Synthesis, characterization, and thermal analysis of Re(C 10H9N2O4)3·nH 2O complexes

Article abstract of DOI:10.1080/15533170601187417

Six new complexes of C10H10N2O4 with light rare earth ions RE(C10H9N2O4)3nH2O, (RE=La, Ce, Nd, Sm, Eu, Gd) have been synthesized in alcohol aqueous solution. The composition of the complexes is determined by elemental analysis, IR, UV, and X-ray powder diffraction. The thermal decomposition processes of the six complexes were studied by TG-DTG curves. It was found that the thermal decomposition processes of the complexes could be divided into three stages. The plot of apparent activation energies of the second thermal decomposition stage for the complexes versus the atomic number showed a grouping effect of the lanthanide elements.

Full text of DOI:10.1080/15533170601187417

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Synthesis, Characterization, and Thermal Analysis of
Re(C10H9N2O4)3 · nH2O Complexes
J.‐H. Wang a , X.‐R. Liu a , A.‐N. Zhou a & S.‐Y. He b
a Department of Chemistry and Chemical Engineering , Xi'an University of Science and
Technology , Xi'an, P. R. China
b Department of Chemistry, Shaanxi Key Laboratory of Physico‐Inorganic Chemistry ,
Northwest University , Xi'an, P. R. China
Published online: 30 Mar 2007.
To cite this article: J.‐H. Wang , X.‐R. Liu , A.‐N. Zhou & S.‐Y. He (2007) Synthesis, Characterization, and Thermal Analysis
of Re(C10H9N2O4)3 · nH2O Complexes, Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 37:2,
91-95
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Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry, 37:91–95, 2007
Copyright # 2007 Taylor & Francis Group, LLC
ISSN: 1553-3174 print/1553-3182 online
DOI: 10.1080/15533170601187417
Synthesis, Characterization, and Thermal Analysis
.
of Re(C10H9N2O4)3 nH2O Complexes
J.-H. Wang, X.-R. Liu, and A.-N. Zhou
Department of Chemistry and Chemical Engineering, Xi’an University of Science and Technology,
Xi’an, P. R. China
S.-Y. He
Department of Chemistry, Shaanxi Key Laboratory of Physico-Inorganic Chemistry,
Northwest University, Xi’an, P. R. China
.
RE(C10H9N2O4)3 2H2O have been synthesized by our
Six new complexes of C10H10N2O4 with light rare earth ions research group.[12] It was shown that the new kind of com-
.
RE(C10H9N2O4)3 nH2O, (RE 5 La, Ce, Nd, Sm, Eu, Gd) have
plexes have effective inhibitor against Botrytis cirerea
Pers.ex Tris., Alternaria alternata Fries keissler and Puccinia
striiformis Westendorp.
been synthesized in alcohol aqueous solution. The composition of
the complexes is determined by elemental analysis, IR, UV, and
X-ray powder diffraction. The thermal decomposition processes
of the six complexes were studied by TG-DTG curves. It was
found that the thermal decomposition processes of the complexes rare earth element RE(C10H9N2O4)3 2H2O have been syn-
could be divided into three stages. The plot of apparent activation
energies of the second thermal decomposition stage for the com-
In this paper, six new complexes of C10H10N2O4 with light
.
thesized and characterized. The coordination behavior, the
thermal decomposition process and thermal stability were dis-
cussed and compared.
plexes versus the atomic number showed a grouping effect of the
lanthanide elements.
EXPERIMENTAL
Keywords rare earth, pyruvic acid-salicylhydrazone, synthesis,
characterization, thermal analysis
Reagents
.
Re(NO3)3 nH2O was prepared from RE2O3 (99.95%) and
HNO3.[13] Glycin and pyriuvic acid are biochemical reagents.
Methyl salicylate, hydrazine hydrate, nonaqueous alcohol and
sodium hydroxide are all of analytical purity standards.
Elemental analysis was performed on a P.E. 2400 elemental
analyzer. IR spectra were recorded on a GXIV 5.0.1 Fourier IR
spectrometer. The UV spectrum was obtained by a TU-1900
UV-VIS spectrophotometer. X-ray powder diffraction was
operated on an X-ray powder diffraction. TG-DTG curve was
measured by TG-209 gravitational thermal analyzer.
INTRODUCTION
Aroylhydrazone as a ligand has attracted much attention for
its excellent bioactivity, strong coordination ability and com-
plicated coordination behavior.[1–3] There are some reports
about the complexes of aroylhydrazone with rare earth
elements,[4–11] and it was found that the coordination form
has three kinds: keto-form, enolic form and the dehydrogena-
tion coujugation form. The results of these reports also show
the lanthanide (III) complexes can accelerate the cleavage of
double-stranded DNA more efficiently than lanthanide ion
alone. Recently, a new aroylhydrazone ligand C10H10N2O4
and its complexes with heavy rare earth element
Synthesis of the Ligand and the Complexes
The ligand pyruvic acid-salicylhydrazone (C10H10N2O4)
was prepared according to the report.[14] Pyriuvic acid
(1.42 mL) was added to the solution of salicyloyl hydrazide
(3.09 g) in nonaqueous alcohol (30 mL). The mixture was
stirred on a water bath (808C) for 2 hours. The precipitate was
filtered and recrystallized from alcohol and washed by ether.
The white needle crystal was obtained with a yield of 60%.
Received 8 November 2006; accepted 15 December 2006.
Financial supports from the National Natural Science Foundation
of China under grant no. 2971023 are gratefully acknowledged. The
authors also thank Prof. H. W. Cai and Dr. F. S. Yang for their help
during experiments.
Address correspondence to A.-N. Zhou, Department of Chemistry
and Chemical Engineering, Xi’an University of Science and Technol-
ogy, Xi’an, P. R. China. E-mail: zhouanning2004@yahoo.com.cn
.
RE(NO3)3 nH2O was dissolved in nonaqueous alcohol,
then a solution of glycin was added dropwise with stirring.
The mixture was heated at 608C for 1 hour, then the alcohol
91

92
J.-H. WANG ET AL.
aqueous solution of the ligand was added dropwise with more than 200 cm21, which indicate that COO2 is coordinated
stirring and a large quantity of deposit appeared. The with the lanthanide ion in the form of one dentate. The amine I
reaction was carried out at 808C for 1 hour. The pH of (nC55O) is shift from 1700 to 1657–1662 cm21 after coordi-
reaction system was adjusted between 3–4. After filtering nation, which indicates that the C55O was coordinated. The
and washing with anhydrous ethanol and ether, the powdery n(N-H) of the free ligand at 3291 cm21 and its complexes at
complex was dried in a desiccator to weight stability.
3234–3246 cm21 show that active hydrogen of -NHN55
group still exists in the complexes. These shifts indicate that
the ligand is coordinated in keto-forms. Amine II(dN-H) is at
1531 cm21 in the free ligand and in its complexes at 1539–
1541 cm21 show that hydrogen of -NH- group still exists
after coordination. All complexes show a strong IR peak in
1657–1662 cm21 assigned to n(C55N) vibration, whereas
n(C55N) appears at 1646 cm21 in free ligand, which indicates
that the C55N (N atom) was coordinated. The bands at 820–
822 cm21 and 582–587 cm21 indicate that water was
coordinated.[16]
RESULTS AND DISCUSSION
Composition and Solubility of the Complexes
The results of elemental analysis for all the complexes are
listed in Table 1. From Table 1, it can be seen that the found
values are in agreement with the calculated ones.
The complexes are insoluble in ether, sparingly soluble in
water, methanol and alcohol, and easily soluble in DMF and
DMSO.
Infrared Spectra
UV Spectra
UV spectra of the ligand and the complexes were obtained
The main IR data of the ligand and their complexes are pre-
sented in Table 2. The IR spectra of all the complexes are
similar to each other. IR spectra of the ligand and the com- in DMF solution with DMF as a reference. The results are
plexes are identified according to Nakamoto.[15] The absorp- listed in Table 3. From Table 3, it can be seen that there is a
tion peak at 1755 cm21 assigned to n(COOH) in the free strong band at 312.5 nm in the ligand, which is the p-pꢀ tran-
ligand has been replaced by two new peaks: nas(COO2) (1 sition of the salicyloyl group. The band blue shift to 284.2–
611–1614 cm21) and ns(COO2) (1368–1369 cm21) in all 288.5 nm in the complexes shows that the conjugation of the
the complexes. The 4n(nas – ns) values of all complexes are salicyloyl group has been weakened after coordination.
TABLE 1
Elementary analysis of the complexes
Found/%
Calculated/%
Complexes
La(C10H9N2O4)3 2H2O
C
H
N
RE
C
H
N
RE
.
42.88
44.04
43.95
43.88
43.56
43.21
3.470
3.194
3.213
3.186
3.242
3.042
10.03
10.37
10.11
10.13
10.12
10.08
7.06
17.36
17.84
17.88
17.97
18.35
42.96
43.85
43.63
43.47
43.23
42.96
3.732
3.560
3.537
3.491
3.510
3.480
10.02
10.23
10.18
10.11
10.08
10.02
16.67
17.05
17.47
18.05
18.23
18.75
.
Ce(C10H9N2O4)3 H2O
.
Nd(C10H9N2O4)3 H2O
.
Sm(C10H9N2O4)3 H2O
.
Eu(C10H9N2O4)3 H2O
.
Gd(C10H9N2O4)3 H2O
TABLE 2
Important IR bands of the complexes (cm21
)
Compound
n(COOH) nas(COO2) ns(COO2) n(C55O) n(C55N) d(N-H) n(N-H) rO-H(H2O) vO-H (H2O)
C10H10N2O4
La(C10H9N2O4)3 2H2O
1755
—
—
—
1700
1657
1659
1660
1662
1661
1662
1646
1573
1572
1571
1572
1573
1571
1531
1540
1540
1539
1539
1541
1540
3291
3234
3236
3236
3246
3238
3242
—
—
.
1611
1614
1612
1613
1612
1614
1369
1369
1368
1369
1369
1368
821
821
821
822
822
820
582
582
582
583
587
585
.
Ce(C10H9N2O4)3 H2O
—
—
.
Nd(C10H9N2O4)3 H2O
.
Sm(C10H9N2O4)3 H2O
—
—
.
Eu(C10H9N2O4)3 H2O
.
Gd(C10H9N2O4)3 H2O
—

SIX NEW RARE EARTH COMPLEXES
93
TABLE 3
UV spectral data and luminescence properties for the ligand
and complexes
b ꢁ 1024
UV
l1(nm)
Fluorescence
l2(nm)
21
.
mol L
Compound
C10H10N2O4
La(C10H9N2O4)3 2H2O
1.02
1.08
1.19
1.15
1.21
1.17
1.00
312.5
284.3
286.5
285.6
288.5
284.2
287.6
430.0
409.1
408.4
408.2
408.3
408.6
408.1
.
.
Ce(C10H9N2O4)3 H2O
.
Nd(C10H9N2O4)3 H2O
.
Sm(C10H9N2O4)3 H2O
.
Eu(C10H9N2O4)3 H2O
.
Gd(C10H9N2O4)3 H2O
.
FIG. 1. The structure of the RE(C10H9N2O4)3 nH2O (n ¼ 1, 2).
Thermal Analysis of the Complexes
The thermal decomposition stages along with the weight
losses and the corresponding temperature ranges of the com-
The excitation wavelength of the excitation spectra is
360.0 nm; the excitation wavelength of the ligand is 430.0 nm;
and, the excitation wavelength of the complexes is 408.1–
409.4 nm; there is a small blue shift, which indicates that the
ligand has been coordinated to the lanthanide ions, and the exci-
tation of the ligand and the complexes belong to Lꢀ-L.[17]
21
.
plexes under heating rate of 58C min
are listed in
Table 5. For comparing, the decomposition process of
ligand according to He et al.[14] is also listed in Table 5.
The thermal decomposition process of the complexes can
be divided into three stage: The first-stage is connected
with the loss of water from the complexes; the second
stage is the lost of 3 N2 þ 6CO; the third-stage is the
further decarburization and dehydrogenation. The remainders
are rare earth oxides. The mass loss of three stages is in
accordance with the calculated value, showing that the
analysis of thermal decomposition process is reasonable.
Comparing the thermal decomposition process of ligand
and complexes, it can be found that the ligand decomposes
within 440–504–583 K and has no remainder. The
decomposition temperature range of the complexes is in
513–613–1073 K, which is obviously larger than the
ligand. It can be deduced that the stability of the complexes
exceeds the ligand.
X-Ray Powder Diffraction
The results of the X-ray powder diffraction for the salt
.
(Nd(NO3)3 4H2O), ligand (C10H10N2O4) and the complex
are shown in Table 4, respectively. The X-ray powder diffrac-
tion data of the salt and the ligand are carried out according to
Wu et al.[13] From Table 4, it can be seen that X-ray power
diffraction of the complexes is obviously different from the
ligand and the salt, and the complex is not simple lap joint of
the ligand and the salt either. It can be deduced that a new
complex is formed.
Based on the above characterizations of all the complexes,
the structure of the complexes may be as Figure 1.
TABLE 4
Data of X-ray for the ligand, salt and complexes
Compound
X-ray powder diffraction data
.
Nd(NO3) 4H2O
I/I0
d/nm
I/I0
d/nm
I/I0
d/nm
I/I0
d/nm
I/I0
100
0.8870
100
0.3601
100
1.4666
100
0.7878
100
0.7810
100
0.8008
80
0.5860
82
0.3386
39
0.7840
27
1.2134
39
1.1652
49
1.1906
80
0.5460
73
0.3684
27
0.4175
28
0.4156
30
0.4107
45
0.7811
20
0.3560
61
0.5611
25
0.4130
23
0.3414
24
0.3401
34
0.4180
20
0.2860
56
0.6321
21
1.2167
21
0.5218
21
0.5157
24
0.3435
8
0.2570
6
0.2020
C10H10N2O4
55
0.5764
20
0.5212
13
0.2877
13
0.2859
22
0.5292
46
0.6021
14
.
La(C10H9N2O4)3 2H2O
0.7286
9
0.2390
.
Ce(C10H9N2O4)3 H2O
.
Nd(C10H9N2O4)3 H2O
11
0.6878
15
0.6986
d/nm
I/I0
d/nm
.
Sm(C10H9N2O4)3 H2O

94
J.-H. WANG ET AL.
TABLE 5
Thermal decomposition for the complexes (b ¼ 5K/min)
Stage I
Stage II
Stage III
Temp
range (K)
Weight
loss (%)
Temp
range (K)
Weight
loss (%)
Temp
range (K)
Weight
loss (%)
Complexes
C10H10N2O4
La(C10H9N2O4)3 2H2O
303ꢀ440
313ꢀ519
313ꢀ521
313ꢀ510
313ꢀ515
313ꢀ519
313ꢀ514
19.38(19.80)
4.21(4.29)
2.20(2.19)
2.15(2.17)
2.18(2.16)
2.19(2.16)
2.17(2.15)
440ꢀ504
519ꢀ613
521ꢀ616
510ꢀ615
515ꢀ614
519ꢀ616
514ꢀ617
25.76(25.28)
29.78(30.03)
28.86(30.66)
29.32(30.43)
28.43(30.29)
29.07(30.21)
31.23(30.04)
504ꢀ583
20.85(19.80)
44.69(46.07)
46.89(47.08)
45.43(46.38)
47.63(46.15)
47.44(46.40)
46.03(46.13)
.
613ꢀ1073
616ꢀ1073
615ꢀ1073
614ꢀ1073
616ꢀ1073
617ꢀ1073
.
Ce(C10H9N2O4)3 H2O
.
Nd(C10H9N2O4)3 H2O
.
Sm(C10H9N2O4)3 H2O
.
Eu(C10H9N2O4)3 H2O
.
Gd(C10H9N2O4)3 H2O
According to TG-DTG experiment data of the complexes,
apparent activation energies of the second thermal decompo- squares method fitting in the computer. The decomposition
sition stage were calculated by Kissinger’s method.[18]
peak temperature value Tp, slope (2ER), the linear correlation
Apparent activation energies E were calculated by least-
The different heating rate (b) and corresponding peak temp- coefficient r and apparent activation energies E are listed in
erature value (Tp) on DTG curve were substituted into Eq. Table 6.
(1):[17]
The plot of apparent activation energies of the second
thermal decomposition stage for the six complexes versus
atomic number of the corresponding rare earth element is
shown in Figure 2. It can be seen from Figure 2 that the corre-
lation between the apparent activation energies and the rare
earth atomic number is monotonic increasing and divided
into two curves, as if the front two groups of “quadripartite
effect”.[19]
d lnðb=TP2Þ
dð1=TPÞ
E
R
¼ ꢂ
Viz.
E P
lnðb=Tp2Þ ¼
þ C
ð1Þ
R TP
TABLE 6
The second decomposing activate energy of complexes
21
21
.
.
E/kJ mol
Complexes
La(C10H9N2O4)3 2H2O
b/K min
TP/K
E/R
r
.
5.00
10.00
15.00
5.00
592.45
599.15
602.75
590.65
594.75
598.65
592.75
595.85
599.25
594.65
597.55
599.95
594.65
597.55
598.55
596.35
597.35
599.5
210.515
20.9995
87.43
113.0
140.6
168.7
231.1
273.2
.
Ce(C10H9N2O4)3 H2O
213.592
216.911
220.291
227.786
232.860
20.9910
20.9848
20.9999
20.9916
20.9332
10.00
15.00
5.00
.
Nd(C10H9N2O4)3 H2O
10.00
15.00
5.00
.
Sm(C10H9N2O4)3 H2O
10.00
15.00
5.00
.
Eu(C10H9N2O4)3 H2O
10.00
15.00
5.00
.
Gd(C10H9N2O4)3 H2O
10.0
15.00

SIX NEW RARE EARTH COMPLEXES
95
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.
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La, Ce, Nd, Sm Eu, Gd), three carboxyls in each complex are
coordinated in the form of one dentate. The lanthanide ion is
coordinated by three N atoms (C55N) and seven O atoms
from one water and three tridentate ligands that coordinated
via keto-form to form three stable five-membered rings. All
the complexes exhibit excellent fluorescence properties at
408 nm. The thermal decomposition process of the complexes
can be divided into three stages. The apparent activation
energies increase along with rare earth atomic number
increases, showing that the thermal stability of the complexes
has the same enhancing tendency as rare earth atomic
number increases. The correlation between the apparent acti-
vation energies and the rare earth atomic number shows a
grouping effect of the lanthanide elements.
12. Chen, F. Y.; Cao, W. K.; Liu, X. R.; Peng, k.; He, S. Y.;
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.
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.
3H2O C6H6. Chin. J. Chem. 2006, 24, 711.
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