Silylated thiiran-1-oxides: Structure,ring opening and conversion to a benzothiophene.

Silylated thiirans upon oxidation with peroxyacids do not give exclusively the corresponding S-oxides but, in addition some products derived from ring opening. The stereochemistry of the oxidation to thiiran-1-oxides is $\text{anti}$ to the silyl group as demonstrated by X-ray analysis.     

Hydrido- and hydroxo-cyanoalkyl complexes of platinium(II). Reactivity of the PtH and PtOH bonds towards nucleophiles and electrophiles

Reactions of the PtH and/or PtC bonds of the hydridocyanoalkyl complexes cis- or trans-PtH[(CH₂)_nCN]L₂ (n = 1, 3; L₂ = 2 PPh₃, Ph₂PCHCHPPh₂) are described, viz. reductive elimination induced by CO, PhCCPh, PEt₃, PPhMe₂, cis-Ph₂PCHCHPPh₂ to give Pt(CO)₂L₂, PtL₂(PhCCPh), PtL₂, PtL(PPhMe₂)₃, PtL₂(Ph₂PCHCHPPh₂) (L = PPh₃), respectively, and cleavages by acids, halogens and alkyl halides.The monomeric hydroxo complexes cis-Pt(OH)[(CH₂)_nCN]L₂ were shown to be intermediates in the synthesis of PtH[(CH₂)_nCN]L₂ from cationic cyanoalkyl complexes in alcoholic NaOH. Their characterisation and the reactions of the PtOH bond with activated methyl groups are reported.     

Radical reduction of aromatic azides to amines with tributylgermanium hydride

[reaction: see text] Aromatic azides are inert toward tributylgermanium hydride under thermal conditions in the absence and in the presence of a radical initiator but in the presence of catalytic amounts of benzenethiol undergo fast reaction, yielding reduced anilines and 2-germylated derivatives in high overall yields.     

Conformational studies by dynamic NMR. 89. Stereomutation and cryogenic enantioseparation of conformational antipodes of hindered aryl oximes

Aryl benzyl oximes having the configuration Z give rise to stereolabile atropisomers when a halogen atom is present in the ortho position of the aryl moiety, as a consequence of the restricted aryl-CN bond rotation. By means of dynamic (1)H NMR spectroscopy it has been possible to determine the corresponding rotation barrier, hence the lifetime of the atropisomers that, in the case of the iodine derivative, was found sufficiently long as to allow a physical separation to be achieved on an appropriately cooled enantioselective HPLC column. Comparison of the barriers determined by dynamic NMR and dynamic HPLC proved the equivalence of the two techniques. When the iodine atom was substituted by an alpha-naphthyl group, two dynamic processes were observed. That with the lower barrier could be determined by NMR and that with the higher barrier by HPLC, thus outlining the complementarity of these two techniques.     

Influence of Discharge Atmosphere on the Ageing Behaviour of Plasma-Treated Polylactic Acid

The effect of a plasma treatment on polymers is not permanent, since the treated surfaces tend to recover to the untreated state (ageing process). This paper investigates the influence of discharge atmosphere on the ageing behaviour of plasma-treated PLA foils: these foils are plasma-treated with a DBD in 4 different atmospheres (air, nitrogen, argon and helium) and are subsequently stored in air. Results of contact angle and XPS measurements show that the discharge gas has a significant influence on the ageing behaviour of the PLA foils. This influence can be explained by the different cross-linking degree of the plasma-treated surfaces: helium and argon plasma-treated PLA films have a high cross-linking degree, which limits polymer chain mobility and as a result reduces the ageing process. In contrast, the ageing behaviour of air and nitrogen plasma-treated films is more pronounced due to their low cross-linking degree.     

One-pot reactions of bicyclic zinc enolate generated from Ni-catalyzed reductive cyclization to furnish octahydro-4,7-ethanobenzofuran-9-one derivatives

The one-pot reactions of catalytically generated bicyclic zinc enolate with various electrophiles are reported. The zinc enolate as a key intermediate is efficiently delivered from Ni-catalyzed reductive cyclization of alkynyl cyclohexadienone. Employing aldehydes, imine, nitroalkene, and α,β-unsaturated carbonyl compounds as electrophiles, this new class of one-pot reactions gave multi-functionalized cis-hydrobenzofurans and octahydro-4,7-ethanobenzofuran-9-one derivatives in moderate to good yields.     

Structural studies of the cadmium(II) chloride / sparteine system

The reaction of dichlorocadmium(II) and (-)-sparteine (sp) provides two products, [CdCl₂(sp)]) (1) and (Hsp)₃[Cd₂Cl₇] (2). The latter represents one of the rare known examples exhibiting an isolated Cd₂Cl₇^3? trianion. Both products are formed in the same reaction mixture and single crystals of one of the two products can be obtained selectively by crystallization depending on the co-solvent. The formation and structural characterization of (H₂sp)[CdCl₄] (3) is also reported, crystallizing with either dichloromethane (3a) or water (3b) as guest molecules.     

The impact of physiological buffer solutions on zinc oxide nanostructures: zinc phosphate conversion

Zinc oxide (ZnO) nanostructures have been widely used in biosensor applications. However, little attention has been given to the interaction of ZnO structures with physiological buffer solutions. In the present work, it is shown that the use of buffers containing phosphate ions leads to the modification of the ZnO tetrapodal micro/nanostructures when immersed in such solutions for several hours, even at the physiological pH (7.4). ZnO samples designed to be used as transducers in biosensors were immersed in phosphate buffers for several durations at pH = 5.8 and pH = 7.4. Their detailed morphological, structural and optical characterization was carried out to demonstrate the effect of the ZnO interaction with the phosphate ions. The pH had an important role in the ZnO conversion into zinc phosphate, with lower pH promoting a more pronounced effect. After 72 h and at pH = 5.8, a significant amount of the ZnO structures were converted into crystalline zinc phosphate, while immersion during the same time at pH = 7.4 resulted predominantly in amorphous zinc phosphate particles mixed with the original ZnO tetrapods. Photoluminescence spectra show remarkable changes with prolonged immersion times, particularly when the luminescence of the sample was investigated at 14 K. These findings highlight the importance of a careful analysis of the sensing results when phosphate-based buffer solutions are in contact with the ZnO transducers, as the changes observed on the transduction signal during sensing experiments may also comprise a non-negligible contribution from a phosphate-induced transformation of ZnO, which can hamper an accurate assessment of the sensing behavior.