The applicability of thianthrene 5-oxide as a mechanistic probe for distinguishing between the electrophilic and the nucleophilic character in oxygen-transfer processes from a series of Mo(V1) and W(V1) peroxo complexes has been investigated. In almost all the cases examined, the predominant formation of the corresponding sulfone has been observed. This would indicate a nucleophilic nature of the oxidants, which is, however, at odd with known chemistry of such species. In fact, competitive experiments performed by employing pchlorophenyl methyl sulfide and phenyl methyl sulfoxide together in equivalent amounts as substrates revealed the preferred oxidation of the former over the latter as expected for an electrophilic oxygen transfer. These apparently contrasting findings are interpreted in terms of an incursion of radical pathways in the oxidation reactions of thianthrene 5-oxide by these peroxo complexes.

New asymmetric (salen)Mn III and UO 2 complexes containing a calix [4]arene unit in the ligand framework were synthesized. The UO 2 complexes were characterized by 1 H-, 13 C-, 2D TOCSY and T-ROESY NMR spectroscopy. Furthermore, the structure of one UO 2 complex was determined by singlecrystal X-ray analysis. The data showed that UO 2 complexes, which can be considered in first approximation models of the Mn=O oxidant active species, possess a chiral pocket and

Fancy a copper? A sensing system for copper(I) ions, based on the interplay between a “classical” chemosensor and a fluorescent silica nanoparticle, is presented (see scheme). The occurrence of properly designed energy transfer processes and the observed increase of the affinity of the nanosystem towards Cu+ improve sensor performance at low metal ion concentrations in living cells.

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A new Cu(I) probe (OBEP-CS1), bearing an alkyl-pyridinium moiety to get complete water solubility, was synthesized. Fluorescence titrations support copper binding and high selectivity in a water solution whereas formation of aggregates was excluded by DOSY experiments. The detection capability for intracellular Cu(I), especially localized in mitochondria, was demonstrated in differentiated neuroblastoma cells by confocal microscopy.