Oksana Pietraszkiewicz

Chiral discrimination of amino acids and their potassium or sodium salts by optically active crown ether derived from d-mannose

Chiral naphtho-18-crown-6 incorporating α-methyl d-mannopyranoside unit exhibits a pronounced chiral discrimination of amino acids in their zwitterionic form, or as potassium and sodium salts in transport across the bulk liquid membrane containing the carrier, as well as in the extraction experiments from the water phase to chloroform phase containing the receptor. The dl selectivity strongly depends on the species used (neutral amino acids, or their salts), and in some cases the reversed selectivity within the same amino acid enantiomers has been observed, indicating the influence of the cation involved.

Rare earth ions, their spectroscopy of cryptates and related complexes in sol-gel glasses

The paper is devoted to the memory of my teacher and friend Christian K. Jorgensen who has written the pioneering works on complexes of Rare Earths (RE).

Separation of Pyrimidine Bases on HPLC Stationary RP-18 Phase Coated with Calix[4] resorcinarene

Lipophilic calix[4]resorcinarenes, derived from lauryl aldehyde and resorcinol, are strongly adsorbed on the modified silica gel RP-18 for HPLC chromatography, while their solutions are passed through the column. The calix[4]resorcinarene-coated RP-18 phases were found to be useful beds for HPLC separation of uracil, thymine and cytosine.

The long and winding road to new porphycenes

We describe attempts — not always successful — made over the years to improve the efficiency of porphycene synthesis and to produce novel compounds, custom-designed for specific purposes. New porphycenes are reported, some of them obtained rather unexpectedly as by-products of the planned reactions. Structure and energy computations of possible tautomeric forms in porphycenes substituted by one, two, three, and four tert-butyl groups lead to predictions regarding the kinetics and mechanisms of intramolecular double hydrogen transfer. The occurrence of tautomerization in single molecules of tert-butyl-substituted porphycenes is demonstrated by using fluorescence polarization techniques.

Transport studies of inorganic and organic cations across liquid membranes containing mannich-base calix[4]resorcinarenes

Calixarenes are very versatile macrocyclic molecular receptors comprising phenolic units. Their easy availability, complexing features and possibility for a variety of chemical modifications makes them particularly attractive to serve as target molecules for various studies in supramolecular chemistry. Three monograph books on calixarene chemistry appeared to date [1–3].

Strongly photoluminescent Eu(III) tetrazolate ternary complexes with phosphine oxides as powerful sensitizers

The Eu(III) cation forms electrically neutral photoluminescent complex with 5-(2-pyridyl-1-oxide)tetrazolate (PTO) anion. Although the photoluminescence properties of such tertiary Eu(III) and Tb(III) complexes were not as high (13 and 31% photoluminescence quantum yield, respectively) as reported for other diketonate lanthanide complexes probably because of high number of nitrogen atoms involved in PTO which leads to attachment of water molecules, reducing the luminescence quantum yield with vibrational and rotational quenching. Here, we report the removal of quencher molecules from the coordination sphere of tris–europium tetrazolate oxide complex by replacing them with various phosphine oxides which leads to improved photoluminescence quantum yield for the complexes by acting as auxiliary co-ligands with that of the main antenna 5-(2-pyridyl-1-oxide)tetrazolate. The coordination sphere in these complexes can be complemented by aromatic phosphine oxides to provide highly photoluminescent Eu(III) complexes. The highest quantum yield was 38% in 3 [Eu(PTO)3·DPEPO](H2O)5 containing bis(2-(diphenylphosphino)phenyl) ether oxide (DPEPO) as compared to tris–europium complex with 5-(2-pyridyl-1-oxide)tetrazolate. The Eu(III) cation forms electrically neutral photoluminescent complex with 5-(2-pyridyl-1-oxide)tetrazolate (PTO) anion. Although the photoluminescence properties of such tertiary Eu(III) and Tb(III) complexes were not as high (13 and 31% photoluminescence quantum yield, respectively) as reported for other diketonate lanthanide complexes probably because of high number of nitrogen atoms involved in PTO which leads to attachment of water molecules, reducing the luminescence quantum yield with vibrational and rotational quenching. Here, we report the removal of quencher molecules from the coordination sphere of tris-europium tetrazolate oxide complex by replacing them with various phosphine oxides which leads to improved photoluminescence quantum yield for the complexes by acting as auxiliary co-ligands with that of the main antenna 5-(2-pyridyl-1-oxide)tetrazolate. The coordination sphere in these complexes can be complemented by aromatic phosphine oxides to provide highly photoluminescent Eu(III) complexes. The highest quantum yield was 38% in 3 [Eu(PTO)3·DPEPO](H2O)5 containing bis(2-(diphenylphosphino)phenyl) ether oxide (DPEPO) as compared to tris–europium complex with 5-(2-pyridyl-1-oxide)tetrazolate.

Chiral Discrimination of Amino Acids by an Optically Active Crown Ether Studied by HPLC, Extraction and a Liquid Membrane Transport Experiments

A chiral crown ether incorporating a methyl α-d-mannopyranoside unit displayed pronounced enantioselection of amino acids in partition liquid chromatography experiments involving solvent systems of limited miscibility: water–ethanol–2,2,4-trimethylpentane. The same system has been used for amino acid transport across a liquid membrane containing the crown ether, and in liquid–liquid extraction experiments. Remarkable enantioselection has been noted for amino acids in all the processes studied.

Luminescent lanthanide complexes with macrocyclic N-oxides

Abstract Bicyclic ligand incorporating 3,3′-biisoquinoline-2,2′-dioxide unit fused with 1,10-diaza-18-crown-6 and 6,6′-dicarboxy-2,2′-bipyridine forms luminescent mononuclear and binuclear europium(III) complexes, respectively, that are stable in water solution. The presence of interfering ions, such as phosphate and Ca(II), caused a slight increase in the quantum yield of Eu(III) emission in the case of bicyclic ligand, and some loss of luminescence efficiency in the case of acyclic Eu(III) complex upon UV irradiation. This feature makes the bicyclic complex very attractive for practical applications in time-resolved fluorimetric immunoassays.

Eu(III) complexes involving 1,3,5-triazine diphosphine oxides

Abstract The 1,3,5-triazine diphosphine oxide ligands with donor-acceptor properties formed strong complexes with europium(III) ion in acetonitrile. Spectrophotometric titrations and mass spectra indicated that two ligands coordinated to one europium ion. The stability constants varied from 11.64 to 14.60 (log β). Binary complexes exhibited rather weak luminescence in solution. 1,3,5-triazine diphosphine oxides engaged as co-ligands in Eu(III) (2-thenoyltrifluoroacetonate) 3 complex contributed to the overall photoluminescence and allowed for excitation with longer wavelengths than the parent complex.

Potentiometric Response of Liquid Membrane Electrode Incorporated with Macrocyclic Polyamine Towards Benzoate

Abstract The potential responses of electrodes based on a macrocyclic polyamine incorporated in poly(vinyl chloride) (PVC) liquid membrane, without and with added lipophilic salt tridodecylmethylammonium chlorides (TDDMACl) towards benzoate were studied. These electrodes are very sensitive towards H+, the potentiometric measurements were realized in the presence of 10−2 M MES buffer pH 5.0. They responsed towards benzoate with the detection limit 1.0 × 10−4 M. This level of sensitivity is sufficient for the determination of benzoic acid added to juices as conservative compound in milimolar concentration. The interferences caused by common anions (CH3COO−, citrate, Cl−, , phosphate and ), which are present in food samples were determinated by the matched potential method (MPM). The validation of macrocyclic polyamine electrodes was done by the recovery test of benzoate in the presence of artificial juice matrix. The results obtained pointed out that these sensors might be applied for the direct determination of benzoate in food samples.