Lanthanide Clusters Research Articles

Nanomaterials for enhanced X‐ray‐triggered cancer therapy: Progress and prospects

AbstractX‐rays, a form of ionizing radiation with high energy and significant penetration capability, are commonly used in clinical tumor treatment through radiotherapy. Despite their widespread use, optimizing X‐ray efficacy remains a critical challenge due to issues such as radiation resistance and damage to surrounding health tissues. Recent advancements in nanotechnology have introduced new opportunities and challenges in cancer diagnosis and treatment. This review summarizes the latest progress in nanomaterials for X‐ray‐triggered cancer therapy, highlighting their various advantages such as targeted delivery, reduced side effects, and enhanced therapeutic efficacy. We examine how nanomaterials, including metals, metal oxides, metal sulfides, metal fluorides, rare earth oxides, cluster compounds, metal‐organic frameworks, and nanohybrids, enhance the effectiveness of X‐ray‐triggered treatments. Furthermore, we address the current challenges and future prospects of efficient X‐ray‐triggered cancer therapy, aiming to provide a comprehensive overview for researchers and clinicians in the field.

Air and Thermally Stable Fluoride Bridged Rare-Earth Clusters Showing Intense Photoluminescence and Potential LED Application.

Fluoride based lattice is attractive for reducing phonon-induced quenching in rare-earth (RE) based luminescent materials. However, due to the strong affinity betweenRE and oxygen, the synthesis of fluoride-based complexes has to be protected under anhydrous conditions,and many known fluoride bridged RE clusters are unstable in air. Here, by using the "mixed-ligand" strategy a family of fluoride bridged RE clusters is synthesized, namely RE16(μ4-F)6(μ3-F)12(tBuCOO)18[N(CH2CH2O)3]4 (RE = Eu, EuFC-16; RE = Tb, TbFC-16), which are highly stable in air and decomposed thermally only when heating above 435°C. Moreover, both clusters exhibit high photoluminescence quantum yields (PLQYEuFC-16 = 87.7%, PLQYTbFC-16 = 99.0%). Upon warming, EuFC-16 and TbFC-16 displayexcellent structural, thermal, and chroma stability. Thus, EuFC-16 and TbFC-16 have the potential to be used in light-emitting diode (LED) devices, offering many advantages over commercial phosphors. First, both clusters are soluble in UV-curable resin at any mixing rate, and the emission colors can be tuned from magenta, turquoise, willow green, and ivory to pure white if mixing blue phosphor BAM:Eu2+. Second, the clusters are hydrophobic, and the LEDs work well after soaking in water, indicating a good quality for outdoor lighting.

Improved Gaussian basis sets for norm-conserving 4f-in-core pseudopotentials of trivalent lanthanides (Ln = Ce-Lu).

The first-principles quantum chemical computations often scale as Nk (N = basis sets; k = 1-4 for linear scaling, Hartree-Fock or density functional theory methods), which makes the development of accurate pseudopotentials and efficient basis sets necessary ingredients in modeling of heavy elements such as lanthanides and actinides. Recently, we have developed 4f-in-core norm-conserving pseudopotentials and associated basis sets for the trivalent lanthanides [Lu et al., J. Chem. Theory Comput. 19, 82-96 (2023)]. In the present paper, we present a unified approach to optimize high-quality Gaussian basis sets for modeling and simulations of condensed-phase systems. The newly generated basis sets not only capture the low total energy and fairly reasonable condition number of overlap matrix of lanthanide-containing systems, but also exhibit good transferability and reproducibility. These advantages ensure the accuracy of the basis sets while avoiding linear dependency concern of atom-centered basis sets. The performance of the basis sets is further illustrated in lanthanide molecular and condensed-phase systems by using Gaussian-plane wave density functional approach of CP2K. These new basis sets can be of particular interest to model structurally complicated lanthanide molecules, clusters, solutions, and solid systems.

Broadly tunable continuous-wave Tm,Ho:SrF2 and Tm,Ho:BaF2 lasers

We report on the first, to our knowledge, room-temperature continuous-wave laser operation of Tm3+,Ho3+-codoped barium and strontium fluoride crystals at ∼2.1 µm. The 3 at.% Tm, 0.5 at.% Ho:BaF2 laser generated 160 mW at 2073 nm with a slope efficiency of 31.0% and a laser threshold of 43 mW. The continuous wavelength tuning of this laser from 2010 to 2090 nm (tuning range, 80 nm) was demonstrated. The spectroscopic properties of Tm,Ho:SrF2 and Tm,Ho:BaF2 crystals were also determined, showing enhanced Tm3+ → Ho3+ energy transfer in rare-earth clusters. For Ho3+ ions in BaF2, the stimulated-emission cross section is 0.40 × 10−20 cm2 at 2044 nm, and the thermal equilibrium luminescence lifetime is as long as 14.1 ms.

A mixed polynuclear clusters-based Y-MOF with an unprecedented (12, 12, 18)-c topology: highly efficient propylene/ethylene separation and iodine adsorption

The design and synthesis of highly stable metal–organic frameworks (MOFs) bearing unpredictable polynuclear clusters and new topologies are important for the development of novel and complicated MOFs. Herein, the polynuclear rare-earth (RE) clusters with more coordination modes and the small V-shaped ligand (2,5-thiophenedicarboxylic acid) were chosen, and subsequently JLU-MOF132 with three different yttrium clusters (two independent Y6 and one Y9 clusters) and a novel (12, 12, 18)-connected topology was successfully synthesized. Notably, JLU-MOF132 exhibits high porosity, excellent thermal, acid-base, and solvent stabilities. JLU-MOF132 shows considerable potential in methanol-to-olefins (MTO) products (C3H6 and C2H4) separation. The high ideal adsorbed solution theory C3H6/C2H4 selectivities (9.2, 10.6, and 15.1) and the breakthrough experiments results, including the high C2H4 purity (>99.9 %) and productivities (26.1, 73.1, and 101.0 L·kg-1), demonstrate its practical purification capability. Semi-empirical tight binding (xTB) quantum chemical calculations explain the mechanisms that differentiate C2H4 and C3H6 adsorption in JLU-MOF132. In addition, JLU-MOF132 also displays outstanding radioactive iodine adsorption performance, with an iodine uptake of 750 mg·g-1 in vapor and 153 mg·g-1 in cyclohexane solutions. Briefly, this work not only demonstrates the viability of employing the V-shaped ligand to increase the structural diversity of highly stable MOFs, but also enhances the application potential of MOFs in the fields of the MTO products separation and radioactive iodine adsorption.

One-Pot In Situ Construction of a Highly Stable Acylhydrazone-Derived Dy9 Cluster with Photodynamic Sterilization Property.

The extremely low stability of lanthanide clusters with precise structures and nanometer dimensions in aqueous solutions limits their application in the field of photodynamic sterilization. In this study, an hourglass-shaped nine-nucleated Dy9 cluster (1) with excellent light-driven reactive oxygen species (ROS) generation ability and photodynamic sterilization property was constructed using acylhydrazone multidentate chelating ligands obtained via an in situ reaction. The eight chelating ligands were distributed outside cluster 1, tightly wrapping the cluster core, thus preventing solvent molecules from attacking the cluster nucleus and ensuring the stability of cluster 1 in solution, which was demonstrated via X-ray diffraction and high-resolution electrospray ionization mass spectrometry (HRESI-MS). Time-dependent HRESI-MS monitoring of the self-assembly process of cluster 1 allowed two possible self-assembly mechanisms. The heavy atom effect of multiple Dy(III) ions in the Dy9 cluster enhanced the ISC pathway through spin-orbit coupling, promoting energy transfer from the excited singlet state (S1) to the triplet state (T1), which was stabilized, inducing the generation of more ROS. Cluster 1 showed a remarkable sterilization effect due to the generation of abundant ROS under light irradiation conditions. To our knowledge, this is a rare instance of lanthanide clusters with photodynamic sterilization, providing new horizons for the construction of fast and efficient sterilizers.

A Homochiral Hexagadolinium Phosphonate Cluster: Structure, Chiral Electrochemical Recognition and a Large Magnetocaloric Effect

AbstractChiral lanthanide clusters have promising applications in chiral recognition, magneto‐optical memories, and spintronic devices. Nonetheless, the precise prediction and controlled development of homochiral polynuclear Ln‐complexes is still a challenge. Herein, through multidentate chelate synthetic strategy, a new homochiral hexagadolinium phosphonate cluster designated as R/S‐[Gd6(pmhpH)8(NO3)2(H2O)8]⋅19H2O (R/S‐1) was successfully obtained by reacting chiral phosphonomethylhomoproline(pmhpH3) with Gd(III) salt. The cluster, shaped like a lantern, is constructed from {GdO8} polyhedra and {PO3C} tetrahedra surrounded by eight pmhpH2− ligands. Within the structure, two types of gadolinium ions with different coordination modes are observed. Each Gd(III) ion is bound to two carboxylate oxygens and six phosphonate oxygens from the coordinated pmhpH2− ligands. Circular dichroism spectra comfirmed that R/S‐1 exists as a pair of enantiomers. Moreover, the cluster exhibits high thermal stability, decomposing at temperatures exceeding 335 °C. Notably, the chiral cluster materials can be used for enantiomeric recognition for tryptophan (Trp) with the differential pulse voltammetry (DPV) peak current ratio (ID/IL) 2.74. Besides, the magnetic measurements revealed that compound R‐1 exhibits a good magnetocaloric effect (MCE) with a maximum entropy change of −ΔSmmax=36.84 Jkg−1 K−1 at T=2 K and ΔH=7 T.

A Recyclable Inorganic Lanthanide Cluster Catalyst for Chemoselective Aerobic Oxidation of Thiols.

Optimizing lanthanide catalyst performance with organic ligands often encounters significant challenges, including susceptibility to water or oxygen and complex synthesis pathways. To address these issues, our research focuses on developing inorganic lanthanide clusters with enhanced stability and functionality. In this study, we introduce the [Sm6O(OH)8(H2O)24]I8(H2O)8 cluster (Sm-OC) as a sustainable and efficient catalyst for the aerobic oxidation of thiols under heating conditions. The Sm-OC catalyst demonstrated remarkable stability, outstanding recyclability, and excellent chemoselectivity across a diverse range of functional groups in 38 different tests. Notably, it enables efficient unsymmetrical disulfide synthesis and prevents the formation of over-oxidized by-products, highlighting its superior performance. This Sm-OC catalyst provides a practical and robust tool for the precise construction of versatile disulfides, thus establishing a template for the broader use of lanthanide clusters in organic synthesis.

Enantioselective Synthesis of Homochiral Hierarchical Nd8Fe3-Oxo Cluster from Racemic Nd9Fe2-Oxo Cluster.

Enantioselective synthesis of homochiral rare earth clusters is still a great challenge. In this work, we developed an efficient "cluster to cluster" approach, that is, a pair of enantiomerical R/S-{Nd8Fe3}-oxo clusters were successfully obtained from the presynthesized racemic {Nd9Fe2}-oxo cluster. R/S-hydrobenzoin ligands trigger the transformation of the pristine clusters by an SN2-like mechanism. Compared to the pristine cluster with an achiral core, the new cluster exhibits hierarchical chirality, from ligand chirality to interface chirality, then to helix chirality, and finally to supramolecular double helix chirality. The spectral experiments monitored the transformation and confirmed distinctly structure-related optical activity. The enantiomeric pure cluster also exhibits a potential asymmetric catalytic activity.

Structural properties and aromaticity of rare-earth doped tin cluster anion: MSn9− (M = Sc, Y, La)

Doping rare earth elements into clusters can significantly improve the performance and application value of the materials. The structure, bonding properties, stability, and aromaticity of MSn9− (M = Sc, Y, La) have been investigated using density-functional theory. The global minimum structure of these clusters is determined to be the addition of a triangle to the vertex position of a pentagonal bipyramid. Ab initio molecular dynamics simulations are used to demonstrate the thermal stability of the structure. Bonding analyses indicate the presence of ionic bonding and covalent bonding. Iso-chemical shielding surfaces and the gauge-including magnetically induced currents indicate that MSn9− clusters are significantly aromatic. This study provides a comprehensive understanding of tin-based nanomaterials, which is important for their design and synthesis.

Yb-to-Eu Cooperative Sensitization Upconversion in a Multifunctional Molecular Nonanuclear Lanthanide Cluster in Solution.

Lanthanide metal clusters excel in combining molecular and material chemistry properties. Here, we report an efficient cooperative sensitization UC phenomenon of a Eu3+/Yb3+ nonanuclear lanthanide cluster in CD3OD. The synthesis and characterization of the heteronuclear cluster in the solid state and solution are described together with the UC phenomenon showing Eu3+ luminescence in the visible region upon 980 nm NIR excitation of Yb3+ at concentrations as low as 100 nM. Alongside being the Eu/Yb cluster to display UC (with a quantum yield value of 4.88 × 10-8 upon 1.13 W cm-2 excitation at 980 nm), the cluster exhibits downshifted light emission of Yb3+ in the NIR region upon 578 nm visible excitation of Eu3+, which is ascribed to sensitization pathways for Yb through the 5D0 energy levels of Eu3+. Additionally, a faint emission is also observed at ca. 500 nm upon 980 nm excitation, originating from the cooperative luminescence of Yb3+. The [Eu8Yb(BA)16(OH)10]Cl cluster (BA = benzoylacetonate) is also a field-induced single-molecular magnet (SMM) under 4K with a modest Ueff/kB of 8.48 K, thereby joining the coveted list of Yb-SMMs and emerging as a prototype system for next-generation devices, combining luminescence with single-molecular magnetism in a molecular cluster.

Complexation of Sc3N@C80 as a model rare-earth nitride cluster fullerene with different crystallizing agents: A DFT analysis

We report on a computational study (at the PBE-D2/DNP level of DFT) of the bonding strength, geometry and selected electronic properties of the noncovalent dyads between different crystallizing agents (CAs) and the scandium nitride cluster (Sc3N) encapsulated by Ih-C80 endohedral fullerene (Sc3N@C80). The crystallizing agents studied were nickel(II) octaethylporphyrin (NiOEP), decapyrrylcorannulene (DPC), Zn tetraphenyl porphyrin (ZnTPP), and Ni tetramethyldibenzo-tetraazaannulenato (NiTMTAA). The strength of noncovalent interactions between the NCF and CAs decreases in the following order: Sc3N@C80 + NiOEP-in > Sc3N@C80 + DPC > Sc3N@C80 + NiOEP-out > Sc3N@C80 + ZnTPP > Sc3N@C80 + NiTMTAA-me > Sc3N@C80 + NiTMTAA-bz. The Sc⋯CC80 distances show negligible changes for the NCF in all the cases. The inner cluster Sc3N remains always planar despite of the use of different CAs. Two general patterns of HOMO-LUMO distribution were found. The dominating one, found in all the dyads except for the two formed with NiOEP, is when no HOMO fraction is detected on Sc3N@C80 component, but instead solely on the corresponding CA; on the contrary, the LUMO is concentrated on NCF.

2D Ionic Liquid-Like State of Charged Rare-Earth Clusters on a Metal Surface.

Rare-earth complexes are vital for separation chemistry and useful in many advanced applications including emission and energy upconversion. Here, 2D rare-earth clusters having net charges are formed on a metal surface, enabling investigations of their structural and electronic properties on a one-cluster-at-a-time basis using scanning tunneling microscopy. While these ionic complexes are highly mobile on the surface at ≈100 K, their mobility is greatly reduced at 5 K and reveals stable and self-limiting clusters. In each cluster, a pair of charged rare-earth complexes formed by electrostatic and dispersive interactions act as a basic unit, and the clusters are chiral. Unlike other non-ionic molecular clusters formed on the surfaces, these rare-earth clusters show mechanical stability. Moreover, their high mobility on the surface suggests that they are in a 2D liquid-like state.

Cl--templated coordination polymers constructed from dragonfly-like Ln4 clusters exhibiting excellent magnetothermal properties.

Lanthanide clusters with high magnetic entropy and an exquisite structure have always been a hot research direction. Herein, two delicately structured lanthanide clusters were synthesized using isonicotinic acid (HIN) as a ligand by the solvothermal method, namely {[Gd4(IN)4(μ3-OH)4(OAc)2(H2O)6]·Cl2·7H2O}n (1) and {[Dy4(IN)4(μ3-OH)4(OAc)2(H2O)6]·Cl2·8H2O}n (2). Structural analysis indicates that the two compounds exhibit comparable structures, and both have the same cubane-like Ln4 metal skeleton and form an interesting dragonfly molecular configuration by connecting to HIN. Moreover, {Ln4} serves as the fundamental structural unit for the construction of a 1D channel of 1, with a diameter of approximately 10.08 Å, which is connected to each other by extra {Ln4} units to form an exquisite porous 3D structure of 1. Cl- exists as an anion-template in its 3D structure, balancing the charge and maintaining its structural stability. Magnetic measurements indicate that 1 exhibits a rather satisfactory magnetic entropy change, reaching a maximum value of -ΔSmaxm = 31.59 J kg-1 K-1 at 2 K for ΔH = 7 T.

Exploring the stability and aromaticity of rare earth doped tin cluster MSn16- (M = Sc, Y, La).

Rare earth elements have high chemical reactivity, and doping them into semiconductor clusters can induce novel physicochemical properties. The study of the physicochemical mechanisms of interactions between rare earth and tin atoms will enhance our understanding of rare earth functional materials from a microscopic perspective. Hence, the structure, electronic characteristics, stability, and aromaticity of endohedral cages MSn16- (M = Sc, Y, La) have been investigated using a combination of the hybrid PBE0 functional, stochastic kicking, and artificial bee colony global search technology. By comparing the simulated results with experimental photoelectron spectra, it is determined that the most stable structure of these clusters is the Frank-Kasper polyhedron. The doping of atoms has a minimal influence on density of states of the pure tin system, except for causing a widening of the energy gap. Various methods such as ab initio molecular dynamics simulations, the spherical jellium model, adaptive natural density partitioning, localized orbital locator, and electron density difference are employed to analyze the stability of these clusters. The aromaticity of the clusters is examined using iso-chemical shielding surfaces and the gauge-including magnetically induced currents. This study demonstrates that the stability and aromaticity of a tin cage can be systematically adjusted through doping.

Different anion (NO3- and OAc-)-controlled construction of dysprosium clusters with different shapes.

The complex hydrolysis process and strong uncertainty of self-assembly rules have led to the precise synthesis of lanthanide clusters still being in the "blind-box" stage and simplifying the self-assembly process and developing reliable regulation strategies have attracted widespread attention. Herein, different anions are used to induce the construction of a series of dysprosium clusters with different shapes and connections. When the selected anion is NO3-, it blocks the coordination of metal sites around the cluster through the terminal group coordination mode, thereby controlling the growth of the cluster. When NO3- was changed to OAc-, OAc- adopted a bridging mode to induce modular units to build dysprosium clusters through an annular growth mechanism. Specifically, we selected 2-amino-6-methoxybenzoic acid, 2-hydroxybenzaldehyde, and Dy(NO3)3·6H2O to react under solvothermal conditions to obtain a pentanuclear dysprosium cluster (1). The five Dy(III) ions in 1 are distributed in upper and lower planes and are formed by the tight connection of nitrogen and oxygen atoms, and μ3-OH- bridges on the ligand. Next, octa-nuclear dysprosium cluster (2) were obtained by only regulating ligand substituents. The eight Dy(III) ions in 2 are tightly connected through ligand oxygen atoms, μ2-OH-, and μ3-OH- bridges, forming an elliptical {Dy/O} cluster core. Furthermore, only by changing NO3- to OAc-, a wheel-shaped tetradeca-nuclear dysprosium cluster (3) was obtained. Cluster 3 is composed of OAc- bridged multiple template Dy3L3 units and pulling of these template units connected by an annular growth mechanism forms a wheel-shaped cluster. The angle of the coordination site on NO3- is ∠ONO = 115°, which leads to the further extension of the metal sites on the periphery of clusters 1 and 2 through the terminal group coordination mode, thereby regulating the structural connection of the clusters. However, the angle of the coordination site on OAc- is ∠OCO = 128°, and a slightly increased angle leads to the formation of a ring-shaped cluster 3 by connecting the template units through bridging. This is a rare example of the controllable construction of lanthanide clusters with different shapes induced by the regulation of different anions, which provides a new method for the precise construction of lanthanide clusters with special shapes.

Hg2+ detection and information encryption of new [1+1] lanthanide cluster

The sensing of heavy metal ion and information encryption are two very important research areas. Therefore, developing multi-functional materials capable of sensing heavy metal ions and encrypting information is highly important. In this work, three [1 + 1] lanthanide clusters [Ln(TFBA)3(dmp) (H2O)2]2 (Ln = Tb3+Tb1+1, Eu3+Eu1+1, Gd3+Gd1+1, HTFBA = 2,3,4,5-tetrafluorobenzoic acid, dmp = 4,7-dimethyl-1,10-phenanthroline) were designed and synthesized. Among them, Tb1+1 shows excellent luminescence sensing towards Hg2+ (Ex = 350 nm, Em = 545 nm). Results demonstrates the sensing with high selectivity, strong anti-interference, 20-s response time, high accuracy, excellent linear relationship in 0–20.0 μM, and a very low limit of detection (0.02 ppb). Furthermore, paper strips based on Tb1+1 is fabricated for visual detection of Hg2+ in real samples of tap water, lake water, human urine, and human serum. More interestingly, a new method for confidentiality of information is realized through multi-color anti-counterfeiting patterns with the [1 + 1] lanthanide cluster ink, based on the luminescence “on-off” sensing towards Hg2+.

A lanthanide cluster formed by fixing atmospheric CO2 to carbonate: a molecular magnetic refrigerant and photoluminescent material

A lanthanide cluster formed by fixing atmospheric CO2 to carbonate: a molecular magnetic refrigerant and photoluminescent material

Tricine-supported polyoxo(alkoxo)lanthanide cluster {Ln15} (Ln = Eu, Gd, Tb) with magnetic refrigerant and fluorescent properties

A family of polyoxo(alkoxo)lanthanide cluster {Ln₁₅} [Ln = Eu (<strong>1</strong>), Gd (<strong>2</strong>), Tb (<strong>3</strong>)] was successfully isolated via the simple hydrolysis reaction of lanthanide metal ions in the presence of tricine ligand. X-ray diffraction analyses revealed the {Ln₁₅} display a wheel-like structure with a <em>µ</em>₅-chloride anion as template. Interestingly, each analogue shows distinctive function based on the different Ln(III) ions. The complexes <strong>1</strong> and <strong>3</strong> in solid state emitted the characteristic fluorescence of Eu(III) or Tb (III). The fluorescence lifetimes of ⁵<em>D</em>₀ excited state for <strong>1</strong> and ⁵<em>D</em>₄ excited state for <strong>3</strong> were tested and the values were 890 and 250 μs, respectively. For gadolinium analogue <strong>2</strong>, it exhibits magneto-caloric effect at ultralow temperatures with a maximum −Δ<em>S</em>_m value of 29.9 J·kg⁻¹·K⁻¹ at 3 K and 7 T.

Photochromic Polyoxoniobates with Photoinduced “D‐f‐A” Electron Transfer Mechanism

AbstractCompounds with redox activities have appealing applications in catalytic, electronic and magnetic properties, but the redox inert of polyoxoniobates (PONbs) significantly limits their applications for a long time. In this work, we are able to integrate organophosphate and lanthanide cluster into PONb to create the first family of inorganic‐organic hybrid organophosphate‐Ln‐PONb composite clusters. These novel species not only present the first family of redox active PONbs that can be reduced to form long‐lived “heteropoly blues” under ambient conditions, but also a new photochromic system. More importantly, the analyses of the electronic configurations and photochromic properties for a series of designed proof‐of‐concept PONbs models allow us to discover a D‐f‐A electron transfer mechanism, that is, photoinduced electron is transferred from a photosensitive organophosphate electron donor (D) to the NbV electron acceptor (A) through the unoccupied 4 f‐orbitals of Ln (f). This work paves the way for developing diverse PONb‐based redox materials and expanding the possibility of the applications of PONbs in the redox chemistry.