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Zinc-air batteries (ZABs) are widely studied because of their high theoretical energy density, high battery voltage, environmental protection, and low price. However, the slow kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) on the air electrode limits the further application of ZABs, so that how to develop a cheap, efficient, and stable catalyst with bifunctional catalytic activity is the key to solving the development of ZABs. Transition metal compounds are widely used as cathode materials for ZABs due to their low cost, high electrocatalytic activity, and stable structure. This review summarizes the research progress of transition metal compounds as bifunctional catalysts for ZABs. The development history, operation principle, and mechanism of ORR and OER reactions are introduced first. The application and development of transition metal compounds as bifunctional catalysts for ZABs in recent years are systematically introduced, including transition metal oxides (TMOs), transition metal nitrides (TMNs), transition metal sulfides (TMSs), transition metal carbides (TMCs), transition metal phosphates (TMPs), and others. In addition, the shortcomings of transition metal compounds as bifunctional catalysts for ZABs were summarized and reasonable design strategies and improvement measures were put forward, aiming at providing a reference for the design and construction of high-performance ZABs cathode materials. Finally, the challenges and future in this field are discussed and prospected.

Abstract Due to its characteristics of not being constrained by the lattice structure and cation size, electrochemical conversion reaction is becoming an increasingly prominent type of electrochemical reaction. Lithium‐ion batteries can achieve superior performance by utilizing conversion reactions, Moreover, Sodium‐ion batteries are expected to become alternatives to lithium‐ion because of the plentiful sodium resources. This review discusses the most current developments and unmet needs in anode materials based on conversion reactions of Lithium‐ion and sodium‐ion batteries, as well as various synthesis techniques, morphological characteristics, and electrochemical properties.

The library of true two-dimensional materials is limited since many transition metal compounds are not stratified and can thus not be easily isolated as nanosheets. Here, micron-sized ultrathin rutile TiO2 nanosheets featuring uniform thickness (2 ± 0.5 nm) with dielectric constant (ε⊥ = 24) have been synthesized via a liquid metal synthesis strategy. [ABSTRACT FROM AUTHOR]

The authors define an ab initio electronic structure model that uses partial spin restriction. It is an intermediate case between the so-called spin-restricted and spin-unrestricted formulations, which are popular in electronic structure methodology. Partial spin restriction arises naturally when the wave function is represented as an antisymmetrized product of two-electron functions, as it is done in generalized valence bond and antisymmetrized product of strongly orthogonal geminal theories. The authors show that the new model is size consistent, and it improves the description of transition metal compounds. [ABSTRACT FROM AUTHOR]

We report the synthesis and spectroscopic identification of the trisbenzene complexes of strontium and barium M(Bz)3 (M=Sr, Ba) in low‐temperature Ne matrix. Both complexes are characterized by a D3 symmetric structure involving three equivalent η6‐bound benzene ligands and a closed‐shell singlet electronic ground state. The analysis of the electronic structure shows that the complexes exhibit metal–ligand bonds that are typical for transition metal compounds. The chemical bonds can be explained in terms of weak donation from the π MOs of benzene ligands into the vacant (n−1)d AOs of M and strong backdonation from the occupied (n−1)d AO of M into vacant π* MOs of benzene ligands. The metals in these 20‐electron complexes have 18 effective valence electrons, and, thus, fulfill the 18‐electron rule if only the metal–ligand bonding electrons are counted. The results suggest that the heavier alkaline earth atoms exhibit the full bonding scenario of transition metals. [ABSTRACT FROM AUTHOR]

In this work we reported syntheses and characterization of two novel compounds of adamantane-1-sulfonic acid (1-AdSO3H) with cobalt(II) and cadmium(II), respectively. The result of the single crystal X-ray analysis of compounds revealed that adamantane-1-sulfonate (1-AdSO3 -) in monoanionic form plays a different role in investigated compounds. Namely, while in compound [Co(H2O)6](1-AdSO3)2 six water molecules are coordinated to cobalt(II) ion and 1-AdSO3 - serves as a counter ion, in compound [Cd(H2O)4(1-AdSO3)2] two molecules of 1-AdSO3 - are trans-coordinated to the cadmium(II) ion as monodentate (O) ligand and other coordination sites are occupied by water molecules. The obtained compounds showed a moderate activity against Artemia salina.

The S100 proteins are a large family of signaling proteins that play critical roles in biology and disease. Many S100 proteins bind Zn2+, Cu2+, and/or Mn2+ as part of their biological functions; however, the evolutionary origins of binding remain obscure. One key question is whether divalent transition metal binding is ancestral, or instead arose independently on multiple lineages. To tackle this question, we combined phylogenetics with biophysical characterization of modern S100 proteins. We demonstrate an earlier origin for established S100 subfamilies than previously believed, and reveal that transition metal binding is widely distributed across the tree. Using isothermal titration calorimetry, we found that Cu2+ and Zn2+ binding are common features of the family: the full breadth of human S100 paralogs—as well as two early-branching S100 proteins found in the tunicate Oikopleura dioica—bind these metals with μM affinity and stoichiometries ranging from 1:1 to 3:1 (metal:protein). While binding is consistent across the tree, structural responses to binding are quite variable. Further, mutational analysis and structural modeling revealed that transition metal binding occurs at different sites in different S100 proteins. This is consistent with multiple origins of transition metal binding over the evolution of this protein family. Our work reveals an evolutionary pattern in which the overall phenotype of binding is a constant feature of S100 proteins, even while the site and mechanism of binding is evolutionarily labile. [ABSTRACT FROM AUTHOR]

We present a method of Cu(In,Ga)S2 (CIGS) thin film formation via conversion of layer-by-layer (LbL) assembled Cu-In-Ga oxide (CIGO) nanoparticles and polyelectrolytes. CIGO nanoparticles were created via a novel flame-spray pyrolysis method using metal nitrate precursors, subsequently coated with polyallylamine (PAH), and dispersed in aqueous solution. Multilayer films were assembled by alternately dipping quartz, Si, and/or Mo substrates into a solution of either polydopamine (PDA) or polystyrenesulfonate (PSS) and then in the CIGO-PAH dispersion to fabricate films as thick as 1–2 microns. PSS/CIGO-PAH films were found to be inadequate due to weak adhesion to the Si and Mo substrates, excessive particle diffusion during sulfurization, and mechanical softness ill-suited to further processing. PDA/CIGO-PAH films, in contrast, were more mechanically robust and more tolerant of high temperature processing. After LbL deposition, films were oxidized to remove polymer and sulfurized at high temperature under flowing hydrogen sulfide to convert CIGO to CIGS. Complete film conversion from the oxide to the sulfide is confirmed by X-ray diffraction characterization. [ABSTRACT FROM AUTHOR]

A synthetic study in the Cd-Se-O-Cl system led to formation of the new oxochloride compound Cd4(SeO3)2OCl2 via solid state reactions. The compound crystallizes in the orthorhombic space group Fmmm with cell parameters a = 7.3610(3) Å, b = 15.4936(2) Å, c = 17.5603(3) Å, Z = 8, S = 0.969, F(000) = 2800, R = 0.0185, Rw = 0.0384. Single crystal X-ray data were collected at 293 K. The crystal structure can be considered as layered and the building units are distorted [Cd(1)O6] octahedra, distorted [Cd(2)O8] cubes, irregular [Cd(3)O4Cl2] polyhedra and SeO3E trigonal pyramids. There are two crystallographically unique Cl atoms that both are half occupied. Thermogravimetric studies show that the compound starts to decompose at 500°C. The crystal structure of the new compound is closely related to the previously described compound Cd4(SeO3)2Cl4(H2O). [ABSTRACT FROM AUTHOR]

A synthetic study in the Cd-Se-O-Cl system led to formation of the new oxochloride compound Cd4(SeO3)2OCl2 via solid state reactions. The compound crystallizes in the orthorhombic space group Fmmm with cell parameters a = 7.3610(3) Å, b = 15.4936(2) Å, c = 17.5603(3) Å, Z = 8, S = 0.969, F(000) = 2800, R = 0.0185, Rw = 0.0384. Single crystal X-ray data were collected at 293 K. The crystal structure can be considered as layered and the building units are distorted [Cd(1)O6] octahedra, distorted [Cd(2)O8] cubes, irregular [Cd(3)O4Cl2] polyhedra and SeO3E trigonal pyramids. There are two crystallographically unique Cl atoms that both are half occupied. Thermogravimetric studies show that the compound starts to decompose at 500°C. The crystal structure of the new compound is closely related to the previously described compound Cd4(SeO3)2Cl4(H2O). [ABSTRACT FROM AUTHOR]

Many fluorescent proteins have been created to act as genetically encoded biosensors. With these sensors, changes in fluorescence report on chemical states in living cells. Transition metal ions such as copper, nickel, and zinc are crucial in many physiological and pathophysiological pathways. Here, we engineered a spectral series of optimized transition metal ion-binding fluorescent proteins that respond to metals with large changes in fluorescence intensity. These proteins can act as metal biosensors or imaging probes whose fluorescence can be tuned by metals. Each protein is uniquely modulated by four different metals (Cu2+, Ni2+, Co2+, and Zn2+). Crystallography revealed the geometry and location of metal binding to the engineered sites. When attached to the extracellular terminal of a membrane protein VAMP2, dimeric pairs of the sensors could be used in cells as ratiometric probes for transition metal ions. Thus, these engineered fluorescent proteins act as sensitive transition metal ion-responsive genetically encoded probes that span the visible spectrum. [ABSTRACT FROM AUTHOR]

Streptococcus pneumoniae requires manganese for colonization of the human host, but the underlying molecular basis for this requirement has not been elucidated. Recently, it was shown that zinc could compromise manganese uptake and that zinc levels increased during infection by S. pneumoniae in all the niches that it colonized. Here we show, by quantitative means, that extracellular zinc acts in a dose dependent manner to competitively inhibit manganese uptake by S. pneumoniae, with an EC50 of 30.2 µM for zinc in cation-defined media. By exploiting the ability to directly manipulate S. pneumoniae accumulation of manganese, we analyzed the connection between manganese and superoxide dismutase (SodA), a primary source of protection for S. pneumoniae against oxidative stress. We show that manganese starvation led to a decrease in sodA transcription indicating that expression of sodA was regulated through an unknown manganese responsive pathway. Intriguingly, examination of recombinant SodA revealed that the enzyme was potentially a cambialistic superoxide dismutase with an iron/manganese cofactor. SodA was also shown to provide the majority of protection against oxidative stress as a S. pneumoniae ΔsodA mutant strain was found to be hypersensitive to oxidative stress, despite having wild-type manganese levels, indicating that the metal ion alone was not sufficiently protective. Collectively, these results provide a quantitative assessment of the competitive effect of zinc upon manganese uptake and provide a molecular basis for how extracellular zinc exerts a ‘toxic’ effect on bacterial pathogens, such as S. pneumoniae. [ABSTRACT FROM AUTHOR]

Metal ions are necessary for the proper functioning of the immune system, and, therefore, they might have a significant influence on the interaction between bacteria and host. Ionic dyshomeostasis has been recently observed also in cystic fibrosis (CF) patients, whose respiratory tract is frequently colonized by Stenotrophomonas maltophilia. For the first time, here we used an inductively mass spectrometry method to perform a spatial and temporal analysis of the pattern of changes in a broad range of major trace elements in response to pulmonary infection by S. maltophilia. To this, DBA/2 mouse lungs were comparatively infected by a CF strain and by an environmental one. Our results showed that pulmonary ionomic profile was significantly affected during infection. Infected mice showed increased lung levels of Mg, P, S, K, Zn, Se, and Rb. To the contrary, Mn, Fe, Co, and Cu levels resulted significantly decreased. Changes of element concentrations were correlated with pulmonary bacterial load and markers of inflammation, and occurred mostly on day 3 post-exposure, when severity of infection culminated. Interestingly, CF strain – significantly more virulent than the environmental one in our murine model - provoked a more significant impact in perturbing pulmonary metal homeostasis. Particularly, exposure to CF strain exclusively increased P and K levels, while decreased Fe and Mn ones. Overall, our data clearly indicate that S. maltophilia modulates pulmonary metal balance in a concerted and virulence-dependent manner highlighting the potential role of the element dyshomeostasis during the progression of S. maltophilia infection, probably exacerbating the harmful effects of the loss of CF transmembrane conductance regulator function. Further investigations are required to understand the biological significance of these alterations and to confirm they are specifically caused by S. maltophilia. [ABSTRACT FROM AUTHOR]

Streptococcus pneumoniae requires manganese for colonization of the human host, but the underlying molecular basis for this requirement has not been elucidated. Recently, it was shown that zinc could compromise manganese uptake and that zinc levels increased during infection by S. pneumoniae in all the niches that it colonized. Here we show, by quantitative means, that extracellular zinc acts in a dose dependent manner to competitively inhibit manganese uptake by S. pneumoniae, with an EC50 of 30.2 µM for zinc in cation-defined media. By exploiting the ability to directly manipulate S. pneumoniae accumulation of manganese, we analyzed the connection between manganese and superoxide dismutase (SodA), a primary source of protection for S. pneumoniae against oxidative stress. We show that manganese starvation led to a decrease in sodA transcription indicating that expression of sodA was regulated through an unknown manganese responsive pathway. Intriguingly, examination of recombinant SodA revealed that the enzyme was potentially a cambialistic superoxide dismutase with an iron/manganese cofactor. SodA was also shown to provide the majority of protection against oxidative stress as a S. pneumoniae ΔsodA mutant strain was found to be hypersensitive to oxidative stress, despite having wild-type manganese levels, indicating that the metal ion alone was not sufficiently protective. Collectively, these results provide a quantitative assessment of the competitive effect of zinc upon manganese uptake and provide a molecular basis for how extracellular zinc exerts a ‘toxic’ effect on bacterial pathogens, such as S. pneumoniae. [ABSTRACT FROM AUTHOR]

Results indicate that the hydrolysis rates of the nitrosylruthenium complex under acidic conditions are similar to those occurring with the ruthenium(III) center under basic conditions. Furthermore, the degree of acetonitrile activation coordinated to the nitrosylruthenium complex is equal to that of acetonitrile coordinated to ruthenium(III)center.

We report herein a novel luminescent iridium(III) complex with two hydrophobic carbon chains as a non-reaction based chemosensor for the detection of Hg2+ ions in aqueous solution (<0.002% of organic solvent attributed to the probe solution). Upon the addition of Hg2+ ions, the emission intensity of the complex was significantly enhanced and this change could be monitored by the naked eye under UV irradiation. The iridium(III) complex shows high specificity for Hg2+ ions over eighteen other cations. The system is capable of detecting micromolar levels of Hg2+ ions, which is within the range of many chemical systems. [ABSTRACT FROM AUTHOR]

Mutations in the CLN6 gene cause a variant late infantile form of neuronal ceroid lipofuscinosis (NCL; Batten disease). CLN6 loss leads to disease clinically characterized by vision impairment, motor and cognitive dysfunction, and seizures. Accumulating evidence suggests that alterations in metal homeostasis and cellular signaling pathways are implicated in several neurodegenerative and developmental disorders, yet little is known about their role in the NCLs. To explore the disease mechanisms of CLN6 NCL, metal concentrations and expression of proteins implicated in cellular signaling pathways were assessed in brain tissue from South Hampshire and Merino CLN6 sheep. Analyses revealed increased zinc and manganese concentrations in affected sheep brain in those regions where neuroinflammation and neurodegeneration first occur. Synaptic proteins, the metal-binding protein metallothionein, and the Akt/GSK3 and ERK/MAPK cellular signaling pathways were also altered. These results demonstrate that altered metal concentrations, synaptic protein changes, and aberrant modulation of cellular signaling pathways are characteristic features in the CLN6 ovine form of NCL. [ABSTRACT FROM AUTHOR]

The article focuses on the activation of white phosphorus (P4) through late-transition metal complexes. According to the authors, the importance of studying the coordination chemistry of elemental phosphorus through late and early metal complexes are based on the need for replacing current technology for manufacturing organophosphorus derivatives. This reaction is based on the chlorination of white phosphorus followed by the reaction of PCl3 with an organic molecule.

Density functional calculations were performed to determine equilibrium geometrical structures, transition states and relative energies for M3 clusters (M = Nb, Mo, Tc, Ru, Rh, Pd, Ag) reacting with CO, leading to proposed reaction pathways. For the Nb3, Mo3, and Tc3 clusters, the lowest energy structure correlates to dissociated CO, with the C and O atoms bound on opposite sides of the metal triangle. For all other trimers, the lowest energy structures maintain the CO moiety. In the case of Pd3 and Ag3 the dissociated geometries lie higher in energy than the sum of the separated reactants. In most cases, several multiplicities were found to be similar in energy and for Mo3CO and Pd3CO singlet-triplet minimum energy crossing points were identified. In the case of Rh3CO, minimum energy crossing points for the doublet, quartet, and sextet reaction pathways were determined and compared. The electron densities of pertinent M3CO species were investigated using Natural Bond Order calculations. It was found that the effect of the metal trimer on the energy of the pure p-type π* antibonding orbital of carbon monoxide directly correlates with the occurrence of CO dissociation. © 2008 Wiley Periodicals, Inc.J Comput Chem, 2008. [ABSTRACT FROM AUTHOR]

The primary route to hydrogen production from fossil fuels involves the water-gas shift (WGS) reaction, and an improvement in the efficiency of WGS catalysts could therefore lead to a major leap forward in the realization of hydrogen economy. On the basis of a combination of high-resolution scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory (DFT) calculations, we suggest the existence of a new thermodynamically stable Cu/Pt near-surface alloy (NSA). Temperature-programmed desorption and DFT reveal that this Cu/Pt NSA binds CO significantly more weakly than does Pt alone, thereby implying a considerable reduction in the potential for CO poisoning of the Cu/Pt NSA surface as compared to that of pure Pt. In addition, DFT calculations show that this Cu/Pt NSA is able to activate H20 easily, which is the rate-determining step for the WGS on several metal surfaces, and, at the same time, to bind the products of that reaction and formate intermediates rather weakly, thus avoiding possible poisoning of the catalyst surface. The Cu/Pt NSA is thus a promising candidate for an improved WGS catalyst. [ABSTRACT FROM AUTHOR]

Treatment of [M(CO)6]-, M = Nb, Ta, with Ag+, I2 or NO+ in the presence of CNXyI provided [M(CNXyI)7]+, M(CNXyI)6I, or c/s-[M(CNXyI)4(NO)2]+, which are isocyanide analogues of the unknown carbonyl complexes [M(CO)7]+, M(CO)6I, or cis-[M(CO)4(NO)2]+, respectively. Reduction of M(CNXyI)6I by cesium graphite gave the respective Cs[M(CNXyI)6], which have been structurally characterized and represent the first isolable homoleptic isocyanidemetalates for second or third row transition metals. Nitrosylation of [Ta(CNXyI)6] affords a rare example of a mononitrosyl tantalum complex, Ta(CNXyI)5NO, which is an isocyanide analogue of the unknown Ta(CO)5NO. This study emphasizes, inter alia, the remarkable versatility of the CNXyI ligand compared to CO in stabilizing various electronic environments at heavier group 5 metal centers. [ABSTRACT FROM AUTHOR]

The remarkable polymorphism exhibited by the linear tricobalt compounds, Co3(μ3-dpa)4Crk2 and Co3(μ3-dpa)4Br2, can be explained using a model involving three distinct electronic states. At high temperatures, symmetric and unsymmetric forms arise from the population of doublet (²A) and quartet (4B) states, respectively, the latter containing a localized high-spin CoII center. In the unsymmetric form, a reduction in temperature leads to a spin-crossover to a second quite distinct doublet state, 2B, where, uniquely, the dx²-y² character on the localized Co° center is distributed between the occupied and vacant manifolds. The variable population of the Co dx²-y² orbital gives rise to the continuous change in Co-Co and Co-N bond lengths as the temperature is decreased. [ABSTRACT FROM AUTHOR]

5-(3-(N-tert-Butyl-N-aminoxyl)phenyl)pyrimidine (RL = 3NITPhPyrim) forms isostructural cyclic M2(RL)2 cyclic dimers with M(hfac)2 (M = Mn, Co, Cu; hfac = hexafluoroacetylacetonate). Mn2(hfac)4(RL)2 exhibits strong antiferromagnetic Mn-RL exchange, with weak ferromagnetic exchange (0.7 cm-1) between Mn-RL units that is consistent with a spin polarization exchange mechanism. The magnetic moment of Co2(hfac)4(RL)2 at higher temperatures is consistent with strongly antiferromagnetic exchange within the Co-NIT units and tends toward zero below 50 K at lower magnetic fields. Cu2(hfac)4(RL)2 shows more complex behavior, with no high-temperature plateau in ΧT(T) up to 300 K but a monotonic decrease down to about 100 K. The Cu(ll)-nitroxide bonds decrease by 0.2–0.3 Å over the same temperature range, corresponding to a change of nitroxide coordination from axial to equatorial. This thermally reversible Jahn-Tellar distortion leads to a thermally induced spin state conversion from a high-spin, paramagnetic state at higher temperature to a low-spin state at lower temperature. This spin state conversion is accompanied by a reversible solid-state thermochromic change between dull yellow-brown at room temperature and green at 77 K. [ABSTRACT FROM AUTHOR]

A series of mixed chloro-azole ruthenium complexes with potential antitumor activity, viz., mer-[RulllCl3(azole)3] (B), trans-[RulllCl2(azole)4]Cl (C), trans-[RullCl2(azole)4] (D), and [Rull(azole)6](SO3CF3)2 (E), where azole = 1-butylimidazole (1), imidazole (2), benzimidazole (3), 1-methyl-1,2,4-triazole (4), 4-methylpyrazole (5), 1,2,4-triazole (8), pyrazole (7), and indazole (8), have been prepared as a further development of anticancer drugs with the general formula [RuCl4(azole)2]- (A). These compounds were characterized by elemental analysis, IR spectroscopy, electronic spectra, electrospray mass spectrometry, and X-ray crystallography. The electrochemical behavior has been studied in detail in DMF, DMSO, and aqueous media using cyclic voltammetry, square wave voltammetry, and controlled potential electrolysis. Compounds B and a number of C complexes exhibit one Rulll/Rull reduction, followed, at a sufficiently long time scale, by metal dechlorination on solvolysis. The redox potential values in organic media agree with those predicted by Lever's parametrization method, and the yet unknown EL parameters were estimated for 1 (EL = 0.06 V), 3 (EL = 0.10 V), 4 (EL = 0.17 V), and 5 (EL = 0.18 V). The EL values for the azole ligands 1–8 correlate linearly with their basicity (pKa value of the corresponding azolium acid H2L+). In addition, a logarithmic dependence between the homogeneous rate constants for the reductively induced stepwise replacement of chloro ligands by solvent molecules and the Rulll/Rull redox potentials was observed. Lower E½ values (higher net electron donor character of the ligands) result in enhanced kinetic rate constants of solvolysis upon reduction. The effect of the net charge on the Rdlll/Rull redox potentials in water is tentatively explained by the application of the Born equation. In addition, the pH-dependent electrochemical behavior of trans-[RuCl2(1,2,4-triazole)4]Cl is discussed. [ABSTRACT FROM AUTHOR]

A series of luminescent transition metal complexes using the pH-sensitive ligand 5-carboxy-1,10-phenanthroline has been synthesized and characterized. The complexes, based on Ru(ll) and Re(l), show monotonic changes in both luminescent intensity and lifetime with pH values over the range 2 « pH « 9. The impact of various structural features on both the range of pH sensitivity and dynamic response was studied using both intensity and lifetime measurements. It was possible to predictably tune the pH sensitivity range over about 1.5 pKa units. While significant variation in the dynamic response range was observed, the correlation with structural features needs further study. [ABSTRACT FROM AUTHOR]

Reaction of PtRu5(CO)15(PBut3)(C), 3, with hydrogen at 97 °C yielded the new dihydride-containing cluster compound PtRu5(CO)14(PBut3)(μ-H)2(μ6-C), 5. Compound 5 was characterized crystallographically and was shown to contain an octahedral duster consisting of one platinum and five ruthenium atoms with a carbido ligand in the center. Two hydrido ligands bridge two oppositely positioned PtRu bonds. Compound 5 reacts with Pt(PBut3)2 to yield Pt2Ru5-(CO)14(PBut3)2(μ-H)2(μ6-C), 6, a Pt(PBut3) adduct of 5, by adding a Pt(PBut3) group as a bridge across one of the Ru-Ru bonds in the square base of the Ru5 portion of the cluster. Compound 6 is dynamically active on the NMR time scale by a mechanism that appears to involve a shifting of the Pt(PBut3) group from one Ru-Ru bond to another. Two new complexes, PtRu5(CO)13(PBut3)(μ-H)3(GePh3)(μ5-C), 7, and PtRu5(CO)13(PBut3)(μ-H)2(μ-GePh2)-(μ6-C), 8, were obtained from the reaction of 5 with HGePh3. The cluster of 7 has an open structure in which the Pt(PBut3) group bridges an edge of the square base of the square pyramidal Rut cluster. Compound 7 also has three bridging hydrido ligands and one terminal GePh3 ligand. When heated to 97 °C, 7 is slowly converted to 8 by cleavage of a phenyl group from the GePh3 ligand and elimination of benzene by its combination with one of the hydrido ligands. The PtRu5 metal cluster of 8 has a closed octahedral shape with a GePh2 ligand bridging one of the Ru-Ru bonds. Two tin-containing compounds, PtRu5(CO)13(PBut3)(μ-H)3(SnPh3)(μ5-C), 9, and PtRu5(CO)13- (PBut3)(μ-H)2(μ-SnPh2)(μ6-C), 10, which are analogous to 7 and 8 were obtained from the reaction of 5 with HSnPh3. [ABSTRACT FROM AUTHOR]

The syntheses, crystal structures, and magnetic properties of [Mn12O12(O2CC6F5)16(H2O)4] (2), (NMe4)[Mn12O12-(O2CC6F5)16(H2O)4] (3), and (NMe4)2 [Mn12O12(O2CC6F5)16(H2O)4] (4) are reported. Complex 2 displays quasi-reversible redox couples when examined by cyclic voltammetry in CH2Cl2: one-electron reductions are observed at 0.64 and 0.30 V vs ferrecene. The reaction of complex 2 with 1 and 2 equiv of NMe4I yields the one- and two-electron reduced analogues, 3 and 4, respectively. Complexes 2·3CH2Cl2, 3·4.5CH2Cl2·½H2O, and 4·6C7H8 crystallize in the triclinic P1, monoclinic P2/c, and monoclinic C2/c space groups, respectively. The molecular structures are all very similar, consisting of a central [MnIVO4] cubane surrounded by a nonplanar alternating ring of eight Mn and eight μ3-O2- ions. Peripheral ligation is provided by 16 bridging C6F5CO2- and 4 H2O ligands. Bond valence sum calculations establish that the added electrons in 3 and 4 are localized on former MnIII ions giving trapped-valence MnIV4MnIII7MnII and MnIV4MnIII6MnII2 anions, respectively. 19F NMR spectroscopy in CD2Cl2 shows retention of the solid-state structure upon dissolution and detrapping of the added electrons in 3 and 4 among the outer ring of Mn ions on the 19F NMR time scale. DC studies on dried microcrystalline samples of 2, 3, and 4·2.5C7H8 restrained in eicosane in the 1.80–10.0 K and 1–70 kG ranges were fit to give S = 10, D = -0.40 cm-1, g = 1.87, |D|/g = 0.21 cm-1 for 2, S = 19⁄2, D = −0.34 cm-1, g = 2.04, |D|/g = 0.17 cm-1 for 3, and S = 10, D = −0.29 cm-1, g = 2.05, |D|/g = 0.14 cm-1 for 4, where D is the axial zero-field splitting parameter. The clusters exhibit out-of-phase AC susceptibility signals (χM″) indicative of slow magnetization relaxation in the 6–8 K range for 2, 4–6 K range for 3, and 2–4 K range for 4; the shift to lower temperatures reflects the decreasing magnetic anisotropy upon successive reduction and, hence, the decreasing energy barrier to magnetization relaxation. Relaxation rate vs T data obtained from χ M″ vs AC oscillation frequency studies down to 1.8 K were combined with rate vs T data from DC magnetization decay vs time measurements at lower temperatures to generate an Arrhenius plot from which the effective barrier (Ueff) to magnetization reversal was obtained; the Ueff values are 59 K for 2, 49 and 21 K for the slower- and faster-relaxing species of 3, respectively, and 25 K for 4, Hysteresis loops obtained from single-crystal magnetization vs DC field scans are typical of single-molecule magnets with the coercivities increasing with decreasing T and increasing field sweep rate and containing steps caused by the quantum tunneling of magnetization (QTM). The step separations gave |D|/g values of 0.22 cm-1 for 2, 0.15 and 0.042 cm-1 for the slower- and faster-relaxing species of 3, and 0.15 cm-1 for 4. [ABSTRACT FROM AUTHOR]

Abstract: Solution and quench treatments are very important for the heat-treatable aluminum alloys because any change in these treatments will induce a trade-off in volume fraction between the constituents and precipitates and so will cause a change in the mechanical properties. In this paper, three types of solution + quench treatments were applied to two kinds of aluminum alloys, i.e., the Al–Cu–Mg alloy that contains disc/plate-shaped precipitates and the Al–Mg–Si alloy that contains rod/needle-shaped precipitates, to change the relative content between the constituents and the precipitates and to develop different coupling of the constituent and precipitates. The specimen treated with an enhanced solution or a stepped solution is found to exhibit a significant increase in yield strength, ductility, and fracture toughness. A multiscale model is presented to quantitatively estimate the coupled influence of the constituents and precipitates on the mechanical properties by combining with a strengthening model. The experimentally observed non-monotonic dependence of ductility on the trade-off in volume fraction between the constituents and precipitates is reasonably explained by using this multiscale model. In addition, the influence of stress triaxiality level on the ductility and fracture toughness is also calculated. All the calculations are in quite good agreement with the experimental results. [Copyright &y& Elsevier]

Studies the mechanistic aspects of C-H activation by Platinum complexes. Classification of C-H activation reactions; Discussion of the Shilov-type chemistry; Details of the catalytica system for catalytic methane functionalization.

Studies the treatment of substitution and rearrangement mechanisms of transition metal complexes with quantum chemical methods. Analysis of the accuracy and the reliability of quantum chemical computations on reaction mechanisms and the conclusions drawn; Discussion of the strengths and limitations of used chemical models and computational techniques; Emphasis on the role of the electron configuration of the transition metal ion on the steric course of the reaction and its mechanism.

Hydrazones derived from substituted benzoyl hydrazides and benzil a-monoxime [viz. benzil a-monoxime benzoylhydrazone (BMBH), benzil a-monoxime 4-chlorobenzoylhydrazone (BMPCBH), benzil a-monoxime 4-methoxybenzoylhydrazone (BMMBH), benzil a-monoxime 4-nitrobenzoylhydrazone (BMNBH) and benzil a-monoxime 2-chlorobenzoylhydrazone (BMOCBH)] have been synthesized and used in preparing the corresponding Cr(III), Mn(III), Fe(III) and Co(III) complexes. The ligands undergo deprotonation in ethanolic alkaline solution to form dinuclear complexes. The complexes are insoluble in common organic solvents, decompose above 300°C, and are spin-free octahedral. The complexes isolated were characterized by elemental analyses, IR, electronic, 1 H NMR spectra, conductance, thermal studies and magnetic susceptibility measurements. The bonding and probable structures of the complexes are discussed on the basis of the spectral and magnetic data. The ligands, as well as their complexes, show antifungal activity. [ABSTRACT FROM AUTHOR]

Several mono- or bi-nuclear nickel, copper, and zinc complexes of some multidentate ligands containing a pyridine ring have been synthesized and characterized by elemental analyses, molar conductivity, IR, UV, 1 H NMR and TG-DTA. The deprotonation behavior upon coordination is discussed. [ABSTRACT FROM AUTHOR]

This paper describes the design of a series of luminescent rhenium(I) polypyridine biotin complexes containing different spacer-arms, [Re(N-N)(CO)3(py-4-CH2-NH-biotin)](PF6) (py-4-CH2-NH-biotin = 4-(biotinamidomethyl)pyridine; N-N = 1,10-phenanthroline, phen (la), 3,4,7,8-tetramethyl-1 ,10-phenanthroline, Me4-phen (2a), 2,9-dimethyl-4,7-diphenyl-1 ,10-phenanthroline, Me2-Ph2-phen (3a), dipyrido[3,2-f.2',3'-h]quinoxaline, dpq (4a)), [Re(N-N)(CO)3(py3-CO-NH-en-NH-biotin)](PF6) (py-3-CO-NH-en-NH-biotin = 3-(N-((2-biotinamido)ethyl)amido)pyridine; N-N = phen (lb), Me4-phen (2b), Me2-Ph2-phen (3b), dpq (4b)), and [Re(N-N)(CO)3(py-4-CH2-NH-cap-NH-biotin)](PF6) (py-4-CH2-NH-cap-NH-biotin = 4-(N-((6-biotinamido)hexanoyl)aminomethyl)pyridine; N-N = phen (1c), Me4-phen (2c), Me2-Ph2-phen (3c), dpq (4c)). Upon irradiation, all of the rhenium(I)-biotin complexes exhibited intense and long-lived triplet metal-to-ligand charge-transfer (³MLCT) (dπ(Re) → π*(diimine)) emission in fluid solutions at 298 K. The interactions of these biotin-containing complexes with avidin have been studied by 4'-hydroxyazobenzene-2-carboxylic acid (HABA) assays, emission titrations, and competitive association and dissociation assays. On the basis of the results of these experiments, homogeneous assays for biotin and avidin have been designed. [ABSTRACT FROM AUTHOR]

A series of complexes, [M(bpy)(SAr)2] (M= platinum(II) or palladium(II), bpy = 2,2'-bipyridine, SAr = 2- or 4-(acylamino)benzenethiolate, or 2-(alkylcarbamoyl)benzenethiolate), were synthesized and characterized on the basis of ¹H NMR, IR, and electrochemical properties. The structures of [Pt(bpy)(S-2-Ph3CCONHC6H4)2] (1) and [Pt(bpy)(S-2-t-BuNHCOC6H4)2] (3) were determined by X-ray analysis. The complexes have intramolecular NH…S hydrogen bonds between the amide NH group and the sulfur atom. A weak NH…S hydrogen bond in these complexes and [Pd(bpy)(S-2-Ph3CCONHC6H4)22] (4) is detected from the ¹H NMR spectra and the IR spectra in chloroform and in the solid state. [Pt(bpy)(S-2-Ph3CCONHC6H4)2] (1) exhibits a remarkably high-energy-shifted lowest-energy band in UV-visible spectra and has a positively shifted oxidation potential. The blue-shift of 42 nm and the positive shift of +0.24 V, as compared to those of [Pt(bpy)(SC6H5)2], are due to the effect of the NH…S hydrogen bond. [ABSTRACT FROM AUTHOR]

An H2L Schiff-base ligand that was obtained from the monocondensation of diaminomaleonitrile and 4-(diethylamino)salicylaldehyde is reported together with four related nickel(II) complexes formulated as [Ni(L)(L')] (L' = MePhCHNH2, iPrNH2, Py, and PPh3). Crystal structures have been solved for H2L, [Ni(L)(MePhCHNH2)], and [Ni(L)(iPrNH2)]. Surprisingly, the complexation process leads to the formation of a rather unusual nickel amido (-NH-NiII) bond by deprotonation of the primary amine of H2L. A reduction of the quadratic hyperpolarizability β) from 38 x 1030 to 17.5 x 1030 cm5 esu-1 is evidenced on H2L upon metal complexation by the electric-field-induced second-harmonic (EFISH) technique. Qualitative ZINDO/SCI quantum chemical calculations indicate that, in [Ni(L)(MePhCHNH2)], the β orientation strongly depends on the laser wavelength. In particular, a β rotation strictly equal to 90° could be obtained with 1.022 μm incident light on passing from [Ni(L)(MePhCHNH2] to a hypothetical [Ni(HL)(MePhCHNH2]+ protonated complex, thus raising the possibility for a new type of molecular switch. [ABSTRACT FROM AUTHOR]

Five platinum(II) 1,4,7-trithiacyclononane (ttcn) complexes with bidentate-substituted 2,2'-bipyridine ligands have been prepared and structurally characterized: [Pt(bpy)(ttcn)](PF6)2 (bpy = 2,2'-bipyridine), triclinic, P&macr1;, a = 10.2529(3) &ARing;, b = 10.7791(3) &ARing;, c = 10.7867(3) &ARing;, α = 83.886(1)°, β = 87.565(1)°, γ = 84.901(1), V = 1179.99(6) ų, Z= 2; [Pt(4,4'-dmbpy)(ttcn)](PF6)2·CH3?CN·H2O(4,4'-dmbpy = 4,4'-dimethyl-2,2'-bipyridine), triclinic, P&1macr;, a = 10.1895(3) Å, b = 11.8566(4) Å, c = 13.1004(4) Å, α = 77.345(1)°, β = 79.967(1)°,γ = 72.341(1)°, V = 1461.56(8) ų, Z = 2; [Pt(5,5'-dmbpy)(ttcn)](PF6)2 (5,5'-dmbpy -- 5,5'-dimethyl-2,2'-bipyridine), triclinic, P&macr1;,a -10.6397(4) Å, b = 10.8449(4) Å, c = 11.2621(4) Å, α = 90.035(1)°, β = 98.061(1)°, γ = 91.283(1)°, V = 1286.32(8) ų, Z = 2; [Pt(dbbpy)(ttcn)](PF6)2·CH3NO2 (dbbpy -- 4,4'-di-tert-butyl-2,2'-bipyridine), triclinic, P&1macr;, a = 11.5422(7)Å, b = 11.6100(7) Å, c = 13.6052(9) Å, α = 85.902(1)°, β = 89.675(1)°, γ, = 74.942(1)°, V = 1755.90(19) ų, Z = 2; and [Pt(dffmbpy)(ttcn)](PF6)2·CH3CN (dtfmbpy = 5,5'-di-trifluoromethyl-2,2'-bipyridine): monoclinic, P21/c, a = 13.1187(9)Å, b = 20.9031(15) Å, c = 11.3815(8) Å, β = 105.789(2)°, V= 3003.3(4) ų, Z = 4. For each salt, the platinum(II) center of the cation is bonded to two nitrogen atoms of the chelating diimine and two sulfur atoms of the thioether macrocycle. The third sulfur atom of ttcn forms a long apical interaction with the metal center (2.84-2.97 Å), resulting in a flattened square pyramid structure. An examination of these and 17 other structures of platinum(II) ttcn complexes reveals a correlation between the apical Pt…S distance and the donor properties of the ancillary ligands, suggesting a means for using variations in ligand electronic properties to tune molecular structure. The room-temperature absorption spectra in acetonitrile solution show a broad and comparatively low-energy MLCT band maximizing near ∼390 nm for the bpy and dialkyl-substituted bipyridyl derivatives. The maximum is dramatically red-shifted to 460 nm in the spectrum of the dtfmbpy complex as a result of the electron-withdrawing properties of the -CF3 groups. The 3:1 EtOH/MeOH 77 K glassy solution emission spectra exhibit low-energy emission bands (λmax, 570-645 nm), tentatively assigned as originating from a lowest, predominantly spin-forbidden MLCT excited state that is stabilized by apical Pt…S interactions. [ABSTRACT FROM AUTHOR]

A theoretical study of the electronic structure, bonding, and properties of unligated and ligated manganeseII porphyrins and phthalocyanines has been carried out "in detail" using a density functional theory (DFT) method. While manganese tetraphenylporphine (MnTPP) in the crystal is high spin (S = 5/2) with the MnII atom out of the porphyrin plane, the present calculations find that the free manganese porphine (MnP) molecule has no obvious tendency to distort from planarity even in the high-spin state. The ground state of the planar structure is found to be intermediate spin (S= 3/2). Manganese phthalocyanine (MnPc) is calculated to have a 4E9 ground state, in agreement with the more recent magnetic circular dichroism (MCD) and UV-vis measurements of the molecule in an argon matrix but different from the early magnetic measurements of solid MnPc. The effect of the crystal structure on the electronic state of MnPc is examined by the calculations of a model system. For the six-coordinate adducts with two pyridine (py) ligands, the strong-field axial ligands raise the energy of the Mn dz²-orbital, thereby making the MnII ion low spin (S = ½). The recent assignment of MnPc(py)2 as an intermediate-spin state proves to be incorrect. Some issues involved in the reduced products have also been clarified. Five-coordinate MnP(py) and MnPc(py) complexes are high spin and intermediate spin, respectively. [ABSTRACT FROM AUTHOR]

Two novel three-dimensional lanthanum coordination polymers have been prepared with the phosphonic acid H2O3-PCH2N(C2H4)2NCH2PO3H2 (LH4). La2(LH2)2(LH4)Cl2 (I) and La2(LH2)2(LH3)Cl (11) arise from similar hydrothermal reactions but differing sources of La. A one-dimensional "lanthanum-phosphate" chain, comprising corner-linked LaO7 and PO3C polyhedra, forms the basis for the two different structures. The two structures differ in the mode of connectivity of the inorganic chains via the phosphonate groups. Both materials include extraframework chloride ions, the different amounts of which apparently direct the polytypic structures. In II, the chloride ions are incorporated in a noncentrosymmetric manner leading to a polar framework topology. [ABSTRACT FROM AUTHOR]

A series of copper(l) amidinates of the general type [(R'NC(R)NR")Cu]2 (R' and R" = n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl; R= methyl, n-butyl) have been synthesized and characterized. These compounds are planar dimers, bridged by nearly linear N-Cu-N bonds. Their properties (volatility, low melting point, high thermal stability, and self-limited surface reactivity) are well-suited for atomic layer deposition (ALD) of copper metal films that are pure, highly conductive, conformal, and strongly adherent to substrates. [ABSTRACT FROM AUTHOR]

One new conjugated symmetric fulvene ligand L1 and two new unsymmetric fulvene ligands L2 and L3 were synthesized. Five new supramolecular complexes, namely Ag2(L1)3(SO3CF3)3 (1) (1, monoclinic, P21/c;, a = 12.702(3) Å, b = 26.118(7) Å, c = 13.998(4) Å, β = 96.063(4)°, Z= 4), [Ag(L1)]ClO4 (2)(monoclinic, C2/c; a = 17.363(2) Å, b = 13.2794(18) Å, c = 13.4884(18) &ARing;, β = 100.292(2)°, Z= 8), [Ag(L1)(C6H6)SbF6]·0.5C6H6·H2O (3) (monoclinic, P21/c; a= 6.8839(11) Å, b = 20.242(3) Å, c = 18.934(3) Å, Β = 91.994(3)°, Z = 4), Ag(L2)(SO3CF3) (4) (triclinic, P&1macr; a = 8.629(3) Å, b = 10.915(3)Å, c = 11.178(3) Å, α = 100.978(4)°, β = 91.994(3)°, γ = 105.652(4)°, Z = 2), and Ag(L3)(H2O)(SO3CF3)(5)(triclinic, P&macr1;; a = 8.914(5) Å, b = 10.809(6) Å, c = 11.283(6) Å, α = 69.255(8)°, β = 87.163(9)°, γ = 84.993(8)°, Z = 2) were obtained through self-assembly based on these three new fulvene ligands in a benzene/toluene mixed-solvent system. Compounds 1-5 have been fully characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. The results indicate that the coordination chemistry of new fulvene ligands is versatile. They can adopt either cis- or trans-conformation to bind soft acid Ag(I) ion through not only the terminal -CN and furan functional groups but also the fulvene carbon atoms into organometallic coordination polymers or discrete complexes. In addition, the luminescent properties of L1-L3 and their Ag(I) complexes were investigated preliminarily in EtOH and solid state. [ABSTRACT FROM AUTHOR]

Reaction of [2.2]paracyclophane with silver(I) heptafluorobutyrate (AgC3F7CO2) has isolated three novel networks: [Ag4(pcp)(C3F7CO2)4]·pyrene (1), [Ag4(pcp)(C3F7CO2)4]·phen (phen = phenanthrene) (2), and [Ag4(pcp)(C3F7CO2)4]· fluorene (3), and an intercalation compound [Ag4(pcp)(3F7CO2)4]·2benzene (4). All the four complexes exhibit two-dimensional (2D) sheet structures in which AgC3F7CO2 form an infinite chain and pcp acts as linkage. 1, 2, and 3 show 2D flat sheets with cavities in which guest molecules are situated, whereas 4 exhibits 2D zigzag layers between which guest benzene molecules are intercalated. Pcp shows μ-di-η¹-η² coordination mode in 1, μ-tetraη¹ coordination mode in 2 and 3, and μ-tetra-η² coordination mode in 4. The reversible guest exchanges were observed between complex 1,2, or 3 and intercalation compound 4. It is unprecedented for metal-organic inclusion complexes that the guest exchange occurs where the guest is the solute molecule. Furthermore, 4 can release the guest, and the original framework was completely recovered after reincorporation of benzene. It should be noted that 4 can incorporate pyrene, phen, and fluorene to give 1, 2, and 3, respectively, after desorption. [ABSTRACT FROM AUTHOR]

CuInSe 2 and its alloys with Ga and/or S are among the most promising absorber materials for thin film solar cells. CuInSe 2 -based solar cells have shown long-term stability and the highest conversion efficiencies of all thin film solar cells, above 19%. Solar cells based on these materials are also very stable, thus allowing long operational lifetimes. The preparation of a thin film solar cell is a multistage process where every step affects the resulting cell performance and the production cost. CuInSe 2 and other Cu chalcopyrites can be prepared by a variety of methods, ranging from physical vapor deposition methods such as evaporation and sputtering to low-temperature liquid phase methods such as electrodeposition. The present review discusses first the concept and operation principle of thin film solar cells, as well as the most important thin film solar cell materials. Next, the properties of CuInSe 2 and related compounds, as well as features of solar cells made thereof are reviewed. The last part of the text deals with deposition methods used for the preparation of CuInSe 2 and Cu(In,Ga)Se 2 thin film absorbers and solar cells. Although the emphasis here is on absorber preparation methods, buffer and conducting oxide preparation are discussed as well. [ABSTRACT FROM AUTHOR]

The organic chemistry of 1,2,3-selenadiazoles has been explored to a greater extent due to the fact that the chemistry of 1,2,3-selenadiazoles mostly is driven by its facile decomposition via elimination of a nitrogen molecule and formation of selenaketocarben and/or its dimerization to 1,4-diselenin. The reactions of 1,2,3-selenadiazoles directly with various transition metal compounds have resulted in unique organo-selenium transition metal complexes. However, the materials chemistry of 1,2,3-selenadiazoles has not appeared in literature prior to the first publication on the subject from our laboratory in 2003. To, the best of our knowledge, no research group is engaged in such an activity. We, have exclusively explored the potential of 1,2,3-selenadiazoles for their effective utilization in synthesis of semiconductor nano particles or nano powder and in this lecture, the results and methodology for the same would be discussed. [ABSTRACT FROM AUTHOR]

The Co-Na heterobinuclear polymer complex based on Salen Schiff base and crown ether have been prepared by a method of interfacial polymerization without the presence of a phase transfer catalyst. The catalytic behavior of the Co-Na heterobinuclear polymer complex in aerobic oxidation of cyclohexene has been studied. [ABSTRACT FROM AUTHOR]

A novel compound formed by copper(II) and picolinic acid of formula [Cu(PCA) 2 (H 2 O) 2 ] (PCA = picolinate) has been synthesized. The complex crystallizes in the monoclinic space group P 2 1 / c with a = 5.4479(11), b = 10.910(2), c = 10.396(2) Å, β = 98.22(3)° and Z = 2. X-Ray analysis reveals that the Cu(II) ion lies in the usual distorted octahedral environment; two nitrogen atoms and two oxygen atoms from the PCA form the basal plane and two oxygen atoms from coordinated water molecules occupy the axial position. [Cu(PCA) 2 (H 2 O) 2 ] units are connected in a three-dimensional structure by intermolecular hydrogen bonds. [ABSTRACT FROM AUTHOR]

A new zincophosphate [H3N(CH2)2NH3]0.5Zn (HPO4)Cl, was obtained at room temperature from a starting mixture of ZnCl2, H3PO4, H2O, and ethylene-diamine. Its unit cell is tricline P-1 (No. 2) with parameters a = 7.709(2) Å, b = 8.479(2) Å c = 5.175(2) Å, α = 104.99(3), β = 107.41(4), γ = 87.34(2), Z = 2, and V = 311.6(2) ų. Its structure is resolved to R = 0.024, Rw = 0.037. The backbone of the title compound is a linear heteroanion built by PO4 and ZnO3Cl tetrahedra assembled to farm four member rings themselves interconnected by sharing common oxygen atoms. Hydrogen bonds O--H…O established between these chains connect them as to build infinite planes. The organic entities, located between these planes form the 3D cohesion through N--H…O or N--H…Cl hydrogen bonds. [ABSTRACT FROM AUTHOR]