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Structure of Free Radical inγ-Irradiated 21-Hydroxyprogesterone (Deoxycorticosterone) Single Crystals. ESR/ENDOR and DFT Studies

100%

Szyczewski A., Pietrzak J., Möbius K.

Acta Physica Polonica A

2005

vol. 108

issue 1

119-126

Single crystals of 21-hydroxyprogesterone have been γ-irradiated at 295 K and studied using X-band ESR and ENDOR. The structure of the one type radical has been determined on the basis of an analysis of the angular variation of the spectra. This radical is formed by abstraction of the hydrogen atom from the C(6) carbon, while the unpaired electron is delocalised onto the system O(3), C(3), C(4), C(5), C(6). Hyperfine splitting constants and unpaired electron density distribution have been calculated for the proposed radical structure by using the Gaussian98 set of programs. The results are in very good agreement with the experimental data. The effect of the hydrogen bond and biological activity on the anisotropy of α-hyperfine splitting tensor have also been discussed.

EPR Study of Gadolinium(III) Complexes with Heteropolyanions: [Gd(SiW_{11}O_{39})_{2}]^{13-} and [GdP_{5}W_{30}O_{110}]^{12-}

76%

Szyczewski A., Lis S., Kruczyński Z., Pietrzak J., But S., Elbanowski M.

Acta Physica Polonica A

1996

vol. 90

issue 2

345-351

The gadolinium complexes: [Gd(SiW_{11}O_{39})_{2}]^{13-} [I] and [GdP_{5}W_{30}O_{110}]^{12-} (Gd-encrypted Preyssler anion) [II] have been chosen for EPR study. This study is a continuation of our recent investigation related to solid gadolinium complexes: β-diketonates and aminopolycarboxylates. The EPR spectra of the Gd-polyoxometalates studied provide much better resolution than those recently studied. The spectra of Gd-polyoxometalates containing 1.7 to 2.5% of Gd(III) do not require an additional computer processing for correct interpretation. It is on the contrary to the β-diketonates and polyaminocarboxylates (with the content of Gd(III) 22-33%) for which the use of the RKU computer program (based on Fourier transform) was necessary in order to enhance the spectra resolution thus improving their correct interpretation. The EPR spectra obtained for the compounds I and II markedly differ from the U-spectrum characteristic of Gd(III) in glasses. 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 and II seem to be related to a various hydration degree.

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2 Acta Physica Polonica A

1 2005

1 1996

2 Pietrzak J.

2 Szyczewski A.

1 But S.

1 Elbanowski M.

1 Kruczyński Z.

1 Lis S.

1 Möbius K.

Search results

Structure of Free Radical inγ-Irradiated 21-Hydroxyprogesterone (Deoxycorticosterone) Single Crystals. ESR/ENDOR and DFT Studies

EPR Study of Gadolinium(III) Complexes with Heteropolyanions: [Gd(SiW_{11}O_{39})_{2}]^{13-} and [GdP_{5}W_{30}O_{110}]^{12-}