5,15-diaminotetrabenzoporphyrins: Synthesis and spectral properties

Article abstract of DOI:10.1134/S1070363212030206

A zinc complex of 5,15-di(N-phthalimidyl)tetrabenzoporphyrin was obtained by the reaction of Ncarboxymethylphthalimide with 1-oxo-1H-3-(1-oxoisoindolin-3- ylidenemethyl)isoindole and zinc oxide. The complex demetallation affords 5,15-di(N-phthalimidyl)tetrabenzoporphyrin. The reaction of N- phthalimidylsubstituted tetrabenzoporphyrins with hydrazine hydrate leads to the formation of 5,15-diaminotetrabenzoporphyrins. Spectral properties of these compounds were studied. Pleiades Publishing, Ltd., 2012.

Full text of DOI:10.1134/S1070363212030206

ISSN 1070-3632, Russian Journal of General Chemistry, 2012, Vol. 82, No. 3, pp. 482–487. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © L.A. Yakubov, N.E. Galanin, G.P. Shaposhnikov, 2012, published in Zhurnal Obshchei Khimii, 2012, Vol. 82, No. 3, pp. 489–494.
5,15-Diaminotetrabenzoporphyrins:
Synthesis and Spectral Properties
L. A. Yakubov, N. E. Galanin, and G. P. Shaposhnikov
Ivanovo State University of Chemical Technology, pr. F. Engelsa 7, Ivanovo, 153000 Russia
e-mail: yakubov_leonid@mail.ru
Received January 20, 2011
Abstract—A zinc complex of 5,15-di(N-phthalimidyl)tetrabenzoporphyrin was obtained by the reaction of N-
carboxymethylphthalimide with 1-oxo-1H-3-(1-oxoisoindolin-3-ylidenemethyl)isoindole and zinc oxide. The
complex demetallation affords 5,15-di(N-phthalimidyl)tetrabenzoporphyrin. The reaction of N-phthalimidyl-
substituted tetrabenzoporphyrins with hydrazine hydrate leads to the formation of 5,15-diaminotetra-
benzoporphyrins. Spectral properties of these compounds were studied.
DOI: 10.1134/S1070363212030206
The interest of scientists and technologists in tthe
unique group of porphyrin compounds, the meso-
substituted tetrabenzoporphyrins, increases every year,
probably due to the development of new, improved
methods for their synthesis [1–3] ensuring the availa-
bility of these compounds for research and practical
applications. The meso-substituted tetrabenzopor-
phyrins have been suggested as a material for the photo-
dynamic cancer therapy [4, 5] and as catalysts [6].
Among the methods of obtaining the meso-
substituted tetrabenzoporphyrins there is a template
condensation of phthalimide with substituted acetic
acid [8]. This one-step method is simple, but it has a
major drawback: the low stability of many of
substituted acetic acid derivatives at high temperatures.
Thus, our attempts to synthesize meso-amino-sub-
stituted tetrabenzoporphyrins by the reaction of
aminoacetic acid with phthalimide and zinc oxide were
unsuccessful. When heating a mixture of the reactants
to a temperature above 250°C tarring occurred,
probably due to the processes of oxidation involving
the primary amino groups.
Currently, meso-aryl- and meso-alkyl-substituted
tetrabenzoporphyrins are the most studied. An in-
formation of tetrabenzoporphyrins containing in their
meso-positions substituents of another nature, like
nitro or amino groups, is rather limited, although they
present no less theoretical and practical interest. This is
due to the lack of convenient methods for obtaining
such compounds. The known methods [7] of the
synthesis of meso-nitro- and meso-amino-substituted
tetrabenzoporphyrins, which consists in the synthesis
of zinc tetrabenzoporphyrinate, its nitration with nitric
acid in the medium of trifluoroacetic acid, and
reduction of the nitro derivatives with tin metal in
boiling acetic acid cannot be considered effective
because of the multistage nature of the process, the low
selectivity of the nitration and preparative complexity
of the reduction of the nitro group.
In this regard, we implemented a reaction of
phthalic anhydride with aminoacetic acid in DMF
solution at boiling and synthesized in high yield N-
carboxymethylphthalimide (I). Compound I is a light
yellow crystalline substance, soluble in water, readily
soluble in pyridine, DMSO and DMF, soluble in alkali
with decomposition. Its composition and structure
1
were confirmed by elemental analysis, IR and H
NMR spectroscopy.
O
N CH2COOH
In this paper, an attempt was made to develop a
more convenient method of the synthesis of meso-
amino-substituted tetrabenzoporphyrins.
O
I
482

5,15-DIAMINOTETRABENZOPORPHYRINS
483
In the IR spectrum of compound I there is a strong
band at 1718 cm–1, characterizing the stretching C=O
vibrations, the bands at 1419 and 1247 cm–1
correspond to the stretching vibrations of C=C bonds
in the aromatic fragments, the bands at 2933 and 1467
cm–1 characterize the vibrations of C–H bonds of the
methylene groups.
1
In the H NMR spectrum of a solution of acid I in
DMSO-d6 (Fig. 1) there are two quadruplets in a weak
field at 7.81–7.79 and 7.74–7.72 ppm corresponding to
the resonance of the four protons of the benzene ring in
3, 6, and 4, 5 positions, respectively. In a strong field
there is a singlet at 4.28 ppm, which characterizes the
resonance of the two protons of the methylene group.
The proton resonance of the carboxy group in the
spectrum is not seen, probably due to the processes of
deuterium exchange.
We have attempted to synthesise zinc 5,10,15,20-
tetra(N-phthalimidyl)tetrabenzoporphyrinate by heating
acid I with phthalimide in the presence of zinc oxide at
different ratios of reactants and temperatures. Ho-
wever, the attempts failed, probably due to steric
constraints to the formation of meso-tetra-substituted
tetrabenzoporphyrins. The process ends mainly at the
stage of the formation of 3,3'- [1-(1-oxo-1H-isoindol-3-
yl)-(N-phthalimidyl)idene]-2,3-dihydro-1H-isoindole-
1-one (II). This assumption is confirmed by the facts
that the reaction mixture is colored to dark-red, and in
its mass spectrum (electron impact ionization) there is
a signal at m/z 419, corresponding to a molecular ion
[M]+ of compound II and the peaks of the products of
its fragmentation, m/z 290, 274, and 160.
δ, ppm
Fig. 1. 1H NMR spectrum of compound I in DMSO-d6.
The interaction of compound III with acid I in the
presence of zinc oxide at 350°C over 50 min leads to
the formation of zinc 5,15-di(N-phthalimidyl)tetrabenzo-
porphyrinate (IV) in a 32% yield, from which we
obtained 5,15-di(N-phthalimidyl)tetrabenzoporphyrin (V)
by the demetallation with concentrated sulfuric acid.
The porphyrins IV and V were purified by column
chromatography on alumina using a chloroform–
pyridine mixture as an eluent. The resulting com-
pounds are dark green substances soluble in pyridine,
DMF, DMSO, and insoluble in water. Their composi-
tion and structure were confirmed by elemental
O
1
analysis, vibrational, electronic, and H NMR spec-
troscopy.
N
O
O
CH
NH
N
The IR spectrum of complex IV contains a band at
3065 cm–1 belonging to CH stretching vibrations of
aromatic fragments, the band at 1710 cm–1 charac-
terizing the C=O stretching vibrations, and the bands at
1457 and 1295 cm–1 corresponding to C=C stretching
vibrations in the aromatic fragments.
O
II
1
The effect of steric factors on the formation of
5,15-disubstituted tetrabenzoporphyrins is much
smaller [9]. Therefore, for the synthesis of compounds
of this structure, we used 3,3'-[1-(1-oxo-1H-isoindol-3-
yl)methyl]-2,3-dihydro-1H-isoindol-1-one (III) obtained
by the known procedure [10] through the condensation
of phthalimide with zinc acetate.
In the H NMR spectrum of compound IV in the
weakest fields there is a singlet at 10.51 ppm cor-
responding to the resonance of the two meso-proton.
The multiplets at 9.61–9.55, 8.11–8.05 and 7.95–
7.78 ppm correspond to the resonance of the sixteen
protons of the macrocycle benzene rings, and the
multiplets at 7.67–7.61 and 7.46–7.41 ppm characterize
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484
YAKUBOV et al.
O
O
N
N
CH2COOH
+
NH
O
III
O
I
O
O
N
N
O
O
N
H
N
Zn
N
H2SO4
ZnO
N
N
N
N
H
N
O
O
N
N
O
O
V
IV
the resonance of eight protons of the benzene rings of
meso-substituents.
nm in the visible region. The positions of these bands
are close to the respective position in the spectrum of
zinc tetrabenzoporphyrinate, indicating that there is no
noticeable distortion of the porphyrin macrocycle.
Apart from these, in the spectrum there are less intense
bands at 493 and 697 nm which do not occur in the
spectrum of zinc tetrabenzoporphyrinate, belonging to
n–π* transitions involving the nonbonding orbitals of
the nitrogen atoms of meso-substituents.
The 1H NMR spectrum of porphyrin V is similar by
the character and position of signals to the spectrum of
complex IV, and differs mainly by the presence of a
signal of two protons of the endocyclic imino groups at
–1.98 ppm.
The electron absorption spectrum of compound IV
(Fig. 2, curve 1) contains strong bands at 629 and 434
In the electron absorption spectrum of porphyrin V
(Fig. 2, curve 2) the absorption bands are also in the
same areas as in the spectrum of the tetrabenzo-
porphyrin, and the bands at 478 and 716 nm cor-
respond to n–π* transitions.
D
The synthesis of 5,15-diaminotetrabenzoporphyrins
(VI, VII) was carried out by reacting compounds IV or
V with hydrazine hydrate in pyridine medium at reflux
for 3 h.
Compounds VI and VII were purified by column
chromatography on silica gel C-60. In contrast to the
unsubstituted tetrabenzoporphyrin and its zinc
complex, and to porphyrins IV and V, they are readily
soluble in low polarity solvents, which allowed the use
of chloroform as an eluent. Porphyrins VI and VII are
λ, nm
Fig. 2. Electron absorption spectra (solvent DMF): (1) com-
pound IV, (2) compound V.
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5,15-DIAMINOTETRABENZOPORPHYRINS
485
O
N
O
N
M
N
N
N
N
N
NH2NH2 H2O
M
N
N
NH2
H2N
O
N
O
IV, V
VI, VII
M = Zn (IV, VI), 2H (V, VII).
crystalline compounds of dark green color, soluble in
acetone, chloroform, benzene, sparingly soluble in the
solutions of mineral acids, and insoluble in water.
Their composition and structure were confirmed by
shoulder on the long-wavelength Q-band at 642 nm
(Fig. 2, curve 1), in the spectrum of complex VI
(Fig. 3, curve 1) a resolved band appears at 643 nm of
the charge transfer from the electron-donor sub-
stituents on the macrocycle.
1
elemental analysis and vibrational, electronic and H
NMR spectroscopy.
EXPERIMENTAL
The IR spectra of complex VI and ligand VII
contain the characteristic bands at 3322–3320 and
1596–1590 cm–1 of the stretching and bending
vibrations of amino groups, respectively. The 1H NMR
spectrum of complex VI dissolved in CDCl3 contains a
singlet at 9.48 ppm in the weakest field, attributable to
the resonance of two protons at the 10 and 20 positions
of the macrocycle. Two singlets at 7.92 and 7.89 ppm
characterize the resonance of four protons of two
amino groups. Multiplets at 8.23, 7.54, and 7.49 ppm
correspond to the resonance of sixteen protons of the
benzene rings of the macrocycle. A significant
downfield shift of the proton signals of amino groups
is noteworthy. This is probably due to their strong
deshielding because of the influence of the aromatic
The electron absorption spectra of the compounds
obtained were measured on a Hitachi UV-2001
spectrophotometer. The H NMR spectra were taken
1
on a Bruker Avance-500 instrument (500 MHz),
solvents DMSO-d6 and CDCl3, internal reference
TMS. IR spectra were recorded on an Avatar 360 FT-
IR spectrophotometer in the region 400–4000 cm–1
from thin films on the TlI glass. Mass spectra were
recorded on a Varian Saturn 2000R GC-MS
spectrometer. The elemental analysis was performed
on a FlashEA 1112 CHNS-O Analyzer.
D
1
macrocycle. In the H NMR spectrum of the ligand
VII a broad singlet is present at –1.73 ppm, which
characterizes the resonance of two protons of the
endocyclic imino groups.
The electron absorption spectra of compounds VI
and VII (Fig. 3) are similar to the spectra of
porphyrins IV and V by the nature and position of the
bands, and also contain the bands in the regions of
477–492 and 695–717 nm due to n–π* transitions
involving the nonbonding orbitals of the nitrogen
atoms of amino groups. It is noteworthy, however, that
while the spectrum of porphyrin IV contains only a
λ, nm
Fig. 3. The electron absorption spectra (solvent CHCl3):
(1) compound VI, (2) compound VII.
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486
YAKUBOV et al.
N-Carboxymethylphthalimide (I). A solution of
in pyridine, DMF, DMSO, poorly soluble in acetone,
benzene, chloroform. IR spectrum, ν, cm–1: 3412 (N–H),
3063 (C–HAr), 1711 (C=O), 1458, 1296 (C=CAr), 1504,
1463 (C–N). The electron absorption spectrum (DMF),
23.0 g (0.16 mol) of phthalic anhydride and 12.7 g
(0.17 mol) of aminoacetic acid in 50 ml of DMF was
heated at reflux for 6 h, then poured into 100 ml of
water, the precipitate was filtered off, washed with 50
ml of water, and dried. Yield 6.30 g (96%). Pale
yellow powder, poorly soluble in water, soluble in
DMF, DMSO, and pyridine. IR spectrum, ν, cm–1:
2933, 1467 (C–H), 1718 (C=O), 1419, 1247 (C=C),
λ
max, nm (log ε): 392 (4.60), 421 (4.89), 435 (4.94),
478 (4.43), 516 (4.16) 567 (4.13), 612 (4.42 ) 665
(4.32) 712 (3.73). 1H NMR spectrum (DMSO-d6), δ, ppm:
10.54 s (2H), 9.63 s (4H), 8.12–8.07 m (8H), 7.97–
7.81 m (4H), 7.64–7.71 m (4H), 7.48–7.44 m (4H),
–1.98 s (2H). Found, %: C 78.36; H 3.74; N 10.22.
C52H28NO4. Calculated, %: C 77.99; H 3.52; N 10.49.
1
738, 713 (C–C). H NMR spectrum (DMSO-d6), δ,
ppm: 7.81–7.79 q (2H, Ar; J1,2 2.84 Hz, J1,3 5.36 Hz,
J1,4 8.20 Hz), 7.74 –7.72 q (2H, Ar; J1,2 3.16 Hz, J1,3
5.68 Hz, J1,4 8.51 Hz), 4.28 s (2H, CH2). Found, %: C
59.12; N 6.73, H 3.88. C10H7NO4. Calculated, %: C
58.54; N 6.83, H 3.44.
Zinc 5,15-Diaminotetrabenzoporphyrinate (VI)
and 5,15-diaminotetrabenzoporphyrin (VII). General
procedure. 0.58 mmol of a compound IV or V was
dissolved in 10 ml of pyridine, 2 ml of 70% hydrazine
hydrate was added, and the mixture was heated at
reflux for 3 h. Then the solvent was evaporated, the
residue was dissolved in chloroform and chromato-
graphed on silica gel C-60 (eluent chloroform), col-
lecting the main green area.
Zinc
5,15-Di(N-phthalimidyl)tetrabenzopor-
phyrinate (IV). A mixture of 3.0 g (0.011 mol) of
compound I, 2.7 g (0.013 mol) of compound III, and
0.6 g of zinc oxide was heated to 350°C and
maintained at this temperature for 50 min, then the
reaction mixture was cooled, ground, suspended in
500 ml of 20% solution of Na2CO3, and kept at 90°C
for 15 min. The precipitate was filtered off, washed
with 200 ml of water, dried, and treated with butyl
alcohol in a Soxhlet apparatus for 24 h. The residue
was dissolved in pyridine and chromatographed on a
column filled with aluminum oxide of II degree of
activity (eluent a mixture of chloroform–pyridine, 1:1
by volume), collecting the main green area. Yield 2.2 g
(32%), dark-green powder, soluble in pyridine, DMF,
DMSO, poorly soluble in acetone, benzene, chloro-
form. IR spectrum, ν, cm–1: 3065 (C–H), 1710 (C=O),
1457, 1295 (C=C), 1501, 1465 (C–N). The electron
absorption spectrum (DMF), λmax, nm (log ε): 410
(4.51), 434 (4.89), 459 (4.42), 493 (4.31) 583 (4.06),
Zinc meso-trans-diaminotetrabenzoporphyrinate
(VI). Yield 0.3 g (86%), dark green powder, soluble in
chloroform, acetone, toluene, pyridine, DMF, DMSO.
IR spectrum, ν, cm–1: 3320, 1590 (NH2), 3060, 2930,
2850 (C–H), 1550, 1451 (C=C), 1548, 1465 (C–N).
The electron absorption spectrum (CHCl3), λmax, nm
(log ε): 407 (4.50), 433 (4.87), 459 (4.41), 492 (4.30),
1
579 (4.05), 629 (4.54), 643 ( 4.45), 695 (3.84). H
NMR spectrum (CDCl3), δ, ppm: 9.48 s (2H), 8.23 m
(4H), 7.92 s (2H), 7.89 with (2H), 7.54 m (8H), 7.49 m
(4H ). Found, %: C 72.13; H 4.51; N 13.44.
C36H22N6Zn. Calculated, %: C 71.59; H 3.67; N 13.91.
meso-trans-Diaminotetrabenzoporphyrin (VII).
Yield 0.25 g (83%), dark-green powder, soluble in
chloroform, acetone, toluene, pyridine, DMF, DMSO.
IR spectrum, n, cm–1: 3322, 1596 (NH2), 3065 (C–H),
1459, 1293 (C = C), 1549, 1465 (C–N). The electron
absorption spectrum (CHCl 3), λmax, nm (log ε): 389
(4.59), 419 (4.88), 433 (4.87) 477 (4.41), 515 (4.16),
1
629 (4.55), 697 (3.84 ). H NMR spectrum (DMSO-
d6), δ, ppm: 10.51 s (2H), 9.61 s (4H), 8.11–8.05 m
(8H), 7.95–7.78 m (4H), 7.61–7.67 m (4H), 7.46–7.41
m (4H). Found, %: C 72.41; H 3.34; N 9.67.
C52H26NO4Zn. Calculated, %: C 72.27; H 3.03; N 9.72.
1
567 (4.12), 609 ( 4.42), 663 (4.31), 717 (3.71). H
5,15-Di(N-phthalimidyl)tetrabenzoporphyrin (V).
1.0 g (0.0011 mol) of the metal complex IV was
dissolved in 50 ml of sulfuric acid monohydrate and
kept for 2 h at 20°C, then poured into 100 ml of water.
The precipitate was filtered off and washed with
100 ml of 20% solution of ammonia, then 200 ml of
water, and dried. The residue was dissolved in pyridine
and chromatographed on alumina (eluent chloroform–
pyridine, 1:1 by volume), collecting the main green
area. Yield 0.79 g (85%), dark green powder, soluble
NMR spectrum (CDCl3), δ, ppm: 9.55 s (2H), 8.29 m
(4H), 7.91 s (2H), 7.78 with (2H), 7.55 m (8H), 7.51 m
(4H), –1.73 s (2H). Found, %: C 79.21; H 4.69; N 14.39.
C36H24N6. Calculated, %: C 79.98; H 4.47; N 15.54.
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