STUDIA UNIVERSITATIS BABES-BOLYAI, PHYSICA, SPECIAL ISSUE, 2003
SPECTROSCOPIC INVESTIGATION OF Cu(II) MOLECULAR COMPLEXES
OF ATENOLOL and METOPROLOL TARTRATE
Felicia Pop-Gozman1, I. Bratu2, O. Cozar3 and M. Bojita4
1
University of Oradea, Faculty of Pharmacy, 1 Armatei
Romane st., Oradea, Romania
2
National R&D Institute of Isotopic and Molecular
Technologies, P.O. Box 700,
R-3400 Cluj-Napoca 5, Romania
3
'Babes-Bolyai' University, 1 Kogalniceanu st., ClujNapoca, Romania
4
'Iuliu Hatieganu' University of Medicine anf Pharmacy,
4 Clinicilor st., Cluj-Napoca, Romania
Abstract
FT-IR spectroscopic data of atenolol and its copper complex suggest that
NH2 and carboxyl groups are involved in the coordination of the metal
ion.
Powder EPR spectra of these complexes show a square-planar symmetry
around the metal ion with a CuN2O2 chromophore in xOy plane. A small
tetragonal-octahedral distortion is present in the case of CuATE
compound.
Introduction
Atenolol (C14H22N2O3) and metoprolol tatrate (C15H25NO3)2.C4H6O6 molecules are
the most frequently used drugs in the treatment of cardiovascular diseases. In the
last few years some molecular copper complexes of different drugs
(cardiovasculares, antiinflammatories) are used because their activity is enhanced.
For a better understanding of their activity, structural investigation [1-10] by
different spectroscopic methods (FT IR and EPR spectroscopy) was done.
Experimental
Molecular complexes of atenolol (ATE) and metoprolol tatrate (MET) with Cu(II)
were obtained on going from the starting salts (sodium benzoate and copper
sulphate) by co-precipitation procedure. After drying, the powder complexes were
analysed by classical KBr pellet technique with an EQUINOX 55 Bruker FT IR
spectrometer in the 400 - 4000 cm-1 spectral domain. The EPR spectra of the
samples in the powder form were registered in the X band using an ADANI-USA
spectrometer.
Results and Discussion
A comparative study of the FTIR spectra of ligands (ATE and MET) and the
corresponding complex, see Figs. 1 and 2, established the molecular groups
involved in the complexation. Analysing the FTIR spectrum of ATE one can see
FELICIA POP-GOZMAN, I. BRATU, O. COZAR AND M. BOJITA
ATE
1.0
A T E - C u ( II)
0
0.8
Absorbance
-1 0 0
-2 0 0
0.6
-3 0 0
-4 0 0
0.4
-5 0 0
-6 0 0
-7 0 0
0.2
-8 0 0
-9 0 0
0.0
4000
3500
3000
2500
2000
1500
Wavenumber / cm
1000
500
-1
Figs. 1: FT IR spectra of ATE and its copper complex
that the frequency of the band at 3351 cm-1 and assigned to NH2 group is shifted to
3441 cm-1 in the spectrum of copper complex; it is possible that some hydrogen
bonds are broken during the complexation process. The band at 1631 cm-1 in the
MET
1.0
Absorbance
0.8
0.6
0.4
0.2
0.0
4000
3500
3000
2500
2000
1500
1000
500
-1
Wavenumber / cm
Fig. 2: FT IR spectra of MET.
FTIR spectrum of ATE, assigned to carbonyl group is shifted to 1602 cm-1 in the
2
INVESTIGATION OF Cu(II) MOLECULAR COMPLEXES, ATENOLOL and METOPROLOL TARTRATE
spectrum of the complex. It is quite evident that the complexation is produced
through this molecular group.
Powder EPR spectra of Cu (II) atenolol (ATE) and Cu (II) metoprolol tarate (MET)
complexes obtained at room temperature exhibit the absorption signals typical of
randomly oriented single state (S=1/2) species having axial symmetry (Fig. 3). The
ground state for paramagnetic electron is dx2-y2 orbital. By comparing the shape of
these EPR spectra with those obtained for others copper complexes with nitrogen
and oxygen ligands we have concluded that the local symmetry around metal ions
is of square-planar type with a CuN2O2 chromofore in the xOy plane [1].
The characteristic EPR parameters for CuATE compound are the following
g // =2.268, g =2.078, A// =165 G and g // =2.268, g =2.095, A// =145 G for
CuMET.
The g // values suggest the presence of a small tetragonal-octahedral distortion in
the case of CuATE compound [10].
A//
g =2.095
g//=2.268
CuMET
2300
2500
2700
2900
3100
3300
3500
3700
3900
Field / G
Fig. 3. Powder EPR spectrum of CuMET at room temperature.
3
FELICIA POP-GOZMAN, I. BRATU, O. COZAR AND M. BOJITA
Conclusions
The FT-IR data obtained for ATE and MET drugs and their copper compounds
suggest that NH2 and carboxyl groups are involved in the complexation
(coordination) of the metal ions.
Powder EPR spectra of these complexes show a square-planar symmetry around
the metal ions with a CuN2O2 chromophore in xOy plane. A small tetragonaloctahedral distortion is present in the case of CuATE compound.
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