction The photocatalytic Suzuki coupling reaction was performed in a sealed reaction tube under visible light irradiations at room temperature (30 °C). The photocatalyst (5 mg) suspended in a mixture of DMF and H2O (2 ml, 1/1 v/v) with aryl halides (0.1 mmol), boronic acids (0.2 mmol) and triethylamine (TEA) (0.3 mmol) were degassed and saturated with N2 to remove the dissolved O2 before the photocatalytic reaction. The reaction was performed under the irradiation of a 300 W Xe lamp with a UV-cut filter to remove all wavelengths less than 420 nm and an IR-cut filter to remove all wavelengths larger than 800 nm. During the reaction process, a radiator fan was used to coll down the reaction tube to ensure that the reaction proceeded at room temperature. The reaction products were analyzed by GC-MS and GC-FID (Shimadzu GC-2014) with a FFAP capillary column. The used photocatalyst was washed with DMF and methanol for several times respectively and dried for the cycling test. Results and Discussion NH2-Uio-66(Zr)

was

prepared

following

the

procedures reported

previously.32 The as-obtained NH2-Uio-66(Zr) showed similar XRD patterns and BET specific surface area (896 m2 g-1) comparable to that reported previously, indicating the formation of NH2-Uio-66(Zr) with high quality (Figure

1

and

S1).

Pd

encapsulated

NH2-Uio-66(Zr)

(denoted

as

Pd@NH2-Uio-66(Zr)) was prepared by a double-solvent impregnation followed by a photo-reduction process. For the impregnation process, activated NH2-Uio-66(Zr) was suspended in a large amount of anhydrous n-hexane, followed by a drop-wise addition of Pd(NO3)2·2H2O aqueous solution with a volume less than the pore volume of NH2-Uio-66(Zr) under vigorous stirring. It is believed that the presence of the excessive hydrophobic hexane can overspread the external surface, which ensures the diffusion of hydrophilic Pd(NO3)2·2H2O into the pores of NH2-Uio-66(Zr) via capillary force. The 6


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following photo-reduction process resulted in the formation of cavity encapsulated Pd@NH2-Uio-66(Zr). A similar double-solvent impregnation approach was first developed by Xu et al. to encapsulate Pt and AuNi NPs inside the cavity of MIL-101(Cr).30-31 As compared to the reduction process using strong reducing agent such as H2 and NaBH4, the current photo-reduction is greener and milder since no extra reducing agent is required, which is more favorable for preserving the framework of the MOFs. The as-prepared Pd@NH2-Uio-66(Zr) shows similar XRD patterns with the parent NH2-Uio-66(Zr), indicating that the structure of NH2-Uio-66(Zr) was well preserved (Figure 1). Although no characteristic diffraction for Pd was observed in the XRD patterns, the existence of metallic Pd was confirmed by the X-ray photoelectron spectroscopy (XPS) results. (Figure S2).33 Transmission electron microscopy (TEM) images and energy-dispersive X-ray spectroscopy (EDX) analyses show that the surface of the Pd@NH2-Uio-66(Zr) is smooth, suggesting that no Pd NPs were deposited on the external surface of NH2-Uio-66(Zr) (Figure 2 and S3). TEM and high-angle annular dark-field scanning TEM (HAADF-STEM) images reveals that Pd nanoclusters smaller than the pore size of NH2-Uio-66(Zr) (1.2 nm) are highly dispersed in Pd@NH2-Uio-66(Zr), indicating that Pd nanoclusters have been confined in the pore of NH2-Uio-66(Zr) (Figure 2 and S3). On the contrary, for Pd/NH2-Uio-66(Zr) prepared by a conventional single-solvent impregnation process, where NH2-Uio-66(Zr) was directly suspended in a large amount of solvent containing Pd precursor, Pd nanoparticles with an average diameter of 9.3 nm were deposited on the surface of NH2-Uio-66(Zr) (Figure S4). This demonstrated that the double-solvent approach can effectively and facilely confine the Pd nanoclusters in the pore of NH2-Uio-66(Zr). The amount of encapsulated Pd in Pd@NH2-Uio-66(Zr) was determined to be 0.67 wt % by inductively coupled plasma optical emission spectrometer (ICP-OES). The Pd@NH2-Uio-66(Zr) exhibited similar light absorption properties as NH2-Uio-66(Zr) with two main absorption peaks centering at around 265 and 365 nm, which can be attributed to the Zr-O clusters and the ligand-based absorption of NH2-Uio-66(Zr) (Figure 3a).34 7



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Pd catalysts have been widely used in C-C coupling reactions such Suzuki coupling reaction.35-41 Previous reports have showed that Pd nanoclusters dislodged from Pd nanoparticles are more active for Suzuki coupling reactions as compared with larger Pd nanoparticles.42-44 Therefore, it is anticipated that the as-prepared Pd nanoclusters encapsulated NH2-Uio-66(Zr) can exhibited excellent catalytic activity for the Suzuki coupling reaction. To study the performance of the as-prepared Pd@NH2-Uio-66(Zr) for Suzuki coupling reaction, the coupling of iodobenzene with phenylboronic acid was performed in the presence of triethylamine (TEA) under visible light irradiations. Basic DMF was first chosen as the solvent as considering that some acidic by-products might be produced during the coupling reaction. However, no biaryl product was detected after reacting for 30 min (Entry 1, Table 1). Addition of equal amount of H2O to the reaction system led to a high catalytic activity with an iodobenzene conversion of 90.4% after irradiating for 30 min (Entry 2, Table 1). Actually, similar promotion induced by H2O has also been observed in other Pd catalyzed Suzuki reaction systems, in which H2O assists the formation of hydroxyl anions for boronic acid activation.45 Prolonging the reaction to 45 min resulted in an almost total conversion of iodobenzene (>99%) and an excellent selectivity to biphenyl (>99%) (Entry 3, Table 1). The homo-coupling of iodobenzene or phenylboronic acid was not observed over Pd@NH2-Uio-66(Zr) under the current reaction condition. The reaction can not proceed in the absence of Pd@NH2-Uio-66(Zr), indicating that the coupling reaction was induced by Pd@NH2-Uio-66(Zr) (Entry 4, Table 1). Pd is essential to the reaction because no reactivity was observed over bare NH2-Uio-66(Zr) without Pd immobilization (Entry 5, Table 1). Only 10.5% of iodobenzene was converted when the reaction was performed without light iradiations (Entry 6, Table 1), which is obviously lower than that obtained upon visible light irradiations. This indicated the significant promoting effect of light on the Pd@NH2-Uio-66(Zr) catalyzed Suzuki coupling reaction. Actually, the promoting effect of light on the coupling reaction was also confirmed by the 8


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results that the conversion of iodobenzene improved with the incident light intensity (Figure 3b). No further reaction occurred in the filtrate after Pd@NH2-Uio-66(Zr) was removed from the reaction system, suggesting that the Suzuki coupling reaction is truly induced by the heterogeneous photocatalysis of Pd@NH2-Uio-66(Zr). These results clearly indicated that Pd@NH2-Uio-66(Zr) is capable of catalyzing the Suzuki coupling reaction between iodobenzene and phenylboronic under visible light irradiations. No obvious aggregation of the Pd nanoclusters in Pd@NH2-Uio-66(Zr) was observed after reaction, indicating that Pd@NH2-Uio-66(Zr) is stable during the reaction (Figure S5). The high stability and reusability of Pd@NH2-Uio-66(Zr) for the visible-light-promoted Suzuki coupling reaction was further confirmed by the XRD analyses, cycling tests and ICP analyses, which showed that only trace of Pd (99%) as compared to those with electron-donating ones (70.5%) (Entry 1-2, Table 2). This result is reasonable since the electron-withdrawing substituents lead to electron-deficient phenyl ring, which is easier for the nucleophilic attack by the photo-generated electrons on electron-rich Pd nanoclusters. On the contrary, phenylboronic acid with electron-donating

substituents

(>99%)

exhibited

higher

activity

than

electron-withdrawing ones (90.4%) (Entry 5-6, Table 2). Since the positive charge on NH2-Uio-66(Zr) is responsible for the activation of C-B bond, phenylboronic acid with the electron-donating substituents is much favorable to react with the positive NH2-Uio-66(Zr). Both meta-substituted iodobenzene and phenylboronic acid showed lower activity than those with ortho- and para-substituents, probably a consequence of both electronic effect and steric hindrance (Table 2). In addition to iodobenzene, the coupling between bromobenzene and phenylboronic

acid

can

also

be

effectively

realized

over

irradiated

Pd@NH2-Uio-66(Zr) in spite of the stronger C-Br bond as compared with C-I bond. A high bromobenzene conversion of 87.9% and a selectivity of 85.7% to biphenyl can be achieved after reacting for 2h (Entry 9, Table 2). This makes the current Pd@NH2-Uio-66(Zr) even attractive since in many cases the industry still relies on bromo derivatives due to their good cost/reactivity relationship. 11



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Conclusions In summary, Pd nanoclusters smaller than 1.2 nm have been successfully encapsulated inside the pores of NH2-Uio-66(Zr) via a double-solvent impregnation combined with a photo-reduction process. The resulting Pd@NH2-Uio-66(Zr) showed excellent activity for the visible-light-promoted Suzuki coupling reaction due to the presence of a large amount of coordinated unsaturated active catalytic Pd sites and the efficient electron transfer from the light-excited NH2-Uio-66(Zr) to the confined Pd nanoclusters. This work presents an effective and mild route for the development of metal@MOFs for efficient heterogeneous catalysis. The successful coupling of the MOFs-based photocatalysis with the metal-based catalysis over the Metal@MOFs is significant since the combination of the diversified MOFs with metal nanoparticles are anticipated to bring about almost infinite possibilities to develop

multifunctional

catalysts

for

various

light-induced

organic

transformations as considering the diversified structures of MOFs and their tunable characteristics. Supporting Information Available The N2 adsorption/desorption isotherm, XPS spectrum, TEM images and the cycling test of the samples. This material is available free of charge via the Internet at http://pubs.acs.org. Author Information *Author to whom all correspondences should be addressed. E-mail: [email protected] (Z. Li); Tel: +86 0591 83779260. Acknowledgements This work was supported by 973 Program (2014CB239303), NSFC (21273035), National Key Technologies R&D Program of China (2014BAC13B03), Specialized Research Fund for the Doctoral Program of Higher Education (20123514110002) and Independent Research Project of State Key Laboratory of Photocatalysis on Energy and Environment (NO. 2014A03).

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References [1] Turner, M.; Golovko, V. B.; Vaughan, O. P. H.; Abdulkin, P.; Berenguer-Murcia, A.; Tikhov, M. S.; Johnson B. F. G.; Lambert, R. M. Selective Oxidation with Dioxygen by Gold Nanoparticle Catalysts Derived From 55-Atom Clusters. Nature 2008, 454, 981-983. [2] Stratakis, M.; Garcia, H. Catalysis by Supported Gold Nanoparticles: beyond Aerobic Oxidative Processes. Chem. Rev. 2012, 112, 4469-4506. [3] White, R. J.; Luque, R.; Budarin, V. L.; Clark, J. H.; Macquarrie, D. J. Supported Metal Nanoparticles on Porous Materials. Methods and Applications. Chem. Soc. Rev. 2009, 38, 481-494. [4] Roucoux, A.; Schulz, J.; Patin, H. Reduced Transition Metal Colloids: a Novel Family of Reusable Catalysts? Chem. Rev. 2002, 102, 3757-3778. [5] Goesmann, H.; Feldmann, C. Nanoparticulate Functional Materials. Angew. Chem., Int. Ed. 2010, 49, 1362-1395. [6] Joo, S. H.; Choi, S. J.; Oh, I.; Kwak, J.; Liu, Z.; Terasaki, O.; Ryoo, R. Ordered Nanoporous Arrays of Carbon Supporting High Dispersions of Platinum Nanoparticles. Nature, 2001, 412, 169-172. [7] Song, H.; Rioux, R. M.; Hoefelmeyer, J. D.; Komor, R.; Niesz, K.; Grass, M.; Yang, P.; Somorjai, G. A. Hydrothermal Growth of Mesoporous SBA-15 Silica in the Presence of PVP-Stabilized Pt Nanoparticles: Synthesis, Characterization, and Catalytic Properties. J. Am. Chem. Soc. 2006, 128, 3027-3037. [8] Férey,G.; Serre, C.; Devic, T.; Maurin, G.; Jobic, H.; Llewellyn, P. L.; DeWeireld, G.; Vimont, A.; Daturi, M.; Chang, J.-S. Why Hybrid Porous Solids Capture Greenhouse Gases? Chem. Soc. Rev. 2011, 40, 550-562. [9] Li,J.-R.; Sculley, J.; Zhou, H.-C. Metal-Organic Frameworks for Separations. Chem. Rev. 2012, 112, 869-932. [10] Dhakshinamoorthy, A.; Asiri, A. M.; Garcia, H. Metal-Organic Frameworks Catalyzed C-C and C-Heteroatom Coupling Reactions. Chem. Soc. Rev. 2015, 44, 1922-1947. [11] Cui, Y.; Yue, Y.; Qian, G.; Chen, B. Luminescent Functional Metal-Organic Frameworks. Chem. Rev. 2012, 112, 1126-1162. [12] Cook, T. R.; Zheng, Y.-R.; Stang, P. J. Metal-Organic Frameworks and Self-Assembled Supramolecular Coordination Complexes: Comparing and

13



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 14 of 27

Contrasting the Design, Synthesis, and Functionality of Metal-Organic Materials. Chem. Rev. 2013, 113, 734-777. [13] Kitagawa, S.; Kitaura, R.; Noro, S. Functional Porous Coordination Polymers. Angew. Chem. Int. Ed. 2004, 43, 2334-2375. [14] Furukawa, H.; Müller, U.; Yaghi, O. M. “Heterogeneity within Order” in Metal-Organic Frameworks. Angew. Chem. Int. Ed. 2015, 54, 3417-3430. [15] Moon, H. R.; Limb, D.-W.; Suh, M. P. Fabrication of Metal Nanoparticles in Metal-Organic Frameworks. Chem. Soc. Rev. 2013, 42, 1807-1824. [16] Meilikhov, M.; Yusenko, K.; Esken, D.; Turner, S.; Tendeloo, G. V.; Fischer, R. A. Metals@MOFs-Loading MOFs with Metal Nanoparticles for Hybrid Functions. Eur. J. Inorg. Chem. 2010, 3701-3714. [17] Luan, Y.; Qi, Y.; Gao, H.; Zheng, N.; Wang, G. Synthesis of an Amino-Functionalized Metal-Organic Framework at a Nanoscale Level for Gold Nanoparticle Deposition and Catalysis. J. Mater. Chem. A 2014, 2, 20588-20596. [18] Doherty, C. M.; Buso, D.; Hill, A. J.; Furukawa, S.; Kitagawa, S.; Falcaro, P. Using Functional Nano-and Microparticles for the Preparation of Metal-Organic Framework Composites with Novel Properties. Accounts Chem. Res. 2014, 47, 396-405. [19] Zhang, W.; Lu, G.; Cui, C.; Liu, Y.; Li, S.; Yan, W.; Xing, C.; Chi, Y. R.; Yang, Y.; Huo, F. A Family of Metal-Organic Frameworks Exhibiting Size-Selective Catalysis with Encapsulated Noble-Metal Nanoparticles. Adv. Mater. 2014, 26, 4056-4060. [20] Li, X.; Guo, Z.; Xiao, C.; Goh, T. W.; Tesfagaber, D.; Huang, W. Tandem Catalysis

by

Palladium

Nanoclusters

Encapsulated

in

Metal-Organic

Fframeworks. ACS Catal. 2014, 4, 3490-3497. [21] Choi, K. M.; Na, K.; Somorjai, G. A.; Yaghi, O. M. Chemical Environment Control and Enhanced Catalytic Performance of Platinum Nanoparticles Embedded in Nanocrystalline Metal-Organic Frameworks. J. Am. Chem. Soc. 2015, 137, 7810-7816. [22] Yuan, B.; Pan, Y.; Li, Y.; Yin, B.; Jiang, H. A Highly Active Heterogeneous Palladium Catalyst for the Suzuki-Miyaura and Ullmann Coupling Reactions of Aryl Chlorides in Aqueous Media. Angew. Chem. Int. Ed. 2010, 49, 4054-4058. [23] Hu, P.; Morabito, J. V.; Tsung, C.-K. Core-Shell Catalysts of Metal Nanoparticle Core and Metal-Organic Framework Shell. ACS Catal. 2014, 4, 4409-4419. 14


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[24] Chen, Y.-Z.; Xu, Q.; Yu, S.-H.; Jiang, H.-L. Tiny Pd@Co Core-Shell Nanoparticles Confined inside a Metal-Organic Framework for Highly Efficient Catalysis. Small 2015, 11, 71-76. [25] Ke, F.; Zhu, J.; Qiu. L.-G.; Jiang, X. Controlled Synthesis of Novel Au@ MIL-100(Fe) Core-Shell Nanoparticles with Enhanced Catalytic Performance. Chem. Commun. 2013, 49, 1267-1269. [26] Liu, H.; Chang, L.; Chen, L.; Li, Y. In Situ One-Step Synthesis of Metal-Organic Framework Encapsulated Naked Pt Nanoparticles without Additional Reductants. J. Mater. Chem. A 2015, 3, 8028-8033. [27] Chen, Y.-Z.; Zhou, Y.-X.; Wang, H.; Lu, J.; Uchida, T.; Xu, Q.; Yu, S.-H.; Jiang H.-L. Multifunctional PdAg@MIL-101 for One-Pot Cascade Reactions: Combination of Host-Guest Cooperation and Bimetallic Synergy in Catalysis. ACS Catal. 2015, 5, 2062-2069. [28] Yang, Q.; Xu, Q.; Yu, S.-H.; Jiang, H.-L. Pd Nanocubes@ZIF-8: Integration of Plasmon-Driven Photothermal Conversion with a Metal-Organic Framework for Efficient and Selective Catalysis. Angew. Chem. Int. Ed. 2016, 55, 3685-3689. [29] Huang, G.; Yang, Q.; Xu, Q.; Yu, S.-H.; Jiang, H.-L. Polydimethylsiloxane Coating for a Palladium/MOF Composite: Highly Improved Catalytic Performance by Surface Hydrophobization. Angew. Chem. Int. Ed. 2016, 55, 7379-7383. [30] Aijaz, A.; Karkamkar, A.; Choi, Y. J.; Tsumori, N.; Ronnebro, E.; Autrey, T.; Shioyama, H.; Xu, Q. Immobilizing Highly Catalytically Active Pt Nanoparticles inside the Pores of Metal-Organic Framework: A Double Solvents Approach. J. Am. Chem. Soc. 2012, 134, 13926-13929. [31] Zhu, Q.-L.; Li, J.; Xu, Q. Immobilizing Metal Nanoparticles to Metal-Organic Frameworks with Size and Location Control for Optimizing Catalytic Performance. J. Am. Chem. Soc. 2013, 135, 10210-10213. [32] Cavka, J. H.; Jakobsen, S.; Olsbye, U.; Guillou, N.; Lamberti, C.; Bordiga, S.; Lillerud, K. P. A New Zirconium Inorganic Building Brick Forming Metal Organic Frameworks with Exceptional Stability. J. Am. Chem. Soc. 2008, 130, 13850-13851. [33] Li, X.; Guo, Z.; Xiao, C.; Goh, T. W.; Tesfagaber, D.; Huang, W. Tandem Catalysis

by

Palladium

Nanoclusters

Encapsulated

Frameworks. ACS Catal. 2014, 4, 3490-3497. 15


in

Metal-Organic


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 16 of 27

[34] Sun, D.; Fu, Y.; Liu, W.; Ye, L.; Wang, D.; Yang, L.; Fu, X.; Li, Z. Studies on Photocatalytic CO2 Reduction over NH2-Uio-66 (Zr) and Its Derivatives: Towards a Better Understanding of Photocatalysis on Metal-Organic Frameworks. Chem. Eur. J. 2013, 19, 14279-14285. [35] Miyaura, N.; Suzuki, A. Palladium-Catalyzed Cross-Coupling Reactions of Organoboron Compounds. Chem. Rev. 1995, 95, 2457-2483. [36] Buchwald, S. L. Cross Coupling. Acc. Chem. Res. 2008, 41, 1439-1439. [37] Suzuki, A. Recent Advances in the Cross-Coupling Reactions of Organoboron Derivatives with Organic Electrophiles, 1995-1998. J. Organomet. Chem. 1999, 576, 147-168. [38] Phan, N. T. S.; Van Der Sluys, M.; Jones, C. W. On the Nature of the Active Species

in

Palladium

Catalyzed

Mizoroki-Heck

and

Suzuki-Miyaura

Couplings-Homogeneous or Heterogeneous Catalysis, a Critical Review. Adv. Synth. Catal. 2006, 348, 609-679. [39] Fihri, A.; Bouhrara, M.; Nekoueishahraki, B.; Basset, J.-M.; Polshettiwar, V. Nanocatalysts for Suzuki Cross-Coupling Reactions. Chem. Soc. Rev. 2011, 40, 5181-5203. [40] Perez-Lorenzo, M. Palladium Nanoparticles as Efficient Catalysts for Suzuki Cross-Coupling Reactions. J. Phys. Chem. Lett. 2012, 3, 167-174. [41] Yin, L.; Liebscher, J. Carbon-Carbon Coupling Reactions Catalyzed by Heterogeneous Palladium Catalysts. Chem. Rev. 2007, 107, 133-173. [42] Leyva-Pérez, A.; Oliver-Meseguer, J.; Rubio-Marqués, P.; Corma, A. Water-Stabilized Three- and Four-Atom Palladium Clusters as Highly Active Catalytic Species in Ligand-Free C-C Cross-Coupling Reactions. Angew. Chem. Int. Ed. 2013, 52, 11554-11559. [43] Ellis, P. J.; Fairlamb, I. J. S.; Hackett, S. F. J.; Wilson, K.; Lee, A. F. Evidence for the Surface-Catalyzed Suzuki-Miyaura Reaction over Palladium Nanoparticles: An Operando XAS Study. Angew. Chem. Int. Ed. 2010, 49, 1820-1824. [44] Le Bars, J.; Specht, U.; Bradley, J. S.; Blackmond, D. G. A Catalytic Probe of the Surface of Colloidal Palladium Particles using Heck Coupling Reactions. Langmuir 1999, 15, 7621-7625. [45] Cotugno, P.; Monopoli, A.; Ciminale, F.; Ciofffi, N.; Nacci, A. Pd Nanoparticle Catalysed

One-Pot

Sequential

Heck

and

Suzuki

Couplings

of

Bromo-Chloroarenes in Ionic Liquids and Water. Org. Biomol. Chem. 2012, 10, 16


Page 17 of 27

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


808-813. [46] Li, X.; Baar, M.; Blechert, S.; Antonietti, M. Facilitating Room-Temperature Suzuki Coupling Reaction with Light: Mott-Schottky Photocatalyst for C-C-coupling. Sci. Rep. 2013, 3, 1743. [47] Jiao, Z.; Zhai, Z.; Guo, X.; Guo, X.-Y. Visible-Light-Driven Photocatalytic Suzuki-Miyaura Coupling Reaction on Mott-Schottky-type Pd/SiC Catalyst. J. Phys. Chem. C 2015, 119, 3238-3243. [48] Wang, Z. J.; Ghasimi, S.; Landfester, K.; Zhang, K. A. I. Photocatalytic Suzuki Coupling Reaction Using Conjugated Microporous Polymer with Immobilized Palladium Nanoparticles under Visible Light. Chem. Mater. 2015, 27, 1921-1924. [49] Tachikawa, T.; Choi, J. R.; Fujitsuka, M.; Majima, T. Photoinduced Charge-Transfer Processes on MOF-5 Nanoparticles: Elucidating Differences between Metal-Organic Frameworks and Semiconductor Metal Oxides. J. Phys. Chem. C 2008, 112, 14090-14101. [50] Llabrés i Xamena, F. X.; Corma. A.; Garcia, H. Applications for Metal-Organic Frameworks (MOFs) as Quantum Dot Semiconductors. J. Phys. Chem. C 2007, 111, 80-85. [51] Sun, D.; Liu, W.; Fu, Y.; Fang, Z.; Sun, F.; Fu, X.; Zhang, Y.; Li, Z. Noble Metals Can Have Different Effects on Photocatalysis Over Metal-Organic Frameworks (MOFs): A Case Study on M/NH2-MIL-125(Ti) (M=Pt and Au). Chem.-Eur. J. 2014, 20, 4780-4788. [52] Horiuchi, Y.; Toyao, T.; Saito, M.; Mochizuki, K.; Iwata, M.; Higashimura, H.; Anpo, M.; Matsuoka, M. Visible-Light-Promoted Photocatalytic Hydrogen Production by Using an Amino-Functionalized Ti(IV) Metal-Organic Framework. J. Phys. Chem. C 2012, 116, 20848-20853. [53] Wang, F.; Li, C. H.; Chen, H. J.; Jiang, R. B.; Sun, L. D.; Li, Q.; Wang, J. F.; Yu, J. C.; Yan, C. H. Plasmonic Harvesting of Light Energy for Suzuki Coupling Reactions. J. Am. Chem. Soc. 2013, 135, 5588-5601. [54] Wang, C.; deKrafft, K. E.; Lin, W. Pt Nanoparticles@Photoactive Metal-Organic Frameworks: Efficient Hydrogen Evolution via Synergistic Photoexcitation and Electron Injection. J. Am. Chem. Soc. 2012, 134, 7211-7214. [55] Sarina, S.; Zhu, H. Y.; Jaatinen, E.; Xiao, Q.; Liu, H. W.; Jia, J. F.; Chen, C.; Zhao, J. Enhancing Catalytic Performance of Palladium in Gold and Palladium 17



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Alloy Nanoparticles for Organic Synthesis Reactions through Visible Light Irradiation at Ambient Temperatures. J. Am. Chem. Soc. 2013, 135, 5793-5801. [56] Xiao, Q.; Sarina, S.; Jaatinen, E.; Jia, J.; Arnold, D. P.; Liuc, H.; Zhu, H. Efficient Photocatalytic Suzuki Cross-Coupling Reactions on Au-Pd Alloy Nanoparticles under Visible Light Irradiation. Green Chem. 2014, 16, 4272-4285. [57] Zhang, S.; Chang, C.; Huang, Z.; Ma, Y.; Gao, W.; Li, J.; Qu, Y. Visible-Light-Activated Suzuki-Miyaura Coupling Reactions of Aryl Chlorides over the Multifunctional Pd/Au/Porous Nanorods of CeO2 Catalysts. ACS Catal. 2015, 5, 6481-6488.

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Captions for Figures Figure 1 XRD patterns of the as-prepared NH2-Uio-66(Zr) and Pd@NH2-Uio-66(Zr). Figure 2 TEM image of Pd@NH2-Uio-66(Zr) (inset shows the size distribution of Pd nanoclusters in Pd@NH2-Uio-66(Zr)). Figure 3 (a) UV/Vis spectra of NH2-Uio-66(Zr) and Pd@NH2-Uio-66(Zr); (b) dependence of photocatalytic activity of Pd@NH2-Uio-66(Zr) for the Suzuki coupling reaction on the light intensity. Figure 4 (a) XRD patterns of Pd@NH2-Uio-66(Zr) before and after Suzuki coupling reaction; (b) cycling

test

on

Pd@NH2-Uio-66(Zr) for the

visible-light-promoted Suzuki coupling reaction between iodobenzene and benzeneboronic acid. Captions for Tables Table 1 Visible-light-promoted Suzuki coupling reaction between iodobenzene and benzeneboronic acid over Pd@NH2-Uio-66(Zr) under different conditions. Table 2 The scope of Suzuki coupling reactions over Pd@NH2-Uio-66(Zr) under visible light irradiations. Captions for Schemes Scheme 1 Proposed mechanism of the visible-light-promoted Suzuki coupling reaction over Pd@NH2-Uio-66(Zr).

19



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Figure 1

20


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Figure 2

21



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Figure 3

22


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Figure 4

23



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Table 1

Entry

Photocatalyst

Solvent

Irradiation

Time (min)

Conv. (%)

Sel. (%)

1

Pd@NH2-Uio-66(Zr)

DMF

√

30

0

-

2

Pd@NH2-Uio-66(Zr)

DMF/H2O

√

30

90.4

>99

3

Pd@NH2-Uio-66(Zr)

DMF/H2O

√

45

>99

>99

4

-

DMF/H2O

√

45

0

-

5

NH2-Uio-66(Zr)

DMF/H2O

√

45

0

-

6

Pd@NH2-Uio-66(Zr)

DMF/H2O

×

45

10.5

>99

7

Pd/NH2-Uio-66(Zr)

DMF/H2O

√

45

58.2

>99

8a

Pd@NH2-Uio-66(Zr)

DMF/H2O

√

300

>99

>99

Reaction condition: 5 mg of photocatalyst, 0.1 mmol of iodobenzene, 0.2 mmol of phenylboronic acid, 0.3 mmol of TEA, N2, 2.0 ml of DMF/H2O (1/1), visible light irradiations, reaction time is 45 min. a reaction was scaled up by a factor of 8. Reaction condition: 5 mg of photocatalyst, 0.8 mmol of iodobenzene, 1.6 mmol of phenylboronic acid, 2.4 mmol of TEA, N2, 16 ml of DMF/H2O (1/1), visible light irradiations, reaction time is 5 h.

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Table 2

Entry

X

R1

R2

Conv. (%)

Sel. (%)

1a

I

p-CF3

H

>99

>99

2a

I

p-CH3

H

70.5

>99

3a

I

o-CH3

H

79.5

>99

4

a

I

m-CH3

H

20.5

>99

5

a

I

H

p-F

90.4

>99

6a

I

H

p-CH3

>99

>99

7

a

I

H

o-CH3

>99

>99

8

a

I

H

m-CH3

63.1

>99

Br

H

H

87.9

85.7

9b a

Reaction condition: 5 mg of photocatalyst, 0.1 mmol of arylhalide, 0.2 mmol of phenylboronic acid or its derivates, 0.3 mmol of TEA, reaction time is 45 min. b The reaction time is 2 h.

25



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Scheme 1

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TOC graphic

By using the nanopores in NH2-Uio-66(Zr) as a template, highly active cavity encapsulated Pd nanoclusters was achieved for efficient visible-light-promoted Suzuki coupling reaction via a successful coupling with MOF-based photocatalysis.

27


Double-Solvent Method to Pd Nanoclusters Encapsulated inside the

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