Synthesis, characterization and luminescence properties of LnIII (Ln = Eu, Tb, Ce, Sm, Dy) complexes containing a terpyridine ligand and a 3d-4f type conjugated terpyridine-alkyne bridging EuIII-Co0 carbonyl cluster complex

Article abstract of DOI:10.1016/j.poly.2014.02.044

Seven new organic trivalent lanthanide complexes containing a terpyridine or terpyridine-alkyne ligand, [Ln(L1)(CH₃OH)(NO₃) ₃] (Ln = Eu 1, Tb 2, Ce 3, Sm 4, Dy 5; L1 = 4-(4-bromophenyl)-2, 2′:6′,2″-terpyridine) and [Ln(L2)(NO₃)₃] (Ln = Eu 6, Tb 7; L2 = 4-(4-trimethylsilyl phenylacetylene)-2,2′: 6′,2″-terpyridine), were synthesized by the reaction of Ln(NO ₃)₃·6H₂O (Ln = Eu, Tb, Ce, Sm, Dy) with L1 and L2, respectively. In addition, a new 3d-4f type conjugated Eu ^III-Co⁰ carbonyl cluster complex, [(NO₃) ₃Eu(η³-L2-μ)(Co₂(CO)₆)] 8, was obtained by the reaction of complex 6 with Co₂(CO)₈ in THF. All of these complexes were characterized and X-ray single-crystal diffraction reveals that the Ce^III ion is ten-coordinated and lies approximately in the center of a polyhedron with 16 faces in the structure of complex 3. The molecular conformation is stabilized by intra- and intermolecular hydrogen bonds, and intermolecular π-Br and π-π interactions. The luminescence properties of these complexes were also investigated in the solid state.

Full text of DOI:10.1016/j.poly.2014.02.044

Polyhedron 74 (2014) 67–71
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Synthesis, characterization and luminescence properties
of LnIII (Ln = Eu, Tb, Ce, Sm, Dy) complexes containing a terpyridine
ligand and a 3d–4f type conjugated terpyridine-alkyne bridging
EuIII–Co0 carbonyl cluster complex
⇑
Bao-Hua Zhu , Yan-Hong Liu, Xue-Yan Jin, Hai-Ying Xu, Ya-Ya Han, Qi Zhao
Chemistry and Chemical Engineering College, Inner Mongolia University, Hohhot 010021, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Seven new organic trivalent lanthanide complexes containing a terpyridine or terpyridine-alkyne ligand,
[Ln(L1)(CH3OH)(NO3)3] (Ln = Eu 1, Tb 2, Ce 3, Sm 4, Dy 5; L1 = 4-(4-bromophenyl)-2,20:60,200-terpyridine)
and [Ln(L2)(NO3)3] (Ln = Eu 6, Tb 7; L2 = 4-(4-trimethylsilyl phenylacetylene)-2,20:60,200-terpyridine),
were synthesized by the reaction of Ln(NO3)3ꢀ6H2O (Ln = Eu, Tb, Ce, Sm, Dy) with L1 and L2, respectively.
Received 18 November 2013
Accepted 17 February 2014
Available online 12 March 2014
In addition, a new 3d–4f type conjugated EuIII–Co0 carbonyl cluster complex, [(NO3)3Eu( 3-L2-
g l)
Keywords:
Lanthanide
Terpyridine derivate
Crystal structure
Cobalt carbonyl cluster
Luminescence
(Co2(CO)6)] 8, was obtained by the reaction of complex 6 with Co2(CO)8 in THF. All of these complexes
were characterized and X-ray single-crystal diffraction reveals that the CeIII ion is ten-coordinated and
lies approximately in the center of a polyhedron with 16 faces in the structure of complex 3. The molec-
ular conformation is stabilized by intra- and intermolecular hydrogen bonds, and intermolecular
and interactions. The luminescence properties of these complexes were also investigated in the solid
state.
p–Br
p–p
Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction
anti-inflammatory and antiapoptotic properties and toxicity
against tumour cells as carbon monoxide releasing molecules
[16–18], which might be applied in the area of medicine in the
future.
The chemistry of organic lanthanide complexes has developed
rapidly and extensively in recent years because of their application
in fluorescent displays, phosphorescence devices, lasers, electrolu-
minescence optical devices, probes for chemical and biological
molecules and for the study of drugs with regard to activities, reac-
tions and dynamics, with this being derived from their high
fluorescent efficiency, narrow band f ? f emissions and excellent
monochromatocity [1–5]. However, as is known, the luminescent
f–f transitions of lanthanide ions are difficult to generate by direct
excitation, and a sensitization process is needed to transfer energy
into the LnIII ions. Terpyridine is one of the promising ligands for
efficient energy transfer to sensitize the emissive states of lantha-
nide ions. Recently, many terpyridine derivative coordinated lan-
thanide luminescent complexes have been reported and they
have exhibited good luminescence properties [6–13].
Based on the current interest in lanthanide luminescent com-
plexes and metal carbonyl CORMs, we are interested in the synthesis
of lanthanide luminescent unit conjugated alkyne-bridging cobalt
carbonyl cluster complexes to construct a new type of bifunctional
molecule, i.e., possessing fluorescence probe functional carbon
monoxide releasing molecules, for the study of drugs. In this paper,
we report the synthesis, characterization and luminescence proper-
ties of seven new organic lanthanide complexes containing terpyri-
dine or terpyridine-alkyne ligands, [Ln(L1)(CH3OH)(NO3)3] (Ln = Eu
1, Tb 2, Ce 3, Sm 4, Dy 5) and [Ln(L2)(NO3)3] (Ln = Eu 6, Tb 7), and one
new 3d–4f type conjugated terpyridine-alkyne bridging EuIII–Co0
carbonyl cluster complex, [(NO3)3Eu(g l) (Co2(CO)6)] 8.
3-L2-
On the other hand, a number of metal carbonyl complexes have
been designed as prodrugs to release CO in vivo, which are known
as CO-releasing molecules (CORMs) [14,15]. Some alkyne-bridging
cobalt carbonyl complexes are reported to exhibit powerful
2. Experimental
2.1. General
Thin-layer chromatography (TLC) was conducted on silica gel
60 F254 plates (Merck KGaA). 1H NMR spectra were recorded on
a Bruker Avance 400 (400 MHz) spectrometer, using CDCl3 as the
⇑
Corresponding author. Tel.: +86 4714993403.
E-mail address: bhzhu@imu.edu.cn (B.-H. Zhu).
http://dx.doi.org/10.1016/j.poly.2014.02.044
0277-5387/Ó 2014 Elsevier Ltd. All rights reserved.

68
B.-H. Zhu et al. / Polyhedron 74 (2014) 67–71
solvent and tetramethylsilane (TMS) as an internal standard. Melt-
ing points were determined on an XD-4 digital micro melting point
apparatus. Infrared spectra were recorded on a Nicolet Nexus 670
2.05; N, 11.12%. IR (KBr pellets, cmꢁ1): 1610m, 1545w, 1482vs,
1425m, 1386s, 1291m, 793m, 740m.
FT-IR spectrometer as KBr pellets in the range 4000–400 cmꢁ1
.
2.2.3. [Eu(L2)(NO3)3] 6
Luminescence and luminescence lifetime measurements were re-
corded on an Edinburgh FLS920 luminescence spectrophotometer
at the room temperature. Elemental analyses (C, H and N) were
performed with a Perkin-–Elmer 2400 type elemental analyzer.
MS positive ions spectra were obtained on an Agilent 1100
LC–MSD-Trap-XCT instrument.
Complex 6 was prepared as described for 1, except that 4-(4-tri-
methylsilyl phenylacetylene)-2,20:60,200-terpyridine (L2) was used
instead of L1. Yield: 78%. Anal. Calc. for C26H23EuN6O9Si: C, 41.93;
H, 3.12; N, 11.29; Found: C, 42.10; H, 3.08; N, 11.26%. IR (KBr pel-
lets, cmꢁ1): 2158w, 1613m, 1540s, 1483vs, 1424m, 1383vs, 1293s.
All chemicals were of reagent grade and used without further
purification. The lanthanide nitrate salts were prepared via dissolv-
ing lanthanide oxides with 6 M HNO3 whilst adding some H2O2 and
then evaporating at 100 °C until a crystal film formed. The terpyr-
idine ligands 4-(4-bromophenyl)-2,20:60,200-terpyridine (L1) and
4-(4-trimethylsilylphenyl acetylene)-2,20:60,200-terpyridine (L2)
were synthesized and characterized according to the literature
methods [19–21].
2.2.4. [Tb(L2)(NO3)3] 7
The preparation of 7 is similar to that for 6, except that
Tb(NO3)3ꢀ6H2O was used instead of Eu(NO3)3ꢀ6H2O. Yield: 76%.
Anal. Calc. For C26H23N6O9SiTb: C, 41.60; H, 3.09; N, 11.20; Found:
C, 41.02; H, 3.33; N, 10.99%. IR (KBr pellets, cmꢁ1): 2158w, 1614m,
1546m, 1483vs, 1422m, 1380vs, 1284s.
2.2.5. [(NO3)3Eu( 3-L2- )(Co2(CO)6)] 8
g
l
L1: m.p.164–166 °C. IR (KBr disc, cmꢁ1): 3052m, 1584s, 1563m,
1467m, 1406m, 1381m, 740m. 1H NMR (CDCl3) d: 7.35 ꢂ 7.38
(m, 2H), 7.63 (d, J = 8.5 Hz, 2H), 7.77 (d, J = 8.5 Hz, 2H),
7.83 ꢂ 7.90 (m, 2H), 8.66 (d, J = 8.0 Hz, 2H), 8.70 (s, 2H), 8.72
(d, J = 5.0 Hz, 2H); 13C NMR (CDCl3) d: 118.8, 121.6, 123.6, 124.1,
129.0, 132.3, 137.1, 137.6, 149.2, 156.2.
To a solution of 6 (300 mg, 0.4 mmol) in 20 ml of CH2Cl2/DMF at
room temperature was added dropwise a solution of Co2(CO)8
(150 mg, 0.44 mmol) in 10 ml of CH2Cl2 under argon. The mixture
was stirred at room temperature for 8 h and monitoring by TLC
showed the disappearance of the starting material. After the sol-
vent was removed, the residue was extracted with a small amount
of CH2Cl2/CH3OH (3:1) and transferred to an Al2O3 chromatogra-
phy column. Elution with CH2Cl2/CH3OH (5:1) afforded the red
band and other unidentified compounds. Condensing the red band
and crystallization at ꢁ20 °C gave red crystals of 8 (100 mg, 22%
yield). Anal. Calc. For C32H23Co2EuN6O15Si: C, 37.29; H, 2.25; N,
8.16; Found: C, 37.02; H, 2.33; N, 8.69%. IR (KBr disc, cmꢁ1):
2091m, 2055m, 2020m, 1545w, 1471w, 1398s, 1248m. ESI-MS
m/z: 945.9, M+ – 3CO; 690.25 M+ – Eu(NO3)3; 578.98 M+ – Eu(NO3)3
– 4CO complex fragmentation.
L2: m.p. 163–164 °C; IR (KBr disc, cmꢁ1): 2959m, 2156m,
1607m, 1585s, 1563s, 1543m, 1467m, 1383m, 1255m, 1116m,
861s. 1H NMR (CDCl3, 500 MHz) d: 8.74 (s, 2H), 8.74 (dd, J = 4.9,
1.0 Hz, 2H), 8.68 (d, 2H, J = 7.8 Hz), 7.90 (td, 2H, J = 7.8, 1.5 Hz),
7.87–7.61 (ABq, 4H, JAB = 8.5 Hz, C6H4), 7.37 (td, 2H, J = 6.4,
1.5 Hz), 0.29 (s, 9H, TMS). 13C NMR (CDCl3, 500 MHz) d: 156.2,
156.1, 149.5, 149.2, 138.5, 137.0, 132.8, 127.2, 124.0, 123.6,
121.5, 118.9, 104.9, 95.9.
2.2. Syntheses of the lanthanide complexes
2.3. X-ray crystallography
2.2.1. [Eu(L1)(CH3OH)(NO3)3] 1
To a solution of 4-(4-bromophenyl)-2,20:60,200-terpyridine (L1)
(1.1 g, 2.83 mmol) in 20 ml of THF at room temperature was added
dropwise a solution of Eu(NO3)3ꢀ6H2O (1.52 g, 3.4 mmol) in 10 ml
of THF and MeOH. The mixture was stirred for 3 h and white pre-
cipitation was obtained by adding 10 ml Et2O and 50 ml n-hexane.
After filtering, the precipitate was washed twice with a small
amount of THF, then recrystallized from a mixed solution of CH2Cl2
and methanol to give white crystals of 1 in 82% yield (1.68 g). Anal.
Calc. for C22H18BrEuN6O10: C, 34.83; H, 2.39; N, 11.08; Found: C,
35.13; H, 2.38; N, 11.15%. IR (KBr pellets, cmꢁ1): 1610m, 1545w,
1485vs, 1424m, 1385s, 1311s, 794m, 739m.
Yellow single crystals of cluster 3 suitable for single crystal
X-ray analysis were obtained from a CH2Cl2/CH3OH mixed solution
at room temperature. The structure of cluster 3 was determined by
the single-crystal X-ray diffraction technique. A suitable crystal
was mounted on the tip of glass fiber with perfluoropolyether
oil. Data were collected at 296 K on a Bruker APEX-II CCD diffrac-
tometer equipped with graphite monochromatic Mo
Ka
(k = 0.71073 Å) radiation. The structure was solved by direct meth-
ods (SHELXS-97) [22] and expanded using Fourier techniques and all
non-hydrogen atoms were refined anisotropically by full-matrix
least-squares on F2 using the SHELXL-97 [23] crystallographic pro-
gram package. Hydrogen atoms were added according to geomet-
rical methods. Further details of the data determination, crystal
data and structure refinement parameters are summarized in
Table 1.
2.2.2. Complexes 2–5
Complexes 2–5 were obtained according to a procedure similar
to that for complex 1.
[Tb(L1)(CH3OH)(NO3)3] 2, 80% yield. Anal. Calc. For
C
22H18BrTbN6O10: C, 34.56; H, 2.37; N, 11.00; Found: C, 34.87; H,
3. Results and discussion
1.98; N, 11.38%. IR (KBr pellets, cmꢁ1): 1614m, 1547w, 1484vs,
1425m, 1384s, 1317m, 794m, 740m.
3.1. Synthesis and characterization
[Ce(L1)(CH3OH)(NO3)3] 3, 85% yield. Anal. Calc. For
C
22H18BrCeN6O10: C, 35.44; H, 2.44; N, 11.28; Found: C, 35.27; H,
The syntheses of 1–8 are outlined in Scheme 1. The proposed
structures were confirmed by elemental analysis, IR spectra and
X-ray single crystal diffraction.
2.08; N, 11.15%. IR (KBr pellets, cmꢁ1): 1612m, 1541w, 1481vs,
1422m, 1383s, 1307m, 792m, 741m.
[Sm(L1)(CH3OH)(NO3)3] 4, 76% yield. Anal. Calc. For
The IR spectra of complexes 1–8 show absorption bands in the
range 1248–1614 cmꢁ1, characteristic of the pyridine rings. For
complexes 6 and 7, besides the pyridine ring absorption bands,
there is an absorption band at 2158 cmꢁ1, which is caused by the
C„C vibration. It should be noted that in the IR spectrum of 8,
the absorption bands of terminal carbonyl ligands attached to the
C
22H18BrSmN6O10: C, 34.88; H, 2.40; N, 11.10; Found: C, 34.45;
H, 1.90; N, 11.47%. IR (KBr pellets, cmꢁ1): 1608m, 1544w,
1485vs, 1424m, 1386s, 1288s, 794m, 739m.
[Dy(L1)(CH3OH)(NO3)3] 5, 72% yield. Anal. Calc. For
22H18BrDyN6O10: C, 34.37; H, 2.36; N, 10.93; Found: C, 33.75; H,
C

B.-H. Zhu et al. / Polyhedron 74 (2014) 67–71
69
Table 1
[C6H4(COOCH2CCH-
l
)2] [Co2(CO)6]2 [25]. All of these bands are
Crystallographic data for complex 3.
consistent with the structures of the compounds containing ter-
pyridine, 1-alkyne and carbonyl ligands [8,13,16,17,24–30]. The
most important IR assignments in the spectra of the ligands L1,
L2 and the complexes 1–8 can be seen in Table S1 of the supporting
information.
Empirical formula
Formula weight
T (K)
Wavelength (Å)
Crystal system
Space group
a (Å)
C22H18BrCeN6O10
746.45
296(2)
0.71073
monoclinic
P2(1)/c
10.7622(5)
25.8198(13)
3.2. X-ray single crystal diffraction
b (Å)
c (Å)
10.9484(6)
The molecular structure of 3 was determined by single crystal
X-ray analysis. The structure, with the numbering, is shown in
Fig. 1. As can be seen in Fig. 1 and Fig. 2, the ten-coordinated CeIII
ion approximately lies in the center of a polyhedron with 16 faces
defined by the nitrogen atoms of the tridentate L1 unit, six oxygen
atoms of three bidentate nitrates and one oxygen atom of the
methanol ligand. The Ce–N and Ce–O average distances are 2.626
and 2.585 Å, respectively. The terpyridine moiety displays an al-
most planar arrangement, the interplanar angles between the cen-
tral and the two terminal pyridines are 5.7(2)° and 19.0(2)°,
respectively. In the crystal structure, weak intra- and intermolecu-
lar interactions are observed: (1) intramolecular hydrogen bond
between terpyridine C15 and O10 of the methanol ligand
(Hꢀ ꢀ ꢀO = 2.498 Å; C–Hꢀ ꢀ ꢀO = 131.3(5)°); (2) intermolecular hydro-
gen bonding between the CH bonds of terminal two pyridines
and the oxygen atoms of the nitrates of two adjacent molecules
(Hꢀ ꢀ ꢀO bond; min = 2.503(5) Å, max = 2.677(6) Å; C–Hꢀ ꢀ ꢀO angle;
min = 140.4(4)°, max = 162.9(3)°) (see Supporting information,
a
b (°)
(°)
90
116.2790(10)
90
2727.9(2)
4
1.818
3.198
1460
c
(°)
V (Å3)
Z
Dcalc (Mg/m3)
Absorption coefficient (mmꢁ1
F(000)
)
Crystal size (mm)
h Range for data collection
Index ranges
0.2 ꢃ 0.2 ꢃ 0.2
1.58–28.27
ꢁ14 6 h 6 14, ꢁ27 6 k 6 34, ꢁ14 6 l 6 14
Reflections collected
19 817
Independent reflections (Rint
Completeness to h = 28.27
Absorption correction
)
6762 (0.0573)
99.8%
none
Refinement method
full-matrix least-squares on F2
6762/0/364
Data/restraints/parameters
Goodness-of-fit on F2
1.027
Final R indices [I > 2
R indices (all data)
Extinction coefficient
r(I)]
R1 = 0.0475, wR2 = 0.1261
R1 = 0.0951, wR2 = 0.1455
0.0006(2)
Fig. S1 and Table S2); (3) intermolecular p–p interactions between
Co atom can be observed at 2091–2020 cmꢁ1, which is similar to
that of the reported 1-alkyne bridging cobalt carbonyl clusters
the pyridine-rings and bromophenyl-ring of two adjacent mole-
cules (the shortest distance between the aromatic-ring atoms is
3.519 Å); (4) weak intermolecular Brꢀ ꢀ ꢀH–C interactions between
[(CH2)n(COOCH2CCH-l)2][Co2(CO)6]2 (n = 3 and 8) [24] and
O
N
O
N
N
N
O
THF
O
Br
O
N
Ln(NO3)3.xH2O
Ln
O
N
N
Br
+
O
O
MeOH
N
CH3
O
H
L1
N
O
Ln=Eu 1; Tb 2; Ce 3; Sm 4; Dy 5.
N
N
O
(CH )
C-Si
C
N
3 3
N
O
O
N
N
CH Cl /THF
L2
2
2
O
O
+
(CH )
Ln
C-Si
O
N
O
N
C
3 3
O
N
O
Ln(NO ) .xH O
3 3
2
Ln=Eu 6;Tb 7.
O
N
O
O
Eu
O
N
N
O
C-Si(CH3)3
O N
C
N
O
O
O
N
6
N
O
Eu
O
O
N
N
O
CH2Cl2/DMF
O
+
O N
N
C
C-Si(CH3)3
(CO)
O
O
N
Co
(CO)3
Co
Co2(CO)8
3
O
8
Scheme 1. Synthesis of complexes 1–8.

70
B.-H. Zhu et al. / Polyhedron 74 (2014) 67–71
70000
60000
50000
40000
C14
N1
C13
C15
H5
C12
C11
C9
C22
O2
O10
O3
C10
N4
C20
C19
C21
C16
O7
30000
20000
10000
0
N3
Br
Ce
O5
O4
H1
C8
N6
O9
O1
N5
C18
C7
C17
C6
O8
O6
C5
C4
N2
C1
550
600
Wavelength (nm)
650
700
C3
C2
Fig. 1. Molecular structure of complex 3.
Fig. 3. The emission spectra (kex = 364 nm) of complexes 1 and 6.
5D0ė7F2
2000
1800
1600
1400
1200
1000
800
5D0ė7F1
600
400
200
0
550
570
590
610
630
650
Wavelength (nm)
Fig. 4. The emission spectrum (kex = 327 nm) of the cluster complex 8.
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
Fig. 2. Perspective view for the coordination geometry of the CeIII ion in complex 3.
aromatic Br atoms and hydrogen atoms of terminal pyridines of
adjacent molecules (Brꢀ ꢀ ꢀC 3.921 Å, Brꢀ ꢀ ꢀH 3.071 Å) and two ꢀ ꢀ ꢀBr
p
interactions (Br(1A)ꢀ ꢀ ꢀC(9A) 3.433 Å, Br(1B)ꢀ ꢀ ꢀC(3B) 3.524 Å, see
0
Fig. S1 and Fig. S2a). The molecular conformation is stabilized by
450
500
550
600
650
these hydrogen bonds and the intermolecular
p–p stacks (see
Wavelength (nm)
Fig. S2b). All of these weak intermolecular interactions result in a
three-dimensional frame network for 3.
Fig. 5. The emission spectra (kex = 360 nm) of complexes 2 and 7.
3.3. Luminescent properties
From the luminescent emission spectra of complexes 1–8, it is
obvious that the sensitivity ability of L1 and L2 is different for
the various lanthanide ions. For the EuIII ion, both L1 and L2 exhibit
excellent sensitivity ability, and the strongest luminescent emis-
sions were observed for complexes 1 and 6 among the two set of
complexes, respectively. For the DyIII ion, the weakest luminescent
emission was observed in complex 5. So, the sensitivity ability of
L1 and L2 may decrease in the sequence EuIII > TbIII > SmIII > DyIII
and EuIII > TbIII, respectively. Comparing the sensitivity ability of
L1 with that of L2 shows that L2 seems to be better than L1. For
example, the luminescent intensity (65091 a.u) of the EuIII
5D0 ? 7F2 transition in 6 is about 4.9 times as strong as that
(13265 a.u) of 1, and the intensity ratio of TbIII 5D4 ? 7F5 in com-
plex 7 (4754 a.u) and 2 (2220 a.u) is about 2:1. It is worth noting
that complex 8 still shows a typical emission of the EuIII ion with
the luminescent intensity (1750 a.u) for the 5D0 ? 7F2 transition,
though it contains the [C2Co2(CO)6] alkyne-bridging cobalt
Except for complex 3, the photophysical properties of the lan-
thanide complexes have been studied at 298 K in the solid state.
Upon excitation of the analogous ligand-centered absorption band,
all the complexes exhibit typical emission spectra for the lantha-
nide ions. Complexes 1, 6 and 8 show the visible emission bands
of EuIII (5D0 ? 7Fj transitions, j = 0, 1, 2, 3 and 4) ions, and the stron-
gest emission band is the induced electric dipole transition
5D0 ? 7F2 (Figs. 3 and 4), indicating that the EuIII ions occupy sites
of low symmetry without an inversion center [31–33]. Complexes
2 and 7 feature the luminescent emission spectra of TbIII (5D4 ? 7Fj
transitions, j = 6, 5, 4 and 3), and the strongest sensitive transition
is the 5D4 ? 7F5 transition (Fig. 5). Complexes 4 and 5 show the
characteristic visible emission bands of SmIII (4G5/2 ? 6Hj/2 transi-
tions, j = 9, 7 and 5) and DyIII (4F9/2 ? 6Hj/2 transitions, j = 15, 13
4
and 11) ions, and the strongest sensitive transitions are G5/
2 ? 6H7/2 and 4F9/2 ? 6H13/2, respectively (see Fig. S3).

B.-H. Zhu et al. / Polyhedron 74 (2014) 67–71
71
Table 2
Photoluminescent data of the complexes 1 and 6 in the solid state at room temperature.
Complexes
m00 (cmꢁ1
)
m01 (cmꢁ1
)
m02 (cmꢁ1
)
m03 (cmꢁ1
)
I01
I02
I02/I01
s
(ms)
1/
s
(msꢁ1
)
Ar
Anr
g (%)
1
6
17241
17241
16875
16874
16255
16255
15404
15404
1772
8188
13265
65091
7.49
7.95
0.590
0.763
1.695
1.311
451
475
1244
836
26.61
36.23
m
0J refers to the energy barrier and
m
0J = 1/kJ, I01 and I02 are the integrated intensities of the EuIII 5D0
?
7F1 and 5D0
?
7F2 transitions. is lifetimes (ms), Ar (sꢁ1) is the radiative
s
emission coefficient, Anr (sꢁ1) is the non-radiative emission coefficient,
g
(%) is the quantum efficiency. Refs. [36,37].
carbonyl luminescence extinction unit. This will provide a new
model complex for the study of carbon monoxide releasing mole-
cule drugs possessing a luminescence probe function. Efforts to
estimate the ability of the carbon monoxide release of complex 8
is currently in progress.
To further examine these lanthanide complexes, the lumines-
cence decay curves of EuIII (5D0) in complexes 1 and 6 were
measured at room temperature (see Fig. S4). From the results,
the lifetime of EuIII (5D0 excited level) in 1 and 6 was calculated
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.poly.2014.02.044.
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Acknowledgements
This work was financially supported by the National Natural
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CCDC 895244 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK; fax: (+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.