methanol (1 mL) and retrieved by the centrifugation. The crude
CH Cl (2 mL) was treated with benzaldehyde (0.4 mmol), 3,5-
2 2
Mn@SiO s were purified by repeating the re-dispersion in
2
bis(benzyloxy)benzaldehyde
trimethylsilane (3 equiv., 1.2 mmol) at room temperature under
atmosphere. The NMR spectrum collected at regular inter-
vals to determine the conversion yields.
(0.4
mmol)
and
cyano-
ethanol and the centrifugation for several times. The purified
Mn@SiO
further use. For the synthesis of HMON@h-SiO
Mn@SiO nanoparticles was treated with 0.5 M NH
tions at room temperature for 16 h. The resulting HMON@h-
SiO nanoparticles were isolated from the reaction dispersion by
the centrifugation and purified by repeating the re-dispersion in
water and the centrifugation. The Mn @p-SiO used for the
control catalytic reaction was prepared by using the Mn O
2
s were re-dispersed in deionized water and stored for
N
2
ꢀ1
2
, 1 mg mL of
OH solu-
2
2
4
Conclusions
2
In conclusion, a novel selective nanoscale etching process that
generated a well defined hollow nanostructure provides a novel
method for fabricating a nanoreactor framework consisting of
a hollow and porous silica shell and a functionalized interior
surface with a catalytically active manganese oxide layer.
Furthermore, the nanoreactor fabricated by the newly developed
method catalyzes the cyanosilylation reactions with size and
shape selectivity, and the size-selectivity effect can be enhanced
significantly by engineering the surface of the silica shell.
O
3 4
2
3
4
nanoparticle instead of MnO nanoparticle through the same
procedure with that applied for the HMON@h-SiO2.
Determination of solubility of bulk MnO and Mn O . 2 mg of
3
4
bulk MnO (Aldrich, ꢂ60 mesh, 99%) and Mn
mesh, 99%) powders were individually immersed in 2.5 M
NH OH solutions and stirred at room temperature. After
3 4
O (Aldrich, 325
2
stirring for 24 h, remaining solids were removed by the centri-
fugation. And the contents of manganese ions were determined
by using ICP.
Acknowledgements
This research was supported by Basic Science Research Program
through the National Research Foundation of Korea funded by
the Ministry of Education, Science and Technology (2010-
0003950) (ISL) and (2009-0069496) (EJK).
Surface modification of HMON@h-SiO
2
. The surface modifi-
cation of HMON@h-SiO was carried out with several silane
2
17
surfactants by modifying the previously reported method. For
this, four different silane reagents, including (3-amino-
propyl)trimethoxysilane, n-propyltrimethoxysilane, (2-phenyl-
ethyl)trimethoxysilane, and n-octadecyltrimethoxysilane, were
used. In a typical modification experiment, an ammonium
hydroxide solution (30%, 0.45 mL) and a silane reagent (2 mL)
were successively added to an ethanol dispersion (30 mL) of
Notes and references
1
For recent reviews on hollow nanoparticles, see: X. W. Lou,
L. A. Archer and Z. Yang, Adv. Mater., 2008, 20, 3987.
2
(a) J. Shin, R. M. Anisur, M. K. Ko, G. H. Im, J. H. Lee and I. S. Lee,
Angew. Chem., Int. Ed., 2009, 48, 321; (b) K. Cheng, S. Peng, C. Xu
and S. Sun, J. Am. Chem. Soc., 2009, 131, 10637; (c) X. W. Lou
and L. A. Archer, Adv. Mater., 2008, 20, 1853; (d) J. Gao,
G. Liang, B. Zhang, Y. Kuang, X. Zhang and B. Xu, J. Am. Chem.
Soc., 2007, 129, 1428; (e) P. M. Arnal, M. Comotti and F. Sch u€ th,
Angew. Chem., Int. Ed., 2006, 45, 8224.
HMON@h-SiO
significant change in the size and shape of the initial HMON@-
h-SiO after the silane modification. While the 3-aminopropyl-,
2
s (100 mg). TEM analyses did not show any
2
n-propyl-, and 2-phenylethyl-modified particles are well
dispersible in ethanol or ethanol/water mixture solvent, n-octa-
decyl-modified particles show much better dispersibility in
chloroform compared with ethanol or ethanol/water mixture.
3 For synthesis using sacrificial template, see: X. Huang, H. Zhang,
C. Guo, Z. Zhou and N. Zheng, Angew. Chem., Int. Ed., 2009, 48,
4
808; C.-J. Jia, L.-D. Sun, F. Luo, X.-D. Han, L. J. Heyderman,
Z.-G. Yan, C.-H. Yan, K. Zheng, Z. Zhang, M. Takano,
N. Hayashi, M. Eltschka, M. K €a lui, U. R u€ diger, T. Kasama,
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3.2 Evaluation of catalytic activities of HMON@h-SiO
cyanosilylation reactions
2
in
General procedure for cyanosilylation reactions. HMON@-
h-SiO (1) or modified HMON@h-SiO catalysts (2a–d) (0.025
2
2
mmol) dispersed in distilled CH Cl (2 mL) were treated with
2
2
aromatic aldehyde (0.5 mmol) and cyanotrimethylsilane
0.13 mL, 1.0 mmol) at room temperature under N atmosphere.
(
2
4
For template-free synthesis, see: (a) X. Liang, X. Wang, Y. Zhuang,
B. Xu, S. Kuang and Y. Li, J. Am. Chem. Soc., 2008, 130, 2736; (b)
S. Peng and S. Sun, Angew. Chem., Int. Ed., 2007, 46, 4155; (c)
A. E. Henkes, Y. Vasquez and R. E. Schaak, J. Am. Chem. Soc.,
After stirring for 12 h, the reaction mixture was filtered through
a plunge of Celite and the filtrate was concentrated under
1
reduced pressure to afford the product sample for H NMR
2
007, 129, 1896; (d) J. Gao, B. Zhang, X. Zhang and B. Xu, Angew.
analysis. The conversion yields of the reactions were determined
1
by H NMR spectroscopy, and were calculated based on the
Chem., Int. Ed., 2006, 45, 1220; (e) Y. Yin, R. M. Rioux,
C. K. Erdonmez, S. Hughes, G. A. Somorjai and A. P. Alivisatos,
Science, 2004, 304, 711.
5 S. H. Joo, J. Y. Park, C.-K. Tsung, Y. Yamada, P. Yang and
G. A. Somorjai, Nat. Mater., 2009, 8, 126; J. Lee, J. C. Park and
H. Song, Adv. Mater., 2008, 20, 1523; S. Ikeda, S. Ishino,
T. Harada, N. Okamoto, T. Sakata, H. Mori, S. Kuwabata,
T. Torimoto and M. Matsumura, Angew. Chem., Int. Ed., 2006, 45,
following representative peaks of aldehyde (ArCHO) and
1
cyanohydrins trimethylsilyl ether (ArCHCN(OTMS)). H NMR
(
300 MHz, CDCl ) ppm: 10.02 (3a) and 5.50 (4a), 10.08 (3b) and
3
5
.57 (4b), 10.42 (3c) and 6.06 (4c), 10.81 (3d) and 6.35 (4d), 11.55
(
3e) and 6.93 (4e), 9.89 (3f) and 5.39 (4f).
7
063; J. Li and H. C. Zeng, Angew. Chem., Int. Ed., 2005, 44, 4342.
6
For recent review on engineering of hollow interior space, see:
Y. Zhao and L. Jiang, Adv. Mater., 2009, 21, 3621; U. Jeong,
Y. Wang, M. Ibisate and Y. Xia, Adv. Funct. Mater., 2005, 15, 1907.
Competitive cyanosilylation reaction. n-Octadecyl-modified
HMON@h-SiO
2
catalyst (2d) (0.02 mmol) dispersed in distilled
1
0620 | J. Mater. Chem., 2010, 20, 10615–10621
This journal is ª The Royal Society of Chemistry 2010