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Abstract: Various N-substituted azaphosphatranes have been prepared and successfully applied to the synthesis of styrene carbonates from CO2 and epoxides. Enhancement of the catalytic properties of the azaphosphatrane was achieved upon pre-organization of the active site through hydrogen-bonding. [Copyright &y& Elsevier]

The iiii stereoisomer of the tetrathiophosphonate-calix[4]resorcinarene host 1 exhibited excellent extraction properties towards soft metal ions, with a better affinity for Ag+ (91%), than for Tl+ (38%) and Hg2+ (16%). The extraction of other picrate salts (Cu2+, Ni2+, Co2+, Zn2+, Cd2+, Pb2+) was not detected. The stoichiometry and the structure of the Hg2+, Tl+ and Ag+ complexes were studied by NMR in solution and gave respectively 1:1, 1:1 and 1:2 host–guest complexes. The formation of the self-assembled 12·(AgPic)4 complex was independent on the anion and only observed with silver(I) ion. [Copyright &y& Elsevier]

The resolution of racemic bromofluoroacetic acid (BrFHCCO2H) 1 was effected by crystallisation of its diastereoisomeric α-methylbenzylamine salts. The crystal structure of the p salt (+)-3a {(+)-BrFHCCO2H·(R)-(+)-α-methylbenzylamine} was solved by X-ray crystallography and the (S)-(+)/(R)-(−) absolute configuration was established for 1. Diastereoisomeric esters 5a and 5b, obtained by addition of bromofluoroacetic acid to enantiomerically pure epoxychroman 4, were used to determine the enantiomeric excess of 1 by 19F NMR. Moreover, the diastereoisomerically pure ester 5a, resulting from addition of enantiomerically pure (+)-1 to 4, gave single crystals and its X-ray crystal structure corroborated the (S)-(+)/(R)-(−) absolute configuration of 1. [Copyright &y& Elsevier]

Abstract: For detection of biological events in vitro, sensors using hyperpolarized 129Xe NMR can become a powerful tool, provided the approach can bridge the gap in sensitivity. Here we propose constructs based on the non-selective grafting of cryptophane precursors on holo-transferrin. This biological system was chosen because there are many receptors on the cell surface, and endocytosis further increases this density. The study of these biosensors with K562 cell suspensions via fluorescence microscopy and 129Xe NMR indicates a strong interaction, as well as interesting features such as the capacity of xenon to enter the cryptophane even when the biosensor is endocytosed, while keeping a high level of polarization. Despite a lack of specificity for transferrin receptors, undoubtedly due to the hydrophobic character of the cryptophane moiety that attracts the biosensor into the cell membrane, these biosensors allow the first in-cell probing of biological events using hyperpolarized xenon. [Copyright &y& Elsevier]

Abstract: An inherently chiral ABii diphosphonato cavitand (±)-4 bearing a single quinoxaline bridging moiety was synthesized and resolved by chiral HPLC. Its chiroptical properties were investigated and VCD experiments allowed the determination of its absolute configuration. Distinguishable diastereomeric complexes in solution with l-adrenaline were observed by 1H and 31P NMR together with a noticeable enantio-discrimination at 253K (dr ∼2:1) in favor of the dextrorotatory cavitand (+)-4. [ABSTRACT FROM AUTHOR]