Organic nanotubes assembled from isophthalamides and their application as templates to fabricate Pt nanotubes

Article abstract of DOI:10.1039/b900843h

A new class of organic nanotubes have been assembled from simple isophthalamide derivatives and their surface can be conveniently coated with Pt, which form new Pt nanotubes after the inside organic materials are removed with hot methanol.

Full text of DOI:10.1039/b900843h

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Organic nanotubes assembled from isophthalamides and their application
as templates to fabricate Pt nanotubesw
Yun-Xiang Xu, Xin Zhao,* Xi-Kui Jiang and Zhan-Ting Li*
Received (in Cambridge, UK) 14th January 2009, Accepted 8th May 2009
First published as an Advance Article on the web 8th June 2009
DOI: 10.1039/b900843h
A new class of organic nanotubes have been assembled from
simple isophthalamide derivatives and their surface can be
conveniently coated with Pt, which form new Pt nanotubes after
the inside organic materials are removed with hot methanol.
packed into bundles and their hollow nature was readily
evidenced by their open-ended features (Fig. 1(b)). The
nano-tubes formed by T2 also had a hexagonal cross section,
which was not observed for those of T1. The hollow nature of
the nanotubes was further confirmed by TEM, which showed
a clear contrast between their inner and outer areas (Fig. 1(e)
and (f)). The sizes and wall thickness of the nanotubes from
both compounds were concentration-dependent. Reducing the
concentration remarkably decreased the diameters of the
nanotubes (Fig. 1(c) and (d)). Therefore, the size of the new
organic nanotubes can be tuned readily by simply changing
the concentration of the initial solutions.
Tubular nanostructures have drawn considerable attention in
recent years because of their potential applications in sensors,
catalysis, gene and drug-delivery, biological separation and
transport. Since the first reports of carbon nanotubes in 19911
and inorganic nanotubes in 1992,2 numerous methods have
been developed for the preparation of various inorganic
nanotubes.3 Although several approaches have been reported
for assembling organic nanotubes from cyclic molecules,4
examples of using acyclic molecules for this purpose are
relatively limited.5 Among others, Pt-nanotubes are potentially
useful in studies in catalysis and electrochemistry,6 but their
preparations have been mainly limited to the inorganic
templates approach.7 We herein report the preparation of a
novel type of organic nanotubes through the self-assembly
of simple isophthalamide derivatives. In addition, the new
organic nanotubes have been successfully used as templates for
fabricating well-ordered Pt nanotubes.
Aromatic amides have a great tendency to form inter-
molecular CQOꢀ ꢀ ꢀHꢁN hydrogen bonds and to stack in
polar solvents. Therefore, it is reasonable to postulate that
the driving forces for the self-assembly of the nanotubes by T1
and T2 mainly came from these two interactions. The IR
spectra of the tubes, upon removal of the solvent under
reduced pressure, exhibited the N–H stretching vibrations at
o3380 cmꢁ1, which indicated that the NH units were involved
in the intermolecular H-bonding.9 The single-crystal X-ray
During our study of the self-assembly of aromatic amide
oligomers,8 we found that compounds T1 and T2 could
self-assemble into nano-scaled tubular structures. These well-
ordered organic nanotubes could be generated in methanol or
its mixtures with water or chloroform. The procedure is quite
simple. Compound T1 or T2 was dissolved in hot methanol.
The resulting clear solution was allowed to cool gradually to
room temperature and stand overnight to give the tubular
structures. SEM and TEM were employed to characterize the
morphologies of the assembled structures (Fig. 1). SEM
images clearly showed the tubular structures. The tubes were
State Key Lab of Bioorganic and Natural Products Chemistry,
Shanghai Institute of Organic Chemistry, Chinese Academy of
Sciences, 345 Lingling Lu, Shanghai 200032, China.
E-mail: xzhao@mail.sioc.ac.cn, ztli@mail.sioc.ac.cn;
Fax: 0086-21-64166128; Tel: 0086-21-54925023
w Electronic supplementary information (ESI) available: Experimental
details, synthesis and characterization, and additional TEM image and
XRD result. CCDC 715335. For ESI and crystallographic data in CIF
or other electronic format see DOI: 10.1039/b900843h
Fig. 1 SEM images of (a) T1 (10 mM), (b) T2 (28 mM), (c) T1
(0.58 mM) and (d) T2 (2.6 mM) and TEM images of (e) T1 (8.4 mM)
and (f) partial magnification of the former image. All the samples were
obtained from their solution in methanol.
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Fig. 2 The packing structure of T2 in the single crystal (along the
b axis), highlighting the dislocated feature of the stacking molecules
stabilized by hydrogen bonds. Please see ESIw for lengths and angles of
H-bonds.
structure of T2z also revealed that, in the solid state,
the molecules stacked with each other, with a torsion angle
of 601 (Fig. 2). The stacked aromatic rings had an
arylcentriod–arylcentriod distance of 3.45 A, which is typical for
the columnar stacking of aromatic amides.10 The stacking was
further stabilized by two pairs of intermolecular CQOꢀ ꢀ ꢀH–N
hydrogen bonds between each molecule and its two stacked
neighbours. The hydrogen bonds forced the stacked molecules
to dislocate slightly, which might play a role in the formation
of the tubular structures. The powder X-ray diffraction (XRD)
of the nanotubes of T2 also exhibited a stacking pattern that
was very similar to that calculated from the crystal structure,11
indicating that the molecules in the nanotubes adopted a
similar packing mode as that in the crystal structure (Fig. 3).
The XRD of the nanotubes of T1 displayed a similar pattern
as that of T2 for most peaks, suggesting that, to some
extent, their stacking patterns in the nanotubes were similar.
However, the XRD of the nanotubes of T1 also exhibited
several extra peaks (2y = 6.57, 8.09 and 24.49) (Fig. S1, ESIw),
which might be produced by the ordered stacking of its
benzyl unit.
Fig. 4 TEM images of Pt–organic nanotubes of T1 formed from
methanol–water solution at (a) 4.2 mM and (b) 0.5 mM. (c) SEM
image and (d) EDX spectrum of Pt–organic nanotubes, both of which
were obtained from a solution of T1 (0.5 mM) in methanol–water. The
copper peaks were generated from the copper support grid.
nanotubes are therefore potentially useful in templating the
fabrication of Pt nanotubes, if Pt(II) ions are anchored on their
surface through the weak metal ion–O or –N interactions and
further reduced to Pt(0) in situ. Based on this consideration,
we further studied the possibility of using organic nanotubes
of T1, which were found generally more stable than those of
T2, to template the growth of Pt nanotubes. The typical
process is as follows. To a solution of T1 (0.5–4.2 mM,
0.3 mL) in methanol and water (5 : 1, v/v) was added a
solution of K2PtCl4 in water (20 mM, 0.1 mL). The mixture
was stirred slowly for 5 min and then a solution of ascorbic
acid in water (0.15 M, 0.1 mL) added.13 The mixture was
gently shaken and the resulting homogeneous solution was
incubated at room temperature for 10 h. The solution turned
from light yellow (that of K2PtCl4) to black, indicating that
the salt was reduced to metal Pt(0).
It was reported that the N and O atoms of amides have a
high affinity towards Pt(II).12 The new O- and N-rich organic
The morphologies of the resulting materials were first
studied by TEM, which showed that Pt was coated on the
surface of the nanotubes (Fig. 4). The surface coverage
significantly depended on the amount of the added salt, even
though the salt was always used in excess. For example, at the
ratio of 1.6 : 1, the organic nanotubes were only partially
covered by the Pt particles (Fig. 4(a)). When the ratio was
increased to 13.3 : 1 by reducing the concentration of T1 from
4.2 to 0.5 mM, the surface of the organic nanotubes was
almost completely covered by the Pt nanoparticles, which
aggregated together to form new Pt–organic nanotubes of
micrometer length with diameters ranging from 100 to 500 nm
(Fig. 4(b)). Fig. 4(a) also indicated that the Pt nanoparticles
were formed on the outside of the organic nanotubes, from
which additional evidence came from SEM (Fig. 4(c)). It can
be seen that a layer of the Pt nanoparticles were packed on the
surface of the thickest organic tube, while its naked end clearly
showed that it was hollow. The formation of the Pt metal
was further confirmed by an energy dispersive X-ray (EDX)
experiment, which exhibited strong peaks of Pt (Fig. 4(d)).5e
The new Pt–organic hybrid nanotubes were stable over
weeks (Fig. S2, ESIw). Removal of the organic tubes from
Fig. 3 XRD patterns of (a) the nanotubes of T2 (top) and the
theoretical profile calculated from its X-ray crystallographic data
(bottom).
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Notes and references
z Crystal data for T2: C60H96N6O9, M = 1045.43, monoclinic, space
group P21/n, a = 14.1075(8), b = 20.1933(11), c = 23.5204(13) A,
b = 91.509(2)1, V = 6698.1(6) A3, T = 173(2) K, Z = 4,
Dc = 1.037 g cmꢁ3, m = 0.069 mmꢁ1, R1 = 0.0706, wR2 = 0.1812
(I 4 2s(I)), R1 = 0.1113, wR2 = 0.2335 (all data). Reflections
collected/unique: 75 209/ 11 753 (Rint = 0.0471), GOF = 1.903.
Disorders at the isobutyl were found.
1 S. Iijima, Nature, 1991, 354, 56.
2 R. Tenne, L. Margulis, M. Genut and G. Hodes, Nature, 1992,
360, 444.
3 (a) J. Sloan, A. I. Kirkland, J. L. Hutchison and M. L. H. Green,
Acc. Chem. Res., 2002, 35, 1054; (b) Y. Sun, B. Mayers and Y. Xia,
Adv. Mater., 2003, 15, 641; (c) Y. Xiong, B. T. Mayers and Y. Xia,
Chem. Commun., 2005, 5013; (d) C. N. R. Rao, A. Govindaraj and
S. R. C. Vivekchand, Annu. Rep. Prog. Chem., Sect. A: Inorg.
Chem., 2006, 102, 20; (e) C. N. R. Rao, S. R. C. Vivekchand,
K. Biswas and A. Govindaraj, Dalton Trans., 2007, 3728;
(f) K. S. Coleman, Annu. Rep. Prog. Chem., Sect. A: Inorg. Chem.,
2008, 104, 379.
Fig. 5 (a) TEM, (b) SEM and (c) high-resolution TEM images and
(d) EDX spectrum of Pt nanotubes, which were obtained after the
internal organic templates were removed with hot methanol.
4 For a review, see: D. T. Bong, T. D. Clark, J. R. Granja and
M. R. Ghadiri, Angew. Chem., Int. Ed., 2001, 40, 988.
5 (a) M. Reches and E. Gazit, Science, 2003, 300, 625; (b) L. Zhao,
W. Yang, G. Zhang, T. Zhai and J. Yao, Chem. Phys. Lett., 2003,
379, 479; (c) S. Hecht and A. Khan, Angew. Chem., Int. Ed., 2003,
42, 6021; (d) Z. Wang, C. J. Medforth and J. A. Shelnutt, J. Am.
Chem. Soc., 2004, 126, 15954; (e) Y. Song, S. R. Challa,
C. J. Medforth, Y. Qiu, R. K. Watt, D. P. Pena, J. E. Miller,
F. van Swol and J. A. Shelnutt, Chem. Commun., 2004, 1044;
(f) Y. S. Zhao, W. Yang, D. Xiao, X. Sheng, X. Yang, Z. Shuai,
Y. Luo and J. Yao, Chem. Mater., 2005, 17, 6430;
(g) G. D. Pantos, P. Pengo and J. K. M. Sanders, Angew. Chem.,
Int. Ed., 2007, 46, 194; (h) G. D. Pantos, J.-L. Wietor and J. K.
M. Sanders, Angew. Chem., Int. Ed., 2007, 46, 2238; (i) X. Zhang,
X. Zhang, W. Shi, X. Meng, C. Lee and S. Lee, Angew. Chem., Int.
Ed., 2007, 46, 1525; (j) N. Kameta, H. Minamikawa, M. Masuda,
G. Mizuno and T. Shimizu, Soft Matter, 2008, 4, 1681; (k) X. Yan,
Q. He, K. Wang, L. Duan, Y. Cui and J. Li, Angew. Chem., Int.
Ed., 2007, 46, 2431.
6 T. R. Ralth and M. P. Hogarth, Platinum Met. Rev., 2002, 46, 3.
7 (a) A. Takai, Y. Yamauchi and K. Kuroda, Chem. Commun., 2008,
4171; (b) X. Zhang, D. Dong, D. Li, T. Williams, H. Wang and
P. A. Webley, Electrochem. Commun., 2009, 11, 190; (c) C. Mu,
Y. Yu, R. Wang, K. Wu, D. Xu and G. Guo, Adv. Mater., 2004,
16, 1550; (d) Y.-G. Guo, J.-S. Hu, H.-M. Zhang, H.-P. Liang,
L.-J. Wan and C.-L. Bai, Adv. Mater., 2005, 17, 746; (e) B. Mayers,
X. Jiang, D. Sunderland, B. Cattle and Y. Xia, J. Am. Chem. Soc.,
2003, 125, 13364; (f) Z. Chen, M. Waje, W. Li and Y. Yan, Angew.
Chem., Int. Ed., 2007, 46, 4060; (g) S. Guo, S. Dong and E. Wang,
Chem.–Eur. J., 2008, 14, 4689; (h) Y. Bi and G. Lu, Electrochem.
Commun., 2009, 11, 45; (i) Z. Q. Tian, S. P. Jiang, Y. M. Liang and
P. K. Shen, J. Phys. Chem. B, 2006, 110, 5343. Chem.; (j) Y. Ding,
A. Mathur, M. Chen and J. Erlebacher, Angew. Chem., Int. Ed.,
2005, 44, 4002.
the Pt tubes was realized by simply immersing the hybrid tubes
in hot methanol (30 min) and then removing the solvent by
centrifugal purification. After repeating three times, T1 was
completely removed, as evidenced by the elemental analysis of
the resulting tubes, which showed that only Pt remained. Both
TEM and SEM supported that the tubular feature of Pt was
maintained after the organic templates were removed
(Fig. 5(a)–(c)). The new Pt nanotubes were also very stable
and the high-resolution TEM showed their hollow nature
(Fig. 5(c)), indicating that Pt existed as nanotubes with or
without the support of the organic templates. The EDX
spectrum of this tubular material was similar to that of the
above Pt–organic nanotubes (Fig. 5(d)).
In summary, we demonstrate that simple isophthalamide
derivatives can self-assemble in methanol to form new well-
ordered organic nanotubes through cooperative intermolecular
hydrogen bonding and stacking interaction. The new organic
nanotubes are good supporting materials to template the
formation of Pt nanotubes by efficient absorption of K2PtCl4
on their surface, followed by in situ reduction. While inorganic
template-based techniques, which usually need chemical
modifications, but can offer a high degree of control over
the pore size and the wall thickness have traditionally been
used to produce Pt-nanotube arrays,7a–i and peptide- or
surfactant-based templates been recently employed to generate
Pt-nanotubes with specific characteristics,14a,b the method
reported here provides an alternative approach that can
produce Pt-nanotubes with comparable quality. Given the
advantages of structural variety and ready modification of
small organic molecules, this strategy may offer great flexibility
for the construction of nanoscaled materials with various
morphologies and should be applicable for many other transition
metals. Currently we are investigating this potential.
8 Y.-X. Xu, G.-T. Wang, X. Zhao, X.-K. Jiang and Z.-T. Li,
Langmuir, 2009, 25, 2684.
9 A. C. Legon, Chem. Soc. Rev., 1990, 19, 197.
10 (a) K. Pieterse, P. A. Van. Hal, R. Kleppinger, J. A. J.
M. Vekemans, R. A. J. Janssen and E. W. Meijer, Chem. Mater.,
2001, 13, 2675; (b) S. Ito, M. Wehmeier, J. D. Brand, C. Kubel,
R. Epsch, J. P. Rabe and K. Mullen, Chem.–Eur. J., 2000, 6, 4327.
¨
11 M. Shirakawa, S. Kawano, N. Fujita, K. Sada and S. Shinkai,
J. Org. Chem., 2003, 68, 5037.
12 P. Tsiveriotis and N. Hadjiliadis, Coord. Chem. Rev., 1999, 192,
171.
13 (a) Z. Wang, Z. Li, C. J. Medforth and J. A. Shelnutt, J. Am.
Chem. Soc., 2007, 129, 2440; (b) R. M. Garcia, Y. Song,
R. M. Dorin, H. Wang, P. Li, Y. Qiu, F. van Swol and
J. A. Shelnutt, Chem. Commun., 2008, 2535.
14 (a) L. Yu, I. A. Banerjee and H. Matsui, J. Mater. Chem., 2004, 14,
739; (b) T. Kijima, T. Yoshimura, M. Uota, T. Ikeda, D. Fujikawa,
S. Mouri and S. Uoyama, Angew. Chem., Int. Ed., 2004, 43, 228.
The authors thank the National Science Foundation of
China (Nos. 20732007, 20621062, 20672137 and 20872167),
the National Basic Research Program (2007CB808001) and
the Chinese Academy of Sciences for financial support.
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This journal is The Royal Society of Chemistry 2009
4214 | Chem. Commun., 2009, 4212–4214