Synthesis of polypyridyl ruthenium complexes with 2-(1-aryl)-1H-imidazo[4,5-f]-1,10-phenanthroline ligand and its application for luminescent oxygen sensing

Article abstract of DOI:10.1007/s11458-010-0103-y

Polypyridyl ruthenium (Ru) complexes 1-3 were prepared. Their photophysical properties were investigated by UV-Vis absorption and luminescence emission spectra. The luminescent lifetimes of these Ruthenium complex were prolonged by more than 5 folds (τ = 2. 50 μs for complex 3) when compared with the parent Ru complex 1 (τ = 0. 45 μs). We propose that the extended luminescent lifetime of complex 3 is due to the equilibrium between ³MLCT state and the pyrene localized ³π-π* triplet state (³IL). The luminescent O₂-sensing property of the complexes in solution and the IMPEK-C polymer film were studied, and the O₂ sensing was quantified with the two-site model. The oxygen-sensing property of the Ru complexes can be improved by 104-fold with extension of the luminescent lifetimes. For example, the quenching constant K_SV was improved from 0. 0023 Torr^-1 of 1 to 0. 2393 Torr^-1 for 3. Our results demonstrated a versatile approach for the preparation of Ru (II) polypyridine complexes with extended luminescent lifetimes as functional materials, for example, for luminescent oxygen-sensing applications.

Full text of DOI:10.1007/s11458-010-0103-y

Front. Chem. China 2010, 5(2): 193–199
DOI 10.1007/s11458-010-0103-y
RESEARCH ARTICLE
1 Introduction
Oxygen sensors are in great interest due to their potential
applications in oceanography, biology, environmental, che-
mical and life science [1–5]. Luminescence-based optical
oxygen sensors have been developed due to their advantages
over conventional amperometric electrodes in that they
respond faster, do not consume oxygen, and are easy to
maintain [1,2]. Among the dyes for luminescent O2 sensing,
ruthenium (II) complexes are particularly interesting because
they are triplet emitters with high photochemical stability,
larger Stokes shift, and long luminescent lifetime due to the
metal-to-ligand charge transfer triplet excited state (3MLCT)
[6–9].
Synthesis of polypyridyl
ruthenium complexes with
2-(1-aryl)-1H-imidazo[4,5-f]-
1,10-phenanthroline ligand
and its application for
luminescent oxygen sensing
Shaomin JI1, Wanhua WU1, Wenting WU1,
Huimin GUO2, Qi YANG1, Quan WANG1,
Xin ZHANG1, Yubo WU1
Recently, it has been found that the luminescence lifetime
of the Ru (II) complexes can be tuned by ligand modification
[10–13]. Usually, the mechanism is supposed to be either
establishment of an equilibrium of triplet-triplet states or
switching the emissive state from 3MLCT state to intraligand
triplet state (3IL state) [10,11]. Herein, we prepared Ru
polypyridine complexes 2 and 3 with 2-(1-aryl)-1H-imidazo
[4,5-f]-1,10-phenanthroline (where aryl = phenyl and pyrenyl)
as the ligand. We studied the photophysics of these complexes
by steady-state absorption and emission spectra. The
luminescent lifetimes (tphos) of complexes 2 and 3 were
determined as 1.13 and 2.50 ms, respectively. They are
extended when compared with the model complex 1 (tphos
= 0.45 ms). The O2-sensing properties of these complexes
were thoroughly studied in solution and IMPEK-C polymer
films. The O2 sensitivity can be improved by up to 104-fold
with tuning the luminescent lifetime of the complexes. For
example, the quenching constant KSV was improved from
0.0023 Torr–1 of complex 1 to 0.2393 Torr–1 for complex 3.
and Jianzhang ZHAO (✉)1
Polypyridyl ruthenium (Ru) complexes 1–3 were
prepared. Their photophysical properties were investi-
gated by UV-Vis absorption and luminescence emission
spectra. The luminescent lifetimes of these Ruthenium
complex were prolonged by more than 5 folds (t =
2.50 ms for complex 3) when compared with the parent
Ru complex 1 (t = 0.45 ms). We propose that the
extended luminescent lifetime of complex 3 is due to the
equilibrium between 3MLCT state and the pyrene
3
localized π-π* triplet state (3IL). The luminescent O2-
sensing property of the complexes in solution and the
IMPEK-C polymer film were studied, and the O2
sensing was quantified with the two-site model. The
oxygen-sensing property of the Ru complexes can be
improved by 104-fold with extension of the luminescent
lifetimes. For example, the quenching constant KSV was
improved from 0.0023 Torr–1 of 1 to 0.2393 Torr–1 for 3.
Our results demonstrated a versatile approach for the
preparation of Ru (II) polypyridine complexes with
extended luminescent lifetimes as functional materials,
for example, for luminescent oxygen-sensing applica-
tions.
app
The KSV value of complex 3 is even higher than PtOEP
under similar conditions (0.15 Torr–1) [14]. The sensitivity of
our complex 3/IMPES-C sensing film is much higher than that
of a reported Pt-porphyrin complex in different polymer films
[15,16].
2 Experimental
Keywords phosphorescence, ruthenium, oxygen sensor,
2.1 General methods
quenching, intraligand triplet state
NMR spectra were taken on a 400-MHz Varian Unity Inova
spectrophotometer. Mass spectra were recorded on Q-TOF
Micro MS spectrometer. UV-Vis spectra were taken on
HP8453 UV-visible spectrophotometer. Phosphorescence
spectra were recorded on a JASCO FP-6500 and Sanco 970
CRT spectrofluorometer. Phosphorescence quantum yields
were measured with Ru(bpy)2(Phen) as the standard (F =
Received December 26, 2009; accepted January 25, 2010
1. State Key Laboratory of Fine Chemicals, School of Chemical
Engineering, P.O. Box 40, 158 Zhongshan Road, Dalian University of
Technology, Dalian 116012, China
2. Department of Chemistry, School of Chemical Engineering, Dalian
University of Technology, 158 Zhongshan Road, Dalian 116012, China
E-mail: zhaojzh@dlut.edu.cn
© Higher Education Press and Springer-Verlag Berlin Heidelberg 2010

194
Shaomin JI, Wanhua WU, Wenting WU, Huimin GUO, Qi YANG et al.
6.0% in CH3CN). Luminescence lifetimes were measured on 2.3 Synthesis of luminescence Ru complexes
a Horiba Jobin Yvon Fluoro Max-4 (TCSPC) instrument. Gel
Synthesis of the Ru complexes 2 and 3 is outlined in
Scheme 1.
permeation chromatography (GPC) analysis of IMPEK-C was
conducted with a PL-GPC220 system at room temperature
using polystyrene as the standard and tetrahydrofuran (THF)
as the eluent.
2-(1-Pyrenyl)-1H-imidazo[4,5-f]-1,10-phenanthroline
(3-c) A solution of 1,10-phenanthroline-5,6-dione (95 mg,
0.46 mmol), pyrene-1-carbaldehyde (110 mg, 0.46 mmol) and
ammonium acetate (710 mg, 13 mmol) in glacial acetic acid
was refluxed for 6 h. The reacting solution was cooled to room
temperature and generated a yellow precipitate, which was
collected, washed with water, and dried. The crude product
was then subjected to column chromatography (silica gel;
eluted with dichloromethane/methanol = 30:1, v/v). Com-
pound 3-c was obtained as yellow solid. The yield of 3-c is
95.0 mg (49.3%). ESI-MS [(M + H)+] calc, m/z = 421.14;
found m/z = 421.29.
2.2 Preparation of O2 sensing film
Typical film preparation procedures are as follows. 5.0 mg of
IMPEK-C polymer [14,17] was dissolved in 0.25 mL chloro-
form, then 0.1 mL of complex Ru(II) solution in acetonitrile
(1.0´10–3 mol$dm–3) was added into the solution. After
thoroughly mixed, ca. 0.2 mL of the solution was coated
on a silica glass disk (diameter: 1.6 cm). The solvent was
evaporated at r.t., and a transparent film was obtained. The
thickness of the film of complex 3 was estimated as 13 μm by
the weight of the film (3.0 mg) and the density of the polymer
(1.14 g$cm–3). The thickness of the film of complex 2 was
estimated as 18 μm with the same method.
2-(1-Phenyl)-1H-imidazo[4,5-f]-1,10-phenanthroline (2-
c) was synthesized using similar method to that of 3-c. ESI-
MS [(M + H)+] calc, m/z = 297.11; found m/z = 297.02.
[(bpy)2Ru(1,10-phenanthroline)]2 +(PF6)2 (1) was
Scheme 1 The structure of complexes 1 and 2 as well as the synthesis of complex 3. a: KBr, H2SO4/HNO3, 100°C, 3 h; b: POCl3, DMF,
CHCl3, 60°C, 20 h; c: ammonium acetate, acetic acid, 60°C, 6 h; d: EtOH, r.t. 4 h, 2,2'-bipyridine, H2O, 100°C, 24 h. The molecular
structure of the IMPEK-C polymer was also shown.
Frontiers of Chemistry in China Vol. 5, No. 2, 2010

Synthesis of polypyridyl ruthenium complexes with 2-(1-aryl)-1H-imidazo[4,5-f]-1,10-phenanthroline ligand
195
synthesized as reported previously [18]. 1H NMR (400 MHz,
CDCl3) δ (ppm) = 8.87 – 8.81 (m, 6H), 8.45 – 8.44 (d, 2H, J =
3 Results and discussion
3.1 UV-Vis absorptions
4.8 Hz), 8.41 (s, 2H), 8.28 – 8.24 (t, 2H, J = 8.0 Hz),
8.19 – 8.13 (m, 4H), 7.95 – 7.89 (m, 4H), 7.66 – 7.62 (t, 2H,
J = 6.0 Hz), 7.41 – 7.37 (t, 2H, J = 6.4 Hz). ESI-HRMS [(M-
PF6)+], calcd, m/z = 739.0753; found m/z = 739.0469; [(M-
2PF6)2+/2], calcd, m/z = 297.0553; found m/z = 297.0457.
[(bpy)2Ru(2-(1-phenyl)-1H-imidazo[4,5-f]-1,10-phe-
nanthroline)]2+(PF6)2 (2) was synthesized with similar
method to that of 3. 1H NMR (400 MHz, acetone-d6) δ
(ppm) = 13.38 (s, 1H), 9.18 (d, 1H, J = 8.0 Hz), 9.07 (d, 1H, J
= 8.0 Hz), 8.86 – 8.81 (m, 4H), 8.37 – 8.12 (m, 10H), 7.96 (m,
4H), 7.65 – 7.56 (m, 5H), 7.40 (s, 2H). 13C NMR (100 MHz,
acetone-d6): δ 158.3, 158.1, 153.8, 152.8, 152.6, 151.3, 151.1,
138.9, 138.8, 131.6, 131.3, 131.2, 130.3, 130.0, 128.7, 128.5,
127.4, 127.2, 127.0, 125.3, 125.2. ESI-HRMS: [(M-2PF6)2+/2]
calcd, m/z = 355.0740; found, m/z = 355.0754.
[(bpy)2Ru(2-(1-Pyrenyl)-1H-imidazo[4,5-f]-1,10-phenan-
throline)]2+(PF6)2 (3) A solution of [RuCl2(cymene)]2 (40 mg,
0.065 mmol) and 3-c (54.0 mg, 0.13 mmol) in ethanol (5 mL)
was stirred for 4 h. The reaction was monitored by TLC. Then
10 mL water and 2,2'-bipyridine (40.0 mg, 0.26 mmol) were
added to the solution, the mixture was then refluxed for an
additional 24 h. After cooling, the reaction mixture was
concentrated under reduced pressure and treated with a
saturated aqueous solution of NH4PF6, which gave a red
precipitate. The crude product was then subjected to column
chromatography (Silica gel, eluted with acetonitrile : water :
saturated aqueous NaNO3 = 100:9:1, v/v). The eluent was
treated with a saturated aqueous solution of NH4PF6, which
yielded a red precipitate. The solid was washed with water and
dried under vacuum. Red solid was obtained in 31.0% yield.
1H NMR (400 MHz, acetone-d6) δ (ppm) = 13.63 (s, 1H), 9.56
(d, 1H, J = 9.6 Hz), 9.27 (d, 1H, J = 8.0 Hz), 9.16 (d, 1H, J =
8.0 Hz), 8.85 (m, 4H), 8.65 (d, 1H, J = 8.0 Hz), 8.46 – 8.11 (m,
15H), 7.98 (d, 4H, J = 5.2 Hz), 7.63 (d, 2H, J = 6.0 Hz), 7.40 (s,
2H). 13C NMR (100 MHz, acetone-d6): δ 158.3, 158.1, 154.4,
152.9, 151.3, 138.9, 138.8, 133.6, 132.3, 131.9, 131.7, 131.5,
130.3, 129.9, 129.8, 128.7, 128.6, 128.2, 128.1, 127.6, 127.1,
126.7, 126.2, 125.8, 125.3, 125.2, 125.1, 124.5. ESI-HRMS:
[(M-2PF6)2+/2] calcd, m/z = 417.0896; found, m/z = 417.0901.
The UV-Vis absorptions of the Ru(II) polypyridine complexes
1, 2 and 3 were studied. The curves were shown in Figure 1
and the absorption maxima were compiled in Table 1. Similar
to the parent compound [Ru(bpy)2(1,10-phenanthroline)],
three main bands were observed for the UV-Vis absorption of
complexes 2 and 3, i.e., two ligand-centered π-π* transition
bands at 225 nm for bpy ligand and at 262 nm for phen ligand.
A broad absorption band centered at 445 nm was also
observed with a higher energy shoulder at 414 nm.
The main peak and the shoulder of this absorption band are
indicative of the presence of strongly overlapped MLCT
1
states, with similar energy levels, such as dπ(Ru)®π*(bpy)
and dπ(Ru)®π*(Phen) [13,19,20]. Ru(II) complexes 2 and
3 show absorption at 285 nm, which is due to the 1H-
imidazo[4,5-f]-1,10-phenanthroline ligand with extended π-
conjugation framework. For complex 3, new absorption bands
appeared at 370 nm, which is due to the absorption of pyrene
[21]. We propose that the pyrene unit and 1H-imidazo[4,5-f]-
Figure 1 UV-Vis absorption spectra of Ru(II) polypyridine
complexes 1, 2, and 3. Measurements were carried out using 1.0
´10–5 mol$L–1 solution in acetonitrile at 25°C.
Table 1 Photophysics parameters of the phosphorescent polyimine ruthenium complexes 1, 2 and 3
c)
c)
ε
kr
/
knr /
IAr/I
I /I
N2 O2
a)
b)
O2
lab /nm
lem /nm
F
t/ns
–1
–1
4
–1
6 –1
（solution）
(film)
/(L$mol $cm
)
( ´10
s
)
( ´10
s )
d)
1
2
3
445
457
458
594
608
609
17900
16728
20459
0.06
0.22
0.02
450
1125
2503
13.3
19.2
2.08
18.5
1.7
e)
1.13
0.48
35.9
1.8
e)
0.83
279.0
3.0
a) Result of deaerated solution, with complex 1 as the standard. b) The determination coefficients (r2) for complexes 1, 2 and 3 are 0.99, 0.99 and 0.95,
respectively. c) Radiative deactivation rate constant (kr) and non-radiative deactivation rate constant (knr). kr = Φem/τem; knr = 1/τem(1 – Φem). It is
assumed that the emitting excited state is produced by ISC with unit efficiency. d) The polymer film is IMPES-C [19]. e) The polymer film is IMPEK-C.
Frontiers of Chemistry in China Vol. 5, No. 2, 2010

196
Shaomin JI, Wanhua WU, Wenting WU, Huimin GUO, Qi YANG et al.
1,10-phenanthroline are non-coplanar, which resulted in increased up to 5.5-fold compared to complex 1 (0.45 ms). We
non-efficient p-conjugation between the imidazole and the propose that the extended luminescent lifetime of complex 3
pyrene fragments. The lmax values of the MLCT transitions of is due to the equilibrium between the 3MLCT and the pyrene
complexes 2 and 3 (457 nm and 458 nm) are red-shifted in localized 3p-p* triplet states (3IL). The long-lived 3p-p* state
relation to that of [Ru(bpy)2(1,10-phenanthroline)] (445 nm) can act as energy reservoir, funneling energy to the emissive
due to the extent of p delocalization of imidazole ligands.
3MLCT state; thus the lifetime can be extended. The radiative
and non-radiative decay rate constants (kr and knr) of all the
complexes are calculated and listed in Table 1 [22]. In general,
the lifetimes of room temperature Ru(II) 3MLCT-based
emissions show kr and knr values on the scale of 104 s–1 and
106 s–1, respectively [22]. Based on the kr values, 1 and 2 show
typical 3MLCT emission. For 3, the exceptional long lifetime
and low kr indicated that the emission is pertubed by an
3.2 Steady-state emission spectra: different emission
profiles and O2 sensitivities in solution
The steady-state emissions of complexes 1, 2 and 3 in
acetonitrile solution under argon, air and O2 atmosphere were
studied (Figure 2). All complexes show broad, structureless
3
3
emission that is characteristic MLCT emission of the Ru
excited state other than MLCT features.
polypyridine complexes. The emissions of 1, 2 and 3 were
quenched in the presence of O2 to different extents. I0/I100
value is usually used to evaluate the O2-sensing property of
phosphorescent dyes [1,14], where I0 is the emission in inert
atmosphere, and I100 is the emission intensity in neat O2. It
was found that the I0/I100 value of the model complex 1 is the
smallest one (I0/I100 = 18.5). For complexes 2 and 3, however,
this value is imcreased. For example, the I0/I100 value of
complex 3 is as high as 279.0. Similarly improved I0/I100
values (35.9) were observed for 2. Thus, it is probable that 2
and 3 show extended lifetimes compared to the reference
complex 1[1].
3.3 Oxygen-sensing performance of the Ru complexes:
effect of the lifetimes
Dyes with long luminescence lifetime are ideal for lumines-
cence oxygen sensors. The O2-sensing property of the Ru (II)
complexes in polymer film is investigated with flow-cell/
optical fiber measuring system (Figure 3 and Figure 4). For
the O2-sensing films, a modified Stern-Volmer or two-site
model (Eq. (1)) is required to study the quenching effect
because even in “homogenous” polymers, the dye molecules
still dwell in different microenvironments [2,14]. In the two-
site model, the O2-sensitive dyes are treated as two different
portions, where f1 and KSV1 are the fraction of the “first”
portion and the quenching constant, respectively. f2 and KSV2
are the fraction of the remaining portion and the quenching
Compared to the reference complex 1, the luminescent
quantum yields of 2 are increased, and the luminescent
lifetime is elongated greatly (Table 1). We propose that the
3MLCT state of complex 2 was stabilized with the extended π-
conjugation of the Phen ligand; thus the energy gap between
constant, and f1 ＋ f2 = 1; pO is the oxygen partial pressure.
2
3
3
I0
I
1
the MC and the MLCT was increased. Therefore, longer
lifetime, red-shifted emission wavelength and higher lumi-
nescent quantum yields were observed for complex 2. For
complex 3, the lifetime is extended to 2.50 ms, which is
¼
(1)
f1
f2
þ
1 þ KSV1pO
1 þ KSV2pO
2
2
Figure 2 Room-temperature emission spectra of complexes 1, 2 and 3 under Ar, air and O2 atmosphere. (a) complex 1, lex = 445 nm, (b)
complex 2, lex = 457 nm, (c) complex 3, lex = 458 nm. Measurements were taken in 1.0 ´ 10–5 mol∙L–1 complexes solution in acetonitrile
at 25°C.
Frontiers of Chemistry in China Vol. 5, No. 2, 2010

Synthesis of polypyridyl ruthenium complexes with 2-(1-aryl)-1H-imidazo[4,5-f]-1,10-phenanthroline ligand
197
Figure 3 Phosphorescent intensity response of sensing films of the complexes 2 and 3 in IMPEK-C to O2/N2 saturation cycles. (a)
complex 2, lex= 476 nm, lem= 593 nm; (b) complex 3, lex= 478 nm, lem = 593 nm. In order to compare the quenching properties of the
films, the y axel is set from 0. Measurements were taken with home-assembled optical fiber/flow cell system.
Figure 4 Phosphorescent intensity response of sensing films of the complexes in IMPEK-C to step variations of O2 concentrations. (a)
complex 2, lex= 476 nm, lem= 593 nm; (b) complex 3, lex= 478 nm, lem = 593 nm. In order to compare the quenching efficiencies of the
films, the y axels are set from 0 for all the figures. Measurements were taken with home-assembled optical fiber/flow cell system. The
numbers indicate the O2 concentration in mixed O2/N2 gas (v/v).
It was found that the O2 quenching effect on the found. For example, with 3.5% O2, the emission of the
luminescence of complex 2 is not significant under our complex 3 is substantially quenched (Figure 4).
experimental conditions with I0/I100 = 1.8, as shown in
The quenching effect of O2 on the emission of complex was
Figure 3. The response time (t↓95) and the recovery time quantitatively studied with the two-site quenching model
(t↑95) are 10 and 22 s, respectively [19]. A higher O2 (Eq.(1)). With fitting of the quenching data (Figure 5), the
sensitivity is observed for complex 3 with I0/I100 = 3.0. The quenching constants KSV1 and KSV2 were obtained as
response time (t↓95) and the recovery time (t↑95) are 4.5 and summarized in Table 2. Complex 3 shows an increased O2
49.9 s, respectively. The longer recovery time of complex 3 is sensitivity compared to complex 1. The apparent value is
ascribed to its high sensitivity for O2; thus, the trace of O2 KSVapp = 0.2393 Torr–1, which is 104 folds of that of complex
dissolved in the polymer will quench the emission.
1. The KSVapp value of complex 3 is even higher than PtOEP
Sensing experiments with smaller O2 partial pressure under similar conditions (0.15 Torr–1) [14]. The sensitivity of
variation were carried out as shown in Figure 4. Complex 2 our complex 3/IMPEK-C-sensing film (KSVapp= 0.2393 Torr–1)
gives reasonable response to the variation of the oxygen is much higher than that of a reported PtOEP/polystyrene O2-
app
partial pressure. For complex 3, however, high sensitivity was sensing film (KSV = 0.0185 Torr–1) [15]. The value of
Frontiers of Chemistry in China Vol. 5, No. 2, 2010

198
Shaomin JI, Wanhua WU, Wenting WU, Huimin GUO, Qi YANG et al.
by steady-state UV-Vis absorption spectra and emission
spectra. Complex 3 shows much longer luminescence lifetime
of 2.50 ms when compared to the reference complex 1 Ru
(bpy)2(Phen) (t = 0.45 ms). We propose that the extended
phosphorescent lifetime of complex 3 is due to an equilibrium
3
3
between MLCT and the pyrene localized π-π* triplet state.
The extended luminescent lifetimes were successfully
employed to improve the oxygen sensitivity of the ruthenium
complexes in luminescent oxygen sensing. The O2 sensitivity
of the complexes in solution, as well as in polymer film, was
studied. The sensitivity of the emission of the complexes was
quantified with the two-site model. The results demonstrated
that, with the introduction of the pyrenyl group to the
imidazole ligand, the O2-sensing property of the Ru
complexes was improved by 104 folds; for example,
quenching constant KSV was improved from 0.0023 Torr–1
of complex 1 to 0.2393 Torr–1 for 3. Our finding may prove
useful for future design of new Ru polypyridine complexes as
luminescent oxygen-sensing materials with high sensitivity.
Figure 5 Oxygen sensitivity of the emission of complexes 1, 2
and 3. The fittings are based on the data of Figure 4 and the two-site
model (Eq. (1)). The supporting polymer film of complex 1 is
IMPES-C, and the supporting polymer for complexes 2 and 3 are
IMPEK-C. Limited oxygen partial pressure was used for complex 3
due to the significant quenching effect.
Acknowledgements We thank the National Natural Science
Foundation of China (Grant Nos. 20642003, 40806042, 20634040,
and 20972024), the Specialized Research Fund for the Doctoral
Program of Higher Education of China (Grant No. SRFDP-
200801410004), Program for New Century Excellent Talents in
University (Grant No. NCET-08-0077), State Key Laboratory of Fine
Chemicals (KF0710 and KF0802), State Key Laboratory of Chemo/
Biosensing and Chemometrics (2008009), the Education Department
of Liaoning Province (2009T015) and Dalian University of
Technology (SFDUT07005 and 1000-893394) for support.
Table 2 Parameters of the O2-sensing film of complexes 1 with
IMPES-C as well as 2 and 3 with IMPEK-C as supporting matrix (fitting
result with the two-site model, Eq.(1))
a)
a)
b)
b)
2 c)
app d)
e)
f1
f2
KSV1
KSV2
r
KSV
p
O2
1
2
3
0.5510 0.4490 0.0002 0.0049
0.5689 0.4311 0.0004 0.0037
0.6042 0.3297 0.3958 0.0004
0.99
0.99
0.99
0.0023
0.0018
0.2393
435
556
4.2
a) The ratio of the two portions of the dyes; b) The quenching constants
of the two portions; c) The determination coefficients; d) Weighted
quenching constant, KSVapp = f1 ´KSV1 + f2 ´KSV2; e) The oxygen partial
pressure at which the initial emission intensity of the film is quenched by
Jianzhang ZHAO obtained his Ph.D.
degree at Jilin University in 2000. Then he
did research in South Korea (POSTECH),
Germany (Max-Plank Research Unit of
Protein Folding) and United Kingdom
(University of Bath). In 2005, he took a
position as a full professor at Dalian
University of Technology. His current
research interests include molecular sensors
and photophysics, such as boronic acid sensors and oxygen sensors.
More recently he focused on the study of phosphorescent metal
complexes.
50% and can be calculated as 1/ KSV
.
complex 3 is also higher than that of the O2-sensing films of
Pt-porphyrin complex in Nafion (KSVapp in the range of 0.007–
0.105 Torr–1, with t↑95 time in the range of 350–370 s)[16].
Our experimental results show that the Ru complexes can
be adopted to detect different O2 concentration ranges through
tuning their luminescence lifetime [9,23]. For example,
complex 3 with long luminescence lifetime is ideal for
detecting trace O2, while complexes 1 and 2 with shorter
lifetime have advantage in sensing O2 with a wide dynamic
concentration range.
References
1. Lakowicz, J. R., Principles of Fluorescence Spectroscopy,
2nd Ed.; Kluwer Academic/Plenum Publishers: New York,
1999
4 Conclusions
2. Wolfbeis, O., Narayanaswamy, R., Optical sensors: Industrial,
Environmental and Diagnostic Applications; Springer-Verlag:
Berlin-Heidelberg, 2004
In summary, we synthesized polypyridyl Ruthenium com-
plexes 1, 2 and 3 with 2-(1-aryl)-1H-imidazo[4,5-f]-1,10-
phenanthroline (where aryl = phenyl and pyrenyl) ligand. The
photophysical properties of the complexes were investigated
3. Goui, J. F.; Bares, F.; Birot, D.; André, J. C., Sens. Actuators B
1997, 39, 401–406
Frontiers of Chemistry in China Vol. 5, No. 2, 2010

Synthesis of polypyridyl ruthenium complexes with 2-(1-aryl)-1H-imidazo[4,5-f]-1,10-phenanthroline ligand
199
Liang, X.; et al., Analyst 2009, 134, 958–965
4. Lu, X.; Winnik, M. A., Chem. Mater. 2001, 13, 3449–3463
15. Mills, A.; Lepre, A., Anal. Chem. 1997, 69, 4653–4659
5. Koo, L. Y. E.; Cao, Y. F.; Kopelman, R.; Koo, S. M.; Brasuel,
M., Philbert, M. A., Anal. Chem. 2004, 76, 2498–2505
16. Vasil’ev, V. V.; Borisov, S. M., Sens. Actuators B 2002, 82, 272–
276
6. Bacon, J. R.; Demas, J. N., Anal. Chem. 1987, 59, 2780–2785
17. Wang, Z.; Chen, T.; Xu, J., Macromolecules 2000, 33, 5672–
5679
7. Amao, Y.; Okura, I., Sens. Actuators B 2003, 88, 162–167
8. Wu, X.; Cong, Y.; Liu, Y.; Ying, L. B., J. Sol. Gel. Sci. Technol.
2009, 49, 355–363
18. Chuai, Y.; Lee, D.; Zhen, C.; Min, J.; Kim, B.; Zou, D., Syn.
Metals 2004, 145, 259–264
9. Zhong, W.; Urayama, P.; Mycek, M. A., J. Phys. D: Appl. Phys.
2003, 36, 1689–1695
19. Ji, S.; Wu, W.; Wu, W.; Song, P.; Han, K.; Wang, Z.; Liu, S.;
Guo, H.; et al., J. Mater. Chem. 2010, 20, 1953–1963
20. Glazer, E. C.; Magde, D.; Tor, Y., J. Am. Chem. Soc. 2005, 127,
4190–4192
10. Wang, X.; Guerzo, A. D.; Schmehl, R. H., J. Photochem.
Photobiol. C 2004, 5, 55–77
11. McClenaghan, N. D.; Leydet, Y.; Maubert, B.; Indelli, M. T.;
Campagna, S., Coord. Chem. Rev. 2005, 249, 1336–1350
12. Baba, A. I.; Shaw, J. R.; Simon, J. A.; Thummel, R. P.; Schmehl,
R. H., Coord. Chem. Rev. 1998, 171, 43–49
21. Mariappan, M.; Maiya, B. G., Eur. J. Inorg. Chem. 2005, 11,
2164–2173
22. Kozlov, D. V.; Tyson, D. S.; Goze, C.; Ziessel, R.; Castellano, F.
N., Inorg. Chem. 2004, 43, 6083–6092
13. Glazer, E. C.; Magde, D.; Tor, Y., J. Am. Chem. Soc. 2007, 129,
8544–8551
23. Oter, O.; Ertekin, K.; Dayan, O.; Cetinkaya, B., J. Fluoresc.
2008, 18, 269–276
14. Ji, S.; Wu, W.; Wu, Y.; Zhao, T.; Zhou, F.; Yang, Y.; Zhang, X.;
Frontiers of Chemistry in China Vol. 5, No. 2, 2010