Meso-trifluoromethyl-substituted expanded porphyrins

Article abstract of DOI:10.1002/chem.200600158

A series of meso-trifluoromethyl-substituted expanded porphyrins, including N-fused [24]pentaphyrin 3, [28]hexaphyrin 4, [32]heptaphyrin 5, [46]decaphyrin 6, and [56]dodecaphyrin 7, were synthesized by means of an acid-catalyzed one-pot condensation reaction of 2-(2,2,2-trifluoro-1-hydroxyethyl)pyrrole (1) as the first examples bearing meso-alkyl substituents. Besides these products, porphyrin 2 and two calix[5]phyrins 8 and 9 were also obtained. [28]Hexaphyrin 4 was quantitatively oxidized to [26]hexaphyrin 14 with MnO₂. These expanded porphyrins have been characterized by mass spectrometry, ¹H and ¹⁹F NMR spectroscopy, and UV/Vis spectroscopy. The single-crystal structures have been determined for 3, 4, 6, 7, and 14. The N-fused [24]pentaphyrin 3 displays a distorted structure containing a tricyclic fused moiety that is similar to those of mejo-aryl-substituted counterparts, whereas 8 and 9 are indicated to take roughly planar conformations with an inverted pyrrole opposite to the sp³-hybridized meso-carbon atom. Both [28]- and [26]hexaphyrins 4 and 14 have figure-of-eight structures. Solid-state structures of the decaphyrin 6 and dodecaphyrin 7 are remarkable, exhibiting a crescent conformation and an intramolecular two-pitch helical conformation, respectively.

Full text of DOI:10.1002/chem.200600158

FULL PAPER
DOI: 10.1002/chem.200600158
meso-Trifluoromethyl-Substituted Expanded Porphyrins
Soji Shimizu, Naoki Aratani, and Atsuhiro Osuka*[a]
Abstract: A series of meso-trifluoro-
methyl-substituted expanded porphy-
rins, including N-fused [24]pentaphyrin
3, [28]hexaphyrin 4, [32]heptaphyrin 5,
[46]decaphyrin 6, and [56]dodecaphyrin
7, were synthesized by means of an
acid-catalyzed one-pot condensation
reaction of 2-(2,2,2-trifluoro-1-hydroxy-
with MnO2. These expanded porphyr-
ins have been characterized by mass
spectrometry, 1H and 19F NMRspec-
those of meso-aryl-substituted counter-
parts, whereas 8 and 9 are indicated to
take roughly planar conformations with
an inverted pyrrole opposite to the sp3-
hybridized meso-carbon atom. Both
[28]- and [26]hexaphyrins 4 and 14
have figure-of-eight structures. Solid-
state structures of the decaphyrin 6 and
dodecaphyrin 7 are remarkable, exhib-
iting a crescent conformation and an
intramolecular two-pitch helical confor-
mation, respectively.
A
The single-crystal structures have been
determined for 3, 4, 6, 7, and 14. The
N-fused [24]pentaphyrin 3 displays a
distorted structure containing
a tri-
A
cyclic fused moiety that is similar to
bearing meso-alkyl substituents. Be-
sides these products, porphyrin 2 and
two calix[5]phyrins 8 and 9 were also
obtained. [28]Hexaphyrin 4 was quanti-
tatively oxidized to [26]hexaphyrin 14
Keywords: aromaticity
tion macrocyclic ligands
porphyrinoids
· conjuga-
·
·
Introduction
oped in recent years,[1,7–14] but homologous expanded por-
phyrins that consist of more than four pyrrolic units with the
regular alternate arrangement of pyrrole groups and meth-
Expanded porphyrins[1] are emerging functional molecules
in light of their potential utilities in a range of applications,
such as anion receptors,[2] transition or lanthanoid ion che-
lates,[3] photodynamic therapy sensitizers,[4] and magnetic
resonance imaging (MRI) contrast agents.[5] In addition,
their large two-photon absorption cross sections have been
recently revealed as promising attributes for their uses in
three-dimensional microfabrication, optical data storage,
and optical limiting.[6] These fascinating properties have en-
couraged synthetic efforts towards a variety of expanded
porphyrins differing in ring size, ring connectivity, peripheral
substituent, and core modification. As a consequence, many
carefully designed expanded porphyrins have been devel-
A
expanded porphyrins may be formed along with a porphyrin
by one-pot condensation of pyrrole and aldehyde, only three
reactions have been reported that are effective for the syn-
thesis of homologous expanded porphyrins; 1) the reaction
of pyrrole with 2,6-disubstituted benzalde
hyde,[15a] 2) the re-
G
action of 3,4-difluoropyrrole with pentafluorobenzal-
dehyde,[15b] and 3) the reaction of 3,4-diethylpyrrole with
triisopropylsilylpropynal.[16] These expanded porphyrins
allow systematic investigations on the optical, electrochemi-
cal, and coordination properties upon change in number of
pyrrolic units, for which meso-substituents are expected to
play a profound impact.
With this background, we wished to prepare meso-alkyl-
substituted homologous expanded porphyrins. In our synthe-
ses of meso-aryl-substituted expanded porphyrins, the use of
aromatic aldehydes that bear electron-deficient substituents
at 2- and 6-positions is crucial,[15] since 2-halobenzaldehyde,
2,4-dihalobenzaldehyde, or 2,6-dimethylbenzaldehyde failed
to give expanded porphyrins under similar conditions. These
results imply that the presence of bulky substituents at the
meso-positions in porphyrinogen precursors may shift an
acid-formed equilibrated mixture favorably toward cyclic ex-
[a] S. Shimizu, Dr. N. Aratani, Prof. A. Osuka
Department of Chemistry
Graduate School of Science, Kyoto University
and
Core Research for Evolutional Science and Technology (CREST)
Japan Science and Technology Agency, 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://www.chemeurj.org/ or from the author.
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panded porphyrinogens, or the electron-deficient substitu-
ents either on aromatic aldehyde or pyrrole may tend to sta-
bilize such precursors. This consideration drove us to exam-
ine the synthesis of meso-trifluoromethyl-substituted ex-
panded porphyrins. A trifluoromethyl group is sufficiently
electron-deficient and certainly sterically demanding, which
may meet the above synthetic requirements. In this paper,
the syntheses of meso-trifluoromethyl-substituted expanded
porphyrins are described as the first examples bearing meso-
alkyl substituents;[17] 2-(2,2,2-trifluoro-1-hydroxyethyl)pyr-
role (1) or 2-(2,2,2-trifluoro-1-hydroxyethyl)-6-trifluorome-
thyldipyrromethane (11) were successfully employed as key
precursors. Expanded porphyrins reported in this paper are
named partly based on the nomenclature put forward by
(DDQ; 2.3 equiv) for 6 h at room temperature, the reaction
mixture was separated by repeated chromatography over
silica gel and gel permeation chromatography (GPC) col-
umns to give meso-trifluoromethyl-substituted expanded
porphyrins (porphyrin 2 (2–3%), N-fused pentaphyrin 3 (5–
10%), hexaphyrin 4 (3–4%), heptaphyrin 5 (4–6%), decap-
hyrin 6 (~1%), and dodecaphyrin 7 (~1%), Scheme 1).[19]
In addition to these fully conjugated expanded porphyrins,
meso-hydroxy-substituted calix[5]phyrin 8 was also obtained
in 4% yield. Methanesulfonic acid (MSA) was found to be
also effective for this reaction. With a catalytic amount of
MSA (0.4 equiv)[20] under the similar conditions, the reaction
gave 2, 3, 4, 5, 6, 7, and 8 in 2, 2, 2, 6, ~1, ~1, and 4%
yields, respectively, along with another calix[5]phyrin 9 in
G
Franck and Nonn for porphy
A
2% yield.
Ring-size selective syntheses[21] of meso-trifluoromethyl-
substituted expanded porphyrins have been explored by
using oligopyrrolic precursors 11, 12, and 13 (Schemes 2 and
3). meso-Trifluoromethyl-substituted dipyrromethane[22] 10
was treated with four equivalents of TFAA in THF at
À208C to give 2-trifluoroacetyl-6-trifluoromethyldipyrro-
Results and Discussion
Syntheses: 2-(2,2,2-Trifluoro-1-hydroxyethyl)pyrrole (1) was
prepared from acylation reaction of pyrrole with trifluoro-
acetic anhydride (TFAA) in benzene at 08C, followed by re-
duction with NaBH4 in THF/MeOH.[18] After acid-catalyzed
cyclization reactions of 1 had been examined for the synthe-
sis of expanded porphyrins under various reaction condi-
tions, we found the reaction conditions that allowed the syn-
thesis of a series of meso-trifluoromethyl-substituted ex-
panded porphyrins in small but reproducible yields. A solu-
tion of 1 (66.6 mm) in CH2Cl2 was refluxed with an equiva-
lent amount of HCl (1.0m in diethyl ether) for 12 h. After
oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone
A
with NaBH4 to its carbinol 11. Self-condensation reaction of
11 with one equivalent of HCl in refluxing CH2Cl2 provided
a series of meso-trifluoromethyl-substituted expanded por-
phyrins bearing an even number of regularly arranged pyr-
role rings and methine carbon atoms (2 1–3%, 4 8–10%, 6
~1%, and 7 ~1%, Scheme 2). When treated with excess
pyrrole (11 equiv) and HCl (0.9 equiv) in THF under reflux-
ing conditions for 4 h, the dipyrromethane derivative 11 was
converted to meso-trifluoromethyl-substituted tripyrrometh-
Scheme 1. Synthesis of a series of meso-trifluoromethyl-substituted expanded porphyrins.
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Porphyrinoids
FULL PAPER
Scheme 2. Ring-size selective synthesis from 11.
A
conditions similar to monoacylation of 10, the tripyrrome-
thane 12 gave a mixture of mono- and diacylated tripyrro-
methane that was hard to separate. Diacylation reaction of
10 with an excess amount of TFAA in toluene at room tem-
perature quantitatively afforded 2,2’-bis(trifluoroacetyl)-6-
trifluoromethyldipyrromethane, which was then reduced to
dipyrromethane dicarbinol 13. A condensation reaction of
12 and 13 with 0.5 equivalents of MSA gave 3, 8, and 9 in 1–
2%, ~1.5%, and 4–5% yields, respectively (Scheme 3),
while the reaction with one equivalent of HCl gave 9 in a
better yield (5–7%).
Structural characterization of N-fused [24]pentaphyrin 3:
High-resolution electrospray ionization time-of-flight (HR-
ESI-TOF) mass spectroscopy revealed the parent ion peak
of 3 at 726.0771 ([MÀH]À, calcd for C30N5F15H11, 726.0780).
X-ray diffraction analysis has unambiguously revealed a dis-
torted N-fused pentaphyrin (NFP5) structure of 3 (Figure 1),
in which the nitrogen atom of the pyrrole B is attached at
the b-position of the pyrrole A to form a fused tricyclic seg-
ment and the pyrroles A, C, and D possess NH hydrogen
atoms, thus indicating its formulation as a [24]NFP5. The tilt-
ing angles of the pyrroles from the macrocyclic mean-plane
defined by 30 core atoms are large; 18.68 (pyrrole E), 25.68
(pyrrole D), and 76.88 (pyrrole C). Thus, the entire structure
Figure 1. X-ray crystal structure of 3, top view (left) and side view
(right). The thermal ellipsoids are scaled to the 50% probability level.
meso-Trifluoromethyl substituents are omitted in the side view for clarity.
is quite distorted, being unfavorable for overall macrocyclic
1
conjugation. Reflecting this structural feature, the H NMR
spectrum of 3 in CD2Cl2 at room temperature contained
three NH proton signals at d=9.26, 8.62, and 8.05 ppm and
nine b-CH protons resonated at d=7.80, 7.63–7.59 (2H),
7.52, 7.28, 7.12, 6.43, 5.95, and 3.09 ppm. These data indicate
the nonaromatic character of 3 in contrast to the antiaroma-
ticity of meso-aryl-substituted [24]NFP5.[23,24] The most up-
Scheme 3. Ring-size selective synthesis from 12 and 13.
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4911

A. Osuka et al.
field shifted peak at d=3.09 ppm has been assigned to the
inner b-CH proton of the pyrrole A (H(1) in Figure 1),
which exhibits correlation with the outer NH at d=
8.62 ppm in the H-H COSY spectrum. Hence, the large up-
field shift of H(1) may be ascribed to the local diatropic ring
current effect of the pyrrole C, which is close to H(1) with a
distance of 2.57 Š. In contrast to the quantitative and rever-
vealed a twisted figure-of-eight conformation of 4 consisting
of two oblique near planar tripyrrolic hemimacrocycles held
with a dihedral angle of 668 (Figure 2). These hemimacrocy-
[23,24]
sible redox interconversions between [24]- and [22]NFP5
bearing meso-pentafluorophenyl substituents, oxidation of 3
to its [22]NFP5 counterpart was found to be difficult even
with DDQ or MnO2 under forcing conditions.
Structural characterization of calix[5]phyrins 8 and 9: The
HR-ESI-TOF mass spectra of 8 and 9 exhibited the parent
ion peaks at 744.0855 and 728.0913, respectively ([MÀH]À;
calcd for C30N5F15H13O for 8, 744.0886 and C30N5F15H13 for
9, 728.0937) in line with the assigned calix[5]phyrin struc-
tures bearing a hydroxyl group and a hydrogen atom at the
saturated sp3-hybridized meso-carbon atom, respectively, as
shown in Scheme 1. Preliminary single-crystal structures
were obtained for both compounds, which revealed that the
pyrrole ring A is pointing outward and the other are orient-
ing inward with three NH hydrogen atoms at the pyrroles
A, C, and D (Scheme 1 and see Supporting information).
Figure 2. X-ray crystal structure of 4, top view (left) and side view
(right). The thermal ellipsoids are scaled to the 50% probability level.
meso-Trifluoromethyl substituents are omitted in the side view for clarity.
cles are both helically wound with the aid of mutual hydro-
gen-bonding interactions between the amine and imine moi-
À
eties of the pyrroles A, B, and C, and D, E, and F with N
H···N distances and angles of 2.07 Š and 1248 (A to B),
1.94 Š and 1348 (B to C), 2.33 Š and 1088 (D to E), and
2.00 Š and 1318 (E to F), respectively. The structure of 4 is
similar to that of perfluorinated [28]hexaphyrin[15b] with re-
spect to the helical structure as well as the presence of four
NH hydrogen atoms, which leads to the assignment of 4 as a
[28]hexaphyrin. In accord with this structural assignment,
1
The H NMRspectrum of 8 in CDCl3 exhibited two signals
due to the NH protons at d=10.02 and 9.22 ppm in a 2:1
ratio; four signals due to the b-CH protons at d=7.84, 7.55,
7.42, and 4.94 ppm in a 2:1:1:1 ratio; and one singlet due to
the meso-OH proton at d=2.23 ppm. Similarly, the
1H NMRspectrum of 9 in CDCl3 showed two signals due to
NH protons at d=10.81 and 9.19 ppm in a 2:1 ratio; five
peaks due to the b-CH protons at d=7.74, 7.73, 7.45, 7.34,
and 5.26 ppm in a 1:1:1:1:1 ratio; and a quartet peak due to
the sp3-meso-CH proton at d=2.64 ppm, which is coupled
with the fluorine atoms of the meso-trifluoromethyl substitu-
ent. The 19F NMRspectra of 8 and 9 in CDCl3 showed three
peaks in a 2:2:1 ratio at d=À53.65, À55.59, and À82.85 ppm
and at d=À52.79, À54.59, and À70.16 ppm, respectively.
The 13C NMRspectrum of 9 showed peaks between d=100
and 150 ppm, except for one peak at d=47.4 ppm that cor-
related with the proton peak at d=2.64 ppm in the H-C
COSY spectrum, while the 13C NMRspectrum of 8 exhibit-
ed most peaks between d=100 and 150 ppm and one peak
at d=73.4 ppm. These NMRspectra supported the prelimi-
nary crystal structures. Since 8 and 9 can be classified as an-
alogues of calixphyrin, we named them as calix[5]phyrin for
8 and 9.[25] These macrocycles are, to the best of our knowl-
edge, the first calix[5]phyrin-type molecules with homolo-
gous pentaphyrin frameworks. Plausibly, the formation of 9
may be caused by sterically bulky meso-trifluoromethyl sub-
stituents that retard full oxidation of a pentaphyrinogen pre-
cursor.
1
the H NMRspectrum of 4 in CD2Cl2 at room temperature
has two peaks due to the NH protons at d=14.95 and
12.35 ppm and broad peaks due to the b-CH protons be-
tween d=7.37 and 6.88 ppm, which became six well-re-
solved peaks at d=7.43, 7.23, 7.00, 6.95, 6.90, and 6.77 ppm
at À808C. The 19F NMRspectrum exhibited three peaks at
d=À55.40, À56.65, and À57.51 ppm at À808C, reflecting a
C2 symmetric structure of 4.
The hexaphyrin 4 was found not to oxidize while stored
under ambient conditions, but was smoothly oxidized with
MnO2 to give [26]hexaphyrin 14 quantitatively (Scheme 4).
Scheme 4. Oxidation of 4 to 14.
HR-ESI-TOF mass spectrum of 14 exhibited molecular ion
peak at 873.1061 ([M+H]+; calcd for C36N6F18H15:
873.1065), which confirmed the loss of two hydrogen atoms
Structural characterization of [28]hexaphyrin
4
and
1
A
from 4. The H NMRspectrum exhibited six peaks due to
showed its parent ion peak at 873.1064 ([MÀH]À; calcd for
the b-CH protons at d=7.88, 7.67, 7.54, 7.38, 6.33, and
5.99 ppm and one peak due to the NH protons at d=
C36N6F18H15: 873.1076). The X-ray diffraction analysis re-
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Porphyrinoids
FULL PAPER
11.11 ppm, which disappeared upon the addition of D2O.
These results indicate that there is no strong diatropic ring
current in 14, despite its cyclic 26p-electron conjugation. Fi-
nally the structure of 14 was determined by X-ray diffrac-
tion analysis. Compound 14 exhibits a twisted figure-of-eight
structure with two NH hydrogen atoms at the pyrroles B
and E (Figure 3), similar to that of 4. Here it is to be noted
diffraction analysis. Compound 6 has a near C2 symmetric
crescent-like conformation consisting of six aminopyrrole
rings and four iminopyrrole rings, thus indicating its formu-
lation as a [46]decaphyrin (Figure 4). The structure of 6 con-
Figure 3. X-ray crystal structure of 14, top view (left) and side view
(right). The thermal ellipsoids are scaled to the 50% probability level.
meso-Trifluoromethyl substituents are omitted in the side view for clarity.
that the hexaphyrin 14 is, to the best of our knowledge, the
first nonaromatic [26]hexaphyrin(1.1.1.1.1.1), which is due to
non-planarity of the molecule caused by the substantial
steric hindrance.[26]
Figure 4. X-ray crystal structure of 6, top view (top) and side view
(bottom). The thermal ellipsoids are scaled to the 50% probability level.
meso-Trifluoromethyl substituents are omitted in the side view for clarity.
Structural characterization of [32]heptaphyrin 5: The HR-
ESI-TOF mass spectrum of 5 showed its molecular ion peak
at 1018.1213 ([MÀH]À; calcd for C42N7F21H17: 1018.1216).
1
The H NMRspectrum in CDCl at room temperature dis-
sists of two segments: semihelical tripyrrolic subunits (the
pyrroles A, B, and C, and the pyrroles F, G, and H) and
near planar dipyrromethene subunits (the pyrroles D and E,
and the pyrroles I and J). Both semihelical subunits are held
by the aid of hydrogen bonding between the amine NH
groups and imine nitrogen atoms of the pyrrole rings. The
19F NMRspectrum of 6 in CDCl3 at room temperature ex-
hibited rather broad two sets of peaks, which became sharp
on lowering temperature. At À608C, one set of peaks ap-
peared at d=À44.55, À46.02, À47.04, À47.84, À48.44,
3
plays two signals at d=15.68 and 11.15 ppm due to the NH
protons and five signals due to the b-CH protons at d=9.93,
8.90, 7.79, 7.56, and 6.60 ppm. The 19F NMRspectrum of
5
exhibited four peaks at d=À50.72, À51.17, À55.26, and
À57.46 ppm in a 2:1:2:2 ratio. Overall these NMRdata sug-
gested a C2 symmetric structure with four NH protons, thus
indicating 32p-electronic conjugation for 5. It is notable that
the heptaphyrin 5 is thermally quite stable in a solution, in
contrast to meso-pentafluorophenyl[32]heptaphyrin[15a] and
perfluorinated[32]heptaphyrin,[15b] which are both thermally
unstable, being gradually converted to their N-fused hepta-
phyrins just on standing. The chemical stability of 5 evident-
ly arises from the lack of meso-pentafluorophenyl substitu-
ents, since the ortho-fluorine atoms in the heptaphyrins are
susceptible for the nucleophilic substitution reaction of the
neighboring pyrrolic nitrogen atom.
À49.39, À54.87, À56.64, and À58.53 ppm in
a
2:1:1:1:1:1:1:1:1 ratio and the other, which consists of five
peaks, appeared at d=À50.93, À51.97, À52.18, À54.54, and
À59.18 ppm, indicating that asymmetric and symmetric con-
formations (6-I and 6-II, respectively) exist in equilibrium in
1:0.3 ratio in CDCl3 (see the Supporting Information). Vari-
1
able-temperature H NMRmeasurements were also exam-
ined to confirm the existence of two conformations in solu-
tion. At À608C, the peaks became well-resolved and were
assigned to each conformer by H-H COSY experiments to
reveal that the twenty peaks due to b-CH protons of 6-I ap-
peared at d=8.32, 8.21, 7.94, 7.84, 7.78, 7.76, 7.67, 7.60, 7.57,
7.41, 7.20–7.19 (2H), 6.74, 6.59, 6.56, 6.49, 6.37, 5.86, 4.83,
and 4.30 ppm, and six NH protons resonated at d=8.16,
7.14, 5.82, 3.44, 3.35, and 1.08 ppm, while the b-CH peaks of
6-II were observed at d=7.73, 7.60, 7.48, 7.34, 7.31, 7.26,
7.16, 7.13, 6.80, and 6.77 ppm and six NH protons resonated
Structural characterization of [46]decaphyrin 6: meso-Tri-
fluoromethyl-substituted decaphyrin 6 could not be purified
by silica-gel column chromatography, because calix[5]phyrin
9 had similar polarity in silica-gel column, but the large dif-
ference in molecular size enabled clear separation through
gel-permeation chromatography. The HR-ESI-TOF mass
spectrum of 6 exhibited the parent ion peak at 1455.1784
([MÀH]À; Calcd for C60N10F30H25: 1455.1790). The solid-
state structure of 6 was determined by X-ray single crystal
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A. Osuka et al.
at d=12.45, 10.72, and 10.61 ppm; these results reflect the
asymmetric and symmetric nature of 6-I and 6-II, respective-
ly. The conformer 6-I exhibits large up-field shifts for some
b-CH protons and NH peaks, which may be accounted for
in terms of some diatropic ring current effect arising from
46p-electron conjugation.[27]
peaks. In the 19F NMRspectrum of 7 in CD2Cl2, six broad
peaks were observed at room temperature, which became
well-resolved peaks at d=À45.00, À49.34, À51.18, À54.78,
À56.33, and À59.47 ppm with twelve smaller peaks at d=
À44.06, À45.88, À49.50, À50.20, À51.37, À53.39, À53.82,
À56.59, À56.75, À56.99, À57.33, and À57.61 ppm at À908C,
suggesting the existence of symmetric and asymmetric con-
formers, 7-I and 7-II, respectively, in a 1:0.3 ratio (see the
Supporting Information). In agreement with this considera-
Structural characterization of [56]dodecaphyrin 7: The HR-
ESI-TOF mass spectrum of 7 exhibited its parent ion peak
at 1747.2201 ([MÀH]À; Calcd for C72N12F36H31: 1747.2225).
The solid-state structure of 7 has been revealed by single-
crystal X-ray diffraction analysis (Figure 5). Curiously, the
1
tion, the H NMRspectrum exhibited the NH proton peaks
due to the major conformer 7-I at d=12.80, 9.40, 8.23, and
6.31 ppm, and its b-CH protons appeared at d=8.92, 8.35,
7.74, 7.32, 7.13, 7.04–6.98, 6.78, 6.74, and 6.46 ppm, while the
peaks due to the minor asymmetrical conformer 7-II were
hard to assign at À908C (see the Supporting Information).
To the best of our knowledge, 7 is the largest structurally
well-characterized expanded porphyrin formed from a one-
pot condensation of a monopyrrolic substrate.
UV/Vis absorption spectra: Absorption spectra of expanded
porphyrins are known to shift to the lower energy side as
the ring-size (conjugation) becomes larger. The same trend
is observed for the present series. Figure 6 shows absorption
spectra of various meso-trifluoromethyl-substituted expand-
ed porphyrins taken in CH2Cl2. The N-fused pentaphyrin 3
has a broad band at 472 nm and a less intense broad absorp-
tion at 643 nm, both of which are blue-shifted relative to
those of meso-pentafluorophenyl-substituted [24]NFP5 (Fig-
ure 6b).[23,24] The absorption spectra of the calix[5]phyrins 8
and 9 are similar to each other, exhibiting a broad absorp-
tion band at 481 nm and a weak absorption band at 673 nm
for 8 and those at 466 and 663 nm for 9 (Figure 6c and d).
These spectra are also analogous to that of 3 in respect of
shape and position, but their absorption coefficients are
larger than that of 3. The [28]hexaphyrin 4 exhibits a split
absorption band at 506 and 557 nm without any low energy
bands (Figure 6e), while the [26]hexaphyrin 14 exhibits a
much sharper and intense absorption band at 581 nm with a
broad weaker band at 748 nm (Figure 6f). The heptaphyrin
5 displays two broad absorption bands at 572 and 363 nm
(Figure 6g), which are similar to those of meso-pentafluoro-
phenyl-substituted [32]heptaphyrin[15a] and perfluorinated
[32]heptaphyrin.[15b] The absorption spectrum 6 shows three
broad bands at 447, 746, and 1036 nm (Figure 6h). It is inter-
esting to note that the lowest energy band reaches into near-
IRregion, probably reflecting its extensive p conjugation.
Finally, the absorption spectrum of 7 shows three broad
bands at 397, 532, and 778 nm, with a very broad band tail-
ing up to 1500 nm (Figure 6i).
Figure 5. X-ray crystal structure of 7, top view (top) and side view
(bottom). The thermal ellipsoids are scaled to the 50% probability level.
meso-Trifluoromethyl substituents are omitted in the side view for clarity.
dodecaphyrin macrocycle contains an intramolecularly
wound helix, consisting of seven pyrrole rings (the pyrroles
D, E, F, G, H, I, and J), that is linked to another semihelix
of three pyrrole rings (the pyrroles L, A, and B) through the
pyrroles C and K (Figure 5). These two spiral helixes are
held with the aid of hydrogen bonding between the amine
NH groups and imine nitrogen atoms, in a similar manner as
observed in the structures of 4, 6, and 14. The bridging pyr-
roles C and K possess inward-pointing NH hydrogen atoms,
which are used for hydrogen bonding with fluorine atom of
the adjacent trifluoromethyl substituents. The helix in 7 can
be characterized by a one-pitch distance of ca. 3.6 Š and a
diameter of 3.2 Š, while the diameter of semihelix is ap-
proximately 3.2 Š. The dodecaphyrin 7 possesses eight NH
hydrogen atoms, thus leading to the assignment of 7 as a
[56]dodecaphyrin. Similar to the case of 6, both 1H and
19F NMRspectra at room temperature showed very broad
Conclusion
meso-Trifluoromethyl-substituted expanded porphyrins 3, 4,
5, 6, 7, 8, and 9 were synthesized as the first examples bear-
ing meso-alkyl substituents. meso-Trifluoromethyl substitu-
ents exert a large influence on the structures and stabilities
4914
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Chem. Eur. J. 2006, 12, 4909 – 4918

Porphyrinoids
FULL PAPER
Figure 6. UV/Vis absorption spectra of a) 2, b) 3, c) 8, d) 9, e) 4, f) 14, g) 5, h) 6, and i) 7.
of the expanded porphyrins; this influence can clearly been
seen in that the pentapyrrolic macrocycles 8 and 9 were iso-
lated as calix[5]phyins for the first time, both [28]- and
[26]hexaphyrins 4 and 14 take figure-of-eight conformations,
the heptaphyrin 5 is chemically quite stable, and crescent
and partial helical structures have been revealed for decap-
hyrin 6 and dodecaphyrin 7. These expanded porphyrins are
expected to have different properties from those of the
normal expanded porphyrins, particularly in multiple coordi-
nation of metal ions, which will be an attractive next target.
Investigations along this direction are now currently in prog-
ress in our laboratory.
Experimental Section
General procedure: All reagents and solvents were of the commercial re-
agent grade and were used without further purification except where
Chem. Eur. J. 2006, 12, 4909 – 4918
ꢀ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
4915

A. Osuka et al.
noted. Dry CH2Cl2 was obtained by distilling over CaH2. 1H, 13C, and
19F NMRspectra were recorded on a JEOL ECA-600 spectrometer (op-
erating as 600.17 MHz for 1H, 150.91 MHz for 13C, and 564.73 MHz for
19F) using the residual solvent as the internal reference for 1H (d=
7.260 ppm for CDCl3 and d=5.320 ppm for CD2Cl2), and 13C (d=
77.0 ppm for CDCl3) and hexafluorobenzene as an external reference for
19F (d=À162.9 ppm). Spectroscopic grade CH2Cl2 was used as the solvent
for all spectroscopic studies. UV/Vis absorption spectra were recorded on
a Shimadzu UV-3100 spectrometer. Mass spectra were recorded on a
JEOL HX-110 spectrometer using positive-FAB ionization method with
accelerating voltage 10 kV and a 3-nitrobenzylalcohol matrix, or on a Shi-
madzu/KRATOS KOMPACT MALDI4 spectrometer by using positive-
MALDI ionization method. ESI-TOF-MS spectra were recorded on a
BRUKER microTOF by using positive- and negative-ion modes and ace-
tonitrile as a solvent. Preparative separations were performed by silica-
gel flash column chromatography (Merck Kieselgel 60H Art. 7736),
silica-gel gravity column chromatography (Wako gel C-400), or recycling
preparative GPC-HPLC that was carried out on JAI LC-908 using prepa-
rative JAIGEL-2H, 2.5H, and 3H columns.
purchased from Aldrich) for 12 h. After addition of DDQ (1.28 g,
5.7 mmol), the solution was stirred for an additional 6 h at room temper-
ature. The resulting solution was washed with
a saturated aqueous
NaHCO3 solution and water. After being dried over Na2SO4, the mixture
was separated by silica-gel column chromatography and gel-permeation
chromatography to afford 2 (2–3%), 3 (5–10%), 4 (3–4%), 5 (4–6%), 6
(~1%), 7 (~1%), and 8 (4%).
Preparation of 2-(2,2,2-trifluoro-1-hydroxyethyl)-6-trifluoromethyldipyr-
romethane 11: Trifluoroacetic anhydride (10.3 mL, 4.0 equiv) was added
to
a solution of meso-trifluoromethyl-substituted dipyrromethane 10
(4.0 g, 18.7 mmol) in THF (186 mL) cooled at À208C, and then the mix-
ture was stirred for 12 h. The reaction mixture was poured into aqueous
NaHCO3 and extracted with dichloromethane. The combined organic ex-
tracts were washed with water and brine, and dried over Na2SO4. After
removal of the solvent, the residue was subjected to distillation through a
glass tube oven at 160–1808C under high vacuum to give pure monoacy-
lated compound as yellow oil in 82–88% yield. The acylated dipyrro-
A
give 11.
Crystallographic data collection and structure refinement: Data collec-
tion for the compounds 4 and 6 were carried out at À1508C on a Rigaku
RAXIS-RAPID diffractometer with graphite-monochromated MoKa ra-
diation (l=0.71069 Š). Data collection for the compounds 3, 7, and 14
were carried out at À1538C for 3 and 7 and at À1838C for 14 on a
Bruker SMART APEX diffractometer with graphite-monochromated
MoKa radiation (l=0.71069 Š). Details of the crystallographic data are
listed in Table 1. The structures were solved by direct methods (Sir 97[28]
or SHELXS-97[29]) and refined with Rigaku CrystalStructure software or
with full-matrix least square technique (SHELXL-97).[29]
Synthesis of meso-trifluoromethyl-substituted expanded porphyrins from
11: HCl in diethyl ether (1.0m; 1.58 mL, 1.0 equiv) was added to a solu-
tion of 11 (492 mg, 1.58 mmol) in dichloromethane(24 mL), and the mix-
A
ture was then refluxed for 12 h. After cooling to room temperature,
DDQ (807 mg, 3.57 mmol) was added and the reaction mixture was stir-
red for 6 h. The reaction mixture was neutralized by washing with aque-
ous NaHCO3 and dried over Na2SO4. After removal of the solvent, the
mixture was separated into each fractions to give 2, 4, 6, and 7 in 1–3%,
8–10%, ~1%, and ~1% yields, respectively.
Preparation of meso-trifluoromethyl substituted tripyrromethane 12: Pyr-
role (6.0 mL, 10.8 equiv) and HCl (0.6 mL, 0.9 equiv) were added to a
solution of 11 (2.5 g, 8.0 mmol) in THF (40 mL), and the resulting mix-
ture was refluxed for 4 h. The reaction mixture was poured into aqueous
NaHCO3, and the organic layer was extracted with CH2Cl2. The organic
phase was washed with water and brine, and dried over Na2SO4. After re-
moval of the solvent, the mixture was purified by silica-gel column chro-
matography to give pure 12 as a white powder (1.61 g, 56% yield).
CCDC-296241 (3), CCDC-296243 (4), CCDC-296244 (6), CCDC-296245
(7), and CCDC-296242 (14) contain the supplementary crystallographic
data for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
Preparation of meso-trifluoromethyl-substituted expanded porphyrins: In
a 100 mL round-bottomed flask under nitrogen 2-(2,2,2-trifluoro-1-hy-
droxyethyl)pyrrole 1 (0.413 g, 2.5 mmol) was dissolved in dichlorometh-
Preparation of 2,2’-bis(2,2,2-trifluoro-1-hydroxyethyl)-6-trifluoromethyl-
dipyrromethane 13: meso-Trifluoromethyl-substituted dipyrromethane 10
ane (37.5 mL) and was refluxed with HCl in diethyl ether (1.0m; 2.5 mL
Table 1. Crystallographic details for 3, 4, 6, 7, and 14.
3
4
6
7
14
formula
Mr
crystal system
space group
a [Š]
b [Š]
c [Š]
a [8]
b [8]
C30N5F15H12
727.45
C36N6F18H16
874.53
C61N10F30H26Cl2
1539.80
monoclinic
P2/c (13)
8.50(1)
12.06(2)
28.41(4)
90
95.7(1)
90
2898.5(8)
2
C80N12F36H34OCl2
1934.09
monoclinic
P21/n (14)
12.0151(7)
40.273(2)
16.0233(10)
90
98.183(1)
90
7674.4(8)
4
C36N6F18H14
872.53
triclinic
triclinic
monoclinic
P21/c (14)
8.4856(10)
41.522(5)
9.8799(11)
90
103.642(2)
90
3382.9(7)
4
¯
¯
P1 (2)
P1 (2)
8.3513(8)
10.9428(10)
15.4333(14)
104.309(2)
97.035(2)
100.594(2)
1322.3(2)
2
11.2767(8)
11.3922(2)
13.9713(8)
108.486(4)
96.708(6)
96.264(8)
1670.1(2)
2
g [8]
V [Š3]
Z
1calcd [gcmÀ3
]
1.827
1.85
1.739
1.76
1.764
2.63
1.674
2.30
1.713
1.74
m
A
]
F
N
724
872
1532
0.25”0.15”0.05
55.0
3856
0.20”0.20”0.10
50.0
1736
0.40”0.20”0.10
56.4
0.45”0.20”0.02
56.6
0.30”0.20”0.15
54.7
total reflections
unique reflections
reflection used
parameters
absorption correction
R1
8592
5962
5962
451
empirical
0.0707
14151
7269
4821
569
–
22208
6605
2452
470
–
40720
13505
13505
1140
empirical
0.0823
20302
7643
7643
597
empirical
0.0704
0.060
0.099
wR2
0.1471
0.072
0.113
0.2201
0.1645
GOF
1.131
1.300
1.254
1.050
1.158
4916
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Chem. Eur. J. 2006, 12, 4909 – 4918

Porphyrinoids
FULL PAPER
(2.14 g, 10 mmol) was dissolved in toluene (60 mL). Trifluoroacetic anhy-
dride (6.9 mL, 50 mmol) was added to the solution at room temperature,
and the resultant solution was stirred for 5 h. Then the reaction mixture
was poured into aqueous NaHCO3 and extracted with dichloromethane.
The combined organic extracts were washed with water and brine, and
dried over Na2SO4. After removal of the solvent, recrystallization in di-
chloromethane and hexane gave diacylated dipyrromethane as a white
solid (3.56 g, 88% yield). Reduction with NaBH4 in THF and MeOH
gave 13 quantitatively as yellow oil.
7.48 (d, J=2.8 Hz, 2H; b-CH), 7.34 (brs, 2H; b-CH), 7.31 (dd, J=5.4,
2.1 Hz, 2H; b-CH), 7.26 (2H; a b-CH signal was hidden in the peak due
to the residual CHCl3), 7.16 (d, J=2.8 Hz, 2H; b-CH), 7.13 (s, 2H; b-
CH), 6.80 (brs, 2H; b-CH), 6.77 ppm (dd, J=4.8, 2.8 Hz, 2H; b-CH);
19F NMR(565 MHz, CDCl 3, 213 K): d=À50.93 (s, 6F), À51.97 (s, 6F),
À52.18 (s, 6F), À54.54 (s, 6F), À59.18 ppm (s, 6F); UV/Vis (CH2Cl2):
lmax (e)=364 (51200), 447 (60800), 746 (50000) 1036 nm
(14600mÀ1 cmÀ1); HR-ESI-TOF-MS: m/z (%): 1455.1784 (100) [MÀH]À;
calcd for C60N10F30H25: 1455.1790.
meso-Trifluoromethyl-substituted [56]dodecaphyrin 7
ACHTREUNG
Conformer 7-I: 1H NMR(600 MHz, CD 2Cl2, 183 K): d=12.80 (s, 2H;
NH), 9.40 (s, 2H; NH), 8.92 (s, 2H; b-CH), 8.35 (s, 2H; b-CH), 8.23 (s,
2H; NH), 7.74 (s, 2H,; b-CH), 7.32 (s, 2H; b-CH), 7.13 (s, 2H; b-CH),
7.04–6.98 (m, 8H; b-CH), 6.78 (s, 2H; b-CH), 6.74 (s, 2H; b-CH), 6.46 (s,
2H; b-CH), 6.31 ppm (s, 2H; NH); 19F NMR(565 MHz, CD 2Cl2, 183 K);
d=À45.00 (s, 6F), À49.34 (s, 6F), À51.18 (s, 6F), À54.78 (s, 6F), À56.33
(s, 6F), À59.47 ppm (s, 6F).
ACHTREUNG
(10.7 ml, 0.5 equiv), the resultant solution was refluxed for 12 h and then
was treated with DDQ (170 mg, 2.3 equiv) at room temperature for 6 h.
The reaction mixture was neutralized by washing with aqueous NaHCO3
and dried over Na2SO4. After removal of the solvent, the mixture was
separated into each fractions to give 3, 8, and 9 in 1–2%, ~1.5%, and 4–
5% yields, respectively.
Conformer 7-II: 19F NMR(565 MHz, CD Cl2, 183 K); d=À44.06 (s, 3F),
2
meso-Trifluoromethyl-substituted [18]porphyrin 2: 1H NMR(600 MHz,
CDCl3, 298 K): d=9.62 (s, 8H; b-CH), À2.08 ppm (s, 2H; NH);
19F NMR(565 MHz, CDCl 3, 298 K): d=À39.03 ppm (s, 12F); UV/Vis
(CH2Cl2): lmax (e)=404 (126000), 510 (9900), 545 (9900), 594 (4800),
649 nm (10000mÀ1 cmÀ1); HR-ESI-TOF-MS: m/z (%): 581.0640 (100)
[MÀH]À; calcd for C24N4F12H9: 581.0641.
À45.88 (s, 3F), À49.50 (s, 3F), À50.20 (s, 3F), À51.37 (s, 3F), À53.39 (s,
3F), À53.82 (s, 3F), À56.59 (s, 3F), À56.75 (s, 3F), À56.99 (s, 3F),
À57.33 (s, 3F), À57.61 ppm (s, 3F); UV/Vis (CH2Cl2): lmax (e)=345
(52100), 397 (53600), 532 (73900), 778 nm (57900mÀ1 cmÀ1); HR-ESI-
TOF-MS: m/z (%): 1747.2201 (100) [MÀH]À; calcd for C72N12F36H31:
1747.2225.
meso-Hydroxy-substituted calix[5]phyrin 8: 1H NMR(600 MHz, CDCl
,
meso-Trifluoromethyl-substituted [24]NFP5 3: 1H NMR(600 MHz,
CD2Cl2, 298 K): d=9.26 (s, 1H; NH), 8.62 (s, 1H; NH), 8.05 (s, 1H;
NH), 7.80 (dd, J=5.3, 2.8 Hz, 1H; b-CH), 7.63–7.59 (m, 2H; b-CH), 7.52
(dd, J=5.0, 2.3 Hz, 1H; b-CH), 7.28 (d, J=5.9 Hz, 1H; b-CH), 7.12 (dd,
J=7.0, 2.3 Hz, 1H; b-CH), 6.43 (brs, 1H; b-CH), 5.95 (t, J=3.2 Hz, 1H;
3
298 K): d=10.02 (s, 2H; NH), 9.22 (s, 1H; NH), 7.84 (m, 4H; b-CH),
7.55 (d, J=4.1 Hz, 2H; b-CH), 7.42 (d, J=4.6 Hz, 2H; b-CH), 4.94 (d,
J=1.9 Hz, 2H; b-CH), 2.23 ppm (s, 1H; OH); 19F NMR(565 MHz,
CDCl3, 298 K): d=À53.65 (m, 6F), À55.59 (s, 6F), À82.85 ppm (s, 3F);
13C NMR(150 MHz, CDCl 3, 298 K): d=151.3, 146.1, 141.4, 139.5, 135.8,
131.5, 130.4, 129.2, 125.6, 124.7, 123.9, 123.7, 122.2, 115.6, 100.6,
73.4 ppm; UV/Vis (CH2Cl2): lmax (e)=358 (29400), 481 (55200), 673 nm
(8100mÀ1 cmÀ1); HR-ESI-TOF-MS: m/z (%): 744.0855 (100) [MÀH]À;
calcd for C30N5F15H13O: 744.0886.
meso-Trifluoromethyl-substituted calix[5]phyrin 9: 1H NMR(600 MHz,
CDCl3, 298 K): d=10.81 (s, 2H; NH), 9.19 (s, 1H; NH), 7.74–7.73 (m,
4H; b-CH), 7.45 (d, J=4.1 Hz, 2H; b-CH), 7.34 (d, J=4.1 Hz, 2H; b-
CH), 5.26 (d, J=1.9 Hz, 2H; b-CH), 2.64 ppm (q, J=8.8 Hz, 1H; CH);
19F NMR(565 MHz, CDCl 3, 298 K): d=À52.79 (s, 6F), À54.59 (s, 6F),
À70.16 ppm (d, J=8.7 Hz, 3F); 13C NMR(150 MHz, CDCl 3, 298 K): d=
151.8, 146.4, 140.3, 139.7, 136.4, 131.7, 130.1, 128.3, 125.0, 124.8, 123.9,
123.6, 122.9, 116.7, 100.8, 47.4 ppm; UV/Vis (CH2Cl2): lmax (e)=359
(34700), 466 (57200), 663 nm (10100mÀ1 cmÀ1); HR-ESI-TOF-MS: m/z
(%): 728.0913 (100) [MÀH]À; calcd for C30N5F15H13: 728.0937.
b-CH), 3.09 ppm (d, J=1.4 Hz, 1H; b-CH); 19F NMR(565 MHz, CD Cl2,
2
298 K): d=À50.54 (s, 3F), À51.06 (s, 3F), À56.58 (s, 3F), À56.65 (s, 3F),
À57.56 ppm (s, 3F); UV/Vis (CH2Cl2): lmax (e)=361 (23000), 472
(34900), 643 nm (7500mÀ1 cmÀ1); HR-ESI-TOF-MS: m/z (%): 726.0771
(100) [MÀH]À; calcd for C30N5F15H11: 726.0780.
meso-Trifluoromethyl-substituted [28]hexaphyrin 4: 1H NMR(600 MHz,
CD2Cl2, 193 K): d=14.99 (s, 2H; NH), 12.14 (s, 2H; NH), 7.43 (d, J=
2.0 Hz, 2H; b-CH), 7.23 (s, 2H; b-CH), 7.00 (s, 2H; b-CH), 6.95 (s, 2H;
b-CH), 6.90 (d, J=2.8 Hz, 2H; b-CH), 6.77 ppm (s, 2H; b-CH); 19F NMR
(565 MHz, CD2Cl2, 193 K): d=À55.40 (s, 6F), À56.65 (s, 6F),
À57.51 ppm (s, 6F); UV/Vis (CH2Cl2): lmax (e)=312 (22600), 506
(62700), 557 nm (66800mÀ1 cmÀ1); HR-ESI-TOF-MS: m/z (%): 873.1064
(100) [MÀH]À; calcd for C36N6F18H15: 873.1076.
1
meso-Trifluoromethyl-substituted [32]heptaphyrin 5: H NMR(600 MHz,
CDCl3, 298 K): d=15.68 (s, 2H; NH), 11.15 (s, 2H; NH), 9.93 (s, 2H; b-
CH), 8.90 (s, 2H; b-CH), 7.79 (s, 2H; b-CH), 7.56 (s, 2H; b-CH),
meso-Trifluoromethyl-substituted [26]hexaphyrin 14: MnO2 (Chemicals
Treated, 23 mg, 0.26 mmol) was added to a solution of compound 4
(10 mg, 11 mmol) in CH2Cl2 (15 mL). The resulting solution was stirred
for 20 min to give an violet solution, which was filtered and evaporated
6.60 ppm (m, 6H; b-CH); 19F NMR(565 MHz, CDCl
, 298 K): d=
3
À50.72 (s, 6F), À51.17 (s, 3F), À55.26 (s, 6F), À57.46 ppm (s, 6F); UV/
Vis (CH2Cl2): lmax (e)=363 (42000), 572 nm (66500mÀ1 cmÀ1); HR-ESI-
TOF-MS: m/z (%): 1018.1213 (100) [MÀH]À; calcd for C42N7F21H17:
1018.1216.
to afford compound 14 quantitatively. 1H NMR(600 MHz, CDCl
,
3
298 K): d=11.11 (s, 2H; NH), 7.88 (m, 2H; b-CH), 7.67 (m, 2H; b-CH),
7.54 (dd, J=4.6, 2.0 Hz, 2H; b-CH), 7.38 (d, J=2.7 Hz, 2H; b-CH), 6.33
(d, J=4.8 Hz, 2H; b-CH), 5.99 ppm (dd, J=4.8, 2.1 Hz, 2H; b-CH);
19F NMR(565 MHz, CDCl 3, 298 K): d=À51.73 (s, 6F), À53.32 (s, 6F),
À55.81 ppm (s, 6F); UV/Vis (CH2Cl2): lmax (e)=329 (38100), 391
(20000), 581 (90300), 748 nm (9700mÀ1 cmÀ1); HR-ESI-TOF-MS: m/z
(%): 873.1061 (100) [M+H]+; calcd for C36N6F18H15: 873.1065.
meso-Trifluoromethyl-substituted [46]decaphyrin 6
1
Conformer 6-I: H NMR(600 MHz, CDCl , 213 K): d=8.32 (brs, 1H; b-
3
CH), 8.21 (dd, J=4.8, 2.8 Hz, 1H; b-CH), 8.16 (s, 1H; NH), 7.94 (d, J=
4.1 Hz, 1H; b-CH), 7.84 (d, J=2.1 Hz, 1H; b-CH), 7.78 (m, 1H; b-CH),
7.76 (dd, J=4.8, 2.0 Hz, 1H; b-CH), 7.67 (dd, J=2.0, 2.0 Hz, 1H; b-CH),
7.60 (d, J=2.8 Hz, 1H; b-CH), 7.57 (s, 1H; b-CH), 7.41 (brs, 1H; b-CH),
7.20–7.19 (m, 2H; b-CH), 7.14 (s, 1H; NH), 6.74 (brs, 1H; b-CH), 6.59
(d, J=5.5 Hz, 1H; b-CH), 6.56 (d, J=3.5 Hz, 1H; b-CH), 6.49 (dd, J=
4.1, 2.0 Hz, 1H; b-CH), 6.37 (s, 1H; b-CH), 5.86 (d, J=4.8 Hz, 1H; b-
CH), 5.82 (s, 1H; NH), 4.83 (s, 1H; b-CH), 4.30 (s, 1H; b-CH), 3.44 (s,
1H; NH), 3.34 (s, 1H; NH), 1.08 ppm (s, 1H; NH); 19F NMR(565 MHz,
CDCl3, 213 K): d=À44.55 (s, 6F), À46.02 (s, 3F), À47.04 (s, 3F), À47.84
(s, 3F), À48.44 (s, 3F), À49.39 (s, 3F), À54.87 (s, 3F), À56.64 (s, 3F),
À58.53 ppm (s, 3F)
Acknowledgements
This work was partly supported by Grant-in-Aid (B) (No. 15350022)
from the Ministry of Education, Culture, Sports, Science and Technology,
Japan. S.S. thanks JSPS for the Research Fellowship for Young Scientists.
Conformer 6-II: 1H NMR(600 MHz, CDCl 3, 213 K): d=12.45 (s, 2H;
NH), 10.72 (s, 2H; NH), 10.61 (s, 2H; NH), 7.73 (brs, 2H; b-CH), 7.60
(2H; a b-CH peak was hidden in the peak due to the conformer 6-I),
[1] a) J. L. Sessler, A. Gebauer, S. J. Weghorn, The Porphyrin Hand-
book, Vol. 2 (Eds.: K. M. Kadish, K. M. Smith, R. Guilard), Aca-
Chem. Eur. J. 2006, 12, 4909 – 4918
ꢀ 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
4917

A. Osuka et al.
demic Press, San Diego, 1999, Chapter 9; b) A. Jasat, D. Dolphin,
Chem. Rev. 1997, 97, 2267–2340; c) T. D. Lash, Angew. Chem. 2000,
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Received: February 4, 2006
Published online: March 24, 2006
4918
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