Synthesis and characterization of mononuclear copper (II) complex with 5,5'-dihydroxy-2,2'-[1,1'-(propane-1,3-diyldioxydinitrilo)dimethylidyne]diphenol

Article abstract of DOI:10.14233/ajchem.2013.15634

Copper(II) complex [Cu(H₂L)]·CH₃CH ₂OH·0.5H₂O has been synthesized by the reaction of copper(II) acetate monohydrate with 5,5'- dihydroxy-2,2'-[1,1'-(propane-1,3- diyldioxydinitrilo)dimethylidyne]diphenol in anh

Full text of DOI:10.14233/ajchem.2013.15634

Asian Journal of Chemistry; Vol. 25, No. 16 (2013), 9365-9367
http://dx.doi.org/10.14233/ajchem.2013.15634
Synthesis and Characterization of Mononuclear Copper(II) Complex with
,5'-Dihydroxy-2,2'-[1,1'-(propane-1,3-diyldioxydinitrilo)dimethylidyne]diphenol
5
*
YU-HUA YANG, JIAO-LONG MENG, GANG LI , LI-SHA ZHANG, XIN-YING ZHANG and ZHENG-KUN WANG
School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou 730070, P.R. China
Corresponding author: E-mail: li_gang78@126.com
Received: 15 April 2013;
*
(
Accepted: 25 September 2013)
AJC-14180
2 3 2 2
Copper(II) complex [Cu(H L)]·CH CH OH·0.5H O has been synthesized by the reaction of copper(II) acetate monohydrate with 5,5'-
dihydroxy-2,2'-[1,1'-(propane-1,3-diyldioxydinitrilo)dimethylidyne]diphenol in anhydrous ethanol medium and characterized by elemental
analyses, molar conductance, IR spectra, UV-visible spectra and TG-DTA analyses.
Key Words: Cu(II) complex, Salen-type bisoxime ligand, Synthesis.
apparatus made in Beijing Taike Instrument Limited Company
and the thermometer was uncorrected.
Preparation of 5,5'-dihydroxy-2,2'-[1,1'-(propane-1,3-
INTRODUCTION
The Cu(II) complexes with salen or salen-type bisoxime
ligands are extensively studied due to their ease of prepa-
ration and structural variety. Salen and its derivatives are very
important as versatile ligands, they can accommodate one, or
more metal centers to form complexes with interesting prop-
4
diyldioxydinitrilo)dimethylidyne]diphenol (H L): Synthetic
route to salen-type bisoxime compound H L is shown in Fig. 1.
4
O
O
C
O
C
1
C
erties and applications . These complexes have been found to
2
possess effective activities including catalysis , medical
Br
Br
N OH
N O O N
2
rt, 75 h, DMF, Et
3
N
3
imaging , inorganic biochemistry , thin films and optical
4
5
C
O
C
C
O
6
materials . Herein, we report on the synthesis and characteri-
O
zation of Cu(II) complex [Cu(H
2 3 2 2
L)]·CH CH OH·0.5H O with
CHO
OH
salen-type bisoxime ligand, 5,5'-dihydroxy-2,2'-[1,1'-(propane-
1
O
N
O
2
,3-diyldioxydinitrilo)dimethylidyne]diphenol (H
4
L).
N
OH
NH
2 2 2
NH ·H O
H N O O NH2
OH HO
EXPERIMENTAL
2
Ethanol
95% Ethanol, Ar
HO
OH
2
,4-Dihydroxybenzaldehyde (≥ 99.0 %) was purchased
H L
4
from Alfa Aesar and used without further purification.
Copper(II) acetate monohydrate (≥ 99.0 %) was purchased
from Shanghai Zhenxin Reagent Factory. The other reagents
and solvents were analytical grade reagents from Tianjin
Chemical Reagent Factory. C, H and N analyses were carried
out with a GmbH VariuoEL V3.00 automatic elemental
analyzer. Elemental analysis for Cu was detected by an IRIS
ER/S·WP-1 ICP atomic emission spectrometer. IR spectra were
recorded on aVERTEX70 FT-IR spectrophotometer using KBr
pellets. UV-VIS absorption spectra were recorded on a
Fig. 1. Synthetic route to 5,5'-dihydroxy-2,2'-[1,1'-(propane-1,3-
diyldioxydinitrilo)dimethylidyne]diphenol (H L)
4
1,3-Bis(aminooxy)propane was synthesized according to
7
-10
.
an analogous method reported earlier
To an ethanolic solution (4 mL) of 2,4-dihydroxy-
benzaldehyde (138.1 mg, 1 mmol) was added an ethanolic
solution (2 mL) of 1,3-bis(aminooxy)propane (53.2 mg, 0.50
mmol). After the solution had been stirred at 55 ºC for 4 h.
The formed precipitate was separated by filtration and washed
successively with ethanol and ether, respectively. The product
was dried under reduced pressure to obtain 124 mg pale-pink
1
Shimadzu UV-2550 spectrometer. H NMR spectra were
recorded on a Mercury-400BB spectrometer. Melting points
were measured by the use of a microscopic melting point
4
crystalline ligand (H L). Yield, 35.8 %. m.p. 462.5-463.5 K.

9
366 Yang et al.
Asian J. Chem.
1
H NMR (400MHz, DMF-d ) δ: 1.98 (s, 2H), 4.12 (s, 4H),
6
Infrared spectra of the free ligand H
4
L and its Cu(II)
-1
6
.28 (s, 4H), 7.27~7.31 (d, 2H), 8.25 (s, 2H), 9.78 (s, 2H),
.82 (s, 2H).
complex exhibit various bands in 4000-400 cm region. The
IR spectra data of the free ligand H L and its Cu(II) complex
are given in Table-2. It can be seen from the infrared spectra
results, the infrared spectra of the free ligand H L and its Cu(II)
complex have large difference and indicates that Cu(II) and
the free ligand H L formed the new complex.
The characteristic C=N stretching band of the free ligand
9
4
Preparation of Cu(II) complex: A blue solution of
copper(II) acetate monohydrate (20 mg, 0.10 mmol) in
ethanol (2 mL) was added dropwise to a pale-pink solution of
4
H
4
L (34.6 mg, 0.10 mmol) in ethanol (2mL) at room tempe-
4
rature. The colour of the mixing solution turned to brown
immediately. After refluxing and stirring for 3 h, the reaction
mixture was cooled and the resulting precipitate was filtered
off, washed with ethanol/ether (1:4) and ether, respectively
and dried under reduced pressure to obtain 32.6 mg grey crysta-
lline solid. Yield, 70.4 %.
-1
4
H L appears at 1631 cm , while the C=N band of the Cu(II)
-1
complex is observed at 1612.6 cm . TheAr-O stretching band
-1
4
occurs at 1250.7 cm for the free ligand H L, whereas that at
-1
1221.3 cm for the Cu(II) complex. This shifting of C=N and
Ar-O stretching frequency indicate that the M-N and M-O
bonds are formed between the Cu(II) ion and the oxime N and
2
-
10a
RESULTS AND DISCUSSION
the phenolic oxygen atoms of (H
2
L) unit . Meanwhile, a
-1
O-H stretching band of the free ligand H
4
L at 3391.8 cm
disappears in the Cu(II) complex, indicating the oxygen in
A Salen-type bisoxime compound H
4
L and its Cu(II)
complex have been synthesized with good yields and the compo-
sitions are confirmed by elemental analyses, IR, UV-visible
phenolic alcohol of the Cu(II) complex has been deprotonated
-1
and coordinated to the Cu(II) ion. In the 1363.7-1516.3 cm
1
spectra and H NMR data.
region, the observed bands were attributed to aromatic C=C
vibrations. In addition, infrared spectrum of the Cu(II) complex
shows the expected strong absorption band due to ν(O-H) at
The colour, yields and elemental analytical results of the
4
synthesized Salen-type bisoxime compound H L and its Cu(II)
-1
complex are presented in Table-1. The H L is a pale-pink solid,
4
ca. 3309.3 cm , which is the evidence for the existence of
10g
ethanol molecules .
stable in air and soluble in methanol, ethanol, acetone, aceto-
nitrile, DMF and DMSO, slightly soluble in ether and benzene,
insoluble in chloroform, dichloromethane and n-hexane. The
corresponding Cu(II) complex is a grey solid, soluble in
chloroform, DMF and DMSO, insoluble in methanol, ethanol,
dichloromethane, ether, acetone, acetonitrile, benzene and
n-hexane. The molar conductance of the Cu(II) complex at 21
The absorption spectra of H L and its corresponding
4
Cu(II) complex (Table-3) show that the spectrum of the Cu(II)
complex is different from the spectrum of the free ligand H L.
4
The UV-visible spectrum of the ligand H L exhibits two
4
intense peaks at around 278 and 312 nm, The former absorption
peak at 278 nm can be assigned to the π-π* transition of the
benzene rings, while the latter one at 312 nm can be attributed
-
3
2
-1
ºC in 10 mol/L DMF solution is 2.08 S cm mol , indicating
1
1
12
that the Cu(II) complex is non-electrolytes . The elemental
analysis data and the composition of the Cu(II) complex shows
that the elemental analysis data of the Cu(II) complex close to
the theoretical value, prove accurate results. Copper(II)
to the intra-ligand π-π* transition of the C=N bonds .
Compared with the absorption peak of the free ligand H L,
4
the former absorption peak at 286 nm is observed in the Cu(II)
complex, which is bathochromically shifted by 8 nm. This
2–
acetate monohydrate and ligand H L formed 1:1 (M:L) type
4
2
indicates that the coordination of Cu(II) ion with the (H L)
stoichiometric ratio and one complex molecule containing 1
ethanol molecule and 0.5 water molecule. It has quite good
stability in air at room temperature.
unit. Meanwhile, the absorption band at ca. 312 nm disap-
pears from the UV-visible spectrum of the Cu(II) complex,
which indicates that the oxime nitrogen atom is involved in
TABLE-1
COLOUR, YIELDS, ELEMENTAL ANALYSIS AND COMPOSITION OF H L ANDITS Cu(II) COMPLEX
4
Yield
%)
Elemental analysis (%) found (calcd.)
Compound
m.f. (m.w.)
Colour
(
C
H
N
Cu
–
H4L
C H N O (346.3)
17
Pale-pink
grey
35.8
70.4
59.07 58.96)
49.45(49.29)
5.31(5.24)
5.00(5.01)
7.61(8.09)
5.59(6.05)
18
2
6
[
Cu(H L)]·CH CH OH·0.5H O CuC H N O (462.9)
7.5
13.86(13.73)
2
3
2
2
19 23
2
TABLE-2
IR SPECTRAL DATA FOR H L AND ITS CU(II) COMPLEX (CM )
-1
4
Compound
ν(C=N)
1631.0
1611.6
ν(Ar-O)
1250.7
1221.3
ν(O-H)
3391.8
3309.3
ν(C=C) benzene ring skeleton
1516.3, 1470.7, 1434.6
1537.4, 1446.5, 1363.7
H L
4
[
Cu(H L)]⋅CH CH OH⋅0.5H O
2 3 2 2
TABLE-3
UV SPECTRAL DATA OF H L AND ITS CU(II) COMPLEX
4
First band
Second band
-
C (×10 mol L )
4
-1
Compound
4
-1
ε (×10 L mol cm )
-1
4
-1
-1
ε (× 10 L mol cm )
λmax1 (nm)
278
λmax2 (nm)
312
1
2
H L
4
1.00
1.00
2.45
2.41
1.94
1.09
[
Cu(H L)]·CH CH OH·0.5H O
3
286
355
2
2
2

Vol. 25, No. 16 (2013)
Synthesis and Characterization of Mononuclear Copper(II) Complex 9367
1
3,14
3
4
.
.
J. Tisato, F. Refosco and F. Bandoli. Coord. Chem. Rev., 135-136, 325
1994).
E.C. Niederhoffer, J.H. Timmons and A.E. Martell, Chem. Rev., 84, 137
1984).
coordination to the metal atom . In addition, the new band
observed at 355 nm for the Cu(II) complex is assigned to the
n-π* charge transfer transition from the filled pπ orbital of the
bridging phenolic oxygen to the vacant d-orbital of the Cu(II)
ion, which is characteristic of the transition metal complexes
(
(
5. S.S. Sundari,A. Dhathathreyan, M. Kanthimathi and U.N. Balachandran,
Langmuir, 13, 4923 (1997).
1
0,15
6. S.S. Gu, S.S. Wang,Y.D.Yu and J.Y. Guo, Asian J. Chem., 23, 1241 (2011).
with N
Thermal properties: The thermal stability studies were
performed for the free ligand H L and the Cu(II) complex.
The thermal decomposition process of the Cu(II) complex
compared with the free ligand H L is significantly different.
The ligand H L has a sharp endothermic peak at 190 ºC in the
O
2 2
coordination spheres
.
7
.
S. Akine, T. Matsumoto, S. Sairenjia and T. Nabeshima, Supramol.
Chem., 23, 106 (2011).
4
8. S. Akine, T. Tadokoro and T. Nabeshima, Inorg. Chem., 51, 11478
2012).
S.Akine, S. Hotate andT. Nabeshima, J. Am. Chem. Soc., 133, 13868 (2011).
0. (a) W.K. Dong, Y.X. Sun, C.Y. Zhao, X.Y. Dong and L. Xu, Polyhedron,
9, 2087 (2010); (b) W.K. Dong, Y.X. Sun, Y.P. Zhang, L. Li, X.N. He
(
9
1
.
4
4
2
DTA curve, with no weight loss in the TG curve. And has a
exothermic peak at 240 ºC, weight loss occurs at 230 ºC in the
and X.L. Tang, Inorg. Chim. Acta, 362, 117 (2009); (c) W.K. Dong,
X.N. He, H.B. Yan, Z.W. Lv, X. Chen, C.Y. Zhao and X.L. Tang, Poly-
hedron, 28, 1419 (2009); (d) W.K. Dong, Y.X. Sun, Y.P. Zhang, L. Li,
X.N. He and X.L. Tang, Inorg. Chim. Acta, 362, 117 (2009); (e) W.K.
Dong, C.Y. Zhao, Y.X. Sun, X.L. Tang and X.N. He, Inorg. Chem.
Commun., 12, 234 (2009); (f) W.K. Dong,Y.X. Sun, X.N. He, J.F. Tong
and J.C. Wu, Spectrochim. Acta A, 76, 476 (2010); (g) W.K. Dong, L.
Li, C.F. Li, L. Xu and J.G. Duan, Spectrochim. Acta A, 71, 650 (2008);
4
corresponding TG curve, the ligand H L decomposed comp-
letely by one step. However, the DTA curves of the Cu(II)
complex has endothermic peaks in the range of 88-147 ºC,
with weight loss in the TG curve. The weight loss values of
the Cu(II) complex are 10.3 and 2.2 %, respectively, which
are close to the theoretical values (10.0 and 1.9 %) of losing
corresponding ethanol and water molecules. The Cu(II)
complex has two exothermic peaks at about 230 and 239 ºC,
with apparent weight loss, which are staged oxidative decompo-
sition of the Cu(II) complex. On further heating, the final solid
product is likely to CuO with a residual value of 17.8 % (theore-
tical value, 17.2 %) when the temperature is above 800 ºC.
(
h) W.K. Dong, Y.X. Sun, S.J. Xing, Y. Wang and X.H. Gao, Z.
Naturforsch., 67b, 197 (2012); (i) W.K. Dong, Y.X. Sun, G.H. Liu, L.
Li, X.Y. Dong and X.H. Gao, Z. Anorg. Allg. Chem., 638, 1370 (2012);
(j) W.K. Dong, S.J. Xing, Y.X. Sun, L. Zhao, L.Q. Chai and X.H. Gao,
J. Coord. Chem., 65, 1212 (2012); (k) W.K. Dong andY.J. Ding, Cryst.
Res. Technol. 43, 321 (2008).
1. W.J. Geary, Coord. Chem. Rev., 7, 81 (1971).
1
12. T. Ghosh, B. Mondal, T. Ghosh, M. Sutradhar, G. Mukherjee and
M.G.B. Drew, Inorg. Chim. Acta, 360, 1753 (2007).
1
1
1
3. H.E. Smith, Chem. Rev., 83, 359 (1983).
4. S. Akine, T. Taniguchi and T. Nabeshima, Chem. Lett., 30, 682 (2001).
5. L. Gomes, E. Pereira and B. de Castro, J. Chem. Soc. Dalton Trans.,
1373 (2000).
REFERENCES
1
2
.
.
S. Akine, W.K. Dong and T. Nabeshima. Inorg. Chem., 45, 4677 (2006).
S. Akine, T. Taniguchi and T. Nabeshima. Angew. Chem., Int. Ed., 41,
4
670 (2002).