Tetranuclear Pt<Subscript>2</Subscript>Cu<Subscript>2</Subscript> Complex with a Staircase-Shaped Chain Aggregate in the Solid State

The reaction of the tetranuclear cyanide aquo complex [{Pt(CN)₄Cu(bipy)(H₂O)}₂]· 2H₂O with aqueous ammonia produces the new tetranuclear ammino-containing product [{Pt(CN)₄Cu(bipy)(NH₃)}₂] (1), with terminal cyanide groups and with NH₃ coordinated to the Cu atom. The distorted trigonal bipyramidal coordination about copper in 1 differs from the square-pyramidal coordination present in the starting material. The bipyridine ligand in 1 is nearly perpendicular to the tetranuclear core of the molecule, as opposed to its coplanar disposition in the aquo complex. The two platinum atoms of the tetranuclear core in 1 form Pt···Pt interactions of 3. 2390(8) Å with platinum atoms of neighboring molecules, producing an echelon-shaped supramolecular chain held together by staggered (CN)₄Pt···Pt(CN)₄ linkages, an aggregate structure which does not have a precedent in chemistry derived from the Pt(CN)₄ building block.     

Stereoselective syntheses of 1,4-dideoxy-1,4-imino-octitols and novel tetrahydroxyindolizidines

A new route for the preparation of four new indolizidines, (1R,2S,6S,7S,8aS)- and (1R,2S,6R,7R,8aS)-1,2,6,7-tetrahydroxyindolizidine (30 and 32) and (1S,2R,7S,8S,8aR)- and (1S,2R,7R,8R,8aR)-1,2,7,8-tetrahydroxyindolizidine (44 and 46), is reported. The synthesis is based on Knoevenagel homologation of the readily available enantiomerically pure pyrrolidin-carbaldehydes 13 and 37followed by asymmetric dihydroxylation of the subsequent alkenyl pyrrolidines and cyclization of the corresponding imino-octitols. The new indolizidines and their precursors (imino-octitols 20, 25, 26) and indolizidinones 28a and 28b have been tested for inhibitory activities toward 26 glycosidases. The enzymatic inhibition of trans-7-hydroxy-d-(-)-swainsonine (44) toward alpha-mannosidases is similar to that described for trans-7-hydroxy-l-(+)-swainsonine (11b) toward naringinase (alpha-l-rhamnosidase from Penicillium decumbens).     

Introduction of C-Sulfonate Groups into Disaccharide Derivatives

To prepare C-sulfonate derivatives of disaccharides two different strategies were followed. Thus 6- and 6′-C-sulfocellobiosides 4 and 10–12 were prepared starting from a suitably protected cellobioside. The 6′-C-sulfoaminocellobioside 18 was prepared by construction of the molecule through a glycosylation reaction. In both cases, the synthetic pathway involves regioselective tosylation, introduction of a sulfur atom by nucleophilic displacement with potassium thioacetate and oxidation with hydrogen peroxide.     

Polymer chain conformation of copolymers with different monomer size: C NMR spectroscopy and MALS study

Copolymer composition, distribution and molecular size of the comonomer influence the final properties of polymer materials. Such influence can be followed from the effect on the chain conformation in solution determined from the scaling law between radius of gyration and molecular weight.     

Hypernuclear physics at \overline{\mbox{P}} anda

Samples obtained as a result of the valleriite synthesis process under different conditions (temperature and proportion Cu:Fe:Mg in the initial mixture) were investigated by ⁵⁷Fe M?ssbauer spectroscopy with attraction data of X-ray diffraction. Parameters of hyperfine interactions for valleriite were determined and crystal chemical identification of ⁵⁷Fe subspectra was carried out. It was found that valleriite was formed in samples synthesized at 150°C and 180°C and not formed in samples synthesized at 250°C.     

Ranking ranges in cross-efficiency evaluations

The existence of alternate optima for the DEA weights may reduce the usefulness of the cross-efficiency evaluation, since the ranking provided depends on the choice of weights that the different DMUs make. In this paper, we develop a procedure to carry out the cross-efficiency evaluation without the need to make any specific choice of DEA weights. The proposed procedure takes into consideration all the possible choices of weights that all the DMUs can make, and yields for each unit a range for its possible rankings instead of a single ranking. This range is determined by the best and the worst rankings that would result in the best and the worst scenarios of each unit across all the DEA weights of all the DMUs. This approach might identify good/bad performers, as those that rank at the top/bottom irrespective of the weights that are chosen, or units that outperform others in all the scenarios. In addition, it may be used to analyze the stability of the ranking provided by the standard cross-efficiency evaluation.     

Shedding light on the mitochondrial matrix through a functional membrane transporter

The first fluorescent probes that are actively channeled into the mitochondrial matrix by a specific mitochondrial membrane transporter in living cells have been developed. The new functional probes (BCT) have a minimalist structural design based on the highly efficient and photostable BODIPY chromophore and carnitine as a biotargeting element. Both units are orthogonally bonded through the common boron atom, thus avoiding the use of complex polyatomic connectors. In contrast to known mitochondria-specific dyes, BCTs selectively label these organelles regardless of their transmembrane potential and in an enantioselective way. The obtained experimental evidence supports carnitine–acylcarnitine translocase (CACT) as the key transporter protein for BCTs, which behave therefore as acylcarnitine biomimetics. This simple structural design can be readily extended to other structurally diverse starting F-BODIPYs to obtain BCTs with varied emission wavelengths along the visible and NIR spectral regions and with multifunctional capabilities. BCTs are the first fluorescent derivatives of carnitine to be used in cell microscopy and stand as promising research tools to explore the role of the carnitine shuttle system in cancer and metabolic diseases. Extension of this approach to other small-molecule mitochondrial transporters is envisaged.

A BODIPY derivative of carnitine enters mitochondria regardless of their membrane potential and in an enantioselective way through a specific mitochondrial membrane transporter in living cells.     

Ultrasound-assisted extraction of antimony and cobalt from inorganic environmental samples using a cup-horn sonoreactor prior to their determination by electrothermal-atomic absorption spectrometry

A simple, fast and reliable method is described for the quantitative extraction of Sb and Co from inorganic environmental matrices containing variable amounts of silicates prior to their determination by electrothermal-atomic absorption spectrometry. The method is based on the ultrasound-assisted extraction of both elements using the mixture 20% v/v HF + 20% v/v HNO₃ as extractant. The extraction procedure was carried out in closed Eppendorf vials immersed in a cup-horn sonoreactor for 20?min. Once extraction has been accomplished, the supernatant liquid is separated from the solid phase and subsequently transferred into the autosampler of the instrument. A two-level full factorial design (2⁴) was applied for screening optimisation of the variables influencing the ultrasonic extraction. These variables were: sonication time; amplitude of the ultrasound energy; nitric and hydrofluoric acid concentrations. MLDs were 0.20 and 0.06?µg?·?g^?1 for Sb and Co, respectively. Between-batch precision values, expressed as relative standard deviations (n?=?3), were less than 5.5 and 9.6% for Sb and Co, respectively. The method was evaluated using a wide variety of inorganic certified reference materials, such as SRM 2702 (Marine Sediment), SRM 2782 (Industrial Sludge), BCR 176R (Fly Ash), SRM 1633b (Coal Fly Ash) SRM 2710 (Montana Soil) and SRM 2711 (Montana Soil).