In memoriam Associate Professor Ing. Vladimír Daněk, DrSc
Published in Chemical Papers
In memoriam Associate Professor Ing. Vladimír Daněk, DrSc
Synthesis and characterization of the rare-earth complexes with salicylic acid
Published in Chemical Papers
Seven rare-earth complexes with salicylic acid RE(HSal)3·nH2O (HSal = C7H5O3; RE = La-Sm, n = 2; RE = Eu, Gd, n = 1) were synthesized and characterized by elemental analysis, the IR spectrum, and cyclic voltammetry. The constant-volume combustion energies of complexes, Δc U, were determined by a precise rotating-bomb calorimeter at 298.15 K. Their ...
Complexes of biologically important ligands. I. Ternary complexes of nickel(II) comprising 1,10-o-phenanthrolineazosulfo...
Published in Chemical Papers
5-[p-(R-Sulfonyl)phenylazo]-1,10-o-phenanthroline (L) and its octahedral complexes of the type [Ni(R2dtp)2(L)] (where R2dtp = diethyl-or dipropyldithiophosphate) with the core NiN2S4 have been prepared and characterized by spectral, magnetic, and thermogravimetric methods. The thermal decomposition mechanism of the compounds was proposed and the ki...
A simple linear sweep voltammetric method for the determination of double-stranded DNA with malachite green
Published in Chemical Papers
In pH 3.5 Britton—Robinson buffer solution double-stranded (ds) DNA can react with malachite green (MG) to form an interaction complex, which resulted in the decrease of the electrochemical response of MG, MG had a well-defined second-order derivative linear sweep voltammetric peak at −0.73 V (vs. SCE). After the addition of dsDNA into MG solution,...
Synthetic approaches towards bisspiro[naphthalene-2(1H),3′-(3H)pyrazol]-1-one-containing compounds
Published in Chemical Papers
1,3-Dipolar cycloaddition reaction of bis{[4-(3,4-dihydro-(2H)-naphthalen-1-oxo-2-yl)methyl-idenephenyl]oxy}alkanes with nitrilimines (generated in situ by triethylamine dehydrohalogenation of the corresponding hydrazonoyl chlorides) in refluxing dry benzene afforded a mixture of monocycloadduct and dicycloadduct products in high regioselectivity. ...
Determination of 5-hydroxymethylfurfural after Winkler and by the HPLC method for authentication of honey
Published in Chemical Papers
The quality and authenticity of commercially available honey from Slovak market and the development of HPLC method for determination of hydroxymethylfurfural (HMF) content of honey with fine separation efficiency, sensitivity, applicability, and recovery was evaluated. Physicochemical parameters (moisture, total acidity, content of proline, sacchar...
Calibrationless determination of electroactive species using chronoamperograms at collector segment of interdigitated mi...
Published in Chemical Papers
The possibility of calibrationless chronoamperometric determination is described using a pair of individually addressable and diffusion layers interacting segments of interdigitated microelectrode array (IDA). It utilizes dual voltammetric mode where the first segment is polarized with potential corresponding to the limiting current of determined s...
Limited sample recovery in coupled methods of high-performance liquid chromatography of synthetic polymers
Published in Chemical Papers
Complex polymer systems, which exhibit multiple distributions in their molecular parameters can be characterized by coupled liquid chromatographic methods. The latter combine entropic (exclusion) and enthalpic (interaction) retention mechanisms. However, recent experimental results suggest that some coupled liquid chromatographic methods may suffer...
The β-carotene dilemma: ESR study with coordinated peroxyl radicals
Published in Chemical Papers
The apparently unpredictable behaviour of β-carotene in the supplementation of the diet of smokers is discussed in the light of the reactions of peroxyl radicals with β-carotene in the absence of oxygen. The decay of tert-butylperoxyl radicals in the presence of β-carotene was studied at ambient temperature in non-polar solvents by ESR spectroscopy...
Synthesis and reactions of 2-and 4-substituted furo[3,2-c]pyridines
Published in Chemical Papers
Substituted furopropenoic acids were prepared from appropriate aldehyde under the Doebner’s conditions. Obtained acids were converted to the corresponding azides, which were cyclized by heating in Dowtherm to furopyridones. These compounds were aromatized with phosphorus oxychloride to chloro derivatives of furo[3,2-c]pyridine (Va, Vb). Chloro deri...
