Angewandte Chemie International Edition
10.1002/anie.201809530
COMMUNICATION
58
slow reaction to give the same products after 195 h (Figure S23).
1999, 121, 3214-3217; b) S. Bonanni, K. Aït-Mansour, W. Harbich, H.
Brune, J. Am. Chem. Soc. 2014, 136, 8702-8707; c) J. Ke, W. Zhu, Y.
Jiang, R. Si, Y.-J. Wang, S.-C. Li, C. Jin, H. Liu, W.-G. Song, C.-H. Yan,
Y.-W. Zhang, ACS Catal. 2015, 5, 5164-5173.
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
5
9
Because this yield exceeded the quantity expected from the
6
0
amount of TBHP added on a stoichiometric basis, it indicated th6a1t
6
2
[7] a) A. Sanchez, S. Abbet, U. Heiz, W.-D. Schneider, H. Häkkinen, R. N.
Barnett, U. Landman, J. Phys. Chem. A 1999, 103, 9573-9578; b) B. Yoon,
H. Häkkinen, U. Landman, A. S. Wörz, J.-M. Antonietti, S. Abbet, K. Judai,
U. Heiz, Science 2005, 307, 403-407; c) A. A. Herzing, C. J. Kiely, A. F.
Carley, P. Landon, G. J. Hutchings, Science 2008, 321, 1331-1335; d) Q.
He, S. J. Freakley, J. K. Edwards, A. F. Carley, A. Y. Borisevich, Y. Mineo,
M. Haruta, G. J. Hutchings, C. J. Kiely, Nat. Commun. 2016, 7, 12905.
[8] a) S. Vajda, M. J. Pellin, J. P. Greeley, C. L. Marshall, L. A. Curtiss, G. A.
Ballentine, J. W. Elam, S. Catillon-Mucherie, P. C. Redfern, F. Mehmood,
P. Zapol, Nat. Mater. 2009, 8, 213-216; b) L. Liu, U. Díaz, R. Arenal, G.
Agostini, P. Concepción, A. Corma, Nat. Mater. 2017, 16, 132-139.
[9] a) D. Astruc, E. Boisselier, C. Ornelas, Chem. Rev. 2010, 110, 1857-1959;
b) V. S. Myers, M. G. Weir, E. V. Carino, D. F. Yancey, S. Pande, R. M.
Crooks, Chem. Sci. 2011, 2, 1632-1646; c) D. A. Tomalia, S. N. Khanna,
Chem. Rev. 2016, 116, 2705-2774.
the TBHP functioned as a radical initiator while the Pt19 SNCs
6
3
provided catalytic activity during the toluene oxidation reaction6a4t
6
6
5
7
room temperature. To the best of our knowledge, this is the first
6
6
report of the primary C-H bond oxidation of toluene catalyzed by
heterogeneous catalysts at room temperature. The HAAD6F8-
6
9
STEM images of the subnano Pt19 particles after the reactions
7
0
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
showed a relatively constant mean diameter (0.9 ± 0.2 nm), whic7h1
7
7
2
4
was comparable to the size of the pristine catalyst particles.
7
3
These results indicate that the dendrimer-encapsulated Pt SNCs
during low-temperature oxidation retained their performanc7e5
7
6
despite the leaching and aggregation of the subnano platinum
7
7
[10] S. Hecht, J. M. J. Fréchet, Angew. Chem. Int. Ed. 2001, 40, 74-91; Angew.
Chem. 2001, 113, 76-94
particles on the carbon support.
We have demonstrated the synthesis of SNCs composed of
78
7
9
[11] Review: K. Yamamoto, T. Imaoka, Acc. Chem. Res. 2014, 47, 1127-1136.
[12] a) K. Yamamoto, T. Imaoka, W.-J. Chun, O. Enoki, H. Katoh, M. Takenaga,
A. Sonoi, Nat. Chem. 2009, 1, 397-402; b) T. Imaoka, H. Kitazawa, W.-J.
Chun, S. Omura, K. Albrecht, K. Yamamoto, J. Am. Chem. Soc. 2013, 135,
13089-13095; c) T. Imaoka, H. Kitazawa, W.-J. Chun, K. Yamamoto,
Angew. Chem. Int. Ed. 2015, 54, 9810-9815; Angew. Chem. 2015, 127,
9948-9953.
8
0
Cu, Ru, Rh, Pd, or Pt with finely tuned sizes, using a dendrimer
8
1
template. These materials showed exceptional catalytic activ8ity2
8
3
during aerobic oxidation compared to available nanocatalysts.
8
4
The less oxophilic Pt SNCs exhibited especially high cataly8tic5
8
8
6
8
[13] M. Takahashi, H. Koizumi, W.-J. Chun, M. Kori, T. Imaoka, K. Yamamoto,
Sci. Adv. 2017, 3, e1700101.
performance and unique selectivity for useful organic compounds
8
7
in the case of aerobic toluene oxidation. In particular, the Pt19 SNC
[14] L. Kesavan, R. Tiruvalam, M. H. Ab Rahim, M. I. bin Saiman, D. I. Enache,
R. L. Jenkins, N. Dimitratos, J. A. Lopez-Sanchez, S. H. Taylor, D. W.
Knight, C. J. Kiely, G. J. Hutchings, Science 2011, 331, 195-199.
[15] a) B. Fu, X. Zhu, G. Xiao, Appl. Cat. A: Gen. 2012, 415-416, 47-52; b) F.
Jiang, X. Zhu, B. Fu, J. Huang, G. Xiao, Chin. J. Cat. 2013, 34, 1683-1689;
c) W. Zhong, S. R. Kirk, D. Yin, Y. Li, R. Zou, L. Mao, G. Zou, Chem. Eng.
J. 2015, 280, 737-747; d) X. Wang, G. Wu, H. Liu, Q. Lin, Catalysis 2016
6, 14.
showed the highest performance among the Pt SNCs, 8in9
9
0
agreement with results previously reported on the basis of an
9
1
electrochemical study.[12c] This catalyst also demonstrated th9e2
9
9
3
5
capacity for sustained toluene oxidation at room temperature. A
9
4
size-dependent oxygen activation pathway was proposed on the
basis of the extended surface areas and irregular electro9n6 [16] a) R. W. J. Scott, H. Ye, R. R. Henriquez, R. M. Crooks, Chem. Mater.
9
7
2003, 15, 3873-3878; b) R. Ye, B. Yuan, J. Zhao, W. T. Ralston, C.-Y. Wu,
E. U. Barin, F. D. Toste, G. A. Somorjai, J. Am. Chem. Soc. 2016, 138,
8533-8537.
distributions for the SNCs, involving the formation of
a
9
8
hydroperoxide species on the surface via hydrogen abstractio9n9
1
00 [17] Although Ru 3d photoelectrons are typically analyzed by XPS because of
transfer. The development of a more detailed mechanism
1
1
1
1
1
01
the strong signals, 3p spectra were used in the present work to avoid
interference from carbon substrate. W. Wang, S. Guo, I. Lee, K. Ahmed,
J. Zhong, Z. Favors, F. Zaera, M. Ozkan, C. S. Ozkan, Sci. Rep. 2014, 4,
4452.
including theoretical considerations is currently in progress.
02
03
04
106
05 [18] A small CuO cluster was reduced during XPS analyses under ultra-high
3
3 Acknowledgements
vacuum. See also: C.-K. Wu, M. Yin, S. O’Brien, J. T. Koberstein, Chem.
Mater. 2006, 18, 6054-6058.
1
07
1
08 [19] Y. J. Lee, E.-K. Lee, S. Kim, R. M. Nieminen, Phys. Rev. Lett. 2001, 86,
3
3
3
3
3
3
4
4
5
6
7
8
9
0
This study was supported by JST ERATO Grant Numb1e0rs9
999-1002.
1
10 [20] D. M. Washecheck, E. J. Wucherer, L. F. Dahl, A. Ceriottl, G. Longoni, M.
JPMJER1503, Japan (to K.Y.) and Grant-in-Aid for Scientific
1
11
Manassero, M. Sansoni, P. Chini, J. Am. Chem. Soc. 1979, 101, 6110-
6112.
Research (S), KAKENHI 15H05757 (to K.Y.). The authors a1l1so2
1
13 [21] A. Staykov, T. Nishimi, K. Yoshizawa, T. Ishihara, J. Phys. Chem. C 2012,
thank Dr. K. Albrecht (Tokyo Institute of Technology) for the
1
14
116, 15992-16000.
preparation of dendrimer templates and our colleagues in the
1
15 [22] M. Boronat, A. Corma, Dalton Trans. 2010, 39, 8538-8546.
Suzukakedai Materials Analysis Division, Technical Departm1en1t6,
Tokyo Institute of Technology, for performing ICP analyses. 117
4
4
1
2
Keywords: dendrimers • platinum • nanoparticles • oxidation •
catalysts
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
References and Notes
[1] a) R. A. Sheldon, J. K. Kochi, Metal-catalyzed oxidations of organic
compounds; Academic Press: New York, 1981; b) N. Mizuno, Ed. Modern
heterogeneous oxidation catalysis: design, reactions and characterization;
Wiley-VCH: Weinheim, 2009.
[2] Y. Ishii, S. Sakaguchi, T. Iwahama, Adv. Synth. Catal. 2001 343, 393–427.
[3] a) E. C. Tyo, S. Vajda, Nat. Nanotechnol. 2015, 10, 577-588; b) Z. Luo, A.
W. Castleman, S. N. Khanna, Chem. Rev. 2016, 116, 14456-14492; c) L.
Liu, A. Corma, Chem. Rev. 2018, 118, 4981-5079.
[4] H. Guan, J. Lin, B. Qiao, X. Yang, L. Li, S. Miao, J. Liu, A. Wang, X. Wang,
T. Zhang, Angew. Chem. Int. Ed. 2016, 55, 2820-2824.
[5] a) W. E. Kaden, T. Wu, W. A. Kunkel, S. L. Anderson, Science 2009, 326,
826-829; b) M. Moseler, M. Walter, B. Yoon, U. Landman, V. Habibpour,
C. Harding, S. Kunz, U. Heiz, J. Am. Chem. Soc. 2012, 134, 7690-7699.
[6] a) U. Heiz, A. Sanchez, S. Abbet, W.-D. Schneider, J. Am. Chem. Soc.
This article is protected by copyright. All rights reserved.