Colorimetric calcium-response of β-lactosylated μ-oxo-bis-[5,15- meso-diphenylporphyrinatoiron(III)]

Article abstract of DOI:10.1016/j.tet.2005.05.103

β-Lactosylated 5,15-meso-diphenylporphyrinatoiron(III) chloride was prepared by ironization of the corresponding free base porphyrin having acetylated lactoside-units followed by deacetylation with ammonia in a water-methanol mixture. The resultant 5,15-m

Full text of DOI:10.1016/j.tet.2005.05.103

Tetrahedron 61 (2005) 7783–7788
Colorimetric calcium-response of b-lactosylated
m-oxo-bis-[5,15-meso-diphenylporphyrinatoiron(III)]
*
Teruaki Hasegawa, Munenori Numata, Masayoshi Asai, Masayuki Takeuchi and Seiji Shinkai
Department of Chemistry and Biotechnology, Graduate School of Engineering, Kyushu University, Hakozaki, 6-10-1, Higashi-ku,
Fukuoka 812-8581, Japan
Received 19 April 2005; revised 20 May 2005; accepted 23 May 2005
Available online 29 June 2005
Abstract—b-Lactosylated 5,15-meso-diphenylporphyrinatoiron(III) chloride was prepared by ironization of the corresponding free base
porphyrin having acetylated lactoside-units followed by deacetylation with ammonia in a water–methanol mixture. The resultant 5,15-meso-
bis(b-lactosylphenyl)porphyrinatoiron(III) chloride showed unique colorimetric response to calcium cation. This colorimetric response is
calcium-specific and no other cations, such as sodium, potassium, or magnesium ions induced such colorimetric response. Lines of evidence
including UV–vis spectra under different conditions and TEM images strongly indicate that interdigitations of the corresponding m-oxo-
dimers are responsible for this colorimetric change.
q 2005 Elsevier Ltd. All rights reserved.
1. Introduction
interactions include their multi-valency. It is well-known
that the individual carbohydrate–carbohydrate interactions
are quite weak, multiple copies of such interactions,
however, can overcome such disadvantages of carbo-
hydrates as recognition units. Some artificial models
composed of clustered carbohydrates have been reported
to investigate carbohydrate–carbohydrate interactions. For
example, interactions between Langmuir monolayers
composed of sialyllactosyl-ceramides (GM3) and micells
presenting b-lactosides were investigated by using p-A
isotherm.12–15 However, only limited papers concerning the
detailed mechanisms (packing, geometry, etc.) of such
interactions can be seen in the literature. Such examples
contain (1) a calcium-induced cross-shaped packing of two
SLex-units linked through an alkyl spacer16 and (2) a
calcium-induced parallel packing of b-lactoside-units along
with an a-helical peptide.17
Carbohydrates exist as components of glycoproteins and
glycolipids on cell surfaces and play substantial roles in
various molecular recognition events (fertilization, differ-
entiation, cell–cell adhesion, etc.).1,2 These carbohydrates
were mainly thought to be ligands for carbohydrate
recognition proteins (lectins) for many years. However, an
increasing interest has been placed on carbohydrate–
carbohydrate interactions on cell surfaces, in which
carbohydrates recognize carbohydrates in specific and, in
most case, calcium-dependent manner.3–7
Glycosphingolipids (GSLs) on cell surface aggregate
laterally to form ‘carbohydrate signaling domains’ that is
associated with various signal transferring proteins (c-Src,
FAK, Rho A, etc.).8–11 Interactions between such carbo-
hydrate signaling domains of the neighboring cells are
essential in various cellular recognition events including
compactions of embryos. However, because of the
heterogeneity and fluidity of cell membrane, it is quite
difficult to reveal detailed mechanisms of such carbo-
hydrate–carbohydrate interactions. Simple and well-
designed model systems are, therefore, highly required for
the detailed and quantitative investigations.
In a series of our research on artificial receptors having
unique allosterisms,18,19 we focused a new system based on
m-oxo-bis[porphyrinatoiron(III)]s to investigate the detailed
mechanisms of carbohydrate–carbohydrate interactions.
It is well-known that porphyrinatoiron(III) can dimerize in
a basic solution to form the corresponding m-oxo-
bis[porphyrinatoiron(III)]s, in which two porphyrinatoirons
are connected through a Fe–O–Fe bond.20 Since these
porphyrin-units can rotate through this axis, m-oxo-
bis[porphyrinatoiron(III)] can afford useful scaffold to
construct unique host molecules with multiple binding
sites and allosterism, which should be quite advantageous to
The most interesting aspects of carbohydrate–carbohydrate
Keywords: Carbohydrate–carbohydrate interactions.
*
Corresponding author. Tel. C81 92 642 3585; fax: C81 92 642 3611;
e-mail: seijitcm@mbox.nc.kyush-u.ac.jp
0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2005.05.103

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T. Hasegawa et al. / Tetrahedron 61 (2005) 7783–7788
detect weak carbohydrate–carbohydrate interactions.
Furthermore, host–guest bindings would be easily moni-
tored by UV–vis and/or CD spectroscopy. Herein, we report
an unique calcium-induced colorimetric response of m-oxo-
bis[5,15-meso-diphenylporphynatoiron(III)] having four
b-lactoside-appendages (Fig. 1).
4-methoxybenzaldehyde (two steps) through the similar
synthetic scheme.
In our solubility test, Por-Lac was well-soluble in aqueous
solvents containing 50% organic media such as N-methyl-
pyroridone (NMP), N,N-dimethylformamide (DMF),
dimethylsulfoxide (DMSO), etc. All these yellow solutions
looked transparent, however, the UV–vis spectra indicated
significant difference among them. For example, Por-Lac in
aqueous DMF showed a sharp Soret-band adsorption at
400 nm, whereas the Soret-band was strongly suppressed in
aqueous NMP. These data indicate that Por-Lac is mono-
dispersed in aqueous DMF but aggregated in aqueous NMP.
Of our great interest, the aggregation in aqueous NMP is
quite essential for the calcium-response of Por-Lac, as
described below.
Por-Lac showed unexpected and unique colorimetric-
response to calcium ions, that is, addition of CaCl2 to Por-
Lac in Tris–HCl buffer (50 mM, pH 9.6, 50 v/v% NMP)
induced a gradual change in the solution color from orange
to pink, as shown in Figure 2a. The colorimetric change
was slow and it required almost 10 h to be equilibrated.
A UV–vis spectrum of Por-Lac (Fig. 2b) in the presence of
Ca2C showed a new peak at 525 nm. The colorimetric
response was specific for calcium ion, and no other ions,
such as potassium, sodium, nor magnesium could induce
such a colorimetric response. The colorimetric response
could be induced even by low calcium-concentrations (KaZ
660 MK1).21
Figure 1. Structure of 5,15-meso-diphenylporpyrinatoiron(III) having two
b-lactosides (Por-Lac) and its dimerization in a basic solution to form the
corresponding m-oxo-dimer.
2. Results and discussion
per-Acetyl-a-lactosyl-bromide (1) was coupled with
4-hydroxybenzaldehyde in a biphasic mixture of CH2Cl2
and aqueous Na2CO3 containing tetrabutyl ammonium
bromide to afford per-acetyl-b-lactosyl-benzaldehyde (2)
in 69% yield (Scheme 1). Lyndsey-condensation of the
per-acetyl-b-lactosyl-benzaldehyde (1.0 equiv) and
dipyrromethane (1.0 equiv) in dry CH2Cl2 containing
trifluoroacetic acid (1.2 equiv) was followed by oxidation
by p-chloranil to afford 5,15-meso-bis(p-per-acetyl-b-
lactosylphenyl)porphyrin (3). The corresponding por-
phyrinatoiron(III) (4) was yielded by treating it with
anhydrous FeCl2 in DMF at 60 8C. The following
deacetylation in aqueous ammonia in methanol resulted in
5,15-meso-bis(b-lactosylphenyl)porphyrinatoiron(III) (Por-
Lac, 5). We also synthesized a porphyrinatoiron(III)
without carbohydrate-unit (Por-OMe, 7) starting from
Figure 2. (a) Colorimetric response of Por-Lac to NaCl, KCl, CaCl2 and
MgCl3: [Por-Lac]Z2.4!10K4 M, [KCl], [NaCl], [CaCl2] or [MgCl3]Z
50 mM, 25 8C, Tris–HCl (pH 9.6, 50 mM, 50 v/v% NMP), 12 h after salt
addition and (b) their UV–vis spectra.
To clarify the origin of this unique colorimetric response,
we measured UV–vis spectra of Por-Lac in various solvent
systems with different pH-values and organic co-solvents.
As shown in Figure 3, the colorimetric calcium-response is
strongly dependent on pH-values and appeared only under
basic conditions (OpH 8.5), confirming that the correspond-
ing m-oxo-dimer is responsible for the calcium-response. In
addition to the pH-dependence, organic co-solvents also
have a critical influence on the calcium-response. Figure 4
shows the UV–vis spectra of Por-Lac in Tris–HCl buffer
(50 mM, pH 9.6) containing 50 mM CaCl2 and 50 v/v%
organic co-solvent (varying the DMF/NMP ratio). With
increasing NMP ratio, the Soret-band is gradually weakened
and the calcium-response simultaneously appears, indi-
cating that the face-to-face interactions between porphyrin-
units are essential for the calcium-response.
Scheme 1. Synthesis of 5,15-meso-bis(b-lactosylphenyl)porpyrinatoiron-
(III) (Por-Lac): (i) 4-hydroxybenzaldehyde, TBAB, Na2CO3, CH2Cl2/H2O,
rt; (ii) dipyrromethane, TFA, CH2Cl2, rt, then p-chloranil, rt; (iii) FeCl2,
DMF, 60 8C; (iv) aqueous ammonia, MeOH, rt.

T. Hasegawa et al. / Tetrahedron 61 (2005) 7783–7788
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Figure 3. (a) UV–vis spectra of Por-Lac under various pH-conditions in the presence of CaCl2 and (b) pH-dependent Abs (525 nm) of PorLac: [Por-Lac]Z
2.4!10K4 M, [CaCl2]Z50 mM, 25 8C, Tris–HCl (pH 9.6, 50 mM, 50 v/v% NMP).
Figure 4. (a) UV–vis spectra of Por-Lac in Tris–HCl buffer containing 50 v/v% organic co-solvents (varying NMP/DMF ratio) in the presence of CaCl2, and
(b) Solvent-dependency of the UV intensities (400 and 525 nm): [Por-Lac]Z2.4!10K4 M, [CaCl2]Z50 mM, 25 8C, Tris–HCl (pH 9.6, 50 mM, 50 v/v%
organic co-solvents).
It should be noted that EDTA-addition could quench the
colorimetric response and change the solution color from
pink to orange, confirming that the origin of this
colorimetric change can be attributed to the non-covalent
interaction between Por-Lac and calcium ions (see ESI).
negligible calcium-response (Fig. 5). These data strongly
suggest that carbohydrate-units play important roles in
colorimetric calcium-response (calcium-binding itself and/
or the resulting face-to-face interactions).
CD spectra of Por-Lac in the presence of calcium ions
showed a new CD signal at 525 nm, supporting that chirally
twisted packing of porphyrin-units induced by calcium
cation (Fig. 6). Together with these data, we assume that the
new peak should be assignable to the red-shifted Soret-band
arising from J-aggregation of the m-oxo-dimer. Although
Structural modification of Por-Lac also provides useful
information about the nature of this calcium-response.
Porphyrinatoiron(III) having no carbohydrate-units (Por-
OMe as well as commercially available 2,3,7,8,12,13,17,18-
octaethyl-porphyrinatoiron(III) chloride) showed no or
Figure 5. UV–vis spectra of Por-Lac (plane line), Por-OMe (dotted line),
and Por-OEt8 (thin line), in the presence of CaCl2: [Por-derivatives]Z2.4!
10K4 M, [CaCl2]Z50 mM, 25 8C, Tris–HCl (pH 9.6, 50 mM, 50 v/v%
NMP).
Figure 6. CD spectra of Por-Lac in the presence (plane line) and absence
(dotted line) of CaCl2: [Por-Lac]Z2.4!10K4 M, [CaCl2]Z50 mM, 25 8C,
Tris–HCl (pH 9.6, 50 mM, 50 v/v% NMP).

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T. Hasegawa et al. / Tetrahedron 61 (2005) 7783–7788
more data should be collected to firmly establish the detailed
mechanism, this slided orientation (J-aggregation) of m-oxo-
Por-Lac can reasonably explain the red-shifted Soret-band
to induce the colorimetric change.
In addition to these data, the stoichiometric analysis (Job
plot) showing ca. 1:2 stoichiometry between the m-oxo-Por-
Lac and Ca2C provides one possible mechanism (Fig. 7).
In this picture, calcium ions interact with two carbohydrate-
units to fix the molecular rotation and then, the resulting
m-oxo-Por-Lacs are interdigitated owing to the hydrophobic
interactions among porphyrin planes. It should be empha-
sized here, that such interdigitations can be achieved only
when the two pairs of b-lactoside-appendages were packed
in a parallel fashion and huge hydrophobic clefts were
formed at the both sides of the rotation-fixed m-oxo-dimer.
Figure 8. TEM images of Por-Lac in the presence (a and b) and absence (c)
of CaCl2: [Por-Lac]Z2.4!10K4 M, [CaCl2]Z50 mM, 25 8C, Tris–HCl
(pH 9.6, 50 mM, 50 v/v% NMP), 12 h after salt addition.
Figure 7. One possible mechanism to induce the colorimetric calcium-
response, in which (a) two calcium cations binds to the b-lactoside-
appendages of m-oxo-Por-Lac to (b) fix the molecular rotation followed by
(c) interdigitation of two such fixed m-oxo-Por-Lacs resulting a
dimerization and (d) further oligomerizations.
spherical nor nanotubular structure was observed (Fig. 8c).
We assumed that the repeating interdigitations of m-oxo-
Por-Lacs (Fig. 7d) should play substantial roles in
constructions of such unique and definite superstructures.
We also measured cold spray ionization (CSI) mass spectra
to support the above idea. Por-Lac (m/zZ1196.30) in
aqueous NMP (pH 9.6) in the absence of CaCl2 showed no
clear peak in the range of m/zZ500–3000, supporting its
aggregation under this condition. However, Por-Lac in the
presence of CaCl2 (50 mM) showed clear peaks at m/zZ
271.84, 372.39, and 472.96 that can be assigned to the
oligomers of m-oxo-Por-Lac associated with calcium ions
and water molecules ((m-oxo-Por-Lac)n(Por-Lac)1(H2O)2-
3. Conclusion
We designed the m-oxo-bis[5,15-meso-bis(b-lactosyl-
phenyl)porphyrinatoiron(III)] to detect calcium-mediated
lactoside–lactoside interactions based on its CD spectral
changes. Although such a calcium-induced CD spectral
changes can be observed, we also found its unexpected
and unique colorimetric response for calcium ions. The
mechanism we proposed in Figure 7, that is calcium-
mediated parallel packings of two b-lactoside-appendages
and the resultant interdigitations of the rotation-fixed m-oxo-
dimers, can reasonably explain the observed spectral
changes. Furthermore, the calcium-induced morphological
change from amorphous aggregates to tubular/spherical
superstructures is also quite of interest since such calcium-
dependent morphological changes are frequently observed
in natural cell lines (compaction of embryos, etc.), although
their mechanisms are quite different from each other.
(Ca2C
)12 where nZ2 (calcd 272.06), 3 (calcd 372.42), or 4
(472.78), respectively).
Of our great interest, the calcium-addition also has critical
impacts on morphologis of Por-Lac aggregates. Figure 8a
and b show transmission electron microscopic (TEM)
images of Por-Lac aggregates in the presence of CaCl2, in
which some nanotubular structures, along with predominant
spherical ones, were observed. On the contrary, Por-Lac
without CaCl2 showed amorphous aggregates, and neither

T. Hasegawa et al. / Tetrahedron 61 (2005) 7783–7788
7787
4. Experimental
4.1.3. 5,15-meso-Bis(p-2,3,6,20,30,40,60-hepta-O-acetyl-b-
lactosylphen0yl)porp0hyrinatoiron(III) (4). To 5,15-meso-
bis(p-2,3,6,2 ,30,40,6 -hepta-O-acetyl-lactosyl)phenyl)por-
phyrin (139 mg) in dry DMF (20 ml), anhydrous FeCl2
(310 mg) was added and the stirring was continued for 6 h at
80 8C under N2 atmosphere. The resulting solution was
diluted with ethyl acetate and washed with NaCl saturated
aqueous solution several times. The organic layer was dried
over Na2SO4, filtered, evaporated to dryness. The residues
was purified by chromatography on a silica gel column
(30 cm long; 3 cm i.d.; CHCl3/MeOHZ20:1w9:1 in v/v) to
give 5,15-meso-bis-(p-2,3,6,20,30,40,60-hepta-O-acetyl-
lactosylphenyl)porphyrinatoiron(III) as a orange powder
4.1. General
1H NMR spectra were acquired on a Brucker DRX600
(Brucker Co., Ltd) in CDCl3 at 600 MHz. The chemical
shifts were reported in ppm (d) relative to Me4Si. Circular
dichroism (CD) spectra were measured on JASCO 720WI
Circular Dichroism Spectrometer. Matrix assisted laser
desorption ionization time-of-flight (MALDI-TOF) mass
spectra were recorded on PerSeptive Biosystems Voyager-
DERP Biospectrometry Workstation. Silica gel 60 N
(particle size 40–50 mm) for column chromatography was
purchased from KANTO CHEMICAL Co. INC. Thin-layer
chromatography (TLC) was carried out with Merck TLC
(78%): [M]CZ1785.1 (calcd 1785.4); IR (ATR, cmK1
)
1751 (acetyl).
aluminum sheets pre-coated with silica gel 60 F254
.
4.1.4. 5,15-meso-Bis(b-lactosylphenyl)por0phyrinatoiron-
(III) (5). To 5,15-meso-bis(p-2,3,6,20,3 ,40,60-hepta-O-
acetyl-b-lactosylphenyl)porphyrinatoiron(III) (32 mg) in
methanol (20 ml) aqueous ammonia (10 ml) was added
and the mixture was stirred at room temperature for 3 h. The
resulting mixture was condensed by evaporation to remove
ammonia vapor and then, diluted with water and lyophilized
to give 5,15-meso-bis(b-lactosylphenyl)porphyrinatoiron-
(III) as a brown powder (quant.). We could not confirm
the purity of this final product owing to its magnetic nature.
The purity of this compound was, therefore, evaluated by
HPLC analysis that showed only one, clear, and symmetri-
cal peak (see ESI): [MCNa]CZ1198.1 (calcd 1197.9); IR
(ATR, cmK1) 3218 (–OH).
4.1.1. p-(2,3,6,20,30,40,60-Hepta-O-acetyl-b-lactosyl)benz-
aldehyde (2). To 2,3,6,20,30,40,60-hepta-O-acetyl-lactosyl
bromide (18.03 g) and 4-hydroxybenzaldehyde (5.12 ml) in
the mixture of CH2Cl2 (50 ml) and aqueous Na2CO3
(70 ml), tetrabutylammonium bromide (0.08 g) was added
and the vigorous stirring was continued for 24 h at room
temperature. The resulting mixture was diluted with CH2Cl2
and washed with 0.5 N HCl aq and NaHCO3 aq repeatedly.
The organic layer was dried over anhydrous Na2SO4,
filtered, evaporated, and purified through column chroma-
tography on silica-gel (CHCl3/MeOHZ25:1) to give
p-(2,3,6,20,30,40,60-hepta-O-acetyl-b-lactosyl)benzaldehyde
1
(69%): H NMR(CDCl3, TMS): 9.93 (s, 1H), 7.85 (d, JZ
8.51 Hz, 2H), 7.08 (d, JZ8.66 Hz, 2H), 5.37 (d, JZ
3.10 Hz, 1H), 5.31 (t, JZ8.33 Hz, 1H), 5.21 (t, JZ7.49 Hz,
1H), 5.19 (d, JZ7.69 Hz, 1H), 5.14 (dd, JZ7.93, 10.34 Hz,
1H), 4.98 (dd, JZ3.36, 10.46 Hz, 1H), 4.52 (d, JZ7.79 Hz,
1H), 4.52 (dd, JZ1.21, 13.30 Hz, 1H), 4.16 (dd, JZ6.44,
10.84 Hz, 1H), 4.14 (dd, JZ4.64, 10.49 Hz, 1H), 4.09 (dd,
JZ7.41, 11.13 Hz, 1H), 3.92 (t, JZ9.73 Hz, 1H), 3.91–3.89
(m, 1H), 3.87–3.84 (m, 1H), 2.17 (s, 3H), 2.09 (s, 3H), 2.08
(s, 3H), 2.07 (s, 9H), 1.98 (s, 3H); [MCH]CZ741.6 (calcd
741.7); IR (ATR, cmK1) 1749 (acetyl).
4.1.5. 5,15-meso-Bis(p-methoxyphenyl)porphyrin (6). To
p-anisaldehyde (0.89 ml) and dipyrromethane (1.1 g) in dry
CH2Cl2 (230 ml) trifluoroacetic acid (0.60 ml) was added.
The stirring was continued for 15 h at room temperature
under N2 atmosphere and then, p-chloranil (1.0 g) was
added. After additional 1 h stirring, triethylamine was added
and the resulting mixture was evaporated to dryness.
Insoluble materials were separated through silica-gel
packed column using chloroform as an eluent. The fractions
were combined, evaporated, and purified by chromato-
graphy on a silica gel column (30 cm long; 3 cm i.d.,
chloroform/methanol (25:1)) to give 5,15-meso-bis(p-
4.1.2. 5,15-meso-Bis(p-2,3,6,20,30,40,60-hepta-O-acety0l-b-
lactosylphenyl)porphyrin (3). To p-(2,3,6,20,30,4 ,60-
hepta-O-acetyl-b-lactosyl)benzaldehyde (1.01 g) and dipyr-
romethane (0.20 g) in dry CH2Cl2 (40 ml), trifluoroacetic
acid (125 ml) was added. The stirring was continued for 15 h
at room temperature under N2 atmosphere and then, p-
chloranil was added. After additional 1 h stirring, triethyl-
amine was added and the resulting mixture was evaporated
to dryness. Insoluble materials were separated through
silica-gel packed column using chloroform as an eluent.
The fractions were combined, evaporated, and purified by
chromatography on a silica gel column (30 cm long; 3 cm
i.d.; toluene/ethyl acetateZ2:3 in v/v) to give 5,15-meso-
di(lactosylphenyl)-porphyrin as a purple powder (19%): 1H
NMR(CDCl3, TMS): 10.31 (s, 2H), 9.39 (d, JZ2.70 Hz,
4H), 9.07 (d, JZ2.70 Hz, 4H), 8.19 (d, JZ7.62 Hz, 4H),
7.42 (d, JZ7.62 Hz, 4H), 5.49–5.40 (m, 8H), 5.20 (t, JZ
9.09 Hz, 2H), 5.03 (d, JZ10.42 Hz, 2H), 4.66 (d, JZ
11.69 Hz, 2H), 4.61 (d, JZ7.86 Hz, 2H), 4.32–3.95 (m,
12H), 2.24 (s, 6H), 2.20 (s, 6H), 2.17 (s, 12H), 2.12 (s, 6H),
2.10 (s, 6H), 2.00 (s, 6H); [MCH]CZ1732.4 (calcd
1732.6); IR (ATR, cmK1) 1757 (acetyl).
1
methoxyphenyl)porphyrin as a purple powder (23%): H
NMR(CDCl3, TMS): 10.23 (s, 2H), 9.32 (d, JZ4.4 Hz, 4H),
9.04 (d, JZ4.3 Hz, 4H), 8.12 (d, JZ8.1 Hz, 4H), 7.28 (d,
JZ7.8 Hz, 4H), 4.06 (s, 6H), K3.15 (s, 2H); [MCH]CZ
523.3 (calcd 523.3).
4.1.6. 5,15-meso-Bis(p-methoxyphenyl)porphyrinato-
iron(III) (7). To 5,15-meso-bis(p-methoxyphenyl)por-
phyrin (210 mg) in dry DMF (40 ml), anhydrous FeCl2
(510 mg) was added and the stirring was continued for 6 h at
80 8C under N2 atmosphere. The resulting solution was
diluted with ethyl acetate and washed with NaCl saturated
aqueous solution several times. The organic layer was dried
over Na2SO4, filtered, evaporated to dryness. The residue
was purified by chromatography on a silica gel column
(30 cm long; 3 cm i.d.; CHCl3/MeOHZ20:1 in v/v) to give
5,15-meso-bis(p-methoxyphenyl)-porphyrinatoiron(III) as a
orange powder (69%): [M]CZ577.3 (calcd 577.1).

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7. Zheng, M.; Hakomori, S. Arch. Biochem. Biophys. 2000, 93.
Acknowledgements
8. Tillack, T. W.; Allietta, M.; Moran, R. E.; Young, W. W.
J. Biochim. Biophys. Acta 1983, 733, 15.
We are grateful to Prof. T. Hayashi of Kyushu University,
Prof. H. Tamiaki of Ritsumeikan University and Prof. M.
Nango of Nagoya Institute of Technology for their kindful
suggestions. This work was supported by the Japan Science
and Technology Corporation.
9. Rock, P.; Alietta, M.; Young, W. W. J.; Thompson, T. E.;
Tillack, T. W. Biochemistry 1990, 29, 8484.
10. Rock, P.; Alietta, M.; Young, W. W. J.; Thompson, T. E.;
Tillack, T. W. Biochemistry 1991, 30, 19.
11. Iwabuchi, K.; Yamamura, S.; Prinetti, A.; Handa, K.;
Hakomori, S. J. Biol. Chem. 1998, 273, 9130.
12. Santacroce, P. V.; Basu, A. Angew. Chem., Int. Ed. 2003, 42,
95.
Supplementary data
13. Matsuura, K.; Kitakouji, H.; Oda, R.; Morimoto, Y.; Asano,
H.; Ishida, H.; Kiso, M.; Kitajima, K.; Kobayashi, K.
Langmuir 2002, 18, 6940.
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.tet.2005.05.
103
14. Esnault, J.; Mallet, J.-M.; Zhang, Y.; Sinay, P.; Bouar, T. L.;
Pincet, F.; Perez, E. Eur. J. Org. Chem. 2001, 253.
15. Siuzdak, G.; Ichikawa, Y.; Caulfield, T. J.; Munoz, B.; Wong,
C.-H.; Nicolaou, K. C. J. Am. Chem. Soc. 1993, 115, 2887.
16. Geyer, A.; Gege, C.; Schmidt, R. R. Angew. Chem., Int. Ed.
2000, 39, 3.
References and notes
17. Hasegawa, T.; Sasaki, T. Chem. Commun. 2003, 8, 978.
18. Sugasaki, A.; Ikeda, M.; Takeuchi, M.; Shinkai, S. Angew.
Chem., Int. Ed. 2000, 39, 3839.
1. Dwek, R. A. Chem. Rev. 1996, 96, 683.
2. Mammen, M.; Choi, S.-K.; Whitesides, G. M. Angew. Chem.,
Int. Ed. 1998, 37, 2754.
19. Sugasaki, A.; Ikeda, M.; Takeuchi, M.; Koumoto, K.; Shinkai,
S. Tetrahedron 2000, 56, 4717.
3. Kojima, N.; Hakomori, S. J. Biol. Chem. 1991, 266, 17552.
4. Iwabuchi, K.; Handa, K.; Hakomori, S. J. Biol. Chem. 1998,
273, 33766.
20. Takeuchi, M.; Imada, T.; Seiji, S. J. Am. Chem. Soc. 1996, 118,
10658.
5. Hakomori, S.; Nudelman, E. D.; Levery, S. B.; Solter, D.;
Knowles, B. B. Biochem. Biophys. Res. Commun. 1981, 100,
1578.
21. We measured the UV–vis spectra of Por-Lac under various
concentrations of CaCl2 and carried out the computational
curve fitting based on Hill plot.
6. Nores, G. A.; Dohi, T.; Taniguchi, M.; Hakomori, S.
J. Immunol. 1987, 139, 3171.