Synthesis and optical properties of fluorescent core-trisubstituted naphthalene diimide dyes

Article abstract of DOI:10.1055/s-2007-983718

Efficient synthetic routes to hitherto unknown core-trisubstituted naphthalene diimides (NDIs) starting with 2,6-dichloro-substituted NDIs 1 are described. The reaction of NDIs 1 with ethylene diamine as solvent, affords the ethylene-diamine-bridged core-

Full text of DOI:10.1055/s-2007-983718

1872
PAPER
Synthesis and Optical Properties of Fluorescent Core-Trisubstituted
Naphthalene Diimide Dyes
Core-Trisubstitut
o
ed Naphthale
r
ne
D
iim
n
ide Dyes elia Röger, Shahadat Ahmed, Frank Würthner*
Universität Würzburg, Institut für Organische Chemie, Am Hubland, 97074 Würzburg, Germany
Fax +49(931)8884756; E-mail: wuerthner@chemie.uni-wuerzburg.de
Received 23 February 2007
This paper is dedicated to Professor Peter Schreier on the occasion of his 65th birthday.
tional dyes. In this work, we present the synthesis of NDIs
bearing three substituents in the aromatic core and de-
scribe their optical properties.
Abstract: Efficient synthetic routes to hitherto unknown core-
trisubstituted naphthalene diimides (NDIs) starting with 2,6-dichlo-
ro-substituted NDIs 1 are described. The reaction of NDIs 1 with
ethylene diamine as solvent, affords the ethylene-diamine-bridged
core-trisubstituted NDIs 2 in very good yield. The substitution of
the chlorine atom of 2 with alkylamino or alkoxy nucleophiles leads
to triamino- or alkoxy-diamino-substituted NDIs. UV/Vis spectros-
copy revealed that the electronic properties of NDI chromophores
bearing three core substituents are strongly influenced by the nature
of the substituents. NDIs which are tri(alkylamino)-substituted at
the naphthalene core exhibit high (up to 70%) fluorescence quan-
tum yields.
The synthetic routes to core-trisubstituted NDIs are de-
picted in Scheme 1. The starting compounds, 2,6-dichlo-
ro-substituted NDIs 1a and 1b were prepared by
imidization of 2,6-dichloro-1,4,5,8-naphthalenetetracar-
boxylic acid dianhydride with n-octylamine or 2,6-diiso-
propylaniline in refluxing glacial acetic acid as described
in the literature.3a,c Reaction of dichlorinated NDIs 1a and
1b in pure ethylene diamine (without any solvent) at room
temperature led not only to the nucleophilic substitution
of one chlorine atom to form the ethylene-diamine-substi-
tuted NDI but also to an in situ ring closure of this inter-
mediate, resulting in the core-trisubstituted compounds 2a
and 2b in 70% and 72% yield, respectively (Scheme 1,
route i). Apparently, this intramolecular ring-closure reac-
tion takes place analogously to a classical Tschitschibabin
reaction. However, if the reaction is carried out in dichlo-
romethane as solvent in the presence of 22 equivalents of
ethylene diamine at room temperature, only the substitu-
tion of one chlorine atom in 1a or 1b takes place, leading
to the respective monoamino-substituted NDIs 3a or 3b.3a
It is worth mentioning that, in contrast to compound 3b,
which is stable for months under ambient conditions, NDI
3a undergoes intramolecular cyclization into NDI 2a,
even in the solid state, within a few hours and can there-
fore not be stored for long periods of time.
Key words: dyes, fluorophores, rylenes, nucleophilic aromatic
substitution, intramolecular ring closure
Naphthalene diimides (NDIs) represent the smallest p-
conjugated systems among the class of rylene diimide
dyes, standing out against their higher homologues by ex-
hibiting better solubility and a lower propensity for the
formation of p-aggregates.1 Although core-unsubstituted
NDIs are colorless and nonfluorescent,2 functionalization
of NDIs with electron-donating substituents in the 2,6-po-
sitions of the naphthalene unit results in highly brilliant
and fluorescent chromophores whose absorption and
emission properties can be tuned over a wide wavelength
range by altering the electron-donating ability of the core
substituents.3 Due to their interesting electronic proper-
ties, such 2,6-disubstituted NDIs have, in recent years, at-
tracted much attention as photoconducting materials,4
light-harvesting chromophores in supramolecular anten-
nae,5 visible light-absorbing units in self-assembled sys-
tems for photoproduction of a transmembrane proton
gradient,6 and they serve as potential candidates for opti-
cally triggered transport investigations in metal-molecule
hybrid setups.7
The reaction of NDIs 2a and 2b with n-butylamine under
reflux facilitates the nucleophilic substitution of the re-
maining chlorine atom, resulting in the corresponding tri-
amino core-substituted NDIs 4a and 4b in 34% and 60%
yield, respectively. The latter derivatives can also be ob-
tained from compounds 3a and 3b, under the same reac-
tion conditions as before, through nucleophilic
substitution of the chlorine atom by n-butylamine and in
situ ring closure. Reaction of compounds 2a and 2b with
ethylene diamine as a solvent under reflux leads to substi-
tution of the chlorine atom in the naphthalene core to af-
ford triamino-substituted NDIs 5a and 5b, but in this case
no further ring closure was observed. NDIs 5a and 5b are
both sensitive to decomposition under ambient condi-
tions. They were also obtained from 3a and 3b, respec-
tively, under the same reaction conditions as applied for
2a and 2b. Furthermore, the chlorine atom in compounds
2a and 2b could also be replaced by alkoxy nucleophiles
Although a broad variety of 2,6-disubstituted NDIs3–7
along with a few examples of 2-,8 2,7- and 2,3-substituted
NDIs9 are known, NDI derivatives containing three or
four substituents at the naphthalene core have not yet been
accomplished. Since the core substituents have strong ef-
fects on the electronic properties of NDI chromophores,
tri- or tetrasubstituted NDIs should be of interest as func-
SYNTHESIS 2007, No. 12, pp 1872–1876
x
x.
x
x
.
2
0
0
7
Advanced online publication: 08.06.2007
DOI: 10.1055/s-2007-983718; Art ID: T03907SS
© Georg Thieme Verlag Stuttgart · New York

PAPER
Core-Trisubstituted Naphthalene Diimide Dyes
1873
R
N
R
N
R
O
O
O
O
O
O
O
O
O
N
O
H
N
H
N
Cl
i
vii
2a: 70%
2b: 72%
6a: 49%
6b: 62%
Cl
Cl
N
H
H13C6O
N
H
N
R
N
R
O
N
R
O
6a,b
2a,b
1a,b
vi
a: R = n-C8H17
b: R = 2,6-i-Pr2C6H3
4a: 34%
4b: 60%
3a: 51%
3b: 48%
iii
ii
5a: 75%
5b: 54%
R
N
R
N
R
N
O
O
O
O
O
O
O
O
O
O
O
H
N
H
N
H
N
iv
NH2
H2N
4a: 34%
4b: 59%
Cl
BuHN
N
H
N
H
N
H
N
R
O
N
R
N
R
3a,b
4a,b
5a,b
v
5a: 78%
5b: 70%
Scheme 1 Synthesis of core-substituted NDIs 2–6. Reagents and conditions: (i) ethylene diamine, Ar, r.t., 12 h; (ii) ethylene diamine, CH2Cl2,
Ar, r.t., 5 h; (iii) n-butylamine, Ar, 80 °C, 5 h; (iv) n-butylamine, Ar, 80 °C, 5 h; (v) ethylene diamine, Ar, 120 °C, 5 h; (vi) ethylene diamine,
Ar, 120 °C, 5 h; (vii) n-hexanol, K2CO3, 160 °C, 3 h. Compound 3b was prepared according to literature.3a
since the reaction of 2a and 2b with hexanol in the pres- cent, NDIs 2a,b are weakly fluorescent, with quantum
ence of potassium carbonate at 160 °C yielded the alkoxy- yields of about 10%. The fluorescence bands of NDIs
dialkylamino-substituted NDIs 6a and 6b (Scheme 1, 2a,b are not in mirror-image relationships to the S0–S1 ab-
route vii). The chemical structures of core-trisubstituted sorption bands of these chromophores as shown for 2b in
NDIs 2 and 4–6 could be confirmed by 1H NMR spectros- Figure 1. This indicates that the absorption band of NDIs
copy as a singlet (d = 7.7–8.5 ppm) was observed, indicat- 2a,b in the visible region comprises not only the S0–S1 ab-
ing the presence of one proton in the naphthalene core. sorption, but presumably overlaps with the next higher
Sharp signals arising from the amino protons of the ethyl- transition. The replacement of the chlorine atom of com-
ene diamino substituents were detected (d = 10–11 ppm), pounds 2a,b by an alkoxy group, evokes a further red shift
revealing strong intramolecular hydrogen bonding be- (14 nm) of the absorption maxima of the respective trisub-
tween the amino protons and the respective adjacent car- stituted NDIs 6a,b (Figure 2) and an increase of the fluo-
bonyl groups.
rescence quantum yield (16–18%) is observed.
Introduction of a third electron-donating amino substitu-
ent at the naphthalene core induces a large red shift of the
visible absorption bands of the triamino-substituted NDIs
4a,b to 576–579 nm. However, the absorption band of the
next higher electronic transition of 4a,b is not shifted
compared to those for NDIs 2a,b and 6a,b. Although the
latter compounds show a pronounced vibronic fine struc-
ture, the spectra of triamino-substituted dyes 4a,b are
broadened. Interestingly, NDIs 4a,b exhibit strong fluo-
rescence with quantum yields in the range of 60–70% in
dichloromethane (Table 1).
The optical properties of the newly synthesized NDIs
were explored by UV/Vis and fluorescence spectroscopy
and the significant results are summarized in Table 1. The
absorption spectra of the nearly colorless non-
fluorescent3a,c dichloro-substituted NDIs 1 exhibit an ab-
sorption band at 300–400 nm for the S0–S1 transition. The
vibronic fine structure of the absorption band arises from
the skeletal vibrations of the aromatic system (Figure 1,
spectrum of NDI 1b is shown exemplarily). Upon intro-
duction of the ethylene diamino substituent to the naph-
thalene core, significant changes in optical properties
were observed for the monochlorodiamino-substituted In summary, synthetic routes to core-trisubstituted NDIs
NDIs 2a,b. These compounds are orange in the solid state, containing an ethylene diamine bridge and an additional,
whilst in solution they show a new absorption band in the variable substituent have been established. While the
visible region which is located at around 497 nm. While number and the nature of the core substituents strongly in-
the dichloro-substituted derivatives 1a,b are nonfluores- fluence the optical properties of NDIs, substituents in the
Synthesis 2007, No. 12, 1872–1876 © Thieme Stuttgart · New York

1874
C. Röger et al.
PAPER
amino substituents at the naphthalene core are highly
fluorescent and may serve as building blocks for supramo-
lecular assemblies or fluorescent labels for bio-imaging.
Solvents and reagents were obtained from commercial suppliers
and purified and dried according to standard procedures.10 Column
chromatography was performed on silica gel (Merck Silica 60, par-
ticle size 0.040–0.063 mm). Semipreparative HPLC was carried out
with a conventional pump and a multi-wavelength UV/Vis detector
(JASCO) on a reversed phase column (Macherey–Nagel, C18). Sol-
vents with purity grade ‘pa’ were used for HPLC. The solvents for
spectroscopic studies were of spectroscopic grade and used as re-
1
ceived. H NMR spectra were recorded on a Bruker Avance 400
spectrometer with TMS or residual undeuterated solvent as internal
standard. High-resolution ESI-TOF mass spectrometry was carried
out on a microTOF focus instrument (Bruker Daltronik GmbH).
UV/Vis spectra were measured in a conventional quartz cell (light
path 10 mm) on a Perkin–Elmer Lambda 40P spectrometer or on a
Lambda 950 spectrometer. Fluorescence emission spectra were re-
corded in a conventional rectangular quartz cell (10 × 10 × 40 mm)
on a PTI QM4-2003 fluorescence spectrometer and are corrected
against photomultiplier and lamp intensity. A long wavelength
range emission-corrected photomultiplier R928 was used. Fluores-
cence quantum yields were determined under dilute conditions (A
<0.05) in CH2Cl2 versus N,N¢-(2,6-diisopropylphenyl)-1,6,7,12-
Figure 1 UV/Vis absorption and fluorescence spectra of 2b (dashed
lines) and, for comparison, absorption spectrum of 1b3a (solid line) in
CH2Cl2.
tetraphenoxyperylene-3,4:9,10-tetracarboxylic
acid
bisimide
(Ffl = 0.96 in CHCl3)11 or fluorescein (Ffl = 0.93, 0.1 M NaOH)12 as
reference.
We would like to note that compounds 2 and 4–6, that we named
above as trisubstituted naphthalene diimides for simplicity, are ac-
tually derivatives of 1,4-diaza-1,2,3,4-tetrahydroanthracene.
N,N¢-Di-n-octyl-6-chloro-5,8,9,10-(1,4-diaza-1,2,3,4-tetrahy-
droanthracene)tetracarboxylic Acid Diimide (2a)
Compound 1a (300 mg, 0.536 mmol) was placed in a flask contain-
ing ethylene diamine (18 mL) and the mixture was stirred at r.t.
overnight under an argon stream. The slurry was then poured into
HCl (1 N, 100 mL) and extracted with CH2Cl2 (2 × 100 mL). The
combined extracts were washed with H2O (100 mL), dried over an-
hyd Na2SO4, concentrated and subjected to column chromatogra-
phy (CH2Cl2, silica gel). Upon concentration under reduced
pressure at r.t., a yellow solid precipitated which was dried under
vacuum over P4O10 to yield 2a (218 mg, 70%).
Figure 2 UV/Vis absorption and fluorescence spectra of 6b (solid
lines) and 4b (dashed lines) in CH2Cl2.
Table 1 Optical Properties of NDI Chromophores in Dichloro-
methane
Colora
(solid state)
labs
(nm)
emax
lem
Fem
(%)
(M–1cm–1) (nm)
Mp 228–231 °C.
1bb
2a
pale-yellow
orange
402
496
497
510
511
533
576
579
13900
38000
39900
29600
31700
14800
26200
29400
–
<0.1
10
9
1H NMR (400 MHz, CDCl3): d = 0.88 (t, J = 6.8 Hz, 6 H), 1.27–
1.44 (m, 20 H), 1.71 (m, 4 H), 3.79 (br s, 4 H), 4.16 (m, 4 H), 8.35
(s, 1 H), 10.64 (br s, 1 H), 11.00 (br s, 1 H).
HRMS (ESI): m/z [M + H]+ calcd for C32H42ClN4O4: 581.2894;
found: 581.2891.
500
500
520
521
570
602
605
2b
6a
orange
orange-red
orange-red
red
16
18
53
60
70
UV/Vis (CH2Cl2): lmax (e) = 434 (15100), 465 (21700), 496 nm
(38000).
6b
3bb
4a
Fluorescence (CH2Cl2): lmax = 500, 534, 572 nm.
Fluorescence quantum yield (CH2Cl2): Ffl = 0.10.
violet
Anal. Calcd for C32H41ClN4O4·0.5 H2O: C, 65.13; H, 7.17; N, 9.49.
Found: C, 65.49; H, 7.10; N, 9.63.
4b
violet
a The colors are given for the solid materials because the coloristic im-
pression for solutions of some of these dyes were influenced by their
strong photoluminescence.
N,N¢-Di(2¢,6¢-diisopropylphenyl)-6-chloro-5,8,9,10-(1,4-diaza-
1,2,3,4-tetrahydroanthracene)tetracarboxylic Acid Diimide
(2b)
Prepared according to the above procedure from compound 1b (100
mg, 0.153 mmol) and ethylene diamine (5 mL) to give 2b, after pu-
rification by column chromatography (CHCl3).
b For comparison, optical data of core-disubstituted NDIs 1b and 3b
are taken from Würthner et al.3a
imide positions exert little effect on absorption and emis-
sion characteristics of these dyes. NDIs with three alkyl-
Yield: 75 mg (72%); yellow solid; mp >300 °C.
Synthesis 2007, No. 12, 1872–1876 © Thieme Stuttgart · New York

PAPER
Core-Trisubstituted Naphthalene Diimide Dyes
1875
1H NMR (400 MHz, CDCl3): d = 1.17 (m, 24 H), 2.67 (m, 4 H),
3.76 (s, 4 H), 7.34 (m, 4 H), 7.48 (m, 2 H), 8.47 (s, 1 H), 10.62 (br
s, 1 H), 10.95 (br s, 1 H).
N,N¢-Di(2¢,6¢-diisopropylphenyl)-6-n-butylamino-5,8,9,10-(1,4-
diaza-1,2,3,4-tetrahydroanthracene)tetracarboxylic Acid Di-
imide (4b)
Preparation from compound 2b:
HRMS (ESI): m/z [M + H]+ calcd for C40H42ClN4O4: 677.2894;
found: 677.2882.
Compound 2b (11 mg, 0.016 mmol) and n-butylamine (2 mL) were
stirred under argon for 5 h at 80 °C. The resultant pink reaction mix-
ture was cooled to r.t., poured into HCl (1 N, 50 mL) and extracted
with CH2Cl2 (3 × 50 mL). The combined organic phases were
washed with HCl (1 N, 2 × 50 mL) and H2O (50 mL). Upon concen-
tration under reduced pressure at r.t., a pink solid precipitated which
was further purified by column chromatography (CH2Cl2, silica gel)
to give compound 4b (7 mg, 60%).
UV/Vis (CH2Cl2): lmax (e) = 433 (17200), 465 (22200), 497 nm
(39900).
Fluorescence (CH2Cl2): lmax = 500, 534, 570 nm.
Fluorescence quantum yield (CH2Cl2): Ffl = 0.09.
Anal. Calcd for C40H41ClN4O4·H2O: C, 69.10; H, 6.23; N, 8.06.
Found: C, 69.50; H, 6.20; N, 8.11.
Preparation from compound 3b:
N,N¢-Di-n-octyl-2-(2¢-aminoethylamino)-6-chloro-1,4,5,8-naph-
thalenetetracarboxylic Acid Diimide (3a)
Compound 3b (250 mg, 0.368 mmol) was placed in a 25 mL round-
bottomed flask containing n-butylamine (10 mL) and the mixture
was stirred under argon for 5 h at 80 °C. During this time, the ini-
tially red reaction mixture turned to pink. After cooling to r.t., the
mixture was slowly poured into HCl (1 N, 150 mL) and the precip-
itated solid was separated by filtration and purified by column chro-
matography (CHCl3, silica gel) to give 4b.
A solution of compound 1a (300 mg, 0.536 mmol) and ethylene di-
amine (796 mL, 11.9 mmol) in CH2Cl2 (45 mL) was stirred at r.t. un-
der argon for 5 h. The resulting red solution was washed with sat.
aq NaHCO3 (100 mL) and the aqueous phase was extracted with
CHCl3 (3 × 100 mL). The organic phases were combined, washed
with H2O (100 mL) and the solvent was evaporated. Column chro-
matography (CHCl3, silica gel) of the crude product gave com-
pound 3a.
Yield: 155 mg (59%); pink solid; mp >300 °C.
1H NMR (400 MHz, CDCl3): d = 0.94 (t, J = 7.4 Hz, 3 H), 1.18 (m,
24 H), 1.45 (m, 2 H), 1.71 (m, 2 H), 2.71 (m, 4 H), 3.42 (m, 2 H),
3.69 (m, 4 H), 7.35 (m, 4 H), 7.49 (m, 2 H), 7.79 (s, 1 H), 9.34 (m,
1 H), 9.88 (br s, 1 H), 10.76 (br s, 1 H).
HRMS (ESI): m/z [M + Na]+ calcd for C44H51NaN5O4: 736.3838;
found: 736.3832.
Yield: 159 mg (51%); red solid.
1H NMR (400 MHz, CDCl3): d = 0.87 (t, J = 6.8 Hz, 6 H), 1.27–
1.41 (m, 20 H), 1.72 (m, 4 H), 3.18 (t, J = 6.0 Hz, 2 H), 3.66 (m,
2 H), 4.14 (m, 4 H), 8.26 (s, 1 H), 8.58 (s, 1 H), 10.27 (t, J = 5.3 Hz,
1 H). NH2 was not detected.
UV/Vis (CH2Cl2): lmax (e) = 408 (11800), 448 (10700), 541
(14900), 579 nm (29400).
HRMS (ESI): m/z [M + H]+ calcd for C32H44ClN4O4: 583.3051;
found: 583.3046.
Fluorescence (CH2Cl2): lmax = 605 nm.
N,N¢-Di-n-octyl-6-n-butylamino-5,8,9,10-(1,4-diaza-1,2,3,4-tet-
rahydroanthracene)tetracarboxylic Acid Diimide (4a)
Preparation from compound 2a:
Fluorescence quantum yield (CH2Cl2): Ffl = 0.68.
Anal. Calcd for C44H51N5O4: C, 74.03; H, 7.20; N, 9.81. Found: C,
73.70; H, 7.13; N, 9.84.
A suspension of compound 2a (100 mg, 0.172 mmol) in n-butyl-
amine (8 mL) was stirred under argon for 5 h at 80 °C. After cooling
to r.t., the red reaction mixture was slowly poured into HCl (1 N, 5
mL) and the precipitated red solid was separated by centrifugation
and washed with HCl (1 N, 10 mL). The residue was dissolved in
CH2Cl2 (50 mL), washed with sat. aq NaHCO3 (50 mL) and H2O
(50 mL). The solvent was removed under reduced pressure and the
product was purified by column chromatography (CH2Cl2, silica
gel) to give 4a (36 mg, 34%) as a pink solid.
N,N¢-Di-n-octyl-6-(2¢-aminoethylamino)-5,8,9,10-(1,4-diaza-
1,2,3,4-tetrahydroanthracene)tetracarboxylic Acid Diimide
(5a)
Preparation from compound 2a:
A suspension of compound 2a (32 mg, 0.055 mmol) in ethylene di-
amine (3 mL) was stirred under argon for 5 h at 120 °C. After cool-
ing to r.t., the reaction mixture was slowly poured into HCl (1 N, 10
mL) and the precipitated red solid was separated by centrifugation
and washed with HCl (1 N, 10 mL). The residue was dissolved in
CHCl3 (50 mL), washed with sat. aq NaHCO3 (50 mL) and H2O (50
mL). After removal of solvent, further purification by column chro-
matography (CH2Cl2, silica gel) afforded compound 5a (26 mg,
78%) as a pink solid.
Preparation from compound 3a:
Prepared according to the above procedure from compound 3a (54
mg, 0.14 mmol) and n-butylamine (5 mL) to give 4a as a pink solid
(29 mg, 34%).
Mp 181–184 °C.
Preparation from compound 3a:
1H NMR (400 MHz, CDCl3): d = 0.88 (t, J = 6.7 Hz, 6 H), 1.00 (t,
J = 7.3 Hz, 3 H), 1.25–1.41 (m, 20 H), 1.52 (m, 2 H), 1.66–1.81 (m,
6 H), 3.42 (m, 2 H), 3.71 (m, 4 H), 4.16 (m, 4 H), 7.68 (s, 1 H), 9.36
(t, J = 5.4 Hz, 1 H), 9.87 (br s, 1 H), 10.78 (br s, 1 H).
Prepared according to the above procedure from compound 3a (45
mg, 0.077 mmol) and ethylene diamine (3 mL) to give 5a as a pink
solid (35 mg, 75%).
HRMS (ESI): m/z [M + H]+ calcd for C36H52N5O4: 618.4019; found:
Mp 170–171 °C.
618.4017.
1H NMR (400 MHz, CDCl3): d = 0.88 (t, J = 6.7 Hz, 6 H), 1.26–
1.43 (m, 20 H), 1.69 (m, 4 H), 3.12 (t, J = 5.7 Hz, 2 H), 3.52 (m,
2 H), 3.69–3.75 (m, 4 H), 4.15 (m, 4 H), 7.69 (s, 1 H), 9.54 (m,
1 H), 9.90 (br s, 1 H), 10.80 (br s, 1 H).
HRMS (ESI): m/z [M + H]+ calcd for C34H49N6O4: 605.3815; found:
605.3810.
UV/Vis (CH2Cl2): lmax (e) = 380 (5000), 402 (8200), 419 (7500),
446 (9300), 576 nm (26200).
Fluorescence (CH2Cl2): lmax = 602 nm.
Fluorescence quantum yield (CH2Cl2): Ffl = 0.60.
Anal. Calcd for C36H51N5O4·1/6 CH3OH: C, 69.65; H, 8.36; N,
11.22. Found: C, 70.00; H, 8.46; N, 10.84.
Synthesis 2007, No. 12, 1872–1876 © Thieme Stuttgart · New York

1876
C. Röger et al.
PAPER
N,N¢-Di(2¢,6¢-diisopropylphenyl)-6-(2¢¢-aminoethylamino)-
5,8,9,10-(1,4-diaza-1,2,3,4-tetrahydroanthracene)tetracarboxy-
lic Acid Diimide (5b)
HRMS (ESI): m/z [M + H]+ calcd for C46H55N4O5: 743.4172; found:
743.4169.
UV/Vis (CH2Cl2): lmax (e) = 413 (11200), 436 (16800), 478
(18000), 511 nm (31700).
Preparation from compound 2b:
Compound 2b (11 mg, 0.016 mmol) and ethylene diamine (1 mL)
were stirred under argon for 5 h at 120 °C during which time the col-
or of the yellow suspension turned to pink. After cooling to r.t., the
reaction mixture was slowly poured into HCl (1 N, 20 mL) and ex-
tracted with CH2Cl2 (3 × 20 mL). The combined organic phases
were washed with sat. aq NaHCO3 (20 mL), H2O (20 mL), the sol-
vent was removed and the residue was subjected to column chroma-
Fluorescence (CH2Cl2): lmax = 521, 556 nm.
Fluorescence quantum yield (CH2Cl2): Ffl = 0.18.
Anal. Calcd for C44H51N5O4: C, 74.37; H, 7.33; N, 7.54. Found: C,
74.32; H, 7.56; N, 7.20.
tography (CH2Cl2–MeOH, 19:1) to give 5b as a pink solid (8 mg, Acknowledgment
70%).
C. R. is grateful to the Degussa Stiftung for a PhD scholarship. Fi-
nancial support of our work by the Fonds der Chemischen Industrie
is greatly appreciated.
Preparation from compound 3b:
Prepared as above from compound 3b (400 mg, 0.589 mmol) and
ethylene diamine (15 mL) to give 5b as a pink solid (225 mg, 54%).
Mp >300 °C.
References
1H NMR (400 MHz, CDCl3): d = 1.17 (m, 24 H), 2.70 (m, 4 H),
3.03 (t, J = 6.1 Hz, 2 H), 3.51 (m, 2 H), 3.69 (m, 4 H), 7.35 (m, 4 H),
7.49 (m, 2 H), 7.81 (s, 1 H), 9.48 (t, J = 5.3 Hz, 1 H), 9.90 (br s,
1 H), 10.78 (br s, 1 H).
(1) (a) Quante, H.; Müllen, K. Angew. Chem., Int. Ed. Engl.
1995, 34, 1323; Angew. Chem. 1995, 107, 1487.
(b) Würthner, F. Chem. Commun. 2004, 1564. (c) Jung, C.;
Müller, B. K.; Lamb, D. C.; Nolde, F.; Müllen, K.; Bräuchle,
C. J. Am. Chem. Soc. 2006, 128, 5283.
MS (MALDI): m/z [M]+ calcd for C42H48N6O4: 700; found: 700.
(2) (a) Alp, S.; Erten, S.; Karapire, C.; Köz, B.; Doroshenko, A.
O.; Içli, S. J. Photochem. Photobiol., A 2000, 135, 103.
(b) Licchelli, M.; Biroli, A. O.; Poggi, A. Org. Lett. 2006, 8,
915.
(3) (a) Würthner, F.; Ahmed, S.; Thalacker, C.; Debaerde-
maeker, T. Chem. Eur. J. 2002, 8, 4742. (b) Thalacker, C.;
Miura, A.; De Feyter, S.; De Schryver, F. C.; Würthner, F.
Org. Biomol. Chem. 2005, 3, 414. (c) Thalacker, C.; Röger,
C.; Würthner, F. J. Org. Chem. 2006, 71, 8098.
(4) Bender, T. P.; Graham, J. F.; Duff, J. M. US 20050004365,
2005.
N,N¢-Di-n-octyl-6-n-hexyloxy-5,8,9,10-(1,4-diaza-1,2,3,4-tetra-
hydroanthracene)tetracarboxylic Acid Diimide (6a)
A suspension of compound 2a (34 mg, 0.050 mmol) and K2CO3 (69
mg, 0.50 mmol) in n-hexanol (2 mL) was stirred under argon for 3 h
at 160 °C. After cooling to r.t., the reaction mixture was poured into
CHCl3 (100 mL) and washed successively with HCl (1 N, 2 × 100
mL) and H2O (100 mL). After removal of the solvent, further puri-
fication by column chromatography (CH2Cl2, silica gel) and subse-
quent HPLC (CH2Cl2–MeOH, 3:7) yielded the orange-red
compound 6a (23 mg, 62%).
(5) Röger, C.; Müller, M. G.; Lysetska, M.; Miloslavina, Y.;
Holzwarth, A. R.; Würthner, F. J. Am. Chem. Soc. 2006, 128,
6542.
(6) Bhosale, S.; Sisson, A. L.; Talukdar, P.; Fürstenberg, A.;
Banerji, N.; Vauthey, E.; Bollot, G.; Mareda, J.; Röger, C.;
Würthner, F.; Sakai, N.; Matile, S. Science 2006, 313, 84.
(7) Blaszczyk, A.; Fischer, M.; von Hänisch, C.; Mayor, M.
Helv. Chim. Acta 2006, 89, 1986.
Mp 140–143 °C.
1H NMR (400 MHz, CDCl3): d = 0.86–0.93 (m, 9 H), 1.27–1.44 (m,
24 H), 1.57 (m, 2 H), 1.71 (m, 4 H), 2.01 (m, 2 H), 3.75 (m, 4 H),
4.15 (m, 4 H), 4.27 (t, J = 7.0 Hz, 2 H), 7.90 (s, 1 H), 10.33 (s, 1 H),
10.95 (s, 1 H).
HRMS (ESI): m/z [M + H]+ calcd for C36H52N5O4: 618.4019; found:
618.4017.
(8) (a) Bondarenko, E. F.; Shigalevskii, V. A.; Gerasimenko, Y.
E. J. Org. Chem. USSR (Engl. Transl.) 1979, 15, 2279; Zh.
Org. Khim. 1979, 15, 2520. (b) Bondarenko, E. F.;
Shigalevskii, V. A.; Yugai, G. A. J. Org. Chem. USSR (Engl.
Transl.) 1982, 18, 530; Zh. Org. Khim. 1982, 18, 610.
(9) (a) Vollmann, H.; Becker, H.; Corell, M.; Streeck, H. Justus
Liebigs Ann. Chem. 1937, 531, 1. (b) Bonnet, E.;
Gangneux, P.; Maréchal, E. Bull. Soc. Chim. Fr. 1976, 504.
(c) Langhals, H.; Jeschke, H. Chem. Eur. J. 2006, 12, 2815.
(10) Perrin, D. D.; Armarego, W. L. F. Purification of Laboratory
Chemicals; Pergamon Press: Oxford, 1980.
(11) (a) Gvishi, R.; Reisfeld, R.; Burshtein, Z. Chem. Phys. Lett.
1993, 213, 338. (b) Seybold, G.; Wagenblast, G. Dyes Pigm.
1989, 11, 303.
(12) Becker, H. G. O. Einführung in die Photochemie; Thieme:
Stuttgart, 1983.
UV/Vis (CH2Cl2): lmax (e) = 413 (9060), 436 (13800), 477 (16900),
510 nm (29600).
Fluorescence (CH2Cl2): lmax = 520, 554 nm.
Fluorescence quantum yield (CH2Cl2): Ffl = 0.16.
N,N¢-Di(2¢,6¢-diisopropylphenyl)-6-n-hexyloxy-5,8,9,10-(1,4-
diaza-1,2,3,4-tetrahydroanthracene)tetracarboxylic Acid Di-
imide (6b)
Prepared as above from compound 2b (33 mg, 0.057 mmol) and
K2CO3 (79 mg, 0.57 mmol) in n-hexanol (3 mL) to give 6b as an or-
ange-red solid (18 mg, 49%).
Mp >300 °C.
1H NMR (400 MHz, CDCl3): d = 0.85 (m, 3 H), 1.17 (m, 24 H),
1.28 (m, 4 H), 1.46 (m, 2 H), 1.89 (m, 2 H), 2.71 (m, 4 H), 3.72 (br
s, 4 H), 4.28 (t, J = 6.5 Hz, 2 H), 7.34 (m, 4 H), 7.49 (m, 2 H), 8.03
(s, 1 H), 10.34 (s, 1 H), 10.90 (s, 1 H).
Synthesis 2007, No. 12, 1872–1876 © Thieme Stuttgart · New York