Photoluminescence behavior of europium (III) complexes containing 1-(4-tert-butylphenyl)-3-(2-naphthyl)-propane-1,3-dione ligand

Article abstract of DOI:10.1016/j.saa.2013.08.023

Three novel europium complexes with 1-(4-tert-butylphenyl)-3-(2-naphthyl)- propane-1,3-dione (TNPD) and 2,2-dipyridine (Bipy) or 1,10-phenan-throline (Phen) were synthesized and confirmed by FT-IR, ¹H NMR, UV-vis absorption and elemental analys

Full text of DOI:10.1016/j.saa.2013.08.023

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 117 (2014) 245–249
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Photoluminescence behavior of europium (III) complexes containing
1-(4-tert-butylphenyl)-3-(2-naphthyl)-propane-1,3-dione ligand
⇑
Dunjia Wang , Chunyang Zheng, Ling Fan, Yanjun Hu, Jing Zheng
Hubei Key Laboratory of Pollutant Analysis and Reuse Technology, College of Chemistry and Chemical Engineering, Hubei Normal University, Huangshi 435002, PR China
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
5D0 7F2
ꢀ
Synthesis of europium (III) complexes
with b-diketone ligand and 2,2-
dipyridine or 1,10-phenanthroline.
Photoluminescence properties of
europium (III) complexes.
200
C1
C2
C3
O
Eu
O
3
(H3C)3
C
C 1
ꢀ
ꢀ
150
100
50
N
N
O
Eu
O
Analysis of the intensity parameters
C(CH3
)
3
3
C2
(
Xt), the lifetime (
s) and the
N
N
O
Eu
luminescent quantum yield (
g
).
O
C(CH3
)
3
3
C3
5D0 7F1
5D0 7F0
5D0 7F3
5D0 7F4
0
560 580 600 620 640 660 680 700 720
Wavelength / nm
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 16 May 2013
Received in revised form 28 July 2013
Accepted 2 August 2013
Available online 14 August 2013
Three novel europium complexes with 1-(4-tert-butylphenyl)-3-(2-naphthyl)-propane-1,3-dione (TNPD)
and 2,2-dipyridine (Bipy) or 1,10-phenan-throline (Phen) were synthesized and confirmed by FT-IR, 1H
NMR, UV–vis absorption and elemental analysis. Photoluminescence behavior of complexes Eu(TNPD)3,
Eu(TNPD)3ꢂBipy and Eu(TNPD)3ꢂPhen were investigated in detail. Their emission spectra exhibited the
characteristic emission bands that arise from the 5D0
?
7FJ (J = 0–4) transitions of the europium ion in
solid state. Meanwhile, the results of their lifetime decay curves indicated that only one chemical envi-
ronment existed around the europium ion. The intrinsic luminescence quantum efficiency ( ) and the
experimental intensity parameters (Xt) of europium complexes were determined according to the emis-
Keywords:
Europium (III) complex
b-Diketone
Photoluminescent property
Quantum efficiency
JuddꢁOfelt intensity parameters
g
sion spectra and luminescence decay curves in solid state. The complex Eu(TNPD)3ꢂPhen showed much
longer lifetime (s) and higher luminescence quantum efficiency (g) than complexes Eu(TNPD)3 and
Eu(TNPD)3ꢂBipy.
Ó 2013 Elsevier B.V. All rights reserved.
Introduction
ultraviolet light is firstly absorbed by b-diketone ligands, and then
the absorbed energy is transferred from the lowest triplet state
energy level of the ligand to the resonance level of europium ions
and makes them send out their characteristic light [6]. Recently,
the design, synthesis and photoluminescence properties of many
new europium complexes with b-diketone ligands have been
reported [7–9].
With the purpose of developing novel optical materials, three
new europium (III) complexes with 1-(4-tert-butyl-phenyl)-3-(2-
naphthyl)-propane-1,3-dione (TNPD) and 2,2-dipyridine (Bipy) or
1,10-phenanthroline (Phen) were synthesized. Their structures
were confirmed by elemental analysis, FT-IR, 1H NMR, UV–vis
Europium (III) complexes with b-diketone ligands have been
attracted attention in last decades due to their long fluorescence
lifetime and narrow emission bands in the visible region [1,2].
These spectroscopic properties have been utilized in material sci-
ence such as electroluminescent materials [3], sensory materials
[4], laser materials and optical fibers [5]. The b-diketone is one of
the important ‘‘antenna’’ ligands. As light conversion materials,
⇑
Corresponding author. Tel.: +86 714 6515602; fax: +86 714 6573832.
E-mail address: dunjiawang@163.com (D. Wang).
1386-1425/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.saa.2013.08.023

246
D. Wang et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 117 (2014) 245–249
absorption and ESI-MS spectroscopy. Their photoluminescence
properties have also been investigated by photoluminescent spec-
troscopy. In addition, according to their photoluminescence spec-
tra and lifetime measurement, the Judd–Ofelt intensity
parameters (Xt), radiative (Arad), nonradiative (Anrad) rates and
Eu(TNPD)3ꢂBipy (C2): same procedure as for Eu(TNPD)3 (C1),
but the reaction mixture with TNPD (0.99 g, 3 mmol), Bipy
(0.13 g, 1 mmol) and 1 mmol EuCl3. The complex C2 was obtained
as a yellow power, yield 70%. IR
m (KBr): 3056(m), 2962(s),
2867(m), 1599(s), 1548(s), 1523(s), 1498(s), 1441(s), 1421(s),
the photoluminescent quantum efficiency (
and analyzed.
g) were calculated
1391(s), 1362(s), 1344(s), 1298(s), 1269(s), 1193(s), 1122(s),
788(s), 757(s), 506(m), 473(m) cmꢁ1 1H NMR (300 MHz, CDCl3):
;
d 1.38 (s, 27H, C(CH3)3), 2.95 (s, 3H, C@CH), 6.21 (d, 6H, ArAH,
J = 7.8 Hz), 6.35 (d, 6H, ArAH, J = 7.8 Hz), 7.51–7.58 (m, 18H,
ArAH), 8.48 (s, 3H, ArAH), 8.28 (br, 2H, Bipy-H), 9.55 (br, 2H,
Bipy-H), 10.13 (d, 2H, Bipy-H, J = 7.5 Hz), 12.01 (d, 2H, Bipy-H,
J = 7.8 Hz) ppm; Anal. Calcd. for EuC79H71N2O6: C,73.19; H, 5.52;
N, 2.16; Eu, 11.72; Found C, 73.45; H, 5.46; N, 2.18; Eu, 11.85.
Eu(TNPD)3ꢂPhen (C3): same procedure as for Eu(TNPD)3 (C1),
but the reaction mixture with TNPD (0.99 g, 3 mmol), Phen
(0.18 g, 1 mmol) and 1 mmol EuCl3. The complexC3 was obtained
Experimental
Apparatus and measurements
Europium trichloride ethanol solution was obtained by dissolv-
ing Eu2O3 in concentrated hydrochloric acid. Other chemicals were
of analytical grade and used without further purification. The euro-
pium content was determined by the complexometric titration
with EDTA. Elemental analysis (C, H, N) was performed on a Per-
kin–Elmer 2400 elemental analyzer. Infrared spectra were re-
corded on a Nicolet FTIR 5700 spectrophotometer with KBr
pellets. 1H NMR spectra were measured on an Avance III™
300 MHz NB Digital NMR spectrometer in CDCl3 solution with
TMS as internal standard. Electrospray ionization mass spectra
(ESI-MS) were determined with a Finnigan LCQ Advantage Max
spectrometer. Emission spectra and fluorescence lifetimes were
measured on a Varian Cary Eclipse fluorescence spectrometer.
The UV–vis spectra were obtained with Hitachi U-3010
spectrometer.
as a yellow power, yield 75%. IR
m (KBr): 3054(m), 2962(s),
2867(m), 1599(s), 1548(s), 1521(s), 1497(s), 1442(s), 1422(s),
1396(s), 1363(s), 1345(s), 1297(s), 1269(s), 1192(s), 1120(s),
841(m), 788(s), 757(s), 730(m), 505(m), 473(m) cmꢁ1 1H NMR
;
(300 MHz, CDCl3): d 1.35 (s, 27H, C(CH3)3), 2.98 (s, 3H, C@CH),
6.02 (d, 6H, ArAH, J = 8.1 Hz), 6.16 (d, 6H, ArAH, J = 7.8 Hz), 7.39–
7.46 (m, 18H, ArAH), 8.42 (s, 3H, ArAH), 8.93 (br, 2H, Phen-H),
10.39 (br, 2H, Phen-H), 10.81 (br, 2H, Phen-H), 10.98 (br, 2H,
Phen-H) ppm; Anal. Calcd. for EuC81H71N2O6: C, 73.68; H, 5.42;
N, 2.12; Eu, 11.51; Found C, 73.51; H, 5.38; N, 2.16; Eu, 11.67.
Results and discussion
Synthesis of b-diketone ligand
Synthesis
1-(4-tert-Butylphenyl)-3-(2-naphthyl)-propane-1,3-dione
(TNPD): the mixture of 2-acetylnaphthalene (6.80 g, 0.04 mol),
ethyl 4-tert-butylbenzoate (7.68 g, 0.04 mol), NaNH2 (1.95 g,
0.05 mol) and toluene (50 ml) was heated to 80 °C under stirring
and maintained for 6 h. The reaction mixture was cooled to room
temperature and acidified with dilute hydrochloric acid, and then
extracted with toluene. The toluene layer was washed with a sat-
urated NaHCO3 solution, dried over anhydrous MgSO4 and the sol-
vent removed by evaporation. The solid residue was recrystallized
from ethanol to obtain b-diketone TNPD. Pale yellow crystals, yield
Scheme 1 presents the synthetic routes for b-diketone ligand
and europium complexes. The b-diketone TNPD was synthesized
by Claisen reaction, which is one of the most widely used methods
for the synthesis of b-diketone. Europium (III) complexes C1–C3
were prepared by reacting the b-diketone ligand with EuCl3 and
2,2-dipyridine or 1,10-phenanthroline according to the method of
Ref. [10].
IR spectra
65%, mp 122–123 °C; IR (KBr):
m 3500(w), 3082(w), 2962(s),
2860(w), 1628(s), 1598(m), 1528(s), 1499(m), 1460(m), 1365(m),
Compared to the IR spectrum of the free ligand TNPD, the IR
spectra of the complexes C1–C3 exhibit apparent changes. The
characteristic, strong bands of the ligand TNPD and europium com-
plexes are summarized in Table 1. The absorption bands in the re-
gions of 1600–1599 cmꢁ1 and 1524–1521 cmꢁ1 in complexes
which are the characteristics of b-diketonate coordinated with
europium ion. Since the C@O bonds were converted into the
vibrating structure of the C@O ? Eu bond and CAOAEu bond, their
stretching frequencies were red-shifted 4–29 cmꢁ1 with respect to
those of the free ligand [11,12]. Further information on the IR spec-
troscopy for complexes is given by the disappearance of corre-
sponding OAH vibration band which exists in the free ligand due
to the keto-enol tautomerism of the b-diketone. In addition, there
are new medium absorption peaks at about 506 cmꢁ1 and
473 cmꢁ1, which are due to the new bonds of the EuAN and EuAO
in complexes, respectively [13,14].
1297(m), 1266(m), 1192(s), 1110(s), 1013(s), 910(s), 845(s),
792(s), 756(s) cmꢁ1 1H NMR (300 MHz, CDCl3): d 1.37 (s, 9H,
;
C(CH3)3), 4.70 (s, 0.14H, keto CH2), 7.00 (s, 1H, enol CH), 7.52–
7.59 (m, 4H, ArAH), 7.95–8.00 (m, 6H, ArAH), 8.55 (s, 1H, ArAH),
17.10 (br s, 1H, enol OH) ppm; ESI-MS: m/z 331.05 [M + 1]+; Anal.
Calcd. for C23H22O2: C, 83.60; H, 6.71; Found C, 83.70; H, 6.69.
Synthesis of complexes
Eu(TNPD)3 (C1): to a solution of TNPD (0.99 g, 3 mmol) in 30 ml
ethanol, 1 N aqueous NaOH (0.12 g, 3 mmol) was added followed
by an ethanol solution containing 1 mmol EuCl3. The reaction mix-
ture was stirred at 60 °C for 5 h and yellow precipitate was formed.
The product was purified by washing for several times with deion-
ized water and ethanol and dried in vacuum at 80 °C for 48 h to ob-
tain the complex C1. Yield: 73%. IR
2867(m), 1600(s), 1524(s), 1498(s), 1463(s), 1416(s), 1392(s),
m (KBr): 3056(m), 2962(s),
1H NMR spectra
1363(s), 1344(s), 1299(s), 1269(s), 1194(s), 789(s), 756(s),
472(m) cmꢁ1
;
1H NMR (300 MHz, CDCl3):
d
1.37 (s, 27H,
The characteristic 1H NMR spectral data of the free ligands and
complexes are listed in Table 2. From Table 2, the free ligand TNPD
showed a singlet for the methine proton at d 7.00 ppm, the keto-
CH2 proton at d 4.70 ppm and the enolic proton at d 17.10 ppm.
The keto-CH2 proton and enolic proton signals were not observed
C(CH3)3), 3.05 (s, 3H, C@CH), 6.42 (d, 6H, ArAH, J = 7.8 Hz), 6.60
(d, 6H, ArAH, J = 7.5 Hz), 7.72–7.80 (m, 18H, ArAH), 8.51 (s, 3H,
ArAH) ppm; Anal. Calcd. for EuC69H63O6: C, 72.68; H, 5.57;
Eu,13.33; Found C, 72.42; H, 5.50; Eu, 13.51.

D. Wang et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 117 (2014) 245–249
247
COOC2H5
O
O
COCH3
(1) NaNH2, 2) H+
Toluene, 80 oC
+
C(CH3)3
TNPD
C(CH3)3
O
O
NaOH
Ethanol
+ EuCl3
C(CH3)3
O
O
Eu
3
C1
(H3C)3C
N
N
O
O
O
Eu
NaOH
O
+ EuCl3 + Bipy
C(CH3)3
Ethanol
C(CH3)3
3
C2
O
O
N
N
O
Eu
NaOH
+ EuCl3 + Phen
C(CH3)3
O
Ethanol
C(CH3)3
3
C3
Scheme 1. The synthetic routes of b-diketone and its complexes.
Table 1
The characteristic IR data of the ligand TNPD and complexes.
due to paramagnetism of the europium ion [15,16]. In addition,
the signals for aryl protons of b-diketone also shifted to high-field
in the europium (III) complexes. However, the proton signals of
coordinated Bipy or Phen have been found to shift remarkably to
lower fields compared with the free Bipy or Phen, which assigned
to the electron-withdrawing inductive effect of coordination. This
result was in agreement with the literature [17].
Complex
m
(OAH)
m
(C@O)
m
(C@N)
m
(C@C)
m
(EuAN)
m
(EuAO)
TNPD
C1
C2
3500(w) 1628(s)
–
–
1528(s)
1524(s)
1523(s) 506(m)
1521(s) 505(m)
–
–
–
–
–
–
1600(s)
1599(s)
1599(s)
472(m)
473(m)
473(m)
1548(s)
1548(s)
C3
Table 2
Comparison of proton chemical shifts (ppm) for the ligands and complexes.
UV–vis spectra
Compound
dketo-CH2
dC@CAH
dOAH
dBipy-H
dPhen-H
TNPD
Bipya
Phena
C1
C2
C3
4.70
–
–
–
–
7.00
–
–
3.05
2.95
2.98
17.10
–
–
–
Fig. 1 gave the UV–vis absorption spectra of the ligand TNPD
–
–
–
–
–
7.22–8.70
–
–
8.28–12.01
–
and the europium complexes (C1–C3) in chloroform (1 ꢃ 10ꢁ5
-
)
7.63–9.19
–
–
mol/L). It can be seen that the maximum absorption peak (kmax
of TNPD is at 368 nm, which was attributed to TNPD-enol isomer
absorption band, and the kmax of complexes C1–C3 were red-shifted
to around 377, 379, 380 nm, respectively. The results indicated the
ligand TNPD was coordinated to the europium ion acting as enol
form. Therefore, the obvious bathochromic effect for the europium
–
8.93–10.98
a
Ref. [18].
the in 1H NMR spectra of complexes C1–C3. But their methine pro-
tons exhibited a single peak at d = 2.95–3.05 ppm and displayed
much larger shift to high-field with respect to the ligand, which
complexes most probably arise from the intense p–
p⁄ transition of
the conjugated chromophore due to the chelation between the
europium ion and organic ligands.

248
D. Wang et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 117 (2014) 245–249
3.0
2.5
2.0
1.5
1.0
0.5
0.0
because the secondary ligand Phen participates in the coordina-
TNPD
C1
tion. This is helpful for the photoluminescence intensity of the
complex C3.
C2
The decay curves of 5D0 level for complexes C1, C2 and C3 were
investigated by monitoring the emission of 613 nm, 613 nm and
612 nm, respectively (Fig. 3). It was found that the decay curves
for these complexes fitted approximately a single exponential de-
cay law, indicating only one chemical microenvironment around
C3
where the Eu3+ ion existed [21]. The lifetime values (
s) for the
emission of complexes C1–C3 are listed in Table 3, which were
determined from fittings of the decay curves. The results showed
that the lifetime value of the complex C3 presented longer lifetime
than that of complexes C1 and C2, suggesting that the introduction
of the secondary ligand Phen can enhance the photoluminescence
stability of the overall coordination system.
250
300
350
400
450
Wavelength / nm
According to the emission spectra and lifetimes of complexes
Fig. 1. UV–vis absorption spectra of the ligand TNPD and complexesC1,C2 and C3 in
chloroform solution (1 ꢃ 10ꢁ5 mol/L).
C1–C3, the luminescent quantum efficiency (
g) for the emitting
5D0 level can be determined. The quantum efficiency,
g
expresses
how well the radiative processes (characterized by the rate con-
stantArad) compete with non-radiative processes (overall rate con-
stant Anrad) [19].
5D0 7F2
200
C1
C2
C3
Arad
Arad þ Anrad
g
¼
ð1Þ
150
100
50
Assuming that only non-radiative and radiative processes are
essentially involved in the depopulation of 5D0 state, non-radiative
and radiative processes influence the experimental luminescence
lifetime (s) by the following equation:
1
s
Atot
¼
¼ Arad þ Anrad
ð2Þ
Here Arad can be calculated by summing over the radiative ratesA0J
P
for each 5D0 ? 7FJ transition ( JA0J) of the europium ion. And A0J is
5D0 7F1
5D0 7F0
5D0 7F3
5D0 7F4
obtained according to the equation as follows [22]:
0
I0J m01
I01 m0J
560
580
600
620
640
660
680
700
720
A0J ¼ A01
ð3Þ
Wavelength / nm
where I0J is the area under the curve related to the 5D0 ? 7FJ transi-
tions (J = 1, 2 and 4) obtained from the spectral data, and m0J is en-
ergy barycenter of transition. The 5D0 ? 7F1 transition does not
depend on the local ligand field seen by europium ion and, thus,
may be used as a reference, the value of A01 is estimated to be
ꢄ50 sꢁ1 [23].
Fig. 2. The emission spectra for complexes C1, C2 and C3 in the solid state at room
temperature, excited around 398, 405 and 407 nm, respectively.
Photoluminescence properties
Fig. 2 presents the photoluminescence spectra of the europium
complexes C1, C2 and C3 in the solid state at room temperature.
Their emission spectra displayed the characteristic emission lines
The obtained radiative decay rates Arad, the non-radiative decay
rates Anrad and the luminescence quantum efficiency
g are also pre-
sented in Table 3. From Table 3, complex C3 presented a longer life-
:
for Eu3+ 5D0 ? 7F0 (580 nm), 5D0 ? 7F1 (591 nm), 5D0 ? 7F2
(612 nm), 5D0 ? 7F3 (653 nm), and 5D0 ? 7F4 (702 nm). The hyper-
sensitive 5D0 ? 7F2 transition is very intense, pointing to a highly
polarizable chemical environment around the Eu3+ ion, and is
responsible for the brilliant-red emission color of these complexes.
The very weak emissions bands at about 580 nm and 653 nm in
these spectra were due to the forbidden transition for 5D0 ? 7F0
and 5D0 ? 7F3 both in magnetic and electric dipole schemes. It
was well-known that the 5D0 ? 7F1 transition is a parity-allowed
magnetic dipole transition and is nonsensitive to the local struc-
ture environment, while the 5D0 ? 7F2 transition is an induced
electric dipole transition and is a very sensitive to the condition
environment [19]. In addition, the photoluminescence intensity
of europium complex C3 is much higher than that of complexes
C1 and C2 corresponded to the coordination of the ‘‘antenna’’
ligands to the europium ion, which causes an efficient energy
transfer from the ligands to central the Eu3+ ion [20]. 1,10-Phenan-
throline is a ligand which has high affinity toward various lantha-
nide ions, especially toward Eu3+ ion. The asymmetry of the
complex C3 is increased and prevented the 4f–4f transition
C1
500
C2
C3
400
300
200
100
0
0.0
0.2
0.4
0.6
Time / ms
0.8
1.0
1.2
Fig. 3. The luminescence decay curves for complexes C1, C2 and C3 in the powder
monitored at 613, 613 and 612 nm, respectively.

D. Wang et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 117 (2014) 245–249
249
Table 3
Experimental intensity parameters and lifetimes of the 5D0 emitting level for complexes C1–C3.
Complex
s
(ms)
Atot (sꢁ1
)
Arad (sꢁ1
)
Anrad (sꢁ1
)
X2 (10ꢁ20 cm2)
X4 (10ꢁ20 cm2)
g (%)
C1
C2
C3
0.017
0.063
0.366
58,823
15,873
2732
516
1074
1370
58,307
14,799
1362
12.6
30.3
38.5
1.8
0.8
2.1
0.8
6.8
50.1
time
s
(0.366 ms) and higher luminescence quantum efficiency
g
state. The results of their emission spectra and lifetime decay
curves indicated that there was one luminescence center in these
complexes, and the europium ion was located in a polarizable
chemical environment. Based on the emission spectra and lifetime
of the 5D0 emitting level in solid state, experimental intensity
parameters (X2 and X4), the radiative decay rate Arad, the nonradi-
(50.1%), which was in agreement with the results from their lumi-
nescence emission intensity. The results showed that the introduc-
tion of the secondary ligand Phen in europium complex could
effectively increase their quantum efficiency. Moreover, the lumi-
nescence quantum efficiency of complex Eu(TNPD)3ꢂPhen is much
higher than that of some corresponding dibenzoylmethane (DBM)
ative rates Anrad, the lifetime (s) and the quantum yield (g) were
europium complexes, such as Eu(DBM)3ꢂPhen (
Eu(4-methoxy-DBM)3ꢂPhen ( = 38.8%) [9], europium complex with
1,3,5-tris(2,2-dibenzoylethyl) benzene and Phen ( = 28.0%) [25],
which due to the introduction of the naphthyl nucleus into the b-
diketone to extend -conjugate system of ligand. The mechanism
g
= 31.3%) [24],
calculated and the complex C3 exhibited a longer lifetime
(0.366 ms) and higher luminescence quantum efficiency
(50.1%). These results demonstrated that the secondary ligand
Phen could improve the luminescence properties of the Eu (III)
complex with b-diketone.
s
g
g
g
p
is that the triplet energy level of ligand gradually decreased with
increasing of the conjugate system, the energy level of TNPD ligand
perfectly matches the 5D0 energy level of the europium ion and its
complexes display the higher luminescence quantum efficiency.
Acknowledgment
Financial support for this work from National Natural Science
Foundation of China (No. 21273065).
Judd–Ofelt analysis
References
The Judd–Ofelt theory is useful tool for analyzing 4f–4f inner
shell electronic transitions. Interaction parameters of ligand fields
are given by the Judd–Ofelt Xt (t = 2, 4, and 6), in which X2 is more
sensitive to the symmetry and sequence of ligand fields [24]. The
JuddꢁOfelt intensity parameters Xt (t = 2, 4) can be determined
from the emission spectra (Fig. 2) using the 5D0 ? 7F2 and
5D0 ? 7F4 electronic transitions of the Eu3+ ion and they are calcu-
lated according to the following equation [26]:
[1] R. Pavithran, M.L.P. Reddy, S.A. Junior, R.O. Freire, G.B. Rocha, P.P. Lima, Eur. J.
Inorg. Chem. 2005 (2005) 4129–4137.
[2] H.F. Brito, O.L. Malta, J.F.S. Menezes, J. Alloys Compd. 303–304 (2000) 336–339.
[3] Y. Hasegawa, Y. Wada, S. Yanagida, J. Photochem. Photobiol. C 5 (2004) 183–
202.
[4] C. Yang, J. Xu, J. Ma, D. Zhu, Y. Zhang, L. Liang, M. Lu, Polym. Chem. 3 (2012)
2640–2648.
[5] K. Kuriki, Y. Koike, Y. Okamoto, Chem. Rev. 102 (2002) 2347–2356.
[6] R.D. Adati, S.A.M. Lima, M.R. Davolos, M. Jafelicci, J. Alloys. Compd. 418 (2006)
222–225.
[7] P. Shukla, V. Sudarsan, R.K. Vatsa, S.K. Nayak, S. Chattopadhyay, J. Lumin. 130
(2010) 1952–1957.
[8] C.-J. Xua, P.-F. Zhang, F.-M. Liu, Y.-Q. Shi, Synth. Met. 162 (2012) 18–21.
[9] D.-J. Wang, C.Y. Zheng, L. Fan, J. Zheng, X.-H. Wei, Synth. Met. 162 (2012)
2063–2068.
[10] L.R. Melby, N.J. Rose, E. Abramson, J.C. Caris, J. Am. Chem. Soc. 86 (1964) 5117–
5125.
[11] V. Sareen, R. Gupta, J. Fluorine. Chem. 76 (1996) 149–150.
[12] X. Jiang, Y. Wu, C. He, Mater. Lett. 62 (2008) 286–288.
[13] W. Zhang, C.-H. Liu, R.-R. Tang, C.-Q. Tang, Bull. Korean Chem. Soc. 30 (2009)
2213–2216.
[14] M. Arvind, K. Sageed, Indian J. Chem. 25A (1986) 589–594.
[15] Y. Zhang, H. Shi, Y. Ke, Y. Cao, J. Lumin. 124 (2007) 51–57.
[16] L. Fu, R.A.S. Ferreira, N.J.O. Silva, A.J. Fernandes, P. Ribeiro-Claro, I.S. Goncalves,
V. de, Z. Bermudez, L.D. Carlos, J. Mater. Chem. 15 (2005) 3117–3125.
[17] N.S. Bhacca, J. Selbin, J.D. Wander, J. Am. Chem. Soc. 94 (1972) 8719–8722.
[18] K. Iftikhar, Polyhedron 15 (1996) 1113–1120.
[19] M.H.V. Werts, R.T.F. Jukes, J.W. Verhoeven, Phys. Chem. Chem. Phys. 4 (2002)
1542–1549.
[20] N. Sabbatini, M. Guardigli, J.M. Lehn, Coord. Chem. Rev. 123 (1993) 201–228.
[21] H.F. Brito, O.L. Malta, L.R. Souza, J.F.S. Menezes, C.A.A. Carvalho, J. Non-Cryst.
Solids 247 (1999) 129–133.
3ꢀhc3A0J
Xt
¼
ð4Þ
5
7
2
4e2x3
v
h D0kUðtÞk FJi
2
where
v
¼ n20ðn20 þ 2Þ =9 is a Lorentz local field correction and an
average index of refraction equal to 1.5 was used. The squared
ꢀ
ꢀ
ꢀ
ꢀ
7
5
2
reduced matrix elements are h D0 Uð2Þ F2i = 0.0032 and
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
7
5
2
h D0 Uð4Þ F4i = 0.0023.
ꢀ
ꢀ
The experimental intensity parameters X2 and X4 are listed in
Table 3. From Table 3, the highest value of the X2 parameters
(38.5 ꢃ 10ꢁ20 cm2) was found for the complex C3, which indicated
the highest hypersensitive behavior of the 5D0 ? 7F2 transition,
which reflected the most polarizable chemical environment of
the europium ion. Also are noted that the higher value for the X4
parameter was obtained to the complex C3, suggesting that steric
factors prevent the Phen ligand from getting closer to the euro-
pium ion [27].
[22] L.D. Carlos, Y. Messaddeq, H.F. Brito, R.A.S. Ferreira, V.D. Bermudez, S.J.L.
Ribeiro, Adv. Mater. 12 (2000) 594–598.
[23] R. Ferreira, P. Pires, B. de Castro, R.A.S. Ferreira, L.D. Carlos, U. Pischel, New J.
Chem. 28 (2004) 1506–1513.
Conclusions
[24] H. Liang, F. Xie, Spectrochim. Acta Part A 75 (2010) 1191–1194.
[25] C. Yang, J. Luo, J. Ma, M. Lu, L. Liang, B. Tong, Dyes Pigm 92 (2011) 696704.
[26] E.E.S. Teotonio, H.F. Brito, M.C.F.C. Felinto, C.A. Kodaira, O.L. Malta, J. Coord.
Chem. 56 (2003) 913–921.
[27] H.F. Brito, O.L. Malta, C.A.A. Carvalho, J.F.S. Menezes, L.R. Souza, R. Ferraz, J.
Alloys Compd. 275–277 (1998) 254–257.
In this work, three novel Eu (III) complexes C1, C2 and C3 have
been designed, synthesized and characterized by FT-IR, 1H NMR,
ESI-MS, UV–vis absorption, elemental analysis and photolumines-
cence spectroscopy. The emission spectra for all complexes dis-
played the characteristic emission lines for europium ion in solid