Preparation and characterization of gold nanoparticles with a ruthenium-terpyridyl complex, and electropolymerization of their pyrrole-modified metal nanocomposites

Article abstract of DOI:10.1039/b412406e

The reduction of tetrachloroaurate with sodium borohydride in the presence of 2,2′:6′,2″-terpyridyloctanethiol gave terpyridine- functionalized gold nanoparticles (Tpy-Au, core size 2.0 nm). Metal complexation of Tpy-Au with ruthenium-terpyridyl trichloride, Ru(tpy)Cl₃, led to new gold nanoparticles bearing the ruthenium-terpyridine complex (Ru-Tpy-Au, core size 5.5 nm) which showed a characteristic MLCT (metal-to-ligand charge transfer) band in the visible region at 483 nm due to the terpyridine-ruthenium complex and a plasmon resonance at ～ 510 nm in the UV-vis spectrum. The redox behavior of Ru-Tpy-Au was studied by cyclic voltammetry. Surface modification of metal electrodes was performed by the electropolymerization of pyrrole-functionalized Ru-Tpy-Au nanoparticles (Pyr-Ru-Tpy-Au) which were obtained from the ligand-exchange reaction of Ru-Tpy-Au with w-(N-pyrrolyl)decanethiol. The Royal Society of Chemistry 2005.

Full text of DOI:10.1039/b412406e

View Article Online / Journal Homepage / Table of Contents for this issue
PAPER
www.rsc.org/materials | Journal of Materials Chemistry
Preparation and characterization of gold nanoparticles with a ruthenium-
terpyridyl complex, and electropolymerization of their pyrrole-modified
metal nanocomposites
Masayuki Ito, Takashi Tsukatani and Hisashi Fujihara*
Received 11th August 2004, Accepted 25th November 2004
First published as an Advance Article on the web 5th January 2005
DOI: 10.1039/b412406e
The reduction of tetrachloroaurate with sodium borohydride in the presence of
2,29:69,20-terpyridyloctanethiol gave terpyridine-functionalized gold nanoparticles (Tpy–Au, core
size 2.0 nm). Metal complexation of Tpy–Au with ruthenium-terpyridyl trichloride, Ru(tpy)Cl3,
led to new gold nanoparticles bearing the ruthenium-terpyridine complex (Ru–Tpy–Au, core size
5.5 nm) which showed a characteristic MLCT (metal-to-ligand charge transfer) band in the visible
region at 483 nm due to the terpyridine-ruthenium complex and a plasmon resonance at y510 nm
in the UV-vis spectrum. The redox behavior of Ru–Tpy–Au was studied by cyclic voltammetry.
Surface modification of metal electrodes was performed by the electropolymerization of pyrrole-
functionalized Ru–Tpy–Au nanoparticles (Pyr–Ru–Tpy–Au) which were obtained from the
ligand-exchange reaction of Ru–Tpy–Au with v-(N-pyrrolyl)decanethiol.
the preparation and characterization of gold nanoparticles
Introduction
(Tpy–Au) stabilized directly by 2,29:69,20-terpyridinyl-
octanethiol (Tpy–SH: 1) and their gold nanoparticles contain-
Currently, noble metal particles on the nanometer scale
represent a rapidly emerging field of great fundamental and
practical interest and are receiving worldwide attention.1–3
ing ruthenium-terpyridyl complexes (Ru–Tpy–Au) as a new
A
class of metal nanocomposites. We also describe the surface
modification of metal electrodes with pyrrole-functionalized
Ru–Tpy–Au nanoparticles (Pyr–Ru–Tpy–Au) by electropoly-
merization. Terpyridines (Tpy) as chelating binding units and
their ruthenium complexes are widely used for the construction
of dendrimers as nanoscale-molecules and supramolecules
because of their unique electrochemical and photochemical
properties.11
number of gold nanoparticles containing functional units have
been synthesized.4,5 Functionalization of the gold nano-
particles with self-assembled monolayers provides a method
for introducing diverse functionality to the nanoparticle
surface. We recently reported the first preparation of full-
erenethiolate-functionalized gold nanoparticles as new metal–
C60 nanocomposites which are adsorbed onto the surface of
gold electrodes to form nanoparticle films.6 In contrast, much
less attention has been paid to the preparation of function-
alized gold nanoparticles with metal complexes. An intriguing
further development in this area involves the attachment of
electropolymerizable groups at the periphery of metal nano-
particles taking advantage of the electropolymerization pro-
cess to prepare electrodes modified by electroactive poly(metal
nanoparticles). Electrochemical polymerization is an elegant
strategy for the immobilization of redox-active groups on the
surface of electrodes and the preparation of conductive
polymer thin films. The surface modification of electrodes
with electroactive polymer thin films has been performed from
the electrochemical polymerization of pyrrole-based mono-
mers which are the most commonly used materials.7 Recently,
increasing attention is being given to the fabrication of thin
films of metal nanoparticles from both a fundamental and a
practical application point of view.8 Such thin films of metal
nanoparticles on solid surfaces have been prepared using a
number of strategies including assembly techniques with
crosslinkers for metal nanoparticles;8 however, the literature
on polymer thin films of metal nanoparticles by the electro-
polymerization method is quite limited.9,10 This paper presents
Experimental
1. Chemicals
All reagents were purchased from Wako Pure Chemical
Industries Ltd., Tokyo Kasei Co. Ltd., Fluka Chemical Co.,
or Aldrich Chemical Co. The reagents used as reaction
solvents were further purified by general methods.
2. Instruments
NMR spectra were recorded on JEOL GSX270 and JEOL
GSX500 (270 MHz and 500 MHz) spectrometers. UV-vis
spectra were measured with a Hitachi U-4000. Mass spectra
were recorded on a JEOL JMS-700. Fourier Transform
Infrared (FT-IR) spectra were collected with a JASCO FT-
IR-470. Transmission electron microscopy (TEM) measure-
ments were performed on a JEOL JEM-3010. Samples for
TEM studies were prepared by placing drops of the gold
nanoparticles (Tpy–Au, Ru–Tpy–Au and Pyr–Ru–Tpy–Au)
on carbon-coated TEM grids.
Cyclic voltammetry was performed at room temperature
using a BAS Instrument model 100B/W electrochemical
workstation. Platinum wire was used as the counter electrode
*h-fuji@apch.kindai.ac.jp
960 | J. Mater. Chem., 2005, 15, 960–964
This journal is ß The Royal Society of Chemistry 2005

View Article Online
Scheme 3 Reagents and conditions: i, n-BuLi, THF,
0 uC; ii,
Br(CH2)10Br, reflux; iii, MeCOSK, MeCN, room temp.; iv, HCl,
MeOH, reflux.
1,8-dibromooctane (7.40 mL, 40 mmol) in the presence of
K2CO3 (2.76 g, 20 mmol) in MeCN was stirred at reflux under
argon for 16 h. After work-up, the crude products were
purified by silica-gel column chromatography (benzene) to
give 4. 4: mp 92–93 uC, 1H NMR (CDCl3) d 8.72–8.67 (m, 2H,
ArH), 8.65–8.58 (m, 2H, ArH), 8.00 (s, 2H, ArH), 7.88–7.80
(m, 2H, ArH), 7.36–7.29 (m, 2H, ArH), 4.22 (t, 2H, J 5 7 Hz,
OCH2), 3.42 (t, 2H, J 5 7 Hz, CH2Br) and 1.88–1.30 (m, 12H,
CH2); 13C NMR (CDCl3) d 167.3, 157.0, 156.2, 149.0, 136.7,
123.7, 121.3, 107.4, 68.1, 33.9, 32.8, 29.1, 28.9, 28.6, 28.1, 25.8.
MS, m/z 440 (M+).
49-(8-Thiobenzoateoctyloxy)-2,29:69,20-terpyridine (5).
A
Scheme 1 Preparation of Ru–Tpy–Au and Pyr–Ru–Tpy–Au.
mixture of 4 (2.20 g, 5 mmol) and sodium thiobenzoate
(1.12 g, 7 mmol) in anhydrous MeCN (80 mL) was refluxed for
13 h. After work-up, the crude products were recrystallized
from MeCN to give 5. 5: mp 98 uC; FT-IR 1661 cm21 (CLO);
1H NMR (CDCl3) d 8.70–8.67 (m, 2H, ArH), 8.64–8.59 (m,
2H, ArH), 8.01 (s, 2H, ArH), 7.98–7.95 (m, 1H, ArH), 7.87–
7.80 (m, 2H, ArH), 7.56–7.53 (m, 1H, ArH), 7.46–7.43 (m, 1H,
ArH), 7.35–7.32 (m, 1H, ArH), 4.24 (t, 2H, J 5 7 Hz, OCH2),
3.08 (t, 2H, J 5 7 Hz, SCH2), 1.90–1.38 (m, 12H, CH2); 13C
NMR (CDCl3) d 192.1, 167.3, 157.0, 156.2, 149.0, 137.2, 136.7,
133.1, 128.5, 127.1, 123.7, 121.3, 107.4, 68.1, 29.5, 29.1, 29.0,
28.95, 28.9, 28.8, 25.8. MS, m/z 498 (M+).
and glassy carbon (3.0 mm diameter) or gold (1.6 mm
diameter) was used as the working electrode in a one-
compartment cell. Potentials were relative to the system
Ag/0.1 M AgNO3 in acetonitrile. Bu4NPF6 (Fluka, electro-
chemical grade) and MeCN (Wako, anhydrous) were used for
the preparation of electrolyte solutions.
3. Synthesis of terpyridine-thiol (1) and pyrrole-thiol (2)
The synthetic sequence is described in Schemes 2 and 3. 2,6-
Bis(29-pyridyl)-4-pyridone (3) was synthesized according to the
procedure of Constable and Ward.12
49-(8-Mercaptooctyloxy)-2,29:69,20-terpyridine (Tpy–SH: 1).
A mixture of 5 (996 mg, 2 mmol) and LiAlH4 (152 mg, 4 mmol)
in anhydrous THF (30 mL) was stirred under argon at room
temperature for 5 h. After work-up, the crude products
were purified by alumina column chromatography (hexane–
MeCO2Et 5 10 : 1) to give 1. 1: mp 73–74 uC; FT-IR
2510 cm21 (SH); 1H NMR (CDCl3) d 8.71–8.67 (m, 2H, ArH),
8.64–8.59 (m, 2H, ArH), 8.01 (s, 2H, ArH), 7.88–7.81 (m,
2H, ArH), 7.36–7.30 (m, 2H, ArH), 4.22 (t, 2H, J 5 7 Hz,
OCH2), 2.53 (dt, 2H, J 5 8, 7 Hz , CH2S), 1.86 (q, 2H, J 5
7 Hz, CH2), 1.68–1.40 (m, 10H, CH2), 1.35 (t, 1H, J 5 8 Hz,
SH); 13C NMR (CDCl3) d 167.3, 157.0, 156.1, 149.0, 136.7,
123.7, 121.3, 107.3, 68.1, 34.0, 29.1, 28.9, 28.2, 25.8, 24.6. MS,
m/z 393 (M+).
49-(8-Bromooctyloxy)-2,29:69,20-terpyridine (4). A mixture
of 2,6-bis(29-pyridyl)-4-pyridone (3) (5.00 g, 20 mmol) and
1-(10-Bromodecyl)pyrrole (6). A mixture of pyrrole (5 mL,
72 mmol) and n-BuLi (1.6 M/hexane, 56 mL, 90 mmol) in
anhydrous THF was stirred at 0 uC under argon for 1 h. Then,
1,10-dibromodecane (16 mL, 72 mmol) in anhydrous was
added dropwise. This mixture was refluxed for 2 h. After
work-up, the crude products were purified by silica-gel column
chromatography (hexane–benzene 5 1 : 1) to give 6. 6: 1H
Scheme 2 Reagents and conditions: i, Br(CH2)8Br, K2CO3, MeCN,
reflux; ii, PhCOSNa, MeCN, reflux; iii, LiAlH4, THF, room temp.
This journal is ß The Royal Society of Chemistry 2005
J. Mater. Chem., 2005, 15, 960–964 | 961

View Article Online
NMR (CDCl3) d 6.64 (t, 2H, J 5 2 Hz, 2,5-pyrrole), 6.13 (t,
2H, J 5 2 Hz, 3,4-pyrrole), 3.86 (t, 2H, J 5 7 Hz, NCH2), 3.40
(t, 2H, J 5 7 Hz, CH2Br), 1.85 (q, 2H, J 5 7 Hz, BrCH2CH2),
1.75 (q, 2H, J 5 7 Hz, NCH2CH2) and 1.41–1.22 (m, 12H,
CH2); 13C NMR (CDCl3) d 120.4, 107.7, 49.6, 34.0, 32.8, 31.5,
29.3, 29.2, 29.1, 28.7, 28.1 and 26.7. MS, m/z 286 (M+).
1-(10-Thioacetyldecyl)pyrrole (7). A mixture of 6 (552 mg,
1.93 mmol) and potassium thioacetate (440 mg, 3.85 mmol) in
anhydrous MeCN (12 mL) was stirred at room temperature
under argon for 2 h. After work-up, the crude products were
purified by silica-gel column chromatography (hexane–
benzene 5 1 : 3) to give 7. 7: FT-IR 1692 cm21 (CLO); 1H
NMR (CDCl3) d 6.64 (t, 2H, J 5 2 Hz, 2,5-pyrrole), 6.13 (t,
2H, J 5 2 Hz, 3,4-pyrrole), 3.85 (t, 2H, J 5 7 Hz, NCH2),
2.85 (t, 2H, J 5 7 Hz, CH2S), 2.31 (s, 3H, CH3), 1.75 (q, 2H,
J 5 7 Hz, NCH2CH2), 1.55 (q, 2H, J 5 7 Hz, SCH2CH2) and
1.40–1.20 (m, 12H, CH2); 13C NMR (CDCl3) d 196.0, 120.4,
107.7, 49.5, 31.5, 29.4, 29.3, 29.2, 29.1, 29.0, 28.7 and 26.7. MS,
m/z 281 (M+).
condensed in vacuo and mixed with diethyl ether. An aqueous
solution of NH4PF6 was then added to precipitate the
terpyridine-ruthenium complexes, Ru–Tpy–Au nanoparticles.
Preparation of Pyr–Ru–Tpy–Au. The ligand-exchange reac-
tion of Ru–Tpy–Au with a pyrrolethiol 2 was carried out as
follows. A mixture of Ru–Tpy–Au nanoparticles (50 mg) and
thiol 2 (15 mg) in MeCN (2 mL) was stirred at room
temperature for 48 h. To the mixture was added EtOH
(200 mL) and then the resulting precipitate was collected
by filtration and washed several times with EtOH. The
nanoparticles were redissolved in MeCN to purify and
precipitated with EtOH, and then the particles were isolated
by filtration.
Results and discussion
Terpyridine-functionalized gold nanoparticles (Tpy–Au) were
prepared by the two-phase reaction4 and repeatedly isolated
from and redissolved in organic solvents and extremely stable.
Metal complexation on the nanointerface of Tpy–Au with
Ru(tpy)Cl3 led to the formation of Ru–Tpy–Au nanoparticles.
New redox-active multifunctional gold nanoparticles (Pyr–
Ru–Tpy–Au) containing Ru-terpyridine complexes and pyr-
role groups as electropolymerization sites were obtained from
the ligand-exchange reaction5 of Ru–Tpy–Au with a pyrrole-
substituted decanethiol (2) (Scheme 1).
1-(10-Mercaptodecyl)pyrrole (Pyr–SH: 2). A mixture of 7
(223 mg, 0.793 mmol) and 3 N HCl (0.4 mL) in MeOH (9 mL)
was refluxed for 2 h. After work-up, the crude products
were purified by silica-gel column chromatography (benzene)
to give 2. 2: FT-IR 2554 cm21 (SH); 1H NMR (CDCl3) d 6.64
(t, 2H, J 5 2 Hz, 2,5-pyrrole), 6.13 (t, 2H, J 5 2 Hz, 3,4-
pyrrole), 3.85 (t, 2H, J 5 7 Hz, NCH2), 2.51 (dt, 2H, J 5
8, 7 Hz, CH2SH), 1.75 (q, 2H, J 5 7 Hz, NCH2CH2), 1.59 (q,
2H, J 5 7 Hz, SCH2CH2), 1.42–1.23 (m, 12H, CH2) and 1.32
(t, 1H, J 5 8 Hz, SH); 13C NMR (CDCl3) d 120.4, 107.7, 49.7,
49.6, 33.9, 31.5, 29.3, 29.1, 28.9, 28.3, 26.7 and 24.5. MS, m/z
239 (M+).
The UV-vis spectrum of the Tpy–Au nanoparticle solution
in CHCl3 exhibited a small plasmon resonance at y505 nm,
which means the formation of small gold nanoparticles
[Fig. 1(inset)]. Further characterization of the material was
performed with use of NMR spectroscopy and transmission
electron microscopy (TEM). The proton signals in the 1H
NMR spectrum of Tpy–Au, though significantly broadened,
appeared at positions that are almost identical to those of
free thiol 1.14 The 13C NMR spectrum of Tpy–Au in CDCl3
showed the peaks of non-coordinate terpyridine ligands at
4. Preparation of Tpy–Au, Ru–Tpy–Au and Pyr–Ru–Tpy–Au
nanoparticles
Preparation of Tpy–Au. To a vigorously stirred solution of
tetraoctylammonium bromide (3.84 g, 7.02 mmol) in 90 mL of
toluene was added HAuCl4?4H2O (650 mg, 1.58 mmol) in
60 mL of deionized water. A solution of a thiol 1 (581 mg,
1.48 mmol) in 50 mL of toluene was added, and the resulting
solution was stirred for 20 min at room temperature.
NaBH4 (662 mg, 17.5 mmol) in 40 mL of deionized
water was then added. The mixture was stirred for 3 h at
room temperature. After stirring the organic phase was
evaporated to 20 mL in vacuo and mixed with EtOH
(800 mL). The resulting precipitate was collected by filtration
and washed several times with EtOH. The nanoparticles
were redissolved in CHCl3 to purify and precipitated with
EtOH, and then the particles were isolated by filtration. These
processes were repeated until no free thiol or phase transfer
1
catalyst remained, as detected by TLC and H and 13C NMR
spectroscopy.
Preparation of Ru–Tpy–Au. Metal complexation of the Tpy–
Au nanoparticle ligands was achieved by the following
procedure. Ru(tpy)Cl3 was obtained according to the litera-
ture.13 A mixture of Tpy–Au nanoparticles (50 mg) in CHCl3
(5 mL) and Ru(tpy)Cl3 (23 mg) in EtOH–H2O (1 : 1, 200 mL)
was refluxed for 24 h. After stirring, the solution was
Fig. 1 UV-vis spectra of (a) Ru–Tpy–Au in MeCN and (b) Pyr–Ru–
Tpy–Au in MeCN. Inset: Tpy–Au in CHCl3.
962 | J. Mater. Chem., 2005, 15, 960–964
This journal is ß The Royal Society of Chemistry 2005

View Article Online
The electrochemical properties of Ru–Tpy–Au were studied
by cyclic voltammetry. The cyclic voltammogram of Ru–Tpy–
Au was measured in 0.1 M Bu4NPF6–MeCN at a glassy
carbon electrode and Ag/0.1 M AgNO3 reference electrode
(scan rate: 100 mV s21). The half-wave potentials (E1/2
)
and the cathodic–anodic peak separation (DEp) values for
two terpyridine redox processes and the ruthenium(II)/(III)
process showed the following values: E1/2 5 21.52 (DEp 5
74) and 21.71 V (DEp 5 52 mV) for tpy ligands, and
+0.93 V (DEp 5 62 mV) for the Ru(II)/(III) couple (Fig. 3).
The Ru–Tpy–Au nanoparticles thus display the expected
electrochemistry.
Fig. 2 TEM micrographs of (a) Tpy–Au and (b) Ru–Tpy–Au.
In order to prepare a new type of polymer thin film
containing metal nanoparticles and metal complex, pyrrole-
modified Ru–Tpy–Au nanoparticles (Pyr–Ru–Tpy–Au) were
prepared from the ligand-exchange reaction of Ru–Tpy–Au
with thiol 2. The UV-vis spectrum of Pyr–Ru–Tpy–Au
solution in MeCN exhibited a characteristic MLCT absorption
(lmax 5 483, 306 and 273 nm) and significant plasmon
resonance (lmax 5 y510 nm) [Fig. 1(b)]. The TEM micro-
graph of Pyr–Ru–Tpy–Au indicated a particle size of 5.5 ¡
1.0 nm. The 1H NMR spectrum of Pyr–Ru–Tpy–Au in CDCl3
showed that the peaks of the pyrrole groups appeared as broad
peaks at d 6.54 (2,5-pyrrole) and d 5.94 (3,4-pyrrole).
d 167.0, 156.6, 155.7, 148.8, 136.4, 123.5, 121.0 and 107.2
which are consistent with those of 1. The core size obtained
from TEM images of Tpy–Au is found to be 2.0 ¡ 0.4 nm
[Fig. 2(a)].
Evidence for complexation of Tpy–Au with Ru(tpy)Cl3 was
provided by NMR and UV-vis spectroscopy, and electro-
chemical data. The 13C NMR spectrum of Ru–Tpy–Au in
CD3CN showed significant doubling of the terpyridine peaks
at d 167.5, 159.3, 159.1, 156.95, 156.92, 153.7, 153.3, 138.93,
138.87, 136.2, 128.45, 128.41, 125.4, 125.3, 124.6 and 112.0.
The UV-vis spectrum of Ru–Tpy–Au in MeCN showed a
characteristic MLCT (metal-to-ligand charge transfer) transi-
tion in the visible region at 483 nm [Fig. 1(a)], indicating the
formation of a terpyridine-ruthenium complex.11 The absorp-
tion maximum at 306, 273 and 242 nm is also distinctive.
Furthermore, Fig. 1(a) shows that the plasmon resonance at
y510 nm is bigger than that of Tpy–Au shown in Fig. 1(inset),
which means the formation of large particles in comparison
with Tpy–Au. The result of the UV-vis spectrum is in good
agreement with that obtained from the TEM micrograph of
Ru–Tpy–Au, i.e., Fig. 2(b) shows an increase in the particle
size by addition of Ru(tpy)Cl3 with heating. The particle size
of Ru–Tpy–Au is 5.5 ¡ 1.0 nm as measured by TEM
[Fig. 2(b)]. This finding indicates that Tpy–Au undergoes
aggregation into somewhat large particles upon addition of
Ru(tpy)Cl3. This aggregation seems to be due to heating of the
gold nanoparticles.15
The electropolymerization of Pyr–Ru–Tpy–Au was per-
formed by cyclic voltammetry (CV). The first scan of the CV of
Pyr–Ru–Tpy–Au in 0.1 M Bu4NPF6–MeCN at a GC electrode
exhibited a single irreversible oxidation wave at Ep 5 +1.16 V
(vs. Ag/0.1 M AgNO3) which seems to overlap the oxidation
peaks of the pyrrole group and the ruthenium(II)/(III) couple
(Fig. 4). Repeat scans showed an increase in the redox-peak
currents. After fifty scans, the electrode was rinsed copiously
with solvent and dipped into fresh 0.1 M Bu4NPF6–MeCN
solution. The CV of the poly(Pyr–Ru–Tpy–Au) film-modified
GC electrode showed two irreversible peaks due to terpyridine
at 21.58 and 21.91 V and one reversible redox peak due to the
Ru(II)/(III) couple at +0.95 V (DEp 5 114 mV) (Fig. 5). Thus,
polypyrrole metal nanoparticles bearing a Ru-terpyridine
complex are readily immobilized on metal electrode surfaces
Fig. 4 Oxidative electropolymerization of Pyr–Ru–Tpy–Au by
repeated potential scans on a GC electrode in 0.1 M Bu4NPF6–
MeCN; scan rate 100 mV s21
Fig. 3 Cyclic voltammogram of Ru–Tpy–Au on a GC electrode in
0.1 M Bu4NPF6–MeCN; scan rate 100 mV s21
.
.
This journal is ß The Royal Society of Chemistry 2005
J. Mater. Chem., 2005, 15, 960–964 | 963

View Article Online
Acknowledgements
This work was supported in part by the Grant-in-Aid for
Scientific Research No. 15550044 from the Ministry of
Education, Science and Culture, Japan.
Masayuki Ito, Takashi Tsukatani and Hisashi Fujihara*
Department of Applied Chemistry and Molecular Engineering Institute,
Kinki University, Kowakae, Higashi-Osaka 577-8502, Japan.
E-mail: h-fuji@apch.kindai.ac.jp
References
1 G. Schmid, Clusters and Colloids; VCH, Weinheim, 1994.
2 D. L. Feldheim and C. A. Foss, Jr., Metal Nanoparticles, Marcel
Dekker, Inc., New York, 2002.
3 G. Schmid, Nanoparticles, Wiley-VCH, Weinheim, 2004.
4 M. Brust, M. Walker, D. Bethell, D. J. Schiffrin and R. Whyman,
J. Chem. Soc., Chem. Commun., 1994, 801.
Fig. 5 Cyclic voltammogram of poly(Pyr–Ru–Tpy–Au) film-
modified GC electrode in 0.1 Bu4NPF6–MeCN; scan rate
100 mV s21
M
.
by electrodeposition. This finding indicates the possibility
for the immobilization of metal nanoparticles having several
kinds of functional molecules on metal electrode surfaces. To
our knowledge, this is the first example of polypyrrole
nanocomposite films containing metal complex and metal
nanoparticles.
5 A. C. Templeton, W. P. Wuelfing and R. W. Murray, Acc. Chem.
Res., 2000, 33, 27.
6 H. Fujihara and H. Nakai, Langmuir, 2001, 17, 6393.
7 A. Deronzier and J. C. Moutet, Acc. Chem. Res., 1989, 22, 249;
D. Curran, J. Grimshaw and S. D. Perera, Chem. Soc. Rev., 1991,
20, 391; S. Sadki, P. Schottland, N. Brodie and G. Sabouraud,
Chem. Soc. Rev., 2000, 29, 283.
8 A. Doron, E. Katz and I. Willner, Langmuir, 1995, 11, 1313;
A. N. Shipway, E. Katz and I. Willner, ChemPhysChem, 2000,
1, 18; A. N. Shipway and I. Willner, Chem. Commun., 2001,
2035.
9 Z. Peng, E. Wang and S. Dong, Electrochem. Commun., 2002, 4,
210.
10 K. Hata and H. Fujihara, Chem. Commun., 2002, 2714.
11 (a) E. C. Constable and P. Harverson, Inorg. Chim. Acta, 1996,
252, 9; (b) G. R. Newkome, E. He, L. A. Godinez and G. R. Baker,
J. Am. Chem. Soc., 2000, 122, 9993 and references therein.
12 E. C. Constable and M. D. Ward, J. Chem. Soc., Dalton Trans.,
1990, 1405.
Conclusion
We have demonstrated that the reduction of an Au(III)
compound in the presence of the terpyridinylthiol results in
the formation of terpyridinylthiolate monolayer-protected
gold nanoparticles which are converted into ruthenium-
coordinated terpyridine-functionalized gold nanoparticles.
Thus metal complexation can be achieved without decomposi-
tion of the nanoparticles. The ligand-exchange reaction of Ru–
Tpy–Au with a pyrrolylthiol gave Pyr–Ru–Tpy–Au bearing
electropolymerizable sites and metal complex which provides a
new type of poly(metal nanocomposite) films-modified elec-
trode. Such ruthenium nanocomposite materials are of special
interest, as they have applications to sensor devices, catalysis,
and nanoelectronics. Further work is currently in progress in
this and related areas.
13 P. A. Adcock, F. R. Keene, R. S. Smythe and M. R. Snow, Inorg.
Chem., 1984, 23, 2336.
14 The broadening effects of 1H NMR signals in alkanethiolate-
stabilized gold nanoparticles have been discussed5.
15 M. M. Maye, W. Zheng, F. L. Leibowitz, N. K. Ly and
C.-J. Zhong, Langmuir, 2000, 16, 490; M. M. Maye and
C.-J. Zhong, J. Mater. Chem., 2000, 10, 1895; T. Teranishi,
S. Hasegawa, T. Shimizu and M. Miyake, Adv. Mater., 2001, 13,
1699.
964 | J. Mater. Chem., 2005, 15, 960–964
This journal is ß The Royal Society of Chemistry 2005