Synthesis of (2,3-diphenyl)pyrazinotribenzoporphyrazine

Article abstract of DOI:10.1134/S1070428012110115

By the method of template cyclotetramerization magnesium(II) (2,3-diphenyl)pyrazinotribenzoporphyrazinate was synthesized, and it was converted into (2,3-diphenyl)pyrazinotribenzoporphyrazine. (2,3-Diphenyl)- pyrazinotribenzoporphyrazine and (2-phenyl)imi

Full text of DOI:10.1134/S1070428012110115

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2012, Vol. 48, No. 11, pp. 1484−1489. © Pleiades Publishing, Ltd., 2012.
Original English Text © E.A. Kokareva, O.G. Khelevina, 2012, published in Zhurnal Organicheskoi Khimii, 2012, Vol. 48, No. 11, pp. 1500−1505.
Synthesis of (2,3-Diphenyl)pyrazinotribenzoporphyrazine
E. A. Kokareva and O. G. Khelevina
Ivanovo State University of Chemical Engineering, Research Institute of Chemistry of Macrocyclic Compounds,
Ivanovo,153000 Russia
e-mail: helevina@isuct.ru
Received April 13, 2012
Abstract—By the method of template cyclotetramerization magnesium(II) (2,3-diphenyl)pyrazinotribenzoporphyr-
azinate was synthesized, and it was converted into (2,3-diphenyl)pyrazinotribenzoporphyrazine. (2,3-Diphenyl)-
pyrazinotribenzoporphyrazine and (2-phenyl)imidazolotribenzoporphyrazine were synthesized from 5,7-diphenyl-
1,4-diazepinotribenzoporphyrazine by vacuum sublimation.
DOI: 10.1134/S1070428012110115
Porphyrazines with fused heterocycles (imidazolo-,
pyridino-, pyrazino-, pyridazino-, diazepinoporphyrazine)
are azaanalogs of well-understood phthalocyanine. The
existing publications make it possible to search among
compounds of this series for substances with valuable
applied properties [1–5]. Recently the unsymmetrical
porphyrazines attract much attention due to their optical
characteristics.
requires repeated chromatographic purifications. The ele-
mental analysis indicated that composition of the complex
contained two water molecules. Similar aqua complexes
magnesium forms with the other porphyrazines [8–10].
IR spectrum of the complex Bz3Ph2PyzPzMg contains
a set of bands corresponding to the stretching and bending
vibrations of functional groups present in its structure:
bands of the stretching vibrations of the C=N bonds in
the porphyrazine ring and the pyrazine fragments (1475
and 1441 cm–1 respectively), C–N bonds (3050 cm–1),
and C=C bonds in the phenyl fragments (1441 cm–1).
The band corresponding to the stretching vibrations of
CPh–CPz appears at lower wavenumber (1136 cm–1). The
character of the electron absorption spectrum (EAS) of
the complex shows that the compound is present in an
associated state. At the addition of a little pyridine the
associates are decomposed (Fig. 1). Bz3Ph2PyzPzMg is
prone to strong aggregation. Due to its association and
aggregation we failed to register its 1H NMR spectrum.
The target of this study was the synthesis of (2,3-di-
phenyl)pyrazinotribenzoporphyrazine Bz3Ph2PyzPzN2.
We first obtained a magnesium complex with (2,3-di-
phenyl)pyrazinotribenzoporphyrazine by template cy-
clotetramerization of phthalonitrile with 5,6-diphenyl-
2,3-dicyanopyrazine in the ratio 3 : 1 applying the
magnesium butylate. The magnesium complexes with
pyrazinoporphyrazine are known to be more soluble in
organic solvents than the ligands [6], therefore we pre-
pared by template cyclotetramerization the magnesium
complex of (2,3-diphenyl)pyrazinotribenzoporphyrazine,
which was isolated by column chromatography from the
mixture of magnesium complexes of di-, tri-, and tetra-
pyrazinoporphyrazines (Scheme 1).
The EAS of the complex in neat trifluoroacetic and
sulfuric acids are shown on Fig. 2, 3. In the 100% tri-
fluoroacetic acid Bz3Ph2PyzPzMg is present in a proton-
ated form as indicated by the red shift of the spectrum
characteristic of the porphyrazine complexes [11]. On the
dissolution of Bz3Ph2PyzPzMg in 100% sulfuric aci the
color of the solution changed from blue-green to light red,
and new absorption bands at 489 and 531 nm appear in
EAS. It is presumable that in sulfuric acid radical forms
of the complex are present.
Due to the low yield of Bz3Ph2PyzPzMg (5%) we de-
cided to prepare it through a phthalocyanine intermediate
(Scheme 2) along the procedure developed for obtaining
phthalocyanines of low symmetry [7].
Bz3Ph2PyzPzMg was isolated by column chroma-
tography on silica gel. The elution was carried out with
CHCl3 containing from 30 to 40% methanol. The isola-
tion of porphyrazine Bz3Ph2PyzPzMg in the pure state
The ligand Bz3Ph2PyzPzH2 was obtained by the
1484

SYNTHESIS OF (2,3-DIPHENYL)PYRAZINOTRIBENZOPORPHYRAZINE
1485
Scheme 1.
Ph
Ph
N
N
N
Ph
Ph
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
Mg
Mg
N
N
Mg
N
N
N
N
N
N
N
N
CN
CN
N
N
N
N
Ph
Ph
Ph
N
N
N
Ph
Ph
Ph
Mg(OC4H9)2
C4H9OH
trans-Bz2Pyz2PzMg
Bz3PyzPzMg
cis-Bz2Pyz2PzMg
+
Ph
N
Ph
Ph
CN
CN
N
N
N
N
Ph Ph
Ph
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
Mg
N
Mg
N
N
N
Mg
N
N
N
N
N
N
N
N
N
Ph
Ph
Ph
Ph
N
N
N
Ph
Ph
Ph
Ph
PcMg
BzPyz3PzMg
Py
z P
zM
g
4
demetalation of the complex Bz3Ph2PyzPzMg by treat-
ing it with trifluoroacetic acid at room temperature. The
ligand Bz3Ph2PyzPzH2 like its magnesium complex is
prone to association in solutions.
to phenylacetylene elimination and to the contraction of
the diazepine ring giving magnesium (2-phenyl)imid-
azolotribenzoporphyirazinate Bz3PhImHPzMg. Thus the
possibility to modify the diazepine ring was demonstrated
leading to obtaining new porphyrazines without the tem-
plate cyclotetramerization.
Recently [12] 5,7-diphenyl-1,4-diazepinotribenzo-
porphyrazine and its magnesium complex were synthe-
sized for the first time. The fragmentation of the molecular
ion of Bz3Ph2DzPzMg at the electron impact at 43 eV led
Therefore we carried out a vacuum sublimation
of 5,7-diphenyl-1,4-diazepinotribenzoporphyrazine1
300
400
500
600
700 λ, nm
400
500
600
700
800 λ, nm
Fig. 1. EAS of Bz3Ph2PyzPzMg in chloroform and in chloro-
Fig. 2. EAS of [Bz3(Ph)2PyzPzMg] in 100% trifluoroacetic acid.
form with added pyridine.
––––––––––––––
1
The sublimation of Bz3DzPzH2 was performed in the Institute of Solution Chemistry of the RussianAcademy of Sciences under the supervision
of Leading Researcher, Candidate of Chemical Science V.B. Sheinin.
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KOKAREVA, KHELEVINA
1486
Scheme 2.
N
N
N
N
N
CN
CN
LiOBu
BuOH
Mg(CH3COO)2
N
NLi
N
N
N
Mg
N
N
Ph
Ph
CN
CN
N
N
N
N
OBu
Bz3Ph2PyzPzMg
and found that in the course of the sublimation
(Bz3Ph2DzPzN2)·4H2O afforded a mixture of two com-
pounds: (2,3-diphenyl)pyrazinotribenzoporphyrazine and
(2-phenyl)imidazolotribenzoporphyrazine (Scheme 3). It
was confirmed by the data of mass spectrometry. EAS of
the mixture in chloroform solution is shown on Fig. 4.
Thus the vacuum sublimation can be used in the
synthesis of new porphyrazines. It is especially inter-
esting in the case of Bz3PhImHPzH2, which cannot be
obtained directly by the template cyclotetramerization
since 4,5-dicyanoimidazole is inert under the conditions
of this synthesis [13]. Using for initial products various
diazepine derivatives of porphyrazine it is possible to
synthesize imidazole derivatives of porphyrazine with
various substituents in the position 2 of the imidazole ring.
The mixture of two porphyrazines was separated
by column chromatography on silica gel with elution
by chloroform with variable content of methanol. The
identity of (2,3-diphenyl)pyrazinotribenzoporphyrazine
prepared by sublimation and by template cyclotetramer-
ization was proved by mass spectrometry and electron
absorption spectroscopy (Figs. 5, 6).
EXPERIMENTAL
Electron absorption spectra (EAS) were registered
Scheme 3.
N
N
N
N
N
N
NH
HN
N
N
CH2
N
N
N
N
N
N
C
CH2
C
Bz3Ph2PyzPzH2
NH
HN
N
N
PhCH2
N
N
HN
H
N
N
N
Bz3Ph2DzPzH2
NH
N
N
N
Bz3PhImHPzH2
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 11 2012

SYNTHESIS OF (2,3-DIPHENYL)PYRAZINOTRIBENZOPORPHYRAZINE
1487
Fig. 3. EAS of Bz3Ph2PyzPzMg in 100% H2SO4.
Fig. 5. EAS Bz3Ph2PyzPzH2 in mixed solvent CHCl3–CH3OH.
Fig. 4. EAS of the porphyrazines mixture in chloroform solu-
Fig.6. EAS of Bz3PhImHPzH2 in mixed solvent CHCl3–
tion.
CH3OH.
on spectrophotometers Hitachi U-2000, Agilent 8453,
Shimadzu UV-1800 from 10–6–10–5 M solutions of
porphyrazines and their complexes in the wave range of
300–800 nm using quartz cells. IR spectra were recorded
on Fourier spectrophotometers NIC 5DX, Avatar 360
FT-IR ESP (400–4000 cm–1), and Bruker Vertex 70
equipped withATR-device Bruker Platinum from samples
pelletized with KBr. MALDI-TOF mass spectra were
measured on a spectrometer Ultraflex (Bruker Daltonics)
using as matrix 3,5-dihydroxybenzoic acid, and without
lonitrile, ethanol, methanol from Aldrich, Acros
Organics, 4,5-dichloro-1,2-dicyanobenzene, 4-tert-
butylphthalonitrile from TCI Europe were used without
additional purification. Butanol was distilled on CaO
(bp 118°C).
Chloroform was refluxed on CaO and distilled at the
atmospheric pressure (bp 80–81°C).
2,3-Dicyano-5,6-diphenylpyrazine was prepared as
described in [14].
(2,3-Diphenyl)pyrazinotribenzoporphyrazinato-
it. Elemental analysis was carried out on instruments EA magnesium(II). To 50 ml of freshly distilled anhydrous
Euro 3000 (Kehatech) and Elementar Vario EL.
butanol was added 0.024 g (3.5 mg-atom) of lithium
metal, the obtained slurry of lithium butylate was cooled,
Diaminomaleodinitrile, dibenzoylmethane, phtha-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 11 2012

KOKAREVA, KHELEVINA
1488
zoporphyrazinate. In 60 ml of boiling freshly distilled
butanol was dissolved 1 g (41 mg-atom) of magnesium
metal. To the formed slurry of magnesium butylate was
added 2.21 g (7.5 mmol) of 2,3-dicyano-5,7-diphenyl-
6N-1,4-diazepine and 9.55 g (75 mmol) of phthalonitrile,
the mixture was stirred at the boiling point of butanol for
4h. In the course of the reaction the mixture turned from
light green to dark green. It was washed with methanol to
remove unreacted nitriles. The dry residue (10.3 g, yield
69% with respect to porphyrazines) was extracted with
dichloromethane, 7.2 g of insoluble magnesium phthalo-
cyanine was separated. The obtained mixture of of mag-
nesium pyrazinoporphyrazinates (2.6 g) was separated by
column chromatography on Al2O3 (II grade of activity),
eluent 5% methanol solution in dichloromethane. On
removal of the solvent the reaction product was dried in a
vacuum at 40°C. Yield of [Bz3Ph2DzPzMg]·H2O 630 mg
(34% with respect to 2,3-dicyano-5,7-diphenyl-6N-1,4-
0.89 g (7 mmol) of phthalonitrile was added thereto, the
reaction mixture was heated till it became light green, and
again it was cooled, 1.97 g (7 mmol) of 5,6-diphenyl-2,3-
dicyanopyrazine and 0.39 g (2.8 mmol) of magnesium
acetate was added. The mixture was heated for 6 h at the
boiling point of butanol. In the course of the reaction the
mixture turned from light green to dark green. On the
completion of the reaction butanol was distilled off, the
residue was dried at room temperature for 48 h. The dry
residue (yield 80% with respect to porphyrazines) was
extracted with chloroform in the Soxhlet extractor to
separate from insoluble magnesium phthalocyanine. The
obtained mixture of magnesium pyrazinoporphyrazinates
was separated by column chromatography on silica
gel, eluent 40% methanol solution in chloroform. On
removal of the solvent the reaction product was dried
in a vacuum at 60°C (yield 38% from the mixture Mg-
pyrazinoporphyrazinates). EAS (in pyridine), λ, nm
(log ε): 362 (4.94), 607 (4.48), 628 (4.52), 666 (5.07),
681(5.11). IR spectrum (KBr), ν, cm–1: 3050 w (–CH),
1660 w, 1606 w, 1537 w, 1475 m, 1441 w, 1346 m,
1331 m, 1288 w, 1248 w, 1188 w, 1155 m, 1136 m,
1113 m, 1078 m, 1059 m, 958 w, 947 w, 889 m, 843 w,
771 m, 754 m, 729 s, 698 s, 667 w, 638 m. Found,
%: C 68.74; H 3.64; N 18.70. C42H22N10Mg·2H2O.
Calculated, %: C 69.39; H 3.60; N 19.27.
diazepine). EAS (in pyridine), λ, nm (log ε): 357 (4.78),
657 (4.76), 696 (4.82). IR spectrum, ν, cm–1: 690 w, 729 s,
754 s, 889 w, 1055 s, 1084 s, 1117 s, 1184 w, 1280 s,
1332 s, 1444 m, 1485 s, 1525 m, 1610 m, 1631 m, 1059 m.
1H NMR spectrum (DMSO-d6, 363 K), δ, ppm: 4.42 br
(2H, CH2), 7.60–7.70 (6H, m,p-Ph), 8.20–8.30 (6H,
β-Bz), 8.54 d (4H, o-Ph, J 7 Hz), 9.30–9.40 (2H, α-Bz),
9.40–9.50 (4H). Mass spectrum (MS FD), m/z (ESI) (Iotn.
,
(2,3-Diphenyl)pyrazinotribenzoporphyrazine.
The magnesium complex was dissolved in a little
trifluoroacetic acid in the dark. The solution obtained was
poured in cold distilled water. The separated precipitate
was filtered off, washed with water till neutral wash-
ings, and with methanol. Yield 70%. EAS (in pyridine),
λ, nm (log ε): 348 (4.21), 613 (3.86), 670 (4.31), 683
(4.37). Found, %: C 74.79; H 3.60; N 20.21. C42H22N10.
Calculated, %: C 75.44; H 3.62; N 20.95.
%): 705 (100) [M + H]+, 722 (45) [M + H2O]+, 740 (10)
[M + 2H2O]+. Calculated, %: C 69.69; H 3.81; N 18.90.
C43H24MgN10·H2O. Found, %: C 69.71; H 4.08; N 18.19.
5,7-Diphenyl-1,4-diazepinotribenzoporphyrazine.
[Bz3Ph2DzPzN2]·4H2O was obtained and identified along
procedure [12]. The magnesium complex was dissolved
in a little trifluoroacetic acid in the dark. The solution
obtained was poured in cold distilled water. The separated
precipitate was filtered off, washed with water till neutral
washings, and subjected to column chromatography on
Al2O3 (II grade of activity), eluent 5% methanol solution
in dichloromethane. On removal of the solvent the reac-
tion product was dried in a vacuum at 40°C. Yield 60%.
EAS (pyridine), λ, nm (log ε): 349 (4.56), 629 (4.33), 678
(4.33), 711 (4.41); (CHCl3): 346 (4.52), 625 (4.23), 676
(4.31), 716 (4.31). IR spectrum, ν, cm–1: 617 m, 655 w,
690 m, 734 s, 873 s, 1001 s, 1093 w, 1118 s, 1182 m,
1317 m, 1444 s, 1494 m, 1537 m, 1610 w, 1064 m, 3298 w
2,3-Dicyano-5,7-diphenyl-6N-1,4-diazepine [15]. A
mixture of 5 g (0.028 mol) of diaminomaleodinitrile, 12.5
g (0.056 mol) of dibenzoylmethane, and 2 g of P2O5 in
160 ml of ethanol was stirred fo 1 h at room temperature.
To the mixture more 3 g of P2O5 was added, and it was
refluxed at the boiling point of ethanol while continuous
stirring for 2 h. The reaction mixture obtained was con-
centrated and cooled. The separated yellow-brown crys-
tals were filtered off, dried, and recrystallized from ace-
tonitrile. Yield 8 g (96%), yellow crystals, mp 249–251°C
[15]. IR spectrum, ν, cm–1: 3080, 2250, 1607, 1540, 1460,
1330, 1262, 1200. Found, %: C 76.89; H 3.87; N 18.75.
C19H12N4. Calculated, %: C 77.01; H 4.08; N 18.91.
1
(NH). N NMR spectrum (THF-d8, 330 K), δ, ppm:
–1.33 br (2H, NH-Pz), 4.61 br (2H, CH2), 7.50–7.60
(6H, m,p-Ph); 8.03 (4H, β-Bz), 8.23 (2H), 8.79 d (4H,
o-Ph, J 6.7 Hz); 9.11 (2H, α-Bz), 9.16 (2H), 9.32 (2H).
Magnesium(II) 5,7-Diphenyl-1,4-diazepinotriben
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 11 2012

SYNTHESIS OF (2,3-DIPHENYL)PYRAZINOTRIBENZOPORPHYRAZINE
1489
Mass spectrum (MS FD), m/z (MALDI-TOF) (Irel, %):
REFERENCES
683 (100) [M + H]+, 705 (27) [M + Na]+. Found, %:
C 68.53; H 4.30; N 18.67. C43H24N10·4H2O. Calculated,
%: C 68.43; H 4.54; N 18.55.
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2004, p. 136.
Sublimation of 5,7-diphenyl-1,4-diazepinotribenzo-
porphyrazine. The ligand was dissolved in chloroform,
and the solution was placed in a trap containing glass
rings. Chloroform was evaporated. The test tube with
the trap was placed in the oven equipped with tempera-
ture control, and the device was connected to a vacuum
line. The sublimation was performed twice. At 180°C
over 2 h the synthesis proceeded with the formation of
(2,3-diphenyl)pyrazinotribenzoporphyrazine, (2-phenyl)
imidazolotribenzoporphyrazne and side tarry products.
To remove the latter the sublimation was repeated for the
second time at 350°C over 6 h. The mixture separated
into zones. The MALDI-spectrum of the sample after
sublimation demonstrated the presence of two com-
pounds: (2,3-diphenyl)-pyrazinotribenzoporphyrazine
and (2-phenyl)imidazolotri-benzoporphyrazine.
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Bz3Ph2PyzPzH2. EAS (pyridine), λ, nm (log ε): 348
(4.21), 613 (3.86), 670 (4.31), 683 (4.37). Mass spectrum
(MS FD), m/z (MALDI-TOF) (Irel, %) 668 (100) [M –
H]–. Found, %: C 74.83; H 3.71; N 20.56. C42H22N10.
Calculated, %: C 75.44; H 3.62; N 20.95.
Bz3PhImHPzH2. Mass spectrum (MS FD), m/z
(MALDI-TOF) (Irel, %): 580 (100) [M – H]–. Found, %:
C 71.78; H 3.40; N 23.96. C35H20N10. Calculated, %:
C 72.40; H 3.47; N 24.12.
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ACKNOWLEDGMENTS
The study was performed under the financial support
of a grant of the President of the Russian Federation
MK-4171.2012.3.
15. Donzello, M.P., Ercolani, C., and Stuzhin, P.A., Eur. J.
Inorg. Chem., 1999, p. 2075.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 11 2012