Post-modification of meso-meso-linked porphyrin arrays by iridium and rhodium catalyses for tuning of energy gap

Article abstract of DOI:10.1002/asia.200900053

meso-meso-Linked diporphyrins fabricated with multiple unsaturated carboxylic acid groups are efficiently synthesized by the use of transition-metal catalysis. Iridium-catalyzed direct borylation of meso-meso-linked diporphyrins furnish multi-borylated di

Full text of DOI:10.1002/asia.200900053

FULL PAPERS
DOI: 10.1002/asia.200900053
Post-Modification of meso–meso-Linked Porphyrin Arrays by Iridium and
Rhodium Catalyses for Tuning of Energy Gap
Jinping Chen,[a] Naoki Aratani,[a] Hiroshi Shinokubo,*[a, b] and Atsuhiro Osuka*[a]
Abstract: meso–meso-Linked dipor-
phyrins fabricated with multiple unsa-
turated carboxylic acid groups are effi-
ciently synthesized by the use of transi-
tion-metal catalysis. Iridium-catalyzed
direct borylation of meso–meso-linked
diporphyrins furnish multi-borylated
diporphyrins with high regioselectivity.
Then, the introduction of a,b- or
a,b,g,d-unsaturated ester functions to
the diporphyrins is achieved through
rhodium-catalyzed Heck-type addition
of the borylated diporphyrins to acry-
late or 2,4-pentadienoate esters. Sapo-
nification of the esters to the corre-
sponding acids is accomplished in high
yields. The post-modification of dipor-
phyrin 6 smoothly provides a water-
soluble multiporphyrin array 1 in 84%
total yield in 3 steps. This functionaliza-
tion significantly affects the electronic
properties of the porphyrins, resulting
in different energy levels of each por-
phyrin unit. The absorption and fluo-
rescence spectra indicate efficient
energy transfer in the porphyrin
dimers.
ꢀ
ꢀ
Keywords: C C coupling
activation · iridium · porphyrinoids ·
· C H
rhodium
Introduction
time. In this regard, extended conjugation at the b-positions
has a significant effect on the electronic property of por-
phyrins and induces a substantial red-shift of their absorp-
tion.[1] The research groups of Grꢀtzel and Officer have suc-
cessfully applied this concept to design the best performing
porphyrin photosensitizers and reached an efficiency of
around 7%.[2] Another approach to harvest photons more
efficiently is to construct electronically interactive multipor-
phyrin arrays that exhibit widely distributed broad absorp-
tion bands arising from the excitonic interactions between
the constituent porphyrins. Furthermore, these multipor-
phyrin arrays are expected to exhibit higher performance in
DSSC devices when a suitable energy gradient is designed
to drive photoexcitation energy to migrate to porphyrins
that are proximal to the surface, hence allowing efficient
electron injection into the acceptor surface. Although a
number of porphyrin arrays have been extensively synthe-
sized, so far, their applications to DSSC devices are rare.[3]
This is partly because of the difficulty of direct installation
of porphyrin arrays with conjugated anchors to allow elec-
tronic coupling with the surface.
The use of porphyrin-based chromophores as light harvest-
ing molecules for dye-sensitized solar cells (DSSCs) is quite
attractive because of their primary role in the natural photo-
synthetic system. However, porphyrins possess an intense
Soret band at 400–450 nm and moderate Q-bands at 500–
650 nm, which are poorly matched with solar light distribu-
tion. One approach to solve this mismatched spectral fea-
ture is to broaden and red-shift the strong and narrow Soret
band, and make the weak Q-bands stronger at the same
[a] Dr. J. Chen, Dr. N. Aratani, Prof. Dr. H. Shinokubo,
Prof. Dr. A. Osuka
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
[b] Prof. Dr. H. Shinokubo
Recently, it has been demonstrated that the iridium-cata-
Department of Applied Chemistry
Graduate School of Engineering
Nagoya University
Chikusa-ku, Nagoya 464-8603 (Japan)
Fax : (+81)52-789-5113
ꢀ
lyzed direct borylation of aromatic compounds by C H
bond activation is a powerful tool for organic synthesis.[4]
Moreover, the use of organoboranes under rhodium cataly-
ꢀ
sis has been extensively explored for new types of C C
E-mail: hshino@apchem.nagoya-u.ac.jp
bond formations.[5] Our research groups have developed iri-
dium-catalyzed highly regioselective borylation of porphyr-
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/asia.200900053.
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Chem. Asian J. 2009, 4, 1126 – 1133

ins.[6] As a continuing research, a facile introduction of a,b-
and a,b,g,d-unsaturated ester functions to porphyrin mono-
mers has been achieved through rhodium-catalyzed Heck-
type addition of the borylated porphyrin to acrylate and 2,4-
pentadienoate esters.[7,8]
Covalently linked porphyrin oligomers have been attract-
ing much interest because of the great potential application
to areas such as molecular electronic devices,[9] nonlinear
optical materials,[10] and DSSCs.[3] As simple multiporphyrin
arrays, dimeric porphyrins with different kinds of linkages
have been synthesized and studied extensively.[11] Among
these, the meso–meso directly linked porphyrin dimer is par-
ticularly attractive given their unique spectral characteristics
and the nearly orthogonal conformation without serious
electronic delocalization.[11e,12] We anticipated that the simi-
lar synthetic strategies of borylation and Heck-type addition
could be applicable to meso–meso-linked diporphyrins, con-
sequently affording an appropriate dye for applications.
First, this functionalization will induce a different energy
level of each porphyrin unit because of the changing of the
electronic property by the extended conjugation at the b-po-
sitions. Second, the introduction of carboxylic acid groups at
the b-position ensures efficient adsorption on the surface of
TiO2 and enhances the efficiency of dye-sensitized solar
cells.[2,7b,13] This strategy will open a new way for the applica-
tion of porphyrin arrays especially in dye-sensitized solar
cells.
Scheme 1. Selective borylation of meso–meso-linked diporphyrin.
Results and Discussion
Syntheses
Diporphyrin tetraacids 1 and 2: The procedure for the syn-
thesis of diporphyrin tetraacids 1 and 2 is shown in
Scheme 1 and 2. Dimer 6 was prepared by the AgPF6-pro-
Scheme 2. Synthesis of diporphyrin tetraacids.
moted oxidative coupling reaction.[14] Treatment of
6
[Rh(OH)ACTHNGUTRENNU(G cod)]2 as catalyst in dioxane and water (10:1) at
(1.0 equiv) with bis(pinacolato)diboron (20.0 equiv) in the
presence of a catalyst generated from [Ir(OMe)(cod)]2
408C afforded the desired tetraacrylated product 8 in 92%
yield. Hydrolysis of tetraester 8 in the mixture of THF and
ethanol in the presence of NaOH/H2O afforded the corre-
sponding tetraacid 1 quantitatively.
In the next step, the oxidation of 8 with DDQ (5.0 equiv)
and ScACTHUNTGRNE(NUG OTf)3 (5.0 equiv) in toluene under reflux for 6 h, af-
G
ACHTUNGTRENNUNG
(2.0 mol%) and 4,4’-di-tert-butyl-2,2’-bipyridyl (dtbpy,
4.0 mol%) in dioxane provided tetraborylated product 7 in
high yield (91%) with perfect regioselectivity at the outer b-
positions (Scheme 1).[6b] We then attempted the introduction
of unsaturated ester functions by the use of a Rh-catalyzed
Heck-type addition (Scheme 2). Treatment of tetraborylated
forded meso–meso, b-b, b’-b’ triply linked diporphyrin 9 in
54% yield.[15] Saponification of 9 at the same conditions af-
1
diporphyrin
7
with ethyl acrylate in the presence of
forded the fully conjugated tetraacid 2. The H NMR spec-
tra of 2 in [D5]pyridine, CDCl3, and [D8]THF is almost un-
readable because of aggregation. The MALDI-TOF mass
spectra showed its ion peak at m/z=1776.5 (calcd 1774.8).
The diporphyrins 1 and 2 can be dissolved in THF and basic
water, but are insoluble in CHCl3 and CH2Cl2.
Abstract in Japanese:
Diporphyrin diacids 3 and 4: The facile preparation of di-
porphyrin tetraacids promoted us to continue the functional-
ization of other kinds of diporphyrins. Because the AgPF6-
induced oxidative coupling reaction of two different porphy-
rin monomers affords random oligomeric products, we em-
ployed a Pd-catalyzed cross-coupling reaction[16] to selective-
ly synthesize 12a and 12b (Scheme 3). Cross-coupling reac-
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H. Shinokubo, A. Osuka et al.
FULL PAPERS
Scheme 4. Synthesis of diporphyrin diacids.
X-ray Diffraction Analysis
Fortunately, single crystals suitable for X-ray diffraction
studies were obtained by slow diffusion of methanol into a
toluene solution of the diporphyrin diester 14a, with the
structure depicted in Figure 1.[18] The mean planes of the
Scheme 3. Synthesis and borylation of asymmetric diporphyrin.
tion of 10[17] and 11a was carried out in a mixture of toluene
and DMF (2:1) in the presence of PdACHTNUTRGEN(UNG PPh3)4 (0.1 equiv) and
Cs2CO3 (2.0 equiv) at 808C to furnish 12a in 90% yield.
Under the same conditions, the cross-coupling reaction of 10
and 11b afforded 12b only in 48% yield. The main byprod-
uct is the dimer formed by self-coupling of 10, which is diffi-
cult to separate with the product of 12b by silica gel chro-
matography or gel permeation chromatography (GPC). Al-
though the yield for 12b is low by the cross-coupling reac-
tion, metalation of 12a with ZnACHTNUGTRENUNG(OAc)2 afforded 12b quanti-
tatively.
With the same method as used for 7, borylation of 12a
and 12b under the standard conditions afforded 13a and
13b almost quantitatively. To eliminate tedious separation
of the borylated compounds by recycling preparative GPC-
HPLC, the borylated mixture was used for the following
Heck-type addition without separation. Treatment of the
crude product of 13a and 13b with ethyl acrylate in the
Figure 1. X-ray structure of diporphyrin diester 14a. a) Top view and
b) side view. The thermal ellipsoids are 50% probability level. meso-Aryl
groups and solvents are omitted for clarity.
presence of [Rh(OH)ACHTUNTRGNEUNG(cod)]2 as catalyst in dioxane and
water (10:1) at 408C, afforded the desired diacrylated prod-
uct 14a and 14b in 46% and 52% yields in two steps from
12a and 12b, respectively. The reaction of 13a or 13b with
methyl 2,4-pentadienoate allows further elongation of conju-
gation, which will further effect the electronic properties of
the porphyrin. The use of methyl 2,4-pentadienoate instead
of ethyl acrylate provided 15a and 15b in 29% and 18%
yields in two steps from 12a and 12b, respectively. Following
the general procedure for the hydrolysis, diporphyrin diacids
3a, 3b, 4a, and 4b were prepared quantitatively (Scheme 4).
two porphyrin rings take an orthogonal conformation with a
dihedral angle of 87.68, which means the two units of por-
phyrin are electronically decoupled. The center-to-center
distance of the two porphyrin rings is 8.3 ꢂ. The unsaturated
ester moieties and the zinc(II)-porphyrin unit take a copla-
nar conformation, as clearly shown in the side view. This ori-
entation allows effective electronic conjugation between the
zinc(II)-porphyrin unit and the carbon–carbon double bonds
of unsaturated esters, which change the energy level of the
ZnII-porphyrin unit effectively. The substantially shortened
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Post-Modification of meso–meso-Linked Porphyrin Arrays
ꢀ
Cpyrrole Cvinyl single bond length (1.44 ꢂ) also indicates the
effective conjugation between the porphyrin core and the
unsaturated moieties.
Steady-State Absorption and Fluorescence Spectroscopy
The absorption and fluorescence spectra of diporphyrin di-
acids 3a, 3b, 4a, and 4b were measured in dichloromethane
but those of 1 and 2 were measured in THF because of their
insolubility in dichloromethane. Figure 2 illustrates the ab-
Figure 3. UV/Vis absorption spectra of diporphyrin diacid 3a (a),
model 1 (c), and model 3 (b) in CH2Cl2.
ins. The intensity of the Q-bands clearly increase compared
with those of the model compounds. The difference of the
absorption coefficients and the slightly red-shift of the ab-
sorption compared with the model compounds, can be ex-
plained by the coupling of transition dipole moments of the
porphyrin units in the dimers.[19,12] The dimers 3b, 4a, and
4b exhibit similar absorption character (see Supporting In-
formation) and the data is summarized in Table 1.
Figure 2. UV/Vis absorption spectra of diporphyrin tetraacids 1 (c)
and 2 (a) in THF.
Figure 4 shows the normalized fluorescence spectra of 3a,
3b, 4a, and 4b along with the corresponding model com-
pounds. The dimer 3a exhibits the similar emission feature
to that of model 1, indicating energy transfer from the ZnII-
porphyrin unit with the unsaturated functions to the free-
base porphyrin unit. The emission of 4a is also similar to
that of model 1, suggesting the same direction of energy
transfer. This is caused by the higher energy level of the
ZnII-porphyrin units, despite the presence of the electron-
withdrawing unsaturated ester functions. Dimers 3b and 4b
exhibit none of the emission character of model 2 but rather
those of model 3 and model 4. In these cases, energy transfer
took place from the ZnII-porphyrin unit to the ZnII-porphy-
rin unit with the unsaturated functions, as a result of energy
lowering by the unsaturated ester moieties. The S1-excitation
energy for model 3 (1.95 eV) and model 4 (1.94 eV), which
were estimated from the emission spectra, are higher than
that of model 1 (1.90 eV) and lower than that of model 2
(2.07 eV). This suggests that the energy transfer process in
dimers 3b and 4b is energetically favorable.
sorption spectra of 1 and 2 in THF, in which 1 exhibits
slightly split Soret bands at 458 nm and 484 nm and a broad
Q-band at 585 nm. The absorption of 2 is extended to the
IR region because of the fully conjugated p-system. In
asymmetric diporphyrins 3a, 3b, 4a, and 4b, energy transfer
is expected to occur arising from the different energy level
of each porphyrin unit. To clarify the direction of energy
transfer in the asymmetric diporphyrins, model 1 to
model 4[7] were used for comparison (Scheme 5). Figure 3
shows the absorption spectrum of 3a compared with
model 1 and model 3. Dimer 3a exhibits two intense Soret
bands, which are diagnostic to meso–meso-linked diporphyr-
To examine the possibility of electron transfer in the
asymmetric porphyrin dimers in polar solvents, we measured
the fluorescence spectra of the corresponding esters in dif-
ferent solvents at the same concentration. We found that the
fluorescence of 14b and 15b was quenched significantly in
polar solvents (THF/DMF=1:1 or 1:3) compared with those
in THF and CH2Cl2, whereas there was almost no change
for the fluorescence intensity of 14a, 15a, and the model
compounds, and with only a slight shift (Figure 5). This sug-
gested that the electron transfer could occur in dimers 3b
and 4b in polar solvents. The free-energy change involved in
Scheme 5. Structure of model compounds.
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H. Shinokubo, A. Osuka et al.
FULL PAPERS
Table 1. Spectral properties for dimers 1–4b and the model compounds in CH2Cl2.
culation according to Equa-
tion (1) shows that the electron
transfer from the ZnII-porphy-
rin unit to the ZnII-porphyrin
unit with unsaturated acid moi-
eties (e=9.08 D) is exothermic
by 7.6 and 7.8 kcalmolꢀ1 for
dimers 3b and 4b, respectively.
This means that the intramo-
lecular electron transfer could
occur efficiently.
Absorption
lmax [nm]
Emission [lem/nm]
Quantum yield[b]
Excitation energy [eV][c]
emax [Mꢀ1 cmꢀ1
]
1[a]
2[a]
3a
3b
4a
4b
458
484
455
599
419
476
421
478
418
487
420
488
421
422
459
475
1.26ꢃ105
1.74ꢃ 105
4.58ꢃ104
5.44ꢃ 104
1.93ꢃ105
2.64ꢃ 105
1.65ꢃ105
2.00ꢃ 105
1.47ꢃ105
2.06ꢃ 105
1.65ꢃ105
2.18ꢃ 105
5.24ꢃ105
6.78ꢃ105
1.76ꢃ105
1.93ꢃ105
660
AHCTUNGTRENGN(UN broad)
–
–
–
–
–
–
–
–
–
657, 719
679
AHCTUNGTRENGN(UN broad)
657, 720
0.087
0.039
0.080
0.056
656, 687
AHCTUNGTRENGN(UN broad)
650, 714
595, 645
633, 682
637, 688
model 1
model 2
model 3
model 4
–
–
–
–
1.90
2.07
1.95
1.94
Conclusions
An expeditious functionaliza-
tion of porphyrin arrays with
unsaturated carboxylic acid
moieties has been achieved by
[a] Measured in THF. [b] The quantum yields of the corresponding esters 14a, 14b, 15a, and 15b. [c] Estimat-
ed from the emission spectra.
the iridium-catalyzed borylation and rhodium-catalyzed
Heck-type addition. This functionalization has a significant
effect on the electronic properties of the meso–meso-linked
diporphyrins and allows fine-tuning of the energy gaps. The
absorption and fluorescence spectra, compared with model
compounds, indicate efficient energy transfer in the porphy-
rin dimers. The direction of energy transfer in dimers 3a
and 4a is from the ZnII-porphyrin unit to the free-base por-
phyrin, although the Zn-porphyrin unit has two dienoate
groups. In 3b and 4b, the energy transfer occurs from the
ZnII-porphyrin unit to the ZnII-porphyrin unit with unsatu-
rated acid moieties, which is favorable for high efficiency for
DSSCs devices. Furthermore, the observed fluorescence
quenching of dimer 3b and 4b in polar solvents suggested
an intramolecular electron transfer.
Figure 4. Normalized fluorescence spectra of porphyrin diacids and
model compounds in CH2Cl2. Excited at one of the Soret bands in the
lower energy.
an electron transfer process can be calculated by the Rehm–
Weller Equation (1)[20]
:
DG ¼ 23:06½EðDꢁþ=DÞꢀEðA=AꢁꢀÞꢀe2=reꢂꢀE00
ð1Þ
E00 is the excited-state energy, EACUTHGNTRENNUNG CAHTUNGTRENNUNG
(D·+/D) and E(A/A·ꢀ) are
Figure 5. Emission spectra of 14b in CH2Cl2 (c), THF (b), THF/
DMF (1:1) (a), THF/DMF (1:3) (d) at the same concentrations. Ex-
cited at one of the Soret bands in the lower energy.
the redox potentials of the donor and the acceptor. e2/re rep-
resents the Coulumbic energy associated with bringing sepa-
rated radical ions at a distance r in a solvent of dielectric
constant e (r is the central distance of two porphyrin rings,
r=8.296 ꢂ). The reduction potentials of model 3, model 4,
and the oxidation potential of model 2 were measured in di-
chloromethane to be ꢀ1.66, ꢀ1.65, and +0.28 V with respect
to the ferrocene/ferrocenium ion pair, respectively. The cal-
Experimental Section
Instrumentation and Materials
1H NMR (600 MHz) spectra were obtained using a JEOL ECA-600 spec-
trometer, and chemical shifts were reported relative to CHCl3 as internal
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Post-Modification of meso–meso-Linked Porphyrin Arrays
reference (d=7.260 ppm). UV/Vis absorption and steady-state fluores-
cence spectra were recorded on a Shimadzu UV-2550 and a Shimadzu
RF-5300PC spectrophotometer, respectively. MALDI-TOF mass spectra
were obtained using a Shimadzu/KRATOS KOMPACT MALDI 4 spec-
trometer without matrix. High resolution ESI-TOF mass spectra were
taken on a Bruker microTOF. Redox potentials were measured by the
cyclic voltammetry method on an ALS electrochemical analyzer model
660 in CH2Cl2, using a platinum microelectrode and a Ag/AgClO4 refer-
ence electrode in the presence of Bu4NBF4 (0.1m) as the supporting elec-
trolyte. Preparative separations were performed by silica gel gravity
column chromatography (Wako gel C-300). Recycling preparative GPC-
HPLC was carried out on JAI LC-908 with preparative JAIGEL-2H and
2.5H columns. Analytical HPLC was recorded on a Shimadzu DGU-14 A
d=1.46 (s, 72H, tBu), 7.68 (d, J=16.1 Hz, 4H, double bond), 7.97 (m,
4H, m-ArH), 8.42 (d, J=4.6 Hz, 4H, b-H), 8.47 (m, 8H, o-ArH), 8.98 (d,
J=4.6 Hz, 4H, b-H), 9.89 (s, 4H, b-H), 10.08 (d, J=15.6 Hz, 4H, double
bond), 10.25 ppm (s, 2H, meso-H); MS (MALDI-TOF): m/z (%) calcd
for C108H110N8O8Zn2: 1774.70 [M]+; found: 1771.2.
Triply linked diporphyrin tetraacrylate ester 9: Diporphyrin tetraester 8
(10.0 mg, 0.0053 mmol, 1.0 equiv), DDQ (6.02 mg, 0.0265 mmol,
5.0 equiv), and ScACHTNUTRGNEUNG(OTf)3 (13.0 mg, 0.0265 mmol, 5.0 equiv) were placed in
a two-necked flask (50 mL), which was purged with argon and charged
with dry toluene (3.0 mL). The resulting mixture was stirred at 808C for
6 h under argon in the dark (the reaction vessel was covered with foil).
The reaction was quenched with THF (10 mL) and stirred for an addi-
tional 1 h at room temperature. The mixture was filtered through a short
alumina column (eluent: THF) and the crude product was recrystallized
from a mixture of methanol and dichloromethane to afford 9 (5.4 mg,
54%). 1H NMR ([D8]THF): d=1.52 (s, 72H, tBu), 4.30 (q, 8H, OCH2),
6.70 (d, J=15.6 Hz, 4H, double bond), 7.33 (s, 4H, m-ArH), 7.72 (s, 8H,
o-ArH), 7.75 (s, 4H, b-H), 8.06 (s, 4H, b-H), 8.73 (d, J=15.1 Hz, 4H,
double bond), 8.88 ppm (s, 2H, meso-H); MS (HR-ESI): m/z (%) calcd
for C116H123N8O8Zn2: 1882.7963 [M+H]+; found: 1882.7988.
system with
a COSMOSIL-packed column and a UV/Vis detector.
Unless otherwise stated, materials obtained from commercial suppliers
were used without further purification. Solvents used for spectroscopic
measurements were all spectra grade.
Crystallographic Data Collection and Structure Refinement
Data collection was carried out at low temperature (ꢀ1538C) on a
Rigaku RAXIS-RAPID with graphite monochromated MoKa radiation
(l=0.71069 ꢂ). The structure was solved by direct methods (SHELXS-
97)[21] using the full-matrix least square technique (SHELXL-97).[21]
CCDC 716804 contains the supplementary crystallographic data for this
paper. These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre at www.ccdc.cam.ac.uk/data_request/cif.
Triply linked diporphyrin tetraacrylic acid 2: According to the procedure
of 1, triply linked diporphyrin tetraester 9 (14.5 mg) was hydrolyzed to
afford
2
(10.0 mg, 73%) as dark green powder. The 1H NMR in
[D5]pyridine, CDCl3, and [D8]THF is almost unreadable. UV/Vis (THF):
lmax [e (Mꢀ1 cmꢀ1)]=455 (4.58ꢃ104), 599 (5.44ꢃ104), 858 (1.43ꢃ104), 1117
(7.85ꢃ103); MS (MALDI-TOF): m/z (%) calcd for C108H106N8O8Zn2:
1774.80 [M]+; found: 1776.5.
Syntheses
meso-Borylporphyrin 10: To a two-necked flask (500 mL) equipped with
stirrer and ice bath, were added 5,15-bis(3,5-di-tert-butylphenyl)porphyrin
(5, 730 mg, 0.97 mmol, 1.0 equiv), CHCl3 (300 mL), and pyridine
(1.0 mL). Then, a solution of N-bromosuccinimide (164 mg, 0.92 mmol,
0.95 equiv) in CHCl3 (50 mL) was added dropwise over a period of
30 min at 0–28C. The mixture was stirred for 5 min at 0–28C. Then, the
reaction was quenched by the addition of acetone (2 mL). The mixture
was washed with water, dried over anhydrous sodium sulfate, and evapo-
rated to dryness. Precipitation from CH2Cl2/MeOH afforded a purple
solid (720 mg) of a mixture of meso-bromoporphyrin, meso,meso-dibro-
Tetraboryldiporphyrin 7: Diporphyrin 6 (74 mg, 0.049 mmol, 1.0 equiv),
bis(pinacolato)diboron (251 mg, 0.988 mmol, 20.0 equiv), 4,4’-di-tert-
butyl-2,2’-bipyridyl (5.3 mg, 0.020 mmol, 0.4 equiv), and [IrACTHNUTRGENN(UG OMe)ACHTUNGTREN(NUNG cod)]2
(6.5 mg, 0.01 mmol, 0.2 equiv) were placed in a Schlenk flask, which was
purged with argon and then charged with 1,4-dioxane (1.5 mL). The mix-
ture was stirred at reflux for 60 h under argon. After removal of solvents
under vacuum, the residue was dissolved in CH2Cl2. The solution was fil-
tered through a short pad of florisil to get rid of the catalyst and insolu-
ble salts (eluent: CH2Cl2). Then, the crude product was purified by recy-
cling preparative GPC-HPLC chromatography to provide 7 as a dark red
solid (90 mg, 91%, recrystallized from a mixture of methanol and di-
chloromethane). 1H NMR (CDCl3): d=1.54 (s, 72H, tBu), 1.76 (s, 48H,
CH3), 7.68 (m, 4H, m-ArH), 8.09 (m, 12H, o-ArH and b-H), 8.67(d, 4H,
b-H), 9.76 (s, 4H, b-H), 11.55 ppm (s, 2H, meso-H); MS (MALDI-TOF):
m/z (%) calcd for C120H146B4N8O8Zn2: 1999.02 [M]+; found: 1994.2.
moporphyrin, and 5. The mixture (720 mg) and PdACHTUNGTRNEG(UN PPh3)2Cl2 (61.0 mg,
0.087 mmol, 0.1 equiv) were placed in a Schlenk flask, which was purged
with argon and then charged with pinacolborane (1.26 mL, 8.7 mmol,
10.0 equiv), Et3N (1.3 mL), and dry CH2ClCH2Cl (8 mL). The mixture
was stirred at reflux (oil bath 908C) for 2 h under argon. After removal
of solvents under vacuum, the crude product was purified by silica gel
chromatography (CH2Cl2/hexane=1:2) to give 10 (500 mg, 58%) as a
dark-red solid after recrystallization from CH2Cl2/MeOH. From the reac-
tion mixture, diborylporphyrin (90 mg, 9%) and 7 (190 mg, 26%) were
also isolated. 1H NMR (CDCl3): d=1.51–1.56 (d, 36H, tBu), 1.86 (s, 12H,
CH3), 7.83 (s, 2H, m-ArH), 8.11 (s, 4H, o-ArH), 9.15 (d, J=4.6 Hz, 2H,
b-H), 9.18 (d, J=4.5 Hz, 2H, b-H), 9.44 (d, J=4.6 Hz, 2H, b-H), 9.94 (d,
J=4.6 Hz, 2H, b-H), 10.34 ppm (s, 1H, meso-H); MS (MALDI-TOF):
m/z (%) calcd for C54H63BN4O2Zn: 874.43 [M]+; found: 874.6.
Diporphyrin tetraacrylate ester 8: Tetraborylated diporphyrin 7 (104 mg,
0.052 mmol, 1.0 equiv) and [Rh(OH)ACHTNUGTRENUNG(cod)]2 (2.37 mg, 0.0052 mmol,
0.1 equiv) were placed in a Schlenk flask, which was purged with argon
and then charged with 1,4-dioxane (3.0 mL), H2O (300 mL), and ethyl ac-
rylate (228 mL, 2.08 mmol, 40 equiv). The mixture was stirred at 408C for
3 days under argon. After removal of the solvent under vacuum, the
crude product was filtered through
a short C200 silica gel column
(eluent: THF), and recrystallized from a mixture of methanol and di-
chloromethane to afford 8 (90 mg, 92%). 1H NMR ([D5]pyridine): d=
1.45 (s, 72H, tBu), 4.46 (q, 8H, OCH2), 7.43 (d, J=16.0 Hz, 4H, double
bond), 7.98 (s, 4H, m-ArH), 8.40 (d, J=4.6 Hz, 4H, b-H), 8.45 (s, 8H, o-
ArH), 8.97 (d, J=4.6 Hz, 4H, b-H), 9.86 (s, 4H, b-H), 9.95 (d, J=
16.0 Hz, 4H, double bond), 11.19 ppm (s, 2H, meso-H); MS (HR-ESI):
m/z (%) calcd for C116H126N8O8Zn2Na: 1909.8174 [M+Na]+; found:
1909.8182.
meso-Bromoporphyrin 11a: To a two-necked flask (300 mL) equipped
with stirrer and ice bath, were added 5,10,15-tris(3,5-di-tert-butylphenyl)-
porphyrin (336 mg, 0.38 mmol, 1.0 equiv), CHCl3 (120 mL), and pyridine
(0.5 mL). Then a solution of NBS (71.2 mg, 0.40 mmol, 1.05 equiv) in
CHCl3 (30 mL) was added dropwise over a period of 30 min at 0–28C.
The mixture was stirred for 15 min in an ice bath. Then, the reaction was
quenched by the addition of acetone (2 mL). The mixture was washed
with water, dried over anhydrous Na2SO4, and evaporated to dryness.
Precipitation from CH2Cl2/MeOH gave 11a (337 mg, 92%) as a purple
solid. 1H NMR (CDCl3): d=1.50–1.55 (d, 54H, tBu), 7.79 (s, 1H, m-
ArH), 7.81 (s, 2H, m-ArH), 8.03 (s, 2H, o-ArH), 8.06 (s, 4H, o-ArH),
8.84 (s, 4H, b-H), 8.93 (d, J=4.6 Hz, 2H, b-H), 9.67 ppm (d, J=4.6 Hz,
2H, b-H); MS (MALDI-TOF): m/z (%) calcd for C62H73BrN4: 952.50
[M]+; found: 953.3.
Diporphyrin tetraacrylic acid 1: The diporphyrin tetraester 8 (10.0 mg,
0.0053 mmol, 1.0 equiv) was dissolved in THF (1 mL). Then, ethanol
(1 mL) and an aqueous solution of NaOH (1 mL, 2m, 370 equiv) were
added. The solution was stirred at N2 atmosphere at 65–708C (oil bath)
for 28 h. The solvent was removed in vacuo, and water (ca. 200 mL) was
added to the solid. Then, the green solid was precipitated by a slow addi-
tion of aqueous HCl (1m) to the aqueous solution (pH 3). This was kept
still overnight and filtered to give 1 (9.4 mg, 99%). UV/Vis (THF): lmax
[e (Mꢀ1 cmꢀ1)]=458 (1.26ꢃ105), 484 (1.74ꢃ105), 584 (3.77ꢃ104); Fluores-
meso-Bromo-zinc(II)-porphyrin 11b: meso-Bromoporphyryin 11a
(337 mg, 0.353 mmol, 1.0 equiv) was dissolved in CHCl3 (30 mL). A solu-
tion of ZnACTHNUGETRNNU(G OAc)2·2H2O (311.7 mg, 1.42 mmol, 4.0 equiv) in MeOH
1
cence (THF, lex =484 nm) lem =660 nm (broad); H NMR ([D5]pyridine):
Chem. Asian J. 2009, 4, 1126 – 1133
ꢁ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
1131

H. Shinokubo, A. Osuka et al.
FULL PAPERS
(10 mL) was added to the solution in one portion, and the reaction mix-
ture was reflux for 1 h. The reaction was quenched with water and ex-
tracted 3 times with CHCl3. The organic layer was washed successively
with aqueous NaHCO3 (5%) and water, and dried over Na2SO4. The sol-
vent was removed in vacuo and recrystallized from a mixture of metha-
nol and dichloromethane to give 11b (345 mg, 96%) as a red solid.
1H NMR (CDCl3): d=1.50–1.54 (d, 54H, tBu), 7.78 (s, 1H, m-ArH), 7.81
(s, 2H, m-ArH), 8.03 (s, 2H, o-ArH), 8.07 (s, 4H, o-ArH), 8.96 (s, 4H, b-
H), 9.04 (d, J=4.6 Hz, 2H, b-H), 9.79 ppm (d, J=4.5 Hz, 2H, b-H); MS
(MALDI-TOF): m/z (%) calcd for C62H71BrN4Zn: 1014.42 [M+]; found:
1015.5.
m-ArH), 8.01 (m, 2H, b-H), 8.06 (m, 8H, o-ArH), 8.14 (m, 2H, o-ArH),
8.16 (d, J=4.1 Hz, 2H, b-H), 8.60 (d, J=4.1 Hz, 2H, b-H), 8.67 (d, J=
4.1 Hz, 2H, b-H), 8.92 (d, J=4.6 Hz, 2H, b-H), 8.96 (d, J=4.6 Hz, 2H, b-
H), 9.36 (s, 2H, b-H), 9.51 (d, J=16.5 Hz, 2H, double bond), 10.64 ppm
(s, 1H, meso-H); MS (HR-ESI): m/z (%) calcd for C120H137N8O4Zn:
1818.0049 [M+H]+; found: 1818.0003.
Diporphyrin diacrylate ester 14b: According to the procedure of 14a,
14b (52%) was prepared from 13b in two steps from 12b. 1H NMR
(CDCl3): d=1.43–1.57 (m, 96H tBu and Et), 4.49 (q, 4H, OCH2), 7.16 (d,
J=16.1 Hz, 2H, double bond), 7.69 (s, 2H, m-ArH), 7.75 (s, 2H, m-
ArH), 7.83 (s, 1H, m-ArH), 8.07–8.17 (m, 14H, b-H and o-ArH), 8.66 (d,
J=4.6 Hz, 2H, b-H), 8.71 (d, J=4.6 Hz, 2H, b-H), 9.03 (d, J=4.6 Hz,
2H, b-H), 9.07 (d, J=4.6 Hz, 2H, b-H), 9.35 (s, 2H, b-H), 9.43 (br, 2H,
double bond), 10.58 ppm (br, 1H, meso-H); MS (HR-ESI): m/z (%)
calcd for C120H135N8O4Zn2: 1879.9184 [M+H]+; found: 1879.9186.
Cross-coupling reaction for the preparation of porphyrin dimer 12a: Por-
phyrin boronate 10 (125.3 mg, 0.143 mmol, 1.0 equiv), bromoporphyrin
11a (204 mg, 0.214 mmol, 1.5 equiv), Cs2CO3 (93.1 mg, 0.286 mmol,
2.0 equiv), and PdACHTUNGTRENNUNG(PPh3)4 (16.5 mg, 0.014 mmol, 0.1 equiv) were placed in
the Schlenk flask, which was purged with argon and then charged with
dry DMF (2 mL) and dry toluene (4 mL). The solution was deoxygenated
by the three freeze-pump-thaw degas cycles, and the resulting mixture
was heated at 808C for 20 h under argon. The reaction was quenched
with water and extracted with CH2Cl2. The organic layer was dried over
anhydrous Na2SO4, and the crude product was purified by silica gel
column chromatography (CH2Cl2/Hexane=1:3) to give 12a (209 mg,
90%) as a dark red solid after precipitation from a mixture of chloroform
and acetonitrile. 1H NMR (CDCl3): d=ꢀ2.11 (s, 2H, NH), 1.42–1.54 (m,
90H, tBu), 7.68 (s, 2H, m-ArH), 7.72 (s, 2H, m-ArH), 7.82 (s, 1H, m-
ArH), 8.00 (d, J=4.6 Hz, 2H, b-H), 8.06 (s, 4H, o-ArH), 8.11 (s, 4H, o-
ArH), 8.15 (m, 2H, o-ArH), 8.23 (d, J=4.6 Hz, 2H, b-H), 8.58 (d, J=
4.6 Hz, 2H, b-H), 8.77 (d, J=4.1 Hz, 2H, b-H), 8.93 (d, J=4.1 Hz, 2H, b-
H), 8.96 (d, J=4.2 Hz, 2H, b-H), 9.18 (d, J=4.2 Hz, 2H, b-H), 9.50 (d,
J=4.1 Hz, 2H, b-H), 10.40 ppm (s, 1H, meso-H); MS (MALDI-TOF):
m/z (%) calcd for C110H124N8Zn: 1620.92 [M]+; found: 1621.9.
Diporphyrin diacrylic acid 3a: According to the procedure of 2, 14a
(21.0 mg) was saponificated. After the solvent was removed in vacuo,
water (ca. 200 mL) was added to the solid. Then, green solid was precipi-
tated by the slow addition of aqueous HCl (1m) to the aqueous solution
(pH 3). This was kept still overnight and filtered to give 3a (18.8 mg,
95%). UV/Vis (CH2Cl2): lmax [e (Mꢀ1 cmꢀ1)]=419 (1.93ꢃ105), 476 (2.64ꢃ
105), 522 (4.87ꢃ104), 575 (4.12ꢃ104); Fluorescence (CH2Cl2, lex
=
476 nm): lem =657, 719 nm; 1H NMR (CDCl3): d=ꢀ2.10 (s, 2H, NH),
1.44–1.57 (m, 90H, tBu), 7.22 (d, J=16.1 Hz, 2H, double bond), 7.70 (s,
2H, m-ArH), 7.80 (s, 2H, m-ArH), 7.84 (s, 1H, m-ArH), 8.05 (d, J=
4.6 Hz, 2H, b-H), 8.08–8.15 (m, 10H, o-ArH), 8.19 (d, J=4.6 Hz, 2H, b-
H), 8.63 (d, J=4.1 Hz, 2H, b-H), 8.73 (d, J=4.6 Hz, 2H, b-H), 8.93 (d,
J=4.6 Hz, 2H, b-H), 8.97 (d, J=4.6 Hz, 2H, b-H), 9.51 (s, 2H, b-H), 9.99
(d, J=16.1 Hz, 2H, double bond), 10.85 ppm (s, 1H, meso-H); MS
(MALDI-TOF): m/z (%) calcd for C116H128N8O4Zn: 1760.94 [M]+;
found: 1764.7.
Diporphyrin 12b: Diporphyrin 12a was metallated by zinc(II) according
Diporphyrin diacrylic acid 3b: According to the procedure of 3a, 3b was
prepared from 14b in 98% yield. UV/Vis (CH2Cl2): lmax [e (Mꢀ1 cmꢀ1)]=
421 (1.65ꢃ105), 478 (2.00ꢃ105), 553 (3.30ꢃ104), 580 (3.73ꢃ104); Fluores-
cence (CH2Cl2, lex =478 nm): lem =679 nm (broad); 1H NMR (CDCl3):
d=1.44–1.57 (m, 90H, tBu), 7.25 (d, J=16.1 Hz, 2H, double bond), 7.70
(s, 2H, m-ArH), 7.79 (s, 2H, m-ArH), 7.84 (s, 1H, m-ArH), 8.09–8.12 (m,
14H, b-H and o-ArH), 8.72 (d, J=4.6 Hz, 2H, b-H), 8.74 (d, J=4.6 Hz,
2H, b-H), 9.04 (d, J=4.6 Hz, 2H, b-H), 9.08 (d, J=4.6 Hz, 2H, b-H),
9.52 (s, 2H, b-H), 10.01 (d, J=15.6 Hz, 2H, double bond), 10.85 ppm (s,
1H, meso-H); MS (MALDI-TOF): m/z (%) calcd for C116H126N8O4Zn2:
1822.85 [M]+; found: 1825.2.
to the procedure of 11b (yield: 94%). 1H NMR
ACTHNUTRGNEU(NG CDCl3): d=1.43–1.56
(m, 90H, tBu), 7.68 (s, 2H, m-ArH), 7.71 (s, 2H, m-ArH), 7.82 (s, 1H, m-
ArH), 8.08 (m, 6H, o-ArH and b-H), 8.11 (s, 4H, o-ArH), 8.17 (m, 4H,
o-ArH and b-H), 8.68 (d, J=4.5 Hz, 2H, b-H), 8.76 (d, J=4.1 Hz, 2H, b-
H), 9.02 (d, J=4.6 Hz, 2H, b-H), 9.07 (m, 2H, b-H), 9.18 (d, J=4.1 Hz,
2H, b-H), 9.50 (d, J=4.1 Hz, 2H, b-H), 10.39 ppm (s, 1H, meso-H). MS
(MALDI-TOF): m/z (%) calcd for C110H122N8Zn2: 1682.84 [M]+; found:
1686.7.
Diborylated diporphyrin 13a: Diporphyrin 12a (195 mg, 0.12 mmol,
1.0 equiv), bis(pinacolato)diboron (305 mg, 1.2 mmol, 10.0 equiv), 4,4’-di-
tert-butyl-2,2’-bipyridyl (3.22 mg, 0.012 mmol, 0.1 equiv), and [Ir
ACHTUNGTRENNUNG(cod)]2 (4.0 mg, 0.006 mmol, 0.05 equiv) were placed in a Schlenk flask,
ACHTUNGTRNE(NUNG OMe)-
Diporphyrin bispentadienoate ester 15a: Borylated diporphyrin 13a
(62.0 mg, 0.033 mmol, 1.0 equiv) and the catalyst [Rh(OH)ACHTUNGTRENNUNG(cod)]2
which was purged with argon and then charged with 1,4-dioxane
(4.0 mL). The mixture was stirred at reflux for 48 h under argon. After
removal of the solvent under vacuum, the residue was dissolved in
(1.5 mg, 0.0033 mmol, 0.10 equiv) were placed in a Schlenk flask, which
was then purged with argon and charged with 1,4-dioxane (3.0 mL), H2O
(300 mL), and methyl 2,4-pentadienoate (154 mL, 1.32 mmol, 40 equiv).
The mixture was stirred at 408C for 48 h under argon. After removal of
the solvent under vacuum, the crude product was dissolved in CH2Cl2
(20 mL), and then DDQ (20 mg) was added to oxidize partially saturated
ester products. The mixture was stirred for 10 min and filtered through a
short alumina column (eluent: THF). The crude product was purified by
silica gel chromatography (CH2Cl2/Hexane=2:1) and precipitated from a
mixture of CH2Cl2/MeOH to give 15a (21.0 mg, 29%) in two steps from
12a. 1H NMR (CDCl3): d=ꢀ2.12 (s, 2H, NH), 1.43–1.56 (m, 90H, tBu),
3.91 (br, 6H, OCH3), 6.28 (d, J=15.6 Hz, 2H, double bond), 7.65 (br,
2H, double bond), 7.68 (s, 2H, m-ArH), 7.75 (s, 2H, m-ArH), 7.83 (s,
1H, m-ArH), 8.02 (br, 2H, double bond), 8.07–8.15 (m, 14H, b-H and o-
ArH), 8.61 (m, 2H, b-H), 8.67 (m, 2H, b-H), 8.80 (br, 2H, double bond),
8.93 (d, J=4.6 Hz, 2H, b-H), 8.97 (d, J=4.6 Hz, 2H, b-H), 9.30 (s, 2H, b-
H), 10.52 ppm (br, 1H, meso-H); MS (HR-ESI): m/z (%) calcd for
C122H137N8O4Zn: 1842.0049 [M+H]+; found: 1842.0055.
CHCl3. The solution was filtered through
a pad of florisil (eluent:
CHCl3) to get rid of the catalyst and the insoluble salts. Then, the crude
product was precipitated from a mixture of methanol and dichlorome-
thane to give crude borylated porphyrin 13a (181 mg) as a mixture of di-
borylated and monoborylated diporphyrins with a ratio of 4:1. The mix-
ture was used for the next reaction without separation by preparative
GPC-HPLC.
Diborylated diporphyrin 13b: According to the procedure of 13a, boryla-
tion of 12b (139 mg) afforded 13b (121 mg).
Diporphyrin diacrylate ester 14a: Borylated porphyrin dimer 13a
(81.4 mg, 0.0434 mmol, 1.0 equiv) and the catalyst [Rh(OH)ACTHNUTRGNEUNG(cod)]2
(2.0 mg, 0.00434 mmol, 0.1 equiv) were placed in a Schlenk flask, which
was then purged with argon and charged with 1,4-dioxane (1.5 mL), H2O
(150 mL), and ethyl acrylate (189 mL, 1.736 mmol, 40 equiv). The mixture
was stirred at 408C for 60 h under argon. After removal of the solvent
under vacuum, the crude product was purified by silica gel chromatogra-
phy (CH2Cl2/Hexane=2:1) to give 14a (45.0 mg, 46%) in two steps from
12a as a dark red solid after recrystallization from a mixture of methanol
and dichloromethane. 1H NMR (CDCl3): d=ꢀ2.12 (s, 2H, NH), 1.42–
1.56 (m, 96H, tBu and Et), 4.51 (q, 4H, OCH2), 7.20 (d, J=16.1 Hz, 2H,
double bond), 7.69 (m, 2H, m-ArH), 7.75 (m, 2H, m-ArH), 7.83 (m, 1H,
Diporphyrin bispentadienoate ester 15b: According to the procedure of
1
15a, 15b (18%) was prepared from 13b in two steps from 12b. H NMR
(CDCl3): d=1.43–1.56 (m, 90H, tBu), 3.91 (br, 6H, OCH3), 6.27 (d, J=
15.0 Hz, 2H, double bond), 7.65 (br, 2H, double bond), 7.68 (s, 2H, m-
ArH), 7.75 (s, 2H, m-ArH), 7.83 (s, 1H, m-ArH), 8.08–8.16 (m, 16H, b-
H, o-ArH, and double bond), 8.65 (d, J=4.6 Hz, 2H, b-H), 8.71 (d, J=
1132
www.chemasianj.org
ꢁ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 2009, 4, 1126 – 1133

Post-Modification of meso–meso-Linked Porphyrin Arrays
4.6 Hz, 2H, b-H), 8.80 (br, 2H, double bond), 9.03 (d, J=4.6 Hz, 2H, b-
H), 9.07 (d, J=4.6 Hz, 2H, b-H), 9.31 (s, 2H, b-H), 10.51 ppm (br, 1H,
meso-H); MS (HR-ESI): m/z (%) calcd for C122H135N8O4Zn2: 1902.9105
[M+H]+; found: 1902.9115.
sense, Rh-catalysis offers a more efficient route to utilized b-borylat-
ed porphyrins.
[9] a) R. W. Wagner, J. S. Lindsey, J. Am. Chem. Soc. 1994, 116, 9759–
9760; b) S. Yang, J. Seth, J.-P. Strachan, S. Gentenann, D. Kim, D.
Holten, J. S. Lindsey, D. F. Bocian, J. Porphyrins Phthalocyanines
1999, 3, 117–147.
Diporphyrin bispentadienoic acid 4a: According to the procedure of 3a,
4a was prepared from 15a in 96% yield. UV/Vis (CH2Cl2): lmax [e
(Mꢀ1 cmꢀ1)]=418 (1.47ꢃ105), 487 (2.06ꢃ105), 521 (4.72ꢃ104), 580 (3.57ꢃ
104); Fluorescence (CH2Cl2, lex =487 nm): lem =657, 720 nm; 1H NMR
(CDCl3): d=ꢀ2.11 (s, 2H, N-H), 1.43–1.56 (m, 90H, tBu), 6.33 (d, J=
15.1 Hz, 2H, double bond), 7.69 (s, 2H, m-ArH), 7.74 (dd, J=16.0,
11.5 Hz, 2H, double bond), 7.78 (s, 1H, m-ArH), 7.83 (s, 2H, m-ArH),
8.07–8.15 (m, 14H, b-H and o-ArH), 8.38 (dd, J=15.6, 11.9 Hz, 2H,
double bond), 8.61 (d, J=4.6 Hz, 2H, b-H), 8.69 (d, J=4.6 Hz, 2H, b-H),
8.94 (d, J=4.6 Hz, 2H, b-H), 8.98 (d, J=4.6 Hz, 2H, b-H), 9.02 (d, J=
15.0 Hz, 2H, double bond), 9.40 (s, 2H, b-H), 10.62 ppm (s, 1H, meso-
H); MS (MALDI-TOF): m/z (%) calcd for C120H132N8O4Zn: 1812.97
[M+]; found: 1816.3.
[10] a) H. L. Anderson, S. J. Martin, D. D. C. Bradley, Angew. Chem.
1994, 106, 711–713; Angew. Chem. Int. Ed. Engl. 1994, 33, 655–657;
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wadzka, O. B. Locos, E. M. Ni Mhuircheartaigh, Adv. Mater. 2007,
19, 2737–2774; c) M. J. Frampton, H. Akdas, A. R. Cowley, J. E.
Rogers, J. E. Slagle, P. A. Fleitz, M. Drobizhev, A. Rebane, H. L.
Anderson, Org. Lett. 2005, 7, 5365–5368; d) Y. Matsuzaki, A.
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nomarev, Chem. Lett. 1996, 485–486; c) J. Rodriguez, C. Kirmaier,
M. R. Johnson, R. A. Friesner, D. Holten, J. L. Sessler, J. Am.
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Yamazaki, A. Itaya, M. Murakami, H. Miyasaka, Chem. Eur. J.
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Jeong, D. Kim, Angew. Chem. 2000, 112, 1517–1521; Angew. Chem.
Int. Ed. 2000, 39, 1458–1462; c) Y. H. Kim, D. H. Jeong, D. Kim,
S. C. Jeoung, H. S. Cho, S. K. Kim, N. Aratani, A. Osuka, J. Am.
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Diporphyrin bispentadienoic acid 4b: According to the procedure of 3a,
4b was prepared from 15b in 94% yield. UV/Vis (CH2Cl2): lmax [e
(Mꢀ1 cmꢀ1)]=420 (1.65ꢃ105), 488 (2.18ꢃ105), 554 (3.78ꢃ104), 584 (4.39ꢃ
104); Fluorescence (CH2Cl2, lex =488 nm): lem =656, 687 nm; 1H NMR
(CDCl3): d=1.44–1.57 (m, 90H, tBu), 6.33 (d, J=15.6 Hz, 2H, double
bond), 7.69 (s, 2H, m-ArH), 7.74 (dd, J=15.4, 11.4 Hz, 2H, double
bond), 7.78 (s, 2H, m-ArH), 7.83 (s, 1H, m-ArH), 8.09–8.17 (m, 14H, b-
H and o-ArH), 8.38 (dd, J=15.1, 11.5 Hz, 2H, double bond), 8.67 (d, J=
4.6 Hz, 2H, b-H), 8.72 (d, J=4.1 Hz, 2H, b-H), 9.02 (d, J=15.0 Hz, 2H,
double bond), 9.04 (d, J=4.6 Hz, 2H, b-H), 9.08 (d, J=4.6 Hz, 2H, b-H),
9.41 (s, 2H, b-H), 10.61 ppm (s, 1H, meso-H); MS (MALDI-TOF): m/z
(%) calcd for C120H130N8O4Zn2: 1874.88 [M]+; found: 1879.7.
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Acknowledgements
This work was supported by Grant-in-Aid for Scientific Research from
MEXT, Japan (Nos 18685013 and 20108001 “pi-Space“). H.S. gratefully
acknowledges financial support from the Sumitomo Foundation. J.C.
thanks the JSPS for a postdoctoral fellowship.
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[18] Crystallographic data of 17a: C121H139N8O5Zn, M=1850.77, Mono-
clinic, space group P21/a, a=17.564(5) ꢂ, b=41.173(5) ꢂ, c=
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12438(5) ꢂ3, Z=4, 1calcd =0.988 gcmꢀ3, R1 =0.0920 (I>2s(I)), wR2 =
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halogenated porphyrins, which are not easy to synthesize. In this
Received: February 6, 2009
Published online: May 26, 2009
Chem. Asian J. 2009, 4, 1126 – 1133
ꢁ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
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