Rhenium Cluster Research Articles

Synthesis and Characterization of A4[Re6Q8L6]@SiO2 Red-Emitting Silica Nanoparticles Based on Re6 Metal Atom Clusters (A = Cs or K, Q = S or Se, and L = OH or CN)

Metal atom clusters constitute very promising candidates as luminophores for applications in biotechnology because they are nanosized entities offering robust luminescence in the near-infrared field (NIR). However, they cannot be used as prepared for biological applications because of potential toxic effects and quenching of the clusters' luminescence in aqueous media, and they therefore need to be dispersed in a biocompatible matrix. We describe herein the encapsulation of octahedral rhenium clusters, denoted as A(4)[Re(6)Q(8)L(6)] (A = Cs or K, Q = S or Se, and L = OH or CN), in silica nanoparticles by a water-in-oil microemulsion process, paying particular attention to the clusters' stability. The obtained A(4)[Re(6)Q(8)L(6)]@SiO(2) nanoparticles are 30 nm in size with good monodispersity and a perfectly spherical shape, as shown by scanning electron microscopy (SEM). The presence of cluster units inside the silica matrix was evidenced by scanning transmission electron microscopy in annular dark-field mode (ADF-STEM). From the point of view of their optical properties, the A(4)[Re(6)Q(8)L(6)]@SiO(2) nanoparticles show red and NIR emission under UV excitation, even when dispersed in water. The evolution of the structural and luminescence properties of clusters before and after encapsulation was followed by Raman and photoluminescence spectroscopy.

Dodecanuclear rhenium cluster complexes with an interstitial carbon atom: Synthesis, structures and properties of two new compounds K 6[Re 12CS 17(OH) 6]·4H 2O and Na 12Re 12CS 17(SO 3) 6·48.5H 2O

The dodecanuclear rhenium anionic complex with terminal hydroxo ligands [Re 12CS 17(OH) 6] 6− was obtained by the reaction of K 6[Re 12CS 17(CN) 6]·20H 2O with molten KOH at 300 °C. The cluster complex was crystallized as a potassium salt from aqueous solution. The reaction between K 6[Re 12CS 17(OH) 6]·4H 2O and Na 2S 2O 4 in water under reflux results in the formation of the complex Na 12[Re 12CS 17(SO 3) 6]·48.5H 2O. Both new compounds were characterized by single-crystal X-ray diffraction, elemental analyses and IR spectroscopy. The electronic structure of [Re 12CS 17(OH) 6] 6− was also elucidated by DFT calculations.

ChemInform Abstract: Hexanuclear Rhenium Clusters: From Solid State to Solution Chemistry. The Crystal Structure of KRe6Se5Cl7(OH)2, H2O, and Its Implications

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Coordination and Reduction of Isocyanide Ligands in Hydrido-Carbonyl Rhenium Cluster Chemistry. Synthesis and Characterization of the Anion (Re3(μ-H)4(CO)9(CNR))- and of the Formimidoyl Derivative (Re3(μ- H)3(CO)9(.mu±eta.2-C(H)=NR)(P

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Crystal Structure of (H3O)4[(C2H5)4N]6 [Th2Cl4(H2O)12O]3[Re4Se4(CN)12

Crystals of the rhenium cluster complex (H3O)4[(C2H5)4N]6[Th2Cl4(H2O)12O]3[Re4Se4(CN)12]4 are obtained in an acidic (HCl) aqueous solution by the reaction of cluster salt K4[Re4Se4(CN)12]·6H2O with ThCl4 and (C2H5)4NCl. Single crystal X-ray analysis shows that the title compound is ionic and crystallizes in the cubic crystal system (a = 22.7322(3) A, V = 11746.93(27) A3, Z = 2, I4 3m space group, R = 0.0350). It contains [Th2Cl4(H2O)12O]2+ cations with two thorium atoms bonded to each other through the bridging oxygen atom forming an angle of 180° in the structure.

ChemInform Abstract: Highly Emissive Hexanuclear Rhenium(III) Clusters Containing the Cubic Cores [Re6S8]2+ and [Re6Se8]2+.

Clusters based on the cubic, hexanuclear rhenium(III) core [Re6(μ3-Q)8]2+ (Q = S, Se) emit red phosphorescence with microsecond-scale lifetimes. Emission quantum yields of 16 clusters range from 1%...

ChemInform Abstract: Adjustment of Dimensionality in Covalent Frameworks Formed by Co2+ and Rhenium Cluster Chalcocyanide [Re6S8(CN)6]4-.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Вплив нанопрепаратів кластерних сполук ренію на активність ферментів печінки в моделі пухлинного росту

Enzymes’ level in rat’s hepatocytes under Guerin's carcinoma T8 development as well as after injection of rhenium compounds and cis-platin has been studied. It has been determined that the decrease of enzymatic activity to the level of the animals of control group was observed at the simultaneous injection of cis-platin and cluster rhenium compounds in nanoliposomal and water-soluble forms. That confirms possible hepatoprotective properties of the rhenium compounds. It has been shown that hepatoprotective properties of rhenium cluster compounds mostly don’t depend on the form of their injection and are detected regardless of anticancer properties. Rhenium-platinum system with β-alanine ligand in aqueous solution, has been found. Its injection is accompanied by the hepatoprotective effect.

Synergistic Behavior of Bimetallic Rhenium Cluster Catalysts: Spectroscopic Investigation into the Nature of the Active Site

Single-site Re nanoparticles were produced by anchoring dirhenium organometallic clusters on to the inner walls of mesoporous silica. The presence of oxophilic atoms (Sb or Bi) is essential to obtain well dispersed Re(0) centers. The interaction between the organometallic cluster and the silica support is critical for the generation of well-defined and isolated Re(0) single sites. FTIR spectroscopy was used to track the decomposition of the organometallic precursors and the adsorption of probe molecules such as CO on the metal sites sheds valuable information on the catalytic potential of this new class of bimetallic nanocatalysts.

ChemInform Abstract: Tellurium-Containing Rhenium Cluster Complexes

Synthetic procedures as well as the structures and some properties of tetrahedral and octahedral tellurium-containing rhenium cluster complexes are reported. Crystal chemistry of various types of structure is discussed.

Direct hydrogenolysis of glycerol into 1,3-propanediol over rhenium-modified iridium catalyst

Rhenium-oxide-modified supported iridium nanoparticles on silica catalyzes direct hydrogenolysis of glycerol to 1,3-propanediol in an aqueous media. The selectivity to 1,3-propanediol at an initial stage reaches 67 ± 3%. The yield of 1,3-propanediol reaches 38% at 81% conversion of glycerol. The characterization of catalyst and the reactivity of alcohols suggest that 1,3-propanediol is produced by the attack of active hydrogen species on iridium metal to 1-glyceride species formed on the oxidized rhenium cluster.

A new hexanuclear rhenium cluster complex with six terminal acetate ligands: Synthesis, structure, and properties of K 4[Re 6S 8(CH 3COO) 6]·8H 2O

A room-temperature reaction between [Re 6S 8(OH) 6] 4− and acetic acid in an aqueous solution resulted in the substitution of all terminal hydroxo groups by acetate ligands, affording a new hexanuclear anionic rhenium cluster complex [Re 6S 8(CH 3COO) 6] 4−. The complex was isolated as a potassium salt with the composition of K 4[Re 6S 8(CH 3COO) 6]·8H 2O ( 1) and characterized by X-ray single-crystal diffraction and elemental analyses, IR, 1H NMR, UV–Vis, and luminescence spectroscopies.

An Electrochemical and Photophysical Study of a Covalently Linked Inorganic–Organic Dyad

A molecular donor-acceptor dyad comprising a hexarhenium cluster core, [Re(6)(mu(3)-Se)(8)](2+), and a fullerene moiety which are covalently linked through a pyridine ligand was synthesized and fully characterized. The electrochemical and photophysical properties are reported. The detailed study includes cyclic voltammetry, steady-state absorption and fluorescence spectroscopy, radiation chemistry and transient absorption spectroscopy. A light-induced electron transfer between the inorganic cluster moiety and the fullerene can be excluded. However, a light-induced energy transfer from the rhenium cluster to the fullerene is proposed.

Probing C–O bond activation on gas-phase transition metal clusters: Infrared multiple photon dissociation spectroscopy of Fe, Ru, Re, and W cluster CO complexes

The binding of carbon monoxide to iron, ruthenium, rhenium, and tungsten clusters is studied by means of infrared multiple photon dissociation spectroscopy. The CO stretching mode is used to probe the interaction of the CO molecule with the metal clusters and thereby the activation of the C-O bond. CO is found to adsorb molecularly to atop positions on iron clusters. On ruthenium and rhenium clusters it also binds molecularly. In the case of ruthenium, binding is predominantly to atop sites, however higher coordinated CO binding is also observed for both metals and becomes prevalent for rhenium clusters containing more than nine atoms. Tungsten clusters exhibit a clear size dependence for molecular versus dissociative CO binding. This behavior denotes the crossover to the purely dissociative CO binding on the earlier transition metals such as tantalum.

Закономірності взаємодії антиген–антитіло у розчинах кластерних сполук ренію та цисплатину

Досліджено вплив кластерних сполук ренію з різноманітними лігандами на реакцію антиген–антитіло з використанням імунодифузійних та імуноелектрофоретичних методів. Показано принципово різний характер впливу зазначених агентів на імунохімічні взаємодії. Проаналізовано закономірності впливу даних агентів на реакцію між імуноглобулінами людини та антитілами до них.

Rhenium complexes and clusters supported on γ-Al 2O 3: Effects of rhenium oxidation state and rhenium cluster size on catalytic activity for n-butane hydrogenolysis

Supported metals prepared from H 3Re 3(CO) 12 on γ-Al 2O 3 were treated under conditions that led to various rhenium structures on the support and were tested as catalysts for n-butane conversion in the presence of H 2 in a flow reactor at 533 K and 1 atm. After use, two samples were characterized by X-ray absorption edge positions of approximately 5.6 eV (relative to rhenium metal), indicating that the rhenium was cationic and essentially in the same average oxidation state in each. But the Re–Re coordination numbers found by extended X-ray absorption fine structure spectroscopy (2.2 and 5.1) show that the clusters in the two samples were significantly different in average nuclearity despite their indistinguishable rhenium oxidation states. Spectra of a third sample after catalysis indicate approximately Re 3 clusters, on average, and an edge position of 4.5 eV. Thus, two samples contained clusters approximated as Re 3 (on the basis of the Re–Re coordination number), on average, with different average rhenium oxidation states. The data allow resolution of the effects of rhenium oxidation state and cluster size, both of which affect the catalytic activity; larger clusters and a greater degree of reduction lead to increased activity.

Reversible sorption of hydrogen on the novel hybrid material based on mesoporous chromium(iii) terephthalate with included rhenium clusters

The interaction of mesoporous chromium(iii) terephthalate [Cr3O(C8H4O4)3F(H2O)2] (MIL-101) with an aqueous solution of the anionic cluster [Re4S4F12]4− ({Re4}) afforded a novel hybrid material {Re4}@MIL-101. According to the elemental analysis data, one cavity of the nanoporous framework contains up to two-three tetranuclear rhenium clusters. The hybrid sorbent obtained reversibly absorbs up to 3.7 wt.% hydrogen at 77 K and 30 atm.

Isomerism in tetrahedral rhenium cluster complexes [Re 4Q 4(PMe 2Ph) 4X 8]·nCH 2Cl 2 (Q = Se, X = Br; Q = Te, X = Cl, Br)

Three new tetrahedral rhenium cluster compounds [Re 4Se 4(PMe 2Ph) 4Br 8]·1.5CH 2Cl 2 ( 1), [Re 4Te 4(PMe 2Ph) 4Br 8]·CH 2Cl 2 ( 2), and [Re 4Te 4(PMe 2Ph) 4Cl 8]·CH 2Cl 2 ( 3) have been synthesized by the reaction of the corresponding precursor chalcohalide complexes [Re 4Q 4(TeX 2) 4X 8] (X = Br, Q = Se (for 1), Te (for 2); X = Cl, Q = Te (for 3)) with dimethylphenylphosphine in CH 2Cl 2. All compounds have been characterized by X-ray single-crystal diffraction and elemental analyses, IR and 31P NMR spectroscopy. 31P NMR spectroscopy indicates the formation of isomers in solution, confirmed by single-crystal X-ray analysis.

Self-Assembly of Ambivalent Organic/Inorganic Building Blocks Containing Re6 Metal Atom Cluster: Formation of a Luminescent Honeycomb, Hollow, Tubular Metal-Organic Framework

Reactions in a sealed glass tube between melted pyrazine (pyz) and a Cs(3)Re(6)Q(i)(7)Br(i)Br(a)(6).H(2)O inorganic rhenium cluster compound (Q = S, Se; "i" for inner and "a" for apical positions) containing [Re(6)Q(i)(7)Br(i)Br(a)(6)](3-) units led to the substitution of three apical bromine ligands by three pyrazine groups with the formation of 3 CsBr as a byproduct. The resulting fac-Re(6)Q(i)(7)Br(i)(pyz)(a)(3)Br(a)(3) building unit, based on a Re(6) metal atom cluster, is neutral and noncentrosymmetric and exhibits an ambivalent organic/inorganic nature owing to the opposite disposition of the three apical pyrazine groups versus the three apical bromine atoms. These compounds were characterized by single-crystal and powder X-ray diffraction, elemental and thermal analyses, and luminescence measurements. The crystal structure of fac-Re(6)Q(i)(7)Br(i)(pyz)(a)(3)Br(a)(3).xH(2)O (Q = S (1) and Se (2)) displays an original, neutral metal-organic framework based on the self-assembling of fac-Re(6)Q(i)(7)Br(i)(pyz)(a)(3)Br(a)(3) hybrid building units. The latter are held together by supramolecular interactions: pi-pi, hydrogen bonds (C-H...N, C-H...Br(a), and C-H...Br(i)), and van der Waals contacts. It gives rise to a honeycomb porous structure of parallel hollow open-ended channels wherein the water molecules are located. Their removal does not lead to the collapsing of the structural edifice. The channel walls are constituted by hydrogen atoms from pyrazine as well as apical bromine from the cluster unit. To our knowledge, the structures of 1 and 2 constitute with that of PTMTC (perchlorotriphenylmethyl functionalized by carboxylic group radicals) one of the rare examples of stable open frameworks stabilized by supramolecular interactions between neutral molecules. Moreover, 1 is the first example of luminescent Re(6) compound built up from a noncentrosymmetric Re(6)S(i)(7)Br(i) cluster core.

Novel compounds based on [Re6Q8(L)6]4− (Q = S, Se, Te; L = CN, OH) and their applications

[Re6Q8L6]4− (Q = S, Se, Te) clusters can serve as promising “building blocks” for the creation of new porous framworks, nanoparticles and mesoporous materials. Since [Re6Q8L6]4−clusters have multi-anchoring sites for transition metals, metal–organic complexes, polymers, and multidentated metal complexes, they could be assembled to form various inorganic or organic–inorganic hybrid solids with new various spatial and chemical functions. Because of the controllable architectures and multi-anchoring sites of clusters together with their photoluminescence, rhenium cluster complexes are promising potential candidates as catalysts, chemical color sensors, magnetic materials, gas storage materials, optoelectronic, diagnostic agents, and gene/drug carriers. A new type of mesoscale material comprising [Re6Q8(CN)6]4− and various divalent transition metals in the presence of a liquid crystal template are obtained in 3D cubic, 2D hexagonal, and lamellar phases. The hexahydroxo complexes [Re6Q8(OH)6]4− (Q = S, Se) with high reactivities and a unique rhenium sulfido–cyanide compound, K8[Re12CS17(CN)6] with a C-centered {Re12} cluster unit were discovered and still many more new rhenium metal cluster complexes at various reaction conditions remain to be explored.