Dye-functionalized head-to-tail coupled oligo(3-hexylthiophenes) - Perylene-oligothiophene dyads for photovoltaic applications

Article abstract of DOI:10.1039/b414817g

A series of novel donor-acceptor systems, consisting of head-to-tail coupled oligo(3-hexylthiophene)s covalently linked to perylenemonoimide, is described. These hybrid molecules, which differ by the length of the oligothiophene units from a monothiophene up to an octathiophene, were created via effective palladium-catalyzed Negishi and Suzuki cross-coupling reactions in good to excellent yields. The optical and electrochemical properties of these compounds were determined and based on this series structure-property relationships have been established which give vital information for the fabrication of photovoltaic devices. Because the synthesized perylenyl-oligothiophenes distinguish themselves by a high absorption between 300 and 550 nm and an almost complete fluorescence quenching of the perylene acceptor, they meet the requirements for organic solar cells. The Royal Society of Chemistry 2005.

Full text of DOI:10.1039/b414817g

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A R T I C L E
Dye-functionalized head-to-tail coupled oligo(3-hexylthiophenes)—
perylene–oligothiophene dyads for photovoltaic applications†
Jens Cremer,a Elena Mena-Osteritz,a Neil G. Pschierer,b Klaus Mu¨llenb and Peter Ba¨uerle*a
a Department Organic Chemistry II (Organic Materials and Combinatorial Chemistry),
University of Ulm, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
E-mail: peter.baeuerle@chemie.uni-ulm.de
b Max-Planck-Institute for Polymer Research, Ackermannstrasse 10, 55128, Mainz, Germany.
E-mail: muellen@mpip-mainz.mpg.de
Received 29th September 2004, Accepted 14th January 2005
First published as an Advance Article on the web 21st February 2005
A series of novel donor–acceptor systems, consisting of head-to-tail coupled oligo(3-hexylthiophene)s covalently
linked to perylenemonoimide, is described. These hybrid molecules, which differ by the length of the
oligothiophene units from a monothiophene up to an octathiophene, were created via effective palladium-catalyzed
Negishi and Suzuki cross-coupling reactions in good to excellent yields. The optical and electrochemical properties of
these compounds were determined and based on this series structure–property relationships have been established
which give vital information for the fabrication of photovoltaic devices. Because the synthesized
perylenyl–oligothiophenes distinguish themselves by a high absorption between 300 and 550 nm and an almost
complete fluorescence quenching of the perylene acceptor, they meet the requirements for organic solar cells.
at the solid–liquid interface which have been characterized
Introduction
by scanning tunnelling microscopy (STM)11 and exhibit very
Head-to-tail coupled poly(3-alkylthiophenes) (P3AT) are in-
tensively investigated (semi)conducting polymers due to well
established synthetic procedures and due to their outstanding
electronic and charge transport properties.1 In particular, the
understanding and control of their self-organizing properties
has led to materials with excellent charge carrier mobilities2
which allow their application in organic electronic devices. Spin-
coated composite films of P3ATs as electron donor and fullerene
derivatives as electron acceptor have been used successfully
as the active layer in plastic photovoltaic devices leading to
conversion efficiencies of around 3.5% which are among the
highest values for plastic solar cells.3
The synthesis and investigation of structurally defined con-
jugated oligomers,4 in particular oligothiophenes,5 as models
for the corresponding polymers and as materials in their own
right has led to valuable structure–property relationships and
applications in, e.g., organic field effect transistors and circuits,6
light emitting diodes7 or in solar cells based on small molecules.8
In this respect and as models for P3ATs, we recently reported
the effective solution- and solid-phase synthesis of a series
of monodisperse head-to-tail coupled oligo(3-alkylthiophenes)
(HT-O3AT) up to a dodecamer by transition metal-catalyzed
cross-coupling reactions of the Suzuki type.9 The investigation
of the physical properties resulted in the typical dependence
of the optoelectronic properties on the inverse of the oligomer
length.9a,10 Furthermore, as the polymers, the model oligomers
form well-organized self-assembled 2D-crystalline monolayers
promising charge carrier mobilities in thin film field-effect
transistors.12
In recent years, extensive studies on covalently linked p-
conjugated oligomer–acceptor dyad and triad molecules have
been performed in order to better understand the photo-
physics in photovoltaic applications. Combinations of olig-
othiophenes and C60,13 oligophenylenevinylenes and C60 or
14
oligophenylenevinylenes and perylenes15 were synthesized and
their electronic properties as well as electron transfer processes
investigated. Perylenes are widely used as chromophores, dyes
and pigments since they show outstanding photophysical prop-
erties including high absorptivities and fluorescence quantum
yields and at the same time are chemically and thermally
extremely stable.16
Perylenes have been implemented successfully as small
molecules in heterojunction solar cells acting as electron trans-
port material and represent an alternative to fullerenes which
are frequently used as electron acceptors.17
We report here the synthesis of a series of perylene-
functionalized head-to-tail coupled O3ATs (7–9,12,14,16). The
optical and electrochemical properties were investigated in
terms of their dependence on the oligothiophene chain length
which varies from one to eight thiophene units. The novel
type of p-donor p-acceptor dyad molecules was designed in a
way that the oligothiophene part should preserve the typical
charge transport and self-assembling properties in the solid
state, whereas the perylene unit, [N-(2,6-diisopropylphenyl)]-
perylene-3,4-dicarboximide, should provide high absorptivity
in the visible region as well as electron accepting properties.
With respect to the range of absorption, to the energy levels of
† Dedicated to Professor Dr Dr h.c. Franz Effenberger (University of
Stuttgart) on the occasion of his 75th birthday.
T h i s j o u r n a l i s
T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 5
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 9 8 5 – 9 9 5
9 8 5
©

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the frontier orbitals and bands in the solid state, respectively,
tailored materials for applications in photovoltaic devices are
expected from our novel hybrid molecules.
with n-BuLi and metal–metal exchange by zinc chloride. Then,
in a Negishi-type reaction under palladium catalysis it was
selectively cross-coupled with iodobromothiophene 3 to give the
next higher homologue, head-to-tail coupled and isomerically
pure trihexyl-terthiophene 5 in 38% yield.
Results and discussion
The smaller members of the homologous series of the
perylenyl oligothiophenes 7–9 were first synthesized by Negishi
coupling of brominated perylene-dicarboximide 6 and the
zincates of a-bromothiophenes 1,4 and 5. Reaction of monothio-
phene 1 led to perylenyl thiophene 7 in 62% yield, of bithiophene
4 to corresponding dye-functionalized bithiophene 8 in 76%
yield and of terthiophene 5 to the trimeric member of the series,
perylenyl-terthiophene 9 in 35% yield.
Because zincates of longer oligothiophenes are less stable, this
synthesis was rather less promising for the efficient preparation
of longer homologues. Therefore, we used a method recently
developed by us for the step-wise build-up of longer HT-
O3ATs in the solid phase.9b With the adaptation of this strategy,
perylenyl-oligothiophenes 8 (n = 2), 12 (n = 4), 14 (n = 6)
and 16 (n = 8) became accessible in excellent yields. From
bromobithiophene 4 the corresponding boronic acid pinacol
ester 10 was synthesized in 98% yield representing the crucial
module which then will be added to the growing oligothiophene
chain. Subsequent palladium-catalyzed Suzuki cross-coupling
of boronic ester 10 with 9-bromoperylene dicarboximide 6 gave
perylenyl bithiohene 8 in higher yield (90%) than obtained before
for the reaction of the corresponding zincate.
Synthesis
The straightforward preparation of HT-O3ATs typically de-
mands a substituent at one a-position. For example, a benzyl
ester group in the case of a liquid phase9a or a Merrifield
resin in a solid phase synthesis9b at the same time serve as
an anchoring and a removable protecting group providing
controlled chain growth at only one end of the oligothiophene.
A similar strategy was successfully used for the synthesis of
the novel donor–acceptor oligomers 7–9,12,14 and 16. The
electron-accepting perylene dye acts as the anchor at which the
electron-donating oligothiophene chain is stepwise elongated
in a modular iterative approach by Pd-catalyzed C–C cross
coupling reactions. Starting from 2-bromo-3-hexylthiophene
1,18 by lithiation with n-butyl lithium (n-BuLi) and reaction
with tri(isopropyl)borate and pinacol the corresponding 3-
hexylthiophene-2-boronic ester 2 has been synthesized in 92%
yield. Selective halogenation of 1 with N-iodosuccinimide (NIS)
on the other hand leads to 2-bromo-3-hexyl-5-iodothiophene
319 in 81% yield comprising two differently reactive halogen
functions.
For the iterative step-wise elongation of the oligothiophene
chain selective iodination at the reactive a-position of the
bithiophene moiety was achieved by a mercuration/iodination
sequence9b yielding iodinated derivative 11 in 97% yield. Subse-
quent Suzuki coupling with boronic ester 10 very efficiently gave
Suzuki-type cross coupling of both components 2 and 3 yields
dihexyl-bithiophene 49b in 90% as a central building block.
Following this synthetic strategy the overall yield of 4 could be
doubled with respect to a previous published synthesis.9b Bithio-
phene 4 was converted to the corresponding zincate via lithiation
9 8 6
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 9 8 5 – 9 9 5

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the next homologue, perylenyl-quaterthiophene 12, in 82% yield.
We continued this iodination/cross-coupling protocol to pro-
duce iodinated perylenyl-quaterthiophene 13 in 93%, perylenyl-
sexithiophene 14 in 75%, iodinated perylenyl-sexithiophene 15
in 94% and finally perylenyl-octathiophene 16 as the longest
representative in the series in 70% yield. With this, a whole
series of dye-functionalized HT-O3ATs, including one to eight
thiophene units were effectively synthesized.
Electronic properties
In homologous series of oligomers, their properties can be
investigated as a function of chain length. Therefore, clear
structure–property relationships become observable. For conju-
gated oligomeric systems it has been shown experimentally and
theoretically that typically the (electronic) properties linearly
depend on the inverse of the conjugated chain length.11 For
the series of dye-functionalized HT-O3ATs 7–9,12,14 and 16
optical and redox properties were determined and an energy level
diagram of the frontier orbitals was deduced from the data set.
The absorption and emission maxima, fluorescence quantum
yields and the optical energy gaps for the complete series are
given in Table 1 and compared to the individually synthesized
parent building blocks. The energy gaps were determined from
the onset of the longest wavelength absorption band of the
hybrid molecules.
Fig. 1 UV-Vis spectra of the perylenyl-oligothiophenes 7–9,12,14 and
16 and reference compound PDCI in chloroform (c = 5 × 10−5 mol l−1
)
(full lines). Emission spectra of PDCI and compounds 7–9 are added
(dashed lines). The other compounds are omitted for clarity.
7–9,12,14 and 16 induces a change in the vibronic distribution
of the p–p* band. With growing oligothiophene chain length a
red-shift of this band (Dk = 14–22 nm) can be determined by
using the parameter “full width at half maximum” (FWHM).21
Consequently, an increased tendency to a tailing of the curve
on the low energy side of the p–p* band is clearly visible. A
detailed analysis has been made by calculating the difference
absorption spectra of all perylenyl-oligothiophenes 7–9,12,14–
16 and reference compound PDCI. As a result a new weak
absorption band in the regime of 534–538 nm irrespective of the
oligothiophene chain length appears. We attribute this band to
a charge-transfer (CT) transition according to the fluorescence
results discussed below.22
Absorption and emission spectra were measured in chloro-
form (c = 5 × 10−5 mol l−1) (Fig. 1) and in the solid state as spin-
coated thin films (Fig. 2). N-(2,6-Diisopropylphenyl)perylene-
3,4-dicarboximide (PDCI) was taken as a reference which shows
three absorption bands: the most intense is located at k1
=
265 nm, a structured very weak band at k2 = 355 nm (not
included in Table 1) and the well structured, very intense p–
p* transition band at k3 = 486 nm with a shoulder at 509 nm
which reflects a rather planar aromatic system. The coupling
of thiophene units to the parent perylene system in compounds
In the absorption spectra, starting with perylenyl-bithiophene
8 at 300 nm a third band due to the p–p* transition of the
oligothiophene moiety arises. With increasing chain length of
the oligothiophene, this band gradually becomes more intense
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 9 8 5 – 9 9 5
9 8 7

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Fig. 2 Solid-state UV-Vis spectra of thin films of the perylenyl-
oligothiophenes 7–9,12,14 and 16 spin-coated on glass (normalized to
the maximum of the perylene absorption band).
and red-shifted finally reaching k2 = 422 nm for the perylenyl-
octithiophene 16. The position of this band compares well
to the absorption maxima of the parent non-functionalized
HT-O3HTs20 indicating that the two chromophoric subunits
in the dyads are rather electronically decoupled due to steric
interactions of the perylene system with the adjacent 3-
hexylthiophene unit. In the same line, the optical band gap is
gradually diminished on going from PDCI (DE = 2.30 eV) to
perylenyl-quaterthiophene 12 (DE = 2.13 eV) and then remains
constant with increasing oligothiophene length.
Corrected emission spectra for the whole series of compounds
were measured in chloroform (Table 1, Fig. 1). While the
emission band of the reference compound PDCI (kmax = 539
nm) is very intense (fluorescence quantum yield of φ = 90%23)
and shows a vibronic splitting, the hybrid compounds exhibit
less structured and broader emission bands whose maxima
with respect to PDCI are significantly shifted to the red. With
increasing oligothiophene length, the intensity of the emission
bands and the quantum yields progressively decrease to 67%
for perylenyl-monothiophene 7, to 37% for bithiophene 8, to
21% for terthiophene 9 and to values around 1% for the
longer homologues 12,14 and 16 when excited at 480 nm.
Excitation at wavelengths corresponding to the oligothiophene
absorption (300–400 nm) results in a weak fluorescence in
the regime of the perylene emission, whereas this from the
oligothiophene part is completely quenched. As a reference,
the pure non-functionalized HT-O3ATs show a structured
emission whose intensity increases with the enlargement of
the conjugated backbone.23 For the smaller homologues of
this series, 7 and 8, the emission band is strongly red-shifted
(kem
= 602 and 656 nm) with respect to PDCI (kem
=
FWHM
FWHM
562 nm).24 This trend is reversed for the longer homologues
finally leading to kemFWHM = 596 nm in the case of octathiophene
16. Perylenyl-oligothiophenes 7–9 were subjected to a more
detailed study concerning the influence of the solvent polarity
on the emission properties. For compounds 7 and 8 we find
a positive solvatochromism which is a clear indication that
the observed emission band has a CT character. However, for
perylenyl-terthiophene 9 we observe a much more complicated
behaviour suggesting other competitive relaxation processes.24
These results are in accordance with an expected photo-induced
electron transfer from the oligothiophene donor to the perylene
acceptor which already has been investigated for derivatives 7
and 8.25
Thin films of the hybrid molecules 7–9,12,14 and 16 (thick-
nesses 34–50 nm) were obtained by spin-coating of corre-
sponding toluene solutions (c = 20 mg ml−1) onto a glass
substrate (Fig. 2). Absorption spectra in the solid state show
the same trends and compared to the solution spectra in
9 8 8
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 9 8 5 – 9 9 5

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general a broadening and red-shift of the bands are visible and
consequently lead to smaller band gaps (DDEopt ≈ 0.10 eV).
The displacement is small for the absorption band of the
perylene moiety (Dk3 = 4–12 nm), but rather pronounced for the
oligothiophene chains and steadily increasing with increasing
chain length (Dk2 = 4–42 nm). With respect to applications in
solar cells, in particular the absorption behaviour of the longer
members 14 and 16 in the series cover a broad range of the visible
spectrum (300–700 nm) with high optical densities.
particular of great importance to ascertain the absolute energetic
positions of the HOMOs and LUMOs which can be derived
from redox potentials. Oxidation and reduction potentials of
the perylenyl-oligothiophenes 7–9,12,14 and 16 were determined
by cyclic voltammetry (CV) in dichloromethane (c = 1 ×
10−3 mol l−1) using tetrabutylammonium hexafluorophosphate
(TBAHFP) as the supporting salt (Fig. 3). Reduction and
oxidation potentials are given versus the internal standard
ferrocene–ferricenium (Fc/Fc+) and are compared to the refer-
ence compound PDCI and the parent non-functionalized HT-
O3ATs which facilitates the assignment of the individual redox
waves. The potential difference between the onset of the first
oxidation and the first reduction wave gives the electrochemically
determined band gap DECV which can be compared to the
optical band gap DEopt (Table 2). The peryleneimide PDCI
Electrochemical properties
Optical measurements provide an estimation of the energy dif-
ference of the frontier orbitals and therefore of the (optical) band
gap DEopt. However, with respect to solar cell applications it is in
Fig. 3 Electrochemical characterization of the perylenyl-oligothiophenes 7–9,12,14 and 16 in dichloromethane–TBAHFP (0.1 M), scan speed
100 mV s−1, potentials vs. Fc/Fc+. Red bars correspond to redox processes of the perylene unit, blue bars to those of the oligothiophene unit.
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 9 8 5 – 9 9 5
9 8 9

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Table 2 Electrochemical properties of the perylenyl-oligothiophenes 7–9,12,14,16 and PDCI, c = 1 × 10−3 mol l−1, in dichloromethane–TBAHFP
(0.1 M) vs. Fc/Fc+ at 100 mV s−1 (P denotes perylene, OT oligothiophene)
Compound
E◦ (P)/V
E◦ (P)/V
E◦ (P)/V
E◦ (OT)/V
E◦ (OT)/V
E◦ (OT)/V
E◦ (OT)/V
DECVa/eV
red2
red1
ox1
ox1
ox2
ox3
ox4
PDCI
7 (1T)
8 (2T)
9 (3T)
12 (4T)
14 (6T)
16 (8T)
−1.95
−1.88
−1.87
−1.87
−1.87
−1.88
−1.87
−1.46
−1.43
−1.42
−1.42
−1.42
−1.42
−1.42
0.95
0.88
1.06
1.04
1.17
1.01
0.93
2.24
2.14
2.02
1.80
1.63
1.58
1.54
1.21b
0.71b (0.83)c
0.52
1.20b (1.24)c
0.84
0.43 (0.43)d
0.31 (0.30)e
0.27 (0.25)f
0.71 (0.85)d
0.45 (0.43)e
0.38 (0.34)f
1.19b (1.20)e
0.78 (0.79)f
1.19b (1.21)f
a Determined by DECV = Eꢀox1–Eꢀred1 (Eꢀ is the onset potential at which the redox process starts). b Irreversible redox process, E◦ determined at I◦
f octahexyl-octathiophene.20
=
0.855 × Ip.26 c Redox potentials for the parent non-functionalized dihexyl-bithiophene, d tetrahexyl-quaterthiophene, e hexahexyl-sexithiophene,
exhibits two reversible reduction waves (E◦
= −1.46 V,
ox1(P)
red1(P)
E◦red2(P) = −1.95 V) and one reversible oxidation wave (E◦
=
0.95 V), indicating the formation of stable radical anions,
dianions, and radical cations, respectively. As a general trend, for
the perylenyl-oligothiophenes 7–9,12,14 and 16 both reduction
processes are slightly facilitated and shifted positively by only
DE◦ ≤ 80 mV, but are independent of the oligothiophene chain
length. The successive coupling of 3-hexylthiophene units to
the parent perylene system leads to more complex CVs in the
positive potential regime. This is due to the interference of
the perylene with the oligothiophene oxidation processes. The
detailed analysis of the various redox transitions in comparison
to the CVs of the non-functionalized HT-O3ATs which allow
us an assignment of the individual redox waves, clearly reveals
that a complicated mutual influence of the two electrophoric
subunits exists.
In the case of the 1T-derivative 7 the first redox wave at
E◦
= 0.88 V corresponds to the oxidation of the perylenyl
ox1(P)
Fig. 4 Correlation of redox potentials (E◦
and E◦ox2) versus
moiety to the radical cation. In comparison to the parent
compound PDCI this value is slightly shifted to the negative
(DE◦ = 70 mV) because the monothiophene unit which is
ox1
reciprocal chain length of the oligothiophene unit (1/nT) of the
perylenyl-oligothiophenes 7–9,12,14 and 16 (blue squares) in compar-
ison to the corresponding non-functionalized oligo(3-alkylthiophenes)
(red squares).
(irreversibly) oxidized at quite higher potential (E◦
=
ox1(OT)
1.21 V) is therefore neutral and increases the overall conjugation.
This conclusion is further supported by the fact that also the
oxidation of the monothiophene unit is facilitated and shifted
to negative potentials compared to pristine 3-hexylthiophene
the hexamer 14, the same situation is observed whereby due to
the more extended p-system all three potentials lie negative in
comparison to those of the tetramer 12. The oxidation of the
oligothiophene chain to the radical trication is observable at
(for comparison E◦ = 1.56 V for 3-methylthiophene).27 With
ox1
increasing chain length of the oligothiophene, the first oxidation
potential of this unit is gradually shifted to the negative (to
E◦
= 1.19 V. Finally, in perylenyl-octathiophene 16, the
ox3(OT)
E◦
= 0.27 V for octamer 16) and successively an increased
four waves are again shifted to the negative and an additional
redox process at E◦ox4(OT) = 1.19 V arises due to the formation of
oligothienyl tetracations.
ox1(OT)
number of redox processes occur (up to four for 16). This is
a well known behaviour in homologous series of conjugated
oligomers28 and has been analyzed in detail for the series of the
non-functionalized HT-O3ATs.9a In contrast to 1T-derivative
7, in perylenyl-2T 8 the oxidation of the bithiophene unit
A useful approach to elucidate structure–property relation-
ships in oligomer series is the correlation of physical properties
with the inverse of the conjugated chain length. Typically a linear
behaviour is found for chain lengths up to 9–11 repeating units,
whereas for longer chains, a beginning saturation of the effective
conjugation is identified.9a,10a In this respect, we correlated the
first and second oxidation potential of the oligothiophene units
in the hybrid systems 7–9,12,14 and 16 with the inverse of the
chain length of the corresponding oligothiophene unit (1/nT)
(Fig. 4). A linear behaviour is obtained for both oxidation
processes (blue squares) whereby the straight lines approach
each other for increasing chain lengths. The slopes of the
regression lines are less steep compared to those of the parent
O3ATs (red squares) indicating that in the hybrid systems the
subunits are not fully decoupled and the perylene is slightly
contributing to the overall conjugation. As expected, this
influence becomes less pronounced for longer oligothiophene
chains.
occurs at a lower potential (E◦
= 0.71 V) than that of
ox1(OT)
the perylene unit (E◦
= 1.06 V) which in turn is shifted to
ox1(P)
the positive (DE◦ = 0.18 V) because the oligothiophene unit is
now positively charged (radical cation) and withdraws electron
density from the perylene system. In the case of homologue 9,
the first oxidation process (E◦ox1(OT) = 0.52 V) is clearly attributed
to the formation of a terthiophene radical cation. However,
the assignment of the second and third oxidation waves which
lie quite close could only be performed with the help of a
correlation of the redox potentials with the inverse chain length
(1/n) (Fig. 4). The 1/n plot shows us that the oxidation wave
at E◦
= 0.84 V should correspond to the formation of a
ox2(OT)
terthiophene dication whereas that at E◦
= 1.04 V belongs
ox1(P)
to the oxidation of the perylenyl moiety. For perylenyl-4T 12
the situation is unambiguous and we see two well-pronounced
reversible redox waves for the oxidation of the oligothiophene
The band gaps DECV were determined from the CVs by taking
the difference between the onset of the first oxidation and
reduction process (Table 2). The band gap gradually becomes
smaller when going from reference compound PDCI (2.24 eV)
(E◦
= 0.43 V, E◦
= 0.71 V) to the radical cation and
ox1(OT)
ox2(OT)
the dication, respectively. Consequently, the oxidation of the
perylenyl unit is shifted to the positive (E◦
= 1.17 V). For
ox1(P)
9 9 0
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 9 8 5 – 9 9 5

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Table 3 Absolute MO energies of the perylenyl-oligothiophenes 7–9,12,14,16 in comparison to PDCI with respect to the vacuum level (P denotes
perylene, OT oligothiophene)
Compound LUMO − 1/eV LUMO/eV HOMO/eV HOMO − 1/eV HOMO − 2/eV HOMO − 3/eV HOMO − 4/eV Ega/eV
PDCI
7 (1T)
8 (2T)
9 (3T)
12 (4T)
14 (6T)
16 (8T)
−2.85 (P)
−2.92 (P)
−2.93 (P)
−2.93 (P)
−2.93 (P)
−2.92 (P)
−2.93 (P)
−3.34 (P)
−3.37 (P)
−3.38 (P)
−3.38 (P)
−3.38 (P)
−3.38 (P)
−3.38 (P)
−5.75 (P)
−5.68 (P)
2.41
2.31
2.14
1.93
1.85
1.73
1.68
−6.01 (OT)
−5.51 (OT) −5.86 (P)
−5.32 (OT) −5.64 (OT)
−5.23 (OT) −5.51 (OT)
−5.11 (OT) −5.25 (OT)
−5.07 (OT) −5.18 (OT)
−6.01 (OT)
−5.84 (P)
−5.97 (P)
−5.81 (P)
−5.58 (OT)
−5.99 (OT)
−5.73 (P)
−5.99 (OT)
a Determined by Eg = ELUMO − EHOMO
.
to perylenyl-octathiophene 16 (1.54 eV) reflecting the decreas-
ing oxidation potential of the oligothiophene subunit. If one
compares DECV with the optically determined band gap DEopt
only the values for PDCI and the perylenyl monothiophene
7 are in good agreement, whereas for the higher homologues
DECV is substantially smaller. While the reduction is always
due to the perylene moiety, the oxidation only corresponds
to the perylene unit for PDCI and 7 whereas for the longer
homologues it is correlated with the oligothiophene units. In
contrast, the optical determined band gap is always representing
the electronic properties of the perylene unit for all compounds
in the series. Therefore, it can be concluded that these donor–
acceptor systems consist of almost perfectly separated subunits
with only marginal conjugation between the oligothiophene and
the perylene moieties.
LUMOs of the hybrid systems are energetically higher than
both the LUMO of fullerene derivative [6,6]-phenyl-C61-butyric
acid methyl ester (PCBM) and the work function of aluminium,
making them suitable for the manufacturing of photovoltaic
devices. First experiments confirm a possible application of this
novel type of hybrid materials in organic solar cells. In a stan-
dardized setup, bulk-heterojunction devices were manufactured
consisting of a PEDOT:PSS-covered ITO cathode, a 1 : 4 mixture
of perylenyl-quaterthiophene12 or octathiophene 16 and PCBM
as photoactive layer and a LiF-covered Al anode. These devices
exhibited good photoresponses at high open-circuit voltages VOC
of 0.94 V and reasonable power conversion efficiencies, which
have been calculated for standard test conditions (AM 1.5G,
1000 W m−2) (12: g = 0.33%; 16: g = 0.48%).31
Conclusion
MO energies
We synthesized a series of perylene-functionalized head-to-tail
coupled oligo(3-hexylthiophenes) 7–9,12,14 and 16. The novel
donor–acceptor hybrid systems consist of an oligothiophene in
which the chain length is systematically varied up to an octamer
(donor) and a covalently linked perylene-3,4-dicarboximide
(acceptor) and were obtained by palladium-catalysed cross-
coupling reactions in excellent yields. Detailed investigations
of the electronic properties of the series in solution and in the
solid state clearly revealed that there is a systematic change in
the spectral range of absorption and emission, the fluorescence
quantum yield in solution, redox potentials and energy gaps.
Clear structure–property relationships of the novel type of p-
donor p-acceptor dyad molecules provide a valuable data set
for their application in organic solar cells. The fabrication
and characterization of the corresponding photovoltaic devices
based on blends of selected perylenyl-oligothiophenes with
fullerenes revealed energy conversion efficiencies up to 0.5%
under a simulated terrestrial sun spectrum.
MO energy diagrams are very helpful for the construction and
understanding of organic devices in which the fundamental
processes are decisively determined by charged states and their
corresponding energy level in the active, organic layer.29 In order
to calculate the absolute energies of the HOMO and LUMO
levels of PDCI and the perylenyl-oligothiophenes 7–9,12,14
and 16 with respect to the vacuum level, the redox data are
standardized to the ferrocene–ferricenium couple which has a
calculated absolute energy of −4.8 eV.30 The band gap energies
Eg then result from the energy difference between the HOMO
and the LUMO levels. The MO energy levels as well as the band
gap energies are listed in Table 3 and a corresponding energy
level diagram is depicted in Fig. 5. Very clearly it can be seen in
the energy diagram that the HOMO–LUMO band gap decreases
with increasing chain length of the oligothiophene unit which is
mainly due to the constant lowering of the HOMO energy level
whereas the LUMO level remains rather constant.
Experimental
General procedures
1H-NMR spectra were recorded in CDCl3 on a Bruker AMX
400 at 400 MHz. 13C-NMR spectra were recorded in CDCl3 on
a Bruker AMX 400 at 100 MHz. Chemical shifts are denoted in
d units (ppm), and were referenced to internal tetramethylsilane
(0.0 ppm). The splitting patterns are designated as follows: s
(singlet), d (doublet), dd (double doublet), t (triplet), q (quartet),
and m (multiplet) and the assignments are Pery (perylene),
1
Ph, (phenyl), Th (thiophene) for H-NMR. Mass spectra were
recorded with a Varian Saturn 2000 GC-MS and with a MALDI-
TOF MS Bruker Reflex 2 (dithranol as the matrix). Elemental
analyses were performed on a Perkin-Elmer EA 2400. Melting
points were determined with a Bu¨chi B-545 melting point
apparatus and are not corrected. Gas chromatography was
carried out using a Varian CP-3800 gas chromatograph. HPCL
analyses were performed on a Shimadsu SCL-10A equipped
with a SPD-M10A photodiode array detector and a SC-10A
Fig. 5 MO energy level diagram scheme for the perylenyl-oligothio-
phenes 7–9,12,14 and 16 and reference compound PDCI.
The work function of a PEDOT-covered ITO electrode lies
higher in energy than the HOMOs of the donor–acceptor
systems, allowing holes to be easily injected from the ITO
cathode into the photoactive layer. On the other side, the
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 9 8 5 – 9 9 5
9 9 1

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solvent delivery system using a LiChrosphor column (Silica 60,
5 lm, Merck). Thin-layer chromatography was carried out on
Silica Gel 60 F254 aluminium plates (Merck). Developed plates
were dried and examined under a UV lamp. Preparative column
chromatography was carried out on glass columns of different
sizes packed with silica gel Merck 60 (40–63 lm). UV/Vis
spectra were taken on a Perkin-Elmer Lambda 19 in 1 cm
cuvettes. Thin uniform films for solid-state spectra were obtained
on a POLOS wafer spinner from a toluene solution (20 mg ml−1)
at 5000 rpm onto a glass substrate. Fluorescence spectra were
measured with a Perkin-Elmer LS 55 in 1 cm cuvettes. Fluores-
cence quantum yields were determined with respect to N-(2,6-
diisopropylphenyl)perylene-3,4-dicarboximide (PDCI) (U = 0.9
in chloroform23) at an excitation wavelength of 480 nm. Cyclic
voltammetry experiments were performed with a computer-
controlled EG & G PAR 273 potentiostat in a three-electrode
single-compartment cell (5 ml). The platinum working electrode
consisted of a platinum wire sealed in a soft glass tube with
a surface of A = 0.785 mm2, which was polished down to
0.5 lm with Buehler polishing paste prior to use in order to
obtain reproducible surfaces. The counter electrode consisted of
a platinum wire and the reference electrode was an Ag/AgCl
secondary electrode. All potential were internally referenced
to the ferrocene–ferricenium couple.30 For the measurements
concentrations of 10−3 mol l−1 of the electroactive species
were used in freshly distilled and deaerated dichloromethane
(Lichrosolv, Merck) and 0.1 M tetrabutylammonium hexafluo-
rophosphate (TBAHFP, Fluka) which was twice recrystallized
from ethanol and dried under vacuum prior to use. Solvents
and reagents were purified and dried by usual methods prior
to use and typically used under inert gas atmosphere. The
following starting materials were purchased and used without
further purification: n-butyllithium (n-BuLi, Merck) was a 1.6 M
solution in n-hexane, N-iodosuccinimide (NIS, ABCR), pinacol
(Aldrich), tri(isopropyl)borate (Merck), zinc chloride (Merck),
iodine (Merck), 9-bromo-N-(2,6-diisopropylphenyl)perylene-
yield with a purity of 95% (GC) and was used without further
1
purification. H-NMR (CDCl3): d = 7.50 (d, J = 4.7 Hz, 1H,
5-H), 7.04 (d, J = 4.7 Hz, 1H, 4-H), 2.91 (t, J = 7.6 Hz, 2H,
a-H), 1.70–1.53 (m, 2H, b-H), 1.40–1.30 (m, 18H, –CH –,
2
–CH ), 0.91 (t, J = 6.9 Hz, 3H, –CH ); 13C-NMR (CDCl3):
3
3
d = 154.58, 131.13, 128.17, 119.63, 83.39, 31.64, 31.54, 30.41,
30.00, 28.90, 29.29, 28.83, 27.79 24.67, 22.49, 13.99; MS (EI):
m/z [M+] = 294.
5-Bromo-4,3ꢀ-dihexyl-2,2ꢀ-bithiophene (4). To a solution of
bromoiodothiophene 3 (5.29 g, 18 mmol) in DME (80 ml)
[Pd(PPh3)4] (835 mg, 0.72 mmol) was added. After the mixture
was stirred for 10 min at room temperature thiophene boronic
ester 2 (6.71 g, 18 mmol) and a 1 M aqueous solution of sodium
hydrogencarbonate (54 ml) were added. The reaction mixture
was refluxed under vigorous stirring for 24 hours. Then it was
poured into water (200 ml) and the organic phase was separated
while the aqueous phase was extracted with ether (3 times 50 ml).
The combined extracts were dried over sodium sulfate and the
solvent was removed by rotary evaporation. The crude product
was purified by flash column chromatography (SiO2, petrol
ether) to yield bithiophene 4 (6.7 g, 90%) as a yellow liquid.
1H-NMR (CDCl3): d = 7.18 (d, J = 5.2 Hz, 1H, 5ꢀ-H), 6.93
(d, J = 5.2 Hz, 1H, 4ꢀ-H), 6.81 (s, 1H, 3-H), 2.73 (t, J = 7.8 Hz,
ꢀ
2H, a -H), 2.58 (t, J = 7.7 Hz, 2H, a-H), 1.68–1.59 (m, 4H,
b,bꢀ-H), 1.40–1.30 (m, 12H, –CH –), 0.94–0.89 (m, 6H, –CH ).
2
3
5-(4,3ꢀ-Dihexyl-2,2ꢀ-bithienyl-5-yl)-4,4,5,5-tetramethyl-[1,3,2]-
dioxaborolane (10). To bithiophene 4 (1 g, 2.4 mmol) in THF
◦
(5 ml) at −80 C was added n-BuLi (1.6 ml, 2.5 mmol). After
stirring at −80 ◦C for one hour tri(isopropyl)borate (500 mg,
2.7 mmol) was added and the solution was allowed to warm up
to room temperature. After an additional two hours at room
temperature pinacol (340 g, 2.9 mmol) was added and the
resulting suspension was stirred overnight at room temperature.
Next, the THF was taken off and the residue was dissolved
in petrol ether. After the white precipitate was filtered off the
resulting solution was filtrated over neutral aluminium oxide.
The solvent was taken off and the product was dried in vacuum.
Dioxaborolane 10 was obtained as a brownish oil (1.1 g, 98%)
yield with a purity of 95% (GC). It was used without further
3,4-dicarboximide
6
(BASF). 2-Bromo-3-hexylthiophene18
1 and tetrakis(triphenylphosphino)palladium(0)32 [Pd(PPh3)4]
were prepared according to literature procedures.
Synthesis
1
purification. H-NMR (CDCl3): d = 7.14 (d, J = 5.2 Hz, 1H,
5ꢀ-H), 7.02 (s, 1H, 3-H), 6.91 (d, J = 5.2 Hz, 1H, 4ꢀ-H), 2.85
2-Bromo-3-hexyl-5-iodothiophene (3). 2-Bromo-3-hexylthio-
phene 1 (22.25 g, 90 mmol) was dissolved in acetic acid (10 ml).
After addition of NIS (20.25 g, 90 mmol) the resulting
suspension was stirred vigorously for 4 h at 100 ◦C under light
protection. Then the reaction mixture was poured into water
(50 ml) and the organic layer was taken off while the water phase
was extracted with dichloromethane. The combined organic
phases were washed with 1 M sodium hydroxide solution
(20 ml), water (20 ml), brine (20 ml) and were dried with
MgSO4. After the solvent was removed by rotary evaporation
bromoiodothiophene 3 was obtained by distill◦ation under
vacuum as a yellow liquid (27.25 g, 81%). Bp 105 C (5 × 10−3
ꢀ
(t, J = 7.6 Hz, 2H, a -H), 2.77 (t, J = 7.8 Hz, 2H, a-H),
1.40–1.25 (m, 28H, –CH –, –CH ), 0.93–0.85 (m, 6H, –CH );
2
3
3
13C-NMR (CDCl3): d = 154.31, 149.33, 141.32, 139.07, 130.37,
129.32, 128.45, 123.05, 82.90, 31.01, 30.88, 30.24, 30.03, 29.82,
29.63, 28.80, 28.56, 28.50, 28.30, 27.23, 24.12, 21.94, 13.45,
13.41; MS (EI): m/z [M+] = 460.
5-Bromo-4,3ꢀ,3ꢀꢀ-trihexyl-2,2ꢀ;5,2ꢀꢀ-terthiophene (5). Bithio-
phene 4 (829 mg, 2 mmol) was dissolved in THF (5 ml). At
−80 ◦C n-BuLi (1.32 ml, 2.1 mmol) was added dropwise and
the resulting solution was stirred for one hour at −80 ◦C. After
addition of zinc chloride (2.1 mmol as a 1 M solution in THF)
the solution was allowed to warm up to room temperature. Next,
this reaction mixture was transferred to a solution of 2-bromo-3-
hexyl-5-iodothiophene 3 (783.5 mg, 2.1 mmol) and [Pd(PPh3)4]
(232 mg, 0.2 mmol) in THF (5 ml) via cannula. The resulting
orange solution was stirred at room temperature for 24 h under
light protection. Then the reaction mixture was poured into
water (20 ml) and the organic layer was taken off while the water
phase was extracted with dichloromethane (three times 20 ml).
The combined organic phases were dried with MgSO4 and the
solvent was removed by rotary evaporation. The crude product
was purified by flash column chromatography (SiO2, petrol
ether–dichloromethane 10 : 1). Terthiophene 5 was obtained
as an orange viscous liquid (440 mg, 38%). 1H-NMR (CDCl3):
d = 7.12 (d, J = 5.1 Hz, 1H, 5ꢀꢀ-H), 6.93 (s, 1H, 4ꢀ-H), 6.90 (d,
J = 5.2 Hz, 1H, 4ꢀꢀ-H), 6.86 (s, 1H, 3-H), 2.73 (t, J = 7.8 Hz,
1
mbar); H-NMR (CDCl3): d = 6.99 (s, 1H, 4-H), 2.55 (t, J =
7.6 Hz, 2H, a-H), 1.61–1.52 (m, 2H, b-H), 1.28–1.29 (m, 6H,
–CH –), 0.92 (t, J = 6.7 Hz, 3H, –CH ).
2
3
2-(3-Hexyl-thien-2-yl)-4,4,5,5-tetramethyl-[1,3,2]dioxaboro-
lane (2). To thiophene 1 (4.94 g, 20 mmol) in THF (20 ml)
at −80 ◦C was added n-BuLi (13.2 ml, 21 mmol). After
stirring at −80 ◦C for one hour tri(isopropyl)borate (4.14 g,
22 mmol) was added and the solution was allowed to warm up
to room temperature. After an additional two hours at room
temperature, pinacol (2.84 g, 24 mmol) was added and the
resulting suspension was stirred over night at room temperature.
Next, THF was taken off and the residue was dissolved in
petrol ether. After the white precipitate was filtered off the
resulting solution was filtered over neutral aluminium oxide.
The solvent was taken off and the product was dried in vacuum.
Dioxaborolane 2 was obtained as a brownish oil (5.4 g, 92%)
ꢀ
ꢀꢀ
4H, a ,a -H), 2.61 (t, J = 7.8 Hz, 2H, a-H), 1.67–1.57 (m, 6H,
9 9 2
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 9 8 5 – 9 9 5

View Article Online
b–bꢀꢀ-H), 1.35–1.25 (m, 18H, –CH –), 0.94–0.85 (m, 9H, –CH );
129.19, 128.11, 127.30, 127.15, 126.73, 123.93, 123.66, 122.97,
120.98, 120.93, 120.22, 120.14, 31.60, 31.40, 30.63, 30.38, 29.29,
29.17, 29.10, 28.95, 28.83, 23.96, 22.55, 22.40, 14.02, 13.91; MS
(MALDI-TOF): m/z [M + H+] = 813; elemental analysis: calcd
(%) for C54H55NO2S2: C 79.66, H 6.81, N 1.72; found C 79.62,
H 6.95, N 1.76.
2
3
13C-NMR (CDCl3): d = 143.53, 139.37, 135.88, 131.02, 129.87,
127.33, 123.38, 121.97, 119.89, 31.71, 31.68, 30.71, 30.53, 30.40,
29.23, 20.17, 29.02, 22.64, 14.10, 14.07; MS (EI): m/z [M+] =
579; elemental analysis: calcd (%) for C30H43BrS3: C 62.15, H:
7.48, S: 16.59; found C 62.36, H: 7.42, S: 16.71.
5-([N-(2,6-Diisopropylphenyl)]-9-perylenyl-3,4-dicarboximide)-
4,3ꢀ,3ꢀꢀ-trihexyl-2,2ꢀ;5ꢀ,2ꢀꢀ-terthiophene (9). Following the
general procedure terthiophene 5 (203 mg, 0.35 mmol) in
THF (10 ml) was converted into the corresponding zincate by
subsequently adding n-BuLi (0.22 ml, 0.35 mmol) and zinc
chloride (50 mg, 0.37 mmol) at −80 ◦C. The resulting zincate was
reacted with 9-bromo-N-(2,6-diisopropylphenyl)perylene-3,4-
dicarboximide 6 (213 mg, 0.37 mmol) and [Pd(PPh3)4] (41 mg,
0.035 mmol) to give 9 (120 mg, 35%) as a black solid after flash
columnchromatography(SiO2, dichloromethane–petrol ether 2 :
1). Mp 98–99 ◦C; 1H-NMR (CDCl3): d = 8.68 (d, J = 8.0 Hz,
2H, Pery-1H,6H), 8.54–8.49 (m, 4H, Pery-2H,5H,7H,12H),
8.00 (d, J = 8.3 Hz, 1H, Pery-8H), 7.70 (d, J = 7.8 Hz, 1H,
Pery-10H), 7.66 (t, J = 7.8 Hz, 1H, Pery-11H), 7.48 (t, J =
7.8 Hz, 1H, 1H, Ph-4H), 7.34 (d, J = 7.8 Hz, 2H, Ph-3H,5H),
7.18 (d, J = 5.2 Hz, 1H, Thꢀ-5H), 7.14 (s, 1H, Th-3H), 6.98
(s, 1H, Thꢀ-4H), 6.95 (d, J = 5.3 Hz, 1H, Thꢀ-4H), 2.80–2.65
General procedure for the preparation of the perylenyl-oligo-
thiophenes (7–9) via Negishi cross coupling. To a 0.1 M solution
of the bromothiophene in dry THF at −80 ◦C was added n-BuLi
(1.02 equivalents). After stirring at −80 ◦C for one hour zinc
chloride (1.05 equivalents, 1 N solution in THF) was added and
the solution was allowed to warm up to room temperature. Next,
this reaction mixture was transferred to a suspension of PDCI-
Br 6 (1.1 equivalents, 1 N solution in THF) and [Pd(PPh3)4] (10
mol%) in THF via cannula. The resulting red suspension was
stirred at 65 ◦C for 24 h. Then the solvent was taken off and the
crude product was purified by flash column chromatography.
2-([N-(2,6-Diisopropylphenyl)]-9-perylenyl-3,4-dicarboximide)-
3-hexyl-thiophene (7). Following the general procedure, 2-
bromo-3-hexylthiophene 1 (136 mg, 0.55 mmol) in THF (10 ml)
was converted to the corresponding zincate by subsequently
adding n-BuLi (0.35 ml, 0.56 mmol) and zinc chloride (82 mg,
0.6 mmol) at −80 ◦C. The resulting zincate was reacted with
9-bromo-N-(2,6-diisopropylphenyl)perylene-3,4-dicarboximide
6 (280 mg, 0.5 mmol) and [Pd(PPh3)4] (58 mg, 0.05 mmol)
to give 7 (200 mg, 62%) as a red solid after flash column
chromatography (SiO2, dichloromethane–petrol ether 2 : 1).
ꢀ
ꢀꢀ
(m, 6H, Ph–CH–(CH3)2, Th–a ,a -CH ), 2.44 (t, J = 7.6 Hz,
2
2H, Th–a-CH ), 1.81–1.65 (m, 4H, Th–bꢀ,bꢀꢀ-CH ), 1.65–1.57
2
2
(m, 2H, Th–b-CH ), 1.57–1.15 (m, 18H, –CH –), 1.22 (d, J
2
2
= 6.8 Hz, 12H, Ph–CH–(CH )2), 0.93 (m, 6H, Thꢀ,Thꢀꢀ–CH ),
3
3
0.77 (t, J = 6.9 Hz, 3H, Th–CH ); 13C-NMR (CDCl3): d =
3
◦
1
Mp 145–146 C; H-NMR (CDCl3): d = 8.59 (d, J = 8.0 Hz,
2H, Pery-1H,6H), 8.35–8.25 (m, 4H, Pery-2H,5H,7H,12H),
7.87 (d, J = 8.3 Hz, 1H, Pery-8H), 7.61 (d, J = 7.7 Hz, 1H,
Pery-10H), 7.56–7.65 (m, 3H, Pery-11H, Ph-4H, Th-3H), 7.40
(d, J = 7.7 Hz, 2H, Ph-3H,5H), 7.16 (d, J = 5.2 Hz, 1H,
Th-4H), 2.88 (sep, J = 6.8 Hz, 2H, Ph–CH–(CH3)2), 2.48
(t, J = 7.6 Hz, 2H, Th–a-CH ), 1.60–1.53 (m, 2H, Th–b-CH ),
163.88, 145.64, 141.84, 139.74, 139.60, 137.51, 137.24, 135.80,
134.89, 134.14, 133.85, 132.00, 131.97, 130.45, 130.37, 130.30,
130.21, 130.01, 1129.37, 129.35, 129.31, 128.71, 128.19, 127.22,
127.09, 126.85, 123.96, 123.90, 123.55, 123.03, 121.04, 120.97,
120.35, 120.27, 31.57, 31.37, 30.53, 30.46, 30.34, 29.58, 29.38,
29.20, 29.13, 29.11, 29.04, 28.91, 28.79, 23.89, 22.51, 22.36,
13.97, 13.87; MS (MALDI-TOF): m/z [M + H+] = 979;
elemental analysis: calcd (%) for C64H69NO2S3: C 78.40, H 7.09,
N 1.43; found C 78.61, H: 7.26, N: 1.34.
2
2
1.29 (d, J = 6.8 Hz, 12H, Ph–CH–(CH )2), 1.35–1.10 (m, 8H,
3
3
–CH –), 0.80 (t, J = 6.9 Hz, 3H, Th–CH ); 13C-NMR (CDCl3):
2
d = 162.83, 144.64, 140.46, 136.25, 135.95, 134.37, 132.95,
132.78, 130.81, 130.03, 129.21, 128.41, 128.30, 128.04, 127.97,
127.71, 126.96, 125.98, 125.57, 124.28, 122.98, 122.78, 121.86,
119.85, 119.07, 118.97, 30.42, 29.46, 28.18, 27.86, 23.02, 21.42,
12.94; MS (MALDI-TOF): m/z [M + H+] = 647; elemental
analysis: calcd (%) for C44H41NO2S: C 81.57, H 6.38, N 2.16;
found C 81.79, H 6.57, N 2.17.
General procedure for the preparation of perylenyl-oligo-
thiophenes (8,12,14,16) via Suzuki coupling. To a solution of
the halogenated compound (1 equivalent) in DME [Pd(PPh3)4]
(5 mol%) and dioxaborolane 10 (1.2 equivalents) were added.
After addition of a 2 M aqueous solution of tripotassium
phosphate (2 equivalents) the mixture was stirred for 3 hours
at 60 ◦C. Next, it was poured into water and the organic
phase was separated while the aqueous phase was extracted
with dichloromethane. The combined extracts were dried over
sodium sulfate and the solvent was removed by rotary evapo-
ration. The crude product was purified by flash column chro-
matography and was dried in vacuum.
5-([N-(2,6-Diisopropylphenyl)]-9-perylenyl-3,4-dicarboximide)-
4,3ꢀ-dihexyl-2,2ꢀ-bithiophene (8). Following the general
procedure, bithiophene 4 (207 mg, 0.50 mmol) in THF (10 ml)
was converted to the corresponding zincate by subsequently
adding n-BuLi (0.32 ml, 0.51 mmol) and zinc chloride (75 mg,
◦
0.55 mmol) at −80 C. The resulting zincate was reacted with
General procedure for the preparation of iodinated perylenyl-
oligothiophenes (11,13,15). To a solution of the perylenyl-
oligothiophene (1 equivalent) in dry dichloromethane was added
mercury caproate (1.01 equivalents). The resulting suspension
was stirred at room temperature until the mercury compound
was completely dissolved. Next, iodine (1.1 equivalents) was
added and the mixture was stirred for another six hours. Then
the solution was filtered over basic aluminium oxide and the
filtrate was concentrated in vacuum. Upon addition of ethanol
the product was allowed to precipitate, was filtered and dried in
vacuum.
9-bromo-N-(2,6-diisopropylphenyl)perylene-3,4-dicarboximide
6 (308 mg, 0.55 mmol) and [Pd(PPh3)4] (58 mg, 0.05 mmol)
to give 8 (310 mg, 76%) as a dark red solid after flash column
chromatography (SiO2, dichloromethane–petrol ether 2 : 1).
◦
1
Mp 120–121 C; H-NMR (CDCl3): d = 8.65 (d, J = 8.0 Hz,
2H, Pery-1H,6H), 8.47–8.38 (m, 4H, Pery-2H,5H,7H,12H),
8.02 (d, J = 8.3 Hz, 1H, Pery-8H), 7.70 (d, J = 7.8 Hz, 1H,
Pery-10H), 7.64 (t, J = 7.9 Hz, 1H, Pery-11H), 7.51 (t, J =
7.8 Hz, 1H, Ph-4H), 7.39 (d, J = 7.8 Hz, 2H, Ph-3H,5H), 7.25
(d, J = 5.2 Hz, 1H, Thꢀ-5H), 7.17 (s, 1H, Th-3H), 7.01 (d, J =
5.2 Hz, 1H, Thꢀ-4H), 2.92–2.80 (m, 4H, Ph–CH–(CH3)2,
ꢀ
Th–a -CH ), 2.49 (t, J = 7.6 Hz, 2H, Th–a-CH ), 1.80–1.70
5-([N-(2,6-Diisopropylphenyl)]-9-perylenyl-3,4-dicarboximide)-
4,3ꢀ -dihexyl-2,2ꢀ -bithiophene (8). Following the general
2
2
2
(m, 2H, Th–bꢀ-CH ), 1.66–1.55 (m, 2H, Th–b-CH ), 1.51–1.41
(m, 2H, Th–c-CH ), 1.41–1.31 (m, 4H, Th–CH –), 1.25
2
ꢀ
procedure,
9-bromo-N-(2,6-diisopropylphenyl)perylene-3,4-
2
2
(d, J = 6.8 Hz, 12H, Ph–CH–(CH )2), 1.30–1.11 (m, 6H,
dicarboximide 6 (2.5 g, 4.5 mmol), dioxaborolane 10 (2.5 g,
5.5 mmol), tripotassium phosphate (5.5 ml, 11 mmol) and
[Pd(PPh3)4] (260 mg, 0.225 mmol) in DME (30 ml) were reacted
at 80 ◦C for 3 hours to give 8 (3.3 g, 90%) as a dark red solid after
flash column chromatography (SiO2, dichloromethane–petrol
3
–CH –), 0.92 (t, J = 6.9 Hz, 3H, Thꢀ–CH ), 0.81 (t, J =
2
3
6.9 Hz, 3H, Th–CH ); 13C-NMR (CDCl3): d = 168.84, 145.63,
3
141.75, 139.59, 137.36, 137.09, 136.15, 134.88, 133.80, 133.77,
131.88, 130.99, 130.39, 130.35, 130.25, 130.09, 129.36, 129.22,
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 9 8 5 – 9 9 5
9 9 3

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ether 2 : 1). Mp 120–121 ◦C; same spectroscopic and analytical
data as described above for Negishi coupling.
(s, 1H, Thꢀꢀꢀ-4H), 2.90–2.70 (m, 8H, Ph–CH–(CH3)2, Th–a ,a -
CH ), 2.45 (t, J = 7.6 Hz, 2H, Th–a-CH ), 1.80–1.65 (m, 6H,
ꢀ
ꢀꢀꢀ
2
2
Th–bꢀ–bꢀꢀꢀ-CH ), 1.65–1.50 (m, 2H, Th–b-CH ), 1.50–1.05
2
2
5-([N-(2,6-Diisopropylphenyl)]-9-perylenyl-3,4-dicarboximide)-
4,3ꢀ -dihexyl-5ꢀ -iodo-2,2ꢀ -bithiophene (11). Following the
general procedure perylenyl-bithiophene 8 (2.85 g, 3.5 mmol),
mercury capronate (1.52 mg, 3.54 mmol) and iodine (977 mg,
3.85 mmol) in dichloromethane (17 ml) were reacted to give
11 (3.2 g, 97%) as a red solid. Mp 124–125 ◦C; 1H-NMR
(CDCl3): d = 8.65 (d, J = 8.0 Hz, 2H, Pery-1H,6H), 8.47–8.38
(m, 4H, Pery-2H,5H,7H,12H), 7.99 (d, J = 8.3 Hz, 1H,
Pery-8H), 7.70–7.62 (m, 2H, Pery-10H,11H), 7.52 (t, J =
7.8 Hz, 1H, Ph-4H), 7.39 (d, J = 7.8 Hz, 2H, Ph-3H,5H),
7.14 (s, 1H, Thꢀ-4H), 7.10 (s, 1H, Th-3H), 2.90–2.80 (m, 4H,
(m, 24H, –CH –), 1.21 (d, J = 6.8 Hz, 12H, Ph–CH–(CH )2),
2
3
0.97–0.81 (m, 9H, Thꢀ–Thꢀꢀꢀ–CH ), 0.77 (t, J = 6.9 Hz, 3H,
3
Th–CH ); 13C-NMR (CDCl3): d = 163.92, 145.71, 141.97,
3
141.40, 139.95, 139.87, 137.43, 137.16, 136.53, 135.81, 134.86,
134.08, 133.84, 133.61, 132.67, 131.97, 131.06, 130.92, 130.59,
130.45, 130.35, 129.44, 129.34, 129.13, 128.78, 128.22, 127.27,
126.82, 124.01, 123.06, 121.10, 121.04, 120.34, 120.26, 71.53,
31.68, 31.62, 31.49, 30.55, 30.48, 29.52, 29.43, 29.28, 29.23,
29.18, 29.13, 29.05, 28.97, 28.93, 24.04, 22.64, 22.60, 22.49,
14.11, 14.00; MS (MALDI-TOF): m/z [M + H+] = 1271;
elemental analysis: calcd (%) for C74H82INO2S4: C 69.89, H
6.49, N 1.10; found C 70.05, H 6.52, N 0.92.
ꢀ
Ph–CH–(CH3)2, Th–a -CH ), 2.47 (t, J = 7.6 Hz, 2H, Th–
2
a-CH ), 1.75–1.65 (m, 2H, Th–bꢀ-CH ), 1.65–1.54 (m, 2H,
Th–b-CH ), 1.51–1.41 (m, 2H, Th–c-CH ), 1.47–1.29 (m, 4H,
2
2
ꢀ
5-([N-(2,6-Diisopropylphenyl)]-9-perylenyl-3,4-dicarboximide)-
4,3ꢀ,3ꢀꢀ,3ꢀꢀꢀ,3ꢀꢀꢀꢀ,3ꢀꢀꢀꢀꢀ-hexahexyl-2,2ꢀ;5ꢀ,2ꢀꢀ;5ꢀꢀ,2ꢀꢀꢀ;5ꢀꢀꢀ,2ꢀꢀꢀꢀ;5ꢀꢀꢀꢀ,2ꢀꢀꢀꢀꢀ-sexi-
thiophene (14). Following the general procedure iodinated
perylenyl-quaterthiophene 13 (160 mg, 126 lmol), dioxaboro-
lane 10 (70 mg, 151 lmol), tripotassium phosphate (0.15 ml,
302 lmol) and [Pd(PPh3)4] (153 mg, 13 lmol) in DME (1 ml)
were reacted at 60 ◦C for 4 hours to give 14 (140 mg, 75%)
as a black solid after flash column chromatography (SiO2,
2
2
–CH –), 1.24 (d, J = 6.8 Hz, 12H, Ph–CH–(CH )2), 1.29–1.11
2
3
(m, 6H, –CH –), 0.92 (t, J = 6.9 Hz, 3H, Thꢀ–CH ), 0.80 (t,
2
3
J = 6.9 Hz, 3H, Th–CH ); 13C-NMR (CDCl3): d = 162.89,
3
144.68, 140.90, 140.43, 138.86, 136.39, 136.10, 135.51, 133.74,
133.61, 133.49, 132.79, 130.95, 130.02, 129.42, 129.32, 128.42,
128.39, 128.35, 127.19, 126.73, 126.28, 125.80, 122.99, 122.01,
120.12, 120.05, 119.35, 119.27, 70.63, 30.60, 30.44, 29.59, 29.40,
28.15, 28.13, 28.00, 27.97, 27.87, 23.02, 21.57, 21.44, 13.06,
12.97; MS (MALDI-TOF): m/z [M + H+] = 939; elemental
analysis: calcd (%) for C54H54INO2S2: C 69.00, H 5.74, N 1.49;
found C 69.15, H 5.79, N 1.36.
◦
1
dichloromethane–petrol ether 2 : 1). Mp 64–65 C; H-NMR
(CDCl3): d = 8.65 (d, J = 8.0 Hz, 2H, Pery-1H,6H), 8.52 −
8.40 (m, 4H, Pery-2H,5H,7H,12H), 8.00 (d, J = 8.3 Hz, 1H,
Pery-8H), 7.69 (d, J = 7.8 Hz, 1H, Pery-10H), 7.63 (t, J =
7.9 Hz, 1H, Pery-11H), 7.48 (t, J = 7.8 Hz, 1H, Ph-4H),
7.35 (d, J = 7.8 Hz, 2H, Ph-3H,5H), 7.16 (m, 2H, Th-3H,
Thꢀꢀꢀꢀꢀ-5H), 7.1–6.90 (m, 5H, Thꢀ–Thꢀꢀꢀꢀ-4H), 2.90–2.75 (m, 12H,
5-([N-(2,6-Diisopropylphenyl)]-9-perylenyl-3,4-dicarboximide)-
4,3ꢀ,3ꢀꢀ,3ꢀꢀꢀ-tetrahexyl-2,2ꢀ;5ꢀ,2ꢀꢀ;5ꢀꢀ,2ꢀꢀꢀ-quaterthiophene (12). Fol-
lowing the general procedure iodinated perylenyl-bithio-
phene 11 (1.4 g, 1.5 mmol), dioxaborolane 10 (800 mg,
1.7 mmol), tripotassium phosphate (1.7 ml, 3.4 mmol) and
[Pd(PPh3)4] (87 mg, 0.075 mmol) in DME (10 ml) were reacted
at 80 ◦C for 3 hours to give 12 (1.4 g, 82%) as a black solid after
flash column chromatography (SiO2, dichloromethane–petrol
ether 2 : 1). Mp 89–90 ◦C; 1H-NMR (CDCl3): d = 8.64
(d, J = 8.0 Hz, 2H, Pery-1H,6H), 8.49–8.42 (m, 4H, Pery-
2H,5H,7H,12H), 8.00 (d, J = 8.3 Hz, 1H, Pery-8H), 7.68 (d, J =
7.8 Hz, 1H, Pery-10H), 7.63 (t, J = 7.9 Hz, 1H, Pery-11H),
7.48 (t, J = 7.8 Hz, 1H, Ph-4H), 7.34 (d, J = 7.8 Hz, 2H,
Ph-3H,5H), 7.17–7.15 (m, 2H, Th-3H, Thꢀꢀꢀ-5H), 7.00 (s, 1H,
Thꢀ-4H), 6.96 (s, 1H, Thꢀꢀ-4H), 6.93 (d, J = 5.3 Hz, 1H, Thꢀꢀꢀ-4H),
ꢀ
Ph–CH–(CH3)2, Th–a –aꢀꢀꢀꢀꢀ-CH ), 2.46 (t, J = 7.5 Hz, 2H,
2
Th–a-CH ), 1.80–1.50 (m, 24H, –CH –), 1.50–1.10 (m, 24H,
2
2
–CH –), 1.20 (d, J = 6.8 Hz, 12H, Ph–CH–(CH )2), 0.95–0.80
2
3
(m, 15H, Thꢀ–Thꢀꢀꢀꢀꢀ–CH ), 0.78 (t, J = 6.9 Hz, 3H, Th–CH );
3
3
13C-NMR (CDCl3): d = 163.85, 145.65, 141.88, 139.85, 139.80,
139.72, 139.55, 137.47, 137.20, 135.79, 134.85, 134.05, 133.93,
133.84, 133.80, 133.75, 131.94, 130.97, 130.44, 130.41, 130.31,
130.29, 130.26, 129.99, 129.36, 129.32, 128.68, 128.49, 128.20,
127.22, 127.13, 126.85, 123.95, 123.89, 123.49, 123.01, 121.07,
121.01, 120.34, 120.26, 31.59, 31.57, 31.37, 30.53, 30.46, 30.40,
30.35, 29.42, 29.38, 29.20, 29.16, 29.13, 29.11, 29.06, 28.81,
23.91, 22.53, 22.49, 22.37, 13.99, 13.97, 12.67; MS (MALDI-
TOF): m/z [M + H+] = 1478; elemental analysis: calcd (%) for
C94H111NO2S6: C 76.32, H 7.65, N 0.95; found C 76.36, H 7.70,
N 0.90.
ꢀ
ꢀꢀꢀ
2.87–2.75 (m, 8H, Ph–CH–(CH3)2, Th–a ,a -CH ), 2.45 (t, J =
2
7.6 Hz, 2H, Th–a-CH ), 1.70–1.60 (m, 6H, Th–bꢀ,bꢀꢀꢀ-CH ),
1.60–1.50 (m, 2H, Th–b-CH ), 1.50–1.22 (m, 24H, –CH –),
2
2
2
2
5-([N-(2,6-Diisopropylphenyl)]-9-perylenyl-3,4-dicarboximide)-
1.20 (d, J = 6.8 Hz, 12H, Ph–CH–(CH )2), 0.96–0.82 (m, 9H,
3
4,3ꢀ,3ꢀꢀ,3ꢀꢀꢀ,3ꢀꢀꢀꢀ,3ꢀꢀꢀꢀꢀ-hexahexyl-5ꢀꢀꢀꢀꢀ-iodo 2,2ꢀ;5ꢀ,2ꢀꢀ;5ꢀꢀ,2ꢀꢀꢀ;5ꢀꢀꢀ,2ꢀꢀꢀꢀ;5ꢀꢀꢀꢀ,
Thꢀ–Thꢀꢀꢀ–CH ), 0.79 (t, J = 6.9 Hz, 3H, Th–CH ); 13C-NMR
3
3
2
ꢀꢀꢀꢀꢀ-sexithiophene (15). Following the general procedure
(CDCl3): d = 163.96, 145.74, 141.97, 139.87, 139.67, 137.54,
137.26, 135.91, 134.95, 134.22, 134.01, 133.94, 133.91, 132.05,
131.08, 130.51, 130.39, 130.35, 130.12, 129.41, 129.38, 128.79,
128.63, 128.28, 127.31, 127.22, 126.91, 124.02, 123.65, 123.11,
121.14, 121.08, 120.41, 120.32, 31.71, 31.50, 30.65, 30.59, 30.52,
30.48, 29.53, 29.48, 29.28, 29.26, 29.24, 29.18, 29.05, 28.94,
24.04, 22.65, 22.50, 14.11; MS (MALDI-TOF): m/z [M + H+] =
1145; elemental analysis: calcd (%) for C74H83NO2S4: C 77.51,
H 7.30, N 1.22; found C 77.45, H 7.28, N 1.00.
perylenyl-sexithiophene 14 (210 mg, 0.14 mmol), mercury
caproate (62 mg, 0.14 mmol) and iodine (40 mg, 0.16 mmol)
in dichloromethane (5 ml) were r◦eacted to give 15 (210 mg,
1
94%) as a black solid. Mp 76–77 C; H-NMR (CDCl3): d =
8.65 (d, J = 8.0 Hz, 2H, Pery-1H,6H), 8.52–8.40 (m, 4H,
Pery-2H,5H,7H,12H), 8.00 (d, J = 8.3 Hz, 1H, Pery-8H),
7.69 (d, J = 7.8 Hz, 1H, Pery-10H), 7.63 (t, J = 7.9 Hz, 1H,
Pery-11H), 7.48 (t, J = 7.8 Hz, 1H, Ph-4H), 7.35 (d, J =
7.8 Hz, 2H, Ph-3H,5H), 7.16 (s, 1H, Th-3H), 7.06 (s, 1H,
Thꢀ-4H), 7.02 (s, 1H, Thꢀꢀ-4H), 6.99 (s, 1H, Thꢀꢀꢀ-4H), 6.96
(s, 1H, Th-4ꢀꢀꢀꢀH), 6.88 (s, 1H, Thꢀꢀꢀꢀꢀ-4H), 2.90–2.75 (m, 12H,
5-([N-(2,6-Diisopropylphenyl)]-9-perylenyl-3,4-dicarboximide)-
4,3ꢀ,3ꢀꢀ,3ꢀꢀꢀ -tetrahexyl-5ꢀꢀꢀ -iodo-2,2ꢀ;5ꢀ,2ꢀꢀ;5ꢀꢀ,2ꢀꢀꢀ -quaterthiophene
(13). Following the general procedure perylenyl-quaterthio-
phene 12 (800 mg, 0.7 mmol), mercury capronate (304 mg,
0.71 mmol) and iodine (195 mg, 0.77 mmol) in dichloromethane
(4 ml) were◦reacted to give 13 (825 mg, 93%) as a black solid.
ꢀ
Ph–CH–(CH3)2, Th–a –aꢀꢀꢀꢀꢀ-CH ), 2.46 (t, J = 7.5 Hz, 2H,
2
Th–a-CH ), 1.80–1.50 (m, 24H, –CH –), 1.50–1.10 (m, 24H,
2
2
–CH –), 1.20 (d, J = 6.8 Hz, 12H, Ph–CH–(CH )2), 0.95–0.80
2
3
(m, 15H, Thꢀ–Thꢀꢀꢀꢀꢀ–CH ), 0.78 (t, J = 6.9 Hz, 3H, Th–CH );
3
3
1
Mp 97–98 C; H-NMR (CDCl3): d = 8.62 (d, J = 8.0 Hz,
13C-NMR (CDCl3): d = 163.66, 145.45, 141.12, 139.66, 139.53,
137.26, 136.99, 136.27, 135.57, 134.64, 133.75, 133.63, 133.56,
133.45, 133.22, 132.33, 131.74, 130.78, 130.68, 130.34, 130.24,
130.09, 129.12, 128.86, 128.47, 128.36, 128.00, 127.01, 126.94,
126.64, 123.75, 123.70, 122.81, 120.87, 120.80, 120.14, 120.05,
71.15, 31.39, 31.31, 31.18, 30.25, 30.19, 30.16, 29.22, 29.18,
2H, Pery-1H,6H), 8.45–8.35 (m, 4H, Pery-2H,5H,7H,12H),
7.98 (d, J = 8.4 Hz, 1H, Pery-8H), 7.66 (d, J = 7.8 Hz, 1H,
Pery-10H), 7.61 (t, J = 7.9 Hz, 1H, Pery-11H), 7.48 (t, J =
7.8 Hz, 1H, Ph-4H), 7.35 (d, J = 7.8 Hz, 2H, Ph-3H,5H), 7.16
(s, 1H, Th-3H), 7.05 (s, 1H, Thꢀ-4H), 7.00 (s, 1H, Thꢀꢀ-4H), 6.89
9 9 4
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 9 8 5 – 9 9 5

View Article Online
29.09, 28.95, 28.90, 28.86, 28.81, 28.73, 28.65, 28.61, 23.71,
22.33, 22.28, 22.17, 13.79, 13.70; MS (MALDI-TOF): m/z [M +
H+] = 1604; elemental analysis: calcd (%) for C94H110INO2S6: C
70.34, H 6.91, N 0.87; found C 70.50, H 6.79, N 0.92.
4 Electronic Materials: The Oligomer Approach, ed. K. Mu¨llen and
G. Wegner, Wiley-VCH, Weinheim, 1998.
5 P. Ba¨uerle, in Handbook of Oligo- and Polythiophenes, ed. D. Fichou,
Wiley-VCH, Weinheim, 1999, pp. 89–184.
6 M. Halik, H. Klauk, U. Zschieschnag, G. Schmid, S. Ponomarenko,
S. Kirchmeyer and W. Weber, Adv. Mater., 2003, 15, 917–922.
5-([N-(2,6-Diisopropylphenyl)]-9-perylenyl-3,4-dicarboximide)-
4,3ꢀ,3ꢀꢀ,3ꢀꢀꢀ,3ꢀꢀꢀꢀ,3ꢀꢀꢀꢀꢀ,3ꢀꢀꢀꢀꢀꢀ,3ꢀꢀꢀꢀꢀꢀꢀ - octaahexyl - 2,2ꢀ;5ꢀ,2ꢀꢀ;5ꢀꢀ,2ꢀꢀꢀ;5ꢀꢀꢀ,2ꢀꢀꢀꢀ;
5ꢀꢀꢀꢀ,2ꢀꢀꢀꢀꢀ;5ꢀꢀꢀꢀꢀ,2ꢀꢀꢀꢀꢀꢀ;5ꢀꢀꢀꢀꢀꢀ,2ꢀꢀꢀꢀꢀꢀꢀ-octathiophene (16). Following the
general procedure iodinated perylenyl-sexithiophene 15 (25 mg,
16 lmol), dioxaborolane 10 (9 mg, 19 lmol), tripotassium
phosphate (19 ll, 38 lmol) and [Pd(PPh3)4] (2 mg, 1.6 lmol)
in DME (0.5 ml) were reacted at 60 ◦C for 4 hours to
give 16 (20 mg, 70%) as a black solid after flash column
chromatogr◦aphy (SiO2, dichloromethane–petrol ether 2 : 1).
7 U. Mitschke and P. B
8 C. Videlot, A. ElKassmi and D. Fichou, Solar Energy Mater. Solar
Cells, 2000, 63, 69–82.
a¨uerle, J. Mater. Chem., 2000, 10, 1471–1507.
9 (a) T. Kirschbaum, R. Azumi, E. Mena-Osteritz and P. Ba¨uerle,
New J. Chem., 1999, 241–250; (b) T. Kirschbaum, C. A. Briehn and
P. B
a¨uerle, J. Chem. Soc., Perkin Trans. 1, 2000, 1211–1216.
10 (a) P. Ba¨uerle, Adv. Mater., 1992, 4, 102–107; (b) R. E. Martin, U.
Gubler, C. Bondon, V. Gramlich, C. Bosshard, J. P. Gisselbrecht, P.
Gu¨nther and F. Diederich, Chem. Eur. J., 1997, 3, 1505–1512; (c) H.
Meier, J. Gerold, H. Kolshorn and B. Mu¨hling, Chem. Eur. J., 2004,
10, 360–370.
1
Mp 66–67 C; H-NMR (CDCl3): d = 8.70 (d, J = 8.0 Hz,
2H, Pery-1H,6H), 8.56–8.50 (m, 4H, Pery-2H,5H,7H,12H),
8.04 (d, J = 8.4 Hz, 1H, Pery-8H), 7.75 − 7.65 (m, 2H,
Pery-10H,11H), 7.51 (t, J = 7.8 Hz, 1H, Ph-4H), 7.37 (d, J =
7.7 Hz, 2H, Ph-3H,5H), 7.20–7.15 (m, 2H, Th-3H, Th-5ꢀꢀꢀꢀꢀꢀꢀH),
7.12–6.95 (m, 7H, Thꢀ–Th–ꢀꢀꢀꢀꢀꢀꢀ4H), 2.90–2.75 (m, 16H, Ph–CH–
11 E. Mena-Osteritz, Adv. Mater., 2002, 14, 609–616.
12 Preliminary measurements of the HT-coupled octahexyl-
octathiophene revealed field-effect mobilities in the range of
5 × 10−3 cm2 V−1 s−1 (unpublished results with Dr. H. Sirringhaus,
University of Cambridge, England).
13 P. A. van Hal, E. H. A. Beckers, S. C. J. Meskers, R. A. Janssen,
B. Jousselme, P. Blanchard and J. Roncali, Chem. Eur. J., 2002, 8,
5415–5429.
14 (a) E. Peeters, P. A. van Hal, J. Knol, C. J. Brabec, N. S. Sariciftci,
J. C. Hummelen and R. A. J. Janssen, J. Phys. Chem. B, 2000, 104,
10174–10190; (b) P. A. van Hal and R. A. Janssen, Phys. Rev. B, 2001,
64, 75206.
15 (a) A. Miura, Z. Chen, S. de Feyter, M. Zdanowska, H. Uji-i, P.
Jonkheijm, A. P. H. J. Schenning, E. W. Meijer, F. Wu¨rthner and
F. C. de Schryver, J. Am. Chem. Soc., 2003, 125, 14968–14969;
(b) E. E. Neuteboom, E. H. A. Beckers, S. C. J. Meskers, E. W. Meijer
and R. A. J. Janssen, Org. Biomol. Chem., 2003, 1, 198–203; (c) A.
Syamakumari, A. P. H. J. Schenning and E. W. Meijer, Chem. Eur. J.,
2002, 8, 3353–3361; (d) A. P. H. J. Schenning, J. v. Herrikhuyzen, P.
Jonkheim, Z. Chen, F. Wu¨rthner and E. W. Meijer, J. Am. Chem.
Soc., 2002, 124, 10252–10253.
ꢀ
(CH3)2, Th–a –aꢀꢀꢀꢀꢀꢀꢀ–CH ), 2.48 (t, J = 7.5 Hz, 2H, Th–a-CH ),
2
2
2
1.80–1.55 (m, 16H, –CH –), 1.55–1.10 (m, 48H, –CH –), 1.22
2
(d, J = 6.8 Hz, 12H, Ph–CH–(CH )2), 0.97–0.85 (m, 21H,
3
Thꢀ–Thꢀꢀꢀꢀꢀꢀꢀ–CH ), 0.81 (t, J = 6.9 Hz, 3H, Th–CH ); 13C-NMR
3
3
(CDCl3): d = 161.79, 143.59, 139.82, 137.79, 137.76, 137.65,
137.48, 135.41, 135.14, 133.73, 132.79, 131.88, 131.79, 131.74,
131.65, 129.90, 129.88, 128.92, 128.38, 128.26, 128.23, 127.92,
127.34, 127.30, 127.27, 126.62, 126.43, 126.15, 125.15, 125.07,
124.79, 121.89, 121.83, 121.43, 120.95, 119.02, 118.96, 118.28,
118.20, 29.53, 29.32, 28.47, 28.41, 28.33, 28.29, 27.36, 27.31,
27.14, 27.09, 27.05, 27.00, 26.87, 26.75, 21.85, 20.48, 20.47,
20.43, 20.31, 11.93, 11.81; MS (MALDI-TOF): m/z [M + H+] =
1810; elemental analysis: calcd (%) for C144H139NO2S8: C 75.57,
H 7.73, N 0.77; found C 75.65, H 7.79, N 0.85.
16 (a) H. Langhals, Heterocycles, 1995, 40, 477–500; (b) H. Langhals,
Chem. Ber., 1985, 188, 4641–4645.
17 A. J. Breeze, A. Salomon, D. S. Ginley and B. A. Gregg, Appl. Phys.
Lett., 2002, 81, 3085–3087.
18 K. J. Hoffmann and P. H. J. Carlsen, Synth. Commun., 1999, 1607–
1610.
Acknowledgements
We would like to thank the German Ministry for Education
and Research (BMBF-Netzwerk “Polymere Solarzellen”) for
funding and BASF AG Ludwigshafen for providing 9-bromo-N-
(2,6-diisopropylphenyl)perylene-3,4-dicarboximide. J.C. would
like to thank the “Fonds der Chemischen Industrie” and the
German Ministry for Education and Research (BMBF) for a
Kekule´-Grant.
19 T.-A. Chen, X. Wu and R. D. Rieke, J. Am. Chem. Soc., 1995, 233–
244.
20 T. Kirschbaum, Dissertation, University of Ulm, 2001.
21 We decided to use the parameter FWHM in order to accurately
compare the position of bands presenting different vibronic coupling
structures.
22 T. Gensch, J. Hofkens, A. Herrmann, K. Tsuda, W. Verheijen, T.
Vosch, T. Christ, T. Basche´, K. Mu¨llen and F. C. De Schryver, Angew.
Chem., Int. Ed., 1999, 38, 3752–3756.
23 R. S. Becker, J. S. de Melo, A. L. Macanita and F. Elisei, J. Phys.
Chem., 1996, 100, 18683–18695.
References
1 (a) R. S. Loewe, S. M. Khersonsky and R. D. McCullough, Adv.
Mater., 1999, 11, 250–253; (b) R. D. McCullough and P. C. Ewbank,
Handbook of Conducting Polymers, 2nd edn., Marcel Dekker, New
York, 1998, pp. 225–258.
24 E. Mena-Osteritz, J. Cremer and P. Ba¨uerle, to be published
elsewhere.
2 (a) H. Sirringhaus, J. P. Brown, R. H. Friend, M. M. Nielsen, K.
Beechgard, B. M. W. Langeveld-Voss, A. J. H. Spiering, R. A. J.
Janssen, E. W. Meijer, P. Herwig and D. M. de Leeuw, Nature, 1999,
401, 685–688; (b) R. H. Friend, R. W. Gymer, A. B. Holmes, J. H.
Burroughes, R. N. Marks, C. Taliani, D. C. C. Bradley, D. A. Dos
Santos, J. L. Bre´das, M. Logdlund and W. R. Salaneck, Nature, 1999,
397, 121–128; (c) E. Mena-Osteritz, A. Meyer, B. M. W. Langeveld-
Voss, R. A. J. Janssen, E. W. Meijer and P. Ba¨uerle, Angew. Chem.,
2000, 112, 2791–2796; (d) E. Mena-Osteritz, A. Meyer, B. M. W.
Langeveld-Voss, R. A. J. Janssen, E. W. Meijer and P. Ba¨uerle, Angew.
Chem., Int. Ed., 2000, 39, 2679–2684.
3 (a) C. Winder and N. S. Sariciftci, J. Mater. Chem., 2004, 14, 1077–
1086; (b) J. Nelson, Mater. Today, 2002, 5, 20–27; (c) A. Cravino
and N. S. Saricifci, J. Mater. Chem., 2002, 12, 1931–1944; (d) C. J.
Brabec, N. S. Sariciftci and J. C. Hummelen, Adv. Funct. Mater., 2001,
1, 15–26; (e) J. J. M. Halls and R. H. Friend, in Organic Photovoltaic
Devices: Clean Electricity from Photovoltaics, ed. M. D. Archer and
R. D. Hill, Imperial College Press, London, 2001, pp. 377–445.
25 E. Fron, M. Lor, R. Pilot, G. Schweitzer, S. De Feyter, J. Cremer, P.
Ba¨uerle, K. Mu¨llen, M. Van der Auweraer and F. C. de Schryver,
Photochem. Photobiol. Sci., 2004, published on the web 9 November
2004.
26 R. N. Adams, Electrochemistry at Solid Electrodes, Marcel Dekker,
New York, 1969, p. 146.
27 G. Tourillon and F. Garnier, J. Electroanal. Chem., 1984, 161, 51–58.
28 J. Heinze and P. Tschunky, in Electronic Materials: The Oligomer
Approach, ed. K. Mu¨llen and G. Wegner, Wiley-VCH, Weinheim,
1998, pp. 479–514.
29 A. Kraft, A. C. Grimsdale and A. B. Holmes, Angew. Chem., Int.
Ed., 1998, 37, 402–428.
30 J. Pommerehne, H. Vestweber, W. Guss, R. F. Mahrt, H. Ba¨ssler, M.
Porsch and J. Daub, Adv. Mater., 1995, 7, 551–554.
31 M. M. Wienk, J. Cremer, P. Ba¨uerle and R. A. J. Janssen, to be
published elsewhere.
32 I. C. G. Coutts, H. R. Goldschmidt and O. C. Musgrave, J. Chem.
Soc., 1970, 488–489.
O r g . B i o m o l . C h e m . , 2 0 0 5 , 3 , 9 8 5 – 9 9 5
9 9 5