Tetranuclear Cluster Research Articles

A d10-Cd Cluster Containing Sandwich-Type Arsenotungstate Exhibiting Fluorescent Recognition of Carcinogenic Dye in Methanol

A d10-Cd cluster containing sandwich-type arsenotungstate [C3H12N2]6[Cd4Cl2(B-α-AsW9O34)2] was synthesized and its structure characterized through elemental analyses, X-ray powder diffraction (XRPD), IR spectroscopy, X-ray photoelectron spectroscopy (XPS), and single-crystal X-ray diffraction. The X-ray analysis revealed that the molecular unit of the compound consists of a captivating tetra-Cd-substituted sandwich-type polyoxoanion, accompanied by six elegantly protonated 1,2-diaminopropane as counter ions. The further novelty of the tetranuclear cadmium cluster lies in its occupied chlorine atom sites. This makes it highly susceptible to coordinate reactions with nitrogen on polycyclic aromatic hydrocarbons, thereby exhibiting different fluorescent signals that facilitate the identification and detection of these carcinogenic substances in methanol.

Diamidocarbene-derived palladium and nickel-sulfur clusters.

Novel palladium and nickel-sulfur clusters were synthesized using a diamidocarbene-derived carbon disulfide ligand. Structural characterization revealed a tetranuclear metal-sulfur cluster geometry with each metal center exhibiting square-planar coordination. The ligand was redox-active, accommodating oxidation states ranging from 0 to -2.

The structure of tetranuclear zirconium pivalate ZR<sub>4</sub>O<sub>2</sub> [(CH<sub>3</sub>)<sub>3</sub>CCO<sub>2</sub>]<sub>12</sub> according to X-ray diffraction analysis and quantum chemical calculations

The crystal and molecular structure of a polynuclear pivalate complex obtained by the interaction of ZrCl4 with pivalic acid was determined by X-ray diffraction analysis. The compound C71H124O28Zr4 (compound 1) crystallizes in the monoclinic crystal system. The crystal structure was refined in the nonstandard space group I2. The asymmetric part of the structure includes three Zr atoms, six pivalate ligands, a bridging µ3-O oxygen atom, as well as disordered crystallization molecules of pivalic acid with an occupancy of 50% and benzene with an occupancy of 50%. The zirconium complex molecule is a tetranuclear cluster that contains three types of Zr atoms that differ in ligand environment. Comparison of the results of quantum chemical calculations of the model reaction ZrCl4 with acetic acid with the literature data on reactions of ZrCl4 with aliphatic acids have shown the possibility of the formation of both mononuclear Zr(RCO2)4 and polynuclear clusters in this reaction, which is a new route for obtaining polynuclear zirconium clusters. The structure of the clusters formed depends on the steric properties of carboxylate ligands.

A Magnesium Organic Framework Fluorescent Sensor for Selective Detection of Nitrofuran Antibiotics and Inorganic Pollutants

ABSTRACTA novel 3D magnesium‐based metal organic framework (Mg‐MOF) has been solvothermally synthesized using 5‐(pyridin‐4‐yl)isophthalic acid. The ligand has demonstrated to preserve two types of coordination modes depending on the connection mode of the pyridine group. The uncoordinated pyridine groups provide Lewis base sites (LBSs), whereas the coordinated ones promote to form a rarely reported eight‐connected tetranuclear Mg clusters. Benefiting from the multinuclearity with high number of connections, the framework keeps good performance of high thermal stability until 500°C. Furthermore, the framework exhibits potential open metal sites (OMSs) benefiting from the terminal coordinated water groups of the metal clusters. Owing to the abundant active sites, the Mg‐MOF exhibits good sensitivity to nitrofuran antibiotics and Cr2O72−, with high KSV (at 104 M−1 level) and low limit of detection (LOD) values (∼10−6 M). Density functional theory (DFT) investigation reveals that the interchange of the HOMO–LUMO energy levels of the framework and antibiotics is responsible for the sensing activity. In addition, the Mg‐MOF is greatly recyclable in five cycles while maintaining the structural rigidity and sensing activity, making it a promising luminescence probe material.

A New Structural Motif in Aggregation of Methylalumoxanes: Non-Hydrolytic Route by the Alkylation of Dicarboxylic Acids.

Alumoxanes are typically produced via controlled hydrolysis of short-chain alkyl aluminium compounds which leads to oligomeric species that are usually difficult to obtain in crystalline form. Simultaneously, various alternative non-hydrolytic approaches to alumoxanes have also been used. In this work, we report on a new methylalumoxane scaffold derived from the alkylation of a series of dicarboxylic acids: itaconic acid (HO2CCH2C(=CH2)CO2H), succinic acid (HO2CCH2CH2CO2H) and homophthalic acid (HO2CCH2C6H4CO2H). The reactions of AlMe3 with a selected dicarboxylic acid in the molar ratio 4 : 1 conducted at elevated temperature occur with double methylation of each carboxylic group and provide to the formation of a new methylalumoxane aggregate, Me10Al6O4, flanked by methylaluminium diolate units. We also aimed to obtain dialkylaluminium derivatives of dicarboxylic acids by the controlled reaction of the appropriate acid with AlMe3 in the 1 : 2 stoichiometry. While the synthesis of organoaluminium derivatives of flexible aliphatic dicarboxylic acids (itaconic and succinic acids) is challenging due to their insolubility, the related homophtalate compound readily forms a molecular tetranuclear cluster, [([(O2CCH2C6H4CO2)(μ-AlMe2)2]2. The molecular and crystal structures of the resulting compounds were determined via NMR spectroscopic analysis and single crystal X-ray diffraction crystallography.

Electrocatalytic micro-environment regulation of ZIF-67 with broadened pore structure and unsaturated coordination sites for oxygen evolution reaction

The atomically precise mental nanoclusters have been widely explored in catalysis. However, the easy aggregation of clusters limits their application. The porous structure of metal-organic framework can prevent the aggregation and growth of clusters. In this work, a copper-phosphine complex: Cu2(dppm)2(PF6)2 (Cu2) was synthesized by one-pot method and then reacted with hydrogen sulfide to obtain a tetranuclear copper cluster: Cu4(S)(dppm)4(PF6)2 (Cu4). The two copper clusters were successfully introduced into Zeolitic imidazole frameworks-67 (ZIF-67) to form Cu2-ZIF-67 and Cu4-ZIF-67. It found that after the introduction of Cu cluster, the pore size of ZIF-67 was increased leading to more exposed Co2+ and more unsaturated coordination mental sites, which is beneficial for electrochemical oxygen evolution reaction (OER). The OER ability of pure ZIF-67 was enhanced after the introduction of Cu2 and Cu4 clusters, in which Cu4-ZIF-67 displayed the best electrochemical performance. At 10 mA cm−2, it requires an overpotential of 340 mV. The lower Tafel slope and smaller charge transfer resistance reflect its faster dynamic process. This work provides a new idea for the development of OER electrocatalysts.

Anion‐Modulated Construction of Two Novel Tetra‐ and Hepta‐Nuclear Ni(II) Salamo‐Type Clusters: Comparison of the DFT Calculations and Weak Interaction Analyses

ABSTRACTTwo novel tetra‐ and hepta‐nuclear Ni(II) salamo‐type clusters, [Ni4(L)2(μ2‐Cl)2(μ3‐OH)2(EtOH)2]⋅4CH2Cl2 (1) and [Ni7(L)3(μ3‐OEt)2(μ3‐OH)6(EtOH)2] (2), were constructed by modulating different anions (Cl− and NO3−). X‐ray crystallographic researches revealed that cluster 1 is a tetranuclear cluster consisting of a symmetric binuclear structure in which chloride ions are involved in coordination. Although cluster 2 consists of seven Ni(II) ions, three deprotonated (L)2− parts, two μ3‐ethoxy groups, six μ3‐OH− anions, and two coordinated ethanol molecules, in which it is quite rare for a large number of water molecules to be deprotonated to participate in the bridging of the cluster due to the alkaline environment. TEM electron scanning displayed the distinct shapes. Comparison of DFT calculations revealed that cluster 2 is less chemically reactive and more kinetically stable, which is in accordance with the analytical results of weak interactions, where the stronger weak interaction forces were presented, the more stable the molecule is. Finally, a comparative analysis of UV–Vis, IR, and fluorescence spectra were carried out.

Defect-engineered indium-organic framework displays the higher CO2 adsorption and more excellent catalytic performance on the cycloaddition of CO2 with epoxides under mild conditions.

In order to achieve the high adsorption and catalytic performance of CO2, the direct self-assembly of robust defect-engineered MOFs is a scarcely reported and challenging proposition. Herein, a highly robust nanoporous indium(III)-organic framework of {[In2(CPPDA)(H2O)3](NO3)·2DMF·3H2O}n (NUC-107) consisting of two kinds of inorganic units of chain-shaped [In(COO)2(H2O)]n and watery binuclear [In2(COO)4(H2O)8] was generated by regulating the growth environment. It is worth mentioning that [In2(COO)4(H2O)8] is very rare in terms of its richer associated water molecules, implying that defect-enriched metal ions in the activated host framework can serve as strong Lewis acid. Compared to reported skeleton of [In4(CPPDA)2(μ3-OH)2(DMF)(H2O)2]n (NUC-66) with tetranuclear clusters of [In4(μ3-OH)2(COO)10(DMF)(H2O)2] as nodes, the void volume of NUC-107 (50.7%) is slightly lower than the one of NUC-66 (52.8%). However, each In3+ ion in NUC-107 has an average of 1.5 coordinated small molecules (H2O), which far exceeds the average of 0.75 in NUC-66 (H2O and DMF). After thermal activation, NUC-107a characterizes the merits of unsaturated In3+ sites, free pyridine moieties, solvent-free nanochannels (10.2 × 15.7 Å2). Adsorption tests prove that the host framework of NUC-107a has a higher CO2 adsorption (113.2 cm3/g at 273K and 64.8 cm3/g at 298K) than NUC-66 (91.2 cm3/g at 273K and 53.0 cm3/g at 298K). Catalytic experiments confirmed that activated NUC-107a with the aid of n-Bu4NBr was capable of efficiently catalyzing the cycloaddition of CO2 with epoxides into corresponding cyclic carbonates under the mild conditions. Under the similar conditions of 0.10mol% MOFs, 0.5mol% n-Bu4NBr, 0.5 MP CO2, 60°C and 3h, compared with NUC-66a, the conversion of SO to SC catalyzed by NUC-107a increased by 21%. Hence, this work offers a valuable perspective that the in situ creation of robust defect-engineered MOFs can be realized by regulating the growth environment.

Additive-Assisted Forming High-Quality Thin Films of Sn-Oxo Cluster for Nanopatterning.

Recently, metal-oxo clusters (MOCs) have attracted significant interest in fabricating nanoscale patterns in semiconductors via lithography. However, many MOCs are highly crystalline, making it difficult for them to form films and hindering subsequent nanopatterning processes. In this study, we developed a novel and simple method to enhance the film-forming ability of aromatic tetranuclear Sn-oxo clusters by adding additives. Theoretical calculations and Fourier-transform infrared (FTIR) analysis revealed the formation of intermolecular hydrogen bonds between the Sn-oxo clusters and additives, which induced a crystal-gel phase transition at -20 °C, thereby inhibiting the easy crystallization of the Sn-oxo clusters. High-quality and uniform thin films with surface roughness below 0.3 nm were prepared via spin coating. The obtained thin films exhibited good lithographic performance under deep ultraviolet (DUV), electron beam, and extreme-ultraviolet irradiation without a photo acid generator/photoinitiator, and 13- and 21 nm-wide line patterns were obtained on the films via electron-beam and extreme-ultraviolet lithographies. This study will pave the way for the further investigation of novel MOCs for advanced lithography and other thin-film applications.

A Propeller-Like Ligand-Directed Construction of a Tetranuclear Cerium-Organic Framework for Single-Step Ethylene Purification from Ternary C2 Mixtures.

The efficient single-step purification of ethylene from ternary C2 mixtures containing ethane and acetylene is challenging and demanding. Herein, we introduce a novel cerium-based metal-organic framework (MOF) of Ce-NTB-rtk synthesized via a ligand-conformer strategy. The Ce-NTB-rtk features a rare tetranuclear cerium cluster and 2D kgd layers pillared by a 3D rtl framework concomitant with an extraordinary (3,3,12)-c network. The compound encompasses microporous cavities replete with a nonpolar microenvironment. Gas sorption and breakthrough experiments demonstrate its superior affinity for C2H6 and C2H2 over C2H4, enabling effective single-step ethylene purification. Computational simulations reveal that preferential adsorptions are facilitated by different interaction strengths of C-H···O hydrogen bonds. The performance of Ce-NTB-rtk in separation selectivity and regeneration capacity makes it a promising candidate for sustainable and cost-effective ethylene purification, showcasing the potential of MOFs in advanced gas separation applications.

Syntheses and properties of seven 3,4-dichlorobenzoate-based zinc-rare earth heterometallic complexes containing a field-induced Zn(II)-Dy(III)-Dy(III)-Zn(II) single-molecule magnet

Under solvothermal conditions of CH3CH2OH and H2O, a series of 3d-4f heterometallic complexes [Ln2Zn2(3,4-DCB)10(2,2′-bpy)2] [Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5), Er (6) and Yb (7), 3,4-DCB = 3,4-dichlorobenzoic acid, 2,2′-bpy = 2,2′-bipyridine] were synthesized by the reactions of Ln(NO3)3·6H2O, Zn(NO3)2·6H2O, 3,4-HDCB, 2,2′-bpy and NaOH. These complexes were characterized by single crystal X-ray diffraction, powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA) and differential thermo analysis (DTA). Complexes 1–7 show two types of different zero-dimensional (0D) structures although they have the same molecular formula. Complexes 1–5 are isomorphic, and complexes 6 and 7 are isomorphic. In 1–7, linear tetranuclear clusters are formed from 3,4-DCB connecting Ln(III) and Zn(II). They can be expanded into one-dimensional (1D) supramolecular chains or two-dimensional (2D) supramolecular layers by the intermolecular π–π interactions. The photoluminescent properties of 1, 2, 4 and 5 and the magnetic properties of 3–7 were studied in detail. Complex 5 exhibits an obvious field-induced single-molecule magnet behavior with a Ueff value of approximately 24 K.

Planar Tetranuclear Uranium Hydride Cluster Supported by ansa‐Bis(cyclopentadienyl) Ligands

AbstractPolynuclear metal hydride clusters play important roles in various catalytic processes, with most of the reported polynuclear metal hydride clusters adopting a polyhedral three‐dimensional structure. Herein, we report the first example of a planar tetranuclear uranium hydride cluster [(CpCMe2CMe2Cp)U]4(μ2‐H)4(μ3‐H)4 (U4H8). It was synthesized by reacting an ansa‐bis(cyclopentadienyl) ligand‐supported uranium chloride precursor [(CpCMe2CMe2Cp)U]3(μ2‐Cl)3(μ3‐Cl)2 with NaHBEt3. The presence of hydrides in U4H8 was confirmed by NMR spectroscopy and its reactivity with phenol and carbon tetrachloride. DFT calculations also facilitated the determination of the hydrides’ positions in U4H8, featuring four bridging μ2‐H ligands and four face‐capping μ3‐H ligands, with the four U centers arranged in a rhombic geometry. The U4H8 represents not only the first example of planar polynuclear actinide metal hydride cluster but also the uranium hydride cluster with the highest nuclearity reported to date.

Planar Tetranuclear Uranium Hydride Cluster Supported by ansa-Bis(cyclopentadienyl) Ligands.

Polynuclear metal hydride clusters play important roles in various catalytic processes, with most of the reported polynuclear metal hydride clusters adopting a polyhedral three-dimensional structure. Herein, we report the first example of a planar tetranuclear uranium hydride cluster [(CpCMe2CMe2Cp)U]4(μ2-H)4(μ3-H)4 (U4H8). It was synthesized by reacting an ansa-bis(cyclopentadienyl) ligand-supported uranium chloride precursor [(CpCMe2CMe2Cp)U]3(μ2-Cl)3(μ3-Cl)2 with NaHBEt3. The presence of hydrides in U4H8 was confirmed by NMR spectroscopy and its reactivity with phenol and carbon tetrachloride. DFT calculations also facilitated the determination of the hydrides' positions in U4H8, featuring four bridging μ2-H ligands and four face-capping μ3-H ligands, with the four U centers arranged in a rhombic geometry. The U4H8 represents not only the first example of planar polynuclear actinide metal hydride cluster but also the uranium hydride cluster with the highest nuclearity reported to date.

Adjusting organic ligands to construct four 3D metal-organic frameworks with Co2N2O8 SBUs as efficient bifunctional electrocatalysts for OER and HER

Multidentate ligands can be used to construct structurally adjustable metal-organic framework materials due to their abundant coordination sites. MOFs 1 − 4 with different configurations are synthesized by solvothermal method based on the symmetrical tetracarboxylic acid H4L main ligand (H4L = 5′-(4-carboxyphenyl)-[1,1′:2′,1′'-terphenyl]-4,4′,4′'-tricarboxylic), named [Co2(L)(bimb)]n (MOF 1, bimb=(1,1′-(1,4-butanediyl) bis (imidazole)), [Co2(L)(bix)]n, (MOF 2, bix=1,4-bis(imidazol-1-ylmethyl) benzene), [Co4(L)2(bidpe)2]n (MOF 3, bidpe=4,4′-bis(imidazolyl)diphenyl ether) and {[Co4(L)(bibdp)2(C3H7NO)]·2(C3H7NO)}n (MOF 4, bibdp=4,4′-bis(1-imidazolyl) biphenyl), respectively. The rich coordination sites of H4L carboxylic acid ligands bring diverse coordination modes, forming Co2N2O8 secondary construction units. Based on it, MOFs 1 − 4 exhibits pillar-layered 3D porous supramolecular structure. Electrochemical measurements support that MOFs 1 − 4 exhibits excellent OER (oxygen evolution reaction) and HER (hydrogen evolution reaction) activities, especially MOF 3, which only requires overpotentials of 180 and 196 mV to reach the current density of 10 mA·cm−2. Remarkable catalytic performance of MOF 3 is attributed to the abundant and dispersed reactive active sites brought by the 3D interpenetrated structure assembled based on tetranuclear metal clusters. The HER occurs through Volmer-Heyrovsky mechanism, meanwhile, possible mechanisms of OER have been predicted. This investigation provides inspiration for exploring multi-core structured MOF materials as efficient HER/OER bifunctional catalysts for electrolytic overall water splitting.

Development of Heterometallic Annular Tetranuclear Clusters in Metal–Organic Frameworks for Methane Purification and Storage

Development of Heterometallic Annular Tetranuclear Clusters in Metal–Organic Frameworks for Methane Purification and Storage

Isoreticular Contraction of Cage-like Metal-Organic Frameworks with Optimized Pore Space for Enhanced C2H2/CO2 and C2H2/C2H4 Separations.

The C2H2 separation from CO2 and C2H4 is of great importance yet highly challenging in the petrochemical industry, owing to their similar physical and chemical properties. Herein, the pore nanospace engineering of cage-like mixed-ligand MFOF-1 has been accomplished via contracting the size of the pyridine- and carboxylic acid-functionalized linkers and introducing a fluoride- and sulfate-bridging cobalt cluster, based on a reticular chemistry strategy. Compared with the prototypical MFOF-1, the constructed FJUT-1 with the same topology presents significantly improved C2H2 adsorption capacity, and selective C2H2 separation performance due to the reduced cage cavity size, functionalized pore surface, and appropriate pore volume. The introduction of fluoride- and sulfate-bridging cubane-type tetranuclear cobalt clusters bestows FJUT-1 with exceptional chemical stability under harsh conditions while providing multiple potential C2H2 binding sites, thus rendering the adequate ability for practical C2H2 separation application as confirmed by the dynamic breakthrough experiments under dry and humid conditions. Additionally, the distinct binding mechanism is suggested by theoretical calculations in which the multiple supramolecular interactions involving C-H···O, C-H···F, and other van der Waals forces play a critical role in the selective C2H2 separation.

Pyridine and bipyridine complexes of tri- and tetranuclear ruthenium clusters revisited. Substitution, orthometallation and bridges between cluster units

The reactions of pyridine and 2-, 3- and 4-picoline with [H4Ru4(CO)12] were carried out under several experimental conditions and produced mono- and disubstituted products as well as complexes where Ru-Ru cleavage occurred, and orthometalation of the heterocycle took place. The disubstituted compound [(μ-H)4Ru4(CO)10(py)2] shows that both pyridine rings are coordinated to the same ruthenium atom; the 4-picoline also forms a similar complex. The reaction of [Ru3(CO)12] with 4,4´-bipyridine was also carried out. The product formed shows a bridged structure with both pyridine rings coordinated to a ruthenium triangle in an ortho-metalated mode. Spectroscopic characterization of all new compounds is described and the X-ray crystal structures of [(μ-H)4Ru4(CO)11py], [(μ-H)4Ru4(CO)10(py)2], [(μ-H)2Ru3(CO)8((μ-η2-NC5H4)2] and [{Ru3(CO)10}2(μ-η2–4,4´-(NC5H3)2] are described.

Synthesis, crystal structure, and gas sorption studies of two neutral octahedral {MII24}-cages built from sulfonylthiacalix[4]arene tetranuclear clusters and triazine linkers

Synthesis, crystal structure, and gas sorption studies of two neutral octahedral {MII24}-cages built from sulfonylthiacalix[4]arene tetranuclear clusters and triazine linkers

Synthesis, structure, photoluminescence and magnetism of a series of cobalt‐lanthanide heterometallic complexes originated from 2,3‐dichlorobenzoate and 1,10‐phenanthroline

AbstractA series of 3d–4f heterometallic complexes, namely [Ln2Co2(2,3‐DCB)10(phen)2] [Ln=Nd (1), Sm (2), Eu (3), Gd (4), Tb (5), Dy (6), Er (7)], were obtained through the self‐assembly reactions of Ln(NO3)3 ⋅ nH2O, Co(NO3)2 ⋅ 6H2O, 2,3‐dichlorobenzoic acid (2,3‐HDCB), NaOH and 1,10‐phenanthroline (phen) under solvothermal conditions. Their crystal structures were determined by single‐crystal X‐ray diffraction. They were also characterized by elemental analysis, FT‐IR, powder X‐ray diffraction (PXRD) and thermogravimetric analysis (TGA) and differential thermoanalysis (DTA). These seven complexes have the same molecular formula but different crystal structures. Complexes 1–3, 4 and 5 as well as 6 and 7 are crystallographically isomorphous, respectively. They all exhibit zero‐dimensional (0D) linear tetranuclear cluster structures. These 0D linear tetranuclear clusters can be further connected into a two‐dimensional (2D) supramolecular network via the extensive intermolecular π–π interactions between 2,3‐DCB and phen. The photoluminescent properties of 3, 5 and 6 and the magnetic properties of 1–2 and 4–7 were investigated. Complex 6 shows a slow magnetic relaxation behavior.

SYNTHESIS AND FEATURES OF THE MOLECULAR AND CRYSTAL STRUCTURE OF THE Cp4Ru4(µ3-CO)4 CLUSTER

When preparing the ruthenium dimer [Ru(CO)2Cp]2 in the thermal reaction of cyclopentadiene with Ru3(CO)12, the tetranuclear cluster [Ru(μ3-CO)Cp]4 (I) was obtained as a minor product. Spectral (13C and 1H NMR, IR) and structural studies were carried out for cluster I. By crystallization under different conditions, two types of dark cherry crystals were obtained, cluster I itself (crystal 1) and its tetrahydrate (crystal 2), the structure of which was determined by X-ray diffraction. Structural data for 1 and 2 have been deposited in the Cambridge Structural Data Center (CCDC nos. 2241197 and 2241199, respectively; deposit@ccdc.cam.ac.uk; http://www.ccdc.cam.ac.uk). Based on a comparative analysis of cluster geometry, it is shown that the distortion of the Ru4(CO)4 framework in I from ideal Td symmetry in the structure of a pure compound is determined by the anisotropy of intermolecular contacts in the crystal. Features of chemical bonding in the [Ru(μ3-CO)Cp]4 cluster and its iron-containing analogue were studied using DFT calculations using topological analysis of electron density to compare energy characteristics and effective force constant bonding interactions. The necessity of using criteria for elastic deformations of interatomic interactions (force constants) for the correct description of structural and chemical phenomena, for example, such as the structural non-rigidity of the framework of transition metal clusters, has been demonstrated.