Synthesis and reactivity of metal-containing monomers 64. Synthesis, structure, polymerization, and catalytic properties of the palladium and cobalt vinylporphyrin complexes

Article abstract of DOI:10.1007/s11172-007-0026-z

2-Vinylporphyrin and its complexes with Pd^II and Co^II were synthesized and characterized by NMR, IR, and mass spectra. The palladium vinylporphyrin complexes are efficient metal-containing monomers in radical copolymerization with styrene. Palladium(II) in an amount of up to 1 mol.% can thus be introduced into the polymers. The synthesized polymeric Pd complexes perform the photosynthesized activation of dioxygen to the lowest excited singlet state, which is an active oxidizing agent for anthracene producing the 1,4-addition products. The monomeric and macromolecular cobalt complexes are chain-transfer catalysts in radical styrene polymerization. Springer Science+Business Media, Inc. 2007.

Full text of DOI:10.1007/s11172-007-0026-z

Russian Chemical Bulletin, International Edition, Vol. 56, No. 1, pp. 160—167, January, 2007
160
Synthesis and reactivity of metalꢀcontaining monomers
64.* Synthesis, structure, polymerization, and catalytic properties
of the palladium and cobalt vinylporphyrin complexes
V. V. Berezovskii,a D. Wöhrle,b O. Tsaryova,b S. G. Makarov,b S. I. Pomogailo,c N. N. Glagolev,d
a
a
c
c
ꢀ
Z. I. Zhilina, I. S. Voloshanovskii, V. P. Roshchupkin, and A. D. Pomogailo
aI. I. Mechnikov Odessa National University,
2 ul. Dvoryanskaya, 65026 Odessa, Ukraine
bInstitute of Organic and Macromolecular Chemistry, University of Bremen,
P.O. Box 330 440, 28334 Bremen, Germany
cInstitute of Problems of Chemical Physics, Russian Academy of Sciences,
1 prosp. Akad. Semenova, 142432 Chernogolovka, Moscow Region, Russian Federation.
Fax: +7 (496) 515 5420. Eꢀmail: adpomog@icp.ac.ru
dN. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences,
4 ul. Kosygina, 119991 Moscow, Russian Federation
2ꢀVinylporphyrin and its complexes with PdII and CoII were synthesized and characterized
by NMR, IR, and mass spectra. The palladium vinylporphyrin complexes are efficient metalꢀ
containing monomers in radical copolymerization with styrene. Palladium(II) in an amount of
up to 1 mol.% can thus be introduced into the polymers. The synthesized polymeric
Pd complexes perform the photosynthesized activation of dioxygen to the lowest excited singlet
state, which is an active oxidizing agent for anthracene producing the 1,4ꢀaddition products.
The monomeric and macromolecular cobalt complexes are chainꢀtransfer catalysts in radical
styrene polymerization.
Key words: vinylporphyrins, palladium vinylporphyrin complexes, cobalt vinylporphyrin
complexes, metalꢀcontaining monomers, copolymerization, anthracene, photooxidation,
anthracene endoꢀperoxide.
Metalꢀcontaining polymeric porphyrins and phthaloꢀ
benzene ring. For this purpose, methods for assembling
substituted porphyrin are used directly in the step of
its formation, for instance, by consecutive reactions of
porphyrin cycle formation, introduction of metal ions
(Cu, Co), and synthesis of metal vinylporphyrin by the
Wittig reaction8 through the interaction of the correspondꢀ
ing aldehydes with triphenylmethylenephosphorane.
The present work deals with the synthesis and strucꢀ
ture of potential vinylporphyrin (co)mononers that inꢀ
clude the exocyclic double bond linked to the pyrrole ring
and the catalytically active metals Pd and Co. Metal
monomers of this type were studied in radical copolymerꢀ
ization with styrene, and the resulting products are cataꢀ
lysts of anthracene photooxidation with air oxygen to anꢀ
thracene endoꢀperoxide.
cyanines find wide use as sensors, catalysts, and photoꢀ
catalysts in organic synthesis.2 Metalꢀcontaining porphyꢀ
rin derivatives can be synthesized by the reactions of metal
salts with porphyrinꢀcontaining polymers (polymerꢀanaloꢀ
gous transformations) and by polycondensation and coꢀ
polymerization of porphyrinꢀcontaining monomers. In the
latter case, both the vinylporphyrin itself and its metal
complexes are of interest as comonomers in radical copoꢀ
lymerization with traditional monomers (styrene, methyl
methacrylate, acrylonitrile, acrylamide, etc.). This method
has been described recently for the polymerization of
vinylporphyrin monomers of copper and zinc3,4 and the
(acryloyloxyphenyl)amide complexes of zinc5,6 and some
other metals.7 However, this method is used in practice
rather rarely, mainly because convenient methods for the
syntheses of the initial vinylporphyrins and their metal
complexes are lacking. Two ways for the solution of this
problem are known7: synthesis of porphyrins and metal
porphyrins containing the vinyl group in the pyrrole or
Results and Discussion
The palladium complex with 2ꢀvinylꢀ5,10,15,20ꢀ
tetraphenylporphyrin (1) was synthesized by the Wittig
reaction of the palladium 2ꢀformylꢀ5,10,15,20ꢀtetraꢀ
* For Part 63, see Ref. 1.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 152—158, January, 2007.
1066ꢀ5285/07/5601ꢀ0160 © 2007 Springer Science+Business Media, Inc.

Palladium and cobalt vinylporphyrin complexes
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 1, January, 2007
161
phenylporphyrin complex (2) with triphenylmethyleneꢀ
phosphorane generated from triphenylmethylphosphoꢀ
nium iodide by the potassium carbonate complex with
crown ether 18ꢀcrownꢀ6 in boiling methanol. The cobalt
complex with 2ꢀvinylꢀ5,10,15,20ꢀtetraphenylporphyrin
(3) was synthesized similarly from the cobalt 2ꢀformylꢀ
5,10,15,20ꢀtetraphenylporphyrin complex (4) (method A).
Aldehydes 2 and 4 were synthesized by the Vilsmeier
formylation of the palladium (5) and cobalt (6)
5,10,15,20ꢀtetraphenylporphyrin complexes, respectively.
containing no metal vinylporphyrin 1. When a metal is
introduced into the coordination cavity of vinylporphyrin
10 according to this method, a πꢀcomplex with the pallaꢀ
dium salt containing the double bond of the vinyl group is
formed in parallel and undergoes further transformations.
It is known that the alkene complexes with the palladium
salts are rather reactive. In particular, they are oxidized
with air oxygen and alkylate aromatic compounds. It
can be assumed that attempts of direct introduction of
Pd atoms into vinylporphyrin 10 give the palladium comꢀ
plexes with the products of oxidation of the vinyl group,
alkylation of the phenyl cycle adjacent to the vinyl group,
another porphyrin molecule, another solvent molecule,
and also products of other reactions.
Unlike the porphyrin containing one vinyl group in
the benzene ring of 5ꢀ(4ꢀvinylporphyrin)ꢀ10,15,20ꢀtriꢀ
phenylporphyrin, whose structure has been determined3
by Xꢀray diffraction analysis, we failed to grow crystals of
1, 3, and 10 appropriate for Xꢀray study. Therefore, the
structures of these products were determined by IR specꢀ
troscopy, NMR, and mass spectrometry. The main charꢀ
acteristics of synthesized 2ꢀvinylꢀ5,10,15,20ꢀtetraphenylꢀ
porphyrin and its complexes with palladium and cobalt
are given in Tables 1 and 2.
Alternatively, cobalt complex 3 was synthesized
through consecutive transformations via method B. The
copper complex with 5,10,15,20ꢀtetraphenylporphyrin (7)
was formylated according to Vilsmeier,7 and the deꢀ
metallation of the resulting copper 2ꢀformylꢀ5,10,15,20ꢀ
tetraphenylporphyrin complex (8) via the known proceꢀ
dure8 afforded 2ꢀformylꢀ5,10,15,20ꢀtetraphenylporphyrin
(9). The latter was transformed by the Wittig reaction9
into 2ꢀvinylꢀ5,10,15,20ꢀtetraphenylporphyrin (10) under
the conditions close to those described3 for the synthesis
of the copper complex with (2ꢀvinylꢀ5,10,15,20ꢀtetraꢀ
phenyl)porphyrin (11). Vinylporphyrin 10 has been synꢀ
thesized earlier10 as an intermediate product during
the study of transformations in the reaction of the
zinc 5,10,15,20ꢀtetraphenylporphyrin complex (12) with
methyl diazoacetate. As in the procedure described, the
method proposed for the synthesis of vinylporphyrin 10 is
also threeꢀstep but provides the higher yields of both tarꢀ
get vinylporphyrin 10 and intermediate porphyrins 8 and 9.
Unlike the method10 in which methyl diazoacetate and
lithium borohydride were used, we applied more safe and
available reagents ([Ph3PMe]I, PhLi]). Meanwhile, inꢀ
termediate porphyrins (7, 9) are more stable, can easily be
isolated and purified, and are more workable than vinylꢀ
porphyrin 10. The reaction of free base vinylporphyrin 10
with cobalt acetate in a chloroform—acetic acid mixture
afforded cobalt complex 3. The first route for the syntheꢀ
sis of vinylporphyrin including the Wittig olefination of
aldehyde 4 is more preferential than the alternative synꢀ
thesis from complex 7, because it requires less time, is
shorter by one step, and, which is the main, yields target
compound 3 by 18—20% more. The reaction of free
base 10 with palladium salts affords mixtures of products
1
The Н NMR spectra exhibit multiplets from aroꢀ
matic pyrrolic protons at δ 8.88—8.68 and two multiplets
from the Ph protons at δ 8.21—8.03 and 7.84—7.66. The
vinylic protons are observed at δ 6.42 (ddd, Hf), 5.82 (dd),
and 5.09 (dd). Quantification of the spectra shows
30 protons of the following types: seven protons Hd, Hd´,
Hd″, and He; eight protons Hc and Hc´; four protons Ha
and Ha´; eight protons Hb and Hb´; one protons Hf; one
proton Hh; and one proton Hg. The spinꢀspin coupling
constant values of the vinylic protons of compounds 1
and 10 differ by 0.1—0.5 Hz. The spectrum of unꢀ
substituted vinylporphyrin 10 contains two more protons
from the NH groups. As known,11 due to magnetic screenꢀ
ing of the protons arranged inside the cycle (N—H proꢀ
tons), their signal in the 1Н NMR spectrum undergoes an
Table 1. Elemental compositions and molecular ions of syntheꢀ
sized compounds 1, 3, and 10
Comꢀ
poꢀ
und
Found
Calculated
Molecular
formula
[M]+,
found
calculated
(%)
.
C
H
N
M
1
73.22* 3.88* 6.92* 14.35* C46H30N4Pd 745
72.88 3.55 6.42 13.91
745.19
3
79.19 4.30 8.03 8.46 C46H30CoN4 697
78.88 3.90 7.55 8.99
697.7
10
86.25 5.00 8.75
86.96 5.11 8.01
—
C46H32N4
640
640.79
* Average of several independent parallel determinations.

162
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 1, January, 2007
Berezovskii et al.
Table 2. Spectral characteristics of synthesized compounds 1, 3, and 10
Comꢀ
pound
1Н NMR (CDCl3),
IR spectrum,
UV—Vis spectrum
(DMF), λ/nm (logε)
δ (J/Hz)
ν/cm–1
1
8.88—8.68 (m, 7 H, Hd, Hd´, Hd″, pyrrole);
8.21—8.03 (m, 8 H, Hc, Hc´, Ph); 7.84—7.66 (m,
12 H, Ha, Ha´, Hb, Hb´, Ph); 6.42 (dd, 1 H,
Hf, CH=CH2, J = 1.0, J = 10.8, J = 17.1);
5.82 (d, 1 H, Hh, CH=CH2, J = 2.0, J = 17.1);
5.09 (d, 1 H, Hg, CH=CH2, J = 2.4, J = 10.8)
—
700, 715, 750, 795 (δ, benzene ring +
pyrrole); 910 (δ(=СН2)); 980, 1010, 1070,
1175, 1350, 1440 (δ(ССН) + ν(C—C),
benzene ring); 1485 (ν(C=C—C=N),
pyrrole); 1595 (ν(СС) + δ(ССН),
benzene ring)
700, 720, 750, 792 (δ, benzene ring +
pyrrole); 905 (δ(=СН2)); 995, 1000 (ССН,
benzene ring); 1070, 1175, 1350, 1345,
1440 (ν(СС) + δ(ССН), benzene ring);
1487 (ν(C=C—C=N), pyrrole);
418 (5.53),
527 (4.71)
3
421 (5.22),
538 (4.54)
1595 (ν(СС) + δ(ССН), benzene ring)
698, 730, 760, 795 (δ, benzene ring +
pyrrole); 985 (δ(=СН2)); 998 (ССН); 1065
(benzene ring); 1170, 1345, 1440,
1465 (ν(СС) + δ(ССН), benzene ring);
10
8.90—8.69 (m, 7 H, Hd, Hd´, Hd″, pyrrole);
8.21—8.03 (m, 8 H, Hc, Hc´, Ph); 7.81—7.21 (m,
12 H, Ha, Ha´, Hb, Hb´, Ph); 6.44 (dd, 1 H, Hf,
CH=CH2, J = 0.5, J = 10.5, J = 17.0); 5.95 (d,
427 (5.48),
526 (4.59)
1 H, Hh, CH=CH2, J = 1.8, J = 17.2); 5.18 (d, 1 H, 1487 (ν(C=C—C=N), pyrrole);
Hg, CH=CH2, J = 1.7, J = 10.7); –2.7 (s, 2 H, NH) 1595 (ν(СС) + δ(ССН), benzene ring)
upfield shift by 11 ppm. For instance, the chemical shifts
of protons of the N—H groups in the porphyrin and
ethylporphyrin are –3.76 and –3.34 ppm, respectively. In
the case of vinylporphyrin 10, this shift is –2.7 ppm. Note
that their integral intensity corresponds to 1.92 protons,
probably, due to the deuterioexchange that occurs with
the solvent (CDCl3).
In the IR spectra of compounds 1, 3, and 10, we could
not detect the band of stretching vibrations of the С=С
bond in the characteristic region of 1650—1630 cm–1
.
This is caused by both the low molar absorption coeffiꢀ
cient of this nonpolar bond and the low relative content
of vinyl groups compared to other atomic groups of the
macrocyclic ligand. Certain hindrance can also be creꢀ
ated by water traces, because the band of bending vibraꢀ
tions of the Н2О molecule lies in the region of stretching
vibrations of the С=С bond. However, the presence of
the vinyl group in compounds 1, 3, and 10 is indicated by
the band at 900 cm–1 assigned to the δ(ССН) bending
vibrations of the С=СН2 group. The assignment of this
band to vibrations of the vinyl group is favored by its
absence in the spectrum of the cobalt complex with
tetraphenylporphyrin. The shape of the broad band at
900 cm–1 in the IR spectra of the compounds under study
differs substantially from those of other absorption bands
with a small width and the Lorentz contour, which is
characteristic of the spectra of molecular crystals. The
broadening of the band of the vinyl group can be caused
by conformational polymorphism due to rotation about
the C—C bond connecting this group with the porphyrin
macrocycle and to superposition of the absorption bands
of several rotamers stabilized by the intermolecular interꢀ
action in the crystal lattice. As can be seen from the data
in Table 2, metal incorporation into the macrocycle cavꢀ
ity exerts virtually no effect on vibrational frequencies of
the groups arranged at the periphery of the Ph rings. This
can be related to the shift of the Ph rings from the conjuꢀ
gation plane in the system of pyrrole rings, which has
been found12 by Xꢀray diffraction analysis. At the same
time, complex formation increases the vibrational freꢀ
The electronic spectra of all samples contain the inꢀ
tense Soret band at λ = 418 (for palladium derivative 1)
and 421 nm (for cobalt complex 3) and the Q band with a
considerably lower intensity at λ = 527 (1) and 538 nm (3).
For vinylporphyrin 10 containing no metal, these bands
are observed at λ = 427 and 526 nm, respectively.

Palladium and cobalt vinylporphyrin complexes
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 1, January, 2007
163
α
quencies of the system of the conjugated C=C—C=N
πꢀbonds in the pyrrole cycles by 20—25 cm–1 (see Table 2).
This is probably caused by the elimination of lone elecꢀ
tron pairs of the N atoms from the nonbonding orbitals of
the pyrrole cycles due to their interaction with the metal
atom and formation of the M—N bond.
All mass spectra contain peaks of molecular ions as
the major peaks and a series of lowꢀintensity impurity
peaks, which is caused by a higher sensitivity of the method
to the substances under study; some samples were anaꢀ
lyzed using the consecutive connection of two mass specꢀ
trometers (МS/MS).
1´
2´
4
0.6
3´
3
0.4
0.2
1
2
0
100
200
300
t/min
Copolymerization of styrene with monomers 1, 3,
and 10. The rate of copolymerization of vinylporphyrin
monomers 1, 3, and 10 and the molecularꢀweight characꢀ
teristics are lower compared to those for styrene homoꢀ
polymerization (Table 3). The palladium content in the
copolymer depends on the composition of the monoꢀ
meric mixture and ranges from 0.1 to 1.0 mol.%. Note
that vinylporphyrin 10 containing no metal induces inhiꢀ
bition of styrene polymerization to a less extent than palꢀ
ladium complex 1 does (Fig. 1).
Fig. 1. Kinetic curves of styrene copolymerization with comꢀ
pounds 1 (1—3) and 10 (1´—3´) at the concentration of
the vinylporphyrin copolymers 0.1 (1, 1´), 0.5 (2, 2´), and
1.0 wt.% (3, 3´); 4, styrene homopolymerization. Copolymerꢀ
ization conditions: Т = 70 °C, 0.6 wt.% AIBN, in block; α is
conversion.
α
3´
0.8
The UV spectra of the monomeric and polymeric palꢀ
ladium complexes are indiscernible, indicating no interꢀ
action between the porphyrin subunits with each other in
solution.4
With an increase in the initiator concentration (Fig. 2),
the copolymerization rate of both comonomers 1 and 10
increases.
2´
3
0.6
0.4
0.2
1´
2
1
The average numerical molecular weight of the coꢀ
polymers decreases with an increase in the fraction of
comonomers 1 and 10 in a monomeric mixture and with
an increase in the initiator concentration (Table 4).
Comparison of the kinetic data and molecularꢀweight
distribution of the synthesized copolymers with vinylꢀ
porphyrin monomers 1 and 10 suggests some mechanistic
features of chain termination in these polymerized sysꢀ
tems. It is most probable that incorporation of the
vinylporphyrin unit into the growing chain produces
monomolecular pseudoꢀtermination: the macroradical
with the terminal porphyrin unit is stabilized due to conꢀ
jugation with the electronic system of the porphyrin cycle.
0
100
200
t/min
Fig. 2. Kinetic curves of styrene copolymerization with comꢀ
pounds 1 (1—3) and 10 (1´—3´) at the AIBN concentraꢀ
tion 1.0 (1, 1´), 1.5 (2, 2´), and 2.0 wt.% (3, 3´). Copolymerizaꢀ
tion conditions: T = 70 °С, in block, content of compounds 1
and 10 in the monomeric mixture 0.1 mol.%; α is conversion.
A similar phenomenon has been observed earlier for styꢀ
rene copolymerization with the CuII and CoII complexes
containing pyrrolylmethyleneiminopropene13 and for coꢀ
polymerization of the copper and zinc vinylporphyrins
Table 3. Molecularꢀweight distribution of the styrene copolymers with compounds 1 and 10 with a varied amount of
comonomers 1 and 10 in the comonomer mixture*
C
1
10
(mol.%)
Mn
Mw
Mz
Mw/Mn Mz/Mw
Mn
Mw
Mz
Mw/Mn Mz/Mw
0
81000
64000
43000
7300
329000
360000
202000
34600
840000
946000
1000000
1000000
4.06
5.63
4.71
4.75
10.38
2.63
2.29
2.90
81000
40400
15250
8400
329000
363000 1800000
56000
23000
840000
4.06
8.99
3.67
2.74
2.56
4.96
8.11
4.13
0.1
0.5
1.0
454000
95000
* Copolymerization conditions: Т = 70 °С, AIBN (0.5%), in block.

164
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 1, January, 2007
Berezovskii et al.
Table 4. Molecularꢀweight distribution of the styrene copolymers with compounds 1 and 10 with a varied initiator amount*
CAIBN
1
10
(wt.%)
Mn
Mw
Mz
Mw/Mn Mz/Mn
Mn
Mw
Mz
Mw/Mn Mz/Mn
0.1 (PPꢀ11)
0.6
1.0 (PPꢀ15)
1.5
106000
—
84000
30000
24000
416000
—
252000
131000
93600
790000
—
461000
387000
288000
3.92
—
3.00
4.36
3.90
1.9
—
3.03
2.95
2.86
—
—
—
—
—
40400
36500
29400
23200
363000
316000
247000
196000
1800000
1951000
1454000
1414000
8.99
8.66
8.40
8.45
4.96
6.17
5.89
7.21
2.0 (PPꢀ19)
* Conditions: Т = 70 °С, concentration of the comonomer in the comonomer mixture 0.1 mol.%.
with styrene and methyl methacrylate.4 Using the known
equation
catalyze photochemical reactions is well known. They
produce transformation of a dioxygen molecule into the
lowest excited singlet state ∆g due to quenching of their
1
lowest excited electron states by dioxygen in organic solꢀ
vents (see, e.g., Ref. 15). In turn, singlet oxygen is an
active oxidizing agent capable of interacting, in particuꢀ
lar, with condensed hydrocarbons, for example, with anꢀ
thracene, to form 1,4ꢀaddition products.16
Although processes of quenching by molecular oxygen
of the excited electronic states of metal porphyrin comꢀ
plexes of different metals have been studied in rather deꢀ
tail, the properties of monomeric and polymeric comꢀ
plexes 1, 3, and 10 in the photosensibilized generation
of 1О2 have not been studied earlier.
–
–
(P 0 and P n are the average degrees of polymerization in
the absence and presence of restriction agents, respecꢀ
tively; Cporph is the concentration of the vinylporphyrin
monomer; Cs = kt/kgr, kgr, and kt are the rate constnts of
chain growth and termination), we can conclude that
vinylporphyrin 10 containing no metal is a more efficient
chainꢀtransfer carrier to the monomer (Cs = 11.2•10–3
than Pdꢀcontaining complex 1 (Cs = 7.3•10–3).
)
Styrene polymerization in the presence of cobalt comꢀ
plex 3 differs basically from polymerization in the presꢀ
ence of palladium complex 1 by both the kinetics of the
process and the structure and molecular weight of the
polymerization products, which is related to phenomena
of catalytic chain transfer and catalytic inhibition.14 Omitꢀ
ting detailed kinetic analysis, we would like to mention
that the sharp decrease in the molecular weight of the
polymerization products with an increase in the content
of compound 3 favors catalytic chain transfer. For inꢀ
stance, for the content of 1 mol.% compound 3 in the
comonomeric mixture (0.5 wt.% AIBN, Т = 70 °С), the
degree of polymerization (in essence, oligomerization) of
styrene is only 4—5 (Mn = 420, Mw = 520, Mz = 680,
Mw/Mn = 1.23, Mz/Mw = 1.30). The resulting oligomers
(Рn) have the structure H—(CH2—CHPh)n—CH=CHPh.
The presence of the terminal С=С bonds indicates
that the catalysis of chain transfer to the monomer (M)
proceeds through H atom abstraction from the methylene
group of the growing macroradical by the metal complex
(CoL) via the "pingꢀpong" mechanism with a change in
The absorption spectra of a system 1—anthracene
upon irradiation with the light of the wavelength λ =
300—400 nm are shown in Fig. 3 as an example. As can be
seen, the exciting light is absorbed by anthracene only,
the absorbance of complex 1 remains unchanged during
irradiation, and the absorption intensity at 300—400 nm
decreases without changing the spectral shape. Similar
absorption spectra are observed for a 10—anthracene sysꢀ
tem. The rate of decreasing the anthracene concentration
(C/mol L–1 s–1) during irradiation was determined by a
change in the absorbance in the absorption maximum of
the most intense band at λ = 349 nm using the formula
V = ∆C/∆τ. The changes observed in the absorption specꢀ
tra are related to the oxidation of anthracene to form its
endoꢀperoxide, which absorbs the light in the region of
λ < 300 nm. After absorption of a photon, molecules 1
and 10 are transformed into the triplet state due to interꢀ
system crossing, and the triplet state is quenched by disꢀ
solved air oxygen.17—19 As a result, an excited molecule of
singlet dioxygen and a molecule of 1 or 10 in the ground
state are formed. The appeared singlet dioxygen reacts
(k is the rate constant of this reaction) with anthracene to
form anthracene endoꢀperoxide or deactivates (Scheme 2).
The oxidation rates of anthracene by air oxygen and
quantum yields (ΦА) in the presence of the monomeric
and polymeric palladiumꢀcontaining porphyrin complexes
and their analogs free of metal are presented in Tables 5
and 6. As can be seen from the data in Table 5, the
specific rates of anthracene oxidation (rates based on the
the valent state CoII
CoIII according to Scheme 1.
Scheme 1
H—(CH2—CHPh)n—CH2—HPhC• + CoL
M + HCoL R + CoL
Pn + HCoL
Photooxidation of anthracene by compounds 1, 3,
and 10. The ability of porphyrins and metal porphyrins to

Palladium and cobalt vinylporphyrin complexes
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 1, January, 2007
165
A
into account that the isolation of the polymeric catalyst
from the reaction mixture is rather simple and the catalyst
can repeatedly be used (unique feature of the polymerꢀ
immobilized catalyst20), we can see its obvious advanꢀ
tages. No oxidation of anthracene occurs in the presence
of polystyrene, which is the major component of the coꢀ
polymers, and complex 3. The cobaltꢀcontaining vinylꢀ
porphyrin complex decomposes only with a rate of 9.2%
during 5 min (DRShꢀ1000 lamp, ZhSꢀ18 filter).
a
2
3
1
4
400
500
600
λ/nm
A
Experimental
Triphenylmethylphosphonium iodide was synthesized as deꢀ
scribed earlier.3 References to the preparation of the earlier
synthesized porphyrins (2, 4—9) are given in Results and Disꢀ
cussion.
b
2
3
Palladium 2ꢀvinylꢀ5,10,15,20ꢀtetraphenylporphyrinate (1).
A mixture of aldehyde 2 (0.5 g, 0.669 mmol), triphenylꢀ
methylphosphonium iodide (1.893 g, 4.683 mmol), potassium
carbonate (1.11 g, 8.028 mmol), and 18ꢀcrownꢀ6 (25 mg) in
anhydrous benzene (100 mL) was refluxed for 18 h under argon
and then cooled and filtered through a layer of Al2O3 (III activꢀ
ity grade, 3 cm). The filtrate was concentrated to a saturated
solution, which was chromatographed on a column with silica
gel (2.5×40 cm) using benzene as the eluent. The fractions conꢀ
taining vinylporphyrin 1 were combined and evaporated to dryꢀ
ness, and the residue was crystallized from a CHCl3—MeOH
(1 : 3) mixture. The yield was 0.389 g (78%).
1
4
400
500
600
λ/nm
Fig. 3. Electronic absorption spectra of the reaction mixtures for
anthracene (A) oxidation in the presence of compound 1 (a) and
the copolymer of compound 1 with styrene PPꢀ15 (b). Condiꢀ
tions: solvent CHCl3, concentration of compound 1 — 1•10–5
mol L–1 (a) and 2.7•10–4 mol L–1 (b), СA = 1.46•10–5 mol L–1
(DRShꢀ1000, ZhSꢀ12), reaction duration (a): 0 (1), 2 (2), 5 (3),
and 10 min (4); (b): 0 (1), 5 (2), 10 (3), and 15 min (4).
Cobalt 2ꢀvinylꢀ5,10,15,20ꢀtetraphenylporphyrinate (3).
A. Complex 3 was synthesized similarly to palladium complex 1
for 10 h in a yield of 0.351 g (75%) from aldehyde 4 (0.469 g,
0.669 mmol), triphenylmethylphosphonium iodide (1.893 g,
4.683 mmol), potassium carbonate (1.11 g, 8.028 mmol), and
18ꢀcrownꢀ6 (25 mg) in anhydrous benzene (70 mL).
Scheme 2
B. A solution of cobalt(II) acetate (0.237 g, 0.95 mmol) in
acetic acid (25 mL) was added with stirring to a solution of free
base 10 (0.5 g, 0.778 mmol) in chloroform (50 mL). The resultꢀ
ing mixture was refluxed for 30 min, cooled, and washed with
water (3×50 mL). The chloroformic solution of complex 3 was
concentrated to a volume of 15 mL, and boiling methanol
(45 mL) was added. Evaporation was continued until a precipiꢀ
tate began to form, and then the reaction mixture was cooled
PdII concentration) and the quantum yields of the reacꢀ
tion in the presence of metalꢀpolymeric systems and their
analogs free of metal are comparable. However, taking
Table 5. Kinetic parameters of the photooxidation of anthracene (1.46•10–4 mol L–1) in chloroform in the
presence of compound 10, polystyrene (PS), and copolymers of compound 10 with styrene (PP)
c
d
Comꢀ
pound
[10]•106
/mol L–1
Сa•105
/g mL–1
vb = (∆С/∆τ)•108
wsp •102
Φ
•102
А
/mol L–1 s–1
/mol L–1 s–1 (mol of 10)–1
10
PS
3.7
—
—
2.9
7.49
—
2.02
0.33
—
PPꢀ1
PPꢀ2
PPꢀ3
3.01
2.01
1.15
3.8
5.2
14.5
5.06
3.36
1.95
1.33
0.65
1.34
0.27
0.27
0.27
a Copolymer concentration.
b Reaction rate.
c Specific rate.
d Quantum yield of the reaction.

166
Russ.Chem.Bull., Int.Ed., Vol. 56, No. 1, January, 2007
Berezovskii et al.
Table 6. Kinetic parameters of the photooxidation of anthracene (1.46•10–4 mol L–1) in chloroform in the
presence of compound 1 and its copolymers with styrene (PP)
c
d
Comꢀ
pound
[Pd]•105
/mol L–1
Сa•104
/g mL–1
vb = (∆С/∆τ)•107
wsp •102
Φ
•102
А
/mol L–1 s–1
/mol L–1 s–1 (mol of Pd)–1
1
1.0
—
1.39
0.60
0.47
0.39
1.39
1.40
1.74
1.63
0.19
0.18
0.22
2.00
PPꢀ11
PPꢀ15
PPꢀ19
0.43
0.27
0.24
2.16
2.61
2.70
a Copolymer concentration.
b Reaction rate.
c Specific rate.
d Quantum yield of the reaction.
down. The precipitate that formed was filtered off, washed with
methanol, water, and methanol again, and dried at 110 °С. The
yield was 0.523 g (96%).
tronic absorption spectra were recorded on a GenesysTM 2 inꢀ
strument.
Quantum yields of anthracene photooxidation (Φ ) in the
А
Electronic absorption spectra were recorded on
Perkin—Elmer Lambda 2 and Specord Mꢀ40 spectrophotometers
presence of the catalysts (vinylporphyrin and its monomeric and
polymeric metal complexes) were determined as the ratio of the
number of anthracene molecules oxidized at the initial moments
(calculated from the linear region of the kinetic curves) to the
number of photons absorbed by the catalyst during this time.
1
(solvent DMF, concentration 10–6—10–4 mol L–1). H NMR
spectra were obtained on a DPXꢀ200 NMR FTꢀIR spectrometer
in CDCl3 at room temperature (internal standard Me4Si). Mass
spectra were measured on a Varian MAT CHꢀ5 instrument.
TLC analysis was carried out on Silufol plates for free bases and
on Silufol UVꢀ254 plates in the case of the complexes. For
column chromatography Al2O3 (III activity grade) and silica gel
L 40/100 were used.
The authors are grateful to Dr. Thomas Dülks
(Universität Bremen, Germany) for recording mass specꢀ
tra with chemical ionization on a Finnigan MAT 8200
instrument (reagent gas NH3) and with electrospray
ionization on a Bruker EsquireꢀLC instrument, A. B.
Sol´ev´eva for helpful discussions, and A. I. Kuzaev for
analysis of the molecularꢀweight characteristics of the coꢀ
polymers.
Copolymerization of vinylporphyrins 1, 3, and 10 with styꢀ
rene was conducted in the bulk. Styrene was preꢀwashed from
the stabilizer with an alcoholic solution of KOH, dried above
anhydrous CaCl2, and distilled in vacuo. The concentration raꢀ
tios of the monomers were determined by the low solubility of
the palladium or cobalt complexes and 2ꢀvinylꢀ5,10,15,20ꢀ
tetraphenylporphyrin in styrene (bulk polymerization) and
ranged from 0.1 to 1 wt.%. Azobisisobutyronitrile (AIBN) in the
amount from 0.5 to 2 wt.% of the sum of monomers was used
as the initiator. The kinetics of copolymerization (70 °С) was
monitored by calorimetry. The copolymer that formed (after
300—400 min) was precipitated, multiply washed with EtOH,
dried until a constant weight was achieved, and analyzed. The
metal content was determined by the atomic absorption method
on a Saturn instrument. The composition of copolymers conꢀ
taining no metal was calculated from the nitrogen content.
IR spectra were recorded on Specord IRꢀ75 and
Perkin—Elmer Spektrum 1000 instruments (KBr pellets).
Molecularꢀweight characteristics of copolymers were deꢀ
termined by gel permeation chromatography in THF on a
Watersꢀ200 instrument equipped with styrogel columns with difꢀ
ferent exposure limits.
The photooxidation of anthracene was carried out in a
chloroformic solution by air oxygen in a glass cell (l = 1 cm)
upon irradiation with the light from a DRShꢀ1000 mercury lamp
equipped with a water filter and the corresponding glass light
filters (without additional oxygen purging) according to earꢀ
lier17—19 described procedures. The incident light intensity was
measured on an IMOꢀ2 power meter. The oxidation kinetics
was monitored by a change in the anthracene concentration,
which was determined by a decrease in the absorbance of
the absorption bands of anthracene at 300—400 nm. Elecꢀ
This work was financially supported by the Russian
Foundation for Basic Research (Project No. 04ꢀ03ꢀ
32634).
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Received October 24, 2006;
in revised form December 14, 2006