Zygmunt Warnke

Bio: Zygmunt Warnke is an academic researcher from University of Gdańsk. The author has contributed to research in topics: Thermal decomposition & Crystal structure. The author has an hindex of 10, co-authored 42 publications receiving 325 citations.

Cuticular hydrocarbons of the german cockroach, Blattella germanica L.

Abstract: 1. 1. The cuticular hydrocarbons from the German cockroach consist of n-alkanes, 3-methylalkanes, internally branched monomethylalkanes and dimethylalkanes. 2. 2. The composition of the hydrocarbon fraction differs markedly from the other species of cockroaches. n-Nonacosane and n-heptacosane as well as their monomethyl and dimethylderivatives are the major constituents of the hydrocarbon fraction from Blattella germanica. 3. 3. Lesser amounts of n-octacosane and two of its monomethylisomers have also been identified. 4. 4. The dimethylalkanes are nearly all 3,X-dimethylalkanes. There are 3, 5 and 7 methylene groups between the 3 and X in the various chains from carbon numbers 27–29.

Structural and physico-chemical characteristics of tetraethylammonium tetrachloridoferrate(III)

Abstract: The crystal structure of tetraethylammonium tetrachloridoferrate(III) was determined. The crystals are hexagonal, space group P63 mc, a = 8.198(1) A, b = 8.198(1) A, c = 13.183(3) A, V = 767.3(2) A3, Z = 2. The asymmetric unit of [(C2H5)4N][FeCl4] consists of half each of a tetraethylammonium cation and a tetrachloridoferrate(III) anion. Tetrachloridoferrate(III) ion adopts almost ideal tetrahedral geometry. Structural characterization of the compound is supplemented by the results of its magnetic susceptibility measurements and electron paramagnetic resonance (EPR) spectra. Magnetic measurements of a powdered [(C2H5)4N][FeCl4] sample gave a negative Weiss constant of −1.57, which suggests antiferromagnetic coupling. The susceptibility curve of [(C2H5)4N][FeCl4] against temperature exhibits a maximum, indicating the presence of antiferromagnetic ordering with a Neel temperature of approximately 2.9 K.

Chemistry, biochemistry, and physiology of insect cuticular lipids

Abstract: The chemistry, biochemistry, and physiology of insect cuticular lipids are reviewed. The types of components present in cuticular extracts are described with special emphasis on the occurrence and identification of the di- and trimethylalkanes and the newly discovered tetramethylalkanes. The methods used in the extraction of cuticular components are discussed, including recommendations to standardize procedures. The structural elucidation of methylalkanes, particularly the mass spectral interpretation of multi-methyl-branched alkanes, is reviewed. The biosynthesis of cuticular lipids is discussed with emphasis on the hydrocarbon components, describing elongation reactions and the origin of the methyl branches. The effects of environment and development on cuticular lipids are reviewed.

Biochemistry of insect epicuticle degradation by entomopathogenic fungi.

Abstract: The biochemical interaction between fungal pathogens and their insect host epicuticle was studied by examining fungal hydrocarbon degrading ability. As a contact insecticide, entomopathogenic fungi invade their host through the cuticle, covered by an outermost lipid layer mainly composed of highly stable, very long chain structures. Strains of Beauveria bassiana and Metarhizium anisopliae (Deuteromycotina: Hyphomycetes), pathogenic both to the blood-sucking bug Triatoma infestans (Hemiptera: Reduviidae) and the bean-weevil Acanthoscelides obtectus (Coleoptera, Bruchidae), were grown on different carbon sources. Alkane-grown cells showed a lipid pattern different from that of glucose-grown cells, evidenced by a major switch in the triacylglycerol and sterol components. Radiolabelled hydrocarbons were used to investigate the catabolic pathway and the by-product incorporation into fungal cellular components. The first oxidation round is presumably carried out by a cytochrome P450 enzyme system, the metabolites will traverse the peroxisomal membrane, and after successive transformations will eventually provide the appropriate fatty acyl CoA for complete degradation in the peroxisomes, the site of β-oxidation in fungi. In this review, we will show the relationship between fungal ability to catabolize very long chain hydrocarbons and virulence parameters.

Diversity of azido magnetic chains constructed with flexible ligand 2,2'-dipyridylamine.

Abstract: By employing a flexible molecule, 2,2′-dipyridylamine (dpa), as a bidentate coligand, three azide-bridged one-dimensional coordination polymers, [M(dpa)(N3)2]n (M = Cu, 1·Cu; Co, 2·Co) and [Ni(dpa)(OAc)0.5(N3)1.5(H2O)]n (3·Ni), have been successfully synthesized and structurally and magnetically characterized. They show versatile one-dimensional chain structures. 1·Cu is an EO-N3 bridged uniform chain; 2·Co is an alternative chain linked by two EO-N3 and two EE-N3 bridges. Interestingly, 3·Ni is a zigzag chain linked alternatively by one EE-N3 and a novel 3-fold bridge, which is composed of two EO-N3 and one acetate group. This series of azido complexes demonstrates that the flexibility of the dpa ligand plays an important role in directing the structures of the final products. Magnetic studies reveal dominant intrachain antiferromagnetic couplings in compound 1·Cu. Compounds 2·Co and 3·Ni are weak ferromagnets due to the spin canting, with critical temperatures of 12.4 and 32.5 K, respectively.

Novel Phase-Transition Materials Coupled with Switchable Dielectric, Magnetic, and Optical Properties: [(CH3)4P][FeCl4] and [(CH3)4P][FeBr4]

Abstract: Two inorganic–organic hybrid compounds with zero-dimensional crystal structures, tetramethylphosphonium tetrachloroferrate(III) (compound 1, [(CH3)4P][FeCl4]) and tetramethylphosphonium tetrabromoferrate(III) (compound 2, [(CH3)4P][FeBr4]), are discovered as multifunctional materials exhibiting simultaneously switchable dielectric, magnetic, and optical properties. Despite the analogue chemical formulas, compounds 1 and 2 crystallize in the different noncentrosymmetric space groups, that is, P63mc and F43m, and exhibit distinct responses in the three above-mentioned physical channels, especially for the magnetic property. Compound 1 undergoes dielectric anomalies which could be tuned in three distinct dielectric states and switched by the sequential phase transitions around 362 and 436 K, respectively. The symmetry breaking occurring during the first phase transition is confirmed by the switchable temperature-dependent second harmonic generation (SHG) effect. Weak antiferromagnetic interactions are also ...