Thermal behavior of some new complexes bearing ligands with polymerisable groups

Article abstract of DOI:10.1007/s10973-005-7176-8

This paper reports the investigation of the thermal stability of a series of new complexes with mixed ligands of the type M(dipy)(C₃H ₃O₂)₂(H₂O)_y ((1) M: Mn, y=1; (2) M: Ni, y=2; (3) M: Cu, y=1; (4) M: Zn, y=2; dipy: 2,2'-dipyridine and C₃H₃O₂ is acrylate anion). The thermal behaviour steps were investigated. The thermal transformations are complex processes according to TG and DTG curves including dehydration, oxidative condensation of acrylate and thermolysis processes. The final products of decomposition are the most stable metal oxides.

Full text of DOI:10.1007/s10973-005-7176-8

Journal of Thermal Analysis and Calorimetry, Vol. 85 (2006) 2, 285–288
THERMAL BEHAVIOR OF SOME NEW COMPLEXES BEARING
LIGANDS WITH POLYMERISABLE GROUPS*
M. Badea1**, R. Olar1, D. Marinescu1 and G. Vasile2
1University of Bucharest, Faculty of Chemistry, Department of Inorganic Chemistry, 90–92 Panduri St., 050663 Sector 5
Bucharest, Romania
2University of Agronomical Sciences and Veterinary Medicine, Department of Agrochemistry, Bd. Marasti 59, Bucharest, Romania
This paper reports the investigation of the thermal stability of a series of new complexes with mixed ligands of the type
M(dipy)(C3H3O2)2(H2O)y ((1) M: Mn, y=1; (2) M: Ni, y=2; (3) M: Cu, y=1; (4) M: Zn, y=2; dipy: 2,2’-dipyridine and C3H3O2 is
acrylate anion). The thermal behaviour steps were investigated. The thermal transformations are complex processes according to
TG and DTG curves including dehydration, oxidative condensation of acrylate and thermolysis processes. The final products of de-
composition are the most stable metal oxides.
Keywords: acrylate, complexes, formate, thermal stability
Introduction
well [11]. Some complexes behave as inhibitors for
different types of microorganisms and also show an
interesting thermal behaviour [10–12].
The polymeric materials with metals particles or metal-
lic ions have opened up a new research field of current
interest due to the practical importance of the obtained
products, which exhibit unusual properties. Recent de-
velopments in polymer chemistry revealed that com-
plexes with mixed ligands such as aromatic amine and
unsaturated polymerisable compounds are suitable for
synthesis of these types of materials. The interest for
these compounds grew up according with its character-
istics such as catalytic activity, unusual magnetic and
electro-physical behaviour as well as biological and
medical applications for tissue engineering, implanta-
tion of medical devices, dentistry, bone repair, etc.
[1–3]. Recent studies have evidenced that compounds
with polymerisable ligands suffer interesting thermal
transformation that generate in the polymeric matrix
metal particles with different sizes [4].
Recently, we have obtained new complexes
starting from acrylate and 2,2’-bipyridine [13]. We
report here the thermal behaviour of these new com-
plexes of the type M(dipy)(C3H3O2)2(H2O)y that rep-
resent the intermediate products in the synthesis of
polymeric materials. Thermogravimetric analysis was
performed for determining the range of stability of
these complexes.
Experimental
All reagents were of commercial analytical quality
and have been used without further purification. The
new complexes were synthesised and previously
characterised by chemical analysis, electronic, IR and
EPR spectra. The redox behaviour was characterised
by voltammetric study and the biological assay were
performed by microdilution method [13]. The chemi-
cal analysis and IR spectral data were used in order to
confirm the nature of some intermediates and also the
final products. Chemical analysis of carbon, nitrogen
and hydrogen has been performed using an EA 1110
analyzer. Manganese, nickel, copper and zinc were
determined gravimetrically in the laboratories of
Inorganic Chemistry Department.
This kind of species with biologic activity and
polymerisable ligands are studied more and more
lately in order to include them into biodegradable
nanospheres which allow controlled release, better
specificity, greater stability and slower excretion rates
of the active agent. Control release of the active agent
is made by diffusion from the nanospheres or
hydrolytic/enzymatic cleavage from the polymer car-
rier [5]. For complex compounds with ammine deriv-
atives, the biologic activity such as antimicrobial, an-
tiviral has been already evidenced [6–9].
IR spectra were recorded in KBr pellets with a
Bio-Rad FTIR 135 spectrometer in the range 400–
4000 cm–1.
We succeeded to obtain this type of complexes
using acrylate [10] and also with mixed ligands as
*
Presented at MEDICTA Conference 2005, Thessaloniki, peer reviewed paper.
Author for correspondence: e_m_badea@yahoo.com; badea.elena@unibuc.ro
**
1388–6150/$20.00
Akadémiai Kiadó, Budapest, Hungary
Springer, Dordrecht, The Netherlands
© 2006 Akadémiai Kiadó, Budapest

BADEA et al.
The heating curves (TG, DTA and DTG) were re-
coli). The values of minimum inhibitory concentration
revealed for complex (1) a very good activity vs. Pseu-
domonas aeruginosa, Staphylococcus aureus, Salmo-
nella enteridis, Listeria monocytogenes [13].
corded in a static air atmosphere using a MOM (Hun-
gary) derivatograph, type Paulik–Paulik–Erdey, with a
sample mass of 100 mg over the temperature range of
20–1000ºC, using a heating rate of 10°C min–1.
The main objective of this paper was to analyse the
thermal behaviour of the complex species with biologic
activity in order to acquire a polymeric fashion for them.
The results concerning the thermal decomposi-
tion/degradation of the new complexes are presented
as it follows.
Results and discussion
The following solid compounds have been studied re-
garding of their thermal behaviour:
TG, DTG and DTA curves corresponding to the
complex (1) heated in the 20–1000°C temperature
range are presented in Fig. 1.
Mn(C10H8N2)(C3H3O2)2(H2O)
Ni(C10H8N2)(C3H3O2)2(H2O)2
Cu(C10H8N2)(C3H3O2)2(H2O)
Zn(C10H8N2)(C3H3O2)2(H2O)2
(1)
(2)
(3)
(4)
Thermal analysis has confirmed the first step of
compound transformation as an endothermic elimina-
tion of water molecules. The reaction proceeds with a
maximum rate at 135ºC. The second step, which is
exothermic, is not a single process (according to DTG
curve) but consists in two processes. During this step
the oxidative transformation of acrylate ion leads to
formate anion, followed by the oxidative degradation
of this intermediate leading to MnO2.
These compounds were obtained in two steps.
First, metallic acrylate from the reaction of metal car-
bonate with acrylic acid in aqueous solution was ob-
tained and then an ethanolic solution of 2,2’-bipyridine
was added.
The third step corresponds to the MnO2 decom-
position and Mn2O3 formation as the final product.
It is important to mention that the physico-chem-
ical studies had evidenced, that with the Cu(II) excep-
tion that adopts a square pyramidal stereochemistry,
the other metallic ions have an octahedral surround-
ings. In all complexes the 2,2’-bipyridine acts as che-
late while the acrylate acts as unidentate ligand in all
complexes except for complex (2) where it is found as
chelate. All the compounds contain water molecules
as indicated the IR spectra and confirmed the thermal
decomposition.
The
thermal
decomposition
of
Ni(C10H8N2)(C3H3O2)2(H2O)2 (2) occurs in three,
well-defined steps. The first step, which is endother-
mic, corresponds to the loss of water molecules. The
resulted anhydrous compound is stable in a wide
range of temperature. The second step corresponds
to an oxidative condensation of acrylic acid and the
degradation of the residual organic part follows as a
third step. This step is complex being an overlap of
at least three oxidative processes.
Antibacterial activity of the complexes has been
carried out vs. Gram positive and Gram negative, refer-
ence and clinical strains (Pseudomonas aeruginosa,
Staphylococcus aureus, Salmonella enteridis, Listeria
monocytogenes, Candida albicans and Escherichia
The
Cu(C10H8N2)(C3H3O2)2(H2O) (3) is similar to that of
Ni(C12H8N2)(C3H3O2)2(H2O)2. TG, DTG and DTA
thermal
decomposition
of
Table 1 Thermal behaviour data (in static air atmosphere) for the acrylate complexes
Complex
Step
Thermal effect
Temperature interval/°C
Δmexp/%
Δmcalc/%
1
2
3
endothermic
exothermic
endothermic
105–160
160–300
4.68
71.56
2.50
4.85
71.69
2.15
Mn(C10H8N2)(C3H3O2)2(H2O)
500–640
residue (Mn2O3)
21.26
21.31
1
2
3
endothermic
exothermic
endothermic
130–200
200–350
9.32
13.14
58.68
18.86
9.16
13.23
58.54
19.07
Ni(C10H8N2)(C3H3O2)2(H2O)2
Cu(C10H8N2)(C3H3O2)2(H2O)
Zn(C10H8N2)(C3H3O2)2(H2O)2
350–580
residue (NiO)
1
2
3
endothermic
exothermic
endothermic
160–215
265–330
4.37
14.06
60.31
21.26
4.74
13.70
60.61
20.95
330–540
residue (CuO)
1
2
3
endothermic
exothermic
endothermic
110–150
150–310
8.92
13.32
57.48
20.28
9.02
13.03
57.64
20.30
310–650
residue (ZnO)
286
J. Therm. Anal. Cal., 85, 2006

COMPLEXES WITH POLYMERISABLE GROUPS’ LIGANDS
Fig. 1 TG, DTG and DTA curves of
Fig. 2 TG, DTG and DTA curves of
Mn(C10H8N2)(C3H3O2)2(H2O)
Cu(C10H8N2)(C3H3O2)2(H2O)
curves corresponding to the complex (3) heated in the
20–1000°C temperature range are presented in Fig. 2.
During the first step the water molecule loss oc-
curs. Considering the higher temperature correspond-
ing to the dehydration process, it could be assumed
that the water molecule is coordinated [14]. The other
two exothermic steps correspond to acrylate to
formate conversion and to oxidative degradation of
the formed compound respectively. The final product
at 540ºC is copper oxide.
that, in all cases, the existence of an intermediate step
corresponds to the formation of metallic formates.
The formation of the complexes with formate at
a temperature that decreases (Ni>Cu>Zn) could be
correlated with the increasing preference of the M(II)
for tetrahedral stereochemistry.
In all the cases, the final residue is the most stable
metallic oxide, as powder X-ray diffraction indicated.
Acknowledgements
In the case of complex (4) the thermal decompo-
sition occurs similar with (2) and (3) meaning the
complex dehydration followed by the oxidative deg-
radation of organic part. The final residue obtained at
720ºC is zinc oxide.
The MATNANTECH National Romanian Research Program
403(204)/2004 financially supported this study.
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Received: August 1, 2005
MEDICTA 2005
DOI: 10.1007/s10973-005-7176-8
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J. Therm. Anal. Cal., 85, 2006