Synthesis and coordination properties of the zinc complex of dimeric porphyrin in reactions with imidazole, 2-methylimidazole, and the pyridine in benzene

Article abstract of DOI:10.1134/S1070363208030250

Dimeric porphyrin(2,6-bis[15′-(3″,5″-di-tert-butylphenol) -3′,7′,13′,17′-tetramethyl-2′,8′,12′, 18-tetraethylporphin-5′-yl]-4-tert-buthylphenol) and its binuclear zinc complex were obtained from 4,4′-dimethyl-3,3′- diethyldipyrrolylmethane, 2,6-diformyl-4-tert-butylphenol and 3,5-di-tert-buthylbenzaldehyde. Coordina-tion properties of dimeric zincporphyrin in the intermolecular reaction with nitrogen-containing bases (imidazole, 2-methylimidazole, and pyridine) in benzene were studied. Geometry and electronic structure of the zincporphyrin and its molecular complexes were calculated by a quantum-chemical method. Energy characteristics of the intermolecular reaction of the dimeric zincporphyrin with bases were determined. The calculated energies of the central metal atom interaction with the nitrogen atom of an extra-ligand agree well with the stability of the Zn-porphyrin molecular complexes. The influence of the deformation distortions of the porphyrin ligand on the strength of the metal-extra-ligand σ-bond was established.

Full text of DOI:10.1134/S1070363208030250

ISSN 1070-3632, Russian Journal of General Chemistry, 2008, Vol. 78, No. 3, pp. 493–502. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © S.V. Zaitseva, S.A. Zdanovich, A.S. Semeikin, O.I. Koifman, 2008, published in Zhurnal Obshchei Khimii, 2008, Vol. 78,
No. 3, pp. 508–517.
Synthesis and Coordination Properties of the Zinc Complex
of Dimeric Porphyrin in Reactions with Imidazole,
2-Methylimidazole, and the Pyridine in Benzene
S. V. Zaitsevaa, S. A. Zdanovicha, A. S. Semeikinb, and O. I. Koifmana,b
aInstitute of Solution Chemistry, Russian Academy of Sciences,
ul. Akademicheskaya 1, Ivanovo, 15345 Russia
e-mail: svz@isc-ras.ru
bIvanovo State University of Chemical Engineering, Ivanovo, Russia
Received June 15, 2007
Abstract—Dimeric porphyrin(2,6-bis[15'-(3'',5''-di-tert-butylphenol)-3',7',13',17'-tetramethyl-2',8',12',18-tetra-
ethylporphin-5'-yl]-4-tert-buthylphenol) and its binuclear zinc complex were obtained from 4,4'-dimethyl-3,3'-
diethyldipyrrolylmethane, 2,6-diformyl-4-tert-butylphenol and 3,5-di-tert-buthylbenzaldehyde. Coordina-tion
properties of dimeric zincporphyrin in the intermolecular reaction with nitrogen-containing bases (imidazole, 2-
methylimidazole, and pyridine) in benzene were studied. Geometry and electronic structure of the
zincporphyrin and its molecular complexes were calculated by a quantum-chemical method. Energy
characteristics of the intermolecular reaction of the dimeric zincporphyrin with bases were determined. The
calculated energies of the central metal atom interaction with the nitrogen atom of an extra-ligand agree well
with the stability of the Zn-porphyrin molecular complexes. The influence of the deformation distortions of the
porphyrin ligand on the strength of the metal–extra-ligand σ-bond was established.
DOI: 10.1134/S1070363208030250
Properties of metalporphyrins are governed by their
structural diversity, conformation transformations of
macrocycles and the ability of a central metal atom to
interact with various donor ligands [1–4]. In the
present work we continue the study of the steric
macrocycle stress influence on coordination properties
of metalporphyrins. We describe here the synthesis of
the dimeric zincporphyrin (ZnP), 2,6-bis[zinc 15'-
(3'',5''-di-tert-butyl-phenyl)-3',7',13',17'-tetramethyl-
2',8',12',18'-tetraethylporphin-5'-yl]-4-tert-buthyl-
phenol with a slightly strained macrocycle and the
regularities of its intermolecular interaction with
nitrogen bases–extra-ligand [(L = imidazole (Im), 2-
methylimidazole, and pyridine (Py)].
____________
Et
Et
N
N
Et
Et
N
N
OH
N
N
Zn
Zn
Et
Et
N
N
Et
First macrocycle
Et
Second macrocycle
493

494
ZAITSEVA et al.
The reaction ZnP + Ln = Zn(L)nP was carried out in
equilibrium solution; А0 is optical density of a free
metalporphyrin solution; A0 is optical density of an
equilibrium solution with the maximal extra-ligand
concentration.
benzene at 295 K, which was used owing to its
inertness. This solvent does not solvate the metal atom
and does not render essential influence on the ability of
the metalporphyrin to coordinate an additional
molecular ligand.
The formation of a binuclear complex (L)nZnP
results in a red shift of the basic absorption bands of
the chromophore in the electronic spectrum and in the
variation of their intensity (Fig. 1), that allows us to
use the spectral method in studying coordination
properties of the dimeric zincporphyrins. Equilibrium
in the metalporphyrin–base system is reached
practically instantaneously. The coordination process,
as well as any other reversible reaction, obeys the mass
action law and is ruled by stability constant (3).
Coordination properties of dimeric ZnP were
studied using spectrophotometric titration [5, 7–10]
and computer simulation [11–14]. The spectro-
photometric method allows evaluation of con-centra-
tions of absorbing species, metalporphyrins and their
extra-complexes, as their dilute solutions obey
Bouguer–Beer law (1).
(1)
A = εcl.
Here A is optical density of a solution; ε is molar
absorption coefficient; c is concentration of absorbing
material, M; l is width of a solution layer.
Kst = [(L)nMP]/[MP][L]n.
(3)
In spite of the fact that the retention of isobestic
points in electronic spectra of complexes with extra-
ligands proves the presence of two colored compounds
in a solution under study, absorption spectra of
metalporphyrins with one and two extra-ligands are
very close to each other, and the displacement of the
isobestic point is comparable with the experimental
error. Therefore we used the Bent-French method [5]
to determine a number of attached ligands. In all cases
(coordination of Im, 2-MеIm, and Py) the dependences
of log [(Aeq – A0)/(A∞ – Aeq] on log cL are linear. The
slope of these straight lines is 1.052, 1.139, and 0.998,
respectively, that corresponds to unity within the limits
of experimental error (Fig. 2). Thus, a complex (L)ZnP
is formed in the course of the inter-molecular
interaction. The attachment of one base molecule,
despite of the presence of two complex-forming
centers, seems to be connected with certain hindrances
caused by mutual screening of reaction centers by
macrocycles arranged under an angle to each other.
Possible orientation of a nitrogen base in (L)ZnP
complexes will be considered below.
The constant of extra-complex stability wаs
calculated by equation (2) for three-component
equilibrium systems.
(Aeq – A0)/(A∞ – A0)
Kst =
1 – (Aeq – A0)/(A∞ – A0)
1
(cL – c0MP)[(Aeq – A0)/(A∞ – A0)]
.
(2)
×
Here с0MP is the initial concentration of a metal-
porphyrin in a solution; Aeq is optical density of an
Table 1. Stability constants of extra-complexes of dimeric
zincporphyrin, shift of their characteristic absorption bands
in benzene, and calculated energy of the zinc atom bond
with the nitrogen atom of the base
Eb (Zn–NL),
Δλ,
nm
kcal mol–1
Complex
(Im)ZnP
(Py)ZnP
Ks2t95, M
pKex+а
The resulting stability constants (Kst) and calculated
structure and energy parameters of the zinc complexes
are given in Tables 1 and 2. The analysis of these data
allows us to estimate the strength of binding nitrogen
bases with the dimeric Zn-porphyrin and to obtain the
stability series: (Im)ZnP > (Py)ZnP > (2-MeIm)ZnP.
This trend is caused by weakening basic properties of
extra-ligands on passing from imidazole to pyridine
and by steric hindrances (in the case of 2-MeIm the
52200 4780 6.65 11.0
–18.23b,
–18.11c
–14.94b,
–14.63c
–13.53b,
–13.49c
5860 427
1950 179
5.29 10.0
5.89 7.9
(2-MeIm)
ZnP
a
The value found by the potentiometric method in water at 298 K
[18]. b Isomer A. c Isomer B.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 3 2008

SYNTHESIS AND COORDINATION PROPERTIES OF THE ZINC COMPLEX
495
424 nm
413 nm
(b)
A
12
0.8
A
1
0.7
0.6
0.5
0.4
0
1
2
3
4
cIm×104, M
(a)
549 nm
12
538 nm
1
2–12
2–12
×5
550
400
450
500
600 λ, nm
Fig. 1. (a) Electron absorption spectrum (EAS) of dimeric zincporphyrin (ZnP) with imidazole in benzene: (1) ZnP without adding
imidazole (cZnP 5.52 × 10–6 M); (2–11) ZnP with intermediate imidazole concentrations (cZnP 5.52 × 10–6 M; cIm 2.11 × 10–5–4.21 ×
10–4 M); (12) ZnP with imidazole excess (cIm 2.42 × 10–3 M). (b) Corresponding titration curve; λ 413 nm.
1.5
methyl group is in the ortho-position of the base)
affecting the coordination. The comparison of Kst
values for dimeric and monomeric zinc complexes
shows that the stability of those latter is much lower
[6]. It results both from the electron effects of
substituents and macrocycles (in the case of a dimer)
and from the deformation strain of a macrocyclic
ligand.
2-Me-Im
1.0
0.5
Im
0.0
–0.5
–1.0
–1.5
2.5 3.0
3.5
4.0
4.5
5.0
log cL
tanα
tanα
tanα 1.0
It was found that the stability constant depends on
the basicity of an additional molecular ligand des-
cribed by the value of рKex+.
The comparison of Kst for zinc extra-complexes
with the variation of absorption bands positions in the
electronic spectra of metalporphyrins (Δλmax) shows
that these values correlate with each other (Fig. 3). The
undirectional dependence described by the equation:
Fig. 2. Dependences of log [(Aeq – A0)/(A∞ – Aeq] on log cL for
the intermolecular reaction of dimeric ZnP with a nitrogen base;
A∞, Aeq, and A∞ are optical densities of solutions on a working
wavelength for metalporphyrin and for equilibrium mixtures at
certain concentrations of the base and the complex.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 3 2008

496
ZAITSEVA et al.
Table 2. Certain calculated characteristics of optimized molecules of dimeric ZnP extra-complexes
Macrocycle 1
Macrocycle 2
b
c
c
Оph–Zn1
Р1
Р2
а
qOph
,
N1–N3 Zn–N1 Zn–N2
N2–N4 Zn–N3 Zn–N4
N1–N3 Zn–N1 Zn–N2
N2–N4 Zn–N3 Zn–N4
Complex
ZnP
Оph–Zn2b
Zn–NL, Zn–Ctd,
Zn–NL, Zn–Ct,
units
Å
Å
Å
Å
Å
Å
Å
Å
Å
Å
Å
Å
–0.214 5.6248
5.1906
11.6131 4.1014 2.0684 2.0458
11.5836 4.1139 2.0331 2.0682
11.6081 4.0970 2.0672 2.0501
11.6775 4.1147 2.0298 2.0647
0.0128 4.0816 2.0674 2.0602
4.1100 2.0166 2.0493
0.0704
(Im)ZnP
–0.237 5.5430
5.1088
0.0128 4.1352 2.1200 2.1093 2.0859 0.4288
4.1258 2.1032 2.0897
(isomer A)
(isomer B) –0.227 5.3162
11.7086 4.1429 2.1168 2.1006 2.0917 0.3976 4.0783 2.0666 2.0553
0.0818
5.2636
11.5763 4.1411 2.1017 2.1137
11.6105 4.0969 2.0672 2.0497
11.6717 4.1149 2.0298 2.0653
4.1023 2.0151 2.0482
(Py)ZnP
–0.231 5.5575
5.0660
0.0119 4.1336 2.1185 2.1115 2.1116 0.4273
4.1224 2.1025 2.0848
(isomer A)
(isomer B) –0.215 5.3862
5.2134
11.7311 4.1431 2.1154 2.0961 2.1146 0.3941 4.0798 2.0667 2.0567
0.0738
11.6196 4.1403 2.1020 2.1145
11.6104 4.0972 2.0675 2.0496
11.6738 4.1151 2.0298 2.0655
4.1044 2.0155 2.0485
(2-MeIm) –0.218 5.5803
0.0128 4.1328 2.1247 2.1155 2.1145 0.4326
4.1276 2.0977 2.0916
ZnP
(isomer A) –0.226 5.3159
(isomer B) 5.2538
5.0165
11.7057 4.1407 2.1162 2.0999 2.1197 0.4096 4.0789 2.0668 2.0558
11.5770 4.14 2.1048 2.1188 4.1033 2.0153 2.0485
0.0798
a Charge on Oph atom of bridging phenol. b Zn1 and Zn2 are central atoms of the first and the second macrocycles, respectively. c Perimeter
of coordination plane N4 of the first and the second macrocycle, respectively. d Ct – centre of a macrocycle coordination cavity.
log Kst = 0.1538 (Δλmax)2 – 2.477Δλmax + 13.299 (r
0.96), differs in character from the linear dependence
for the case of ZnTPP [7]. The deviation from
linearity, as in the above-described case, is caused by
an increase in steric strain in dinuclear ZnP on the
coordination of an external ligand. The non-planarity
of the ZnP structure and the change in the extent of the
macrocycle deformation on the coordination with an
extra-ligand were also confirmed by the quantum-
chemical calculations.
compound under study with a base, to understand the
reasons of variations in stability of formed complexes
of binuclear zincporphyrin from the position of
structural and energy characteristics of the
metalporphyrin and the extra-ligand (Table 2). We
have found on the basis of the calculated data that the
dimeric zincporphyrin is nonplanar and strained (Fig. 4).
The angle between macrocycles in the complex under
study is 112°. The phenyl groups are oriented to the
plane of tetrapyrrole fragments under an angle of 84°–
86°. Alkyl substituents pairwise protrude into a solvent
on the both sides of the macrocycle under an angle of
60°–62°. It is necessary to note that deformation
strains of macrocycles are ambiguous. One fragment
has a rather planar structure of a coordination center
with a small deviation of the metal atom from the
plane. The structure of the second macrocycle is
nonplanar with dominating saddle-like deformation
(Fig. 4). The perimeter of its coordination plane N4 is
less by 0.295 Å than that of the first macrocycle.
Quantum-chemical calculations allow prediction of
the course of the intermolecular interaction of the
log Kst
Im
4.6
Py
3.9
3.2
2.5
2-MeIm
8
We believe that the difference in the extent of
deformation of two macrocycles is connected both
with their mutual influence and the orientation of the
OH group of bridging phenol (Fig. 4). The proximity
of oxygen to the N4 plane of the second tetrapyrrole
7
9
10
11 Δλmax, nm
Fig. 3. Dependence of log Kst of dimeric ZnP molecular
complexes on the shift of basic absorption bands in EAS.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 3 2008

SYNTHESIS AND COORDINATION PROPERTIES OF THE ZINC COMPLEX
497
Fig. 4. Structure of a dimeric ZnP molecule calculated by the PM3 quantum-chemical method in various projections.
fragment (closer by 0.4336 Å than to the first
fragment) affects the structure of the coordination
cavity and causes a redistribution of electron density
on neighboring atoms. The charge on the zinc atom in
this case is less by 0.01 units than the charge of the
central metal atom of the first macrocycle.
porphyrin deformation, axial and torsional strains of
macrocycles increasing (Table 2, Fig. 5).
On the basis of the quantum-chemical calculations
we have found that isomers of the molecular
complexes are formed in the reaction course. The
existence of structures A and B (Fig. 6) is most energy
favorable. The conformation conversion of these forms
for (Im)ZnP, (Py)ZnP, and (2-MeIm)ZnP corresponds
The formation of the molecular complex is
accompanied by a change in the extent of dimeric
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 3 2008

498
ΔZ, Å
ZAITSEVA et al.
macrocycle 2
macrocycle 1
ZnP
ΔZ, Å
0.40
0.40
0
0
10
10
20
20
0.20
0.20
0.00
–
0.00
–
0
10
20
Atom no.
0.20
0.20
Atom no.
Isomer А
(Im)ZnP
ΔZ, Å
ΔZ, Å
0.40
0.40
0.20
0.00
–
0.20
0.00
–
0
10
20
0
10
20
Atom no.
Atom no.
0.20
0.20
(Py)ZnP
ΔZ, Å
0.40
ΔZ, Å
0.40
0.20
0.20
0.00
–
0.00
–
0
10
20
0
10
20
Atom no.
0.20
0.20
Atom no.
(2-MeIm)ZnP
ΔZ, Å
ΔZ, Å
0.40
0.40
0.20
0.20
0.00
0.00
–
0
10
20
0
10
20
–
Atom no.
Atom no.
0.20
0.20
Fig. 5. Deviations of porphyrin macrocycle skeletal atoms in dimeric ZnP and in its molecular complexes with nitrogen-containing
bases from the molecule medial plane (ΔZ) as calculated by the PM3 quantum-chemical method.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 3 2008

SYNTHESIS AND COORDINATION PROPERTIES OF THE ZINC COMPLEX
499
Isomer B
(Im)ZnP
macrocycle 1
macrocycle 2
ΔZ, Å
ΔZ, Å
0.40
0.40
0.20
0.00
0.20
0.00
0
0
0
10
20
0
10
20
–0.20
–0.40
–0.60
–0.20
–0.40
Atom no.
Atom no.
–0.60
(Py)ZnP
ΔZ, Å
ΔZ, Å
0.40
0.40
0.20
0.00
0.20
0.00
10
20
0
10
20
–0.20
–0.40
–0.60
–0.20
–0.40
–0.60
Atom no.
Atom no.
(2-MeIm)ZnP
ΔZ, Å
ΔZ, Å
0.40
0.40
0.20
0.00
0.20
0.00
10
20
0
10
20
–0.20
–0.40
–0.60
–0.20
–0.40
–0.60
Atom no.
Atom no.
Fig. 5. (Contd.)
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 3 2008

500
ZAITSEVA et al.
Isomer A
Isomer B
Fig. 6. Structure of isomers of (Im)ZnP complex calculated by the PM3 quantum-chemical method.
to 0.12, 0.31, and 0.4 kcal mol–1, respectively (Table 2).
The molecule of a base interacts with a zinc atom,
being in a cavity between macrocycles. Such
orientation is caused by the metal atom (Zn–Ct)
protruding into the same cavity. In dimeric ZnP the
coordination in the position of the second macrocycle
proceeds easier, as the Zn–Ct distance in it is longer by
0.068 Å than in the first macrocycle. In the course of
the intermolecular interaction the angle between
macrocycles decreases: for (Im)ZnP, (2-MeIm)ZnP,
and (Py)ZnP by 9°–10°, 4°–5°, and 6°–7°, res-
pectively. In the case of B isomers the slope of phenyl
fragments to the N4 plane changes. In the first
macrocycle this value is 89°–90° and in the second
80°–82°. The attachment of a base results in an
increase in the coordination plane area of the
macrocycle involved in the coordination and in a
decrease in the area of the N4 plane of the neighboring
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 3 2008

SYNTHESIS AND COORDINATION PROPERTIES OF THE ZINC COMPLEX
501
macrocycle, except for (Py)ZnP B isomer (Table 2).
log Kst
The effective charge on the reactive center of the
neighboring macrocycle also decreases: for (Im)ZnP,
(2-MeIm)ZnP, and (Py)ZnP by 0.005–0.01, 0.006–
0.009, and 0.005–0.007 units, respectively. An increase
in the Zn–Ct distance is characteristic for the molecular
complexes: for B isomers in the both macrocycles and
for A isomers in the macrocycle involved in the base
bonding (Table 2).
5.0
Im
4.5
4.0
3.5
3.0
Py
2-MeIm
–13
The extent of the molecular complex strain depends
both on the nature of the base and on its orientation
(Table 2 and Fig. 5). The formation of the Zn–NL bond
leads to a change in the type of the macrocycle
deformation. A mixed deformation type, dome- and
saddle-shaped, with slight waviness is characteristic of
the second macrocycle in the case of isomer A. For
isomer B the dominanting dome-shaped deformation
increases in the first macrocycle (Figs. 5 and 6).
–19
–17
–15
Eb, kcal mol–1
Fig. 7. Correlation between Eb and the molecular complex
stability (for isomer A).
macrocycles, essentially affect coordination properties
of dimeric zincporphyrins.
The analysis of the experimental and calculated
data has shown that the energy of the Zn–NL bond
formation (Eb) in the molecular complex varies in
direct proportion to its stability. The resulting
dependences are described by equations (4) and (5) for
isomers A and B, respectively (Tables 1 and 2, Fig. 7).
EXPERIMENTAL
Optical density for a series of solutions with a
constant metalporphyrin concentration and various
extra-ligand concentrations was measured at 413 and
425 nm for (2-MеIm)ZnP and (Im)ZnP and at 413 and
424 nm for (Py)ZnP at 259 K in cells of 1 cm in
thickness. The inaccuracy of thermostating was no
more than 1 K. The electron absorption spectra were
taken on a Cary-100 spectrophotometer within the
range from 400 up to 650 nm and recorded as graphs
and tables for the subsequent mathematical treatment.
The increase in Eb in the series of complexes (2-
MeIm)ZnP > (Py)ZnP > (Im)ZnP corresponds to the
increase of compounds stability on passing from 2-
methylimidazole to imidazole. A similar trend is also
characteristic for the Zn–NL bond energy. In the series
of the nitrogen-containing bases 2-MeIm > Py > Im the
stability of the complexes increases as the strength of
the Zn–NL σ-bond increases. However, in this series
there is no correlation between the metal deviation
from the N4(Zn–Ct) plane and the Zn–NL bond
strength (Table 2). The mutual influence of ligands
The optimization of Kst values and the deter-
mination of root-mean-square deviations were carried
out using the least squares method. The relative error
in the determination of Kst did not exceed 8–10%.
Quantum-chemical calculations were fulfilled by
the РМ3 semiempirical method, using a combination
of the conjugate gradient Fletcher-Reeves and Polak–
Ribiere methods [14.] The calculation was terminated
on reaching a gradient of 0.01 kcal mol–1 Å.
(4)
(5)
log Kst = –0.2998Eb – 0.7362,
log Kst = –0.3029Eb – 0.7457.
(2,6-Bis[15'-(3'',5''-di-tert-butylphenol)-
3',7',13',17'-tetramethyl-2',8',12',18'-tetra-
ethylporphin-5'-yl]-4-tert-buthylphenol) (I) was syn-
thesized using the procedure [15–17]. At room
temperature a solution of 0.2 g of trichloroacetic acid
in 10 ml of acetonitrile was added with stirring in an
argon atmosphere to a solution of 0.5 g of 4,4'-
dimethyl-3,3'-diethyldipyrrolylmethane, 0.05 g of 2,6-
diformyl-4-tert-butylphenol, and 0.42 g of 3,5-di-tert-
fairly strongly manifests itself in molecular complexes.
The appearance of a Zn–NL bond with one macrocycle
results in essential weakening of the Zn–Np bond in
it and to its strengthening in the other macrocycle
(Table 2).
The aforesaid suggests that deformation strains of
tetrapyrrole fragments, alongside with the nature of
bases and the electron effects of substituents and
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 3 2008

502
ZAITSEVA et al.
butyl-benzaldehyde in 30 ml of acetonitrile. The
mixture was stirred for one day under these conditions;
a solution of p-chloranil in 30 ml of THF was added
and stirred for 4 h. The solvents were distilled off in
vacuum of a water-jet pump; a residue was washed out
with water and dried in air at 70°C. The residue was
dissolved in chloroform and chromatographed on
aluminum oxide (grade II) with chloroform as an
eluent. The second band of the dimeric porphyrin was
gathered. The solutions were evaporated up to a
minimal volume and chromatographed repeatedly on
silica gel. After evaporation to a minimal volume the
porphyrins were precipitated by methanol, filtered off,
and dried. Dimeric porphyrin yield 12.8 mg (1.6%).
EAS, λmax, nm (log ε): 626 (3.52); 574 (4.08); 542
(3.97); 509 (4.45); 412 (5.56) (chloroform). Molecular
weight 1480.185.
Russian Foundation for Basic Research (grants nos.
06-3-325337-a and 07-3-00727-a).
REFERENCES
1. Askarov, K.A., Berezin, B.D., and Evstigneev, R.P.,
Porfiriny: struktura, svoistva, sintez (Porphyrins:
Structure, Properties, Synthesis), Enikolopyan, N.S.,
Ed., Moscow: Nauka, 1985.
2. Scheidt, W.R., Porphyrin Stereochemistry. The Por-
phyrins, Dolphin, D., Ed., New York: Acad. Press, 1979,
vol. 3, Ch. 10, p. 463.
3. Scheidt, W.R. and Lee, Y.J., Struct. Bonding, Berlin::
1987, vol. 64, p. 1.
4. Wickramasinghe, A., Jaquinod, L., Nurco, D.J., and
Smith, K.M., Tetrahedron, 2001, vol. 57, p. 4261.
5. Bulatov, M.I. and Kalinkin, I.P., Prakticheskoe ruko-
vodstvo po fotokolorimetricheskim
i
spektrofoto-
2,6-Bis[zinc-15'-(3'',5''-di-tert-butylphenol)-
3',7',13',17'-tetramethyl-2',8',12',18'-tetraethyl-
porphin-5'-yl]-4-tert-buthylphenol (II). Porphin (10
mg) was dissolved in 50 ml of benzene, then a tenfold
excess of zinc acetate was added to the porphyrin
solution. The reaction mixture was heated and boiled
for 40-50 min. The reaction course was monitored by
the variation of the electron absorption spectrum of the
mixture. The disappearance of porphyrin absorption
bands and the appearance of absorption bands of its
metal complex allowed to judge the completion of the
reaction. After the reaction termination the resulting
mixture was cooled, and excess salt was extracted by
water. The benzene solution of a zinc complex was
evaporated and chromatographed on silica gel (eluent–
chloroform). The crystalline complex was isolated by
precipitation from chloroform. Yield 91%. EAS
(benzene), λmax, nm (log ε): 573.0 (4.14), 538.0 (4.47),
metricheskim metodam analiza (Manual on Photo-
colorimetric and Spectrophotometric Methods of Ana-
lysis), Leningrad: Khimiya, 1968.
6. Zaitseva, S.V., Zdanovich, S.A., and Koifman, O.I.,
Koord. Khim., 2006, vol. 32, no. 7, p. 54.
7. Zaitseva, S.V., Zdanovich, S.A., Ageeva, T.A., Golub-
cikov, О.А., and Semeikin, A.S., Koord. Khim., 2001,
vol. 27, no. 3, p. 168.
8. Zaitseva, S.V., Cand. Sci. (Chem.) Dissertation, Ivanovo,
1999.
9. Karmanova, T.V., Koifman, O.I., and Berezin, B.D.,
Koord. Khim., 1983, vol. 9, no. 6, p. 772.
10. Tipugina, M.Yu., Lomova, T.N., and Ageeva, T.A., Zh.
Obshch. Khim., 1999, vol. 69, no. 3, p. 459.
11. Stewart, J.J.P., J. Comput. Chem., 1989, vol. 10, p. 209.
12. Stewart, J.J.P., J. Comput. Chem., 1989, vol. 10, p. 221.
13. Stewart, J.J.P., J. Computer-Aided Molecular Desing,
1
413.0 (5.28). Н NMR spectrum, (CDCl3, internal
1990, vol. 4, p. 1.
standard TMS, δ, ppm: 11.45 s (1H, OH–Ph); 10.25
with (4H, meso-H), 8.40 d (4H, Ho); 8.28 t (4H, Hn);
4.33 q (16H, CH2CH3), 2.43 s (24H, CH3), 1.50 s
(36H, t-Bu); 1.75 t (24H, CH2CH3), 1.45 s (9H, t-
BuPh). Found, %: C 76.2, H 7.39, N 7.20.
C98H114Zn2N8O. Calculated, %: C 75.97, H 7.36, N
7.23.
14. Fletcher, R., Methods of Optimization, New York: J. Wiley,
1980, p. 45.
15. Treibs, A. and Haberle, N., Liebigs Ann., 1968, vol. 718,
p. 183.
16. Mamardashvili, N.Z., Semeikin, A.S., and Golubchi-
kov, O.A., Zh. Org. Khim., 1993, vol. 29, no. 6, p. 1213.
17. Mamardashvili, N.Zh., Semeikin, A.S., Berezin, B.D.,
and Golubchikov, O.A., USSR Inventor’s Certificate
no. 1671665, 1991, Byul. Izobret., 1991.
ACKNOWLEDGMENTS
This work was financially supported by the
program of the Russian Academy of Sciences “Theo-
retical and experimental study of the chemical bond
nature and of mechanisms of the most important
chemical reactions and processes'” (2007) and by the
18. Tablitsy constant skorostei
i ravnovesii gomoli-
ticheskikh organicheskikh reaktsii (Tables of Rate Con-
stants and Equilibria of Homolytic Organic Reactions),
Moscow: Viniti, 1976, vol. 2.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 78 No. 3 2008