Site-isolated porphyrin catalysts in imprinted polymers

Article abstract of DOI:10.1002/chem.200500375

A meso-tetraaryl ruthenium porphyrin complex having four polymerizable vinylbenzoxy groups (2) has been synthesized by reaction of pyrrole with 4-(vinylbenzoxy)benzaldehyde and subsequent metalation with [Ru ₃(CO)₁₂]. The porphyrin complex was immobilized by copolymerization with ethylene glycol dimethacrylate. The resulting polymer P2 was found to catalyze the oxidation of alcohols and alkanes with 2,6-dichloropyridine N-oxide without activation by mineral acids. Under similar conditions, the homogeneous catalyst 2 was completely inefficient. By using diphenylaminomethane and 1-aminoadamantane as coordinatively bound templates during the polymerization procedure, the molecularly imprinted polymers P3 and P4 have been synthesized. Compared with the polymer P2, the imprinted catalysts displayed a significantly increased activity with rate enhancements of up to a factor of 16.

Full text of DOI:10.1002/chem.200500375

FULL PAPER
Site-Isolated Porphyrin Catalysts in Imprinted Polymers
Estelle Burri, Margarita Öhm, Corinne Daguenet, and Kay Severin*[a]
Abstract: A meso-tetraaryl ruthenium
porphyrin complex having four poly-
merizable vinylbenzoxy groups (2) has
been synthesized by reaction of pyrrole
catalyze the oxidation of alcohols and
alkanes with 2,6-dichloropyridine N-
oxide without activation by mineral
acids. Under similar conditions, the ho-
mogeneous catalyst 2 was completely
inefficient. By using diphenylamino-
methane and 1-aminoadamantane as
coordinatively bound templates during
the polymerization procedure, the mo-
lecularly imprinted polymers P3 and
P4 have been synthesized. Compared
with the polymer P2, the imprinted cat-
with
4-(vinylbenzoxy)benzaldehyde
and subsequent metalation with
[Ru3(CO)12]. The porphyrin complex
was immobilized by copolymerization
with ethylene glycol dimethacrylate.
The resulting polymer P2 was found to
Keywords: heterogeneous catalysis ·
molecular imprinting · oxidation ·
porphyrin complexes · ruthenium
alysts displayed
a significantly in-
creased activity with rate enhance-
ments of up to a factor of 16.
Introduction
countered in some cases.[9b,10] We have recently reported a
supported Ru–porphyrin catalyst, which was obtained by co-
polymerization of [Ru{meso-tetra(styryl)porphyrin}(CO)]
with an excess of ethylene glycol dimethacrylate
(EGDMA).[13] The resulting mesoporous, highly cross-linked
polymer was found to efficiently catalyze the epoxidation of
olefins as well as the oxidation of alkanes and secondary al-
cohols. Herein, we describe the synthesis of a new EGDMA
copolymer P2, which is based on the ruthenium complex 2
Starting with the pioneering work of Hirobe et al.,[1] rutheni-
um–porphyrin catalysts in conjunction with 2,6-disubstituted
pyridine N-oxides as the oxidant have been widely used for
oxygen-transfer reactions.[2] Recent developments include
the utilization of dendritic ruthenium porphyrins,[3] the ex-
tension to asymmetric reactions using chiral porphyrin com-
plexes,[4] the investigation of new substrates such as alka-
nes[5] or amides,[6] and the utilization of alternative oxidation
agents such as N2O[7] or O2.[8] Generally, Ru–carbonyl com-
plexes of the formula [Ru(por)(CO)] (por=meso-tetra-
(aryl)porphyrin) are used as catalyst precursors. They are
easily accessible from [Ru3(CO)12] and the free-base porphy-
rin. Alternatively, dichloro or dioxo complexes of the formu-
la [Ru(X)2(por)] (X=O, Cl) have been employed.[2]
having
four
polymerizable
4-vinylbenzoxy
groups
(Scheme 1). For the oxidation of secondary alcohols and al-
kanes with 2,6-dichloropyridine N-oxide (Cl2pyNO), this
polymeric catalyst was found to be by far superior to the ho-
mogeneous counterpart. Furthermore, the activity of the
supported catalyst could be increased significantly by using
the technique of molecular imprinting.[14,15]
Immobilized ruthenium–porphyrin catalysts have been
synthesized by encapsulation in mesoporous molecular
sieves[9] or sol–gel silica,[10] by electropolymerization of com-
plexes with fluorene groups,[11] and by covalent attachment
to Merrifield resins.[12] Good catalytic activity was observed
for these systems although problems with leaching were en-
Results and Discussion
In order to obtain the metallomonomer 2, we first synthe-
sized the free-base porphyrin 1 by reaction of pyrrole with
4-(vinylbenzoxy)benzaldehyde in propionic acid under
reflux (Scheme 1).[16] After cooling, the product precipitated
as a purple, microcrystalline material in a 12% yield. Com-
pared to other procedures for the preparation of porphyrin
ligands with polymerizable acrylate[17,18] or styrene[13] side
chains, this new method has the advantage that the required
aldehyde can be easily synthesized from commercially avail-
able starting materials.[19] The porphyrin is then obtained in
[a] E. Burri, M. Öhm, C. Daguenet, Prof. Dr. K. Severin
Institut de Sciences et IngØnierie Chimiques
École Polytechnique FØdØrale de Lausanne (EPFL)
1015 Lausanne (Switzerland)
Fax : (+41)21-693-9305
E-mail: kay.severin@epfl.ch
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DOI: 10.1002/chem.200500375
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of the metallomonomer 2. As
the oxidant, Cl2pyNO was em-
ployed. The results are summar-
ized in Table 1.
For all alcohols that were in-
vestigated, good to excellent
conversions to the correspond-
ing ketones were observed after
6h. Even for the least reactive
substrate, indanol, a quantita-
tive conversion was determined
after 24 h. It is important to
note that for the homogeneous
oxidation of alcohols and alka-
nes with [Ru(por)(CO)] cata-
Scheme 1. Synthesis of the tetraarylporphyrin 1 and its {Ru(CO)} complex 2: a) 1428C, CH3CH2CO2H;
b) 1118C, [Ru3(CO)12], styrene, toluene.
Table 1. Catalytic oxidation of secondary alcohols with the polymeric
a one-step procedure with no chromatographic purification
steps being required.
catalyst P2.[a]
Following a standard procedure,[20] the free-base porphy-
rin 1 was metalated by reaction with [Ru3(CO)12] to give
complex 2 in a 70% yield. An excess of styrene was added
as a “hydrogen scavenger” because previous results had
shown that reduction of the vinyl groups can occur during
the reaction with [Ru3(CO)12].[13] The infrared spectrum of
Substrate
Product
Conversion [%]
>99
91
complex 2 showed a characteristic carbonyl band at nCO
=
1929 cmꢀ1. Compared with the free ligand 1, a hypsochromic
shift of 7.3 nm was found for the Soret band of 2.
91
Complex
2
was subsequently copolymerized with
EGDMA (2/EGDMA=1:400) in the presence of chloro-
form as the porogen (Scheme 2). To initiate the reaction,
2,2’-azobis(isobutyronitrile) (AIBN) was employed. After
24 h, a dark-red polymer (P2) was obtained, which was
80 (99)[b]
89
96
82
[a] The reactions were performed in benzene at 558C with a substrate/
Cl2pyNO/catalyst molar ratio of 200:250:1. The conversion was deter-
mined after 6h by gas chromatography. [b] Conversion after 24 h.
Scheme 2. Synthesis of the polymeric catalyst P2: a) 6 85C, CHCl3,
EGDMA, AIBN.
ground in a mortar. The nearly colorless washing solutions
indicated a quantitative incorporation of the metallomono-
mer 2 in the polymeric EGDMA matrix. A BET surface
area of 409 m2gꢀ1 and an average pore size of 54 Š was de-
termined for P2.[21] These data suggested that the Ru com-
plexes in the interior of the polymeric particles are accessi-
ble for catalytic transformations.
To evaluate the catalytic properties of the polymer P2, we
investigated the oxidation of secondary alcohols at 558C
using 0.5 mol% Ru. The amount of polymer that was re-
quired was calculated based on a quantitative incorporation
lysts, it was reported that the addition of strong mineral
acids such as HCl or HBr was crucial for the success of the
reaction[4d,5e] unless a highly fluorinated[5c] or a sterically
very encumbered porphyrin ligand[5a] was employed. In ac-
cordance with these observations, only a very low yield
(<2%) of ketones was obtained when complex 2 was used
as a homogeneous catalyst instead of the polymer P2 under
otherwise identical conditions. It seems likely that a site-iso-
lation effect is responsible for the significantly increased ac-
tivity of the polymer P2. In fact, it has been reported that
inactive dimeric m-oxo–RuIV complexes may form rather
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Porphyrin Catalysts
FULL PAPER
easily from the catalytically relevant [RuO(por)] and
[Ru(O)2(por)] species.[22,23]
Next we were interested in whether we could improve the
activity and selectivity of the immobilized catalyst by using
the technique of molecular imprinting. The key step of mo-
lecular imprinting with a transition-metal catalyst is the uti-
lization of a pseudosubstrate, which is coordinatively bound
to the active site of the catalyst during the polymerization
procedure.[15] After polymerization, the pseudosubstrate is
selectively cleaved off, thereby generating an imprint (“sub-
strate pocket”) in direct proximity to the active site. So far,
molecular imprinting studies with porphyrin metallomono-
mers have focused on ligand-recognition studies[18] and only
recently a report about a molecularly imprinted hemin cata-
lyst has been published.[24]
For [Ru(por)(CO)] complexes it was known that they
form stable adducts with N-donor ligands.[2a,25] We thus in-
vestigated whether primary amines could be used as pseudo-
substrates. When one equivalent of aminodiphenylmethane
was added to complex 2 in [D6]acetone, the immediate for-
mation of the new complex 3 was observed by 1H NMR
spectroscopy (Figure 1, Scheme 3). For the signal of the pyr-
Scheme 3. Synthesis of the imprinted polymer P3: a) 6 85C, CHCl3,
EGDMA, AIBN; b) CF3CO2H.
ratio) were the same as those used for P2 in order to allow
for a direct evaluation of the imprinting effect. The pseudo-
substrate was cleaved off by washing the polymer with a so-
lution of CF3CO2H in acetone. As the decomplexation step
was fast and quantitative for complex 3 in homogeneous so-
lution, it was expected that the CF3CO2H treatment would
also be effective for the polymer P3. This was indirectly con-
firmed by results of the catalysis experiments as outlined
below.
First, the oxidation of diphenylmethane was investigated,
a substrate which displays a strong structural similarity to
the pseudosubstrate. For both polymeric catalysts, the time
course of the reaction was examined by removing samples
from the reaction mixture, which were analyzed by gas chro-
matography. The imprinted catalyst P3 was found to be sig-
nificantly more active than the nonimprinted polymer P2:
the initial rate, calculated from the conversion of diphenyl-
methane after 6h, was 6.4 times higher for polymer P3 than
for polymer P2 (Figure 2). For both reactions, the main oxi-
dation product was benzophenone with small amounts of di-
phenylmethanol being present, in particular at the beginning
of the reaction. This points to the fact that the reaction pro-
ceeds in two steps and that the alcohol oxidation is consider-
ably faster than the alkane oxidation. A slight induction
period was evident from the time course of the reactions.
This was not unexpected as the {Ru(CO)} complexes are
catalyst precursors from which the catalytically active Ru=O
species are generated by decarbonylation.[2]
Figure 1. Part of the 1H NMR spectrum (400 MHz, [D6]acetone) high-
lighting the signals of the pyrrole-CH groups of a) complex 2, b) complex
2+(0.5 equiv of H2NCHPh2), c) complex 2+(1 equiv of H2NCHPh2),
d) complex 2+(1 equiv of H2NCHPh2)+(0.5 equiv CF3COOH), and
e) complex 2+(1 equiv of H2NCHPh2)+(excess of CF3COOH).
role-CH proton, for example, a shift towards higher field
was observed during the progressive addition of amine to
the ruthenium–porphyrin complex. The complexation of the
amine could be cleanly reversed by addition of trifluoroace-
tic acid (Figure 1). These results suggested that aminodiphe-
nylmethane could indeed be employed to create a substrate
pocket next to the ruthenium center.
The imprinted polymer P3 was synthesized as outlined in
Scheme 3. Addition of one equivalent of aminodiphenyl-
methane to complex 2 gave the adduct 3, which was copoly-
merized with EGDMA using chloroform as the porogen.
The reaction conditions (initiator, temperature, EGDMA
When 2 equivalents of diphenylaminomethane were
added to the reaction mixture, the rates dropped to zero in-
dicating that the amine acts as a catalyst poison. According-
ly, only very low conversions were observed when the im-
printed polymer P3 was not washed with trifluoroacetic acid
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K. Severin et al.
and an analogous explanation can be put forward in the
present case.
Similarly, the nature of the substrate has a pronounced
effect on the relative reaction rates. This is evident when the
results for the oxidation of diphenylmethanol, diphenylme-
thane, and anthracene are compared (Figure 4). All three
Figure 2. Oxidation of diphenylmethane by Cl2pyNO with the nonim-
*
*
printed catalyst P2 ( ) or with the imprinted catalyst P3 ( ). The reac-
tions were performed in benzene at 358C with a substrate/Cl2pyNO/cata-
lyst molar ratio of 100:250:1. The data points represent averaged values
from two independent experiments, the errors are less than 1%.
prior to being used as a catalyst. These results clearly ex-
cluded the possibility that residual pseudosubstrate in the
polymer P3 was responsible for the increased activity. In
order to verify that the difference in activity between P2
and P3 was not due to the washing step with trifluoroacetic
acid, polymer P2 was likewise treated with CF3CO2H/ace-
tone. This treatment, however, had no effect on the catalytic
activity of P2 as evidenced by control experiments with a
second batch of P2, which was exclusively washed with ace-
tone.
The rate enhancement due to molecular imprinting was
found to depend strongly on the reaction temperature and
the nature of the substrate. When the oxidation of diphenyl-
methane was performed at 558C, the difference between the
rates of reactions with the catalysts P2 and P3 was only a
factor of 4.3. When the temperature was lowered to 208C,
on the other hand, the difference increased to a factor of
16.3 (Figure 3). A similar temperature dependence has been
Figure 4. Conversions and rate enhancements for the oxidation of three
different substrates with the imprinted catalyst P3 compared with the
nonimprinted catalyst P2. The reactions were performed in benzene at
358C with a substrate/Cl2pyNO/catalyst molar ratio of a) 1000:1250:1,
values after 1 h, b) 200:500:1, values after 6h, and c) 100:500:1, values
after 6h.
substrates have a size and shape which is related to that of
the pseudosubstrate diphenylaminomethane. For diphenyl-
methanol, however, a rate enhancement due to imprinting
of a factor of 2.5 was observed, whereas factors of 6.4 and
15.7 for the oxidation of diphenylmethane and anthracene,
respectively, were determined. This difference can be ex-
plained by the fact that the oxidation of diphenylmethane
and anthracene requires two- or multiple oxidation steps, re-
spectively. As the imprinting effect will manifest itself in
each step, higher rate enhancements are indeed expected
for diphenylmethane and in particular for anthracene.
To further probe the selectivity of the polymeric catalysts,
we performed competition experiments with equimolar
amounts of two substrates, which undergo the same oxida-
tion step (alcohol!ketone), but which differ in terms of
their size and shape. Previous results with imprinted rutheni-
um catalysts for transfer hydrogenations had shown that mo-
lecular imprinting may result in an increased selectivity for
the substrate, the structure of which most closely resembles
that of the pseudosubstrate.[27] For the imprinted catalyst P3,
however, the rate enhancements relative to P2 were similar
for all alcohol pairs tested. A moderate substrate selectivity
was found when the imprinted polymer P4 was employed.
P4 was generated by using 1-aminoadamantane instead of
aminodiphenylmethane as the pseudosubstrate. In competi-
Figure 3. Rate enhancements for the oxidation of diphenylmethane with
the imprinted catalyst P3 when compared to the nonimprinted catalyst
P2 at three different temperatures. The reactions were performed in ben-
zene with a substrate/Cl2pyNO/catalyst molar ratio of 100:250:1. The rate
enhancements were calculated from the conversions after 6h.
reported for the binding affinities of some molecularly im-
printed polymers;[26] this was attributed to the increased
flexibility of the polymer backbone at higher temperatures,
which reduces the structural integrity of the imprinting site,
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Porphyrin Catalysts
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Table 2. Catalytic oxidation of alkanes with the nonimprinted catalyst P2
and the imprinted catalyst P3.[a]
tion experiments with the substrate pair 2-adamantanol/2-
octanol and the catalyst P2, the two substrates were oxi-
dized with the same rates but in reactions with the imprint-
ed catalyst P4, a clear preference for adamantanol was ob-
served (Figure 5). The selectivity, as calculated from the rel-
Substrate
Product
Conv. [%]
Conv. [%]
P2
P3
48
>99
13
62
7698
49
96
638
12
87
Figure 5. Oxidation of 2-adamantanol (circles) and 2-octanol (triangles)
by Cl2pyNo catalyzed with the nonimprinted catalyst P2 (open symbols)
or the imprinted catalyst P4 (closed symbols). Reaction conditions:
a) benzene, RT, 2-adamantanol/2-octanol/Cl2pyNO/catalyst (molar ratio
100:100:250:1), and 1 mol% P2 or P4. The data points represent aver-
aged values from two independent experiments, the errors are less than
1%.
[a] The reactions were performed in benzene at 558C with a substrate/
Cl2pyNO/catalyst molar ratio of 100:250:1 (100:500:1 for anthracene).
The conversion (conv.) was determined after 24 h by gas chromatogra-
phy.
ative conversion after 4 h,[28] was found to be 1.0 for P2 and
1.4 for P4.
Conclusion
The results indicated that the imprinting procedure had a
strong effect on the catalytic activity of the porphyrin-con-
taining polymers (in particular for substrates which undergo
multiple consecutive oxidation steps) but only a small effect
on the selectivity within the same class of substrates. This
might be due to the fact that the pseudosubstrate was at-
tached to the metallomonomer by a single coordinative
bond. Consequently, the pseudosubstrate had a high confor-
mational flexibility during the imprinting procedure, which
resulted in large but structurally ill-defined substrate pock-
ets. This is in agreement with studies of Spivak et al. which
highlight the importance of multipoint interactions during
the formation of the molecularly imprinted polymer.[29]
Despite the moderate selectivity, the imprinted polymers
show clear advantages in terms of catalytic performance.
This was further substantiated by oxidation reactions with
simple hydrocarbon substrates. Using only 1 mol% of the
imprinted polymer P3 and no activating mineral acid, good
conversions were observed for most substrates investigated
(Table 2). For the nonimprinted polymer P2, on the other
hand, only one substrate—tetralon—displayed a conversion
of more than 50% under similar conditions. As found for
the oxidation of alcohols, negligible conversions of less than
2% were obtained in reactions with the homogeneous cata-
lyst 2.
A ruthenium–porphyrin complex has been incorporated into
a mesoporous, highly cross-linked polymer by copolymeriza-
tion with a large excess of EGDMA. Due to site isolation of
the complexes within the rigid polymeric matrix it was possi-
ble to use the polymer as an efficient catalyst for the oxida-
tion of alcohols and alkanes. This is in sharp contrast to the
corresponding homogeneous catalyst, which was completely
ineffective for these reactions. The utilization of an
EGDMA polymer as the solid support allowed manipula-
tion of the microenvironment of the catalyst by using the
technique of molecular imprinting. It was thus possible to
increase the activity of the catalyst by more than one order
of magnitude by carrying out the polymerization in the pres-
ence of aminodiphenylmethane as a template. This increase
in activity is significant given the fact that the imprinted and
the nonimprinted polymer contain the same amount of
ruthenium complexes with an identical first coordination
sphere. Highly cross-linked organic polymers therefore rep-
resent ideal supports for immobilized Ru–porphyrin cata-
lysts: they not only prevent intermolecular deactivation re-
actions but also allow manipulation of the microenviron-
ment of the catalyst in a controlled fashion. It is conceivable
that future research along these lines may lead to porphyrin
catalysts with an even more defined substrate pocket. This
could be achieved by using secondary interactions (e.g., hy-
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K. Severin et al.
(1.8 mL) in a 6mL screw-cap vial. The vial was closed and heated for
24 h at 658C. The resulting polymer was ground, treated 3 times with a
solution of trifluoroacetic acid in acetone (20 mL, 0.02m), washed with
acetone (3”20 mL), and dried under vacuum. Yield: 1.9 g (>98%). BET
surface area: 357 m2gꢀ1; average pore size: 58 Š.
drogen bonding) between the pseudosubstrate and the poly-
meric matrix. Attempts in this direction are currently being
pursued in our laboratory.
Synthesis of the polymer P4: The synthesis was performed analogous to
that of P3 but using 1-aminoadamantane instead of aminodiphenylme-
thane.
Experimental Section
Catalytic oxidation of alcohols: A suspension/solution of polymer P2/
complex 2 (20.0 mg/0.33 mg, 0.248 mmol Ru) and Cl2pyNO (10.2 mg,
62 mmol) in benzene (1.0 mL) was stirred for 5 min. The reaction was
then started by addition of the substrate (49.6 mmol) and the Schlenk
tube was placed immediately in an oil bath regulated at 558C. Samples
(50 mL) were removed at regular intervals, filtered (or quenched with
pyridine for the homogenous catalysis), and analyzed by GC.
General: All complexes were synthesized under an inert atmosphere of
dinitrogen using standard Schlenk techniques. The solvents (analytical
grade purity) were degassed and stored under a dinitrogen atmosphere.
4-(Vinylbenzoxy)benzaldehyde was synthesized according to the litera-
ture.[19] Ethylene glycol dimethacrylate (EGDMA) was purchased from
Aldrich. It was washed with NaOH (1m) and saturated NaCl solution
and dried with Na2SO4. After filtration, the monomer was distilled under
reduced pressure. AIBN was purchased from Fluka and was re-crystal-
lized from methanol before use. 2,6-Dichloropyridine N-oxide was pur-
chased from Aldrich. Polymerizations were performed in a glovebox con-
taining less than 1 ppm of oxygen and water. The 1H and 13C spectra
were recorded on a Brucker Advance DPX 400 instrument using the re-
sidual protonated solvents as internal standards. The spectra were record-
ed at room temperature. The GC analyses were performed with a Varian
3800 gas chromatograph using a CP-Sil 8 CB column (30 m). The BET
measurements were carried out by Quantachrome GmbH, Odelzhausen,
on a Quantachrome Autosorb-3 instrument. Prior to the measurements,
the samples were dried under vacuum at 1008C for 2 h.
Catalytic oxidation of alkanes: The reactions were performed as de-
scribed for the oxidation of alcohols but 2.5 equivalents of Cl2pyNO
(with respect to the substrate) were added (20.3 mg, 124 mmol).
Acknowledgements
The work was supported by the Swiss National Science Foundation and
by the DFG.
Synthesis of porphyrin 1: To propionic acid (100 mL) at reflux (b.p.
1428C), pyrrole (1.9 mL, 27.3 mmol) and 4-(vinylbenzoxy)benzaldehyde
(6.5 g, 27.3 mmol) were added and stirred for 30 min at reflux. After
cooling, the violet precipitate was filtered off and washed with methanol
(200 mL) and pentane (50 mL) and dried under vacuum. Yield: 920 mg
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1
3
(12%); H NMR (400 MHz, CDCl3): d=ꢀ2.77 (s, 2H; NH), 5.31 (d, J=
3
11 Hz, 4H; CH=CH2), 5.35 (s, 8H, OCH2), 5.83 (d, J=18 Hz, 4H; CH=
CH2), 6.80 (dd, 3J=11, 3J=18 Hz, 4H; CH=CH2), 7.35 (d, 3J=8 Hz, 8H;
RC6H4R’), 7.59 (m, 16H; RC6H4R’), 8.12 (d, 3J=8 Hz, 8H; RC6H4R’),
8.86ppm (s, 8H; pyrrole-H); 13C NMR: not determined due to low solu-
bility; UV/Vis (CHCl3): lmax (e in cm2molꢀ1)=423 (457000), 519 (35000),
551 (28000), 592 (21000), 650 nm (20000); MS (FAB+) m/z: 1143.3
[M]+; elemental analysis calcd (%) for C80H62N4O4 (1143.39): C 84.04,
H 5.47, N 4.90; found: C 84.04, H 5.56, N 4.82.
Synthesis of complex 2: A mixture of toluene (150 mL), porphyrin 1
(400 mg, 0.35 mmol), [Ru3(CO)12] (293 mg, 0.46mmol), and styrene
(4.0 mL, 42.3 mmol) was protected from light and heated to reflux for
48 h. The solvent was evaporated and the product was washed with
hexane and then purified by column chromatography (SiO2; first CHCl3
then CHCl3/THF 99:1). The product was dissolved in a minimal amount
of chloroform and precipitated in hexane. Removal of the solvent and
drying in vacuum yielded the product. Yield: 330 mg (70%); 1H NMR
3
(400 MHz, CDCl3): d=5.32 (br, 12H; OCH2 and CH=CH2), 5.83 (d, J=
18 Hz, 4H; CH=CH2), 6.80 (dd, 3J=11, 3J=18 Hz, 4H; CH=CH2), 7.31
(m, 8H; RC6H4R’), 7.59 (m, 16H; RC6H4R’), 8.12 (m, 8H; RC6H4R’),
8.86ppm (s, 8H; pyrrole-H); 13C NMR (400 MHz, CDCl3): d=70.17,
113.07, 113.10, 114.17, 121.51, 126.47, 127.94, 131.73, 134.72, 135.25,
135.30, 136.47, 137.47, 144.38, 158.06, 181.75 ppm (CO); IR: n˜CO
=
1929 cmꢀ1; UV/Vis (CHCl3): lmax (e in cm2molꢀ1)=415 (229000), 531
(31000), 565 nm (17000); MS (FAB+) m/z: 1270.3 [MꢀTHF]+; elemental
analysis calcd (%) for C81H60N4O5Ru·THF (1342.56): C 76.04, H 5.11, N
4.17; found: C 76.55, H 4.66, N 4.02.
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a solution of complex 2 (48 mg, 35.8 mmol) and AIBN (60 mg,
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Synthesis of the polymer P3: EDGMA (1.8 mL, 9.55 mmol) was added
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5060
ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
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Received: April 4, 2005
Published online: June 24, 2005
Chem. Eur. J. 2005, 11, 5055 – 5061
www.chemeurj.org
ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
5061