Room-temperature columnar liquid-crystalline perylene imido-diesters by a homogeneous one-pot imidification-esterification of perylene-3,4,9,10- tetracarboxylic dianhydride

Article abstract of DOI:10.1002/ejoc.201001346

The reaction of PTCDA (perylene-3,4,9,10-tetracarboxylic dianhydride) with an alcohol, a bromoalkane, and an alkylamine in the presence of DBU in DMF yields imido-diester-substituted perylenes. The reaction is limited to polar alcohols such as propanol, but longer alkyl chains are efficiently introduced in a second step by alkyl group exchange by using selective acidic ester hydrolysis that leaves the imide group intact. This amine-efficient approach to imido-diesters is used to obtain acceptor-type self-assembling dyes that form a hexagonal columnar liquid crystalline phase at room temperature. Perylenetetracarboxylic monoimide-diesters were synthesized by an amine-efficient, one-pot procedure. Alkyl group exchange of the ester moieties leads, through the use of the monoimido-monoanhydride, to room-temperature hexagonal columnar liquid crystals with potential as self-assembling electron acceptors for organic electronics.

Full text of DOI:10.1002/ejoc.201001346

FULL PAPER
DOI: 10.1002/ejoc.201001346
Room-Temperature Columnar Liquid-Crystalline Perylene Imido-Diesters by a
Homogeneous One-Pot Imidification–Esterification of Perylene-3,4,9,10-
tetracarboxylic Dianhydride
Julien Kelber,[a] Harald Bock,*[a] Olivier Thiebaut,[a] Eric Grelet,[a] and Heinz Langhals[b]
Dedicated to the memory of Dr. Marc Julia
Keywords: Liquid crystals / Heterocycles / Fluorescence spectroscopy / Self-assembly
The reaction of PTCDA (perylene-3,4,9,10-tetracarboxylic di-
anhydride) with an alcohol, a bromoalkane, and an alk-
ylamine in the presence of DBU in DMF yields imido-diester-
substituted perylenes. The reaction is limited to polar
alcohols such as propanol, but longer alkyl chains are ef-
ficiently introduced in a second step by alkyl group exchange
by using selective acidic ester hydrolysis that leaves the
imide group intact. This amine-efficient approach to imido-
diesters is used to obtain acceptor-type self-assembling dyes
that form a hexagonal columnar liquid crystalline phase at
room temperature.
Introduction
Derivatives of perylene-3,4,9,10-tetracarboxylic dianhy-
dride (PTCDA, 1) constitute an extraordinarily successful
class of functional dyes and pigments whose applications
range from car paints to photoreceptors in photocopiers.[1]
They have been incorporated in organic solar cells starting
with Tang’s seminal bilayer cell in 1986,[2] and liquid crys-
talline derivatives have been discussed as self-assembling
electron acceptor layers with superior charge transport
properties.[3]
Scheme 1. PTCDA and its symmetrically and dissymmetrically sub-
stituted ester and carboxylic imide derivatives.
Tetraalkyl esters 2 show large hexagonal columnar liquid
crystalline temperature ranges, and this mesophase can be
stabilized at room temperature by the incorporation of race-
mically branched alkyl chains.[4] The face-on (homeotropic)
alignment needed in photovoltaic devices, where the colum-
nar charge transport pathways are aligned perpendicular to
the substrate, has been conveniently obtained by thermal
annealing (Scheme 1) with room-temperature columnar es-
ter and imido-ester materials.[5]
Tetraesters 2 contain moderate electron density in the
aromatic core as expressed by their lowest unoccupied and
highest occupied molecular orbital energy (ELUMO and
EHOMO) values of –3.5 and –5.8 eV, respectively.[6] This
quality makes these materials potential electron-acceptor
and electron-donor layers depending on what type of mate-
rial they are paired with at a donor–acceptor interface;
more pronounced acceptor-type behavior is observed with
their dialkyl diimide analogues 3, with a ELUMO value of
about –4.2 eV.[7] Contrary to tetraesters 2, diimides 3 do not
possess a sufficient number of alkyl substituents to induce
a stable hexagonal columnar mesophase at room tempera-
ture.[8] However, imido-diesters 4[9] possess an enhanced ac-
ceptor-type behavior compared to esters 2 and display a
sufficient number of alkyl substituents to suggest the pos-
sibility of a stable room-temperature mesophase, together
with accessible clearing temperatures (i.e., moderate transi-
tion temperatures to the isotropic liquid state) to allow con-
trolled growth and alignment of columnar liquid crystalline
samples.
Yang et al.[10] recently synthesized perylene imido-di-
esters 4 with three identical nonbranched n-alkyl substitu-
ents and found pronounced chromophore aggregation in
amorphous sublimed films. No evidence of a columnar me-
sophase or a transition to the liquid state at accessible tem-
[a] CRPP: Centre de Recherche Paul Pascal, CNRS 115,
Avenue Schweitzer, 33600 Pessac – Bordeaux, France
Fax: +33-5-56845600
E-mail: bock@crpp-bordeaux.cnrs.fr
[b] Department of Chemistry, LMU University of Munich,
Butenandtstr. 13, 81377 Munich, Germany
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J. Kelber, H. Bock, O. Thiebaut, E. Grelet, H. Langhals
FULL PAPER
peratures could be found. They did, however, find ELUMO
values of about –4.0 eV, confirming a good acceptor-type
electronic structure. Their synthetic approach involved the
low-yield formation and isolation of unsubstituted per-
ylenetetracarboxylic monoimido-monoanydride 5 (R = H),
followed by phase-transfer trialkylation of its dipotassium
salt with an excess amount of the alkyl bromide. Although
useful, this approach is limited to providing perylenes with
identical substituents on both the carboxylic imide and es-
ter groups and, more importantly, to easily accessible pri-
mary alkyl bromides.
A common approach to alkyl-substituted 5 starts with
diimidification of PTCDA with an alkylamine, followed by
its delicate monohydrolysis.[9,11] Such alkylimidoanhydrides
can then be esterified, or, as is frequently the case, imidated
with another amine to which shall be grafted a strongly
fluorescent or electronically interacting perylenetetracarb-
oxdiimide (PTCDI) moiety.[12,13]
Results and Discussion
It occurred to us during our syntheses of perylene tetra-
carboxylic tetraesters from PTCDA with an alkanol and a
bromoalkane that, in the presence of a strong lipophilic
base such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and
with DMF as polar aprotic solvent, the pigment quickly
dissolved even if the bromoalkane was initially omitted. In
this ester synthesis, base-catalyzed ring opening of each an-
hydride moiety by the alcohol first produces a carboxylic
ester-acid, which can then react with the bromoalkane to
form the diester (Scheme 2). If the bromoalkane is omitted,
the pigment dissolves with formation of perylenetetracarb-
oxylic diester 7, and a homogeneous solution is obtained.
Perylenetetracarboxylic dialkylimides 3 are known to be
highly soluble and low melting only if the alkyl substituent
is secondary, that is, derived from an α-branched alk-
ylamine such as 7-aminotridecane.[14] Such amines can be
obtained in two efficient steps from the corresponding
ketone through the oxime.[13,14]
Scheme 2. Esterification of PTCDA with alkanol and alkyl halide
in homogeneous solution (3 h at 60 °C or 24 h at 25 °C, yield
Ͼ80% for R = ethyl, propyl, or butyl).
Both aforementioned synthetic procedures necessitate
the selective formation and isolation of monoimido-
monoanhydride 5 and are not economical with respect to
the alkyl substituent on the imide function. Given that long
α-branched alkylamines are not commercially available and
that even the ketone starting materials can be expensive, we
envisioned a synthetic procedure for the direct monoalkyl-
imidation of PTCDA that is more efficient with respect to
the amine, does not involve kinetically controlled half reac-
tions or separations based on differential solubilities,[11] is
not limited to primary alkyl substituents,[10] and, ideally,
only creates soluble side products of strongly different po-
larity that are easily separated by column chromatography.
The main difficulty in the monoimidation of PTCDA
with an alkylamine is that the former is an insoluble pig-
ment, which dissolves in an organic solvent only upon reac-
tion with the amine. Monoimidated molecules therefore dis-
solve readily and react a second time more quickly than the
initial pigment. This undesired disubstitution explains why
the most common procedure for monoimidation entails ini-
tial carboxylic diimide formation followed by monohydro-
lysis.
We envisioned that the vicinal ester-acid groups could be
labile to attack by various amines leading to expulsion of
alcohol. Indeed it was found that if the addition order is
alcohol, alkylamine, and then bromoalkane, with sufficient
time between additions and using excess amounts of all
components relative to the amine, a yield of carboxylic
imido-diester of more than 50% with respect to the amine
could be obtained at room temperature in a single step from
PTCDA (1) (Scheme 3). After initial formation of diester-
diacid 7, addition of alkylamine led to the formation of
imido-ester-acid 8, which was finally treated with the bro-
moalkane to give imido-diester 4.
A similar approach that relies on controlled monohydro-
lysis of a symmetrically substituted PTCDA derivative to
create a monoanhydride while maintaining soluble alkyl
chains on the other side of the perylene moiety was recently
described by Xue and co-workers.[15] This approach uses
tetraester 2 as starting material, thus avoiding the excessive
use of the branched amine; anhydride-diester 6 results fol-
lowing acid-catalyzed monohydrolysis. The anhydride-dies-
ter can be converted subsequently with an equimolar
amount of the amine into imido-diester 4 in three steps
Scheme 3. One-pot formation of imido-diester in homogeneous
solution by sequential addition of alcohol, alkylamine, and alkyl
halide (Rf = 0.45 in DCM on silica). Side products are the much
less polar diimide [3 with R = CH(C6H13)2, Rf = 0.8] and the much
more polar tetraester (2 with R = C3H7, Rf = 0.23). Yields are
calculated with respect to the amine, using 1 in twofold excess.
As the reaction depends on the good initial dissolution
from PTCDA (1, which may be hydrolyzed to yield imido- of the pigment by incorporation of alcohol, the scope is
anhydride 5 through a fourth step). limited to polar alcohols such as methanol, ethanol, or pro-
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Room-Temperature Columnar Liquid-Crystalline Perylene Imido-Diesters
panol that quickly and efficiently achieve this dissolution.
Longer chain alcohols such as 2-ethylhexan-1-ol (yielding
flexible alkyl chain substituents that are efficient in stabiliz-
ing the liquid crystalline state) are inefficient at inducing
solubilization. The main side product of the reaction is
tetraester 2, along with small quantities of carboxylic di-
imide 3. Because an alkylimide group is intrinsically more
lipophilic than two vicinal alkyl ester groups, the carboxylic
diimide is more lipophilic than the tetraester, and the
imido-diester has intermediate lipophilicity, as long as all
alkyl groups are of similar size. Separation of the three
products by column chromatography is possible as long as
the combined size of the ester alkyl groups is similar to
the size of the carboxylic imide alkyl group, and separation
becomes trivial if the carboxylic imide alkyl group is much
bigger than the combined ester alkyl groups: Trace amounts
of carboxylic diimide are eluted with a lipophilic solvent
that does not elute the targeted imido-diester. The latter
can be eluted with a solvent of medium polarity leaving the
tetraester on the column.
In order to freely choose the alkyl substituents on the
ester groups, we then looked for a selective way to hydrolyze
the initial short-chain esters without affecting the imide
group. We found that this can be cleanly achieved by heat-
ing at reflux with sulfuric acid in acetic acid for a couple of
hours – no trace of dianhydride was observed and the ester
groups were quantitatively reverted to the corresponding
anhydride.
Figure 1. Absorption (left) and fluorescence (right) spectra of 4b
in chloroform.
the very slight contribution to the HOMO and LUMO.
Light absorption in the visible region is estimated to be at-
tributable to a pure π–π* transition according to the calcu-
lated orbitals in Figure 2. The central nodal planes in the
HOMO and LUMO correspond to the analogous nodal
planes in 3[17] and are of special interest for labeling with 4
because the chromophore remains essentially unaffected by
substituents at the nitrogen atom.
Reaction of 7-aminotridecane, a long α-branched amine,
a twofold excess of PTCDA (1) to minimize the formation
of diimide, and an excess amount of propanol and 1-bro-
mopropane as short alkyl reagents for esterification pro-
ceeded to give 58% yield of imido-diester 4a in addition to
15% of the carboxylic diimide (73% combined yield with
respect to the amine). Analytically pure imido-anhydride 5a
(R = 1-hexylheptyl) was obtained by acidic hydrolysis of
4a. Esterification of 5a with 2-ethylhexanol, 2-butyloctanol,
or 2-hexyldecanol together with the corresponding 2-alkyl-
1-bromoalkanes yielded the series of imido-diesters 4b–d as
brilliant red waxes. The UV/Vis absorption and fluores-
cence spectra of 4a–d corresponded well to previously de-
scribed spectra of the methyl ester,[9] and consequently were
Figure 2. Quantum chemical calculated orbitals (DFT B3LYP) of
the trimethyl derivative of 4. From left to right: LUMO, HOMO,
HOMO – 1 (second-highest occupied molecular orbital).
Mesogens 4b–d form large hexagonal columnar meso-
found to be independent of the esterifying alkyl groups. The phase ranges. Although 2-ethylhexyl derivative 4b was, like
spectra for 4a–d were found to be about 10 nm more hyp- propyl derivative 4a, crystalline at room temperature with
sochromic than those of diimides 3 (Figure 1). The fluores- a single mesophase at higher temperature, higher homo-
cence spectra were found to mirror the absorption spectra. logues 4c and 4d were found to be liquid crystalline at room
The materials are highly fluorescent, with fluorescence temperature (Scheme 4).
quantum yields of 93, 98, 90, and 93% for 4a–d, respec-
Differential scanning calorimetry was performed on all
tively, in chloroform.
four homologues 4a–d (Figure 3). Derivative 4a showed a
The electronic system of 4 was further analyzed by quan- crystal to mesophase transition (melting point charac-
tum chemical DFT calculations of the N and O methyl ana- terized by its large transition enthalpy and its appearance
logues (Figure 2). The chromophore of 4 is found to be only on first heating) at 118 °C and a mesophase to iso-
planar with the ester groups twisted out of the plane by tropic liquid transition (clearing point) at 199 °C. Com-
about 30° (steric interactions are somewhat underesti- pound 4b was found to melt at 69 °C and cleared at 252 °C.
mated[16] by the DFT method; the AM1 method gave a Both 4a and 4b showed no other (LC to LC) phase transi-
twist of some 60°, and the real value may lie between these tions between melting and clearing. Compound 4c showed
values). As a consequence, the ester groups are weakly cou- no large enthalpy melting, but a nonhysteretic small en-
pled electronically to the chromophore, as can be seen by thalpy transition at 8 °C that may be a mesophase to meso-
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Scheme 4. Hexagonal columnar liquid crystalline imido-diesters
with racemic alkyl ester substituents obtained by selective hydroly-
sis to the imido-anhydride.
Figure 4. Left: homeotropic mesophase domain growing from the
isotropic liquid between glass plates at cooling through the liquid
to mesophase transition of 4c (polarizing optical microscopy with
slightly uncrossed polarizers, 0.5 mmϫ0.6 mm). Right: powder X-
ray diffraction spectrum of 4d at room temperature (logarithmic
intensity scaling). The indicated Miller indices correspond to a col-
umn lattice of hexagonal symmetry.
phase transition, which was not characterized further given
the low temperature; a clearing point of 192 °C was found
for 4c. Derivative 4d showed no other transition above our
lower limit of –30 °C other than clearing at 131 °C. The
textures of all four homologues between glass plates by pol-
arizing optical microscopy upon cooling through the clear-
ing point consisted of homeotropic domains of hexagonal
symmetry (Figure 4, left). Powder X-ray diffraction on 4d
at room temperature confirmed the hexagonal nature of the
columnar mesophase with the presence of the characteristic
(100), (110), and (210) reflections (Figure 4, right). The li-
quid crystalline feature was evidenced by the presence of a
broad peak at about 1.8 Å–1, characteristic of liquid-like or-
der between the disk-shaped molecules within the columns.
Conclusions
In summary, imido-diesters 4 with long branched alkyl
chains are hexagonal columnar liquid crystals at room tem-
perature. Combined with their known acceptor-type char-
acter and good absorption, this property makes them po-
tentially interesting materials for use in organic electronic
devices based on the unidirectional columnar self-assembly
of energy pathways. The fluorescence quantum efficiency of
4 in dilute solution is close to unity. Imido-anhydrides 5,
from which the mesogens are obtained by esterification and
which constitute versatile and important chromophore
building blocks, are accessible by a novel and convenient
two-step procedure involving the one-pot imidification–
esterification of alkylamines with an excess amount of
PTCDA, alcohol, and bromoalkane.
Experimental Section
General: IR spectra were recorded with a Perkin–Elmer 1420 Ratio
Recording Infrared Spectrometer, FT 1000. UV/Vis spectra were
recorded with a Varian Cary 5000 and a Bruins Omega 20. Fluores-
cence spectra were recorded with a Varian Eclipse. NMR spectra
were recorded with a Bruker Advance 400 and a JEOL ECS 400
(400 MHz). Mass spectra were obtained with a Finnigan MAT 95.
Fluorescence quantum yields were determined according to ref.[18]
N-(1-Hexylheptyl)-9,10-bis(propyloxycarbonyl)perylene-3,4-di-
carboximide (4a): A mixture of PTCDA (9.8 g, 25 mmol), DBU
(15.2 g, 100 mmol), 1-propanol (13.6 g, 200 mmol), and DMF
(100mL) was stirred at room temperature with the exclusion of
moisture for 16 h (homogeneous solution was formed within the
first hour). The mixture was treated with 7-aminotridecane (2.49 g,
12.5 mmol) and further stirred for 3 d. The mixture was then
treated with 1-bromopropane (23 g, 200 mmol, beginning precipi-
tation), stirred for another 16 h, and then treated with dichloro-
methane (DCM, 500 mL) and 5% aqueous HCl (500 mL). The or-
ganic phase was separated, and the aqueous phase was extracted
with DCM (3ϫ100 mL). The combined organic phases were evap-
orated, and the crude residue was subjected to column chromatog-
raphy [silica gel; DCM/n-pentane, 2:1; for elution of the tetracarb-
Figure 3. Differential calorimetry scans (heating in black, cooling
in gray) of 4a–d (5 K/min for 4a and 4b, 3 K/min for 4c and 4d).
The temperatures given are onset temperatures. Transition enthal-
pies are given in brackets.
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Room-Temperature Columnar Liquid-Crystalline Perylene Imido-Diesters
oxylic bis(imide), 690 mg (from 1-butanol and completed with
methanol), 15%; Rf (silica gel, DCM) = 0.8; then DCM for elution
of 4a; the tetraester remained on the column; Rf (silica gel, DCM)
= 0.23]. Yield: 4.93 g (58% from ethanol and competed with meth-
anol); bright red, shiny wax. Rf (silica gel, DCM) = 0.45. IR (ATR):
NMR (400 MHz, CDCl3): δ = 8.60 (br., 2 H, ArH), 8.45 (d, J =
8 Hz, 2 H, ArH), 8.43 (d, J = 8 Hz, 2 H, ArH), 8.07 (d, J = 8 Hz,
2 H, ArH), 5.18 (tt, J = 9, 6 Hz, 1 H, NCH), 4.25 (d, J = 6 Hz, 4
H, OCH2), 2.25 (m, 2 H, CH2), 1.91–1.78 (m, 4 H, CH & CH2),
1.49–1.17 (m, 64 H, CH2), 0.87 (t, J = 7 Hz, 6 H, CH3), 0.86 (t, J
= 7 Hz, 6 H, CH3), 0.82 (t, J = 7 Hz, 6 H, CH3) ppm. 13C NMR
ν = 3386 (w), 2954 (s), 2922 (s), 2854 (s), 2348 (w), 1921 (w), 1720
˜
(m)1693 (s), 1655 (s), 1614 (s), 1591 (s), 1579 (m), 1511 (w), 1456 (100 MHz, CDCl3): δ = 168.3, 164.8 & 163.7 (br.[17]), 135.1, 132.0,
(m), 1415 (m), 1397 (w), 1350 (m), 1310 (m), 1292 (m), 1257 (m),
131.9, 131.7 & 131.0 (br.), 130.0, 129.3, 129.2, 129.0, 125.8, 122.7 &
122.0 (br.), 122.4, 121.6, 68.5, 54.5, 37.4, 32.4, 32.0, 31.9, 31.8, 31.4
1200 (m), 1173 (m), 1156 (m), 1129 (w), 1097 (w), 1071 (m), 1038
1
(w), 930 (w), 845 (w), 826 (w), 805 (m) 745 (w), 699 (w) cm–1. H (2ϫ), 30.1, 29.71, 29.66, 29.4, 29.3, 27.0, 26.8, 26.7, 22.7 (2ϫ), 22.6,
NMR (400 MHz, CDCl3): δ = 8.57 (br., 2 H, ArH next to imide),
14.1 (2ϫ), 14.0 ppm. UV/Vis (CHCl3): λmax (Erel) = 474.8 (0.76),
8.41 (d, J = 8 Hz, 2 H, ArH), 8.38 (d, J = 8 Hz, 2 H, ArH), 8.07 506.6 nm (1.00). Fluorescence (CHCl3): λmax (Irel) = 523.6 (1.00),
(d, J = 8 Hz, 2 H, ArH), 5.18 (tt, J = 9, 8 Hz, 1 H, NCH), 4.31 (t,
J = 7 Hz, 4 H, OCH2), 2.25 (m, 2 H, one H of CH2 next to NCH),
1.85 (m, 2 H, other H of CH2 next to NCH), 1.83 (sext., J = 7 Hz,
4 H, propyl-CH2), 1.39–1.17 (m, 16 H, CH2), 1.05 (t, J = 7 Hz, 6
H, propyl-CH3), 0.82 (t, J = 7 Hz, 6 H, CH3) ppm. 13C NMR
(100 MHz, CDCl3): δ = 168.2, 164.7 & 163.7 (two broad peaks of
the imide carbonyls[17]); 134.8, 131.8, 131.7, 131.6 & 130.8 (br.[17]);
130.1, 129.1, 129.0, 128.8, 125.6, 122.7 & 121.9 (br.[17]); 122.1,
121.6, 67.2, 54.6, 32.4, 31.8, 29.2, 27.0, 22.6, 22.0, 14.0, 10.5 ppm.
UV/Vis (CHCl3): λmax (Erel) = 474.2 (0.75), 505.8 nm (1.00). Fluo-
rescence (CHCl3): λmax (Irel) = 523.0 (1.00), 562.3 nm (0.68). Fluo-
562.4 nm (0.68). Fluorescence quantum yield (CHCl3, λex =
475 nm, E475 nm/1 cm = 0.0136, ref.[16] 1 with Φ = 1.00): 0.93 ppm.
MS (70 eV): m/z (%) = 392.05 (29.65), 574.25 (22.21), 1039.76
(100.00), 1040.77 (74.17), 1041.77 (27.19). C69H101NO6 (1040.9):
calcd. C 79.64, H 9.78, N 1.35; found C 79.80, H 10.00, N 1.17.
9,10-Bis(2-butyloctyloxycarbonyl)-N-(1-hexylheptyl)perylene-3,4-di-
carboximide (4c): Imido-anhydride 5a (1.0 g, 1.74 mmol), DBU
(2 g, 13 mmol), 1-bromo-2-butyloctane (4.0 g, 16 mmol), 2-butyl-
octan-1-ol (4 g, 21 mmol), and ethyl acetate (100 mL) were allowed
to react in a fashion analogous to that of 4d. Yield: 1.24 g (77%);
red wax. IR (ATR): ν = 2953 (s), 2922 (s), 2855 (s), 1710 (s), 1694
˜
rescence quantum yield (CHCl3, λex = 474 nm, E474 nm/1 cm
=
(s), 1656 (s), 1593 (s), 1524 (w), 1511 (m), 1466 (m), 1456 (m), 1416
(m), 1397 (w), 1378 (w), 1350 (s), 1308 (w), 1292 (s), 1260 (s), 1200
(s), 1168 (s), 1104 (m), 1070 (m), 1036 (w), 948 (w), 844 (m), 825
0.0143, ref.[16] 1 with Φ = 1.00): 0.93 ppm. MS (70 eV): m/z (%) =
364.06 (21.06), 392.06 (53.73), 493.16 (100.00), 494.16 (51.44),
675.36 (99.65), 676.36 (49.43). C43H49NO6 (675.9): calcd. C 76.42,
H 7.31, N 2.07; found C 76.39, H 7.46, N 2.01.
1
(w), 805 (m), 773 (w), 746 (m), 725 (w), 700 (w), 641 (w) cm–1. H
NMR (400 MHz, CDCl3): δ = 8.61 (br., 2 H, ArH), 8.49 (d, J =
8 Hz, 2 H, ArH), 8.46 (d, J = 8 Hz, 2 H, ArH), 8.08 (d, J = 8 Hz,
2 H, ArH), 5.19 (tt, J = 9, 6 Hz, 1 H, NCH), 4.26 (d, J = 6 Hz, 4
H, OCH2), 2.25 (m, 2 H, CH2), 1.91–1.77 (m, 4 H, CH & CH2),
1.51–1.16 (m, 48 H, CH2), 0.92 (t, J = 7 Hz, 6 H, CH3), 0.88 (t, J
= 7 Hz, 6 H, CH3), 0.82 (t, J = 7 Hz, 6 H, CH3) ppm. 13C NMR
(100 MHz, CDCl3): δ = 168.3, 164.9 & 163.8 (br.[17]), 135.4, 132.2,
132.0, 131.9 & 131.1 (br.), 130.1, 129.5, 129.4, 129.3, 126.0, 122.8 &
N-(1-Hexylheptyl)perylene-3,4-dicarboximide-9,10-dicarbox-
ylic Anhydride (5a):[19] Imido-diester 4a (3.5 g, 51.8 mmol) was sus-
pended in a mixture of concentrated sulfuric acid (3.5 g) and glacial
acetic acid (100 g). The mixture was heated at reflux for 2 h, al-
lowed to cool to room temperature, and poured into water
(100 mL). The solid was collected by vacuum filtration, washed
with distilled water, and dried in vacuo. Yield: 2.95 g (99 %,
51.4 mmol). 1H NMR (400 MHz, CDCl3): δ = 8.69 (br., 2 H, ArH 122.1 (br.), 122.5, 121.8, 68.5, 54.6, 37.4, 32.4, 31.9, 31.8, 31.4, 31.0,
next to imide), 8.65 (d, J = 8 Hz, 2 H, ArH), 8.63 (d, J = 8 Hz, 2
H, ArH), 8.61 (d, J = 8 Hz, 2 H, ArH), 5.17 (tt, J = 9, 8 Hz, 1 H,
29.7, 29.2, 29.0, 26.9, 26.7, 23.0, 22.7, 22.6, 14.1 (2ϫ), 14.0 ppm.
UV/Vis (CHCl3): λmax (Erel) = 474.8 (0.76), 506.6 nm (1.00). Fluo-
NCH), 2.23 (m, 2 H, CH2), 1.92–1.82 (m, 2 H, CH2), 1.38–1.17 rescence (CHCl3): λmax (Irel) = 523.4 (1.00), 562.2 nm (0.69). Fluo-
(m, 16 H, CH2), 0.82 (t, J = 7 Hz, 6 H, CH3) ppm. 13C NMR rescence quantum yield (λex = 475 nm, E475 nm/1 cm = 0.0150,
(100 MHz, CDCl3): δ = 164.4 & 163.3 (br.[17]) 159.9, 136.4, 133.6
(2 C), 132.0 & 131.2 (br.), 131.8, 129.5, 126.7, 126.5, 124.7 & 123.9
(br.), 124.1, 123.1, 119.0, 54.9, 32.4, 31.8, 29.2, 26.9, 22.6,
14.0 ppm. C37H35NO5 (573.7): calcd. C 77.46, H 6.15, N 2.44;
found C 77.23, H 6.15, N 2.43.
CHCl3, ref.[16] 1 with Φ = 1.00): 0.90 ppm. MS (70 eV): m/z (%) =
392.05 (28.06), 927.64 (100.00), 928.64 (62.77). C61H85NO6 (928.4):
calcd. C 78.92, H 9.23, N 1.51; found C 79.18, H 9.32, N 1.44.
9,10-Bis(2-ethylhexyloxycarbonyl)-N-(1-hexylheptyl)perylene-3,4-di-
carboximide (4b): Imido-anhydride 5a (500 mg, 0.87 mmol), DBU
9,10-Bis(2-hexyldecyloxycarbonyl)-N-(1-hexylheptyl)perylene-3,4-di- (1.0 g, 7 mmol), 1-bromo-2-ethylhexane (2.0 g, 10 mmol), 2-eth-
carboximide (4d): A solution of imido-anhydride 5a (2.5 g,
43.6 mmol), DBU (5 g), 1-bromo-2-hexyldecane (10 g), and 2-hex-
yldecan-1-ol (10 g) in ethyl acetate (200 mL) was stirred at 60 °C
for 16 h under exclusion of moisture and treated with DCM
(500 mL) and 5% aqueous HCl (500 mL). The organic layer was
collected, and the aqueous layer was extracted with DCM
(3ϫ100 mL). The combined organic phases were evaporated, dis-
solved in a small amount of DCM, precipitated with methanol,
collected by vacuum filtration, purified by column separation (sil-
ica gel, DCM), dissolved in DCM and recrystallized from 2-propa-
nol; the product precipitates not in the crystalline state, but in the
columnar liquid crystalline state. Yield: 3.45 g (76%); brilliant red
ylhexan-1-ol (2.0 g, 15 mmol), and ethyl acetate (50 mL) were al-
lowed to react in a fashion analogous to that of 4d. Yield: 570 mg
(80%); red wax. IR (ATR): ν = 2955 (s), 2922 (s), 2855 (s), 1709
˜
(s), 1692 (s), 1654 (s), 1614 (w), 1594 (s), 1524 (w), 1512 (m), 1458
(m), 1416 (m), 1400 (w), 1378 (w), 1351 (s), 1292 (s), 1259 (s), 1199
(s), 1169 (s), 1104 (s), 1070 (m), 1036 (m), 948 (w), 856 (w), 843
(m), 825 (w), 805 (m), 773 (w), 746 (m), 726 (w), 700 (w), 682 (w),
1
671 (w), 639 (w) cm–1. H NMR (400 MHz, CDCl3): δ = 8.63 (br.,
2 H, ArH), 8.52 (d, J = 8 Hz, 2 H, ArH), 8.49 (d, J = 8 Hz, 2 H,
ArH), 8.10 (d, J = 8 Hz, 2 H, ArH), 5.19 (tt, J = 9, 6 Hz, 1 H,
NCH), 4.29 (dd, J = 10, 6 Hz, 2 H, OCH2), 4.25 (dd, J = 10, 6 Hz,
2 H, OCH2), 2.24 (m, 2 H, 1 H of CH2 next to NCH), 1.90–1.75
wax. IR (ATR): ν = 2953 (s), 2921 (s), 2853 (s), 1709 (s), 1694 (s), (m, 4 H, CH & 1 H of CH2 next to NCH), 1.53–1.17 (m, 32 H,
˜
1656 (s), 1594 (s), 1524 (w), 1511 (m), 1465 (m), 1457 (m), 1415
CH2), 0.97 (t, J = 7 Hz, 6 H, CH3), 0.91 (t, J = 7 Hz, 6 H, CH3),
(m), 1397 (w), 1377 (w), 1351 (s), 1308 (w), 1292 (s), 1262 (s), 1200 0.82 (t, J = 7 Hz, 6 H, CH3) ppm. 13C NMR (100 MHz, CDCl3):
(m), 1168 (s), 1104 (m), 1070 (m), 1035 (w), 1001 (w), 947 (w), 844 δ = 168.4, 164.9 & 163.8 (br.[17]), 135.4, 132.2, 132.0, 131.9 & 131.1
1
(m), 825 (w), 805 (m), 745 (m), 723 (w), 700 (w), 641 (s) cm–1. H (br.), 130.1, 129.5, 129.3, 129.3, 126.1, 122.8 & 122.1 (br.), 122.6,
Eur. J. Org. Chem. 2011, 707–712
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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711

J. Kelber, H. Bock, O. Thiebaut, E. Grelet, H. Langhals
FULL PAPER
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Received: September 27, 2010
Published Online: December 9, 2010
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Eur. J. Org. Chem. 2011, 707–712