Subporphyrins with monodisperse oligocarbazole arms

Article abstract of DOI:10.1002/ejoc.200800646

Novel star-shaped subporphyrins with monodisperse oligocarbazole arms were prepared by using pyridine-tri-N-pyrrolylborane as a template. It was found that photoinduced energy transfer took place from the oligocarbazole arms to the subporphyrin core, and

Full text of DOI:10.1002/ejoc.200800646

FULL PAPER
DOI: 10.1002/ejoc.200800646
Subporphyrins with Monodisperse Oligocarbazole Arms
Xingliang Liu,[a] Ran Lu,*[a] Tinghua Xu,[a] Defang Xu,[a] Yong Zhan,[a] Peng Chen,[a]
Xianping Qiu,[a] and Yingying Zhao[a]
Keywords: Porphyrinoids / Fluorescence / Conjugation / UV/Vis spectroscopy / Energy transfer
Novel star-shaped subporphyrins with monodisperse oligo-
carbazole arms were prepared by using pyridine-tri-N-pyr-
rolylborane as a template. It was found that photoinduced
energy transfer took place from the oligocarbazole arms to
the subporphyrin core, and the energy transfer efficiency de-
creased with an increase in the number of carbazole units in
the arms. These subporphyrins could emit intense yellow-
green light when they were excited at 295 nm.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2009)
and their optoelectronic properties can be finetuned by
varying the axial ligands or by functionalizing the periph-
Introduction
As important members in porphyrin families,[1] expanded eral substituents.[6] The applications of SubPcs in dye-based
porphyrins with more than 18π electron have been exten- technological devices,[7] supramolecular building blocks,[8]
sively studied for many years because of their unique prop- and nonlinear optical chromophores[9] have been widely de-
erties and potential applications in two-photon absorption, veloped. Recently, the first subporphyrin (SubP) with sim-
multiple metal ion coordination, and switches.[2–4] Boron- ilar electronic structure to SubPc was prepared by the group
stable azaporphyrins, such as subphthalocyanines (SubPcs), of Osuka under harsh reaction conditions.[10] Subsequently,
were discovered in 1972 by Meller and Ossko;[5] however, more versatile and facile synthetic methods for meso-aryl
less synthetic effort has been devoted to the preparation of subporphyrins were developed by the groups of Osuka and
ring-contracted porphyrins. It is known that SubPcs with Kobayashi.[11] Subporphyrins also adopt a nonplanar
a cone-shaped conformation comprise 14π-electron systems cone-shaped conformation, and they may serve
Scheme 1. Molecular structures of T(OCAn)SubPs 1–7.
as a model to understand π-conjugated C3-symmetric por-
[a] State Key Laboratory of Supramolecular Structure and Materi-
phyrin systems when three identical groups are introduced
als, College of Chemistry, Jilin University,
into its meso positions. Until now, only few subporphyrins
bearing pyridyl or phenyl as the substituents in the meso
positions have been reported.[10,11] It is still a great chal-
lenge to synthesize novel subporphyrins modified by func-
Changchun 130012, P. R. China
Fax: +86-431-88923907
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.
Eur. J. Org. Chem. 2009, 53–60
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
53

X. Liu, R. Lu, T. Xu, D. Xu, Y. Zhan, P. Chen, X. Qiu, Y. Zhao
FULL PAPER
tional moieties that realize fascinating optoelectronic prop- and 18, which was prepared by the hydrolysis of compound
erties. It is well known that monodisperse linearly conju- 17 in a mixture of DMSO, THF, and KOH/H2O with a
gated oligomers bearing well-defined and uniform struc- good yield of 90%.[21] Compound 17 was synthesized in
tures not only represent an ideal model for molecular wires, 76% yield through an Ullmann coupling reaction between
but also favor tuning their bandgaps to investigate struc- 3-iodo-9-tosylcarbazole (15) and 16. Similarly, the Ullmann
ture–activity relationships. Nowadays, linear π-conjugated coupling reaction between p-iodobenzaldehyde and 20
oligomers are of great interest in materials science[12] due to could afford aldehyde 14, and compound 20 was obtained
their potential applications in the fields of molecular elec- from compound 15 and compound 18 under Ullmann reac-
tronics as well as in light-harvesting molecular antenna- tion condition, followed by removal of the Ts group.
type architectures.[13–16] In addition, carbazole-based oligo-
mers are attractive on account of their applications in pho-
Synthesis of the Subporphyrins
toconductors, charge-transporting and emitting materials in
OLEDs.[17,18] To the best of our knowledge, there is only
one report on a subporphyrin containing linear π-conju-
gated moieties in the literature.[11g] We recently reported the
synthesis of new subporphyrins functionalized with den-
dritic carbazole arms.[19] Herein, we have designed and syn-
thesized a series of well-defined star-shaped subporphyrins
T(OCAn)SubPs 1–7 with three monodisperse oligocarba-
zole arms in the meso positions (Scheme 1) and investigated
their photophysical properties.
Although tripyrrolylborane may be a promising template
for the synthesis of meso-aryl-substituted subporphyr-
ins,[11a] it was sensitive to oxygen and moisture, which
makes the manipulation become discommodious. Fortu-
nately, Osuka et al. presented another strategy for the syn-
thesis of subporphyrins that involved a one-pot, two-step
reaction under milder conditions by using pyridine-tri-N-
pyrrolylborane, which was stable towards oxygen and
moisture, as the template.[11b] Accordingly, we prepared
star-shaped subporphyrins 1–7 with three monodisperse oli-
gocarbazole arms through the one-pot, two-step reaction as
shown in Scheme 3. Firstly, pyridine-tri-N-pyrrolylborane
and a three molar amount of aldehyde 8 were condensed in
the presence of trifluoroacetic acid (TFA) in o-dichloroben-
zene at 0 °C under an atmosphere of nitrogen for 3 h to
Results and Discussion
Synthesis of the Precursors of the Aldehydes
Oligocarbazole aldehydes 8–12 and carbazole hexamer avoid acid-promoted scrambling. After the reaction was
16 were prepared according to the procedures reported by quenched with pyridine, the mixture was heated to reflux
our group.[20] The synthetic routes for the precursors of oli- for 1.5 h to complete the air oxidation. The crude product
gocarbazole aldehydes 13 and 14 are outlined in Scheme 2. was purified by column chromatography twice to give sub-
Compound 13 was obtained in a yield of 76% by an porphyrin 1 in a yield of 4.9%. The synthetic methods for
Ullmann coupling reaction between p-iodobenzaldehyde subporphyrins 2–7 were similar to that of 1. Because the
Scheme 2. Synthesis of the precursors of aldehydes 13 and 14.
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Eur. J. Org. Chem. 2009, 53–60

Subporphyrins with Monodisperse Oligocarbazole Arms
volumes of aldehydes 9–14 increased as the number of carb- Optical Properties of T(OCAn)SubPs
azole units increased, the condensation reaction time was
The UV/Vis absorption spectra of 1–7 in CHCl3 are
prolonged from 4 to 18 h. To avoid adsorption of the sub-
porphyrins on silica gel, as little as possible silica gel was
used during column chromatography. Possessing a similar
Rf value with its precursor 13, compound 6 was obtained
after chromatography followed by washing with ethyl ace-
tate owing to its lower solubility in ethyl acetate relative to
that of 13. The purification of subporphyrin 7 was similar
to that of 6. The yields of subporphyrins 2–7 were 4.3, 4.0,
3.0, 2.5, 2.2, and 1.8%, respectively. Interestingly, these ob-
tained star-shaped subporphyrins 1–7 bear no alkyl groups,
but they were well soluble in common organic solvents,
such as CH2Cl2, chloroform, THF, and toluene. The inter-
shown in Figure 1. Several absorption bands were observed
in the visible region, including two Q-bands in the range of
450–530 nm, together with a Soret band at 385 nm, and
other bands in the UV region (250–350 nm, Table 1) due to
the carbazole units. The absorption of the carbazole units
was clearly proportional to their increasing number in each
star-shaped subporphyrin, which indirectly reflected the
flawless or perfect structures of the as-synthesized subpor-
phyrins. In comparison to the meso-triphenylsubporphyrin,
the Soret bands of the monodisperse oligocarbazole-func-
tionalized subporphyrins 1–7 are redshifted from 374 to
385 nm, which might be due to the extensive conjugation in
1–7. From Figure 1b of the fluorescence emission spectra of
1–7 in dilute solutions, we can find strong emission bands at
ca. 537 nm attributable to the emission of subporphyrin
cores and weak emissions due to carbazole units in the
range of 350–480 nm under excitation at 295 nm, which can
selectively excite the carbazole moieties instead of the sub-
porphyrin core. This indicates that intramolecular energy
transfer from the carbazole arms to the subporphyrin cores
might take place. The remarkable changes of the time-re-
solved fluorescence spectra of the subporphyrins compared
with the reference compounds (oligocarbazoles) could also
confirm the occurrence of the excitation energy transfer in
the subporphyrins (Figure S2–S7, Supporting Information).
The fluorescence lifetimes of subporphyrins 1, 3, and 5 and
the reference compounds 21–23 were measured in CHCl3
by using a time-correlated single-photon counting (TCSPC)
instrument. The fluorescence decay was monitored at
400 nm for the reference compounds, and monitored at 400
and 537 nm for the subporphyrins under excitation at
295 nm. The values of the fluorescence lifetime are given in
Table 2. As can be inferred from these data, the lifetimes of
the reference compounds decreased with an increase in the
number of carbazole units, indicating appearance of a com-
peting nonradiative process in the larger molecules.[22b]
Nevertheless, we were unable to measure the lifetime of the
subporphyrins in the emission band of the oligocarbazole
1
mediates and the final products were characterized by H
and 13C NMR spectroscopy, FTIR spectroscopy, MALDI-
TOF mass spectrometry, and C, H, N elemental analyses
(See Supporting Information). The purity of T(OCAn)-
SubPs 1–7 was also confirmed by gel permeation
chromatography (GPC) with DMF as the eluent. As shown
in Figure S1 (Supporting Information), the retention time
decreased gradually with an increase in the molecular
weight of the compound, from 1 to 7, and all the peaks
were symmetrical. In order to investigate the excitation en-
ergy transfer of the subporphyrins, we synthesized three ref-
erence compounds 23–25 by alkylation reactions from com-
pounds 21, 22, and 16, respectively (Scheme 4).[18b]
Scheme 3. Synthesis of T(OCAn)SubPs 1–7.
Scheme 4. Synthesis of reference compounds 23–25.
Eur. J. Org. Chem. 2009, 53–60
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55

X. Liu, R. Lu, T. Xu, D. Xu, Y. Zhan, P. Chen, X. Qiu, Y. Zhao
FULL PAPER
arms (400 nm), because the residual emission was too weak reference compounds 23–25 decreased with an increase in
to measure with our instrument.[22b] The lifetimes of sub- the number of carbazoles (Table 2). Thus, the little vi-
porphyrins 1, 3, and 5 were measured by monitoring the brational deactivation of the oligocarbazole arms was an-
emission at 537 nm when excited at 295 nm and values of other possible factor to depress the energy transfer effi-
2.98, 2.80, and 2.45 ns were found. Therefore, it further il- ciency in subporphyrins. In addition, subporphyrins 1–7
lustrated the occurrence of the excitation energy transfer could emit strong yellow-green light (Figure 2). The fluores-
from the oligocarbazole arms to the subporphyrin core in cence quantum yields (ΦF) of 1–7 in THF were measured
star-shape subporphyrins 1–7. Comparison between the ex- by using quinine sulfate (ΦF = 0.546) as a standard, and
citation and the absorption spectra allowed quantitation of they were 0.132, 0.127, 0.153, 0.131, 0.141, 0.142, and 0.135
the energy transfer efficiency (ΦET),[22] and the ΦET values (Table 1), respectively.
of 1–7 were estimated to be 87, 86, 82, 74, 67, 59, and 55%,
respectively (Figures S8–S14, Supporting Information;
Table 1). It was clear that the value of ΦET decreased as the
number of carbazole units in the arms increased. On the
one hand, there was leveling-off appearance between the
energy transfer distance and the light-harvesting ability. In
other words, the increased molecular length allowed higher
light-harvesting ability due to more light-collecting units
(carbazoles); however, it resulted in a larger donor–acceptor
separation, which reduced the energy transfer efficiency. On
the other hand, the larger molecules favored the occurrence
of little vibrational deactivation, which might lead to a de-
crease in the fluorescence quantum yields to a certain de-
gree.[23] We found that the fluorescence quantum yields of
Table 2. Fluorescence lifetimes of T(OCAn)SubPs 1, 3, and 5 and
reference compounds 23–25, and the fluorescence quantum yields
of compounds 23–25.
τ[a] [ns]
τ[a] [ns] ΦF
[b]
T(OCA2)SubP (1)
T(OCA4)SubP (3)
T(OCA6)SubP (5)
2.98
2.80
2.45
Compound 23 1.94
Compound 24 1.90
Compound 25 1.85
0.218
0.210
0.210
[a] Decay profiles were satisfactorily fitted by a single exponential
function. [b] The fluorescence quantum yields were determined
against quinine sulfate in 0.1  H2SO4 (ΦF = 0.546, λex = 366 nm)
as the standard.
Figure 2. Emission spectra of 1–7 at 1 µ in CHCl3 (λex = 295 nm).
Figure 1. UV/Vis absorption spectra (normalized at the Soret
bands) of 1–7 in CHCl3.
Conclusions
Table 1. Absorption and fluorescence data for T(OCAn)SubPs 1–7
in CHCl3.
Novel star-shaped subporphyrins functionalized with
three monodisperse oligocarbazole arms T(OCAn)SubPs
(1–7) were synthesized through one-pot, two-step reactions
from pyridine-tri-N-pyrrolylborane and the corresponding
aldehydes. Such facile synthetic methodology is helpful for
us to construct other functional subporphyrins with desired
properties. The photophysical investigation indicates an ef-
ficient energy transfer occurs from the oligocarbazole arms
to the subporphyrin core, and the efficiency of the energy
transfer decreases with an increase in the number of carb-
azole units in accordance with Förster energy transfer
mechanism. In addition, the as-synthesized subporphyrins
emit intense yellow-green light. Such novel subporphyrins
might be good candidates for optical materials.
max
max[a]
[b]
[c]
λabs
[nm]
λem
[nm]
ΦET
ΦF
[%]
1
2
3
4
5
6
7
295, 346, 385, 466, 494
295, 346, 385, 466, 494
295, 346, 385, 466, 494
295, 346, 385, 466, 494
295, 346, 385, 466, 494
295, 346, 385, 466, 494
295, 346, 385, 466, 494
538
537
537
537
538
538
536
87
86
82
74
67
59
55
0.132
0.127
0.153
0.131
0.141
0.142
0.135
[a] Excited at 295 nm. [b] Energy transfer efficiency (ΦET) was cal-
culated by comparing the absorption and excitation spectra of T(O-
CAn)SubPs by monitoring the emission of the subporphyrin core.
[c] The fluorescence quantum yields were determined against quin-
ine sulfate in 0.1  H2SO4 (ΦF = 0.546, λex = 366 nm) as the stan-
dard.
56
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Subporphyrins with Monodisperse Oligocarbazole Arms
20 min. The crude product was collected by filtration, and purified
by chromatography (silica gel; petroleum ether/CH2Cl2, 1:3) and
then recrystallized from EtOH/THF (3:2) to give 13 (5.4 g, 71%)
Experimental Section
General: Ether and benzene were freshly distilled from sodium and
benzophenone. Pyrrole was distilled from sodium, and pyridine was
distilled from CaH2. N,N-dimethylacetamide (DMAc) was dried
with P2O5. Other chemicals were used as received. Compounds 13,
14, and 16–22 were synthesized according to the procedures re-
ported by our group.[20] Tri-N-pyrrolylborane was prepared from
LiBH4 and pyrrole by a reported procedure and was converted into
pyridine-tri-N-pyrrolylborane by treatment with dry pyridine under
an atmosphere of nitrogen. 1H and 13C NMR spectra were re-
corded with a Mercury plus instrument at 500 and 125 MHz by
using CDCl3 as the solvent in all cases. UV/Vis spectra were deter-
mined with a Shimadzu UV-1601PC spectrophotometer. Photolu-
minescence (PL) spectra were carried out with a Shimadzu RF-
5301 luminescence spectrometer. IR spectra were measured by
using a Nicolet-360 FTIR spectrometer by incorporating samples
in KBr disks. Mass spectra were performed with Agilent 1100 MS
series and AXIMA CFR MALDI/TOF (matrix-assisted laser de-
sorption ionization/time-of-flight) MS (COMPACT). C, H, and N
elemental analyses were taken with a Perkin–Elmer 240C elemental
analyzer. The gel permeation chromatography (GPC) measure-
ments were performed with a Waters chromatograph connected to
a Waters 410 differential refractometer with DMF as eluent.
as a light-yellow solid. M.p. Ͼ250 °C. IR (KBr): ν = 1701.0 [s,
˜
1
νs(C=O)] cm–1. H NMR (500 MHz, CDCl3): δ = 10.17 (s, 1 H, -
CHO), 8.42 (d, J = 12.0 Hz, 4 H), 8.32 (s, 1 H), 8.23–8.16 (m, 9
H), 7.91 (d, J = 8.5 Hz, 2 H), 7.77–7.61 (m, 14 H), 7.60–7.43 (m, 12
H), 7.42–7.30 (m, 12 H) ppm. MS (MALDI-TOF): m/z = 1261.8.
C91H55N7O (1262.46): calcd. C 86.58, H 4.39, N 7.77; found C
86.42, H 4.63, N 7.96.
3-{3-[3-(3-{3-[3-(9H-Carbazol-9-yl)-9H-carbazol-9-yl]-9H-carbazol-
9-yl}-9H-carbazol-9-yl)-9H-carbazol-9-yl]-9H-carbazol-9-yl}-9-(9-
tosyl-9H-carbazol-6-yl)-9H-carbazole (19): By following the syn-
thetic procedure for compound 17 and by using compound 18
(7.9 g, 6.8 mmol), 15 (4.5 g, 10 mmol), Cu2O (2.5 g, 17 mmol), and
DMAc (20 mL) as reagents, the Ullmann reaction was carried out
at 200 °C in an oil bath for 28 h. The crude product was recrys-
tallized from EtOH/THF (3:2) to give 19 (8.0 g, 79%) as a white
1
solid. M.p. Ͼ250 °C. H NMR (500 MHz, CDCl3): δ = 8.63 (d, J
= 8.5 Hz, 1 H), 8.43 (d, J = 9.5 Hz, 6 H), 8.33 (s, 1 H), 8.23–8.15
(m, 9 H), 7.96 (d, J = 7.5 Hz, 1 H), 7.87 (d, J = 8.5 Hz, 2 H), 7.79–
7.77 (m, 1 H), 7.66–7.65 (m, 12 H), 7.52–7.48 (m, 13 H), 7.44–7.30
(m, 13 H), 7.24 (d, J = 8.0 Hz, 2 H), 2.35 (s, 3 H) ppm.
C103H64N8O2S (1477.73): calcd. C 83.72, H 4.37, N 7.58; found C
3-[3-(3-{3-[3-(9H-Carbazol-9-yl)-9H-carbazol-9-yl]-9H-carbazol-9-
yl}-9H-carbazol-9-yl)-9H-carbazol-9-yl]-9-(9-tosyl-9H-carbazol-6-
yl)-9H-carbazole (17): Compound 16 (8.48 g, 8.5 mmol), 3-iodo-9-
tosylcarbazole (15; 5.7 g, 13 mmol), Cu2O (3.5 g, 24 mmol), and
DMAc (20 mL) were added sequentially into a seal tube under a
nitrogen atmosphere and heated to 195 °C in an oil bath for 24 h.
Then, the mixture was cooled to room temperature and filtered.
The filtrate was poured into H2O (300 mL) and stirred for 20 min.
The crude product was collected by filtration and recrystallized
from EtOH/THF (3:2) to give 17 (8.5 g, 76%) as a white solid. M.p.
83.71, H 4.30, N 7.68.
3-{3-[3-(3-{3-[3-(9H-Carbazol-9-yl)-9H-carbazol-9-yl]-9H-carbazol-
9-yl}-9H-carbazol-9-yl)-9H-carbazol-9-yl]-9H-carbazol-9-yl}-9-
(9H-carbazol-6-yl)-9H-carbazole (20): By following the synthetic
procedure for compound 18, compound 20 (8.3 g, 5.6 mmol) was
hydrolyzed in THF (52 mL), DMSO (26 mL), and H2O (10 mL)
containing KOH (7.0 g, 0.13 mol), and 20 (6.6 g, 89%) was ob-
tained as a white solid after chromatography (silica gel; petroleum
ether/CH2Cl2, 1:2). M.p. Ͼ250 °C. 1H NMR (500 MHz, CDCl3): δ
= 8.42–8.40 (m, 5 H), 8.32 (s, 2 H), 8.21–8.09 (m, 9 H), 8.03 (s, 1
H), 7.66–7.62 (m, 13 H), 7.51–7.42 (m, 19 H), 7.36–7.29 (m, 9 H)
ppm. MS (MALDI-TOF): m/z = 1323.1. C96H58N8 (1323.54):
calcd. C 87.12, H 4.42, N 8.47; found C 87.09, H 4.67, N 8.50.
1
Ͼ250 °C. H NMR (500 MHz, CDCl3): δ = 8.63 (d, J = 8.5 Hz, 1
H), 8.42 (d, J = 8.5 Hz, 5 H), 8.32 (s, 1 H), 8.22–8.15 (m, 8 H),
7.95 (d, J = 8.0 Hz, 1 H), 7.86 (d, J = 8.5 Hz, 2 H), 7.77 (d, J =
9.0 Hz, 1 H), 7.65–7.60 (m, 9 H), 7.56–7.43 (m, 17 H), 7.40–7.30
(m, 7 H), 7.23 (d, J = 8.0 Hz, 2 H), 2.35 (s, 3 H, -CH3) ppm.
C91H57N7O2S (1312.54): calcd. C 83.27, H 4.38, N 7.47; found C
83.40, H 4.63, N 7.38.
4-[3-(3-{3-[3-(3-{3-[3-(9H-Carbazol-9-yl)-9H-carbazol-9-yl]-9H-
carbazol-9-yl}-9H-carbazol-9-yl)-9H-carbazol-9-yl]-9H-carbazol-9-
yl}-9H-carbazol-9-yl)-9H-carbazol-9-yl]benzaldehyde (14): By fol-
lowing the synthetic procedure for compound 13 and by using com-
pound 20 (6.5 g, 4.9 mmol), 4-iodobenzaldehyde (3.0 g, 13 mmol),
Cu2O (2.5 g, 17 mmol), and DMAc (20 mL) as solvents, the
Ullmann reaction was carried out at 180 °C in an oil bath for 18 h.
The crude product was purified by chromatography (silica gel; pe-
troleum ether/CH2Cl, 1:3) and then recrystallized from EtOH/THF
(1:1) to give 14 (5.2 g, 74%) as a light-yellow solid. M.p. Ͼ250 °C.
3-{3-[3-(3-{3-[3-(9H-Carbazol-9-yl)-9H-carbazol-9-yl]-9H-carbazol-
9-yl}-9H-carbazol-9-yl)-9H-carbazol-9-yl]-9H-carbazol-9-yl}-9H-
carbazole (18): To a solution of compound 17 (9.2 g, 7.0 mmol)
dissolved in THF (34 mL), DMSO (17 mL), and H2O (7 mL) was
added KOH (7.0 g, 0.13 mol). The mixture was heated at reflux for
4 h (monitored by TLC), cooled to room temperature, neutralized
by HCl, and then poured into water to give a white solid. The
crude product was purified on silica gel (petroleum ether/CH2Cl2,
IR (KBr): ν = 1700.1 [s, ν (C=O)] cm–1 1H NMR (500 MHz,
.
˜
s
1
CDCl3): δ = 10.17 (s, 1 H, -CHO), 8.42 (d, J = 13.0 Hz, 5 H), 8.32
(s, 1 H), 8.23–8.15 (m, 10 H), 7.91 (d, J = 8.0 Hz, 2 H), 7.76 (d, J
= 9.0 Hz, 1 H), 7.70–7.58 (m, 13 H), 7.55–7.49 (m, 14 H), 7.43–
7.36 (m, 12 H), 7.30–7.28 (m, 3 H) ppm. MS (MALDI-TOF): m/z
= 1426.9. C103H62N8O (1427.65): calcd. C 86.65, H 4.38, N 7.85;
found C 86.59, H 4.44, N 7.81.
3:1) to afford 18 (7.3 g, 90%) as a white solid. M.p. Ͼ250 °C. H
NMR (500 MHz, CDCl3): δ = 8.42–8.41 (m, 4 H), 8.32–8.29 (m, 2
H), 8.21–8.09 (m, 8 H), 7.68–7.63 (m, 11 H), 7.51–7.36 (m, 18 H),
7.35–7.29 (m, 8 H) ppm. MS (MALDI-TOF): m/z = 1157.7.
C84H51N7 (1158.35): calcd. C 87.10, H 4.44, N 8.46; found C 87.33,
H 4.54, N 8.53.
4-(3-{3-[3-(3-{3-[3-(9H-Carbazol-9-yl)-9H-carbazol-9-yl]-9H-carb-
azol-9-yl}-9H-carbazol-9-yl)-9H-carbazol-9-yl]-9H-carbazol-9-yl}-
9H-carbazol-9-yl)benzaldehyde (13): Compound 18 (7.0 g,
6.0 mmol), 4-iodobenzaldehyde (4.0 g, 17 mmol), Cu2O (2.5 g,
17 mmol), and DMAc (20 mL) were added sequentially into a seal
tube under a nitrogen atmosphere and heated to 180 °C in oil bath
for 18 h. Then, the mixture was cooled to room temperature and
filtered. The filtrate was poured into H2O (300 mL) and stirred for
9-(9-Butyl-9H-carbazol-3-yl)-9H-carbazole (23): To a solution of
compound 21 (1.4 g, 4.3 mmol) in DMF (30 mL) was added NaH
(60 wt.-%, 0.25 g, 6.3 mmol) and n-C4H9Br (4.6 mL, 4.3 mmol).
The mixture was stirred at room temperature until the reaction was
complete, as monitored by TLC. The mixture was poured into
water (200 mL), and the precipitate was collected by filtration and
recrystallized from petroleum ether to give 23 (1.5 g, 90%) as a
1
white solid. M.p. 144.0–146.0 °C. H NMR (500 MHz, CDCl3): δ
Eur. J. Org. Chem. 2009, 53–60
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X. Liu, R. Lu, T. Xu, D. Xu, Y. Zhan, P. Chen, X. Qiu, Y. Zhao
FULL PAPER
= 8.22 (s, 1 H), 8.17 (d, J = 8.0 Hz, 2 H), 8.04 (d, J = 5.5 Hz, 1
H), 7.56 (s, 2 H), 7.50–7.45 (m, 2 H), 7.41–7.38 (m, 4 H), 7.29–7.27
(m, 2 H), 7.25–7.21 (m, 1 H), 4.37–4.34 (m, 2 H), 1.95–1.89 (m, 2
H), 1.49–1.44 (m, 2 H), 1.01–0.98 (t, 3 H) ppm.
C
141H85BN12O (1974.07): calcd. C 85.79, H 4.34, N 8.51; found C
86.04, H 4.42, N 8.27.
T(OCA4)SubP (3): By following the synthetic procedure for com-
pound 2 and by using pyridine-tri-N-pyrrolylborane (300 mg,
1.04 mmol) and OCA4-CHO (10; 2.4 g, 3.13 mmol) as reagents in
o-dichlorobenzene (45 mL), the mixture was stirred at 0 °C for 6 h
under an atmosphere of nitrogen in the dark. The crude product
was purified by chromatography (silica gel, CH2Cl2) twice to give
9-{9-[9-(9-Butyl-9H-carbazol-3-yl)-9H-carbazol-3-yl]-9H-carbazol-
3-yl}-9H-carbazole (24): The synthesis of compound 24 from 22
was similar to that of 23 from 21. After purification by column
chromatography (silica gel; petroleum ether/ethyl acetate, 10:1), 24
(2.6 g, 85%) was obtained as a white solid. M.p. 214.0–216.0 °C.
1H NMR (500 MHz, CDCl3): δ = 8.40 (s, 1 H), 8.33–8.32 (m, 2
3 (103 mg, 4.0%) as a brown-orange solid. M.p. Ͼ250 °C. IR
(KBr): ν = 3420 [s, ν (OH)] cm–1. H NMR (500 MHz, CDCl ): δ
1
˜
s
3
H), 8.19–8.10 (m, 5 H), 7.67–7.59 (m, 5 H), 7.55–7.41 (m, 11 H), = 8.48–8.42 (m, 15 H), 8.33 (s, 3 H), 8.27–8.10 (m, 21 H), 8.00 (d,
7.34–7.28 (m, 5 H), 4.44–4.41 (m, 2 H), 2.00–1.95 (m, 2 H), 1.51–
1.48 (m, 2 H), 1.04–1.01 (t, 3 H) ppm.
J = 8.5 Hz, 3 H), 7.83–7.77 (m, 6 H), 7.70–7.61 (m, 12 H), 7.56–
7.50 (m, 15 H), 7.46–7.38 (m, 21 H), 7.34–7.28 (m, 9 H) ppm. 13C
NMR (75 MHz, CDCl3): δ = 142.6, 141.9, 141.6, 141.2, 141.1,
140.5, 140.1, 137.4, 136.6, 134.7, 129.8, 129.5, 129.3, 127.3, 127.1,
126.8, 126.6, 125.8, 125.6, 125.4, 124.9, 124.2, 124.0, 123.2, 123.1,
122.8, 122.7, 120.9, 120.7, 120.6, 120.3, 120.0, 119.7, 119.6, 119.5,
111.3, 111.0, 110.9, 110.3, 109.8 ppm. MS (MALDI-TOF): m/z =
2451.8 [M – OH]+. C177H106BN15O (2469.65): calcd. C 86.08, H
4.33, N 8.51; found C 86.11, H 4.40, N 8.62.
9-[9-(9-{9-[9-(9-Butyl-9H-carbazol-3-yl)-9H-carbazol-3-yl]-9H-
carbazol-3-yl}-9H-carbazol-3-yl)-9H-carbazol-3-yl]-9H-carbazole (25):
The synthesis of compound 25 from 16 was similar to that of 23
from 21. After purification by column chromatography (silica gel;
petroleum ether/ethyl acetate, 10:1), 25 (3.8 g, 82%) was obtained
1
as a white solid. M.p. Ͼ250 °C. H NMR (500 MHz, CDCl3): δ =
8.42–8.40 (m, 3 H), 8.33 (d, J = 8.5 Hz, 2 H), 8.20–8.10 (m, 7 H),
7.67–7.62 (m, 9 H), 7.54–7.42 (m, 15 H), 7.36–7.28 (m, 7 H), 4.44–
4.42 (m, 2 H), 1.99–1.96 (m, 2 H), 1.53–1.48 (m, 2 H), 1.04–1.01
(t, 3 H) ppm.
T(OCA5)SubP (4): By following the synthetic procedure for com-
pound 1 and by using pyridine-tri-N-pyrrolylborane (300 mg,
1.04 mmol) and OCA5-CHO (11; 2.9 g, 3.11 mmol) as reagents in
o-dichlorobenzene (45 mL), the mixture was stirred at 0 °C for 8 h
under an atmosphere of nitrogen in the dark. The subsequent oxi-
dation reaction was carried out in the open air under reflux for
2.5 h. The crude product was purified by chromatography (silica
gel, CH2Cl2) twice to give 4 (92 mg, 3.0%) as a brown-orange solid.
T(OCA2)SubP (1): To a suspension of pyridine-tri-N-pyrrolylbor-
ane (300 mg, 1.04 mmol) in o-dichlorobenzene (45 mL) was added
OCA2-CHO (8; 1.4 g, 3.21 mmol), and the mixture was cooled to
0 °C in an ice bath. After adding trifluoroacetic acid (0.085 mL,
1.10 mmol) dropwise by syringe, the mixture immediately turned
deep red from light-yellow. After stirring at 0 °C for 3 h under an
atmosphere of nitrogen in the dark, the reaction was quenched with
pyridine (0.1 mL), and the resulting solution was heated to reflux
in the open air for 1.5 h. Black tar was obtained after the solvent
was removed by distilling, which was purified by chromatography
(silica gel, CH2Cl2) twice to give 1 (75 mg, 4.9%) as a brown-orange
M.p. Ͼ250 °C. IR (KBr): ν = 3430 [s, ν (OH)] cm–1. 1H NMR
˜
s
(500 MHz, CDCl3): δ = 8.49–8.42 (m, 15 H), 8.32 (s, 3 H), 8.28–
8.11 (m, 24 H), 8.00 (d, J = 8.0 Hz, 3 H), 7.84–7.77 (m, 6 H), 7.72–
7.60 (m, 21 H), 7.54–7.42 (m, 48 H), 7.29 (s, 6 H) ppm. 13C NMR
(75 MHz, CDCl3): δ = 142.7, 142.0, 141.6, 141.3, 141.1, 140.5,
137.5, 136.6, 134.6, 129.9, 129.6, 129.2, 127.3, 127.1, 126.8, 126.7,
126.5, 125.8, 125.6, 125.4, 124.9, 124.3, 124.2, 124.0, 123.2, 123.1,
122.7, 120.9, 120.8, 120.6, 120.2, 120.0, 119.6, 119.5, 111.1, 110.9,
110.3, 109.8 ppm. MS (MALDI-TOF): m/z = 2946.8 [M – OH]+.
C213H127BN18O (2965.22): calcd. C 86.28, H 4.32, N 8.50; found C
86.18, H 4.41, N 8.43.
solid. M.p. Ͼ250 °C. IR (KBr): ν = 3420 [s, ν (OH)] cm–1. 1H NMR
˜
s
(500 MHz, CDCl3): δ = 8.44–8.38 (m, 15 H), 8.22–8.20 (m, 9 H),
8.08 (d, J = 8.5 Hz, 6 H), 7.93 (d, J = 9.0 Hz, 3 H), 7.81 (d, J =
8.0 Hz, 3 H), 7.69–7.67 (m, 3 H), 7.62–7.59 (t, 3 H), 7.48–7.40 (m,
15 H), 7.34–7.31 (t, 6 H) ppm. 13C NMR (75 MHz, CDCl3): δ =
141.8, 141.4, 140.4, 139.8, 137.4, 136.4, 134.6, 130.2, 127.2, 126.9,
125.9, 125.7, 124.7, 123.2, 123.1, 122.7, 120.8, 120.3, 119.6, 111.1,
110.3, 109.8 ppm. MS (MALDI-TOF): m/z = 1461.3 [M – OH]+.
T(OCA6)SubP (5): By following the synthetic procedure for com-
pound 1 and by using pyridine-tri-N-pyrrolylborane (300 mg,
1.04 mmol) and OCA6-CHO (12; 3.5 g, 3.20 mmol) as reagents in
o-dichlorobenzene (45 mL), the mixture was stirred at 0 °C for 11 h
under an atmosphere of nitrogen in the dark. The subsequent oxi-
dation reaction was carried out in the open air under reflux for
3.5 h. The crude product was purified by chromatography (silica
gel, CH2Cl2) twice to give 5 (92 mg, 2.5%) as a brown-orange solid.
C105H64BN9O (1478.50): calcd. C 85.30, H 4.36, N 8.53; found C
85.22, H 4.45, N 8.47.
T(OCA3)SubP (2): By following the synthetic procedure for com-
pound 1 and by using pyridine-tri-N-pyrrolylborane (300 mg,
1.04 mmol) and OCA3-CHO (9; 1.9 g, 3.16 mmol) as reagents in
o-dichlorobenzene (45 mL), the mixture was stirred at 0 °C for 4 h
under an atmosphere of nitrogen in the dark. The subsequent oxi-
dation reaction was carried out in the open air under reflux for
2 h. The crude product was purified by chromatography (silica gel,
CH2Cl2) twice to give 2 (90 mg, 4.3%) as a brown-orange solid.
M.p. Ͼ250 °C. IR (KBr): ν = 3430 [s, ν (OH)] cm–1. 1H NMR
˜
s
(500 MHz, CDCl3): δ = 8.48–8.40 (m, 21 H), 8.31 (s, 3 H), 8.27–
8.10 (m, 27 H), 8.00 (d, J = 8.5 Hz, 3 H), 7.83–7.77 (m, 6 H), 7.70–
7.61 (m, 24 H), 7.55–7.48 (m, 30 H), 7.42–7.28 (m, 33 H) ppm. 13
C
NMR (75 MHz, CDCl3): δ = 142.8, 142.7, 142.0, 141.7, 141.4,
141.2, 140.6, 140.2, 137.5, 136.7, 134.7, 129.9, 129.6, 129.3, 127.3,
127.1, 126.7, 126.6, 125.8, 125.6, 125.5, 125.0, 124.3, 124.2, 124.1,
123.3, 123.1, 122.7, 121.0, 120.9, 120.6, 120.3, 120.2, 120.0, 119.5,
111.2, 111.0, 110.4, 109.9 ppm. MS (MALDI-TOF): m/z = 3441.2
[M – OH]+. C249H148BN21O (3460.79): calcd. C 86.42, H 4.31, N
8.50; found C 86.47, H 4.38, N 8.47.
M.p. Ͼ250 °C. IR (KBr): ν = 3425 [s, ν (OH)] cm–1. 1H NMR
˜
s
(500 MHz, CDCl3): δ = 8.46–8.42 (m, 12 H), 8.35 (s, 3 H), 8.26–
8.17 (m, 12 H), 8.11 (d, J = 8.0 Hz, 6 H), 7.98 (d, J = 8.5 Hz, 3
H), 7.82 (d, J = 8.5 Hz, 3 H), 7.77–7.75 (m, 3 H), 7.66–7.57 (m, 12
H), 7.52–7.51 (m, 6 H), 7.47–7.43 (m, 15 H), 7.36–7.31 (m, 9 H)
ppm. 13C NMR (75 MHz, CDCl3): δ = 142.5, 141.9, 141.5, 141.0,
140.4, 140.0, 137.4, 136.5, 134.6, 129.9, 129.6, 127.2, 127.0, 126.6,
125.8, 125.6, 125.5, 124.8, 124.1, 123.2, 123.0, 122.8, 122.7, 120.9,
120.6, 120.3, 120.1, 119.7, 119.6, 119.5, 111.2, 110.9, 110.4, 110.2,
109.8 ppm. MS (MALDI-TOF): m/z = 1956.6 [M – OH]+.
T(OCA7)SubP (6): By following the synthetic procedure for com-
pound 1 and by using pyridine-tri-N-pyrrolylborane (300 mg,
1.04 mmol) and OCA7-CHO (13; 3.9 g, 3.09 mmol) as reagents in
o-dichlorobenzene (45 mL), the mixture was stirred at 0 °C for 14 h
58
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Eur. J. Org. Chem. 2009, 53–60

Subporphyrins with Monodisperse Oligocarbazole Arms
[6]
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Spain), Spanish Patent ES 200401615, 2005.
under an atmosphere of nitrogen in the dark. The subsequent oxi-
dation reaction was carried out in the open air under reflux for
5 h. The crude product was purified by chromatography (silica gel,
CH2Cl2) twice and washed with ethyl acetate to give 6 (92 mg,
2.2%) as a brown-orange solid. M.p. Ͼ250 °C. IR (KBr): ν = 3415
˜
1
[s, νs(OH)] cm–1. H NMR (500 MHz, CDCl3): δ = 8.48–8.40 (m,
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Jung, ChemPhysChem 2002, 3, 881–885.
a) C. G. Claessens, D. González-Rodríguez, T. Torres, G.
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21 H), 8.31 (s, 3 H), 8.25–8.10 (m, 30 H), 8.00 (d, J = 8.5 Hz, 3
H), 7.83–7.76 (m, 6 H), 7.67–7.59 (m, 30 H), 7.54–7.28 (m, 75 H)
ppm. MS (MALDI-TOF): m/z
285H169BN24O (3956.36): calcd. C 86.52, H 4.31, N 8.50; found C
86.39, H 4.41, N 8.32.
=
3936.2 [M
–
OH]+.
C
T(OCA8)SubP (7): By following the synthetic procedure for com-
pound 1 and by using pyridine-tri-N-pyrrolylborane (300 mg,
1.04 mmol) and OCA8-CHO (14; 4.5 g, 3.15 mmol) as reagents in
o-dichlorobenzene (45 mL), the mixture was stirred at 0 °C for 18 h
under an atmosphere of nitrogen in the dark. The subsequent oxi-
dation reaction was carried out in the open air under reflux for
6 h. The crude product was purified by chromatography (silica gel,
CH2Cl2) twice and washed with ethyl acetate to give 7 (83 mg,
[9]
1.8%) as a brown-orange solid. M.p. Ͼ250 °C. IR (KBr): ν = 3430
˜
1
[s, νs(OH)] cm–1. H NMR (500 MHz, CDCl3): δ = 8.48–8.39 (m,
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7.42–7.35 (m, 39 H) ppm. MS (MALDI-TOF): m/z = 4433.0 [M –
OH]+. C321H190BN27O (4451.93): calcd. C 86.60, H 4.30, N 8.49;
found C 86.42, H 4.48, N 8.73.
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Supporting Information (see footnote on the first page of this arti-
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absorption and excitation curves; 1H and 13C NMR spectra and
mass spectrometry data for all new compounds.
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Received: July 1, 2008
Published Online: November 28, 2008
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Eur. J. Org. Chem. 2009, 53–60