Preparation of 1,3-diphenylselenophenotetraazaporphyrinato ruthenium(II) Bis(4-methylpyridine) by the reaction of 3,4-dicyano-2,5-diphenylselenophene and phthalonitrile: Its optical and electrochemical properties

Article abstract of DOI:10.1002/hc.21178

2,5-Diphenylselenophene (2a) was treated with bromine and then copper(I) cyanide to produce 3,4-dicyano-2,5-diphenylselenophene (4). Compound 4 was mixed with phthalonitrile, and the mixture was reacted with ruthenium(III) trichloride and 4-methylpyridine in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in refluxed 2-ethoxyethanol to give 1,3-diphenylselenophenotetraazaporphyrinato ruthenium(II) bis(4-methylpyridine) (6). The structure of 6 was determined by ¹H NMR and fast atom bombardment mass spectrometry (FABMS). In the ¹H NMR spectrum, the signals of 4-methylpyridine coordinating to the central ruthenium atom were observed at a higher magnetic field than those of free 4-methylpyridine itself but at a lower magnetic field than those of phthaocyaninato ruthenium(II) bis(4-methylpyridine) (7). The ⁷⁷Se NMR spectrum of 6 showed one singlet peak at δ = 759.5 ppm, which is a lower magnetic field than those of 2a and 4. The Q band absorption of 6 (λ_max = 660 nm) lies at a longer wavelength than does that of 7. Oxidation and reduction potentials of 6 were measured with cyclic voltammetry using Ag/AgNO₃ as a reference electrode.

Full text of DOI:10.1002/hc.21178

Heteroatom Chemistry
Volume 25, Number 5, 2014
Preparation of 1,3-Diphenylselenopheno-
tetraazaporphyrinato Ruthenium(II)
Bis(4-methylpyridine) by the Reaction of
3,4-Dicyano-2,5-diphenylselenophene and
Phthalonitrile: Its Optical and Electrochemical
Properties
Takeshi Kimura and Naoko Murakami
Center for Instrumental Analysis, Iwate University, Morioka, Iwate 020-8551, Japan
Received 31 January 2014; revised 22 April 2014
cyclic voltammetry using Ag/AgNO3 as a reference
electrode. 2014 Wiley Periodicals, Inc. Heteroatom
Chem. 25:428–433, 2014; View this article online at
wileyonlinelibrary.com. DOI 10.1002/hc.21178
ABSTRACT: 2,5-Diphenylselenophene (2a) was
treated with bromine and then copper(I) cyanide
to produce 3,4-dicyano-2,5-diphenylselenophene
ꢀC
(4). Compound
4 was mixed with phthaloni-
trile, and the mixture was reacted with ruthe-
nium(III) trichloride and 4-methylpyridine in
the presence of 1,8-diazabicyclo[5.4.0]undec-7-
ene (DBU) in refluxed 2-ethoxyethanol to give
1,3-diphenylselenophenotetraazaporphyrinato ruthe-
nium(II) bis(4-methylpyridine) (6). The structure
of 6 was determined by 1H NMR and fast atom
bombardment mass spectrometry (FABMS). In the
1H NMR spectrum, the signals of 4-methylpyridine
coordinating to the central ruthenium atom were
observed at a higher magnetic field than those of
free 4-methylpyridine itself but at a lower magnetic
field than those of phthaocyaninato ruthenium(II)
bis(4-methylpyridine) (7). The 77Se NMR spectrum of
6 showed one singlet peak at δ = 759.5 ppm, which
is a lower magnetic field than those of 2a and 4.
The Q band absorption of 6 (λmax = 660 nm) lies at
a longer wavelength than does that of 7. Oxidation
and reduction potentials of 6 were measured with
INTRODUCTION
Phthalocyanines have been utilized as dyes, pig-
ments, and catalysts for desulfurization of petroleum
and posses potential applications in fields of so-
lar cells, organic semiconductors, photodynamic
therapy for cancer, and so on [1–3]. As related
compounds, tetraazaporphyrins (TAPs), fused with
five- or six-membered heterocycles such as thio-
phene, thiadiazole, selenadiazole, pyridine, and
pyradine, have been prepared and reported until
now [4–6]. These compounds can be considered
as isosteric structures of phthalocyanine. However,
while TAPs bearing the pyridine, pyradine, thiadia-
zole, and selenadiazole rings are stable, the furan,
pyrrole, and thiophene derivatives are unstable [4].
Although early attempts to prepare TAPs with four
furans, pyrroles, and thiophenes had not given de-
sired products, tetra(2,3-thieno)tetraazaporphyrins
whose four thiophene units are linked at the 2,3-
positions [2,3-TTTAP] (Fig. 1) were reported as sta-
ble derivatives [7].
Correspondence to: Takeshi Kimura; e-mail: kimura@iwate-
u.ac.jp.
Dedicated to Professor Renji Okazaki on the occasion of his
77th birthday.
ꢀC
2014 Wiley Periodicals, Inc.
428

Preparation of 1,3-Diphenylselenophenotetraazaporphyrinato Ruthenium (II) 429
FIGURE 1 TAPs with four chalcogenophenes.
Another
thiophene
derivative,
tetra(3,4-
thieno)tetraazaporphyrin, is also acceptable. In
this compound, four thiophene units are linked
at the 3,4-positions [3,4-TTTAP]; therefore, it is
required that one of the thiophene rings contains
an unusual tetravalent sulfur atom (Fig. 1) [8, 9].
We recently reported the first structure determi-
nation of a ruthenium(II) complex of 3,4-TTTAP
having eight phenyl groups on the thiophene rings
and two 4-methylpyridines as axial ligands [3,4-
TTTAP-Ph8] [8]. Phthalocyaninato ruthenium(II)
complexes can link two axial coordinating groups
and are stable. These ligands can be applied to esti-
mation of the shielding effect of the TAP ring and
can block the aggregation of the planar ring system.
There are several reports about TAP derivatives with
one thiophene ring linked at the 3,4-positions [10].
Recently, TAPs with four selenophene rings,
SCHEME
1 Preparation of 3,4-dicyano-2,5-diphenylt-
hiophene (4): (i) n-BuLi, TMEDA, Et2O, –78°C, 1 h; (ii) I2,
rt, 2 h; (iii) PhB(OH)2, (Ph3P)4Pd, K3PO4, toluene, 105°C, 22
h; (iv) Br2, CH2Cl2, 18 h; (v) CuCN/DMF, 150°C, 18 h; (vi) n-
BuLi, TMEDA, Et2O, –78°C, 1 h; (vii) I2, rt, 2 h; (viii) PhB(OH)2,
(AcO)2Pd, K2CO3, DME, 78°C, 4 h.
tetra(2,3-selenopheno)tetraazaporphyrin
[2,3-
TSTAP] derivatives, which consist of several
positional isomers, were first reported by Heeney
and co-workers [11]. In contrast, to our knowledge,
tetra(3,4-selenopheno)tetraazaporphyrin
TSTAP] has never been reported yet. To prepare
3,4-TSTAP, 3,4-dicyano-2,5-diphenylselenophene
[3,4-
method. It was reported that the phenyl groups
are effective to stabilize nonclassical thiophene,
thieno[3,4-c]thiophene [13]. Therefore, we selected
the phenyl group as substituents of 3,4-TSTAP. Ini-
tially, selenophene (1) was lithiated with n-butyl
lithium in diethyl ether at –78°C in the presence
of N,N,Nꢁ,Nꢁ-tetramethylethylenediamine (TMEDA)
and then treated with iodine to produce 2,5-
diiodolselenophene (2aꢀ) and 2-iodolselenophene
(2bꢀ) (Scheme 1).
(4) was prepared from selenophene via four step
reactions and tetramerization of 4 was attempted
by a method reported previously [8]. On the
other hand, if 4 and phthalonitrile are combined
and cyclized, unsymmetrically substituted TAPs
can be obtained in a statistical manner. This
paper reports the preparation and optical and
electrochemical properties of tetraazaporphyri-
nato ruthenium(II) bis(4-methylpyridine) with the
2,5-diphenylselenophene unit.
Since we could not separate 2aꢀ and 2bꢀ each
other by column chromatography, a mixture of them
was treated with phenylboronic acid in the pres-
ence of tetrakis(triphenylphosphine)-palladium in
toluene to give 2,5-diphenylselenophene (2a) and
2-phenylselenophene (2b) in 22% and 11% yields,
respectively. Compounds 2a and 2b could be iso-
lated by silica gel column chromatography, and the
yields were calculated based on the amount of 1.
RESULTS AND DISCUSSION
A
method for preparing 2,5-disubstituted se-
lenophene was reported by Zeni and co-workers
[12]. We prepared 2,5-diphenylselenophene (2a)
with
a slightly modified procedure of Zeni’s
Heteroatom Chemistry DOI 10.1002/hc

430 Kimura and Murakami
When di(acetoxy)palladium was used as a catalyst,
the reaction gave a similar result. Compound 2a was
further treated with bromine in dichloromethane at
room temperature for 18 h. The reaction proceeded
without any additional catalyst and produced 3,4-
dibromo-2,5-diphenylselenophene (3) in 97% yield.
Finally, 3 was reacted with copper(I) cyanide in DMF
at 150°C for 18 h and the reaction gave 3,4-dicyano-
2,5-diphenylselenophene (4) in 55% yield. On the
other hand, 2b was treated with n-butyl lithium and
then iodine to give 2-iodo-5-phenylselenophene (2c)
in 53% yield. Compound 2c was treated with phenyl-
boronic acid in the presence of di(acetoxy)palladium
in 1,2-dimethoxiethane (DME) but the process pro-
duced 2a in low yield.
The preparation of 3,4-TSTAP fused with four
2,5-diphenylselenophene units was attempted by
the procedure reported previously [8]. Compound
4 was reacted with ruthenium(III) trichloride and
4-methylpyridine in the presence of DBU in 2-
ethoxyethanol at reflux temperature for 48 h. How-
ever, we could not obtain 3,4-TSTAP by the reac-
tion. It is expected that if the four selenophenes
react at the 3,4-dicyano groups and construct the
TAP skeleton, 3,4-TSTAP produced by this treat-
ment has to contain an unusual tetravalent sele-
nium atom in one selenophene ring (Fig. 1). The
tetravalent selenium atom is a bonding system sim-
ilar to the well-known nonclassical selenophene,
selenolo[3,4-c]selenophene, which was reported to
be extremely unstable [14]. Therefore, 3,4-TSTAP
would be more unstable than the 2,3-TSTAP deriva-
tive reported by Heeney and co-workers [11]. Instead
of 3,4-TSTAP, we tried to prepare TAP fused with
the several 2,5-diphenylselenophene units; hence,
4 was mixed with phthalonitrile 5 in a 3:1 ratio
and the mixture was reacted with ruthenium(III)
trichloride, 4-methylpyridine, and DBU in refluxed
2-ethoxyethanol (Scheme 2). The reaction mixture
was separated by column chromatography to pro-
duce unsymmetrical TAP complex 6 with the 2,5-
diphenylselenophene unit and phthalocyanine com-
plex 7 in 1% and 10% yields, respectively. In the
reaction, two blue-green colored compounds were
obtained together with 6 and 7. These compounds
showed the molecular ion peak at 1212.1 (M+) by fast
atom bombardment mass spectrometry (FABMS)
and the Soret and Q band absorption in UV–vis
spectra (Fig. 2), suggesting that the two compounds
are adjacent and opposite TAP isomers with two se-
lenophene rings. However, we could not observe
clear spectra of these compounds by 1H NMR. In
addition, a TAP isomer with three selenophene rings
was not detected. When 4 and 5 were mixed in a 1:5
ratio, 6 was obtained in 3% yield. The structure of 6
FIGURE 2 UV–vis spectra (CHCl3); solid line: 6; dotted line:
7; dashed line and dashed and dotted line: the adjacent and
opposite TAP isomers with two selenophene rings.
TABLE 1 1H NMR Chemical Shifts of 4-Methylpyridine in the
Free and the Coordinated State
Chemical Shift δ (ppm)
Compound
Ha
Hb
Hc
3,4-TTTAP-Ph8
1.37
1.20
1.15
2.39
5.46
5.13
5.03
7.08
3.14
2.49
2.34
8.45
6
7
4-Methylpyridine
was determined by 1H NMR and FABMS. FABMS of
6 showed the molecular ion peak at m/z = 1006.1
[M+] when m-nitrobenzyl alcohol was used as a
matrix.
1
In the H NMR spectrum of 6, the protons of
the two phenyl groups and peripheral aromatic
rings were observed together with those of 4-methyl
pyridines as axial ligands, which showed 6 has
the unsymmetrical structure. The signals of 4-
methylpyridine were observed at δ = 1.20, 2.49,
and 5.13 ppm (Table 1). Since the signals of free
4-methylpyridine itself are observed at δ = 2.39,
7.08, and 8.45 ppm, the signals of 4-methylpyridine
of 6 are strongly shielded by the magnetic field
generated by the TAP ring. There is a report with
1
respect to identification of H NMR chemical shifts
of four-substituted pyridines in the phthalocyani-
nato ruthenium(II) complexes [15]. The signals of
4-methylpyridine of 6 were identified based on the
report. As reported in our previous paper, 7 and
3,4-TTTAP-Ph8 showed the signals of 4-
methylpyridine at δ = 1.15, 2.34, and 5.03 ppm
and δ = 1.37, 3.14, and 5.46 ppm, respectively. The
1H NMR chemical shifts of 4-methylpyridine of
Heteroatom Chemistry DOI 10.1002/hc

Preparation of 1,3-Diphenylselenophenotetraazaporphyrinato Ruthenium (II) 431
SCHEME 2 Preparation of TAP (6).
6 appear at a lower magnetic field than do those
of 7 and at a higher magnetic field than do those
of 3,4-TTTAP-Ph8. The 77Se NMR spectrum of 6
showed one singlet peak at δ = 759.5 ppm, which is
a lower magnetic field than those of 2a (δ = 575.2
ppm), 3 (δ = 683.2 ppm), 4 (δ = 675.7 ppm), and
2,3-TSTAP derivatives (δ = 555 and 558 ppm) [11].
In the UV–vis spectrum measured in chloroform,
the Q-band absorption of 6 was observed as a broad-
ened peak at 660 nm (log ε = 5.05) (Fig. 2). While
the absorption of 6 is a lower energy region than that
of 7 (626 nm), it is a higher energy area than those
of Heeneys’ 2,3-TSTAP (701 nm) and 3,4-TTTAP-Ph8
(758 nm). The Q band absorption of the adjacent and
opposite TAP isomers with two selenophene rings ap-
peared at a lower energy region than did those of 6
and 7. It is expected that the increase in the number
of the selenophene units can heighten the proba-
bility of the appearance of the unusual tetravalent
selenium atom, which perturbs the π-conjugation
system of the macrocycle and influences the Q band
absorption. To determine the electrochemical prop-
erty of 6, oxidation and reduction potentials were
measured by cyclic voltammetry using Ag/AgNO3 as
a reference electrode (solvent: CH2Cl2, scan rate: 200
mV s–1). In the voltammogram, two reversible oxi-
dation potentials (E1/2 = 0.25 and 0.92 V) and one
irreversible (Ep = –1.24 V) and one reversible re-
duction potentials (E1/2 = –1.64 V) were observed.
It appeared that the first oxidation potential of 6 is
slightly lower than that of 7 (E1/2 = 0.37 V), and the
first reduction potential of 6 is higher than that of 7
(–1.66 V).
CONCLUSIONS
The reaction of 3,4-dicyano-2,5-diphenylseleno-
phene (4) with phthalonitrile, ruthenium(III)
trichloride, and 4-methylpyridine produced TAP 6
1
with one selenophene ring. The H NMR chemical
shifts of 4-methylpyridine of 6, 7, and 3,4-TTTAP-
Ph8 suggest that the diatropic ring current of the
TAP ring is weaker in compound 6 than in phthalo-
cyanine 7 but stronger than in 3,4-TTTAP-Ph8. The
77Se NMR signal of 6 was observed at a lower mag-
netic field than those of 2a, 3, 4, and Heeneys’ 2,3-
TSTAP, which shows that the selenium atom in the
selenophene ring of 6 is strongly deshielded by the
Heteroatom Chemistry DOI 10.1002/hc

432 Kimura and Murakami
magnetic field generated by the TAP ring. The Q band
absorption of 6 is longer wavelength than that of 7
but shorter than those of the 2,3-TSTAP derivatives
and 3,4-TTTAP-Ph8.
2,5-Diphenyl-3,4-dicyanoselenophene (4)
Compound 3 (1.915 g, 4.0 mmol) and CuCN (1.788
g, 20 mmol) were placed in a glass reactor under Ar.
DMF (15 mL) was added and the solution was stirred
at 150°C for 18 h. After the reactor was cooled, aque-
ous FeCl3•6H2O (5.773 g, 21 mmol) solution (40 mL)
was added to the reaction mixture. The solution was
stirred at 80°C for 15 min. After cooling the reac-
tor, the reaction mixture was filtered and the residue
was dissolved with CHCl3. The CHCl3 solution was
dried over MgSO4, and the solvent was evaporated.
The product was purified by column chromatog-
raphy (Wakogel C-300HG, CHCl3) to produce 4 in
55% yield (805.1 mg): Colorless powder; 1H NMR
(500 MHz, CDCl3) δ 7.50–7.54 (m, 6H, Ar-H), 7.71–
7.76 (m, 4H, Ar-H); 13C NMR (126 MHz, CDCl3) δ
110.2, 114.1, 128.0, 129.6, 130.9, 131.8, 161.0; 77Se
NMR (95 MHz, CDCl3) δ 675.7; IR (KBr) 2224 cm–1
(CN); HR-MS Calcd for C18H10N280Se = 334.0009.
Found (m/z) = 334.0014 (M+).
EXPERIMENTAL
General
NMR spectra were measured with a Bruker Avance
500 III spectrometer. Mass spectra were obtained
using a JEOL JMS-700 mass spectrometer. UV–vis
spectra were recorded with a Jasco Ubest V-570 spec-
trophotometer. For IR measurement, a Jasco FT/IR-
4200 spectrometer was employed. A Hokuto Denko
Co. model HAB-151 apparatus was used to mea-
sure oxidation potentials. Bio-beads SX-1 for col-
umn chromatography was purchased from Nippon
Bio-Rad Laboratories.
Oxidation Potentials
2,5-Diphenylselenotetraazaporphyrinato
Ruthenium(II) bis(4-Methylpyridine) (6)
All measurements were performed by cyclic voltam-
metry, using Ag/0.01 M AgNO3 as a reference elec-
trode, a Pt wire as a counterelectrode, and glassy
carbon as a working electrode. A solution of 0.1 M
n-Bu4NClO4 in CH2Cl2 was used as an electrolyte. A
scan rate of 200 mV s–1 was used for the measure-
ment.
Compound 4 (337.5 mg, 1.0 mmol), phthaloni-
trile (641.1 mg, 5.0 mmol), and RuCl3•nH2O (396.4
mg, 1.5 mmol) were placed in a reactor, and 2-
ethoxyethanol (12 mL), DBU (1.8 mL), and 4-
methylpyridine (2.2 mL) were added under Ar. The
solution was stirred at 135°C for 48 h. After the re-
actor was cooled, aqueous MeOH was added and
the precipitate was filtered. The residue was dis-
solved in chloroform, and the solution was dried
over MgSO4. After the solvent was evaporated, the
product was separated by column chromatogra-
phy (alumina, CHCl3). The product was purified
by column chromatography (Wako-gel C-300HG, n-
hexane/CHCl3 and Bio-beads SX-1, CHCl3) to pro-
2,5-Diiodoselenophene (1) and
2,5-Diphenylselenophene (2)
2,5-Diiodoselenophene (1) and 2,5-Diphenylseleno-
phene (2) were prepared by the methods reported
previously [12].
1
2,5-Diphenyl-3,4-dibromoselenophene (3)
duce 6 in 3% (26.4 mg); 6; green crystals; H NMR
(500 MHz, CDCl3) δ 1.20 (s, 6H, –CH3), 2.32 (d, 4H,
J = 6.8 Hz, Py-H), 5.13 (d, 4H, J = 6.8 Hz, Py-H),
7.65 (t, 2H, J = 7.3 Hz, Ar-H), 7.80–7.84 (m, 8H, Ar-
H), 7.86–7.91 (m, 2H, Ar-H), 8.85 (d, 2H, Ar-H), 9.01
(d, 4H, J = 7.8 Hz, Ar-H), 9.13 (d, 4H, Ar-H); 77Se-
NMR (95 MHz, CDCl3) δ 759.5; FAB-MS (m/s) 1006.1
(M+).
To a solution of 2a (1.500 g, 5.3 mmol) in CH2Cl2 (40
mL), Br2 (0.6 mL, 11 mmol) was added from A sy-
ringe. The solution was stirred at room temperature
for 18 h. The aqueous Na2SO3 solution was added,
and the product was extracted with CH2Cl2. The ex-
tract was dried over MgSO4, and the solvent was
evaporated. The product was purified with column
chromatography (Wakogel C-300HG, n-hexane) to
1
give 3 in 97% yield (2.2441 g): Yellow crystals; H
REFERENCES
NMR (500 MHz, CDCl3) δ 7.40 (t, 1H, J = 7.5 Hz,
p-Ph), 7.45 (t, 2H, J = 7.5 Hz, m-Ph), 7.61 (d, 2H, J =
7.5 Hz, o-Ph); 13C NMR (126 MHz, CDCl3) δ 112.3,
128.4, 128.6, 129.1, 134.7, 142.9; 77Se NMR (95 MHz,
CDCl3) δ 683.2; HR-MS Calcd for C16H1079Br280Se =
439.8314. Found (m/z) = 439.8304 (M+).
[1] (a) Kadish, K. M.; Smith, K. M.; Guilard, R. (Eds.).
The Porphyrin Handbook, Vol. 16–20; Academic
Press: San Diego, CA, 2003; (b) Leznoff, C. C.;
Lever, A. B. P. (Eds.). Phthalocyanines: Properties
and Applications, Vol. 1–4; VCH: New York, 1989–
1996.
Heteroatom Chemistry DOI 10.1002/hc

Preparation of 1,3-Diphenylselenophenotetraazaporphyrinato Ruthenium (II) 433
[2] (a) Wo¨hrle, D.; Suvorova, O.; Gerdes, R.; Bartels, O.;
[10] (a) Cook, M. J.; Jafari-Fini, A. J Mater Chem 1997,
7, 5–7; (b) Cook, M. J.; Jafari-Fini, A. Tetrahedron
2000, 56, 4085–4094; (c) Nemykin, V. N.; Polshina, A.
E.; Kobayashi, N. Chem Lett 2000, 1236–1237.
[11] Shahid, M.; Padamsey, N.; Labram, J.; Antopoulos, T.
D.; Heeney, M. J Mater Chem C 2013, 1, 6198–6201.
[12] (a) Prediger, P.; Moro, A. V.; Nogueira, C. W.; Savwg-
nago, L.; Menezes, P. H.; Rocha, J. B. T.; Zeni, G. J
Org Chem 2006, 71, 3786–3792; (b) Barros, O. S. D.;
Favero, A.; Nogueira, C. W.; Menezes, P. H.; Zeni, G.
Tetrahedron Lett 2006, 47, 2179–2182; (c) Gai, B. M.;
Stein, A. L.; Roehrs, J. A.; Bilheri, F. N.; Nogueria, C.
W.; Zeni, G. Org Biomol Chem 2012, 10, 798–807.
[13] (a) Cava, M. P.; Husbands, G. E. M. J Am Chem Soc
1969, 91, 3952–3953; (b) Glick, M. D.; Cook, R. E. Acta
Crystallogr, Sect B 1972, 28, 1336–1339; (c) Yoneda,
S.; Ozaki, K.; Inoue, T.; Sugimoto, A. J Am Chem
Soc 1985, 107, 5801–5802; (d) Ishii, A.; Nakayama,
J.; Kazami, J.; Ida, Y.; Nakamura, T.; Hoshino, M. J
Org Chem 1991, 56, 78–82; (e) Amaresh, R. A.; Lak-
shmikantham, M. V.; Baldwin, J. W.; Cava, M. P.;
Metzger, R. M.; Rogers, R. D. J Org Chem 2002, 67,
2453–2458.
Lapok, L.; Baziakina, N.; Makarov, S.; Slodek, A. J
Porphyrins Phthalocyanines 2004, 8, 1020–1041; (b)
de la Torre, G.; Va´zquez, P.; Agullo´-Lo´pez, F.; Torres,
T. Chem Rev 2004, 104, 3723–75; (c) de la Torre,
G.; Claessens, C. G.; Torres, T. Chem Commun 2007,
2000–2015
[3] (a) Hains, A. W.; Liang, Z.; Woodhouse, M. A.; Gregg,
B. A. Chem Rev 2012, 110, 6689; (b) Mack, J.;
Kobayashi, N. Chem Rev 2011, 111, 281–321.
[4] Stuzhin, P. A.; Ercolani, C. In The Porphyrin Hand-
book; Kadish, K. M.; Smith, K. M.; Guilard, R. (Eds.);
Academic Press: San Diego, CA, 2003; Vol. 15, pp.
263–364.
[5] Donzello, M. P.; Ercolani, C.; Stuzhin, P. A. Coord
Chem Rev 2006, 250, 1530–1561.
[6] Kimura, T. Heterocycles 2013, 87, 245–274.
[7] (a) Knawby, D. M.; Swager, T. M.; J Mater Chem
1997, 9, 535–538; (b) Miyazaki, E.; Kaku, A. H.; Mori,
H.; Iwatani, M.; Takimiya, K. J Mater Chem 2009, 19,
5913–5915; (c) Bilton, J. A.; Linstead, R. P. J Chem
Soc 1937, 922–929.
[8] Kimura, T.; Iwama, T.; Namauo, T.; Suzuki, E.;
Fukuda, T.; Kobayashi, N.; Sasamori, T.; Tokitoh, N.
Eur J Inorg Chem 2011, 888–894.
[14] (a) Gronowitz, S.; Konar, S. J Chem Soc, Chem Com-
mun 1977, 163–164; (b) Gronowitz, S.; Konar, S.
Chem Scr 1977, 12, 11–14.
[15] Rawling, T.; McDonagh, A. Coord Chem Rev 2007,
251, 1128–1157.
[9] Vegh, D.; Landl, M.; Pavlovicova, R.; Kuzmany, H.;
Zalupsky, P. Khim Geterotsikl Soedin 1995, 1409–
1411.
Heteroatom Chemistry DOI 10.1002/hc