Andrzej Vogt

Synthesis and characterization of Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes with N-salicydene-o-hydroxymethyleneaniline

Abstract The new Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes with tridentate Schiff base, the product of condensation of o-aminobenzyl alcohol with salicylaldehyde have been synthesized and characterized by elemental analysis, IR, electronic, EPR and Mossbauer spectra, thermal analysis, magnetic susceptibility and molecular weight measurements. Dimeric or polymeric structures for the investigated complexes were proposed. The interaction of the cobalt complex with dioxygen is also described.

Synthesis and characterization of nickel(II), copper(II), manganese(III) and iron(III) complexes with new chiral salen-type ligand |N,N′-bis(3,5-di-tert-butylsalicylidene)-(1R,3S)-1,3-diamine-1,2,2-trimethylcyclopentane|

Abstract The title Schiff base (tBuSalcamH2) obtained by condensation of enantiomerically pure (1R,3S)-1,2,2-trimethyl-1,3-cyclopentanediamine with 3,5-di-tert-butylsalicylic aldehyde was used as a ligand to prepare Ni(II), Cu(II), Mn(III), and Fe(III) 1 : 1 complexes. The compounds were characterized by physicochemical methods. Catalytic activity of (tBuSalcam)MnCl complex was tested in the reactions of single oxygen atom transfer.

Influence of additional ligands on the two-phase epoxidation with sodium hypochlorite catalyzed by (salen)managanese(III) complexes

The two-phase epoxidation of olefins with sodium hypochlorite catalyzed by the salen-type Mn(III) complex 1 was examined in the presence of various additional ligands and 4-dodecyloxypyridine 1-oxide (3) was found as the most effective one. The system 1–3 was studied by conductometry and UV-Vis spectra. The results support the hypothesis that the disproportionation of the dimeric μ-oxo Mn(IV) complex producing an active oxidant is strongly favoured by the presence of 3.

Single-crystal-to-single-crystal Transformation of the Dichloromethane Solvate of the Shiff Base Manganese(III) Complex to a Solvent Free Material

The chloride complex of Mn(III)with an optically active Schiff base derived from3,5-tert-butyl-salicyl aldehyde and(1R,3S)-1,2,2,-trimethylcyclopentane-1,3-diaminecrystallizes as a 1 : 1 solvate (I) withCH2Cl2 and transforms at room temperature toa solvent-free compound (II) without destructionof the crystals. Two X-ray diffraction experimentscarried out on the same crystal at 120 K revealed thatthe guest CH2Cl2 molecules are completelyenclosed in the host matrix and that drasticconformational changes of the complex molecules occurduring removal of solvent. A possible mechanism of thecrystal transformation is disscused. The spectralevidence on association of the metal complex withdichloromethane in solution are demonstrated.

Studies on the cobalt(II)-dipeptide-imidazole system; a new dioxygen carrier

Abstract A series of new mixed cobalt(II) complexes with dipeptide and imidazole, which are dioxygen carriers, was synthesized. The oxygen-free, high-spin octah

The distinctive properties of dioxygen complexes formed in the cobalt(II)-asparagine-OH− systems (in relation to other amino acids and mixed complexes with N-base)

Abstract Dioxygen complexes forming in the Cobalt(II)-asparagine-OH− system in aqueous solution have been investigated by potentiometric, volumeric and spectroscopic methods. In contrast to the corresponding complexes with other bidentate amino acids the asparagine ligand acts at high pH (> 13) as a tridentate ligand, the stability of the oxygen adduct being evidently enhanced thereby. This result has been interpreted as coordination of the side chain amide group deprotonated in presence of the metal, followed by structurally stimulated formation of a monobridged dimer. Additionally it has been proved that in weakly basic solutions the cobalt(II)-α-amino acid active complexes, able to bind dioxygen, are generally of ML3 type (not ML2 as it was assumed up to now).

A new composite absorbing material which is highly effective at the lower frequencies of the VHF range, and its applications

The authors present here a new composite absorbing material, which is highly effective at the lower frequencies of the VHF range. Due to the effectiveness of these materials it is possible to produce flat very thin double-layer absorbers made of ferrite and the new composite material. Such an arrangement shows the unique properties at the lower end of the VHF range - its reflectivity is markedly reduced in comparison to the reflectivity of just ferrite.

Hybrid absorber using new absorbing composites

In this paper, the authors analyse the usefulness of a new composite absorbing material which can be used to make two-layer hybrid absorbers incorporating a ferrite base layer, using the method of homogenization and the transmission line approach. The results acquired show the possibility of obtaining a reflectivity in the range -20 dB and better in the frequency-range from around 30 MHz up to several GHz, using a thickness of absorber significantly less than that which is used with current types of absorbers given in this document.

A Potential Model for Metal-Peptide Interactions

Abstract In order to investigate hitherto undescribed dioxygen interactions in the cobalt (II)-DGEN system (DGEN: N, N-diglycylethylenediamine, l, 8-diamino-3, 6-diaza-2, 7-octanedione) all the equilibria possible under an oxygen-free atmosphere had to be reexamined. Two new equilibria have been confirmed by potentiometric and spectrophotometric measurements: M + L + H ⇌ MLH and M i+ 2L ⇌ ML2. Unlike Co (II)-dipeptide systems, metal-promoted deprotonation of the amide group has not been observed. The ML2 species may act as an “active” complex, able to take up dioxygen in a partially reversible way (reversibility up to 50%). The reaction mechanism is similar to that known for diamines. The structure of the bridging unit in the oxygenated μ-peroxo-μ-hydroxodicobalt (III) complexes has been confirmed by volumetric and spectroscopic experiments.

An effective solution to the problem of the ferrite tile gap effect

Due to the high permeability of ferrite, the presence of air gaps between adjacent tiles diminishes the performance of both the absorber and the anechoic chamber dramatically. The effectiveness of using gap fillers based on ferrite powder (e.g. ferrite rubber) is constrained due to the poor properties of ferrite powder. The problem can be solved effectively only with the use of higher permeability magnetic materials. A family of new magnetic materials has been developed by the authors. Among them is a material which can be plastic and can serve well as a gap filler. The permeability of the material is far higher than that of any mixture containing ferrite powder, even at high concentrations. In this paper, we show the effectiveness of high permeability material for filling these gaps. Due to the high permeability of the new filler the reflectivity of a resultant layer made of tiles with gaps is practically identical to that of a solid sheet of ferrite.