Synthetic routes to core-fluorinated perylene bisimide dyes and their properties

Article abstract of DOI:10.1515/znb-2009-0621

Numerous core-fluorinated perylene bisimide (PBI) dyes with various substituents at the imide positions have been synthesized by different methods. Core-difluorinated PBIs 4a-f are obtained by imidization of difluoro-substituted perylene bisanhydride 1 wi

Full text of DOI:10.1515/znb-2009-0621

Synthetic Routes to Core-fluorinated Perylene Bisimide Dyes
and their Properties
Ru¨diger Schmidta, Peter Osswalda, Martin Ko¨nemannb, and Frank Wu¨rthnera
a Universita¨t Wu¨rzburg, Institut fu¨r Organische Chemie, Am Hubland, 97074 Wu¨rzburg, Germany
b BASF SE, GVP/C, 67056 Ludwigshafen, Germany
Reprint requests to Prof. Dr. F. Wu¨rthner. Fax +49-(0)931-318 4756.
E-mail: wuerthner@chemie.uni-wuerzburg.de
Z. Naturforsch. 2009, 64b, 735 – 746; received March 26, 2009
Dedicated to Professor Gerhard Maas on the occasion of his 60th birthday
Numerous core-fluorinated perylene bisimide (PBI) dyes with various substituents at the imide
positions have been synthesized by different methods. Core-difluorinated PBIs 4a–f are obtained by
imidization of difluoro-substituted perylene bisanhydride 1 with appropriate primary amines or, alter-
natively, by nucleophilic halogen exchange reactions (Halex process) of the corresponding dibromo-
substituted PBIs 2a–d,f with potassium fluoride. Core-tetrafluorinated PBIs 5a–c could also be syn-
thesized by halogen exchange reactions of the respective tetrachlorinated PBIs 3a–c. In particular,
core-fluorinated perylene bisimide pigments 4h, 5h containing hydrogen atoms in the imide posi-
tions could be obtained for the first time by deprotection of α-methylbenzyl-substituted precursors.
Compared with core-unsubstituted perylene bisimides, these fluorinated dyes display hypsochromi-
cally shifted absorption and fluorescence spectra, and they exhibit fluorescence quantum yields up to
unity, enabling bright yellow emission. The electrochemical properties of these electron-poor pery-
lene bisimides have been studied. Furthermore, the packing features of a tetrafluorinated PBI deriva-
tive in the solid state have been discussed.
Key words: Dyes and Pigments, Fluorination, n-Type Semiconductors, Perylene Bisimides
Introduction
devices and OFETs has been demonstrated [10]. Re-
cently, high charge carrier mobilities up to 2.1 cm2
V−1 s−1 were determined for vapor-deposited films
[10c]. PBIs bearing four chlorine atoms in the bay area
(1,6,7,12-positions) have also been investigated for ap-
plications in thin film transistors, and charge carrier
mobilities up to 0.18 cm2 V−1 s−1 were determined
for vapor-deposited films [11]. Furthermore, the intro-
duction of two strongly electron-withdrawing cyano
groups in the bay area has significantly improved the
applicability of PBI dyes with air-stable charge carrier
Electronic materials based on organic semiconduct-
ing molecules are becoming increasingly important
due to their widespread applications in organic field
effect transistors (OFETs) [1], light emitting diodes
(OLEDs) [2], and solar cells [3]. Whilst several classes
of organic materials with high p-type charge carrier
mobility have been known for a long time, their n-
type counterparts have become available only recently.
One general approach toward n-type semiconducting
materials is the introduction of perfluorinated sub-
stituents or other electron-withdrawing groups to elec-
tron-poor extended aromatic π systems, e. g., naph-
thalene bisimides [4] and thiazols [5], or even at
originally electron-rich π-conjugated systems, e. g.,
oligothiophenes [6], acenes [7], and phthalocyanines
[8]. Among organic n-type semiconductors, perylene
bisimide (PBI) dyes are very auspicious candidates
since core-unsubstituted perylene bisanhydride and
PBIs are considered to be the archetype n-type semi-
conducting materials [9]. Their application in solar cell
mobilities up to 0.64 cm2 V−1 −1 [12].
s
As the incorporation of electron-withdrawing, in
particular, fluorine groups afforded significant im-
provements of the n-type semiconducting properties
for several classes of organic semiconductors [8a, 12],
we have recently introduced the first examples of core-
fluorinated perylene bisimides [13], and demonstrated
very recently that such fluorinated PBIs indeed af-
ford air-stable n-channel semiconductors [14]. Thus,
core-fluorinated PBIs are highly promising for OFETs,
and hence further derivatives with varied imide sub-
c
0932–0776 / 09 / 0600–0735 $ 06.00 ꢀ 2009 Verlag der Zeitschrift fu¨r Naturforschung, Tu¨bingen · http://znaturforsch.com
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R. Schmidt et al. · Synthetic Routes to Core-fluorinated Perylene Bisimide Dyes and their Properties
R =
Zn(OAc)2,
F
6a b d e
),
R-NH2
(
, , ,
O
O
O
O
a:
b:
180 °C, quinoline
O
O
F
Imidization
O
N
O
O
N
O
F
1
R
R
Br
O
N
O
O
N
O
F
18-crown-6,
KF, sulfolane,
160 °C
c:
d:
−
4a f
R
R
Br
HALEX process
−
2a d, f
ClCl
F
F
O
N
O
O
N
O
O
N
O
O
N
O
CNC+Cl-, KF,
sulfolane,
160-180 °C
C12H25
C12H25
e:
f:
R
R
R
R
ClCl
F
5a d
F
−
C12H25
−
3a d
N
N
Scheme 1. Synthe-
sis of core-fluorina-
ted PBIs 4 and 5.
CNC+
=
N
N
N
Table 1. Yields (%) of difluorinated PBIs 4a–f by imidiza-
tion of perylene bisanhydride 1 and Halex reaction of PBIs
2a–d, f.
stituents are in demand. Here we report the synthesis
of a broad spectrum of core-fluorinated PBI deriva-
tives by different routes and discuss their optical and
electronic properties. Moreover, core-fluorinated pery-
lene bisimides without imide substituents are also of
interest as the corresponding parent compound itself is
an n-type semiconductor, and incorporation of fluorine
atoms into the bay area should enhance its electron-
accepting properties. However, such core-fluorinated
PBIs are so far not known and are considered to be dif-
ficult to purify owing to their extremely low solubility.
Here we present for the first time di- and tetrafluori-
anted PBIs with N-H imide functionality that are made
accessible by a novel deprotection procedure devel-
oped in our group [15].
— Method —
PBI
Imidization
13
Halex reactiona
4a
4b
4c
4d
4e
4f
59b
60
27
c
46
10
46b
c
12
c
25
c
a
b
Catalyst: 18-crown-6; previously communicated [13]; not per-
formed.
orinated perylene bisanhydride 1 was obtained by the
reaction of dibrominated p◦erylene bisanhydride with
potassium fluoride at 160 C in anhydrous sulfolane
containing 18-crown-6 [16], while the dibrominated
and tetrachlorinated precursor PBIs 2 and 3 were syn-
thesized according to literature methods [17]. Imidiza-
tion of difluorinated perylene bisanhydride 1 with
amines 6a, b, d or e afforded the corresponding di-
fluorinated perylene bisimides 4a, b, d and e in rel-
atively lower yields (see Table 1). The reasons for
these unsatisfactory yields might be, on the one hand,
the insufficient purity of the starting material 1 [16]
and, on the other hand, facile nucleophilic exchange
Results and Discussion
Synthesis
The core-fluorinated perylene bisimides 4 and 5
(Scheme 1) were synthesized by a sequence of halogen
exchange and imidization reactions and both routes,
i. e., halogen exchange of perylene bisanhydrides and
subsequent imidization, or first imidization and sub-
sequent halogen exchange, were explored. The diflu-
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R. Schmidt et al. · Synthetic Routes to Core-fluorinated Perylene Bisimide Dyes and their Properties
737
Scheme 2. Synthesis of PBIs
4h, 5h and bisanhydride 7.
Table 2. Yields of tetrafluorinated PBIs 5a–c by the Halex
process of chlorinated PBIs 3a–c.
of fluorine atoms by aliphatic amines. Indeed, for the
reaction of perylene bisanhydride 1 with an excess
amount of the more nucleophilic primary amine n-
octylamine high quantities of a green byproduct with
an NH-octyl substituent in bay position were obtained.
Thus, the alternative route, namely, halogen exchange
reaction (Halex process) [18] of dibrominated perylene
bisimides 2a–d and f was chosen. This reaction was
PBI
5a
5b
5c
Yield (%)
3
20a
18a
a
These yields are based on the conversion of the PBIs 3b and 3c,
respectively, as about 50 % of the starting materials was recovered
(see Experimental Section).
Notably, the core-fluorinated PBIs with NH imide
carried out in sulfolane with potassium fluoride and groups 4h and 5h could be synthesized for the first
catalytic amounts of 18-crown-6, and indeed signifi- time by the cleavage of the α-methylbenzyl imide
cantly higher yields (between 25 % and 60 %, see Ta- substituents of PBIs 4b and 5b, respectively, with
ble 1) were achieved. Notably, the use of the N,N-di- boron tribromide in dichloromethane in nearly quan-
methylimidazolidino-tetramethylguanidiniumchloride titative yield (Scheme 2). These fluorinated PBIs are
(CNC+) catalyst, which was previously applied for insoluble pigments, and thus could be characterized
Halex reactions [18], was less successful for the flu- only by mass spectrometry. It is noteworthy that
orination of dibrominated PBIs [13].
the above-mentioned deprotection method is appli-
cable not only to PBI derivatives bearing electron-
withdrawing bay substituents, but also to those con-
taining electron-donating core substituents such as
amino [15a] and aryloxy groups [15b]. Thus, boron
tribromide-mediated deprotection of α-methylbenzyl
imide substituents is a quite general method with broad
scope for the synthesis of core-substituted perylene
bisimides with NH imide groups.
By saponification of 5c the tetrafluorinated perylene
bisanhydride 7 was obtained in a yield of 94 %. Mass
spectrometry revealed a trifluoro-hydroxy-substituted
perylene as an impurity, which obviously originates
from the nucleophilic substitution of one fluorine atom
by potassium hydroxide. The saponification of 4c led
also to an insoluble compound, but the desired difluori-
nated bisanhydride could neither be isolated nor iden-
tified.
The Halex reaction of tetrachlorinated perylene
bisimides 3a–c afforded the corresponding tetrafluo-
rinated PBIs 5a–c in lower yields (Table 2), while
for PBI 3d no conversion was observed. The deficient
yields of these reactions can be explained by the ster-
ical congestion imparted by four halogen atoms and
the four step reaction sequence required for complete
halogen exchange. For this Halex reaction, the CNC+
catalyst was used, as this catalyst was developed par-
ticularly for the chloride-fluoride exchange [18], while
18-crown-6 is a quite general phase transfer catalyst.
The solubility of PBIs in sulfolane has a strong influ-
ence on the yield, and thus for the almost insoluble
PBI 3d no conversion could be observed, and the yield
of the poorly soluble dye 5a (3 %) was significantly
lower than those for the better soluble compounds 5b
and 5c (20% and 18 %, respectively). Replacement of
the CNC+ with 18-crown-6 catalyst led to even lower
yields.
All the di- and tetrafluorinated PBIs were charac-
1
terized by H and 19F NMR spectroscopy and high-
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R. Schmidt et al. · Synthetic Routes to Core-fluorinated Perylene Bisimide Dyes and their Properties
Fig. 1. UV/Vis absorption spectra (left) and fluorescence emission (right) spectra of 4f (dashed lines) and 5b (solid lines) in
dichloromethane.
Table 3. UV/Vis absorption and fluorescence emission prop-
erties of core-fluorinated perylene bisimide dyes 4 and 5 in
dichloromethane.
of the related unsubstituted PBI derivatives. Such hyp-
sochromic shifts are unprecedented for PBI dyes and
lead for the first time to a bright yellow fluorescence for
this class of fluorophores [13]. The similar absorption
coefficients and vibronic progressions in the spectra of
difluorinated and unsubstituted perylene bisimides are
in agreement with a flat, rather than a twisted, perylene
core as has been demonstrated by single crystal X-ray
analysis of a difluorinated PBI derivative [13].
The absorption maxima for tetrafluorinated PBIs
5a–c are even further shifted to shorter wavelengths
(503 to 500 nm). Their absorption coefficients are de-
creased considerably as compared to those of diflu-
orinated derivatives 4a–f, which can be attributed to
the population of conformations with a twisted pery-
lene core as demonstrated for 5a by X-ray analy-
sis (see below). The fluorescence spectra of all core-
fluorinated PBIs fulfill the mirror image condition as
exemplified for compounds 4f and 5b in Fig. 1. The
core-fluorinated PBIs presented here show rather small
PBI
λabs (nm)
ε (M−1 cm−1
)
λem (nm)
Φfl
a
4ab
4b
4c
508
510
508
508
511
508
500
503
501
81300
80900
76600
89000
96900
83300
66000
68400
71900
514
518
516
513
518
515
509
514
513
1.00
0.98
1.00
0.98
0.35
1.00
0.88
0.85
1.00
4db
4e
4f
5ab
5b
5c
a
Average deviation 0.03; the quantum yields were determined
at three different wavelenghts with N,Nꢀ-di(2,6-diisopropylphenyl)-
perylene-3,4 : 9,10-tetracarboxylic acid bisimide (Φfl = 1.00 in chlo-
b
roform) as reference (for details see Experimental Section); taken
from ref. [13] and shown for completeness.
resolution mass spectrometry (see Experimental Sec-
tion).
Optical properties
The optical properties of the perylene bisimide dyes Stokes shifts (5 – 12 nm), indicating a quite rigid struc-
4 and 5 were investigated by UV/Vis and fluorescence ture of the molecules. Nearly all of the dyes exhibit
spectroscopy. Absorption and fluorescence spectra of very high fluorescence quantum yields (85 – 100%)
the difluorinated PBI 4f and its tetrafluorinated deriva- which correspond very well with the values reported
tive 5b are shown as representative examples in Fig. 1, for unsubstituted PBI derivatives. The only exception
and the optical data for these compounds are collected is dye 4e, which has a lower fluorescence quantum
in Table 3. The absorption spectra of the difluori- yield of 35 %. This value is in good accordance with
nated compounds 4a–f show a well-defined vibronic the low quantum yield of the parent chromophore
fine structure of the S0–S1 transition with maxima be- (without core fluorination) bearing identical imide sub-
tween 508 and 511 nm, depending on the imide sub- stituents [19], where the fluorescence quenching could
stituent. The absorption and emission maxima of di- be attributed to a photoinduced electron transfer pro-
fluorinated derivatives are hypsochromically shifted by cess from the electron-rich imide substituents to the
16 and 17 nm, respectively, in comparison with those electron-poor PBI core.
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R. Schmidt et al. · Synthetic Routes to Core-fluorinated Perylene Bisimide Dyes and their Properties
739
Table 4. First and second half-wave reduction potentials (in
V vs. Fc/Fc+) of core-fluorinated perylene bisimides 4 and 5.
PBI E (PBI/PBI−)(V)a E (PBI−/PBI2−)(V)a ε LUMO (eV)b
difluorinated PBIs 4a–f were observed between −1.02
and −1.08 V vs. Fc/Fc+, while the second reduction
waves appeared in the range of −1.26 to −1.29 V.
Both first and second reduction waves of tetrafluori-
nated PBIs 5a–c were observed at slightly higher po-
tentials (−0.98 and −1.21 V vs. Fc/Fc+), indicating
that the tetrafluorinated perylene bisimides are easier
to reduce than the corresponding difluorinated deriva-
tives. In regard to the effect of imide substituents on
the redox properties of these PBIs, it is to note that the
aromatic substituent in 4e led to a 20 – 60 mV higher
reduction potential compared to aliphatic substituents.
Interestingly, the influence of fluorine core sub-
stituents on the redox potential of PBIs is very small.
The core-unsubstituted reference compound N,Nꢀ-
di(cyclohexyl)-perylene-3,4:9,10-tetracarboxylic acid
bisimide shows under identical conditions a first reduc-
tion potential of −1.10 V, which is only 20 mV lower
than the potential of the difluorinated compound 4d.
In contrast, significantly larger effects are observed for
core-chlorinated or core-brominated PBIs [20].
4ac
4b
4c
−1.04
−1.04
−1.07
−1.08
−1.02
−1.04
−0.98
−0.98
−0.98
−1.26
−1.25
−1.28
−1.29
−1.26
−1.25
−1.22
−1.21
−1.21
−3.76
−3.76
−3.73
−3.72
−3.78
−3.76
−3.82
−3.82
−3.82
4dc
4e
4f
5ac
5b
5c
a
Measured in 0.1 M solution of Bu4NPF6 in dichloromethane with
a scan rate of 100 mV s−1; ferrocene served as internal standard;
b calculated according to the literature method by using the equation:
εLUMO = −4.8 eV – E(PBI/PBI−) [21]; c taken from ref. [13] and
shown for completeness.
Electrochemical properties
The electrochemical properties of core-fluorinated
PBIs 4 and 5 were investigated by cyclic voltamme-
try, and their reduction potentials are given in Table 4.
Exemplified cyclic voltammograms for 4b and 5c are
shown in Fig. 2. The fluorinated PBIs exhibit two re-
versible reduction waves, whereas within the accessi-
ble scanning range in dichloromethane no oxidation
waves could be detected. The first reduction waves for
Properties in the solid state
We have presented the crystal structure of the
tetrafluorinated PBI 5a in our recently published let-
ter [13]. However, the highly interesting packing prop-
erties of this PBI in the solid state that are related to
the conformational chirality of core-substituted PBIs,
imparted by a dihedral twist of the perylene core [22],
were not discussed there. We now turn to this aspect
in this full paper. The molecular structure of PBI 5a
is depicted in Fig. 3. For this derivative, bearing four
fluorines at the bay position, the twisting of the pery-
lene core was surprisingly unsymmetrical but, as ex-
pected, significantly larger than for difluorinated pery-
lene bisimide dyes [13]. Thus, the dihedral angle of
the one bay area is ∼17◦ (carbon atoms C16–C4–
C3–C22), the other being ∼28◦ (carbon atoms C24–
C5–C7–C15). The extended twist angle for 5a can
mainly be attributed to the repulsive interactions of the
strongly electronegative fluorine atoms at the bay area.
The unsymmetrical distortion is most probably in-
duced by packing effects and intermolecular interac-
tions in the crystal lattice, allowing a denser arrange-
ment in the solid state. The fluorine atoms possess a
van-der-Waals radius of 135 pm, which is in between
that of oxygen (140 pm) and hydrogen (120 pm). Due
to the small size of the fluorine atom the difluorinated
PBIs exhibit a nearly planar perylene core quite sim-
Fig. 2. Cyclic voltammograms of 4b (above) and 5c (below).
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R. Schmidt et al. · Synthetic Routes to Core-fluorinated Perylene Bisimide Dyes and their Properties
Fig. 3. Ball and stick representation of the molecular structure of PBI 5a in the crystal.
Fig. 5. Separation of aliphatic imide substituents and aro-
matic cores for PBI 5a in the crystal.
The crystal packing of 5a is shown in Fig. 4. The dye
molecules are arranged in stacks along the a axis of the
unit cell, but share less than 50 % of their perylene core
surface. Two molecules of 5a with opposite chirality
are found in one unit cell (blue: P-enantiomer, red:
M-enantiomer). Furthermore, no solvent molecules are
embedded in the crystal lattice, which is quite un-
usual for a perylene molecule of this size, and only
the outer areas of the octyl substituents are partly dis-
ordered.
˚
The closest intermolecular contacts of about 2.4 A,
which can be assigned to CH···O contacts, are found
between hydrogen atoms of the perylene core and oxy-
gen atoms of imide groups. The closest π-π interac-
tions are found between neighboring molecules of op-
posite chirality (P- and M-enantiomer) in one stack and
Fig. 4. Molecular packing in crystals of 5a. The P-enan-
tiomers are shown in blue and the M-enantiomers in red. Dis-
tances between naphthalene subunits of the two neighboring
˚
molecules are given in A. Imide substituents are omitted for
clarity, (color online).
˚
are in the range of 3.2– 3.3 A, which is smaller than the
˚
ilar to that of the unsubstituted PBIs [13, 23], while
tetrachloro- and tetraphenoxy-substituted PBIs possess
a torsion angle of 25 – 37◦ in the solid state [24]. Ac-
cordingly, the dihedral angles of 17◦ and 28◦ observed
for 5a are in the expected range.
interplane spacing (3.37 A) of graphite [25]. The inter-
molecular distances between the π surfaces of naph-
thalene units in a stack are identical, although the con-
tacts to the upper and lower neighboring molecules are
slightly different along a given stack. Furthermore, as
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R. Schmidt et al. · Synthetic Routes to Core-fluorinated Perylene Bisimide Dyes and their Properties
741
shown in Fig. 5, the lipophilic octyl chains and the aro- ica gel (Si 60, 40 – 63 µm) were purchased from com-
mercial sources, while 3,4,5-tridodecylaniline was synthe-
sized according to the literature [26]. Potassium fluoride
was dried in vacuum (60 ◦C/10−3 mbar), sulfolane was
fractionally distilled under vacuum prior to use. All other
chemicals and solvents were used as received. The cata-
lyst (N,Nꢀ-dimethyl-imidazolidino)-tetramethylguanidinium
chloride (CNC+) was synthesized according to literature
procedures [18]. 1H NMR spectra (400 MHz) were recorded
on a Bruker Advance 400 spectrometer; chemical shifts
in CDCl3 are given relative to CHCl3 (δ = 7.26 ppm).
19F NMR spectra (376.5 MHz) were recorded on a Bruker
Avance 400 spectrometer, chemical shifts in CDCl3 are
given relative to CClF3 (δ = 0.0 ppm). UV/Vis spec-
tra were measured in quartz glass cuvettes under am-
bient conditions, unless otherwise stated. The measure-
ments were performed with a PE 950 spectrometer (Perkin
Elmer GmbH, Rodgau, Germany). Fluorescence emission
and excitation spectra were recorded on a PTI QM4-
2003 fluorescence spectrometer and corrected against pho-
tomultiplier and lamp intensity. The fluorescence quantum
yields were determined by the optical dilution method [27]
(A < 0.05) using N,Nꢀ-di(2,6-diisopropylphenyl)-perylene-
3,4 : 9,10-tetracarboxylic acid bisimide (Φfl = 1.00 in chlo-
roform) [28] as reference. Cyclic voltammetry (CV) was
performed with a standard commercial electrochemical an-
alyzer in a three-electrode single-compartment cell under ar-
gon atmosphere. Dichloromethane (HPLC grade) was used
as solvent and was dried over calcium hydride and degassed
prior to measurement. The supporting electrolyte tetrabutyl-
ammonium hexafluorophosphate was recrystallized from
ethanol/water and dried in high vacuum. The measurements
were carried out at a concentration of 10−4 M with ferrocene
as internal standard for the calibration of potential. Working
electrode: Pt disc; reference electrode: Ag/AgCl; auxiliary
electrode: Pt wire.
matic perylene cores are well separated in the crystal.
This packing should enable a two-dimensional charge
carrier transport along the PBI stacks, hence this PBI
might be suitable for application in OFETs.
Conclusion
A series of di- and tetrafluorinated perylene bis-
imide dyes were synthesized by employing the Halex
reaction. Owing to the high sensibility of the fluori-
nated bisanhydrides towards nucleophilic amines lead-
ing to undesired side reactions, only low yields were
obtained for the imidization of fluorinated perylene
bisanhydrides. Therefore, for the synthesis of core-
fluorinated perylene bisimides the sequence of first
imidization and subsequent Halex reaction is the bet-
ter choice.
The physical attributes of the difluorinated deriva-
tives are, apart from the hypsochromic shift of the op-
tical absorption and emission, quite similar to those
of the corresponding unsubstituted dyes. Like core-
unsubstituted PBIs, the difluorinated derivatives can
build up strong π-π interactions in the solid state due
to their negligible torsion angle in the bay area [13].
Nevertheless, the quadrupole moments of the dyes are
changed by the two bay substituents, which induces
a modified packing of these dyes in the solid state.
The structural attributes of tetrafluorinated derivatives
are very similar to those of other tetrasubstituted PBI
dyes (e. g., tetrachloro). For one example (5a), the
packing in the solid state revealed close π-π dis-
tances between the naphthalene units of conformation-
ally twisted chromophores, and an alternate arrange-
ment of P- and M-enantiomers as in the case of a core-
tetrachlorinated PBI [24c].
Crystal structure determination of 5a
Since π-π interactions are indispensable for high
charge carrier mobilities, the present core-fluorinated
PBI derivatives are promising n-type semiconductors
for organic electronic applications.
Single crystals of 5a were obtained by recrystallization
from dichloromethane and methanol. The X-ray diffrac-
tion data for 5a were collected on a Bruker X8 APEX
diffractometer with a CCD area detector, using graphite-
monochromatized MoKα radiation. The structure was solved
with Direct Methods, and expanded by means of Fourier
techniques with the SHELX software package [29]. All
non-hydrogen atoms were refined anisotropically. Hydrogen
atoms were placed in idealized positions and included in
structure factor calculations.
Experimental Section
General information
Dibrominated PBIs 2a, c, d, f and tetrachlorinated
PBIs 3a, c, d were synthesized according to the liter-
ature [17]. For the former compounds, mixtures of the
Crystal and structure determination data: C40H38F4N2O4,
¯
1,7- and 1,6-regioisomers in a ratio of about 9 : 1 were orange needles, triclinic, space group P1, a = 7.8097(4),
◦
˚
used. Potassium fluoride, zinc acetate, propionic acid, cyclo- b = 12.1717(7), c = 18.25◦17(11) A, α = 75.605(1) , β =
◦
3
˚
hexylamine, 1-n-octylamine, 2-ethylhexylamine, 1-n-butyl- 80.791(1) , γ = 80.2050(1) , V = 1643.3(2) A , Z = 2, T =
amine, 1-phenylethylamine, sulfolane, 18-crown-6, and sil- 193(2) K, ρcalc = 1.388 g cm−3, µ = 0.105 mm−1, F(000) =
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742
R. Schmidt et al. · Synthetic Routes to Core-fluorinated Perylene Bisimide Dyes and their Properties
720 e, R1 = 0.1024, wR2 = 0.1829, 5792 independent reflec- N,Nꢀ-Bis(α-methylbenzyl)-1,6,7,12-tetrachloro-3,4:9,10-
tions [2θ ≤ 50.0◦] and 467 parameters.
tetracarboxylic acid bisimide (rac) (3b)
The CIF file of 5a is available as supporting information
A
mixture of 3.00 (5.66 mmol) 1,6,7,12-tetra-
g
in ref. [13].
chloro-3,4:9,10-tetracarboxylic acid bisanhydride, 7.5 mL
(65.2 mmol) α-methylbenzylamine (rac) and 1.00
g
Zn(OAc)2 were stirred in 65 mL quinoline at 180 ◦C for 4 h.
After cooling to r. t. the mixture was poured into 300 mL
2 N HCl, and the precipitate was filtered off and dried in
vacuum. After column chromatography (CH2Cl2) 3.70 g
(5.03 mmol, 88 %) of a dark red solid was obtained. –
1H NMR (400 MHz, CDCl3): δ = 8.64 (s, 4 H), 7.51 (m,
4 H), 7.34 (m, 4 H), 7.2 – 7.3 (m, 2 H), 6.54 (q, 2 H,
3J(H,H) = 7.2 Hz), 2.01 (d, 6 H, 3J(H,H) = 7.2 Hz). –
HRMS (apci (pos. mode, chloroform)): m/z = 735.0414
(calcd. 735.0406 for C40H23Cl4N2O4, [M]−).
Synthesis
1,7-Difluoro-3,4:9,10-tetracarboxylic acid bisanhydride (1)
A mixture of 11.4 g (43.2 mmol) of 18-crown-6 and 6.30 g
(108.8 mmol) of potassium fluoride in 75 mL anhydrous sul-
folane was heated to 160 C, and at this temperature a sus-
◦
pension of 3.0 g (5.4 mmol) of 1,7-dibromoperylene bisan-
hydride that contained about 15 % of the 1,6-regioisomer in
75 mL anhydrous sulfolane was added within 30 min. The re-
action◦mixture was stirred at 160 ◦C for 1 h and then cooled
to 80 C. Subsequently, 250 mL of water was added drop-
wise, and stirring was continued for additional 1 h at 80 ◦C.
After cooling down to room temperature (r. t.), the precipi-
tate was separated by vacuum filtration, was◦hed several times
with water, and dried under vacuum at 80 C to give 2.47 g
(quantitative) of a red solid.
1H NMR spectroscopic analysis in D2SO4 revealed that
this product consists of a mixture of 1,7- and 1,6-regio-
isomers (about 85 : 15). Because of signal overlapping, the
ratio of the isomers could not be determined accurately. The
crude product could not be purified since it is insoluble in or-
ganic solvents, and was used as such for further reactions. –
1H NMR (500 MHz, D2SO4, TMS): δ = 9.0 (m, 2 H), 8.5
(m, 2 H), 8.3 (m, 2 H). (Values for the center of multiplets are
given). – 13C NMR (125 MHz, D2SO4, TMS): δ = 165.5 (s,
CO), 164.4 (s, CO), 162.2 (d, CF, 1J(C,F) = 266 Hz), 136.6
(d), 132.5 (d), 129.9 (s), 129.4 (s), 127.2 (d), 125.6 (s), 120.0
(s), 119,9 (s), 118.2(s). – MALDI-MS (neg. mode, DHB):
m/z = 427.7 (calcd. 428.01 for C24H6F2O6, [M]−).
General procedure A (imidization)
A mixture of difluorinated perylene bisanhydride 1 [16],
the respective amine and zinc acetate in quinoline was stirred
at 180 ◦C under argon for 2 h. After cooling to r. t., the reac-
tion mixture was poured into 2 N HCl and extracted with
CH2Cl2. The organic layer was washed with 2 N HCl, and
the solvent was removed in vacuum. The crude products were
first purified by silica gel column chromatography and sub-
sequently precipitated from CH2Cl2/methanol to give red-
orange solids.
General procedure B (Halex process)
A mixture of dibrominated perylene bisimide 2 or tetra-
chlorinated perylene bisimide 3, KF and 18-crown-6 (for
2) or (N,Nꢀ-dimethylimidazolidino)-tetramethylguanidinium
chloride (CNC+) (for 3) in sulfolane was stirred at 160 –
180 ◦C for 6.5 – 27 h under argon. The reaction was ter-
minated by cooling and addition of 10 mL of water. The
precipitate was separated by filtration, washed several times
with water, and dissolved in CH2Cl2. The solution was dried
over MgSO4, and the product was purified by silica gel col-
umn chromatography. After removing the solvent under re-
duced pressure, the obtained solid material was re-dissolved
in dichloromethane, precipitated by addition of methanol and
dried in vacuum (60 ◦C, 10−3 mbar, 1 day).
N,Nꢀ-Bis(α-methylbenzyl)-1,7-dibromo-3,4:9,10-tetra-
carboxylic acid bisimide (rac) (2b)
A mixture of 2.00 g (3.63 mmol) 1,7-dibromo-3,4 : 9,10-
tetracarboxylic acid bisanhydride, 0.5 mL α-methylbenzyl-
amine (rac) and 10 mg Zn(OAc)2 was stirred in 12 mL
◦
quinoline for 3 h at 130 C. After cooling to r. t. the mix-
ture was poured into 200 mL 2 N HCl, and the precipitate
was filtered off and dried in vacuum. After column chro-
matography (CH2Cl2) 1.31 g (1.74 mmol, 48 %) of a dark
red solid was obtained. – 1H NMR (400 MHz, CDCl3): δ =
9.46 (d, 2 H, 3J(H,H) = 8.2 Hz), 8.90 (s, 2 H), 8.67 (d, 2 H,
N,Nꢀ-Di(n-octyl)-1,7-difluoroperylene-3,4:9,10-tetra-
carboxylic acid bisimide (4a)
According to general procedure A, the reaction of
3J(H,H) = 8.1 Hz), 7.51 (m, 4 H), 7.34 (m, 4 H), 7.2 – 7.3 44.0 mg (103 µmol) 1,7-difluoroperylene-3,4:9,10-tetracarb-
(m, 2 H), 6.54 (q, 2 H, 3J(H,H) = 7.2 Hz), 2.02 (d, 6 H, oxylic acid bisanhydride (1), 78.1 mg (604 µmol) 1-n-octyl-
3J(H,H) = 7.2 Hz). – HRMS (apci (pos. mode, chloroform)): amine and 20.0 mg Zn(OAc)2 in 5 mL quinoline afforded
m/z = 755.0178 (calcd. 755.0176 for C40H24Br2N2O4, after column chromatography (CHCl3 : n-hexane = 4 : 1, and
[M+H]+).
7 : 3) 9 mg (14 µmol, 13 %) of 2a as an orange solid.
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R. Schmidt et al. · Synthetic Routes to Core-fluorinated Perylene Bisimide Dyes and their Properties
743
Details according to general procedure B were reported (pos. mode, chloroform)): m/z = 650.2945 (calcd. 650.2951
previously [13]. – M. p. 335 – 338 ◦C. – 1H NMR (400 MHz, for C40H40F2N2O4, [M]−). – UV/Vis (CH2Cl2): λmax (εmax
,
CDCl3): δ = 9.13 (m, 2 H), 8.74 (m, 2 H), 8.51 (m, 2 H),
M
−1cm−1) = 508 nm (76600), 474 (45200), 444 (16000). –
4.21 (m, 4 H), 1.77 (m, 4 H), 1.49 – 1.21 (m, 20 H), 0.88 (t, Fluorescence (CH2Cl2): λmax = 516 nm, fluorescence quan-
3
6 H, J(H,H) = 6.8 Hz). – 19F NMR (376.5 MHz, CDCl3): tum yield Φfl = 1.00. – CV (CH2Cl2, 0.1 M TBAHFP, vs.
δ = −102.99 (m). – HRMS (apci (pos. mode, chloro- Fc/ Fc+): E1/2 (PBI/PBI−) = −1.07 V, E1/2 (PBI−/PBI2−) =
form)): m/z = 650.2947 (calcd. 650.2962 for C40H40F2N2O4, −1.28 V.
[M]−). – UV/Vis (CH2Cl2): λmax (εmax
, M
−1cm−1) =
N,Nꢀ-Di(cyclohexyl)-1,7-difluoroperylene-3,4:9,10-tetra-
carboxylic acid bisimide (4d)
508 nm (81300), 474 (48400), 444 (17300). – Fluorescence
(CH2Cl2): λmax = 514 nm, fluorescence quantum yield Φfl =
1.00. – CV (CH2Cl2, 0.1 M TBAHFP, vs. Fc/ Fc+): E1/2
(PBI/PBI−) = −1.04 V, E1/2 (PBI−/PBI2−) = −1.26 V.
According to general procedure A, the reaction of 40.0 mg
(93.4 µmol) 1,7-difluoroperylene-3,4:9,10-tetracarboxylic
acid bisanhydride (1), 86.7 mg (874 µmol) cyclohexylamine
and 20.0 mg Zn(OAc)2 in 5 mL quinoline yielded after col-
umn chromatography (CH2Cl2 : n-pentane = 4 : 1 and 3 : 2)
5.0 mg (8.47 µmol, 10 %) of 4d as an orange solid.
N,Nꢀ-Bis(α-methylbenzyl)-1,7-difluoro-3,4:9,10-tetra-
carboxylic acid bisimide (rac) (4b)
a) According to general procedure A, the reaction of
100 mg (0.233 mmol) 1,7-difluoroperylene-3,4 : 9,10-tetra-
carboxylic acid bisanhydride (1), 200 mg (1.65 mmol) 1-
phenylethylamine and 50.0 mg Zn(OAc)2 in 12 mL quinoline
afforded after column chromatography (CH2Cl2 : pentane =
4 : 1) 40.0 mg (63.0 µmol, 27 %) of 4b as an orange solid.
b) According to general procedure B, the reaction of
651 mg (1.36 mmol) N,Nꢀ-di(1-phenylethyl)-1,7-dibromo-
3,4:9,10-tetracarboxylic acid bisimide (2b), 650 mg KF and
200 mg 18-crown-6 in 13 mL sulfolane afforded after col-
umn chromatography (CH2Cl2) 330 mg (0.52 mmol, 60 %)
For details according to general procedure B, see
ref. [13]. – M. p. > 440 ◦C (decomposition). – 1H NMR
3
(400 MHz, CDCl3): δ = 9.14 (dd, 2 H, J(H,H) = 8.4 Hz,
3J(H,H) = 5.2 Hz), 8.69 (d, 2 H, 3J(H,H) = 7.7 Hz), 8.50
3
(d, 2 H, J(H,F) = 13.8 Hz), 5.04 (m, 2 H), 2.56 (m, 4 H),
1.20 – 2.00 (m, 16 H). – 19F NMR (376.5 MHz, CDCl3):
δ = −103.22 (m). – HRMS (ESI, CH2Cl2, acetonitrile
1 : 1): m/z = 590.2015 (calcd. 590.2023 for C36H28N2O4F2,
[M]−). – UV/Vis (CH2Cl2): λmax (εmax
, M
−1cm−1) =
508 nm (89000), 473 (52100), 444 (18300). – Fluorescence
(CH2Cl2): λmax = 513 nm, fluorescence quantum yield Φfl =
0.98. – CV (CH2Cl2, 0.1 M TBAHFP, vs. Fc/Fc+): E1/2
of a red solid. – Melting range: 311 – 322 C. – 1H NMR
◦
(400 MHz, CDCl3): δ = 9.04 (m, 2 H), 8.63 (d, 2 H,
3
3J(H,H) = 7.8 Hz), 8.46 (d, 2 H, J(H,H) = 13.7 Hz), 7.51
(PBI/PBI−) = −1.08 V, E1/2 (PBI−/PBI2−) = −1.29 V.
(m, 4 H), 7.34 (m, 4 H), 7.2 – 7.3 (m, 2 H), 6.54 (q, 2 H,
3J(H,H) = 7.2 Hz), 2.04 (d, 6 H, 3J(H,H) = 7.2 Hz). –
19F NMR (376.5 MHz, CDCl3): δ = −103.07. – HRMS (apci
N,Nꢀ-Di(3,4,5-tridodecylphenyl)-1,7-difluoroperylene-
(pos. mode, chloroform)): m/z = 635.1776 (calcd. 635.1777 3,4:9,10-tetracarboxylic acid bisimide (4e)
for C40H25F2N2O4, [M+H]+). – UV/Vis (CH2Cl2): λmax
(εmax, M−1cm−1) = 510 nm (80900), 475 (47400), 445
(16600). – Fluorescence (CH2Cl2): λmax = 518 nm, fluo-
rescence quantum yield Φfl = 0.98. – CV (CH2Cl2, 0.1 M
TBAHFP, vs. Fc/ Fc+): E1/2 (PBI/PBI−) = −1.04 V, E1/2
According to general procedure A, the reaction of
100 mg (233 µmol) 1,7-difluoroperylene-3,4:9,10-tetracarb-
oxylic acid bisanhydride (1), 550 mg (920 µmol) 3,4,5-tri-
dodecylaniline and 51.0 mg Zn(OAc)2 in 13 mL quinoline
yielded after column chromatography (CH2Cl2 : n-pentane =
1 : 1, 1 : 3 and 2 : 3) 45.0 mg (28.0 µmol, 12 %) of 4e
as an orange sticky solid. According to optical polarizing
microscopy and powder X-ray analysis a soft crystalline
(PBI−/PBI2−) = −1.25 V.
N,Nꢀ-Di(2-ethylhexyl)-1,7-difluoro-3,4:9,10-tetracarboxylic
acid bisimide (rac) (4c)
phase is present at r. t. – M. p. 321 ◦C (∆Hm = 22.4 kJ
According to general procedure B, the reaction of mol−1 according to DSC). – H NMR (400 MHz, CDCl3):
590 mg (1.36 mmol) N,Nꢀ-di(2-ethylhexyl)-1,7-dibromo- δ = 9.22 (m, 2 H), 8.78 (d, 2 H, 3J(H,H) = 7.8 Hz),
3,4:9,10-tetracarboxylic acid bisimide (2c), 590 mg KF and 8.58 (d, 2 H, 3J(H,F) = 13.5 Hz), 6.97 (s, 4 H), 2.66 (t,
295 mg 18-crown-6 in 20 mL sulfolane afforded after column 12 H), 1.19 – 1.64 (m, 120 H), 0.88 (m, 18 H). – 19F NMR
chromatography (CH2Cl2) 270 mg (0.43 mmol, 46 %) of 4c (376.5 MHz, CDCl3): δ = −102.83 (m). – HRMS (apci
1
◦
1
as a red solid. – M. p. 311 – 315 C. – H NMR (400 MHz, (neg. mode, chloroform)): 1587.2344 (calcd. 1587.2352 for
CDCl3): δ = 9.12 (m, 2 H), 8.68 (d, 2 H, 3J(H,H) = 8.0 Hz), C108H160F2N2O4, [M]−). – UV/Vis (CH2Cl2): λmax (εmax
,
8.49 (d, 2 H, 3J(H,H) = 13.6 Hz), 4.15 (m, 4 H), 1.97 (m, −1cm−1) = 511 nm (96900), 476 (57300), 446 (20500). –
M
2 H), 1.2 – 1.5 (m, 16 H), 0.96 (m, 6 H), 0.90 (m, 6 H). – Fluorescence (CH2Cl2): λmax = 518 nm, fluorescence quan-
19F NMR (376.5 MHz, CDCl3): δ = −102.90. – HRMS (apci tum yield Φfl = 0.35. – CV (CH2Cl2, 0.1 M TBAHFP, vs.
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744
R. Schmidt et al. · Synthetic Routes to Core-fluorinated Perylene Bisimide Dyes and their Properties
Fc/Fc+): E1/2 (PBI/PBI−) = −1.02 V, E1/2 (PBI−/PBI2−) = (calcd. 686.2768 for C40H38F4N2O4, [M]−). – UV/Vis
−1.26 V.
(CH2Cl2): λmax (εmax, M−1cm−1) = 500 nm (66000), 466
(41300), 438 (15000). – Fluorescence (CH2Cl2): λmax
=
N,Nꢀ-Di(n-butyl)-1,7-difluoroperylene-3,4:9,10-tetra-
carboxylic acid bisimide (4f)
509 nm, fluorescence quantum yield Φfl = 0.88. – CV
(CH2Cl2, 0.1 M TBAHFP, vs. Fc/Fc+): E1/2 (PBI/PBI−) =
−0.98 V, E1/2 (PBI−/PBI2−) = −1.22 V.
According to general procedure B, the reaction of
100 mg (151 µmol) N,Nꢀ-di(n-butyl)-1,7-dibromo-3,4:9,10-
tetracarboxylic acid bisimide (2f), 100 mg KF and 35 mg
18-crown-6 in 5 mL sulfolane afforded after column chro-
matography (CH2Cl2) 20 mg (37.2 µmol, 25 %) of 4f as
N,Nꢀ-Bis(α-methylbenzyl)-1,6,7,12-tetrafluoroperylene-
3,4:9,10-tetracarboxylic acid bisimide (5b)
According to general procedure B, the reaction of
1.00 g (1.36 mmol) N,Nꢀ-bis(α-methylbenzyl)-1,6,7,12-
tetrachloroperylene-3,4:9,10-tetracarboxylic acid bisimide
(3b), 1.25 g KF and 100 mg CNC+ in 8 mL sulfolane
at 160 ◦C for 5 h afforded after column chromatography
(CH2Cl2 : n-pentane = 2 : 1) 80.0 mg (43.0 µmol, 9 %) of
5b as an orange solid. Since 550 mg of starting mate-
rial was re-isolated, the yield referring to the converted
amounts of starting material 3b is about 20 %. – M. p. 275 –
a red solid. – M. p. 375 – 377 C. – 1H NMR (400 MHz,
◦
CDCl3): δ = 9.19 (m, 2 H), 8.73 (d, 2 H, 3J(H,H) = 7.8 Hz),
8.54 (d, 2 H, 3J(H,F) = 13.5 Hz), 4.22 (m, 4 H), 1.70 –
1.80 (m, 4 H), 1.4 – 1.6 (m, 4 H), 0.90 – 1.20 (t, 6 H). –
19F NMR (376.5 MHz, CDCl3): δ = −103.12 (m). – HRMS
(apci (pos. mode, acetonitrile, chloroform)): m/z = 538.1709
(calcd. 538.1710 for C32H24F2N2O4, [M+H]+). – UV/Vis
(CH2Cl2): λmax (εmax, M−1cm−1) = 508 nm (83300), 473
(49500), 444 (17400). – Fluorescence (CH2Cl2): λmax = 515
nm, fluorescence quantum yield Φfl = 1.00. – CV (CH2Cl2,
0.1 M TBAHFP, vs. Fc/Fc+): E1/2 (PBI/PBI−) = −1.04 V,
◦
279 C. – 1H NMR (400 MHz, CDCl3): δ = 8.44 (t, 4 H,
3J(H,F) = 5.3 Hz), 7.34 (m, 4 H), 7.51 (m, 4 H), 7.26
(m, 2 H), 6.54 (q, 2 H, 3J(H,H) = 7.3 Hz), 2.01 (d, 6
H, 3J(H,H) = 7.0 Hz). – 19F NMR (376.5 MHz, CDCl3):
δ = −94.29 (t, 3J(H,F) = 5.3 Hz). – HRMS (apci (neg.
mode, chloroform)): m/z = 670.1532 (calcd. 670.1521 for
E1/2 (PBI−/PBI2−) = −1.25 V.
C40H22F4N2O4, [M]−). – UV/Vis (CH2Cl2): λmax (εmax
,
1,7-Difluoro-3,4:9,10-tetracarboxylic acid bisimide (4h)
M
−1cm−1) = 503 nm (68400), 468 (43000), 440 (16300). –
612 mg (0.96 mmol) N,Nꢀ-di(1-phenylethyl)-1,7-difluoro-
3,4:9,10- tetracarboxylic acid bisimide (4◦b) was dissolved
in 450 mL dry CH2Cl2 and cooled to 0 C. Then 2.5 mL
boron tribromide was added, and the solution was stirred
for 3 h at r. t. Afterwards CH2Cl2 was removed in vacuum,
and the residue was poured into in a mixture of water and
methanol. After treatment in an ultrasonic bath for 30 min
the precipitate was filtered off and washed with water and
CH2Cl2 to give 390 mg (0.92 mmol, 96 %) of a dark pow-
der. – M. p. > 450 ◦C (subl.). – 1H NMR (400 MHz, CDCl3):
insoluble compound. – MS (EI (pos. mode)): m/z = 426.0445
(calcd. 426.0447 for C24H6F4N2O4, [M]+).
Fluorescence (CH2Cl2): λmax = 514 nm, fluorescence quan-
tum yield Φfl = 0.85. – CV (CH2Cl2, 0.1 M TBAHFP, vs.
Fc/Fc+): E1/2 (PBI/PBI−) = −0.98 V, E1/2 (PBI−/PBI2−) =
−1.21 V.
N,Nꢀ-Di(2-ethylhexyl)-1,6,7,12-tetrafluoroperylene-
3,4:9,10-tetracarboxylic acid bisimide (5c)
According to general procedure B, the reaction of 300 mg
(400 µmol) N,Nꢀ-di(2-ethylhexyl)-1,6,7,12-tetrachloroperyl-
ene-3,4:9,10-tetracarboxylic acid bisimide (3c), 250 mg KF
and 100 mg CNC+ in 2.4 mL sulfolane at 160 ◦C for
2 h afforded after column chromatography (CH2Cl2 and
CH2Cl2 : n-hexane = 7 : 3) 30.0 mg (43.0 µmol, 9 %) of 5c
as an orange solid. Since 150 mg of starting material 3c
was re-isolated, the yield referring to the converted amounts
N,Nꢀ-Di(n-octyl)-1,6,7,12-tetrafluoroperylene-3,4:9,10-
tetracarboxylic acid bisimide (5a)
According to general procedure B, the reaction of 200 mg of starting material 3c is about 18 %. – M. p. 222 ◦C. –
(270 µmol) N,Nꢀ-di(n-octyl)-1,6,7,12-tetrachloroperylene- 1H NMR (400 MHz, CDCl3): δ = 8.49 (t, 4 H, 3J(H,F) =
3,4:9,10-tetracarboxylic acid bisimide (3a), 154 mg KF and 5.2), 4.16 (m, 4 H), 1.95 (m, 2 H), 1.43 – 1.25 (m, 16 H),
17 mg CNC+ in 6.5 mL sulfolane at 170 ◦C for 28 h afforded 0.97 – 0.88 (m, 12 H). – 19F NMR (376.5 MHz, CDCl3):
after column chromatography (CH2Cl2 : n-pentane = 3 : 2 δ = −94.27 (t, 3J(H,F) = 5.3 Hz). – HRMS ((apci (neg.
and chloroform : n-pentane = 7 : 3) 5.2 mg (8◦.00 µmol, 3 %) mode, chloroform)): m/z = 686.2783 (calcd. 686.2773 for
of 5a as an orange solid. – M. p. 237 – 242 C. – 1H NMR C40H38F4N2O4, [M]−). – UV/Vis (CH2Cl2): λmax (εmax
,
(400 MHz, CDCl3): δ = 8.49 (t, 4 H, 3J(H,F) = 5.2 Hz),
M
−1cm−1) = 501 nm (71900), 466 (44900), 437 (16400). –
3
4.21 (t, 4 H, J(H,H) = 7.2 Hz), 1.76 (m, 4 H), 1.47 – 1.24 Fluorescence (CH2Cl2): λmax = 513 nm, fluorescence quan-
(m, 20 H), 0.88 (t, 6 H, 3J(H,H) = 6.9 Hz). – 19F NMR tum yield Φfl = 1.00. – CV (CH2Cl2, 0.1 M TBAHFP, vs.
(376.5 MHz, CDCl3): δ = −94.27 (t, 3J = 5.31 Hz). – HRMS Fc/Fc+): E1/2 (PBI/PBI−) = −0.98 V, E1/2 (PBI−/PBI2−) =
(ESI (neg. mode, CH2Cl2, acetonitrile)): m/z = 686.2762 −1.21 V.
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R. Schmidt et al. · Synthetic Routes to Core-fluorinated Perylene Bisimide Dyes and their Properties
745
1,6,7,12-Tetrafluoro-3,4:9,10-tetracarboxylic acid bisimide 1,6,7,12-Tetrafluoro-3,4:9,10-tetracarboxylic acid bisanhy-
(5h) dride (7)
A mixture of 55.0 mg (80.0 µmol) N,Nꢀ-di(2-ethylhexyl)-
A portion of 70.0 mg (104 µmol) of N,Nꢀ-di(1-phenyl-
1,6,7,12-tetrafluoro-3,4:9,10- tetracarboxylic acid bisimide
(5c), 300 mg◦KOH, 200 µL water and 10 mL butanol was
stirred at 75 C for 2 h. Then the mixture was poured into
200 mL acetic acid and stirred for 5 h at 100 ◦C. The mixture
was diluted with water and the product precipitated over
night. The precipitate was filtered off and dried in vacuum
to obtain 34.0 mg (75.0 µmol, 94 %) of a dark powder. –
M. p. > 450 ◦C (decomp.). – MS (EI (pos. mode)): m/z =
464.1 (calcd. 464.0 for C24H4F4O6, [M]+).
ethyl)-1,6,7,12-tetrafluoro-3,4:9,10-tetracarboxylic acid bis-
imide (5b) was dissolved in 15 mL dry CH2Cl2 under argon
and cooled to 0 ◦C. Then 200 µL boron tribromide was added
and the solution was stirred for 3 h at r. t. CH2Cl2 was re-
moved in vacuum, and the residue was poured into a mixture
of water and methanol. After treatment in an ultrasonic bath
for 30 min the precipitate was filtered off and washed with
water and CH2Cl2 to obtain 45.0 mg (97.0 µmol, 93 %) of a
red powder. – M. p. > 495 ◦C (decomp.). – This compound is
not soluble in common solvents, thus no 1H NMR spectrum
could be measured. – HRMS (EI (pos. mode, chloroform)):
m/z = 462.0255 (calcd. 462.0260 for C24H6F4N2O4, [M]+).
[1] For representative reviews on OFETs, see: a) H. E.
Katz, Z. Bao, S. L. Gilat, Acc. Chem. Res. 2001, 34,
359 – 369; b) C. R. Newman, C. D. Frisbie, D. A. da
Silva Filho, J.-L. Bre´das, P. C. Ewbank, K. R. Mann,
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