A series of pyrazolone lanthanide (III) complexes: Synthesis, crystal structures and fluorescence

Article abstract of DOI:10.1016/j.ica.2006.10.010

A series of pyrazolone lanthanide complexes: Ln(PMPP)₃ · 2H₂O · C₂H₅OH (Ln = Nd (1), Sm (2), Gd (3), Dy (4); PMPP = 1-phenyl-3-methyl-4-propionyl-5-pyrazolone) have been synthesized by the hydrothermal method with the starting ligand PMPP-SAH (1-phenyl-3-methyl-4-(salicylidene hydrazone)-propionyl-5-pyrazolone) changed into PMPP during the formation process of complexes. All the complexes were structurally characterized by X-ray crystallography. The fluorescence of these four complexes 1-4 in solid state and DMF solution was investigated via F-4500 spectrophotometer and all of them indicate a fluorescent behavior at room temperature.

Full text of DOI:10.1016/j.ica.2006.10.010

Inorganica Chimica Acta 360 (2007) 1995–2001
www.elsevier.com/locate/ica
A series of pyrazolone lanthanide (III) complexes: Synthesis,
crystal structures and fluorescence
*
Jun Li, Li Zhang, Lang Liu, Guangfei Liu, Dianzeng Jia , Guancheng Xu
Institute of Applied Chemistry, Xinjiang University, No. 14 Shengli Road, Urumqi, Xinjiang Province 830046, China
Received 14 July 2006; received in revised form 18 October 2006; accepted 19 October 2006
Available online 25 October 2006
Abstract
A series of pyrazolone lanthanide complexes: Ln(PMPP)3 Æ 2H2O Æ C2H5OH (Ln = Nd (1), Sm (2), Gd (3), Dy (4); PMPP = 1-phe-
nyl-3-methyl-4-propionyl-5-pyrazolone) have been synthesized by the hydrothermal method with the starting ligand PMPP-SAH
(1-phenyl-3-methyl-4-(salicylidene hydrazone)-propionyl-5-pyrazolone) changed into PMPP during the formation process of com-
plexes. All the complexes were structurally characterized by X-ray crystallography. The fluorescence of these four complexes 1–4
in solid state and DMF solution was investigated via F-4500 spectrophotometer and all of them indicate a fluorescent behavior at
room temperature.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Lanthanide; Derivatives of pyrazolone; Crystal structures; Fluorescence
1. Introduction
To amplify the scope of derivatives of pyrazolone coor-
dinated with rare earth, our group focuses much effort on
synthesizing new derivatives of pyrazolone lanthanide com-
plexes, studying on their crystal structures and fluorescent
properties. We choose the derivatives of pyrazolone
PMPP-SAH (1-phenyl-3-methyl-4-(salicylidene hydra-
zone)-propionyl-5-pyrazolone) coordinated with lantha-
nide ions, while, what amazed us is that the starting
ligand PMPP-SAH had been changed into PMPP during
the formation process of Ln(PMPP)3 Æ 2H2O Æ C2H5OH
(Ln = Nd (1), Sm (2), Gd (3), Dy (4); PMPP = 1-phenyl-
3-methyl-4-propionyl-5-pyrazolone) and found that these
complexes showed interesting structures and fluorescence
(see Chart 1).
Investigation on molecular coordination compounds of
lanthanide ions has been attracted significant attention,
owing to their fluorescent broad applications in biochemis-
try, material chemistry, medicine and so forth [1–4].
Among them, rare earth b-diketonate complexes are a kind
of high functional compounds with outstanding optical
properties which can be used as fluorescence probes [5–7].
Since, b-diktonate coordination with lanthanide (III) ions
has undergone a great proliferation in recent years.
Meanwhile, 4-acyl-pyrazolone derivatives are widely
used in many fields in the society, especially clinical and
analytical applications [8–10], because pyrazolone, espe-
cially 4-acyl-pyrazolone, displays several different coordi-
nation modes, with respect to classical b-diketonate
[11–13]. In our previous work, we have investigated the
synthesis and crystal structure of several derivatives of pyr-
azolone translation metal complexes [14–16].
2. Experimental
2.1. Syntheses
Nd(NO3)3 Æ 5H2O, Sm(NO3)3 Æ 6H2O, Gd(NO3)3 Æ 6H2O,
Dy(NO3)3 Æ 5H2O were prepared by dissolving Nd2O3,
Sm2O3, Gd2O3, or Dy2O3 in nitric acid in aqueous
*
Corresponding author. Tel./fax: +86 991 8580032.
E-mail address: jdz@xju.edu.cn (D. Jia).
0020-1693/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2006.10.010

1996
J. Li et al. / Inorganica Chimica Acta 360 (2007) 1995–2001
2.2. Instrumentation
The elemental analyses (C, H, N) were determined on a
PE-2400 element analyzer. The Re (III) ions were deter-
mined by ICP on a Plasma-Spec analyzer. The thermal
analyses were carried out on a NETZSCH STA 449C
instrument with a heating rate of 20 ꢁC minꢀ1 in an atmo-
sphere of flowing air. The crystal structures were analyzed
using a Bruker Smart 1000 CCD and the SHELXTL 97 crys-
tallographic software package of molecular structure. The
fluorescence emission spectra were performed on a HIT-
ACHI F-4500 FL Spectrophotometer at room temperature
with 380 nm excitation cut-off filter, emission slit at 5 nm
and PMT voltage at 400 V. The scan speed was 240 nm/
min.
Chart 1.
solutions, then crystallizing the products. 1-Phenyl-3-
methyl-4-propionyl-pyrazolone-5 (PMPP) [17] and the sali-
cylic hydrazone (SAH) [18] was synthesized and purified
according to the literature method. And the ligand
PMPP-SAH was synthesized by refluxing equimolar PMPP
and SAH in ethanol for 4 h, adding a few drops of glacial
acetic acid as a catalyst. On cooling, the yellow solid
obtained was filtered, washed with ethanol, and dried in
air. m.p. 178–180 ꢁC. Anal. Calc. for C20H20N4O2 (Fw:
348.40): C, 68.95; H, 5.79; N, 16.08. Found: C, 69.14; H,
6.14; N, 16.11%. The syntheses of the complexes were per-
formed under hydrothermal condition. A mixture was pre-
pared of Ln(NO3)3 Æ XH2O (X = 5, Ln = Nd, Dy; X = 6,
Ln = Sm, Gd) (0.2 mmol), PMPP-SAH (0.6 mmol), water
(10 ml) and EtOH (20 ml), heated in a Teflon-lined stainless
steel autoclave for 48 h inside a programmable electric fur-
nace at 130 ꢁC. After cooling the autoclave to room temper-
ature over 48 h, the mixture was filtered off, and then the
mixture was allowed to evaporate slowly and reddish brown
single crystals suitable for X-ray diffraction were obtained
after two weeks. The crystals are stable and no changes were
observed after storing under ambient atmosphere. The ele-
mental analyses of the synthesized complexes are summa-
rized in Table 1.
2.3. X-ray crystallography
Suitable single crystals of the complexes 1–4 were
mounted on a Bruker Smart 1000 CCD diffractometer
equipped with graphite monochromated Mo Ka
˚
(k = 0.71073 A) radiation. Empirical absorption correc-
tions were applied. The unit cell parameters were deter-
mined by least squares refinements of all reflections in all
four of the cases. All the structures were solved by direct
method and refined by full-matrix least squares on F2.
All non-hydrogen atoms were refined anisotropically, and
hydrogen atoms were located from the difference map,
and then added geometrically. All calculations were per-
formed using the SHELXTL97 program package. Crystal data
and experimental details for complexes 1–4 are contained
in Table 2.
3. Results and discussion
We found that the starting ligand PMPP-SAH changed
into PMPP in the forming process of complexes 1–4. On
the contrary, the PMPP-SAH showed great stability in
the presence transition metals and formed polynuclear
and supramolecular complexes with special structures in
the research by our group. This is probably because the
Ln (III) ions induce the activation and cleavage of the car-
boxamido bond [19]. High coordination numbers of lan-
thanide elements have advantages in certain organic
reactions that can be promoted catalytically in the presence
of lanthanide ions. The catalytic roles of lanthanide ions
and their complexes in the hydrolytic cleavage of phos-
phate diesters have been considerably studied. However,
so far, the identification of the catalytic mechanism has
not been ambiguously rendered [19]. In our work, the
ligand PMPP-SAH has been changed into PMPP in the
presence of Ln (III) ions.
Table 1
Composition of the products determined by elemental analysis
Complex
%
C
H
N
RE
Nd(C13H13N2O3)3 Æ 2H2O Æ C2H5OH (1)
Calc.
Found
53.87 5.40 9.23 15.78
53.44 5.33 9.27 15.35
Sm(C13H13N2O3)3 Æ 2H2O Æ C2H5OH (2)
Calc.
Found
53.51 5.37 9.13 16.34
53.05 5.23 9.49 16.51
Gd(C13H13N2O3)3 Æ 2H2O Æ C2H5OH (3)
Calc.
Found
53.12 5.33 9.06 16.96
53.44 5.33 9.23 17.29
The four complexes with the general formula Ln
(PMPP)3 Æ 2H2O Æ C2H5OH (Ln = Nd (1), Sm (2), Gd (3),
Dy (4)) crystallize isostructurally with Tb(PMPP)3 Æ
2H2O Æ C2H5OH reported by Chunhui Huang and cowork-
ers [20]. As shown in Fig. 1, they are built up by the
Dy(C13H13N2O3)3 Æ 2H2O Æ C2H5OH (4)
Calc.
Found
52.82 5.30 9.01 17.43
53.07 5.40 9.25 17.08

J. Li et al. / Inorganica Chimica Acta 360 (2007) 1995–2001
1997
Table 2
Crystal data and structure refinement parameters for complexes 1–4
Complexes
1
2
3
4
Empirical formula
Formula weight
Crystal system
T (K)
C41H49N6O9Nd
914.10
monoclinic
294(2)
C41H49N6O9Sm
920.21
monoclinic
293(2)
C41H49N6O9Gd
927.11
monoclinic
293(2)
C41H49N6O9Dy
932.36
monoclinic
294(2)
˚
Wavelength (A)
0.71073
P2(1)/c
17.783(2)
12.9749(17)
18.438(2)
90
102.249(2)
90
4157.4(9)
4
0.71073
P2(1)/c
17.7165(11)
12.9394(8)
18.3657(12)
90
101.874
90
4120.1(5)
4
0.71073
P2(1)/c
17.7165(11)
12.9394(8)
18.3657(12)
90
101.874(10)
90
4120.1(5)
4
0.71073
P2(1)/c
17.608(4)
12.901(3)
18.299(4)
90
101.355(3)
90
4075.4(15)
4
Space group
˚
a (A)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
Z
Absorption coefficient
1.310
1.487
1.671
1.896
(mmꢀ1
)
Crystal size (mm)
H range for data collection
(ꢁ)
0.22 · 0.18 · 0.12
1.93–26.52
0.32 · 0.22 · 0.18
1.94–25.03
0.42 · 0.32 · 0.20
1.94–25.03
0.26 · 0.24 · 0.20
1.18–26.38
Reflections collected/
23268/8596
21832/7264
21789/7260
22399/8275
unique
Completeness (%)
Limiting indices
99.5
99.9
99.9
99.3
ꢀ22 6 h 6 18, 15 6 k 6 16,
ꢀ13 6 h 6 21, 15 6 k 6 15,
ꢀ21 6 h 6 20, 15 6 k 6 14,
ꢀ17 6 h 6 21, 16 6 k 6 14,
ꢀ16 6 l 6 22
ꢀ21 6 l 6 23
ꢀ21 6 l 6 21
ꢀ19 6 l 6 21
Rint
Dcalc (g cmꢀ3
0.0248
0.0137
0.0172
0.0345
1.520
)
1.460
1.484
1.495
Data/restraints/parameters
F(000)
8596/34/530
1876
7264/36/540
1884
7260/36/540
1892
8275/28/529
1900
Goodness-of-fit on I
Final R indices [I > 2h(I)]
R indices (all data)
1.062
1.089
1.035
1.019
R1 = 0.0282, xR2 = 0.0661
R1 = 0.0456, xR2 = 0.0761
0.859 and ꢀ0.503
R1 = 0.0201, xR2 = 0.0556
R1 = 0.0198, xR2 = 0.0506
R1 = 0.0303, xR2 = 0.0652
R1 = 0.0511, xR2 = 0.0732
0.791 and ꢀ0.625
R1 = 0.0244, xR2 = 0 .0584 R1 = 0.0247, xR2 = 0.0528
0.633 and ꢀ0.443 0.574 and ꢀ0.507
Largest differencꢀe3in peak
˚
and hole (e A
)
mononuclear Ln(PMPP)3 Æ 2H2O Æ C2H5OH compound
molecules. The rare earth atoms are coordinated by six
oxygen atoms of three bidentate PMPP ligands and the
other two oxygen atoms of two coordinated water mole-
cules to complete 8-fold coordinated polyhedron. As far
as the average bond lengths between the Ln(III) ion and
the pyrazolone oxygen atom, and that between the Ln(III)
ion and water oxygen atoms, the former is slightly shorter
than the latter, which we can confirmed from the data in
Table 3. This may be result of the negative charge of the
pyrazolone oxygen atom, which could be more strongly
coordinated to the Ln (III) ion due to electrostatic effects
[20]. Meanwhile, it indicates that the ligand PMPP has bet-
ter donating properties than the water molecule [21], and
the ligand can approach closer to the central ion. The
˚
Ln–O bond distances vary over the range 2.372–2.504 A
˚
for compound 1, 2.3493–2.4785 A for compound 2,
˚
˚
2.3378–2.4491 A for compound 3 and 2.306–2.432 A for
compound 4 (Table 3). With increasing atomic number of
the rare earth atom, the Ln–O bond distances decrease
monotonously, which according to excellently with the
well-known ‘‘lanthanide contraction’’ [22].
Fig. 1. Crystal structure of a Nd(L)3 Æ 2H2O Æ C2H5OH complex molecule
with thermal ellipse at the 30% probability level. The hydrogen atoms and
two ethanol molecules being omitted for clarity (Ln = Sm (2), Gd (3) and
Dy (4) have the same structure).
As shown in Fig. 2, the eight oxygen atoms form a
square-antiprism coordination polyhedron around the

1998
J. Li et al. / Inorganica Chimica Acta 360 (2007) 1995–2001
Table 3 (continued)
Table 3
˚
Selected bond lengths (A) and angles (ꢁ) for complexes 1–4
Complex 1 (Nd)
Complex 4 (Dy)
Dy(1)–O(5)
2.332(2)
2.363(2)
Dy(1)–O(7)
Dy(1)–O(8)
2.395(2)
2.432(3)
Dy(1)–O(2)
Nd(1)–O(1)
Nd(1)–O(3)
Nd(1)–O(5)
Nd(1)–O(4)
2.372(19)
2.382(19)
2.410(2)
2.437(2)
Nd(1)–O(2)
Nd(1)–O(6)
Nd(1)–O(7)
Nd(1)–O(8)
2.440(2)
2.447(2)
2.463(2)
2.504(2)
O(3)–Dy(1)–O(1)
O(3)–Dy(1)–O(5)
O(1)–Dy(1)–O(5)
O(3)–Dy(1)–O(2)
O(1)–Dy(1)–O(2)
O(5)–Dy(1)–O(2)
O(3)–Dy(1)–O(4)
O(1)–Dy(1)–O(4)
O(5)–Dy(1)–O(4)
O(2)–Dy(1)–O(4)
O(3)–Dy(1)–O(6)
O(1)–Dy(1)–O(6)
O(5)–Dy(1)–O(6)
O(2)–Dy(1)–O(6)
142.29(8)
76.00(8)
138.78(9)
75.04(8)
75.49(8)
115.04(9)
74.86(8)
119.06(8)
77.79(9)
142.81(9)
140.80(8)
74.94(8)
74.90(8)
141.97(9)
O(4)–Dy(1)–O(7)
O(6)–Dy(1)–O(7)
O(3)–Dy(1)–O(8)
O(1)–Dy(1)–O(8)
O(5)–Dy(1)–O(8)
O(2)–Dy(1)–O(8)
O(4)–Dy(1)–O(8)
O(6)–Dy(1)–O(8)
O(7)–Dy(1)–O(8)
O(4)–Dy(1)–O(6)
O(3)–Dy(1)–O(7)
O(1)–Dy(1)–O(7)
O(5)–Dy(1)–O(7)
O(2)–Dy(1)–O(7)
73.44(9)
111.68(8)
113.80(9)
77.96(9)
69.33(9)
71.66(10)
141.79(9)
79.22(10)
143.06(9)
73.77(9)
80.70(8)
71.71(9)
146.78(9)
80.60(9)
O(1)–Nd(1)–O(3)
O(1)–Nd(1)–O(5)
O(3)–Nd(1)–O(5)
O(1)–Nd(1)–O(4)
O(3)–Nd(1)–O(4)
O(5)–Nd(1)–O(4)
O(1)–Nd(1)–O(2)
O(3)–Nd(1)–O(2)
O(5)–Nd(1)–O(2)
O(4)–Nd(1)–O(2)
O(1)–Nd(1)–O(6)
O(3)–Nd(1)–O(6)
O(5)–Nd(1)–O(6)
O(4)–Nd(1)–O(6)
142.46(7)
O(5)–Nd(1)–O(7)
O(4)–Nd(1)–O(7)
O(2)–Nd(1)–O(7)
O(6)–Nd(1)–O(7)
O(1)–Nd(1)–O(8)
O(3)–Nd(1)–O(8)
O(5)–Nd(1)–O(8)
O(4)–Nd(1)–O(8)
O(2)–Nd(1)–O(8)
O(6)–Nd(1)–O(8)
O(7)–Nd(1)–O(8)
O(2)–Nd(1)–O(6)
O(1)–Nd(1)–O(7)
O(3)–Nd(1)–O(7)
147.05(8)
80.74(8)
73.27(8)
111.35(7)
113.64(8)
77.88(8)
68.95(8)
71.48(9)
141.83(8)
79.64(9)
143.53(8)
74.40(7)
81.53(7)
71.61(7)
76.63(7)
137.97(8)
77.23(7)
73.04(7)
117.29(7)
72.62(7)
121.36(7)
76.81(8)
142.48(8)
138.98(7)
76.71(7)
72.64(7)
141.65(8)
Complex 2 (Sm)
Sm(1)–O(6)
Sm(1)–O(2)
Sm(1)–O(4)
Sm(1)–O(1)
2.3493(16)
Sm(1)–O(5)
Sm(1)–O(3)
Sm(1)–O(7)
Sm(1)–O(8)
2.4090(17)
2.4248(16)
2.4382(18)
2.4785(18)
2.3551(16)
2.3803(16)
2.4079(16)
O(6)–Sm(1)–O(2)
O(6)–Sm(1)–O(4)
O(2)–Sm(1)–O(4)
O(6)–Sm(1)–O(1)
O(2)–Sm(1)–O(1)
O(4)–Sm(1)–O(1)
O(6)–Sm(1)–O(5)
O(2)–Sm(1)–O(5)
O(4)–Sm(1)–O(5)
O(1)–Sm(1)–O(5)
O(6)–Sm(1)–O(3)
O(2)–Sm(1)–O(3)
O(4)–Sm(1)–O(3)
O(1)–Sm(1)–O(3)
142.36(6)
O(5)–Sm(1)–O(7)
O(3)–Sm(1)–O(7)
O(6)–Sm(1)–O(8)
O(2)–Sm(1)–O(8)
O(4)–Sm(1)–O(8)
O(1)–Sm(1)–O(8)
O(5)–Sm(1)–O(8)
O(3)–Sm(1)–O(8)
O(7)–Sm(1)–O(8)
O(5)–Sm(1)–O(3)
O(6)–Sm(1)–O(7)
O(2)–Sm(1)–O(7)
O(4)–Sm(1)–O(7)
O(1)–Sm(1)–O(7)
73.50(6)
111.91(6)
114.01(6)
77.81(6)
69.27(6)
71.57(7)
141.84(7)
79.30(7)
143.16(6)
74.14(6)
80.90(6)
71.67(6)
146.90(6)
80.40(6)
76.33(6)
138.44(6)
76.55(6)
73.92(6)
116.45(6)
73.39(6)
120.41(6)
77.14(6)
142.67(7)
139.55(6)
76.14(6)
73.47(6)
141.73(6)
Complex 3 (Gd)
Gd(1)–O(6)
Gd(1)–O(2)
Gd(1)–O(4)
Gd(1)–O(1)
2.3378(16)
Gd(1)–O(5)
Gd(1)–O(3)
Gd(1)–O(7)
Gd(1)–O(8)
2.3939(17)
2.4056(17)
2.4113(18)
2.4491(19)
2.3485(16)
2.3663(16)
2.3885(17)
Fig. 2. The coordination polyhedron around the central Neodymium (III)
ions (Ln = Sm (2), Gd (3)and Dy (4) have the same structure).
O(6)–Gd(1)–O(2)
O(6)–Gd(1)–O(4)
O(2)–Gd(1)–O(4)
O(6)–Gd(1)–O(1)
O(2)–Gd(1)–O(1)
O(4)–Gd(1)–O(1)
O(6)–Gd(1)–O(5)
O(2)–Gd(1)–O(5)
O(4)–Gd(1)–O(5)
O(1)–Gd(1)–O(5)
O(6)–Gd(1)–O(3)
O(2)–Gd(1)–O(3)
O(4)–Gd(1)–O(3)
O(1)–Gd(1)–O(3)
142.54(6)
O(6)–Gd(1)–O(8)
O(2)–Gd(1)–O(8)
O(4)–Gd(1)–O(8)
O(1)–Gd(1)–O(8)
O(5)–Gd(1)–O(8)
O(3)–Gd(1)–O(8)
O(7)–Gd(1)–O(8)
O(4)–Gd(1)–O(7)
O(1)–Gd(1)–O(7)
O(5)–Gd(1)–O(7)
O(3)–Gd(1)–O(7)
O(5)–Gd(1)–O(3)
O(6)–Gd(1)–O(7)
O(2)–Gd(1)–O(7)
113.66(6)
77.87(6)
69.55(6)
71.52(7)
141.84(7)
79.54(7)
143.12(6)
146.59(6)
80.60(6)
73.45(6)
111.45(6)
73.90(6)
81.10(6)
71.71(6)
75.82(6)
138.74(6)
75.89(6)
74.67(6)
115.91(6)
74.09(6)
119.85(6)
77.16(6)
142.75(6)
140.12(6)
75.40(6)
74.40(6)
141.86(6)
central Nd atom. Four oxygen atoms form the upper
plane, and the others form the bottom plane in their coor-
dination polyhedron, respectively. And the dihedral angles
Table 4
Dihedral angles between the planes
Complex 1
Complex 2
Complex 3
Complex 4
(Nd)
(Sm)
(Gd)
(Dy)
Plane 1
Plane 2
O2, O3, O6, O1, O8, O6, O1, O8, O6, O1, O7, O6,
O7 O4 O4 O4
O1, O8, O5, O7, O2, O3, O2, O7, O5, O2, O8, O5,
Complex 4 (Dy)
Dy(1)–O(3)
Dy(1)–O(1)
O4
O5
O3
O3
2.306(2)
2.310(2)
Dy(1)–O(4)
Dy(1)–O(6)
2.364(2)
2.380(2)
Dihedral
angle
2.4ꢁ
2.1ꢁ
2.0ꢁ
1.9ꢁ

J. Li et al. / Inorganica Chimica Acta 360 (2007) 1995–2001
1999
Table 6
Interactions parameters of complexes 1–4
a0
b0
˚
p–p Interactions
Cg–Cg (A)
Cg (I)–Res(I)–Cg(J)
Complex 1 (Nd)
Cg (3) [1] ! Cg (5)
3.917
14.40
21.00
Cg (3) = N5, N6, C35, C34, C33; Cg (5) = C14, C15, C16, C17, C18, C19
Complex 2 (Sm)
Cg (2) [1] ! Cg (4)
3.9226
15.05
7.77
Cg (2) = N3, N4, C20, C18, C19; Cg (4) = C9, C10, C11, C12, C13, C14
Complex 3 (Gd)
Cg (2) [1] ! Cg (4)
3.9357
15.78
7.87
Cg (2) = N3, N4, C20, C18, C19; Cg (4) = C9, C10, C11, C12, C13, C14
Complex 4 (Dy)
Cg (3) [1] ! Cg (4)
3.932
16.36
7.42
Cg (3) = N5, N6, C35, C34, C33; Cg (4) = C1, C2, C3, C4, C5, C6
Fig. 3. 3D framework of the Nd(L)3 Æ 2H2O Æ C2H5OH complexes mole-
cules view along b axis.
Cg: Centroid, a: dihedral angle between planes I and J, b: angle Cg
(I) ! Cg (J) or Cg (I) ! Me vector and normal to plane I.
of them are listed in Table 4. These small dihedral angles
imply that the two planes are paralleled in each
compound.
The TG–DTA curves of complexes 1–4 are similar.
Some data of thermal analyses are listed in Table 7. The
DTA curves of complexes have an endothermic peak
around 150 ꢁC and the corresponding TG curves both exhi-
bit a weight loss. This process corresponds to the com-
plexes losing two water molecules and one ethanol
molecule. The experimental values are in agreement with
the theoretical ones within the experimental error. These
results are in accordance with the compositions of the com-
pounds determined by elemental analyses. Meanwhile, they
answered for the crystal structure.
In the packing arrangement of complex 1, the molecules
are stacked into a 3D supramolecular framework through
the hydrogen-bonding interactions from the pyrozolone
ring and water molecules (Fig. 3). The corresponding data
for the H-bonds are listed in Table 5. There are also weak
intermolecular interactions in the complexes, which are p–p
interactions between the pyrazolone ring and benzene ring
interiorly. The p–p interactions parameters of complexes 1–
4 are listed in Table 6.
The fluorescence spectra of the Ln(PMPP)3 Æ 2H2O Æ
C2H5OH complexes in solid state excited by a 380 nm laser
beam are shown in Fig. 4. All complexes exhibit a green
emission band peaked at 550 nm which indicates that the
fluorescence spectral of complexes is relevant to the struc-
ture. However, the spectra of the complexes have a slightly
red shift as compared to the ligand, which probably was led
by the charge-transfer that was caused by the alternation of
the structure of the ligand during the formulation of com-
plex [23]. And the emission peak intensity for complex 4 is
much stronger than the other complexes in solid state. It
probably assigned to the lowest triplet state energy level
of ligand and the lowest excited state energy level of
Dy3+ ion is better matched [22].
The emission spectra of the complexes in dimethylfor-
maide (DMF) solution, however, are quite different from
those of the powdered samples as shown in Fig. 5. In the
same laser beam, the complexes in DMF exhibit a green
emission band too, and the fluorescence peaks of all com-
plexes have a blue shift compared with that in solid state.
However, the emission peak of complex 3 has a slightly
red shift as compared to the other complexes in DMF
solution, while this phenomenon had not occurred in solid
state. We consider all the difference in emission as the
result of the different environment between the two states
[24].
Table 5
Some significant interaction parameters and hydrogen bonding parame-
ters for complexes 1–4
D–HA
d(D–H)
d(Hꢁ ꢁ ꢁA)
d(Dꢁ ꢁ ꢁA)
(DHA)
Complex 1
O7–H7Aꢁ ꢁ ꢁN2
O7–H7Bꢁ ꢁ ꢁN6
O8–H8Aꢁ ꢁ ꢁN4
O8–H8Bꢁ ꢁ ꢁO9
0.869
0.901
0.883
0.860
1.974
1.935
1.938
2.075
2.830
2.824
2.815
2.892
168.38
168.91
171.61
158.48
Complex 2
O7–H7Aꢁ ꢁ ꢁN3
O7–H7Bꢁ ꢁ ꢁN5
O8–H8Aꢁ ꢁ ꢁN1
O8–H8Bꢁ ꢁ ꢁO9
0.850
0.850
0.850
0.861
1.988
1.996
1.966
2.175
2.827
2.834
2.816
2.818
168.86
168.39
178.72
131.25
Complex 3
O7–H7Aꢁ ꢁ ꢁN3
O7–H7Bꢁ ꢁ ꢁN5
O8–H8Aꢁ ꢁ ꢁN1
O8–H8Bꢁ ꢁ ꢁO9
0.850
0.850
0.850
0.861
2.004
2.011
1.986
2.181
2.842
2.849
2.836
2.825
168.32
168.48
178.27
131.41
Complex 4
O7–H7Aꢁ ꢁ ꢁN6
O7–H7Bꢁ ꢁ ꢁN4
O8–H8Aꢁ ꢁ ꢁO9
O8–H8Bꢁ ꢁ ꢁN2
0.889
0.871
0.919
0.868
1.964
1.994
2.128
1.971
2.850
2.857
2.888
2.833
174.60
170.27
139.38
171.72

2000
J. Li et al. / Inorganica Chimica Acta 360 (2007) 1995–2001
Table 7
Thermal analytical results (TG, DTG, DTA) for the complexes 1–4
Complex
Temperature range (ꢁC)
DTGmax (ꢁC)
Removed group
Mass loss (%)
Residue (%)
Residue Product
Found
Calc.
Found
Calc.
Nd(L)3 Æ 2H2O Æ C2H5OH
Sm(L)3 Æ 2H2O Æ C2H5OH
Gd(L)3 Æ 2H2O Æ C2H5OH
Dy(L)3 Æ 2H2O Æ C2H5OH
104–242
115–226
89–208
96–206
149.9
182.4
124.4
138.7
2H2O + C2H5OH
2H2O + C2H5OH
2H2O + C2H5OH
2H2O + C2H5OH
7.52
8.99
8.20
8.28
9.98
8.92
8.85
8.80
20.00
20.25
16.38
17.81
18.14
19.11
19.62
20.15
Nd2O3
Sm2O3
Gd2O3
Dy2O3
Educational Institutions (XJEDU2005S01) and the Young
Scholar Science Foundation of Xinjiang University
(QN040107).
Appendix A. Supplementary material
CCDC 613546, 613547, 613548 and 613549 contain the
supplementary crystallographic data for this paper. These
data can be obtained free of charge via http://www.ccdc.ca-
m.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. TG–DTA plots for 1–4 are available from
the authors on request. Supplementary data associated
with this article can be found, in the online version, at
doi:10.1016/j.ica.2006.10.010.
Fig. 4. Room temperature fluorescence spectra of Ln(PMPP)3 Æ 2H2O Æ
C2H5OH in solid state excited by a 380 nm laser beam.
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