Synthesis and characterization of ultrathin metal coordination Prussian blue nanoribbons

Article abstract of DOI:10.1039/c3dt00060e

Ultrathin metal coordination Prussian blue (PB) nanoribbons with tunable width have been successfully synthesized. The morphology and microstructure of PB nanoribbons are characterized using UV-vis, FT-IR, AFM, TEM and XRD. PB nanoribbons synthesized possess an ultrathin thickness of approximately 1 nm and narrow width. The width of PB ribbons can be tuned by varying the chain length of polymeric precursors. The PB hybrid nanoribbons synthesized exhibit enhanced thermal stability and electrochemical activity. The merit of narrow and tunable width as well as ultrathin thickness of PB hybrid nanoribbons along with enhanced thermal stability and electrochemical activity makes them potentially useful in nano-devices, biosensors and so on.

Full text of DOI:10.1039/c3dt00060e

Dalton
Transactions
View Article Online
View Journal | View Issue
COMMUNICATION
Synthesis and characterization of ultrathin metal
coordination Prussian blue nanoribbons†
Cite this: Dalton Trans., 2013, 42, 5242
Received 8th January 2013,
Accepted 18th February 2013
a
a
a
a,b
a,b
Suping Bao, Wangping Qin, Qihua Wu, Guodong Liang,* Fangming Zhu and
Qing Wu
a,b
DOI: 10.1039/c3dt00060e
www.rsc.org/dalton
6
Ultrathin metal coordination Prussian blue (PB) nanoribbons with synthesize hollow nanoparticles of PB. More recently, PB
tunable width have been successfully synthesized. The mor- nanoparticles with tunable sizes have been synthesized in the
7
,8
phology and microstructure of PB nanoribbons are characterized presence of polymeric templates. However, the synthesis of
4
using UV-vis, FT-IR, AFM, TEM and XRD. PB nanoribbons syn- highly anisotropic PB nanomaterials has been rarely reported.
thesized possess an ultrathin thickness of approximately 1 nm
Nanoribbons featuring narrow and straight-edged stripes
and narrow width. The width of PB ribbons can be tuned by represent promising building blocks or connecting units for
varying the chain length of polymeric precursors. The PB hybrid applications in nano-devices due to their intriguing structure-
9
nanoribbons synthesized exhibit enhanced thermal stability and related physical properties. Although nanoribbons of a
electrochemical activity. The merit of narrow and tunable width number of inorganic or organic materials have been syn-
as well as ultrathin thickness of PB hybrid nanoribbons along thesized, including graphene nanoribbons prepared by ex-
9
a
9b
with enhanced thermal stability and electrochemical activity foliating graphite,
unzipping of carbon nanotubes
or
9
c
makes them potentially useful in nano-devices, biosensors and so chemical vapor deposition processes, metal oxide or sulfide
on.
nanoribbons by thermal evaporation and condensation proces-
ses, dithioperylene nanoribbons by solution processes etc.,
9
d
9e
the preparation of nanoribbons with narrow width (<10 nm),
in which quantum confinement and the edge effect are signifi-
cant, remains challenging. Polypeptides, as one of the most
Introduction
9
f
Intense endeavors have been devoted to the construction of important components of proteins, are able to arrange into α
metal coordination nanomaterials with varied morphologies helix and β fold structures due to supramolecular interaction
1
0
due to their versatile properties including reversible redox among amino acid units. Such highly anisotropic structures
activity, superior thermal stability, excellent mechanical offer a new opportunity for the achievement of nanoparticles
strength and so on, which give rise to a wide range of potential with unique architectures. Herein, we report the synthesis of
1
,2
applications in nano-devices.
Since Mann and coworkers PB hybrid nanoribbons with ultrathin thickness and tunable
synthesized metal coordination nanocubes of Prussian blue width using a cyanoferrate modified polypeptide as the precur-
3
(
PB) in reverse microemulsions, numerous approaches have sor. We demonstrate that the PB hybrid nanoribbons exhibit
been developed to regulate the morphology of PB. Talham and enhanced thermal stability and electrochemical activity.
coworkers have synthesized two-dimensional PB grids through
metal coordination of an amphiphilic pentacyanoferrate
4
complex at the air–water interface. MacLachlan and coworkers
have prepared PB nanoworms and nanocontainers by means
Results and discussion
of self organization of the ferrate-containing diblock copoly- Synthesis of PB hybrid nanoribbons
5
mers. Mini-emulsion droplets have also been used to
To synthesize PB hybrid nanoribbons, a 4-armed star poly-
(
γ-benzyl-L-glutamate) modified with NH Na [Fe(II)(CN) -
4
2
5
a
DSAPM Lab, Institute of Polymer Science, School of Chemistry and Chemical
(4-(aminomethyl)pyridine)] (PBLG–Fe, 6) was used (synthesis,
ESI†). In a typical experiment, 50 mg PBLG–Fe was suspended
in 10 mL distilled water with the assistance of sonication to
Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China.
E-mail: lgdong@mail.sysu.edu.cn; Tel: +86-20-84114033
b
PCFM Lab, OFCM Institute, Sun Yat-Sen University, Guangzhou, 510275,
3+
get a light green suspension. Upon addition of Fe aqueous
P. R. China
solution, the color of the suspension changed to light blue in
a few minutes, suggesting the formation of PB. The color
†
Electronic supplementary information (ESI) available: AFM height images of
PB hybrid nanoribbons and synthesis of PBLG–Fe. See DOI: 10.1039/c3dt00060e
5
242 | Dalton Trans., 2013, 42, 5242–5246
This journal is © The Royal Society of Chemistry 2013

View Article Online
Dalton Transactions
Communication
Fig. 3 Tapping mode AFM image (a) with a size of 600 nm × 600 nm, TEM
image (b) of PB hybrid nanoribbons and EDX spectrum (c).
Fig. 1 UV-vis spectra of PBLG–Fe aqueous solution with various amounts of
Prussian blue monolayers. PBLG–Fe is amphiphilic. When
PBLG–Fe self organizes in aqueous media, hydrophobic PBLG
layers are sandwiched between two hydrophilic ferrate layers.
Subsequent coordination polymerization of the cyanoferrate
Fe +. The concentration of PBLG–Fe was 0.30 mg mL−1
3
.
3
+
complex with Fe leads to the formation of tri-layered struc-
tures consisting of a PBLG layer sandwiched between two PB
monolayers. Moreover, the width of PB hybrid nanoribbons
was close to the chain length of fully extended PBLG–Fe macro-
molecules, implying that PBLG macromolecules aligned per-
pendicular to the long axes of the ribbons. A typical TEM
image of PB hybrid nanoribbons with widths of ca. 10 nm is
shown in Fig. 3. Some sets of parallel lines with the interline
distance of ca. 0.5 nm aligned perpendicular to the long axis
of the ribbons were discerned in TEM images. The endeavor to
obtain EDX elemental mapping was unsuccessful due to rapid
degradation of nanoribbons upon exposure to intense electron
beams, likely associated with the ultrathin thickness. EDX
analysis confirmed the presence of iron in PB hybrid
nanoribbons.
Fig. 2 FT-IR spectra for PBLG, PBLG–Fe and PB hybrid nanoribbons.
change implies that the cyanoferrate complex is accessible to
3
+
Fe and is located on the surface of the PBLG–Fe assembly,
Microstructure of PB hybrid nanoribbons
3
+
which enables the subsequent coordination with Fe . UV-vis
Polypeptides such as PBLG exhibit secondary structures
induced by intramolecular and intermolecular hydrogen
3
+
results revealed that addition of Fe led to the appearance of
the absorbance band at 721 nm (Fig. 1), attributed to charge
1
0
bonding in bulk or in solution. The secondary structure of
PBLG depending on its molar mass can be verified using
FT-IR. The FT-IR spectrum of PBLG showed two distinct absor-
1
1
transfer of Fe(II)–CN–Fe(III). The intensity of the absorbance
3
+
band increased with increasing Fe amounts until molar
3
+
3+
equivalent Fe was added, illustrating that Fe is involved in
the coordination polymerization reaction. The FT-IR spectrum
bance bands at 1628 cm− and 1529 cm (Fig. 2), being
characteristic of β sheets with anti-parallel configuration,
ascribed to the CvO and C–N stretching vibrations, respective-
1
−1
−
1
of PBLG–Fe showed an absorbance band at 2060 cm attribu-
table to the CuN stretching vibration (Fig. 2). This band
shifted to 2078 cm− after coordination polymerization due to
1
0a
ly.
These bands remained for PBLG–Fe and PB hybrid
1
nanoribbons, demonstrating that inclusion of the ferrate
complex and formation of PB did not change the secondary
structure of the β sheets of PBLG.
1
2
the formation of the Fe(II)–CN–Fe(III) bridge.
Morphology of PB hybrid nanoribbons
The microstructure of PBLG, PBLG–Fe and PB hybrid
The morphology of PB hybrid nanoribbons fabricated was nanoribbons was characterized by means of wide-angle X-ray
characterized using tapping mode atomic force microscopy diffraction (XRD), as shown in Fig. 4. Two distinct reflections
(
AFM) and transmission electron microscopy (TEM). A typical at 2θ = 5.4° and 2θ = 18.7°, attributed to lamellar stacking of β
7
a
AFM image revealing ribbon-like structures is shown in Fig. 3. sheets and the intermolecular distance between adjacent
7
d
Cross-sectional analysis illustrated that the thickness of PB macromolecules within individual β sheets,
hybrid nanoribbons was ca. 1 nm and the width was 9.7 nm were observed for PBLG. The reflection peak at 2θ = 5.4° (d =
Fig. S1, ESI†). The thickness of PB hybrid nanoribbons was 1.61 nm) for PBLG shifted to a lower angle 2θ = 5.3° (d =
similar to that of a single PBLG layer sandwiched between two 1.67 nm) for PBLG–Fe, revealing that substitution of the benzyl
respectively,
(
This journal is © The Royal Society of Chemistry 2013
Dalton Trans., 2013, 42, 5242–5246 | 5243

View Article Online
Communication
Dalton Transactions
delamination of stacked β sheets and the formation of
nanoribbons.
The PBLG–Fe aqueous suspension after sonication was not
stable, and flocculation occurred if left to stand over 30 min.
3
+
After coordination polymerization with Fe and forming PB
hybrid nanoribbons, the suspension was stable over 3 days,
revealing that the formation of PB layers improved the dis-
persion of hybrid ribbons in aqueous media.
Tuning width of PB hybrid nanoribbons
PB hybrid nanoribbons consisted of PBLG–Fe macromolecules
aligned perpendicular to the long axes, as implied by morpho-
logical analysis. This means that the width of the nanoribbons
is related to the chain length of PBLG–Fe, and the shorter
chain length of PBLG–Fe must lead to narrower nanoribbons.
This finding encouraged us to regulate the width of PB hybrid
nanoribbons by varying the chain length of the PBLG–Fe,
which can be readily achieved by varying the monomer/
initiator ratio in the PBLG synthesis process.
Fig. 4 X-ray diffraction (XRD) curves of conventional PB, PBLG, PBLG–Fe and PB
hybrid nanoribbons.
ester moiety with the bulky ferrate complex enlarged slightly
the gallery distance of the β sheets of PBLG. In contrast, this
peak disappeared completely for PB hybrid nanoribbons, illus-
trating irreversible delamination of stacked β sheets. This
result was in good agreement with the morphological analysis.
Moreover, the diffraction peak at 2θ = 18.7° (d = 0.48 nm)
remained for PBLG–Fe and PB hybrid nanoribbons, indicating
that the intermolecular arrangement of PBLG (individual β
sheets) was retained. A broad “amorphous halo” at 2θ = ∼23°
was observed for all samples investigated, derived mainly from
the long amorphous side-chains. Moreover, it was worth
noting that no reflection peaks from PB crystals were detected
for PB hybrid nanoribbons, which implied that PB nanolayers
in ribbons were amorphous, likely due to the ultrathin thick-
ness of PB nanolayers.
We next synthesized PB hybrid nanoribbons with narrower
width using PBLG–S–Fe with a decreased molar mass of 5.8 kg
−
1
mol (synthesis, ESI†). The typical AFM image and cross-sec-
tional profile of nanoribbons (Fig. S3, ESI†) showed that PB
hybrid nanoribbons had a similar thickness of 1 nm and a
decreased width of 6.1 nm, as expected.
Thermal property of PB hybrid nanoribbons
The thermal stability of PB hybrid nanoribbons was evaluated
using thermogravimetric analysis (TGA) (Fig. 5). PBLG began
to decompose mainly at 250 °C with a maximum decompo-
sition rate at 280 °C. Decomposition of PBLG almost ceased
above 500 °C and PBLG lost 88% of its initial mass. However,
PB hybrid nanoribbons only lost 20% of their initial mass even
at high temperature (500 °C), which indicated that PB hybrid
Understanding the formation of PB hybrid nanoribbons
PBLG–Fe before sonication consisted of stacked β sheets, as nanoribbons possessed significantly enhanced thermal stab-
revealed by FT-IR and XRD results. PBLG–Fe can not be dis- ility in contrast to PBLG. The possible reason is that sandwich-
persed in water even with vigorous stirring. When a PBLG–Fe ing of PBLG layers between inorganic PB nanolayers restricts
aqueous mixture was subjected to sonication for 10 min, the mobility of PBLG macromolecules, which prevents radical
PBLG–Fe aggregates disappeared and a homogeneous clear species produced during thermal decomposition from
solution was obtained. The morphology of PBLG–Fe after soni-
cation was examined using TEM (Fig. S2, ESI†). Ribbon-like
structures, rather than stacked sheets or lamellae, were
observed. This showed that the stacked β sheets of PBLG–Fe
were delaminated into ribbon-like structures during sonication
of the PBLG–Fe aqueous suspension. Hydrophobic pristine
PBLG was unable to disperse in water even using high-power
sonication for long durations. Consequently, incorporation of
the ferrate complex into PBLG–Fe was crucial for the delamina-
tion of stacked β sheets of PBLG and the resulting formation
of nanoribbons. Two possible reasons account for the ferrate-
incorporation induced delamination of PBLG–Fe: (1) inclusion
of the bulky cyanoferrate complex enlarges the gallery distance
of the β sheets of PBLG–Fe, as verified by XRD measurement
(Fig. 4); (2) electrostatic repulsion among the negatively-
Fig. 5 Thermogravimetric analysis traces of PBLG, PBLG–Fe and PB hybrid
charged ferrate complex ions of the β sheets is helpful for the nanoribbons under N
2
.
5
244 | Dalton Trans., 2013, 42, 5242–5246
This journal is © The Royal Society of Chemistry 2013

View Article Online
Dalton Transactions
Communication
nanoribbons together with their structure-related enhanced
properties made them useful in nano-devices, biosensors and
so on.
Experimental section
Synthesis of PB hybrid nanoribbons
To synthesize PB hybrid nanoribbons, 50 mg PBLG–Fe (syn-
thesis, ESI†) was suspended in 10 mL distilled water with the
assistance of sonication. To the PBLG–Fe suspension was
3 3
added a 2 molar equivalent Fe(NO ) aqueous solution. The
mixture was stirred for 12 h at room temperature. The result-
ing solution was added dropwise to 100 mL cold methanol
with stirring. The mixture was centrifuged and the top layer
was decanted. The solid was rinsed with methanol (50 mL × 3)
and dried in a vacuum at 40 °C overnight to give light blue
powders.
Fig. 6 Cyclic voltammogram of PB hybrid nanoribbons and conventional PB
particles deposited on glassy carbon electrodes. In 0.1 M KCl solution, scan rate:
−1
5
2
0 mV min , under N .
Characterization
propagating. Moreover, thermal insulating PB nanolayers are
inclined to inhibit heat flow during degradation.
A field emission gun TEM microscope (JEM2010HR) equipped
with an Oxford Instrument UTW ISIS EDX system was used to
characterize the microstructure of PB hybrid nanoribbons. The
acceleration voltage was 200 kV. The sample was prepared by
drying a drop of PB hybrid nanoribbon/water suspension on a
carbon-coated copper grid. The specimen was directly
observed without staining due to the presence of iron. Tapping
mode AFM to investigate the three-dimensional morphology of
PB nanoribbons was performed using a commercial atomic
Electrochemical behavior of PB hybrid nanoribbons
The electrochemical behavior of PB hybrid nanoribbons was
measured by using cyclic voltammograms (CVs). A typical CV
curve of conventional PB particles showed two sets of distinct
redox pairs, located at E1/2 = 0.18 V with a peak separation of
2
(
5 mV and at E1/2 = 0.86 V with a peak separation of 45 mV
Fig. 6), ascribed to reversible Prussian white/Prussian blue
and Berlin green (or Prussian yellow)/Prussian blue conver-
force microscope (SPM-9500J3) with a silicon micro-cantilever
1
(
spring constant 30 N m− and resonance frequency ∼270
kHz). The scan rate varied from 0.1 to 2.0 Hz to optimize the
image quality. X-ray diffraction (XRD) measurements were per-
formed using an XRD diffractometer (D-MAX 2200 VPC)
equipped with Ni-filtered Cu Kα radiation, having a wavelength
1
3
sion, respectively. Both the former and the latter redox pairs
with peak separations of 33 mV and 56 mV, respectively, were
observed for PB hybrid nanoribbons, demonstrating regular
PB structures with homogeneous charge distribution through
PB layers. The redox peak separations of PB hybrid nano-
ribbons, associated with the diffusion rates of redox species to
the electrode, were comparable to those of three-dimensional
of 0.154 nm. The diffractometer was scanned in 2θ range from
1
1
.5° to 50° and the scan rate used was 1.2° min− . The TGA
curves were recorded using a NetzschTG-209 thermo-balance
in a temperature range from 25 to 550 °C at a heating rate of
(3D) PB particles. This revealed that PB hybrid nanoribbons
1
1
0 °C min− under nitrogen. UV-vis spectroscopy data were
possessed similar charge diffusion rates to 3D PB particles,
despite the amorphous nature of PB layers and the low fraction
of PB in hybrid ribbons.
obtained by using a Hitachi U3500 at room temperature. FT-IR
spectra were recorded using a Nicolet/Nexus 670 FT-IR spectro-
photometer. Powder samples were mixed with KBr and then
pressed into pellets for FT-IR measurements. Cyclic voltamme-
try was performed using a CHI-660D electrochemical analyzer
(
CH Instruments, Inc.) in a three electrode cell. Glassy carbon
Conclusions
working electrodes with a diameter of 3 mm were polished
In summary, metal coordination Prussian blue (PB) nano- with a slurry of 0.05 μm alumina particles, sonicated and
ribbons with ultrathin thickness and tunable width were syn- rinsed with ultrapure water. After drying under N , the glassy
thesized for the first time. PB hybrid nanoribbons consisted of carbon working electrodes were made hydrophilic by treating
a single PBLG layer with macromolecules aligned perpendicu- in oxygen plasma (1 Torr O , 10 W) for 5 min. The cleaning
2
2
lar to the long axes of ribbons, sandwiched between two amor- process was repeated until no voltammetric features were
phous PB nanolayers. TGA results illustrated that PB hybrid observed in the range from −0.2 to 1.2 V (vs. Ag/AgCl) at the
nanoribbons exhibited enhanced thermal stability. CV results scan rate of 100 mV s− in 0.1 M KCl solution. PB hybrid
revealed that PB hybrid nanoribbons were electrochemically nanoribbons/water suspension was deposited on freshly
active. The intriguing microstructure of PB hybrid cleaned glassy carbon working electrodes. The solvent was
1
This journal is © The Royal Society of Chemistry 2013
Dalton Trans., 2013, 42, 5242–5246 | 5245

View Article Online
Communication
Dalton Transactions
allowed to evaporate at room temperature overnight. 0.1 M KCl
solution was used as a buffer solution. To remove oxygen, the
buffer solution was degassed by bubbling N for 40 min prior
2
to CV measurements. Every sample was tested three times to
obtain reproducible results.
(b) M. Hu, S. Furukawa, R. Ohtani, H. Sukegawa,
Y. Nemoto, J. Reboul, S. Kitagawa and Y. Yamauchi, Angew.
Chem., Int. Ed., 2012, 51, 984–988; (c) N. L. Torad, M. Hu,
M. Imura, M. Naito and Y. Yamauchi, J. Mater. Chem.,
2012, 22, 18261–18267; (d) M. Hu and Y. Yamauchi, Chem.
Asian J., 2011, 6, 2282–2286; (e) M. Hu, A. A. Belik,
H. Sukegawa, Y. Nemoto, M. Imura and Y. Yamauchi,
Chem. Asian J., 2011, 6, 3195–3199.
Acknowledgements
8
9
(a) A. Tokarev, P. Agulhon, J. Long, F. Quignard,
M. Robitzer, R. A. S. Ferreira, L. D. Carlos, J. Larionova,
C. Guerin and Y. Guari, J. Mater. Chem., 2012, 22, 20232–
Financial support in part from NSFC (21074151), the Guangz-
hou Planning Project of Science and Technology
(11C52050729), the One Hundred Talents Project of Sun
20242; (b) B. Folch, J. Larionova, Y. Guari, K. Molvinger,
Yat-Sen University, the SRF for ROCS and SEM, and the Hong
Kong Scholar Program (XJ2011047) is gratefully acknowledged.
C. Luna, C. Sangregorio, C. Innocenti, A. Caneschi and
C. Guerin, Phys. Chem. Chem. Phys., 2010, 12, 12760–12770.
(a) X. L. Li, X. R. Wang, L. Zhang, S. W. Lee and H. J. Dai,
Science, 2008, 319, 1229–1232; (b) D. V. Kosynkin,
A. L. Higginbotham, A. Sinitskii, J. R. Lomeda, A. Dimiev,
B. K. Price and J. M. Tour, Nature, 2009, 458, 872–876;
(c) W. Liu, B. L. Jackson, J. Zhu, C. Q. Miao, C. H. Chung,
Y. J. Park, K. Sun, J. Woo and Y. H. Xie, ACS Nano, 2010, 4,
3927–3932; (d) Y. Jiang, W. J. Zhang, J. S. Jie, X. M. Meng,
J. A. Zapien and S. T. Lee, Adv. Mater., 2006, 18, 1527–1532;
(e) W. Jiang, Y. Zhou, H. Geng, S. D. Jiang, S. K. Yan,
W. P. Hu, Z. H. Wang, Z. G. Shuai and J. A. Pei, J. Am.
Chem. Soc., 2011, 133, 1–3; (f) J. M. Cai, P. Ruffieux,
R. Jaafar, M. Bieri, T. Braun, S. Blankenburg, M. Muoth,
A. P. Seitsonen, M. Saleh, X. L. Feng, K. Mullen and
R. Fasel, Nature, 2010, 466, 470–473.
Notes and references
1
P. A. Rupar, L. Chabanne, M. A. Winnik and I. Manners,
Science, 2012, 337, 559–562.
2
(a) F. H. Schacher, P. A. Rupar and I. Manners, Angew.
Chem., Int. Ed., 2012, 51, 7898–7921; (b) R. Ahmed,
A. Priimagi, C. F. J. Faul and I. Manners, Adv. Mater., 2012,
2
4, 926–931; (c) J. B. Gilroy, S. K. Patra, J. M. Mitchels,
M. A. Winnik and I. Manners, Angew. Chem., Int. Ed., 2011,
0, 5851–5855.
(a) S. Vaucher, M. Li and S. Mann, Angew. Chem., Int. Ed.,
000, 39, 1793–1796; (b) S. Vaucher, J. Fielden, M. Li,
E. Dujardin and S. Mann, Nano Lett., 2002, 2, 225–229.
5
3
2
4
5
J. T. Culp, J. H. Park, D. Stratakis, M. W. Meisel and 10 (a) P. Papadopoulos, G. Floudas, H. A. Klok, I. Schnell and
D. R. Talham, J. Am. Chem. Soc., 2002, 124, 10083–10090.
(a) X. Roy, J. K. H. Hui, M. Rabnawaz, G. J. Liu and
M. J. MacLachlan, J. Am. Chem. Soc., 2011, 133, 8420–8423;
T. Pakula, Biomacromolecules, 2004, 5, 81–91; (b) K. T. Kim,
C. Park, C. Kim, M. A. Winnik and I. Manners, Chem.
Commun., 2006, 1372–1374; (c) K. T. Kim, C. Park,
G. W. M. Vandermeulen, D. A. Rider, C. Kim, M. A. Winnik
and I. Manners, Angew. Chem., Int. Ed., 2005, 44,
7964–7968; (d) Y. C. Lin and S. W. Kuo, J. Polym. Sci., Part
A: Polym. Chem., 2011, 49, 2127–2137.
(b) X. Roy, J. K. H. Hui, M. Rabnawaz, G. J. Liu and
M. J. MacLachlan, Angew. Chem., Int. Ed., 2011, 50, 1597–1602.
(a) R. McHale, N. Ghasdian, Y. B. Liu, M. B. Ward,
N. S. Hondow, H. H. Wang, Y. Q. Miao, R. Brydson and
6
X. S. Wang, Chem. Commun., 2010, 46, 4574–4576; 11 (a) F. Armand, H. Sakuragi and K. Tokumaru, New J. Chem.,
(
b) S. J. Ye, Y. B. Liu, S. J. Chen, S. Liang, R. McHale,
1993, 17, 351–356; (b) S. H. Toma, J. A. Bonacin, K. Araki
and H. E. Toma, Eur. J. Inorg. Chem., 2007, 3356–3364.
N. Ghasdian, Y. Lu and X. S. Wang, Chem. Commun., 2011,
4
7, 6831–6833; (c) G. D. Liang, J. T. Xu and X. S. Wang, 12 (a) S. F. A. Kettle, E. Diana, E. Boccaleri and
J. Am. Chem. Soc., 2009, 131, 5378–5379; (d) Y. B. Liu and
X. S. Wang, Polym. Chem., 2012, 3, 2632–2639.
(a) H. Ming, N. L. K. Torad, Y. D. Chiang, K. C. W. Wu and
P. L. Stanghellini, Inorg. Chem., 2007, 46, 2409–2416;
(b) S. Z. Zhan, D. Guo, X. Y. Zhang, C. X. Du, Y. Zhu and
R. N. Yang, Inorg. Chim. Acta, 2000, 298, 57–62.
7
Y. Yamauchi, CrystEngComm, 2012, 14, 3387–3396; 13 A. A. Karyakin, Electroanalysis, 2001, 13, 813–819.
5
246 | Dalton Trans., 2013, 42, 5242–5246
This journal is © The Royal Society of Chemistry 2013