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The article focuses on radicals with multiple personalities, based from combined theoretical and experimental approach. It mentions that distonics ions are ions that contain both positive and negative charges. It states that tetrathiofulvalene-nitronylnitroxide (TTF-NN) complex is an example of orbital energy-level conversion, in which radical centre of singly occupied molecular orbital (SOMO) has lower energy compared to doubly occupied molecular orbital (HOMO). It adds that mass spectrometrist Stephen Blanskby and computational chemist Michelle Coote has suggested that orbital conversion in distonic anion are common that usually thought.

UV-irradiation of a self-assembled benzophenone bis-urea macrocycle generates μ m amounts of radicals that persist for weeks under ambient conditions. High-field EPR and variable-temperature X-band EPR studies suggest a resonance stabilized radical pair through H-abstraction. These endogenous radicals were applied as a polarizing agent for magic angle spinning (MAS) dynamic nuclear polarization (DNP) NMR enhancement. The field-stepped DNP enhancement profile exhibits a sharp peak with a maximum enhancement of ϵon/off=4 superimposed on a nearly constant DNP enhancement of ϵon/off=2 over a broad field range. This maximum coincides with the high field EPR absorption spectrum, consistent with an Overhauser effect mechanism. DNP enhancement was observed for both the host and guests, suggesting that even low levels of endogenous radicals can facilitate the study of host-guest relationships in the solid-state. [ABSTRACT FROM AUTHOR]

The solution photochemistry of bis(phenylpyrrolidinonyl)ketones (R,R)-1b and (S,S)-1b exhibited a remarkably high memory of, chirality. Stereospecific decarbonylation to products (RR)-3b and (S,S)-3b, respectively, occurred with an ee of Ca. 80%. The reaction is thought to occur along the single state manifold by sequential Norrish type-1 α-cleavage, decarbonylation, and radical-radical combination in a time scale that is comparable to that required for the radical intermediate to expose its other enantiotopic face by rotation about an axis perpendicular to that of the p orbital (ca. 3-7 ps). The absolute configuration of a key intermediate and that of ketone (R,R)-1b were determined by single-crystal X-ray diffraction and the ee values of the photochemical products with the help of chiral shift reagent (+)-Eu(tfc)[sub3] and chiral LC- MS/MS. On the basis of the ee and de values at 25 °C, it could be determined that Ca. 70% of the bond forming events occur with double memory of chirality, Ca. 21% occur after rotation of one radical to form the meso product (R,S)-3b, and only 9% occur after double rotation to form the opposite enantiomer. This report represents the first example of a doubly enantiospecific Norrish type-I and decarbonylation reaction in solution and illustrates potentially efficient ways to obtain compounds with adjacent stereogenic quaternary centers. [ABSTRACT FROM AUTHOR]