Rare Earth and Actinide Complexes

Abstract

The rare earth metals (scandium, yttrium, lanthanum and the subsequent 4f elements) and actinides (actinium and the 5f elements) are vital components of our technology-dominated society. Examples include the fluorescent-red europium ions used in euro banknotes to deter counterfeiting [1], the radioactive americium used in smoke detectors [2] that save countless lives every year as well as neodymium used in the strongest permanent magnets [3]. However, the rare earth and actinide elements remain poorly recognised by non-scientists, and even by many undergraduates in chemistry.The similar radii of the respective +3 cations (Figure 1) belies their individually unique spectral [4] and magnetic [5] properties that contribute to their fascinating chemistry. In this Special Issue, devoted to molecular rare earth and actinide complexes, work from Natrajan and co-workers [6] has explored how fluorinated ligands improve the luminescence of 4f complexes, while Baker and co-workers [7] investigated the optical properties, as well as structure, of a new class of uranyl selenocyanate. Pointillart and co-workers' article [8] bridges the areas of lanthanide optical and magnetic properties-literally-by using bridging tetrathiafulvalene derivatives. The growing field of Single Molecule Magnetism originates in the d-block, but recent interest in the f-elements has been growing. Powell and co-workers [9] explore the use of dimeric dysprosium (which has a highly anisotropic f-electron distribution) compounds with a "hula-hoop" geometry, defined by the ligand that sits in an equatorial plane around both Dy atoms. The main current medical use for the lanthanides, as Magnetic Resonance Imaging (MRI) contrast agents, also relies on the unique electronic properties of the lanthanides. The article by Parac-Vogt and co-workers [10] demonstrates the combination of gadolinium for MRI imaging (thanks to its seven unpaired electrons) connected to a luminescent BODIPY fragment in order to explore combined MRI and optical imaging, addressing the drawbacks of both techniques through their complementary properties. The rare earth metals (scandium, yttrium, lanthanum and the subsequent 4f elements) and actinides (actinium and the 5f elements) are vital components of our technology-dominated society. Examples include the fluorescent-red europium ions used in euro banknotes to deter counterfeiting [1], the radioactive americium used in smoke detectors [2] that save countless lives every year as well as neodymium used in the strongest permanent magnets [3]. However, the rare earth and actinide elements remain poorly recognised by non-scientists, and even by many undergraduates in chemistry.The similar radii of the respective +3 cations (Figure 1) belies their individually unique spectral [4] and magnetic [5] properties that contribute to their fascinating chemistry. In this Special Issue, devoted to molecular rare earth and actinide complexes, work from Natrajan and co-workers [6] has explored how fluorinated ligands improve the luminescence of 4f com...

Functional Materials Based on Metal Hydrides

“…Sieverts-type measurements reveal a three-step desorption-absorption cycle with release of 4.2, 3.7 and 3.5 wt % H 2 for the first, second and third cycle. This work adds a new example to the growing interest in utilisation of rare earth metals and their unique properties [30,31].…”