Stabilization of hydrated Ac<sup>III</sup> cation: the role of superatom states in actinium-water bonding

Grover, Payal; Schreckenbach, Georg

doi:10.1039/d0sc02342f

Cited by 16 publications

(26 citation statements)

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“…For lanthanides with smaller ionic radii, eight coordination sites (or the size of the inner cavity) may be suitable, but for actinides with larger ionic radii, a higher coordination number is required. For example, only nine-coordinated [An III (DOTA)(H 2 O)] − (An = Pu, Am) were characterized by X-ray crystallography, whereas [An III (DOTA)] − complexes were not. , Further research found that changes in the ninth coordination species can not only directly affect the spectroscopic, magnetic, and electronic structure properties of the complex but also change the oxidation state of the central Ln/An atom. − Therefore, a systematic study on the interaction between the [An III (DOTA)] − fragment and different axial ligands could provide a detailed characterization of actinide chelation chemistry in a fruitful and convenient way.…”

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confidence: 99%

Computational Characterization of Ac^III-DOTA Complexes in Aqueous Solution

2021

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The 1,4,7,10-tetrazacyclodecane-1,4,7,10-tetraacetic acid (DOTA) aqueous complexes of AcIII with H2O, dimethyl sulfoxide (DMSO), OH–, and F– as axial ligands were studied using density functional theory. Formation of the [AcIII(DOTA)(OH)]2– and [AcIII(DOTA)(F)]2– complexes is predicted to be significantly more favorable than that of [AcIII(DOTA)(H2O)]− and [AcIII(DOTA)(DMSO)]− because of the enhanced relative Gibbs free energies. Further electronic structure analyses demonstrate that the type and nature of the bond between Ac and the ligand donor atom is the main driving force that determines the thermodynamic stability of the complexes. Specifically, the [AcIII(DOTA)]− complex strongly binds to OH– and F– via covalent bonds, while the bonding to H2O and DMSO is ionic and relatively weaker.

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confidence: 99%

Computational Characterization of Ac^III-DOTA Complexes in Aqueous Solution

2021

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“…When 225 Ac-DOTA-benzene-p-SCN was injected intratumorally in nude mice bearing HEP-G2 tumors, a very rapid clearance of radioactivity from the tumor was observed ( Figure 5 b); and almost 10-fold higher uptake in liver and spleen was seen with regard to the 225 Ac-rHDL biodistribution pattern ( Figure 5 b). These findings suggest that although the DOTA chelating agent is highly stable for positive trivalent radiometals [ 12 , 24 , 25 ], 225 Ac-DOTA-benzene-p-SCN does not remain in the tumor, because the recoil energy of the 225 Ac daughters (1000 times greater than the binding energy of any chemical compound) is possibly causing the breaking of chemical bonds, with the consequent retention of 225 Ac 3+ and its progeny in the liver as ionic forms [ 23 ].…”

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confidence: 99%

225Ac-rHDL Nanoparticles: A Potential Agent for Targeted Alpha-Particle Therapy of Tumors Overexpressing SR-BI Proteins

et al. 2022

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Actinium-225 and other alpha-particle-emitting radionuclides have shown high potential for cancer treatment. Reconstituted high-density lipoproteins (rHDL) specifically recognize the scavenger receptor B type I (SR-BI) overexpressed in several types of cancer cells. Furthermore, after rHDL-SR-BI recognition, the rHDL content is injected into the cell cytoplasm. This research aimed to prepare a targeted 225Ac-delivering nanosystem by encapsulating the radionuclide into rHDL nanoparticles. The synthesis of rHDL was performed in two steps using the microfluidic synthesis method for the subsequent encapsulation of 225Ac, previously complexed to a lipophilic molecule (225Ac-DOTA-benzene-p-SCN, CLog P = 3.42). The nanosystem (13 nm particle size) showed a radiochemical purity higher than 99% and stability in human serum. In vitro studies in HEP-G2 and PC‑3 cancer cells (SR-BI positive) demonstrated that 225Ac was successfully internalized into the cytoplasm of cells, delivering high radiation doses to cell nuclei (107 Gy to PC-3 and 161 Gy to HEP-G2 nuclei at 24 h), resulting in a significant decrease in cell viability down to 3.22 ± 0.72% for the PC‑3 and to 1.79 ± 0.23% for HEP-G2 at 192 h after 225Ac-rHDL treatment. After intratumoral 225Ac‑rHDL administration in mice bearing HEP-G2 tumors, the biokinetic profile showed significant retention of radioactivity in the tumor masses (90.16 ± 2.52% of the injected activity), which generated ablative radiation doses (649 Gy/MBq). The results demonstrated adequate properties of rHDL as a stable carrier for selective deposition of 225Ac within cancer cells overexpressing SR-BI. The results obtained in this research justify further preclinical studies, designed to evaluate the therapeutic efficacy of the 225Ac-rHDL system for targeted alpha-particle therapy of tumors that overexpress the SR-BI receptor.

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“…All complexes were chosen to have 9‐coordinate geometries with a tricapped trigonal prismatic (TTP) arrangement of donor atoms around the central Ac 3+ ion. This choice of coordination number (CN) 9 was motivated by DFT studies of the Ac 3+ ion with 4–11 water molecules where [Ac(H 2 O) 9 ] 3+ was shown to be the most stable, both, in the gas phase and the aqueous phase (COSMO model) 26 . Keeping the coordination number fixed also provides internal consistency thanks to the similar steric crowding around the Ac metal center.…”

Section: Resultsmentioning

confidence: 99%

“…(The longest‐lived isotope, 227 Ac, has a half‐life of about 21.7 years.) Thus, computational methods are applied to actinium chemistry and to improve the chelate design 13,22–26 . Other theoretical studies investigated the maximum possible coordination number of Ac 3+ and found that up to 18 helium atoms can be accommodated giving a stable complex [AcHe 18 ] 3+ in the gas phase 27,28 …”

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confidence: 99%

Actinium coordination chemistry: A density functional theory study with monodentate and bidentate ligands

Tomeček

Schreckenbach

2022

J Comput Chem

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In the current study, the coordination chemistry of nine‐coordinate Ac(III) complexes with 35 monodentate and bidentate ligands was investigated using density functional theory (DFT) in terms of their geometries, charges, reaction energies, and bonding interactions. The energy decomposition analysis with naturals orbitals for chemical valence (EDA‐NOCV) and the quantum theory of atoms in molecules (QTAIM) were employed as analysis methods. Trivalent Ac exhibits the highest affinities toward hard acids (such as charged oxophilic donors, fluoride), so its classification as a hard acid is justified. Natural population analysis quantified the involvement of 5f orbitals on Ac to be about 30% of total valence electron natural configuration indicating that Ac is a member of the actinide series. Pearson correlation coefficients were used to study the pairwise correlations among the bond lengths, ΔG reaction energies, charges on Ac and donor atoms, and data from EDA‐NOCV and QTAIM. Strong correlations and anticorrelations were found between Voronoi charges on donor atoms with ΔG, EDA‐NOCV interaction energies and QTAIM bond critical point densities.

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Stabilization of hydrated Ac^III cation: the role of superatom states in actinium-water bonding

Abstract: The stable 9-coordinated complex adopts a closed-shell 18-electron configuration of a 1S21P61D10 jellium state, while potential 10-coordinated complexes need to overcome an energy barrier (>0.10 eV) caused by hydrogen bonding to convert to 9-coordination.

Cited by 16 publications

References 93 publications

Computational Characterization of Ac^III-DOTA Complexes in Aqueous Solution

Computational Characterization of Ac^III-DOTA Complexes in Aqueous Solution

225Ac-rHDL Nanoparticles: A Potential Agent for Targeted Alpha-Particle Therapy of Tumors Overexpressing SR-BI Proteins

Actinium coordination chemistry: A density functional theory study with monodentate and bidentate ligands

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Stabilization of hydrated AcIII cation: the role of superatom states in actinium-water bonding

Abstract: The stable 9-coordinated complex adopts a closed-shell 18-electron configuration of a 1S21P61D10 jellium state, while potential 10-coordinated complexes need to overcome an energy barrier (>0.10 eV) caused by hydrogen bonding to convert to 9-coordination.

Cited by 16 publications

References 93 publications

Computational Characterization of AcIII-DOTA Complexes in Aqueous Solution

Computational Characterization of AcIII-DOTA Complexes in Aqueous Solution

225Ac-rHDL Nanoparticles: A Potential Agent for Targeted Alpha-Particle Therapy of Tumors Overexpressing SR-BI Proteins

Actinium coordination chemistry: A density functional theory study with monodentate and bidentate ligands

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Stabilization of hydrated Ac^III cation: the role of superatom states in actinium-water bonding

Computational Characterization of Ac^III-DOTA Complexes in Aqueous Solution

Computational Characterization of Ac^III-DOTA Complexes in Aqueous Solution