Bogusława Łęska

Freshwater Ulva (Chlorophyta) as a bioaccumulator of selected heavy metals (Cd, Ni and Pb) and alkaline earth metals (Ca and Mg)

We analyzed the ability of freshwater taxa of the genus Ulva (Ulvaceae, Chlorophyta) to serve as bioindicators of metal in lakes and rivers. Changes in heavy metal (Ni, Cd and Pb) and alkaline earth metal (Ca and Mg) concentrations in freshwater Ulva thalli were investigated during the period from June to August 2010. The study was conducted in two ecosystems in Western Poland, the Malta lake (10 sites) and the Nielba river (six sites). Three components were collected for each sample, including water, sediment and Ulva thalli. The average concentrations of metals in the water sample and in the macroalgae decreased in the following order: Ca>Mg>Ni>Pb>Cd. The sediment revealed a slightly altered order: Ca>Mg>Pb>Ni>Cd. Ca and Mg were found at the highest concentrations in thalli due to the presence of carbonate on its surface. Among the examined heavy metals in thalli, Ni was in the highest concentration, and Cd found in the lowest concentration. There were statistically significant correlations between the levels of metals in macroalgae, water and sediment. Freshwater populations of Ulva exhibited a greater efficiency to bioaccumulate nickel as compared to species derived from marine ecosystems.

Supercritical fluid extraction of algae enhances levels of biologically active compounds promoting plant growth

Abstract The aim of this research was to screen plant growth biostimulant properties of supercritical CO2 macroalgal extracts. To this end secondary metabolites were isolated from the biomass of marine macroalgae from the Baltic Sea (species of Polysiphonia, Ulva and Cladophora). Chemical characteristics of the algal extracts were determined by inductively coupled plasma atomic emission spectroscopy for inorganic constituents and high-performance liquid chromatography and spectrophotometry for organic constituents. Inorganic (macro- and microelements) and organic (plant hormones: auxins and cytokinins; polyphenols) compounds were detected in the extract. Algal extracts were tested primarily on garden cress (Lepidium sativum L.; Brassicaceae) and wheat (Triticum aestivum L.; Poaceae). The extracts enhanced chlorophyll and carotenoid content in plant shoots, as well as root thickness and above-ground biomass. The most effective method of application of the extract was by foliar feed on cress and seed maceration for wheat. Algal extracts obtained by supercritical fluid extraction (SFE) were found to be a novel natural source of compounds, stimulating growth of cultivated plants. However, field trials will be required to show that the extracts can act as plant biopesticides and growth biostimulants.

Podand Solvents for Organic Reactions

Three tris(oxaalkyl)phenylsilanes and two tris(oxaalkyl)phosphates were used as podand solvents in kinetic studies of proton transfer reactions between C-acids: dimethyl (4-nitrophenyl)malonate or phenyl-4-nitrophenylcyanomethane and the strong base: 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD). The acceptor numbers were measured for all new podand solvents. The kinetic parameters for studied reactions were obtained, discussed and compared with those of acetonitrile and OP(OEt) 3 as non-podand solvents. This study demonstrated that the second order rate constants strongly decreased and the energy barrier increased for the proton transfer reaction in podand solvents. Spectroscopic observations showed that ionic products were strongly stabilised and therefore their lifetime was relatively long. The podand solvents formed the ionic channels in which ionic products are strongly solvated.

Kinetic and equilibrium studies of the proton and deuteron transfer reaction between bis (2,4-dinitrophenyl)methane and strong nitrogen bases in acetonitrile

Abstract Deprotonation of bis(2,4-dinitrophenyl)methane (C-acid) by tetramethylguanidine (TMG), 1,2-bis(dimethyl-aminomethyl) benzene (DMAMB) and 1,8-bis(dimethylamino)naphthalene (DMAN) in acetonitrile was studied by visible, 1 HNMR and FT-IR spectroscopy. The mixture of TMG with C-acid forms a protonated base and a product, which was different when compared with the mixtures of DMAMB or DMAN with C-acid. The spectral feature was explained as a strong electrostatic interaction between the product and the protonated TMG. Kinetic and equilibrium measurements of the reactions of C-acid with TMG, DMAMB and DMAN were completed and the kinetic isotope effects k H / k D are reported.

FTIR and NMR studies of bis(oxaalkyl) sulphates(IV) and their complexes with proton and some metal cations

Abstract The complexation of Li + and Na + cations by three bis(oxaalkyl) sulphates(IV) was studied by FTIR and NMR on 1 H, 13 C, 7 Li and 23 Na nuclei. The NMR results have proved the formation of complexes and the fluctuation of Li + and Na + cations in respective circular arrangements. In the FTIR spectra of protonated sulphates intense continuous absorptions were observed indicating fast fluctuation of the protons in the respective multiminima potentials. The continuous absorptions in the far infrared region of the FTIR spectra of Li + or Na + complexes with three bis(oxaalkyl) sulphates(IV) indicate fast fluctuations of Li + or Na + cations between O-atoms of the oxaalkyl chains. The independence of the shape of the continua on the length of the oxaalkyl chains, i. e. the number of minima in the multiminima potential, demonstrates that the fluctuation of cations occurs in the respective circular arrangements.

Deprotonation of N-phenacyl- and N-acetonyl-4-cyanopyridinium halides with 1,4-diazabicyclo[2,2,2]octane

Abstract In N-phenacyl- and N-acetonyl-4-cyanopyridinium halides (1a·Br and 1b·Cl) the N+CH2 hydrogens are replaced by deuterium in D2O or CH3OD solutions, similarly as in β-diketones, proving a prototropic equilibrium 1⇌2. The rate constants have been measured for deprotonation of 1a·Br and 1b·Cl with 1,4-diazabicyclo[2,2,2]octane (DABCO) in solutions. UV, FTIR, 1H and 13C NMR spectra are consistent with the ylide structure of the deprotonated species. N-phenacyl-4-cyanopyridinium ylide (3a) is relatively stable in the solid state and unstable in solutions. The observed parallel changes in ΔS≠ and the time of disappearance of the ylide absorption band suggest that solvation is responsible for the ylide stability. The UV–Vis spectra of 1a·Br and 1b·Cl with DABCO show solvent dependent isosbestic points, which suggest that the decomposition reactions of ylides are very probably uniform. The PM3 and B3LYP calculations were carried out to investigate the structures of the cations, ylides and their complexes with ammonia and DABCO. Ylides are formed by abstraction of hydroxy proton from enol form (2) via complex 8.

Supercritical Algal Extracts: A Source of Biologically Active Compounds from Nature

The paper discusses the potential applicability of the process of supercritical fluid extraction (SFE) in the production of algal extracts with the consideration of the process conditions and yields. State of the art in the research on solvent-free isolation of biologically active compounds from the biomass of algae was presented. Various aspects related with the properties of useful compounds found in cells of microalgae and macroalgae were discussed, including their potential applications as the natural components of plant protection products (biostimulants and bioregulators), dietary feed and food supplements, and pharmaceuticals. Analytical methods of determination of the natural compounds derived from algae were discussed. Algal extracts produced by SFE process enable obtaining a solvent-free concentrate of biologically active compounds; however, detailed economic analysis, as well as elaboration of products standardization procedures, is required in order to implement the products in the market.

Potentiometric and AM1d studies of a new class of Tr-podands–silver(I) complexes

Formation of complexes of structurally comparable six silicon, boron and phosphorous Triton X podands (Tr-podands) and silver(I) cations in propylene carbonate has been studied by the potentiometric and AM1d semi-empirical methods. Three types of these podands (2–7) form stable complexes with Ag+ cations. The stability constants of the complexes including different number of silver(I) cations are determined. It has been shown that the number of Ag+ cations complexed by the podands depends strongly on the number of oxaalkyl chains and on the type of central podands atom (Si, B or P). The (7) podand (with six polyoxaalkyl chains) can complex as many as six silver(I) cations. The structures of these complexes are visualised by the AM1d semi-empirical method.

Studies on the complex formation between lactams and thiolactams of sparteine with copper(II) cation

The complex formation for lactams and thiolactams of sparteine with Cu(II) cation in ethanol was studied by theoretical, kinetic and MS methods. The studied compounds with Cu(II) cation formed 1:1 and 1:2 complexes. The kinetic parameters of their formation were determined. Both kinetic and thermodynamic parameters depend strongly on the presence of oxo- or thiono-group in sparteine skeleton.

15N NMR and FTIR studies of 2,4-dinitroanilines and their salts

Abstract Twenty-two 2,4-dinitroanilines were synthesised and their p K a values were determined. The 2,4-dinitroanilines and their protonated forms were studied by 15 N NMR spectroscopy. The relations between the 15 N NMR chemical shifts and the p K a values of the 2,4-dinitroanilines and their salts were found to be linear. The deprotonation reaction of N -methyl-2,4-dinitroanilines and N -methyl-2,4,6-trinitroaniline by MTBD was successful only for the latter and yielded protonated MTBD molecule and the anion in which the electrons are strongly delocalised. The kinetic parameters of the 2,4-dinitroanilines in reactions with hydroxide ions in mixed solvent DMSO:water (95:5, v/v) were determinated and discussed.