Multistimuli responsive micelles formed by a tetrathiafulvalene- functionalized amphiphile

Article abstract of DOI:10.1021/la201699t

An electroactive tetrathiafulvalene (TTF)-functionalized amphiphile 1 was designed and synthesized to investigate its self-assembling behavior in water. Dynamic light scattering (DLS), ¹H NMR, fluorescence spectrum, and cryogenic transmission electron microscopy (cryo-TEM) studies revealed that amphiphile 1 can form micelle-like aggregates via direct dissolution into water, and the micellar architectures could be disrupted either by addition of chemical oxidant Fe(ClO₄)₃ or by complexation with electron-deficient cyclobis(paraquat-p-phenylene) tetracation cyclophane (CBPQT⁴⁺) to release encapsulated hydrophobic dye Nile Red from the interior of micelles.

Full text of DOI:10.1021/la201699t

ARTICLE
pubs.acs.org/Langmuir
Multistimuli Responsive Micelles Formed by a
Tetrathiafulvalene-Functionalized Amphiphile
Xiao-Jun Wang, Ling-Bao Xing, Feng Wang, Ge-Xia Wang, Bin Chen, Chen-Ho Tung, and Li-Zhu Wu*
Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry & Graduate University,
Chinese Academy of Sciences, Beijing 100190, P. R. China
S Supporting Information
b
ABSTRACT:
An electroactive tetrathiafulvalene (TTF)-functionalized amphiphile 1 was designed and synthesized to investigate its self-
1
assembling behavior in water. Dynamic light scattering (DLS), H NMR, fluorescence spectrum, and cryogenic transmission
electron microscopy (cryo-TEM) studies revealed that amphiphile 1 can form micelle-like aggregates via direct dissolution into
water, and the micellar architectures could be disrupted either by addition of chemical oxidant Fe(ClO4)3 or by complexation with
electron-deficient cyclobis(paraquat-p-phenylene) tetracation cyclophane (CBPQT4þ) to release encapsulated hydrophobic dye
Nile Red from the interior of micelles.
’ INTRODUCTION
Becher and Bryce realized that πꢀπ stacking and hydrogen-
bonding interactions were effective in building supramolecular
stacks.7 Recently, hydrogen-bonding and/or intermolecular πꢀπ
stacking interactions have been employed to establish well-defined
nanostructures of organic molecules containing the TTF unit.8
Specifically, Zhang and co-workers utilized the unique redox proper-
ties of TTF moiety to tune the gelꢀsol transition behaviors by oxida-
tion and reduction as well as by reactions with electron acceptors.9
Zhao and Li reported the first self-assembling vesicles from TTF
derivatives in organic solvents.10
In the present work, we wish to report a TTF-functionalized
amphiphile 1 bearing p-phenyleneethynyleneꢀTTF as a hydropho-
bic moiety and three triethylene glycol (TEG) monomethyl ether
chains as hydrophilic tails (Scheme 1). Compared with TTF end-
functionalized poly(N-isopropylacrylamide) amphiphilic polymer11
described by Cooke and Woisel very recently, such a small molecular
weight amphiphile12 simplifies the synthesis remarkably and has a
well-defined structure. We envision that amphiphile 1 would assem-
bly in water and respond to the applied stimuli, analogous to those
Amphiphilic ensembles, namely those that carry both hydro-
philic and hydrophobic segments in a determined proportion, can
spontaneously self-assembly in solutions or at interfaces to generate a
variety of well-defined nano- or microscopic architectures, such as
micelles, vesicles, nanotubes, fibers, and rods.1 The incorporation of
stimuli-responsive functional groups into these building blocks is
of particular significance to engineer “smart” systems for use in
optoelectronic materials, drug or gene delivery, and template syn-
thesis.2ꢀ4 In general, these responsive self-assembling processes can
be achieved by tuning the properties of functional groups in
amphiphiles. Zhang et al.,1e for example, made use of noncovalent
interactions to prepare a series of superamphiphiles and manipulate
their self-assembly and disassembly simply by external triggers. Lee
et al.1f developed responsive nanostructures via the self-assembly of
small block molecules based on rigidꢀflexible molecules in aqueous
solution. Much to our surprise, although a large number of functional
stimuli-responsive amphiphiles have been constructed during the
past decades, the self-assembling behavior of tetrathiafulvalene and its
derivatives (TTFs) in aqueous environment is far less explored.
As one of the most famous organic famous electron donors,
TTFs have been used as versatile building blocks in the design
of organic metals and self-assembling architectures.5,6 In 1995,
Received: May 7, 2011
Revised:
June 1, 2011
Published: June 06, 2011
r
2011 American Chemical Society
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Scheme 1. Chemical Structure of Amphiphile 1 and the Schematic Representation of Assembly and Disassembly of the Micelles
ARTICLE
Scheme 2. Synthetic Routes to 1 and 1aa
a Reagents and conditions: (a) trifluoroacetic acid, CH2Cl2; (b) 4-iodobenzoic acid, PyBOP, TEA, DMF, CH2Cl2; (c) TMSA, [Pd(PPh3)4], CuI, TEA,
THF; (d) K2CO3, CH3OH, CH2Cl2; (e) 2-iodotetrathiafulvalene, [Pd(PPh3)4], CuI, TEA, THF.
observed in organic solvents.10 As will be discussed later, this
expectation was found to be the case. The self-assembling and
disassembling processes are capable of realizing with the addition of
either chemical oxidant Fe(ClO4)3 or electron-deficient cyclophane
CBPQT4þ into the aqueous solution.
’ RESULTS AND DISCUSSION
Synthesis and Self-Assembly of Amphiphile 1 in Water.
The synthesis of amphiphile 1 was carried out under the typical
Sonogashira coupling conditions with a relatively shorter reac-
tion time and higher yield (Scheme 2). The starting N-Boc-
protected compound 2 (see Scheme S1) with hydrophilic R
Figure 1. Temperature-dependent transmittance at 700 nm of 1 (1 ꢁ
10ꢀ4 M) in aqueous solution.
group was deprotected under excess trifluoroacetic acid (TFA) in
CH2Cl2. Subsequently, an excess of triethylamine (TEA) was slowly
added to neutralize TFA in an iceꢀwater bath. The generated
terminal amine was directly coupled with 4-iodobenzoic acid in the
mixture of CH2Cl2 and DMF in the aid of benzotriazol-1-yl-oxy-
tripyrrolidinophosphonium hexafluorophosphate (PyBOP) to give
compound 3. The Sonogashira reaction of 3 with an excess
(trimethylsilyl)acetylene (TMSA) yielded 4, which was then de-
protected by excess K2CO3 in the mixture of CH3OH and CH2Cl2
to afford the terminal alkyne compound 5. Then, 5 was reacted with
2-iodotetrahiafulvalene in the presence of triethylamine (TEA) in
THF to produce target amphiphilic compound 1, which was
identified by 1H NMR and 13C NMR spectroscopy, matrix-assisted
laser desorption/ionization mass spectrometry (MALDI-TOF
MS), and satisfactory elemental analysis. As expected, amphiphile
1 was found very soluble both in organic solvents and in water.
Owing to temperature-sensitive hydrogen-bonding ability of
poly(ethylene glycol) functionality with water,13 it is suggested
that the degree of hydration of the ethylene oxide chains would
decrease with increasing temperature, thus resulting in a lower
critical solution temperature (LCST) behavior. This was indeed
observed as shown in Figure 1 (inset). The solution of amphi-
phile 1 becomes turbid upon heating, and the whole process was
thermally reversible. The value of LCST was determined to be
around 37 °C by the transmittance change of amphiphile 1 at
700 nm. Clearly, this thermoresponsive solution behavior is
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resulted from the dehydration of TEG chains and amide groups
with increasing temperature.
main distribution of hydrodynamic diameter (Dh) of the aggre-
gates centered at ∼8 nm in aqueous solution (Figure 3a).
Cryogenic transmission electron microscopy (cryo-TEM) was
performed to gain a direct visualization of the size and morphol-
ogy. As shown in Figure 3b and Figure S4, individual spherical
micelles were clearly observed with the diameter in the range of
6ꢀ11 nm, in a good agreement with that obtained by DLS. As for
the aqueous solution of reference 1a at the same concentration,
however, the low DLS count rates (less than 12 kcps) and cryo-
TEM images suggestnoaggregation for 1a under the similar condi-
tions (Figure S5). These results further indicate that hydrophobic
p-phenyleneethynyleneꢀTTF unit is necessary for self-assembly
of amphiphile 1 in water. In addition, a small amount of larger
aggregates was observed around 73 nm with a close inspection of
DLS data and cryo-TEM image of 1, suggesting the existence of
vesicles in a small quantity (Figure S6).
Disassembly by Chemical Oxidant Fe(ClO4)3. As we know,
TTF moiety can be oxidized to its radical cation (TTF3 þ) and
dication (TTF2þ) sequentially and reversibly at low potentials. In
the case of amphiphile 1, cyclic voltammetry (CV) experiment was
carried out in water. Two reversible one-electron oxidation waves
(E1/2) at þ316 and þ601 mV vs SCE, corresponding to the two-
step oxidation (TTF f TTF•þ f TTF2þ), were detected (Figure
S7). To exploit the influence of oxidized TTF on the amphiphilicity
of 1 and the stability of micelles, we employed Fe(ClO4)3 as an
oxidant to generate these oxidized states of 1 in aqueous and
CH3CN solutions, respectively (Figure 4a and Figure S8). Mon-
itored by absorption spectra, it was found that about 32 equiv of
Fe(ClO4)3 was required to fully oxidize 1 in the aqueous solution,
whereas only2 equivof Fe(ClO4)3 was needed to produce dication
12þ (TTF2þ) in CH3CN. Such differences could be interpreted by
the fact that the TTF moiety is buried in the hydrophobic core of
micelles that is not easily accessible for Fe(ClO4)3. Furthermore,
electron spin resonance (ESR) of radical cation 1•þ (TTF•þ)
showed four-line spectra in aqueous solution, while no splitting
signal could be observed from that of 1•þ in CH3CN (Figure 4b
and Figure S9). Such a difference was presumably induced by the
spinꢀspin coupling of TTF•þ units in 1•þ, which are close to each
other in the hydrophobic inner core in aqueous solution.14
As shown in Figure 5, with continuous addition of Fe(ClO4)3
to a solution of 1 and NR, the fluorescence intensity of NR
encapsulated into the hydrophobic core of micelles decreased as
well as red-shifted to longer wavelength,15 indicative of the
release of NR and the collapse of micellar architectures. Accord-
ing to the relative fluorescence intensity, 70% NR was found to be
The self-assembly of amphiphile 1 can be performed by simply
1
dissolving into water. Far from its H NMR spectra in organic
solvents, the proton signals of amphiphile 1 in D2O were broad,
weak, and upfield-shifted (Figure S1), which may be derived
from the interaction between the TTF groups and the environ-
mental change of 1, i.e., the formation of aggregates in water. Such
aggregates was evidenced by fluorescence spectroscopy method,
where organic dye Nile red (NR) was served as a probe. It is well-
known that NR is not soluble in water because of its strong
hydrophobicity. No absorption and emission could be detected from
its aqueous solution. When NR was introduced to the aqueous
solution of amphiphile 1, as shown in Figure 2, the fluorescent
intensity of NR remained almost unchanged at low concentration,
but a sharp increase was clearly observed as the concentration of 1
over 1.6 ꢁ 10ꢀ5 M. No significant change in the fluorescence spectra
of NR was observed for model compound 1a under the same
conditions. These results suggest that amphiphile 1 aggregates in
water and the dyes have been encapsulated inside the hydrophobic
domain of the aggregators. Consistent with that obtained by the
fluorescence spectroscopy method, the plot of the surface tension
versus the concentration of amphiphile 1 further proved the forma-
tion of aggregates with critical aggregation concentration (CAC)
value of 1.5 ꢁ 10ꢀ5 M (Figure S2).
The aggregated species of 1 in aqueous solution was corro-
borated by dynamic light scattering (DLS) experiments. CON-
TIN analysis of the DLS autocorrelation function of 1 shows a
Figure 2. Fluorescence intensity of NR as a function of the concentra-
tion of 1 (9) and 1a (b) in water at ambient temperature (λex = 530 nm,
λem = 635 nm).
Figure 3. DLS data (a) and cryo-TEM image of the micelles (b) for amphiphile 1 obtained at concentration of 9.0 ꢁ 10ꢀ5 M in aqueous solution. The
DLS data are shown as the size probability distribution obtained by a CONTIN analysis.
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Figure 4. (a) Absorption spectral changes of 1 (5 ꢁ 10ꢀ5 M) in aqueous solution with the concentration of Fe(ClO4)3. (b) ESR spectra of radical
cation 1•þ (1 ꢁ 10ꢀ4 M); in water at room temperature.
in 1 to influence the reduction of the radical cation TTF•þ
back to its neutral form.
Additional insight into the complexation of 1 and CBPQT4þ
was gained by means of 1H NMR spectroscopy studies in D2O
and CD3CN (Figure 6b and Figure S13). A mixture of 1 and
CBPQT4þ (1:1) exhibited a quite different spectrum from that of
amphiphile 1 itself in D2O. Upon addition of CBPQT4þ to
solution, the broad and featureless peaks of 1 disappeared with
emergence of notable splitting and shifting signals. Specifically,
the proton H (]) resonance of TTF unit shifted to upfield
position (Δδ = 0.17 ppm in D2O, 0.56 ppm in CD3CN), whereas
the aromatic protons H (2, ]) neighboring the TTF unit shifted
to downfield (Δδ = 0.22 for H (4) and 0.63 for H (2) in D2O;
0.16 for H (4) and 0.26 ppm for H (2) in CD3CN). These
observations suggest the formation of charge-transfer complex
between 1 and CBPQT4þ, leading to the strong shielding and
deshielding effect of the aromatic rings in CBPQT4þ. In contrast
to the upfield shift (Δδ = 0.15 ppm for H ([)) in CD3CN, the
“abnormal” downfield shift of H ([, Δδ = 0.08 ppm) of TTF
unit in CBPQT4þ aqueous solution could be explained as follows.
The protons of TTF unit located in the inner core of micelles felt the
strong shielding effect. When the TTF unit was trapped into the ring
of CBPQT4þ, the shielding effect of CBPQT4þ ring is smaller than
the deshielding effect induced by the disassembly of micelles. As a
result, the H ([) of TTF unit was downfield-shifted in D2O upon
Figure 5. Fluorescence spectra of NR in the aqueous solution of 1
(8.0 ꢁ 10ꢀ5 M) with the concentration of Fe(ClO4)3.
out of the micelles. The fluorescence spectra of either NR in the
presence of Fe(ClO4)3 or the micelles of 1 with NR in the
presence of NaClO4 have no significant changes (Figures S10
and S11), suggesting that the disassembly of micelle architectures
was induced by the oxidation of TTF unit to more hydrophilic
TTF2þ, together with the electrostatic repulsion between the
oxidized species. Such disassembly was supported by the cryo-
TEM image of 1 upon fully oxidation of the TTF unit by an
excess of Fe(ClO4)3 (Figure S12).
addition of CBPQT4þ
.
Disassembly by Electron-Deficient Cyclophane CBPQT4þ
.
The disassembling micelles of 1 upon complexation with
CBPQT4þ were further studied using fluorescence and cryo-
TEM techniques. Figure 7a displayed the fluorescence spectra of
1 and NR with the addition of CBPQT4þ. In the beginning, the
fluorescent intensity was slightly increased, possibly due to the
reduction of electron transfer from the TTF unit in 1 to NR.
Subsequently, the fluorescent intensity of NR decreased dramati-
Because of the high π-electron-donating ability, TTFs can form
stable charge-transfer complexes with electron-deficient species,
tetracationic cyclobis(paraquat-p-phenylene) (CBPQT4þ).16
Herein, we took advantage of the complexation of 1 and
CBPQT4þ in solution to disassembly the micelle architec-
tures. As shown in Figure 6a, when amphiphile 1 and
CBPQT4þ were mixed in water, a green solution appeared
immediately, accompanied with a very broad charge-transfer
band around 800 nm in the absorption spectra. Meanwhile,
the CV patterns were remarkably affected by the presence of
CBPQT4þ (Figure S7). The first oxidation peak for the
complex shifted dramatically from þ316 to þ535 mV,
whereas the second oxidation peak at þ601 mV was almost
the same as that of 1 in aqueous solution. These observations
indicate that CBPQT4þ ring moves away from the TTF unit in
the charge-transfer complex just as soon as it is oxidized to the
radical cation 1•þ. In the reducing cycle, the first reduction
peaks of the dication TTF2þ are almost identical at þ531 mV,
which means that the CBPQT4þ ring is close to the TTF unit
cally even to disappearance with the concentration of CBPQT4þ
,
while no significant changes could be observed from that of NR itself
in water under the same condition (Figure S14). Clearly, the
remarkable decrease in fluorescence intensity of NR was triggered
by its release from the disassembling micelles upon complexation
with CBPQT4þ. Such a disassembling fact was also confirmed by
the cryo-TEM image of 1 inthe presence of CBPQT4þ (Figure 7b).
This disruption may be explained by considering the two factors:
(1) the original hydrophobic part of 1 became more hydrophilic
upon complexation with CBPQT4þ, and (2) the electrostatic
repulsion interactions between these terminus tetracationic species
caused the separations of charge-transfer complexes.
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Figure 6. (a) Absorption spectra of 1 (5 ꢁ 10ꢀ5 M) in the absence and presence of CBPQT 4Cl (1.0 equiv) in H2O. (b) Partial 1H NMR spectra
3
(400 MHz, D2O, 298 K) of 1 (3 mM, bottom), 1 þ 1.0 equiv of CBPQT 4Cl (middle), and CBPQT 4Cl (3 mM, top).
3
3
Figure 7. (a) Fluorescence spectra of NR and 1 (8.0 ꢁ 10ꢀ5 M) with the concentration of CBPQT 4Cl in water. (b) Cryo-TEM image of 1 (8.0 ꢁ 10ꢀ5 M)
3
in the presence of CBPQT4þ (1.4 equiv).
’ CONCLUSIONS
or by the complexation with electron-deficient ring CBPQT4þ
.
This is, to the best of our knowledge, the first example of micelles
based on a small organic molecule featuring electroactive TTF unit.
It is anticipated that this research line can lead to the fabrication of
new smarter aggregates, such as vesicle, which is actively undergoing
in our research group.
In conclusion, we have synthesized a redox-active TTF functio-
nalized amphiphile 1by the Sonogashira reaction in a good chemical
yield. The amphiphilic 1 can self-assembly in water to form micellar
aggregates. More interestingly, the micelle architectures could
be disrupted either by the addition of chemical oxidant Fe(ClO4)3
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’ EXPERIMENTAL SECTION
(m, 10H), 3.34 (s, 3H), 3.32 (s, 6H), 1.79 (s, 2H). 13C NMR (101 MHz,
CDCl3): δ 167.3, 166.6, 152.0, 140.7, 134.1, 131.2, 129.1, 127.0, 125.6, 124.6,
118.9, 118.7, 115.1, 106.6, 92.4, 72.0, 71.5, 70.3, 70.1, 69.3, 68.6, 58.6, 36.2,
29.2. MALDI-TOF-MS: m/z calcd for C46H62N2O14S4: 995.2; found: 993.7
[M]þ. Anal. Calcd (%) for C46H62N2O14S4: C, 55.51; H, 6.28; N, 2.81;
found: C, 55.57; H, 6.33; N, 2.86.
3: To a CH2Cl2 (30 mL) solution of 2 (8.03 g, 10.5 mmol) was added
20 mL of trifluoroacetic acid (TFA), and the mixture was stirred at room
temperature for over 2 h. Then, an excess of triethylamine was added to
neutralize TFA in the iceꢀwater bath. To the resulting mixture was added
DMF (50 mL), 4-iodobenzoic acid (2.48 g, 10 mmol), and then PyBOP
(6.24 g, 12 mmol). The solution was stirred at room temperature for another
1.5 h, then poured into water (200 mL), and extracted with CH2Cl2 (3 ꢁ
100 mL). The combined organic layer were washed with brine for more than
eight times to remove DMF, dried over Na2SO4, and evaporated in vacuo to
dryness. The crude product was purified by silica gel flash column chroma-
tography (CH2Cl2/CH3OH, 100/1) to give 3 as colorless oil (7.61 g, 8.5
mmol, 85%). 1H NMR (400 MHz, CDCl3): δ 7.80 (d, J = 8.3 Hz, 2H), 7.64
(d,J= 8.4 Hz, 3H), 7.17 (s, 3H), 4.24ꢀ4.19 (m, 6H), 3.84 (t, J= 4.7 Hz, 4H),
3.79 (t, J = 5.1 Hz, 2H), 3.72ꢀ3.70 (m, 6H), 3.67ꢀ3.62 (m, 12H),
3.55ꢀ3.49 (m, 10H), 3.37 (s, 3H), 3.35 (s, 6H), 1.80 (s, 2H). 13C NMR
(101 MHz, CDCl3): δ 167.9, 166.9, 152.5, 141.5, 137.7, 133.9, 129.4, 128.9,
107.4, 98.4, 72.4, 71.9, 70.7, 70.5, 69.8, 69.1, 59.0, 36.4, 36.2, 29.7. MALDI-
TOF-MS: m/z calcd for C38H59IN2O14: 894.8; found: 917.4 [M þ Na]þ.
4: Compound 3 (0.89 g, 1.0 mmol), CuI (7.6 mg, 0.04 mmol), and
Pd(PPh3)4 (23 mg, 0.02 mmol) were added to the mixture of anhydrous
THF (40 mL) and TEA (20 mL) under Ar. While stirring, trimethylsily-
lethyne (0.12 g, 1.20 mmol) was injected through syringe. The reaction
mixture was stirred at 50ꢀ60 °C overnight under an Ar atmosphere and was
monitored by TLC. Upon completion, the solution was evaporated in vacuo
to dryness. The crude product was purified by silica gel flash column
chromatography (CH2Cl2/CH3OH, 100/1) to give the compound 4 as a
colorless oil (0.75 g, 0.87 mmol, 87%). 1H NMR (400 MHz, CDCl3): δ 7.82
(d, J = 8.2 Hz, 2H), 7.67 (s, 1H), 7.49 (d, J = 8.2 Hz, 2H), 7.44 (s, 1H), 7.17
(s, 2H), 4.20ꢀ4.16 (m, 6H), 3.81 (t, J= 4.8 Hz, 4H), 3.76 (t, J= 5.0 Hz, 2H),
3.70ꢀ3.68 (m, 6H), 3.62ꢀ3.60 (m, 12H), 3.52ꢀ3.49 (m, 10H), 3.34
(s, 3H), 3.32 (s, 6H), 1.78 (s, 2H), 0.23 (s, 9H). 13C NMR (101 MHz,
CDCl3): δ 167.4, 166.9, 152.1, 140.8, 133.8, 131.7, 129.2, 126.9, 125.9, 106.8,
104.0, 96.5, 72.1, 71.6, 70.4, 70.3, 70.2, 69.4, 68.6, 58.7, 36.3, 36.2, 29.3, ꢀ0.3.
MALDI-TOF-MS: m/z calcd for C43H68N2O14Si: 865.1; found: 865.5
[M]þ, 887.6 [M þ Na]þ, 903.7 [M þ K]þ.
’ ASSOCIATED CONTENT
S
Supporting Information. Experimental details. This mate-
b
rial is available free of charge via the Internet at http://pubs.acs.org.
’ AUTHOR INFORMATION
Corresponding Author
*E-mail: lzwu@mail.ipc.ac.cn. Fax: þ86 10-8254 3580.
’ ACKNOWLEDGMENT
We are grateful for financial support from the National Science
Foundation of China (20732007, 20920102033, and 20972171),
the Ministry of Science and Technology of China (2007CB808004,
2007CB936001, and 2009CB22008), and the Bureau for Basic
Research of Chinese Academy of Sciences. We thank Prof. Dr.
Zhibo Li (ICCAS, Beijing) and Dr. Gang Ji (IBP, Beijing) for their
help on cryo-TEM.
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5: To a CH2Cl2 (20 mL) and methanol (30 mL) solution of 4 (2.10 g,
2.43 mmol) was added K2CO3 (13.8 g, 10 mmol). The solution was stirred at
room temperature for 15 min, then poured into water (100 mL), and
extracted with CH2Cl2 (3 ꢁ 50 mL). The combined organic layer were
washed with 1 M HCl (1 ꢁ 100 mL) and brine (3 ꢁ 150 mL), dried over
Na2SO4, and evaporated in vacuo to dryness. The crude product was purified
by silica gel flash column chromatography (CH2Cl2/CH3OH, 105/1) to give
5 as colorless oil (1.83 g, 2.31 mmol, 95%). 1H NMR (400 MHz, CDCl3):
δ7.89(d,J= 8.3 Hz, 2H), 7.73 (s, 1H), 7.54 (d, J= 8.3 Hz, 2H), 7.48 (s, 1H),
7.23 (s, 2H), 4.25 (t, J = 4.6 Hz, 4H), 4.20 (t, J = 4.8 Hz, 2H), 3.83 (t, J = 5.1
Hz, 4H), 3.76 (t, J = 4.6 Hz, 2H), 3.71ꢀ3.69 (m, 6H), 3.65ꢀ3.61 (m, 12H),
3.55ꢀ3.51 (m, 10H), 3.36 (s, 3H), 3.34 (s, 6H), 3.18 (s, 1H), 1.82 (s, 2H).
13C NMR (101 MHz, CDCl3): δ 167.4, 166.8, 152.1, 140.8, 134.1, 131.8,
129.2, 126.9, 124.9, 106.7, 82.6, 79.5, 72.1, 71.6, 70.4, 70.3, 70.2, 70.1, 69.4,
68.6, 58.6, 36.2, 36.1, 29.2. MALDI-TOF-MS: m/z calcd for C40H60N2O14:
792.3; found: 793.5 [M þ H]þ, 815.5 [M þ Na]þ.
1: To the mixture of anhydrous THF (30 mL) and TEA (30 mL) were
added 5 (0.83 g, 1.05 mmol,), TTF-I (0.4 g, 1.20 mmol), CuI (3.8 mg, 0.02
mmol), and Pd(PPh3)4 (12 mg, 0.01 mmol) under Ar. The reaction mixture
was refluxed over 12 h under an Ar atmosphere and was monitored by TLC.
Upon completion, the solution was evaporated in vacuo to dryness. The
crude product was purified by silica gel flash column chromatography
(CH2Cl2/CH3OH, 90/1) to give the compound 1 as red oil (0.86 g, 0.89
mmol, 85%). 1H NMR (400 MHz, CDCl3): δ 7.85 (d, J = 8.5 Hz, 2H), 7.77
(s, 1H), 7.54 (s, 1H), 7.47 (d, J = 8.4 Hz, 2H), 7.17 (s, 2H), 6.60 (d, J = 2.3
Hz, 1H), 6.31 (s, 2H), 4.21ꢀ4.16 (m, 6H), 3.81 (t, J = 5.1 Hz, 4H), 3.76
(t, J = 4.7 Hz, 2H), 3.69ꢀ3.67 (m, 6H), 3.63ꢀ3.59 (m, 12H), 3.52ꢀ3.47
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