CARS in combustion: Prospects and problems

The principles of CARS are reviewed. This technique has achieved important successes in combustion, but its use has been limited mostly to temperature measurements. We demonstrate the feasibility of sensitive single-shot concentration measurements (to 0.2%) with fair accuracy, in spite of the adverse effects of turbulence and saturation. Even better sensitivities will be achieved using electronic resonance enhancement.     

Formation of Chiral Structures in UV-Initiated Formose Reaction

It has been found that the UV-initiated formose reaction in an extremely concentrated aqueous solution of formaldehyde gives sugars and other biologically significant chiral compounds with sp³-hybridized carbon atom. The reaction leads to an optically active condensed phase, which is a result of the spontaneous spatial separation of enantiomers in the racemate into the antipodes, similarly to the separation of enantiomers of different chirality sign in the famous Pasteur experiments. In our opinion, such a scenario is as close as possible to the actually realized de novo scenario of synthesis of chiral prebiotic molecules and matrices.     

Sequestering agent for uranyl chelation: new binaphtyl ligands

The synthesis of phosphonate, sulfocatecholamide (CAMS) and hydroxypyridinone (HOPO) binaphtyl ligands is presented. Their binding abilities for uranyl cation were determined by UV spectrophotometry in aqueous media versus pH. These titrations showed that the efficiency of these chelating agents depends on the nature of the chelating group. Each ligand shows a more or less pronounced affinity towards uranium. While the bisphosphonate compound did not show any affinity towards the uranyl ion, the BINHOPO derivative exhibits significant affinity at acidic and neutral pH while the BINCAMS is more efficient at basic pH.     

Sydnone-Cyanines as Clickable Probes for Fluorescent Labelling

The synthesis of four clickable sydnone-heptamethine cyanine derivatives is described in this article. The synthetic route is based on a palladium-cross coupling reactions of sydnone boronates affording the desired sydnone-cyanine conjugates in only five steps. These compounds were shown to react smoothly with cyclooctynes to form the corresponding pyrazoles clicked products quantitatively at room temperature and with rate constants up to 18 m ⁻¹ ⋅ s⁻¹, affording interesting new tools for biorthogonal fluorescent labelling of (bio)molecules. Fluorescence properties of both sydnone- and pyrazole-cyanines are described, as well.     

Modern Strategies for Carbon Isotope Exchange

In contrast to stable and natural abundant carbon-12, the synthesis of organic molecules with carbon (radio)isotopes must be conceived and optimized in order to navigate through the hurdles of radiochemical requirements, such as high costs of the starting materials, harsh conditions and radioactive waste generation. In addition, it must initiate from the small cohort of available C-labeled building blocks. For long time, multi-step approaches have represented the sole available patterns. On the other side, the development of chemical reactions based on the reversible cleavage of C−C bonds might offer new opportunities and reshape retrosynthetic analysis in radiosynthesis. This review aims to provide a short survey on the recently emerged carbon isotope exchange technologies that provide effective opportunity for late-stage labeling. At present, such strategies have relied on the use of primary and easily accessible radiolabeled C1-building blocks, such as carbon dioxide, carbon monoxide and cyanides, while the activation principles have been based on thermal, photocatalytic, metal-catalyzed and biocatalytic processes.