The 99Ru Mössbauer spectrum of β-RuCl3

The ⁹⁹Ru nuclear quadrupole interaction in β-RuCl₃ can be related to the large trigonal distortion at the ruthenium site. The ratio of the quadrupole moments has been determined to be Q_e/Q_g = +3.06 ± 0.10, and it is confirmed that Q_c and Q_g are both positive.     

Well-defined, organic nanoenvironments in water: the hydrophobic effect drives a capsular assembly

The synthesis of a water-soluble, deep-cavity cavitand is reported. A blend of molecular curvature and amphiphilicity, this molecule has a hydrophobic concave surface and a hydrophilic convex surface. As a result, in aqueous solution and in the presence of a guest molecule, the host self-assembles to form a capsular assembly with an interior cavity large enough to entrap steroidal guests.     

The photodegradation of poly(vinyl chloride)—V The effect of wavelength of irradiation on the dehydrochlorination reaction

For a purified sample of poly(vinyl chloride), it is found that radiation of wavelength less than 300 nm causes dehydrochlorination. It appears that polychromatic radiation yields a constant ratio of concentrations of polyenes, even from the very early stages of reaction. It is proposed that energy transfer is an important step in the photodecomposition of poly(vinyl chloride).     

A study of the new perovskite solid solution series SrFexRu1−xO3−y by ruthenium-99 and iron-57 Mössbauer spectroscopy

The magnetic and structural properties of the solid solution SrFe_xRu_1?xO_3?y (0 ? x ? 0.5) have been studied using ⁵⁷Fe and ⁹⁹Ru Mössbauer spectroscopy and other techniques. These phases, which are here reported for the first time, have a distorted perovskite structure. The iron substitutes exclusively as Fe³⁺ and thereby causes oxygen deficiency, but has little effect on the magnetic behaviour of the Ru⁴⁺ until x > 0.2, whereupon the metallic band system begins to revert to a localized electron structure. The properties of a sample with x = 0.3 are complex and intermediate in character. For x > 0.3 the oxygen deficiency is reduced by substantial oxidation to Ru⁵⁺ until at x = 0.5 the system corresponds to Sr₂Fe³⁺Ru⁵⁺O₆.     

Dipolar interactions and origin of spin ice in ising pyrochlore magnets

Recent experiments suggest that the Ising pyrochlore magnets Ho2Ti2O7 and Dy2Ti2O7 display qualitative properties of the nearest-neighbor "spin ice" model. We discuss the dipolar energy scale present in both these materials and discuss how spin-ice behavior can occur despite the presence of long-range dipolar interactions. We present results of numerical simulations and a mean field analysis of Ising pyrochlore systems. Based on our quantitative theory, we suggest that the spin-ice behavior in these systems is due to long-range dipolar interactions, and that the nearest-neighbor exchange in Dy2Ti2O7 is antiferromagnetic.     

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Ohne Zusammenfassung     

Characterization of an exception to the ‘even‐electron rule’ upon low‐energy collision induced decomposition in negative ion electrospray tandem mass spectrometry

Electrospray‐generated precursor ions usually follow the ‘even‐electron rule’ and yield ‘closed shell’ fragment ions. We characterize an exception to the ‘even‐electron rule.’ In negative ion electrospray mass spectrometry (ES‐MS), 2‐(ethoxymethoxy)‐3‐hydroxyphenol (2‐hydroxyl protected pyrogallol) easily formed a deprotonated molecular ion (M‐H)^? at m/z 183. Upon low‐energy collision induced decomposition (CID), the m/z 183 precursor yielded a radical ion at m/z 124 as the base peak. The radical anion at m/z 124 was still the major fragment at all tested collision energies between 0 and 50 eV (E_lab). Supported by computational studies, the appearance of the radical anion at m/z 124 as the major product ion can be attributed to the combination of a low reverse activation barrier and resonance stabilization of the product ions. Furthermore, our data lead to the proposal of a novel alternative radical formation pathway in the protection group removal of pyrogallol. Copyright © 2009 John Wiley & Sons, Ltd.     

A versatile and modular approach to functionalisation of deep-cavity cavitands via"click" chemistry

The surface modification of deep-cavity cavitands has been demonstrated by using the azide-alkyne "click" coupling to attach dendritic macromolecules or linear polymers onto their periphery. The resulting set of macromolecular cavitands exhibited tuneable solubility yet retained the ability to encapsulate guest molecules.