Total synthesis of the taraxacine A natural product Ag(I)-catalysed imidate-alkyne cyclization.

A domino approach towards β-carboline natural product taraxacine A and its analogues was developed. The main step relies on a silver(I) and base co-catalysed imidate-alkyne cyclization. The reaction tolerates primary and secondary alcohols, and various substitutions in the indole are possible.

PEGylation of Terminal Ligands as a Route to Decrease the Toxicity of Radiocontrast Re-Clusters.

The development of novel radiocontrast agents, mainly used for the visualization of blood vessels, is still an emerging task due to the variety of side effects of conventional X-ray contrast media. Recently, we have shown that octahedral chalcogenide rhenium clusters with phosphine ligands-NaH[{ReQ}(P(CHCOO))] (Q = S, Se)-can be considered as promising X-ray contrast agents if their relatively high toxicity related to the high charge of the complexes can be overcome. To address this issue, we propose one of the most widely used methods for tuning the properties of proteins and peptides-PEGylation (PEG is polyethylene glycol).

Evolution of the Electronic Structure of the -[ReSbipyCl] Octahedral Rhenium Cluster during Reduction.

Understanding the processes that occur during the redox transformations of complexes coordinated by redox-active apical ligands is important for the design of electrochemically active compounds with functional properties. In this work, a detailed analysis of the interaction energy and electronic structure was performed for cluster complexes -[ReSbipyCl] (n = 2-, 4-, 6-, 8-), which can be obtained by stepwise electrochemical reduction of a neutral cluster -[ReSbipyCl] in DMSO solution. It was shown that the formation of open-shell paramagnetic ions with S = 1, 2 and 1 is the most energetically favorable for n = 2-, 4- and 6-, respectively.

Unusual Square Pyramidal Chalcogenide Mo Cluster with Bridging Pyrazolate-Ligands.

The family of chalcogenide molybdenum clusters is well presented in the literature by a series of compounds of nuclearity ranging from binuclear to multinuclear articulating octahedral fragments. Clusters actively studied in the last decades were shown to be promising as components of superconducting, magnetic, and catalytic systems. Here, we report the synthesis and detailed characterization of new and unusual representatives of chalcogenide clusters: square pyramidal complexes [{Mo(μ-Se)(μ-Se)(μ-pz)}(pzH)] (pzH = pyrazole, i = inner, t = terminal).

Octahedral Rhenium Cluster Complexes with 1,2-Bis(4-pyridyl)ethylene and 1,3-Bis(4-pyridyl)propane as Apical Ligands.

A series of eight new octahedral rhenium cluster complexes with the general formula -[{ReQ}LX] (Q = S or Se; L = 1,2-Bis(4-pyridyl)ethylene (bpe) or 1,3-Bis(4-pyridyl)propane (bpp); X = Cl or Br) was synthesized and investigated. While bpe is a ligand with a conjugated aromatic system, bpp represents a molecule of opposite type and has independent aromatic systems of the two pyridine rings. It was shown that this difference in the electronic structure of the ligands has a fundamental effect on the electronic structure, electrochemical and luminescent properties of the corresponding cluster complexes.

Coordination Polymers Based on Rhenium Octahedral Chalcocyanide Cluster Anions and Ag Cations with Bipyridine Analogs.

A series of six coordination polymers based on octahedral cluster anions [ReQ(CN)] (Q = S or Se) and Ag cations coordinated by bipyridine analogs were synthesized under solvothermal conditions. Their structures have been characterized by single crystal X-ray diffraction. Compounds and described by the general formula [{Ag(phen)}ReQ(CN)] (Q = Se (), S (); phen = 1,10-phenanthroline) exhibit layered structures assembled into a supramolecular network by CH…π contacts.

Selective Oxidation of Inner Pnictogenide Ligands in Mixed-Ligand Rhenium Cubane-Type Cluster Complexes.

Reactivity of new tetrahedral rhenium cluster complexes with pnictogenide inner ligands μ-As, μ-Sb, and μ-Bi has been investigated in reactions with aqueous HO. It has been found that the oxidation of clusters [{ReAsQ}(CN)] (Q = S or Se) led to the formation of stable clusters with μ-(AsO) ligands. Under the same conditions, the oxidation of [{ReAsS}(CN)] cluster led to substitution of μ-As ligands to μ-O.

Water-Soluble Chalcogenide W-Clusters: On the Way to Biomedical Applications.

Despite the great potential of octahedral tungsten cluster complexes in fields of biomedical applications such as X-ray computed tomography or angiography, there is only one example of a water-soluble WQ-cluster that has been reported in the literature. Herein we present the synthesis and a detailed characterization including X-ray structural analysis, NMR, IR, UV-Vis spectroscopies, HR-MS spectrometry, and the electrochemical behavior of two new cluster complexes of the general formula WQL with phosphine ligands containing a hydrophilic carboxylic group, which makes the complexes soluble in an aqueous medium. The hydrolytic stability of the clusters' aqueous solutions allows us to investigate for the first time the influence of W-clusters on cell viability.

The Cluster Polyazide Complexes: Synthesis, Crystal Structures, and N NMR Studies of [{Re(μ-X)}(N)] (X = Br or I).

Azide cluster complexes [{Re(μ-Br)}(N)] and [{Re(-I)}(N)] were obtained by reaction of ReX (X = Br or I, respectively) with sodium azide in methanol. The complexes were crystallized as cesium salts of the compositions Cs[{Re(μ-Br)}(N)]·HO () and Cs[{Re(μ-I)}(N)]·HO () and characterized by X-ray single-crystal diffraction and elemental analyses, mass spectrometry, N NMR spectroscopy, and DFT calculations. In the anions, each rhenium atom is coordinated by three azide ligands.

Crystal Structure Defects in Titanium Nickelide after Pressing at Lowered Temperature.

The experimental results regarding the effect of warm (573 K) pressing with an increase in the specified true strain, , up to 9.55, on the microstructure and crystal structure defects (dislocations, vacancies) of the TiNi (at %) alloy are presented. It is shown that all samples (regardless of ) have a two-level microstructure.

Structure and Phase State of TiNi (at%) Hydrogenated in Normal Saline.

The paper analyzes the surface structure and phase state of TiNi (at%) hydrogenated at 295 K in normal saline (0.9% NaCl aqueous solution with pH = 5.7) at 20 A/m for 0.

Chirality and Relativistic Effects in Os(CO).

The energy and structural parameters were obtained for all forms of the carbonyl complex of osmium Os(CO) with D and D symmetries using density functional theory (DFT) methods. The calculations took into account various levels of relativistic effects, including those associated with nonconservation of spatial parity. It was shown that the ground state of Os(CO) corresponds to the D symmetry and thus may be characterized either as left-twisted (D) or right-twisted (D).

Supramolecular Frameworks Based on Rhenium Clusters Using the Synthons Approach.

The reaction of the K[{ReS}(OH)]·8HO rhenium cluster salt with pyrazine (Pz) in aqueous solutions of alkaline or alkaline earth salts at 4 °C or at room temperature leads to apical ligand exchange and to the formation of five new compounds: [{ReS}(Pz)(OH)(HO)] (), [{ReS}(Pz)(OH)(HO)] (), (NO)[{ReS}(Pz)(OH)(HO)](Pz)·3HO (), [Mg(HO)][{ReS}(Pz)(OH)(HO)]·8.5HO (), and K[-{ReS}(Pz)(OH)(HO)]·8HO (). Their crystal structures are built up from - or -[{ReS}(Pz)(OH)(HO)] cluster units.

Heterogeneous photoactive antimicrobial coatings based on a fluoroplastic doped with an octahedral molybdenum cluster compound.

Despite the wide variety of strategies developed to combat pathogenic microorganisms, the infectious diseases they cause remain a worldwide health issue. Hence, the search for new disinfectants, which prevent infection spread, constitutes an extremely urgent task. One of the most promising methods is the use of photoactive compounds - photosensitizers, capable of generating reactive oxygen species, in particular, singlet oxygen (O2(1Δg)), which causes rapid and effective death of microorganisms of all types.

Stabilization of Re/Re Metalloclusters by Cyanide Ligands in New Trinuclear Rhenium Cluster Complexes [{ReX}(CN)]/[{ReX}(CN)] (X = Br or I).

The interaction of rhenium(III) halides ReBr and ReI with aqueous solution of sodium cyanide resulted in the formation of the first trinuclear halide-cyanide rhenium cluster complexes [{ReX}(CN)]/[{ReX}(CN)] (X = Br or I) crystallized as salts of the compositions CsNa[{ReBr}(CN)]·5.25HO (), CsNa[{ReI}(CN)]·6HO (), Cs[{ReBr}(CN)]·2HO·0.5CsCl (), and Cs[{ReI}(CN)]·().

Inorganic Ligands Sb and Bi: Synthesis and Crystal Structures of Complexes with Mixed-Ligand Cluster Cores {ReSeSb} and {ReSeBi}.

The reactions of ReI, Se, and KCN with SbO or BiO at elevated temperature led to the formation of two new tetrahedral clusters with mixed-ligand cluster cores {ReSeSb} and {ReSeBi}. They are the first examples of complexes with either Sb or Bi ligands, which have never been previously described in the literature.

Cyanide Complexes Based on {MoI} and {WI} Cluster Cores.

Compounds based on new cyanide cluster anions [{MoI}(CN)], -[{MoI}(CN)(MeO)] and -[{WI}(CN)(MeO)] were synthesized using mechanochemical or solvothermal synthesis. The crystal and electronic structures as well as spectroscopic properties of the anions were investigated. It was found that the new compounds exhibit red luminescence upon excitation by UV light in the solid state and solutions, as other cluster complexes based on {MoI} and {WI} cores do.

Cyclodextrin-Assisted Hierarchical Aggregation of Dawson-type Polyoxometalate in the Presence of {ReSe} Based Clusters.

The association of metallic clusters (CLUS) and polyoxometalates (POM) into hierarchical architectures is achieved using γ-cyclodextrin (γ-CD) as a supramolecular connector. The new self-assembled systems, so-called CLUSPOM, are formed from Dawson-type polyoxometalate [PWO] and electron-rich rhenium clusters. It is worth noting that a cluster-based cation [{ReSe}(HO)] on one hand and a cluster-based anion on the other hand [{ReSe}(CN)] can be associated with the anionic POM.

The {Re} Tetrahedral Cyanometalate Cluster Anion [{Re(μ-CCN)}(CN)] with Inner (μ-CCN) Ligands and Its Features in Coordination of Cu Cations.

A reaction between ReI and KCN at elevated temperature led to the formation of the new cyanometalate cluster anion [{Re(μ-CCN)}(CN)] (). The anion contains μ-CCN ligands, which are stabilized by the coordination to the triangular faces of the tetrahedral {Re} metallocluster in a μ mode. The compound crystallized as a potassium salt, and its crystal structure was determined by single-crystal X-ray diffraction analysis.

Photodynamic properties of tungsten iodide clusters incorporated into silicone: A[MIL]@silicone.

The light-induced antibacterial and antifungal properties of A[MIL] with M = Mo and W, A = organic cation, L = ligand have been studied. The photoactive compounds (TBA)[WI(CHSO)] and (TBA)[WI(COOCF)] have been incorporated into a permeable silicone matrix and were measured for their application in the decomposition of multi-resistant bioactive species (hospital germs) such as and as well as fungi. In addition, we present a new high volume synthesis route for these types of cluster compounds departing from the soluble compound WI.

Soluble Molecular Rhenium Cluster Complexes Exhibiting Multistage Terminal Ligands Reduction.

Substitution of terminal halide ligands of octahedral rhenium cluster complexes [ReQX] in a melt of 4,4'-bipyridine (bpy) led to us obtaining four new compounds with the general formula -[ReQ(bpy)X] (Q = S or Se; X = Cl or Br) in high yield. In contrast to most of the known molecular rhenium cluster complexes with heteroaromatic terminal ligands, compounds - are soluble in organic solvents. This made it possible to carry out a detailed characterization of the new compounds both in solids and in solutions.

[{ReQ}(SO)] (Q = S or Se): Facile Synthesis and Properties of the Most Highly Charged Octahedral Cluster Complexes and High Magnetic Relaxivity of Their Colloids with Gd Ions.

New octahedral rhenium cluster complexes [{ReQ}(SO)] (Q = S or Se) were synthesized starting from [{ReQ}(HO)(OH)]·12HO. The complexes were crystallized as sodium salts and characterized by X-ray single-crystal diffraction and elemental analyses, IR, UV/vis and luminescence spectroscopies. Magnetic relaxation data demonstrate the complex formation of the cluster units with gadolinium ions.

Size-Exclusion Mechanism Driving Host-Guest Interactions between Octahedral Rhenium Clusters and Cyclodextrins.

In aqueous solution, cyclodextrins (CDs) are able to bind strongly either hydrophobic species or also hydrophilic molecules such as octahedral hexametallic cluster. Systematic investigation of the reactivity between native CDs (α- or β-CD) and water-soluble rhenium clusters [ReQ(CN)] with Q = S, Se, and Te were performed, leading to six new crystal structures revealing different types of supramolecular arrangements. Encapsulation of [ReQ(CN)] (Q = S, Se, or Te) within two β-CDs is observed regardless of the cluster size.

Octahedral molybdenum cluster as a photoactive antimicrobial additive to a fluoroplastic.

Finding methods that fight bacterial infection or contamination, while minimising our reliance on antibiotics is one of the most pressing needs of this century. Although the utilisation of UV-C light and strong oxidising agents, such as bleach, are still efficacious methods for eliminating bacterial surface contamination, both methods present severe health and/or environmental hazards. Materials with intrinsic photodynamic activity (i.