Cage Clusters Research Articles

Construction of Mo/S/Ag Cluster Complexes from Dinuclear Molybdenum Precursors [R4N]2[(edt)2Mo2S2(μ‐S)2] (R = Et, nPr; edt = −SCH2CH2S−)

AbstractWe have demonstrated that complexes [(edt)2Mo2O2(μ‐S)2Ag2(dppm)2]·4CH3OH·DMF (2, edt = 1,2‐ethanedithiolate dianion, dppm = bis(diphenylphosphino)methane, DMF = N,N‐dimethylformamide) and [(μ‐Cl)2Ag4(μ3‐Cl)2(dppm)2]·4DMF (3), were generated by combining a dinuclear molybdenum precursor [Et4N]2[(edt)2Mo2S2(μ‐S)2] (1a) with two equimolar AgCl and dppm in a CH3OH‐DMF mixed solution. Treatment of complex 1a with one equimolar AgCl and DPEPhos in CH3OH and DMF mixed solutions, producing complex [Et4N][(edt)2Mo2S2(μ‐S)2Ag(DPEPhos)]·CH3OH (4, DPEPhos = bis(2‐diphenylphosphinophenyl)ether). Treatment of complex [nPr4N]2[(edt)2Mo2S2(μ‐S)2] (1b) with AgBr in acetonitrile followed by addition of (NH4)2S produced a dodecanuclear Mo–Ag–S cage cluster [nPr4N]2[{Mo2Ag2S2O2(edt)2}3(μ6‐S)]·1.5CH3CN (5). Complexes 2−5 have been characterized by infrared(IR), 1H NMR, UV‐vis, and fluorescence spectroscopies. Moreover, molecular structures of complexes 2−5 have been established by single‐crystal X‐ray crystallography.

Growth Patterns of Carbon Clusters Cn (n = 2-60) Identified via ABCluster Searching and DFT Benchmarking.

Recently, novel algorithms and enhanced computational capabilities have created unprecedented opportunities to precisely determine the geometric structures of clusters through theoretical calculations. In this study, we extensively investigated and characterized the geometric arrangements of the carbon clusters Cn (n = 2-60), employing the efficient ABCluster algorithm in conjunction with the gradient-corrected PBE and higher-accuracy B3LYP hybrid functional in density functional theory (DFT). New structures and a discernible structural growth pattern have been discovered. We observed a distinct preference in carbon clusters that transform from the linear chains (n = 2-9) to closed single-ring and planar structures (n = 10-27) and finally evolve to carbon cages (n = 28-60). A shortcut to construct the cage clusters was unveiled by inserting or rotating specific atoms within a distinct structural unit. The research results obtained from combining ABCluster with DFT calculations offer valuable new insights into the growth mechanisms and evolutionary trajectories of carbon clusters, providing a crucial theoretical framework for the development of innovative carbon-based materials and their potential applications.

Formation of Uranyl Peroxide Compounds via Dissolution of Studtite, [(UO2)(O2)(H2O)2](H2O)2, in Ionic Liquids.

Four uranyl peroxide compounds with novel structures were formed following the dissolution of studtite, [(UO2)(O2)(H2O)2](H2O)2, in imidazolium-based ionic liquids. The compounds were characterized using single crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), Raman and infrared (IR) spectroscopy, and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). The ionic liquids used in the experiments were 1-ethyl-3-methylimidazolium (EMIm) diethyl phosphate, EMIm ethyl sulfate, and EMIm acetate. Each of the four uranyl peroxide compounds contain components from the ionic liquids as terminal ligands on uranyl peroxide molecular units, bridging ligands in uranyl peroxide sheet structures, or charge balancing cations located in the interstitial space. The studtite dissolved in and reacted with the ionic liquids, producing unique crystal structures depending on the anionic component of the ionic liquid, the temperature at which the synthesis was performed, and the introduction of additional ionic species into the solution. This is the first report of studtite dissolving in and reacting with ionic liquids to form uranyl peroxide compounds, which has the potential to vastly increase the number of synthetic routes for the formation of uranyl peroxide clusters and uranyl peroxide cage clusters.

High-Nuclearity Ln210Al140 Clusters: Neonates of Open Hollow Dodecahedral Cage Families.

Open hollow dodecahedral cage clusters have long been a coveted target in synthetic chemistry, yet their creation poses immense challenges. Here we report two open hollow dodecahedral lanthanide-aluminum (Ln-Al) heterometallic cage clusters, namely, [Ln210Al140(μ2-OH)210(μ3-OH)540(OAc)180(H2O)156](ClO4)120·(MeCN)x·(H2O)y, (Ln = Dy and x = 27, y = 300 for 1; Ln = Y and x = 28, y = 420 for 2). Remarkably, the 350 metal atoms in 1 and 2 display a Keplerate-type four-shell structure of truncated icosidodecahedron@dodecahedron@dodecahedron@icosidodecahedron. The diameter of the cationic cluster in 1 is approximately 5.0 nm, with an inner cavity diameter of about 2.8 nm and a window diameter of roughly 0.66 nm. The cluster in 1 boasts an accessible inner void volume of up to 15,000 Å3. Notably, these cage clusters maintain stability in water, and the truncated icosidodecahedrons in 1 and 2 are the first of their kind synthesized to date. Given that the open hollow dodecahedral Ln-Al cage cluster has never been reported before, this work represents a member in the family of hollow open dodecahedral cages.

The magnetic modulation by the valence transition of polyoxometalate

Three novel vanadoborates with crown-shaped V12B32 cluster cages were successfully synthesized, differing only in their countercation. X-ray photoelectron spectroscopy (XPS) and Bond valence sum (BVS) analyses revealed distinct V4+/V5+ ratios (11:1, 10:2, and 10:2) in the cluster cage of the three compounds. Structural analyses indicated that the valence state ratio was modulated by the countercation. The magnetic properties of these compounds were examined using variable-temperature magnetic susceptibilities and two-dimensional correlation infrared spectroscopy (2D-COS-IR) under magnetic perturbation. This approach elucidated the origin and variability of their magnetic properties, demonstrating that the vanadium valence ratio and countercation significantly influence the magnetic behaviour of vanadoborates. The present study highlights the effectiveness of the transition of the vanadium valence state in the cluster cage by altering the countercation, providing a new avenue for the study of magnetically modulated materials.

Luminescence properties of endohedrally doped group-IV clusters.

Endohedrally doped clusters form a large category of cage clusters, with unique structures, diverse elemental compositions, and highly tunable electronic structures and physisochemical properties. They have been widely achieved in laboratory and may serve as functional building blocks for assembling new supermolecular structures and devices. In this paper, for the first time, we disclosed the luminescence properties of endohedrally doped group-IV clusters by time-dependent density functional theory calculations. A total of 64 cage clusters have been explored in terms of stability, emission wavelength, and the energy difference between the first excited singlet and triplet states. The key geometric and electronic factors governing the photophysical properties of these cage clusters were unveiled, to provide crucial insights for crafting atomically precise nanoclusters for optical and optoelectronic applications.

Electrocatalytic and photocatalytic activities of two alkynyl Ag20 cage clusters involved ligand exchange between PhCOO− and CF3COO−

Two silver alkynyl clusters, [(CO32−)@Ag20(tBuC≡C)14(PhCOO)3(CF3COO)] (1) and [(CO32−)@Ag20(tBuC≡C)14(PhCOO)(CF3COO)3] (2), composed of alkynyl Ag20 shell templated by a CO32− anion and supported by carboxyl ligands PhCOO− and CF3COO−, were synthesized successfully by conventional methods. Single crystal X–ray diffractometer (SCXRD) was used to determine the precise structures of 1 and 2. Although compounds 1 and 2 have the [(CO32−)@Ag20(tBuC≡C)14]4+ unit, the numbers of PhCOO− and CF3COO− ligands along with Ag···Ag interactions were affected by the steric hindrance of different carboxyl ligands and their concentrations. That is, compounds 1 and 2 separately contain the [(CO32−)@Ag20(tBuC≡C)14(PhCOO)(CF3COO)]2+ unit, which is involved in the ligand exchange between PhCOO− and CF3COO−. Powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA) were used to characterized compounds 1 and 2. The photocurrent responses, absorption spectra, as well as luminescence of 1 and 2 have been studied. In addition, the reduction of H2O2 for GCE–1 and GCE–2 showed good electrocatalytic activity, and catalysts 1 and 2 showed good photocatalytic degradation efficiency of methylene blue (MB). The results suggest that 1 and 2 can act as new electrocatalysts and photocatalysts to detect and decompose organic pollutants and hazardous materials in wastewater.

Synthesis and functionalities of FeSn12 superatom prepared by single atom introduction with a dendrimer template.

Superatoms are promising as new building block materials that can be designed by precise controlling of the constituent atoms. Stannaspherene (Sn12 2-) is a rigid cage-like cluster with icosahedral symmetry, for which one-atom encapsulation was theoretically expected and detected in the gas phase. Here, a single-atom introduction method into stannaspherene using a dendrimer template with polyvinylpyrrolidone (PVP) protection is demonstrated. This advanced solution-phase synthesis allows not only the selective doping of one atom into the cluster cage, but also enable further detail characterization of optical and magnetic properties that were not possible in the gas-phase synthesis. In other words, this liquid-phase synthesis method has enabled the adaptation of detailed analytical methods. In this study, FeSn12 was synthesized and characterized, revealing that a single Fe atom introduction in the Sn12 2- cage result in the appearance of near-infrared emission and enhancement in the magnetism.

Eco-Friendly Encapsulation of Metal Clusters in Porous Organic Cages for Engineerable Microenvironment and Enhanced Catalysis

Eco-Friendly Encapsulation of Metal Clusters in Porous Organic Cages for Engineerable Microenvironment and Enhanced Catalysis

Carboxonium derivatives based on closo-dodecaborate anions [1,2-B12H10O2CR]−: synthesis and molecular orbital analysis

Borylated carboxonium ions based on closo-dodecaborate anions were obtained. The nature of the interaction between the cluster cage and the organic moiety was analysed theoretically.

Activation of uranyl peroxides by ionizing radiation prior to uranyl carbonate formation.

The solid form of the uranyl peroxide cage (UPC) cluster LiU28 (Li28[(UO2)28(O2)42]) was irradiated by 5 MeV He2+ ions to achieve doses up to 42 MGy. An intermediate compound formed that reacts with atmospheric CO2 to form uranyl carbonates. The role of water in the UPC to uranyl carbonate transformation was studied by flowing either dry or hydrated Ar over samples during He2+ irradiation, and by storing samples in dry and humid environments before and after irradiation. Raman, infrared, and X-ray photoelectron spectroscopies and electrospray ionization mass spectrometry were used to characterize solid Li-U28 salts before and after He2+ irradiation. The highest yield of uranyl carbonates occurred when hydrated Ar gas was flowed across the sample during He2+ irradiation. Electron paramagnetic resonance spectroscopy provided evidence of hydroxyl and superoxide radicals in both unirradiated and γ-irradiated Li-U28.

The tetracyanoborate anion as a building block for the heterocubane cluster cage [Cr4{B(CN)4}4]4.

The tetracyanoborate anion [B(CN)4]- (TCB) was utilized as a building block for the synthesis of polynuclear chromium carbonyl compounds upon photolytic reaction with [Cr(CO)6]. Up to four κN-coordinated cyano groups of TCB can be involved in binding to chromium, giving mixtures of [B(CN)4-x{CN-Cr(CO)5}x]- (x = 1-4; 1-4) and [{Cr(CO)4(B(CN)4)}2]2- (5). The reaction of [B(CN)4]- with fac-[Cr(CO)3(MeCN)3] led to isolation of salts of the tetraanionic heterocubane cage [{Cr(CO)3(B(CN)4)}4]4-.

Evolution of Polynuclear Gold(I) Sulfido Complexes from Clusters and Cages to Macrocycles.

Two unprecedented tetratriacontanuclear and tetraicosanuclear gold(I) sulfido clusters (denoted as Au34-LMe and Au24-LCbz) with different temperature-induced stimulus-responsive behavior and emission property have been constructed by taking advantage of the judiciously designed bidentate phosphine ligand. Au34-LMe represents the highest nuclearity of the gold(I) sulfido cluster with more than a thousand atoms in the molecule. Octagonal macrocycles based on metal-cluster nodes have been assembled for the first time. The self-assembly and temperature-induced stimulus-responsive processes were monitored by 1H and 31P{1H} NMR spectroscopy, and the identities of the discrete gold(I) complexes were established by single-crystal structural analysis and high-resolution electrospray ionization mass spectrometry data. The steric effects exerted by the substituents on the V-shaped 1,3-bis(diphenylphosphino)benzene ligand have been shown to govern the self-assembly from the 1D cluster and 3D cage to 2D macrocycles. This work not only offers a new strategy to construct and regulate the structure of 2D macrocyclic gold(I) sulfido complexes but also lays the foundation for the future precise design and controlled construction of higher polygonal and cluster-node macrocycles.

Theoretical investigation of CB5H6(Hfac) and CB5H5(H2) carboranes: Combined MO and QTAIM analysis

Anion [CB5H6]– is suitable object for molecular modeling of carborane properties. Its protonated form CB5H6(Hfac) has been of special interest to researchers for several decades. One of the reasons of such interest is the nature of chemical bonding between additional Hfac and cluster cage. In present research, the nature of given interaction was investigated with the analysis of molecular orbitals and topology of electron density. This combined analysis allows to rigorous and clear representation of bonding nature between Hfac and cluster cage. CB5H6(Hfac) can be isomerized to systems in which boron atom attached to two hydrogen atoms CB5H5(H2). The electronic structure of CB5H5(H2) was also investigated in detail in present study. CB5H6(Hfac) and CB5H5(H2) are the key intermediates in EINS (electrophile induced nucleophilic substitution) process. Extensive investigation of structure of these systems gives an insight on EINS substitution process not only in the [CB5H6]– anion, but also for the whole family of carborane systems.

Nanoscale calcium uranyl carbonate clusters in water

Aqueous calcium uranyl carbonate complexes are the predominant form of U(VI) in neutral to alkaline water in the environment, including seawater. We report a robust and repeatable synthesis of a nanoscale [(UO2)24O4(OH)12(CO3)36]44− cage cluster that we co-crystallized with Ca and Na countercations and determine its structure using single-crystal X-ray diffraction. Crystals were harvested and dissolved in water, followed by collection of electrospray ionization-mass spectra (ESI-MS). Introduction of a pH 8.1 solution containing 1.19 ± 0.04 mmol·L−1 U into the spectrometer produced broad m/z peak envelopes with −7 and 6 charge states at 1375, 1430, 1530, 1600, and 1675 m/z corresponding to mass 9625, 10,010, 10,710, 9600 and 10,080 amu, respectively. The spectra are consistent with [(UO2)24O4(OH)12(CO3)36]44− in solution (8909.07 amu), together with charge-balancing cations and H2O. Intentional fragmentation of the clusters yielded uranyl hydroxide and uranyl carbonate species containing Na. The [(UO2)24O4(OH)12(CO3)36]44− cluster is similar to that found in the mineral ewingite, which has been found to form in mine waters of an abandoned uranium mine. Demonstration of persistence of a nanoscale Ca uranyl carbonate cage cluster in aqueous solution reveals the need to re-examine aspects of environmental metal speciation to evaluate the extent to which nanoscale clusters may be important. SynopsisThis study demonstrates the existence of a nanoscale aqueous uranyl carbonate macroion at environmentally relevant pH conditions using mass spectrometry.

Cover Picture

The cover picture depicts two oxide cluster, Lu2O and Er2O, nested in the robust Cs(6)‐C82 fullerene cage, respectively. Their crystallographic structures display a large variation in the angles of the clusters within the cage (146.74° vs. 116.51°), suggesting flexible configurations of the oxide clusters heavily dependent on the radius of encapsulated metal ions. This work discloses the role of metal species in adjusting cluster conformation, and facilitates the understanding of interplay between the encapsulated cluster and host cage. More details are discussed in the article by Lu et al. on page 1915—1920.image

Theoretical Insight on the Formation Mechanism of a Trisubstituted Derivative of Closo-Decaborate Anion [B10H7O2CCH3(NCCH3)

A theoretical modelling of the interaction process between a protonated complex of carboxonium derivative [2,6-B10H8O2CCH3*Hfac]0 and acetonitrile molecule CH3CN was carried out. As a result of the process, a trisubstituted [B10H7O2CCH3(NCCH3)]0 derivative was formed. This reaction has an electrophile-induced nucleophilic substitution (EINS) mechanism. The main intermediates and transition states of the substitution process were established. As in the case of all previously investigated EINS processes, the key intermediate was an anion with a dihydrogen H2 fragment attached to one boron atom (B(H2) structure motif). The process of nucleophilic substitution can proceed on a different position of the cluster cage. The main potential pathways were assessed. It was established that substitution on the B4 position of the cluster cage was the most energetically favourable, and the [2,4,6-B10H7O2CCH3(NCCH3)]0 isomer was formed.

Robust magnetism of the cluster assembled (Fe@In6)Ba2 crystal

Fe@In6 is the smallest transition metal doped endohedral cage cluster. Its anion, with an octahedral geometry of Oh symmetry, has three singly occupied degenerate orbitals with the ground electronic state 4A1g. Global optimization based on the evolutionary algorithm combined with density functional theories shows that the lowest energy structure of the crystal assembled by Fe@In6 and Ba2 is spin polarized, and the crystal structure is slightly deviated from the fcc (face centered cubic) structure due to the spin-polarization. The magnetic moment is 2.45 μB per Fe@In6Ba2 unit, and the magnetism is very robust. The formation enthalpy of the crystal reaches −1.1 eV per atom, and the spin-polarized state is 2.36 eV lower in energy than the non-polarized state. Calculations also demonstrate that the magnetic moments change linearly with the pressures imposing on the polarization direction. The present study provides a new way for designing cluster assembled magnetic materials by transition metal doped clusters.

Electrochemistry of Uranyl Peroxide Solutions during Electrospray Ionization.

The ionization of uranyl triperoxide monomer, [(UO2)(O2)3]4- (UT), and uranyl peroxide cage cluster, [(UO2)28(O2)42-x(OH)2x]28- (U28), was studied with electrospray ionization mass spectrometry (ESI-MS). Experiments including tandem mass spectrometry with collision-induced dissociation (MS/CID/MS), use of natural water and D2O as solvent, and use of N2 and SF6 as nebulizer gases, provide insight into the mechanisms of ionization. The U28 nanocluster under MS/CID/MS with collision energies ranging from 0 to 25 eV produced the monomeric units UOx- (x = 3-8) and UOxHy- (x = 4-8, y = 1, 2). UT under ESI conditions yielded the gas-phase ions UOx- (x = 4-6) and UOxHy- (x = 4-8, y = 1-3). Mechanisms that produce the observed anions in the UT and U28 systems are: (a) gas-phase combinations of uranyl monomers in the collision cell upon fragmentation of U28, (b) reduction-oxidation resulting from the electrospray process, and (c) ionization of surrounding analytes, creating reactive oxygen species that then coordinate to uranyl ions. The electronic structures of anions UOx- (x = 6-8) were investigated using density functional theory (DFT).

Asymmetric {Dy4} metallogrid and double-layered {Dy8} cage clusters from carboxylic decorated o-vanillin Schiff bases: syntheses, topological variation, and single molecule magnet behaviors

Two carboxylic decorated o-vanillin Schiff base ligands, which only differ in the positions of Cl-substituents, have realized the construction of an asymmetric {Dy4} metallogrid and a double-layered {Dy8} cage SMMs, respectively.