New p-n diblock and triblock oligomers: Effective tuning of HOMO/LUMO energy levels

Article abstract of DOI:10.1016/j.tetlet.2006.02.001

A new series of oligomers consisting of thiophene as p-type unit and oxadiazole as n-type unit were synthesized, and their photophysical and electrochemical properties were evaluated. Cyclic voltammography studies demonstrated that the electronic properties of the p-n diblock oligomers could be modulated by changing the number of thiophene and oxadiazole rings. The molecular regiochemical effect to the electrochemical and optical properties was also investigated.

Full text of DOI:10.1016/j.tetlet.2006.02.001

Tetrahedron Letters 47 (2006) 2829–2833
New p–n diblock and triblock oligomers: effective tuning
of HOMO/LUMO energy levels
Jun-Hua Wan, Jia-Chun Feng, Gui-An Wen, Hong-Yu Wang, Qu-Li Fan, Wei Wei,*
Chun-Hui Huang and Wei Huang*
Institute of Advanced Materials (IAM), Fudan University, 220 Handan Road, Shanghai 200433, China
Received 11 October 2005; revised 27 January 2006; accepted 1 February 2006
Available online 3 March 2006
Abstract—A new series of oligomers consisting of thiophene as p-type unit and oxadiazole as n-type unit were synthesized, and their
photophysical and electrochemical properties were evaluated. Cyclic voltammography studies demonstrated that the electronic
properties of the p–n diblock oligomers could be modulated by changing the number of thiophene and oxadiazole rings. The molec-
ular regiochemical effect to the electrochemical and optical properties was also investigated.
ꢀ 2006 Elsevier Ltd. All rights reserved.
As potential patterned light sources and large area dis-
plays, polymer light-emitting diodes (PLEDs) have
drawn special attention.1 High efficiency single-layer
PLEDs require the conjugated polymers with balanced
injection and transport properties for both electrons
and holes.2 In our previous work, we have developed a
p–n diblock concept and obtained a series of p–n di-
block conjugated polymers.3 The variation in p and n
segments of the block polymer chain gave the possibility
of tuning the HOMO and LUMO energy levels as well
as emissive wavelengths. These polymers showed
improved photoluminescent and electroluminescent
properties. However, the improvement is still below
the expected level. The poor improvement maybe attrib-
uted to the alternated distribution of the p-segment and
n-segment in the polymer chain. Electron deficient unit
inserted into a p-type polymer chain will partially act
as the hole-blocking unit due to its high electron defi-
ciency. Vice versa, the hole-transporting unit will lower
the electron mobility.
be accurately adjusted and controlled. In this letter, a
series of diblock oligomers (T2O, T2O2, and T4O2) con-
sisting of electron-rich thiophene unit and electron-defi-
cient oxadiazole unit with different unit lengths were
successfully synthesized (Scheme 1). By changing num-
ber of thiophene and oxadiazole repeating units, the re-
dox properties and emissive wavelength of those diblock
oligomers were readily tuned. For comparison, another
C8H17
C8H17O
S
O
S
N
N
C8H17 OC8H17
T2O
C8H17
C8H17O
S
O
O
Diblock
S
N
N
N N
OC8H17
C8H17
T2O2
C8H17
C8H17
C8H17
O
O
S
S
O
S
S
N
N
N
N
OC8H17
C8H17
C8H17
T4O2
The above-mentioned drawback can be resolved by
defining the diblock oligomer with two separate blocks,
the p-type and n-type unit, respectively. By tuning the
unit length, the HOMO and LUMO energy levels can
C8H17
O
C8H17
C8H17O
S
O
O
S
N
N
N N
OC8H17
OC8H17
C8H17
Triblock
OT2O
C8H17
OC8H17
OC8H17
S
C8H17
N
N
Keywords: Thiophene; Oxadiazole; Diblock oligomers; Triblock oligo-
S
O
S
O
S
mers; Electronic properties.
N
N
C8H17
O
C8H17
C8H17
O
*
C8H17
Corresponding authors. Tel.: +86 21 5566 4188/4198; fax: +86 21
6565 5123/5566 4192; e-mail addresses: iamww@fudan.edu.cn;
chehw@nus.edu.sg; wei-huang@fudan.edu.cn
T2O2T2
Scheme 1. The structures of oligomers.
0040-4039/$ - see front matter ꢀ 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2006.02.001

2830
J.-H. Wan et al. / Tetrahedron Letters 47 (2006) 2829–2833
series of n–p–n(OT2O) and p–n–p(T2O2T2) triblock
oligomers were also synthesized (Scheme 1). Comparing
with the conjugated copolymers, the monodisperse con-
jugated oligomers possess well-defined and uniform
structures, ease of purification and characterization.4
Furthermore, deep electron traps possibly occur in poly-
meric systems due to chain entanglements or structural
defects, which may not be observed in the well-defined
oligomeric system.5
the two by-products were removed by a silica gel chro-
matography. After cyclodehydration of Compound 6,
monobromo-substituted oxadiazole dimer
7
was
obtained with 73% yield. The thiophene monomers
10 and 11 were prepared through the ordinary route.
Scheme 3 shows the synthetic route to the oligomers.
The oligomers were constructed in moderate yield from
the thiophene monomer with corresponding oxadiazole
monomer by Stille reaction. Exceptably, due to the dif-
ficulty of obtaining pure monobromo-substituted tetra-
thiophene monomer through the ordinary route, T4O2
was obtained from the Stille reaction of the stannane
10 with compound Br–T2O2, which was obtained by
the bromination of T2O2 with NBS. The structure and
purity of all oligomers were verified by 1H and 13C
NMR, MALDI-TOF-mass, and the elemental analysis.6
Generally, the oligomers synthesis involves three proce-
dures, for example, the synthesis of the thiophene mono-
mers, the synthesis of the oxadiazole monomers,
and coupling reaction. Scheme 2 shows the synthetic
route to oxadiazole monomer. The common synthetic
sequence of 4-bromo-2,5-bis(octyloxy)benzoic acid
methyl ester 2 from compound 1 involves three steps,
which is rather complicated (Scheme 2). We developed
a one-pot synthesis route for compound 2 from 1,4-dib-
romo-bis(octyloxy)benzene 1. Compound 2 with 60%
yield was prepared by treating 1 with n-BuLi and liquid
dimethyl carbonate, which is more convenient to use
than gas CO2. Moreover, the monobromo-substituted
oxadiazole dimer was synthesized successfully (Scheme
2). To the our best knowledge, no monobromo-substi-
tuted oxadiazole dimer has been synthesized so far. To
obtain compound 6, the mixture of compound 3 and
benzohydrazide in pyridine was added into the solution
of terephthaloyl dichloride in anhydrous THF slowly by
a syringe. Compound 6 was obtained in 45% yield after
Spectroscopic properties of the oligomers were investi-
gated with the UV–vis absorption and fluorescence
emission. Figure 1a shows the absorption spectra of
the oligomers in toluene. The oligomers, T2O2, T4O2,
C8H17
S
5
(i)
9
(i)
SnBu3
C8H17
T2O
S
T2O2T2
10
7
(i)
T2O2
NBS
(ii)
OC8H17
COCl
OC8H17
COOH
C8H17
O
C8H17
Br
SOCl2
S
O
O
Br
Br
S
N
N
N
N
C8H17
O
C8H17
O
OC8H17
C8H17
1.n-BuLi
2.CO2
MeOH
Br-T2O2
C8H17
O
C8H17
Br
O
C8H17
Br
O
10
(i)
(i)
(ii)
Br
CO2Me
OC8H17
CONHNH2
OC8H17
Br
T4O2
C8H17
Bu3Sn
OC8H17
S
2
1
3
SnBu3
C8H17
5
(i)
(iii)
O
S
OT2O
C8H17
Br
O
C8H17
O
O
11
(iv)
O
Br
CNHNHC
N
N
OC8H17
OC8H17
Scheme 3. Reagents and conditions: (i) Pd(PPh3)4 (3%), 100 ꢁC,
toluene, 60% (T2O), 71% (T2O2), 73% (T4O2), 70% (OT2O), 35%
(T2O2T2); (ii) NBS, CHCl3/AcOH, 80%.
4
5
C8H17
Br
O
O
O
N
N
N
N
OC8H17
(iv)
7
O
C8H17O
O
O
O
Br
CNHNHC
CNHNHC
T O
2
T
O
2
6
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
T O
OC8H17
2
2
T O
2
2
(v)
T O
4
2
T O
4
2
OT O
2
OT O
2
T O T
ClOC
OC8H17
COCl
2
2
2
T O T
2 2
2
(vi)
OC8H17
O
O
O
O
Br
CNHNHC
CNHNHC
Br
8
C8H17
C8H17O
(iv)
OC8H17
O
OC8H17
Br
O
Br
N
N
N
N
C8H17
O
C8H17
O
9
300
350
400
450
400
500
600
Scheme 2. Reagents and conditions: (i) n-BuLi, ꢀ78 ꢁC, Me2CO3,
THF, 60%; (ii) NH2NH2ÆH2O, MeOH, 83%; (iii) benzoyl chloride,
pyridine, 73%; (iv) POCl3, 80 ꢁC, 75% (5), 73% (7); (v) the solution of 3
and benzohydrazide in pyridine, THF, 45%; (vi) 3, pyridine.
(a)
Wavelength (nm)
(b)
Wavelength (nm)
Figure 1. (a) Absorption spectra in toluene, (b) fluorescence spectra in
toluene (1 · 10ꢀ5 M solution in toluene, normalized).

J.-H. Wan et al. / Tetrahedron Letters 47 (2006) 2829–2833
2831
and T2O2T2 show two distinct absorption bands. The
absorption bands at longer wavelength range
(>360 nm) come from the thiophene units,7 and the
remarkable enhancement of the absorption intensity of
T4O2 relative to T2O2 reflects the corresponding in-
creases in the number of thiophene units in the oligo-
mers. Another absorption bands of T2O2, T4O2, and
T2O2T2 (around 300 nm) come from the p–p* transition
of oxadiazole groups.8 This implies that the electronic
interactions between the oxadiazole units and thiophene
units are rather limited. Nevertheless, both T2O and
OT2O display no remarkable absorption band in the
range of shorter wavelengths.
The redox properties of these materials were determined
by cyclic voltammetry in the CH2C12 and THF solution
of 0.1 M tetrabutylammonium hexafluorophosphate
(TBAPF6) using a Pt wire as a counter electrode and a
Ag/AgNO3 (0.1 M) electrode as the reference electrode.
When scanning cathodically, all oligomers display
reversible reduction processes. In the case of the diblock
oligomers, the increase of the oxadiazole ring number in
the oxadiazole unit changes the reduction potential of
1=2ðRÞ
those material remarkably (E
¼ ꢀ2:06 V and
T2O2
1=2ðRÞ
E
¼ ꢀ2:44 V versus Ag/Ag+). The detailed data
T2O
are listed in Table 2 and cyclic voltammograms are given
in Figure 2. The increasing thiophene ring number of
those materials does not affect the reduction potential
remarkably. As seen from Figure 2 and Table 2, the
introduction of one oxadiazole ring to the terminal thio-
phene side of T2O (T2O ! OT2O) had much smaller
Figure 1b shows the normalized fluorescence emission
spectra of the oligomers in toluene. In the case of di-
block oligomers, with the increasing number of thio-
phene unit in T4O2 relative to T2O2, bathochromic
shifts result from the formation of a highly extended
p-delocalized system.
effect to the terminal oxadiazole side (T2O ! T2O2)
1=2ðRÞ
regarding the reduction potential (E
¼ ꢀ2:06 V
T2O2
1=2ðRÞ
and E
¼ ꢀ2:39 V versus Ag/Ag+). The molecular
OT2O
regiochemistry has also a significant impact on the
T4O2 versus T2O2T2 and T2O2 versus OT2O with differ-
ent regiochemistry exhibit different emission wavelength
in spite of the same unit numbers. Apparently, the emis-
sion wavelength can be modulated by different molecu-
lar regiochemistry as well as unit number. The
emissive color varying from blue to green were achieved
for the respective toluene solutions.
1=2ðRÞ
1=2ðRÞ
reduction potential (E
¼ ꢀ2:06 V and E
¼
T2O2
OT2O
2:39 V versus Ag/Ag+). This finding points out the exis-
tence of electronic interaction between two adjacent
oxadiazole rings. Cyclic voltammetric reduction poten-
tial values can be used as a surrogate for LUMO energy
levels. The results suggest that the LUMO of those mol-
ecules can be effectively adjusted by changing the
oxadiazole ring number and molecular regiochemistry.
The reduction onset potential of T2O2 and T4O2 was
measured to be ꢀ1.98 and ꢀ2.00V versus Ag/Ag+.
The value is comparable with that of 1,3,5-tris(N-phen-
ylbenzimidizol-2-yl)benzene (TPBI) (ꢀ1.7 V versus
SCE), one of the most widely used electron-transporting
materials.9
All of the oligomers exhibit only one maximum emis-
sion, and this emission maximum is clearly independent
to the excitation wavelength. This indicates the existence
of efficient energy transfer from the oxadiazole moiety
to the thiophene chromophore.8a The PL quantum yield
(Uf) of T2O, T2O2, and OT2O were calibrated against
9,10-diphenylanthracene (Table 1). They were remark-
ably higher than that of poly(3-octylthiophene)
(U = 0.11).
On sweeping anodically, all of those materials undergo a
reversible multielectron (two or three) oxidation origi-
nating from oligothiophene segments except T2O2T2.
Unlike their reduction potentials, the oxidation poten-
tial of diblock oligomers is sensitive to the variation of
Table 1. Optical properties of the oligomers
a
a
Oligomer
Abkmax (nm)
PLkmax (nm)
Ufb (%)
T2O
T2O2
/363
441
446
495
471
451
16
19
thiophene ring number in the oligothiophene units
312/371
314/377
/376
1=2ðOÞ
1=2ðOÞ
(E
¼ 0:65 V and E
¼ 0:52 V versus Ag/Ag+),
T4O2
OT2O
T2O2T2
T2O2
T4O2
17.5
while the increase of oxadiazole ring does not change
315/376
1=2ðOÞ
the oxidation potentials (E
¼ 0:67 V versus Ag/
T2O
a Measured in toluene (1 · 10ꢀ5 M).
Ag+) remarkably. This indicated that the HOMO level
of the diblock oligomers can be effectively adjusted by
b 9,10-Diphenylanthracene standard (UPL = 0.95 in cyclohexane).
Table 2. Electrochemical data of oligomers
Oligomer
Reductiona
Oxidationa
LUMO/HOMOc (eV)
b
Epa/Epc (V)
Epc/Epa (V)
T2O
T2O2
ꢀ2.52/ꢀ2.36
ꢀ2.13/ꢀ1.99
ꢀ2.13/ꢀ2.03
ꢀ2.51/ꢀ2.28
ꢀ2.32/ꢀ2.16
0.83/0.52
0.78/0.52
0.61/0.44
0.76/0.64
0.83/0.72
ꢀ2.37/ꢀ5.37
ꢀ2.72/ꢀ5.39
ꢀ2.70/ꢀ5.15
ꢀ2.40/ꢀ5.30
ꢀ2.60/ꢀ5.38
T4O2
OT2O
T2O2T2
a Determined by cyclic voltammetry in dichloromethane (for oxidation) and THF (for reduction) with Ag/AgNO3 (0.1 M) as a reference electrode.
Scan rate: 200 mV sꢀ1
.
b Epa and Epc stand for anodic peak potential, and cathodic peak potential, respectively.
c HOMO and LUMO energy was calculated with reference to ferrocene (4.7 eV).

2832
J.-H. Wan et al. / Tetrahedron Letters 47 (2006) 2829–2833
T4O2
T O2
OT2O
T2O
T2O2T2
2
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
-2.5
-2.0
-1.5
-1.0 -0.5
0.0
0.5
1.0
Potential (V vs Ag/Ag+ )
Potential (V vs Ag/Ag+ )
Figure 2. Cyclic voltammogram of oligomers. Measured in dichloromethane (for oxidation) and THF (for reduction). Scan rate: 200 mV sꢀ1
.
Inbasekaran, M.; O’Brien, J.; Wu, W. Adv. Mater. 2000,
12, 1737.
2. (a) Li, X.-C.; Liu, Y.; Liu, M. S.; Jen, A. K.-Y. Chem.
Mater. 1999, 11, 1568; (b) Shu, C.-F.; Dodda, R.; Wu, F.-
I.; Liu, M.-S.; Jen, A. K.-Y. Macromolecules 2003, 36,
6698.
changing the thiophene number. In the same way, the
oxidation potential can also be drastically modulated
1=2ðOÞ
by changing the molecular regiochemistry (E
¼
T4O2
1=2ðOÞ
0:52 V and E
¼ 0:77 V versus Ag/Ag+).
T2O2T2
3. Yu, W.-L.; Meng, H.; Pei, J.; Huang, W. J. Am. Chem.
Soc. 1998, 120, 11808.
4. (a) Klubek, K.; Vaeth, K. M.; Tang, C. W. Chem. Mater.
2003, 15, 4352; (b) Lee, S.-H.; Nakamara, T.; Tsutsui, T.
Org. Lett. 2001, 3, 2005.
5. Wu, C.-C.; Liu, T.-L.; Hung, W.-Y.; Lin, Y.-T.; Wong,
K.-T.; Chen, R.-T.; Chen, Y.-M.; Chien, Y.-Y. J. Am.
Chem. Soc. 2003, 125, 3710.
All oligomers undergo both reversible oxidation and
reduction process except T2O2T2, suggesting their po-
tential bipolar charge transport properties.10 Molecules
that can stabilize both cation and anion radicals are sug-
gested to be beneficial for OLED devices.11 However,
most of the respective diblock copolymers showed irre-
versible oxidation process.3
6. Physical data for oligomers. T2O: 1HNMR (400 MHz,
CDCl3): d 8.18–8.16 (d, 2H), 7.70 (s, 1H), 7.58–7.52 (m,
4H), 7.04 (s, 1H), 7.02 (s, 2H), 6.80 (s, 1H), 4.10–4.07 (t,
2H), 4.05–4.01 (t, 2H), 2.61–2.48 (m, 4H), 1.92–1.84 (m,
2H), 1.76–1.69 (m, 2H), 1.63–1.58 (m, 8H), 1.39–1.18 (m,
40H), 0.90–0.82 (m, 12H) ppm. 13C NMR (400 MHz,
CDCl3): d 165.0, 164.0, 151.1, 150.8, 144.4, 142.0, 137.3,
137.2, 131.7, 131.3, 129.2, 128.6, 127.1, 125.2, 125.0, 124.5,
119.0, 117.4, 114.3, 112.9, 69.9, 69.7, 32.1, 32.0, 30.8, 30.7,
30.6, 29.9, 29.7, 29.6, 29.5, 29.4, 26.5, 26.2, 22.9, 14.3 ppm.
Anal. Calcd for C54H78N2O3S2: C, 74.78; H, 9.06; N, 3.23;
S, 7.39. Found: C, 74.73; H, 9.10; N, 3.27; S, 7.33. MS
(MALDI-TOF): 865.9 (calcd for C54H78N2O3S2: 866.5).
In conclusion, a new series of p–n diblock and triblock
oligomers were synthesized and characterized. Changing
the number of thiophene and oxadiazole ring of the di-
block oligomer can modulate the redox behavior and
emission wavelength. We also made interesting findings
on the effect of molecular regiochemistry to electronic
properties. These should be valuable for the molecule
design of other organic electronic materials besides
light-emitting materials.
1
Acknowledgements
T2O2: H NMR (400 MHz, CDCl3): d 8.32 (s, 4H), 8.19–
8.17 (d, 2H), 7.72 (s, 1H), 7.59–7.56 (m, 3H), 7.04–7.01 (t,
3H), 6.80 (s, 1H), 4.11–4.08 (t, 2H), 4.03–4.00 (t, 2H),
2.60–2.51 (m, 4H), 1.93–1.89 (t, 2H), 1.76–1.72 (t, 2H),
1.62–1.58 (m, 8H), 1.54–1.25 (m, 40H), 0.90–0.82 (m, 12H)
ppm. 13C NMR (400 MHz, CDCl3): d 165.2, 164.5, 164.1,
164.0, 151.2, 150.8, 144.3, 142.0, 137.3, 137.2, 132.2, 131.2,
129.4, 129.0, 127.7, 127.6, 127.3, 127.2, 126.6, 125.5, 125.0,
123.8, 119.1, 117.3, 114.3, 112.4, 69.9, 69.7, 34.0, 32.1,
32.1, 32.0, 30.8, 30.7, 30.6, 29.8, 29.7, 29.6, 29.5, 29.4, 29.1,
26.5, 26.2, 22.9, 14.3 ppm. Anal. Calcd for C62H82N4O4S2:
C, 73.62; H, 8.17; N, 5.54; S, 6.34. Found: C, 73.58; H,
8.22; N, 5.49; S, 6.29. MS (MALDI-TOF): 1010.4 (calcd
This work was financially supported by the National
Natural Science Foundation of China (Grants
60325412 and 90406021), the Shanghai Commission of
Science and Technology (Grants 03DZ11016 and
04XD14002), and the Shanghai Commission of Educa-
tion (Grant 03SG03).
Supplementary data
1
for C62H82N4O4S2: 1010.58). T4O2: H NMR (400 MHz,
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.tetlet.
2006.02.001.
CDCl3): d 8.32 (s, 4H), 8.18–8.17 (d, 2H), 7.72 (s, 1H),
7.58–7.56 (t, 3H), 7.04–6.99 (m, 4H), 6.86 (s, 1H), 4.11–
4.08 (t, 2H), 4.04–4.01 (t, 2H), 2.56–2.50 (m, 8H), 1.91–
1.89 (t, 2H), 1.76–1.72 (t, 2H), 1.61–1.56 (m, 20H), 1.42–
1.25 (m, 60H), 0.93–0.82 (m, 18H) ppm. 13C NMR
(400 MHz, CDCl3): d 165.2, 164.5, 164.1, 164.0, 163.9,
151.2, 151.1, 144.3, 143.5, 143.4, 142.2, 137.6, 137.2, 137.1,
136.8, 132.2, 131.4, 129.4, 128.9, 127.7, 127.6, 127.5, 127.2,
127.0, 126.6, 125.3, 125.1, 123.8, 119.2, 117.3, 114.3, 112.5,
109.4, 69.9, 69.7, 34.0, 32.2, 32.1, 32.0, 31.8, 31.6, 30.8,
References and notes
1. (a) Burroughes, J. H.; Bradley, D. D. C.; Brow, A. R.;
Marks, R. N.; Mackay, K.; Friend, R. H.; Burn, P. L.;
Holmes, A. B. Nature 1990, 347, 539; (b) Bernius, M. T.;

J.-H. Wan et al. / Tetrahedron Letters 47 (2006) 2829–2833
2833
30.7, 30.6, 29.9, 29.8, 29.7, 29.6, 29.5, 29.4, 29.2, 28.2, 28.0,
27.9, 27.4, 27.1, 26.7, 26.5, 26.3, 22.9, 19.4, 17.7, 14.3,
13.8 ppm. Anal. Calcd for C86H118N4O4S4: C, 73.77; H,
8.49; N, 4.00; S, 9.16. Found: C, 73.75, H, 8.53; N, 3.97; S,
165.2, 164.2, 164.1, 151.7, 150.0, 144.3, 142.0, 137.3, 137.2,
132.2, 131.2, 129.4, 129.0, 127.6, 127.4, 127.3, 126.9, 126.6,
125.2, 125.0, 123.8, 118.9, 117.8, 114.4, 112.4, 69.9, 69.7,
32.0, 29.6, 29.5, 29.4, 29.3, 26.3, 26.2, 22.9, 22.8, 14.3 ppm.
Anal. Calcd for C102H150N4O6S4: C, 73.95; H, 9.13; N,
3.38; S, 7.74. Found: C, 73.91; H, 9.09; N, 3.34; S, 7.68.
MS (MALDI-TOF): 1656.6 (calcd for C102H150N4O6S4:
1655.0).
9.12.
MS
(MALDI-TOF):
1399.1
(calcd
for
C86H118N4O4S4: 1398.8). OT2O: 1H NMR (400 MHz,
CDCl3): d 8.16–8.14 (d, 4H), 7.70 (s, 2H), 7.54–7.52 (m,
6H), 7.06 (s, 2H), 7.02 (s, 2H), 4.10–4.06 (t, 4H), 4.03–4.00
(t, 4H), 2.55–2.51 (t, 4H), 1.90–1.86 (t, 4H), 1.76–1.72 (t,
4H), 1.65–1.52 (m, 12H), 1.41–1.23 (m, 60H), 0.90–0.83
(m, 18H) ppm. 13C NMR (400 MHz, CDCl3): d 165.0,
164.0, 151.1, 150.8, 142.1, 136.9, 131.7, 131.5, 129.2, 128.6,
127.1, 125.2, 124.5, 117.4, 114.3, 112.9, 69.9, 69.7, 60.6,
32.1, 32.0, 30.8, 29.9, 29.8, 29.7, 29.6, 29.5, 29.4, 28.0, 27.0,
26.5, 26.2, 22.9, 17.7, 14.4, 14.3, 13.8 ppm. Anal. Calcd for
C84H118N4O6S2: C, 75.07; H, 8.85; N, 4.17; S, 4.77.
Found: C, 74.04; H, 8.90; N, 4.11; S, 4.73. MS (MALDI-
TOF): 1344.1 (calcd for C84H118N4O6S2: 1342.8). T2O2T2:
1H NMR (400 MHz, CDCl3): d 8.31 (s, 4H), 7.71 (s, 2H),
7.04–6.98 (m, 6H), 6.80 (s, 2H), 4.11–4.08 (t, 4H), 4.03–
4.00 (t, 4H), 2.60–2.51 (m, 8H), 1.93–1.89 (m, 4H), 1.76–
1.72 (m, 4H), 1.63–1.53 (m, 16H), 1.41–1.00 (m, 80H),
0.90–0.77 (m, 24H) ppm. 13C NMR (400 MHz, CDCl3): d
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