Search

Photoactive transition metal compounds that are prone to reversible redox reactions are important for myriad applications, including catalysis, optoelectronics, and sensing. This article describes chemical and electrochemical methods to prepare cluster complex (Bu4N)[{Mo6I8}Cl6], a rare example of a 23 e- cluster complex within the family of octahedral clusters of Mo, W, and Re. The low temperature and room temperature crystal structures; electronic structure; and the magnetic, optical, and electrochemical properties of this complex are described.

Molybdenum octahedral clusters, when incorporated into an appropriate polymer matrix, are considered as promising agents for a range of biological applications. This work describes the one-pot synthesis, morphology and cellular toxicity of nano-sized polystyrene beads doped with luminescent cluster complexes [(Mo6X8)(NO3)6]2- (X=Cl, Br or I). Specifically, the particles were obtained by free radical dispersion copolymerisation of styrene and methacrylic acid or 4-vinylpyridine in the presence of the cluster complexes. The effects of the cluster loading in the reaction mixture on both the content of the final material and number-average molar mass of the copolymers were evaluated.

Octahedral rhenium cluster complexes have recently emerged as relevant building blocks for the design of singlet oxygen photosensitizing materials toward biological applications such as blue-light photodynamic therapy. However, their singlet oxygen generation ability as well as biological properties have been studied only superficially. Herein we investigate in detail the singlet oxygen photogeneration, dark and photoinduced cytotoxicity, cellular uptake kinetics, cellular localization and in vitro photoinduced oxidative stress, and photodynamic cytotoxicity of the series of octahedral rhenium cluster complexes [{Re6Q8}(CN)6]4–, where Q = S, Se, Te. Our results demonstrate that the selenium-containing complex possesses optimal properties in terms of absorption and singlet oxygen productivity. These features coupled with the cellular internalization and low dark toxicity lead to the first photoinduced cytotoxic effect observed for a molecular [{M6Q8}L6] complex, making it a promising object for further stu...

Selective substitution of μ-SO22- groups by either O2- or Se2- ions occurs upon heating the bioctahedral rhenium cluster complex K6[Re12CS14(μ-SO2)3(CN)6] in air atmosphere or in the presence of a Se source, respectively, manifesting the remarkable lability of SO22- ligands bound to a transition-metal cluster. A series of compounds based on the new mixed-ligand anions, [Re12CS14(μ-O)3(CN)6]6-, [Re12CS14(μ-Se)3(CN)6]6-, and [Re12CS14(μ-O)3(OH)6]6-, were isolated and their solid-state structures were elucidated by single-crystal X-ray diffraction analysis. Along with the previously reported μ-sulfide clusters, the new species constitute a series of rhenium anionic complexes with the common formula [Re12CS14(μ-Q)3L6]6- (Q = O, S, Se, L = CN-; Q = O, S, L = OH-), within which the total charge and number of cluster valence electrons (CVEs) are constant. The article presents insights into the mechanistic and synthetic aspects of the substitution process, and it comprehensively discusses the influence of inner ligand environment on the structure, spectroscopic characteristics, and electrochemical behavior of the novel compounds.

Three new polymeric compounds of general formula {[Ln(phen)(H2O)3Ln(phen)(H2O)2(μ-OH)2][Re4Te4(CN)12]}·H2O (Ln = Dy, Ho, Er) were obtained by self-assembly reaction of [Re4Te4(CN)12]4– cluster anions, Ln3+ cations and 1,10-phenthroline (phen) in a solvothermal conditions. Single-crystal X-Ray diffraction showed that structure of compounds consist of non-charged ladder-type chains formed by [Re4Te4(CN)12]4− cluster anions and dimeric cationic complexes [Ln(phen)(H2O)3Ln(phen)(H2O)2(μ-OH)2]4+. Chains are packed parallel and linked with each other by a system of hydrogen bonds. The magnetic susceptibility of compounds is determined by exchange coupled Ln3+ ions in dimeric cationic fragments. The anisotropy effects take place and cause non-linear field dependencies of magnetization for the complexes.

This article evaluates the link between ligands on rhenium clusters and their toxicity., The octahedral rhenium cluster compound Na2H8[{Re6Se8}(P(C2H4CONH2)(C2H4COO)2)6] has recently emerged as a very promising X-ray contrast agent for biomedical applications. However, the synthesis of this compound is rather challenging due to the difficulty in controlling the hydrolysis of the initial P(C2H4CN)3 ligand during the reaction process. Therefore, in this report we compare the in vitro and in vivo toxicity of Na2H8[{Re6Se8}(P(C2H4CONH2)(C2H4COO)2)6] with those of related compounds featuring the fully hydrolysed form of the phosphine ligand, namely Na2H14[{Re6Q8}(P(C2H4COO)3)6] (Q = S or Se). Our results demonstrate that the cytotoxicity and acute in vivo toxicity of the complex Na2H8[{Re6Se8}(P(C2H4CONH2)(C2H4COO)2)6] solutions were considerably lower than those of compounds with the fully hydrolysed ligand P(C2H4COOH)3. Such behavior can be explained by the higher osmolality of Na2H14[{Re6Q8}(P(C2H4COO)3)6] versus Na2H8[{Re6Se8}(P(C2H4CONH2)(C2H4COO)2)6].

This article reports the synthesis, crystal structure of new molybdenum hexaazide cluster complex ( n Bu 4 N) 2 [{Mo 6 I 8 }(N 3 ) 6 ] ( 3 ) and comparison of its photophysical and electrochemical properties to those of earlier reported analogues ( n Bu 4 N) 2 [{Mo 6 X 8 }(N 3 ) 6 ] (X = Cl, Br). Additionally, the dimerisation of 3 as a result of hydrolysis was revealed by mass spectrometry and single crystal X-Ray diffraction. Indeed, the structurally characterised compound ( n Bu 4 N) 4 [({Mo 6 I 8 }(N 3 ) 5 ) 2 O] represents the first example of oxo-bridged dimer of octahedral molybdenum clusters complexes.

Octahedral rhenium cluster complexes may have considerable potential as therapeutic and diagnostic drugs due to their luminescent and X-ray contrast properties, as well as their ability to generate singlet oxygen upon photoirradiation. However, their potential biological effects and toxicity in vitro and in vivo are rather far from being understood. Thus, the aim of our research was to study cytotoxicity, intracellular localization and cellular uptake/elimination kinetics in vitro, biodistribution and acute intravenous toxicity in vivo of a complex Na4[{Re6Te8}(CN)6] as the promising compound for biomedical application. The results have demonstrated that the complex penetrates through cell membranes with the maximum accumulation in cells in 24 h of incubation and have low toxic effects in vitro and in vivo. The median lethal dose (LD50) of intravenously administrated Na4[{Re6Te8}(CN)6] is equal to 1082 ± 83 mg/kg. These findings will be useful for future development of cluster-based agents for different biomedical applications.

Luminescent coordination polymers (CPs) based on inexpensive stable precursors are attractive materials for applications. Here we report the synthesis and evaluation of the stability and photophysical characteristics of the first examples of phosphorescent CPs based on octahedral molybdenum and tungsten cluster anions. In particular, 1D CP trans-[{Ca(OPPh3)4}{{M6Cli8}Cla6}]∞ (M = Mo, W) can be obtained either directly at increased temperature or via intermediate phases [cis-Ca(OPPh3)4(H2O)2][{M6Cli8}Cla6]·2CH3CN that are stable at room-temperature, but convert to the titled CPs at temperatures above 100 °C.

The development of water-soluble forms of octahedral molybdenum clusters {Mo6X8}4+ (X = Cl, Br, I) is strongly motivated by the tremendous potential that these complexes have for biological applications, namely as agents for bioimaging and photodynamic therapy. In this work, we report the first water-soluble hybrid materials, which represent sodium polystyrene sulfonate doped by molybdenum clusters, and the evaluation of their photophysical and biological properties (dark and photoinduced cytotoxicity and cellular uptake) with the use of cervical cancer (HeLa) and human epidermoid larynx carcinoma (Hep-2) cell-lines as models.

Herein we report the comparative study of cytotoxicity of a series of hexarhenium cluster complexes of general formula [{Re 6 Q 8 }L 6 ] n (Q = S, Se, Te; L = P(CH 2 CH 2 COO – ) 3 , SO 3 2– , OH – , CN – ) in the presence of hydrophilic polymers: dextran-70 (Mw ∼70 kDa) and polyethylene glycol (Mw ∼40 kDa) and their oxidised derivatives. It was demonstrated that cluster complexes in the presence of dextran polymers are generally more cytotoxic than non-coated cluster complexes, while PEG-coated cluster complexes are vice versa less cytotoxic.

New octahedral rhenium cluster complexes [{Re

The first luminescent twelve-nuclear rhenium cluster complexes were obtained. Three new clusters, namely, [Re12CS14(μ-Cl)3Cl6]5-, [Re12CS14(μ-Br)3Cl6]5- and [Re12CS14(μ-Br)3Br6]5-, were synthesized using the non-isovalent substitution of μ-O ligands within the {Re12CS14(μ-O)3}0 cluster core by halide anions. The geometry of the new clusters was investigated by X-ray structural analysis, and the electronic structures were evaluated by the use of DFT calculations. It was found that compounds based on these anions showed red luminescence in both the solid state and solution that was never observed before for previously studied twelve-nuclear rhenium clusters.

New tetrahedral anionic rhenium cluster complexes [{Re

Three new polymeric compounds with general formula {[Gd(phen)(H2O)3Gd(phen)(H2O)2(μ-OH)2][Re4Q4(CN)12]}·nH2O (Q = S0.84Te0.16, n = 0.25 for compound 1; Q = Se, Te, n = 1 for compounds 2, 3, respectively) were obtained by self-assembly reaction of [Re4Q4(CN)12]4− cluster anions, Gd3+ cation and 1,10-phenthroline (phen) in a solvothermal conditions. Compounds were investigated by single-crystal X-ray diffraction, magnetic measurements and thermogravimetric analysis. Structure of compounds consist of non-charged ladder chains formed by alternating [Re4Q4(CN)12]4− cluster anions and dimeric cationic complex [{Gd(phen)(H2O)3Gd(phen)(H2O)2(μ-OH)2}]4+ connected through –C N–Gd–N C– covalent bonds. Chains are packed parallel and linked with each other by a system of hydrogen bonds. The magnetic susceptibility of compounds is determined by spins of Gd3+ ions that weakly antiferromagnetic coupled in dimeric cationic fragments.

The octahedral cluster compound Na2 H8 [{Re6 Se8 }(P(C2 H4 CONH2 )(C2 H4 COO)2 )6 ] has been shown to be highly radio dense, thus becoming a promising X-ray contrast agent. It was also shown that this compound had low cytotoxic effect in vitro, low acute toxicity in vivo and was eliminated rapidly from the body through the urinary tract. The present contribution describes a more detailed cellular internalization assay and morphological analysis after intravenous injection of this hexarhenium cluster compound at different doses. The median lethal dose (LD50 ) of intravenously administrated compound was calculated (4.67 ± 0.69 g/kg). Results of the study clearly indicated that the cluster complex Hn [{Re6 Se8 }(P(C2 H4 CONH2 )(C2 H4 COO)2 )6 ]n-10 was not internalized into cells in vitro and induced only moderate morphological alterations of kidneys at high doses without any changes in morphology of liver, spleen, duodenum, or heart of mice. Copyright © 2016 John Wiley & Sons, Ltd.

Self-assembly reaction of [Re 4 Te 4 (CN) 12 ] 4– tetrahedral rhenium chalcocyanide cluster anions, Tm 3+ cations and 1,10-phenanthroline in an H 2 O/EtOH medium was investigated at different temperatures. Slow mixing of reagent solutions at the room temperature lead to formation of cluster compound ( 1 ) containing unique trimeric anionic fragment [{Tm(phen) (H 2 O) 4 }{Tm(phen) 2 (H 2 O) 3 }{Tm(phen) 2 (H 2 O) 2 }{Re 4 Te 4 (CN) 12 } 3 ] 3− ( A1 , phen = 1,10-phenanthroline). Oligomeric anion A1 shows an unusual U-shaped structure build from three cluster anions and three {Tm(phen) n (H 2 O) m } 3+ ( n = 1, 2; m = 2–4) complex cations linked to each other by C N Tm N C covalent bonds and two couples of short OH…N hydrogen bonds. At the elevated (80–100 °C) temperatures the initial reaction products were dissolved, however, further increase of temperature up to 150 °C resulted in formation of layered (2D) coordination polymer K[{Tm(phen) (H 2 O) 3 }{Re 4 Te 4 (CN) 12 }]·0.5H 2 O ( 2 ). In addition to the experimental and X-Ray structural analysis data, thermal decomposition of compounds is also discussed.

Halide octahedral molybdenum clusters [(Mo6X8)L6]n- possess luminescence properties that are highly promising for biological applications. These properties are rather dependent on the nature of both the inner ligands X (i.e. Cl, Br, or I) and the apical organic or inorganic ligands L. Herein, the luminescence properties and the toxicity of thiol-modified polystyrene microbeads (PS-SH) doped with [(Mo6X8)(NO3)6]2- (X=Cl, Br, I) were studied and evaluated using human epidermoid larynx carcinoma (Hep2) cell cultures. According to our data, the photoluminescence quantum yield of (Mo6I8)@PS-SH is significantly higher (0.04) than that of (Mo6Cl8)@PS-SH (6Br8)@PS-SH (6X8)@PS-SH showed that all three types of doped microbeads had no significant effect on the viability and proliferation of the cells.

The present work describes a new method to sense cholinesterase-catalyzed hydrolysis of acetylcholine (ACh) through a luminescence response of the hexarhenium cluster complex [{Re6S8}(OH)6](4-). A proton released from acetylcholinesterase (AChE)- or butyrylcholinesterase (BuChE)-catalyzed hydrolysis of ACh results in time-resolved sensitization of cluster-centered luminescence. The sensitization results from protonation of apical hydroxo-groups of the cluster complex. The protonation is affected by a counter ion effect. Thus, optimal conditions for adequate sensing of acetic acid produced by ACh hydrolysis are highlighted. Time-resolved luminescence and pH measurements under conditions of AChE-catalyzed hydrolysis of ACh show a good correlation between the cluster-centered luminescence and pH-induced inhibition of AChE. The inhibition is not significant within the first two minutes of ACh hydrolysis. Thus, the luminescence response measured within two minutes is dependent on both substrate and enzyme concentrations, which fits with AChE and BuChE kinetics. The usability of cluster-centered luminescence for monitoring the concentration-dependent inhibition of AChE with irreversible inhibitors is demonstrated, using a carbamylating agent, pyridostigmine bromide, as a model.

Photoluminescent silica-based materials are used in applications in photonics, sensing, and biological and medical sciences. Specifically, hybrid particles based on silica doped by photoluminescent octahedral molybdenum metal cluster complexes are inexpensive and readily available via the Stober process and thus are promising materials for diverse applications. We evaluated design of photoluminescent materials based on silica and {Mo6X8}4+ clusters (where X = Cl, Br, I), including how synthesis conditions (chemical composition of metal cluster precursors (Bu4N)2[{Mo6X8}(NO3)6], loading of the precursor and presence of a surfactant) influence key parameters of the final materials, such as phase composition, size and morphology of the particles and photophysical characteristics. Our study revealed that hydrolysis of the molybdenum cluster precursors during the Stober process strongly affects both morphology and photophysical parameters of the materials, especially at high loadings. At relatively low loadings of the precursors, materials doped by {Mo6I8}4+ clusters demonstrated the most promising set of properties—the highest photoluminescence quantum yields and efficient singlet oxygen generation—while particle size and morphology remained the same as for undoped SiO2 materials.

Tungsten trioxide has been found to be a convenient precursor for the synthesis of metal cluster compounds with new types of cluster cores. The reaction between WO3 and KCN led to the formation of the cluster complex [{W6(μ4-O)2(μ3-CCN)4}(CN)16]10-. Unexpectedly, it includes the fully deprotonated form of acetonitrile, the CCN3- anion, as a μ3-bridging ligand coordinated to the trigonal faces of the bitetrahedral W6 metallocluster. A similar complex [{W6(μ4-O)2(μ3-As)4}(CN)16]10- containing μ3-As3- ligands instead of μ3-CCN3- ones has been synthesized by the reaction between WO3, As and KCN.

Water-soluble salts of anionic [Re6 Q8 (CN)6 ]4- (Q=S, Se, Te) chalcogenide octahedral rhenium clusters react with γ-cyclodextrin (γ-CD) producing a new type of inclusion compounds. Crystal structures determined through single-crystal X-ray diffraction analysis revealed supramolecular host-guest assemblies resulting from close encapsulations of the octahedral cluster within two γ-CDs. Interestingly, nature of the inner Q ligands influences strongly the host-guest conformation. The cluster [Re6 S8 (CN)6 ]4- interacts preferentially with the primary faces of the γ-CD while the bulkier clusters [Re6 Se8 (CN)6 ]4- and [Re6 Te8 (CN)6 ]4- exhibit specific interactions with the secondary faces of the cyclic host. Furthermore, analysis of the crystal packing reveals additional supramolecular interactions that lead to 2D infinite arrangements with [Re6 S8 (CN)6 ]4- or to 1D "bamboo-like" columns with [Re6 Se8 (CN)6 ]4- and [Re6 Te8 (CN)6 ]4- species. Solution studies, using multinuclear NMR methods, ESI-MS and Isothermal titration calorimetry (ITC) corroborates nicely the solid-state investigations showing that supramolecular pre-organization is retained in aqueous solution even in diluted conditions. Furthermore, ITC analysis showed that host-guest stability increases significantly ongoing from S to Te. At last, we report herein that deep inclusion alters significantly the intrinsic physical-chemical properties of the octahedral clusters, allowing redox tuning and near IR luminescence enhancement.

Unlike silica nanoparticles, the potential of silica mesoparticles (SMPs) (i.e. particles of submicron size) for biological applications in particular the in vitro (let alone in vivo) cellular delivery of biological cargo has so far not been sufficiently studied. Here we examine the potential of luminescent (namely, octahedral molybdenum cluster doped) SMPs synthesised by a simple one-pot reaction for the labelling of cells and for protein transduction into larynx carcinoma (Hep-2) cells using GFP as a model protein. Our data demonstrates that the SMPs internalise into the cells within half an hour. This results in cells that detectably luminesce via conventional methods. In addition, the particles are non-toxic both in darkness and upon photo-irradiation. The SMPs were modified to allow their functionalisation by a protein, which then delivered the protein (GFP) efficiently into the cells. Thus, the luminescent SMPs offer a cheap and trackable alternative to existing materials for cellular internalisation of proteins, such as the HIV TAT protein and commercial protein delivery agents (e.g. Pierce™).

The redox-active rhenium octahedral cluster unit [Re6Se8(CN)6]4– was combined with Gd3+ ions and dicarboxylate linkers in novel types of metal–organic frameworks (MOFs) that display a set of functi...

A series of four new coordination compounds [{Cu(bpy) 2 (μ-CN)Cu(bpy)} 2 Re 6 S 8 (CN) 6 ]·bpy·2H 2 O ( 1 ), [{Cu(bpy)} 2 (μ-CN)][{Cu(bpy)} 3 Re 6 S 8 (CN) 6 ] ( 2 ) and [{Cu(bpy)(μ-CN)Cu(bpy)} 2 {Cu(bpy)} 2 Re 6 Q 8 (CN) 6 ] ( 3 , Q = Se; 4 , Q = Te) have been synthesized by the reactions of hexanuclear rhenium(III) chalcocyanide complexes, CuCN and 2,2′-bipyridine (bpy) under hydrothermal conditions. Compound 1 was characterized by single-crystal X-ray diffraction analysis, compounds 2 – 4 were characterized by a set of methods, including IR spectroscopy, thermal analysis, elemental analysis, EDS, and single-crystal X-ray diffraction analysis. 1 has a molecular structure, in which two cyano groups of cluster anion [Re 6 S 8 (CN) 6 ] 4− are N-bonded to the dimeric mixed-valent cations {Cu(bpy) 2 (μ-CN)Cu(bpy)} 2+ through axial coordination to the Cu + cations. In 2 , the cluster anions provide all of their six cyano groups for coordination with the copper centers of {Cu(bpy)} + moieties, giving rise to a 3D framework in which the cavities are occupied by the dimeric cations [{Cu(bpy)} 2 (μ-CN)] + . 3 and 4 are isostructural and have a 1D chain structure, in which four equatorial cyano groups of cluster anions are N-bonded to the {Cu(bpy)} + bridging fragments, while two axial cyano groups are terminated by dimeric cations {Cu(bpy)(μ-CN)Cu(bpy)} + . The compounds synthesized appear to be the first examples which combine hexanuclear rhenium(III) chalcocyanide clusters and monovalent Cu(I) ions.

Compounds with general formula (bipyH2)[{Ln(H2O)6}{Re4Te4(CN)12}]2·10H2O (Ln = Gd (1), Dy (2), Tb (3), Ho (4), Er (5)) were obtained by evaporation of acidic aqueous solution containing salts of [Re4Te4(CN)12]4− cluster anion, respective lanthanide cation and 4,4′-bipyridine. Structures of compounds 1–5 consist of dimeric cluster fragments [{Ln(H2O)6}{Re4Te4(CN)12}]22−, forming supramolecular ionic structure with outer-sphere 4,4′-bipyridinium cations and H2O molecules. Magnetic susceptibility of all compounds in the range of temperature 80–300 K was measured; thermal stability was also investigated.

Although many of the layered metal chalcogenides, such as MoS2, are well-studied, some other chalcogenides have received less attention by comparison. In particular, there has been an emerging interest in vanadium tetrasulfide (VS4), which displays useful properties as a component of hybrids. However, the synthetic methods and characteristics of individual VS4 are not yet well defined, and there is no report on its solution processability. Here we have synthesized VS4 by a simple and fast direct reaction between elements. Reinvestigation of the VS4 crystal structure yielded more precise atomic coordinates and interatomic distances, thereby confirming the crystallization of VS4 in the monoclinic C2/c group and its quasi-1D chainlike structure. As the chains in VS4 are only bonded by weak van der Waals forces, we further demonstrate that bulk VS4 may be ultrasonically dispersed in appropriate solvents to form colloids, similarly to the layered chalcogenides. VS4 particles in colloids retain their phase identity and rod-shaped morphology with lengths in the range of hundreds of nanometers. Isopropanol dispersion exhibited the highest concentration and stability, which was achieved owing to the repulsion caused by high negative charges on the edges of the particles.

Three new salts of tetrahedral rhenium chalcocyanide cluster anions [Re4Q4(CN)12]4− (Q = S, Se, Te) and 1,10-phenanthroline-1-ium cations, (phenH)4[Re4S4(CN)12]·6H2O (1), (phenH)4[Re4Se4(CN)12]·6H2O (2), and (phenH)4[Re4Te4(CN)12]·10H2O (3), have been synthesized by reactions of K4[Re4Q4(CN)12]·nH2O with 1,10-phenanthroline in the presence of Nd3+ in an acidic aqueous medium (pH 4). 1 and 2 exhibit similar 2-D layered supramolecular architectures based on hydrogen bonds between water molecules, CN-groups of cluster anions, and phenH+ cations. The latter are involved in π–π and C–H⋯π stacking interactions, connecting the adjacent layers with each other. Complex 3 demonstrates a 3-D framework based on hydrogen bonds between water molecules and CN-groups, π–π and C–H⋯π interactions. Notably short O···Te contacts of 3.40 and 3.50 Å are found in the structure of 3. The thermal properties of 1–3 have been investigated by TG-DTG.

The reaction between ZnCl2 and an aqueous solution of CaK4[Re3Mo3S8(CN)6]·8H2O is controlled by the concentration of NH3. High concentration of NH3 favors the formation of [Zn(NH3)4]8{Zn[Re3Mo3S8(CN)6]3}·9H2O with an ideal primitive cubic 3D network of Zn2+ cations joined by cyanocluster anions acting as unprecedented bulky linear spacers. The low concentration of NH3 leads to the formation of the usual Prussian blue structure [Zn(NH3)4]2[ZnRe3Mo3S8(CN)6]·2H2O with alternating octahedral Zn2+ and cyanocluster nodes. Both compounds contain a paramagnetic cluster anion with g = 2.279 and 2.280, respectively. Powder diffraction studies prove that the former compound transforms into the latter after the exposure of a polycrystalline sample to air.

Photoactive transition metal compounds that are prone to reversible redox reactions are important for myriad applications, including catalysis, optoelectronics, and sensing. This article describes chemical and electrochemical methods to prepare cluster complex (Bu

Selective substitution of μ-SO

Octahedral cluster complexes of transition metals are associated with halogen or chalcogen inner ligands to form edge-bridged {M6(μ2-X)12} or face-capped {M6(μ3-X)8} cluster cores. The partial exchange of X atoms leading to mixed inner ligand environment invokes a distortion of metallic cluster, reduction of symmetry as well as an isomerism of the cluster cores. This review summarizes preparation methods of mixed ligand cluster complexes with the general formulas [{M6(μ2-X)12}L6] n or [{M6(μ3-X)8}L6] n and their structural features.

Stable colloidal dispersions of niobium chalcogenides NbQ 2 and NbQ 3 (Q = S, Se) in organic solvents – CH 3 CN, dmf, i PrOH, EtOH, EtOH/H 2 O (vol. 1/1), n -BuOH were prepared by ultrasonication. According to DLS and AFM data the particle size distributions in the dispersions are rather wide: particle sizes vary from 70 to 400 nm, and the mean sizes are in range of 150–200 nm. DLS polymodal and monomodal analyses were carried out for the colloidal dispersions of NbQ 2 and NbQ 3 (Q = S, Se) in acetonitrile. The particles diffusive Brownian motion in the acetonitrile colloidal dispersions is best described by diffusion of disk-shaped particles with monomodal distributions for NbQ 3 and bimodal distributions for NbQ 2 . A series of thin films prepared from the colloidal dispersions show that the particles retain their original crystal structures, at the same time strong texturing of the films appears.

Four new octahedral rhenium cluster complexes trans-[{Re6Q8}(PPh3)4X2] (Q = S, Se; X = Cl, I) were synthesized by reaction of cesium salts of cluster anions [{Re6Q8}X6]4−/3− with molten triphenylphosphine. The compounds were characterized by elemental and X-ray structural analyses. Emission spectra and photophysical characteristics for all new compounds and earlier described trans-[{Re6Q8}(PPh3)4Br2] were obtained showing a dependence of the emission maximum wavelength, quantum yield and lifetime values from cluster ligand environment.

The hexarhenium cluster complexes with benzotriazolate apical ligands [{Re6(μ3-Q)8}(BTA)6](4-) (Q = S, Se; BTA = benzotriazolate ion) were obtained by the reaction of [{Re6(μ3-Q)8}(OH)6](4-) with molten 1H-BTA (1H-benzotriazole). The clusters were crystallized as potassium salts and characterized by X-ray single-crystal diffraction, elemental analyses, and UV-vis and luminescence spectroscopy. In addition, their cellular uptake and toxicity were evaluated. It was found that both clusters exhibited luminescence with high lifetimes and quantum yield values; they were taken up by the cells illuminating them under UV irradiation and, at the same time, did not exhibit acute cytotoxic effects.

International audience; At the occasion of the fiftieth birthday of the introduction of the term 'metal atom cluster' by F. A. Cotton in inorganic chemistry, it is the good time to make a review on the advances in the engineering of molecular assemblies and nanomaterials based on octahedral Re6 metal atom clusters. The latter exhibit unique intrinsic structural and physicochemical properties (orthogonal disposition of metallic sites that can be selectively functionalized, photoluminescence, redox, generation of singlet oxygen) that make them relevant building blocks for the structuration at the nanometric scale and functionalization of hybrid organic-inorganic materials and supramolecular frameworks. After synthesis by solid state chemistry techniques at high temperature, inorganic precursors built up on face-capped [(Re6Yi8)Ya6] cluster units (Y = chalcogen and/or halogen) can be functionalized via solution chemistry techniques or organic melts to form [(Re6Yi8)La6] (L = CN, OH, various organic ligands...). This work reports advances in the synthesis of [(Re6Yi8)Ya6] and [(Re6Yi8)La6] cluster units as well as on their use in the elaboration of supramolecular frameworks, nanoparticles, hybrid nanomaterials (co-polymers and liquid crystals) and active molecular junctions.

The first example of dodecanuclear chalcohalide rhenium cluster complex, (Et4N)4(Me2NH2)2[Re12CS17Br6] (1), has been synthesized by reaction of polymeric cluster solid Re12CS17 with excess of Et4NBr in boiling DMF. The compound was characterized by a set of methods, including IR and UV–Vis spectroscopy, elemental analysis, EDS, mass-spectrometry, single-crystal X-ray diffraction analysis, and quantum-chemical calculations. The crystal structure presents an interesting case of 1D supramolecular architecture based on notably short Br⋯Br interactions of 3.432 A between the terminal bromide trans-ligands of adjacent [Re12CS17Br6]6− cluster anions. The DFT calculations performed for the [Re12CS17Br6]6− anion showed good agreement between calculated and experimental data.

New polymerisable photoluminescent octahedral rhenium cluster complexes trans-[{Re6Q8}(TBP)4(VB)2] (Q = S or Se; TBP-p-tert-butylpyridine; VB-vinyl benzoate) have been synthesised, characterised and used to construct rhenium cluster-organic polymer hybrid materials. These novel polymer systems are solution-processable and the rhenium clusters retain their photoluminescent properties within the polymer environment. Notably, when the rhenium cluster complexes are incorporated into the matrix of the electroluminescent polymer poly(N-vinylcarbazole), the resultant cluster polymer hybrid combined properties of both components and was used successfully in the construction of a polymer light emitting diode (PLED). These prototype devices are the first PLEDs to incorporate octahedral rhenium clusters and provide the first direct evidence of the electroluminescent properties of rhenium clusters and indeed, to the best of our knowledge, of any member of the family of 24-electron hexanuclear cluster complexes of molybdenum, tungsten or rhenium.

Exfoliated nanomaterials, such as graphene and related few-layered materials, are now widely studied for electronic devices, electrodes and composites, so it is desirable to demonstrate exfoliation of a wider number of layered materials. We have shown that bulk niobium trichalcogenides NbS3 and NbSe3 may be stably dispersed in a number of common organic solvents by ultrasonic treatment. The most concentrated dispersions are obtained in alcoholic media (up to ∼0.443 g L−1). The colloids contain thin well-crystallized nanoribbons of NbS3 and NbSe3. Filtration or spraying of the colloids produces strongly textured thin films with good conducting properties.

A new rhenium cyanohydroxo octahedral cluster complex trans-[Re6S8(CN)2(OH)4]4− has been synthesized for the first time starting from K4[Re6S8(OH)6]·8H2O. It was crystallized as salts of compositions Cs2.67K1.33[Re6S8(CN)2(OH)4]·4H2O (1) and [Cu(NH3)4]2[Re6S8(CN)2(OH)4]·2H2O (2). By the reaction of trans-[Re6S8(CN)2(H2O)4], which was prepared by neutralization of 1 by diluted H2SO4, with molten 3,5-dimethylpyrazole (3,5-Me2PzH), the molecular complex trans-[Re6S8(3,5-Me2PzH)4(CN)2]·2H2O (3) was synthesized. Compounds 1–3 have been characterized by single-crystal X-ray diffraction and elemental analyses, IR spectroscopy and compounds 1 and 3 by UV-Vis and luminescence spectroscopy.

The synthesis and characterisation of a new, highly luminescent inorganic cluster complex, (Bu4N)2[Mo6I 8(NO3)6], are described. The complex possesses labile nitrato ligands and is therefore a useful precursor for the design of new luminescent materials. To exemplify this, functionalised polystyrene beads have been utilised as "polymeric ligands" to immobilise the molybdenum cluster complex. This journal is

This work is devoted to the preparation of trans-[Re6S8(CN)4(OH)(H2O)]3− and trans-[Re6S8(CN)4(H2O)2]2− cluster complexes starting from trans-[Re6S8(CN)4(OH)2]4− and a study of their luminescence properties. The controlled separation of each species could be achieved by pH adjustment: pH > 10, 5.5 H 3 O 2 - intercluster bridging groups through strong hydrogen bonding. The trans disposition of the H 3 O 2 - groups around Re6 enables the formation of polymeric linear chains of cluster complexes.

Interaction of cluster anions [{Re6Q8}X6]4−/3− (Q = S or Se; X = Cl, Br or I) with molten pro-ligands – pyrazole (pzH) and 3,5-dimethylpyrazole (3,5-Me2pzH) has led to the formation of cationic apically homoleptic cluster complexes [{Re6Q8}L6]2+ (L = pzH or 3,5-Me2pzH). All new compounds were characterized by a set of physicochemical properties such as X-ray diffraction analyses on crystals and powders, FTIR and NMR spectroscopies. Synthesis of the complete series of pyrazole complexes and finishing the earlier series of 3,5-dimethylpyrazole complexes with different halogens in addition to the previously described [{Re6Q8}(3,5-Me2pzH)6]Br2·2(3,5-Me2pzH) (Q = S, Se) allowed us to study dependence of luminescence properties on the nature of the inner or outer ligands as well as counterions in detail.

International audience; 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.e. a material's ability upon photoexcitation to convert molecular oxygen into reactive oxygen species such as singlet oxygen), which work with light within the visible photomagnetic spectrum could offer a significantly safer alternative. Here we present a new, bespoke molybdenum cluster (BuN)[{MoI}(CF(CF)COO)], which is both efficient in the generation of singlet oxygen upon photoirradiation and compatible with the fluoropolymer (F-32L) known for its good oxygen permeability. Thus, (BuN)[{MoI(CF(CF)COO)]/F-32L mixtures have been solution-processed to give homogenous films of smooth and fibrous morphologies and which displayed high photoinduced antibacterial activity against four common pathogens under visible light irradiation. These materials thus have potential in applications ranging from antibacterial coatings to filtration membranes and air conditioners to prevent spread of bacterial infections.

A new 2D coordination polymer, [{Cu(NH3)3}2{Re6S8(OH)4(μ-OH)2}]·8H2O (1), has been prepared as a result of reactivity studies of the octahedral rhenium cluster anion [Re6S8(OH)6]4− in a system containing Cu2+ cations in aqueous ammonia. The compound was characterized by means of IR spectroscopy, thermal analysis, elemental analysis and single-crystal X-ray diffraction analysis. The structure determination revealed the presence of neutral layers containing Cu2+ cations surrounded by three NH3 molecules, located midway between two different [Re6S8(OH)6]4− cluster anions. The cluster anion displays an unprecedented bidentate coordination to Cu2+, occurring via the μ3-S ligand (Cu⋯S, 2.996(3) A) and O atom of a terminal OH group (Cu–O, 1.986(7) A). The resultant Cu(II) coordination environment can be described as a stretched octahedral geometry (4 + 2).

Octahedral rhenium cluster complexes may have considerable potential as therapeutic and diagnostic drugs due to their luminescent and X-ray contrast properties, as well as their ability to generate singlet oxygen upon photoirradiation. However, their potential biological effects and toxicity in vitro and in vivo are rather far from being understood. Thus, the aim of our research was to study cytotoxicity, intracellular localization and cellular uptake/elimination kinetics in vitro, biodistribution and acute intravenous toxicity in vivo of a complex Na