Discovery of powerful uranyl ligands from efficient synthesis and screening

New tripodal gem-(bis-phosphonates) uranophiles were discovered by a screening method that allowed for the selection of ligands with strong uranyl-binding properties in a convenient microtiter-plate format. The method is based on competitive uranium binding by using Sulfochlorophenol S as chromogenic chelate. This dye compound was found to present high uranyl complexation properties and allowed to highlight ligands presenting association constants for UO(2+)(2) up to 10(18) at pH 7.4 and 10(20) at pH 9. A collection of 40 known ligands including polycarboxylate, hydroxamate, catecholate, hydroxypyridonate and hydroxyquinoline derivatives was tested. Also screened was a combinatorial library prepared from seven amine scaffolds and eight acrylates bearing diverse chelating moieties. Among these 96 tested candidates, a tripod derivative bearing gem-bis-phosphonates moieties was found to present the highest complexation properties over a wide range of pH and was further studied.     

Extraction of glyphosate by a supported liquid membrane technique

The possible application of the supported liquid membrane (SLM) technique for the extraction of glyphosate is presented. For the extraction of this compound the SLM system has been applied with utilisation of Aliquat 336 as a cationic carrier incorporated into the membrane phase. The extraction efficiency of glyphosate [N-(phosphonomethyl)glycine] is dependent on the donor phase pH, carrier concentration in the organic phase and NaCl concentration in the acceptor phase. The optimal extraction conditions are: donor phase pH>11, acceptor phase of 2 M NaCl solution and the organic phase composed of 20% (w/w) Aliquot 336 solution in di-hexyl ether. Counter-coupled transport of chloride anions from the acceptor phase to the donor phase is a driving force of the mass transfer in this system.     

Catalytic ignition of ionic liquids for propellant applications

In this proof of concept study, the ionic liquids, 2-hydroxyethylhydrazinium nitrate and 2-hydroxyethylhydrazinium dinitrate, ignited on contact with preheated Shell 405 (iridium supported on alumina) catalyst and energetically decomposed with no additional ignition source, suggesting a possible route to hydrazine replacements.     

Circular dichroism, optical rotation and absolute configuration of 2-cyclohexenone-cis-diol type phenol metabolites: redefining the role of substituents and 2-cyclohexenone conformation in electronic circular dichroism spectra

The absolute configurations of 2-cyclohexenone cis-diol metabolites resulting from the biotransformation of the corresponding phenols have been determined by comparison of their experimental and calculated circular dichroism spectra (TDDFT at the PCM/B2LYP/Aug-cc-pVTZ level), optical rotations (calculated at the PCM/B3LYP/Aug-cc-pVTZ level) and by stereochemical correlation. It is found that circular dichroism spectra and optical rotations of 2-cyclohexenone derivatives are strongly dependent on the ring conformation (M or P sofa S(5) or half-chair), enone non-planarity and the nature and positions of the hydroxy and alkyl substituents. The effect of non-planarity of the enone chromophore, including the distortion of the C=C bond, is determined for the model structures by TDDFT calculations at the PCM/B2LYP/6-311++G(2d,2p) level. Non-planarity of the C=C bond in the enone chromophore is commonly encountered in 2-cyclohexenone derivatives and it is a source of significant rotatory strength contribution to the electronic circular dichroism spectra. It is shown that the two lowest-energy transitions in acrolein and 2-cyclohexenone and its derivatives are n(C=O)-π(C=O)* and π(C=C)-π(C=O)*, as expected, while the shorter-wavelength (below 200 nm) transitions are of more complex nature. In 2-cyclohexenone and its alkyl derivatives it is predominantly a mixture of π(C=C)-π(C=C)* and π(C=C)-σ* transitions, whereas the presence of hydroxy substituent results in a dominant contribution due to the n(OH)-π(C=O)* transition. A generalized model for correlation of the CD spectra of 2-cyclohexenones with their structures is presented.     

Structure and atropisomerisation of new diastereomeric gossypol Schiff bases with (R)-(+)-2-amino-3-benzyloxy-1-propanol studied by NMR,ECD and DFT methods

Gossypol Schiff base with (R)-(+)-2-amino-3-benzyloxy-1-propanol 1 was synthesised and resolved by HPLC method into diastereomers to study their atropisomerisation process. The spectroscopic analysis performed by one- and two-dimensional NMR, UV–vis and FT-IR methods indicated that the compound exists in solution as an enamine-oxo tautomer. The ECD measurements and TD-DFT calculations allowed us to unambiguously determine the configuration about the axially chiral biaryl moiety of 1. The conditions of the atropisomerisation processes of diastereopure gossypol Schiff bases (S_AX,R)-1 and (R_AX,R)-1 were determined on the basis of ECD and NMR measurements. Exposure of the diastereomers of 1 to sunlight and to the light at λ = 254 nm significantly accelerated the atropisomerisation when compared to its rate in the dark.     

Three dimensional film electrode prepared from oppositely charged carbon nanoparticles as efficient enzyme host

Three dimensional carbon film electrodes were prepared from oppositely charged carbon nanoparticles (ca. 9 to 18 nm diameter) by a layer-by-layer approach. This was done by alternative immersion of indium tin oxide plates into suspension of positively and negatively charged particles. A stable film is formed already after single immersion and withdrawal step as confirmed by scanning electron microscopy. Up to ten immersion and withdrawal steps can be used to systematically increase the amount of nanoparticulate carbon material. The capacitive current density and current density of hydrogen peroxide reduction are proportional to the number of immersion and withdrawal steps. The same can be seen for adsorbed redox active 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate). After adsorption of bilirubin oxidase into the film efficient bioelectrocatalytic dioxygen reduction is observed.     

Electrodeposition of gold nanoparticles at a solid|ionic liquid|aqueous electrolyte three-phase junction

Gold nanoparticles have been electrodeposited on an electrode through electrogeneration at an ITO|AuCl₄^? solution in an ionic liquid|aqueous electrolyte three-phase junction. The electrodeposition was carried out by inverted double-pulse potential chronoamperometry. The direct reduction of AuCl₄^? ions at the electrode is followed by a counterion transfer through the liquid|liquid interface. Contrary to the electrodeposition from a single ionic liquid phase, scanning electron microscopy reveals that the shape of the resulting nanoparticles is highly angular and well-developed with a diameter of 110 ± 30 nm. Catalytic oxidation of glucose on the modified electrode is demonstrated.     

Bonding in β-diketiminate boron and its analogues

Bonding analysis in β-diketiminate boron and related systems has been performed. For the optimized geometries (MP2/aug-cc-pVTZ), the post-SCF electron density function has been produced and its topological parameters have been analyzed according to Atoms in Molecules Quantum Theory approach. The B–N bond has characteristics similar to those found for TM–ligand bonding. The symmetric character of the B–N interaction found for the β-diketiminate boron results from the fully π-electron delocalized character of the β-diketiminate moiety. If the π-electron system in NCCCN sequence of bonds is localized, the asymmetric B–N bonding is enforced. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.