Zdzislaw Kruczynski

Variations in the free radical scavenging activity of Ginkgo biloba L. leaves in the period of complete development of green leaves to fall of yellow ones

The scavenging effect against the DPPH radical has been determined for Ginkgo leaves in the growing season from 28 June to 28 October using an EPR method. The influence of the storage time on the leaves scavenging activity has also been assayed. The antioxidant properties decreased as the storage time increased.

EPR study of sandwiched gadolinium(III) complexes with polyoxometalates

Abstract The gadolinium-sandwiched complexes with polyoxometalates: [GdW 10 O 36 ] 9− , [Gd(SiW 11 O 39 )] 13− and [Gd(SiW 11− x Mo x O 39 ) 2 ] 13− (where x =2, 5, 8) have been chosen for electron paramagnetic resonance (EPR) study. The EPR spectra obtained for the ‘pure’ Gd(III) compounds (not doped) markedly differ from the U-spectrum characteristic for Gd(III) in glasses. This report shows how some of the spectroscopic properties of lanthanide(III) complexes can be studied with EPR through examples of Gd 3+ ion interactions with polyoxometalates. Analysis of EPR spectra obtained at X- (9.4 GHz) and Q- (35 GHz) bands provide estimates of zero-field splitting (ZFS) parameter D , a linewidth of the central line and effective g -factors for particular EPR lines. An interesting pattern showing a linear dependence of the D -value on the content of number x of Mo atoms, in the [Gd(SiW 11− x Mo x O 39 ) 2 ] 13− structure, was obtained and an attempt to explain it was made.

Electron Paramagnetic Resonance study of chosen gadolinium(III) sandwiched- and encapsulated-polyoxometalate complexes

Abstract The gadolinium(III) complexes with polyoxometalates were studied using X-band Electron Paramagnetic Resonance (EPR) spectroscopy. We selected the following sandwiched complexes: Gd(SiW 11 O 39 ) 2 13− [ I ], GdW 10 O 36 9− [ II ], Gd(P 2 W 17 O 61 ) 2 17− [ III ], and encrypted [GdSb 9 W 17 O 86 ] 16− [ IV ], [GdP 5 W 30 O 110 ] 12− [ V ]. The EPR spectra obtained for the compounds I – III and IV – V differ markedly from the U-spectrum characteristic for Gd(III) in glasses. The values of the zero-field splitting parameter D for both kind of complexes studied have been estimated. Taking into account the spin-hamiltonian calculations, the existence of Gd(III) ion in two different surroundings, in a strong crystal field of rhombic symmetry and in a weak crystal field, is observed. The differences observed between the case I – III and IV – V seems to be related to a various coordination of the Gd(III) ion and its hydration degree. Our study shows a relation between the presence of particular g -values of the spectral lines and the number of the inner-sphere water molecules as well as the type of the Gd(III) complex (sandwiched and/or encrypted) in solid.

Continuous microwave saturation of EPR spectra of melanin complexes at different temperatures

Continuous microwave saturation of EPR spectra of melanin complexes at different temperatures Paramagnetic centers in DOPA-melanin and complexes of DOPA-melanin with netilmicin and Cu(II) were studied by the use of an X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy. Measurements of continuous microwave saturation of EPR spectra at temperatures: 125 K, 175 K, 225 K, 275 K, were performed. Homogeneous broadening of all the examined EPR spectra was observed. EPR spectra of DOPA-melanin-Cu(II) complexes saturated at higher microwave powers than the others tested melanin samples. Fast spin-lattice relaxation exists in DOPA-melanin-Cu(II) complexes. Slow spin-lattice relaxation processes exist in melanins paramagnetic centers of DOPA-melanin and its complexes with netilmicin, and its complexes with both netilimicin and Cu(II). EPR spectra of all the tested samples saturated at higher microwave powers with increasing of the measuring temperature. Faster spin-lattice relaxation processes occurs in DOPA-melanin and its complexes with netilmicin and Cu(II) at higher temperature.

Spin traps in the detection of free radicals in the blood of patients with ischemia

Spin traps in the detection of free radicals in the blood of patients with ischemia Electron Paramagnetic Resonance and a nitrosobenzene spin trap were used to investigate free radicals in the human blood after angioplasty treatment. The nitrosobenzene anion radical was determined using EPR measurements and quantum-mechanical calculations. Differences were observed in the concentration of free radicals before and after angioplasty treatment. These results were compared with myocardium damage parameters (CPK, MB and TnT).

Free radicals in a conglomerate of peripheral blood with a spin trap investigated by the EPR method before and after angioplasty treatment

Free radicals in a conglomerate of peripheral blood with a spin trap investigated by the EPR method before and after angioplasty treatment The Electron Paramagnetic Resonance (EPR) was used to investigate free radicals in the peripheral blood of patients subjected to angioplasty treatment. To detect these free radicals, a nitrosobenzene spin trap was used in this experiment. The EPR spectra of the blood with a spin trap conglomerate was measured at room temperature and at 170 K. To confirm the kind of free radicals in the conglomerate blood-spin trap, simulation and quantum-chemical calculations were made, and the conglomerate spin trap with ascorbic acid was measured. Two different types of radicals, one at room temperature and the other in a frozen sample of blood, were found.