Sugar-functionalized water-soluble cyclotriveratrylene derivatives: Preparation and interaction with fullerene

Article abstract of DOI:10.1021/jo202141a

Cyclotriveratrylene (CTV) has attracted much attention because of its good chemical stability, small cavity, stable conformation, and facile modification. In this article, two water-soluble CTV derivatives (CTV-G and CTV-L) functionalized by glucose and lactose residues were synthesized, respectively. Unexpectedly, sugar-bearing CTVs exhibit a distinct photoluminescence, which might be ascribed to the enhanced planar conformation of cyclotriveratrylene ring derived from the spatial effect of bulky branch groups. The interaction between the water-soluble CTV derivatives and C₆₀ was investigated in organic solvent and aqueous solution, which was further characterized by fluorescence spectra, ultraviolet-visible spectra, and Raman spectra. CTV-G can associate with C₆₀ to form supramolecular complex with 1:1 molar ratio (K_a = 1.38 × 10⁵ M^-1, 298 K). As for CTV-L, a similar complex with a lower association constant (K_a = 5.09 × 10⁴ M^-1, 298 K) can also be formed.

Full text of DOI:10.1021/jo202141a

Article
pubs.acs.org/joc
Sugar-Functionalized Water-Soluble Cyclotriveratrylene Derivatives:
Preparation and Interaction with Fullerene
Fen Yang,†,‡ Qi Chen,† Qian-Yi Cheng,† Chao-Guo Yan,*,‡ and Bao-Hang Han*,†
†National Center for Nanoscience and Technology, Beijing 100190, China
‡College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, China
S
* Supporting Information
ABSTRACT: Cyclotriveratrylene (CTV) has attracted much
attention because of its good chemical stability, small cavity,
stable conformation, and facile modification. In this article, two
water-soluble CTV derivatives (CTV-G and CTV-L)
functionalized by glucose and lactose residues were synthe-
sized, respectively. Unexpectedly, sugar-bearing CTVs exhibit a
distinct photoluminescence, which might be ascribed to the
enhanced planar conformation of cyclotriveratrylene ring
derived from the spatial effect of bulky branch groups. The interaction between the water-soluble CTV derivatives and C60
was investigated in organic solvent and aqueous solution, which was further characterized by fluorescence spectra, ultraviolet−
visible spectra, and Raman spectra. CTV-G can associate with C60 to form supramolecular complex with 1:1 molar ratio (Ka =
1.38 × 105 M−1, 298 K). As for CTV-L, a similar complex with a lower association constant (Ka = 5.09 × 104 M−1, 298 K) can
also be formed.
media, which, to some extent, hampers its biological
application. Thus, it is necessary to exploit water-soluble
macrocyclic host systems to improve the water-solubility of C60
by forming water-soluble supramolecular complexes. Cyclo-
dextrin or calixarene derivatives are of particular interest. γ-CD
has been used to dissolve C60 in water.18 Two CTV derivatives
containing peripheral triethyleneglycol chains also have an
ability to form water-soluble supramolecular complexes with
C60, which makes them interesting candidates for biological
applications.19
Sugar, as a multihydroxyl biological molecule, possesses good
water-solubility and biocompatibility.20 Introducing sugar to a
CTV platform can not only provide CTV with a good solubility
in water but also extend the cavity of CTV with appending
sugar chains, which would furnish a novel water-soluble host for
fullerene. In this article, two CTV-based glycoconjugates
(CTV-G and CTV-L, Figure 1) were first designed and
prepared smoothly through click reaction (Scheme 1). With an
extended cavity based on the basic CTV platform, the two
sugar-bearing CTVs show a good ability to form supra-
molecular complexes with C60 in both polar organic solvent and
aqueous solution. Supramolecular interaction between CTV
derivatives and C60 can be detected through fluorescence
spectra and ultraviolet spectra. The two water-soluble hosts for
C60 overcome the natural repulsion of fullerene for water and
show a promising potential in biological applications.
INTRODUCTION
■
Cyclotriveratrylene (CTV), discovered almost a century ago,
has attracted much attention due to its good chemical stability,
small cavity, stable conformation, and facile modification.1−5
Considering its bowl-shape conformation with a molecular
cavity, the application of CTV as a host molecule, especially as a
fullerene host, has been widely reported in recent years.6,7 CTV
and its derivatives are well-known to bind fullerenes both in
solution and in the solid state. Modification with appending
functional groups can extend side-arms to the upper rim on the
basic CTV platform, which expands the cavity effectively and
enhances the binding ability to C60 in solution. Therefore,
various cyclotriveratrylene derivatives with extended cavities
have been developed through versatile functionalizations. The
CTV-based receptor that has three 2-ureido-4-[1H]-pyrimidi-
none side-arms can form hydrogen-bonded self-assembled
capsules binding fullerenes inside,8,9 which was further applied
to the isolation of C70 and C84 from mixtures of fullerenes.
Attaching aromatic moieties of 2-[9-(1,3-dithiol-2-ylidene)-
anthracen-10(9H)-ylidene]-1,3-dithiole (exTTF) to the basic
CTV platform can afford another host exTTF-CTV, which
shows a very effective association with both C60 and C70.10
These derivatives form stable complexes with fullerenes in
organic solvent and can be used to purify fullerenes efficiently
from crude soot or fullerite mixtures.11,12
In the past decade, the applications of fullerenes have been
gradually extended to many other research fields, such as
pharmaceutical science and biological science.13−15 For
instance, fullerene derivatives were reported to be used in
photodynamic therapy16 or as inhibitors for the HIV-1
protease.17 However, fullerene is almost insoluble in aqueous
Received: October 29, 2011
Published: December 20, 2011
© 2011 American Chemical Society
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Figure 1. Chemical structures of CTV-L and CTV-G.
Scheme 1. Synthetic Routes to CTV-Based Glycoconjugates CTV-G and CTV-L
on the 13C NMR spectrum of the corresponding desired
intermediates, CTV-L-OAc and CTV-G-OAc (Supporting
Information). After entire removal of the acetyl group with
MeONa/MeOH, CTV-G and CTV-L can be obtained
quantitively (Scheme 1), which were further characterized by
1H NMR, 13C NMR, MS, and IR spectra (Figure S1,
Supporting Information). CTV-L-OAc and CTV-G-OAc, as
the protected sugar-bearing CTVs, are readily soluble in
common solvents, such as methylene chloride, chloroform, and
tetrahydrofuran but insoluble in methanol, ethanol, and water.
The solubility of the resulting glycoconjugates, CTV-G and
CTV-L, are different from their precursors, showing a good
solubility in DMF, DMSO, toluene−DMSO (1:1, v/v), and
water.
Optical Properties of Sugar-Bearing CTV. Both CTV-G
and CTV-L exhibit an absorption maximum peak nearly at 290
nm in toluene−DMSO (1:1, v/v) solution or in water,
respectively (Figure 2). Unexpectedly, CTV-G and CTV-L
also display an emission maximum peak at 368 nm in toluene−
DMSO (1:1, v/v) solution. In water medium, the emission
RESULTS AND DISCUSSION
■
Synthesis of Sugar-Bearing CTV Hosts: CTV-G and
CTV-L. The synthetic routes to sugar-bearing CTV are outlined
in Scheme 1. Using the known cyclotriveratrylene21−23 as the
starting material, cyclotricatechylene (CTC) can be obtained
through a classic demethylation method in a good yield by
treatment of CTV with BBr3 in anhydrous dichloromethane.
After exposure to propargyl bromide under basic condition, the
six phenolic hydroxyl groups of CTC were propargylated to
furnish CTV1, whose structure can be proved by signal peaks at
3284 and 2126 cm−1 in the IR spectrum (Figure S1, Supporting
Information) and chemical shifts at 78.9 ppm and 76.1 ppm in
the 13C NMR spectrum (Supporting Information), respectively.
Cu(I)-catalyzed azide/alkyne click ligation24 between CTV1
and azido-functionalized sugar derivatives (1 or 2) was chosen
to introduce six sugar groups into the CTV platform, owing to
the efficiently selective ligation and mild reaction condition
based on the click reaction. Formation of the triazole ring is
1
confirmed by the chemical shift nearly at 8.41 ppm in the H
NMR spectrum and the peaks nearly at 124.3 and 144.2 ppm
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Figure 3. Fluorescence spectra of CTV-G (5.0 × 10−6 mol L−1) in the
absence and presence of various concentrations of C60 in the toluene−
DMSO solution at room temperature (λex = 310 nm). The
concentrations of C60 ( × 10−6 mol L−1) are 0.0, 1.25, 2.5, 5.0, 10.0,
15.0, 20.0, and 25.0, respectively. The inset is the plot of [C60]−1 vs ΔI.
Figure 2. Fluorescence spectra of CTV-L and CTV-G in water and
toluene−DMSO (1:1, v/v) (λex = 310 nm).
peak shifts to 400 nm with a vibronic shoulder peak at 440 nm.
When the molecule is excited from the ground-state to the
excited-state, the polarity of the excited molecule is higher than
that of the ground one. Solvent with a higher polarity can
produce a better stabilizing effect on the excited molecule, and
then the energy for electron excitation becomes lower.25
Therefore, the obvious bathochromic/red shift in photo-
luminscence spectra of sugar-bearing CTV in high polarity
solvents was observed. The fluorescence in the region from 350
to 390 nm probably results from the formation of ground-state
dimer because of the interactions between the benzene rings
upon excitation26 or excimeric emission caused by the
interaction between the phenyl groups.27 As for sugar-bearing
CTV, besides the reasons aforementioned, the fluorescence
might be ascribed to the enhanced planar conformation of the
cyclotriveratrylene ring derived from the spatial effect of bulky
branch chains. When excited at 310 nm, the fluorescence
intensity of CTV is very low. For CTC and CTV1, their
fluorescence intensities are even nearly zero under the same
conditions (Figure S2, Supporting Information). After the
incorporation of six sugar groups into CTV platform, the
obtained sugar-bearing CTVs possess a distinct photo-
luminescence. Compared with CTV-G, the branched lactopyr-
anosyl chains of CTV-L are bulkier and make the CTV skeleton
more coplanar, and the fluorescence intensity is correspond-
ingly higher (Figure 2), considering the greater enhanced
planar conformation of cyclotriveratrylene ring.
Studies for Complexation between Sugar-Bearing
CTV and Fullerene. CTV and its derivatives are well-known
to bind fullerenes in solution and in the solid state. The binding
of C60 in solution is enhanced through the use of extended-
cavity CTV derivatives.1 Optical spectroscopy assays have
drawn much attention in the investigation of C60−CTVs
binding because they are highly sensitive, convenient, and cost-
effective. Supramolecular interaction between sugar-bearing
CTV and C60 was studied by spectrofluorometric titrations in
toluene−DMSO (1:1, v/v) at 25 °C. Both sugar-bearing CTV
and C60 are soluble in the cosolvent. Continuous changes were
observed in the fluorescence spectra of sugar-bearing CTV
upon successive additions of the fullerene to the host solution.
Upon the addition of C60 solution (0−25 mM), the
fluorescence intensity of CTV-G gradually decreased and was
significantly quenched by 80% when the concentration of C60 is
up to 25 mM (Figure 3). As mentioned above, the fluorescence
of sugar-bearing CTV might be ascribed to the enhanced planar
conformation of the cyclotriveratrylene ring derived from the
spatial effect of bulky sugar moieties. The enhanced planar
conformation of the cyclotriveratrylene ring makes the π-
electron delocalization and excitation much easier. As for the
ground-state C60, it possesses remarkable electron-acceptor
properties and is capable of accommodating as many as six
electrons in solution.28 When sugar-bearing CTV interacts with
C60, the photoinduced intermolecular electron transfer from
sugar-bearing CTV donors to C60 takes place and leads to the
fluorescence quenching of sugar-bearing CTV. Meanwhile, a 16
nm red-shift (from 370 to 386 nm) of its emission maximum
was observed, which might be attributed to further enhanced
planar conformation of the CTV part when binding with the
C60 or the aggregation of sugar-bearing CTV complexes
because of the increasing concentration of C60. On the basis
of the linear fitting of the plot of [C60]−1 vs ΔI, the complex
formed by host and C60 was in 1:1 ratio, and the association
constant Ka of host CTV-G with C60 in toluene−DMSO
solution is 1.38 × 105 M−1 at 298 K (R2 = 0.9966). Similar
fluorescence quenching was also observed for CTV-L in the
presence of different concentrations of C60 (Figure S3,
Supporting Information), which indicates that the C60−CTV-
L complexation possesses a relatively smaller association
constant estimated to be 5.09 × 104 M−1 (R2 = 0.9997).
Apparently, the CTV-G with shorter glucopyranosyl chains
forms a slightly more stable complex with C60, maybe because
the resulting cavity is more suitable to accommodate the
spherical C60 molecule. The bulkier lactopyranosyl chains result
in a shallower cavity of the CTV due to the steric effect. The
complexation between CTV-G and C60 can also be confirmed
by ultraviolet−visible (UV−vis) absorption spectrum. As
shown in Figure 4, C60 exhibits two absorption peaks nearly
at 284 and 335 nm, respectively, in toluene−DMSO (1:1, v/v)
solution. When the same amount of C60 was mixed with CTV-
G (C60/CTV-G = 1:2, molar ratio) under the same conditions,
the absorption peak of C60 at 284 nm shifted to 293 nm;
furthermore, the absorption intensity at 335 nm decreased
about 30%. The absorption peak of C60 at 284 nm shifted to
288 nm when it was mixed with CTV-L (C60/CTV-L = 1:2,
molar ratio) under the same conditions (Figure S4, Supporting
Information). The absorption intensity at 335 nm decreased
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complex, which proves that CTV-G can bind C60 in aqueous
solution to form a water-soluble complex. Similar results were
also found for C60−CTV-L ensemble. (Figure S5, Supporting
Information) The interaction of sugar-bearing CTV hosts with
C60 can be visually monitored by a color change of the
corresponding solutions. For instance, the aqueous solution of
CTV-G is almost colorless, but after addition of C60 and
followed by centrifugation, the color of aqueous C60−CTV-G
solution gradually changes into yellow (Figure 5). These novel
CTV hosts with peripheral sugar chains show their ability to
form water-soluble supramolecular complexes with C60. Sugar−
triazole cluster structure based on the bowl-shape CTV can
provide an internal cavity capable of encapsulating the
hydrophobic C60 guest, thus preventing the aggregation in an
aqueous solution due to the fullerene−fullerene interaction.
Multiple hydroxyl groups from sugar moieties make the
supramolecular complexes water-soluble. The hydrophobic
triazole groups and six-membered ring skeleton of sugars can
increase the hydrophobic and van der Waals interactions
between the inner surface of sugar-bearing CTV hosts and C60,
which are useful to enhance the major driving forces for the
formation of supramolecular complexes. Further study with
Raman spectra shows the existence of C60 in C60−CTV-G
complex, in which the featured peak at 1470 cm−1 was assigned
Figure 4. Absorption spectra of C60−CTV-G (C60: 2.5 μM; CTV-G:
5.0 μM), C60 (2.5 μM), and CTV-G (5.0 μM) in toluene−DMSO
(1:1, v/v).
about 16%, which also shows the relatively weaker interaction
in C60−CTV-L. On the basis of these data, not only the
complexation between sugar-bearing CTV and C60, but also the
energy transfer through the interaction can be proved
apparently.
Fullerenes exhibit interesting biological activities both in
vitro and in vivo due to their easy excitation by visible light and
the special properties of the resulting excited-states.19 However,
the low solubility of fullerenes in aqueous media appears to be a
major problem for their biological applications. Preparation of
water-soluble supramolecular complexes between CTV-based
host systems and fullerenes is a reliable strategy to overcome
the natural repulsion of fullerenes for water. The host−guest
interaction of sugar-bearing CTV hosts and C60 was
investigated in aqueous solution. Figure 5 shows the UV−vis
Figure 6. Raman spectra of C60−CTV-G, CTV-G, and C60.
to the totally symmetric pentagonal pinch mode of C60 (Figure
6).29
CONCLUSIONS
■
On the basis of macrocyclic host CTV, two water-soluble sugar-
bearing CTV derivatives (CTV-G and CTV-L) modified with
glucose and lactose were synthesized, respectively. Cu(I)-
catalyzed azide/alkyne click ligation efficiently facilitated the
preparation. Thanks to the enhanced planar conformation of
functionalized cyclotriveratrylene ring, sugar-bearing CTVs
exhibit distinct photoluminescence, which can be used to
conveniently detect their interaction with C60 through
spectrofluorometric titration. The supramolecular complexation
between the water-soluble CTV derivatives and C60 was
investigated in organic solvent and aqueous solution,
respectively, which were confirmed by fluorescence, UV−vis,
and Raman spectra. Both CTV-G and CTV-L can bind C60 to
form a supramolecular complex with 1:1 molar ratio (for CTV-
G, Ka = 1.38 × 105 M−1; for CTV-L, Ka = 5.09 × 104 M−1). The
Figure 5. Absorption spectra of aqueous C60−CTV-G and CTV-G
solution, and C60 in water. The concentration of CTV-G is 5.0 × 10−5
M. Inset A is the amplificatory spectra in the region from 320 to 550
nm, and inset B shows the colors of C60 in various solvents: (a) C60 in
toluene; (b) C60 in water after centrifugation; (c) CTV-G in water;
and (d) C60−CTV-G in water after centrifugation.
absorption spectra of C60, CTV-G, and C60−CTV-G complex,
respectively, in aqueous solution after centrifugation. As
expected, C60 has no absorption intensity because of its
insolubility in aqueous solution. However, in the presence of
CTV-G, a new absorption peak at 342 nm (characteristic signal
peak of C60 in UV−vis region) was observed for C60−CTV-G
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6H), 5.22−5.14 (m, 18H), 4.34 (t, J = 9.2 Hz, 6H), 4.26−4.20 (m,
3H), 4.14−4.02 (m, 12H), 3.52−3.49 (m, 3H), 2.07−1.49 (m, 72H);
13C NMR (DMSO-d6) δ (ppm) 170.5, 170.1, 169.9, 169.0, 146.9,
144.4, 144.2, 132.0, 124.1, 116.9, 87.1, 84.4, 72.7, 70.6, 68.0, 62.7, 62.5,
62.2, 56.6, 31.2, 20.9; IR v (cm−1) 2950 (w), 1758 (s), 1613 (w), 1507
(s), 1450 (w), 1372 (s), 1232 (s), 1102 (s), 1039 (s), 918 (m);
MALDI-TOF-MS calcd. for C123H144N18O60, 2833.88 (m/z), found
2832.40. Anal. Calcd for C123H144N18O60: C, 52.12; H, 5.12; N, 8.89.
Found: C, 52.35; H, 5.24; N, 8.75.
Synthesis of CTV-L. To a solution of CTV-L-OAc (150 mg, 0.023
mmol) in methanol−dichloromethane (2:1; 30 mL) was added a
solution of sodium methoxide in methanol (1.0 M) until the pH value
reached to 11. The reaction was stirred for 24 h at room temperature,
and the obtained suspension was then filtered and washed with
dichloromethane. A foamy product was obtained as a white solid after
purification on a Biogel P2 column (77 mg, 84%): 1H NMR (DMSO-
d6) δ (ppm) 8.43 (s, 6H), 7.39 (s, 6H), 5.64 (d, J = 9.2 Hz, 6H), 5.15
(s, 12H), 4.25 (d, J = 6.4 Hz, 6H), 3.87 (t, J = 8.4 Hz, 6H), 3.76−3.33
(m, 114H); 13C NMR (DMSO-d6) δ (ppm) 146.2, 142.7, 132.4, 124.2,
115.5, 115.4, 103.8, 87.0, 79.7, 77.8, 75.5, 75.1, 73.2, 71.7, 70.5, 68.1,
60.4, 30.7; MALDI-TOF-MS calcd. for C111H156N18O66, 2797.94 (m/
z), found 2820.88 (M + Na). Anal. Calcd for C111H156N18O66: C,
47.64; H, 5.62; N, 9.01. Found: C, 47.45; H, 5.70; N, 9.13.
host−guest interaction between sugar-bearing CTV and C60 in
aqueous solution will boost the potential biological applications
of C60.
EXPERIMENTAL SECTION
■
Materials and Characterization. All chemical reagents are
commercially available and used as received unless otherwise stated.
CTV was prepared from 1,2-dimethoxybenzene according to the
reported method.30−32 Azido-functionalized sugar derivatives (1 or 2)
were prepared according to reported methods.33,34 Ultrapure water
(18.2 MΩ cm) was purified with a Millipore purification system (Milli-
Q water).
The 1H NMR and 13C NMR spectra were recorded on a 400 M Hz
NMR spectrometer. UV−vis spectra were measured using a UV−vis−
NIR spectrophotometer and quartz cells with a 1 cm path length. The
fluorescence spectra were measured in a conventional cell with a 1 cm
path length at room temperature. Mass spectra were measured using a
MALDI TOF-MS or liquid chromatography−mass spectrometry
(LC−MS) with the ESI(+) technique. IR spectra were recorded in
KBr pellets using a FTIR spectrometer. Raman spectra were recorded
by dropping the sample solutions CTV-G or CTV-L onto a slide glass
or silicon wafer after air drying. C60 was tested in powder form on a
slide glass.
Synthesis of CTV-G. CTV-G was obtained as a foamy solid (84
Synthesis of CTV1.35 To a solution of CTC (0.366 g, 1 mmol) in
33 mL of acetonitrile were added potassium carbonate (1.656 g, 12.0
mmol) and propargyl bromide (6.0 mL, 6.0 mmol, 80% in toluene)
under a nitrogen atmosphere at room temperature. The reaction
mixture was refluxed overnight and then cooled down to room
temperature. The suspension was then filtered and washed with
acetonitrile. After the solvent of the filtrate was removed under
reduced pressure, the desired product was obtained as a light brown
solid. Further purification can be done by crystallization from the
mg, 87%) from CTV-G-OAc (150 mg, 0.053 mmol) according to the
1
same synthetic method for CTV-L: H NMR (DMSO-d6) δ (ppm)
8.37 (d, J = 6.4 Hz, 6H), 7.40 (s, 6H), 5.51 (d, J = 8.0 Hz, 6H), 5.15
(s, 12H), 3.98−3.92 (m, 32H), 3.44−3.40 (m, 12H), 3.22 (s, 6H); 13C
NMR (DMSO-d6) δ (ppm) 146.8, 143.3, 133.0, 124.8, 116.0, 88.0,
80.5, 77.4, 72.5, 70.0, 61.2, 31.2; ESI-MS (positive ions) calcd. for
C75H96N18O36, 1825.66 (m/z), found 1847.69 (M + Na+). Anal. Calcd
for C75H96N18O36: C, 49.34; H, 5.30; N, 13.81. Found: C, 49.50; H,
5.41; N, 13.93.
Studies of Sugar-Bearing CTV−C60 Interaction Based on
Spectrofluorometric Titration. A solution of CTV-G or CTV-L
was prepared in toluene−DMSO (1:1, v/v). Aliquots of C60 in the
same solvent were added to the solution. The final concentration of
CTV-G or CTV-L was 5 × 10−6 M. After each addition, the sample
was allowed to equilibrate for 2 h prior to recording a spectrum.
Additions of C60 were continued until no significant change in the
fluorescence signal was observed. The excitation wavelength was 310
nm and the emission scan ranged from 330 to 550 nm.
1
CHCl3/EtOH mixture (298 mg, yield 50.1%, mp 153−155 °C): H
NMR (CDCl3) δ (ppm) 7.04 (s, 6H, Ar−H), 4.72 (t, J = 2.8 Hz, 12H,
Ar−OCH2), 4.62 (d, J = 2.4 Hz, 3H, Ar−CH2−Ar), 3.58 (d, J = 13.6
Hz, 3H, Ar−CH2−Ar), 2.56 (t, J = 2.4 Hz, 6H, CCH); 13C NMR
(CDCl3) δ (ppm) 146.5, 133.3, 117.4, 78.9, 76.1, 57.4, 36.5, 31.0; IR v
(cm−1) 3284 (vs), 2925 (w), 2125 (w), 1610 (w), 1506 (s), 1456 (w),
1260 (s), 1194 (m), 1140 (m), 1088 (m), 1023 (w), 661 (s). Anal.
Calcd for C39H30O6: C, 78.77; H, 5.09; O, 16.14. Found: C, 78.55; H,
5.20; O, 16.29.
Preparation of Sugar-Bearing CTV−C60 Complexes in
Aqueous Solution. The aqueous solutions of sugar-bearing CTV−
C60 complexes were prepared by stirring an aqueous solution of CTV-
G or CTV-L (1.0 × 10−3 M) containing C60 solid (>99%) for 30 h.
After centrifugation, clear aqueous solutions containing sugar-bearing
CTV−C60 complex were obtained for further studies.
Synthesis of CTV-L-OAc. To the solution of CTV1 (100 mg,
0.168 mmol) and sugar derivative 1 (1.580 g, 2.39 mmol) in
tetrahydrofuran−water cosolvent (50 mL, v/v = 2/1) were added
sodium ascorbate (40 mg) and copper sulfate (30 mg). The
heterogeneous mixture was stirred vigorously in a dark room at 50−
60 °C until complete consumption of the reactants (on the basis of
TLC analysis). After removal of tetrahydrofuran under a reduced
pressure, the residue was dissolved in water (20 mL), and the product
was extracted with ethyl acetate (3 × 25 mL). The combined organic
layer was dried over anhydrous sodium sulfate and evaporated in
vacuo. The crude product was purified by column chromatography
using ethyl acetate/petroleum ether (5/1) as eluent to give the desired
product (520 mg, 68%) as an off-white solid: 1H NMR (DMSO-d6) δ
(ppm) 8.41 (d, J = 3.6 Hz, 6H), 7.26 (d, J = 5.6 Hz, 6H), 6.26 (d, J =
8.8 Hz, 6H), 5.51−5.43 (m, 12H), 5.25−5.12 (m, 30H), 4.89−4.81
(m, 12H), 4.37−4.33 (m, 3H), 4.27−4.20 (m, 12H), 4.05−4.00 (m,
24H), 3.45−3.42 (m, 3H), 2.11 (s, 18H), 2.01−1.98 (m, 90H), 1.90
(s, 18H); 13C NMR (DMSO-d6) δ (ppm) 170.5, 170.1, 169.9, 169.6,
146.9, 144.2, 144.0, 133.3, 132.1, 124.3, 117.0, 100.6, 84.2, 76.3, 75.0,
72.9, 70.9, 69.5, 67.6, 65.6, 62.7, 61.4, 58.0, 56.6, 55.3, 31.2, 20.9;
MALDI-TOF-MS calcd. for C195H240N18O108, 4563.39 (m/z), found
4563.50. Anal. Calcd for C195H240N18O108: C, 51.32; H, 5.30; N, 5.52.
Found: C, 51.51; H, 5.19; N, 5.65.
ASSOCIATED CONTENT
■
S
* Supporting Information
FTIR spectra of CTV1, CTV-G-OAc, and CTV-G; fluo-
rescence spectra of CTV, CTC, and CTV1; fluorescence
spectra of CTV-L in the absence and presence of various
concentrations of C60 in the toluene−DMSO solution; UV−vis
spectra of C60−CTV-L (2:1, molar ratio) in toluene−DMSO
(1:1, v/v); UV−vis spectra of spectra of CTV-L complex with
C60 in aqueous solution; Raman spectra of C60−CTV-L, CTV-
1
L, and C60; and H NMR, 13C NMR, and mass spectra of key
compounds. This material is available free of charge via the
Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Synthesis of CTV-G-OAc. CTV-G-OAc was obtained as an off-
■
white solid (544 mg, 71%) from sugar derivative 2 (0.753 g, 2.018
Corresponding Author
1
mmol) according to the same synthetic method for CTV-L-OAc: H
*E-mail: cgyan@yzu.edu.cn (C.-G.Y.); hanbh@nanoctr.cn (B.-
H.H.). Tel: +86 10 8254 5576 (B.-H.H.).
NMR (DMSO-d6) δ (ppm) 8.55 (d, J = 6.0 Hz), 7.25 (d, J = 4.0 Hz,
6H), 6.35 (d, J = 9.2 Hz, 6H), 5.67−5.64 (m, 6H), 5.56−5.51 (m,
975
dx.doi.org/10.1021/jo202141a | J. Org. Chem. 2012, 77, 971−976

The Journal of Organic Chemistry
Article
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Cyclotriveratrylene−[60]Fullerene Complexes with Potential for
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ACKNOWLEDGMENTS
■
This work is supported by the Ministry of Science and
Technology of China (National Basic Research Program, Grant
2011CB932500) and the National Science Foundation of
China (Grants 20972035 and 21002017).
V.; Holler, M.; Illescas, B. M.; Munoz, A.; Martín, N.; Rojo, J.;
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Vincent, S. P. Fullerene Sugar Balls. Chem. Commun. 2010, 46 (22),
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