A comparative study of the optical and electroluminescent properties of EuIII complexes with TTA and 2-(2′-pyridyl)azoles: The crystal structure of [Eu(TTA)3(PBO)]

Article abstract of DOI:10.1002/ejic.200600420

Two Eu^III mixed-ligand complexes, namely [Eu(TTA) ₃(PBO)] and [Eu(TTA)₃(PBT)] [TTA = 1,1,1-trifluoro-3-(2- thenoyl)acetonato, PBO = 2-(2′-pyridyl)-1,3-benzoxazole, and PBT = 2-(2′-pyridyl)-1,3-benzothiazole], have been synthesized. [Eu(TTA) ₃(PBO)] has been structurally characterized by single-crystal X-ray diffraction analysis. The complex crystallizes in the monoclinic space group C2/c. The lattice parameters are a = 41.346(4), b = 10.0538(8), c = 20.3793(16) A, β = 110.922(2)°, Z = 8. The Eu^III ion is eight-coordinate, with three bidentate TTA^- anions and one bidentate N,O-chelated PBO molecule. A comparative study by UV and emission spectroscopy was carried out and electroluminescent properties of the related complexes [Eu(TTA)₃(PBO)] and [Eu-(TTA)₃(PBT)] are reported as well. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.

Full text of DOI:10.1002/ejic.200600420

FULL PAPER
DOI: 10.1002/ejic.200600420
A Comparative Study of the Optical and Electroluminescent Properties of EuIII
Complexes with TTA and 2-(2Ј-Pyridyl)azoles: The Crystal Structure of
[
Eu(TTA) (PBO)]
3
Li-Hua Gao,[a,b] Min Guan, Ke-Zhi Wang,* Lin-Pei Jin, and Chun-Hui Huang
[c]
[a]
[a]
[c]
Keywords: X-ray diffraction / Luminescence / Chelates / N,O ligands / Lanthanides
Two EuIII mixed-ligand complexes, namely [Eu(TTA)
and [Eu(TTA) (PBT)] [TTA = 1,1,1-trifluoro-3-(2-thenoyl)acet-
onato, PBO = 2-(2Ј-pyridyl)-1,3-benzoxazole, and PBT = 2-
(PBO)]
β = 110.922(2)°, Z = 8. The Eu ion is eight-coordinate, with
III
3
–
3
three bidentate TTA anions and one bidentate N,O-chelated
PBO molecule. A comparative study by UV and emission
spectroscopy was carried out and electroluminescent proper-
ties of the related complexes [Eu(TTA)
(TTA) (PBT)] are reported as well.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2006)
(
[
2Ј-pyridyl)-1,3-benzothiazole], have been synthesized.
Eu(TTA) (PBO)] has been structurally characterized by sin-
3
3
(PBO)] and [Eu-
gle-crystal X-ray diffraction analysis. The complex crys-
tallizes in the monoclinic space group C2/c. The lattice pa-
rameters are a = 41.346(4), b = 10.0538(8), c = 20.3793(16) Å,
3
the introduction of L to replace the two coordinated water
Introduction
molecules in [Eu(β-diketonate) (H O) ] is imperative to ob-
3
2
2
EuIII complexes have attracted tremendous interest due tain vapor volatility for vacuum deposition film-based elec-
[
15]
to their highly monochromic red emission with large Stokes troluminescent devices. However, as almost all of the bi-
shifts and long emission lifetimes of up to a few milli- dentate neutral heterocyclic ligands are α-diimines such as
[
1]
seconds. These materials have found widespread applica- 2,2Ј-bipyridine (bpy), 1,10-phenanthroline (phen), or their
tions in chemical and earth sciences as well as bioinorganic substitutional derivatives, in addition to 2,2Ј-bipyridine N-
[
16]
chemistry, ranging from DNA binding properties to anti- oxide and 1,10-phenanthroline N-oxide,
novel types of
We have reported a series of
class of complexes is that of lanthanide β-diketonates, [Eu(β-diketonate) (α-diimine)]-type complexes for electrolu-
body labels in immunoassays.[1–3] A particularly important complexes are limited.
[1–8]
3
[
8]
which have recently attracted attention in the development minescent devices, and introduced amphiphilic complexes
of new materials based on red, near-infrared, and white- of this kind into Langmuir–Blodgett films.
light photo-conversion and switching/sensing molecular de- rapid development of these research fields, it is important
[
13]
To promote
[
4]
[5]
[6]
vices, sol–gel glasses, liquid crystals, red-emitting elec- to develop novel examples of such complexes.
[
7–9]
[10]
troluminescent devices,
supramolecular assemblies,
In addition to the great interest in functional metal com-
plexes based on bpy and phen derivatives, structurally anal-
ogous 2-(2Ј-pyridyl)azoles such as 2-(2Ј-pyridyl)-1,3-benz-
oxazole (PBO), 2-(2Ј-pyridyl)-1,3-benzothiazole (PBT), and
2-(2Ј-pyridyl)benzimidazole (PBI), which are structurally
[
11]
polymers,
sembled ultrathin films.
and Langmuir–Blodgett (LB) and self-as-
[12–14]
III
As far as Eu β-diketonates developed for electrolumi-
nescent devices are concerned, [Eu(β-diketonate) L]-type
3
complexes (L = bidentate neutral heterocyclic ligand) have
played a very important role. It has been demonstrated that
similar to 2,2Ј-bipyridine or 1,10-phenanthroline N-ox-
[16]
ide,
have attracted special attention for use in electrolu-
minescent devices, as radiopharmaceuticals based on metal
I
[17]
[
a] Department of Chemistry, Beijing Normal University,
complexes of [Re (CO) (L)X] (X = halide),
when at-
3
Beijing 100875, P. R. China
V
3+
V
3+
[18]
tached to Re O and Tc O cores,
for complexation
Fax: +86-10-5880-2075
E-mail: kzwang@bnu.edu.cn
II [19]
II [20]
III
II [20b]
V [21]
II [22]
with Ru ,
Pt ,
Rh and Pd ,
Mo ,
Sn ,
b] School of Chemical and Environment Engineering, Beijing and Co , Zn and CuII etc.,[23] and because of their struc-
II
II
[
[
Technology and Business University,
Beijing 100037, China
tural and physicochemical properties. We have reported the
c] State Key Laboratory of Rare Earth Materials Chemistry and electroluminescence properties of Eu
III
complexes with
Applications and the University of Hong Kong Joint Labora-
tory on Rare Earth Materials and Bioinorganic Chemistry, Pe-
king University,
[8c,8i]
PBI,
but so far little attention has been paid to lantha-
nide complexes with 2-(2Ј-pyridyl)azoles.
ent a comparative study of the optical and electrolumines-
[
24]
Here, we pres-
Beijing 100871, P. R. China
Eur. J. Inorg. Chem. 2006, 3731–3737
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3731

L.-H. Gao, M. Guan, K.-Z. Wang, L.-P. Jin, C.-H. Huang
FULL PAPER
cence properties of EuIII complexes of [Eu(TTA) (L)] [TTA Crystal Structure
3
=
1,1,1-trifluoro-3-(2-thenoyl)acetonato; L = PBO, PBT,
A molecular view and the crystal packing of [Eu(TTA)3-
PBO)] are shown in Figures 2 and 3, respectively; selected
and PBI], and a single-crystal X-ray structural characteriza-
tion of [Eu(TTA) (PBO)].
(
3
bond parameters are listed in Table 1. As expected, the PBO
III
ligand coordinates to the Eu ion in an unusual N,O-chela-
tion mode. The complex crystallizes in the monoclinic space
group C2/c with lattice parameters a = 41.346(4), b =
Results and Discussion
1
8
0.0538(8), c = 20.3793(16) Å, β = 110.922(2)°, and Z =
Synthesis
III
. The complex is mononuclear and the Eu ion is eight-
–
coordinate, with six oxygen atoms of three bidentate TTA
2
-(2Ј-Pyridyl)-1,3-benzoxazole (PBO), 2-(2Ј-pyridyl)-1,3-
benzothiazole (PBT), and 2-(2Ј-pyridyl)benzimidazole
PBI), and their EuIII complexes [Eu(TTA) (PBO)],
(
3
[
Eu(TTA) (PBT)], and [Eu(TTA) (PBI)] were prepared ac-
3 3
cording to the reactions shown in Figure 1. The three 2-
2Ј-pyridyl)azoles were obtained by direct condensation of
picolinic acid with 2-aminophenol, 2-aminothiophenol, and
,2-phenylenediamine, respectively, in a 1:1 molar ratio in
(
1
[
25]
the presence of polyphosphoric acid, although there have
been reports of the synthesis of PBO based on the oxidation
of the appropriate Schiff bases by Ag O
[26a]
and by the pal-
2
ladium-catalyzed carbonylation and condensation of aro-
matic halides and o-aminophenols.[
27]
Single crystals of
PBT suitable for X-ray diffraction analysis were obtained
by recrystallization from CH Cl /hexane; its structure and
2
2
lattice parameters are consistent with those reported pre-
[
26b]
viously.
The reaction of [Eu(TTA) (H O) ] with L (L =
3 2 2
PBO, PBT and PBI) in a 1:1 molar ratio in refluxing etha-
nol for 1 h, and then washing of the filtered product with
hot ethanol, yielded satisfactorily pure [Eu(TTA) (L)].
3
[
Eu(TTA) (PBO)] was also structurally characterized by
3
Figure 2. Asymmetric unit of [Eu(TTA) (PBO)] with atom number-
3
single-crystal X-ray diffraction.
ing scheme and thermal ellipsoids (30%).
Figure 1. The synthetic routes to the EuIII complexes.
3732
www.eurjic.org
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2006, 3731–3737

EuIII Complexes with TTA and 2-(2Ј-Pyridyl)azoles
FULL PAPER
anions and one oxygen atom and one nitrogen atom of a phenanthroline),[8h] and [Eu(DBM) (edapip)] {edapip =
3
bidentate PBO ligand. These atoms lie at the apices of a 3-ethyl-2-[4Ј-(dimethylamino)phenyl]imidazo[4,5-f]1,10-
[
8d]
slightly distorted square antiprism. One of the two planes phenanthroline}.
Interestingly, as shown in Figure 3,
of the square antiprism is formed exclusively by oxygen there is a π···π stacking interaction between two PBO mo-
atoms [O(1)–O(4)] and the other one by one nitrogen atom lecular planes in two adjacent [Eu(TTA) (PBO)] molecules,
3
and three oxygen atoms [N(1) and O(5)–O(7)]. The two with an interplanar distance of 3.354(1) Å and a dihedral
square planes are almost parallel to each other, as shown angle of 0° between them.
by the dihedral angle of 1.3°. The average bond lengths and
–
angles of the TTA ligands are similar to those reported for
other TTA complexes.[ The Eu–O bond lengths range
28]
UV Spectra
from 2.33(2) to 2.58(2) Å, and the mean Eu–O(TTA) bond
The UV absorption spectrum of [Eu(TTA) (PBO)] is
3
[
2.36(2) Å] is 0.22 Å shorter than the average Eu–O(PBO)
compared with those of [Eu(TTA) (H O) ] and PBO in Fig-
3
2
2
bond [2.58(2) Å], thus indicating that TTA has a stronger
coordinating ability than PBO. The EuϪO bond in PBO of
ure 4. There is one principle π–π* absorption peak at
3
3
00 nm in the spectrum of PBO and two peaks at 266 and
38 nm in that of [Eu(TTA) (H O) ], while a new shoulder
[
Eu(TTA) (PBO)], however, is stronger than the EuϪN
3
3
2
2
bonds found in [Eu(TTA) (PBO)], [Eu(DBM) (pip)] (DBM
3
3
centered at 318 nm appears in the spectrum of [Eu(TTA)3-
PBO)] in addition to one peak at 302 nm due to PBO and
two peaks at 266 and 336 nm to [Eu(TTA) (H O) ], thus
=
dibenzoylmethanato; pip = 2-phenylimidazo[4,5-f]1,10-
(
3
2
2
indicating the complexation of PBO to the Eu(TTA) moi-
3
ety.
Figure 4. UV absorption spectra of PBO (dashed line), [Eu-
3 2 2 3
(TTA) (H O) ] (dotted line), and [Eu(TTA) (PBO)] (solid line) in
CH CN.
3
3
Figure 3. The molecular packing of [Eu(TTA) (PBO)] along the a-
axis. Hydrogen atoms have been omitted for clarity.
As shown in Figure 5, the complexation of PBT to
Eu(TTA) results in profound changes in the UV spectra:
3
Table 1. Selected bond lengths [Å] and angles [°] for [Eu(TTA)
3
-
the π–π* absorption bands at 338 and 266 nm of [Eu-
(PBO)].
(
TTA) (H O) ] are blue-shifted to 330 and 251 nm, respec-
3 2 2
Eu(1)–O(1)
Eu(1)–O(3)
Eu(1)–O(5)
Eu(1)–O(7)
2.33(2)
2.38(2)
2.36(2)
2.58(2)
Eu(1)–O(2)
Eu(1)–O(4)
Eu(1)–O(6)
Eu(1)–N(1)
2.38(2)
2.33(2)
2.38(2)
2.68(2)
O(1)–Eu(1)–O(4)
O(4)–Eu(1)–O(5)
O(4)–Eu(1)–O(6)
O(1)–Eu(1)–O(2)
O(5)–Eu(1)–O(2)
O(1)–Eu(1)–O(3)
O(5)–Eu(1)–O(3)
O(2)–Eu(1)–O(3)
O(4)–Eu(1)–O(7)
O(6)–Eu(1)–O(7)
O(3)–Eu(1)–O(7)
O(4)–Eu(1)–N(1)
O(6)–Eu(1)–N(1)
O(3)–Eu(1)–N(1)
109.6(8) O(1)–Eu(1)–O(5)
135.2(7)
147.3(8)
72.1(8)
80.0(8)
79.3(8)
71.4(7)
135.2(8)
85.9(8)
90.7(8)
78.1(8)
69.4(7)
69.3(8)
125.4(8)
63.0(8)
97.0(8)
77.6(7)
71.1(8)
O(1)–Eu(1)–O(6)
O(5)–Eu(1)–O(6)
O(4)–Eu(1)–O(2)
151.2(8) O(6)–Eu(1)–O(2)
75.2(8)
80.3(7)
O(4)–Eu(1)–O(3)
O(6)–Eu(1)–O(3)
124.4(7) O(1)–Eu(1)–O(7)
147.1(8) O(5)–Eu(1)–O(7)
74.5(8)
O(2)–Eu(1)–O(7)
141.5(8) O(1)–Eu(1)–N(1)
149.1(8) O(5)–Eu(1)–N(1)
120.8(7) O(2)–Eu(1)–N(1)
Figure 5. UV absorption spectra of PBT (dashed line), [Eu-
TTA) (H O) ] (dotted line), and [Eu(TTA) (PBT)] (solid line) in
CH CN.
(
3
2
2
3
78.8(7)
O(7)–Eu(1)–N(1)
3
Eur. J. Inorg. Chem. 2006, 3731–3737
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3733

L.-H. Gao, M. Guan, K.-Z. Wang, L.-P. Jin, C.-H. Huang
FULL PAPER
tively, for [Eu(TTA) (PBT)] and the molar extinction coeffi- Figure 7 shows the chemical structures of the materials and
3
cient for the former is decreased as the coordination reac- the configuration of the EL devices. As exemplified in Fig-
tion takes place. Furthermore, the broad band at 305 nm ure 8 for the electroluminescence spectrum of [Eu(TTA) -
3
III
for PBT disappears in the spectrum of [Eu(TTA) (PBT)].
(PBO)], the two devices give similar features of an Eu
3
In the spectrum of [Eu(TTA) (PBI)] (Figure 6), the characteristic emission with good red-emitting purity cen-
3
5
7
dominant absorption feature for Eu(TTA) is also blue- tered at 613 nm, which corresponds to the D Ǟ F tran-
3
0
2
shifted to 323 nm relative to [Eu(TTA) (H O) ]; no absorp- sition. Figures 9 and 10 show current density/luminance/
3
2
2
tion feature for PBI is observed (308 nm).
voltage curves for the devices ITO/TPD (20 nm)/[Eu(TTA)3-
(
(
(
(
PBO)] (40 nm)/BCP (10 nm)/Alq (40 nm)/Mg0.9:Ag0.1
200 nm)/Ag (80 nm) and ITO/TPD (20 nm)/[Eu(TTA)3-
3
PBT)] (40 nm)/BCP (10 nm)/Alq (40 nm)/Mg0.9:Ag0.1
3
200 nm)/Ag (80 nm), respectively. The [Eu(TTA) (PBO)]-
3
based device has a turn-on voltage (the voltage at which the
–2
device gives a luminance of 1 cdm ) of about 10 V, which
is comparable to the voltage of about 10.5 V for an [Eu-
(
TTA) (PBT)]-based device. However, the maximum red-
3
–
2
emitting brightness of 18 cd m achieved at 15 V and
4
lower than the value of 30 cd m observed at 15 V and
1
.3 mAcm–2 for the [Eu(TTA) (PBO)]-based device is much
3
–
2
65 mA cm–2 for an [Eu(TTA) (PBT)]-based device and
3
–2
much higher than the value of 0.43 cdm observed at 26 V
and 1.6 mAcm–2 for an [Eu(TTA) (PBI)]-based device; it
[8i]
3
Figure 6. UV absorption spectra of PBI (dashed line), [Eu(TTA)
3
-
–2
is half that (36 cdm ) observed for an [Eu(TTA) (HEPB)]
3
(H
2
O) ] (dotted line), and [Eu(TTA) (PBI)] (solid line) in CH CN.
2
3
3
Photo- and Electroluminescent Properties
The excitation spectra for PBO, PBT, and PBI in CH CN
3
show maximum excitation wavelengths at 300, 305, and
308 nm, respectively; these correspond well to their corre-
sponding maximum UV absorption peaks. However, the ex-
citation spectra for [Eu(TTA) (PBO)], [Eu(TTA) (PBT)],
3
3
and [Eu(TTA) (PBI)] in CH CN show maximum excitation
3
3
wavelengths at 341, 341, and 339 nm, respectively, which
correspond well to the maximum UV absorption peak at
–
3
38 nm for [Eu(TTA) (H O) ], thus indicating that TTA
3 2 2
rather than neutral 2-(2Ј-pyridyl)azoles (PBO, PBT and
PBI) is mainly involved in intramolecular energy transfer
–
5
III [1]
from the excited triplet of TTA * to the D state of Eu .
0
Figure 7. Chemical structures of the materials and the configura-
The emission spectra of the three complexes show a similar tion of the EL device.
III
pattern in the Eu region, with sharp characteristic emis-
5
7
sion peaks at 595, 613, 654, and 702 nm due to D Ǟ F
0
J
(
J = 1, 2, 3, and 4) transitions, respectively, with the electric
5
7
dipole transition ( D Ǟ F ) being the strongest. The emis-
0
2
sion quantum yields of [Eu(TTA) (PBO)], [Eu(TTA) -
3
3
(
PBT)], and [Eu(TTA) (PBI)] in CH CN were determined
3 3
to be 1.22-, 0.51-, and 0.54-times that of [Eu(TTA)3-
H O) ] in the same solvent, respectively.
(
2
2
By using N,NЈ-bis(3-methylphenyl)-N,NЈ-diphenyl-1,1Ј-
biphenyl-4,4Ј-diamine (TPD) as hole-transporting material,
,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) as
hole-blocking material, and tris(8-quinolinolato)aluminium
Alq ) as electron-transporting material, we fabricated four-
2
(
3
layer electroluminescence (EL) devices with the configura-
Figure 8. Electroluminescence spectrum of the [Eu(TTA)
based device ITO/TPD (20 nm)/[Eu(TTA) (PBO)] (40 nm)/BCP
(40 nm)/Mg0.9:Ag0.1 (200 nm)/Ag (80 nm).
3
(PBO)]-
III
tion ITO/TPD (20 nm)/Eu
complex (40 nm)/BCP
3
(
10 nm)/Alq (40 nm)/Mg0.9:Ag0.1 (200 nm)/Ag (80 nm). (10 nm)/Alq
3
3
3734
www.eurjic.org
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2006, 3731–3737

EuIII Complexes with TTA and 2-(2Ј-Pyridyl)azoles
FULL PAPER
[
EPBM = 1-ethyl-2-(2Ј-pyridyl)benzimidazole] based de- mal decomposition during the vacuum deposition of
[
8c]
vice.
The poor EL performance observed for the [Eu(TTA) (PBI)].
3
[
Eu(TTA) (PBI)]-based device is mainly attributed to the
3
poor vacuum volatility of [Eu(TTA) (PBI)] due to the pres-
ence of the strongly polar NH group on PBI.
3
Experimental Section
Physical Measurements: C, H, N elemental analyses were per-
formed with a Vario EL elemental analyzer. IR spectra were mea-
sured with a Nicolet Avatar 360 FT-IR spectrometer as KBr disks.
1
H NMR spectra were obtained with a Bruker DRX-500 spectrom-
eter. UV absorption spectra were determined with a GBC Cintra
1
0e UV/Vis spectrophotometer. Emission spectra were recorded
with a Shimadzu RF-5301PC spectrofluorimeter. The PL quantum
yields of CH CN solutions of the complexes were calculated using
3
Equation (1),[ where φ
known and standard [Eu(TTA)
the solution absorbance at the excitation wavelength, I
29]
and φstd are the quantum yields of un-
(H O) ], A and Astd (Ͻ 0.1) are
and Istd are
s
3
2
2
s
s
the integrated emission intensities, and n
s
and nstd are the refractive
indices of the solvents.
Figure 9. Current/voltage (I/V) and luminance/voltage (L/V) char-
/nstd)2
φ
s
= φstd(Astd/A
s
)(I
s
/Istd)(n
s
(1)
acteristics for the EL device ITO/TPD (20 nm)/[Eu(TTA)
3
(PBO)]
(
(
40 nm)/BCP (10 nm)/Alq
80 nm).
3
(40 nm)/Mg0.9:Ag0.1 (200 nm)/Ag
The EL devices were fabricated by sequentially depositing organic
layers in one run under high vacuum (Ͻ8×10 Pa) thermal evapo-
4
ration onto a pre-cleaned indium/tin oxide glass substrate with a
2
sheet resistance of 15 Ω/cm , which was kindly supplied by China
Southern Glass Holding Co., Ltd as a gift. A shadow mask with
5-mm-diameter openings was used to define the cathode of a 200-
nm thick Mg0.9:Ag0.1 alloy layer, with an 80-nm thick Ag cap. The
thickness of the deposited layer and the evaporation speed of the
individual materials were monitored in vacuo with quartz crystal
monitors. The deposition rates were maintained to be 0.1–
–
1
–1
0
.3 nms for organic materials and 1.0–1.3 nms for Mg0.9:Ag0.1
alloy. All electrical testing and optical measurements were per-
formed under ambient conditions. The EL spectra were measured
with a Spectrascan PR650 photometer. The current/voltage (I/V)
and luminance/voltage (L/V) characteristics were measured with a
computer-controlled Keithley 2400 Sourcemeter unit with a cal-
ibrated silicon diode.
Figure 10. Current/voltage (I/V) and luminance/voltage (L/V) char-
acteristics for EL device ITO/TPD (20 nm)/[Eu(TTA) (PBT)]
(40 nm)/Mg0.9:Ag0.1 (200 nm)/Ag
3
3 2 2
(H O)
][30] [TTA = 1,1,1-trifluoro-3-(2-
Materials: [Eu(TTA)
thenoyl)acetonato] was prepared by a literature method. 2-(2Ј-Pyr-
idyl)benzimidazole (PBI) and [Eu(TTA) (PBI)] were synthesized as
The other materials were commercially
available and were used without further purification.
(
(
40 nm)/BCP (10 nm)/Alq
80 nm).
3
3
described previously.[
8c,8i]
2
-(2Ј-Pyridyl)-1,3-benzoxazole (PBO): A mixture of powdered 2-
Conclusions
picolinic acid (12.3 g, 0.1 mol), 2-aminophenol (10.9 g, 0.1 mol),
We have synthesized two EuIII mixed-ligand complexes and syrupy phosphoric acid (50 mL) was stirred at 160 °C for 4 h.
with TTA and PBO or PBT. The N,O-bidentate coordina- The blue slurry was then poured into vigorously stirred cold water
III
tion to Eu by PBO in [Eu(TTA) (PBO)] has been demon- (500 mL). Aqueous ammonia was then added up to a pH of about
3
7
. The resulting pink solid product was filtered off and recrys-
strated by single-crystal X-ray diffraction. The N,N-Biden-
tate coordination to Eu by PBT and PBI in [Eu(TTA)3-
PBT)] and [Eu(TTA) (PBI)] causes more evident changes
1
III
2 2
tallized from CH Cl /hexane. Yield: 8.6 g (43.9 %). H NMR
(
500 MHz, CDCl
.90 Hz, 1 H), 7.94 (m, 1 H), 7.86 (m, 1 H), 7.71 (d, J = 4.60 Hz,
H), 7.50 (m, 1 H), 7.44 (m, 2 H) ppm. IR (KBr): ν˜ = 3058 (w),
583 (m), 1552 (m), 1454 (vs), 1437 (s), 1347 (m), 1242 (m), 1076
3
): δ = 8.86 (d, J = 4.60 Hz, 1 H), 8.40 (d, J =
(
3
7
1
1
in the UV spectra than in the N,O-bidentate coordinated
Eu(TTA) (PBO)]. However, the photoluminescence quan-
[
3
tum yield of N,O-coordinated [Eu(TTA) (PBO)] is the high-
est and follows the order: [Eu(TTA) (PBO)] Ͼ [Eu(TTA) -
–1
3
12 8 2
(s), 809 (m), 742 (vs), 704 (m) cm . C H N O (196.21): calcd. C
3
3
73.50, H 4.10, N 14.30; found C 73.70, H 4.20, N 14.10.
(
PBI)] Ϸ [Eu(TTA) (PBT)]. The maximum red-emitting EL
3
2
-(2Ј-Pyridyl)-1,3-benzothiazole (PBT): This was synthesized as de-
brightness follows the order [Eu(TTA) (PBT)] Ͼ
3
scribed above for PBO except that 2-aminothiophenol was used
instead of 2-aminophenol. Yield: 6.0 g (30.6 %). H NMR
(500 MHz, CDCl ): δ = 8.72 (d, J = 4.70 Hz, 1 H), 8.42 (d, J =
[
Eu(TTA) (PBO)] ϾϾ [Eu(TTA) (PBI)]. The low bright-
1
3
3
–
2
ness of only 0.43 cdm observed for the [Eu(TTA) (PBI)]-
3
3
based EL device is most probably due to the poor vacuum 7.91 Hz, 1 H), 8.13 (d, J = 8.13 Hz, 1 H), 8.00 (d, J = 7.94 Hz, 1
volatility of [Eu(TTA) (PBI)], since we noticed serious ther- H), 7.89 (m, 1 H), 7.54 (m, 1 H), 7.44 (m, 2 H) ppm. IR (KBr): ν˜
3
Eur. J. Inorg. Chem. 2006, 3731–3737
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3735

L.-H. Gao, M. Guan, K.-Z. Wang, L.-P. Jin, C.-H. Huang
FULL PAPER
=
3052 (w), 1583 (m), 1562 (m), 1509 (m), 1456 (s), 1432 (vs), 1316
tion and refinement are given in Table 2. CCDC-296449 contains
the supplementary crystallographic data for this paper. These data
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
(s), 1292 (m), 1265 (m), 1233 (m), 996 (m), 978 (s), 783 (s), 758 (s),
–1
8 2
739 (s), 725 (s), 618 (s) cm . C12H N S (212.21): calcd. C 67.90,
H 3.80, N 13.20; found C 68.00, H 3.85, N 13.15.
Eu(TTA) (PBO)]: PBO (0.0785 g, 0.4 mmol) and [Eu(TTA)
O) ] (0.3408 g, 0.4 mmol) were refluxed in ethanol (10 mL) for
h. The solid product formed upon cooling was filtered off,
washed with hot ethanol, and then vacuum-dried. Yield: 0.29 g
[
3
3
-
(H
2
2
Acknowledgments
1
We are grateful to the NSFC (20371008, 90401007, 20471004, and
3
(71.6%). UV (CH CN): λ (ε) = 266 (4.03), 302 (5.18), 318 (5.70),
20331010), and the Beijing Natural Science Foundation (2052008)
4
–1
–1
3
1
36 (6.80×10  cm ) nm. IR (KBr): ν˜ = 1598 (s), 1578 (m),
541 (m), 1508 (w), 1463 (w), 1413 (m), 1359 (w), 1311 (s), 1250
for their financial support of this work.
(
(
w), 1230 (w), 1189 (m), 1136 (s), 1085 (w), 1062 (w), 935 (w), 858
w), 787 (m), 748 (m), 720 (m), 681 (w), 642 (w), 581 (w), 457 (vw) [1] a) J.-C. G. Bünzli, G. R. Choppin, Lanthanide Probes in Life,
–1
cm . C36
found C 42.66, H 2.06, N 2.96.
H
20EuF
9
N
2
O
7
S
3
(1011.7): calcd. C 42.74, H 1.99, N 2.77;
Chemical and Earth Sciences, Elsevier, Amsterdam, 1989, chap-
ter 7; b) J.-C. G. Bünzli, Acc. Chem. Res. 2006, 39, 53–61; c) J.-
C. G. Bünzli, C. Piguet, Chem. Rev. 2002, 102, 1897–1928; d)
R. Pavithran, M. L. P. Reddy, S. A. Junior, R. O. Freire, G. B.
Rocha, P. P. Lima, Eur. J. Inorg. Chem. 2005, 4129–4137; e) J.-
C. G. Bünzli, C. Piguet, Chem. Soc. Rev. 2005, 34, 1048–1077;
f) C. Piguet, J.-C. G. Bünzli, Chem. Soc. Rev. 1999, 28, 347–
[
Eu(TTA) (PBT)]: This complex was synthesized as described
above for [Eu(TTA) (PBO)] except that PBT was used instead of
PBO. UV (CH CN): λ (ε) = 234 (3.73), 251 (3.77), 330
3
3
3
4
–1
–1
(
(
5.69×10  cm ) nm. IR (KBr): ν˜ = 1625 (m), 1598 (s), 1578
358.
m), 1540 (m), 1508 (w), 1464 (w), 1413 (m), 1357 (w), 1308 (s),
[
[
[
2] P. B. Glover, P. R. Ashton, L. J. Childs, A. Rodger, M. Kercher,
R. M. Williams, L. De Cola, Z. Pikramenou, J. Am. Chem.
Soc. 2003, 125, 9918–9919.
3] I. A. Hemmila, Applications of Fluorescence in Immunoassays,
J. Wiley & Sons, New York, 1991, vol. 117, Chemical Analysis
Series.
4] a) N. Shavaleev, L. P. Moorcraft, S. J. A. Pope, Z. R. Bell, S.
Faulkner, M. D. Ward, Chem. Commun. 2003, 1134–1135; b)
H. Tsukube, S. Shinoda, Chem. Rev. 2002, 102, 2389–2403; c)
P. Coppo, M. Duati, V. N. Kozhevnikov, J. W. Hofstraat, L.
De Cola, Angew. Chem. Int. Ed. 2005, 44, 1806–1810; d) J. A.
Fernandes, R. A. S. Ferreira, M. Pillinger, L. D. Carlos, I. S.
Goncalves, P. J. A. Ribeiro-Claro, Eur. J. Inorg. Chem. 2004,
3913–3919; e) T. Gunnlaugsson, J. P. Leonard, Chem. Commun.
2005, 3114–3131.
1
9
248 (w), 1231 (w), 1187 (m), 1142 (s), 1083 (w), 1065 (m), 995 (w),
35 (w), 855 (w), 788 (m), 762 (w), 718 (m), 681 (w), 644 (m), 577
–1
9 2 6 4
(m), 496 (vw), 461 (vw) cm . C36H20EuF N O S (1027.8): calcd.
C 42.07, H 1.96, N 2.73; found C 41.77, H 2.11, N 2.76.
X-ray Crystallographic Study: Yellow single crystals with approxi-
mate dimensions suitable for X-ray structural analysis were ob-
tained by recrystallization from CH
collected at 294(2) K with a CCD area detector Bruker SMART
000 X-ray diffractometer with graphite-monochromated Mo-K
radiation (λ = 0.71073 Å) in the ω-2θ scan mode (2θ range: 5.52–
2.48°). The coordinates of all non-hydrogen atoms and anisotropic
2 2 3
Cl /CH CN. The data were
2
α
5
thermal parameters were refined by full-matrix least squares. The
data were processed with a Pentium PC using the Bruker
SHELXTL software package.[16] Further details of the data collec-
[5] K. Binnemans, P. Lenaerts, K. Driesen, C. Gorller-Walrand, J.
Mater. Chem. 2004, 14, 191–195.
[
6] a) R. Van Deun, D. Moors, B. De Fre, K. Binnemans, J. Mater.
Chem. 2003, 13, 1520–1522; b) L. N. Puntus, K. J. Schenk,
J. C. G. Bünzli, Eur. J. Inorg. Chem. 2005, 4739–4744.
7] J. Kido, Y. Okamoto, Chem. Rev. 2002, 102, 2357–2368.
8] a) M. Sun, H. Xin, K. Z. Wang, Y. A. Zhang, L. P. Jin, C. H.
Huang, Chem. Commun. 2003, 702–703; b) Z. Q. Bian, D. Q.
Gao, K. Z. Wang, L. P. Jin, C. H. Huang, Thin Solid Films
Table 2. Principal crystallographic data and parameters of
3
[Eu(TTA) (PBO)].
[
[
Empirical formula
Formula mass
Temp. [K]
Wavelength [Å]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
β [°]
V [Å ]
36 9 2 7 3
C H20EuF N O S
1011.68
294(2)
0.71073
monoclinic
C/2c
41.346(4)
10.0538(8)
20.3793(16)
110.922(2)
7912.7(11)
8
1.698
1.835
3984
0.16×0.14×0.10
2.02–25.01
19608
6958
5215
2
004, 460, 237–241; c) L. Huang, K. Z. Wang, C. H. Huang,
F. Y. Li, Y. Y. Li, J. Mater. Chem. 2001, 11, 790–793; d) Z. Q.
Bian, K. Z. Wang, L. P. Jin, Polyhedron 2002, 21, 313–319; e)
H. Xin, M. Sun, K. Z. Wang, Y. A. Zhang, L. P. Jin, C. H.
Huang, Chem. Phys. Lett. 2004, 388, 55–57; f) H. Xin, F. Y. Li,
M. Guan, C. H. Huang, M. Sun, K. Z. Wang, Y. A. Zhang,
L. P. Jin, J. Appl. Phys. 2003, 94, 4729–4731; g) K. Z. Wang,
L. Huang, C. H. Huang, L. P. Jin, Solid State Commun. 2002,
3
Z
D
1
22, 233–236; h) D. Q. Gao, Z. Q. Bian, K. Z. Wang, L. P. Jin,
–
3
calcd. [gcm ]
C. H. Huang, J. Alloys Compd. 2003, 358, 188–192; i) L. Hu-
ang, K. Z. Wang, C. H. Huang, D. Q. Gao, L. P. Jin, Synth.
Met. 2002, 128, 241–245.
–
1
Absorption coefficient [mm ]
F(000)
Crystal size [mm]
[
9] a) H. Jang, C. H. Shin, B. J. Jung, D. H. Kim, H. K. Shim, Y.
Do, Eur. J. Inorg. Chem. 2006, 718–725; b) M. R. Robinson,
M. B. O’Regan, G. C. Bazan, Chem. Commun. 2000, 1645–
θ range [°]
No. of reflections collected
No. of independent reflections
No. of observed reflections [IϾ2σ(I)]
No. of refined parameters
Largest peak/hole [e·Å ]
Final Rint [IϾ2σ(I)]
1
646; c) C. J. Liang, D. Zhao, Z. R. Hong, D. X. Zhao, X. Y.
Liu, W. L. Liu, J. B. Peng, J. Q. Yu, C. S. Lee, S. T. Lee, Appl.
Phys. Lett. 2000, 76, 67–69; d) C. Adachi, M. A. Baldo, S. R.
Forrest, J. Appl. Phys. 2000, 87, 8049–8055.
652
0.765/–0.547
–
3
R
R
1
= 0.0363, wR = 0.0911
2
= 0.0570, wR = 0.1095
2
[
10] a) A. P. Bassett, S. W. Magennis, P. B. Glover, D. J. Lewis, N.
Spencer, S. Parsons, R. M. Williams, L. D. Cola, Z. Pikra-
menou, J. Am. Chem. Soc. 2004, 126, 9413–9424; b) M. H. W.
Lam, D. Y. K. Lee, S. S. M. Chiu, K. W. Man, W. T. Wong, Eur.
J. Inorg. Chem. 2000, 1483–1488.
[
a]
R
int (all data)
1
2
2
2)2]/
[
a] Structure was refined on F
o
: wR
2
= {Σ[w(F
o
– F
c
2
2
1/2
–1
2
2
Σw(F
o
) } , where w = [Σ(F
o
) + (aP) + bP] and P =
2
2
[max(F
o
c
,0) + 2F ]/3.
3736
www.eurjic.org
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2006, 3731–3737

EuIII Complexes with TTA and 2-(2Ј-Pyridyl)azoles
FULL PAPER
[
[
[
11] J. L. Bender, P. S. Corbin, C. L. Fraser, D. H. Metcalf, F. S.
[20] a) X. F. He, C. M. Vogels, A. Decken, S. A. Westcott, Polyhe-
dron 2004, 23, 155–160; b) C. K. Choudhary, R. K. Choudhary,
L. K. Mishra, J. Indian Chem. Soc. 2002, 79, 761–762.
[21] S. S. Mandal, P. C. Ghorai, S. Ray, H. K. Saha, J. Indian Chem.
Soc. 1995, 72, 807–810.
[22] S. Hu, D. Shi, T. Huang, J. Wan, Z. Huang, J. Yang, C. Xu,
Inorg. Chim. Acta 1990, 173, 1–4.
Richardson, E. L. Thomas, A. M. Urbas, J. Am. Chem. Soc.
2002, 124, 8526–8527.
12] Y. L. Zhao, D. J. Zhou, C. H. Huang, L. B. Gan, L. M. Ying,
X. S. Zhao, B. Zhang, Y. Ma, M. Xu, K. Wu, Langmuir 1998,
14, 417–422.
13] a) K. Z. Wang, L. H. Gao, C. H. Huang, J. Photochem. Pho-
tobiol. A: Chem. 2003, 156, 39–43; b) D. J. Zhou, K. Z. Wang,
C. H. Huang, G. X. Xu, L. G. Xu, T. K. Li, Solid State Com-
mun. 1995, 93, 167–169; c) K. Z. Wang, V. W. W. Yam, C. H.
Huang, Solid State Commun. 1998, 107, 249–252; d) L. H.
Gao, K. Z. Wang, L. Cai, H. X. Zhang, L. P. Jin, C. H. Huang,
H. J. Gao, J. Phys. Chem. B 2006, 110, 7402–7408.
[23] a) P. S. K. Chia, L. F. Lindoy, S. E. Livingstone, Inorg. Chim.
Acta 1968, 2, 459–462; b) L. F. Lindoy, S. E. Livingstone, Inorg.
Chim. Acta 1968, 2, 119–126.
[24] For a paper dealing with the solid lanthanide(III) thiocyanate
3 2 2
complexes [Ln(NCS) (PBO) ]·nH O, see: P. Hakur, V. Chakra-
vortty, K. C. Dash, Indian J. Chem. Sect. A 1999, 38, 1223–
1227.
[
[
[
[
14] L. Zhang, H. G. Liu, R. J. Zhang, Y. D. Mu, D. J. Qian, X. S.
Feng, Colloids Surf. A 2005, 257–58, 401–404.
[25] A. W. Addison, P. J. Burke, J. Heterocycl. Chem. 1981, 18, 803–
15] K. Z. Wang, L. J. Li, W. M. Liu, Z. Q. Xue, C. H. Huang, J. H.
Lin, Mater. Res. Bull. 1996, 31, 993–998.
16] X. H. Zhu, L. H. Wang, J. Ru, W. Huang, J. F. Fang, D. G.
Ma, J. Mater. Chem. 2004, 14, 2732–2734.
805.
[26] a) J. Chang, K. Zhaob, S. Pana, Tetrahedron Lett. 2002, 43,
951–954; b) J. Gangopadhyay, S. Sengupta, S. Bhattacharyya,
I. Chakraborty, A. Chakravorty, Inorg. Chem. 2002, 41, 2616–
2622.
17] a) K. Z. Wang, L. Huang, L. H. Gao, L. P. Jin, C. H. Huang,
Inorg. Chem. 2002, 41, 3353–3358; b) R. Czerwieniec, A. Kap-
turkiewicz, J. Lipkowski, J. Nowacki, Inorg. Chim. Acta 2005,
[27] R. J. Perry, B. D. Wilson, R. J. Miller, J. Org. Chem. 1992, 57,
2883–2887.
3
58, 2701–2710; c) X. Chen, F. J. Femia, J. B. Babich, J. Zubi-
[28] a) K. Z. Wang, C. H. Huang, R. J. Wang, G. X. Xu, Polyhedron
1995, 14, 3669–3673; b) Y. Fukuda, A. Nakao, K. Hayashi, J.
Chem. Soc., Dalton Trans. 2002, 527–533.
[29] M. J. Han, L. H. Gao, Y. Y. Lu, K. Z. Wang, J. Phys. Chem. B
2006, 110, 2364–2371.
eta, Inorg. Chim. Acta 2001, 314, 91–96.
[
[
18] S. Tzanopoulou, I. C. Pirmettis, G. Patsis, C. Raptopoulou, A.
Terzis, M. Papadopoulos, M. Pelecanou, Inorg. Chem. 2006,
45, 902–909.
19] a) N. Chanda, D. Paul, S. Kar, S. M. Mobin, A. Datta, V. G.
[30] L. R. Melby, N. J. Rose, E. Abramson, J. C. Caris, J. Am.
Chem. Soc. 1964, 86, 5117–5125.
Puranik, K. K. Rao, G. K. Lahiri, Inorg. Chem. 2005, 44,
3
499–3511; b) N. Chanda, B. Sarkar, S. Kar, J. Fiedler, W.
Received: May 8, 2006
Kaim, G. K. Lahiri, Inorg. Chem. 2004, 43, 5128–5133; c) M.
Maji, P. Sengupta, S. K. Chattopadhyay, G. Mostafa, C. H.
Schwalbe, S. Ghosh, J. Coord. Chem. 2001, 54, 13–24.
Published Online: August 7, 2006
Eur. J. Inorg. Chem. 2006, 3731–3737
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3737