Recent advances enabled the discovery of heterometallic molecules for many metals: main group, d-block, lanthanides, and some actinides (U, Th). These complexes have at least two different metals joined by bridging ligands or by direct metal-metal bonding interactions. They are attractive because they can enable chemical cooperativity between metals from different parts of the periodic table.
View Article and Find Full Text PDFNumerous technologies-with catalytic, therapeutic, and diagnostic applications-would benefit from improved chelation strategies for heavy alkaline earth elements: Ra, Ba, and Sr. Unfortunately, chelating these metals is challenging because of their large size and weak polarizing power. We found 18-crown-6-tetracarboxylic acid () bound Ra, Ba, and Sr to form .
View Article and Find Full Text PDFHistoric perspectives describing f-elements as being redox "inactive" are fading. Researchers continue to discover new oxidation states that are not as inaccessible as once assumed for actinides and lanthanides. Inspired by those contributions, we studied americium(III) oxidation in aqueous media under air using NaBiO.
View Article and Find Full Text PDFAdvancing the field of chemical separations is important for nearly every area of science and technology. Some of the most challenging separations are associated with the americium ion Am(III) for its extraction in the nuclear fuel cycle, Am production for industrial usage, and environmental cleanup efforts. Herein, we study a series of extractants, using first-principle calculations, to identify the electronic properties that preferentially influence Am(III) binding in separations.
View Article and Find Full Text PDFAn amendment to this paper has been published and can be accessed via a link at the top of the paper.
View Article and Find Full Text PDFDesign-specific control over excited-state dynamics is necessary for any application seeking to convert light into chemical potential. Such control is especially desirable in iron(II)-based chromophores, which are an Earth-abundant option for a wide range of photo-induced electron-transfer applications including solar energy conversion and catalysis. However, the sub-200-femtosecond lifetimes of the redox-active metal-to-ligand charge transfer (MLCT) excited states typically encountered in these compounds have largely precluded their widespread use.
View Article and Find Full Text PDFIn an effort to better define the nature of the nuclear coordinate associated with excited state dynamics in first-row transition metal-based chromophores, variable-temperature ultrafast time-resolved absorption spectroscopy has been used to determine activation parameters associated with ground state recovery dynamics in a series of low-spin Fe(ii) polypyridyl complexes. Our results establish that high-spin (T) to low-spin (A) conversion in complexes of the form [Fe(4,4'-di-R-2,2'-bpy')] (R = H, CH, or -butyl) is characterized by a small but nevertheless non-zero barrier in the range of 300-350 cm in fluid CHCN solution, a value that more than doubles to ∼750 cm for [Fe(terpy)] (terpy = 2,2':6',2''-terpyridine). The data were analyzed in the context of semi-classical Marcus theory.
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