Antiradical, chelating and antioxidant activities of hydroxamic acids and hydroxyureas

Reactive oxygen species, along with reactive nitrogen species, may play an important role in the pathogenesis and progress of many diseases, including cancer, diabetes and sickle cell disease. It has been postulated that hydroxyurea, one of the main treatments in sickle cell disease, achieves its activity partly also through its antioxidant properties. A series of hydroxyurea derivatives of L- and D-amino acid amides and cycloalkyl-N-aryl-hydroxamic acids was synthesized and investigated for their radical scavenging activity, chelating properties and antioxidant activity. All the compounds showed exceptional antiradical activities. For example, free radical scavenging activities of investigated hydroxyureas were higher than the activity of standard antioxidant, butylated hydroxyanisole (BHA). Moreover, most of the investigated hydroxamic acids were stronger Fe2? ion chelators than quercetin. In addition, the investigated compounds, especially hydroxamic acids, were proven to be excellent antioxidants. They were as effective as BHA in inhibiting β-carotene-linoleic acid coupled oxidation. It is reasonable to assume that the antioxidant activity of the investigated compounds could contribute to their previously proven biological properties as cytostatic and antiviral agents.     

Three novel phases in the Sm-Co-Ga system. Syntheses, crystal and electronic structures, and electrical and magnetic properties

This paper presents the synthesis, identification, and characterization of three novel phases in the ternary system Sm-Co-Ga: SmCoGa5 (tP7, HoCoGa5 type, tetragonal P4/mmm, Z = 1, a = 4.2419(3) A, and c = 6.8559(5) A), Sm4Co3Ga16 (tP23, tetragonal P4/mmm, Z = 1, a = 6.0620(5) A, and c = 11.1495(9) A), and SmCoGa4 (oC24, YNiAl4 type, orthorhombic Cmcm, Z = 4, a = 4.1246(6) A, b = 15.608(2) A, and c = 6.4556(9) A). The structure of SmCoGa5 was obtained from a multiphase X-ray powder Rietveld refinement whereas the crystal structures of the other two phases were determined from single-crystal X-ray analysis. Electronic structures were calculated for all phases by first-principles DFT methods. The atomic arrangements and bonding are discussed on the basis of the partial anionic networks involving Co and Ga atoms, and a strong structural correlation is observed between SmCoGa5 and Sm4Co3Ga16. The latter, which displays paramagnetic behavior, has a resistivity of 4.2 microOmega.cm at 3 K and undergoes a superconducting transition at 2.8 K.     

Effect of cetyltrimethylammonium bromide on the migration of polyaromatic hydrocarbons in capillary electrokinetic chromatography

The separation of different ring numbered polyaromatic hydrocarbons (PAHs) was accomplished by using cetyltrimethylammonium bromide (CTAB) in capillary electrokinetic chromatography. In order to increase the solubilities and selectivities of PAHs, acetonitrile (ACN) was used as an organic modifier. Under the optimised conditions, 11 aromatic compounds were separated within 14.5 min in a running electrolyte containing 10 mM phosphate, 30 mM CTAB, and 40% ACN at pH 6.0. The effects of CTAB and ACN concentrations, voltage and pH on the resolution were investigated. Reproducibilities of migration times range between 0.55 and 1.27 R.S.D.% and peak areas between 1.02 and 7.23 R.S.D.%. Limit of detections (LODs) range between 0.09 and 2.24 μg ml⁻¹. This new and fast separation method of PAHs was applied to cooked oil sample.     

Extending Excited-state Lifetimes by Interchromophoric Triplet-state Equilibration in a Pyrene-Ru(II)diimine Dyad System

The synthesis and the spectroscopic properties of a bichromophoric ruthenium trisbipyridyl-1,4-diethynylenebenzene-pyrene system (Ru-b-Py) and the corresponding pyrene ligand (b-Py) are reported. The ruthenium model systems Ru-b-OH, Ru-b-Ph are also presented. UV–Vis absorption and emission at room and low temperature and time-resolved spectroscopy are discussed. For the Ru-b-Py dyad, a mixing of the ³MLCT state of the ruthenium-based component and the triplet state of pyrene, ³Py, is observed. Time-resolved transient absorption studies performed on the Ru-b-Py and on the b-Py ligand show that the lowest energy absorption is due to the population of the triplet state localized on the pyrene-component. Time-resolved studies also evidenced a relatively slow forward triplet equilibration rate, in the order of 2×10⁵?s^-1 (5?μs), and an even slower back energy transfer rate, 3.3×10⁴?s^-1, still faster than the intrinsic decay time of the pyrene (200?μs).     

Kinetic spectrophotometric determination of traces of molybdenum(VI) by its inhibitory effect on the oxidation of 4-hydroxycoumarine by potassium permanganate.

The present paper describes a simple, selective and sensitive kinetic method for the determination of trace amounts of molybdenum(VI) based on its inhibitory effect on the reaction oxidation of 4-hydroxycoumarine by KMnO(4) in the presence of hydrochloric acid, at pH 1.75 at 25 degrees C. The rate of the indicator reaction was followed spectrophotometrically by measuring the decrease in the absorbance of KMnO(4) at 525 nm. The development method includes optimization of the reagent concentration and temperature. The calibration graph was linear in the range of concentrations from 20 to 200 ng/cm(3) of molybdenum(VI). The probable relative error was in the interval 3.10 - 10.52% for the concentration range of 200 - 20 ng/cm(3) molybdenum(VI), respectively. The interference effects of the foreign ions were determined to assess the selectivity of the method. The developed method was found to have relatively good selectivity, sensitivity, simplicity and rapidity. The proposed method was applied to the determination of molybdenum(VI) in a particular type of steel and alloy (hastelloy).     

Absolute configuration of (+)‐(S)‐2‐(5‐fluoro‐2‐methoxy‐1,4‐benzodioxan‐2‐yl)­imidazolinium bromide

The title compound, C₁₂H₁₄FN₂O₃⁺·Br^?, crystallizes in the non‐centrosymmetric P2₁2₁2₁ space group. The absolute configuration of the pharmacologically active mol­ecule could be resolved in the hydro­bromide salt, the structure of which is reported. The mol­ecule of the title compound has the S configuration. The molecular packing in the crystal is stabilized by weak N—H?Br [N?Br = 3.240 (4) and 3.302 (4) Å] hydrogen bonding.     

Multimedia Tools for Learning Fluorescence: A Spectrofluorometer Simulator

A new teaching method, using multimedia software, is in progress at our university. Running on a PC computer, it allows self-formation in molecular spectroscopy. A new software package devoted to photoluminescence (ISPL) is currently in progress. The concepts are introduced by using numerous graphs, animations, and simulations. The software allows electronic book facilities (search function, glossary, and bookmarks, for instance) and self-assessment. Tedious and time-consuming training is always necessary to acquire experimental skill. This is particularly true in the case of luminescence because numerous artifacts are possible and the number of parameters to be optimized is very large. In this view, a spectrofluorometer simulator appears to be a valuable tool that makes this training easy and fast: after choosing a set of experimental parameters, the computer displays immediately the corresponding spectrum. The influence of every experimental parameter is simulated: monochromator slit width, excitation or emission wavelengths, xenon source type, photomultiplier tube high-voltage, etc. The nature of solvents, with first- and second-order Rayleigh and Raman scattering, is managed. Sample geometry and concentration, with a corresponding inner filter, are also simulated. Obviously, there is no risk of damaging the virtual photomultiplier tube.