Self-Assembly and Characterization of Supramolecular [60]Fullerene-Containing 2,6-Diacylamidopyridine with Uracil Derivative by Hydrogen-Bonding Interaction

Article abstract of DOI:10.1021/ol025614i

matrix presented Novel, self-assembly systems of uracil, derivatives with organofullerene by a three-point hydrogen-bonding interaction were designed and established. The formation of hydrogen bonding was established by ¹H NMR studies in CDCl₃.

Full text of DOI:10.1021/ol025614i

ORGANIC
LETTERS
2
002
Vol. 4, No. 7
179-1182
Self-Assembly and Characterization of
Supramolecular [60]Fullerene-Containing
1
2
,6-Diacylamidopyridine with Uracil
Derivative by Hydrogen-Bonding
Interaction
Zhiqiang Shi, Yuliang Li,* Haofei Gong, Minghua Liu, Shengxiong Xiao,
Huibiao Liu, Hongmei Li, Shengqiang Xiao, and Daoben Zhu
Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences,
Beijing 100080, P. R. China
ylli@infoc3.icas.ac.cn
Received January 24, 2002
ABSTRACT
Novel self-assembly systems of uracil derivatives with organofullerene by a three-point hydrogen-bonding interaction were designed and
1
3
established. The formation of hydrogen bonding was established by H NMR studies in CDCl .
2
,3
6
There has been an increasing interest in design and self-
assembly of fullerene derivatives by hydrogen bonds into
one-, two-, and three-dimensional supramolecular architecture
as a result of their potential applications as new photoelectric
materials. Hydrogen bonds are essential for molecular
recognition and self-organization of molecules in supra-
molecular chemistry and have been used for the design of
various molecular aggregates in solid state or in solution.
Meanwhile, energy and electron-transfer processes have also
been investigated in the assembled supramolecular systems
through hydrogen bonds. Very recently, Guldi and Hum-
7
melen reported, respectively, the synthesis and photophysical
properties of the first quadruple hydrogen bonded fullerene
dimer.
We sought to develop a complementary strategy for the
synthesis of a donor system and an acceptor unit containing
[60]fullerene that would form a class of supramolecular
systems that were structurally different from previously
reported ones. Here we report the synthesis of new orga-
nofullerenes containing a 2,6-diacylamidopyridine unit and
self-assembly with a compound bearing the uracil moiety to
form a hydrogen-bonded supramolecular system (Scheme 1).
The donor and acceptor are linked by a three-point hydrogen
1
-5
(
1) Brienne, M. J.; Gabard, J.; Lehn, J. M.; Stibor, I. J. Chem. Soc.,
Chem. Commun. 1989, 1868.
2) Berg, A.; Shuali, Z.; Someda, M. A.; Levanon, H. J. Am. Chem.
Soc. 1999, 121, 7433.
3) Sessler, J. L.; Brown, C. T.; O’Connor, D.; Springs, S. L.; Wang,
R.; Sathiosatham, M.; Hirose, T. J. Org. Chem. 1998, 63, 7370.
4) Archer, E. A.; Goldberg, N. T.; Lynch, V.; Krische, M. J. J. Am.
Chem. Soc. 2000, 122, 5006.
5) Rebeck, J. J. Chem. Soc. ReV. 1996, 25, 255.
(
(
(6) Gonz a´ lez, J. J.; Gonz a´ lez, S.; Priego, E. M.; Luo, C.; Guldi, D. M.;
Mendoza, J.; Martin, N. Chem. Commun. 2001, 163.
(7) Rispens, M. T.; S a´ nchez, L.; Knol, J.; Hummelen, J. C. Chem.
Commun. 2001, 161.
(
(
1
0.1021/ol025614i CCC: $22.00 © 2002 American Chemical Society
Published on Web 03/03/2002

12
pioneered by the Wudl group. This methodology has proven
to be a simple and versatile method for synthesis of C60 dyads
Scheme 1a
1
3
systems. The condensation product 2 of uracil and 1-bro-
moundecane was obtained at ambient temperature. It is
expected that the introduction of long alkyl chain in 1 and 2
exceedingly enhances the solubility of the compounds in
organic solvents.
The addition of azides to C60 in this reaction proceeds via
intermediate triazolines, which rearrange to closed 1,2-aza-
bridged isomers as the major monoaddition product after
extrusion of N
2
. With high symmetry, the closed 1,2-aza-
bridged isomer keeps the framework of C60 well also, which
13
can be confirmed by the C NMR spectrum. Except for two
3
2
sp -C peaks that appear at δ 83.22 ppm, all other sp -C peaks
of C60 appear at a closed region of δ 149-140 ppm (Figure
1
).
a
(i) Thionyl chloride, 90°, 90%; (ii) 2,6-diaminopyridine, THF,
rt, 18 h, 94%; (iii) chloroacetanoyl chloride, THF, rt, 24 h, 82%;
iv) sodium azide, 10% water/ethanol, reflux, 24 h, 94%; (v) C60
chlorobenzene, reflux, 72 h, 21%; (vi) 1-bromoundecane, DMSO,
0°, 24 h, 70%.
Figure 1. The 13C NMR spectrum of compound 1.
(
,
4
Our evidence for the formation of hydrogen bonding self-
1
assembly came from H NMR spectroscopic studies. It is
well-known that the characteristic of the formation of a three-
point hydrogen bonding complex between the uracil and 2,6-
diaminopyridine groups is the downfield shifts for their
bond. The formation of hydrogen bonds between the uracil
and 2,6-diaminopyridine groups has proved to be an efficient
way to construct a supramolecular assembly.2,6
1
,5
amidic protons. Upon complexation of compound 2 by
compound 1, the imide proton signal undergoes a significant
downfield shift of several ppm in the NMR titration
experiment since the electron densities of the protons
involved in H-bonds are decreased and consequently their
NMR signals are shifted to lower magnetic fields.1 The
association constant of this three-point hydrogen bond is in
The synthesis of the organofullerene DAP-C60 (1) is
sketched in Scheme 1. The 2,6-diaminopyridine was mono-
amidated with lauroyl chloride, and then 2-amino-6-lauroyl-
8
aminopyridine was further amidated with chloroacetanoyl
chloride to afford 2-chloroacetanoylamino-6-lauroyl-
4,15
9
aminopyridine. Nucleophilic substitution of chloride with
sodium azide yielded 2-azidoacetanoylamino-6-lauroyl-
aminopyridine.10 The DAP-C6011 was prepared by reaction
of 2-azidoacetanoylamino-6-lauroylaminopyridine with 1
equiv of C60 in chlorobenzene under reflux, which relied on
-
1 5
a range of 300-600 M . The interaction of 1 with
1
compound 2 was investigated by H NMR spectroscopic
1
titrations carried out in chloroform-d. For the H NMR
studies, the concentration of the host was kept constant (3
mM) and the change in the chemical shift was followed as
the cycloaddition reaction of the azide group with C60
,
(
8) Select data for 2-amino-6-lauroylaminopyridine: 1H NMR (CDCl3,
ppm) δ 0.79 (t, J ) 6.6 Hz, 3H), 1.16 (m, 16H), 1.60 (m, 2H). 2.32 (t, J
7.5 Hz, 2H), 5.42 (bs, 2H, NH2), 6.30 (d, J ) 7.7 Hz, 1H), 7.40 (t, J )
(11) Select data for compound 1: 1H NMR (CDCl3, ppm) δ 0.87 (t, J )
6.5 Hz, 3H), 1.25 (m, 16H), 1.74 (m, 2H). 2.44 (t, J ) 7.4 Hz, 2H), 4.59
)
7
1
3
13
.7 Hz, 1H), 7.45 (d, J ) 7.7 Hz, 1H), 8.77 (bs, 1H); C NMR (CDCl3,
ppm) δ 172.5, 155.1, 147.7, 142.0, 104.6, 102.5, 37.7, 31.9, 29.6, 29.5,
(s, 2H), 7.84 (m, 1H), 8.03 (m, 2H), 9.86 (bs, 2H); C NMR (CDCl3, ppm)
δ 170.5, 164.3, 145.3, 144.9, 144.8, 144.6, 143.8, 143.2, 142.9, 142.1, 141.6,
106.6, 105.8, 83.3, 37.8, 31.9, 29.7, 29.6, 29.5, 29.4, 29.4, 29.3, 29.2, 25.3,
22.7, 14.2; MS 1067 (M + 1).
+
2
9.3, 29.2, 25.2, 22.7, 14.1; EI-MS 291 (M ).
9) Select data for 2-chloroacetanoylamino-6-lauroylaminopyridine: 1
NMR (CDCl3, ppm) δ 0.90 (t, J ) 6.6 Hz, 3H), 1.24 (m, 16H), 1.73 (m,
(
H
(12) Prato, M.; Li, Q.; Wudl, F.; Lucchini, V. J. Am. Chem. Soc. 1993,
115, 1148.
2
(
H). 2.40 (t, J ) 7.5 Hz, 2H), 4.21 (s, 2H), 7.78 (t, J ) 7.7 Hz, 1H), 7.85
13
1
d, J ) 7.7 Hz, 1H), 7.97 (d, J ) 7.7 Hz, 1H), 8.83 (bs, 2H); C NMR
(13) Select data for compound 2: H NMR (CDCl3, ppm) δ 0.88 (t, 6
(
3
CDCl3, ppm) δ 171.3, 164.1, 148.3, 146.6, 140.2, 109.2, 108.1, 44.8, 41.7,
Hz, 3H), 1.26 (m, 16H), 1.68 (m, 4H), 3.72 (t, 7.4 Hz 2H), 5.70 (d, 8.2 Hz,
+
13
6.7, 30.9, 28.6, 28.4, 28.3, 28.1, 24.2, 21.6, 13.1; EI-MS 367 (M ).
1H), 7.14 (d, 8.2 Hz, 1H), 9.11 (bs, 1H); C NMR (CDCl3, ppm) δ 163.9,
1
(
10) Select data for 2-azidoacetanoylamino-6-lauroylaminopyridine: H
NMR (CDCl3, ppm) δ 0.91(t, J ) 6.6 Hz, 3H), 1.25 (m, 16H), 1.72 (m,
H). 2.38 (t, J ) 7.5 Hz, 2H), 4.16 (s, 2H), 7.64 (bs, 1H), 7.72 (t, J ) 7.7
150.9, 144.5, 102.1, 48.9, 31.9, 29.6 (2C), 29.5, 29.4, 29.3, 29.52, 29.1,
26.4, 22.7, 14.1; FAB-MS 281 (M + 1).
2
(14) Schuster, P.; Zundel, G.; Sandorfy, C. The Hydrogen Bond: Recent
DeVelopments in Theory and Experiments; North-Holland: Amsterdam,
1976; Vols. 1-3.
Hz, 1H), 7.95 (d, J ) 7.7 Hz, 1H), 7.79 (d, J ) 7.7 Hz, 1H), 8.39 (bs, 1H);
13
C NMR (CDCl3, ppm) δ 169.9, 163.1, 147.7, 146.3, 139.2, 108.3, 107.5,
1.0, 35.9, 30.0, 27.7, 27.5, 27.4, 27.3, 27.1, 23.4, 23.2, 20.8, 12.2; EI-MS
46 (M - 28).
5
3
(15) Konrat, R.; Tollinger, M.; Kontaxis, G.; Kraufler, B. Monatsh. Chem.
1999, 130, 961.
1180
Org. Lett., Vol. 4, No. 7, 2002

a function of increasing guest concentration. The NMR
titration experiments reveal a significant downfield shift of
the amidic proton signal due to melamine complexation
(Figure 2). Therefore, hydrogen-bond-mediated complex
Figure 4. The absorption spectra of the 1-2 system in chloroform.
Considering the self-assembling behavior of 1 with 2 in
organic solvents, it can be assumed that they will construct
three-dimensional superstructures that are stabilized by
intermolecular hydrogen bonding through uracil group and
1
Figure 2. Partial H NMR spectra of 1-2 supramolecular systems
2
,6-diaminopyridine moiety and chain interaction. In fact,
3
in different concentration ratio in CDCl at room temperature.
the self-assembled balls of 1 with 2 could be observed in
field emission scanning electron microscopy (FESEM)
images. Figure 4 shows the FESEM and the size distribution
histograms of the assemblies result from the solutions of the
formation could be unambiguously demonstrated in chloro-
form. Specifically, as illustrated in Figure 3, analysis of the
-
5
1
-2 system in chloroform/hexane (10 M).
The assemblies formed are in the range of 20-115 nm
the average size is 45 nm) for the 1-2 system. The size
(
Figure 3. 1H NMR binding isotherm for 1 with 2 in CDCl
at
3
room temperature. The concentration of 1 was kept constant at 3
mmol/L.
downfield shift for the amidic proton as a function of
increasing concentration of 1 provided support for a 1:1
binding model and yielded an association constant of K )
a
-
1 16
3
23 ( 45 M . This result showed that hydrogen bonding
took place between 1 and 2, and these assembly motifs
exhibit a significantly high stability.
As shown in the UV-vis spectra (Figure 4), the formation
of the 1-2 supramolecular system lead to an obvious blue
shift of compound 2 by 7 nm in chloroform. This change of
the small molecule 2 in electronic transition cannot be
explained by the formation of hydrogen bonds alone but
suggests additional contributions resulting from the influence
of the redox-active chromophore of C60 through the hydrogen
bonds.
Figure 5. FESEM image and size distribution histogram of
assemblies resulting from 10 M 1-2 in chloroform/hexane.
-
5
(16) Kr a´ l, V.; Furuta, H.; Shreder, K.; Lynch, V.; Sessler, J. L. J. Am.
Chem. Soc. 1996, 118, 1595.
Org. Lett., Vol. 4, No. 7, 2002
1181

distribution is broad, showing strong structure factors cor-
responding to the stacking of forming hydrogen-bond-
directed arrangement of 1 with 2. From the fact that the
diameter of the smallest ball in Figure 5 is about 20 nm, we
presume that the superstructures of the ballslike assemblies
are constructed from the numerous molecules of 1 with 2
by intermolecular hydrogen bonding and π-π interaction.
In conclusion, the self-assembly of the hydrogen-bonded
ball-like structure of a uracil derivative with organofullerene
can be used to design new supramolecular systems based
on [60]fullerene. The possibility of producing a well-defined
supramolecular structure like the ball presented here could
be of interest for the construction of three-dimensional
nanomaterials for future applications as photoelectric devices.
Acknowledgment. This work was supported by the Major
State Basic Research Development Program and the National
Natural Science Foundation of China (20151002, 90101025).
OL025614I
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Org. Lett., Vol. 4, No. 7, 2002