Synthesis of BODIPY-appended subporphyrins

Article abstract of DOI:10.1002/ejoc.201001188

BODIPY-subporphyrin hybrids bridged by a 1,4-biphenylene or 1,4-diphenylethynylene spacer were synthesized either by the palladium-catalyzed Suzuki-Miyaura reaction or the Sonogashira reaction. Their structural and optical properties were examined with re

Full text of DOI:10.1002/ejoc.201001188

FULL PAPER
DOI: 10.1002/ejoc.201001188
Synthesis of BODIPY-Appended Subporphyrins
Hisashi Sugimoto,[a] Masahiro Muto,[a] Takayuki Tanaka,[a] and Atsuhiro Osuka*[a]
Keywords: Porphyrinoids / Cross-coupling / Fluorescence / Palladium
BODIPY–subporphyrin hybrids bridged by a 1,4-biphenyl-
ene or 1,4-diphenylethynylene spacer were synthesized
either by the palladium-catalyzed Suzuki–Miyaura reaction
or the Sonogashira reaction. Their structural and optical
properties were examined with respect to the bridge and
BODIPY structures. In all cases, intramolecular excitation
energy transfer from the subporphyrin core to the BODIPY
peripheries is efficient. Depending on the presence or ab-
sence of β-methyl groups adjacent to the meso position of
the BODIPY subunit, the fluorescence is either increased or
decreased. It was also found that the electronic interaction
between the subporphyrin core and the meso-(1,4-phenyl-
ene) substituents causes spectral changes for the subpor-
phyrin part, which is not observed for porphyrin counterparts.
ponents of an energy-transfer cassette.[7,8] In fact, there are
many reports on the utilization of BODIPY as an element
of artificial light-harvesting systems, in which light energy
Introduction
Since the first report on tribenzosubporphines in 2006,[1]
the chemistry of subporphyrins has been actively studied
because of their attractive attributes, which include their
bowl-shaped structure, 14π-aromatic system, intense green
fluorescence, and boron-chelated supramolecular as-
sembly.[2–5] Compared with porphyrins, meso-aryl substitu-
ents of subporphyrins have a smaller rotation barrier, which
leads to large effects on the electronic and optical properties
of subporphyrins. Such unique features have allowed the
exploitation of novel functionalized chromophores based
on subporphyrins. For example, meso-oligo(1,4-phenylene-
ethynylene)-substituted subporphyrins display redshifted
and intensified absorption bands and enhanced fluores-
cence as a consequence of the extension of the π-conjuga-
tion network,[3b] and 4-(N,N-dialkylamino)phenyl-substi-
tuted subporphyrins exhibit considerably perturbed absorp-
tion and fluorescence spectra owing to intramolecular
charge-transfer interactions.[3c] Despite these recent efforts,
the chemistry of subporphyrins still remains at the rudimen-
tary stage, and the exploration of subporphyrins that hold
novel functions and intriguing properties is desirable.
4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (boron di-
pyrromethene, BODIPY) is a useful pigment with remark-
able optical properties such as strong and sharp absorption
bands, tunable fluorescence intensity, and photochemical
stability.[6] Some BODIPYs are known for their very bright
fluorescence with almost quantitative quantum yield and
have been used as biochemical labeling reagents and com-
[a] Department of Chemistry, Graduate School of Science,
Kyoto University,
Sakyo-ku, Kyoto 606-8502, Japan
Fax: +81-75-753-3970
E-mail: osuka@kuchem.kyoto-u.ac.jp
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201001188.
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H. Sugimoto, M. Muto, T. Tanaka, A. Osuka
FULL PAPER
is efficiently collected and migrated from a donor part to bridged subporphyrin–BODIPY hybrids was achieved in a
an acceptor part. Along this line, BODIPY has been em- stepwise manner. Subporphyrin 5 was converted into meso-
ployed as an effective energy donor toward porphyrin.[7b,7e] tris(4-ethynylphenyl)subporphyrin 10 by Sonogashira cou-
Recently, hexaphyrin–BODIPY hybrids were prepared, in pling between 5 and trimethylsilylacetylene followed by de-
which the energy transfer from BODIPY to [26]hexaphyrin protection with tetrabutylammonium fluoride.[3b] Subse-
or [28]hexaphyrin proceeds efficiently.[8]
quent Sonogashira coupling of 10 with meso-(4-iodo-
With this background, it occurred to us that covalently phenyl)-substituted BODIPYs 11 and 12 provided subpor-
linked subporphyrin–BODIPY might be an interesting tar- phyrin–BODIPY hybrids 3 and 4 in 70 and 73% yield, re-
1
get, in that (1) the fluorescence of subporphyrins (500– spectively.[6e] The H NMR spectra of both 3 and 4 are in
600 nm) overlaps well with the absorption band of line with their structures (see the Supporting Information).
Single crystals of 1 suitable for X-ray diffraction analysis
were obtained by slow vapor diffusion of ethanol into its
dichlorobenzene solution. The crystal structure shows C3
symmetry (Figure 1). In the solid state, the dihedral angles
between the plane defined by neighboring Cα–Cmeso–Cα
atoms and adjacent phenylene spacers are relatively small
(43.7, 44.7, and 44.9°), which is in line with previous stud-
ies.[3a] These stereochemical features are expected to allow
strong electronic interaction between the subporphyrin core
and the meso substituents. On the other hand, the BODIPY
units and phenylene spacers are almost perpendicular (81.6,
84.8, and 85.8°) due to the steric hindrance imposed by the
β-methyl groups adjacent to the meso position, which is un-
favorable for the electronic interaction between the subpor-
phyrin core and the BODIPY ends. The B–B distance is
about 16 Å, and the bowl depth, which is defined by the
distance between the central boron atom and the mean
plane of the peripheral six β-carbon atoms, is 1.28 Å.
Figure 2 shows the UV/Vis absorption and fluorescence
BODIPY, which is an important requirement for effective
excitation energy transfer, and that (2) the conjugative com-
bination of subporphyrin and BODIPY might lead to even
more fluorescent molecular systems. Here we wish to report
the synthesis of 1,4-biphenylene- and 1,4-diphenylethyny-
lene-bridged subporphyrin–BODIPY hybrids 1–4 and their
optical and electrochemical properties.
Results and Discussion
Scheme 1 outlines the synthetic routes to subporphyrin–
BODIPY hybrids 1–4. meso-Tris(4-bromophenyl)subpor-
phyrin 5[4a] and meso-4-bromophenyl BODIPYs 6 and 7[6e]
were prepared by reported methods. Borylated BODIPYs 8
and 9 were prepared by reaction of 6 and 7 with bis-
(pinacolato)diboron in the presence of a Pd catalyst
(20 mol-%). Suzuki–Miyaura coupling of subporphyrin 5
with borylated BODIPYs 8 and 9 afforded hybrids 1 and 2
1
in 59 and 62% yield, respectively. The H NMR spectra of
both 1 and 2 exhibit a singlet due to the β-protons at δ = spectra of 1–4 along with those of relevant reference mole-
8.23 ppm and at δ = 8.26 ppm, respectively, and a single set cules. Subporphyrins 1 and 2 exhibit Soret-like bands at
of signals due to the meso substituent groups in accord with nearly the same positions, 383 and 382 nm, respectively,
1
their C3 symmetric structures. These H NMR spectra also both of which are clearly redshifted in comparison to that
indicate free rotation of the meso substituents in 1 and 2 at (373 nm) of meso-triphenylsubporphyrin 13 (Figure 4). The
room temperature. The synthesis of 1,4-diphenylethynylene- Soret-like band of 2 is broader than that of 1. In order to
Scheme 1. Synthesis of subporphyrin–BODIPY hybrids 1–4.
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Synthesis of BODIPY-Appended Subporphyrins
in the order 13 (ΦF = 0.14) Ͻ 14 (ΦF = 0.26) Ͻ 15 (ΦF
=
0.34), probably as a reflection of the increasing size of the
effective radiative chromophore.[3b,9] The observed effects
of the meso-(4-biphenyl) and meso-(4-terphenyl) substitu-
ents are quite unique for subporphyrin chromophores, as
such redshifts and increasing fluorescence quantum yields
have never been observed for porphyrin counterparts.[10]
Figure 1. X-ray crystal structure of 1: (a) top view and (b) side view.
Thermal ellipsoids are scaled to 50% probability. Hydrogen atoms
are omitted for clarity.
examine the electronic influences of the 4-biphenyl substitu-
ents at the meso positions, we prepared meso-tris(4-bi-
phenyl)-substituted subporphyrin 14 by Suzuki–Miyaura
coupling of 5 with pinacolatoboryl benzene in 71% yield
(Scheme 2). The X-ray crystal structure of 14 is shown in
Figure 3. The Soret-like band of 14 is observed at 382 nm,
Figure 2. UV/Vis absorption (solid lines) and fluorescence (dashed
lines) spectra of (a) 1, 2, 13, 14, and 15; (b) 3, 4, 13, and 16 in
CH2Cl2.
The observed broadening of the Soret-like band of 2 may
which is quite similar to those of 1 and 2. These data indi- be ascribed to the conformational distribution of the BOD-
cate that the redshifts of 1 and 2 stem from the electronic IPY edges that arises from the small steric constraint for
interaction of the meso-(4-biphenyl) substituents with the their rotation. Subporphyrins 3 and 4 exhibit Soret-like
subporphyrin core; the BODIPY edges play only a marginal bands at 389 and 390 nm, which are similar to that
effect. Next, we prepared meso-tris(4-terphenyl)-substituted (388 nm) of meso-tris(phenylethynylphenyl)-substituted
subporphyrin 15 in 77% yield through a similar coupling subporphyrin 16. Similar to 2, the Soret-like band of 4 is
reaction, which displays a Soret-like band at 385 nm. Inter- slightly broader than that of 3. A small electronic interac-
estingly, the fluorescence quantum yield distinctly increases tion of the subporphyrin and BODIPY can be also seen
Scheme 2. Synthesis of subporphyrins 14 and 15.
Eur. J. Org. Chem. 2011, 71–77
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73

H. Sugimoto, M. Muto, T. Tanaka, A. Osuka
FULL PAPER
Figure 3. X-ray crystal structure of 14: (a) top view and (b) side view. Thermal ellipsoids are scaled to 50% probability. Hydrogen atoms
are omitted for clarity.
from the absorption bands of BODIPY, which show almost Table 1. Optical properties of 1–4 and 13–16.
no shift as compared to those of meso-phenyl BODIPYs 17
Compd.
Absorption
λmax / nm
Fluorescence
ΦF
and 18 at 501 and 511 nm, respectively. The UV/Vis absorp-
tion spectra of 1–4 can be almost reproduced by linear com-
binations of the corresponding meso-oligo(1,4-phenylene)-
substituted subporphyrin and BODIPY fragments, indicat-
ing that the electronic interaction in the ground state is
weak.
Table 1 summarizes the optical properties. The fluores-
cence spectra of 1–4 show emissions from the BODIPY seg-
ments, independent of the excitation wavelength either
around 380 nm (subporphyrin) or around 500 nm
(BODIPY), indicating an efficient excitation energy transfer
from the subporphyrin core to the BODIPY segment.[11,12]
Mitigated but clear fluorescence is observed for 1 and 3 (ΦF
= 0.20 and 0.29 for the excitation at BODIPY part),
whereas the fluorescence is strongly quenched in 2 and 4;
in both cases, ΦF Ͻ 0.1%. The latter feature may arise from
the intrinsic small quantum yield of meso-phenyl-1,7-di-
λex / nm λmax / nm
(ε / 105 m–1 cm–1)
1
2
3
4
383 (2.11)
501 (2.50)
382 (1.45)
512 (1.80)
389 (1.56)
502 (1.87)
390 (1.38)
513 (1.63)
373 (1.66)
382 (1.94)
385 (2.23)
388 (2.11)
383
501
382
512
389
502
390
513
373
382
385
388
548
548
530
530
548
548
535
535
516
548
548
554
0.23
0.20
0.01
0.01
0.36
0.29
0.01
0.01
0.14
0.26
0.34
0.29
13
14
15
16
Conclusions
BODIPY-appended subporphyrins 1–4 were prepared by
methyl BODIPY 17 (ΦF = 0.19) as compared to that of Suzuki–Miyaura reaction or Sonogashira reaction. Al-
meso-phenyl-1,3,5,7-tetramethyl BODIPY 18 (ΦF = 0.65; though the intramolecular excitation energy transfer pre-
Figure 4).[13] Fluorescence quantum yields of hybrids 1–4 vails in the singlet excited states of 1–4, the fluorescence
are reduced in comparison to those of 17 and 18. Reasons quantum yields of 1 and 3 are enhanced, whereas those of
for these phenomena are not clear at the present stage, but 2 and 4 are significantly decreased as compared to that of
might be due to efficient intramolecular electron-transfer or reference subporphyrin 13. These trends can be understood
charge-transfer interaction.
in terms of the intrinsic optical properties of reference
Figure 4. Reference molecules triphenylsubporphyrin 13, meso-tris(phenylethynyphenyl)subporphyrin 16, meso-phenyl-1,7-dimethyl
BODIPY 17, and meso-phenyl 1,3,5,7-tetramethyl BODIPY 18.
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Synthesis of BODIPY-Appended Subporphyrins
(233 mg, 920 μmol), Pd(dppf)Cl2·CH2Cl2 (32 mg, 40 μmol), KOAc
(393 mg, 4.00 mmol), toluene (3.3 mL), and H2O (0.7 mL). The re-
sulting solution was deoxygenated through three freeze–pump–
thaw cycles and then stirred at 100 °C for 24 h under a N2 atmo-
sphere. After the mixture was passed through a short Celite pad,
the eluent was diluted with CH2Cl2 (50 mL). The resulting solution
was washed with water and brine, and the solvents were evaporated
to dryness. The product was separated through a silica gel column
(CH2Cl2/hexane, 1:1) and recrystallized (CH2Cl2/hexane) to give 9
(92.2 mg, 55% yield) as a red powder. 1H NMR (600 MHz,
CDCl3): δ = 7.91 (d, J = 7.8 Hz, 2 H, Ar-H), 7.49 (d, J = 8.4 Hz,
2 H, Ar-H), 6.69 (d, J = 4.2 Hz, 2 H, BODIPY-H), 6.26 (d, J =
4.2 Hz, 2 H, BODIPY-H), 2.65 (s, 6 H, Me), 1.38 (s, 12 H, pinacol-
ato Me) ppm. 13C NMR (150 MHz, CDCl3): δ = 157.7, 142.4,
136.7, 134.4, 130.4, 129.7, 119.4, 84.2, 24.9, 14.9, 1.0 ppm. MS
(MALDI-TOF+): m/z = 420.80 (calcd. for C23H26N2B1F2O2 422.08
[M]+). UV/Vis (CH2Cl2): λ = 339, 512 nm. Fluorescence (CH2Cl2):
λex = 512 nm, λmax = 532 nm.
BODIPYs 17 and 18. meso-1,4-Oligophenylene substituents
influence the optical properties of subporphyrins through
conjugative interactions. Exploration of novel subporphyr-
in-based molecular systems is actively in progress in our
laboratory.
Experimental Section
General: All reagents were of the commercial reagent grade and
were used without further purification except where noted. Spectro-
scopic-grade dichloromethane was used as solvent for all spectro-
scopic studies. Silica gel column chromatography was performed
on Wakogel C-200 and C-300. Thin-layer chromatography (TLC)
was carried out on aluminum sheets coated with silica gel 60 F254
(Merck 5554). UV/Vis absorption spectra were recorded with Shim-
adzu UV-3100PC and Shimadzu UV2550 spectrometers. Fluores-
cence spectra were recorded with a Shimadzu RF-5300PC spec-
trometer. Absolute fluorescence quantum yields were determined
with a Hamamatsu C9920–02S. 1H, 11B, and 13C NMR spectra
were recorded with a JEOL ECA-600 spectrometer (operating as
600.17 MHz for 1H, 193 MHz for 11B, and 151 MHz for 13C) by
using the residual solvent as the internal reference for 1H (δ =
7.26 ppm in CDCl3), BF3·Et2O as the external reference for 11B (δ
= 0.00 ppm in CDCl3), and residual solvent as the internal refer-
ence for 13C (δ = 77.16 ppm in CDCl3). High-resolution electro-
spray-ionization time-of-flight mass spectroscopy [HRMS (ESI-
TOF)] was recorded with a Bruker microTOF model by using the
positive mode for acetonitrile solutions of samples. Mass spectra
were recorded with a Bruker microflex-KR by using the positive-
MALDI-TOF method with matrix. Crystallographic data were col-
lected with a Rigaku RAXIS–RAPID apparatus at –150 °C by
using graphite-monochromated Mo-Kα radiation (λ = 0.71069 Å)
or a Bruker-Apex X-ray diffractometer equipped with a large area
CCD detector at –183 °C. The structures were solved by direct
methods (SIR97 or SHELXS-97) and refined with full-matrix least
square technique (SHELXL-97). In the event of solvent molecules
not being adequately modeled, core molecule 1 was refined without
the solvent molecules by a combination of the SHELX-97 and
PLATON SQUEEZE programs.[12]
BODIPY-Appended Subporphyrin 1: A 10-mL Schlenk tube was
charged with 5,10,15-tris(4-bromophenyl)subporphyrin 5 (30.0 mg,
40.6 μmol), BODIPY 8 (60.3 mg, 134 μmol), Pd(dppf)Cl2·CH2Cl2
(6.6 mg, 8.12 μmol), K2CO3 (185 mg, 1.34 mmol), toluene (2 mL),
and H2O (0.4 mL). The resulting solution was deoxygenated
through three freeze–pump–thaw cycles and then stirred at 100 °C
for 4 d under a N2 atmosphere. After the mixture was passed
through a short Celite pad, the eluent was diluted with CH2Cl2
(50 mL). The resulting solution was washed with water and brine,
and the solvents were evaporated to dryness. To the residual solid,
a mixture of CH2Cl2/MeOH (1:1, 50 mL) was added, and the solu-
tion was heated at 50 °C for 10 min. The product was separated
through a silica gel column (CH2Cl2/hexane/ether, 1:2:1) and
recrystallized (CH2Cl2/MeOH) to give 1 (35.0 mg, 23.8 μmol, 59%
yield) as an orange powder. 1H NMR (600 MHz, CDCl3): δ = 8.23
(s, 6 H, β-H), 8.22 (d, J = 7.2 Hz, 6 H, Ar-H), 8.06 (d, J = 7.8 Hz,
6 H, Ar-H), 7.98 (d, J = 7.8 Hz, 6 H, Ar-H), 7.48 (d, J = 8.4 Hz,
6 H, Ar-H), 6.04 (s, 6 H, BODIPY-H), 2.60 (s, 18 H, Me), 1.53 (s,
18 H, Me), 0.92 (s, 3 H, OMe) ppm. 11B NMR (193 MHz, CDCl3):
δ = 0.79 (t, J = 33.9 Hz, 3 B, BODIPY), –15.15 (s, 1 B, subpor-
phyrin) ppm. 13C NMR (150 MHz, CDCl3): δ = 155.9, 143.3,
141.6, 141.2, 141.2, 140.0, 137, 134.7, 134.0, 132.0, 129.0, 128.0,
127.5, 122.6, 121.5, 120.3, 53.6, 47.1, 14.8 ppm. HRMS (ESI-
TOF+): m/z = 1436.6283 (calcd. for C90H72B4F6N9 1436.6225 [M –
OMe]+). UV/Vis (CH2Cl2): λ (ε, m–1 cm–1) = 383 (211000), 501
(38600) nm. Fluorescence (CH2Cl2) λex = 383 nm, λmax = 548 nm,
ΦF = 0.225, λex = 501 nm, λmax = 548 nm, ΦF = 0.202.
Pinacolatoboryl BODIPY 8: A 20-mL Schlenk tube was charged
with BODIPY
6 (171 mg, 424 μmol), bis(pinacolato)diboron
(215 mg, 848 μmol), Pd(dppf)Cl2·CH2Cl2 (35 mg, 85 μmol), KOAc
(416 mg, 4.24 mmol), toluene (5 mL), and H2O (1 mL). The re-
sulting solution was deoxygenated through three freeze–pump–
thaw cycles and then stirred at 100 °C for 24 h under a N2 atmo-
sphere. After being passed through a short Celite pad, the eluent
was diluted with CH2Cl2 (50 mL). The resulting solution was
washed with water and saturated NaCl aqueous solution, and the
solvents were evaporated to dryness. The product was separated
through a silica gel column (CH2Cl2/hexane, 1:1) and recrystallized
(CH2Cl2/hexane) to give 8 (132 mg, 69% yield) as a red powder.
1H NMR (600 MHz, CDCl3): δ = 7.90 (d, J = 7.8 Hz, 2 H, Ar-H),
7.29 (d, J = 7.8 Hz, 2 H, Ar-H), 5.97 (s, 2 H, BODIPY-H), 2.55 (s,
6 H, Me), 1.39 (s, 12 H, pinacolato Me), 1.37 (s, 6 H, Me) ppm.
13C NMR (150 MHz, CDCl3): δ = 155.5, 143.2, 141.7, 137.9, 135.4,
131.3, 127.4, 121.2, 84.1, 25.0, 14.5, 14.4 ppm. MS (MALDI-
TOF+): m/z = 449.02 (calcd. for C25H30N2B1F2O2 450.14 [M]+).
UV/Vis (CH2Cl2): λ = 315, 364, 501 nm. Fluorescence (CH2Cl2) λex
= 501 nm, λmax = 511 nm.
BODIPY-Appended Subporphyrin 2: A 10-mL Schlenk tube was
charged with 5,10,15-tris(4-bromophenyl)subporphyrin 5 (10.0 mg,
13.5 μmol), BODIPY 9(18.8 mg, 44.6 μmol), Pd(dppf)Cl2·CH2Cl2
(2.2 mg, 2.70 μmol), K2CO3 (61.6 mg, 446 μmol), toluene (0.8 mL),
and H2O (0.2 mL). The resulting solution was deoxygenated
through three freeze–pump–thaw cycles, and then stirred at 100 °C
for 4 d under a N2 atmosphere. After being passed through a short
Celite pad, the mixture was diluted with CH2Cl2 (50 mL). The re-
sulting solution was washed with water and brine, and the solvents
were evaporated to dryness. To the residual solid, a mixture of
CH2Cl2/MeOH (1:1, 50 mL) was added, and the solution was
heated at 50 °C for 10 min. The product was separated through
a silica gel column (CH2Cl2/hexane/ether, 1:2:1) and recrystallized
(CH2Cl2/MeOH) to give 2 (11.5 mg, 8.31 μmol, 62% yield) as an
1
orange powder. H NMR (600 MHz, CDCl3): δ = 8.26 (s, 6 H, β-
H), 8.24 (d, J = 7.8 Hz, 6 H, Ar-H), 8.03 (d, J = 7.8 Hz, 6 H, Ar-
H), 7.93 (d, J = 7.8 Hz, 6 H, Ar-H), 7.70 (d, J = 8.4 Hz, 6 H, Ar-
H), 6.86 (d, J = 4.8 Hz, 6 H, BODIPY-H), 6.33 (d, J = 3.6 Hz, 6
Pinacolatoboryl BODIPY 9: A 20-mL Schlenk tube was charged
with BODIPY
7 (150 mg, 400 μmol), bis(pinacolato)diboron
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H. Sugimoto, M. Muto, T. Tanaka, A. Osuka
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H, BODIPY-H), 2.70 (s, 18 H, Me), 0.92 (s, 3 H, OMe) ppm. 11B
NMR (193 MHz, CDCl3): δ = 0.98 (t, J = 66.0 Hz, 3 B, BODIPY),
–15.06 (s, 1 B, subporphyrin) ppm. 13C NMR (150 MHz, CDCl3):
δ = 158.7, 143.1, 143.0, 141.8, 140.3, 137.8, 135.3, 134.6, 134.3,
132.0, 131.2, 128.2, 127.7, 123.2, 120.9, 120.2, 47.2, 15.1 ppm.
HRMS (ESI-TOF+): m/z = 1352.5293 (calcd. for C84H60B4F6N9
1352.5284 [M – OMe]+). UV/Vis (CH2Cl2): λ (ε, m–1 cm–1) = 382
(127000), 512 (79000) nm. Fluorescence (CH2Cl2) λex = 383 nm,
cence (CH2Cl2): λex = 390 nm, λmax = 535 nm, ΦF = 0.013, λex
513 nm, λmax = 535 nm, ΦF = 0.013.
=
Methoxido[5,10,15-tris(4-biphenylyl)subporphyrinato]boron(III) (14):
A 10-mL Schlenk tube was charged with 5,10,15-tris(4-bro-
mophenyl)subporphyrin
methyl-2-phenyl-1,3,2-dioxaborolane
5
(19.2 mg, 26.0 μmol), 4,4,5,5-tetra-
(24.4 mg, 119 μmol),
Pd(dppf)Cl2·CH2Cl2 (4.57 mg, 5.60 μmol), K2CO3 (118 mg,
857 μmol), toluene (1.8 mL), and H2O (0.3 mL). The resulting solu-
tion was deoxygenated through three freeze–pump–thaw cycles and
then stirred at 100 °C for 6 h under a N2 atmosphere. After the
mixture was passed through a short Celite pad, the mixture was
diluted with CHCl3. The resulting solution was washed with water
and brine, and the solvents were evaporated to dryness. To the re-
sidual solid, a mixture of CHCl3/MeOH (1:1, 50 mL) was added,
and the solution was heated at 50 °C for 10 min. The product was
separated through a silica gel column (CH2Cl2/hexane/MeOH,
2:10:1) and recrystallized (CH2Cl2/MeOH) to give 14 (13.5 mg,
18.6 μmol, 71% yield) as a red powder. 1H NMR (600 MHz,
CDCl3): δ = 8.22 (s, 6 H, β-H), 8.18 (d, J = 8.2 Hz, 6 H, Ar-H),
7.95 (d, J = 8.2 Hz, 6 H, Ar-H), 7.81 (d, J = 7.3 Hz, 6 H, Ar-H),
7.55 (t, J = 7.8 Hz, 6 H, Ar-H), 7.44 (t, J = 7.2 Hz, 3 H, Ar-H),
0.89 (s, 3 H, OMe) ppm. 11B NMR (193 MHz, CDCl3): δ = –15.11
(s, 1 B) ppm. 13C NMR (150 MHz, CDCl3): δ = 141.1, 140.8, 136.4,
133.8, 129.1, 127.8, 127.5, 127.4, 122.7, 122.5, 120.3, 47.0 ppm.
HRMS (ESI-TOF+): m/z = 698.2770 (calcd. for C51H33BN3
698.2770 [M – OMe]+). UV/Vis (CH2Cl2): λ (ε, m–1 cm–1) = 382
(163000), 468 (13000), 495 (17000) nm. Fluorescence (CH2Cl2): λex
= 382 nm, λmax = 548 nm, ΦF = 0.255.
λmax = 530 nm, ΦF = 0.007, λex = 512 nm, λmax = 530 nm, ΦF
=
0.010.
BODIPY-Appended Subporphyrin 3:
A 10-mL Schlenk tube
was charged with 5,10,15-tris(4-ethynylphenyl)subporphyrin 10
(10.6 mg, 18.5 μmol), BODIPY 11 (26.6 mg, 59.2 μmol), Pd(PPh3)2-
Cl2 (4.3 mg, 3.70 μmol), CuI (1.4 mg, 7.40 μmol), toluene (0.8 mL),
and diisopropylamine (0.8 mL). The resulting solution was deoxy-
genated through three freeze–pump–thaw cycles and then stirred at
80 °C for 21 h under a N2 atmosphere. After the mixture was
passed through a short Celite pad, the mixture was diluted with
CH2Cl2 (50 mL). The resulting solution was washed with water and
brine, and the solvents were evaporated to dryness. To the residual
solid, a mixture of CH2Cl2/MeOH (1:1, 50 mL) was added, and the
solution was heated at 50 °C for 10 min. The product was separated
through a silica gel column (CH2Cl2/hexane/ether, 1:2:1) and
recrystallized (CH2Cl2/MeOH) to give 3 (19.8 mg, 12.9 μmol, 70%
yield) as an orange powder. 1H NMR (600 MHz, CDCl3): δ = 8.18
(s, 6 H, β-H), 8.11 (d, J = 7.8 Hz, 6 H, Ar-H), 7.91 (d, J = 8.4 Hz,
6 H, Ar-H), 7.77 (d, J = 7.2 Hz, 6 H, Ar-H), 7.36 (d, J = 7.2 Hz,
6 H, Ar-H), 6.02 (s, 6 H, BODIPY-H), 2.58 (s, 18 H, Me), 1.49 (s,
18 H, Me), 0.86 (s, 3 H, OMe) ppm. 11B NMR (193 MHz, CDCl3):
δ = 0.75 (t, J = 33.9 Hz, 3 B, BODIPY), –15.20 (s, 1 B, subporphy-
rin) ppm. 13C NMR (150 MHz, CDCl3): δ = 155.8, 143.0, 140.8,
140.7, 137.4, 135.2, 133.2, 132.4, 132.0, 131.2, 128.3, 124.0, 122.5,
122.4, 121.4, 120.0, 90.5, 90.2, 46.8, 29.7, 14.7 ppm. HRMS (ESI-
TOF+): m/z = 1508.6159 (calcd. for C90H72B4F6N9 1508.6227 [M –
OMe]+). UV/Vis (CH2Cl2): λ (ε, m–1 cm–1) = 389 (155000), 502
(104000) nm. Fluorescence (CH2Cl2): λex = 389 nm, λmax = 548 nm,
ΦF = 0.363, λex = 502 nm, λmax = 548 nm, ΦF = 0.297.
Methoxido[5,10,15-tris(4-terphenylyl)subporphyrinato]boron(III)
(15): A 10-mL Schlenk tube was charged with 5,10,15-tris(4-bro-
mophenyl)subporphyrin
5 (19.2 mg, 26.0 μmol), 4-(4,4,5,5-tet-
ramethyl-1,3,2-dioxaborolan-2-yl)biphenyl (31.9 mg, 114 μmol),
Pd(dppf)Cl2·CH2Cl2 (4.34 mg, 5.31 μmol), K2CO3 (121 mg,
878 μmol), toluene (1.3 mL), and H2O (0.3 mL). The resulting solu-
tion was deoxygenated through three freeze–pump–thaw cycles and
then stirred at 100 °C for 9 h under a N2 atmosphere. After the
mixture was passed through a short Celite pad, the mixture was
diluted with CHCl3. The resulting solution was washed with water
and brine, and the solvents were evaporated to dryness. To the re-
sidual solid, a mixture of CHCl3/MeOH (1:1, 50 mL) was added,
and the solution was heated at 50 °C for 10 min. The product was
separated through a silica gel column (CH2Cl2/hexane/MeOH,
2:10:1) and recrystallized (CH2Cl2/MeOH) to give 15 (19.1 mg,
19.9 μmol, 77% yield) as a red powder. 1H NMR (600 MHz,
CDCl3): δ = 8.24 (s, 6 H, β-H), 8.20 (d, J = 8.2 Hz, 6 H, Ar-H),
8.01 (d, J = 7.8 Hz, 6 H, Ar-H), 7.90 (d, J = 8.2 Hz, 6 H, Ar-H),
7.79 (d, J = 8.3 Hz, 6 H, Ar-H), 7.72 (d, J = 7.3 Hz, 3 H, Ar-
H),7.51 (t, J = 7.8 Hz, 6 H, Ar-H), 7.40 (t, J = 7.8 Hz, 3 H, Ar-
H), 0.91 (s, 3 H, OMe) ppm. 11B NMR (193 MHz, CDCl3): δ =
–15.08 (s, 1 B) ppm. 13C NMR (150 MHz, CDCl3): δ = 141.1,
140.8, 140.7,140.2, 139.6, 136.5, 133.8, 129.0, 127.9, 127.8, 127.7,
127.6, 127.4, 127.2, 122.5, 120.4, 47.1 ppm. HRMS (ESI-TOF+):
m/z = 926.3703 (calcd. for C69H45BN3 926.3712 [M – OMe]+). UV/
Vis (CH2Cl2): λ (ε, m–1 cm–1) = 385 (223000), 497(25000) nm. Fluo-
rescence (CH2Cl2): λex = 385 nm, λmax = 548 nm, ΦF = 0.337.
BODIPY-Appended Subporphyrin 4: A 10-mL Schlenk tube was
charged with 5,10,15-tris(4-ethynylphenyl)subporphyrin 10
(12.0 mg, 20.9 μmol), BODIPY 12 (29.1 mg, 69.0 μmol), Pd(PPh3)2-
Cl2 (4.8 mg, 4.18 μmol), CuI (1.6 mg, 8.36 μmol), toluene (0.8 mL),
and diisopropylamine (0.8 mL). The resulting solution was deoxy-
genated through three freeze–pump–thaw cycles and then stirred at
80 °C for 21 h under a N2 atmosphere. After the mixture was
passed through a short Celite pad, the mixture was diluted with
CH2Cl2 (50 mL). The resulting solution was washed with water and
brine, and the solvents were evaporated to dryness. To the residual
solid, a mixture of CH2Cl2/MeOH (1:1, 50 mL) was added, and the
solution was heated at 50 °C for 10 min. The product was separated
through a silica gel column (CH2Cl2/hexane/ether, 1:2:1) and
recrystallized (CH2Cl2/MeOH) to give 4 (22.1 mg, 15.2 μmol, 73%
1
yield) as a red powder. H NMR (600 MHz, CDCl3): δ = 8.19 (s,
6 H, β-H), 8.12 (d, J = 9.0 Hz, 6 H, Ar-H), 7.92 (d, J = 7.8 Hz, 6
H, Ar-H), 7.74 (d, J = 7.8 Hz, 6 H, Ar-H), 7.56 (d, J = 8.4 Hz, 6
H, Ar-H), 6.77 (d, J = 4.2 Hz, 6 H, BODIPY-H), 6.31 (d, J =
4.2 Hz, 6 H, BODIPY-H), 2.68 (s, 18 H, Me), 0.87 (s, 3 H,
OMe) ppm. 11B NMR (193 MHz, CDCl3): δ = 0.93 (t, J = 32.4 Hz,
3 B, BODIPY), –15.20 (s, 1 B, subporphyrin) ppm. 13C NMR
(150 MHz, CDCl3): δ = 157.9, 141.5, 143.0, 140.9, 137.5, 134.3,
134.2, 133.2, 132.0, 131.5, 130.5, 130.2, 125.1, 122.5, 122.4, 119.6,
91.3, 90.2, 46.9, 15.0 ppm. HRMS (ESI-TOF+) m/z = 1424.5299
Crystallographic Data for 1: C91H75B4F6N9O1, M = 1467.84, tri-
¯
clinic, space group P1 (no. 2), a = 9.086(8) Å, b = 23.79(2) Å, c =
24.84(2) Å, α = 97.060(12)°, β = 95.959(13)°, γ = 93.029(14)°, V =
5288(8) Å3, ρcalcd. = 0.922 gcm–3, Z = 2, R1 = 0.1018 [I Ͼ 2σ(I)],
wR2 = 0.2323 (all data), GOF = 0.709.
The contributions to the scattering arising from the presence of the
disordered solvents in the crystals were removed by use of the util-
ity SQUEEZE in the PLATON software package.[14]
(calcd. for C84H60B4F6N9 1424.5286 [M
–
OMe]+). UV/Vis
(CH2Cl2): λ (ε, m–1 cm–1) = 390 (138000), 513 (121000) nm. Fluores-
76
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 71–77

Synthesis of BODIPY-Appended Subporphyrins
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21.660(5) Å, c = 17.340(7) Å, β = 92.920(7)°, V = 4032.1(13) Å3,
ρcalcd. = 1.321 gcm–3, Z = 4, R1 = 0.0476 [I Ͼ 2σ(I)], wR2 = 0.1242
(all data), GOF = 1.070.
CCDC-787281 (for 1) and -787282 (for 14) contain the supplemen-
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tained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/datarequest/cif.
Supporting Information (see footnote on the first page of this arti-
cle): NMR spectra, high-resolution mass spectra (ESI-TOF), and
X-ray diffraction analysis.
Acknowledgments
[8]
This work was supported by Scientific Grants-in-Aid from the
Ministry of Education, Culture, Sports, Science, and Technology
of Japan (MEXT) [nos. 22245006 (A) and 20108001 (“pi-Space”)].
T. T. acknowledges a Japan Society for the Promotion of Science
Fellowship for Young Scientists.
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Received: August 24, 2010
Published Online: November 18, 2010
Eur. J. Org. Chem. 2011, 71–77
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
77