Synthesis and Characterization of Carbazole-Based Dendrimers with Porphyrin Cores

Article abstract of DOI:10.1002/ejoc.200600356

A series of novel dendritic carbazole-based porphyrins [T(Cz-Gn)Ps] have been synthesized by a combination of Ullmann coupling and Adler condensation reactions and their intramolecular energy-transfer properties have been studied by absorption and steady-state fluorescence spectroscopy. It has been found that the light-harvesting capabilities of T(Cz-Gn)Ps increase with increasing generation, but that the efficiency of the enrgy transfer decreases from T(Cz-G0)P to T(Cz-G2)P due to the Foerster energy-transfer process. In addition, these dendritic macromolecules can emit intense red light with high fluorescence quantum yields and so may find applications in photonic devices.

Full text of DOI:10.1002/ejoc.200600356

FULL PAPER
DOI: 10.1002/ejoc.200600356
Synthesis and Characterization of Carbazole-Based Dendrimers with Porphyrin
Cores
[
a]
[a]
[a]
[a]
[a]
Ting Hua Xu, Ran Lu,* Xian Ping Qiu, Xing Liang Liu, Peng Chong Xue,
[a]
[a]
[a]
Chang Hui Tan, Chun Yan Bao, and Ying Ying Zhao
Keywords: Carbazole / Dendrimers / Porphyrin / Energy transfer / Light-harvesting antennas / Red photoluminescence
A series of novel dendritic carbazole-based porphyrins
T(Cz-Gn)Ps] have been synthesized by a combination of
that the efficiency of the energy transfer decreases from
T(Cz-G0)P to T(Cz-G2)P due to the Förster energy-transfer
process. In addition, these dendritic macromolecules can
emit intense red light with high fluorescence quantum yields
and so may find applications in photonic devices.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2006)
[
Ullmann coupling and Adler condensation reactions and
their intramolecular energy-transfer properties have been
studied by absorption and steady-state fluorescence spec-
troscopy. It has been found that the light-harvesting capabili-
ties of T(Cz-Gn)Ps increase with increasing generation, but
Introduction
is an interesting undertaking that may find many attractive
applications, since porphyrins are excellent functional or-
Dendrimers are monodisperse, highly branched macro- ganic molecules, and their functionalities are often affected
[
3]
molecules with well defined three-dimensional structures, by the local environment. Of particular interest is their
based on an interior core with a regular array of branching efficient light-harvesting ability for use as antennas. Al-
[
1]
units. Increasing attention has recently been focused on though considerable efforts in the exploration of light-har-
[
3b,3f,3m,3n]
the incorporation of functional units into such dendritic vesting dendritic porphyrins with flexible
and
dendrons have already been made, the
To encapsulate a porphyrin core in the development of π-conjugated porphyrin-containing dendri-
[
3c–3e,3g,3h,3k,3l,3o]
structures to provide new nanoscopic materials with desir- rigid
[
2,3]
able properties.
interior of a dendritic structure with various dendron units mers is still the subject of much attention. On the other
Scheme 1. Molecular structures of T(Cz-Gn)Ps.
hand, carbazole is a promising building block for dendritic
[
a] Key Laboratory of Supramolecular Structure and Materials, construction because of its chemical structure and special
College of Chemistry, Jilin University,
Changchun 130012, P. R. China
[2i,2k,4]
electronic and optical properties.
Construction of a
rigid carbazole dendron around a porphyrin core may result
in interesting photochemical, electrochemical, and catalytic
properties, but there has so far been no example of a por-
Fax: + 86-431-8923907
E-mail: luran@mail.jlu.edu.cn
Supporting information for this article is available on the
WWW under http://www.eurjoc.org or from the author.
4014
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Eur. J. Org. Chem. 2006, 4014–4020

Carbazole-Based Dendrimers with Porphyrin Cores
FULL PAPER
phyrin directly covalently linked to a carbazole dendron. out in N,N-dimethylacetamide (DMAc), with Cu O cataly-
2
Here we report the synthesis, characterization, and photo- sis at 160 °C. The reactivities of the N–H groups in the car-
physical behaviors of porphyrins with four monodisperse bazole moieties in the Ullmann reaction decreased with in-
dendritic carbazole arms (Scheme 1). We have found that creasing generation of the dendron, so compound 13 was
the light-harvesting abilities of T(Cz-Gn)Ps increase with obtained from compounds 7 and 10 at 180 °C. Although
increasing generation. Meanwhile, the carbazole-based den- the Ullmann coupling conditions were harsh, the aldehyde
drimers can emit intense red light with high fluorescence groups in the obtained carbazole dendrons did not decom-
quantum yields, because the carbazole units can reduce the pose. The pure carbazole dendrons could be readily recrys-
self-quenching of the fluorescence of the porphyrin cores, tallized from THF/EtOH in moderate yields. Because the
and they may be good candidates for photonic devices.
Ullmann coupling reactions were catalyzed by Cu O, and
2
the residual Cu2 present would coordinate with porphyrin
in the later Adler reaction, the obtained aldehydes 11 and
13 were further purified by column chromatography. In or-
der to study the photoinduced energy interactions between
carbazole units and phorphyrin cores in the dendrimers
conveniently, the carbazole dendron 12 was also synthesized
in an Ullmann coupling reaction.
+
Results and Discussion
Synthesis of the Carbazole-Based Dendrons
The synthetic routes to the carbazole dendrons 9, 11, and
13 are shown in Schemes 2 and 3. Firstly, iodination of car-
bazole with KI/KIO in AcOH at 80 °C provided com-
3
pound 5 in a yield of 56%.[ N-Alkylation of compounds 4
5]
and 5 with 1-bromobutane was carried out at 0 °C in DMF Synthesis of the Dendrimers
containing NaH, giving compounds 6 and 8, respectively,
in quantitative yields.[ 9-Butylcarbazole-3-carbaldehyde
6]
The synthesis of dendritic carbazole-based porphyrins is
[
9]
shown in Scheme 4. The obtained aldehydes 9, 11, and 13
were converted into the corresponding dendritic porphyrins
T(Cz-Gn)Ps (1–3) under Adler conditions in xylene and in
the presence of 4-nitrobenzoic acid as the catalyst in yields
of 21%, 11%, and 7%, respectively. It was found that the
Adler condensation time increased with the increase in the
carbazole dendrons’ volumes: the formation of T(Cz-G0)P,
for instance, needed 3 h, whilst T(Cz-G1)P and T(Cz-G2)P
were synthesized over 10 h and 24 h, respectively. According
to previous reports the conditions of the Adler condensa-
tion are harsh and the yields low, but the reaction was easy
(
9) was readily obtained from 8 through a Vilsmeier reac-
[7]
tion in a yield of 79%, and compound 7, an important
intermediate for the synthesis of larger carbazole dendrons,
was prepared from 6, also through a Vilsmeier reaction.
Scheme 2. Synthesis of compounds 7 and 9. Reagents and condi- to operate and gave moderate yields. We also adopted
tions: a) (i) NaH, DMF, 20 min, (ii) n-C
4 9
H Br, room temp., 1 h. b)
Lindsey conditions to prepare the above porphyrins, but
only traces of T(Cz-Gn)Ps were obtained when trifluoro-
acetic acid was used as catalyst in CH Cl in the dark, fol-
POCl , DMF, ClCH CH Cl, reflux, 8 h.
3
2
2
2
2
Compounds 11 and 13 were synthesized by Ullmann lowing by DDQ oxidation and Et N neutralization.[10]
3
coupling of 7 with compounds 4 and 10, respectively
The obtained dendritic porphyrins T(Cz-Gn)Ps were sol-
[
2i,2k,4d,4e,8]
(Scheme 3).
Compound 10 was synthesized as de- uble in chloroform, THF, and CH Cl , their solubilities in-
2
2
[2i,2k]
scribed in the literature,
with the reaction being carried creasing with the generation. All intermediates and final
Scheme 3. Synthesis of carbazole dendrons 11, 12, and 13.
Eur. J. Org. Chem. 2006, 4014–4020
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R. Lu et al.
FULL PAPER
Scheme 4. Synthesis of T(Cz-Gn)Ps.
products were purified by column chromatography on silica ever, the Soret band of 3 was red-shifted by 16 nm relative
1
gel and characterized by FT-IR and H NMR spectroscopy, to TPP, which indicated that the carbazole in compound 3
MALDI-TOF mass spectrometry, and GPC. The MALDI- was partially conjugated with the porphyrin ring. As shown
TOF mass spectra of T(Cz-Gn)Ps 1–3 are given in the Sup- in Figure 3, the absorption bands for the porphyrin cores
porting Information, and the results fitted the calculated of compounds 1–3 in films were bathochromically shifted
values very well. The gel permeation chromatography in relation to those in solution, due to the aggregation ef-
(GPC) eluting curves of 1–3 each showed a symmetrical, fect, with the degree of redshift depending on the genera-
narrow peak, which indicated high purity (see Figures S1– tion number of the dendrimer: the absorptions of 1, 2, and
S3, Supporting Information).
3 in films, for example, were red-shifted by 19, 18, and
5 nm, respectively, or in other words, the higher the gener-
1
ation, the smaller the redshift in the absorption. We de-
duced that the dendrons in higher-generation dendrimers
had a site isolation effect on the porphyrin core.
Optical Properties of T(Cz-Gn)Ps
The absorption and fluorescent emission data for T(Cz-
Gn)Ps 1, 2, and 3 are listed in Table 1. In THF, we can
observe several absorption bands in the visible region, in-
cluding four Q-bands in the 500–700 nm region (consistent
with a free-base porphyrin), together with the Soret band
at ca. 430 nm, and others in the UV region (250–350 nm)
due to carbazole units (see Figure 1). With increasing gen-
eration number the molar extinction coefficients of the por-
phyrin units remained constant, but those for the carbazole
dendrons in the UV region increased because of the grow-
ing numbers of carbazole units, whereas no spectral broad-
ening or spectral shift took place. This suggested that the
electronic structures of the dendritic porphyrins were not
changing with increasing generation number, which pro-
vided an opportunity to excite the dendrons selectively and
[
2a,3b]
to study the intramolecular energy transfer properties.
As can be seen in Figure 2, we found that the Soret band
of TPP + 12 appeared at the same region as that of TPP,
which meant that physical mixing of the carbazole dendron
Figure 1. UV/Vis absorption spectra of 1–3 in THF (1 µ). The
dotted curve represents the fluorescence spectrum of the dendron
with TPP could not induce a shift in the Soret band. How- 12 in THF (1 µ) upon excitation at 293 nm.
Table 1. Absorption and fluorescence emission data in THF and in thin film for T(Cz-Gn)Ps.
[
b]
Dendrimer
In THF
431 347
Φ
ET
In film
λabsmax [nm]
293, 342
293, 342
292, 341
λemmax [nm]
[a]
λabsmax [nm]
295, 348
297, 347
298, 343
λemmax [nm]
[c]
T(Cz-G0)P
T(Cz-G1)P
T(Cz-G2)P
665, 725
666, 727
664, 730
69%
65%
40%
450
450
446
678
671
671
747
730
732
432
431
384
392
[a] Excited at 293 nm. [b] Energy transfer efficiency (ΦET) was calculated by comparison of the absorption and excitation spectra of
dendrimers with monitoring of the emission of the porphyrin core (664 nm) in THF. [c] Excited at 451 nm.
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Carbazole-Based Dendrimers with Porphyrin Cores
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Figure 2. UV/Vis absorption spectra of (a) TPP, (b) TPP + 12 (TPP
mixed with 4 equiv. of 12), and (c) compound 3 in THF (1 µ).
Figure 4. Emission spectra of 1–3 at 1 µ in THF (λex = 432 nm).
Figure 5. Normalized fluorescence spectra of 1–3 (film) excited at
451 nm.
Figure 3. Normalized absorption spectra of 1–3 (film).
As can be seen in Figure 4, we were able to find that, in showed that porphyrins connected to peripheral carbazole
THF, all dendrimers showed characteristic luminescence of units could have light-harvesting potential, and that it was
their porphyrin cores, with two emission bands at ca. possible to obtain intense emission from the core when ex-
664 nm and 730 nm on excitation at 432 nm. In films, the cited by sensitization from the large light-harvesting an-
emission bands located at around 670 nm were broadened tenna. As discussed above, we were able to address the car-
and red-shifted – relative to the fluorescence in solution – bazole dendrons and the porphyrin core independently by
by 14, 6, and 6 nm for T(Cz-G0)P, T(Cz-G1)P, and T(Cz- changing the excitation wavelength because of the following
G2)P, respectively (as shown in Figure 5). The results indi- facts: (1) the absorption spectra of the two chromophores
cated that the higher-generation dendrimer had a smaller did not overlap, and (2) the carbazole dendron function-
Stokes shift than the lower one, indicative to a certain ex- alized porphyrin could not significantly perturb the elec-
tent of a site isolation or dendron dilution effect, reducing tronic transition in the ground state. As shown in Figure 7,
the extent or possibility of aggregation of the core. How- on excitation at 293 nm T(Cz-Gn)Ps gave strong emission
ever, the attachment of the above dendrons to the porphyrin bands at 664 nm and 730 nm attributable to the emission
could not completely shield the chromophore core.
of porphyrin cores and weak emissions due to carbazole
Bifunctional dendrimers represented an ideal architec- dendrons. Because the porphyrin should not emit red light
ture with which to reveal the interaction between chromo- under excitation at 293 nm, we concluded that intramolecu-
phores. On excitation at 293 nm, compound 12 emitted lar energy transfer from carbazole units to porphyrin cores
strong fluorescence at 394 nm, partially overlapping with (energy trap) was taking place. It was also found that the
the Soret band of the porphyrin core (see Figure 1). A sing- red photoluminescence was enhanced with increasing gen-
let–singlet Förster energy transfer might therefore take eration, which suggested that the light-harvesting abilities
place in T(Cz-Gn)Ps, as was clearly demonstrated by the improved from 1 to 3 because of the multiplying of the
excitation and absorption spectra (see Figure 6). These number of carbazole units (energy-collecting sites). A mix-
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R. Lu et al.
FULL PAPER
ture of TPP and 12 showed no porphyrin moiety emission
bands when excited at 293 nm; thus, as expected, no energy
transfer took place between compound 12 and TPP in a
simple mixture, but the carbazole units in the dendrimers
exhibited significant light-harvesting for the luminescence
of porphyrin cores. The efficiency of energy transfer (ΦET
)
could be estimated by comparing the UV/Vis spectrum with
the excitation spectrum recorded at 293 nm,[
ΦET values for T(Cz-Gn)Ps (1–3) were found to be 69%,
5%, and 40%, respectively (see Figure 6). It was clear that
2a,3b,11]
and the
6
the energy-transfer efficiency decreased for the higher-gen-
eration dendrimers, which could be explained by the Förster
mechanism of energy transfer, and that the distance be-
tween the donor and the acceptor might play an important
[
2a]
role in the ΦET. These results were similar to the findings
of W. Dehaen et al., but the energy transfer did not reach
1
Figure 7. Emission spectra of 1–3 at 1 µ in THF (λex = 293 nm).
00% in our system.[3o] In addition, on direct excitation of
the core, the Förster energy transfer between the periphery
donors and the core acceptor in the dendrimers could be
neglected. From Figure 4 we were able to determine that
the emission intensities of the cores for carbazole-based
dendrimers at the same concentrations were almost equal
(within experimental deviation) on excitation at 432 nm,
which indicated that there was no other quenching pathway
in such a system, so the photoinduced energy transfer in
T(Cz-Gn)Ps could be outlined as shown in Figure 8.
Figure 8. Schematic diagram for energy transfer in T(Cz-Gn)Ps (1–
). (I) excited at maximum absorption of Cz (293 nm), (II) energy
transfer, (III) excited at maximum absorption of porphyrin
432 nm).
3
(
Table 2.[a] Fluorescence quantum yields (Φ
and TPP in THF.
) of T(Cz-Gn)Ps 1–3
F
T(Cz-G0)P (1) T(Cz-G1)P (2) T(Cz-G2)P (3) TPP
0.215 0.199 0.201 0.110
a] Excitation at 423 nm.
Φ
F
[
Conclusion
We have synthesized three dendritic carbazole-based por-
phyrins T(Cz-Gn)Ps (1–3) with intramolecular energy-
transfer properties. The light-harvesting abilities of these
compounds increased with increasing generation number,
Figure 6. Absorption and corrected excitation spectra of T(Cz-G1)-
P in THF monitored at the porphyrin core emission wavelength so the T(Cz-Gn)Ps were efficient light harvesters. The effi-
(
664 nm). The excitation spectra were normalized at the Soret ab-
ciency of the energy transfer, however, decreased with the
generation because the energy-transfer process followed the
Förster mechanism. Meanwhile, these dendritic macromole-
cules could emit intense red light with high fluorescence
quantum yields, and so might be good candidates for pho-
tonic devices.
sorption band of the porphyrin.
The emission spectra of T(Cz-Gn)Ps on excitation at 423
and 293 nm revealed that the dendrimers could emit intense
red light. We obtained the fluorescence quantum yields
(
Φ ) of 1–3 in THF relative to TPP (Φ = 0.11), which were
F
F
Experimental Section
in the range from 0.199 to 0.215 and much higher than
those of other porphyrins (Table 2)[
3i,3l]
because the carba-
General: Tetrahydrofuran (THF) was distilled from sodium/benzo-
zole units were able to reduce the self-quenching of the fluo- phenone; other chemicals were purchased and used as received. 3-
rescence of porphyrin cores.
Iodocarbazole (5), N-butylcarbazole (8), and 3,6-bis(9Ј-carbazol-
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Carbazole-Based Dendrimers with Porphyrin Cores
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yl)-9H-carbazole (10) were prepared as described in the litera-
and the mixture was heated to 190 °C in an oil bath for 24 h and
then allowed to cool to room temperature and filtered. The filtrate
was poured into H O (300 mL) and stirred for 20 min, the solid
2
[
2i,2k,4d,4e,5,6] 1
ture.
H NMR spectra were recorded with Mercury
as
plus 300 MHz and JEOL JNM-500EX instruments in CDCl
3
solvent in all cases. UV/Vis spectra were determined with a Shim-
adzu UV-1601PC spectrophotometer, PL spectra were measured
with a Shimadzu RF-5301 luminescence spectrometer, and IR spec-
tra were measured with a Nicolet-360 FT-IR spectrometer by in-
corporation of samples in KBr disks. Mass spectra were performed
with an Agilent 1100 MS series and an AXIMA CFR MALDI/
TOF (matrix-assisted laser desorption ionization/time-of-flight)
MS (COMPACT) instrument. The gel permeation chromatography
was collected by filtration and recrystallized from EtOH/THF (4:1,
v/v) to give a light yellow solid (0.70 g, 63%); m.p. 164.0–166.0 °C.
1
3
H NMR (CDCl , 300 MHz): δ = 10.10 (s, 1 H, –HC=O), 8.59 (s,
1 H, Ar–H), 8.33 (s, 1 H, Ar–H), 8.19 (d, 2 H, Ar–H), 8.09 (d, 1
H, Ar–H), 7.67 (m, 2 H, Ar–H), 7.56 (d, 1 H, Ar–H), 7.43–7.38
(m, 4 H, Ar–H), 7.34–7.28 (m, 2 H, Ar–H), 4.56 (t, 2 H,
–NCH
–CH –), 1.03 (t, 3 H, –CH
2867, 1684, 1626, 1595, 1496, 1451, 1377, 1231, 751 cm ; a strong
2
2
–), 2.00–1.95 (m, 2 H, –CH –), 1.57–1.46 (m, 2 H,
2
3
) ppm. IR (KBr): ν˜ = 3054, 2955, 2928,
–
1
(GPC) measurements were performed with a Waters chromato-
–
1
graph connected to a Waters 410 differential refractometer with
THF as an eluent.
peak at 1684 cm is the ν
s
of a C=O moiety. MS: calcd. 416.5;
+
found 417.1 [M+H] .
9
-Butyl-3-iodocarbazole (6): NaH (60 wt.-%; 1.0 g, 25.0 mmol) and
9-Butyl-3-Cz2-carbazole (12) [Cz2 = 3,6-bis(carbazol-9-yl)carbazol-
9-yl]: Compound 12 was produced by the procedure used for the
preparation of 11, collected by filtration, and purified by column
chromatography (silica gel; hexane/ethyl acetate, 10:1, v/v) to give
n-C Br (1.85 mL, 17.2 mmol) were added to a solution of com-
4
H
9
pound 5 (5.0 g, 17.1 mmol) in DMF (30 mL). The mixture was
stirred at room temperature until the reaction was complete, as
monitored by TLC. The mixture was poured into water (200 mL),
the precipitate collected by filtration, and recrystallized from petro-
1
56 mg (68%) of a white solid; m.p. 212.0–214.0 °C. H NMR
(CDCl
8.16 (d, 5 H, Ar–H), 7.75–7.54 (m, 9 H, Ar–H), 7.44–7.37 (m, 8 H,
–), 2.01–
–), 1.03 (t, 3 H,
) ppm. IR (KBr): ν˜ = 3042, 2950, 2919, 2853, 1614, 1593,
3
, 300 MHz): δ = 8.41 (s, 1 H, Ar–H), 8.31 (s, 2 H, Ar–H),
leum ether to give 4.0 g (67%) of a white solid, m.p. 44.0–46.0 °C.
1
H NMR (CDCl
3
, 300 MHz): δ = 8.39 (s, 1 H, Ar–H), 8.03 (d, 1 Ar–H), 7.33–7.27 (m, 4 H, Ar–H), 4.46 (t, 2 H, –NCH
–), 1.28–1.23 (m, 2 H, –CH
2
H, Ar–H), 7.69 (d, 1 H, Ar–H), 7.50 (d, 1 H, Ar–H), 7.39 (d, 1 H, 1.96 (m, 2 H, –CH
Ar–H), 7.24–7.17 (m, 2 H, Ar–H), 4.27 (t, 2 H, –NCH –), 1.78– –CH
–), 0.94 (t, 3 H, 1493, 1474, 1450, 1332, 1311, 1230, 802, 748, 722 cm . MS: calcd.
) ppm. IR (KBr): ν˜ = 3048, 2956, 2924, 2856, 1619, 1588, 718.9; found 719.7 [M+H] .
2
2
2
3
–
1
1
–
1
3
2 2
.88 (m, 2 H, –CH –), 1.30–1.41 (m, 2 H, –CH
+
CH
3
–1
473, 1458, 1345, 1331, 1273, 1213, 797, 747, 722 cm . MS: calcd.
49.3; found 350.2 [M+H] .
9-Butyl-6-Cz2-carbazole-3-carbaldehyde (13): Compound 13 was
+
produced by the procedure used for the preparation of 11, collected
9
-Butyl-6-iodocarbazole-3-carbaldehyde (7): Phosphoryl chloride
by filtration, and recrystallized from EtOH/THF (4:1, v/v) to give
1.0 g (51%) of a light yellow solid; m.p. 218.0–220.0 °C. H NMR
1
(4.0 g, 0.025 mol) was added slowly to DMF (5.0 g, 0.07 mol), with
purging with nitrogen and cooling to 0 °C. The Vilsmeier reactant
was then allowed to warm to room temperature, stirred for 1 h,
and then cooled to 0 °C. After that, a solution of 9-butyl-3-iodo-
carbazole (6, 5.3 g, 0.015 mol) in 1,2-dichloroethane (13 mL) was
3
(CDCl , 300 MHz): δ = 10.13 (s, 1 H, –HC=O), 8.69 (s, 1 H, Ar–
H), 8.49 (s, 1 H, Ar–H), 8.30 (m, 2 H, Ar–H), 8.18–8.10 (m, 5 H,
Ar–H), 7.89–7.67 (m, 2 H, Ar–H), 7.64–7.50 (m, 5 H, Ar–H), 7.50–
7.32 (m, 9 H, Ar–H), 7.31–7.28 (m, 3 H, Ar–H), 4.48 (t, 2 H,
added, and after 1 h the system was warmed to 90 °C for 8 h. Fi- –NCH
nally, the cooled solution was poured into water, extracted with –CH –), 1.05 (t, 3 H, –CH
CH Cl , and dried with anhydrous magnesium sulfate. The crude 2864, 1687, 1626, 1596, 1494, 1450, 1385, 1280, 1230, 749 cm ; a
product was purified by column chromatography on silica gel
CH Cl /hexane 3:1, v/v) to give 3.2 g (57%) of a light yellow solid; 746.9; found 747.8 [M+H] .
m.p. 111.0–112.0 °C. H NMR (CDCl
2
2
–), 2.02–1.96 (m, 2 H, –CH –), 1.57–1.46 (m, 2 H,
2
3
) ppm. IR (KBr): ν˜ = 3047, 2949, 2926,
–
1
2
2
–
1
s
strong peak at 1687 cm is the ν of a C=O moiety. MS: calcd.
+
(
2
2
1
3
, 300 MHz): δ = 10.09 (s, 1
H, –HC=O), 8.55 (s, 1 H, Ar–H), 8.47 (s, 1 H, Ar–H), 8.03 (d, 1
H, Ar–H), 7.78 (d, 1 H, Ar–H), 7.47 (d, 1 H, Ar–H), 7.24 (d, 1 H,
T(Cz-G0)P (1): 9-Butylcarbazole-3-carbaldehyde (9, 1.4 g,
.6 mmol) and p-nitrobenzoic acid (0.47 g, 2.8 mmol) were dis-
5
solved in xylene (45 mL). The mixture was heated to reflux, a solu-
tion of pyrrole (0.39 mL, 5.6 mmol) in xylene (5 mL) was slowly
added, and the system was stirred for a further 3 h. Xylene (30 mL)
was distilled from the mixture, after which MeOH (70 mL) was
added. The crude product was collected by filtration and purified
Ar–H), 4.32 (t, 2 H, –NCH
2
–), 1.88–1.83 (m, 2 H, –CH
–), 0.96 (t, 3 H, –CH ) ppm. IR (KBr): ν˜ =
058, 2945, 2925, 2871, 1687, 1622, 1587, 1566, 1478, 1379 cm ; a
2
–), 1.57–
1
3
.35 (m, 2 H, –CH
2
3
–
1
–1
s
strong peak at 1687 cm is the ν of a C=O moiety. MS: calcd.
+
3
77.2; found 378.4 [M+H] .
through a short pad of silica gel with elution with CHCl
the crude porphyrin. Further chromatography (silica gel; CHCl
petroleum ether, 1:1, v/v) gave the product as a purple solid
3
to afford
9
-Butylcarbazole-3-carbaldehyde (9): The product was obtained by
the procedure used for the preparation of 7 and purified by column
chromatography (silica gel; hexane/ethyl acetate, 4:1, v/v). Yield
3
/
1
3
(350 mg, 21%); m.p. Ͼ 250 °C. H NMR (CDCl , 300 MHz): δ =
1
7
9%. M.p. 43.0–45.0 °C. H NMR (CDCl
3
, 300 MHz): δ = 10.06 8.96 (s, 4 H, Ar–H), 8.89 (s, 8 H, Ar–H), 8.36 (d, 4 H, Ar–H), 8.18
(
(
4
2
2
s, 1 H, –HC=O), 8.51 (s, 1 H, Ar–H), 8.09 (d, 1 H, Ar–H), 7.96 (d, 4 H, Ar–H), 7.74 (d, 4 H, Ar–H), 7.60–7.52 (m, 8 H, Ar–H),
d, 1 H, Ar–H), 7.50 (d, 1 H, Ar–H), 7.29–7.42 (m, 3 H, Ar–H), 7.29–7.27 (m, 4 H, Ar–H), 4.55 (t, 8 H, –NCH –), 2.12–2.05 (m, 8
H, –CH –), 1.65–1.57 (m, 8 H, –CH –), 1.10 (t, 12 H, –CH ),
) ppm. IR (KBr): ν˜ = 3054, 2958, –2.43 (s, 2 H, –NH–) ppm. IR (KBr): ν˜ = 3447, 3048, 2950, 2919,
2
.20 (t, 2 H, –NCH
2
–), 1.76–1.83 (m, 2 H, –CH
2
–), 1.30–1.41 (m,
2
2
3
H, –CH –), 0.94 (t, 3 H, –CH
2
3
–1
931, 2867, 1686, 1625, 1593, 1494, 1466, 1383 cm ; a strong peak 2848, 1655, 1593, 1490, 1459, 1372, 1349, 1265, 1244, 1211, 1146,
–
1
–1
at 1686 cm is the ν
2
s
of a C=O moiety. MS: calcd. 251.3; found
1122, 804, 746, 727 cm . MALDI-TOF: calcd. 1195.5; found
+
52.2 [M+H] .
1195.4 (see Figure S1, Supporting Information).
9
-Butyl-6-Cz1-carbazole-3-carbaldehyde (11) (Cz1 = carbazol-9-yl):
T(Cz-G1)P (2): Compound 11 (0.8 g, 1.9 mmol) and p-nitrobenzoic
acid (0.24 g, 1.4 mmol) were dissolved in xylene (30 mL). The mix-
ture was heated to reflux, pyrrole (0.133 mL, 1.9 mmol) in xylene
(5 mL) was then slowly added, and the mixture was stirred for a
Carbazole (0.5 g, 3.0 mmol), 9-butyl-6-iodocarbazole-3-carbal-
dehyde (7, 1.0 g, 2.65 mmol), Cu O (1.0 g, 7.0 mmol), and DMAc
7 mL) were sequentially placed in a sealed tube under nitrogen,
2
(
Eur. J. Org. Chem. 2006, 4014–4020
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4019

R. Lu et al.
FULL PAPER
further 6 h. Xylene (20 mL) was distilled from the mixture, after
which MeOH (70 mL) was added. The crude product was collected
by filtration and purified through a short pad of silica gel with
Hofkens, F. C. De Schryver, K. Müllen, Chem. Eur. J. 2001, 7,
4
844–4853; h) T. H. Ghaddar, J. F. Wishart, D. W. Thompson,
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8
289; i) N. D. McClenaghan, R. Passalacqua, F. Loiseau, S.
elution with CHCl
3 3
. Further chromatography (silica gel; CHCl /
Campagna, B. Verheyde, A. Hameurlaine, W. Dehaen, J. Am.
Chem. Soc. 2003, 125, 5356–5365; j) K. R. J. Thomas, A. L.
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petroleum ether, 1:1, v/v) gave the product as a purple solid
1
(
8
(
100 mg, 11%); m.p. Ͼ 250 °C. H NMR (CDCl
.92–8.84 (m, 8 H, Ar–H), 8.44–8.29 (m, 12 H, Ar–H), 8.18–8.04
m, 8 H, Ar–H), 7.86–7.60 (m, 12 H, Ar–H), 7.46–7.32 (m, 20 H,
Ar–H), 7.21–7.19 (m, 4 H, Ar–H), 4.64 (t, 8 H, –NCH –), 2.23–
–), 1.14 (t, 12 H,
), –2.54 (s, 2 H, –NH–) ppm. IR (KBr): ν˜ = 3442, 3052, 2945,
919, 2848, 1650, 1593, 1492, 1477, 1451, 1342, 1286, 1230, 1148,
3
, 300 MHz): δ =
2
2
–
2
7
.09 (m, 8 H, –CH
2
–), 1.74–1.59 (m, 8 H, –CH
2
[3] a) F. Wurthner, M. S. Vollmer, F. Effenberger, P. Emele, D. U.
Meyer, H. Port, H. C. Wolf, J. Am. Chem. Soc. 1995, 117,
CH
3
8
090–8099; b) D. L. Jiang, T. Aida, J. Am. Chem. Soc. 1998,
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120, 10895–10901; c) J. N. G. Pillow, M. Halim, J. M. Lupton,
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5
99, 748, 717 cm . MALDI-TOF: calcd. 1856.3; found 1858.2 (see
Figure S2, Supporting Information).
993; d) M. Kimura, T. Shiba, T. Muto, K. Hanabusa, H. Shi-
rai, Macromolecules 1999, 32, 8237–8239; e) M. Kimura, T.
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T(Cz-G2)P (3): Compound T(Cz-G2)P (3) was obtained as a pur-
ple solid (60 mg, 7%) by the procedure used for the preparation of
1
T(Cz-G1)P (2); m.p. Ͼ 250 °C. H NMR (CDCl
3
, 500 MHz): δ =
9
.01–8.82 (m, 8 H, Ar–H), 8.54–8.40 (m, 12 H, Ar–H), 8.31–8.06
m, 24 H, Ar–H), 7.99–7.93 (m, 4 H, Ar–H), 7.91–7.74 (m, 16 H,
Ar–H), 7.70–7.31 (m, 56 H, Ar–H), 4.68 (t, 8 H, –NCH –), 2.22–
.11 (m, 8 H, –CH –), 1.76–1.64 (m, 8 H, –CH –), 1.16–1.09 (t, 12
H, –CH ), –2.46 (s, 2 H, –NH–) ppm. IR (KBr): ν˜ = 3447, 3053,
955, 2919, 2853, 1654, 1593, 1492, 1451, 1377, 1311, 1281, 1231,
1
1848–11849; g) K. Onitsuka, H. Kitajima, M. Fujimoto, A.
(
Iuchi, F. Takei, S. Takahashi, Chem. Commun. 2002, 2576–
2577; h) T. Imaoka, H. Horiguchi, K. Yamamoto, J. Am.
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2
2
2
2
3
2
1
3
–1
153, 799, 748, 723 cm . MALDI-TOF: calcd. 3177.8; found
180.8 (see Figure S3, Supporting Information).
2
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Received: April 25, 2006
Published Online: July 10, 2006
Herrmann, T. Weil, V. Sinigersky, U. M. Wiesler, T. Vosch, J.
4020
www.eurjoc.org
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2006, 4014–4020