Transition Metal Complexes of a Salen–Fullerene Diad: Redox and Catalytically Active Nanostructures for Delivery of Metals in Nanotubes

A covalently‐linked salen–C₆₀ (H₂L) assembly binds a range of transition metal cations in close proximity to the fullerene cage to give complexes [M(L)] (M=Mn, Co, Ni, Cu, Zn, Pd), [MCl(L)] (M=Cr, Fe) and [V(O)L]. Attaching salen covalently to the C₆₀ cage only marginally slows down metal binding at the salen functionality compared to metal binding to free salen. Coordination of metal cations to salen–C₆₀ introduces to these fullerene derivatives strong absorption bands across the visible spectrum from 400 to 630 nm, the optical features of which are controlled by the nature of the transition metal. The redox properties of the metal–salen–C₆₀ complexes are determined both by the fullerene and by the nature of the transition metal, enabling the generation of a wide range of fullerene‐containing charged species, some of which possess two or more unpaired electrons. The presence of the fullerene cage enhances the affinity of these complexes for carbon nanostructures, such as single‐, double‐ and multiwalled carbon nanotubes and graphitised carbon nanofibres, without detrimental effects on the catalytic activity of the metal centre, as demonstrated in styrene oxidation catalysed by [Cu(L)]. This approach shows promise for applications of salen–C₆₀ complexes in heterogeneous catalysis.     

Paramagnetic properties of cubic RbSm3F10 and KHo3F10

The title compounds crystallize in the cubic KY₃F₁₀ structure, with the rare earth ion occupying a site of tetragonal symmetry. Paramagnetic susceptibilities are compared with predictions based on experimental crystal field parameters, down to temperatures of ∼10 mK.     

Impact of an external radiation field on handheld XRF measurements for nuclear forensics applications

X-ray fluorescence (XRF) is an attractive technique for nuclear forensics applications. We evaluated a handheld XRF device by applying an external radiation field (10 mR/h–17 R/h) using two types of radiography sources: a ⁶⁰Co radiography camera for high-energy gamma emissions and an ¹⁹²Ir radiography camera for several low-energy gamma (0.604, 0.468, and 0.317 MeV) and decay daughter X-ray emissions. External radiation tests proved that radiation, in general, has a significant effect on the dead time or background at dose rates over 1 R/h for both the ¹⁹²Ir and ⁶⁰Co sources.     

The effect of evanescent wave modes on scattering and near-trapping

The effect of evanescent modes on the scattering and near-trappingof small-amplitude waves over axisymmetric topography is investigated.A two-stage numerical implementation, which facilitates an examinationof the resonant frequencies associated with near-trapping, isdeveloped. This is achieved in the latter stage of the procedureby dealing with the progressing and decaying waves separately. Numerical results are given for a selection of bed shapes, andit is found that the evanescent waves can have a significanteffect on scattering. Numerical evidence is found that, forthe selection of bed profiles considered, no new resonant frequenciesare introduced by the inclusion of the decaying wave components,but that the inclusion of these decaying waves does improveprevious approximations to resonant frequencies.     

Wide-angle high-energy proton spectra by 800 MeV/A C,Ne, and Ar beams

Inclusive proton spectra, as well as two-particle correlations, resulting from collisions between energetic nuclei have been measured. Protons associated with large momentum transfers show exponential-type energy distributions having a decay constant about (70–90 MeV)^?1. For light-mass targets a strong two-particle correlation has been observed, which is kinematically consistent with quasi-elastic pp scatterings.     

The Four-Body System Made up of Hydrogen and Antihydrogen

 In view of current interest in the trapping of antihydrogen atoms at low temperatures [1–3], we have investigated the reasons for considering that does not have a bound state. We go on to carry out a four-body variational calculation for s-wave hydrogen-antihydrogen scattering, using the Kohn variational method. This is a continuation of earlier work on interactions [5–7]. Received October 30, 2001; accepted for publication November 21, 2001     

Asymmetric induction in simple [2 + 2] photoadditions

Photochemical cycloaddition of cyclopentene with enone esters $\text{1}$ containing different chiral auxiliaries yielded anti and syn adducts $\text{2}$ and $\text{3}$ in good yield and with moderate to high (79%) enantiomeric excesses.