Preparation and characterization of RuCl3 - Diamine group functionalized polymer

Article abstract of DOI:10.1016/j.reactfunctpolym.2010.03.003

Gel-type resin with diamine functional groups, FCN, was used as a matrix for immobilization of ruthenium complexes. By reacting of RuCl₃ with swollen matrix of FCN polymer a series of Ru/FCN composites with various Ru loading (1%, 2%, and 4%) w

Full text of DOI:10.1016/j.reactfunctpolym.2010.03.003

Reactive & Functional Polymers 70 (2010) 382–391
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Reactive & Functional Polymers
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Preparation and characterization of RuCl3 – Diamine group functionalized polymer
a
a
a
a
a
D. Duraczynska a, , A. Drelinkiewicz , E.M. Serwicka , D. Rutkowska-Zbik , E. Bielanska , R. Socha ,
*
´
A. Bukowska b, W. Bukowski b
a Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, 30-239 Kraków, Niezapominajek 8, Poland
b Faculty of Chemistry, Rzeszów University of Technology, 35-959 Rzeszów, ul. W. Pola 2, Poland
a r t i c l e i n f o
a b s t r a c t
Article history:
Gel-type resin with diamine functional groups, FCN, was used as a matrix for immobilization of ruthe-
nium complexes. By reacting of RuCl3 with swollen matrix of FCN polymer a series of Ru/FCN composites
with various Ru loading (1%, 2%, and 4%) was prepared. All the characterization techniques (FT-IR, XRD,
SEM, EDS, STEM, XPS, and DSC) proved the participation of functional groups in the coordination of
Ru(III). These complexes contained both Cl- and N-ligands in various proportions depending on ruthe-
nium loading in polymer. Taking into account the chelating character of N-ligands a hypothetical struc-
ture of octahedral Ru(III) complex coordinated to FCN polymer was proposed. 2%Ru/FCN when reduced
by NaBH4 exhibited catalytic activity in liquid phase hydrogenation of acetophenone. Higher selectivity
in the presence of FCN supported Ru as compared to 2%Ru/Al2O3 catalyst toward 1-phenylethanol was
observed.
Received 21 December 2009
Received in revised form 9 March 2010
Accepted 13 March 2010
Available online 18 March 2010
Keywords:
Functional polymer
Ruthenium
Hydrogenation
Acetophenone
Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction
has been observed that specific environment of catalytically active
centers located in the functionalized polymer matrices could influ-
Polymer supported noble metals composites have been used in
a wide range of organic synthetic applications and in heteroge-
neous catalysis [1]. Very prominent and promising catalytic perfor-
mance of Pd, Pt, Rh–polymer composites was observed in
hydrogenation of cyclohexene [2], nitroaromatics [3,4] unsatu-
rated aldehydes and alcohols [5–7], hydrosilylation of alkenes
[8]. Among many conventional carriers such as Al2O3, TiO2, SiO2,
C, and zeolites, polymeric supports offer unique features as poten-
tial carriers. Their hydrophobic/hydrophilic character, the presence
of various functional groups and high ability to stabilize finely dis-
persed metal nanoparticles make polymers very attractive as po-
tential supporting materials [9,10]. As a result of such specific
properties, catalytic centers formed in polymer matrix act in the
environment which essentially differs from that of conventional
inorganic carriers supported noble metal catalysts [10,11]. Litera-
ture data as well as the recent results reported by Drelinkiewicz
et al. [12–16] showed that the presence of polymer matrix exhib-
ited profound role in the activity of Pt, Pd–polymer supported cat-
alysts via an influence of polymer framework on the access of
reagents to the active centers surrounded by polymer chains. In
addition, functional groups of polymer may modify adsorption
properties of catalytically active centers via electron interactions,
especially in the case of finely dispersed metal nano-clusters. It
ence not only the activity but also the selectivity of catalyzed reac-
tion [1,17]. In contrast to the widely studied polymer supported
palladium and platinum catalysts, investigation of catalytic appli-
cation of less expensive Ru/polymer systems is rather limited. Re-
cently, Sanchez-Delago et al. [18] demonstrated that Ru
immobilized on poly(4-vinylpyridine) was found to be an efficient
catalyst for selective hydrogenation of aromatic ring of quinoline
to give 1,2,3,4-tetrahydroquinoline at 30–40 bar H2 and ca.
100 °C. This catalyst (10 wt.% Ru) was prepared by NaBH4 reduc-
tion of RuCl3ꢀxH2O in methanol in the presence of the polymer
[18]. Another study showed that Ru catalysts supported on highly
hydrophilic support, i.e. potassium methacryloyl ethylene sulpho-
nate resin were efficient in partial hydrogenation of benzene to
cyclohexene [19]. Interestingly, they exhibited better selectivity
than Ru/C catalyst. Other Ru catalysts, obtained by reacting of
RuCl3 with chloromethylated styrene–divinyl benzene co-polymer
functionalized by glycine, were found to be effective in the hydro-
genation of nitrobenzene [20].
It has been shown that polymer framework, and, in particular,
functional groups, played a key role in anchoring of Pt and/or Pd-
ions, by facilitating formation of various coordination species act-
ing as precursors of catalytically active centers [1]. In view of this,
understanding the relation between the nature of the polymer and
its bonding mode to noble metal ions is of paramount importance.
This issue constitutes the main goal of present work, in which no-
vel catalysts consisting of ruthenium complexes supported on
* Corresponding author. Tel.: +48 12 6395142; fax: +48 12 4251923.
E-mail address: ncduracz@cyf-kr.edu.pl (D. Duraczynska).
1381-5148/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.reactfunctpolym.2010.03.003

D. Duraczynska et al. / Reactive & Functional Polymers 70 (2010) 382–391
383
several times and dried in air. Then 10-fold excess of NaBH4 solu-
tion in THF:CH3OH (9:1 volume ratio) with respect to Ru was
added and the catalysts were gently stirred till the evolving of
gas bubbles was no longer observed. The resulting black Ru–poly-
mer beads were filtered, washed several times with acetone and
dried in air.
P
2
Scheme 1. The structure of FCN resin.
2.3. Preparation of Ru/Al2O3 catalyst
functionalized gel-type resin (FCN), shown in Scheme 1, were de-
signed and prepared. In the earlier study performed by Drel-
inkiewicz et al. [14] this polymer served as support immobilizing
coordinatively bonded palladium species. The successful applica-
tion of Pd/FCN catalyst in the hydrogenation of phenylacetylene
and 2-butyne-1,4-diol prompted us to apply FCN resin as potential
supporting matrix for ruthenium.
In order to elucidate the nature of interactions between the
functional groups of FCN polymer, e.g. C@O, NH, NH2 (see Scheme
1) and RuCl3 during the incorporation of ruthenium into the FCN
polymer, a series of Ru/FCN composites with various content of
ruthenium (1 wt.%, 2 wt.%, and 4 wt.%) were prepared and charac-
terized by FT-IR, XRD, SEM, STEM, EDS, XPS, and DSC techniques.
Catalytic properties of 2%Ru/FCN composite were evaluated in
hydrogenation of acetophenone. This reaction was chosen as a
model reaction because ruthenium catalysts are known to be
highly selective in hydrogenation of carbonyl group in the vicinity
of isolated, conjugated and aromatic double bonds [21–24].
Ruthenium was incorporated into
c-Al2O3 carrier (BET surface
area 155 m2/g, particles ca. 100
l
m in size) by means of impregna-
tion method. Prior to ruthenium incorporation, Al2O3 support was
dried overnight in the oven at 150 °C. Then RuCl3 aqueous solution
(0.06 mol/dm3) was added (38 cm3 to 10 g of dried and cooled
Al2O3) and the obtained mixture was vigorously stirred on water
bath (ꢁ90 °C) until evaporation to dryness. The resulting black so-
lid was dried overnight at 150 °C. Reduction was performed using
10-fold excess of NaBH4 solution in THF:CH3OH (9:1 volume ratio).
When the evolving of gas bubbles was no longer observed, the
black solid was filtered, washed several times with acetone and
dried in air.
2.4. Characterization methods
The catalysts were characterized by FT-IR, XRD, SEM, EDS,
STEM, XPS and DSC techniques. FT-IR studies were carried out
using a Bruker–Equinox 55 spectrometer and a standard KBr pellet
technique. X-ray diffraction patterns were collected on a PANalyt-
2. Experimental
ical X’Pert Pro diffractometer using Cu Ka radiation. Morphology of
Ru/FCN composites was investigated by means of Field Emission
Scanning Electron Microscope JEOL JSM – 7500 F equipped with
the X-ray energy dispersive (EDS) system. Two detectors were used
and the images were recorded in two modes. The secondary elec-
tron detector provided SEI images and back scattered electron
detector provided BSE (COMPO) micrographs. K575X Turbo Sputter
Coater was used for coating the specimens with chromium (depos-
ited film thickness – 20 nm). Energy dispersive X-ray (EDS) mea-
surements were performed for both Ru and Cl elements.
Transmission electron microscopic studies were performed with
FEI Tecnai G2 transmission electron microscope at 200 kV equipped
with EDAX EDX and HAADF/STEM detectors. The X-ray Photoelec-
tron Spectroscopy measurements were performed in the ultrahigh
vacuum (2 ꢂ 10ꢃ7 Pa) system equipped with hemispherical ana-
lyzer (SES R4000, Gammadata Scienta). The unmonochromatized
2.1. Materials
Acetophenone, and RuCl3ꢀxH2O were purchased from Sigma–Al-
drich while 1-phenylethanol, 1-cyclohexylethanol, cyclohexyl
methyl ketone were manufactured by Fluka.
2.2. Preparation of Ru/FCN composites
The preparation route of FCN resin is based on a two-step pro-
cess involving preparation of GMA-co-polymer and its functional-
ization by ethylene diamine. The details concerning the synthesis
and characterization of FCN resin were published before [14].
The first step consisted of the synthesis of GMA co-polymer by
suspension polymerization of the mixture of glycidyl methacrylate
(GMA, 20 mol%), styrene (77 mol%) and diethylene glycol dimeth-
acrylate (DEGDMA, 3 mol%). The GMA co-polymer was obtained
in the form of microbeads. In the second step microbeads of
GMA-co-polymer were functionalized by ethylene diamine to pro-
duce final FCN resin (Scheme 1). Functionalization was performed
with 5-fold excess of ethylene diamine in DMF medium (24 h, at
80 °C). The final FCN polymer was carefully washed with DMF,
methanol and methylene chloride and then dried in vacuum oven
at 40 °C. The FCN resin (3% crosslinking degree) used in present
Mg Ka X-ray source of incident energy of 1253.6 eV was applied
to generate core excitation. The spectrometer was calibrated
according to ISO 15,472:2001. The energy resolution of the system
in all experiments, measured as a full width at half maximum
(FWHM) for Ag 3d5/2 excitation line, was 0.9 eV. The spectra were
calibrated for C 1s excitation at binding energy of 285.0 eV. The
spectra were analyzed and processed with the use of CasaXPS
2.3.10. software. The background was approximated by Shirley
algorithm and the detailed spectra were fitted with Voigt function.
The accuracy of the XPS analysis is approximately 3%. DSC mea-
surements were performed using Toledo 822 calorimeter with Star
System software. The samples were heated from 30 °C to 300 °C
and then cooled to 30 °C. The procedure was repeated twice. The
rates of heating and cooling were adjusted to 10 °C/min. Swelling
ability of pure resin, as-prepared and NaBH4 treated Ru/FCN com-
posites was evaluated by the measurements of bulk expanded vol-
ume in THF solvent. About 0.06 g of dry sample was placed into
1 cm3 graduated syringe and its volume was measured (Vo). Then,
an excess of THF was added. Swelling equilibrium was achieved
after 30 min, and the volume of expanded samples (Vs) was deter-
mined. As the measure of swelling ability the ratio Vs/Vo was as-
sumed. In order to predict the geometry and electronic structure
work was in the form of beads 50–150 lm in size, the content of
N was determined to be 2.78 wt.% [14]. THF, in which the FCN poly-
mer swells very well, was used as a solvent medium during the
preparation of Ru-composites.
Ru/FCN composites, with ruthenium loadings of 1, 2, and 4 wt.%,
were synthesized as follows. Prior to incorporation of ruthenium,
ca. 2 g of FCN resin was allowed to swell for 30 min in 25 ml of
THF solvent. Then 15 ml of RuCl3 aqueous solution (0.015 mol/
dm3, 0.03 mol/dm3, and 0.06 mol/dm3 for 1%, 2% and 4%Ru, respec-
tively) were added and the suspension of polymer beads in THF/
aqueous medium was gently shaken until the complete discolor-
ation of initially black solutions. The resulting dark brown or black
polymer beads were separated by filtration, washed with acetone

384
D. Duraczynska et al. / Reactive & Functional Polymers 70 (2010) 382–391
1714
1601
(a)
(b)
1380
1665
1550
1638
1354
Scheme 2. Hydrocarbon chain used as a model of polymer for theoretical studies.
of possible ruthenium–polymer species, theoretical studies were
done within density functional theory (DFT) with Becke–Perdew
functional [25,26], as implemented in Turbomole v. 5.9.0. [27].
The resolution of identity (RI) approach [28] was applied for com-
puting the electronic Coulomb interactions. For geometry optimi-
zations, all electron basis sets of SVP quality were employed for
all atoms (C, H, O and N) except for ruthenium, for which equiva-
lent effective core potential was used [29]. The polymer was mod-
eled by hydrocarbon chain carrying all functional groups (see
Scheme 2), and the polymer chain was approximated by phenyl
ring. It was assumed that octahedral sphere was preserved and
each ruthenium atom was coordinated to the polymer chain by
nitrogen atoms, and two chlorine ions completed octahedral
structure.
2000
1900
1800
1700
1600
1500
1400
1300
1200
Wavenumber [cm-1]
Fig. 1. FT-IR spectra of (a) FCN resin and (b) as-prepared 1%Ru/FCN.
1714
1655
1601
(a)
(b)
1380
2.5. Hydrogenation experiments
1550
Hydrogenation experiments were carried out in an agitated
batch glass reactor at constant atmospheric pressure of hydrogen
and temperature 40 °C. 10 cm3 of H2O and 10 cm3 of ACT solution
in isooctane (137ꢀ10ꢃ5 mol/dm3) as well as 0.2 g of catalyst were
placed in the reactor. Before the hydrogenation experiment the
catalyst wetted with water was activated inside the reactor by
passing gaseous hydrogen through the reactor for 45 min at 20 °C
and 45 min at the temperature of reaction (40 °C in the typical pro-
cedure). The progress of reaction was monitored by gas chroma-
tography. Samples of liquids were withdrawn from the reactor
via a sampling tube at regular intervals of time and analyzed by
GC method. A gas chromatograph (Clarus 500, Perkin Elmer) with
He as carrier gas (flow rate 1 cm3/min) equipped with a capillary
2000
1800
1600
1400
1200
Wavenumber [cm-1]
Fig. 2. FT-IR spectra of (a) FCN resin and (b) as-prepared 4%Ru/FCN.
column Elite 5MS (30 m ꢂ 0.25 mm ꢂ 0.25
lm) and a flame ioniza-
istic of FCN functional groups. A broad new band located at ca.
1354 cmꢃ1 can clearly be seen next to the band of CAN vibration
at 1380 cmꢃ1 visible in the spectra of as-received 1%Ru/FCN and
4%Ru/FCN composites (Figs. 1 and 2). In the range of NAH vibra-
tions a new band around 1638 cmꢃ1 appears. As shown in Figs. 1
and 2, such spectral changes are observed irrespective of the load-
ing of ruthenium in the FCN polymer. From such spectral changes
it can be concluded that functional groups of FCN polymer, partic-
ularly N-groups, like ANH and ANH2 participate in bonding of
ruthenium species to polymer matrix. A similar observation has
been reported by Patel et al. [20] for glycine modified chlorome-
thylated polymer.
tion detector (FID) was used to analyze the composition of reaction
mixture. The contents of acetophenone (ACT), 1-phenyletahanol
(PE), cyclohexyl methyl ketone (CMK), and 1-cyclohexylethanol
(CE), and ethylbenzene (EB) were determined by the comparison
with calibration curves.
3. Results and discussion
3.1. FT-IR spectroscopy
Fourier transform IR spectra of the parent FCN resin and Ru/FCN
composites with 1%Ru and 4%Ru are shown in Figs. 1 and 2, respec-
tively. In the FT-IR spectrum of parent FCN polymer a set of bands
originating from the presence of styrene as well as carbonyl and
amine functional groups can be seen [14]. Strong and broad bands
located at 1714 cmꢃ1 and 1601 cmꢃ1 are ascribed to CAO stretch-
ing vibrations in the carbonyl group. The bands located within the
range 1550–1655 cmꢃ1 are assigned to the NAH bonds in ANH and
ANH2 functional groups and the band 1380 cmꢃ1 to the vibrations
of CAN bond [14]. In the spectral region characteristic of hydrogen
bond vibrations a broad maximum located at 3430 cmꢃ1 appears
(spectrum not shown).
3.2. XRD diffraction studies
Fig. 3 shows the XRD diffraction patterns of the parent FCN
polymer, as-prepared and NaBH4 treated Ru/FCN composites. In
the diffraction pattern of parent FCN polymer two broad peaks lo-
cated within the 2h region of 10–18° can clearly be seen indicating
partly crystalline nature of the polymer. Incorporation of RuCl3 re-
sults in a broadening of these reflections, particularly obvious for
the peak around 11°. Such modification of the XRD pattern sug-
gests some degree of ‘‘disordering” in polymer backbone due to
incorporation of Ru-species. The effect is maintained after treat-
The most noticeable spectral changes caused by the incorpora-
tion of ruthenium species are observed within the range character-

D. Duraczynska et al. / Reactive & Functional Polymers 70 (2010) 382–391
385
1%Ru/FCN
2%Ru/FCN
4%Ru/FCN
(c)
(c)
(c)
(b)
(b)
(a)
(b)
(a)
(a)
5
15
25
35
45
5
15
25
35
45
5
15
25
35
45
2 Theta
2 Theta
2 Theta
Fig. 3. XRD profiles of parent FCN resin (a), as-prepared (b) and NaBH4 treated Ru/FCN composites (c).
ment of Ru-composites by reducing agent, NaBH4. Furthermore,
the XRD patterns of reduced composites show no trace of peaks
at 2h = 38.1°, 42.1°, and 44.0° characteristic of most intense reflec-
tions of crystalline Ru metal [30–32] which confirms fine disper-
sion of metallic Ru centers.
3.3. Electron microscopic studies (SEM, EDS)
The morphology of parent FCN polymer, as-prepared and NaBH4
treated Ru/FCN composites was studied by scanning electron
microscopy technique (SEM). Energy dispersive X-ray spectroscopy
(EDS) was used to evidence the presence of Ru and Cl elements. X-
ray microprobe analysis for Ru and Cl elements was performed in
various grains of Ru-composites as well as in several surface areas
of composite beads.
In Fig. 4a showing parent FCN, spherical beads of polymer with
smooth surface can clearly be seen. Fig. 4b shows the SEM image of
as-prepared 4%Ru/FCN composites. Strong changes in morphology
of polymer beads are observed as a result of incorporation of RuCl3.
The surface of Ru-containing polymer beads features highly folded
texture. These folds characterize various depths and shapes and
creates complex ‘‘mosaic” texture of Ru-containing spherical poly-
mer beads (Fig. 4c). These morphological changes – folds – are very
distinct and are formed in most of polymer beads. It should be
noted that no such effects are observed in polymer support sub-
jected to treatment with impregnating solution without Ru salt.
This type of morphological changes was observed irrespective of
the Ru loading in the polymer. At low loading of Ru in polymer
(1%Ru/FCN) only few polymer beads exhibited folded morphology.
As the loading of Ru is increased, the number of beads with
‘‘mosaic” texture increased. Moreover, the Ru–polymer beads dif-
fered with respect to the extent of foldings. In order to clarify the
nature of such strong morphological changes, X-ray analysis was
carried out for Ru and Cl elements for few beads of 4%Ru/FCN dif-
fering in the degree of folding (Fig. 5). From the data of EDS anal-
ysis of Cl/Ru atomic ratio (at.%/at.%) was calculated and the
obtained data are collected in Table 1.
First of all, it is evident that both elements Ru and Cl are present
in all polymer beads. Moreover, the values of Cl/Ru atomic ratio for
smoother beads (spectra 1 and 2, Fig. 5) were 2.05 and 2.16 being
only slightly smaller than that of stoichiometric Cl/Ru ratio equal
to three (see Table 1). The values of Cl/Ru were lower (1.38 and
1.12) for the beads with more folded texture (spectra 7, 8 in
Fig. 5). For the highly folded beads (spectra 3–6 in Fig. 5) the lowest
Cl/Ru atomic ratios, below one, were observed. It can be therefore
concluded that the observed strong changes in morphology of
Fig. 4. SEM micrographs of (a) parent FCN (ꢂ100), (b) as-prepared 4%Ru/FCN
(ꢂ100), and (c) as-prepared 4%Ru/FCN (ꢂ1000).
polymer beads are the result of Ru-species insertion. For all ana-
lyzed beads of as-prepared Ru/FCN composites the Cl/Ru atomic ra-

386
D. Duraczynska et al. / Reactive & Functional Polymers 70 (2010) 382–391
after the chelation of Ru(III) by N,O-ligands [20] in glycine func-
tionalized styrene–DVB. After the treatment of Ru/FCN composites
with NaBH4, the content of Cl strongly decreased with consequent
decreasing of Cl/Ru ratio (Table 2). In reduced composites only
traces of Cl are detected by the EDS analysis. The observed decrease
of Cl content indicates the breakage of the RuACl bonds and the
subsequent removal of Cl ions upon the treatment with reducing
agent. The representative SEM images of NaBH4 treated 4%Ru/
FCN composite is shown in Fig. 6. It can be seen that after the treat-
ment of Ru/FCN sample with NaBH4, the complex ‘‘mosaic” texture
is still preserved. However, the new irregular ‘‘bright” spots of var-
ious shapes and sizes randomly oriented and distributed through-
out the polymer beads appeared. The representative SEM images of
a typical ‘‘bright” spots registered at high magnification using both
SEI and BSE (COMPO) detection modes are shown in Fig. 7a and b,
respectively. For the comparison, typical surface morphology of
untreated FCN polymer is shown in Fig. 8. A number of small
Fig. 5. SEM micrograph of as prepared 4%Ru/FCN composite with marked areas
where EDS analysis was performed.
spherical polymer beads
– particles of very uniform sizes
(0.1 m) forming granular morphology composed of relatively reg-
l
Table 1
ular ‘‘chains” can be seen on the surface of untreated FCN polymer.
The SEI image of NaBH4 treated 2%Ru/FCN composite shows the
same type of granular morphology, however some of small poly-
mer particles differ from the others. They are observed in the BSE
images (COMPO) as the ‘‘bright” spherical particles, i.e. the poly-
mer small spherical particles consisting of ruthenium (Fig. 7).
EDS analysis carried out in areas of these ‘‘bright spots” showed
predominant presence of Ru (94.4–96%) with only traces of Cl
(4–6%). Thus, these bright, irregularly shaped spots observed in
the BSE (COMPO) images present the particles of polymer enriched
by metallic ruthenium. Fig. 9a presents STEM micrograph of NaBH4
treated 2%Ru/FCN. At this high magnification, ‘‘bright” areas are
visible throughout the whole examined sample. It is interesting
to note that no separate Ru-particles were visible and no diffrac-
tion of crystalline ruthenium was observed (Fig. 9b). No crystalline
ruthenium was also observed by the XRD diffraction pattern
shown in Fig. 3. Thus, most likely colloidal ruthenium or nano-
clusters of ruthenium were formed.
EDS analysis of as-prepared 4%Ru/FCN.
Spectrum
Ru (at.%)
Cl (at.%)
Cl/Ru
Spectrum 1
Spectrum 2
Spectrum 3
Spectrum 4
Spectrum 5
Spectrum 6
Spectrum 7
Spectrum 8
32.75
31.68
54.61
52.27
51.96
56.38
41.98
47.08
67.25
68.32
45.39
47.73
48.04
43.62
58.02
52.92
2.05
2.16
0.83
0.91
0.92
0.77
1.38
1.12
tios were distinctly lower as compared to the stoichiometric value
of RuCl3 (Cl/Ru = 3). This suggests that upon the treatment of FCN
polymer with RuCl3, the breakage of the RuACl bond occurred
and some of Cl-ligands were substituted by the N/O ligands from
the FCN polymer (Scheme 1). The lower Cl/Ru atomic ratios ob-
served for the most folded beads may suggest higher degree of Cl
exchange by N/O ligands from the polymer. Thus, the larger partic-
ipation of the functional groups of FCN polymer in the bonding to
Ru-species, the more distinct morphological changes are.
3.4. X-ray photoelectron spectroscopy
Although the contents of Ru and Cl differed for individual beads
of Ru-composites, the average value of Cl/Ru ratios were calculated
for particular Ru/FCN composites (with 1, 2, and 4 wt.%) and they
are presented in Table 2. It can be seen that as the Ru loading in-
creases from 1% up to 4%, the Cl/Ru atomic ratio gradually in-
creases from 0.6 to 1.12. Hence, at lower loading of Ru,
functional groups of polymer are more involved in the coordina-
tion of Ru-species, and as the loading of Ru grows the participation
of polymer in coordination of ruthenium gradually decreases. It
should be stressed that remarkable morphological changes were
also noticed upon treatment of bidenate N, O-donor sites-contain-
ing polymer (poly(S-DVB) with RuCl3 solution [33]. Some changes
in the morphology of polymer and its texture were also noticed
XPS measurements were employed to confirm the coordination
of ruthenium by functional groups of FCN polymer. As pointed out
in the literature there are relatively few reliable reference values of
the photoelectron binding energy for ruthenium compounds [34–
36]. Moreover, the value of BE is very sensitive to changes in the
nearest environment of the Ru atom, e.g. types of ligands.
Table 2
The average values of EDS data for as-prepared and NaBH4 treated Ru/FCN
composites.
Sample
Ru (at.%)
Cl (at.%)
Cl/Ru
As-prepared 1%Ru/FCN
NaBH4 treated
57
92.87
43
7.13
0.60
0.08
As-prepared 2%Ru/FCN
NaBH4 treated
60.26
85.53
39.74
14.47
0.66
0.17
As-prepared 4%Ru/FCN
NaBH4 treated
46.09
86.72
53.91
13.28
1.17
0.15
Fig. 6. SEM micrograph of NaBH4 treated 4%Ru/FCN composites.

D. Duraczynska et al. / Reactive & Functional Polymers 70 (2010) 382–391
387
Fig. 7. SEM micrograph of NaBH4 treated 2%Ru/FCN obtained with SEI (a) and
COMPO (b) detection modes (magnification 100,000).
Fig. 9. STEM micrograph of NaBH4 treated 2%Ru/FCN (a) and its diffraction pattern
(b).
Table 3
Binding energies (BE) and contributions (%) of individual Ru3+ peak components.
Sample
Ru 3p3/2
Ru 3d5/2
BE (eV) Contributions (%) BE (eV) Contributions (%)
RuCl3ꢀxH2O
As-prepared
4%Ru/FCN
463.00
462.95
100
79.4
281.80
281.31
100
79.6
465.97
463.16
20.6
66.3
282.43
281.33
20.4
66.8
NaBH4 treated
4%Ru/FCN
465.92
33.7
282.41
33.2
Fig. 8. SEM micrograph of parent FCN.
to))ruthenate(III) complex, K[Ru(CH3C@(O)CHC@(C6H5)NCH2CH
(CH3)N@C(C6H5)C@(H)C(O)CH3)Cl2], in which Ru is coordinated
to N,O-containing ligands [38].
The XPS spectra of as-prepared 4%Ru/FCN composite showed
two ruthenium states characterized by Ru 3d5/2 energy of
281.31 eV and 282.43 eV (3p3/2 energy of 462.95 eV and
467.97 eV, respectively) (Table 3). The first Ru 3d5/2 energy of
281.31 eV (3p3/2, 462.95 eV) is very similar to the energy of ruthe-
nium state in starting reagent, RuCl3 complex having the Cl ions as
the ligands [37]. The appearance of the second ruthenium state
with higher binding energy of 282.43 (3p3/2, 465.97 eV) indicates
the presence of a new type of Ru3+ ions surrounded most probably
by N and O – containing ligands [37]. The binding energy observed
for this component is similar to that reported for potassium di-
Hence, results obtained by the XPS technique are consistent
with the FT-IR spectra showing the participation of functional
groups of FCN polymer in the bonding of Ru-species. It should be
stressed that the obtained XPS data are not quite representative
for the whole analyzed composite, because of high inhomogeneity
of Ru and Cl in individual composite beads (see Table 1). Therefore,
XPS data may be considered as indicative of two types of Ru3+
states, whereas in view of EDS results (Tables 1 and 2) the contri-
bution of such states may vary in different places of polymer beads.
In the XPS spectrum of NaBH4 treated 4%Ru/FCN composite the
same two states of Ru-species were observed (see Table 3). How-
chloro
(4,40-(1,2-propylenediimino)-bis(4-phenyl-butan-2-ona-

388
D. Duraczynska et al. / Reactive & Functional Polymers 70 (2010) 382–391
Table 5
ever the contribution of Ru-state of lower binding energy originat-
ing from Ru3+-Cl decreased (from 79.4% to 66.3%) at the expense of
Ru-state with higher binding energy (465.92 eV) ascribed to Ru3+
ions surrounded by N and/or O containing ligands. In fact, the con-
tent of Cl in reduced composites decreased (Table 1). This suggests
some type of ‘‘reorganization” in the nearest environment of Ru3+
ions upon the NaBH4 treatment, which acted as the reducing agent
mostly towards the RuACl species. Noteworthy, in the NaBH4 trea-
ted 4%Ru/FCN composite surface no peaks assignable to metallic Ru
(Ru 3d5/2, 280.6 eV, 3p3/2, 462 eV) [37] can be seen. It has to be born
in mind that XPS is a surface sensitive technique, and it provides
information only from the most external surface layer of the solid
(ca. few nanometers). The result shows that surface ruthenium
species probed by the XPS technique become reoxidized after
exposure of the catalyst to air.
The values of glass transition temperature Tg (°C) determined for parent FCN, as-
prepared and NaBH4 treated Ru/FCN composites.
Sample
FCN
Tg (°C)
130
As-prepared 1 wt.%Ru/FCN
NaBH4 treated 1 wt.%Ru/FCN
141
150
As-prepared 2 wt.%Ru/FCN
NaBH4 treated 2 wt.%Ru/FCN
147
151
As-prepared 4 wt.%Ru/FCN
NaBH4 treated 4 wt.%Ru/FCN
140
160
quite well confirms additional crosslinking of FCN polymer by Ru
complex. The treatment of as-prepared Ru-composites by NaBH4
results in further increase of Tg evidencing even higher crosslinking
of polymer due to greater participation of functional groups of FCN
polymer in coordination of Ru3+ ions, observed also by the XPS
analysis. Thus, similarly to the observation of other authors, partic-
ipation of polymer in the Ru-complexes has a direct effect on the
properties of Ru-composites such as swelling ability of polymer
mass and the temperature of glass transition [1,8].
3.5. Swelling measurements
The FCN resin consists mostly of non-polar constituents such as
styrene (ca. 77 mol%) and smaller number of polar groups such as
carbonyl and N-groups. This composition makes FCN resin rela-
tively hydrophobic, and THF (dielectric constant,
e = 7) was found
to be the solvent resulting in the best expansion of FCN beads
[14]. Therefore, swelling ability of pure FCN and as-prepared Ru/
FCN composites was examined in THF solvent and the obtained
data are collected in Table 4. These data show that the parent
FCN polymer swells very well in THF and the volume of its beads
increases 4.8-times. After incorporation of Ru-species the expan-
sion of polymer mass in THF remarkably decreases, being only
2.4–3.2. No clear trend indicating the influence of the content of
incorporated ruthenium upon the swelling ability was observed.
The reduced swelling ability of Ru/FCN composites indicates that
the structure of ruthenium–polymer composite becomes more ri-
gid. This can be related to the formation of a ‘‘more crosslinked”
polymer network. As demonstrated by the physical–chemical char-
acterization, ruthenium–polymer complex is formed with the par-
ticipation of functional groups of FCN polymer. Apparently, such a
complex acts as an additional crosslinker. A similar phenomenon
was observed in the case of Ru(III)-complexes coordinated by gly-
cine modified chloromethylated styrene–divinyl benzene co-poly-
mer [20].
In conclusions, all employed methods (FT-IR, XPS, XRD, EDS,
SEM and STEM) show that ruthenium is indeed bound chemically
It should be noted that FCN polymer (and Ru/FCN composites)
do not swell in isooctane and water, i.e. the solvents used in pres-
ent catalytic hydrogenation experiments.
3.6. DSC studies
DSC experiments were performed for FCN resin, as-prepared
and NaBH4 treated Ru/FCN composites and the values of the glass
transition temperatures (Tg) are presented in Table 5. These data
show that the insertion of Ru3+-species leads to Tg rise from
130 °C for parent FCN up to ca. 141 °C for as-prepared Ru/FCN com-
posites. No influence of the ruthenium loading in FCN polymer on
the value of Tg is noticed. An increase of glass transition tempera-
ture indicates more rigid polymer backbone, which may result
from more crosslinked polymer. Thus, the observed increase of Tg
Table 4
Swelling ability (Vs/Vo) of pure FCN polymer and as-prepared Ru/FCN composites in
THF solvent.
Sample
Vs/Vo
Pure FCN
1%Ru/FCN
2%Ru/FCN
4%Ru/FCN
4.8
2.6
3.2
2.4
Scheme 3. Theoretical structures of ‘‘cis” (a) and ‘‘trans” (b) isomers of Ru/FCN
composite.

D. Duraczynska et al. / Reactive & Functional Polymers 70 (2010) 382–391
389
to the FCN polymer. The anchoring of Ru-complexes occurs with
participation of functional groups of the FCN resin, and involves
particularly the N-groups.
drances exerted on the center of the complex by bulky polymer
chains. In ‘‘cis” isomer, on contrary, there are larger discrepancies
between rutheniumAnitrogen bond lengths from two chelating
Reacting of RuCl3 with functional groups having glycine func-
tionalized styrene–DVB polymer resulted in Ru-complexes in
which four coordination positions were occupied by functional
groups (N, C@O) whereas parent Cl-ligands located in two axial
positions [20]. Similar coordination sphere was postulated in
poly(styrene–DVB)-supported amino acid-Ru(III) complexes hav-
ing two Cl-ligands in axial positions whereas four coordination
positions were occupied by two chelating N,O ligands [33]. The
presence of the two types of N-groups e.g. ANH and ANH2 in the
structure of FCN polymer (Scheme 1) was confirmed in previously
published data [14]. Thus, in the view of strong coordination ability
of Ru(III) ions and the above described literature reports [20,33]
two hypothetical structures (cis and trans isomers) of Ru-com-
plexes formed with functional groups (ANH2 and ANH) of polymer
were taken into account (see Scheme 3 and Table 6). In the pro-
posed structures, the presence of two Cl ions is assumed based
on the EDS analysis. In all as-prepared samples Cl/Ru atomic ratio
did not exceeded two (see Tables 1 and 2). Moreover, the Ru-spe-
cies identified by Patel et al. [20] and Valodkar [33] in which Ru
was coordinated to ANH ligands also contained two Cl ions in axial
positions. The comparison of total energies of the two complexes
indicates the ‘‘trans” isomer as predominant in the real system
(its total energy is lower than total energy of ‘‘cis” species by
27 kJ/mol). In ‘‘trans” isomer, the central ruthenium atom is equa-
torially coordinated to nitrogen atoms originated from polymer
functional groups. The RuAN bonds are slightly longer when
formed with the participation of nitrogen from terminal ANH2
group than with nitrogen from internal ANH group. Two chains
are practically equidistant from ruthenium and in this sense they
may be considered as being equivale0nt. The relatively small differ-
ence in RuACl bond lengths (0.009 ÅA) results form the steric hin-
polymer functional groups. It is seen that nitrogen atoms from
0
one functional group bind at the same distance (approx. 2.16 ÅA)
to the central metal, whereas these from the second one form
two non-equivalent bonds: shorter (with ANH2 group) and longer
(with ANH). Here, the difference between two RuACl bond lengths
0
is large than in ‘‘trans” isomer (it amounts to 0.019 ÅA), but the rea-
son for this seems to be the same. Thus, calculated energies indi-
cate that the formation of ‘‘trans” isomer with two axial Cl ions
is preferred, similarly to what was reported by Patel et al. [20]
and Valodkar et al. [33]. The participation of CAOH groups of
FCN polymer seems to be less probable because no changes in
the FT-IR spectral region of hydrogen bonds vibration were ob-
served after immobilization of ruthenium complexes. Moreover,
it cannot be excluded that octahedral symmetry of Ru3+ complexes
together with the chelating action of polymer groups forces the
occurrence of ‘‘disordering” of polymer framework with conse-
quent remarkable changes in morphology of Ru-containing poly-
mer beads.
3.7. Hydrogenation of acetophenone
The catalytic hydrogenation of acetophenone (ACT), used here
as a test reaction, is an important process of industrial relevance.
The intermediates and/or products of this reaction e.g. 1-phenyl-
ethanol (PE), cyclohexyl methyl ketone (CMK), 1-cyclohexyletha-
nol (CE) (Scheme 4) are widely used in pharmaceutical, cosmetic,
food, agrochemical, and chemical industries. The most desired 1-
phenylethanol, formed by the hydrogenation of carbonyl group of
acetophenone, found an application as a fragrance or an intermedi-
ate in synthesis of various pharmaceuticals. Since many products
are formed in the course of ACT hydrogenation, achieving high
selectivity toward 1-phenylethanol, being a desired product is a
complicated issue.
Table 6
Computed parameters of proposed ‘‘trans” and ‘‘cis” binding modes of ruthenium
atom to polymer chain.
In the present work the results of preliminary catalytic experi-
ments are shown. Further catalytic work is in progress in order to
shed more light on the catalytic behavior of Ru/FCN composites.
Here, catalytic efficiency of 2%Ru/FCN composite is compared with
that of 2%Ru/Al2O3 catalyst. In experiments Ru/FCN catalyst re-
duced by NaBH4 was used because no hydrogenation reaction of
ACT was observed in the presence of as-received catalyst. The
activity of both Ru/FCN and Ru/Al2O3 catalysts in organic solvents
such as ethanol, THF and isooctane was very low, practically no
measurable under conditions used in present experiments. There-
fore biphasic system composed of two solvents e.g. water and iso-
octane (1:1 V/V) was used, similarly to what was reported by
‘‘trans”
‘‘cis”
Relative energy (kJ/mol)
0
27
Bond length (Å)
RuACl
RuACl
RuANH2
RuANH
RuANH2
RuANH
2.366
2.357
2.144
2.170
2.147
2.168
2.356
2.337
2.134
2.219
2.167
2.169
OH
CH3
O
PE
HO
CH3
CH3
O
CE
ACT
CH3
CMK
Scheme 4. Hydrogenation of acetophenone.

390
D. Duraczynska et al. / Reactive & Functional Polymers 70 (2010) 382–391
Table 7
Perosa et al. [39] for hydrogenation of ACT in the presence of Pt/C
catalyst. The role of a biphasic solvent system is discussed in detail
in a forthcoming paper [40]. Briefly, the enhanced activity and
selectivity is interpreted as due chiefly to favourable modification
of polar properties of the reaction participants (reactants, catalyst
surface and solvents). The obtained data of catalytic experiments
are summarized in Fig. 10. It can be seen that after ca. 400 min
of reaction conversion of ACT attained about 70% (Fig. 10a) in the
presence of both catalysts, although the ‘‘shape” of curves differed.
An induction period is observed on 2%Ru/Al2O3 catalyst only. In the
presence of both catalysts the dominant reaction was hydrogena-
tion of C@O of ACT to give 1-phenylethanol (PE). The contribution
of other reactions, such as hydrogenation of aromatic ring of ACT or
PE yielding cyclohexyl methyl ketone (CMK) and cyclohexyletha-
nol (CE), respectively, proceeded to a much lesser extent. Forma-
tion of ethylbenzene is marginal on ruthenium catalysts [21,22]
and in fact no ethylbenzene was observed in the present catalytic
The composition of reaction mixture at 50% ACT conversion and selectivity (S) to
phenylethanol determined at 70% ACT conversion.
Catalyst
t (min)a PE (mol%) CMK (mol%) CE (mol%) S to PE (%)
2%Ru/FCN
2%Ru/Al2O3 242
188
40.3
34.6
6.3
3.4
5.4
77
67
10.0
Reaction conditions: 20 cm3 of ACT solution in water–isooctane (1:1 V/V) initial
ACT concentration of 0.137 mol/dm3, 0.2 g of catalyst, reaction temperature of
40 °C.
a
Time (min) required ed to reach 50% ACT conversion.
tests. It can be seen form Fig. 10b and c that the contribution of side
reactions involving hydrogenation of aromatic ring was especially
low in the presence of 2%Ru/FCN catalyst. As a consequence, at 50%
ACT conversion, the dominating product in the reaction mixture
was PE, a desirable product (Table 7). The selectivity to PE in final
solution (ACT conversion ca. 70%) was calculated to be 77% and
67% (see Table 7) for 2%Ru/FCN and 2%Ru/Al2O3 catalysts, respec-
tively. The relatively high selectivity towards phenylethanol (PE)
shows preferential activity of polymer-supported Ru catalysts un-
der present hydrogenation conditions towards the conversion of
acetophenone via hydrogenation of carbonyl groups, whereas the
hydrogenation of aromatic ring is strongly suppressed. It should
be also noted that the obtained selectivity to PE is higher than that
reported for Ru/TiO2 or Ru/SiO2 catalysts (50% and 18%, respec-
tively) [24]. Therefore, more catalytic experiments are needed to
clarify such highly efficient catalytic system and the studies are un-
der progress.
Al2O3
(a)80.0
70.0
FCN
60.0
50.0
40.0
30.0
20.0
10.0
0.0
4. Conclusions
0
50
100
150
200
250
300
350
400
100
100
By reacting of RuCl3 with swollen matrix of FCN polymer con-
taining diamine (ANH, ANH2 functional groups) a series of Ru/
FCN composites with various Ru loading (1%, 2%, and 4%) was pre-
pared. Physico-chemical characterization proved the participation
of polymer functional groups in the coordination of Ru(III). The
coordination sphere around Ru trapped within the polymer matrix
contained both Cl- and N-ligands in various proportions depending
on ruthenium loading in polymer. Taking into account the chelat-
ing character of N-ligands a hypothetical structure of octahedral
Ru(III) complex coordinated to FCN polymer was proposed. One
of these composites, 2%Ru/FCN when reduced by NaBH4 exhibited
catalytic activity in liquid phase hydrogenation of acetophenone.
Higher selectivity in the presence of FCN supported Ru as com-
pared to 2%Ru/Al2O3 catalyst toward 1-phenylethanol was
observed.
t [min]
2%Ru/FCN
(b) 60.0
50.0
40.0
30.0
20.0
10.0
0.0
PE
CMK
CE
0
20
40
60
80
Acknowledgements
ACT conversion [%]
D.D. acknowledges the financial support from the POL-POST
DOC II (Project D037/H03/2006) and Grant NN204 249034 (project
2490/B/H03/2008/34).
2%Ru/Al 2O3
(c) 50.0
40.0
PE
CMK
CE
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