Synthesis, Structural and Optical Properties of Tetrabenzoporphyrin Complexes Bearing Four or Eight Peripheral Phenyl Groups

Article abstract of DOI:10.1002/ejoc.201900528

A series of free-base and phosphorus(V) complexes of tetrabenzoporphyrin (TBP) and some phosphorus(V) porphyrins containing four or eight phenyl groups on the periphery have been synthesized and characterized by X-ray crystallography, electronic absorption, and magnetic circular dichroism (MCD) spectroscopy, together with quantum chemical calculations. All phosphorus TBP and meso-tetraphenyl porphyrin complexes adapted ruffled conformations due to the small P(V) ion, although the Zn(II)TBPs containing eight phenyl (Φ) groups at the so-called β and α positions showed planar and saddled structures in the solid state, due to, respectively, marginal or severe steric hindrance between the neighboring Φ groups. All P(V)TBPs showed the Soret and Q bands beyond 450 and 700 nm, respectively, which are some of the longest wavelengths exhibited by metallated TBPs reported to date. Of the eight Φ group-substituted P(V)TBPs, those substituted at α positions always showed absorption bands at longer wavelengths than those at β positions, which was reproduced by calculated absorption spectra. The Soret band positions of meso-tetraphenylated P(V) species without fused benzo-groups (ca. 430–440 nm) were also some of the longest among metalloporphyrins of this type.

Full text of DOI:10.1002/ejoc.201900528

A Journal of
Accepted Article
Title: Synthesis, Structural and Optical Properties of
Tetrabenzoporphyrin Complexes Bearing Four or Eight
Peripheral Phenyl Groups
Authors: Taniyuki Furuyama, Tetsuo Okujima, Kota Muramatsu, Yuichi
Takahashi, Akihiro Mikami, Tomoteru Fukumura, Shigeki
Mori, Takahiro Nakae, Masayoshi Takase, Hidemitsu Uno,
and Nagao Kobayashi
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of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
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to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.201900528
Link to VoR: http://dx.doi.org/10.1002/ejoc.201900528
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10.1002/ejoc.201900528
European Journal of Organic Chemistry
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Synthesis, Structural and Optical Properties of
Tetrabenzoporphyrin Complexes Bearing Four or Eight Peripheral
Phenyl Groups
Taniyuki Furuyama,*[a, c] Tetsuo Okujima,*[b] Kota Muramatsu,[b] Yuichi Takahashi,[c] Akihiro Mikami,[b]
Tomoteru Fukumura,[c] Shigeki Mori,[d] Takahiro Nakae,[b] Masayoshi Takase,[b] Hidemitsu Uno,[b] and
Nagao Kobayashi,*[c, e]
Abstract: A series of free-base and phosphorus(V) complexes of
tetrabenzoporphyrin (TBP) and some phosphorus(V) porphyrins
containing four or eight phenyl groups on the periphery have been
synthesized and characterized by X-ray crystallography, electronic
absorption and magnetic circular dichroism (MCD) spectroscopy,
together with quantum chemical calculations. All phosphorus TBP
and meso-tetraphenyl porphyrin complexes adapted ruffled
conformations due to the small P(V) ion, although the Zn(II)TBPs
containing eight phenyl (F) groups at the so-called b and a positions
showed planar and saddled structures in the solid state, due to,
respectively, marginal or severe steric hindrance between the
neighboring F groups. All P(V)TBPs showed the Soret and Q bands
beyond 450 and 700 nm, respectively, which are some of the longest
wavelengths exhibited by metallated TBPs reported to date. Of the
eight F group-substituted P(V)TBPs, those substituted at a positions
always showed absorption bands at longer wavelengths than those
at b positions, which was reproduced by calculated absorption
spectra. The Soret band positions of meso-tetraphenylated P(V)
species without fused benzo-groups (ca. 430-440 nm) were also
some of the longest among metalloporphyrins of this type.
applications such as light emitting displays, thin film transistors,
solar cells, photosensitizers for photodynamic therapy, or as
other
types
of
opt-electronic
material.[1]
(Metallo)tetrabenzoporphyrin (MTBP) was obtained by the
traditional route, starting from phthalimide or isoindole at high
temperature.[2,3] The introduction of substituents into the benzo
moieties of TBP afforded an effective method for tuning the
structures and the absorptions. Little is known about the
synthetic method of TBPs bearing peripheral phenyl groups by
the traditional method,[4] while various meso-substituted
porphyrins have been successfully synthesized.[5] Recently,
soluble precursors of TBPs which were synthesized utilizing
masked isoindole methods have been reported. Porphyrin fused
with cyclohexenes at b-pyrrolic positions was reported as a
precursor of TBP by oxidative aromatization.[6] Vinogradov and
co-workers have reported the synthesis of TBP with
alkoxycarbonyl or alkoxy groups at the benzo moieties.[7] We
have reported thermally convertible precursors of TBP by
utilizing retro Diels–Alder strategy.[8] This strategy afforded
octamethoxycarbonylTBPs.[9]
On the other hand, we have reported the synthesis of
phosphorus(V) complexes of azaporphyrin derivatives.[10] For
instance, Phosphorus(V) phthalocyanines (Pcs) showed red-
shifted Q-bands beyond 1000 nm.[10d,f] More importantly, the
effect of phosphorus ion was changed depending on a choice of
macrocyclic core, such as phthalocyanine, tetraazaporphyrin
(TAP)[10b,c] and tetrabenzotriazacorrole (TBC).[10g] TBPs have
relatively intense Q bands compared to porphyrins (Pors), and
are therefore called "an intermediate" between Pcs and Pors.
This unique properties of TBPs provoke us to examine optical
properties of phosphorus TBPs. To date, there is no report on
phosphorus TBPs, while phosphorus tetraphenylporphyrin (TPP)
and octaethylporphyrin (OEP) have been reported.[11] We herein
report the synthesis of free base, zinc and phosphorus TBPs
bearing peripheral phenyl groups based on the precursor
methods. The thermal conversion method afforded TBPs
Introduction
Much attention has been focused on p-expanded porphyirns for
[a]
[b]
Prof. Dr. T. Furuyama
Graduate School of Natural Science and Technology
Kanazawa University, Kakuma-machi, Kanazawa 920-1192 (Japan)
E-mail: tfuruyama@se.kanazawa-u.ac.jp
http://kohka.ch.t.kanazawa-u.ac.jp/lab4/lab4.html
Prof. Dr. T. Okujima, K. Muramatsu, A. Mikami, Dr. T. Nakae, Prof.
Dr. M. Takase, Prof. Dr. H. Uno
Graduate School of Science and Engineering
Ehime University, Matsuyama 790-8577 (Japan)
E-mail: okujima.tetsuo.mu@ehime-u.ac.jp
http://chem.sci.ehime-u.ac.jp/~orgchem1/eindex.html
Prof. Dr. T. Furuyama, Y. Takahashi, Prof. Dr. T. Fukumura, Prof.
Dr. N. Kobayashi
bF8MTBP (M
=
H2 and Zn) and bF8P(V)TBP from
[c]
bicyclo[2.2.2]octadiene(BCOD)-fused precursors bF8MP (M = H2
and Zn) and bF8P(V)P, respectively, while the oxidative
aromatization method afforded phenylTBPs aF8MTBP (M = H2
and Zn) and aF8P(V)TBP from the cyclohexene-fused precursor
aF8H2P (Figure 1). Meso-tetraphenylated phosphorus(V) TBP,
Department of Chemistry, Graduate School of Science
Tohoku University, Sendai 980-8578 (Japan)
Dr. S. Mori
Advanced Research Support Center
Ehime University, Matsuyama 790-8577 (Japan)
Prof. Dr. N. Kobayashi
[d]
[e]
i.e. m
to the corresponding metal-free derivative m
was prepared by the reported methods.[8c,g] For the purpose of
comparison, the meso-tetraphenylporphyrin phosphorus
complex 4P(V)TPP, was also prepared from the
F
4P(V)TBP was obtained by phosphorus insertion reaction
Faculty of Textile Science and Technology
Shinshu University, Ueda 386-8567 (Japan)
E-mail: nagaok@shinshu-u.ac.jp
F
4H2TBP, which
http://soar-rd.shinshu-u.ac.jp/profile/en.ypAhOVyC.html
m
F
Supporting information for this article is given via a link at the end of
the document.
corresponding metal-free complex, m 4H2TPP, referencing to
F
the literature method.[11]
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10.1002/ejoc.201900528
European Journal of Organic Chemistry
FULL PAPER
chromatography (Scheme 1). A solution of this mixture and
trans-1,2-bis(phenylsulfonyl)ethylene in o-dichlorobenzene was
heated at 180 °C in an autoclave to give a Diels–Alder adduct 5.
The adduct 5 was treated with ethyl isocyanoacetate and KOt-
Results and Discussion
Synthesis and characterization
The reaction of 1[12] with PhLi, followed by dehydration with
[13]
Bu
to
give
6
in
73%
yield.
H3PO4
afforded a mixture of 3 and 4 in a ratio of 2 : 1 as
determined by NMR, which could not be isolated by column
OMe
+
+
Ph Ph
L
Ph
Ph Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
NH
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
Ph
Ph
Ph
M
M
P
M
P
Ph
–
PF6
Ph
N HN
N
N
N
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
–
L
ClO4
MeO
MTBP
mΦ4MTBP mΦ4P(V)TBP–L
M = H2, Zn
βΦ8MP
M = H2, Zn
βΦ8P(V)P
αΦ8H2P
L = OMe, Cl
+
+
OMe
Ph Ph
Ph
Ph
Ph
Ph
Ph
Ph
OMe
Ph Ph
Ph
Ph
Ph
Ph
Ph
L
+
N
N
N
Ph
Ph
Ph
Ph
Ph
Ph
Ph
M
Ph
Ph
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
M
M
P
P
N
N
N
N
N
Ph
Ph
Ph
Ph
Ph
P
Ph
Ph
Ph
Ph
Ph
Ph
MeO
MeO
Ph
–
–
–
Ph
Ph
PF6
Ph
PF6
ClO4
Ph
L
βΦ8MTBP
M = H2, Zn
αΦ8MTBP
M = H2, Zn
βΦ8P(V)TBP
αΦ8P(V)TBP
mΦ4MTPP mΦ4P(V)TPP–L
M = H2, Zn L = OMe, Cl
Figure 1. Structure of phenylTBPs, phenylTPPs and some of their precursors.
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10.1002/ejoc.201900528
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Ph
O
Ph
Ph
CO2Et
Ph
HO Ph
SO2Ph
Ph
Ph
Ph
Ph
Ph
i)
ii)
iii)
iv)
Ph
NH
Ph
SO2Ph
Ph
1
2
3
4
5
6
Ph
Ph
Ph
Ph
Ph
Ph
Ph
N
N
N
N
N
N
v)
viii)
M
M
N
N
Ph
Ph
Ph
Ph
vi)
Ph
Ph
Ph
Ph
βΦ8H2P
βΦ8ZnP
βΦ8MTBP
vii)
MeO
Ph
Ph
Ph
Ph
MeO
Ph
Ph
Ph
Ph
N
P
N
N
N
N
N
N
N
viii)
P
PF6
Ph
PF6
Ph
Ph
Ph
Ph
OMe
Ph
Ph
OMe
βΦ8P(V)TBP
βΦ8P(V)P
Scheme 1. Synthesis of bF8MTBP. Reagents and Conditions: i) PhLi, LiBr, dry THF, 70%; ii) H3PO4, dry toluene, reflux; iii) trans-1,2-bis(phenylsulfonyl)ethylene,
o-dichlorobenzene, autoclave, 180 °C, 3 h, 45% (from 2); iv) CNCH2CO2Et, KOt-Bu, dry THF, 93%; v) 1. LiAlH4, dry THF, 2. p-TsOH•H2O, CHCl3, 3. p-chloranil;
vi) Zn(OAc)2•2H2O, CHCl3, 88%; vii) 1. POBr3, dry pyridine, 2. MeOH, 62%; viii) 200°C, quant.
Porphyrin bF8H2P was synthesized by reduction of 6 with
LiAlH4, followed by acid-mediated tetramerization and oxidation
with p-chloranil in 74% yield.[14] Zinc(II) porphyrin bF8ZnP was
readily prepared in 88% yield by reaction with Zn(OAc)2. BCOD-
fused porphyrin bF8H2P reacted with POBr3 in pyridine to give
the corresponding phosphorus complexes, which were treated
with MeOH and then KPF6, to afford bF8P(V)P in 62% yield.[10]
The thermal conversion processes of bF8ZnP was investigated
by using thermogravimetric analysis (TGA), as shown in Figure
2. Weight loss from this compound starts at around 150 °C and
finishes at around 200 °C. The amount lost was 11%,
corresponding to the removal of four ethylenes, closely matching
the calculated values of 9%. When the retro Diels–Alder
reactions of bF8MP (M = H2 and Zn) and bF8P(V)P were carried
out in a glass tube oven at 200 °C under reduced pressure,
TBPs bF8MTBP (M = H2 and Zn) and bF8P(V)TBP were
obtained in quantitative yields.
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10.1002/ejoc.201900528
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detected by mass spectroscopy. The oxidation with DDQ in the
presence of methanesulfonic acid in refluxing toluene resulted in
decomposition of aF8H2P. The reaction with excess amount of
DDQ (molar ratio: aF8H2P/DDQ = 1/50) in refluxing toluene gave
a mixture of aF8H2TBP, mono- and dichlorinated aF8H2TBP,
which could not be purified by column chromatography. In 2008,
Vinogradov, Cheprakov and co-workers reported the complete
aromatization of cyclohexene-fused meso-diphenylporphyrin
0
-2
-4
-6
-8
using
2,3,4,5-tetraphenylcyclopentadienone
(tetracyclone),
which resulted in the formation of meso-diphenylTBPs and
tribenzonaphthoporphyrins which was formed by Diels–Alder
reaction of fused benzene moiety and another tetracyclone,
followed by aromatization by CO extruction.[15] In a case of
aF8H2P, the byproduct would not be formed due to the steric
hindrance of the peripheral phenyl groups. A mixture of aF8H2P
and tetracyclone was heated at 230 °C in an autoclave for 3
days to give aF8H2TBP in 49% yield. The free base aF8H2TBP
was readily converted into the zinc(II) porphyrin, aF8ZnTBP, in
61% yield. Phosphorus TBP, aF8P(V)TBP, was obtained by
insertion of phosphorus using POBr3 in pyridine, followed by
exchange of axial substituents and counter anion.
-10
-12
100
150
Temperature / °C
200
250
Figure 2. Thermogravimetric analysis of bF8ZnP.
As a starting pyrrole for TBPs aF8MTBP (M = H2 and Zn)
and aF8P(V)TBP, cyclohexene-fused pyrrole 10 was prepared
as shown in Scheme 2. The Diels–Alder adduct 8 was obtained
by
heating
a
mixture
of
7
and
trans-1,2-
bis(phenylsulfonyl)ethylene in toluene at 155 °C in an autoclave.
Barton-Zard reaction of 8 afforded p-terphenyl by base-mediated
successive eliminations instead of the desired cyclohexadiene-
fused pyrrole. Cyclohexene-fused pyrrole 10 was prepared by
Pd-catalyzed hydrogenation of 8, followed by Barton-Zard
reaction. Porphyrin aF8H2P was synthesized by reduction of 10
with LiAlH4 followed by acid-mediated tetramerization and
oxidation with p-chloranil in 60% yield.
Ph
Ph
Ph
Ph
CO2Et
NH
SO2Ph
SO2Ph
SO2Ph
SO2Ph
i)
ii)
iii)
iv)
Ph
Ph
Ph
Ph
8
9
10
7
Ph
Ph
N
Ph
Ph
Ph
Ph
Ph
Ph
NH
N
N
N
N
v)
M
N
HN
Ph
Ph
Ph
Ph
Figure 3. Molecular structures of (a) bF8ZnTBP and (b) aF8ZnTBP. The
thermal ellipsoids were scaled to the 50% probability level. Hydrogen atoms
and solvent molecules have been omitted for clarity.
Ph
Ph
Ph
Ph
αΦ8H2P
αΦ8H2TBP
αΦ8ZnTBP
vi)
The meso-tetraphenylated free-base TBP, m 4H2TBP,
F
was yielded quantitatively by heating BCOD-fused meso-
tetraphenyl porphyrin free base under reduced pressure. For the
introduction of the phosphorus(V) ion, phosphorus(V)
oxybromide (POBr3) is a good source.[10,16] However, the
Scheme 2. Synthesis of aF8MTBP. Reagents and Conditions: i) trans-1,2-
bis(phenylsulfonyl)ethylene, toluene, autoclave, 155 °C, 20 h, 61%; ii) H2,
Pd/C, CH2Cl2, 96%; (iii) CNCH2CO2Et, KOt-Bu, dry THF, reflux, 56%; iv) 1.
LiAlH4, dry THF, 2. p-TsOH•H2O, CHCl3, 3. p-chloranil, 60%; v) tetracyclone,
230 °C, 3 d, 49%; (vi) Zn(OAc)2•2H2O, CHCl3, 61%.
reaction of m 4H2TBP with POBr3 afforded complex mixtures,
F
such that the desired complex could not be separated. As
porphyrin phosphorus(V) complexes were synthesized from
free-base porphyrins and phosphorus(V) oxychloride (POCl3),[11f]
Oxidative aromatization of aF8H2P was carried out under
various conditions. When a solution of aF8H2P was refluxed with
DDQ (molar ratio: aF8H2P/DDQ = 1/16) in THF, octahydroTBP
was obtained as a major product together with hydroTBPs,
the reaction of
m 4H2TBP and POCl3 yielded pure
F
m
F
4P(V)TBP-Cl with conventional separation methods.
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10.1002/ejoc.201900528
European Journal of Organic Chemistry
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Although the axial ligands of this complex were chloride at this
stage, the P–Cl bonds were relatively stable under ambient
conditions. The introduction of methoxy groups at axial positions
proceeded smoothly in a methanol/pyridine solution of crude
F F
m 4P(V)TBP-Cl at reflux temperature, and m 4P(V)TBP-OMe
containing two OMe groups as axial ligands was obtained in
moderate yield. For a comparison of the physical properties
tetraphenylporphyrin phosphorus complexes containing two Cl-
and OMe axial ligands (m 4P(V)TPP-
4P(V)TPP-Cl[11f] and m
F F
OMe) were also synthesized by the same procedure. Finally, the
counter anion was replaced by excess NaClO4, producing the
desired meso-tetraphenyl-substituted phosphorus TBPs and
TPPs as perchlorate salts.
between
TBP
and
normal
porphyrins,
meso-
Figure 4. Molecular structures of (a) aF8P(V)TBP, (b) m
F
4P(V)TBP-OMe and (c) m 4P(V)TPP-OMe. The thermal ellipsoids were scaled to the 50% probability level.
F
Hydrogen atoms and solvent molecules have been omitted for clarity.
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10.1002/ejoc.201900528
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Figure 5. Views of the skeletal deviation of the atoms from the 4N mean plane for (a) bF8ZnTBP (black line) and aF8ZnTBP (red line), (b) aF8P(V)TBP, (c) m
F
4P(V)TBP-
OMe and (d) m
F
4P(V)TPP-OMe. Black circles indicate carbon atoms. Blue triangles and squares indicate nitrogen atoms at meso-positions and coordinating nitrogen atoms,
respectively.
Single-crystal and X-ray structure
and macrocycle is important for understanding the substitution
Single crystals of bF8ZnTBP, aF8ZnTBP,
m
F
8P(V)TBP,
effect at the meso-position. The average tilt angles in
m
F
4P(V)TBP-OMe, and m
F
4P(V)TPP-OMe were obtained by
m 4P(V)TBP-OMe and m 4P(V)TPP-OMe are 78.5° in the
F F
recrystallization from
pyridine/MeOH, pyridine/MeOH,
67.7–87.7° range and 62.1° in the 60.4–63.7° range,
respectively. The average tilt angle between the b-aryl groups
and TAP macrocycle of phosphorus(V) TAP was 41.0°,[10b] which
is smaller than that of the complexes in this work. Hence the
orbital interaction between the meso-aryl groups and macrocycle
CH2Cl2/MeOH, CHCl3/hexane, and chlorobenzene/hexane,
respectively and were used for X-ray crystallographic analysis.
The crystallographic data are summarized in Table S1. These
TBPs and TPP crystallized in a triclinic unit cell (space group P¯1,
Z = 1) for bF8ZnTBP, in a triclinic unit cell (space group P¯1, Z =
in m 4P(V)TBP-OMe and m 4P(V)TPP-OMe may be weaker.
F F
2) for aF8ZnTBP, in an orthorhombic unit cell (space group Pnma
Z = 4) for aF8P(V)TBP, in a orthorhombic unit cell (space group
,
The macrocycles are severely ruffled due to the small atomic
radius (106 pm) of the phosphorus(V) ion,[17] as in the reported
Pbca, Z = 8) for m
F
4P(V)TBP-OMe, and in a triclinic unit cell
4P(V)TPP-OMe. The molecular
crystal
structure
of
azaporphyrinoid
phosphorus(V)
(space group P¯1, Z = 2) for m
F
complexes.[10] Figures 5b, c, and d, respectively, show the
structures are shown in Figures 3 and 4. In bF8ZnTBP, two
pyridines are coordinated to zinc as axial ligands. Dihedral
angles of 39-71° are observed between the benzo moieties and
the peripheral phenyl groups. While bF8ZnTBP adopts a planar
conformation with an Dr value of 0.091 Å, which was calculated
as the square root of the sum of the squares of the deviation of
each atom from the 4N mean plane, there is a marked saddling
of the porphyrin ring of aF8ZnTBP due to steric hindrance
between peripheral phenyl groups of the neighboring isoindole
moieties (Figure 5a). The mean Dr value of aF8ZnTBP is 0.55 Å,
more than six-times larger than the value of bF8ZnTBP (0.091
Å). Zinc in aF8ZnTBP is slightly pulled out of the porphyrin plane
by the coordinated axial pyridine.
displacement of the 24 core atoms from the 4N mean plane of
4P(V)TBP-OMe, and m 4P(V)TPP-OMe. The
aF8P(V)TBP, mF F
Dr (distortion of the core) values of aF8P(V)TBP (0.68 Å) and
m
m
F
F
4P(V)TBP-OMe (0.65 Å) are larger than those of
4P(V)TPP-OMe (0.56 Å), the reported a-phenylPc[10d] and
Te-substituted Pc (0.61 Å),[10c] which were the most distorted
simple (aza)porphyrinoids known to date. The mechanism of
distortion by the introduction of the phosphorus(V) ion can be
explained by a mismatch between the size of phosphorus(V) ion
(106 pm) and macrocyclic core so that the size of the core
should be discussed in relation to the distortion of
phosphorus(V) complexes. In fact, the distances between the
two pyrrole nitrogen atoms at opposite sides in the core of
The phosphorus atom sits in the center of the 4N mean
plane of the porphyrin macrocycles. Dihedral angles of ca. 50°
are observed between the benzo moieties and a-phenyl groups
for aF8P(V)TBP. The tilt angle between the meso phenyl groups
4P(V)TBP-OMe, and m 4P(V)TPP-OMe (i.e.
aF8P(V)TBP, mF F
3.63–3.67 Å) are shorter than that of aF8ZnTBP (4.02 Å) or
ZnTBC (4.12 Å)[18] and similar to those of the other
phosphorus(V) complexes[10,11], strongly suggesting that the
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10.1002/ejoc.201900528
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severe distortion of the phosphorus complexes was induced by
the small P(V) ion. Indeed, comparison of the data between
Figures 5a and 5b indicates that the displacement of a central
Zn(II) ion by a small P(V) ion increases the non-planarity of the
aF8TBP macrocycle. Data in Figures. 5c and 5d further show
that removal of four fused benzene rings, i.e. on going from
complexes showed sharp peaks for all protons. The broad
signals were split into five kinds of sharp signal at low
temperature in CD2Cl2 (Figure S1).[19] The 1H-1H COSY
spectrum at –70°C indicated that five protons of meso-phenyl
groups were observed as non-equivalent due to a distortion of
the TBC macrocycle (Figure S2). The 31P NMR spectrum of
m
F
4P(V)TBP-OMe to
m
F
4P(V)TPP-OMe, reduces the
m 4P(V)TBP-OMe exhibited only one peak at –177 ppm,
F
displacement from the 4N mean plane to some extent.
supporting hexacoordinated phosphorus representations as the
other (aza)porphyrinoid phosphorus(V) complexes.[10] The signal
NMR spectroscopy
of m 4P(V)TBP-OMe locates between those of PPcs (~–170
F
ppm) and PTAPs (~–180 ppm), indicating that the order of the
shielding effect of the diatropic ring current is TAP > TBP > Pc.
The 1H NMR spectrum of m
F
4P(V)TBP-OMe in CDCl3 or CD2Cl2
shows broad signals for meso-phenyl groups, while those of
4P(V)TPP-OMe and reported azaporphyrin phosphorus(V)
m
F
Figure 6. Electronic absorption (bottom) and MCD spectra (top) of (a) m
F
4H2TBP (blue) and P(V)TBP-OMe (red), (b) m
F
4H2TPP (blue) and m
F
4P(V)TPP-OMe
(red), and (c) aF8P(V)TBP (blue) and bF8P(V)TBP (red). The MCD spectra of m 4H2TBP and m 4H2TPP have already been reported in the literature, in ref. 23.
F F
Electronic absorption and MCD spectra
The absorption data are summarized in Table 1, with the
absorption and MCD spectra of some compounds shown in
of aF8 species always appear at longer wavelengths than those
of the bF8 species. For example, on going from bF8H2P to
aF8H2P, the Soret band shifted from 393 to 412 nm, while the
Q00 band shifted from 497-616 to 508-628 nm, and on going
from bF8ZnTBP to aF8ZnTBP, the Soret shifted from 438 to 461
nm, while the Q00 band shifted from 590-641 to 615-668 nm. The
shift of the Soret band of P(V)TBP species is fairly small (452 to
454 nm for b to a) but the Q00 band shifts significantly from 590-
641 to 615-668 nm. ii) Among P(V) species having axial ligands,
those with a Cl group always show both the Soret and Q bands
at longer wavelengths than those with an axial OMe group. For
Figure 6, together with absorption spectra of
a
- and bF8ZnTBP
in Figure S3 and m 4P(V)TBP-Cl and -OMe and m
F
F
4P(V)TPP-
Cl and -OMe in Figure S4. In Table 2, the energy differences
between the Q00 and Soret bands, which reflect the magnitude
of configuration interactions between the two Eu excited states,
are summarized from the data in Table 1. In obtaining the data
in Table 2, the central values of the two split Q and/or Soret
bands of metal-free species were adopted, in order to compare
the data with those of the Zn and P(V) species. From the data in
these two Tables, the following are observed experimentally. i)
On comparing the aF8 and bF8 species, the Soret and Q bands
example, comparing m 4P(V)TBP-OMe and m 4P(V)TBP-Cl,
F F
the Soret shifted from 456 to 467 nm, while the Q00 band shifted
from 645-707 to 649-714 nm. In a similar manner, on going from
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10.1002/ejoc.201900528
European Journal of Organic Chemistry
FULL PAPER
m
F
4P(V)TPP-OMe and m
F
4P(V)TPP-Cl, the Soret and Q00
aF8H2TBP to 8.798 kcm-1 for aF8P(V)TBP-OMe, and from 7.656
for bF8H2TBP to 7.919 kcm-1 for bF8P(V)TBP-OMe. In addition,
as seen in Figures 6, and Tables 1 and 2) the relative intensity
of the Q band to the Soret band is larger for TBP species than
for normal porphyrins without fused benzo groups. This appears
to originate from the larger splitting of the HOMO and HOMO-1
bands moved from 431 to 440 and 602 to 613 nm, respectively.
iii) The splitting between the Soret and Q00 band decreased on
changing from the metal-free species to P(V) species in the case
of porphyrins without fused benzo rings, but inversely increased
in the case of benzoporphyrins. For example, on going from
4H2TPP to m 4P(V)TPP-OMe, (DHOMO) of the former compared to the latter, due to
bF8H2P to bF8P(V)P and from mF F
the values decreased from 8.496 to 7.354 kcm-1and from 7.768
to 6.591 kcm-1, respectively. Inversely, for TBP derivatives,
however, the value generally increased from 6.910 for
stabilization of the a2u type orbital, as has been reported
previously in the comparison of absorption spectra of ZnTPP,
ZnTBP and Zn phthalocyanine (ZnPc).[20]
m
F
4H2TBP to 7.786 kcm-1 for m
F
4P(V)TBP-OMe, from 6.961 for
Table 1. Absorption data of porphyrins in CHCl3.
ompound
bF8H2P
lmax / nm (log e)
393 (5.26)
404 (5.44)
410 (5.15)
412 (5.37)
424, 443
497 (4.24), 530 (3.96), 564 (3.84), 616 (3.34)
bF8ZnP
528 (4.26), 564 (4.23), 584(3.76)
546 (4.17), 587 (4.04)
bF8P(V)P
aF8H2P
508 (4.16), 542 (4.15), 575 (3.87), 628 (3.72)
575, 626, 674
bF8H2TBP
bF8ZnTBP
438 (5.65)
590 (4.25), 641 (5.21)
453 (5.32), 471
(5.51)
aF8H2TBP
610 (4.28), 660 (4.96), 702 (4.76)
aF8ZnTBP
461 (5.41)
452 (5.34)
454 (5.12)
615 (4.17), 668 (5.12)
643 (4.30), 704 (4.97)
680 (4.13), 756 (4.95)
bF8P(V)TBP-OMe
aF8P(V)TBP-OMe
450 (sh),
465 (5.51)
m
F
4H2TBP
592 (4.18), 641 (5.29), 697 (3.99)
m
F
m
F
m
F
m
F
m
F
4P(V)TBP-Cl
4P(V)TBP-OMe
4H2TPP
467 (5.30)
456 (5.40)
418 (5.64)
440 (5.48)
431 (5.47)
649 (3.90), 714 (4.84)
645 (4.00), 707 (4.84)
515 (4.20), 550 (3.74), 590 (3.70), 647 (3.60)
569 (4.15), 613 (3.85)
4P(V)TPP-Cl
4P(V)TPP-OMe
560 (4.15), 602 (3.48)
that the MO energy increases by the introduction of this group.
However, the extent of destabilization depends on the position.
Since the HOMO has more LCAO coefficient of carbon at a
positions, the HOMO destabilizes more when phenyl (F) groups
are linked at a positions rather than b positions. Since the Q00
band has significant contributions from the HOMO-LUMO
transition, particularly for TBP species, the aF8TBP species has
its Q band at longer wavelength compared to the bF8TBP
species, as is indeed observed. (b) Using the notation of D4h
symmetry, the two LUMOs are always eg type, while the HOMO
of tetraphenylporphyrin is a2u type, and that of TBP is a1u type.
As shown in Figure 9, when butadiene, whose HOMO is a1u-like,
is linked to the b-position of the pyrrole of normal porphyrin to
furnish TBPs, the a2u type orbital has a non-bonding interaction
with the HOMO of butadiene, while the a1u type orbital produces
stabilized bonding and destabilized anti-bonding (HOMO)
The MCD spectra of all metal complexes showed
dispersion type Faraday A-term type curves corresponding to
the Q and Soret absorption bands, and signs changed from
minus to plus in ascending energy, since the excited state is
degenerate or nearly degenerate even if there is some
deformation of the ligand. The minus-to-plus MCD sign
experimentally suggests that the DHOMO is larger than DLUMO
(= LUMO+1 – LUMO)[21] and this is reproduced later in the MO
calculation section.
Electronic structures
To carry out an in-depth analysis of the electronic structures,
molecular orbitals (MOs) and transition energies were calculated
for the free-base, Zn and P(V)-OMe species, with the results
shown in Figures. 7 and 8 and summarized in Table S2. From
Figures 7 and 8, the following can be easily understood. (a)
Phenyl groups always function as electron-donating groups, so
orbitals.[24] Since the
approximation to the HOMO-LUMO (and/or LUMO+1) transition,
Q band corresponds in the first
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10.1002/ejoc.201900528
European Journal of Organic Chemistry
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Table 2. Energy differences between the Q00 and Soret bands, calculated from Table 1.
E(Soret)-E(Q00) / kcm-1
Compound
bF8H2P
l
max(Soret or Q00) / nm (kcm-1)
8.496
393 (25.445)
404 (24.752)
410 (24.390)
412 (24.272)
434 (23.041)
438 (22.831)
462 (21.645)
461 (21.692)
452 (22.124)
454 (22.026)
458 (21.858)
467 (21.413)
456 (21.930)
418 (23.923)
440 (22.727)
431 (23.202)
590 (16.949)
584 (17.123)
587 (17.036)
602 (16.625)
650 (15.385)
641 (15.601)
681 (14.684)
668 (14.970)
704 (14.205)
756 (13.228)
669 (14.948)
714 (14.006)
707 (14.144)
619 (16.155)
613 (16.313)
602 (16.611)
7.629
bF8ZnP
7.354
bF8P(V)P
8.127
aF8H2P
7.656
bF8H2TBP
bF8ZnTBP
aF8H2TBP
aF8ZnTBP
bF8P(V)TBP-OMe
aF8P(V)TBP-OMe
7.230
6.961
6.722
7.919
8.798
6.910
m
F
m
F
m
F
m
F
m
F
m
F
4H2TBP
7.407
4P(V)TBP-Cl
4P(V)TBP-OMe
4H2TPP
7.786
7.768
6.144
4P(V)TPP-Cl
4P(V)TPP-OMe
6.591
Figure 7. Partial molecular energy diagram and orbitals of phosphorus(V) TBPs (left) and meso-tetraphenylporphyrin complexes (right), and their calculated
absorption spectra (bottom). Blue and red plots indicate occupied and unoccupied MOs, respectively. Calculations were performed at the B3LYP/6-31G* level.
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10.1002/ejoc.201900528
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Figure 8. Partial molecular energy diagram and orbitals of bF8TBP (left) and aF8TBP (right) complexes and their calculated absorption spectra (bottom). Blue
and red plots indicate occupied and unoccupied MOs, respectively. Calculations were performed at the B3LYP/6-31G* level.
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10.1002/ejoc.201900528
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Figure 9. Interaction between a1u and a2u type orbitals of m
F
4H2TPP and butadiene to produce m
F
4H2TBP molecular orbitals (left) and effect of insertion of P(V)
ion into metal-free TBP and TPP orbitals (right).
particularly for TBPs, this explains why the Q band of TBPs
appears at longer wavelength compared to normal porphyrins. In
addition, the resulting larger HOMO and HOMO-1 energy gap
explains why the Q band of TBPs is stronger than that of normal
porphyrins.[22] (c) The highly positive P(V) ion stabilizes all
reasonably explained. (e) While the calculated absorption
spectra broadly reproduced the trends observed in the
absorption spectra (positions, intensities and
a type of
transitions) for most of the compounds, for bF8P(V)TBP-OMe
(Figure 8, left, bottom) the intense CT transitions calculated
orbitals, including the four (HOMO-1 to LUMO+1) frontier orbitals, between the Q and Soret bands were not reproduced. This is
so that the orbitals of metal-free derivatives are stabilized by
insertion of the P(V) ion. The extent of stabilization is different
between the a1u and a2u type orbitals: that of the a2u type is more
significant, since it has a larger LCAO coefficient at pyrrole
nitrogens. (d) Although not shown in Figures 7-9, we have
possibly due to the fact that the calculated HOMO-1 and -2 are
substituent-centered orbitals.
Conclusions
F
calculated the MOs of P-Cl bond-containing m 4P(V)TBP-Cl
and m 4P(V)TPP-Cl (Figure S5). In the case of P-Cl complexes,
F
In conclusion, we have successfully synthesized meso-phenyl
the stabilizing effect is larger than for the P-OMe complexes as a
result of the electron-deficient Cl atom. Therefore, both the
HOMO–LUMO and HOMO–1–LUMO energy gaps of the P-Cl
complexes were smaller than those of the corresponding P-OMe
complexes, and the Q and Soret bands appeared at longer
wavelengths. For example, the calculated HOMO–LUMO and
TBPs,
m 4MTBP (M = H2, Zn) and m 4P(V)TBP-OMe
F F
(m 4P(V)TBP-Cl), and peripherally phenyl-substituted TBPs,
F
bF8MTBP (M = H2, Zn), aF8MTBP (M = H2, Zn), bF8P(V)TBP-
OMe, and aF8P(V)TBP-OMe by precursor methods. The
F F
thermal conversion method afforded m 4MTBP, m 4P(V)TBP-
OMe, bF8MTBP and bF8P(V)TBP-OMe from BCOD-fused
precursors. The oxidative aromatization method furnished
aF8MTBP and aF8P(V)TBP-OMe from cyclohexene-fused
precursors. In addition, some P(V)-inserted normal porphyrins
without fused benzene rings were prepared, in order to compare
their properties with those of P(V)-inserted TBPs. The distorted
structures due to the steric hindrance between phenyl groups
and insertion of a phosphorus atom resulted in marked red-
HOMO–1–LUMO energy gaps of m
and 3.08 eV, respectively, compared to 2.21 and 3.09 eV for
4P(V)TBP-OMe, while the location of the experimental Q and
Soret bands of 4P(V)TBP-Cl were 714 and 467 nm
compared to those (707 and 456 nm, respectively) of
F
4P(V)TBP-Cl were 2.18
m
F
m
F
m
F
4P(V)TBP-OMe (Figure S4).
Using Figure 9, we can explain why the Q and Soret bands
of TBPs shifted to the red and blue, respectively, as a result of
P(V) ion insertion in the experiment. Here, the calculated energy
shifted absorptions. The Q bands of
and m 4P(V)TBP-OMe (-Cl also) extended to above 700 nm.
The X-ray crystallographic analysis revealed saddle
a
- and bF8P(V)TBP-OMe
F
differences of m
F
4H2TPB are 2.38 eV for HOMO~LUMO and
4P(V)TBP are
a
2.90 eV for HOMO-1~LUMO+1 and those of m
F
conformation for aF8ZnTBP as a result of steric hindrance
2.15 and 3.10 eV, respectively. Since the contributions of
HOMO~LUMO (or LUMO+1) and HOMO-1~LUMO (or LUMO+1)
are significant for the Q and Soret bands, respectively, the Q
band shifts to the red while the Soret band appears at shorter
wavelength as a result of P(V) ion insertion. Specifically, the a1u
HOMO having nodes at pyrrole nitrogens is less stabilized
compared with a2u HOMO-1 which has large coefficients at
pyrrole nitrogens. In the case of normal porphyrins without fused
benzo-groups such as TPP, these values do not change
significantly between metal-free and P(V) ion-inserted species:
between peripheral phenyl groups of the neighboring isoindole
F
moieties, and a ruffle conformation for m 4P(V)TBP-OMe and
F
m 4P(V)TPP-OMe similar to tetraazaporphyrin phosphorus
complexes.[10b] The synthetic strategy based on the precursor
method afforded p-expanded porphyrins with fine-tuning of their
optical properties. Upon P(V) ion-insertion into m
Q and Soret bands shifted to shorter and longer wavelengths,
respectively, while inversely, insertion into m 4H2TBP caused a
F
4H2TPP, the
F
red- and blue-shift of the Q and Soret bands, respectively, which
was reasonably explained and reproduced by molecular orbital
calculations.
the values of m
HOMO~LUMO and HOMO-1~LUMO+1, respectively, and the
corresponding values of m 4P(V)TPP-OMe are 2.75 and 3.03
eV, suggesting that the Q band of m 4P(V)TPP-OMe may
appear at slightly shorter wavelength than that of m 4H2TPP, as
F
4H2TPP are 2.70 and 3.02 eV for the
F
F
Experimental Section
F
is indeed observed experimentally. In calculated absorption
spectra in Figure. 9 (right, bottom), the Q and Soret bands of
Methods and Materials
m
F
4P(V)TPP-OMe appear at shorter and longer wavelengths
compared to those of m 4H2TPP, while inversely those of
4P(V)TBP-OMe appear at longer and shorter wavelengths
compared to 4H2TBP, respectively, reproducing the
NMR spectra were obtained on
a Bruker AVANCE 500
F
spectrometer or a JEOL AL-400 spectrometer. Chemical shifts
are expressed in d (ppm) values, and coupling constants are
expressed in hertz (Hz). 1H-NMR spectra were referenced to the
residual solvent as an internal standard. 31P-NMR spectra were
referenced to external 85% H3PO4 solution (0.0 ppm). The
m
F
m
F
experimentally-observed trend (Figure 6 and Tables 2 and 3).
Thus, the increase and decrease of configuration interaction on
F
P(V) ion insertion into H2TBP and H2P (and m 4H2TPP) are
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10.1002/ejoc.201900528
European Journal of Organic Chemistry
FULL PAPER
following abbreviations are used: s = singlet, d = doublet, m =
multiplet, and brs = broad singlet. High-resolution mass spectra
(HRMS) were recorded on a Bruker Daltonics Apex-III or a
with water and brine, dried over Na2SO4, and concentrated
under reduced pressure. The residue was purified by column
chromatography on silica gel with CHCl3 to give bF8ZnP (26 mg,
88%). Red solid; mp > 150 °C (decomp); MS (FAB) m/z 1293
[M+H]+, 1181 [M+H−4C2H4]+; 1H NMR (400 MHz, CDCl3) d
10.66–10.34 (m, 4H, meso), 7.58–7.22 (m, 40H, Ph), 6.13 (m,
8H, bridge head), 2.74–2.50 (m, 8H, bridge), 2.34–2.10 (m, 8H,
bridge); UV-vis (CHCl3) lmax, nm (log e) 404 (5.44), 528(4.26),
564 (4.23), 584(3.76); Anal. Calcd for C92H68N4Zn·1/2H2O: C,
84.74; H, 5.33; N, 4.30. Found: C,84.54; H, 5.63; N, 4.54.
Bruker Daltonics solariX 9.4
absorption spectra were recorded on
T
spectrometer. Electronic
JASCO V-570
a
spectrophotometer. Magnetic circular dichroism (MCD) spectra
were recorded on a JASCO J-725 spectrodichrometer with a
magnetic field of up to 1.03 T. XRD measurement and elemental
analyses were performed in ADRES, Ehime University. Melting
points were determined on a Büchi melting point M-565
apparatus. Unless otherwise noted, materials were purchased
from Tokyo Kasei Co., Aldrich Inc., and other commercial
suppliers and were used after appropriate purification (distillation
or recrystallization).
[Tetrakis(
b
-diphenylBCOD)porphyrinato]phosphorus(V)
(
bF8P(V)P): To a mixture of bF8H2P (101 mg, 0.082 mmol) in
dry pyridine (16 ml) was added POBr3 (3.6761 g) under an Ar
atmosphere, and the resulting mixture stirred at room
temperature for 4 h. After addition of dry MeOH (29 ml) and dry
CH2Cl2 (16 ml), the mixture was refluxed for 19 h, then
concentrated under reduced pressure and extracted with CH2Cl2.
The organic layer was washed with water, dried over Na2SO4,
and concentrated under reduced pressure. The residue was
purified by column chromatography on alumina with CH2Cl2 and
then MeOH/CH2Cl2 (v/v 1/9). After removal of the solvent, the
red crude product was dissolved in dry CH2Cl2 (31 ml) and KPF6
(275 mg, 1.5 mmol) added to the solution under an N2
atmosphere. After strirring at room temperature for 13 h, the
reaction mixture was washed with water, dried over Na2SO4, and
concentrated under reduced pressure. The residue was washed
with ether to give bF8P(V)P (75 mg, 62%). Purple crystals; mp >
124 °C (decomp); MS (MALDI-TOF) m/z 1322 [M−PF6]+ , 1209
[M−4C2H4]+; 1H NMR (400 MHz, CDCl3) d 10.11–9.86 (m, 4H,
meso), 7.60–6.95 (m, 40H, Ph), 6.06–5.92 (m, 8H, bridge head),
2.80–2.40 (m, 12H, bridge), 2.34–2.01 (m, 4H, bridge), −2.50–
−2.75 (m, 6H, POMe); UV-vis (CHCl3) lmax, nm (log e) 410 (5.15),
546 (4.17), 587 (4.04); Anal. Calcd for C94H74N4O2P2·2H2O: C,
75.09; H, 5.23; N, 3.73. Found: C,74.92; H, 5.48; N, 3.66.
The X-ray diffraction data were recorded at 100 K on a Rigaku
CCD detector (Saturn 724) mounted on a Rigaku rotating anode
X-ray generator (MicroMax-007HF) using CuKa and MoKa
radiation from the corresponding set of confocal optics. The
structures were solved with SIR2004[25] and refined with
SHELXL-97.[26] All calculations were performed by using the
Crystal Structure crystallographic software package.[27] CCDC-
1588352 (bF8ZnTBP), 1588353 (aF8ZnTBP), and 1588354
(
aF8P(V)TBP),
1827221
(m
F
4P(V)TBP-OMe),
1827222
(m 4P(V)TPP-OMe) contain the supplementary crystallographic
F
data for this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre.
Tetrakis( -diphenylBCOD)porphyrin (bF8H2P): To a solution
b
of 6 (117 mg, 0.32 mmol) in dry THF (8 ml) was added LiAlH4
(71 mg, 1.9 mmol) at 0 °C under an Ar atmosphere. The
resulting mixture was stirred at the same temperature for 2 h,
then the reaction quenched by addition of sat. aqueous
potassium sodium tartrate. After filtration with Celite, the filtrate
was extracted with EtOAc. The organic layer was washed with
brine, dried over Na2SO4, and concentrated under reduced
pressure. The residue was diluted with CHCl3 (60 ml) and p-
TsOH·H2O (7 mg) was added. After stirring at room temperature
for 18 h, the mixture was stirred with p-chloranil (52 mg) for 1 h,
then the reaction mixture washed with sat. aqueous NaHCO3,
water and brine, dried over Na2SO4, and concentrated under
reduced pressure. The residue was purified by column
chromatography on alumina with CHCl3 to give bF8H2P (73 mg,
74%). Brown crystals; mp > 150 °C (decomp); MS (FAB) m/z
Retro Diels-Alder reaction of BCOD-fused porphyrins:
Porphyrins bF8MPs and bF8P(V)P (ca. 10 mg each) were
heated at 200 °C under reduced pressure for 1 h in a glass tube
to give bF8MTBPs and bF8P(V)TBP in quantitative yields.
bF8H2TBP[4]: Green solid; MS (MALDI-TOF) m/z 1119 [M+H]+;
UV-vis (CHCl3) lmax, nm, 424, 443, 575, 626, 674 nm.
bF8ZnTBP[4]: Green solid; MS (MALDI-TOF) m/z 1181 [M+H]+;
UV-vis (CHCl3) lmax, nm (log e) 438 (5.65), 590 (4.25), 641
(5.21).
1
1232 [M+H]+, 1120 [M+H−4C2H4]+; H NMR(400 MHz, CDCl3) d
10.64–10.40 (m, 4H, meso), 7.80–6.80 (m, 40H, Ph), 6.12 (s, 8H, bF8P(V)TBP: Green solid; mp > 213 °C (decomp); MS (MALDI-
bridge head), 2.90–2.44 (m, 8H, bridge), 2.40–1.90 (m, 8H,
bridge), -4.47 (br. s, 1H, NH), -4.51 (br. s, 1H, NH); UV-vis
(CHCl3) lmax, nm (log e) 393 (5.26), 497 (4.24), 530 (3.96), 564
(3.84), 616 (3.34); Anal. Calcd for C92H70N4·1/4CHCl3: C, 87.82;
H, 5.63; N, 4.44. Found: C, 87.99; H, 5.79; N, 4.37.
TOF) m/z 1210 [M−PF6]+; 1H NMR (400 MHz, CDCl3) d 10.15 (br.
s, 4H, meso), 9.38 (br. s, 8H, benzo), 7.66–7.20 (m, 40H, Ph),
−1.33 (d, 6H, J = 27.2 Hz, POMe); UV-vis (CHCl3) lmax, nm (log
e) 452 (5.34), 643 (4.30), 704 (4.97); Anal. Calcd for
C86H58N4O2P2F6·3/2EtOAc: C, 74.28; H, 4.74; N, 3.77. Found: C,
73.98; H, 4.87; N, 4.02.
[Tetrakis( -diphenylBCOD)porphyrinato]zinc(II) (bF8ZnP): To
b
a solution of bF8H2P (28 mg, 0.023 mmol) in CHCl3 (5 ml) was
added a solution of Zn(OAc)2·2H2O (120 mg) in MeOH (1.5 ml)
at room temperature. The resulting mixture was stirred at the
same temperature for 19 h. The reaction mixture was washed
a
-Octaphenylporphyrin (aF8H2P): To a solution of 10 (704 mg,
2.0 mmol) in dry THF (50 ml) was added LiAlH4 (390 mg, 10.3
mmol) at 0 °C under an Ar atmosphere, and the resulting
mixture stirred at the same temperature for 2 h. The reaction
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10.1002/ejoc.201900528
European Journal of Organic Chemistry
FULL PAPER
was quenched by addition of sat. aqueous potassium sodium
tartrate. After filtration with Celite, the filtrate was extracted with
EtOAc. The organic layer was washed with water and brine,
dried over Na2SO4, and concentrated under reduced pressure.
The residue was diluted with CHCl3 (400 ml) and p-TsOH·H2O
(31 mg) added. After stirring at room temperature overnight in
concentrated under reduced pressure, then the residue purified
by column chromatography on alumina with CH2Cl2 followed by
MeOH/CH2Cl2 (v/v 1/1). After removal of the solvent, the green
crude product was dissolved in dry CH2Cl2 (10 ml) and KPF6 (6
mg, 0.033 mmol) added to the solution. After strirring at room
temperature for 18 h, the reaction mixture was washed with
the dark, the mixture was stirred with p-chloranil (291 mg) for 3 h, water, dried over Na2SO4, and concentrated under reduced
then the reaction mixture washed with sat. aqueous NaHCO3,
water and brine, dried over Na2SO4, and concentrated under
reduced pressure. The residue was purified by column
pressure. The residue was washed with CH2Cl2, ether and
hexane to give aF8H2TBP (11 mg, 28%). Green crystals; mp >
230 °C (decomp); MS (FAB) m/z 1209 [M−PF6]+; HRMS calcd
chromatography on alumina with CHCl3 to give aF8H2P (341 mg, for C86H58N4O2P 1209.4297, found 1209.4258; 1H NMR (400
60%). Red crystals; mp > 149 °C (decomp); MS (MALDI-TOF)
m/z 1136 [M+H]+; 1H NMR (400 MHz, CDCl3) d 9.35–8.98 (m,
4H, meso), 7.48–7.09 (m, 24H, Ph), 7.04–6.76 (m, 16H, Ph),
MHz, CD2Cl2) d 8.76 (s, 2H, meso), 8.75 (s, 2H, meso), 7.70 (s,
8H, benzo), 7.44–7.16 (m, 40H, Ph), −0.49 (d, 6H, J = 23.6 Hz,
POMe); UV-vis (CHCl3) lmax, nm (log e) 454 (5.12), 680 (4.13),
5.70–4.84 (m, 8H, CH), 2.86–1.90 (m, 16H, CH2), -3.38--3.74 (m, 756 (4.95); Anal. Calcd for C86H58N4O2PF6·2H2O: C, 74.24; H,
2H, NH); UV-vis (CHCl3) lmax, nm (log e) 412 (5.37), 508 (4.16),
542 (4.15), 575 (3.87), 628 (3.72); Anal. Calcd for
C84H70N4·1/3CHCl3·1/3H2O: C, 85.75; H, 6.06; N, 4.74. Found: C, Meso-tetraphenyltetrabenzoporphyrin (m
4.49; N, 4.03. Found: C, 73.96; H, 4.59; N, 3.98.
4H2TBP) : Meso-
F
85.44; H, 5.95; N, 4.67.
tetraphenylporphyrin free-base complex (20 mg, 0.02 mmol) was
heated at 200°C for 10 min under reduced pressure. Analytically
a
-OctaphenylTBP (aF8H2TBP): A mixture of aF8H2P (48 mg,
pure m 4H2TBP (18 mg, 100%) was obtained as a green
F
0.042 mmol) and tetracyclone (340 mg) was heated at 230 °C
for 3 d under an Ar atmosphere in a pressure tube. After cooling
to room temperature, the mixture was purified by column
chromatography on silica gel with CHCl3/hexane (v/v 1/2),
followed by recrystallization from CHCl3/MeOH to give
aF8H2TBP (23 mg, 49%). Green crystals; mp > 275 °C
(decomp); MS (MALDI-TOF) m/z 1119 [M+H]+; 1H NMR (400
MHz, CDCl3) d 10.04 (br. s, 4H, meso), 7.58 (s, 8H, benzo),
powder. 500 MHz 1H-NMR (CDCl3/1% Et3N) d (ppm): 8.37 (d,
8H, J = 6.84 Hz), 7.93 (t, 4H, J = 7.33 Hz), 7.86 (t, 8H, J = 6.84
Hz), 7.44-6.98 (br, 16H), –1.16 (s, 2H, inner NH). UV-vis (CHCl3)
l
max nm (e x 10–5): 697 (0.10), 641 (1.95), 592 (0.15), 465 (3.20).
Meso-tetraphenyltetrabenzoporphyrin
(m 4P(V)TBP-Cl): POCl3 (0.1 mL) was added to a solution of
4H2TBP (12 mg, 0.015 mmol) in 2 ml pyridine. After stirring
the mixture for 72 h under reflux, it was concentrated in vacuo.
The crude m 4P(V)TBP-Cl was purified by silica gel column
P-Cl
complex
F
m
F
7.51–7.26 (m, 40H, Ph), −0.60 (s, NH, 2H); UV-vis (CHCl3) lmax
,
nm (log e) 453 (5.32), 471 (5.51), 610 (4.28), 660 (4.96), 702
(4.76); Anal. Calcd for C84H54N4·H2O: C, 88.70; H, 4.96; N, 4.93.
Found: C, 88.94; H, 5.15; N, 4.65.
F
chromatography (CH2Cl2 : MeOH = 7 : 1), then alumina column
chromatography (CH2Cl2 : MeOH = 10 : 1). Counteranion
exchange was carried out by dissolving crude m 4P(V)TBP-Cl
F
a
-Octaphenyl ZnTBP (aF8ZnTBP): To a solution of aF8H2TBP
in CH3CN and by adding sodium perchlorate to the solution.
After stirring the mixture for 12 h at room temperature, the
solvent was removed, and the product recrystallized from
(20 mg, 0.018 mmol) in CHCl3 (5 ml) was added a solution of
Zn(OAc)2·2H2O (70 mg) in MeOH (3 ml) at room temperature.
The resulting mixture was stirred at same temperature for 19 h,
then washed with sat. aqueous NaHCO3, water and brine, dried
over Na2SO4, and concentrated under reduced pressure. The
residue was purified by column chromatography on silica gel
with CHCl3 to give aF8ZnTBP (13 mg, 61%).
Green solid; mp > 400 °C (decomp); MS (FAB) m/z 1180 [M]+;
1H NMR (400 MHz, CDCl3) d 10.34 (s, 4H, meso), 7.56 (s, 8H,
benzo), 7.56 (m, 16H, Ph), 7.41 (m, 8H, Ph), 7.35 (m, 16H, Ph);
UV-vis (CHCl3) lmax, nm (log e) 461 (5.41), 615 (4.17), 668
(5.12); Anal. Calcd for C84H52N4Zn·3/2H2O·1/2Hexane: C, 83.40;
H,4.99; N, 4.47. Found: C, 83.33; H, 5.21; N, 4.37.
CH2Cl2/nhexane, to afford pure m
F
4P(V)TBP-Cl (4.0 mg, 23%)
as a green powder. 500 MHz 1H-NMR (CDCl3) d (ppm): 8.01-
7.76 (br), 7.66 (m, 8H), 7.36 (m, 8H). 200 MHz 31P-NMR (CDCl3)
d (ppm): –177. HRMS-MALDI (m/z) Calcd for C60H36Cl2N4P [M–
ClO4]+: 913.2050. Found: 913.2044. UV-vis (CHCl3) lmax nm (e x
10–5): 714 (0.70), 649 (0.08), 467 (1.98).
Meso-tetraphenyltetrabenzoporphyrin
(m 4P(V)TBP-OMe): The crude
dissolved in MeOH, and the mixture stirred for 12 h, then the
solvent removed. The crude m 4P(V)TBP-OMe was purified by
P-OMe
complex
F
F
m 4P(V)TBP -Cl was
F
silica gel column chromatography (CH2Cl2 : MeOH = 10 : 1,
twice). After recrystallization from CH2Cl2/nhexane, pure
a
-Octaphenyl P(V)TBP ( a mixture of
aF8P(V)TBP): To
aF8H2TBP (32 mg, 0.029 mmol) in dry pyridine (7 ml) was
added POBr3 (1.4428 g) under an Ar atmosphere, and the
resulting mixture stirred at room temperature for 61 h. After
addition of dry MeOH (12 ml) and dry CH2Cl2 (6 ml), the mixture
was refluxed for 30 h. The reaction mixture was concentrated
under reduced pressure and extracted with CH2Cl2. The organic
layer was washed with water, dried over Na2SO4, and
m
F
4P(V)TBP-OMe (1.8 mg, 12%) was obtained as a green
1
powder. 500 MHz H-NMR (CDCl3) d (ppm): 7.98-7.82 (br), 7.56
(m, 8H), 7.28 (m, 8H), –0.55 (d, 6H, JPH = 24.4 Hz). 200 MHz
31P-NMR (CDCl3) d (ppm): –177. HRMS-MALDI (m/z) Calcd for
C62H42N4O2P [M–ClO4]+: 905.3040. Found: 905.3034. Found:
905. UV-vis (CHCl3) lmax nm (e x 10–5): 707 (0.70), 645 (0.10),
456 (2.54).
3
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10.1002/ejoc.201900528
European Journal of Organic Chemistry
FULL PAPER
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F
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4P(V)TBP-Cl but using m
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4H2TPP
1
(50 mg, 80 µmol) in 5 ml pyridine. 500 MHz H-NMR (CDCl3) d
(ppm): 9.14 (d, 8H), 7.99 (m, 8H), 7.79 (m, 12H). 200 MHz 31P-
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(CHCl3) lmax nm (e x 10–5): 613 (0.07), 569 (0.14), 440 (2.99).
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OMe): Methanol was added to pyridine solution of
4P(V)TPP-Cl and stirred for 12 h under reflux temperature.
F
4P(V)TPP-
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column chromatography (SiO2, CH2Cl2/MeOH = 7/1, then Al2O3,
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602 (0.03), 560 (0.14), 431 (2.93).
Acknowledgements
This work was supported by JSPS KAKENHI Grant Numbers
18K19071 (TF), JP26410052 (TO), JP25110003 (HU), and
18K05076 (NK). TF also thanks The Kyoto Technoscience
Center Foundation and Kanazawa University SAKIGAKE Project
2018. We thank the Advanced Research Support Center in
Ehime University for permission in obtaining the MALDI-TOF
mass spectra.
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Keywords: tetrabenzoporphyrin • phosphorus • electronic
structure • phenyl group • absorption spectra
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Entry for the Table of Contents
FULL PAPER
Tetrabenzoporphyrins
T. Furuyama,* T. Okujima,* K.
Muramatsu, Y. Takahashi, A. Mikami, T.
Fukumura, S. Mori, T. Nakae, M.
Takase, H. Uno, N. Kobayashi*
Page No. – Page No.
The first synthesis of tetrabenzoporphyrin phosphorus(V) complexes has been
developed. All phosphorus(V) compounds showed the Soret and Q bands beyond
450 and 700 nm, respectively. The effects of fused benzo-groups and peripheral
substituted phenyl groups were rationalized by theoretical calculations.
Synthesis, Structural and Optical
Properties of Tetrabenzoporphyrin
Complexes Bearing Four or Eight
Peripheral Phenyl Groups
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