Magnetic properties and chiral states of a trimetallic uranium complex

Future Directions for Transuranic Single Molecule Magnets

Single Molecule Magnets (SMMs) based on transition metals and rare earths have been the object of considerable attention for the past 25 years. These systems exhibit slow relaxation of the magnetization, arising from a sizeable anisotropy barrier, and magnetic hysteresis of purely molecular origin below a given blocking temperature. Despite initial predictions that SMMs based on 5f-block elements could outperform most others, the results obtained so far have not met expectations. Exploiting the versatile chemistry of actinides and their favorable intrinsic magnetic properties proved, indeed, to be more difficult than assumed. However, the large majority of studies reported so far have been dedicated to uranium molecules, thus leaving the largest part of the 5f-block practically unexplored. Here, we present a short review of the progress achieved up to now and discuss some options for a possible way forward.

Exploration of the Structural, Electronic and Tunable Magnetic Properties of Cu₄M (M = Sc-Ni) Clusters

The structural, electronic and magnetic properties of Cu₄M (M = Sc-Ni) clusters have been studied by using density functional theory, together with an unbiased CALYPSO structure searching method. Geometry optimizations indicate that M atoms in the ground state Cu₄M clusters favor the most highly coordinated position. The geometry of Cu₄M clusters is similar to that of the Cu₅ cluster. The infrared spectra, Raman spectra and photoelectron spectra are predicted and can be used to identify the ground state in the future. The relative stability and chemical activity are investigated by means of the averaged binding energy, dissociation energy and energy level gap. It is found that the dopant atoms except for Cr and Mn can enhance the stability of the host cluster. The chemical activity of all Cu₄M clusters is lower than that of Cu₅ cluster whose energy level gap is in agreement with available experimental finding. The magnetism calculations show that the total magnetic moment of Cu₄M cluster mainly come from M atom and vary from 1 to 5 μ_B by substituting a Cu atom in Cu₅ cluster with different transition-metal atoms.

The linear and non-linear magnetic response of a tri-uranium single molecule magnet

We report here low temperature magnetization isotherms for the single molecule magnet, (UO₂-L)₃. By analyzing the low temperature magnetization in terms of M  =  χ ₁ B  +  χ ₃ B ³ we extract the linear susceptibility χ ₁ and the leading order nonlinear susceptibility χ ₃. We find that χ ₁ exhibits a peak at a temperature of T ₁  =  10.4 K with χ ₃ also exhibiting a peak but at a reduced temperature T ₃  =  5 K. At the lowest temperatures the isotherms exhibit a critical field B _c  =  11.5 T marked by a clear point of inflection. A minimal Hamiltonian employing S  =  1 (pseudo) spins with only a single energy scale (successfully used to model the behavior of bulk f-electron metamagnets) is shown to provide a good description of the observed linear scaling between T ₁, T ₃ and B _c. We further show that a Heisenberg Hamiltonian previously employed by Carretta et al (2013 J. Phys.: Condens. Matter 25 486001) to model this single molecule magnet gives formulas for the angle averaged susceptibilities (in the Ising limit) very similar to those of the minimal model.

Metal complexes containing natural and and artificial radioactive elements and their applications

Recent advances (during the 2007–2014 period) in the coordination and organometallic chemistry of compounds containing natural and artificially prepared radionuclides (actinides and technetium), are reviewed. Radioactive isotopes of naturally stable elements are not included for discussion in this work. Actinide and technetium complexes with O-, N-, N,O, N,S-, P-containing ligands, as well π-organometallics are discussed from the view point of their synthesis, properties, and main applications. On the basis of their properties, several mono-, bi-, tri-, tetra- or polydentate ligands have been designed for specific recognition of some particular radionuclides, and can be used in the processes of nuclear waste remediation, i.e., recycling of nuclear fuel and the separation of actinides and fission products from waste solutions or for analytical determination of actinides in solutions; actinide metal complexes are also usefulas catalysts forcoupling gaseous carbon monoxide, as well as antimicrobial and anti-fungi agents due to their biological activity. Radioactive labeling based on the short-lived metastable nuclide technetium-99m (^99mTc) for biomedical use as heart, lung, kidney, bone, brain, liver or cancer imaging agents is also discussed. Finally, the promising applications of technetium labeling of nanomaterials, with potential applications as drug transport and delivery vehicles, radiotherapeutic agents or radiotracers for monitoring metabolic pathways, are also described.