Localized Pd overgrowth on cubic Pt nanocrystals for enhanced electrocatalytic oxidation of formic acid

Binary Pt/Pd nanoparticles were synthesized by localized overgrowth of Pd on cubic Pt seeds for the investigation of electrocatalytic formic acid oxidation. The binary particles exhibited much less self-poisoning and a lower activation energy relative to Pt nanocubes, consistent with the single crystal study.     

Concise Total Synthesis of Enigmazole A

An efficient entry into the phosphorylated marine macrolide enigmazole A is described. Enigmazole A interferes with c‐Kit signaling by an as yet unknown mode of action and is therefore a potential lead in the quest for novel anticancer agents. Key to success is a gold‐catalyzed cascade comprising a [3,3]‐sigmatropic rearrangement of a propargyl acetate along the periphery of a macrocyclic scaffold, followed by a transannular hydroalkoxylation of the resulting transient allenyl acetate. This transformation mandated the use of a chiral gold catalyst to ensure a matching double‐asymmetric setting. Other noteworthy steps are the preparation of the oxazole building block by a palladium‐catalyzed C?H activation, as well as the smooth ring‐closing alkyne metathesis of a diyne substrate bearing a propargylic leaving group, which has only little precedent.     

Intermediates in the palladium-catalysed reactions of 1,3- dienes: IV. The reactions of η1,η3-octadienediyl-palladium complexes with alkynes and activated alkenes

The reactions of [Pd(PR₃)(η¹,η³-C₈H₁₂)] complexes with the dimethyl ester of acetylene dicarboxylic acid involves an unusual 1,3-addition of the alkyne to an allyl fragment to give cyclopentene-substituted η³-allylpalladium complexes. p-Benzoquinone and 5-hydroxynaphthoquinone react similarly.     

Electrostatic and Non‐covalent Interactions in Dicationic Imidazolium–Sulfonium Salts with Mixed Anions

A series of thioether‐functionalised imidazolium salts have been prepared and characterized. Subsequent reaction of the thioether‐functionalised imidazolium salts with iodomethane affords imidazolium–sulfonium salts composed of doubly charged cations and two different anions. Imidazolium–sulfonium salts containing a single anion type are obtained either by a solvent extraction method or by anion exchange. The imidazolium–sulfonium salts undergo a methyl‐transfer reaction on exposure to water, giving rise to a new, singly charged imidazolium salt with iodide introduced at the 2‐position of the imidazolium ring. Crystal structures of some of the imidazolium–sulfonium salts were determined by X‐ray crystallography providing the topology of the interactions between the dications and the anions. Electrospray ionization mass spectrometry and quantum‐chemical calculations were used to rationalise the relative strength of these interactions.     

Synthesis of novel near-infrared cyanine dyes for metal ion determination

Four heptamethine cyanine dyes 10, 19–21 containing an ortho-hydroxy-carboxy functionality for metal ion complexation and absorbing at λ max (methanol) 761±1 nm have been synthesized.     

A new approximation algorithm for the multilevel facility location problem

In this paper we propose a new integer programming formulation for the multilevel facility location problem and a novel 3-approximation algorithm based on LP-rounding. The linear program that we use has a polynomial number of variables and constraints, thus being more efficient than the one commonly used in the approximation algorithms for these types of problems.     

Thermomechanical,calorimetric and magnetic properties of a Ni–Ti shape-memory alloy wire

Journal of Thermal Analysis and Calorimetry - In this work, some physical properties of a commercial Ni–Ti (nitinol) shape-memory alloy with cylindrical geometry (wire) were investigated; the...