The Experts below are selected from a list of 981 Experts worldwide ranked by ideXlab platform
P. Delahaye - One of the best experts on this subject based on the ideXlab platform.
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towards high resolution laser ionization spectroscopy of the heaviest elements in supersonic gas jet expansion
Nature Communications, 2017Co-Authors: R Ferrer, R. P. De Groote, A. E. Barzakh, M Block, B. Bastin, R. Beerwerth, P. Creemers, H. Grawe, P. DelahayeAbstract:Resonant laser ionization and spectroscopy are widely used techniques at radioactive ion beam facilities to produce pure beams of exotic nuclei and measure the shape, size, spin and electromagnetic multipole moments of these nuclei. However, in such measurements it is difficult to combine a high efficiency with a high spectral resolution. Here we demonstrate the on-line application of atomic laser ionization spectroscopy in a supersonic gas jet, a technique suited for high-precision studies of the ground- and isomeric-state properties of nuclei located at the extremes of stability. The technique is characterized in a measurement on Actinium isotopes around the N=126 neutron shell closure. A significant improvement in the spectral resolution by more than one order of magnitude is achieved in these experiments without loss in efficiency. It is challenging to explore properties of heavy elements as they can only be produced artificially. Here, the authors demonstrate a high resolution spectroscopy method, studying the properties of Actinium, which can be extended to the study of other elements located at the end of the periodic table.
R. Beerwerth - One of the best experts on this subject based on the ideXlab platform.
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towards high resolution laser ionization spectroscopy of the heaviest elements in supersonic gas jet expansion
Nature Communications, 2017Co-Authors: R Ferrer, R. P. De Groote, A. E. Barzakh, M Block, B. Bastin, R. Beerwerth, P. Creemers, H. Grawe, P. DelahayeAbstract:Resonant laser ionization and spectroscopy are widely used techniques at radioactive ion beam facilities to produce pure beams of exotic nuclei and measure the shape, size, spin and electromagnetic multipole moments of these nuclei. However, in such measurements it is difficult to combine a high efficiency with a high spectral resolution. Here we demonstrate the on-line application of atomic laser ionization spectroscopy in a supersonic gas jet, a technique suited for high-precision studies of the ground- and isomeric-state properties of nuclei located at the extremes of stability. The technique is characterized in a measurement on Actinium isotopes around the N=126 neutron shell closure. A significant improvement in the spectral resolution by more than one order of magnitude is achieved in these experiments without loss in efficiency. It is challenging to explore properties of heavy elements as they can only be produced artificially. Here, the authors demonstrate a high resolution spectroscopy method, studying the properties of Actinium, which can be extended to the study of other elements located at the end of the periodic table.
R Ferrer - One of the best experts on this subject based on the ideXlab platform.
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search for octupole deformed Actinium isotopes using resonance ionization spectroscopy
Physical Review C, 2019Co-Authors: E Verstraelen, A. E. Barzakh, R Ferrer, A Teigelhofer, Wouter Ryssens, F Ames, Michael Bender, S GorielyAbstract:In-source resonance ionization spectroscopy of the neutron-rich Actinium isotopes $^{225\ensuremath{-}229}\mathrm{Ac}$ has been performed at the ISAC facility in TRIUMF, probing a $^{2}D_{3/2}\ensuremath{\rightarrow}^{4}P_{5/2}^{\ensuremath{\circ}}$ atomic transition. New data on the magnetic dipole moments and changes in mean-square charge radii $\ensuremath{\delta}\ensuremath{\langle}{r}^{2}\ensuremath{\rangle}$ of $^{226,228,229}\mathrm{Ac}$ have been obtained. The comparison of the measured isotope shifts and magnetic dipole coupling constants $a(^{4}P_{5/2}^{\ensuremath{\circ}})$ of $^{225,227}\mathrm{Ac}$ with a high-resolution data set is used to identify systematic uncertainties on the deduced $\ensuremath{\delta}{\ensuremath{\langle}{r}^{2}\ensuremath{\rangle}}^{A,215}$ and magnetic dipole moment values. The charge radii odd-even staggering is evaluated for the odd-$N$ isotopes, showing that $^{226}\mathrm{Ac}$ has an inverted odd-even staggering that might be linked with a reflection-asymmetric shape. Comparison of the magnetic dipole moments of $^{225,227,229}\mathrm{Ac}$ with Nilsson-model estimates supports the assumption of octupole deformation in isotopes $^{225,227}\mathrm{Ac}$ and its gradual decrease toward isotope $^{229}\mathrm{Ac}$. The changes in mean-square charge radii are compared to self-consistent calculations employing multiple modern energy density functionals: SLy5s1, BSk31, and DD-MEB1. For SLy5s1 in particular, self-consistent time-reversal breaking calculations of odd-odd nuclei incorporating finite octupole deformation are reported for the first time. For these calculations, the overall best agreement is obtained when the octupole degree of freedom is taken into account.
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towards high resolution laser ionization spectroscopy of the heaviest elements in supersonic gas jet expansion
Nature Communications, 2017Co-Authors: R Ferrer, R. P. De Groote, A. E. Barzakh, M Block, B. Bastin, R. Beerwerth, P. Creemers, H. Grawe, P. DelahayeAbstract:Resonant laser ionization and spectroscopy are widely used techniques at radioactive ion beam facilities to produce pure beams of exotic nuclei and measure the shape, size, spin and electromagnetic multipole moments of these nuclei. However, in such measurements it is difficult to combine a high efficiency with a high spectral resolution. Here we demonstrate the on-line application of atomic laser ionization spectroscopy in a supersonic gas jet, a technique suited for high-precision studies of the ground- and isomeric-state properties of nuclei located at the extremes of stability. The technique is characterized in a measurement on Actinium isotopes around the N=126 neutron shell closure. A significant improvement in the spectral resolution by more than one order of magnitude is achieved in these experiments without loss in efficiency. It is challenging to explore properties of heavy elements as they can only be produced artificially. Here, the authors demonstrate a high resolution spectroscopy method, studying the properties of Actinium, which can be extended to the study of other elements located at the end of the periodic table.
David A. Scheinberg - One of the best experts on this subject based on the ideXlab platform.
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a phase 2 study of Actinium 225 225ac lintuzumab in older patients with previously untreated acute myeloid leukemia aml unfit for intensive chemotherapy
Blood, 2017Co-Authors: Laura Finn, David A. Scheinberg, Dragan Cicic, Moshe Yair Levy, Johnnie J Orozco, Jae H Park, Ehab Atallah, Michael Craig, Alexander E Perl, Gregory BergonioAbstract:Abstract Background: Older patients (pts) unfit for induction chemotherapy have high early death rates and limited overall survival (OS), both of which depend on age, prior MDS, comorbidities, and performance status (PS) (Heaematologica 2012;97:1916). 225Ac-lintuzumab (Actimab-A) is a radioimmunoconjugate composed of 225Ac linked to a humanized anti-CD33 monoclonal antibody. 225Ac emits 4 α-particles and has a 10 day half-life. A Phase 1 trial to evaluate fractionated-doses of 225Ac-lintuzumab in combination with low-dose cytarabine was previously conducted. Responses were seen at doses of ≥1 µCi/kg/fraction, and 2 µCi/kg/fraction was chosen as the phase 2 dose to limit myelosuppression. Responding pts had peripheral blasts Patients and Methods: Pts ≥ 60 years with untreated AML and ECOG PS 0-3 were enrolled. Pts with antecedent hematologic disorders (AHDs) were eligible, including those with prior AHD therapy. Pts 60 to 74 years of age were required to have significant cardiac, pulmonary, renal or hepatic impairment. Any pt ≥ 75 years of age was eligible. Expression of CD33 on > 25% of blasts was required. Pts were required to have a peripheral blast count Results: Thirteen pts were treated, and preliminary data are available on 9 with median age 75 years (range, 65-82) and PS median 2 (0-1 in 2 pts, 2 in 3 pts, & 3 in 2 pts). Six (67%) had prior treatment for AHDs (5 MDS, 1 atypical CML). At baseline, 5 pts had ANC ≥ 500/µL, only 2 had ANC ≥ 1000/µL, and only 1 had platelets > 50,000/µL. Available cytogenetic data were limited, but 1 had intermediate and 3 had adverse cytogenetics by MRC criteria. The median baseline bone marrow blast percentage was 26% (range, 20-88%) with a median CD33 expression of 67% (range, 33-91%). Myelosuppression was seen in all evaluable pts including grade 4 thrombocytopenia with marrow aplasia for > 6 weeks following therapy in 3 pts. The only Grade >3 non-hematologic toxicities reported in ≥1 pt were pneumonia and cellulitis. Veno-occlusive disease did not occur. The 30-day mortality rate was 33% (disease progression, acute on chronic respiratory failure, and post-traumatic intracranial hemorrhage after a fall). Objective responses were documented in 5 of the 9 pts (56%): 2 Complete Remissions with incomplete platelet count recovery (CRp) and 3 Complete Remissions with incomplete hematologic recovery (CRi). Among the responders, 2 pts had adverse cytogenetics including one with t-AML, and 3 pts had no AHD. Two pts had resistant disease. Median time to neutrophil recovery (ANC ≥ 500/µL) was 36 days (range 20-60) from the first dose of 225Ac-lintuzumab. The two pts with CRp had neutrophil recovery at Days 60 and 36. Two of the pts with CRi had not reached ANC ≥ 500/µL when they expired from infection on days 65 and 56, and the third is at day 66+ without ANC recovery. Since pts with AHDs may not have capacity to recover to normal neutrophil production, pts without AHDs may be more informative. Of the 3 pts without AHDs, 1 had ANC recovery at Day 36, 1 had death from infection at Day 56 without ANC recovery, and 1 is pending ANC recovery at Day 66+. No pts reached platelet counts > 20,000/µL without transfusions. Conclusions: Preliminary data from this Phase 2 trial of 225Ac-lintuzumab monotherapy at 2 µCi/kg/fraction document a 56% response rate in older pts unfit for intensive therapy, many with AHDs. As myelosuppression at this dose was considered to be longer than acceptable in this population, accrual to this study will continue at 1.5 µCi/kg/fraction with the goal to shorten recovery times. Data on additional patients treated at that dose will be presented. Disclosures Levy: Actinium Pharmaceuticals: Equity Ownership; Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Research Funding; Takeda: Consultancy, Speakers Bureau. Orozco: Actinium Pharmaceuticals: Other: Research Funding to Institution for sponsored Clinical Trials. Park: Amgen: Consultancy. Atallah: ADC Therapeutics: Research Funding. Perl: Novartis: Other: Advisory Board; Asana Biosciences: Other: Scientific advisory board; Arog Pharmaceuticals: Consultancy; Pfizer: Other: Advisory Board; Daiichi Sankyo: Consultancy; Seattle Genetics: Other: Advisory board; Actinium Pharmaceuticals: Other: Scientific Advisory Board; Astellas: Consultancy. Scheinberg: Eureka Therapeutics: Consultancy, Equity Ownership, Honoraria, Membership on an entity's Board of Directors or advisory committees; Memorial Sloan Kettering Cancer Center: Patents & Royalties: WO2012135854 A2, US Provisional 62/62/395,577; Actinium Pharmaceuticals: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Cicic: Actinium Pharmaceuticals: Employment, Equity Ownership. Bergonio: Actinium Pharmaceuticals: Employment, Equity Ownership. Berger: Actinium Pharmaceuticals: Employment, Equity Ownership. Jurcic: Astellas Pharma, Inc: Research Funding; Daiichi-Sankyo: Research Funding; Actinium Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees, Research Funding; Alexion Pharmaceuticals: Consultancy; Celgene: Research Funding; Forma Therapeutics: Research Funding; Genentech: Research Funding; Incyte: Consultancy; Kura Oncology: Research Funding; Merck: Consultancy; Novartis: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Consultancy, Research Funding; Syros Pharmaceuticals: Research Funding; Amgen: Consultancy.
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phase i trial of the targeted alpha particle nano generator Actinium 225 225ac lintuzumab anti cd33 in combination with low dose cytarabine ldac for older patients with untreated acute myeloid leukemia aml
Blood, 2013Co-Authors: Joseph G Jurcic, Dragan Cicic, Jae H Park, Farhad Ravandi, John M Pagel, Dan Douer, Elihu H Estey, Hagop M Kantarjian, David A. ScheinbergAbstract:Background Lintuzumab, a humanized anti-CD33 antibody, targets myeloid leukemia cells and has modest activity against AML. To increase the antibody’s potency yet avoid nonspecific cytotoxicity seen with β-emitting isotopes, the isotope generator 225Ac (t½=10 days), which yields 4 α-particles, was conjugated to lintuzumab. A phase I trial demonstrated that 225Ac-lintuzumab is safe at doses ≤ 3 μCi/kg and has anti-leukemic activity across all dose levels studied (Jurcic et al. ASH, 2011). We are conducting a multicenter, phase I dose escalation trial to determine the maximum tolerated dose (MTD), toxicity, and biological activity of fractionated-dose 225Ac-lintuzumab in combination with LDAC. Patients and Methods Patients ≥ 60 yrs who had untreated AML with poor-prognostic factors, such as an antecedent hematologic disorder (AHD), unfavorable cytogenetic or molecular abnormalities, and significant comorbidities, were eligible. Patients received LDAC 20 mg bid for 10 days every 4-6 weeks. During cycle 1, beginning 4-7 days after LDAC, two doses of 225Ac-lintuzumab were given approximately one week apart. Results Seven patients (median age, 76 yrs; range, 72-80 yrs) were treated, all of whom had AHDs. Five (71%) had intermediate-risk cytogenetics, and two (29%) had unfavorable cytogenetics. The median CD33 expression was 76% (range, 69-95%). Prior therapy for myelodysplastic syndrome included hypomethylating agents (n=4) and allogeneic hematopoietic cell transplantation (n=1). Patients received 225Ac-lintuzumab at doses of 0.5 (n=3) or 1 (n=4) μCi/kg/fraction, two fractions per patient (total administered activity, 68-199 μCi). Dose-limiting toxicity was seen in one patient receiving 1 μCi/kg/fraction who had grade 4 thrombocytopenia in the setting of an aplastic bone marrow that persisted > 6 wks after completing the second fraction of 225Ac-lintuzumab. Other toxicities included grade 3 febrile neutropenia (n=5), bacteremia (n=1), pneumonia (n=1), cellulitis (n=1), transient increase in creatinine (n=1), and generalized weakness (n=1). Bone marrow blast reductions were seen in 4 of 6 evaluable patients (67%) after cycle 1 (mean blast reduction, 58%; range, 34-100%). No CRs, however, were observed. The median number of cycles administered was 2 (range, 1-4), and the median time to progression was 2.5 months (range, 2-7+ months). Conclusions Fractionated-dose 225Ac-linutuzmab in combination with LDAC is feasible, safe, and has anti-leukemic activity. Accrual continues to define the MTD, with planned dose levels up to 2 μCi/kg/fraction. Additional patients will be treated at the MTD in the phase II portion of this trial to determine response rate, progression-free survival, and overall survival. Disclosures: Jurcic: Actinium Pharmaceuticals, Inc.: Membership on an entity’s Board of Directors or advisory committees. Ravandi: Actinium Pharmaceuticals, Inc.: Research Funding. Pagel: Actinium Pharmaceuticals, Inc.: Equity Ownership, Membership on an entity’s Board of Directors or advisory committees, Research Funding. Park: Actinium Pharmaceuticals, Inc.: Research Funding. Douer: Actinium Pharmaceuticals, Inc.: Research Funding. Estey: Actinium Pharmaceuticals, Inc.: Membership on an entity’s Board of Directors or advisory committees. Cicic: Actinium Pharmaceuticals, Inc.: Employment, Equity Ownership. Scheinberg: Actinium Pharmaceuticals, Inc.: Ac-225-Lintuzumab, Ac-225-Lintuzumab Patents & Royalties, Equity Ownership, Membership on an entity’s Board of Directors or advisory committees.
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Actinium 225 in targeted alpha particle therapeutic applications
Current Radiopharmaceuticals, 2011Co-Authors: David A. Scheinberg, Michael R McdevittAbstract:Alpha particle-emitting isotopes are being investigated in radioimmunotherapeutic applications because of their unparalleled cytotoxicity when targeted to cancer and their relative lack of toxicity towards untargeted normal tissue. Actinium- 225 has been developed into potent targeting drug constructs and is in clinical use against acute myelogenous leukemia. The key properties of the alpha particles generated by 225Ac are the following: i) limited range in tissue of a few cell diameters; ii) high linear energy transfer leading to dense radiation damage along each alpha track; iii) a 10 day halflife; and iv) four net alpha particles emitted per decay. Targeting 225Ac-drug constructs have potential in the treatment of cancer.
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realizing the potential of the Actinium 225 radionuclide generator in targeted alpha particle therapy applications
Advanced Drug Delivery Reviews, 2008Co-Authors: Matthias Miederer, David A. Scheinberg, Michael R McdevittAbstract:Alpha particle-emitting isotopes have been proposed as novel cytotoxic agents for augmenting targeted therapy. Properties of alpha particle radiation such as their limited range in tissue of a few cell diameters and their high linear energy transfer leading to dense radiation damage along each alpha track are promising in the treatment of cancer, especially when single cells or clusters of tumor cells are targeted. Actinium-225 (225Ac) is an alpha particle-emitting radionuclide that generates 4 net alpha particle isotopes in a short decay chain to stable 209Bi, and as such can be described as an alpha particle nanogenerator. This article reviews the literature pertaining to the research, development, and utilization of targeted 225Ac to potently and specifically affect cancer.
Benjamin W Stein - One of the best experts on this subject based on the ideXlab platform.
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computer assisted design of macrocyclic chelators for Actinium 225 radiotherapeutics
Inorganic Chemistry, 2021Co-Authors: Amanda Morgenstern, Laura M Lilley, Benjamin W Stein, Stosh A Kozimor, Enrique R Batista, Ping YangAbstract:Actinium-225 (225Ac) is an excellent candidate for targeted radiotherapeutic applications for treating cancer, because of its 10-day half-life and emission of four high-energy α2+ particles. To harness and direct the energetic potential of Actinium, strongly binding chelators that remain stable in vivo during biological targeting must be developed. Unfortunately, controlling chelation for Actinium remains challenging. Actinium is the largest +3 cation on the periodic table and has a 6d05f0 electronic configuration, and its chemistry is relatively unexplored. Herein, we present theoretical work focused on improving the understanding of Actinium bonding with macrocyclic chelating agents as a function of (1) macrocycle ring size, (2) the number and identity of metal binding functional groups, and (3) the length of the tether linking the metal binding functional group to the macrocyclic backbone. Actinium binding by these chelators is presented within the context of complexation with DOTA4-, the most relevant Ac3+ binding agent for contemporary radiopharmaceutical applications. The results enabled us to develop a new strategy for Actinium chelator design. The approach is rooted in our identification that Ac3+-chelation chemistry is dominated by ionic bonding interactions and relies on (1) maximizing electrostatic interactions between the metal binding functional group and the Ac3+ cation and (2) minimizing electronic repulsion between negatively charged Actinium binding functional groups. This insight will provide a foundation for future innovation in developing the next generation of multifunctional Actinium chelators.
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preparation of an Actinium 228 generator
Inorganic Chemistry, 2020Co-Authors: Kelly E Aldrich, Laura M Lilley, Stosh A Kozimor, Mila Nhu Lam, Cecilia Eiroalledo, Veronika Mocko, Benjamin W SteinAbstract:Advances in targeted α-therapies have increased the interest in Actinium (Ac), whose chemistry is poorly defined due to scarcity and radiological hazards. Challenges associated with characterizing Ac3+ chemistry are magnified by its 5f06d0 electronic configuration, which precludes the use of many spectroscopic methods amenable to small amounts of material and low concentrations (like EPR, UV-vis, fluorescence). In terms of nuclear spectroscopy, many Actinium isotopes (225Ac and 227Ac) are equally "unfriendly" because the Actinium α-, β-, and γ-emissions are difficult to resolve from the Actinium daughters. To address these issues, we developed a method for isolating an Actinium isotope (228Ac) whose nuclear properties are well-suited for γ-spectroscopy. This four-step procedure isolates 228Ra from naturally occurring 232Th. The relatively long-lived 228Ra (t1/2 = 5.75(3) years) radioisotope subsequently decays to 228Ac. Because the 228Ac decay rate [t1/2 = 6.15(2) h] is fast, 228Ac rapidly regenerates after being harvested from the 228Ra parent. The resulting 228Ac generator provides frequent and long-term access (of many years) to the spectroscopically "friendly" 228Ac radionuclide. We have demonstrated that the 228Ac product can be routinely "milked" from this generator on a daily basis, in chemically pure form, with high specific activity and in excellent yield (∼95%). Hence, in the same way that developing synthesis routes to new starting materials has advanced coordination chemistry for many metals by broadening access, this 228Ac generator has the potential to broaden Actinium access for the inorganic community, facilitating the characterization of Actinium chemical behavior.
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synthesis and characterization of the Actinium aquo ion
ACS central science, 2017Co-Authors: Maryline G Ferrier, Benjamin W Stein, Stosh A Kozimor, Enrique R Batista, Jonathan W Engle, Eva R Birnbaum, Kevin D John, John M Berg, Juan Lezama S PachecoAbstract:Metal aquo ions occupy central roles in all equilibria that define metal complexation in natural environments. These complexes are used to establish thermodynamic metrics (i.e., stability constants) for predicting metal binding, which are essential for defining critical parameters associated with aqueous speciation, metal chelation, in vivo transport, and so on. As such, establishing the fundamental chemistry of the Actinium(III) aquo ion (Ac-aquo ion, Ac(H2O)x3+) is critical for current efforts to develop 225Ac [t1/2 = 10.0(1) d] as a targeted anticancer therapeutic agent. However, given the limited amount of Actinium available for study and its high radioactivity, many aspects of Actinium chemistry remain poorly defined. We overcame these challenges using the longer-lived 227Ac [t1/2 = 21.772(3) y] isotope and report the first characterization of this fundamentally important Ac-aquo coordination complex. Our X-ray absorption fine structure study revealed 10.9 ± 0.5 water molecules directly coordinated t...
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Synthesis and Characterization of the Actinium Aquo Ion
2017Co-Authors: Maryline G. Ferrier, Benjamin W Stein, Stosh A Kozimor, Enrique R Batista, Jonathan W Engle, Eva R Birnbaum, Kevin D John, John M Berg, Juan Lezama S Pacheco, Lindsay N. RedmanAbstract:Metal aquo ions occupy central roles in all equilibria that define metal complexation in natural environments. These complexes are used to establish thermodynamic metrics (i.e., stability constants) for predicting metal binding, which are essential for defining critical parameters associated with aqueous speciation, metal chelation, in vivo transport, and so on. As such, establishing the fundamental chemistry of the Actinium(III) aquo ion (Ac-aquo ion, Ac(H2O)x3+) is critical for current efforts to develop 225Ac [t1/2 = 10.0(1) d] as a targeted anticancer therapeutic agent. However, given the limited amount of Actinium available for study and its high radioactivity, many aspects of Actinium chemistry remain poorly defined. We overcame these challenges using the longer-lived 227Ac [t1/2 = 21.772(3) y] isotope and report the first characterization of this fundamentally important Ac-aquo coordination complex. Our X-ray absorption fine structure study revealed 10.9 ± 0.5 water molecules directly coordinated to the AcIII cation with an Ac–OH2O distance of 2.63(1) Å. This experimentally determined distance was consistent with molecular dynamics density functional theory results that showed (over the course of 8 ps) that AcIII was coordinated by 9 water molecules with Ac–OH2O distances ranging from 2.61 to 2.76 Å. The data is presented in the context of other actinide(III) and lanthanide(III) aquo ions characterized by XAFS and highlights the uniqueness of the large AcIII coordination numbers and long Ac–OH2O bond distances
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spectroscopic and computational investigation of Actinium coordination chemistry
Nature Communications, 2016Co-Authors: Maryline G Ferrier, Stosh A Kozimor, Enrique R Batista, Jonathan W Engle, Eva R Birnbaum, John M Berg, Justin N Cross, Henry S La Pierre, Juan Lezama S Pacheco, Benjamin W SteinAbstract: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) A, 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.
