Unsymmetrical azaporphyrins. Synthesis, structure, and properties

Article abstract of DOI:10.1007/s11176-005-0101-9

Given are data on the synthesis and spectral and other physicochemical properties of unsymmetrically substituted azaporphyrins containing peripheral fused benzene and sulfur- or nitrogen-containing rings or phenyl substituents. 2004 MAIK "Nauka/Interperiodica".

Full text of DOI:10.1007/s11176-005-0101-9

Russian Journal of General Chemistry, Vol. 74, No. 11, 2004, pp. 1801 1817. Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004,
pp. 1912 1928.
Original Russian Text Copyright
2004 by Maizlish, Kulinich, Shaposhnikov.
Unsymmetrical Azaporphyrins.
Synthesis, Structure, and Properties
V. E. Maizlish, V. P. Kulinich, and G. P. Shaposhnikov
Ivanovo State University of Chemical Engineering, Ivanovo, Russia
Received November 12, 2002
Abstract Given are data on the synthesis and spectral and other physicochemical properties of unsym-
metrically substituted azaporphyrins containing peripheral fused benzene and sulfur- or nitrogen-containing
rings or phenyl substituents.
In the recent time, much attention is given to un-
symmetrically substituted phthalocyanines (Pc) and
azaporphyrins (porphyrazines, Pa) which contain both
different functional groups and various kinds of fused
aromatic or heterocyclic moieties. These compounds
have found application in nonlinear optics, photo-
dynamic diagnostics and therapy of cancer and are
promising materials for Langmuir Blodgett films
(LB), stacked (highly ordered) polymers, and liquid
crystals [1 7]. However, the synthesis and isolation
of such compounds still remain a difficult problem.
Up now, several methods for the preparation of un-
symmetrical azaporphyrins have been repoted. The
simplest and most widely used procedure is based on
reactions involving two different orthodicarboxylic
acids or their derivatives [8 12]. For example, reac-
tions of metal salts with dinitriles having different
fragments A and B could give rise to six metalphtha-
locyanine complexes (MPc).
CN
CN
A
B
+
CN
CN
A
A
A
A
B
B
N
N
N
M
N
N
N
N
N
N
N
N
N
N
N
MX
N
N
N
N
N
N
M
N
M
N
N
N
A
A
B
A
A
B
B
A
B
AAAB
N
AABB
AAAA
B
A
A
N
N
N
N
N
N
N
N
N
N
N
M
N
B
N
M
N
N
M
N
N
N
N
N
N
N
N
B
A
B
B
B
ABAB
BBBA
BBBB
1070-3632/04/7411-1801 2004 MAIK Nauka/Interperiodica

1802
MAIZLISH et al.
According to McKeown et al. [4], the ratio of iso-
cyanines of ABAB type [19]. These procedures are
examples of purposeful synthesis where the macroring
is formed via cross coupling of the initial reactants.
meric structures formed by the above condensation
can be controlled. The authors performed statistical
analysis of the ratio of isomers formed via different
combinations of phthalodinitriles A and B provided
that participation of each reagent is equally probable.
They calculated the ratios of isomeric MPcs, depend-
ing on the reactant ratio, and proved their conclusions
experimentally.
The synthesis of unsymmetrical metal-free azapor-
phyrins can be effected by reacting boron subphthalo-
cyanine with substituted 1,3-diiminoisoindoles [20
24]. Until recently, this method was believed to be
ideal for preparation of unsymmetrical macrohetero-
cycles with a 3:1 ratio of two different isoindole
moieties. On the other hand, Sastre et al. [20] showed
that opening of the subphthalocyanine core could
give rise to very small amounts of other products.
In the reaction of CuCl2 with 4-nitrophthalic acid
and phthalic anhydride in nitrobenzene in the presence
of urea and ammonium molybdate as catalyst, the
only isolated product was identified as mononitro-
phthalocyanine [12]. This is explained in terms of a
lower reactivity of one of the components, which
eventually determines the ratio of the macrocyclic
products. Thus, in some cases, the number of un-
symmetrical products is lesser than that theoretically
possible. Later on, the possibility for synthesizing un-
symmetrical phthalocyanines with a desired structure
was demonstrated. Reactions of unsubstituted phthalo-
dinitrile with its analogs containing bulky substituents
in the ortho positions with respect to the cyano groups
lead to formation of a nonstatistical mixture of un-
symmetrical complexes AB3 and A2B2 together with
unsubstituted phthalocyanine [13 17]. For example,
the condensation of tetraphenylphthalodinitrile with
other dinitriles gives no hexadecaphenylphthalocya-
nine [13 15]. The inability of tetraphenyl-substituted
phthalodinitrile to undergo self-condensation was
confirmed by molecular modeling [2]; however,
Subbotin et al. [16] reported on the synthesis of hexa-
decaphenylphthalocyanine.
We can conclude that there exist three main syn-
thetic approaches to unsymmetrical azaporphyrins:
cross coupling [18, 19], subphthalocyanine path
[20 24], and statistical condensation, the latter
necessarily including separation of isomer mixtures
[5, 6, 8 12]. The present article contains our data on
the synthesis and some properties of unsymmetrical
azaporphyrins. Phthalocyanines of type ABAB and
their structural analogs were synthesized according to
the cross coupling approach [19]. We obtained a series
of phthalocyanines containing different kinds of
substituents [25 29], as well as azaporphyrins contain-
ing peripheral fused benzene rings and heterocyclic
residues [30 35].
UNSYMMETRICALLY SUBSTITUTED
ABAB PHTHALOCYANINES
Taking into account that 5(6)-nitro-1,3,3-trichloro-
isoindole [19] was the only known representative of
substituted 1,3,3-trichloroisoindoles, we developed
procedures for the preparation of some new substi-
tuted derivatives III [36, 37]. It is known that the re-
action of phthalimide with phosphorus pentachloride
in o-dichlorobenzene gives 3-chloroisoindol-1-one
which is then transformed into 1,3,3-trichloroisoindole
[38].
Less common methods for the synthesis of unsym-
metrical phthalocyanines have also been reported. One
of these involves reaction of substituted dithioxoiso-
indole and aminoiminoisoindole [18]. In our opinion,
a more perfect procedure is based on the reaction of
1,3,3-trichloroisoindoles with different aminoimino-
isoindoles, which leads to unsymmetrical phthalo-
O
Cl
Cl
PCl5
PCl5
R
NH
N
N
R
R
Cl
Cl
O
O
I
II
III
R = Cl, Br, NO2, t-Bu.
Using 4-chloro-, 4-bromo-, and 4-tert-butylphthal-
imides I as initial compounds, we synthesized the
corresponding substituted trichloroisoindoles III which
were isolated by fractional distillation under reduced
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

UNSYMMETRICAL AZAPORPHYRINS
1803
pressure (10 12 mm). Compounds III are light yellow
thick viscous substances which are soluble in tetra-
hydrofuran and acetone; the products crystallized on
storage. Unsymmetrical phthalocyanines V and VI
(ABAB) were obtained according to the following
scheme.
R
R
N
N
N
N
N
H
N
H
N
N
NH2
R
R
Et3N, CH3ONa,
hydroquinone
V
H2Pc(R)2(R )2
2III + 2R
N
R
R
NH
IV
N
N
N
N
N
MCl1
2
N
M
N
N
R
R
VI
MPc(R)2(R )2
R = Cl, R = H, t-Bu; R = Br, R = H, t-Bu; R = NO2, R = H, Cl, t-Bu; R = t-Bu, R = H; M = Cu, Co.
The reactions were carried out in anhydrous ace-
tone in the presence of triethylamine, sodium meth-
oxide, and hydroquinone under argon. In the synthesis
of the corresponding metal complexes, copper(I) or
cobalt(II) chloride was also added. Presumably, in the
first stage, dimeric or more complex condensation
products are formed; and the subsequent cyclization
gives substituted dehydrophthalocyanine. Hydrogen
chloride liberated during the process is trapped by
triethylamine, and triethylamine hydrochloride is
removed by filtration. Substituted dehydrophthalo-
cyanines are reduced with hydroquinone in the pres-
ence of sodium methoxide on heating to afford the
corresponding phthalocyanines V or (in the presence
of a metal salt) metal complexes VI. We preliminarily
showed that no phthalocyanine is formed when only
one reagent, III or IV, is taken. It is known [38] that
dehydrophthalocyanine cannot be isolated in the pure
state, for it always contains H2Pc as an impurity. We
also noted that in the first stage the corresponding
substituted H2Pc separated together with triethylamine
hydrochloride. All compounds V and VI thus ob-
tained were purified by washing in succession with
water, dilute hydrochloric acid until colorless
washings, water until chloride ions disappeared from
the filtrate, and acetone and ethanol until colorless
washings. tert-Butyl-substituted phthalocyanines were
additionally extracted with benzene, the extract was
evaporated, and the residue was subjected to chroma-
tography on aluminum oxide.
The products were identified by elemental analysis
and electronic and IR spectroscopy. Their IR spectra
contained bands typical of phthalocyanines [39], as
well as additional absorption bands due to substituents
(NO2, Cl, Br, or t-Bu). All the products were dark
blue powders which were almost insoluble (except
for the tert-butyl derivatives) in organic solvents
(except for -chloronaphthalene) and soluble in con-
centrated sulfuric acid. The presence of halogen in Pc
molecule reduces the solubility, especially in the case
of halodinitro-substituted compounds. Dihalophthalo-
cyanines can be sublimed under reduced pressure (6
5
10 mm) at 400 450 C. Introduction of two tert-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

1804
MAIZLISH et al.
Table 1. Positions of long-wave bands in the electronic
absorption spectra of disubstituted phthalocyanines
trum of H2Pc(4-Cl)2 in -chloronaphthalene, the long-
wave absorption bands are located more closely than
in the spectrum of H2Pc: the distances between the
corresponding maxima are 19 and 33 nm, respectively.
The nature of the halogen atom is not significant. A
similar pattern is typical of dihalodi(tert-butyl)-
substituted phthalocyanines in organic solvents and in
concentrated sulfuric acid. In the first case, the absorp-
tion curves are almost identical to those observed for
dihalo derivatives in -chloronaphthalene, while a
little red shift of the absorption maxima results from
variation of the solvent. The presence of tert-butyl
groups becomes more appreciable in the spectra
recorded from solutions in sulfuric acid.
(
max, nm)
-Chloro-
naphthalene
Phthalocyanine
Benzene H2SO4
H2Pc(4-Cl)2
H2Pc(4-Br)2
CuPc(4-Cl)2
CuPc(4-Br)2
CoPc(4-Cl)2
CoPc(4-Br)2
693, 674
842, 790
836, 784
796
681
681
672
673
799
788
H2Pc(4-Cl)2(4-t-Bu)2
H2Pc(4-Br)2(4-t-Bu)2
CuPc(4-Cl)2(4-t-Bu)2
CuPc(4-Br)2(4-t-Bu)2
CuPc(3-Cl)2(4-t-Bu)2
CoPc(4-Cl)2(4-t-Bu)2
CoPc(4-Br)2(4-t-Bu)2
H2Pc(4-NO2)2
689, 670 839, 804
689, 670 839, 801
The visible region of the electronic absorption spec-
trum of H2Pc(4-NO2)2 contains two bands with equal
intensities; the distance between their maxima is
21 nm, i.e., it is almost the same as in the spectra of
known dinitro-substituted phthalocyanines [19]. The
corresponding distance for tetra-4-nitrophthalocyanine
is 36 nm, and for unsubstituted H2Pc, 33 nm. It
should be noted that the long-wave component is dis-
placed by 16 nm toward shorter wavelengths, as com-
pared to tetranitrophthalocyanine, and by 6 nm toward
longer wavelengths, as compared to H2Pc. The elec-
tronic absorption spectra of H2Pc(4-NO2)2R2 in or-
ganic solvents (Fig. 1, Table 1) are also characterized
by the presence of two absorption bands, and the
distance between their maxima is even shorter than in
the spectrum of H2Pc(4-NO2)2; in some cases, these
bands merge together. The distance between the long-
wave maxima strongly depends on the nature and
position of the R substituent. In the spectra of dinitro-
dihalophthalocyanines, the two bands either merge
into one broadened [H2Pc(4-NO2)2(4-Cl)2] or are split
only slightly [H2Pc(4-NO2)2(3-Cl)2], presumably due
to aggregation in solution. In the spectrum of dinitro-
di-tert-butylphthalocyanine, the distance between the
longwave absorption bands is 10 nm, which is also
typical of other dinitro-substituted H2Pc soluble in
organic solvents [19].
677
679
683
668
667
812
807
822
799
704, 683
723, 673
714, 668
691
791, 755
810, 758
812, 760
791, 760
809, 772
776, 746
804, 760
CuPc(4-NO2)2
CoPc(4-NO2)2
H2Pc(4-NO2)2(4-Cl)2
H2Pc(4-NO2)2(3-Cl)2
CuPc(4-NO2)2(4-Cl)2
CuPc(4-NO2)2(3-Cl)2
702, 693
708, 685
714, 681
H2Pc(4-NO2)2(4-t-Bu)2 701, 689 691, 681
CuPc(4-NO2)2(4-t-Bu)2 716, 676 701, 670
butyl groups reduces the sublimation point to 340
400 C. Also, tert-butyl-substituted compounds
acquire solubility in organic solvents, such as benzene,
acetone, DMF, and DMSO.
The stability of dihalophthalocyanine copper com-
plexes to thermooxidative decomposition in air strong-
ly depends on the nature of the halogen and other
substituents. Vigorous exothermic processes accom-
panied by maximal weight loss were observed at 435
470 and 550 630 C for CuPc(4-Br)2 and CuPc(4-Cl)2,
respectively. Introduction of tert-butyl groups reduces
the thermal stability of the resulting complexes, and
the maximal weight loss occurs at 440 C for CuPc(4-
Cl)2(4-t-Bu)2 and at 402 C for CuPc(4-Br)2(4-t-Bu)2.
As with the free ligands, the presence of two chlo-
rine atoms in phthalocyanine metal complexes almost
does not affect the position of the Q-band (Table 1);
a similar pattern was observed previously for other
dihalo-substituted phthalocyanines [40]. Introduction
of two tert-butyl groups leads to a small blue shift of
the Q-band due to solvation effects.
Introduction of two chlorine atoms into positions 4
of the benzene rings in H2Pc also affects the shape
and position of absorption bands in the electronic
spectra recorded from solutions in organic solvents
and concentrated sulfuric acid (Table 1). In the spec-
The Q-band in the spectrum of MPc(4-NO2)2 is
split into two components, which is generally untyp-
ical of MPc. On the other hand, an analogous split-
ting was observed for other nitro-substituted phthalo-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

UNSYMMETRICAL AZAPORPHYRINS
cyanine metal complexes [19, 40 42]. In these cases,
1805
the components were characterized by approximately
equal intensities, and the distance between their
maxima ranged from 10 nm for MPc(4-NO2)4 to
45 nm for dinitro analogs. The distances between the
maxima for our complexes are 50 nm (copper com-
plex) and 46 nm (cobalt complex) (Table 1), and the
intensities of the components are different (especially
for the cobalt complex). Also, a considerable red shift
(a)
(b)
D
D
(
= 22 23 nm) of the long-wave absorption band
relative to the corresponding band in the spectra of
tetra-4-nitrophthalocyanine complexes was observed.
As might be expected, the spectral pattern almost does
not change in going from organic solvents to con-
centrated sulfuric acid; a red shift of the absorption
bands results from protonation at the meso-nitrogen
atoms [43].
1
1
2
3
2
3
Introduction of halogen atoms into position 4 of
the benzene rings does not affect the spectral pattern.
The spectra of dinitro-substituted phthalocyanines, as
well as of other nitro-substituted phthalocyanines, are
characterized by considerably smaller red shift of the
absorption bands, as compared to those containing no
nitro groups. This is explained by reduced basicity of
the meso-nitrogen atoms and hence degree of proto-
nation. The electronic absorption spectra of dinitrodi-
halophthalocyanines in sulfuric acid differ from the
spectra in -chloronaphthalene (Fig. 2, Table 1). The
two long-wave absorption bands are clearly resolved,
500
600 700 800 500
, nm
600 700 800
Fig. 1. Electronic absorption spectra in (1, 2) -chloro-
naphthalene and (3) benzene of (a) H Pc(4-NO ) R
2
2 2 2
and (b) CuPc(4-NO ) R : (1) R = 4-Cl, (2) R = 3-Cl,
2 2
2
(3) R = 4-t-Bu.
and the distance between their maxima ranges from
31 to 37 nm. Chlorine atoms in position 3 of the
benzene rings affect the position of absorption bands
(a)
(b)
D
D
2
1
1
2
500
600
700 800
500
, nm
600
700 800
Fig. 2. Electronic absorption spectra in concentrated sulfuric acid of (a) H Pc(4-NO ) R and (b) CuPc(4-NO ) R : (1) R =
2
2 2
2
2 2 2
4-Cl, (2) R = 3-Cl.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

1806
MAIZLISH et al.
to a greater extent than do chlorine atoms in position
4. In the spectrum of H2Pc(4-NO2)2(3-Cl)2, the long-
wave doublet is displaced to longer wavelengths rel-
ative to the corresponding doublet in the spectrum of
H2Pc(4-NO2)2(4-Cl)2. A similar pattern was ob-
served previously for other chloro-substituted phtha-
locyanines [40].
heterocycles attract interest from the viewpoint of
studying the effect of functional and hetero substitu-
tion on their physical and chemical properties. Un-
symmetrical fused azaporphyrins were synthesized
and purified by the procedure described above for
unsymmetrical phthalocyanines with the difference
that appropriate hetero analogs were used as starting
compounds instead of 1-amino-3-iminoisoindole;
these were 1-amino-3-imino-4,7-dithia-4,5,6,7-tetra-
hydroisoindole (VII), 1-amino-3-imino-4(7)-azaiso-
indole (VIII), and 1-amino-3-imino-4,7-diazaiso-
indole (IX). We thus synthesized unsymmetrical
sulfur-containing azaporphyrins of type ABAB and
made an attempt to obtain sulfur-containing com-
pounds XII with an ABAC structure, i.e., azapor-
phyrins having two fused 1,4-dithiacyclohexene rings
and two benzene rings with different substituents [31].
The desired products were prepared by successive re-
actions of compound VII with differently substituted
1,3,3-trichloroisoindoles III.
In the electronic spectra of metal complexes de-
rived from all dinitro-substituted phthalocyanines, the
Q-band is also split into two components (see above).
The magnitude of splitting depends on the nature and
position of the other substituents. Possible reasons are
distortion of the molecular symmetry as a result of
unsymmetrical substitution and the presence of
randomers.
UNSYMMETRICAL AZAPORPHYRINS HAVING
FUSED SUBSTITUTED BENZENE AND SULFUR-
OR NITROGEN-CONTAINING RINGS
Azaporphyrin derivatives in which the pyrrole rings
are fused to substituted benzene rings or various
R1
R1
N
N
N
N
N
N
A
A
A
HN
A
NH
N
N
M
N
N
N
N
N
N
R2
R2
X
XI
S
S
A
=
: H2Pa(DT)2(RAr)2 (X); MPa(DT)2(RAr)2 (M = Cu, Co) (XI); R1 = R2 = Cl, Br, NO2, t-Bu; R1 = t-Bu,
N
R2 = Cl, Br, NO2; R1 = Cl, R2 = NO2;
: H2Pa(Py)2(RAr)2 (X); MPa(Py)2(RAr)2 (M = Cu, Co) (XI);
A
=
N
R1 = R2 = Cl, NO2, t-Bu.
A
=
: H2Pa(Pz)2(RAr)2 (X); MPa(Pz)2(RAr)2 (M = Cu, Co) (XI);
N
R1 = R2 = Cl, NO2, t-Bu.
In the first stage, initial compounds VII and III
(R = t-Bu or Cl) at a molar ratio of 2:1 were mixed
with a required amount of triethylamine (to bind
liberated hydrogen chloride) in acetone on cooling
under argon, and the mixture was kept at room tem-
perature. The precipitate of triethylamine hydrochlo-
ride was separated, and stoichiometric amounts of the
other compound III (R = Cl, Br, NO2) and triethyl-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

UNSYMMETRICAL AZAPORPHYRINS
1807
amine were added to the resulting solution of inter-
mediate compound XII at 0 C. The subsequent pro-
cedure was the same as in the synthesis and isolation
of ABAB products.
R1
Cl
Cl
R1
N
N
N
Cl
NH2
N
N
B
III
S
S
S
S
S
S
2
N
N
NH
NH H2N
A
VII
XII
R1
Cl
Cl
N
R2
; M2+
Cl
N
N
N
C
III
N
M
N
S
S
S
S
N
N
N
R2
XIII
MPa(DT)2(R1Ar)(R2Ar) (XIII); R1 = t-Bu; R2 = Cl, Br, NO2; R1 = Cl; R2 = NO2; M = 2H, Cu, Co.
Intermediate compound XII (R1 = t-Bu) was iso-
groups considerably weakens intermolecular interac-
tions, thus favoring vaporization.
lated as a brown powder. Its IR spectrum contained
1
absorption bands in the region 3400 3550 cm cor-
responding to stretching vibrations of the terminal NH
and imino groups. Such bands were lacking in the
cyclization products XIII. On the other hand, the ab-
In order to elucidate the effect of heteroatom in the
heterocyclic moieties on the properties of macrocyclic
compounds, we synthesized azaporphyrins having
fused pyridine [MPa(Py)2(RAr)2)] and pyrazine rings
[MPa(Pz)2(RAr)2)]. The conditions for their synthesis
were different. Like bis(dithiacyclohexeno) derivatives
and unsymmetrical phthalocyanines, dipyridinodi-
(R-benzo)azaporphyrins were formed in low-boiling
solvents (tetrahydrofuran, acetone), while the forma-
tion of dipyrazinodi(R-benzo) analogs required heat-
ing in relatively high-boiling dimethylformamide. The
yields of pyridino and pyrazino derivatives were quite
low (0.7 to 6.1%). The products were isolated as dark
blue (almost black) powders which, as well as bis(1,4-
dithiacyclohexeno)azaprophyrins, were poorly soluble
(except for the tert-butyl-substituted compounds) in
organic solvents and soluble in concentrated sulfuric
acid. The sulfuric acid concentration at which the
1
sorption at 2840 2975 cm due to symmetric and
antisymmetric C H stretching vibrations of the tert-
butyl substituents and methylene groups in the 1,4-di-
thiacyclohexene rings was retained. Compound XII
displayed in the electronic absorption spectrum a
diffuse band in the region 300 330 nm (DMF). Aza-
porphyrins XIII are dark violet powder-like sub-
stances, which are soluble in -chloronaphthalene and
concentrated sulfuric acid; tert-butyl-substituted de-
rivatives are soluble in benzene and some other
weakly polar solvents. Unlike H2Pa(DT)4, H2(DT)2Pa
(t-BuAr)2 can be sublimed in a high vacuum (6
5
10 mm) at 350 360 C. Presumably, replacement of
two 1,4-dithiacyclohexene rings in the azaporphyrin
molecule by benzene rings containing bulky tert-butyl
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

1808
MAIZLISH et al.
1
1100 cm we observed absorption bands typical of
C S C moieties in 1,4-dithiacyclohexene rings.
Halogen atoms in the benzene rings give rise to
characteristic C Cl and C Br stretching vibration
D
1
bands at 830 and 690 cm , respectively. The IR
spectra of the nitro-substituted compounds contained
1
absorption bands at 1500 and 1340 1350 cm , which
3
belong, respectively, to antisymmetric and symmetric
stretching vibrations of the nitro groups. The bands at
1
2840 2975 cm (see above) originate from sym-
2
metric and antisymmetric stretching vibrations of C H
bonds in the tert-butyl groups and methylene groups
in the 1,4-dithiacyclohexene rings. The IR spectra of
MPa(Py)2(RAr)2 and MPa(Pz)2(RAr)2 contained
broadened absorption bands, some of which are ty-
pical of CuPc [39], CuPa(Py)4 [44], and CuPa(Pz)4
[45]. In addition, absorption bands belonging to the
substituents were present, , cm : 820 830 (C Cl);
1340 1350, 1550 1560 (NO2); 2850, 2930, 2980
(CH2, CH3).
1
400
500
600 700 800
, nm
1
Fig. 3. Electronic absorption spectra of (1) H (DT)
2
2
2
(BrAr) Pa in
-chloronaphthalene, (2) H (DT)
2
2
(BrAr) Pa in H SO , and (3) H (DT) Pa in -chloro-
2
2
4
2
4
naphthalene.
The temperatures corresponding to the start of de-
composition in air of the tert-butyl-substituted com-
plex CuPa(DT)2(t-BuAr)2 and structurally related
tetra-4-tert-butylphthalocyanine [CuPc(4-t-Bu)4] and
tetra(1,4-dithiacyclohexeno)tetraazaporphyrin copper
complexes [Cu(DT)4Pa] differ insignificantly: they
range from 280 to 310 C (Table 2). Stronger dif-
ferences were observed in the shape of the DTA
curves in the temperature range from 300 to 500 C.
The temperature corresponding to the maximal exo-
thermic effect in the decomposition of CuPa(DT)2
(t-BuAr)2 is higher than those found for the other
complexes. Pyridine-fused copper complexes are more
stable against thermooxidative degradation than the
respective sulfur-containing azaporphyrins. The di-
chloro derivative is more stable than both CuPa(Py)4
and CuPc but less stable than CuPc(4-Cl)2. It was
somewhat surprising that the complex CuPa(Py)2
(t-BuAr)2 turned out to be more stable in air than
CuPc(4-t-Bu)4, although unsubstituted CuPc is
superior to CuPa(Py)4 in this respect.
compounds begin to separate from solution is con-
siderably lower than that found for phthalocyanines.
The products were identified on the basis of their
elemental compositions, thermogravimetric data, and
vibrational and electronic spectra. The IR spectra of
MPa(DT)2(RAr)2 and MPa(DT)2(R1Ar)(R2Ar) were
poorly resolved owing to enhanced intermolecular
interaction involving sulfur atoms in the peripheral
1,4-dithiacyclohexene rings. Nevertheless, some
characteristic bands appeared more distinctly than in
the spectra of tetra(1,4-dithiacyclohexeno)azapor-
phyrins. For example, in the IR region 1000
Table 2. Parameters of thermooxidative decomposition of
phthalocyanine and azaporphyrin copper complexes
Temperature,
C
Comp.
no.
Complex
start of
maximal
maximal exothermic
The electronic absorption spectra of solutions of
metal-free sulfur-containing azaporphyrins in -chlo-
ronaphthalene resemble that of tetra(1,4-dithiacyclo-
hexeno)azaporphyrin (Fig. 3, Table 3). The long-wave
absorption band is displaced by 7 24 nm to the red
region, as compared to the corresponding absorption
band of H2Pa(DT)4. The second long-wave absorp-
tion band in the spectra of the halo and tert-butyl
weight loss
effect
CuPc
445
460
310
425
280
290
450
435
390
458
550
CuPc(4-Cl)2
CuPc(4-t-Bu)4
Cu(Py)4Pa
Cu(DT)4Pa
Cu(DT)2(t-BuAr)2Pa XLIIe
Cu(Py)2(ClAr)2Pa
Cu(Py)2(NO2Ar)2Pa XLVIIIb
Cu(Py)2(t-BuAr)2Pa XLVIIIc
328, 451 w
442
290 w, 412
362 w, 470
526
derivatives is located at
617 627 nm, while the
XLVIIIa
corresponding band in the spectrum of the nitro-
substituted compound appears at longer wavelengths
452
409
(
656 nm), i.e., the distance between the two long-
wave maxima in the spectrum of the latter is shorter
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

UNSYMMETRICAL AZAPORPHYRINS
1809
Table 3. Positions of bands in the electronic absorption
spectra of di(1,4-dithiacyclohexeno)di(R-benzo)azapor-
phyrins and complexes derived therefrom [M(DT)2
(RAr)2Pa]
Table 4. Positions of bands in the electronic absorption
spectra of di(1,4-dithiacyclohexeno)(R1-benzo)(R2-benzo)-
azaporphyrins and complexes derived therefrom
[M(DT)2(R1Ar)(R2Ar)Pa]
[M(DT)2(RAr)2Pa
, nm
M(DT)2(R1Ar)(R2Ar)Pa
, nm
benzene
Comp.
no.
M
R
-chloronaphthalene
H2SO4
679
M
R1
R2
Cl
Br
H2SO4
696
2H
2H
Cl
Br
722, 690 sh, 654 sh, 627,
565 w, 524
722, 691 sh, 654 sh, 627,
565 w, 534
XLIVa 2H
XLIVb 2H
t-Bu
t-Bu
726, 668 w,
612
727, 687 w,
667 w, 611,
553
681
687
2H
2H
NO2 716, 656, 595 w, 545 w
t-Bu 729, 693 w, 668 w, 611,
554 w, 351a
681
691
XLIVc
2H
t-Bu
NO2 720, 680 w,
612, 520
685
Cu
Cu
Cu
Cu
Co
Co
Co
Co
Cl
Br
690 sh, 660, 595 w, 541 w
690 sh, 661, 615 w, 540 w
737
735
716
730
733
733
727
732
XLIVd 2H
Cl
t-Bu
t-Bu
NO2
Cl
Br
678
729
731
XLVa
XLVb
Cu
Cu
698, 634
699, 635,
580 w,
NO2 683, 610 sh, 550
w
t-Bu 700, 632, 580 w, 352a
Cl
Br
720 sh, 655, 528
719 sh, 658, 540
w
w
525 w
XLVc
XLVd
Cu
Cu
t-Bu
Cl
t-Bu
t-Bu
NO2 692, 660
NO2
Br
733
720
731
727
NO2 672, 530 w
t-Bu 670, 620, 530 w, 333a
XLVIa Co
XLVIb Co
680 sh, 635
NO2 650 br
a
In benzene.
than in the spectra of the other substituted azapor-
phyrins or H2Pa(DT)4. A tendency to closer arrange-
ment of the long-wave absorption bands was observed
previously for unsymmetrical nitro-substituted
phthalocyanines.
The intensity ratio of the first long-wave absorption
band and the Soret band in the spectrum of CuPa(DT)2
(t-BuAr)2 is equal to 1.1, while the corresponding
ratio for CuPc(4-t-Bu)4 is 3.1. Comparison of the elec-
tronic absorption spectra of H2Pa(DT)2(t-BuAr)(R2Ar)
and H2Pa(DT)2(t-BuAr)2 shows that replacement of
one tert-butyl group by halogen atom or nitro group is
not accompanied by appreciable variations in the
spectral pattern. The above-noted tendency to closer
arrangement of the long-wave absorption bands is also
inherent in H2Pa(DT)2(t-BuAr)(NO2Ar).
The electronic absorption spectra of the halo- and
nitro-substituted azaporphyrin metal complexes in
-
chloronaphthalene contain only one strong band in the
long-wave region. This band is slightly broadened, as
compared to the spectra of the corresponding phthalo-
cyanines. We believe that the reason is association
involving peripheral sulfur atoms and polar functional
substituents in the benzene rings. The position of the
long-wave band is determined by the nature of sub-
stituents and central metal ion. The tert-butyl-substi-
tuted complexes in benzene give rise to two long-
wave absorption bands (Table 3, 4), presumably due
to reduced molecular symmetry. Like the spectra of
H2Pa(DT)4 and metal complexes derived therefrom, in
Metal complexes MPa(DT)2(R1Ar)(R2Ar) also
display two long-wave maxima in the electronic
absorption spectra (Table 4); as above, this may be
due to reduction in the molecular symmetry. The
positions of these bands and their relative intensities
depend on the substituent. Compounds posses-
sing both a chlorine atom and a nitro group are almost
insoluble in organic solvents; therefore, their elec-
tronic absorption spectra were obtained only from
solutions in concentrated sulfuric acid. The spectra
contained one broadened absorption band at 678
737 nm (Tables 3, 4). This pattern results from
aggregation and protonation of both meso-nitrogen
atoms and sulfur atoms in the 1,4-dithiacyclohexene
rings. In going from organic solvents to sulfuric acid,
the red shift of the Q-band in the spectra of the metal
the region 500 560 nm we observed weak absorption
*
bands originating from n
transitions which
involve n-electrons on the sulfur atoms in the 1,4-di-
thiacyclohexene rings; the relative intensity of these
bands is lower. The relative intensity of the Soret
band in the electronic absorption spectra of tert-butyl-
substituted sulfur-containing azaporphyrins in benzene
is considerably higher, as compared to MPc(4-t-Bu)4.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

1810
MAIZLISH et al.
Table 5. Positions of bands in the electronic absorption
spectra of di(pyridino)- and di(pyrazino)(R-benzo)aza-
porphyrins and complexes derived therefrom [M(X)2
(RAr)2Pa]
H2Pa(Pz)2(ClAr)2 in DMF contains a band at
650 nm, while the nitro-substituted analog displays a
broad band in the region 600 700 nm; the spectrum
of unsubstituted H2Pa(Pz)4 in the same solvent is
characterized by an absorption band at
639 nm.
M(X)2(RAr)2Pa
, nm
Likewise, H2Pa(Pz)2(ClAr)2 in concentrated sulfuric
acid shows two strong absorption bands at 766 and
652 nm, the corresponding bands in the spectrum of
H2Pa(Pz)2(NO2Ar)2 are located at 722 and 672 nm,
whereas tetrapyrazinotetraazaporphyrin gives a strong
band at 654 nm with an inflection at 600 nm [45].
Comp.
no.
DMF
X
M
R
H2SO4
(benzene)
XLVIIa
Py
2H
Cl
640
743, 692,
680
In the electronic absorption spectra of dipyidino-
azaporphyrin metal complexes in DMF we observed
a strong narrow Q-band which was slightly displaced
XLVIIb
XLVIIc
Py
Py
2H
2H
NO2
t-Bu
646
655, 645
(670, 657)
652
710, 672
(
12 nm) to longer wavelengths (except for the
XLVIIIa
XLVIIIb
XLVIIIc
Py
Py
Py
Cu
Cu
Cu
Cl
760, 692,
637
tert-butyl derivative) relative to the Q-band of the free
ligand (Table 5). The position of this band almost
does not depend on the substituent in the benzene ring
NO2
650
720, 687,
660, 635
(
650 652 nm). The spectra of the complexes in
comncaxentrated sulfuric acid, as well as those of the free
ligands, contain a greater number of absorption bands
in the region 600 750 nm, their number and posi-
tion depending on the substituent.
t-Bu 650 (655) 697, 663,
636
766, 652
600 700 722, 672
IIa
IIb
La
Lb
Pz
Pz
Pz
Pz
2H
2H
Cu
Cu
Cl
NO2
Cl
650
632
654
696, 654
735, 675,
653
NO2
The electronic absorption spectra of dipyrazinoaza-
porphyrin metal complexes in DMF are characterized
Lc
Pz
Cu
t-Bu
647
704, 660
by a Ared shift of the Q-band (up to
23 nm), as com-
pared to CuPa(Pz)4. In going to concentrated sulfuric
acid, variations in the spectral pattern are similar to
those observed for pyridine-fused azaporphyrins. The
spectrum of CuPa(Pz)4 contains one strong absorption
band at 648 nm [45], while CuPa(Pz)2(RAr)2 (R =
Cl, t-Bu) show in the spectra two strong absorption
bands at 696 704 and 645 660 nm, and the nitro
analog gives rise to three strong absorption bands at
735, 675, and 653 nm (Table 5). As with unsymmet-
rical sulfur-containing azaporphyrins, replacement of
two heterocyclic fragments in symmetric azapor-
phyrins Pa(Py)4 and Pa(Pz)4 by substituted benzene
rings is accompanied by a red shift of the first long-
wave absorption band, especially in the spectra re-
corded from concentrated sulfuric acid solution. In
addition, the spectral patterns become more complex
due to appearance of new long-wave absorption bands,
presumably as a result of reduction of the molecular
symmetry.
complexes is greater than that observed for MPa(DT)4.
This means that the degree of protonation at the meso-
nitrogen atoms is higher than for MPa(DT)4 but lower
than for Pc. As with tetra(1,4-dithiacyclohexeno)aza-
porphyrins and ABAC compounds, no absorption was
observed in the region 500 560 nm; this absorption
appears in the spectra recorded from solutions in
*
organic solvents and corresponds to n
transitions
involving sulfur atoms of the 1,4-dithiacyclohexene
rings.
The electronic absorption spectra of metal-free Cl-
and NO2-substituted dipyridinoazaporphyrins in DMF
contain one broad band centered at 640 645 nm, i.e.,
in same region as that typical of H2(Py)4Pa (
643 nm) [46]. In the spectrum of H2Pa(Py)2(t-BuAr)2,
two strong absorption bands were present both in
DMF ( 645 and 655 nm) and in benzene (657 and
670 nm) (Table 5). In going to concentrated sulfuric
acid, the spectra of the chlorine- and nitro group-
containing azaporphyrins become more complex due
to appearance of additional absorption bands which
are displaced red, as compared to H2Pa(Py)4.
UNSYMMETRICAL PHENYL-SUBSTITUTED
AZAPORPHYRINS
It is known [47] that the presence of phenyl groups
in molecules of unsymmetrical azaporphyrins makes
them soluble in a wide series of organic solvents.
Therefore, such compounds can be purified by highly
efficient methods which allow isolation of pure iso-
The spectral parameters of metal-free dipyrazino
derivatives considerably differ from those found for
H2Pa(Pz)4. The electronic absorption spectrum of
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

UNSYMMETRICAL AZAPORPHYRINS
1811
mers. We developed a procedure for the synthesis of
unsymmetrical azaporphyrins [48] with the use of
5-amino-2-imino-3,4-diphenyl-2H-pyrrole (XIV) and
substituted 3-amino-1,1-dichloro-1H-isoindole hydro-
chlorides XV as starting compounds; these com-
pounds were not used previously for that purpose.
Compounds XIV and XV are sufficiently reactive to
effect their condensation and the subsequent complex
formation under mild temperature conditions. Pyrrole
XIV was synthesized by reaction of diphenylmaleo-
dinitrile with ammonia in methanol in the presence of
sodium methoxide [49].
gen chloride through a solution of phthalodinitrile in
anhydrous chloroform [50]. Hydrochlorides XVb
XVd were synthesized under similar conditions from
the corresponding substituted phthalodinitriles (R = Cl,
Br, Ph) [51, 52]. Their structure was confirmed by
elemental analysis and IR spectroscopy. The presence
in the IR spectra of a broad absorption band in the
1
region 2900 3100 cm is typical of stretching vibra-
tions of N H bonds in RNH2 HCl-like salts; free
amino groups usually give rise to absorption at higher
frequencies. The presence of halogen atoms in the
benzene rings is confirmed by characteristic absorp-
1
tion bands at 800 850 (C Cl) and 600 680 cm
Prior to our studies, compound XIVa (R = H) have
been reported. It was obtained by passing dry hydro-
(C Br) [53].
R
NH2 HCl
N
NH2
N +
Cl
Cl
N
N
Ph
Ph
Ph
Ph
R
N
NH2 HCl
XVa XVd
NH
NH
XIV
XVIa XVId
R
R
Et3N
N
NH
N
NH2
N
N
Ph
Ph
Ph
Ph
N
N
NH2
NH
XVIIa XVIId
R
R
N
XVIIa XVIId,
hydroquinone
N
N
N
N
N
N
N
Ph
Ph
Ph
Ph
MeOH, MCl1
2
N
-------
M
N
-------
M
N
and/or
N
R
R
N
N
N
N
Ph Ph
R
XVIIIA
XVIIIB
MPa(RAr)(Ph)4; R = H (a), Cl (b), Br (c), Ph (d); M = 2H, Cu, Co.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

1812
MAIZLISH et al.
Compounds XIV and XVa XVd reacted in acetone
The products were thoroughly purified using extrac-
tion methods and column chromatography.
at room temperature according to the above scheme to
afford compounds XVIa XVId having terminal =NH
and NH2 HCl groups. Treatment of the latter with tri-
ethylamine gave free bases XVIIa XVIId which were
subjected to cyclization by heating in boiling acetone
in the presence of hydroquinone and sodium meth-
oxide. The corresponding metal complexes were ob-
tained when the cyclization was performed in the
presence of copper(II) or cobalt(II) chloride [51, 52].
It is known that ammonium compounds like
XVIa XVId can exist as two tautomers A and B [54].
Therefore, their cyclization could give rise to isomeric
products XVIIIA and XVIIIB differing in mutual
arrangement of the isoindole and diphenylpyrrole
fragments.
N
N
N
N
N
N
N
N
N
N
*
*
*
*
*
*
*
*
----M------
----M------
N
N
N
N
N
N
*
*
A
B
MPa(Ar)2Ph4; M = 2H, Cu.
Initially, by the extraction and column chromatog-
raphy we isolated one fraction containing deeply
colored products [51]. Using ascending thin-layer
chromatography (TLC) and varying the eluent com-
position we succeeded in separating each fraction into
two spectrally distinguishable components [52, 55].
In the synthesis of dibenzotetraphenyltetraazapor-
phyrin and its copper complex, we obtained in each
case two fractions: less mobile with Rf 0.19 and 0.23
1and more mobile with Rf 0.49 and 0.52 (Silufol UV-
254, benzene heptane, 9:1; Table 6). Compounds
isolated from these fractions had the same elemental
composition and molecular weight (determined from
the mass-spectral data). The mass spectra (FAB) of
the complexes contained peaks corresponding to the
molecular ions, m/z 781 [M + H]+ and 780 [M+]. In
addition, the presence of ion peaks with m/z 704, 627,
550, and 473 indicated fragmentation of the molecular
ion via successive elimination of phenyl groups.
Table 6. Yields, Rf values, and electronic absorption
spectra in benzene of azaporphyrins MPa(RAr)2(Ph)4 iso-
lated by TLC
Yield,
%
Electronic absorption
spectrum, max, nm
Compound
Rf
H2Pa(Ar)2(Ph)4 (A)
H2Pa(Ar)2(Ph)4 (B)
15 0.49 672, 629, 581 sh, 358
12 0.19 698, 639 w, 605,
575 sh, 560 sh, 349
The elecronic absorption spectra of metal-free di-
benzotetraphenyltetraazaporphyrin isomers, as well as
the spectra of symmetric tetraazaporphyrin derivatives
(phthalocyanine and octaphenyltetraazaporphyrin),
contained two strong long-wave bands. The isomer
with Rf 0.19 showed a more complex spectrum, as
compared to that with Rf 0.49; in particular, the spec-
trum of the former contained a greater number of
vibrational satellites and was characterized by a longer
distance between the main absorption maxima. Taking
these data into account, we presumed that the first
CuPa(Ar)2(Ph)4 (A)
CuPa(Ar)2(Ph)4 (B)
H2Pa(PhAr)2(Ph)4 (A)
13 0.52 647, 588 sh, 358
11 0.23 682, 640, 578 sh, 351
6
0.24 710, 679, 621, 590 sh,
351
H2Pa(PhAr)2(Ph)4 (B)
CuPa(PhAr)2(Ph)4 (A)
CuPa(PhAr)2(Ph)4 (B)
5
8
8
0.52 681, 637, 591, 361
0.26 654, 595, 358
0.53 700 sh, 657, 624,
570 sh, 362
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

UNSYMMETRICAL AZAPORPHYRINS
1813
D
1.0
D
1.4
2
2
0.8
0.6
1.2
1
1.0
0.8
1
0.4
0.6
0.4
0.2
0
0.2
0
350
400
500
600 700
, nm
350
400
500
600 700
, nm
Fig. 4. Electronic absorption spectra in benzene of
(1) H Pa(Ar) (Ph) (isomer A) and (2) CuPa(Ar) (Ph)
Fig. 5. Electronic absorption spectra in benzene of
(1) H Pa(Ar) (Ph) (isomer B) and (2) CuPa(Ar) (Ph)
2
2
4
2
4
2
2
4
2
4
(isomer A).
(isomer B).
isomer has a less symmetric structure (cis-structure
B) and that the second has trans-structure A
(Figs. 4, 5). A distinct difference in the electronic
absorption spectra was also observed for the isomeric
copper complexes. The spectrum of the conceivably
more symmetric isomer A (Rf 0.52) contained one
strong band in the long-wave region ( 647 nm),
consists of three groups of signals. The downfield
signal at 7.6 ppm corresponds to resonance of eight
protons in the isoindole fragments, and multiplet
signals at 7.0 and 6.8 ppm belong to 20 protons in
the phenyl rings. The intensity ratio of these signals is
0.45, i.e., it is fairly close to the theoretical value. The
signal at 6.8 ppm was assigned to four ortho-pro-
whose position is intermediate between the correspond- tons in the phenyl rings (marked with an asterisk in
ing maxima in the spectra of phthalocyanine [40] and
octaphenyltetraazaporphyrin copper complexes [47]
(Fig. 4). The shapes of the Soret bands in the spectra
of isomers A and B are similar, and their positions
differ by 7 9 nm.
the above scheme). This signal is displaced slightly
upfield relative to the other aromatic proton signals
due to steric hindrances. In the spectrum of isomer B
of CuPa(Ar)2(Ph)4, we observed analogous groups of
signals at 7.4 (isoindole) and 7.13 and 7.02 ppm
(phenyl rings).
In order to establish correspondence between the
structures of metal-free H2Pa(Ar)2(Ph)4 and its copper
complex, the latter was synthesized from the free
ligand and copper(II) salt in boiling DMF. In this way,
from trans isomer A we obtained the corresponding
complex A, and from cis isomer B, complex B. These
complexes were identical in their spectral parameters
and Rf values to those synthesized by the above
scheme and separated by TLC.
Thus, the results of spectral studies indicate that the
synthesis of unsymmetrical phenyl-substituted aza-
porphyrins according to the scheme developed in [48]
gives isomeric products differing by mutual arrange-
ment of the isoindole and diphenylpyrrole fragments.
The reaction followed the same pattern when halo-
gen-substituted hydrochlorides XVb and XVc were
used in the synthesis of unsymmetrical tetraazapor-
phyrins. However, it was quite difficult to separate
the products by chromatography. Table 7 contains the
positions of absorption maxima in the spectra re-
corded from solutions of isomer mixtures in benzene.
Dibenzotetraphenyltetraazaporphyrin displayed in the
long-wave region of the electronic absorption spec-
trum a greater number of bands, as compared to octa-
phenyltetraazaporphyrin and phthalocyanine [40, 47].
The absorption patterns obtained for the halogen-
substituted and unsubstituted compounds were fairly
similar: only a slight red shift of some absorption
bands was observed.
The IR spectra of the products contained absorption
bands typical of vibrations of the azaporphyrin macro-
ring [47], while no bands assignable to bending vibra-
tions of the pyrrole C H bonds were present in the
1
region 800 900 cm . These data indicate complete
replacement of the pyrrole hydrogen atoms by phenyl
groups and fused benzene rings. The IR spectra of the
isomeric compounds are generally similar, but some
differences were observed in the position of absorp-
tion bands and their intensity.
The 1H NMR spectrum of CuPa(Ar)2(Ph)4 (A)
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

1814
MAIZLISH et al.
Table 7. Yields and electronic absorption spectra of aza-
porphyrins MPa(HlgAr)2(Ph)4
are generally similar to those observed for isomeric
dibenzotetraphenyltetraazaporphyrins [55]. It should
be noted that the spectrum containing only one long-
Electronic absorption
wave band at
654 nm belongs to the less mobile
max
spectrum, max, nm
copper complex, in contrast to the more mobile trans
isomer of dibenzotetraphenyltetraazaporphyrin copper
complex. The red shift of the long-wave maxima in
going from that complex to MPa(PhAr)2(Ph)4 results
from increase in the number of phenyl rings from 4
to 6 per molecule. In keeping with the general trends,
the spectra of the free ligands H2Pa(PhAr)2(Ph)4 (A
and B) consist of a greater of absorption bands than
the spectra of the corresponding copper complexes
due to higher molecular symmetry of the latter.
Yield,
%
Compound
18 M
H2SO4
benzene
H2Pa(ClAr)2(Ph)4
H2Pa(BrAr)2(Ph)4
15 696, 675, 630,
615, 581, 357
15 696, 675, 630,
615, 583, 357
CuPa(ClAr)2(Ph)4
CuPa(BrAr)2(Ph)4
CoPa(ClAr)2(Ph)4
CoPa(BrAr)2(Ph)4
19 685, 562, 357
25 685, 653, 358
26 638 br, 357
29 640 br, 358
750
759
728
735
As we already noted, in the recent time unsym-
metrical azaporphyrins containing both different func-
tional substituents and fused heterocyclic fragments
at the pyrrole rings attract increasing interest. Im-
portant aspects in studying these compounds are the
effects of functional and hetero substitutions on their
properties and search for their possible application.
The synthesis and properties of tetra(1,4-dithiacyclo-
hexeno)- and octaphenyltetraazaporphyrins have been
estensively studied [49, 56 59]. However, there are
no published data on compounds having a combina-
tion of fragments intrinsic to the above azaporphyrins.
We have synthesized unsymmetrical azaporphyrins
possessing both phenyl groups and fused 1,4-dithia-
cyclohexene rings in a single molecule and examined
their properties [52, 60]. As starting compounds we
used compound XIV and 5-amino-2,2-dichloro-3,4-
ethylenedisulfanyl-2H-pyrrole hydrochloride (XIX),
as well as compounds VII and XVd.
We succeeded in separating isomers A and B of
both free ligand H2Pa(PhAr)2(Ph)4 (XVIIId) and its
copper(II) complex [52]. Taking into account better
solubility of these compounds due to greater number
of phenyl substituents (as compared to dibenzotetra-
phenyltetraazaporphyrins) [55], the eluent composi-
tion (benzene heptane) was changed toward higher
concentration of heptane. According to the TLC data
and electronic absorption spectra, the isolated isomers
were individual substances. Their electronic absorp-
tion spectra differed both in the character and in the
position of bands (Table 6). The first long-wave ab-
sorption band of the less mobile CuPa(PhAr)2(Ph)4
isomer appears by 27 nm red relative to the corre-
sponding band in the spectrum of octaphenyltetraaza-
porphyrin copper complex, and by 7 nm, as compared
to tetraphenylbenzotetraazaporphyrin. The more
mobile isomer of CuPa(PhAr)2(Ph)4 displayed two
strong long-wave bands with their maxima at 657
and 624 nm and two weak bands at 700 and 570 nm.
The positions of the Soret bands of both isomers
differed insignificantly.
Di(1,4-dithiacyclohexeno)tetraphenyltetraazapor-
phyrin H2Pa(DT)2Ph4 and its copper and cobalt com-
plexes XX and di(phenylbenzo)di(1,4-dithiacyclo-
hexeno)tetraazaporphyrin cobalt complex CoPa(DT)2
Ph2 (XXI) were synthesized according to the scheme
shown above. A brief version of that scheme is shown
below.
The differences in the spectra of isomers A and B
S
S
S
S
triethylamine,
hydroquinone,
N
N
N
N
N
N
Cl
Cl
N
CH3ONa,
MCl1
N
N
Ph
Ph
Ph
Ph
S
S
S
S
2
XIV +
N
N
-------
M
-------
M
N
and
N
Ph
N
N
NH2 HCl
N
N
S
S
Ph Ph
XX
MPa(DT)2Ph4; M = 2H, Cu, Co.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

UNSYMMETRICAL AZAPORPHYRINS
1815
S
S
S
S
triethylamine,
hydroquinone,
CH3ONa,
N
N
N
N
N
N
N
N
S
CoCl2
Ph
N
--------
Co N
and
--------
N Co
VII + XVd
Ph
Ph
N
S
N
N
N
N
S
S
XXI
CoPa(DT)2(ArPh)2
Ph
Compounds XX and XXI were isolated as violet
powders which were soluble in benzene, chloroform,
and other organic solvents. In each case, we isolated
by column chromatography one deeply colored frac-
tion which was separated by TLC to obtain two prod-
ucts with the same elemental composition and
similar spectral parameters but different Rf values.
Compounds XX and XXI showed in the IR spectra a
D
1.0
1
0.5
2
1
0
weak absorption in the region 600 650 cm (C S)
400
500
600 700 , nm
1
and bands at 2840 2870 cm due to stretching vibra-
Fig. 6. Electronic absorption spectra of CuPa(DT) (Ph)
(isomer A) in (1) benzene and (2) sulfuric acid.
tions of C H bonds in the methylene groups of the
1,4-dithiacyclohexene rings.
2
4
The electronic absorption spectra of the di(1,4-di-
Table 8. Yields, Rf values, and electronic absorption spec-
tra of sulfur-containing phenyl-substituted azaporphyrins
thiacyclohexeno)tetraphenyltetraazaporphyrin
complexes contained one strong long-wave band at
623 642 nm and the Soret band at 335 342 nm.
Also, a weak absorption was present at 440 460 nm;
metal
Electronic absorption
spectrum, max, nm
*
Yield,
%
it corresponds to n
transitions involving n elec-
Compound
Rf
trons on the sulfur atoms. The differences in the posi-
tions of the Q-bands of the isomeric copper and cobalt
complexes (islated by TLC) were 6 and 2 nm, respec-
tively. The spectral patterns and position of bands of
the isolated compounds considerably differed from
those observed for the corresponding symmetric aza-
porphyrin and di(R-benzo)tetraphenyltetraazapor-
phyrin derivatives. Unlike the latter, the former dis-
played a lesser number of absorption bands, and the
long-wave absorption maxima were displaced to
shorter wavelengths. The Q-band in the spectra of di-
(phenylbenzo)di(1,4-dithiacyclohexeno)tetraazapor-
phyrin cobalt complex shifts by 26 and 30 nm to the
red region relative to the corresponding bands of the
18 M
benzene
H2SO4
H2Pa(DT)2(Ph)4 (A) 12a
H2Pa(DT)2(Ph)4 (B)
675, 629,
598, 364
686, 635,
598, 362
CuPa(DT)2(Ph)4 (A) 16a
CuPa(DT)2(Ph)4 (B)
0.38 636, 454,
334
0.14 642, 461,
338
0.41 623, 455,
335
0.19 625, 458,
342
675
683
670
673
727
744
CoPa(DT)2(Ph)4 (A) 17a
CoPa(DT)2(Ph)4 (B)
isomeric
di(1,4-dithiacyclohexeno)tetraphenyltetra-
azaporphyrin cobalt complexes. This is the result of
replacement of four phenyl substituents in the azapor-
phyrin macroring by two fused benzene rings, which
increases the aromaticity of the macrocyclic system.
CoPa(DT)2(PhAr)4 (A)
CoPa(DT)2(PhAr)4 (B)
5
5
0.26 649, 458,
340
0.09 655, 456,
342
Complexes XX and XXI are fairly stable in con-
centrated sulfuric acid. Their electronic absorption
a
Before separation of the isomers by TLC.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

1816
MAIZLISH et al.
spectra in that solvent contain a diffuse band in the
region 670 683 nm (Fig. 6, Table 8). The absorp-
tion at 440 460 nm, which is typical of solutions in
organic solvents, disappears in going to sulfuric acid
solution. The red shift of the Q-band in the spectra
recorded in concentrated sulfuric acid relative to its
position in the spectra obtained in organic solvents is
considerably smaller than the corresponding shift ob-
served for phthalocyanine metal complexes. As noted
above, these spectral changes result from protonation
of the sulfur atoms.
18. Leznoff, C.C., Greenberg, S., Knouw, B., and Le-
ver, A.B.P., Can. J. Chem., 1987, vol. 65, no. 8,
p. 1705.
19. Young, J.G. and Onyebuagu, W., J. Org. Chem., 1990,
vol. 55, no. 2, p. 2155.
20. Sastre, A., Del Rey, B., and Torres, T., J. Org. Chem.,
1996, vol. 61, no. 24, p. 8591.
21. Ando, M. and Mori, M., JPN Patent Appl. no. 63-
159949, 1988; Ref. Zh., Khim., 1991, no 2 N 210 P.
22. Kasuga, K., Idehara, T., Handa, M., and Isa, K., Inorg.
Chim. Acta, 1992, vol. 196, no. 2, p. 127.
REFERENCES
23. Kobayashi, N., Kondo, R., Nakajima, S., and Osa, T.,
J. Am. Chem. Soc., 1990, vol. 112, p. 9640.
1. Moser, F.H. and Thomas, A.L., The Phthalocyanines,
Boca Raton: CRC, 1983, vols. 1, 2.
24. Sastre, A., Torres, T., and Hanack, M., Tetrahedron
Lett., 1995, vol. 36, no. 46, p. 8501.
2. The Phthalocyanines: Properties and Applications,
Leznoff, C.C. and Lever, A.B.P., Eds., New York:
VCH, 1996, vol. 4.
3. De la Torre, G., Vazquez, P., Adullo-Lopez, F., and
Torres, T., J. Mater. Chem., 1998, vol. 8, no. 8,
p. 1671.
4. McKeown, N.B., Cook, M.J., Thomson, A.J., Har-
rison, K.J., Daniel, M.F., Richardson, R.M., and
Roser, S.J., Thin Solid Films, 1988, vol. 159, p. 469.
5. Palasin, S., Lesieur, P., Stefanelli, I., and Roser, S.J.,
Thin Solid Films, 1988, vol. 159, p. 83.
6. Piechocki, C. and Simon, J., J. Chem. Soc., Chem.
Commun., 1985, no. 5, p. 259.
7. Lawrence, D.S. and Whitten, D.G., Photochem.
Photobiol., 1996, vol. 64, no. 6, p. 923.
8. Linben, T.G. and Hanack, M., Chem. Ber., 1994,
vol. 127, no. 10, p. 2051.
25. Kulinich, V.P., Maizlish, V.E., Shaposhnikov, G.P.,
Doroshina, O.V., and Smirnov, R.P., Izv. Vyssh.
Uchebn. Zaved., Ser. Khim. Khim. Tekhnol., 1993,
vol. 36, no. 3, p. 37.
26. Maizlish, V.E., Kolesnikova, E.E., Kulinich, V.P.,
Sokolovskaya, E.E., Shaposhnikov, G.P., and Smir-
nov, R.P., Koord. Khim., 1994, vol. 20, no. 10, p. 766.
27. Maizlish, V.E., Kulinich, V.P., Shaposhnikov, G.P.,
Doroshina, O.V., Sokolovskaya, E.E., and Smir-
nov, R.P., Koord. Khim., 1995, vol. 21, no. 2, p. 149.
28. Maizlish, V.E., Kulinich, V.P., Shaposhnikov, G.P.,
and Smirnov, R.P., Izv. Vyssh. Uchebn. Zaved., Ser.
Khim. Khim. Tekhnol., 1998, vol. 41, no. 2, p. 71.
29. Maizlish, V.E., Kulinich, V.P., Kolesnikova, E.E.,
Sokolovskaya, E.E., Shaposhnikov, G.P., and Smir-
nov, G.P., Russian Patent no. 2093515, 1993; Byull.
Izobret., 1997, no. 29.
9. Ikeda, Y., Konami, H., Hatano, M., and Mochizuki, K.,
Chem. Lett., 1992, no. 5, p. 763.
10. Leznoff, C.C., McArthur, C.R., and Qin, Y.N., Can. J.
Chem., 1993, vol. 71, no. 9, p. 1319.
30. Kulinich, V.P., Nikulina, T.A., Maizlish, V.E., Sha-
poshnikov, G.P., Sokolovskaya, E.E., and Smir-
nov, R.P., Russ. J. Gen. Chem., 1994, vol. 64, no. 4,
p. 594.
11. Albert, B., Kuppelmaier, H., and Wagenblast, G.,
FRG Patent Appl. no. 3711762, 1987; Ref. Zh.,
Khim., 1989, no. 12N235P.
31. Kulinich, V.P., Shaposhnikov, G.P., Maizlish, V.E.,
Nikulina, T.A., and Smirnov, R.P., Koord. Khim.,
1996, vol. 22, no. 6, p. 502.
12. Rajic, N.Z. and Stojakovic, D.R., J. Serb. Chem. Soc.,
32. Kulinich, V.P., Shaposhnikov, G.P., Maizlish, V.E.,
and Smirnov, R.P., Russ. J. Gen. Chem., 1996, vol. 66,
no. 9, p. 1518.
1989, vol. 54, no. 3, p. 141.
13. Kobayashi, N., Ashida, T., and Osa, T., Chem. Lett.,
1992, no. 10, p. 2031.
33. Maizlish, V.E., Kulinich, V.P., Shishkina, O.V., Do-
roshina, O.A., Shaposhnikov, G.P., and Smirnov, R.P.,
Russ. J. Gen. Chem., 1997, vol. 67, no. 5, p. 850.
14. Kobayashi, N., Ashida, T., Hiroja, K., and Osa, T.,
Chem. Lett., 1992, no. 8, p. 1567.
34. Maizlish, V.E., Kulinich, V.P., Shaposhnikov, G.P.,
and Smirnov, R.P., Russian Patent no. 2134268,
1995; Byull. Izobret., 1999, no. 22.
15. Kobayashi, N., Ashida, T., Osa, T., and Konami, H.,
Inorg. Chem., 1994, vol. 33, no. 9, p. 1735.
16. Subbotin, N.B., Nemykin, V.N., and Voloshin, V.S.,
Mendeleev Commun., 1993, no. 5, p. 12.
17. Nemykin, V.N., Subbotin, N.B., Kostromina, N.A.,
Volkov, S.V., and Luk’’yanets, E.A., Zh. Neorg.
Khim., 1995, vol. 40, no. 7, p. 1183.
35. Kulinich, V.P., Nikulina, T.A., Maizlish, V.E., Sha-
poshnikov, G.P., and Smirnov, R.P., Russian Patent
no. 2122547, 1994; Byull. Izobret., 1998, no. 33.
36. Maizlish, V.E., Kulinich, V.P., Shaposhnikov, G.P.,
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004

UNSYMMETRICAL AZAPORPHYRINS
1817
Smirnov, R.P., and Sokolovskaya, E.E., Russian
Patent no. 2064 928, 1993; Byull. Izobret., 1996,
no. 22.
Structure, Properties, and Synthesis), Enikolo-
pyan, N.S., Ed., Moscow: Nauka, 1985.
48. Vasil’ev, S.I., Kulinich, V.P., Shaposhnikov, G.P.,
and Smirnov, R.P., Russian Patent no. 2139289,
1997; Byull. Izobret., 1999, no. 28.
49. Vasil’ev, S.I., Kulinich, V.P., Shaposhnikov, G.P., and
Smirnov, R.P., Russ. J. Gen. Chem., 1998, vol. 68,
no. 8, p. 1264.
50. Bartlett, R.K., Renny, Z.V., and Chann, K.K.,
J. Chem. Soc., 1969, no. 1, p. 129.
51. Vasil’ev, S.I., Kulinich, V.P., Shaposhnikov, G.P., and
Smirnov, R.P., Russ. J. Gen. Chem., 1999, vol. 69,
no. 2, p 314.
37. Maizlish, V.E., Kulinich, V.P., Shaposhnikov, G.P.,
Kolesnikova, E.E., Doroshina, O.A., and Smir-
nov, R.P., Russian Patent no. 2074180, 1993; Byull.
Izobret., 1997, no. 6.
38. Vollmann, H., The Chemistry of Synthetic Dyes,
Venkataraman, K., Ed., New York: Academic, 1971,
vol. 5. Translated under the title Khimiya sintetiches-
kikh krasitelei, Leningrad: Khimiya, 1977, vol. 5,
p. 268.
39. Sidorov, A.N. and Kotlyar, I.P., Opt. Spektrosk., 1961,
vol. 11, no. 2, p. 175.
52. Kulinich, V.P. and Shaposhnikov, G.P., Russ. J. Gen.
Chem., 2001, vol. 71, no. 10, p. 1632.
40. Elektronnye spektry ftalotsianinov i rodstvennykh so-
edinenii: Katalog (Electronic Spectra of Phthalocy-
anines and Related Compounds. Catalog), Luk’’ya-
nets, E.A., Ed., Cherkassy: NIITEKhim, 1989.
53. Gordon, A.J. and Ford, R.A., The Chemist’s Com-
panion, New York: Wiley, 1972.
54. Bauman, F., Bienert, B., and Rosch, G., Angew. Chem.,
41. Negrimovskii, V.M., Cand. Sci. (Chem.) Dissertation,
1956, vol. 68, no. 4, p. 133.
Moscow, 1994.
55. Vasil’ev, S.I., Kulinich, V.P., Shaposhnikov, G.P., and
Smirnov, R.P., Russ. J. Gen. Chem., 1999, vol. 69,
no. 12, p. 1956.
42. Maizlish, V.E., Shaposhnikov, G.P., Snegireva, F.P.,
Mochalova, N.L., and Smirnov, R.P., Izv. Vyssh.
Uchebn. Zaved., Ser. Khim. Khim. Tekhnol., 1988,
vol. 31, no. 5, p. 42.
56. Wolf, W., Degener, E., and Petersen, S., Angew.
Chem., 1960, vol. 72, no. 24, p. 963.
43. Berezin, B.D., Koordinatsionnye soedineniya porfi-
rinov i ftalotsianina (Coordination Compounds of
Porphyrins and Phthalocyanine), Moscow: Nauka,
1978.
57. Shaposhnikov, G.P., Kulinich, V.P., Osipov, Yu.M.,
and Smirnov, R.P., Khim. Geterotsikl. Soedin., 1986,
no. 5, p. 603.
58. Shaposhnikov, G.P., Kulinich, V.P., Osipov, Yu.M.,
and Smirnov, R.P., Khim. Geterotsikl. Soedin., 1986,
no. 9, p. 1276.
44. Sidorov, A.N. and Akopov, A.S., Koord. Khim., 1987,
vol. 13, no. 10, p. 1318.
45. Korzhenevskii, A.B., Cand. Sci. (Chem.) Dissertation,
59. Khelevina, O.G., Chizhova, N.V., and Berezin, B.D.,
Ivanovo, 1977.
Russ. J. Org. Chem., 1998, vol. 34, no. 5, p. 607.
46. Bykova, V.V., Cand. Sci. (Chem.) Dissertation,
60. Vasil’ev, S.I., Kulinich, V.P., Shaposhnikov, G.P., and
Smirnov, R.P., Russ. J. Gen. Chem., 2000, vol. 70,
no. 2, p. 304.
Ivanovo, 1981.
47. Porfiriny: struktura, svoistva, sintez (Porphyrins:
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 11 2004