Selective solid phase extraction of platinum on an ion imprinted polymers for its electrothermal atomic absorption spectrometric determination in environmental samples

An ion-imprinted polymer (IIP) was obtained by copolymerization of methacrylic acid (as a functional monomer) and ethylene glycol dimethacrylate (as a crosslinking agent) in the presence of various chelators for Pt(II) ion and using 2,2??-azo-bis-isobutyronitrile as the initiator. Specifically, acetaldehyde thiosemicarbazone (AcTSn) and benzaldehyde thiosemicarbazone (BnTSn) were used as chelators. The IIPs were applied as sorbents for solid-phase extraction of Pt(II) and Pt(IV) ions from aqueous solutions. The effects of acidity and flow rate of the sample, of elution conditions and of potentially interfering ions were investigated. The imprinting effect of analyte is clearly demonstrated by the fact that only the IIP is capable of quantitative retention of Pt(II) and Pt(IV) ions. The method works best in the pH range from 0.5 to 1 and from 3.5 to 9.5. The ions can be recovered with an acidic solution of thiourea. The Pt-AcTSn polymer displays better sorption properties for the separation of analytes. The selectivity coefficients of the Pt-AcTSn and control polymers for Pt(IV) in the presence Pd(II), Rh(III), Ru(III), Al(III) and Cu(II) were calculated, and the sorbent capacity for Pt(IV) was found to be 4.56???g?g?^-1. The method was successfully applied to the determination of Pt(IV) by electrothermal atomic absorption spectrometry in tap water, tunnel dust and anode slime samples.

New potentially tridentate amidinate ligand {o-MeOC6H4NC(Ph)N(SiMe3)}?. Synthesis and molecular structures of amidinate complexes of lithium [{o-MeOC6H4NC(Ph)N(SiMe3)}Li]2 and yttrium [{o-MeOC6H4NC(Ph)N(SiMe3)}YCl2(THF)2]2

The reaction of lithium silylamide [??o-MeOC₆H₄N(SiMe₃)}Li(OEt₂)]₂ with 2 equiv. of benzonitrile in THF at ??20 °C affords the lithium derivative of the new tridentate amidinate ligand [{o-MeOC₆H₄NC(Ph)N(SiMe₃)}Li]₂. The X-ray diffraction study showed that this complex has a dimeric structure due to the coordination of the N atoms and the ether group of one amidinate ligand to different Li atoms. The reaction of anhydrous YCl₃ with the resulting complex in THF gives the monoamidinate complex [{o-MeOC₆H₄NC(Ph)N(SiMe₃)}YCl₂(THF)₂]₂ regardless of the reagent ratio. The latter has a dimeric structure in the crystalline state as a result of the presence of two ??₂-bridging Cl atoms that link Y atoms. The ether groups of the amidinate ligands are not involved in the metal-ligand interaction.     

Modeling of the molecular and electronic structures of some mono- and biosmium complexes of fullerene C60

The modeling of the molecular and electronic structures of the following mono- and biosmium complexes of fullerene C₆₀ was performed by quantum chemical methods (MNDO/PM3 and DFT/PBE): (??²-C₆₀)[Os(PPh₃)₂(CO)CNMe], (??²,??²-C₆₀)[Os(PPh₃)₂(CO)(CNMe)]₂, (??²-C₆₀)[Os(PH₃)₂(CO)H], (??²,??²-C₆₀)[Os(PH₃)₂(CO)H]₂, (??²-C₆₀)[Os(PH₃)₂(CO)CNMe], (??²,??²-C₆₀)[Os(PH₃)₂(CO)CNMe]₂, and (5-C₆₀H₅)[Os(C₅H₅)], (5, 5-C₆₀H₁₀)[Os(C₅H₅)]₂.The osmium atoms in the first six complexes are ??²-coordinated by fullerene C₆₀. In the last two complexes, the ??⁵-coordination mode is observed. The structures of the radical anions of these complexes were calculated. The energies of the frontier orbitals were evaluated. The acceptor properties of the complexes are discussed. The electron affinities were estimated in two ways: from the energy of the lowest unoccupied molecular orbital (LUMO) and as the energy difference between the neutral molecule and its radical anion.     

Reactions of methylaluminoxane and trimethylaluminum with zirconium and titanium tetracyclopentadienyl derivatives

Gas volumometry, gas chromatography, mass spectrometry, and ESR were used to study reactions of methylaluminoxane (MAO) and Me₃Al with Cp₄Zr, Cp₄Ti, and 2,2,6,6-tetra-methylpiperidine-1-oxyl (TEMPO). It was shown that the reaction is accompanied by evolution of methane, whose amount exceeds the initial concentration of the starting metallocene or free radical by a few hundred times, but in all the cases is no more than 15% of the starting amount of the Me??Al fragments in the organoaluminum compound. Metal-centered radicals were detected by ESR in the systems with Zr and Ti metallocene derivatives. Mechanism of the observed reactions is discussed.     

Free-radical reactions of the tris-dioximate clathrochelates: synthesis and X-ray structure of the first cyclohexyl-substituted monoribbed-functionalized macrobicyclic iron(ii) complex

Quantum chemical calculations were performed at the DFT level for the boron-capped dichloro-substituted tris-dioximate iron(II) clathrochelate and cyclohexane and 1,4-dioxane radicals. The 1,4-dioxane and cyclohexane radicals are nucleophiles towards the macrobicyclic precursor studied. The reaction of this clathrochelate with cyclohexane in the presence of a free-radical initiator resulted in substitution of a chlorine atom by a cyclohexyl fragment. The compound obtained was characterized by elemental analysis, IR spectroscopy, ¹H and ¹³C{¹H} NMR, and single-crystal X-ray diffraction data.     

Synthesis and photophysical properties of silica nanoparticles based on europium(iii) complexes

Monodisperse 280?C480 nm silica particles doped with europium complexes with thenoyltrifluoroacetylacetone and adducts with some phosphine oxides as luminophores were prepared for the first time by the optimized Stober procedure using surfactants. The size and the polydispersity of the obtained particles depend on the luminophore incorporated in the polymer template. The photophysical properties of aqueous dispersions of the europium(iii)-doped silica particles were studied by the luminescence method.     

Relaxation of microparticles exposed to hydrodynamic forces in microfluidic conduits

The behavior of microparticles exposed to gravitational and lift forces and to the velocity gradient in flow velocity profile formed in microfluidic conduits is studied from the viewpoint of the transient period (the relaxation) between the moment at which a particle starts to be transported by the hydrodynamic flow and the time at which it reaches an equilibrium position, characterized by a balance of all active forces. The theoretical model allowing the calculation of the relaxation time is proposed. The numerical calculus based on the proposed model is compared with the experimental data obtained under different experimental conditions, namely, for different lengths of microfluidic channels, different average linear velocities of the carrier liquid, and different sizes and densities of the particles used in the study. The results are important for the optimization of microfluidic separation units such as microthermal field-flow fractionation channels in which the separation or manipulation of the microparticles of various origin, synthetic, natural, biological, etc., is performed under similar experimental conditions but by applying an additional thermodynamic force.

Extended canonical algebras and Fuchsian singularities

The authors introduce a new class of finite dimensional algebras called extended canonical, and determine the shape of their derived categories. Extended canonical algebras arise from a canonical algebra ?? by onepoint extension or coextension by an indecomposable projective module. Our main results concern the case of negative Euler characteristic of the corresponding weighted projective line ${\mathbb{X}}$ ; more specifically we establish, for a base field of arbitrary characteristic, a link to the Fuchsian singularity R of ${\mathbb{X}}$ which for the base field of complex numbers is isomorphic to an algebra of automorphic forms. By means of a recent result of Orlov we show that the triangulated category of the graded singularities of R (in the sense of Buchweitz and Orlov) admits a tilting object whose endomorphism ring is the corresponding extended canonical algebra. Of particular interest are those cases where the attached Coxeter transformation has spectral radius one. A K-theoretic analysis then shows that this happens exactly for 38 cases including Arnold??s 14 exceptional unimodal singularities. The paper is related to recent independent work by Kajiura, Saito and Takahashi.     

Foliations invariant by rational maps

We give a classification of pairs ${(\mathcal{F}, \phi)}$ where ${\mathcal{F}}$ is a holomorphic foliation on a projective surface and ${\phi}$ is a non-invertible dominant rational map preserving ${\mathcal{F}}$ .