Bright orange and red light-emitting diodes of new visible light excitable tetrakis-Ln-β-diketonate (Ln = Sm3+, Eu3+) complexes

Article abstract of DOI:10.1039/c6nj03450k

The syntheses and luminescent properties of two new visible light excitable lanthanide complexes (NBu₄[LnL₄]) [L = 1-(4-(9H-carbazol-9-yl)phenyl)-4,4,4-trifluorobutane-1,3-dione; (Ln = Sm³⁺, Eu³⁺)] are described

Full text of DOI:10.1039/c6nj03450k

View Article Online
View Journal
NJC
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: B. Silvanose, L. Xu,
M. A. H. Alves, R. O. Freire and Z. Chen, New J. Chem., 2017, DOI: 10.1039/C6NJ03450K.
This is an Accepted Manuscript, which has been through the
Volume 40 Number
1 January 2016 Pages 1–846
Royal Society of Chemistry peer review process and has been
accepted for publication.
NJC
Accepted Manuscripts are published online shortly after
New Journal of Chemistry
www.rsc.org/njc
A journal for new directions in chemistry
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
author guidelines.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the ethical guidelines, outlined
in our author and reviewer resource centre, still apply. In no
event shall the Royal Society of Chemistry be held responsible
for any errors or omissions in this Accepted Manuscript or any
consequences arising from the use of any information it contains.
ISSN 1144-0546
PAPER
Jason B. Benedict et al.
The role of atropisomers on the photo-reactivity and fatigue of
diarylethene-based metal–organic frameworks
rsc.li/njc

Please do not adjust margins
New Journal of Chemistry
Page 1 of 11
View Article Online
DOI: 10.1039/C6NJ03450K
Journal Name
ARTICLE
Bright Orange and Red Light-emitting Diodes of New Visible Light
Excitable Tetrakis-Ln-
-Diketonate (Ln = Sm3+, Eu3+) Complexes†
β
Received 00th January 20xx,
Accepted 00th January 20xx
Silvanose Biju,a,b* Liang-Jin Xu,a Marcelo Augusto Hora Alvesc, Ricardo Oliveira Freirec and Zhong-
Ning Chena*
DOI: 10.1039/x0xx00000x
The syntheses and luminescent properties of two new visible light excitable lanthanide complexes (NBu4[LnL4]) [L = 1-(4-
(9H-carbazol-9-yl)phenyl)-4,4,4-trifluorobutane-1,3-dione; Ln = Sm3+, Eu3+) is described within. The (NBu4[LnL4]) complexes
exhibit bright photoluminescence at room temperature in solid state with characteristic red and orange emissions of Eu3+
www.rsc.org/
and Sm3+ ions, respectively. Photoluminescent overall quantum yield (
φov) and life time (τobs) values obtained for the
complexes are 80 ± 8 %, 780 ± 6 ꢀs for NBu4[EuL4]) and 10 ± 1 %, 97 ± 2 ꢀs for NBu4[SmL4]) (λex = 410 nm) in solid state.
RM1 calculations were employed for predicting the ground-state geometry of NBu4[EuL4], which shows that the central
Eu3+ is 8-fold coordinated. Theoretical Judd–Ofelt and photoluminescence parameters predicted for NBu4[EuL4] from this
model are in close agreement with the experimental values, proving the efficiency of this theoretical approach
implemented in the LUMPAC software (http://lumpac.pro.br/theory). LEDs with the general structure ITO/PEDOT:PSS (50
nm)/(NBu4[LnL4]) (5%):CBP (66.5%) - OXD7(28.5%) (50 nm)/BCP (50nm)/LiF (1.5 nm)/Al (120 nm), using the two complexes
as emitters were fabricated by simple spin coating technique. The device based on (NBu4[EuL4]) exhibits the maximum
brightness of 1234 cd/m2, current efficiency of 3.5 cd/A, power efficiency of 1.3 lm/W and external quantum efficiency of
2.3% with a pure red emission. Whereas, its Sm3+ analogue shows bright orange emission with maximum brightness of 831
cd/m2, current efficiency of 1.4 cd/A, power efficiency of 0.5 lm/W, and external quantum efficiency of 1.1%.
transport properties of Ln3+-complexes can be improved either
by doping them into appropriate carrier materials9-13 or by a
proper modification of the ligands through the introduction of
Introduction
Ln3+-
β-diketonate complexes present an astounding class of
emissive materials for OLEDs due to unique optical properties
like extremely sharp emission bands and high internal
quantum efficiencies (theoretically up to 100%).1-3 In particular
Eu3+ complexes with fluorinated
the charge-transport groups to ligands.14-18 In the first method,
phase separation occurs between the host and guest during
the device operation and hence the charge transporting group
linked to the Ln3+-complexes by covalent bonding approach is
preferred. Among all the charge transport groups covalently
linked to the ligand systems, carbazole based ligands play a
major role because of being cheap starting materials, its good
chemical and environmental stability, and the ease in
attaching to a wide variety of functional groups in order to
tune the optical and electrical properties.19-21 Thus, a large
number of Eu3+-complexes containing carbazole moieties have
β-diketonate ligands are
characterized by high photoluminescence efficiency (20-95%)
both in solution and in solid state.4, 5 The presence of fluorine
in place of hydrogen atom in a ligand not only increases the
volatility of the complex thus making device fabrication easier,
but also leads to improved thermal and oxidative stability and
reduced vibrational quenching of the luminescence.6-8
However, a large majority of Ln3+-
β-diketonates studied are
known to have poor carrier-transport ability. The carrier-
been reported to serve as efficient light conversion molecular
In particular, Eu3+-complexes sensitized by
22-24
devises.8,
carbazole functionalized β-diketones moieties have been
proven as good electroluminescent materials.25-27
aState Key Laboratory of Structural Chemistry, Fujian Institute of Research on the
Structure of Matter, Chinese Academy of Science, Fuzhou, Fujian 35002, China
E-mail: czn@fjirsm.ac.cn
A recent challenge in the photophysics of the Eu3+ ions is to
develop luminescent Eu3+ complexes that can be sensitized by
low energy visible light and this field has much relevance in the
present world because of the increasing demand for low-
voltage-driven pure-red LEDs. The main strategies that can be
adopted to achieve visible light excitation are either the
introduction of a transition metal ion such as Ir(III)28 or Pt(II)29
into the Eu3+ complex molecule with an efficient energy
bLaboratory of Bioinorganic Chemistry, Department of Chemistry, Katholieke
Universiteit Leuven, Celestijnenlaan 200F, P. O. Box 2404, B-3001 Heverlee, Belgium
E-mail: drbijusilvanose@gmail.com
cPople Computational Chemistry Laboratory, Departamento de Quımica,
UniversidadeFederal de Sergipe, 49.100-000, São Cristóvão - SE, Brazil
E-mail: rfreire@ufs.br
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 2 of 11
View Article Online
DOI: 10.1039/C6NJ03450K
ARTICLE
Journal Name
transfer to the Eu3+ ion, or the modification of the ligand geometries of lanthanide compounds for the cases when the Ln3+ is
molecule with an expanded π-conjugated system to shift the directly coordinated to any other atoms, not only oxygen or
excitation band of its Eu3+ complex to the visible region.30 nitrogen, as was the case of the Sparkle model. A detailed study
Many investigations showed that the PL efficiency of Eu3+ showed that the errors obtained with the RM1 to prediction of the
complexes sensitized by ligands containing Ir(III) and Pt(II) coordination polyhedron has decreased significantly.35 In the case
units was always very low involving the 3MMLCT (metal-metal- of europium compounds, for interatomic distances of coordination,
to-ligand charge transfer) or 3MLCT (metal-to-ligand charge the overall error associated with the previous Sparkle Models is
31
transfer) transitions.28,
Thus the second approach is about 5% and for RM1 model the coordinating bonds are now
preferred. However, the selection of expanded π-conjugated predicted within accuracy of 2%. Thus we predicted the ground
system requires extreme care. It cannot be either too small to state geometry and PL properties of NBu4[EuL4] using RM1
absorb visible light or too big to raise the triplet state of the method. The experimental PL and EL properties of NBu4[LnL4]
5
ligand very close to D0, the lowest excited state energy level of (Ln= Sm3+, Eu3+) were investigated. The NBu4[GdL4] was
of the central Eu3+ ion. Phenanthrene,32 fluorine30 and used for the determination of ligand energy states.
carbazole33 groups connected to
β-diketones are known to Experimental
expand the excitation window of their Eu3+ complexes to the Materials
visible region. Among them, the carbazole-containing Lanthanide(III) nitrate hexahydrates 99.99% (Sm, Eu, Gd) were
β
-
diketonates exhibit distinguished advantages as they can lower obtained from Sigma Aldrich. 9H-Carbazole 98 % (Acros
the excitation energy and can improve the carrier-transport Organics), 4-Iodo-acetophenone 98% (Beijing HWRK Chem),
abilities simultaneously. However it has been noticed that in ethyltrifluoroacetate 98% (Accela Chem Bio) and tetra-n-
most of the cases the achievement of visible light sensitization butylammoniumbromide 98% (Acros Organics) were used
is at the expense of lowering the triplet energy levels of the without further purification. Solvents were dried using
ligands. For example, He et al. developed
β-diketonates standard procedures. All the other chemicals used were of
containing 2-or 2,7-position substituted carbazole rings namely analytical reagent grade.
2-(4'4'4'-trifluoro-1'3'-dioxobutyl)-carbazole (2-TFDBC) and Methods
2,7-bis(4'4'4'-trifluoro-1'3'- dioxobutyl)-carbazole (2,7-BTFDBC) Elemental analysis (C, H, N) was carried out on a Perkin-Elmer
and their blue-light excitable Eu3+ complexes.24 The model 240 C elemental analyzer. Infrared spectra (IR) were
photoluminescence obtained from these Eu3+ complexes are recorded on a Magna 750 FT-IR spectrophotometer with KBr
not sufficient enough for OLED technology. It is mainly due to (neat) pellets. Electrospray ionization mass spectrometry (ESI-
the lower energies of the triplet states of the ligands (18115 MS) was performed on a Finnigan LCQ mass spectrometer
cm-1: 2-TFDBC and 18051 cm-1: 2,7-BTFDBC), which are close to using dichloromethane as mobile phases. 1H and 13C NMR
the 5D0 (17 250 cm-1) state of Eu3+ and their energy gaps,
ꢁE = spectra were recorded on a Bruker Avance III 400
[(π−π*)3 – 5D0] = 865, 801 cm-1 respectively, are not enough to spectrometer with SiMe4 as internal reference. The
prevent the nonradiative back energy transfer.34 Thus in the thermogravimetric analysis (TGA) was performed on a TGA-
present study we have designed a new a
β
-diketone ligand by 50H instrument (Shimadzu, Japan). UV−vis absorpꢀon spectra
Perkin-Elmer Lambda 35 UV−vis
connecting the cabazole ring to benzoyltrifluoroacetone were measured on
a
(BTFA), a known photo-sensitizer for Eu3+, through the N-atom spectrophotometer. The cyclic voltammogram (CV) was
(9-position) of carbazole ring. The attachment of carbazole ring measured using a potentiostat/galvanostat model 263A in
to the BTFA unit through N-atom (9-position) will break the dichloromethane solution containing 0.1 M (Bu4N)(PF6) as the
extended conjugation and hence the triplet energy level of supporting electrolyte. Platinum and glassy graphite were used
BTFA is expected to be preserved.
The large majority of available reports used neutral tris-Ln3+-
β-
as the counter and working electrodes, respectively, and the
potential was measured against Ag/AgCl reference electrode.
diketonates as emitting materials in OLEDs. However it is Photoluminescence emission, excitation, excited state
known that the anionic tetrakis- Ln3+-
-diketonates are more lifetimes (solid state) and electroluminescence emission
luminescent than neutral tris-Ln3+- -diketonates.4 Recenty we spectra were recorded on an Edinburgh analytical instrument
have showed that pure white electroluminescence can be (F900 fluorescence spectrometer). The PL emission quantum
generated by employing -diketonate as yields (ϕov) in solid-state were determined by the absolute
tetrakis-Eu3+-
β
β
a
β
emiting layer in OLEDs.26 Thus in this work the newly method using an integrating sphere attached to F900
synthesized ligand (HL) is complexed with Sm3+, Eu3+ and Gd3+ fluorescence spectrometer. All the spectra were corrected for
in a metal to ligand ratio of 1:4 to form the anionic tetrakis- experimental responses. Using as input data the experimental
Ln3+- -diketonates. The obtained NBu4[LnL4] (Ln= Sm3+, Eu3+, emission spectrum we carried out the calculation of
β
Gd3+) are well characterized by various spectroscopic experimental (or phenomenological) Judd-Ofelt intensity
techniques. The next challenge we faced was the accurate parameters36, 37 and experimental emission decay rate (Arad).
prediction of, the ground state geometry and PL properties of These calculations were done in the LUMPAC software38 in a
newly developed amorphous complexes, in the absence of specific module for the obtainment of the experimental
single crystals. This issue was solved by using RM1 model for quantities. Details of experimental methods adopted for the
lanthanides, which was developed to be a much more general theoretical calculations are presented in the supporting
NDDO method. The RM1 for lanthanides is capable of predicting information (SI)† part.
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 3 of 11
View Article Online
DOI: 10.1039/C6NJ03450K
Journal Name
ARTICLE
3.88. FTIR (KBr, cm-1): 3450 (νs O‒H); 3071, (ν Csp2H); 1650,
1590 (νs C=O); 1516, 1472, 1469, 1449 (ν C=C); 1361, 1235
(νsC‒N); 1147, 1098 (δC‒H); 1100 (νsC‒F); 844, 795 (δ C‒H),
OLEDs Fabrication and Characterization
The OLEDs were fabricated on indium tin oxide (ITO) coated glass
substrates. Patterned ITO coated glass substrates were washed with
acetone, detergent, distilled water and isopropanol, subsequently
in an ultrasonic bath. After UV Ozone treatment for 15 minutes,
PEDOT: PSS (Batron-P 4083, Bayer AG) from water solution was
spin-coated (at 3000 rpm) onto the substrate followed by drying in
a vacuum oven at 140 °C for 20 min, giving a film of 50 nm thickness.
1
712 (δ CF3). H NMR (CDCl3, 400 MHz), δ (ppm): 6.69 (1H, s),
7.36-7.39 (2H, t; J = 7.4 Hz), 7.46-7.49 (2H, t; J = 7.4 Hz), 7.53-
7.55 (2H, d; J = 8.4 Hz), 7.78-7.80 (2H, d; J = 8.8 Hz), 8.18-8.22
(4H, q; J = 6.8 Hz), 15.22 (1H, s: broad). 13C NMR (CDCl3, 400
A mixture of CBP/OXD7 and NBu4[LnL4] (Ln= Sm3+, Eu3+) (66.5:28.5:5) MHz)
δ
(
ppm):
92.40
(CO‒CH‒CO);
109.76-143.20
in CH2Cl2 (5.5 mg/mL) was spin-coated on the top of PEDOT: PSS (at
1500 rpm). Typically, the thickness of the emitting layer was around
50 nm. The TPBI layer (50 nm) was then thermally deposited
followed by a thin layer of LiF(1.5 nm) with a 120 nm thick Al
capping layer deposited through a shadow mask in a chamber with
a base pressure of around 10-4 Pa. Current density (J)-voltage (V)-
Brightness (L) data were collected using a Keithley 2400/2000
source measurement unit (source voltage 5μV - 210V; measure
voltage from 1μV - 211V, source current from 50pA - 1.05A;
measure current from 10pA - 1.055A, measure resistance from
100μꢂ (<100μꢂ in manual ohms) to 211Mꢂ, maximum source
power is 22W) and a calibrated silicon photodiode. The brightness
in cd m-2 was measured by a silicon photodiode.
(carbazole/phenyl); 129.43 (CF3); 177.25, 184.89 (CO). m/z =
380.3 (100%) [M-H]‒.
Synthesis of [NBu4(LnL4)] (Ln= Sm, Eu, Gd)
The tetrakis complexes [NBu4(LnL4)] (Ln= Sm, Eu, Gd) were
synthesized as described in our previous publications.6, 26, 39
Synthesis of the ligand HL
The ligand HL was prepared in a two-step process with an
overall yield of 70% (Scheme 1). In the first step, a mixture of
carbazole (20 mmol), Cu(0) (2.68 mmol), 18-Crown-6 (6.55
mmol), 4-iodoacetophenone (21 mmol) and K2CO3 (80.3 mmol)
in dry dimethylformamide (DMF, 40 mL) was stirred and
heated at 170°C for 50 h. The hot mixture was cooled, diluted
with H2O (40 mL) and the product was extracted with CHCl3 (3
× 50 mL). The CHCl3 layer was washed with H2O and brine and
was then dried over anhydrous MgSO4. The product, 1-(4-(9H-
Scheme 2. Synthetic procedure for the Ln3+ complexes NBu4[LnL4].
NBu4[SmL4] (yellow solid). Yield: 94%. Elemental analysis (%) calcd.
for C104H88F12SmN5O8 (1914.18): C, 65.26; H, 4.63; N, 3.66. Found: C,
65.48; H, 4.81; N, 3.85. FTIR (KBr, cm-1): 3060, (νs O–H); (ν Csp2H);
2976, 2959, 2936, 2870 (ν Csp3H); 1680, 1623 (νs C=O); 1517, 1473,
carbazol-9-yl)phenyl)ethanone (CPE) was purified by silica 1470, 1446 (ν C=C); 1360, 1238 (νsC‒N); 1145, 1096 (δC‒H); 1101
(νsC‒F); 844, 795 (δ C‒H), 715 (δ CF3). m/z= 1671.9 (100%)[(SmL4)] ‒.
column chromatography (petroleum ether/ CH2Cl2) to give a
pale yellow solid (14 mmol) in 70% yield. In the second step
the 1-(4-(9H-carbazol-9-yl)phenyl)ethanone synthesized in the
first step (10 mmol) and NaH (11 mmol) were added to 50 mL
of dry tetrahydrofuran (THF) and stirred for 10 min at 0°C. To
this solution, ethyltrifluoroacetate (11 mmol) was added
dropwise in an inert atmosphere and temperature was
increased to 60°C and stirred for another 12 h. To the resulting
yellow solution, 50 mL of 2 M HCl was added, and the mixture
was extracted with dichloromethane (2×50 mL). The organic
layer was separated and dried over MgSO4, and the product
was obtained as fine yellow crystals in 100% yield from
evaporation of the CH2Cl2.
NBu4[EuL4] (yellow solid). Yield: 95%. Elemental analysis (%) calcd.
for C104H88F12EuN5O8: (1915.79): C, 65.20; H, 4.63; N, 3.66. Found: C,
65.35; H, 4. 94; N, 3.90. FTIR (KBr, cm-1): 3059, (ν Csp2H); (ν Csp2H);
2975, 2959, 2936, 2873 (ν Csp3H); 1681, 1623 (νs C=O); 1517, 1471,
1470, 1446 (ν C=C); 1360, 1237 (νsC‒N); 1145, 1097 (δC‒H); 1101
(νsC‒F); 844, 795 (δ C‒H), 715 (δ CF3). m/z= 1673.5 (100%) [(EuL4)]‒.
NBu4[GdL4] (yellow solid). Yield: 95%. Elemental analysis (%) calcd.
for C104H88F12GdN5O8 (1921.07): C, 65.02; H, 4.64; N, 3.65. Found: C,
65.48; H, 4.81; N, 3.85 FTIR (KBr, cm-1): 3056, (ν Csp2H); (ν Csp2H);
2974, 2960, 2936, 2873 (ν Csp3H); 1680, 1622 (νs C=O); 1517, 1470,
1470, 1446 (ν C=C); 1361, 1237 (νsC‒N); 1145, 1095 (δC‒H); 1100
(νsC‒F); 844, 795 (δ C‒H), 714 (δ CF3). m/z= 1678.3 (100%) [(GdL4)] ‒.
Results and Discussion
Synthesis and Spectroscopic Characterization
The ligand HL in enolic form was synthesized by two step processes
using 9H-carbazole, 4-iodo-acetophenone and ethyltrifluoroacetate
40
by known procedures (Scheme 1).26,
The tetrakis complexes
Scheme 1. Synthetic procedure for ligand HL.
[NBu4(LnL4)] (Ln= Sm, Eu, Gd) were synthesized according to a
HL (yellow solid). Yield: 70%. Anal. Calcd. for C22H14F3NO2
(381.35): C, 69.29; H, 3.70; N, 3.67. Found: C, 69.57; H, 3.89; N,
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 4 of 11
View Article Online
DOI: 10.1039/C6NJ03450K
ARTICLE
Journal Name
Table 1 Spherical Atomic Coordinates for the RM1 Coordination Polyhedron of NBu4[EuL4] compound, Charge Factors (g) and the
Polarizability (α) of the Coordinated Atom.
Atom
R/Å
θ/o
ϕ/o
ga
αa
1.9632 × 10-24
1.2085 × 10-24
0.4028 × 10-24
1.7115 × 10-24
1.8127 × 10-24
0.7437 × 10-24
7.3037 × 10-24
8.0991 × 10-24
2.3729
2.4172
2.3732
2.4148
2.3727
2.4123
2.3746
2.4159
56.56
69.44
136.45
139.49
99.49
116.14
68.58
33.15
215.19
141.76
89.56
0.2224
0.2219
0.2224
0.2219
0.2224
0.2219
0.2224
0.2219
O1 (
O2 (
O3 (
O4 (
O5 (
O6 (
O7 (
β
β
β
β
β
β
β
β
-diketone 1)
-diketone 1)
-diketone 2)
-diketone 2)
-diketone 3)
-diketone 3)
-diketone 4)
-diketone 4)
197.31
278.25
345.56
58.19
340.44
O8 (
a
Obtained using the procedure based on the electronic densities and superdelocalizabilities for a unique adjustment of the Ωλ
parameters.41
the range 450-600 °C leaving residual masses of ∼12-15%, which
account for the formation of corresponding lanthanide oxides and
oxyfluorides.
Electronic Absorption Spectroscopy and Ligand-Centred Energy
Levels
The electronic absorption spectra of the ligand HL and NBu4[LnL4]
(Ln = Sm3+, Eu3+, Gd3+) were recorded in CH2Cl2 solutions as shown
in Fig. 2. Owing to the electronic transitions of the organic
chromophores, the ligand HL and its Ln3+ complexes display well-
defined absorption bands in the range 200-450 nm with maxima at
237-239 nm and two to three well separated low energy shoulders
(Table 2). The absorption bands below 300 nm can be attributed to
44
the π−π* transitions of carbazole moieties.26,
The absorption
Fig. 1 The ground state geometry of NBu4[EuL4] calculated using the
band of HL with maximum at 391 nm can be related to the π−π
*
RM1 model; (a) coordination polyhedron.
transition of −diketone or an intra-ligand charge transfer (ILCT) or
β
a combination of both. The ILCT transition is normally observed in
ligands with donor–acceptor electronic structures.22
literature procedure (Scheme 2).6, 26, 39 The newly synthesized ligand
1
and complexes were characterized by FTIR, H-NMR (Fig. S1)†, 13C-
NMR (Fig. S2)† spectroscopy and elemental analysis. The results of
the above mentioned analyses showed that each Ln3+ ions are
coordinated to four β
-diketonates (L–) and one molecule of (NBu4)+
cation is present in the outer sphere, to provide electrical neutrality.
The formation of tetrakis complexes was further confirmed by the
presence of base peaks m/z = 1671.9 [(SmL4)]‒, 1673.5 [(EuL4)]‒ and
1678.3 [(GdL4)]‒ in the ESI mass spectral analysis (Fig. S3-S5)†. In the
absence of single crystals, ground state geometry of NBu4[EuL4] was
calculated using the RM1 model42 (Fig. 1). The average Eu–O bond
length 2.39(4) Å computed using RM1 (Table 1), closely matches
with the median value observed for 96 analogous compounds with
O-O-chelating β
-diketonates: 2.37 Å.43 The coordination polyhedron
around the Eu3+ ion can be best described as a distorted square
antiprism (Fig. 1a). The thermal behavior of the NBu4[LnL4] (Ln=
Sm3+, Eu3+
,
Gd3+) was examined by TGA (Fig. S6)†. All three
Fig. 2 UV-vis absorption spectra of HL and its complexes NBu4[LnL4]
(Ln = Sm3+, Eu3+, Gd3+) in CH2Cl2 at 298 K; (c ∼ 1×10-5); (a) Corrected
compounds decompose in two main steps up to 600 °C, with the
onset of decomposition being in the range 190-200 °C. The first phosphorescence spectrum of NBu4[GdL4] at 77 K in CDCl3, (c ∼
step (up to ca. 300 °C) and the second weight loss event occurs in
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 5 of 11
View Article Online
DOI: 10.1039/C6NJ03450K
Journal Name
1×10-5, delay increment 0.5 ms, λex = 343 nm); vertical scales being achieved through the
ARTICLE
β
-diketonate part whereas for NBu4[SmL4],
arbitrary units.
the major energy transfer is from the carbazole part. It is surprising
to note that the excitation maxima obtained for
Table 2 UV-Vis absorption spectral data of the ligand HL and its
complexes NBu4[LnL4] (Ln = Sm3+, Eu3+, Gd3+) in DCM at 298 K; (c ∼
1×10-5).
max / nm (ε
/ 104 M-1 cm-1)
Compound
λ
HL
391 (0.48986), 337 (0.35852), 323 (0.37960), 291
(0.64825), 260 (0.61321), 249 (0.93138), 239
(1.47239)
NBu4[LaL4]
344 (1.95121), 329 (1.54416), 293 (1.61481), 284
(1.25086), 259(2.18268), 247 (3.44726), 237
(4.65178)
NBu4[SmL4] 342 (1.7735), 329 (1.58738), 293 (1.68245), 284
(1.54811), 259 (2.08283), 238 (3.30368)
Fig. 3 Corrected, normalized excitation (
λ
em= 612 nm; NBu4[EuL4])
ex= 410 nm) spectra
NBu4[EuL4] 344 (1.95121), 329 (1.54416), 293 (1.61481), 284
(1.25086), 259(2.18268), 247 (3.44726), 237
(4.65178)
and ( em= 648 nm ; NBu4[SmL4]) and emission (
λ
λ
at 298 K in solid state; vertical scales being arbitrary units.
NBu4[EuL4] here (410 nm) is longer than that obtained for the Eu3+
complex with 4-(4′-carbazol-9-yl-biphenyl-4-yl)- 1,1,1- trifluoro -4-
Here the carbazole moieties can act as the donor whereas carbonyl
and CF3 groups at the β-diketonate can accept the electrons. Upon
(400nm).26
coordination with the Ln3+ ions, the absorption maxima of HL (239
nm) show a small blue shift (1-2 nm), indicating that the carbazole
centred energy states have little influence by the coordination of
the Ln3+ ions. On the other hand, the lower energy absorption band
of HL with maximum at 391 nm shows a profound effect on metal
complexes (342-344 nm). In fact the absorption band centred at
391 nm was replaced by bands around 342-344 nm after
coordination. This band shows a blue shift of nearly 50 nm in
complexation with Ln3+ ions. It may be the result of the lowering of
electron affinity of carbonyl end of the L– after metal coordination
and thus weakening the possibilities of ILCT transition. The singlet
energy levels S1(π−π*)1 of the Ln3+ complexes were calculated from
their lower wavelength absorption edges and are found to be
identical (25,188 cm-1/ 3.123 eV: 397 nm). The triplet energy level
T1(π−π*)3 of HL is calculated from the higher energy band of the
phosphorescence spectrum of NBu4[GdL4] (Fig. 1, inset a) as 20,000
cm-1/ 2.480 eV (500 nm). These values shows that the energy level
difference between the lowest triplet state of ligand and receiving
oxo-
but-2-en-2-ol
anion
as
ligand
This observation is against a widely accepted theory that biphenyl
system bathochromically shifts the excitation window than phenyl
system due to the conjugation effects. The only possible
explanation for this unexpected bathochromic shift in the excitation
maximum of NBu4[EuL4] is the involvement of ILCT transition, which
is absent in the case of 4-(4′-carbazol-9-yl-biphenyl-4-yl)-1,1,1-
trifluoro-4-oxo-but-2-en-2-ol anion as ligand. When excited using
blue light (410 nm), in solid state at room temperature, both the
complexes show highly intense luminescence. The emission
obtained from NBu4[EuL4] is red (CIE = 6.45, 2.71) in colour whereas
Table 3. Intensity parameters (Ωn), radiative (Arad), non-radiative
(Anrad) decay rate, 5D0 lifetime (
sensitization efficiency ( sen), and overall quantum yield (
NBu4[EuL4] complex at 298K in solid state and 5 weight % doped
τobs) intrinsic quantum yield (
φLn),
φ
φov) of
thin PMMA film (
λ
ex = 410 nm).a
state [ꢁ
E = (π−π*)3 – Ln(f-f)*] for Eu3+ (5D0) is 2750 cm-1 and for
Parameters
Experimental
Theoretical
film
Sm3+ (4G5/2) is 2100 cm-1, and is ideal for efficient sensitization of
the luminescence for both these ions.35
Solid
Film
Solid
Ω2/10-20 cm2
Ω4/10-20 cm2
Ω6/10-20 cm2
27.89
6.66
28.40
8.56
28.44
6.70
28.80
8.60
Ln3+-Centred PL Properties of Complexes
—
—
0.30
0.32
The corrected photoluminescence excitation and emission spectra
of NBu4[LnL4] (Ln = Sm3+, Eu3+) in solid state at 298 K are presented
in Fig. 3. The excitation spectra of both the complexes show broad
bands, characteristics of the organic chromospheres, covering the
entire UV region and extending up to the visible region (250-500
nm). Both the excitation spectra contain two structures centred at
300 and 410 nm, respectively, corresponding to the absorption due
780 ± 6
979.51
1020.92
261.13
79.63
99.53
80 ± 8
796 ± 6
932.76
1072.09
184.19
85.33
99.61
85 ± 9
—
—
τobs
τrad
/
ꢀ
s
995.56
1004.46
277.60
78.35
98.72
77.56
957.75
1044.11
212.17
83.11
98.99
82.27
/
ꢀ
s
Arad / s-1
Anrad / s-1
φLn / %
φsen / %
φov / %
to the carbazole and
β-diketonate parts of the organic
chromophore. In the case of NBu4[EuL4], the maximum excitation is
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 6 of 11
View Article Online
DOI: 10.1039/C6NJ03450K
ARTICLE
Journal Name
of the remaining transfer rates are assumed to be identical to those
found for coordination compounds, namely
=104 s−1 φ1 =106 s−1
3 =105 s−1 and K1 = K2 = 106 s−1 49
A close analysis shows
that the main channels of energy transfer are T1(π−π*)3 → 5D1 and
φ
,
,
aEstimated uncertainties: ± 5% (Theoretical), ± 12% (τrad
, φLn) and ±
φ2 =108 s−1
,
φ
.
16% (φsen
)
the NBu4[SmL4] emits orange light (CIE = 6.02, 3.81). The emission
spectrum of NBu4[EuL4] composed of five line-like signals derived
7
from the deactivation of 5D0 to F0-4 states of Eu3+. The pure red
light of the NBu4[EuL4] emission is due to the higher 5D0→7F2 /
5D0→7F1 ratio (18.80). Such high value also tells that the central Eu3+
is located in a site without inversion symmetry.45 The emission
4
spectrum of NBu4[SmL4] presents bands corresponding to the G5/2
6
4
6
4
6
→ H3/2 (562 nm), G5/2 → H5/2 (601 nm) and G5/2 → H7/2 (646 nm)
transitions, with the highest
hypersensitive 4G5/2 → 6H7/2 transition.
intensity band being the
The intensity parameters (Ω2-4), radiative (Arad), non-radiative (Anrad
decay rates, intrinsic quantum yield ( Ln), sensitization efficiency
sen) and overall quantum yield ( ov) values were experimentally
calculated for NBu4[EuL4] from its room temperature emission
)
φ
(
φ
φ
Fig. 4 Energy level diagram for NBu4[EuL4] showing the most
probable channels for the intramolecular energy transfer process.
spectrum. The experimental lifetime (τobs) of the NBu4[LnL4] (Ln =
Sm3+, Eu3+) were obtained from the luminescence decay curves (Fig.
T1
exchange mechanism. As it is possible to note in Fig. 4, the channels
( →
π−π*)3 5D0, in other words the process is governed by the
4
S7)† of the emitting G5/2 (Sm3+) and 5D0 (Eu3+) levels. The decay
curves for the NBu4[LnL4] complexes at room temperature were
found to be a single exponential, indicating the existence of only
one site of symmetry around the Ln3+ ions. The obtained values are
presented in Table 3. From Table 3, it is evident that NBu4[EuL4]
shows highly efficient luminescence, which is marked by the long
of energy transfer T1
(
π−π*)3
→
5D1 and T1
(
π−π*)3
→
5D0 are six
5
orders of magnitude higher than the channel S1(π−π*)1 → D4. We
can also observe that the back-transfer rate in the T1 (π−π*)3 → 5D1
channel is high, however due to the similar non-radiative rates K1
and K2 as well as the high energy transfer rate in the T1 (π−π*)3 →
excited state lifetime of 780 ± 6
80 ± 8 %. These values are found to be higher than those obtained
for NBu4[Eu(BTFA)4] (τobs = 730 ± 5 s and
ov = 60 ± 9),6 indicating
ꢀs and high overall quantum yield
5D0 channel, the
φov of the compound is not compromised.
ꢀ
φ
We have then investigated the effect of concentration on
φov and
that the newly developed ligand with carbazole group (HL) can
sensitize Eu3+ in a much better way than BTFA. Furthermore, we
have calculated the above mentioned parameters for NBu4[EuL4] by
using RM1 method. The obtained values are presented in Table 3,
which show excellent agreement with the experimental values. The
experimental lifetime and overall quantum yield values of orange
τobs values of the newly synthesized Sm3+, Eu3+-complexes in thin
films. The films were made by doping 1-10% of (NBu4[LnL4]) (Ln =
Sm3+, Eu3+) in an optically transparent polymeric matrix, PMMA.6
The excitation and emission spectra of (NBu4[LnL4]) (Ln = Sm3+, Eu3+)
complexes in PMMA were similar to that obtained in powder form
(Fig. S8-S9)†. The change in φov was found to be <10% of that
obtained in powder form (Table S1)†, such marginal difference falls
under the range of experimental errors associated with φov
measurements. However, a slight increase in the τobs values are
light emitted by NBu4[SmL4], τobs = 97 ± 2 ꢀs and φov = 10 ± 1 are one
of the highest values reported for similar systems.39, 46-48
noticed, which shows
a decreasing trend with increase in
In order to get a better understanding of the various sensitization
process in the Eu3+-complex, we have modelled the sensitization
process in NBu4[EuL4]. The triplet energy value predicted for the
ground state geometry (20,141 cm-1) shows a good agreement with
experimental value (20,000 cm-1). However, the singlet energy is
overrated for this model. We found a theoretical value of 34,332.60
cm-1 whereas the experimental value is 25,188 cm-1. While the
disagreement is considerable, this fact has no significant impact on
the theoretical study in this work, since the process of energy
transfer in systems is mostly governed by the triplet level. The
energy level diagram with all the probable channels for the
intramolecular energy transfer process is presented in Fig. 4. In Fig.
4, the vertical lines concern the radiative transitions (Arad) and
nonradiative paths (Anrad). The curved lines are related to the ligand
→ Eu3+ energy transfer (green) or back transfer (red). Typical values
concentration of the complexes (Table S1)†. This can be attributed
to the suppression of nonradiative (Ln3+ ↔ Ln3+) energy transfer
due to the larger metal to metal distances in thin films than in
powder. The best PL performances were shown by thin films doped
with 5 weight % of (NBu4[LnL4]) [(Ln = Sm3+
= 11 ± 1), Eu3+(τobs = 796 ± 6
(τobs = 104 ± 1 ꢀs and φov
ꢀ
s and ov = 85 ± 9)]. The experimental
φ
and theoretical PL properties computed for the PMMA film doped
with 5% of (NBu4[EuL4]) is presented in Table 3.
Electroluminescence (EL) Performance of OLEDs
The high PL efficiency of the thin films doped with 5 weight % of the
newly synthesized complexes inspired us to fabricate OLEDs having
general structure ITO/PEDOT:PSS (50 nm)/(NBu4[LnL4]) (5%):CBP
(66.5%)-OXD7(28.5%) (50 nm)/BCP (50nm)/ LiF (1.5 nm)/Al (120
nm), by simple spin coating technique to investigate their
6 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 7 of 11
Journal Name
View Article Online
DOI: 10.1039/C6NJ03450K
ARTICLE
electroluminescence (EL) properties. Here the NBu4[LnL4] range (Fig. 6). Both spectra resemble the PL emission spectra with
complexes (guest) were doped (5%) in to the host matrix, which is a respect to their peak positions and emission colours. The device
blend of CBP (66.5%) and OXD7 (28.5%). The CBP/OXD7 blend is
expected to show balanced electron and hole transport within the
emitting layer, because of the combination of high triplet energy
Fig. 6 Electroluminescence spectra of devices ITO / PEDOT: PSS (50
nm) / NBu4[LnL4] (Ln = Sm3+, Eu3+) (5%): CBP (56%)-OXD7 (24%) (50
nm) / TPBI (50 nm) / LiF(1.5 nm) / Al (120 nm) at 12V; vertical scales
being arbitrary units.
Fig. 5 Energy level diagram of the devices.
on Eu3+ -complex shows pure red emission due to the highly intense
.
5
hypersensitive D0→7F2 transition of Eu3+ ion. On the other hand, its
Sm3+ analogue shows bright orange emission mainly due to the
(2.56 eV) and ambipolar charge transporting abilities of CBP50 with
the electron transporting property of OXD7. Furthermore, the
newly synthesized complexes contain carbazole moieties in the
ligands and hence, a balanceable electron and hole injection and
transport in devises was expected. The HOMOs and LUMOs of the
complexes, which are considered to determine the carrier injection
and transport ability, were investigated by a combination of CV and
UV-vis absorption analyses (Fig. S10)†. The values were found to be
–5.6 eV (HOMO) and -2.5 eV (LUMO). It can be seen from Fig. 5 that
the HOMO level of NBu4[LnL4] falls within that of the CBP host with
5
transitions G5/2→6H5/2-7/2. Figures 7 and 8 show the brightness (L)–
current density (J)–voltage (V) curves of the devices. The turn-on
voltage (V0) of device based on NBu4[EuL4] is 6.7 V and its maximum
brightness of 1234 cd m-2 was achieved at 14.0 V with the current
density of 212 mA cm-2. On the other hand, device with NBu4[SmL4]
had a slightly higher turn-on voltage at 7.6 V and its maximum
brightness of 831 cdm-2 was achieved at 14.9 V with the current
density of 270 mA cm-2. The power (
quantum efficiencies (EQE = ext) of the devices are presented in
ext of 2.3%
ηp), current (ηc) and external
η
a shallow hole trap depth of 0.3 eV, and its LUMO value (2.5 eV) is Table 4. From the Fig. 9, it can be seen that a maximum
η
slightly higher than that of the electron transport layer TPBI. Such a was achieved by the device containing NBu4[EuL4] at a brightness
kind of energy level architecture may facilitate efficient charge value of 28 cd m-2 and it shows impressive values of 1.8% at 100 cd
trapping and recombination within the emitting layer in these m-2 and 0.5% at 1000 cd m-2. These values are better than the
devices.
performances of device based ontris[1(N-ethylcarbazolyl) (3',5'-
hexyloxybenzoyl) methane] (phenanthroline) europium, a complex
The EL spectra of NBu4[LnL4] (Ln= Sm3+
,
Eu3+) show only
characteristic emission from the Ln3+ ions in the entire voltage
curves (a) of the device based on ITO/PEDOT: PSS (50
nm)/NBu4[EuL4] (5%): CBP(66.5%)-OXD7(28.5%)(50 nm)/ TPBI (50
nm)/LiF(1.5 nm)/Al (120 nm).
Fig. 7 Voltage (V) – brightness (L) – current density (J) curves and
Current density (J) – current efficiency (ηc) – power efficiency (ηp)
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 8 of 11
View Article Online
DOI: 10.1039/C6NJ03450K
ARTICLE
Journal Name
Fig. 8 Voltage (V) – brightness (L) – current density (J) curves and
current density (J) – current efficiency ( c) – power efficiency (ηp
η
)
curves (a) of the device based on ITO/PEDOT: PSS (50
nm)/NBu4[SmL4] (5%): CBP(66.5%)-OXD7(28.5%)(50 nm)/ TPBI (50
nm)/LiF(1.5 nm)/Al (120 nm).
Table 4. EL characteristics of OLEDs with Ln -
3+ β-diketonate complexes.a
Complex
Von
V
/
L /
cd m-2
ηc/
ηp/
LmW-1
ηext /%
L= 100
1.8
0.7
—
cd A-1
3.5 (9.1V)
1.4 (9.2V)
0.18
Max (L)
2.3 (28)
1.1(10)
—
1000
0.5
—
NBu4[EuL4]
6.7
7.6
—
6
1234 (14.0V)
831 (14.9V)
43 (14V)
474(18V)
118 (13.6)
490 (15V)
135 (10V)
81
1.3 (9.1V)
NBu4[SmL4]
Sm(HFNH)3X5
Sm(HFNH)3X51
Sm(HFNH)3X51
Sm(DBM)3Z52
Sm(BTFA)3X53
Sm(TTA)3X54
0.5 (9.2V)
—
—
0.96
0.5
—
—
—
10
3.0
—
—
15
—
9
0.029
—
—
—
—
—
—
0.6
—
—
—
—
—
—
—
0.04 (12.3V)
—
—
—
—
—
55
Sm(TTA)3Y2
0.5 (23V)
135
—
—
—
—
56
Sm(HFAC)3X2
0.1
—
—
—
—
Sm(THFP)3X57
21(21V)
0.114
—
—
—
—
a
HFNH
=
4,4,5,5,6,6,6-heptafluoro-1-(2-naphthyl)hexane-1,3-dione, DBM
=
dibenzoylmethane, BTFA = benzoyltrifluoroacetone, TTA = 2-
thenoyltrifluoroacetone, HFAC = hexafluoroacetylacetone, THFP = 4,4,5,5,6,6,6-heptafluoro-1-(2-thenoyl)hexane-1,3-dione, X = 1,10-phenanthroline, Y =
triphenylphosphinoxide, Z = 4,7=diphenyl-1,10-phenanthroline.
having β-diketone directly connected to carbazole ring as emitting
material [V0 = 8.7 V; L = 50 cd m-2 (15 mA cm-2); ηext = 0.3%].25
However, the performance of device based on NBu4[EuL4] in this
study is still unsatisfactory when compared with many reported EL
devices containing Eu3+-compounds as emitters.58 It is well known
that the device efficiency drops rapidly with an increase in the
current density in Eu3+-based OLEDs. Detailed research suggests
that one of the main reasons for this efficiency roll-off is the
emitter’s luminescence lifetime being too long.59 Thus it is
reasonable to assume that the best EL results obtained for
NBu4[SmL4] in this study (
m-2) in spite of its low PL efficiencies is due to its relatively low
excited state lifetime (97± 2 s).
s) than its Eu3+counterpart (780± 6
η
ext = 1.1% at 10 cdm-2 and 0.7 % at 100 cd
ꢀ
ꢀ
Fig. 9 Brightness (L) – external quantum efficiency (
the devices based on ITO/PEDOT: PSS (50 nm)/NBu4[LnL4] (Ln =
Sm3+ Eu3+) (5%): CBP(66.5%)-OXD7(28.5%)(50 nm)/ TPBI (50
ηext) curves of
To the best of our knowledge, this is the highest EL performance of
devices based on Sm3+ complexes reported so far in literatures as
shown in Table 4.
,
nm)/LiF(1.5 nm)/Al (120 nm).
Conclusions
In summary, we have showed that by well-planned designing of
lanthanide complexes, visible light sensitization and balanced
carrier injection properties can be achieved. The newly designed
Ln3+-complexes with carbazole-containing ligand show very high
photoluminescence efficiencies. PL results showed that there is +15%
8 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 9 of 11
View Article Online
DOI: 10.1039/C6NJ03450K
Journal Name
ARTICLE
14.
15.
16.
17.
18.
Z. Chen, F. Ding, F. Hao, M. Guan, Z. Bian, B. Ding and
C. Huang, New J. Chem., 2010, 34, 487-494.
M. Guan, Z. Qiang Bian, F. You Li, H. Xin and C. Hui
Huang, New J. Chem., 2003, 27, 1731-1734.
F. Liang, Q. Zhou, Y. Cheng, L. Wang, D. Ma, X. Jing
and F. Wang, Chem. Mater., 2003, 15, 1935-1937.
M. Sun, H. Xin, K.-Z. Wang, Y.-A. Zhang, L.-P. Jin and
C.-H. Huang, Chem. Commun., 2003, 702-703.
J. Wang, R. Wang, J. Yang, Z. Zheng, M. D. Carducci, T.
Cayou, N. Peyghambarian and G. E. Jabbour, J. Am.
Chem. Soc., 2001, 123, 6179-6180.
increases in sensitization efficiency (φsen) for the new ligand
compared to BTFA towards Eu3+, mainly because of the perfect
match of the excited energy levels and the compact structure of the
complex with improved intramolecular energy-transfer efficiency.
Further, the modification made in the ligand BTFA, increases the
volumes of the complexes, which reduces the intermolecular
interaction and results in the amorphous phase and the
extraordinarily low self-quenching of the luminescence. This is
reflected in the excellent electroluminescence performances of
devices fabricated using the newly synthesized complexes. As far as
our knowledge is concerned, the PL and EL performances of the
Sm3+ complex described here are the best reported so far in
literatures among similar systems.
19.
20.
21.
22.
J. V. Grazulevicius, P. Strohriegl, J. Pielichowski and K.
Pielichowski, Prog. Polym. Sci., 2003, 28, 1297-1353.
J. Li and A. C. Grimsdale, Chem. Soc. Rev., 2010, 39
2399-2410.
,
J.-F. Morin, M. Leclerc, D. Adès and A. Siove,
Macromol. Rapid Commun., 2005, 26, 761-778.
D. Nie, Z. Chen, Z. Bian, J. Zhou, Z. Liu, F. Chen, Y.
Zhao and C. Huang, New J. Chem., 2007, 31, 1639-
1646.
Y. Zheng, F. Cardinali, N. Armaroli and G. Accorsi, Eur.
J. Inorg. Chem., 2008, 2008, 2075-2080.
P. He, H. H. Wang, S. G. Liu, J. X. Shi, G. Wang and M.
L. Gong, Inorg. Chem., 2009, 48, 11382-11387.
M. R. Robinson, M. B. O'Regan and G. C. Bazan, Chem.
Commun., 2000, 1645-1646.
S. Biju, L.-J. Xu, C.-Z. Sun and Z.-N. Chen, J. Mater.
Chem. C, 2015, 3, 5775-5782.
S. Li, G. Zhong, W. Zhu, F. Li, J. Pan, W. Huang and H.
Tian, J. Mater. Chem., 2005, 15, 3221-3228.
F.-F. Chen, Z.-Q. Bian, Z.-W. Liu, D.-B. Nie, Z.-Q. Chen
and C.-H. Huang, Inorg. Chem., 2008, 47, 2507-2513.
J. Li, J.-Y. Wang and Z.-N. Chen, J. Mater. Chem. C,
2013, 1, 3661-3668.
V. Divya, R. O. Freire and M. L. P. Reddy, Dalton
Trans., 2011, 40, 3257-3268.
Acknowledgements
This research was supported by the NSFC (21390392, 21473201,
U1405252 and 21531008), the 973 project (2014CB845603) from
MSTC, the CAS/SAFEA International Partnership Program for
Creative Research Teams and the Strategic Priority Research
Program of the Chinese Academy of Sciences (XDB20000000). S. B.
acknowledges the Collegiate Education Dept., Dept. of Higher
Education Govt. of Kerala, (India) for granting leave without salary
for doing postdoctoral research. The Brazilian authors appreciate
the financial support from the Brazilian agencies and foundations
(CNPq, CAPES, FACEPE/PRONEX and FAPITEC-SE).
23.
24.
25.
26.
27.
28.
29.
30.
Notes and References
1.
S. V. Eliseeva and J.-C. G. Bünzli, Chem. Soc. Rev.,
2010, 39, 189-227.
31.
32.
M. D. Ward, Coord. Chem. Rev., 2007, 251, 1663-1677.
V. Divya and M. L. P. Reddy, J. Mater. Chem. C, 2013,
2.
3.
A. de Bettencourt-Dias, Dalton Trans., 2007, 2229-
2241.
M. A. Katkova and M. N. Bochkarev, Dalton Trans.,
2010, 39, 6599-6612.
1
, 160-170.
B. Francis, C. Heering, R. O. Freire, M. L. P. Reddy and
C. Janiak, RSC Adv., 2015, , 90720-90730.
33.
34.
5
4.
5.
K. Binnemans, Chem. Rev., 2009, 109, 4283-4374.
J. Yu, L. Zhou, H. Zhang, Y. Zheng, H. Li, R. Deng, Z.
Peng and Z. Li, Inorg. Chem., 2005, 44, 1611-1618.
S. Biju, R. O. Freire, Y. K. Eom, R. Scopelliti, J.-C. G.
Bünzli and H. K. Kim, Inorg. Chem., 2014, 53, 8407-
8417.
S. Comby and J.-C. G. Bünzli, in Handbook on the
Physics and Chemistry of Rare Earths, ed. J-C. G.
Bünzli, K. A. Gschneidner Jr, V. K. Pecharsky, Elsevier,
2007, pp. 217-470
M. A. M. Filho, J. D. L. Dutra, H. L. B. Cavalcanti, G. B.
Rocha, A. M. Simas and R. O. Freire, J. Chem. Theory
Comput., 2014, 10, 3031-3037.
B. R. Judd, Phys. Rev., 1962, 127, 750-761.
G. S. Ofelt, J. Chem. Phys., 1962, 37, 511-520.
J. D. L. Dutra, T. D. Bispo and R. O. Freire, J. Comput.
Chem., 2014, 35, 772-775.
S. Biju, Y. K. Eom, J.-C. G. Bünzli and H. K. Kim, J.
Mater. Chem. C, 2013, 1, 6935-6944.
6.
35.
7.
8.
D. B. A. Raj, S. Biju and M. L. P. Reddy, Inorg. Chem.,
2008, 47, 8091-8100.
D. B. A. Raj, B. Francis, M. L. P. Reddy, R. R. Butorac, V.
36.
37.
38.
M. Lynch and A. H. Cowley, Inorg. Chem., 2010, 49
9055-9063.
,
9.
C. Adachi, M. A. Baldo and S. R. Forrest, J. Appl. Phys.,
2000, 87, 8049-8055.
39.
40.
41.
42.
10.
11.
P.-P. Sun, J.-P. Duan, H.-T. Shih and C.-H. Cheng, Appl.
Phys. Lett., 2002, 81, 792-794.
M. D. McGehee, T. Bergstedt, C. Zhang, A. P. Saab, M.
B. O'Regan, G. C. Bazan, V. I. Srdanov and A. J. Heeger,
Adv. Mater., 1999, 11, 1349-1354.
Q. Zhang, P. Jiang, K. Wang, G. Song and H. Zhu, Dyes
Pigm., 2011, 91, 89-97.
J. D. L. Dutra, N. B. D. Lima, R. O. Freire and A. M.
Simas, Sci. Rep., 2015, 5, 13695.
J. D. L. Dutra, M. A. M. Filho, G. B. Rocha, R. O. Freire,
12.
13.
P. P. Sun, J. P. Duan, J. J. Lih and C. H. Cheng, Adv.
Funct. Mater. , 2003, 13, 683-691.
Y. Zhang, C. Li, H. Shi, B. Du, W. Yang and Y. Cao, New
J. Chem., 2007, 31, 569-574.
A. M. Simas and J. J. P. Stewart, J. Chem. Theory
Comput., 2013, 9, 3333-3341.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 9
Please do not adjust margins

Please do not adjust margins
New Journal of Chemistry
Page 10 of 11
View Article Online
DOI: 10.1039/C6NJ03450K
ARTICLE
Journal Name
43.
S. M. Bruno, R. A. S. Ferreira, F. A. Almeida Paz, L. D.
Carlos, M. Pillinger, P. Ribeiro-Claro and I. S.
Gonçalves, Inorg. Chem., 2009, 48, 4882-4895.
Q. Ma, Y. Zheng, N. Armaroli, M. Bolognesi and G.
Accorsi, Inorg. Chim. Acta, 2009, 362, 3181-3186.
P. A. Tanner, Chem. Soc. Rev., 2013, 42, 5090-5101.
S. Biju, D. B. Ambili Raj, M. L. P. Reddy, C. K.
Jayasankar, A. H. Cowley and M. Findlater, J. Mater.
Chem., 2009, 19, 1425-1432.
44.
45.
46.
47.
Y. Kuramochi, T. Nakagawa, T. Yokoo, J. Yuasa, T.
Kawai and Y. Hasegawa, Dalton Trans., 2012, 41,
6634-6640.
48.
49.
50.
Y. Hasegawa, S.-i. Tsuruoka, T. Yoshida, H. Kawai and
T. Kawai, J. Phys. Chem. A, 2008, 112, 803-807.
O. L. Malta, F. R. Gonçalves e Silva and R. Longo,
Chem. Phys. Lett., 1999, 307, 518-526.
V. Adamovich, J. Brooks, A. Tamayo, A. M. Alexander,
P. I. Djurovich, B. W. D'Andrade, C. Adachi, S. R.
Forrest and M. E. Thompson, New J. Chem., 2002, 26
1171-1178.
,
51.
52.
J. Yu, H. Zhang, L. Zhou, R. Deng, Z. Peng, Z. Li, L. Fu
and Z. Guo, J. Lumin., 2007, 122–123, 678-682.
B. Chu, W. L. Li, Z. R. Hong, F. X. Zang, H. Z. Wei, D. Y.
Wang, M. T. Li, C. S. Lee and S. T. Lee, J. Phys. D: Appl.
Phys., 2006, 39, 4549-4552.
53.
54.
55.
E. Stathatos, P. Lianos, E. Evgeniou and A. D.
Keramidas, Synth. Met., 2003, 139, 433-437.
R. Deng, J. Yu, H. Zhang, L. Zhou, Z. Peng, Z. Li and Z.
Guo, Chem. Phys. Lett., 2007, 443, 258-263.
R. Reyes, E. N. Hering, M. Cremona, C. F. B. da Silva, H.
F. Brito and C. A. Achete, Thin Solid Films, 2002, 420–
421, 23-29.
56.
57.
58.
59.
Z. Kin, H. Kajii, Y. Hasegawa, T. Kawai and Y. Ohmori,
Thin Solid Films, 2008, 516, 2735-2738.
Y. Zheng, L. Fu, Y. Zhou, J. Yu, Y. Yu, S. Wang and H.
Zhang, J. Mater. Chem., 2002, 12, 919-923.
H. Xu, Q. Sun, Z. An, Y. Wei and X. Liu, Coord. Chem.
Rev., 2015, 293–294, 228-249.
L. Zhang, B. Li, L. Zhang and Z. Su, ACS Appl. Mater.
Interfaces, 2009, 1, 1852-1855.
10 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 11 of 11
New Journal of Chemistry
View Article Online
DOI: 10.1039/C6NJ03450K
TOC Entry
Bright Orange and Red Light-emitting Diodes of New Visible Light Excitable
Tetrakis-Ln-
-Diketonate (Ln = Sm3+, Eu3+) Complexes
β
A new β
-diketonate ligand and its visible light excitable Sm3+, Eu3+ -complexes were designed
and synthesized, which showed highly efficient photoluminescence and electroluminescence
properties.