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Th(GeO)2 crystallizes in the tetragonal I4_1/amd space group. The structure is zero-dimensional and consists of eight Th(GeO)2 clusters. Th is bonded in a linear geometry to two equivalent O atoms. Both Th–O bond lengths are 2.14 Å. Ge is bonded in a distorted single-bond geometry to one O atom. The Ge–O bond length is 1.82 Å. O is bonded in a bent 150 degrees geometry to one Th and one Ge atom.
Th is Tungsten structured and crystallizes in the cubic Im-3m space group. The structure is three-dimensional. Th is bonded in a distorted body-centered cubic geometry to eight equivalent Th atoms. All Th–Th bond lengths are 3.47 Å.
Th is Copper structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Th is bonded to twelve equivalent Th atoms to form a mixture of edge, face, and corner-sharing ThTh12 cuboctahedra. All Th–Th bond lengths are 3.56 Å.
This study investigates the dynamics and mechanisms of solution combustion synthesis (SCS) for the preparation of nanoscale ThO 2 and Th 1–x U x O 2 materials, utilizing metal nitrates (Th(NO 3 ) 4 and UO 2 (NO 3 ) 2 ) and acetylacetone (C 5 H 8 O 2 ) as reactants dissolved in a 2-methoxyethanol (C 3 H 8 O 2 ) solvent. By combining thermodynamic calculations, dynamic time–temperature profile measurements with differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), this research reveals how variations in acetylacetone concentration and uranium content influence the structural parameters of the synthesized oxides. The time–temperature measurements show that the heating rate and maximum combustion temperatures are sensitive to acetylacetone concentration. DSC-TGA results indicate shifts in exothermic peak temperatures as the uranium content changes. The complexation between thorium and acetylacetone emerges as a critical factor, impacting combustion parameters and the structural characteristics of the final products. The uniform distribution of Th and U in the Th 1–x U x O 2 solid solution and the formation of nanoscale particles with strained crystallites are considered essential for the low-temperature densification of these materials for nuclear fuel pellet applications. Additionally, high-quality ThO 2 and Th 1–x U x O 2 thin (100–150 nm) films are successfully synthesized via electrospray deposition of combustible solutions followed by a brief period of heat treatment. Furthermore, these films exhibit excellent structural and morphological uniformity, making them ideal candidates for nuclear measurements, irradiation damage studies, and investigations into the physical properties of both pure and mixed oxides.
The fundamental interest in actinide chemistry, particularly for the development of thorium-based materials, is experiencing a renaissance owing to the recent and rapidly growing attention to fuel cycle reactors, radiological daughters for nuclear medicine, and efficient nuclear stockpile development. Herein, we uncover fundamental principles of thorium chemistry on the example of Th-based extended structures such as metal–organic frameworks in comparison with the discrete systems and zirconium extended analogs, demonstrating remarkable over two-and-half-year chemical stability of Th-based frameworks as a function of metal node connectivity, amount of defects, and conformational linker rigidity through comprehensive spectroscopic and crystallographic analysis as well as theoretical modeling. Despite exceptional chemical stability, we report the first example of studies focusing on the reactivity of the most chemically stable Th-based frameworks in comparison with the discrete Th-based systems such as metal–organic complexes and a cage, contrasting multicycle recyclability and selectivity (>97%) of the extended structures in comparison with the molecular compounds. Altogether, the presented work not only establishes the conceptual foundation for evaluating the capabilities of Th-based materials but also represents a milestone for their multifaceted future and foreshadows their potential to shape the next era of actinide chemistry.
Targeted alpha therapy (TAT) offers great promise for treating recalcitrant tumors and micrometastatic cancers. One drawback of TAT is the potential damage to normal tissues and organs due to the relocation of decay daughters from the treatment site. As such, the present study evaluates La( 227 Th)PO 4 core (C) and core +2 shells (C2S) nanoparticles (NPs) as a delivery platform of 227 Th to minimize systemic distribution of decay daughters, 223 Ra and 211 Pb. In vitro retention of decay daughters within La( 227 Th)PO 4 C NPs was influenced by the concentration of reagents used during synthesis, in which the leakage of 223 Ra was between 0.4 ± 0.2% and 20.3 ± 1.1% in deionized water. Deposition of two nonradioactive LaPO 4 shells onto La( 227 Th)PO 4 C NPs increased the retention of decay daughters to >99.75%. The toxicity of the nonradioactive LaPO 4 C and C2S NP delivery platforms was examined in a mammalian breast cancer cell line, BT-474. No significant decrease in cell viability was observed for a monolayer of BT-474 cells for NP concentrations below 233.9 μg mL –1 , however cell viability decreased below 60% when BT-474 spheroids were incubated with either LaPO 4 C or C2S NPs at concentrations exceeding 29.2 μg mL –1 . La( 227 Th)PO 4 C2S NPs exhibit a high encapsulation and in vitro retention of radionuclides with limited contribution to cellular cytotoxicity for TAT applications.
Th(MnGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Th is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Th–Ge bond lengths are 3.15 Å. Mn is bonded to four equivalent Ge atoms to form a mixture of edge and corner-sharing MnGe4 tetrahedra. All Mn–Ge bond lengths are 2.45 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Th, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.67 Å.
ThTi2H6 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Th is bonded in a 6-coordinate geometry to nine H atoms. There are a spread of Th–H bond distances ranging from 2.31–2.48 Å. There are two inequivalent Ti sites. In the first Ti site, Ti is bonded in a distorted hexagonal planar geometry to six H atoms. There is two shorter (1.83 Å) and four longer (1.91 Å) Ti–H bond length. In the second Ti site, Ti is bonded in a 6-coordinate geometry to six equivalent H atoms. All Ti–H bond lengths are 1.79 Å. There are two inequivalent H sites. In the first H site, H is bonded in a trigonal planar geometry to one Th and two Ti atoms. In the second H site, H is bonded to two equivalent Th and two equivalent Ti atoms to form a mixture of distorted corner and edge-sharing HTh2Ti2 tetrahedra.
Th(TeI)2 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one Th(TeI)2 sheet oriented in the (0, 0, 1) direction. Th4+ is bonded in a 8-coordinate geometry to four Te1- and four equivalent I1- atoms. There are two shorter (3.21 Å) and two longer (3.24 Å) Th–Te bond lengths. There are two shorter (3.19 Å) and two longer (3.23 Å) Th–I bond lengths. There are two inequivalent Te1- sites. In the first Te1- site, Te1- is bonded in a 2-coordinate geometry to two equivalent Th4+ atoms. In the second Te1- site, Te1- is bonded in a 2-coordinate geometry to two equivalent Th4+ atoms. I1- is bonded in a distorted water-like geometry to two equivalent Th4+ atoms.
Th(NiH)2 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Th is bonded in a hexagonal planar geometry to six equivalent H atoms. All Th–H bond lengths are 2.50 Å. Ni is bonded in a linear geometry to two equivalent H atoms. Both Ni–H bond lengths are 1.77 Å. H is bonded to three equivalent Th and two equivalent Ni atoms to form a mixture of edge and corner-sharing HTh3Ni2 trigonal bipyramids.
ThV2Al20 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Th is bonded in a 4-coordinate geometry to sixteen Al atoms. There are four shorter (3.15 Å) and twelve longer (3.23 Å) Th–Al bond lengths. V is bonded to twelve Al atoms to form VAl12 cuboctahedra that share corners with six equivalent VAl12 cuboctahedra, edges with eighteen equivalent AlThAl10V cuboctahedra, and faces with six equivalent AlThAl10V cuboctahedra. There are six shorter (2.58 Å) and six longer (2.81 Å) V–Al bond lengths. There are three inequivalent Al sites. In the first Al site, Al is bonded in a distorted linear geometry to two equivalent Th and twelve equivalent Al atoms. All Al–Al bond lengths are 3.12 Å. In the second Al site, Al is bonded in a 12-coordinate geometry to two equivalent V and ten Al atoms. There are a spread of Al–Al bond distances ranging from 2.73–2.86 Å. In the third Al site, Al is bonded to one Th, one V, and ten Al atoms to form distorted AlThAl10V cuboctahedra that share corners with fifteen equivalent AlThAl10V cuboctahedra, edges with two equivalent AlThAl10V cuboctahedra, edges with three equivalent VAl12 cuboctahedra, a faceface with one VAl12 cuboctahedra, and faces with fifteen equivalent AlThAl10V cuboctahedra. There are a spread of Al–Al bond distances ranging from 2.72–2.92 Å.
Monazite-cheralite ceramics are a promising waste form for actinides. To elucidate the long-term behavior of this matrix in aqueous solutions, this study measured thermodynamic data for Th-rhabdophanes Ln 1-2 x Ca x Th x PO 4 ·nH 2 O (with Ln = Pr, Nd; x = 0–0.15) and the associated anhydrous monazite-cheralites Ln 1-2 x Ca x Th x PO 4 . Further, solubility experiments at 298K and high temperature oxide melt solution calorimetry were combined for calculation of ΔG$^°_f$, ΔH$^°_f$ and S$^°_m$ of Th-rhabdophanes and associated monazite-cheralites. Standard solubility constants were employed in a geochemical simulation using the PHREEQC software, the results of which confirmed the high chemical stability of the monazite-cheralite phases and supported their use as a specific conditioning matrix for the long-term immobilization of actinides.
Isolating isostructural compounds of tetravalent metals M IV (Zr, Hf, Ce, Th, U, Pu, Np) improves our understanding of metal hydrolysis and coordination behavior across the periodic table. These metals form polynuclear clusters typified by the hexamer [M IV 6 O 4 (OH) 4 ] 12+ . Exploiting the ammonium M IV -sulfate (Ce IV , Th IV , and U IV ) phase space targeting rapid crystallization, we isolate the common hexamer [M IV 6 (OH) 4 (O) 4 ] 12+ but with different numbers of capping sulfates and water molecules for Ce IV , Th IV , and U IV . Furthermore, these phases allowed a direct comparison of bonding trends across the series. Upon cocrystallization with the hexamers, higher complex structures can be identified. Thorium features assemblies with monomer-linked hexamer chains. Uranium features assemblies with sulfate-bridged hexamers and the supramolecular assembly of 14 hexamers into the U 84 , [U 6 (OH) 4 (O) 4 ) 14 (SO 4 ) 120 (H 2 O) 42 ] 72– . Last, cerium showcases the isolation from monomers to the Ce 62 , [Ce 62 (OH) 30 (O) 58 (SO 4 ) 71 (H 2 O) 33.25 ] 41– . Furthermore, small-angle X-ray scattering (room temperature) shows ammonium-induced cluster assembly for Ce IV but minimal reactivity for U IV and Th IV . In this study, because the phases crystallized at elevated temperature demonstrates favorable cluster assembly, these solution phase results were surprising and suggest some other characteristics such as Ce’s facile redox behavior, contributes to its solution-phase speciation.
The conceptual framework presented in this Perspective overviews the design principles of innovative thorium-based materials that could address urgent needs of the medicinal, nuclear energy, and waste remediation sectors from the lens of zirconium and uranium analogs. We survey the intersections of Zr, Th, and U chemistry with a focus on how the intrinsic behavior of each metal translates to broader material properties, including, but not limited to, structural and topological diversity, preferential metal–ligand binding, and reactivity. On the example of several classes of materials, including organometallic complexes, polyoxometalates, and the primary focus of this Perspective, metal–organic frameworks (MOFs), the design principles that govern the preparation of Zr-, Th-, and U-compounds, including oxophilicity, variation in oxidation states, and stable coordination environments have been considered. Further, we highlight how the impact of the mentioned variables may shift throughout the progression from discrete molecular systems to extended structures. We discuss the common assumption that zirconium-organic materials are typically considered a close analog of thorium-based congeners in areas such as material design and preparation. Through consideration of fundamental chemistry principles, we shed light on the relationships between Zr-, Th-, and U-based materials and highlight how a critical analysis of their distinct properties can be used to target a desired material performance. Finally, we provide a detailed understanding of Th-based materials chemistry by anchoring their fundamental properties between two well-studied reference points, zirconium- and uranium-containing analogs.
Th(PS3)2 crystallizes in the tetragonal P4_2/m space group. The structure is one-dimensional and consists of one Th(PS3)2 ribbon oriented in the (0, 0, 1) direction. Th4+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are four shorter (2.84 Å) and four longer (3.04 Å) Th–S bond lengths. P4+ is bonded in a trigonal non-coplanar geometry to three S2- atoms. There are two shorter (2.02 Å) and one longer (2.06 Å) P–S bond lengths. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 1-coordinate geometry to two equivalent Th4+ and one P4+ atom. In the second S2- site, S2- is bonded in an L-shaped geometry to one Th4+ and one P4+ atom.
Th(InBr3)2 crystallizes in the monoclinic C2/c space group. The structure is one-dimensional and consists of two Th(InBr3)2 ribbons oriented in the (0, 0, 1) direction. Th4+ is bonded in a 8-coordinate geometry to eight Br1- atoms. There are a spread of Th–Br bond distances ranging from 2.90–3.15 Å. In1+ is bonded in a 1-coordinate geometry to three Br1- atoms. There are a spread of In–Br bond distances ranging from 3.39–3.50 Å. There are three inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a single-bond geometry to one Th4+ atom. In the second Br1- site, Br1- is bonded in a distorted water-like geometry to two equivalent Th4+ and one In1+ atom. In the third Br1- site, Br1- is bonded in a 1-coordinate geometry to one Th4+ and two equivalent In1+ atoms.
Th(PO3)4 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent Th4+ sites. In the first Th4+ site, Th4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Th–O bond distances ranging from 2.38–2.47 Å. In the second Th4+ site, Th4+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Th–O bond distances ranging from 2.36–2.45 Å. There are eight inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.62 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.61 Å. In the third P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.61 Å. In the fourth P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.61 Å. In the fifth P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There is two shorter (1.50 Å) and two longer (1.60 Å) P–O bond length. In the sixth P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.61 Å. In the seventh P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.61 Å. In the eighth P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There is two shorter (1.50 Å) and two longer (1.61 Å) P–O bond length. There are twenty-four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Th4+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two P5+ atoms. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Th4+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Th4+ and one P5+ atom. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to two P5+ atoms. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the ninth O2- site, O2- is bonded in a distorted single-bond geometry to one Th4+ and one P5+ atom. In the tenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Th4+ and one P5+ atom. In the eleventh O2- site, O2- is bonded in a distorted single-bond geometry to one Th4+ and one P5+ atom. In the twelfth O2- site, O2- is bonded in a distorted single-bond geometry to one Th4+ and one P5+ atom. In the thirteenth O2- site, O2- is bonded in a distorted single-bond geometry to one Th4+ and one P5+ atom. In the fourteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Th4+ and one P5+ atom. In the fifteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Th4+ and one P5+ atom. In the sixteenth O2- site, O2- is bonded in a distorted single-bond geometry to one Th4+ and one P5+ atom. In the seventeenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Th4+ and one P5+ atom. In the eighteenth O2- site, O2- is bonded in a distorted linear geometry to one Th4+ and one P5+ atom. In the nineteenth O2- site, O2- is bonded in a distorted single-bond geometry to one Th4+ and one P5+ atom. In the twentieth O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the twenty-first O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the twenty-second O2- site, O2- is bonded in a bent 150 degrees geometry to two P5+ atoms. In the twenty-third O2- site, O2- is bonded in a distorted single-bond geometry to one Th4+ and one P5+ atom. In the twenty-fourth O2- site, O2- is bonded in a distorted single-bond geometry to one Th4+ and one P5+ atom.
ThPt4Ge12 crystallizes in the cubic Im-3 space group. The structure is three-dimensional. Th is bonded to twelve equivalent Ge atoms to form ThGe12 cuboctahedra that share faces with eight equivalent PtGe6 octahedra. All Th–Ge bond lengths are 3.37 Å. Pt is bonded to six equivalent Ge atoms to form PtGe6 octahedra that share corners with six equivalent PtGe6 octahedra and faces with two equivalent ThGe12 cuboctahedra. The corner-sharing octahedral tilt angles are 60°. All Pt–Ge bond lengths are 2.52 Å. Ge is bonded in a 2-coordinate geometry to one Th, two equivalent Pt, and two equivalent Ge atoms. There are one shorter (2.54 Å) and one longer (2.65 Å) Ge–Ge bond lengths.