title: Spectroscopic and computational investigation of actinium coordination chemistry.
abstract: Actinium-225 is a promising isotope for targeted-α therapy. Unfortunately, progress in developing chelators for medicinal applications has been hindered by a limited understanding of actinium chemistry. This knowledge gap is primarily associated with handling actinium, as it is highly radioactive and in short supply. Hence, Ac(III) reactivity is often inferred from the lanthanides and minor actinides (that is, Am, Cm), with limited success. Here we overcome these challenges and characterize actinium in HCl solutions using X-ray absorption spectroscopy and molecular dynamics density functional theory. The Ac-Cl and Ac-OH2O distances are measured to be 2.95(3) and 2.59(3) Å, respectively. The X-ray absorption spectroscopy comparisons between Ac(III) and Am(III) in HCl solutions indicate Ac(III) coordinates more inner-sphere Cl(1-) ligands (3.2±1.1) than Am(III) (0.8±0.3). These results imply diverse reactivity for the +3 actinides and highlight the unexpected and unique Ac(III) chemical behaviour.
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Maryline G
authors.initials: MG
authors.lastname: Ferrier
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Enrique R
authors.initials: ER
authors.lastname: Batista
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Berg
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Eva R
authors.initials: ER
authors.lastname: Birnbaum
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Justin N
authors.initials: JN
authors.lastname: Cross
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Engle
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Henry S
authors.initials: HS
authors.lastname: La Pierre
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Stosh A
authors.initials: SA
authors.lastname: Kozimor
authors.affiliation: Stanford University, Stanford, California 94305, USA.
authors.forename: Juan S
authors.initials: JS
authors.lastname: Lezama Pacheco
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: Benjamin W
authors.initials: BW
authors.lastname: Stein
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.|California State Polytechnic University, Pomona, California 91768, USA.
authors.forename: S Chantal E
authors.initials: SC
authors.lastname: Stieber
authors.affiliation: Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.|Cornell University, Ithaca, New York 14853, USA.
authors.forename: Justin J
authors.initials: JJ
authors.lastname: Wilson
mesh_terms: D000186:Actinium / Q000737:chemistry*; D005583:Fourier Analysis; D008958:Models, Molecular; D011868:Radioisotopes; D012996:Solutions; D056928:X-Ray Absorption Spectroscopy
chemical_list: D011868:Radioisotopes; D012996:Solutions; D000186:Actinium