The synthesis and characterization of copper(II)-p-aminosalicylate complexes with diamine ligands

Article abstract of DOI:10.1007/s10973-010-1128-7

The complexes were synthesized by the reaction between sodium salt of p-aminosalicylic acid (PAS) and Cu(II) for 1 and corresponding ethylenediamine (en) or its derivatives for 2-6. The complexes were characterized by using elemental analyses, FT-IR, UV-Vis, magnetic moment measurements, and thermal analyses techniques. In complex 1[Cu₂(PA)₄(H ₂O)₂], two Cu(II) ions were found as bridged by four μ-O:O′ p-aminosalicylato (PA) ligands, forming a cage structure, and two aqua ligands to form dinuclear square-pyramidal geometry around Cu(II) ions. In the complexes 2-6, the PA (anionic form of p-aminosalicylic acid) coordinated to Cu(II) ions as monodentate manner by using its oxygen atom of deprotonated carboxylic acid and ethylenediamine derivatives coordinated to the Cu(II) ions in bidentate manner to form mononuclear octahedral complexes [Cu(PA)₂(L)₂] (L = ethylendiamine, N,N- dimethylethylendiamine, N,N′-dimethylethylendiamine, N,N,N′, N′-tetramethylethylendiamine, and 1,3-propanediamine, for complexes 2, 3, 4, 5, and 6, respectively). In all the complexes OH and NH₂ groups of PA ligands were not coordinated to metals.

Full text of DOI:10.1007/s10973-010-1128-7

J Therm Anal Calorim (2011) 103:995–1000
DOI 10.1007/s10973-010-1128-7
The synthesis and characterization of copper(II)–p-aminosalicylate
complexes with diamine ligands
•
•
Murat Tas¸ Seval C¸ amur Yalc¸ın Kılıc¸
Received: 23 July 2010 / Accepted: 25 October 2010 / Published online: 6 January 2011
´
´
Ó Akademiai Kiado, Budapest, Hungary 2011
Abstract The complexes were synthesized by the reac-
tion between sodium salt of p-aminosalicylic acid (PAS)
and Cu(II) for 1 and corresponding ethylenediamine (en) or
its derivatives for 2–6. The complexes were characterized
by using elemental analyses, FT-IR, UV–Vis, magnetic
moment measurements, and thermal analyses techniques.
In complex 1[Cu2(PA)4(H2O)2], two Cu(II) ions were
found as bridged by four l-O:O0 p-aminosalicylato (PA)
ligands, forming a cage structure, and two aqua ligands to
form dinuclear square-pyramidal geometry around Cu(II)
ions. In the complexes 2–6, the PA (anionic form of
p-aminosalicylic acid) coordinated to Cu(II) ions as
monodentate manner by using its oxygen atom of depro-
tonated carboxylic acid and ethylenediamine derivatives
coordinated to the Cu(II) ions in bidentate manner to form
mononuclear octahedral complexes [Cu(PA)2(L)2] (L =
ethylendiamine, N,N-dimethylethylendiamine, N,N0-dim-
ethylethylendiamine, N,N,N0,N0-tetramethylethylendiamine,
and 1,3-propanediamine, for complexes 2, 3, 4, 5, and 6,
respectively). In all the complexes OH and NH2 groups of
PA ligands were not coordinated to metals.
Introduction
Many authors investigated coordination compounds due
to their chemical, biological, environmental, ion-
exchange, and catalytic importance. Recently, consider-
able attention has been devoted to the study of mixed
ligands complexes of metal(II) containing nitrogen donor
ligands [1].
The salicylic acid derivatives are widely used for
treatment of various diseases [2]. 4-aminosalicylic acid (4-
amino-2-hydroxybenzoic acid or p-aminosalicylic acid)
which is a derivative of salicylic acid, also nicknamed
PAS, PASER, Paramycin, or Parasal, has been used as an
anti-tuberculosis drug since the early 1950s. In literature,
there are a lot of knowledge including 4-aminosalicylic
acid (PAS), can also use as a strong pain killer, antipyretic,
reducing the body burden of Mn in manganism, treatment
of inflammatory bowel diseases, ulcerative colitis and
inhibition of CA isozymes [3–10].
Also, the copper complexes especially copper salicylate
complex, are highly effective for anti-inflammatory agents
and shown great potential in the treatment of numerous
chronic diseases, inflammatory diseases, gastrointestinal
ulcers, cancers, epilepsy, and diabetes [11].
Keywords 4-Aminosalicylic acid ꢀ 4-Amino-2-
hydroxybenzoic acid ꢀ p-Aminosalicylic acid ꢀ Mixed
ligand complex ꢀ Copper(II) complexes
In addition to these properties, the metal carboxylate
chemistry has been of great interest in the field of catalysis,
as antifungal agents, enzyme models, or mainly, in the field
of molecular magnetism for their versatile co-ordination
behavior as well as for making metallo-organic frame-
works [12, 13].
Besides, PAS can be used as a carboxylic acid to handle
versatile coordinated complexes, also can be used in
organic synthesis as precursor, because of its NH2, OH, and
COOH substituents. So the PAS is ready for versatile usage
than salicylic acid.
M. Tas¸ (&) ꢀ S. C¸ amur ꢀ Y. Kılıc¸
Department of Chemistry, Faculty of Art and Sciences, Giresun
University, Giresun, Turkey
e-mail: murat.tas@giresun.edu.tr
123

996
M. Tas¸ et al.
The aim of this study is the synthesis and characteriza-
respectively, [9–16]. The IR spectra of the both the com-
plexes except 1 were similar. The broad band at 3574
indicated the aqua ligands in complex 1. The peaks at
3244–3204, 3147, 1614, and 1509 cm-1 were attributed to
NH2, OH, COOa-sym, and COOs-ym vibrations of PA, in
complex 1 (Table 2).
tion of novel mixed ligands PAS complexes with Cu(II) ion.
Results and discussion
The complexes were synthesized by the reaction between
sodium salt of p-aminosalicylic acid (PAS) and Cu(II) for 1
and corresponding ethylenediamine or its derivatives for
2–6. The complexes were characterized with using ele-
mental analyses, FT-IR, UV–Vis, magnetic moment mea-
surements, and thermal analyses techniques. The colors,
yields, magnetic moments, UV–Vis, and elemental analy-
ses data are given in Table 1. The IR and thermal analyses
data are collected in Tables 2 and 3, respectively.
The difference between the COO-asym (masym), and
COO-sym (msym) carboxylate vibrations (D = masym-msym) is
often used to determine the coordination modes of the
carboxylate group [13, 17–20].
The reducing of the difference (D) between COOa-sym
,
and COO-sym vibrations indicated that the bridging biden-
tated manner of PA ligand in complex 1 [17–21]. Similar
dinuclear structure for Cu(II) carboxylate complexes pre-
viously reported [21–25].
In the IR spectra of complexes 2–6, the peaks at 3463–
3349, 3360–3143, 3213–3222, 3037–2844, 1644–1629, and
IR, UV–Vis spectroscopy, and magnetic moment
measurement
1511–1506 cm-1, were attributed to NH2-PA, NH2-Dimen
,
OH-PA, CHaliphatic, C=O?COO-asym and COOs-ym vibrations,
respectively, (Table 2). Seeing of OH peaks in the IR spectra
of the complexes 1–6 indicated the OH protons were not
separated and not bonded to the Cu(II) ions.
The IR spectrum of sodium salt of PAS (PA) showed peaks
at 3400–3328, 3218, 1636, and 1504 cm-1 attributed to
NH2, O–H, C=O?COOs-ym and COOs-ym vibrations,
Table 1 Colors, yields, magnetic moments, UV–Vis, and elemental analyses data of the complexes
Color
MA/g/mol
Yield%
l/BM
d ? d/nm
e/L/mol/cm
Elemental analyses
C%
H%
N%
1
Green
Violet
Deep blue
Blue
786.67
488.00
544.10
544.10
600.21
516.05
88
78
65
70
72
84
2.32
1.23
1.21
1.27
1.52
1.31
572
144
544
4.65
572
9.10
574
5.41
574
8.47
580
5.91
44.38 (44.28)
4.12 (3.97)
5.51 (5.78)
6.34 (6.67)
6.41 (6.67)
7.22 (7.39)
6.09 (6.25)
7.41 (7.12)
C29H31Cu2N4O14
2
44.46 (44.30)
48.62 (48.56)
48.71 (48.56)
52.25 (52.03)
46.71 (46.55)
17.38 (17.22)
15.63 (15.45)
15.54 (15.45)
14.36 (14.00)
16.47 (16.29)
C
18H28CuN6O6
3
C22H36CuN6O6
4
C
22H36CuN6O6
5
Green
Violet
C26H44CuN6O6
6
C20H32CuN6O6
Table 2 The IR spectra data of the sodium salt of PAS (PA–Na) and handled complexes
H2O
NH2-PA
OH
NH2-Dimen
CHaliphatic
COO-asym
COO-sym
1509
D
PA–Na
–
3393–3330
3244–3204
3459–3354
3463–3371
3446–3364
3446–3358
3459–3349
3226
3147
3235
3213
3226
3239
3222
–
1638
1614
1644
1636
1630
1636
1629
129
100
133
127
124
127
120
1
2
3
4
5
6
3574
1514
1511
1509
1506
1509
1509
–
–
–
–
–
3296–3143
3360–3340
3156
2970–2845
3037–2844
3002–2808
3010–2848
2958–2857
–
3318–3261
123

The synthesis and characterization of copper(II)–p-aminosalicylate
997
Table 3 The thermal analyses data of the complexes
Stage 1
Stage 2
Stage 3
Total mass
loss residue
1
2
3
4
5
6
Temperature/°C
DTAmax/°C
Mass loss%
30–103
68
103–380
257, 292
73.5
Found: 79.3
Calc.: 79.8
CuO
5.5
Temperature/°C
DTAmax/°C
Mass loss%
70–137
106
137–257
187, 213
60.1
257–587
Found: 83.2
Calc.: 83.7
CuO
505
6.9
16.7
Temperature/°C
DTAmax/°C
Mass loss%
100–152
137
152–229
175
229–510
Found: 86.3
Calc.: 85.4
CuO
419
2.7
49
34.9
Temperature/°C
DTAmax/°C
Mass loss%
61–125
88
125–240
190, 203
49.3
240–540
Found: 88.6
Calc.: 88.3
Cu
431
5.5
33.8
Temperature/°C
DTAmax/°C
Mass loss%
30–80
70
80–197
180
197–495
Found: 90.0
Calc.: 89.4
Cu
228, 263, 301, 355, 406
2.2
26.1
62.1
Temperature/°C
DTAmax/°C
Mass loss%
64–138
110
138–260
171, 175, 199
49.3
260–564
443, 489
23.9
Found: 84.1
Calc.: 84.5
Cu
11.1
The complex 5 which has N,N,N0,N0-tetramethyle-
for complex 1 and spin-only magnetic moments acceptable
for other complexes.
thylenediamine (Ten) as a secondary ligand, was a key to
understand of coordination manner of PA ligand in the
complexes. The Ten ligand had no NH or NH2 parts, so it
does not cause overlapping of the peaks for NH2-PAor OHPA
of PA ligand. In the IR spectra of complex 5, the peaks of
NH2-PA shifted to higher frequencies and became clear and
the OHPA peak showed small shift indicating the NH2 and
OH groups of PA were not coordinated to metals. The IR
spectra of the other complexes were similar with the com-
plex 5 and the additional peaks of NH2 for 2, 3, 6 and NH
peak for 4 were seen in their spectra indicating the en
ligands or its derivatives were in the coordination spheres.
The difference (D) between the masym and msym fre-
quencies of PA was 129 cm-1 and the small shifts were
found for D values were in the range 120–133 cm-1 for
complexes 2–6. These results indicated that the carboxylate
group participated in the coordination with the metal ions
in unidentate manner in complexes 2–6 [17–21] (Table 2).
The room temperature spin-only magnetic moments
were found as 2.32 for complex 1 which was suitable with
square-planar geometry around Cu(II) centers of dinuclear
complex and between 1.21 and 1.52 BM for complexes
2–6 which were suitable with octahedral geometry around
the Cu(II) centers of mononuclear complexes [26]
(Table 1). The lower magnetic moment values indicate
anti-ferromagnetic coupling between the two Cu(II) centers
The UV–Vis spectra of an ethanol solution of the
complexes had one band. The absorption coefficients were
in the range of approximately 5–9 for complexes 2–6 and
144 for complex 1 which consistent with octahedral and
square-planar environments for a d9 electron configuration
(Table 1) [26]. Based on the lights of these overall results,
the suggested structures of the complexes are shown in
Figs. 1 and 2.
Thermal analyses
The thermal analyses data of the complexes are given in
Table 3. All the complexes undergo complete endothermic
OH
HO
OH2
Cu
O
O
H2N
NH2
O
O
O
O
Cu
H2N
NH2
O
O
OH2
HO
OH
Fig. 1 The suggested structure of complex 1
123

998
M. Tas¸ et al.
100.0
80.0
60.0
50.0
5.000
4.000
3.000
2.000
1.000
0.000
OH
O
N
N
N
N
0.0
H2N
Cu
O
O
–50.0
NH2
O
40.0
20.0
0.0
HO
–100.0
Ethylenediamine (en) for complex 2
N,N-Dimethylethylenediamine (NNen) for complex3
N,N'-Dimethylethylenediamine (NN'en) for complex 4
N,N,N',N'-Tetramethylethylenediamine (Ten) for complex 5
1,3-Propanediamine (Pen) for complex 6
–150.0
=
N
N
100.0 200.0 300.0 400.0 500.0 600.0 700.0
Temperature/°C
Fig. 4 Thermal analyses curves of complex 2
Fig. 2 The suggested structure of complexes 2–6
100.0
100.0
50.0
and exothermic decompositions. Complex 1 undergoes
complete decompositions in two stages (Fig. 3). The first
stage occurred at 30–103 °C (DTAmax: 68 °C) and were
corresponded to an endothermal removal of two water
ligands (calc.: 4.6%, found: 5.5%). In the second stage,
between 103 and 380 °C the organic parts of the PA was
lost by highly exothermic reaction. Thus, the total of 79.3%
of the original mass of complex 1 was removed to form
CuO (calc.: 79.8%) during thermolysis, which was con-
sistent with the proposed structure (Fig 1).
2.000
80.0
1.500
60.0
0.0
–50.0
1.000
40.0
–100.0
–150.0
0.500
20.0
0.000
0.0
100.0 200.0 300.0 400.0 500.0 600.0 700.0
Temperature/°C
Fig. 5 Thermal analyses curves of complex 3
The complexes 2–6 were decomposed with endothermic
and exothermic reactions in three stages (Figs. 4, 5, 6, 7,
and 8). Averagely, the complexes were stable until around
100 °C and it was not easy to reasonable explain without
mass spectra of evolution fragments during thermal
decompositions. The complexes formed CuO and metallic
Cu as final products for 2–3 and 4–6, respectively. The
increasing of carbon numbers may consume the amount of
oxygen in the static air atmospheres to result metallic Cu
around 500 °C as final products for 4–6.
1.600
100.0
80.00
60.00
40.00
20.00
1.400
80.0
1.200
1.000
60.0
0.800
0.600
0.400
0.200
0.000
40.0
0.00
–20.00
–40.00
20.0
0.0
The overall weight loss and residue weights agree well
with the proposed structures (Fig. 2).
100.0 200.0 300.0 400.0 500.0 600.0 700.0
Temperature/°C
Fig. 6 Thermal analyses curves of complex 4
300.0
200.0
100.0
80.0
60.0
100.0
1.200
60.00
40.00
20.00
0.00
1.500
1.000
0.500
0.000
1.000
80.0
100.0
0.0
0.800
60.0
0.600
–100.0
–200.0
–300.0
40.0
20.0
0.0
40.0
0.400
–20.00
0.200
20.0
–40.00
0.000
0.0
100.0 200.0 300.0 400.0 500.0 600.0 700.0
100.0 200.0 300.0 400.0 500.0 600.0 700.0
Temperature/°C
Temperature/°C
Fig. 3 Thermal analyses curves of complex 1
Fig. 7 Thermal analyses curves of complex 5
123

The synthesis and characterization of copper(II)–p-aminosalicylate
999
100.0
1.000
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10.00
1.800
0.600
0.400
0.200
0.000
80.0
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