Energy transfer at the single-molecule level: Synthesis of a donor-acceptor dyad from perylene and terrylene diimides

Article abstract of DOI:10.1002/chem.201300439

In 2004, we reported single-pair fluorescence resonance energy transfer (spFRET), based on a perylene diimide (PDI) and terrylene diimide (TDI) dyad (1) that was bridged by a rigid substituted para-terphenyl spacer. Since then, several further single-mole

Full text of DOI:10.1002/chem.201300439

FULL PAPER
Donor–Acceptor Systems
H. N. Kim, L. Puhl, F. Nolde, C. Li,
L. Chen, T. Baschꢀ,
K. Mꢁllen* .................... &&&& — &&&&
D–A tripper: The synthesis of dyad
(see scheme), which consists of pery-
lene diimide (PDI) and terrylene di-
ACHTUNGTRNEiNUNG mide (TDI) units that are linked
together through a rigid para-terphenyl
moiety, is described.
Energy Transfer at the Single-Mole-
cule Level: Synthesis of a Donor–
Acceptor Dyad from Perylene and
Terrylene Diimides
Nonsymmetrical Functionalization
The synthesis of dyad depicted on the left, which consists
of perylene diimide (PDI) and terrylene diimide (TDI)
linked via a rigid p-terphenyl, is described. Among a lot of
different approaches that can be employed, an optimized
reaction pathway was chosen with respect to solubilities,
reactivities and accessibilities of the building blocks used.
The key towards facile synthesis of the dyad is the
nonsymmetrical functionalization of perylene diimide and
terrylene diimide. For more details see the Full Paper by
K. Mꢀllen et al. on page &&ff.
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DOI: 10.1002/chem.201300439
Energy Transfer at the Single-Molecule Level: Synthesis of a Donor–
Acceptor Dyad from Perylene and Terrylene Diimides
Ha Na Kim,[a] Larissa Puhl,[a] Fabian Nolde,[a] Chen Li,[a] Long Chen,[a]
Thomas Baschꢀ,[b] and Klaus Mꢁllen*[a]
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Energy Transfer at the Single-Molecule Level
FULL PAPER
Abstract: In 2004, we reported single-
pair fluorescence resonance energy
transfer (spFRET), based on a pery-
lene diimide (PDI) and terrylene dii-
mide (TDI) dyad (1) that was bridged
by a rigid substituted para-terphenyl
spacer. Since then, several further
single-molecule-level investigations on
this specific compound have been per-
formed. Herein, we focus on the syn-
thesis of this dyad and the different ap-
proaches that can be employed. An op-
timized reaction pathway was chosen,
considering the solubilities, reactivities,
and accessibilities of the building
blocks for each individual reaction
whilst still using established synthetic
Suzuki coupling, and cyclization reac-
tions. The key differentiating consider-
ation in this approach to the synthesis
of dyad 1 is the introduction of func-
tional groups in
a nonsymmetrical
techniques,
including
imidization,
manner onto either the perylene dii-
mide or the terrylene diimide by using
imidization reactions. Combined with
well-defined purification conditions,
this modified approach allows dyad 1
to be obtained in reasonable quantities
in good yield.
Keywords: chromophores · donor–
acceptor systems · dyads · energy
transfer · single-molecule spectro-
scopy
Introduction
The spectroscopic overlap between the PDI emission and
the TDI absorption leads, for the given electronic coupling
strength, to fast EET times on the 10 ps timescale at both
room temperature and at liquid-helium temperature.[7,9]
These outstanding characteristics of the dyad have fostered
a number of single-molecule results, including the determi-
nation of EET rates[7,9] and the study of the mutual influence
of the chromophores on their photostability.[10] With regard
to the mechanism of EET, quantum-chemical calculations
have shown that a pure Fçrster description of the EET proc-
ess is insufficient, owing to a contribution that originates
from the polarizability of the bridge.[11] Moreover, the
energy flow between the PDI and TDI moieties can be con-
trolled by dual-color laser excitation.[12] Because there are
still a number of fascinating single-molecule experiments,
for example, in the realm of quantum-state detection and
manipulation, we consider it worthwhile to describe herein
an efficient synthetic route to this dyad.
There are many possible approaches for the synthesis of
dyad 1 (Figure 1), which contains perylene diimide and ter-
rylene diimide groups that are linked together by a para-ter-
phenyl bridge, including various methods for the synthesis
of the individual PDI, TDI, and para-terphenyl moieties.
Therefore, the major challenge lies in finding an acceptable
balance between the solubility and reactivity of the building
blocks for each reaction. Herein, we report an efficient
strategy for the synthesis of dyad 1 that consists of four
parts, that is, the syntheses of the PDI, TDI, and linker units
and their final combination to form dyad 1.
Electronic excitation energy transfer (EET) is of fundamen-
tal importance for the functioning of light-harvesting com-
plexes and a crucial step in the optoelectronic applications
of organic materials. Because the efficiency of EET between
a donor (D) and an acceptor (A) chromophore sensitively
depends on the separation and relative orientation of the
two chromophores, it constitutes a molecular ruler that op-
erates on the length scale 1–10 nm.[1] Recently, EET has
been applied at the single-molecule level to measure distan-
ces and distance fluctuations on the nanometer scale in real
time without the problems that are encountered with ensem-
ble averaging.[2–4] To gain new and quantitative information
on the energy-transfer process, single-molecule spectroscopy
(SMS) has been applied to simple model systems, in which
the donor and acceptor moieties are held at fixed distances
from one another.[5–8] In particular, we have investigated a
dyad in which a designated donor molecule (perylene dii-
mide, PDI) and a designated acceptor molecule (terrylene
diimide, TDI) are linked by
a para-terphenyl bridge
(Figure 1).[7] PDI and TDI were chosen because they pos-
sessed favorable properties for single-molecule spectroscopy,
with large absorption cross-sections, high emission quantum
yields, and low photobleaching yields. In the dyad, each of
the chromophores can be selectively excited and the dis-
tance and relative orientation of PDI and TDI are rather
well-defined by virtue of the fairly rigid para-terphenyl
bridge.[9] Both chromophores give rise to sharp zero-phonon
lines at liquid-helium temperatures, which is crucial for ex-
tracting EET times from the line-width measurements.[7,9]
Results and Discussion
[a] Dr. H. N. Kim, L. Puhl, Dr. F. Nolde, Dr. C. Li, Dr. L. Chen,
Prof. Dr. K. Mꢀllen
Our approach (Figure 1) includes the imidization of pery-
lene 6 to introduce a functional group at the peri position
(Figure 1a), a coupling reaction to form a bridge between
the PDI and TDI building blocks (Figure 1b) and, finally, a
cyclization reaction for the ring closure of the terrylene
moiety (blue part of compound 2, Figure 1c). These three
building blocks, that is, the PDI unit, the para-terphenyl
bridge, and the TDI unit (Figure 1), are designed with the
Max Planck Institute for Polymer Research
Ackermannweg 10, 55128 Mainz (Germany)
Fax : (+49)6131-379-350
E-mail: Mꢀllen@mpip-mainz.mpg.de
[b] Prof. Dr. T. Baschꢂ
Institut fꢀr Physikalische Chemie
Johannes-Gutenberg-Universitꢃt Mainz
Jakob-Welder-Weg 11, 55099 Mainz (Germany)
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The first challenge to be ad-
dressed is the correct moment
at which to introduce the solu-
bilizing groups. This choice es-
sentially relates to deciding
which chromophore, PDI or
TDI, should be connected to
the linker first. Both the pery-
lene and terrylene diimides
À
tend to form strong p p aggre-
gates, which result in poor solu-
bility in organic solvents.[14] In
this way, the use of a solubiliz-
ing group (C8H17) greatly af-
fects the entirety of the synthet-
ic strategies of routes A and B
(Figure 2). The second chal-
lenge involves the reactivity
and overall reaction yield of
each synthetic route. In the
case of route A, the overall
yield is very low, whereas, in
the case of route B, compound
11 displays very low reactivity
under these conditions. On the
basis of the design criteria, the
detailed synthetic procedures of
three building blocks are descri-
À
À
Figure 1. Synthesis of dyad 1 (PDI linker TDI): a) Imidization, b) Suzuki coupling, and c) cyclization reac-
tions.
synthetic requirements of reactivity, selectivity, and solubili-
ty in mind. The bridge compound (7) contains an amino
group for the imidization of 3,4,9,10-perylenetetracarboxylic
dianhydride (6, PDA), whilst the PDI and TDI building
blocks (3 and 4) were prepared with nonsymmetrical func-
tional groups for a subsequent Suzuki coupling reaction
(Figure 1b). Owing to its low toxicity and the simple intro-
duction of easily convertible functional groups, a Suzuki
cross-coupling reaction was primarily utilized, despite the
potential formation of a homo-coupling side product. In ad-
dition, the purification method for removing this byproduct
is well-established.
bed separately and the final coupling reaction is described
as follows.
The linker: Alkyl-substituted oligophenylenes are perfectly
suited as rigid, nonconjugated linkers, owing to their great
There are several possible methods for combining these
three moieties to achieve dyad 1, such as routes A and B as
shown in Figure 2. In the case of route A, the critical step in
the synthesis is the cyclization reaction, which causes the
complete hydrolysis of the PDI part (compound 8; Figure 2,
red arrow) under basic reaction conditions. On the other
hand, in the case of route B, the use of nonsymmetrical
compounds 9 and 11 as the building blocks to avoid the cyc-
lization reaction did not allow the synthesis of final target
compound (1) by statistical imidization. Not only were the
solubilities of compounds 9 and 11 too low to facilitate this
reaction, but also the syntheses of compounds 9 and 11 were
rather complicated and included multiple steps.[13] There-
fore, the success of this synthesis greatly depends on the se-
quence of the reaction steps and the design of each building
block.
Figure 2. Preliminary approaches for the synthesis of dyad 1.
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Energy Transfer at the Single-Molecule Level
FULL PAPER
persistence length whilst simul-
taneously being twisted.[15] Bi-
functional para-terphenyl com-
pounds are well-established[16]
and have been used as linkers
in various molecular architec-
tures.[17] Herein, we use a phe-
nylene derivative, 1,4-dibro-
mo-2,5-dioctylbenzene
(13),
which is functionalized in an
AB pattern, as a starting mate-
rial. Owing to the solubilizing
effect of the alkyl-substituted
phenylene moiety, the chromo-
phores, when connected, can
be dissolved in reasonable con-
centrations in organic solvents.
The construction of the
Scheme 1. Synthesis of compounds 14 and 7: a) [PdACHTNUTRGNEUNG(PPh3)4], K2CO3, toluene/H2O (3:2 v/v), 808C, 16 h, 65%
yield; b) TFA/CH2Cl2 (10% yield), RT, 0.5 h, 90% yield.
para-terphenyl spacer in
a
step-wise fashion requires two
functional groups, which are
accessible through Suzuki cou-
pling reactions. To ensure a se-
lective coupling reaction, that
is, the sole reaction of com-
pound 13 with the boronic
ester group of compound 12,
rather than with the amine
group, compound 12 contains
both a boronic ester group and
a tert-butyloxycarbonyl (Boc)-
protected amine group, which
can easily be activated by de-
protection in the presence of
acid for the next imidization
step. The synthesis of the
linker started from compound
13, which was coupled with
Scheme 2. Synthesis of compounds 3a and 3b: a) Imidazole/propionic acid (10:1, v/v), 1408C, 4 h (26% yield);
b) propionic acid, 1508C, 16 h; c) [PdCl
2ACHTUNGTREN(NUNG dppf)]·CH2Cl2, bis(pinacolato)diboron, 1,4-dioxane, KOAc, 17 h;
d) [Pd(PPh3)4], K2CO3, toluene/H2O (3:2 v/v), 808C, 16 h; e) propionic acid, 1508C, 16 h.
AHCTUNGTRENNUNG
tert-butyl-N-[4-(4,4,5,5-tetramethyl-1,2,3-dioxaborolan-2-yl)-
phenyl]carbamate (12) through a Suzuki reaction. After re-
moving the Boc protecting group from this product (14), the
linker, 4-aniline-2,5-dioctylbenzene bromide (7), was ob-
tained (Scheme 1).
product (3b) was labile under the basic reaction conditions
that were required to produce the closed product (3a)
during the final reaction step. The advantages of the one-pot
imidization reaction (route A) is that it is not only simple,
but it also allows the facile recovery of compound 7 by
column chromatography when an excess amount of com-
pound 7 is used. Concerning the solubility and reactivity of
PDA 6, the imidization of compound 6 was first carried out
with 2,6-diisopropylaniline (5) in imidazole; then, a solution
of compound 7 in propionic acid was added into the reac-
tion mixture to produce the closed product (3a).
The PDI unit (donor): One key step in the synthetic route is
the synthesis of a nonsymmetrical perylene dimide. Several
synthetic methods for the mono-functionalization of PDI
have been reported and achieved in a one-pot manner or
through a base-promoted coupling reaction between naph-
thalene monoimide derivatives 22 and 23, as shown in
Scheme 2 (route B). Alternatively, several multistep reac-
tions, for example, multiple imidization and saponification
steps, can also be used, but they often produce low
yields.[13,18–20] Each method has its own particular advantag-
es, but, herein, para-biphenyl bridge compound 7 was con-
nected to PDA 6 in a one-pot imidization reaction (route
A) because route B consisted of five steps and the open
The TDI unit (acceptor): The principal concept in the syn-
thetic route of the TDI building block is the introduction of
a boronic ester group onto the TDI moiety (compound 4)
for the final coupling reaction with PDI. Starting from N-
(2,6-diisopropylphenyl)-9-(4,4,5,5-teramethyl-1,3,2-dioxabor-
olan-2-yl)perylene-3,4-dicarboximide (15),[20] building block
4 was synthesized in a multistep sequence, as shown in
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Scheme 3. For the selective cross-coupling of boronic ester
15 with 4-bromonaphthalene-1,8-dicarboxylic anhydride
(16), the introduction of a bromo substituent onto the aryl
group at the N-imide position should come after the [Pd-
able side reaction. Cyclization by using K2CO3 as a base in
ethanolamine completed the synthesis of dyad 1. Disap-
pointingly, it seems that even the use of a weak base
(K2CO3) is still not able to avoid the side reaction, that is,
hydrolysis. Besides unreacted compound 2, the main side
products of reaction b (Scheme 4) are compounds 9 and 17,
both of which contain anhydride groups. It has been report-
ed that the perylene compounds with anhydride groups are
quite polar and easily stick on the silica gel during column
chromatography.[22] For this reason, the final compound (1)
ACHTUNGTRENNUNG(PPh3)4]-catalyzed coupling reaction, according to a litera-
ture procedure.[18] During the coupling reaction (Scheme 3,
step a), it is critical to use an excess amount of naphthalene
derivative 16 to induce the hetero-coupling reaction be-
tween compounds 15 and 16 and minimize the homo-cou-
pling reaction of compound 15. Next, the mono-substitution
(Scheme 3, step b) of com-
pound 17 was accomplished by
the condensation of the anhy-
dride moiety with a solution of
4-bromo aniline (18) in pro-
pionic acid. Compound 19 was
treated with bis(pinacolato)di-
boron (20) to form N-(2,6-diiso-
propylphenyl)-9-[N-(4-bromo-
phenyl)naphthalene-1,8-dicar-
boximide]perylene-3,4-dicar-
boximide (4; Scheme 3, step c).
The dyad (1): Finally, the open
form of the dyad (dyad 2) was
achieved through Suzuki cou-
pling of the PDI part (3a) to
Scheme 3. Synthesis of compounds 17, 19, and 4: a) [PdACHTNUTRGNE(UNG PPh3)4], K2CO3, toluene/H2O (3:2 v/v), 808C, 16 h,
the TDI part (4) with a palladi-
um catalyst (Scheme 4a).
72% yield; b) 4-bromoaniline, propionic acid, 1508C, 16 h, 88% yield; c) [PdCl
to)diboron, 1,4-dioxane, KOAc, 708C, 16 h, 78% yield.
2ACHTNUGTREN(NNUG dppf)]·CH2Cl2, bis(pinacola-
Owing to the difficulties in the
purification of this compound
by column chromatography on
silica gel, the open form of
dyad 2 was obtained in 60%
yield after purification by gel-
permeation
chromatography
(GPC). Owing to its extended
aromatic core, terrylene diimide
showed much lower solubility
than its smaller homologue,
perylene diimide.[21] Concerning
this poor solubility, as well as
the stoichiometry of the TDI
unit, the cyclization reaction
was performed as the final step
(Scheme 4 b) to afford better
reactivity in the coupling reac-
tions. The ring-closing reaction
of the terrylene diimide part for
compound 2 was carried out
under mild conditions, as previ-
ously described.[18] As shown in
Figure 2, the perylene part is
easily hydrolyzed; thus, the cyc-
lization reaction time was kept
relatively short (within 30 min)
Scheme 4. Synthesis of compounds 2 and 1: a) [Pd
ACHTUGNRTNE(NGNU PPh3)4], K2CO3, toluene/H2O (3:2 v/v), 808C, 16 h, 40%
to try to minimize this unfavor- yield; b) ethanolamine, K2CO3, 1608C, 0.5 h, 20% yield.
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Energy Transfer at the Single-Molecule Level
FULL PAPER
analysis was performed at the Department of Chemistry and Pharmacy
of the University of Mainz.
can easily be purified by column chromatography on silica
gel by using a mixture of toluene/CH2Cl2/MeOH as an
eluent to afford dyad 1 in 20% yield.
Synthesis of compound 14: 4-(N-Boc-amino)phenylboronic acid pinacol
ester (12, 554.7 mg, 1.74 mmol) and 1,4-dibromo-2,5-dioctylbenzene (13,
The successful synthesis of dyad 1 will encourage the re-
search of energy transfer at the single-molecule level. Since
2004, dyad 1 has been intensively investigated by single-mol-
ecule spectroscopy, such as the effect of different polymer
hosts, the function of the spacer (para-terphenyl for com-
pound 1), the temperature effects, the method of dual-pulse
excitation, and photoblinking and photobleaching.[7,9,10,12,13]
In addition, we report the traditional chemical characteriza-
tion of compound 1, as well as of all of the intermediates.
The characterization data include proton and carbon NMR
spectra, as well as mass spectra. Other properties of com-
pound 1, such as its absorption, emission, and other optical
properties, can be found in our previous reports.[7,9,10,12]
During the preparation of this manuscript, dyad 1 was fur-
ther investigated by using single-molecule experiments. This
investigation, in the realms of quantum-state detection and
manipulation, will give us further information about elec-
tronic excitation energy transfer. Therefore, we believe that
dyad 1 will continue to be unique in the field of single-mole-
cule-level research.
2 g, 4.34 mmol) were coupled by using a [PdACHTNUTRGNE(UNG PPh3)4] catalyst (251 mg,
0.22 mmol) with K2CO3 (12 g, 86.9 mmol) in toluene (60 mL) and water
(40 mL) at 808C for 24 h. After washing with water, compound 14 was
purified by column chromatography on silica gel (n-hexane/EtOAc 5:1 v/
v). The product was obtained as yellowish oil in 64.3% yield. 1H NMR
(300 MHz, CD2Cl2, 298 K): d=7.30 (d, J=6.0 Hz, 3H), 7.07 (d, J=
6.0 Hz, 2 H), 6.91 (s, 1H), 6.69 (s, 1 H), 2.57 (t, J=9 Hz, 2 H), 2.38 (t, J=
9 Hz, 2 H), 1.54–1.46 (m, 2 H), 1.41 (s, 9H), 1.28–1.06 (m, 22 H), 0.78–
0.73 ppm (m, 6H); 13C NMR (75 MHz, CD2Cl2): d=153.12, 141.07,
140.44, 139.55, 138.08, 136.02, 133.43, 132.20, 130.02, 123.36, 118.45, 80.72,
53.02, 36.10, 32.83, 32.34, 32.29, 31.61, 30.52, 30.16, 29.87, 29.86, 29.79,
29.71, 29.68, 29.58, 28.54, 23.12, 23.09, 14.35 ppm; MS (FD, 8 kV): m/z
calcd for C33H50BrNO2: 572.6; found: 571.2; elemental analysis calcd (%)
for C33H50BrNO2: C 69.21, H 8.80, N 2.45; found: C 69.07, H 8.87, N 2.32.
Synthesis of compound 7: Compound 14 (1 g) was dissolved in CH2Cl2
(27 mL), trifluoroacetic acid (TFA, 3 mL) was added, and the mixture
was stirred for 30 min at RT. After evaporation the reaction mixture to
dryness, the crude product was purified by column chromatography on
silica gel (CH2Cl2) to afford compound 15 (700 mg, 84%) as a yellow oil.
1H NMR (300 MHz, CD2Cl2, 298 K): d=7.31 (s, 1 H), 6.97 (s, 1 H), 6.94
(d, J=3.0 Hz, 2 H), 6.61 (d, J=9 Hz, 2 H), 2.59 (t, J=9 Hz, 2 H), 2.42 (t,
J=9 Hz, 2 H), 1.56–1.46 (m, 2 H), 1.36–1.10 (m, 22 H), 0.81–0.76 ppm (m,
6H); 13C NMR (75 MHz, CD2Cl2): d=146.15, 141.61, 140.54, 139.39,
133.26, 132.30, 131.31, 130.34, 122.75, 114.83, 71.80, 53.17, 53.08, 36.03,
32.81, 32.28, 32.24, 31.58, 30.50, 30.09, 29.80, 29.65, 29.55, 23.06,
14.27 ppm; MS (FD, 8 kV): m/z calcd for C28H42BrN: 472.54; found:
471.2.
Conclusion
Synthesis of compound 3a:
A solution of 2,6-diisopropylaniline (5,
571 mg, 2.96 mmol) and perylene-3,4,9,10-tetracarboxylic dianhydride (6,
871 mg, 2.22 mmol) in imidazole (10 g) was heated at 1408C for 2 h and
then a solution of compound 7 in propionic acid (1 mL) was added. After
4 h, the mixture was poured into a 20% aqueous solution of HCl and the
as-formed red precipitate was filtered. The crude product was purified by
column chromatography on silica gel (CH2Cl2) to afford compound 3a in
about 26% yield (400 mg). 1H NMR (300 MHz, CD2Cl2, 298 K): d=8.58
(t, J=6, 9 Hz, 4H), 8.49 (t, J=6, 9 Hz, 4H), 7.42 (d, J=6 Hz, 3H), 7.36
(s, 1 H), 7.33 (s, 1 H), 7.31 (d, J=3.0 Hz, 1 H), 7.18 (dd, J=3, 6 Hz, 1 H),
7.11 (s, 1 H), 7.08 (d, J=9 Hz, 1 H), 2.96 (t, J=6 Hz, 1 H), 2.71 (t, J=
6 Hz, 1 H), 2.66 (t, J=6 Hz, 2 H), 2.54 (t, J=6 Hz, 2 H), 1.61–1.54 (m,
2 H), 1.28 (d, J=6 Hz, 12H), 1.24–1.18 (m, 22 H), 0.82–0.79 ppm (m,
6H); 13C NMR (75 MHz, CD2Cl2): d=163.94, 163.74, 150.55, 146.54,
141.93, 140.56, 140.26, 139.74, 135.12, 135.06, 134.69, 133.45, 132.29,
131.84, 131.73, 131.29, 130.38, 128.95, 126.82, 125.17, 123.91, 123.88,
123.80, 123.74, 123.68, 54.53, 54.37, 54.22, 54.17, 54.01, 53.86, 53.81, 53.65,
53.45, 53.14, 53.09, 36.06, 34.59, 32.74, 32.30, 32.25, 31.64, 30.44, 30.08,
29.83, 29.79, 29.66, 29.62, 29.05, 24.17, 23.85, 23.08, 14.29 ppm; MS (FD,
8 kV): m/z calcd for C64H65BrN2O4: 1006.12; found: 1006.5.
We have reported a synthetic approach to a dyad that con-
sists of three parts, that is, donor–bridge–acceptor. Dyad 1,
which is an attractive candidate for fundamental EET stud-
ies, was designed based on the considerations of its photo-
physical properties for electronic excitation energy transfer,
as well as the solubilities and accessibilities of each building
block in the synthesis. The preparation of asymmetrically
substituted PDI and TDI units represents a versatile strat-
egy and the purification of the respective components is
readily achieved. Thus, by using well-designed reactions, an
efficient route to dyad 1 is presented. This new synthetic
strategy will not only contribute to the rapid preparation of
this dyad (1), but also to the design of functionalized PDI,
TDI, and their derivatives for the assembly of other, more-
complicated multichromophore systems.
Synthesis of compound 19: Compounds 15[20] and 17[18] were prepared as
described in the literature. Compounds 15 (1.8 g, 2.96 mmol) and 16
(1.64 g, 5.93 mmol) were dissolved in toluene (250 mL), a solution of
K2CO3 (8.2 g, 0.059 mol) in water (50 mL) and EtOH (15 mL) was
Experimental Section
added, and the mixture was flushed with argon. The [PdACTHNUTRGNE(UNG PPh3)4] catalyst
(171 mg, 0.148 mmol) was added and the reaction mixture was stirred
under an argon atmosphere for 16 h at 908C. After cooling to RT, the re-
action mixture was poured into a 20% solution of HCl (200 mL). The re-
sulting product (17) was collected by filtration and used directly in the
next step without further purification (1.45 g, 72%). Compound 17 (1.2 g,
1.77 mmol), 4-bromoaniline (18, 0.609 g, 3.54 mmol), and propionic acid
(40 mL) were added into a 100 mL flask and the reaction mixture was
stirred for 16 h at 1508C. Water (150 mL) was poured into the cooled sol-
ution to obtain a red precipitate, which was collected by filtration. The
product was purified by column chromatography (CH2Cl2/pentane/
EtOAc, 10:20:1) to give compound 19 (1.3 g, 88%). 1H NMR (500 MHz,
C2D2Cl4, 393 K): d=8.68 (d, J=10.0 Hz, 1 H), 8.61–8.56 (m, 3H), 8.52 (d,
General: The solvents were of commercial grade. Perylenemonoimide 15
was supplied by BASF AG. Column chromatography was performed on
silica gel (Geduran Si60, Merck). 1H NMR and 13C NMR spectra were re-
corded on Bruker DRX 500 (500 and 125 MHz, respectively), Bruker
AMX 300 (300 and 75 MHz, respectively), or Bruker Avance 700 spec-
trometers (700 and 175 MHz, respectively). Mass spectra were recorded
on a Bruker MALDI-TOF spectrometer. FD mass spectra were recorded
on a VG-Instruments ZAB 2-SE-FDP instrument. UV/Vis data were ob-
tained on a Perkin–Elmer Lambda 9. Fluorescence spectra were meas-
ured on SPEX Fluorolog 2 Type 212 or SPEX Fluorolog 3 spectrometers.
[Pd
ACHTUNGTRENNUNG(PPh3)4] and [PdCl2ACHTUNGTRENNUNG(dppf)]·CH2Cl2 (dppf=1,1’-bis(diphenylphospha-
nyl)ferrocene) catalysts were purchased from Sigma–Aldrich. Elemental
Chem. Eur. J. 2013, 00, 0 – 0
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K. Mꢀllen et al.
J=10 Hz, 1 H), 8.48 (d, J=10 Hz, 1 H), 8.43 (t, J=5 Hz, 2 H), 7.84–7.79
(m, 2 H), 7.62–7.60 (m, 3H), 7.57 (t, J=5 Hz, 1 H), 7.44 (t, J=5, 10 Hz,
1 H), 7.37–7.33 (m, 2 H), 7.22 (d, J=5 Hz, 2 H), 7.17 (d, J=10 Hz, 2 H),
2.69 (q, J=5, 10 Hz, 2 H), 1.10 ppm (d, J=5 Hz, 12 H); 13C NMR
(126 MHz, C2Cl4D2, 393 K): d=164.09, 146.47, 145.29, 139.43, 137.61,
132.84, 132.20, 131.41, 131.05, 130.45, 129.54, 128.15, 127.79, 124.42,
124.27, 123.39, 121.34, 121.23, 120.83, 74.62, 74.40, 74.18, 29.69,
24.28 ppm; MS (FD, 8 kV): m/z calcd for C52H35BrN2O4: 831.75; found:
833.6; MS (MALDI-TOF): m/z: 834.23.
123.27, 121.75, 120.44, 99.77, 74.22, 74.13, 74.09, 74.07, 74.00, 73.91, 73.78,
32.72, 31.81, 31.23, 29.58, 29.54, 29.42, 29.19, 29.15, 23.88, 22.54, 13.90,
13.83, 0.88 ppm; MS (MALDI-TOF): m/z calcd for C116H98N4O8: 1676.04;
found: 1677.05.
Acknowledgements
This work was supported by the German Science Foundation (SFB 625)
and by a National Research Foundation of Korea grant, funded by the
Korean Government (Ministry of Education, Science and Technology,
NRF-2011-1-C00069). We also acknowledge Dr. Joseph Krumpfer for his
help in the preparation of this manuscript.
Synthesis of compound 4:
A mixture of compound 19 (300 mg,
0.36 mmol), bis(pinacolato)diboron (20, 275 mg, 1.08 mmol), and potassi-
um acetate (35.4 mg, 0.36 mmol) was dissolved in 1,4-dioxane (20 mL)
under an argon atmosphere. The [PdCl2ACTHNUTRGNEN(UG dppf)]·CH2Cl2 catalyst
(14.73 mg, 0.018 mmol) was added and the resulting mixture was stirred
overnight at 808C. The solvent was completely evaporated and the mix-
ture was washed with distilled water and CH2Cl2 twice each. The CH2Cl2
layer was collected, dried over Na2SO4, and the crude product was puri-
fied by column chromatography on silica gel (CH2Cl2/pentane/EtOAc,
[1] T. Ha, T. Enderle, D. F. Ogletree, D. S. Chemla, P. R. Selvin, S.
Weiss, Proc. Natl. Acad. Sci. USA 1996, 93, 6264–6268.
[2] E. A. Lipman, B. Schuler, O. Bakajin, W. A. Eaton, Science 2003,
301, 1233–1235.
[3] B. Schuler, E. A. Lipman, P. J. Steinbach, M. Kumke, W. A. Eaton,
Proc. Natl. Acad. Sci. USA 2005, 102, 2754–2759.
[4] M. Antonik, S. Felekyan, A. Gaiduk, C. A. M. Seidel, J. Phys.
Chem. B 2006, 110, 6970–6978.
[5] M. Cotlet, R. Gronheid, S. Habuchi, A. Stefan, A. Barbafina, K.
Mꢀllen, J. Hofkens, F. C. De Schryver, J. Am. Chem. Soc. 2003, 125,
13609–13617.
[6] J. Hernando, J. P. Hoogenboom, E. M. H. P. van Dijk, J. J. Garcia-
Lopez, M. Crego-Calama, D. N. Reinhoudt, N. F. van Hulst, M. F.
Garcia-Parajo, Phys. Rev. Lett. 2004, 93, 236404/1–236404/4.
[7] a) R. Metivier, F. Nolde, K. Mꢀllen, T. Basche, Phys. Rev. Lett. 2007,
98, 047802/1–047802/4; b) C. G. Hꢀbner, V. Ksenofontov, F. Nolde,
K. Mꢀllen, T. Basche, J. Chem. Phys. 2004, 120, 10867–10870; c) B.
Fuckel, G. Hinze, G. Diezemann, F. Nolde, K. Mꢀllen, J. Gauss, T.
Baschꢂ, J. Chem. Phys. 2006, 125, 144903/144901–144903/144907.
[8] H. W. Bahng, M. C. Yoon, J. E. Lee, Y. Murase, T. Yoneda, H. Shi-
nokubo, A. Osuka, D. Kim, J. Phys. Chem. B 2012, 116, 1244–1255.
[9] G. Hinze, R. Metivier, F. Nolde, K. Mꢀllen, T. Basche, J. Chem.
Phys. 2008, 128, 124516/1–124516/12.
[10] M. Haase, C. G. Hubner, F. Nolde, K. Mꢀllen, T. Basche, Phys.
Chem. Chem. Phys. 2011, 13, 1776–1785.
[11] B. Fuckel, A. Kohn, M. E. Harding, G. Diezemann, G. Hinze, T.
Basche, J. Gauss, J. Chem. Phys. 2008, 128, 074505/1–074505/13.
[12] B. Fuckel, G. Hinze, F. Nolde, K. Mꢀllen, T. Basche, Phys. Rev. Lett.
2009, 103, 103003/1–103003/4.
[13] F. Nolde, Dissertation, Johannes-Gutenberg-Universitꢃt Mainz, Ger-
many, 2008.
[14] A. Herrmann, K. Mꢀllen, Chem. Lett. 2006, 35, 978–985.
[15] A. C. Grimsdale, K. Mꢀllen, Angew. Chem. 2005, 117, 5732–5772;
Angew. Chem. Int. Ed. 2005, 44, 5592–5629.
[16] P. Kissel, S. Breitler, V. Reinmuller, P. Lanz, L. Federer, A. D.
Schluter, J. Sakamoto, Eur. J. Org. Chem. 2009, 2953–2955.
[17] a) J. M. Tour, Adv.Mater. 1994, 6, 190–198; b) M. Banerjee, R.
Shukla, R. Rathore, J.Am.Chem.Soc. 2009, 131, 1780–1786; c) S.
Grunder, C. Valente, A. C. Whalley, S. Sampath, J. Portmann, Y. Y.
Botros, J. F. Stoddart, Chem. Eur. J. 2012, 18, 45–63.
[18] F. Nolde, J. Q. Qu, C. Kohl, N. G. Pschirer, E. Reuther, K. Mꢀllen,
Chem. Eur. J. 2005, 11, 3959–3967.
[19] a) A. Wicklein, A. Lang, M. Muth, M. Thelakkat, J.Am.Chem. Soc.
2009, 131, 14442–14453; b) N. Pasaogullari, H. Icil, M. Demuth,
Dyes Pigm. 2006, 69, 118–127; c) S. Asir, A. S. Demir, H. Icil, Dyes
Pigm. 2010, 84, 1–13.
10:20:1 v/v) to afford compound
4 (250 mg, 79%) as a red solid.
1H NMR (700 MHz, CD2Cl2, 393 K): d=8.70 (d, J=7.0 Hz, 1 H), 8.63–
8.60 (m, 3H), 8.58–8.55 (m, 2 H), 8.51–8.49 (m, 2 H), 7.91 (d, J=7 Hz,
2 H), 7.87 (d, J=7 Hz, 1 H), 7.83 (d, J=7 Hz, 1 H), 7.68 (d, J=7 Hz,
1 H), 7.60 (t, J=7 Hz, 1 H), 7.47 (t, J=7 Hz, 1 H), 7.43 (t, J=7 Hz, 1 H),
7.40 (d, J=7 Hz, 1 H), 7.33 (dd, J=7 Hz, 4H), 2.72–2.68 (m, 2 H), 1.30
(s, 12 H), 1.07 ppm (dd, J=7 Hz, 12 H); 13C NMR (175 MHz, CD2Cl2):
d=164.03, 163.98, 146.14, 135.56, 131.96, 131.53, 131.37, 130.86, 129.26,
129.11, 128.27, 128.20, 127.62, 127.30, 124.29, 124.03, 123.41, 120.86,
120.76, 84.10, 53.74, 53.59, 53.44, 53.28, 53.13, 29.69, 29.10, 24.68,
23.72 ppm; MS (FD, 8 kV): m/z calcd for C58H47BN2O6: 878.81; found:
878.9; MS (MALDI-TOF): m/z: 880.55.
Synthesis of compound 2: Compounds 3a (60 mg, 0.059 mmol) and 4
(78.6 mg, 0.089 mmol) were dissolved in toluene (16 mL), a solution of
K2CO3 (82.4 mg, 0.59 mmol) in water (3 mL) and EtOH (1 mL) was
added, and the mixture was flushed with argon. The [PdACTHNUTRGNE(UNG PPh3)4] catalyst
(3.45 mg, 0.003 mmol) was added and the reaction mixture was stirred
under an argon atmosphere for 16 h at 908C. The reaction mixture was
cooled to RT and the resulting salt was collected by filtration. The salt
was poured into concentrated HCl (50 mL) and the resulting mixture was
collected by filtration and dried in a vacuum oven overnight. The crude
compound was purified by gel-permeation chromatography (THF) to
afford compound 2 as a red solid (40 mg, 40%). 1H NMR (300 MHz,
CD2Cl2, 298 K): d=8.76 (dd, J=6 Hz, 1 H), 8.69 (d, J=9 Hz, 1 H), 8.63–
8.57 (m, 6H), 8.56 (d, J=3 Hz, 2 H), 8.52 (s, 1H), 8.49 (d, J=3 Hz, 1 H),
8.45 (d, J=9 Hz, 3H), 7.91–7.84 (m, 2 H), 7.68 (d, J=6 Hz, 1 H), 7.61 (t,
J=6, 9 Hz, 1 H), 7.56 (d, J=9 Hz, 4H), 7.46–7.37 (m, 8H), 7.32–7.29 (m,
2 H), 7.26 (s, 3H), 7.21 (dd, J=3, 9 Hz, 1 H), 7.11 (d, J=9 Hz, 1 H),
2.75–2.63 (m, 8H), 1.27–1.18 (m, 24H), 1.10–1.06 (m, 24H), 0.82–0.77 (m,
6H); 13C NMR (75 MHz, CD2Cl2): d=164.69, 164.53, 164.39, 163.97,
163.86, 163.79, 151.86, 150.57, 146.53, 145.02, 142.84, 142.74, 140.63,
139.71, 138.08, 137.74, 137.49, 136.23, 136.12, 135.41, 135.19, 135.09,
134.89, 134.52, 133.81, 133.27, 132.32, 132.21, 131.93, 131.77, 131.59,
131.32, 130.94, 130.60, 130.29, 130.05, 129.96, 129.66, 129.54, 129.33,
128.95, 128.69, 128.64, 128.00, 127.75, 127.32, 127.07, 126.84, 125.80,
125.21, 124.65, 124.51, 124.43, 123.96, 123.91, 123.87, 123.77, 123.73,
123.46, 121.83, 121.70, 121.21, 121.12, 34.61, 34.49, 33.01, 32.31, 31.94,
30.23, 24.19, 24.15, 24.07, 23.89, 23.11, 21.22, 14.33 ppm; MS (MALDI-
TOF): m/z calcd for C116H100N4O8: 1678.06; found: 1679.14.
Synthesis of compound 1: Compound 2 (40 mg, 0.023 mmol), K2CO3
(165 mg, 1.19 mmol), and ethanolamine (1 mL) were stirred under an
argon atmosphere for 0.5 h at 1608C. After cooling to RT, the solution
was poured into water (50 mL). The precipitate was collected by filtra-
tion, washed with water, dried under vacuum, and purified by column
chromatography on silica gel (toluene/CH2Cl2/MeOH 5:10:1 v/v) to
afford compound 1 as a blue solid (8 mg, 20%). 1H NMR (500 MHz,
C2D2Cl4, 393 K): d=8.70–8.61 (m, 15H), 8.56–8.53 (m, 4H), 7.50 (dd, J=
10 Hz, 4H), 7.37–7.33 (m, 7H), 7.23 À7.21 (m, 6H), 2.70–2.64 (m, 8H),
1.59–1.56 (m, 6H), 1.32–1.22 (m, 24H), 1.1 ppm (dd, J=5 Hz, 24H);
13C NMR (126 MHz, C2D2Cl4, 393 K): d=163.42, 131.78, 128.47, 123.95,
[20] T. Weil, E. Reuther, C. Beer, K. Mꢀllen, Chem. Eur. J. 2004, 10,
1398–1414.
[21] F. O. Holtrup, G. R. J. Mꢀller, H. Quante, S. Defeyter, F. C. De-
Schryver, K. Mꢀllen, Chem. Eur. J. 1997, 3, 219–225.
[22] Y. Avlasevich, C. Li, K. Mꢀllen, J. Mater. Chem. 2010, 20, 3814–
3826.
Received: February 4, 2013
Published online: && &&, 0000
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