Cage-like Clusters Research Articles

Non-Covalent and Covalent Binding of New Mixed-Valence Cage-like Polyoxidovanadate Clusters to Lysozyme.

The high-resolution X-ray structures of the model protein lysozyme in the presence of the potential drug [VIVO(acetylacetonato)2] from crystals grown in 1.1 M NaCl, 0.1 M sodium acetate at pH 4.0 reveal the binding to the protein of different and unexpected mixed-valence cage-like polyoxidovanadates (POVs): [V15O36(OH2)]5-, which non-covalently interacts with the lysozyme surface, [V15O33(OH2)]+ and [V20O51(OH2)]n- (this latter based on an unusual {V18O43} cage) which covalently bind the protein. EPR spectroscopy confirms the partial oxidation of VIV to VV and the formation of mixed-valence species. The results indicate that the interaction with proteins can stabilize the structure of unexpected - both for dimension and architecture - POVs, not observed in aqueous solution.

Two new 3-D vanadoborates incorporating rare polymeric K-O-K chain or network with photocatalytic properties

The discovery of novel high-dimensional vanadorates with important photocatalytic properties is of great importance in structural chemistry and materials science. Herein, new types of three-dimensional (3-D) vanadoborates (H3O)2{[K6(H2O)10][Ni(H2O)4][V12B18O54(OH)6]}·13H2O (1) and (H3O)2{[K12(H2O)10][Zn4(B2O4H2)(B4O14H10)(V10B28O74H8)]}·2H2O (2) were synthesized by a facile and feasible hydrothermal technique and structurally characterized. 1 comprises cage-like vanadoborate cluster [V12B18O54(OH)6]10- based on the combination of one puckered [B18O36(OH)6] ring and two hexa-meric oxo-vanadate [V6O9] units, while 2 contains a rare vanadoborate cluster {[Zn4(B2O4H2)(B4O14H10)(V10B28O74H8)]}14- built up from two [B14O28(OH)4] rings, one [Zn4(B2O4H2)(B4O14H10)] unit and one ellipse-like [V10O30] ring. The 3-D framework of 1 is constructed by the linkage of rare [K6(H2O)10]n chains and {[Ni(H2O)4][V12B18O54(OH)6]}n chains, while 3-D architecture of 2 is built from the interconnection of infrequent [K12(H2O)10]n layers and vanadoborate {[Zn4(B2O4H2)(B4O14H10)- (V10B28O74H8)]}14- clusters. The documented polymeric vanadoborates are usually based on low nuclearity metal complexes as bridging groups, however, 1 and 2 present new types of the 3-D vanadoborates based on K-O-K polymeric chain or layer as bridging group. The photocatalytic results revealed 1 and 2 displayed the efficient photo-catalytic properties for degradation of methylene blue under visible light. This study offers a facile synthetic method for the preparation of new high-dimensional vanadorates as the potential photo-catalysts to eliminate the harmful methylene blue dyes in industrial wastewaters.

K2(Bi@Pd12@Bi20)]4-: An Endohedral Inorganic Fullerene with Spherical Aromaticity.

Inorganic fullerene clusters have attracted widespread attention due to their highly symmetrical geometric structures and intrinsic electronic properties. However, cage-like clusters composed of heavy metal elements with high symmetry are rarely reported, and their synthesis is also highly challenging. In this study, we present the synthesis of a [K2(Bi@Pd12@Bi20)]4- cluster that incorporates a {Bi20} cage with pseudo-Ih symmetry, making it the largest main group metal cluster compound composed of the bismuth element to date. Magnetic characterization and theoretical calculations suggest that the spin state of the overall cluster is a quartet. Quantum chemical calculations reveal that the [Bi20]3- cluster has a similar electronic configuration to C606- and the [Bi@Pd12@Bi20]6- cluster exhibits a unique open-shell aromatic character.

A Luminescent Sensing Experiment of Cage-like Europium-Germanate Oxo Cluster for Advanced Undergraduate Students

A Luminescent Sensing Experiment of Cage-like Europium-Germanate Oxo Cluster for Advanced Undergraduate Students

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.

Predicting Binding Energies and Electronic Properties of Boron Nitride Fullerenes Using a Graph Convolutional Network.

As isoelectronic counterparts of carbon fullerenes, medium-sized boron nitride clusters also prefer cage structures composed of even-sized polygons. As the cluster size increases, the number of cage isomers grows rapidly, and determining the ground state structure requires a tremendous amount of DFT calculations. Herein, we develop a graph convolutional network (GCN) that can describe the energy of a (BN)n cage by its topology connection. We define a vertex feature vector on a dual polyhedron by the permutation of the neighbor vertices' degree and aggregate the information on vertices by two graph convolutional layers to learn the local feature of the dual polyhedron. The GCN is trained on (BN)28 and subsequently tested on (BN)23 and (BN)24 data sets, which satisfactorily reproduce the order of isomer energies from DFT calculations. We further employ the trained GCN to predict the ground state structures within the size range of n = 25-32, which agree well with DFT results. Using the same GCN framework, we also successfully trained the highest-occupied or lowest-unoccupied orbital energies of (BN)28 isomers. The present graph convolutional network establishes a direct mapping between the topological connection and the energetic or electronic properties of a cage-like cluster or molecule.

Exploration and Insights on Topology Adjustment of Giant Heterometallic Cages Featuring Inorganic Skeletons Assisted by Machine Learning.

Inorganic molecular cages are emerging multifunctional molecular-based platforms with the unique merits of rigid skeletons and inherited properties from constituent metal ions. However, the sensitive coordination bonds and vast synthetic space have limited their systematic exploration. Herein, two giant cage-like clusters featuring the organic ligand-directed inorganic skeletons of Ni4[La74Ni104(IDA)96(OH)184(C2O4)12(H2O)76]·(NO3)38·(H2O)120 (La74Ni104, 5 × 5 × 3 - C2O4) and [La84Ni132(IDA)108(OH)168(C2O4)24(NO3)12(H2O)116]·(NO3)72·(H2O)296 (La84Ni132, 5 × 5 × 5 - C2O4) were discovered by a high-throughput synthetic search. With the assistance of machine learning analysis of the experimental data, phase diagrams of the two clusters in a four-parameter synthetic space were depicted. The effect of alkali, oxalate, and other parameters on the formation of clusters and the mechanism regulating the size of two n × m × l clusters were elucidated. This work uses high-throughput synthesis and machine learning methods to improve the efficiency of 3d-4f cluster discovery and finds the highest-nuclearity 3d-4f cluster to date by regulating the size of the n × m × l inorganic cages through oxalate ions, which pushes the synthetic methodology study on elusive inorganic giant cages in a significantly systematic way.

First-Principles Study of B16N16 Cluster-Assembled Porous Nanomaterials.

Owing to the similar valence electron structures between the B-N bond and the C-C bond, boron nitride, similar to carbon, can form abundant polymorphs with different frameworks, which possess rich mechanical and electronic properties. Using the hollow, cage-like B16N16 cluster as building blocks, here, we established three new BN polymorphs with low-density porous structures, termed Cub-B16N16, Tet-B16N16, and Ort-B16N16, which have cubic (P4¯3m), tetragonal (P4/nbm), and orthomorphic (Imma) symmetries, respectively. Our density functional theory (DFT) calculations indicated that the existence of porous structure Cub-B16N16, Tet-B16N16, and Ort-B16N16 were not only energetically, dynamically, thermally and mechanically stable, they were even more stable than some known phases, such as sc-B12N12 and Hp-BN. The obtained Pugh's ratio showed that the Cub-B16N16 and Tet-B16N16 structures were brittle materials, but Ort-B16N16 was ductile. The analysis of ideal strength, Young's moduli, and shear moduli revealed that the proposed new phases all exhibited sizable mechanical anisotropy. Additionally, the calculation of electronic band structures and density of states showed that they were all semiconducting with a wide, indirect band gap (~3 eV). The results obtained in this work not only identified three stable BN polymorphs, they also highlighted a bottom-up way to obtain the desired materials with the clusters serving as building blocks.

Possible boron-rich amorphous silicon borides from ab initio simulations

By means of ab initio molecular dynamics simulations, possible boron-rich amorphous silicon borides (BnSi1-n, 0.5 ≤ n ≤ 0.95) are generated and their microstructure, electrical properties andmechanical characters are scrutinized in details.As expected, the mean coordination number of each species increases progressively and more closed packed structures form with increasing B concentration.In all amorphous models, pentagonal pyramid-like configurations are observed and some of which lead to the development of B12 and B11Si icosahedrons.It should be noted that the B11Si icosahedron does not form in any crystalline silicon borides. Due to the affinity of B atoms to form cage-like clusters, phase separations (Si:B) are perceived in the most models.All simulated amorphous configurations are a semiconducting material on the basis of GGA+U calculations.The bulk modulus of the computer-generated amorphous compounds is in the range of 90GPa to 182 GPa.As predictable, the Vickers hardness increases with increasing B content and reaches values of 25-33 GPa at95% B concentration.Due to their electrical and mechanical properties, these materials might offer some practicalapplications in semiconductor technologies. The density functional theory (DFT) based abinitio molecular dynamics (AIMD) simulations were used to generate B-rich amorphous configurations.

Perfect Core-Shell Octahedral B@B38 + , Be@B38 , and Zn@B38 with an Octa-Coordinate Center as Superatoms Following the Octet Rule.

Planar, tubular, cage-like, and bilayer boron clusters Bn +/0/- (n=3∼48) have been observed in joint experimental and theoretical investigations in the past two decades. Based on extensive global searches augmented with first-principles theory calculations, we predict herein the smallest perfect core-shell octahedral borospherene Oh B@B38 + (1) and its endohedral metallo-borospherene analogs Oh Be@B38 (2), and Oh Zn@B38 (3) which, with an octa-coordinate B, Be or Zn atom located exactly at the center, turn out to be the well-defined global minima of the systems highly stable both thermodynamically and dynamically. B@B38 + (1) represents the first boron-containing molecule reported to date which contains an octa-coordinate B center covalently coordinated by eight face-capping boron atoms at the corners of a perfect cube in the first coordination sphere. Detailed natural bonding orbital (NBO) and adaptive natural density partitioning (AdNDP) bonding analyses indicate that these high-symmetry core-shell complexes X@B38 +/0/- (X=B, Be, Zn) as super-noble gas atoms follow the octet rule in coordination bonding patterns (1S2 1P6 ), with one delocalized 9c-2e S-type coordination bond and three delocalized 39c-2e P-type coordination bonds formed between the octa-coordinate X center and its octahedral Oh B38 ligand to effectively stabilize the systems. Their IR, Raman, and UV-Vis spectra are computationally simulated to facilitate their spectroscopic characterizations.

Tunnel barrier to spin filter: Electronic-transport characteristics of transition metal atom encapsulated in a small Cadmium Telluride cage.

First-principles theory-based comparative electronic-transport studies were performed for an atomic chain of Au, a bare Cd9Te9 cage-like cluster, and a single transition metal (TM) (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd) atom encapsulated within the Cd9Te9 using Au(111) as the electrodes. The bare cluster was semiconducting and acted as a tunnel barrier up to a particular applied bias and then beyond that the device displayed a linear current-voltage relationship. Several TMs (Ti, V, Cr, Mn, Fe) encapsulated in the cage showed a half-metallic behavior and spin-filtering effect in the I-V characteristics of the device. Detailed qualitative and quantitative analyses of the I-V characteristics for metallic, semiconducting, and half-metallic nanostructures were carried out for quantifying the use of these TMs in spintronic device applications.

Inside Cover: Anion‐Guided Stepwise Assembly of High‐Nuclearity Lanthanide Hydroxide Clusters (Angew. Chem. Int. Ed. 33/2022)

The rational synthesis of high-nuclearity lanthanide cluster remains challenging. In their Research Article (DOI: 10.1002/anie.202205385), Min Feng, Zhiping Zheng et al. developed a stepwise synthesis of a high-nuclearity sodalite cage-like cluster Er60, guided by judiciously selected anions. The successive introduction of I−, CO32−, and NO3− led to the isolation of three crucial intermediate clusters, namely the wheel-like Er12, ship-like Er34, and bowl-like Er48. The findings opened the “black box” of the elusive self-assembly process and provided mechanistic insights.

Water clusters and density fluctuations in liquid water based on extended hierarchical clustering methods

The microscopic structures of liquid water at ambient temperatures remain a hot debate, which relates with structural and density fluctuations in the hydrogen bond network. Here, we use molecular dynamics simulations of liquid water to study the properties of three-dimensional cage-like water clusters, which we investigate using extended graph-based hierarchical clustering methods. The water clusters can cover over 95% of hydrogen bond network, among which some clusters maximally encompass thousands of molecules extending beyond 3.0 nm. The clusters imply fractal behaviors forming percolating networks and the morphologies of small and large clusters show different scaling rules. The local favored clusters and the preferred connections between adjacent clusters correspond to lower energy and conformational entropy depending on cluster topologies. Temperature can destroy large clusters into small ones. We show further that the interior of clusters favors high-density patches. The water molecules in the small clusters, inside which are the void regarded as hydrophobic objects, have a preference for being more tetrahedral. Our results highlight the properties and changes of water clusters as the fundamental building blocks of hydrogen bond networks. In addition, the water clusters can elucidate structural and density fluctuations on different length scales in liquid water.

Lanthanide‒containing titanium-oxo clusters with high aqueous stability for photocatalytic application

Increasing the structural stability towards aqueous conditions is a great challenge for titanium-oxo clusters (TOCs). In this study, two lanthanide-containing titanium-oxo clusters formulated as [Er2Ti8(μ3-O)8(μ2-O)2(μ2-OH)2(BA)16] and [Yb2Ti8(μ3-O)8(μ2-O)2(μ2-OH)2(BA)16] (BA = benzoate) were synthesized, which possess ultrahigh stability in aqueous solutions with a wide pH range for at least 1 week. The structures of the clusters were characterized by single-crystal X-ray diffraction analysis. It reveals that the high structural stability of the clusters can be attributed to the cage-like cluster core that is fully coordinated by benzoate ligands. The photoelectrochemical and photocatalytic properties of the clusters were investigated. The clusters exhibit favorable performance for the photocatalytic dye degradation and photocatalytic oxidative desulfurization.

Half-metallicity in smallest cage-like cluster of CdTe with doping of transition metal atoms

We report first principles theory based electronic structure studies of a semiconducting stoichiometric cage-like Cd9Te9 cluster. Substantial changes are observed in the electronic structure of the cluster on passivation with fictitious hydrogen atoms, in particular, widening of the energy gap between highest occupied molecular orbital and lowest unoccupied molecular orbital and enhancement in stability of cluster is seen. The cluster, when substitutionally mono-doped for a Cd by a set of 3d and 4d transition metal atoms (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ru, Rh and Pd), is found to acquire polarization as seen from spin resolved density of states near Fermi level. Further, such mono-doping in passivated cluster shows half-metallic behavior. Mapping of partial density of states of each system on that of undoped cluster reveals additional levels caused by doping each TM atom separately. In the 3d elemental doping, Ti and Mn doping result into electron type doping whereas all other cases result into hole doped systems. For all the 4d elements studied, it is akin to the doping with holes for Cd substitution in the outer ring, whereas for Ru and Rh, there is electron type doping in case of substitution for Cd in central ring upon passivation. A comparison of partial density of states plots for bare and passivated clusters, on doping with transition metal atoms, suggests suitability of the cage-like cluster for spintronics applications.

Entrapping polysulfides via S, N-coordinated supermolecule towards enhanced Li-S kinetics

Currently, the urgent requirement of high-energy–density storage devices for large-grid applications has been brought to public attention. Lithium-sulfur (Li-S) batteries are one of the most recognized candidates to substitute for the state-of-the-art lithium-ion (Li-ion) batteries. To conquer the dogged polysulfide shuttling in Li-S cells, a supramolecular crystal was synthesized via the coordination of a thiol ligand with nickel to generate a unique cage-like cluster in the form of N4-Ni∙∙∙Ni-S4 as the precursor of organosulfur, in which sulfur was anchored on nitrogen sites. The organosulfur undergoes changes in both the configuration and electron distribution upon lithiation/delithiation process, which can strengthen entrapment of polysulfides, boost efficient sulfur conversion and promote the reaction kinetics of the cathodes. The Li-S cells were demonstrated a high initial discharge capacity of 1354.9 mAh g−1 at 0.2 C and a long-term lifespan of 1000 cycles at 2 C. The high-loading sulfur cathodes of 8.6 mg cm−2 is capable of delivering an areal capacity as high as 9.1 mAh cm−2. Combining with the advantages of low cost and facile synthesis, such organosulfur is of great promising perspective in further boosting the commercial realization of Li-S batteries.

Amorphous boron phosphide: An ab initio investigation

We generate a structural model of amorphous boron phosphide (BP) by quenching the melt via ab initio molecular dynamics calculations and compare it structurally and electrically with the crystal. We find that both phases of BP have a significantly different short-range order. Namely, the amorphous network presents strong chemical disorder and structural defects. P-atoms form only undercoordinated defects while B atoms present both undercoordinated and overcoordinated defects. The mean coordination number of B and P atoms is 4.17 and 3.69, correspondingly. Some of overcoordinated B atoms with chemical disorder yield the formation of pentagonal-pyramid-like motifs and a cage-like B10 cluster in the amorphous network. About 13 % volume expansion is observed by amorphization, probably due to the low-coordinated structural defects. The amorphous configuration is semiconductor as in the crystal but has a smaller energy band gap.

Origin of the structural stability of cage-like Au144 clusters.

Cage-like metal nanoclusters are rarely found due to the densely packed property of metals. Recently, single crystallography has unraveled for the first time that multi-shell golden cages are formed in large-size thiolate (SR) and alkynl (CCR) protected neutral Au144 nanoclusters, denoted as Au144(SR)60 and Au144(CCR)60. In this study, the origin of the structural stability of golden cage Au144 clusters is studied based on the density functional theory (DFT) energy calculation and energy decomposition analysis (EDA). The formation of hollow cages rather than centre-filled icosahedrons in the Au144 clusters is attributed to the significant Pauli repulsion between the central gold atom and the surrounding metal shell, which leads to the decrease of the averaged formation energy of the clusters. The present study also shows that the Au144 cluster is unique in size. The smaller size clusters Au133 and Au130 and the larger size cluster Au279 both preferred the centre-filled golden icosahedrons, decahedrons or octahedrons.

The electronic and magnetic properties of 3d VIIB and VIII atom-substituted C20 cage

To analyze the contributions of the metal atoms to stabilize and synthesize the small cage-like carbon clusters, the configurations, electronic and magnetic characteristics of Mn-, Fe-, Co- and Ni-substituted C[Formula: see text] cage have been investigated using the PBE functional. The results demonstrate that the TM (TM[Formula: see text]=[Formula: see text]Mn, Fe, Co and Ni) substitution decreases the structural stability of the C[Formula: see text] cages, while increases the activity of the C[Formula: see text] cages. Electronic migrations between the TM atoms and C atoms are less. All the TM–C bonds of the TMC[Formula: see text] and TM2C[Formula: see text] clusters display covalent bond characters. The [Formula: see text] orbitals of TM atoms lose electrons, the [Formula: see text] and [Formula: see text] orbitals of TM atoms obtain electrons. The special distributions of the HOMO states of the TMC[Formula: see text] and TM2C[Formula: see text] clusters are mainly from the hybridization of the C [Formula: see text] orbitals and the TM [Formula: see text] orbitals. The Mn2C[Formula: see text] cages display the highest spin polarization.

Hydrogen storage capability of cagelike Li3B12 clusters

The cagelike Li3B12 cluster that was predicted to possess high stability in a recent report [X. Dong et al., Angew. Chem. Int. Ed. 57, 4627 (2018)] was investigated as a candidate for hydrogen storage material within the density functional theory framework. Our computational results indicate that every Li atom in a Li3B12 cluster can at most attach six H2 molecules, resulting in the gravimetric hydrogen uptake capacity of 24.8%. The binding energies of H2 on clusters are in the range of 0.06–0.14 eV predicted with the wB97xD functional. Ab initio molecular dynamics simulations indicate that H2 molecules are substantially attached by the host cluster at low temperature (77 K) and can be efficiently released at room temperature (298 K). Moreover, the adsorption and desorption kinetics of hydrogen molecules on the cluster can be adjusted by applying the external electric field.