Validation of microscopic magnetochiral dichroism theory.

Magnetochiral dichroism (MChD), a fascinating manifestation of the light-matter interaction characteristic for chiral systems under magnetic fields, has become a well-established optical phenomenon reported for many different materials. However, its interpretation remains essentially phenomenological and qualitative, because the existing microscopic theory has not been quantitatively confirmed by confronting calculations based on this theory with experimental data. Here, we report the experimental low-temperature MChD spectra of two archetypal chiral paramagnetic crystals taken as model systems, tris(1,2-diaminoethane)nickel(II) and cobalt(II) nitrate, for light propagating parallel or perpendicular to the c axis of the crystals, and the calculation of the MChD spectra for the Ni(II) derivative by state-of-the-art quantum chemical calculations. By incorporating vibronic coupling, we find good agreement between experiment and theory, which opens the way for MChD to develop into a powerful chiral spectroscopic tool and provide fundamental insights for the chemical design of new magnetochiral materials for technological applications.

Dynamics of the platyhelminth fauna of wood ducks in relation to food habits and reproductive state.

The dynamics of the intestinal helminth fauna of wood ducks (Aix sponsa) and the relationship between changes in food habits and helminth populations during the bird's reproductive cycle were studied in southeast Missouri. A total of 11 species of helminths, comprised of four species of trematodes and seven species of cestodes, were recovered from the digestive tracts of 155 wood ducks. All species except one were found in both sexes. Significant differences were found in parasite numbers by season (spring vs. fall), sex, and stage of the reproductive cycle. Helminth infection in both sexes was higher in the spring than during fall courtship; however, the magnitude of the seasonal difference was considerably greater in females. Females contained significantly more helminths than males during spring, but no sex-related differences were detected in the fall. Seasonal changes and sex-related differences in parasite numbers corresponded closely with the consumption of invertebrates that serve as intermediate hosts. The average number of parasites in females was similar during fall courtship and pre-egg-laying, suggesting that little or no new infection occurred during winter. The most intensive infections were found in laying females and were attributed to hyperphagia and increased invertebrate consumption during egg production. A large decrease in the parasite numbers in females between incubation and fall courtship indicated that most of the helminths acquired by laying females were lost during summer; therefore, the long-term effects of the increased infection are probably negligible.

Optically active molecule-based magnets: enantioselective self-assembling, optical, and magnetic properties.

In this short communication we describe the synthesis and the optical and magnetic properties of optically active three dimensional (3D) bimetallic [Cr-Mn] networks [[Delta Cr(III) Delta Mn(II)(ox)(3)][Delta Ru(II)(bpy)(3)]ClO(4)](n)1 - Delta, [[Lambda Cr(III)Lambda Mn(II)(ox)(3)][Lambda Ru(II) (bpy)(3)]ClO(4)](n) 1 - Lambda and [[Delta Cr(III)Delta Mn(II)(ox)(3)][Delta Ru(II)(bpy)(2)p p y]](n) 2 - Delta,[[Lambda Cr(III)Lambda Mn(II)(ox)(3)][Lambda Ru(II)(bpy)(2)ppy]](n) 2 - Lambda (ox = oxalate, bpy = bipyridine, ppy = phenyl-pyridine).

Rational design of three-dimensional (3D) optically active molecule-based magnets: synthesis, structure, optical and magnetic properties of ([Ru(bpy)3](2+), ClO4(-), [Mn(II) Cr(III)(ox)3](-))n and ([Ru(bpy)2ppy](+), [M(II)Cr(III)(ox)3](-))n, with M(II) = Mn(II), Ni(II). X-ray structure of ([deltaRu(bpy)3](2+), ClO4(-), [deltaMn(II)DeltaCr(III)(ox)3](-))n and ([lambdaRu(bpy)2ppy)](+), [lambdaMn(II)lambdaCr(III)(ox)3](-))n.

To elucidate the relation between structural and magnetic properties, we have synthesized molecular materials having both Cotton effects and a ferromagnetic long range order. Such optically active 3D molecule-based magnets were rationally designed using the enantioselective template effect of optically active cations, namely Delta or Lambda [Ru(bpy)3, ClO4](+) or Delta or Lambda [Ru(bpy)3ppy](+) (bpy = bipyridine; ppy = phenylpyridine). Such cations are able to template the formation of optically active 3D anionic networks in which transition metal ions (Cr-Mn) and (Cr-Ni) are connected by oxalate ligands (ox). Following this strategy, we described the synthesis of ([Ru(bpy)3](2+), ClO4(-), [Mn(II)Cr(III)(ox)3](-))n and ([Ru(bpy)2ppy](+), [M(II)Cr(III)(ox)3](-))n with M(II) = Mn(II), Ni(II) in their optically active forms. In these 3D networks, all of the metallic centers have the same configuration, Delta or Lambda, as the template cation. We have determined the structure of ([DeltaRu(bpy)3][ClO4][DeltaMnDeltaCr(ox)3])n and ([LambdaRu(bpy)2ppy](+), [LambdaMn(II)LambdaCr(III)(ox)3](-))n by X-ray diffraction studies. These optically active networks show the Cotton effect and long-range ferromagnetic order at low temperatures. The magnetic circular dichroism of ([Ru(bpy)3](2+), ClO4(-), [Mn(II)Cr(III)(ox)3](-))n at 2 K is reported.