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Eight simple amides have been subjected to UV irradiation in the presence of either MNP or NO. In all cases radical species were generated: these were detected by means of EPR spectroscopy in the form of different nitroxides resulting from the trapping of the primary radicals. NO acted as a double spin trap, scavenging a radical to afford a diamagnetic nitroso derivative that in turn acted as trap towards another radical unit. As amido-groups are present in components of skin tissue and may be present in many therapeutic or cosmetic products used as skin sunscreen, and NO is a ubiquitous endogenous reactive species, the nitroxides detected in the present studies might participate in radical processes triggered by sun exposure and resulting in damages, even severe, of biological tissues. (C) 2012 Elsevier Ltd. All rights reserved.

High energy radiation treatment of foodstuff for microbial control and shelf-life extension is being used in many countries. However, for consumer protection and information, the European Union has adopted the Directives 1999/2/EC and 1999/3/EC to harmonize the rules concerning the treatment and trade of irradiated foods in EU countries. Among the validated methods to detect irradiated foods the EU directives also include Electron Paramagnetic Resonance (EPR/ESR) spectroscopy. We describe herein the use of EPR for identification of four species of bivalve mollusks, i.e. brown Venus shells (Callista chione), clams (Tapes semidecussatus), mussels (Mytilus galloprovincialis) and oysters (Ostrea edulis) irradiated with 60Co γ-rays. EPR could definitely identify irradiated seashells due to the presence of long-lived free radicals, primarily CO2−, CO33−, SO2− and SO3− radical anions. The presence of other organic free radicals, believed to originate from conchiolin, a scleroprotein present in the shells, was also ascertained. The use of one of these radicals as a marker for irradiation of brown Venus shells and clams can be envisaged. We also propose a dosimetric protocol for the reconstruction of the administered dose in irradiated oysters.

Treatment of food with ionising radiations in order to increase its shelf-life is largely employed in many countries. Because of restrictions issued by different governments on the use of this technique, in addition to the identification of irradiated foodstuffs, it may be important to determine the radiation dose administered to the foodstuffs. An EPR based protocol to reconstruct the administered dose from samples of irradiated meats (rabbit, pork and duck) within an uncertainty of ±25% is reported. © 2010 Elsevier Ltd.

The radical cation and anion of the title compound were obtained either by treatment with mercury trifluorocatetate in trifluoroacetic acid or by reduction with potassium in tetrahydrofurane. For both species the ESR spectra indicated magnetic non-equivalence of the two phosphorus atoms, as well as of the two methyl groups. Spectra attributed to the corresponding spin adducts were also observed when reacting the title compound with in situ-generated alkoxyl and thiyl radicals. MO calculations carried out for both the ionic radicals and the neutral spin adducts led to questioning the actual nature of some of the latter species.

The antimalaric drug artemisinin (QHS) is believed to operate through a mechanism initiated with the cleavage of its endoperoxidic bond induced by transition metal ions. An ESR investigation of the reaction of QHS with human serum in the presence of two spin trapping agents has led to the detection of spin adducts of carbon-centred radicals. Experiments carried out replacing the human serum with iron(II) salts led to the observation of the same spin adducts, thus supporting previous suggestions that also in vivo the drug operates via a radical-based mechanism. UV irradiation of QHS also led to the trapping of transient free radicals.

This paper is aimed at providing an overview of our studies on the title compounds as spin trapping agents, and at emphasising the links between purely cognitive, academic research and industrial applications. Phosphoryl- and thiophosphoryl-dithioformates exhibit a comparable and interesting spin trapping ability, their efficiency being analogous to that of some aromatic thioketones. The spectral hyperfine structure may provide valuable information on the nature of the trapped radical but the phosphorus hfs constant cannot be used as an useful indicator. Thionformates are less efficient spin traps than the corresponding dithioformates, being inert towards stabilised radicals such as benzyl or relatively hindered radicals as tert-butoxyl. In no case could spin adducts to thiolformates be detected, this being an indication that their carbonyl group is significantly deactivated with respect to that of organic and organometallic ketones. Because of their ability in trapping either alkyl or alkoxy radicals both kind of dithioformates were exploited as stabilisers in the processing of such polymers as polypropylene, but their outstanding performance could not compensate for some organoleptic drawbacks that were intrinsic of the thiocarbonyl function. A much more promising application of dithioesters is instead their use as RAFT chain transfer agents in the controlled polymerisation of styrene. Preliminary experiments with benzyl diethoxyphosphoryldithioformate have afforded polystyrene with a polydispersity as low as 1.17, but further studies are needed to fully elucidate the RAFT-polymerisation mechanism and to optimise its outcome.

New physical evidence to support a ketyl radical-anion mechanism for the [3,3]-sigmatropic rearrangement is presented. With use of EPR spectroscopy, spectra are observed that can be attributed to 8, an acyl radical-anion species resulting from a [3,3]-rearrangement; this also functions as a key intermediate in the process. The spectrum of an additional paramagnetic species resulting from further addition of tin-centered radicals to the reaction product was also observed.