Aryl-diamide bridged binuclear ruthenium (II) tris(bipyridine) complexes: Synthesis, photophysical, electrochemical and electrochemiluminescence properties

Article abstract of DOI:10.1016/j.jorganchem.2006.06.034

Several new symmetrical aromatic hydrocarbon bridged bipyridine ligands and their binuclear Ru (II) complexes have been designed, synthesized and characterized on the basis of ¹H NMR, MS and HRMS. Their absorption and emission properties, elect

Full text of DOI:10.1016/j.jorganchem.2006.06.034

Journal of Organometallic Chemistry 691 (2006) 4189–4195
www.elsevier.com/locate/jorganchem
Aryl-diamide bridged binuclear ruthenium (II)
tris(bipyridine) complexes: Synthesis, photophysical,
electrochemical and electrochemiluminescence properties
a
a,
b
a,c,
*
Minna Li , Jianhui Liu *, Changzhi Zhao , Licheng Sun
a
State Key Laboratory of Fine Chemicals, Dalian University of Technology, School of Chemical Engineering,
Zhong Shan Road 158-46, 116012, Dalian, PR China
College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, PR China
b
c
KTH Chemistry, Organic Chemistry, Royal Institute of Technology, 10044 Stockholm, Sweden
Received 21 February 2006; received in revised form 12 June 2006; accepted 21 June 2006
Available online 4 July 2006
Abstract
Several new symmetrical aromatic hydrocarbon bridged bipyridine ligands and their binuclear Ru (II) complexes have been designed,
1
synthesized and characterized on the basis of H NMR, MS and HRMS. Their absorption and emission properties, electrochemical
behaviors and electrochemical luminescence were investigated. All ruthenium complexes show characteristic MLCT absorption and sim-
ilar redox potential. Among the three complexes reported, 4c has the best electrochemical luminescence property.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Binuclear ruthenium complexes; Electrochemiluminescence; Polypyridine ligands; Synthesis
1. Introduction
potential ECL active substances owing to their multiple
redox centers [10]. In recent studies, complexes with two
or three ruthenium polypyridyl units connected by a bridg-
ing ligand of proporxycarbonyl linker amino acid lysine or
the related dipeptide (LysLys) showed that the ECL inten-
sity increases by 30% [11].
On the other hand, significant advances have been
achieved recently in the design of electroluminescence mol-
ecules of aryl ethylene type [12], e.g., phenylenevinylenes
oligomer and phenyl thiophenevinylenes oligomers. Its
extension of a p-conjugation system has brought changes
in the properties of such assembly, leading to a better elec-
tron communications. More importantly, polynuclear
ruthenium complex units can be connected through conju-
gate system by triple bond and aromatic ring [13]. Signifi-
cant example is the ruthenium tris(bipyridine) bridged
with tetraphenylene, which shows fully reversible voltage-
dependent switching between green and red light emission
[14]. Based on this observation, we would like to examine
the EL or ECL for the system of aromatic ring alternatively
The design and synthesis of molecules that have reliable
electrogenerated chemiluminescence (ECL) properties are
attracting considerable interests [1]. Typically, aromatic
hydrocarbons [2] and their derivatives [3] are used either
by themselves or by the incorporation to a metal complex
[4] as an ECL candidate. One of the most widely used metal
complexes is the ruthenium tris(bipyridine) [Ru(bpy)3]2+[5].
Since the first report by Bard on the electrogenerated
chemiluminescence (ECL) of [Ru(bpy)3]2+ [6], the ECL
properties of this complex have been studied extensively
and widely used in analytical applications, especially in
clinical diagnostics [7] and environmental assays [8]. Poten-
tial applications also include uses in display devices [9].
Polynuclear system based complexes seem to be the most
*
Corresponding authors. Tel.: +86 411 88993886; fax: +86 411
83072185.
E-mail address: liujh@dlut.edu.cn (J. Liu).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.06.034

4190
M. Li et al. / Journal of Organometallic Chemistry 691 (2006) 4189–4195
coupled with double or triple bond. However, in some
cases, the construction for such molecules encountered
great difficulties, although the synthetic methodology has
been established, for example, by transition metal catalyzed
coupling reaction [15].
an effort has been made to develop this new class of mole-
cule that shows excellent ECL properties, including the
design and synthesis.
2. Results and discussion
We are clearly aware that the amide bond might be a
good candidate for the replacement of the double or triple
bond, since it has considerable double bond characters due
to the conjugation. The lone pair electrons on nitrogen can
delocalize into the carbonyl group. In addition, the amide
group provides a natural point of attachment to other
structure subunit due to the facile synthesis by the connec-
tion of acid chloride with amine. However, to the best of
our knowledge, amide-containing compounds are quite
rare used as ECL material, and there have been very scat-
tered examples containing the amide bond as connections
for the construction of substances with electroluminescence
properties [16]. To investigate this possibility, we designed
a new kind of molecules showed as follows:
2.1. Synthesis and characterization
In connection with our studies on the synthesis of
tris(bipyridine) ruthenium complexes, we need to prepare
the key ligand 3a, 3b and 3c. The synthesis of our three
target ligands was carried out as outlined in Scheme 1.
1,4-Phenylenediamine reacted with 40-methyl-2,20-bipyridi-
nyl- 4-carbonyl chloride (prepared from 4,40-dimethyl-2,
20-bypyridine) [17] in the presence of Et3N to form phe-
nyl-centered bipyridine ligand 3a in good yield. The other
two ligands 3b and 3c were prepared in the similar manner.
These compounds proved extremely insoluble in even the
most polar aprotic solvents, making both purification
and characterization difficult. Therefore for these three
ligands, it is rather difficult to perform their 13C NMR.
Nevertheless, the structures of the three aryl diamides were
well confirmed by 1H NMR. It was worth mentioning that
the experiment condition for the synthesis of the ligands
was vital. Higher temperature or longer reaction time
yielded other by-products.
N
N
N
N
N
N
O
O
-
Ru
Ru
N
N
4PF
N
N
6
NH Ar NH
N
N
With the three ligands in hand, the preparation of
tris(bipyridine) ruthenium complexes were accomplished
quite easily. The ligands were refluxed in EtOH–H2O
(1:1) with Ru(bpy)2Cl2 and the binuclear complexes were
purified by column chromotography to give the orange-
colored product in good yield. The structures of these com-
The covalent combination of the aromatic subunits and
ruthenium tris(bipyridine) through amide bond will be the
substitution of that connected by double or triple bond. We
are now interested in the design and synthesis of the amide-
bond containing hydrocarbons (analogue of 3 with differ-
ent central aromatic rings) 3a–3c as well as their bis-capped
ruthenium tris(bipyridine) complexes 4a–4c. In this work,
1
pounds were confirmed by H, 13C NMR, MS and each
proton was well assigned by 1H-1H COSY. Compound
4a showed an ESI+-MS molecular ion at m/z 1328.28, con-
sistent with the formula C70H56N14O2Ru2. The strong UV
N
N
O
COOH
SOCl
COCl
H N
3a, 56%
Ar NH
o
2
2
NH
Ar NH
2
N
3b, 52%
3c, 69%
reflux, 3h
THF, 50 C, 18h
O
N
N
N
N
N
1
2
N
N
N
N
N
4a, 75%
O
O
Ru(bpy) Cl
2
2
Ru
-
N
N
Ru
N
N
4PF
4b, 72%
6
EtOH/H O, reflux, 10h
2
NH Ar NH
N
4c, 77%
N
N
a
c
Ar=
b
Scheme 1. Synthetic route for ligands 3a–3c and metal complexes 4a–4c.

M. Li et al. / Journal of Organometallic Chemistry 691 (2006) 4189–4195
4191
Table 1
absorption maximum at 460 nm indicated the presence of
1
[Ru(bpy)3]2+ (Fig. 1). In the H NMR spectrum for com-
The absorption spectra for the three ruthenium complexes in CH3CN
Complexes
Absorption
max/nm
Emission
max/nm
U
plex 4a, the chemical shift for each proton in bpy ligand
(designated as b) follows the general trend order as
reported in the literature [18]: Hb3 (8.50) > Hb4
(8.06) > Hb6 (ca. 7.72) > Hb5 (7.4). Those in amide bpy
ligand (designated as a) are easy for assignment based on
the peak split. The proton on the central phenyl was
observed in d 7.82, reflecting the strong unshielding effect
k
k
Ru(bpy)32PF6
245
244
244
242
283
288
288
288
454
458
459
458
618
642
638
636
0.062
0.053
0.081
0.058
4a
4b
4c
3
1
This indicates that the MLCT excited state is almost the
same for the three complexes and have the same energy
level, no matter what kind of linkage existed in the mole-
cules. The average value of ca. 640 nm for the emission
maxima is red shifted by only ca. 20 nm from that of the
[Ru(bpy)3]2+ that it is derived from. The small difference
in emission properties of these three complexes and that
of its parent core molecule might be caused by the lack
of delocalization across the amide bond connecting the
two parts of the [Ru(bpy)3]2+ moiety. The twisting around
the central connecting bond made the full delocalization of
the molecular orbitals over the entire molecule not possi-
ble. This small difference may also reflect the strong elec-
tron accepting nature of the amide bonds. The
luminescence quantum yields for 4a and 4c are lower than
that of the reference [Ru(bpy)3]2+, while for 3b is higher to
the reference complex. A large strokes shift of ca. 170 nm
was observed between the absorption and emission spectra
maxima (see Fig. 1(b)).
compared to the average value (7.26). H NMR experi-
ments indicated that the presence of amides at d 9.34.
1
The H NMR data of 4b and 4c showed a strong resem-
blance with those of 4a, providing evidence for the presence
of Ru(bpy)3 unit. Clear differences in the 1H NMR spectra
of these compounds were only evident in the low field
region for different central aromatic moieties (phenyl,
biphenyl, and naphthalyl).
2.2. Electronic absorption and emission spectra
Absorption and emission spectra were measured in
CH3CN and shown in Fig. 1. [Ru(bpy)3]2+ was used as ref-
erence, which showed two bands at 454 and 248 nm for the
MLCT absorption, and one band at 286 nm for the ligand
centered p–p* absorption [17]. The absorption spectra for
the three target binuclear ruthenium complexes 4a, 4b
and 4c were quite similar to that of the reference
[Ru(bpy)3]2+, with a broad band at 460 nm and an observa-
ble band at 244 nm for dp (Ru) ! p*(bpy) metal to ligand
charge transfer (1MLCT) and an intense ligand centered p–
p* absorption at 288 nm. These similar maximal absorp-
tions indicate the absence of a strong electronic interaction
between the two [Ru(bpy)3]2+ units. It was noted that the
more extended conjugation for the three complexes leads
to almost no shift of the MLCT band (see Table 1).
2.3. Electrochemistry
The redox behavior of the three different aromatic
amide bridged homo-binuclear complexes 4a, 4b and 4c
was determined by cyclic voltammetry (CV) in MeCN
(c = 10ꢀ4 M) using tetrabutylammonium hexafluorophos-
phate (TBAPF6) as the supporting salt (see Fig. 2). All elec-
trochemical data for the three ruthenium complexes were
recorded in Table 2. The oxidation potentials of 4a, 4b
The emission spectra of 4a, 4b and 4c are shown in
Fig. 1b. All of these three complexes exhibited almost the
same emission maxima, centered at 642, 638 and 636 nm.
Emission
Excitation
600
500
400
300
200
100
0
1.4
4a
4b
4c
4a
4b
4c
1.2
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
350
400
450
500
550
600
650
700
750
800
850
300
400
500
600
700
800
Wavelength (nm)
a
b
Wave length(nm)
Fig. 1. (a) UV–vis absorption spectra of complexes 4a, 4b and 4c in CH3CN. (b) Excitation and emission spectra of complexes 4a, 4b and 4c in CH3CN
(10ꢀ5 M) at 25 ꢁC (kex = 457 nm, kem = 639 nm).

4192
M. Li et al. / Journal of Organometallic Chemistry 691 (2006) 4189–4195
30
20
4a
4b
4c
10
0
-10
-20
-30
-40
Fig. 3. Electrochemiluminescence spectra of complexes 4a–4c in MeCN
(1.22 · 10ꢀ4 mol/L) at room temperature.
2
1
-1
-2
-3
0
E(V)
Fig. 2. Cyclic voltammogram of complex 4, 0.1 mM in 0.05 M of n-
Bu4NPF6/CH3CN at a scan rate of 100 mV/s.
Table 3
ECL data for three ruthenium complexes
Complexes
ECL kmax/nm
ECL
ECL (a.u.)
ECL (times)
Table 2
[(bpy)3Ru(2PF6)
595
569
570
570
202
3327
447
404
3327
447
1
Electrochemical data for three ruthenium complexes
4a
4b
4c
8.2
1.1
11.5
Complexes
Ep (V)
4627
4627
Oxidation
Reduction
Ru(bpy)3Æ(2PF6)a [19]
Ru(bpy)3Æ(2PF6)
+1.35
+0.95
+1.04
+1.03
+1.01
ꢀ1.32
ꢀ1.67
ꢀ1.53
ꢀ1.52
ꢀ1.62
ꢀ1.51
ꢀ1.88
ꢀ1.73
ꢀ1.72
ꢀ1.85
ꢀ1.76
ꢀ2.15
ꢀ2.04
ꢀ2.04
ꢀ2.14
exhibited ECL emission centered around 570 nm with dif-
ferent intensities. The ECL emissions of the three com-
plexes have the same shapes, but different maxima
compared to their fluorescence spectra with red-shifted by
ca. 65 nm. Since there existed little interaction between
the two equal ruthenium tris(bipyridine) subunits based
on the UV–vis spectra and cyclic voltammograms studies,
we calculated the efficiency by comparing the number of
ruthenium tris(bipyridine) containing in the molecules.
Thus, the actual efficiency is half of that by measuring.
The relative emission intensities behaves in the following
order: 4c > 4a > 4b, respectively, 4, 0.5 and 6 times than
that of the reference compound. The reason is not clear,
but it seemed that this related to the polarity and the con-
jugation of the whole molecules. The reaction mechanism is
quite certain that electrochemically oxidized Ru (III)
reacted with radical Pr2NꢀCH2CH2CH3 which was
obtained from Pr2N+CH2CH2CH3 radical cation. The
[Ru(bpy)3]3+ was reduced to Ru(II) with concomitant for-
mation of Pr2N+@CHEt and then to give out the emission
to the ground state.
4a
4b
4c
a
Measured with SCE as reference electrode, otherwise with Ag/AgNO3
as reference electrode.
and 4c occurred in a single irreversible two electron step at
potentials Ep = +1.04, +1.03, and +1.01 V vs. Ag/Ag+
electrode, respectively, with the peak current for the oxida-
tion being noticeably larger than that for the reduction.
The cyclic voltammogram of these ruthenium binuclear
complexes show only a single oxidation wave, suggesting
further relatively little or weak interaction between the
two ruthenium centers. The oxidation potential of the pres-
ent binuclear ruthenium complex is more positive than that
obtained for the reference [Ru(bpy)3]2+(Ep = +0.95 V),
which indicates that binuclear ruthenium complex is more
difficult to be oxidized. In the cathodic region, complex 4a
exhibited three quasi-reversible reduction wave at ꢀ1.53,
ꢀ1.73, and ꢀ2.04 V. Complex 4b has also three peaks at
almost the same to that of 4a, while for 4c, the reduction
potential moved more negatively at ꢀ1.62, ꢀ1.85 and
ꢀ2.14 V, respectively.
2þ
As a reference compound, RuðbpyÞ3 has been already
widely used in analytical aspects, including the detection
of biological agents, metal cations and DNA mutations
because of its low-lying metal-to-ligand charge transfer
(MLCT) excited states, high emission quantum yield and
long excited-stated lifetimes. A comparison of the emission
2.4. Electrochemiluminescence
ECL emission spectra were recorded in the presence of
TPA with the sample concentration of 0.1 mM (see
Fig. 3). All the ECL data of the three ruthenium complexes
are shown in Table 3. The pulsed voltage was used from the
2þ
intensities of 4a–4c with the reference complex RuðbpyÞ3
proves that 4c is the most ECL-active complex with the
rigidity and planarity of the bridging aromatic unit, which
contributes much to the ECL efficiency. Thus much atten-
tion will be paid to its potential applications in above-
mentioned areas. The stronger intensity of 4c compared
2þ
first negative to first positive peak potentials. RuðbpyÞ3
was used as the reference for the measuring the relative
ECL efficiency (UECL). All three complexes 4a, 4b and 4c

M. Li et al. / Journal of Organometallic Chemistry 691 (2006) 4189–4195
4193
to the reference RuðbpyÞ23þ means the higher sensitivity and
lower detection limit, which could provide quickly access to
a wide range of analytical applications. The PFꢀ6 counter
ions in these complexes could be exchanged with Clꢀ to
improve the solubility in aqueous solution. This work is
in progress.
In conclusion, the aryl-diamide centered binuclear
ruthenium (II) tris(bipyridine) complexes 4a, 4b and 4c
are obtainable from readily available 4-methyl-2,20-bipy-
ridinyl-4-carboxylic acid aromatic diamine via the amida-
tion. ECL studies showed that 4c has much higher
emission intensity than the reference. The combination of
amide bond and central aromatic ring seems to be respon-
sible for the high efficiency of ECL. Based on these results,
work will be extended in our laboratory to the same kind of
molecules that have thiophene analogue as the bridges.
All reagents from commercial sources were used without
further purification except for the following: THF and
Et3N were distilled from sodium. p-Phenylenediamine,
2,20-bipyridine, 4,40-dimethyl-2,20-bipyridine, 4,40-dipheny-
lenediamine, 1,5-naphthalenediamine, hydrated ruthenium
trichloride, and ammonium hexafluorophosphate were
purchased from Chinese Chemicals Corporation.
40-Methyl-2,20-bipyridyl-4-carbaldehyde [20] and cis-
[Ru(bpy)2Cl2] Æ 2H2O [21] were prepared according to the
literature procedures. The serial numbers of complexes
4a, 4b and 4c are shown in Fig. 4.
3.1. Bis(40-methyl-2,20-bipyridinyl-4-carboxamide)-N,N0-
(1,4-phenylene) (3a)
A solution of 40-methyl-2,20-bipyridinyl-4-carboxylic
acid (214 mg, 1 mmol) in SOCl2 (10 mL) was refluxed for
2 h. After removing excess of SOCl2 by distillation under
reduced pressure and dried in vacuum at 70 ꢁC for 1 h
the residue was dissolved in dry THF (2 mL) and then
added dropwise to the mixture of TEA (150 mg, 1.5 mmol)
and p-phenylenediamine (54 mg, 0.5 mmol) in anhydrous
THF (20 mL) under vigorously stirring within 5 min. The
reaction mixture was left to react for 18 h under Argon
at 50 ꢁC, and then filtered on a frit. The white precipitate
was washed with THF (3 · 10 mL), water (3 · 10 mL)
and dried over 70 ꢁC under vacuum. White powder was
obtained (140 mg, 56%). 1H NMR (CD3)2SO d 2.45 (s,
6H), 7.36 (d, 2H, J = 4.8 Hz), 7.83 (s, 4H), 7.93 (d, 2H,
J = 8.8 Hz), 8.30 (s, 2H), 8.62 (d, 2H, J = 4.8 Hz), 8.86
(m, 4H), 10.73 (s, 2H); MS m/z: [M + H]+ 501.5.
3. Experimental section
General: 1H NMR at 400 MHz and 13C NMR were
recorded on a Varian spectrometer. FT-NMR instrument.
UV–vis absorption spectra were recorded on a model
8452A Hewlett–Packard diode array spectrophotometer
referenced against a solvent blank (CH3CN). Electrochem-
istry was performed with a CH Instrument Model 660. All
experiments were performed with the protection of Argon
with Bu4NPF6 as supporting electrolyte, glassy-carbon as
working electrode and Ag/AgNO3 electrode as reference.
The eluents for the column chromatography was selected
with the polarity to ensure all Rf values kept at ca. 0.2
for the better separation.
N
N
N
'
N
N
N
b
5
a
5
O
O
3
5
2
6
-
Ru
5
N
N
Ru
4PF
N
N
6
1
4
HN
NH
'
a
3
b
3
N
N
b
a '
3
3
b
a '
5
N
N
N
N
'
b5
a5
a3
O
O
3
2
-
Ru
N
N
Ru
4PF6
N
N
1
4
HN
NH
'
b3
b3
N
N
N
N
6
5
a3'
b5
a5'
N
N
'
b5
a5
a3
O
2
3
6
Ru
N
N
N
N
1
4
5
O
HN
'
-
b3
4PF6
Ru
N
N
N
N
b3
a3'
NH
8
N
N
b5
7
a5'
Fig. 4. Serial numbers of complexes 4a, 4b and 4c.

4194
M. Li et al. / Journal of Organometallic Chemistry 691 (2006) 4189–4195
3.2. Bis(40-methyl-2,20-bipyridinyl-4-carboxamide)-N,N0-
(4,40-biphenylene) (3b)
157.24, 158.05, 162.31.TOF MS ES+ Calc. 1328.2798,
M4+/4 (m/z) 332.0706; Measured. 1328.2824.
This ligand was prepared following the same procedure
as described for the preparation of 3a using 40-methyl-2,20-
bipyridinyl-4-carboxylic acid (214 mg, 1 mmol), 4, 40-diph-
enylenediamine (92 mg, 0.5 mmol) and 3 eq. of TEA to
3.5. Bis(2,20-bipyridine)-ruthenium-bis(40-methyl-2,20-
bipyridinyl-4-carbox amide)-N,N0-(1,4-biphenylene)-
ruthenium-bis(2,20-bipyridine) hexafluorophosphate (4b)
1
give a white solid (150 mg, 52%). H NMR (CD3)2SO d
The procedure for the preparation of compound 4b was
the same as that of compound 4a from bis-2,20-bipyridyl
ruthenium dichloride (55 mg, 0.11 mmol) and 3b (29 mg,
0.05 mmol) to give compound 4b after purified with aceto-
nitrile–water–saturated KNO3 (100:10:0.8) as an orange-
2.46 (s, 6H), 7.37 (d, J = 4.0 Hz, 2H), 7.75 (d, J = 8.8 Hz,
4H), 7.93 (d, J = 8.8 Hz, 4H), 7.96 (d, J = 2.0 Hz, 2H),
8.32 (s, 2H), 8.63 (d, J = 4.8 Hz, 2H), 8.88 (s, 2H), 8.90
(d, J = 5.6 Hz, 2H), 10.81 (s, 2H) MS m/z: [M + H]+
577.3 TOF MS EI+: 576.2269.
1
red solid (71 mg, 72%). H NMR (CD3CN) d 2.55 (s, 6H,
0
–CH3), 7.28 (d, 2H, J = 5.6 Hz, Ha5 ), 7.38–7.43 (m, 8H,
0
0
0
Hb5, Hb5 , Hb5, Hb5 ), 7.57 (d, 2H, J = 6.0 Hz, Ha6 ),
7.78 (d, 2H, J = 6.4 Hz, Ha5), 7.70–7.75 (m, 12H, Hb6,
3.3. Bis(40-methyl-2,20-bipyridinyl-4-carboxamide)-N,N0-
(1,5-naphthylene) (3c)
0
0
Hb6 , Hb6, Hb6 , H3, H5), 7.85 (d, 4H, J = 8.4 Hz, H2,
H6), 7.91 (d, 2H, J = 6.0 Hz, Ha6), 8.07 (t, 8H,
J = 8.0 Hz, Hb4, Hb4 , Hb4, Hb4 ), 8.50 (d, 8H,
J = 8.0 Hz, Hb3, Hb3 , Hb3, Hb3 ), 8.56 (s, 2H, Ha3 ),
8.90 (s, 2H, Ha3), 9.24 (s, 2H, N–H); 13C NMR (CD3CN)
d 20.51, 121.29, 121.99, 124.54, 125.05, 125.81, 127.36,
127.85, 129.02, 136.87, 137.62, 138.13, 143.03, 150.99,
151.09, 151.79, 151.99, 152.68, 156.20, 157.02, 157.23,
158.27, 162.42; TOF MS ES+ Calc. 1404.3084, M4+/4
(m/z) 351.0771; Measured. 1401.3084.
This ligand was prepared as the same procedure for the
preparation of 3a outlined above using 40-methyl-2,20-bipy-
ridinyl-4-carboxylic acid (214 mg, 1 mmol), 1,5-naphtha-
lenedimine (79 mg, 0.5 mmol) and 3 eq. of TEA to give a
0
0
0
0
0
1
white solid (190 mg, 69%): H NMR (CD3)2SO d 2.46 (s,
6H), 7.37 (d, J = 4.0 Hz, 2H), 7.64–7.68 (m, 4H), 8.01 (d,
J = 8.8 Hz, 2H), 8.07–8.09 (m, 2H), 8.34 (s, 2H), 8.63 (d,
J = 4.4 Hz, 2H), 8.93 (d, J = 4.0 Hz, 2H), 9.01 (s, 2H),
10.98 (s, 2H) MS m/z: [M + H]+ 551.7 TOF MS EI+:
550.2116.
3.6. Bis(2,20-bipyridine)-ruthenium-bis(40-methyl-2,20-
bipyridinyl-4-carboxamide)-N,N0-(1,5-naphthylene)-
ruthenium-bis(2,20-bipyridine) hexafluorophosphate (4c)
3.4. Bis(2,20-bipyridine)-ruthenium-bis(40-methyl-2,20-
bipyridinyl-4-carboxamide)-N,N0-(1,4-phenylene)-
ruthenium-bis(2,20-bipyridine) hexafluorophosphate (4a)
The procedure for the preparation of compound 4c was
the same as that of compound 4a from bis-2,20-bipyridyl
ruthenium dichloride (55 mg, 0.11 mmol) and 3c (28 mg,
0.05 mmol) to give compound 4c after purified with aceto-
nitrile–water–saturated KNO3 (100:10:0.6) as an orange-
red solid (77 mg, 77 %). 1H NMR (CD3CN) d 2.56 (s,
6H, –CH3), 7.29 (d, 2H, J = 5.2 Hz, Ha5 ), 7.40–7.45 (m,
8H, Hb5, Hb5 , Hb5, Hb5 ), 7.59 (d, 2H, J = 6.0 Hz,
Ha6 ), 7.63 (dd, 2H, J = 8.4 Hz, J = 8.4 Hz, H3, H7), 7.74
(d, 8H, J = 5.6 Hz, Hb6, Hb6 , Hb6, Hb6 ), 7.79 (d, 2H,
J = 5.2 Hz, H4, H8), 7.86 (d, 2H, J = 4.8 Hz, Ha5), 7.97
Bis-2,20-bipyridyl
ruthenium
dichloride
(55 mg,
0.11 mmol) and 3a (25 mg, 0.05 mmol) were refluxed in
the solution of EtOH and H2O (20 mL, 1:1) under argon
for 10 h. The color of the solution turned red. The solvent
was removed by rotary evaporation and the residue was
purified by column chromatography packed with silica
gel, with acetonitrile–water–saturated KNO3(100:10:1) as
eluent. The solvent was removed by rotary evaporation
and the residue was re-dissolved in a minimum volume
(5 mL) of acetonitrile, and the precipitation appeared by
addition of saturated NH4PF6. The precipitation was fil-
tered off and dried in vacuum to give the red solid
0
0
0
0
0
0
0
(d, 2H, J = 6.0 Hz, Ha6), 8.02–8.10 (m, 10H, Hb4, b4 ,
0
0
Hb4, Hb4 , H2, H6), 8.51 (d, 8H, J = 8.0 Hz, Hb3, Hb3 ,
0
0
Hb3, Hb3 ), 8.57 (s, 2H, Hb3 ), 8.98 (s, 2H, Ha3), 9.35 (s,
2H, N–H).13C NMR (CD3CN) d 20.51, 122.18, 122.48,
124.57, 125.18, 125.86, 126.30, 127.90, 129.05, 130.13,
133.26, 138.15, 142.63, 151.01, 151.11, 151.82, 152.01,
156.21, 157.03, 157.26, 158.38, 163.69, TOF MS ES+ Calc.
1378.2954, M4+/4 (m/z) 344.5722; Measured. 1378.2888.
1
(71 mg, 75%). H NMR (CD3CN) d 2.56 (s, 6H, –CH3),
7.28 (d, 2H, J = 5.2 Hz, Ha5), 7.38–7.42 (m, 8H, Hb5,
0
0
Hb5 , Hb5, Hb5 ), 7.56 (d, 2H, J = 6.0 Hz, Ha6), 7.70–
0
0
7.74 (m, 8H, Hb6, Hb6 , Hb6, Hb6 ), 7.78 (dd, 2H,
0
J = 7.2 Hz, J = 1.6 Hz, Ha5 ), 7.82 (s, 4H, H2, H6, H3,
0
H5), 7.91 (d, 2H, J = 6.0 Hz, Ha6 ), 8.06 (ddd, 8H,
0
J = 8.0 Hz, J = 8.0 Hz, J = 1.2 Hz, Hb4, Hb4 , Hb4,
Acknowledgements
0
0
0
Hb4 ), 8.50 (d, 8H, J = 8.0 Hz, Hb3, Hb3 , Hb3, Hb3 ),
0
8.56 (s, 2H, Ha3), 8.92 (s, 2H, Ha3 ), 9.34 (s, 2H, N–H);
We are grateful to the Chinese National Natural Science
Foundation (Grand Nos. 20471013 and 20128005), the Sci-
entific Research Foundation for the Returned Overseas
Chinese Scholars (State Education Ministry) and the
13C NMR (CD3CN) d 20.51, 121.45, 121.96, 124.54,
125.06, 125.80, 127.86, 129.01, 135.12, 138.13, 143.01,
150.99, 151.79, 151.99, 152.66, 156.20, 156.80, 157.02,

M. Li et al. / Journal of Organometallic Chemistry 691 (2006) 4189–4195
4195
(b) C. Desruisseaux, D. Long, G. Drouin, G.W. Slater, Macromol-
ecules 34 (2001) 44;
(c) M.M. Richter, J.D. Debad, D.R. Striplin, G.A. Crosby, A.J.
Bard, Anal. Chem. 68 (1996) 4370;
(d) H.D. Abruna, J. Electroanal. Chem. 175 (1984) 321;
(e) B. Fleet, G.F. Kirkbright, C.J. Pickford, Talanta 15 (1968) 566;
(f) E.S. Handy, A.J. Pal, M.F. Rubner, J. Am. Chem. Soc. 121 (1999)
3525.
Swedish Energy Agency and the Swedish Research Council
for financial support of this work.
References
[1] (a) M.M. Richter, Chem. Rev. 104 (2004) 3003;
(b) L.R. Faulkner, A.J. BardElectroanalytical Chemistry, vol. 10,
Marcel Dekker, New York, 1977, p. 1;
[11] M. Staffilani, E. Ho¨ss, U. Giesen, E. Schneider, F. Hartl, H-P. Josel,
L. De Cola, Inorg. Chem. 42 (2003) 7789.
[12] (a) T. Ye, D.-B. Anne, D. Marie, L. Jennifer, T.C. Gorjanc, C. Py,
M.S. Wong, Synth. Met. 111–112 (2000) 417;
(c) L.R. Faulkner, A.J. Bard, Electrogenerated chemiluminescence,
in: Electrochemical Methods, John Wiley & Sons, New York, 1980, p.
621;
(d) R.Y. Lai, E.F. Fabrizio, L. Lu, S.A. Jenekhe, A.J. Bard, J. Am.
Chem. Soc. 123 (2001) 9112;
(e) I. Prieto, J. Teetsov, M.A. Fox, D.A. Vanden Bout, A.J. Bard, J.
Phys. Chem. A 105 (2001) 520;
(b) J.P. Yang, P.L. Heremans, R. Hoefnagels, W. Tachelet, P. Dieltiens,
F. Blockhuys, H.J. Geise, G. Borghs, Synth. Met. 108 (2000) 95.
[13] (a) Y. Liu, A. De Nicola, O. Reiff, R. Ziessel, K.S. Schanze, J. Phys.
Chem. A 107 (2003) 3476;
(f) M. Oyama, S. Okazaki, Anal. Chem. 70 (1998) 5079;
(g) A. Kapturkiewicz, J. Electroanal. Chem. 290 (1990) 35.
[2] J.D. Debad, J.C. Morris, P. Magnus, A.J. Bard, J. Org. Chem. 62
(1997) 530.
(b) A. Harriman, A. Khatyr, R. Ziessel, A.C. Benniston, Angew.
Chem., Int. Ed. 39 (2000) 4287;
(c) A. Barbieri, B. Ventura, F. Barigelletti, A. De Nicola, M.
Quesada, R. Ziessel, Inorg. Chem. 43 (2004) 7359.
[14] S. Welter, K. Brunner, J.W. Hofstraat, L. De Cola, Nature 421
(2003) 54.
[3] S.K. Lee, Y. Zu, A. Herrmann, Y. Geerts, K. Mullen, A.J. Bard, J.
¨
Am. Chem. Soc. 121 (1999) 3513.
[4] J.D. Debad, J.C. Morris, V. Lynch, P. Magnus, A.J. Bard, J. Am.
Chem. Soc. 118 (1996) 2374.
[5] (a) A.J. Bard, C.P. Keszthelyi, H. Tachikawa, N.E. Tokel, Chemi-
lumin. Biolumin. Pap. Int. Conf. (1973) 193;
[15] (a) K. Sonogashira, in: E-i. Negishi (Ed.), Handbook of Organopal-
ladium Chemistry for Organic Synthesis, Wiley-Interscience, New
York, 2002, p. 493;
(b) E-i. Negishi, L. Anastasia, Chem. Rev. 103 (2003) 1979;
(c) R.R. Tykwinski, Angew. Chem., Int. Ed. 42 (2003) 1566;
(d) I.P. Beletskaya, A.V. Cheprakov, Chem. Rev. 100 (2000) 3009;
(e) B.M. Bhanage, M. Arai, Catal. Rev. Sci. 43 (2001) 315;
(f) A. de Meijere, F.E. Meyer, Angew Chem., Int. Ed. 33 (1994) 2379.
[16] (a) H.F. Brito, D.L. Malta, M.C.F.C. Felinto, E.E.S. Teotonio,
J.F.S. Menezes, C.F.B. Silva, C.S. Tomiyama, C.A.A. Carvalho, J.
Alloy. Compd. 344 (2002) 293;
(b) A. Kapturkiewicz, Adv. Electrochem. Sci. Eng. 5 (1997) 1;
(c) A.J. Bard, R.L. Faulkner, Electrochemical Methods, Fundamen-
tals and Applications, John Wiley & Sons, New York, 1980;
(d) K.A. Fa¨hnrich, M. Pravda, G.G. Guilbault, Talanta 54 (2001) 531;
(e) F.G. Gao, A.J. Bard, Chem. Mater. 14 (2002) 3465;
(f) M. Buda, G. Kalyuzhny, A.J. Bard, J. Am. Chem. Soc. 124 (2002)
6090;
(g) P. McCord, A.J. Bard, J. Electroanal. Chem. 318 (1991) 91.
[6] N.E. Tokel, A.J. Bard, J. Am. Chem. Soc. 94 (1972) 2862.
[7] (a) W.-Y. Lee, Mikrochim. Acta 127 (1997) 19;
(b) A.W. Knight, Trends Anal. Chem. 18 (1999) 47;
(c) G.F. Blackburn, H.P. Shah, J.H. Kenten, J. Leland, R.A. Kamin,
J. Link, J. Peterman, M.J. Powell, A. Shah, D.B. Talley, S.K. Tyagi,
E. Wilkins, T.-G. Wu, R.J. Massey, Clin. Chem. 37 (1991) 1534.
[8] A.W. Knight, G.M. Greenway, Analyst 119 (1994) 879.
[9] (a) H. Manakata, JP86-259286, 861, 1986, p. 117;
(b) W.H. Gastrock, P.J. Wepplo, USP 4,683,324, 1987;
(c) H. Kojima, Y. Takagi, H. Teramoto, Electrochim. Acta 33 (1988)
1789;
(b) Y.H. Tak, Repub. Korean Kongkae. Taeho. Kongbo KR 46
(2000) 139;
(c) F.L. Bai, J.L. Yang, Z.T. Wang, P.M. Zhang, Z.T. Huang, Chin.
Sci. Bull. 39 (1994) 921;
(d) N. Kuramoto, K. Natsukawa, Y. Sakurai, Sangyo Gijutsu Sogo
Kenkyusho Hokoku, Gijutsu Shiryo 5 (1996) 89.
[17] B.M. Bishop, D.G. McCafferty, B.W. Erickson, Tetrahedron 27
(2000) 4629.
[18] K. Araki, M. Fuse, N. Kishii, S. Shiraishi, T. Kodama, Y. Uchida,
Bull. Chem. Soc. Jpn. 63 (1990) 1299.
[19] X.E. Liu, J.H. Liu, K. Jin, X.C. Yang, O.J. Peng, L.C. Sun,
Tetrohedron 61 (2005) 5655.
(d) D. Laser, A.J. Bard, J. Electrochem. Soc. 122 (1975) 632.
[10] (a) M.M. Richter, A.J. Bard, W. Kim, R.H. Schmehl, Anal. Chem.
70 (1998) 310;
[20] G.F. Strouse, J.R. Schoonover, R. Duesing, S. Boyde, W.E. Jones
Jr., T.J. Meyer, Inorg. Chem. 34 (1995) 473.
[21] B.P. Sullivan, D.J. Salmon, T.J. Meyer, Inorg. Chem. 17 (1978) 3334.