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The activation of metal-oxo species with Lewis acids is of current interest.

N-Dealkylation of amines by metal oxo intermediates (M Created by potrace 1.16, written by Peter Selinger 2001-2019 O) is related to drug detoxification and DNA repair in biological systems. In this study, we report the first example of N-dealkylation of various alkylamines by a luminescent osmium(vi) nitrido complex induced by visible light., The visible light-induced N-dealkylation of various alkylamines by a luminescent osmium(vi) nitrido complex has been investigated. We provide definitive evidence that these reactions occur via an ET/PT mechanism.

Metal oxo (M Created by potrace 1.16, written by Peter Selinger 2001-2019 O) complexes are common oxidants in chemical and biological systems. The use of Lewis acids to activate metal oxo species has attracted great interest in recent years, especially after the discovery of the CaMn4O5 cluster in the oxygen-evolving centre of photosystem II. Strong Lewis acids such as Sc3+ and BF3, as well as strong Brønsted acids such as H2SO4 and CF3SO3H, are commonly used to activate metal oxo species. In this work, we demonstrate that relatively weak Lewis acids such as Ca2+ and other group 2 metal ions, as well as weak Brønsted acids such as CH3CO2H, can readily activate the stable RuO4− complex towards the oxidation of alkanes. Notably, the use of Ca2+ and CH3CO2H together produces a remarkable cooperative effect on RuO4−, resulting in a much more efficient oxidant. DFT calculations show that Ca2+ and CH3CO2H can bind to two oxo ligands to form a chelate ring. This results in substantial lowering of the barrier for hydrogen atom abstraction from cyclohexane., Combining a weak Lewis acid and weak Brønsted acid produces strong cooperative effects for activating metal oxo species towards alkane oxidation.

Here, we report the use of an amphiphilic Pt(II) complex, K[Pt{(O3SCH2CH2CH2)2bzimpy}Cl] (PtB), as a model to elucidate the key role of Pt···Pt interactions in directing self-assembly by combining temperature-dependent ultraviolet-visible (UV-Vis) spectroscopy, stopped-flow kinetic experiments, quantum mechanics (QM) calculations, and molecular dynamics (MD) simulations. Interestingly, we found that the self-assembly mechanism of PtB in aqueous solution follows a nucleation-free isodesmic model, as revealed by the temperature-dependent UV-Vis experiments. In contrast, a cooperative growth is found for the self-assembly of PtB in acetone–water (7:1, vol/vol) solution, which is further verified by the stopped-flow experiments, which clearly indicates the existence of a nucleation phase in the acetone–water (7:1, vol/vol) solution. To reveal the underlying reasons and driving forces for these self-assembly processes, we performed QM calculations and show that the Pt···Pt interactions arising from the interaction between the pz and dz2 orbitals play a crucial role in determining the formation of ordered self-assembled structures. In subsequent oligomer MD simulations, we demonstrate that this directional Pt···Pt interaction can indeed facilitate the formation of linear structures packed in a helix-like fashion. Our results suggest that the self-assembly of PtB in acetone–water (7:1, vol/vol) solution is predominantly driven by the directional noncovalent Pt···Pt interaction, leading to the cooperative growth and the formation of fibrous nanostructures. On the contrary, the self-assembly in aqueous solution forms spherical nanostructures of PtB, which is primarily due to the predominant contribution from the less directional hydrophobic interactions over the directional Pt···Pt and π−π interactions that result in an isodesmic growth.

The development of efficient and cost-effective electrocatalysts for the hydrogen evolution reaction (HER) is of intense interest because H2 is one of the most promising renewable energy sources. Herein, we report a highly efficient and stable HER electrocatalyst composed of ruthenium nanoparticles embedded in nitrogen-doped carbon (NC), which is synthesized via a simple thermolysis process using a ruthenium complex as metal precusor and using ethylenediaminetetraacetic acid tetrasodium (Na4EDTA) salt as ligand and carbon source. It is found that the amount of Na4EDTA employed plays an important role in achieving sutiable and uniform Ru nanoparticles. The resulting Ru@NC(1 : 5) was found to exhibit excellent HER activity and robust stability in alkaline media (1.0 M KOH) with a low overpotential at 10 mA cm−2 (29 mV), small Tafel slope (27 mV per decade) and a high turnover frequency (TOF) of 0.96 s−1 at an overpotential of 50 mV, which are comparable to the state-of-the-art commercial Pt/C catalyst. Based on the characterization of the samples and the electrochemical measurements, this high performance of Ru@NC(1 : 5) is ascribed to its smallest particle size (ca. 2.1 nm diameter), large active site density and the high electrochemical conductivity by the N-doped carbon support. In addition, Ru@NC(1 : 5) also works well in acidic media (0.5 M H2SO4) indicating it is a pH-universal catalyst.

The profile of 11 trace metals in two commonly used biomonitors (the native oyster Crassostrea palmula and mussel Mytella strigata) from Estero de Urias lagoon, Gulf of California, were studied for six months, covering both dry and wet seasons. Metal concentrations in these two bivalves were compared with concentrations accumulated by Artificial Mussels (AMs) deployed alongside during the same period. Significant temporal variations in Cd, Cr and Mn were observed in both bivalve species and AMs. Temporal changes were observed for Fe in both bivalve species, Pb in oyster only and Cu in both AMs and oysters, revealing seasonal changes in inputs and/or chemical forms of these metals in the lagoon. Significant correlations for Cd, Cr and Cu were found in mussels and oysters, but their Co, Fe, Mn and Zn profiles were very different, despite these two species being taxonomically closely related and often used as biomonitors for metals. Interestingly, Hg and U were detected in AMs but not in oysters and mussels. The difference in metal profile in oysters, mussels and AMs revealed in the present study clearly showed that different biomonitors and AM take up metals differentially from the same environment, and metal profile in a single biomonitor or AM alone therefore, cannot provide a good estimate on metal concentrations in the ambient environment. As such, different biomonitors and AM should be used in metal monitoring, in order to provide a comprehensive picture on metal levels in aquatic ecosystems. Concentrations of Ni and Pb in oysters, and Cr, Fe and Mn in mussels were among the highest reported in coastal waters worldwide. Concentrations of Pb in oysters exceeded legal limits set for bivalve mollusks in EU. Concentrations of Cr in mussels and oysters exceeded or were very close to, respectively, the legal limit for fish, crab-meat, oysters, prawns, and shrimps in Hong Kong. The results indicate a potential public health risk on human consumption of oysters and mussels commonly harvested from the Estero de Urias lagoon, and corresponding pollution control measures are deemed necessary.

International audience; Achieving visible-light-driven carbon dioxide reduction with high selectivity control and durability while using only earth abundant elements requires new strategies. Hybrid catalytic material was prepared upon covalent grafting a Co–quaterpyridine molecular complex to semiconductive mesoporous graphitic carbon nitride (mpg-C3N4) through an amide linkage. The molecular material was characterized by various spectroscopic techniques, including XPS, IR, and impedance spectroscopy. It proved to be a selective catalyst for CO production in acetonitrile using a solar simulator with a high 98% selectivity, while being remarkably robust since no degradation was observed after 4 days of irradiation (ca. 500 catalytic cycles). This unique combination of a selective molecular catalyst with a simple and robust semiconductive material opens new pathways for CO2 catalytic light-driven reduction.

Hydrogen is considered as the promising renewable resources in future C-free systems, but more efficient and scalable synthesis is required to enable its widespread deployment. Here, in-situ generated hierarchical NiS-PBA/CNT hybrid has been fabricated which combined the high conductivity and electrocatalytic activity together. Through study the electronic structure, it was found that the electron transfer among metal atom enable higher activity. The optimized NiS-PBA/CNT delivers an ultralow overpotential of 253 mV @ 20 mA cm−2, a small Tafel slope of 49.8 mV dec-1, and can work steadily for more than 40 h with a Faradic efficiency of 95.5%. Density functional theory calculations based on the NiS-PBA, NiS and PBA model reveal that the enhanced catalytic activities of NiS-PBA is mainly manifested in its lower free energy of rate-determining step (the oxidation of *OH to *O) and higher electrical conductivity. This work provides a novel partial sulfidation strategy for PBA to significantly boost catalytic performance. And the microwave-assisted solvothermal reaction offers a novel mild implementation toward in situ heterogeneous doping for carbon matrix.

The development of metal-based anticancer drugs is of considerable interest and significance in inorganic medicine. In contrast to noble metal-based small molecules, the anticancer property of earth abundant metal-based small molecules is much less explored which are usually essential trace element for the human body. Among earth abundant metals, chromium (Cr) in the +3 valent is an essential trace element for the human body to low down the blood lipids and maintain the blood sugar; on the other hand, Cr(VI) are known to be highly toxic due to their oxidation power. To design stable high-valent Cr small molecules to construct Cr(high-valent)-Cr(III) in-situ transition system to achieve low-toxic and highly efficient anti-cancer therapy is a very desirable approach. Herein we report the Cr(V)-Cr(III) in-situ transition system promotes ROS generation to achieve efficient cancer therapy in vivo and in vitro. To the best of our knowledge, these Cr-based small molecules are the first stable Cr(V) compounds with potent anticancer efficacy, especially towards malignant cancers.

Using innovative artificial mussels technology for the first time, this study detected eight heavy metals (Cd, Cu, Fe, Mn, Ni, Pb, U, Zn) on a regular basis in waterways across Bangladesh (Chittagong, Dhaka and Khulna). Three heavy metals, viz. Co, Cr and Hg were always below the instrumental detection levels in all the sites during the study period. Through this study, seven metal pollution "hot spots" have been identified, of which, five "hot spots" (Cu, Fe, Mn, Ni, Pb) were located in the Buriganga River, close to the capital Dhaka. Based on this study, the Buriganga River can be classified as the most polluted waterway in Bangladesh compared to waterways monitored in Khulna and Chittagong. Direct effluents discharged from tanneries, textiles are, most likely, reasons for elevated concentrations of heavy metals in the Buriganga River. In other areas (Khulna), agriculture and fish farming effluents may have caused higher Cu, U and Zn in the Bhairab and Rupsa Rivers, whereas untreated industrial discharge and ship breaking activities can be linked to elevated Cd in the coastal sites (Chittagong). Metal pollution may cause significant impacts on water quality (irrigation, drinking), aquatic biodiversity (lethal and sub-lethal effects), food contamination/food security (bioaccumulation of metals in crops and seafood), human health (diseases) and livelihoods of people associated with wetlands.

The search for a highly active nitrido complex that can transfer its nitrogen atom to inert organic molecules remains a challenge to chemists. In this regard, the use of solar energy to generate a reactive nitrido species is an appealing strategy to solve this problem. Here we report the design of a strongly luminescent osmium(VI) nitrido compound, [OsVI(N)(NO2-L)(CN)3]− (NO2-OsN) with emission quantum yield (Φ) and life time (τ) of 3.0% and 0.48 μs, respectively in dichloromethane solution. Upon irradiation with visible light, this complex readily activates the aliphatic C-H bonds of various hydrocarbons, including alkanes. The excited state of NO2-OsN can undergo ring-nitrogenation of arenes, including benzene. Photophysical and computational studies suggest that the excited state of NO2-OsN arises from O^N ligand to Os ≡ N charge transfer transitions, and as a result it possesses [Os = N•] nitridyl character and is highly electrophilic.

Advanced oxidation processes based on activation of peroxydisulfate (PDS) typically require energy or chemical input, for which ultraviolet light and metal catalyst are commonly adopted. However, the sluggish reaction kinetics due to insufficient catalyst redox cycling and limited solar energy utilization remain a key challenge to be addressed. Here, we report a visible light-driven Ru(bpy)32+/PDS system that allows for highly-efficient and sustained pollutant degradation, at efficiencies far exceeding the existing PDS-based reaction systems. The degradation rate of Rhodamine B (RhB) was 40-fold higher than that achievable by the state-of-the-art Fe2+/PDS system. The Ru(bpy)33+ reduction was closely coupled with the pollutant oxidation, enabling an efficient Ru(bpy)32+/Ru(bpy)33+ cycling and RhB degradation via non-radical dominated pathway in the Ru(bpy)32+/PDS/vis system. The high activity of the catalyst towards multiple antibiotics and its high stability and robustness over a wide pH range and in the presence of various environmental anions were also demonstrated. This work provides solid evidence to support a direct oxidation of pollutant by high-valent metal complex, and may inspire new development of solar-responsive catalysts for efficient, sustainable advanced oxidation processes.

International audience; The electrochemical catalytic reduction of CO2 into CO could be achieved with excellent selectivity and rate in acetonitrile in the presence of phenol with cobalt 2,2′:6′,2″:6″,2‴-quaterpyridine complex [CoII(qpy)(H2O)2]2+ (Co) acting as a molecular catalyst. Upon using cyclic voltammetry at low and high scan rate (up to 500 V/s) two catalytic pathways have been identified. At a low concentration of phenol (

0000-0002-2139-7655 WOS: 000442365500005 Using the native mussel Unio crassus and artificial mussels (AMs), profiles of 11 metals (Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, U, Zn) were determined and compared in winter and summer along a pollution gradient in Sarcay Stream, Turkey. Principal components analysis and correlation analysis showed that metal profiles in the native mussels and AMs were different. Concentrations of most metals were significantly higher in the native mussels compared with AMs, suggesting that metals in Sarcay Stream predominantly existed in suspended particulates and food compartments, rather than in dissolved form. Although U was not readily accumulated by the native mussels, it could be taken up by AMs. Overall, the results suggest that the use of native mussels and AMs in water quality monitoring can provide complementary information and a better estimate and coverage of different metal species and forms in aquatic environments. Scientific Research Project Office of Mugla Sitki Kocman University [13/72]; Education University of Hong Kong [R3721] This work was supported by the Scientific Research Project Office of Mugla Sitki Kocman University (Project number: 13/72) awarded to Tuncer Genc, and a start-up grant from the Education University of Hong Kong (R3721) awarded to Rudolf Wu. Data in the present study were extracted from the Ph.D. thesis of Tuncer O. Genc. The authors thank Jonathan C. H. Yip, Kung-Ming Leung and Jenny C. Y. Ng for their help with manuscript preparation.

Bismuth (Bi) and silver (Ag) co-doped KBa 2 Ta 5 O 15 nanocomposites were fabricated and modified with Ag nanoparticles (NPs) to form a novel visible light-driven plasmonic photocatalyst (Ag@Ag-Bi-KBT) for photodegradation applications. X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectroscopy and high resolution transmission electron microscopy have been conducted to investigate the structural, morphological, electronic and optical characteristics of the photocatalysts. The photocatalytic activity of the Ag@Ag-Bi-KBT nanocomposites has been systematically evaluated by photodegradation of four organic contaminants (rhodamine B, orange G, methyl orange and bisphenol A) in aqueous solution under visible light irradiation ( λ > 420 nm). The degradation mechanism over Ag@Ag-Bi-KBT is discussed. Ag@Ag-Bi-KBT exhibits high photocatalytic activity under visible light irradiation, mainly due to increased reaction sites and strong visible light absorption by Bi- and Ag-co-doping, as well as to the optimized localized surface plasmon resonance behavior and efficient charge separation resulting from Ag NPs.

Zero-Valent Iron nanoparticles (nZVI) have been extensively applied for the reduction of various recalcitrant organic contaminants, but their reactivity usually declines over time due to the formation of passive iron oxides. In this study we observed a sustained reactivity of nZVI for the dechlorination of carbon tetrachloride (CT) in water during several consecutive reaction cycles. The dechlorination rate constants increased substantially in Cycle 2, then remained at a high level over several consecutive cycles, and ultimately declined in Cycle 7. In the entire process, the solution pH increased only slightly from 7.0 to 7.8, which was different from other unbuffered nZVI reduction systems reported before. Characterization of the particle surface morphology and composition revealed an important role of Fe oxyhydroxide formation in self-buffering the solution pH and sustaining a high nZVI reactivity. Our study provides new knowledge on the nZVI dechlorination process and may offer implications for extending the lifetime of nZVI in wastewater treatment and environmental remediation applications.

Shape and facet engineering of crystals at the nanoscale level has become an important strategy for optimizing the reactivity of catalysts in heterogeneous catalysis. We report here the fabrication of four morphology-controlled α-Fe2O3 catalysts with exposed specific facets by a solvothermal method. The effects of morphology and exposed facets of these α-Fe2O3 nanocrystals towards visible light-driven water oxidation have been investigated. Water oxidation was carried out using two catalytic systems, Fe2O3/[Ru(bpy)3]2+/S2O82− and Fe2O3/AgNO3, at λ > 420 nm. The α-Fe2O3 nanocubes with exposed {012} facets exhibit much higher catalytic activity than α-Fe2O3 nanoflakes with {001} facets. This work demonstrates that the catalytic activity of α-Fe2O3 nanocrystals in photocatalytic water oxidation is morphology-dependent and the reactivity trend can be rationalized in terms of exposed facets in the order of {012} > {001}. This study provides a new approach to the design of highly effective water oxidation catalysts by engineering the morphology and the exposed facets of crystals.

A cancer-cell selective bis(guanidine)-ruthenium(iii) complex induces apoptosis, whereas its amidine analogue effectively kills cancer cells through paraptosis pathways., Two novel series of (salen)ruthenium(iii) complexes bearing guanidine and amidine axial ligands were synthesized, characterized, and evaluated for anticancer activity. In vitro cytotoxicity tests demonstrate that these complexes are cytotoxic against various cancer cell lines and the leading complexes have remarkable cancer-cell selectivity. A detailed study of the guanidine complex 7 and the amidine complex 13 reveals two distinguished modes of action. Complex 7 weakly binds to DNA and induces DNA damage, cell cycle arrest, and typical apoptosis pathways in MCF-7 cells. In contrast, complex 13 induces paraptosis-like cell death hallmarked by massive vacuole formation, mitochondrial swelling, and ER stress, resulting in significant cytotoxicity against human breast cancer cells. Our results provide an extraordinary example of tuning the mechanism of action of (salen)ruthenium(iii) anticancer complexes by modifying the structure of the axial ligands.

A new silver tantalate material has been synthezied by heating a mixture of AgNO3, Ta2O5 and KCl at 850 °C for 20 h. XRD, EDX, XPS, SEM, TEM and HRTEM show that the material consists of Ag1.4K0.6Ta4O11 nanoplates, with Ag nanoparticles present on the surface, which is consistent with enhanced absorption of the material in the visible region. Addition of 0.5–5 mol% of La2O3 in the preparation of Ag1.4K0.6Ta4O11 results in significant change in the morphology from nanoplates to nanoplates/nanowire composites. The photocatalytic activities of Ag1.4K0.6Ta4O11 and La-Ag1.4K0.6Ta4O11 have been evaluated by degradation of the organic pollutants rhodamine B (RhB) and pentachlorophenol (PCP) in water under visible light (λ > 420 nm), as well as by photocatalytic reduction of water to H2 at λ > 390 nm. The photocatalytic activity of Ag1.4K0.6Ta4O11 is significantly enhanced by La-doping; the optimal La content is 1 mol% for degradation of organic substrates and 5 mol% for H2 evolution, with photocatalytic activity significantly higher than that of P25 TiO2. The enhancement of photocatalytic activity upon La doping is attributed to trapping of excited electrons by La3+, and the formation of nanowires which further promote charge separation.

The effects of KOH concentration (10–30 M) on the morphology of KNbO 3 produced from Nb 2 O 5 by hydrothermal synthesis have been investigated. High purity KNbO 3 nanocubes have been obtained using 30 M KOH at 200 °C. The KNbO 3 nanocubes can be readily doped with nitrogen by heating with urea at 425 °C without significant change in morphology. The band gap of KNbO 3 decreases from 3.13 to 2.76 eV as a result of N-doping, the surface area also increases substantially. The photocatalytic activity of the N-doped KNbO 3 nanocubes has been evaluated by photodegradation of four organic contaminants (rhodamine B, orange G, bisphenol A and pentachlorophenol) as well as water splitting under visible light irradiation. The results show that the photocatalytic activity of N-doped KNbO 3 is significantly higher than that of pure KNbO 3 nanocubes and Degussa TiO 2 P25 under visible light irradiation.

The “Artificial mussel” (AM), a novel passive sampling technology, was used for the first time in Australia in freshwater to monitor and assess the risk of trace metals (Cd, Cu, Hg, Pb, and Zn). AMs were deployed at 10 sites within the Goulburn–Murray Water catchments, Victoria, Australia during a dry year (2009–2010) and a wet year (2010–2011). Our results showed that the AMs accumulated all the five metals. Cd, Pb, Hg were detected during the wet year but below detection limits during the dry year. At some sites close to orchards, vine yards and farming areas, elevated levels of Cu were clearly evident during the dry year, while elevated levels of Zn were found during the wet year; the Cu indicates localized inputs from the agricultural application of copper fungicide. The impacts from old mines were significantly less compared ‘hot spots’. Our study demonstrated that climate variability (dry, wet years) can influence the metal inputs to waterways via different transport pathways. Using the AMs, we were able to identify various ‘hot spots’ of heavy metals, which may pose a potential risk to aquatic ecosystems (sub-lethal effects to fish) and public (via food chain metal bioaccumulation and biomagnification) in the Goulburn–Murray Water catchments. The State Protection Policy exempted artificial channels and drains from protection of beneficial use (including protection of aquatic ecosystems) and majority of sites (‘hot spots’) were located within artificial irrigation channels. Keywords: Artificial mussel (AM), Trace metals, Hot spots, Climate variability

A comprehensive study was carried out to assess metal contamination in five cities spanning from temperate to tropical environment along the coastal line of China with different hydrographical conditions. At each of the five cities, Artificial Mussels (AM) were deployed together with a native species of mussel at a control site and a polluted site. High levels of Cr, Cu and Hg were found in Qingdao, high level of Cd, Hg and Pb was found in Shanghai, and high level of Zn was found in Dalian. Furthermore, level of Cu contamination in all the five cities was consistently much higher than those reported in similar studies in other countries (e.g., Australia, Portugal, Scotland, Iceland, Korea, South Africa and Bangladesh). Levels of individual metal species in the AM showed a highly significant correlation with that in the native mussels (except for Zn in Mytilus edulis and Cd in Perna viridis), while no significant difference can be found between the regression relationships of metal in the AM and each of the two native mussel species. The results demonstrated that AM can provide a reliable time-integrated estimate of metal concentration in contrasting environments over large biogeographic areas and different hydrographic conditions, and overcome the shortcomings of monitoring metals in water, sediment and the use of biomonitors.

DNA sequences with guanine repeats can form G-quartets that adopt G-quadruplex structures in the presence of specific metal ions. Using circular dichroism (CD) and ultraviolet-visible (UV-Vis) spectroscopy, we determined the spectral characteristics and the overall conformation of a G-quadruplex of PS2.M with an oligonucleotide sequence, d(GTG(3)TAG(3)CG(3)TTG(2)). UV-melting curves demonstrate that the Pb(2+)-induced G-quadruplex formed unimolecularly and the highest melting temperature (T(m)) is 72°C. The analysis of the UV titration results reveals that the binding stoichiometry of Pb(2+) ions to PS2.M is two, suggesting that the Pb(2+) ions coordinate between adjacent G-quartets. Binding of ions to G-rich DNA is a complex multiple-pathway process, which is strongly affected by the type of the cations. Kinetic studies suggest that the Pb(2+)-induced folding of PS2.M to G-quadruplex probably proceeds through a three-step pathway involving two intermediates. Structural transition occurs after adding Pb(NO(3))(2) to the Na(+)- or K(+)-induced G-quadruplexes, which may be attributed to the replacement of Na(+) or K(+) by Pb(2+) ions and the generation of a more compact Pb(2+)-PS2.M structure. Comparison of the relaxation times shows that the Na(+)→Pb(2+) exchange is more facile than the K(+)→Pb(2+) exchange process, and the mechanisms for these processes are proposed.

Reaction of [Os(VI)(N)(L(1))(Cl)(OH(2))] (1) with CN(-) under various conditions affords (PPh(4))[Os(VI)(N)(L(1))(CN)(Cl)] (2), (PPh(4))(2)[Os(VI)(N)(L(2))(CN)(2)] (3), and a novel hydrogen cyanamido complex, (PPh(4))(2)[Os(III){N(H)CN}(L(3))(CN)(3)] (4). Compound 4 reacts readily with both electrophiles and nucleophiles. Protonation and methylation of 4 produce (PPh(4))[Os(III)(NCNH(2))(L(3))(CN)(3)] (5) and (PPh(4))[Os(III)(NCNMe(2))(L(3))(CN)(3)] (6), respectively. Nucleophilic addition of NH(3), ethylamine, and diethylamine readily occur at the C atom of the hydrogen cyanamide ligand of 4 to produce osmium guanidine complexes with the general formula [Os(III){N(H)C(NH(2))NR(1)R(2)}(L(3))(CN)(3)](-) , which have been isolated as PPh(4) salts (R(1) = R(2) = H (7); R(1) = H, R(2) = CH(2)CH(3) (8); R(1) = R(2) = CH(2)CH(3) (9)). The molecular structures of 1-5 and 7 and 8 have been determined by X-ray crystallography.

Nitrogen doped K2Nb4O11 (K2Nb4O11-N) has been prepared by solid state reaction between K2Nb4O11 and urea at 400 °C. K2Nb4O11-N has been characterized by XRD, SEM, XPS and UV/vis diffuse reflectance. The photodegradation of various organic pollutants in water by this material, including Orange G (OG), bisphenol A (BPA) and pentachlorophenol (PCP) have been studied at λ > 330 nm and >399 nm. The results show that the photocatalytic activity of K2Nb4O11-N at >399 nm is higher than those of K2Nb4O11 and Degussa TiO2 P25, indicating the activating effect of nitrogen doping. A mechanism for the photodegradation of organic substrates by K2Nb4O11-N is proposed.

The passive sampler called 'Artificial Mussel' (AM) developed by Wu et al. (2007) can provide a time-integrated estimate of metal concentrations in the marine environment, and offers a potential device to assess and compare metal concentration in different marine environments worldwide. The aim of this study was to compare metal accumulation on AM and natural mussel Mytilus galloprovincialis at three sites with different metal loads along the Portuguese coast for four months. M. galloprovincialis were placed in cages alongside AMs at each site. Samples were collected monthly and Cd, Cr, Cu, Pb, and Zn concentrations in whole soft tissues and AMs compared. For both Cu and Cd, the results were similar between AMs and natural mussels. Higher concentrations of Zn were observed in natural mussels, whereas the inverse was shown for Pb (about 10-fold higher). Our results showed that AMs are promising tools for assessing metal concentrations in marine environments. Hong Kong Research Grants Council - AoE/P-04/2004, The Centre of Marine and Environmental Research (Portugal) and Foundation of Science and Technology (FCT) (Portugal) info:eu-repo/semantics/publishedVersion

A series of osmium(VI) nitrido complexes containing pyridine-carboxylato ligands OsVI(N)(L)2X (L = pyridine-2carboxylate (1), 2-quinaldinate (2) and X = Cl (a), Br (1b and 2c) or CH3O (2b)) and [OsVI(N)(L)X3]− (L = pyridine-2,6-dicarboxylate (3) and X = Cl (a) or Br (b)) have been synthesised. Complexes 1 and 2 are electrophilic and react readily with various nucleophiles such as phosphine, sulfide and azide. Reaction of OsVI(N)(L)2X (1 and 2) with triphenylphosphine produces the osmium(IV) phosphiniminato complexes OsVI(NPPh3)(L)2X (4 and 5). The kinetics of nitrogen atom transfer from the complexes OsVI(N)(L)2Br (2c) (L = 2-quinaldinate) with triphenylphosphine have been studied in CH3CN at 25.0 °C by stopped-flow spectrophotometric method. The following rate law is obtained: −d[Os(VI)]/dt = k2[Os(VI)][PPh3]. OsVI(N)(L)2Cl (L = 2-quinaldinate) (2a) reacts also with [PPN](N3) to give an osmium(III) dichloro complex, trans-[PPN][OsIII(L)2Cl2] (6). Reaction of OsVI(N)(L)2Cl (L = 2-quinaldinate) (2a) with lithium sulfide produces an osmium(II) thionitrosyl complex OsII(NS)(L)2Cl (7). These complexes have been structurally characterised by X-ray crystallography.

Reaction of [Ru (VI)(N)(L (1))(MeOH)] (+) (L (1) = N, N'-bis(salicylidene)- o-cyclohexylenediamine dianion) with excess pyridine in CH 3CN produces [Ru (III)(L (1))(py) 2] (+) and N 2. The proposed mechanism involves initial equilibrium formation of [Ru (VI)(N)(L (1))(py)] (+), which undergoes rapid N...N coupling to produce [(py)(L (1))Ru (III) N N-Ru (III)(L (1))(py)] (2+); this is followed by pyridine substituion to give the final product. This ligand-induced N...N coupling of Ru (VI)N is utilized in the preparation of a series of new ruthenium(III) salen complexes, [Ru (III)(L)(X) 2] (+/-) (L = salen ligand; X = H 2O, 1-MeIm, py, Me 2SO, PhNH 2, ( t )BuNH 2, Cl (-) or CN (-)). The structures of [Ru (III)(L (1))(NH 2Ph) 2](PF 6) ( 6), K[Ru (III)(L (1))(CN) 2] ( 9), [Ru (III)(L (2))(NCCH 3) 2][Au (I)(CN) 2] ( 11) (L (2) = N, N'-bis(salicylidene)- o-phenylenediamine dianion) and [N ( n )Bu 4][Ru (III)(L (3))Cl 2] ( 12) (L (3) = N, N'-bis(salicylidene)ethylenediamine dianion) have been determined by X-ray crystallography.

The dimetallic complexes [{Ni(cyclen)}{Mn(N)(CN)4}·CH3OH]n (cyclen = 1,4,7,10-tetraazacyclododecane) (1), [{Cu(cyclen)}{Mn(N)(CN)4}]n (2), and [{Mn(5,5′-Me2salen)}2{Mn(N)(CN)4}·CH3OH]n [5,5′-Me2salen = N,N′-bis(5,5′-dimethylsalicylidene)-o-ethylenediimine] (3) have been synthesized and structurally characterized. Compounds 1 and 2 have one-dimensional chain structures, while compound 3 has a two-dimensional sheet-like network structure. Magnetic studies of 1 and 3 show that there is no significant magnetic coupling between the paramagnetic metal centers. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

A new polymer ligand exchanger (PLE) has been developed for the removal of phosphate in wastewater. This PLE, consisting of lanthanum(III) bound to chelex-100 resin, was prepared by passing LaCl 3 solution through a column of chelex-100. Uptake of phosphate from water by this La-chelex resin was investigated in the column mode. The La-chelex resin was able to remove phosphate efficiently from water, and the uptake of phosphate was not affected by the presence of large amounts of anions (0.1 M) such as chloride and sulfate. The La-chelex resin was also able to efficiently remove phosphate from seawater to −1 , and regenerated for reuse by removing the sorbed phosphate by eluting with 6 M HCl.

A new chemical sampling device, artificial mussel (AM), has been developed for monitoring metals in marine environments. This device consists of a polymer ligand suspended in artificial seawater within a Perspex tubing, and enclosed with semi-permeable gel at both ends. Laboratory and field experiments were carried out to examine the uptake of five metals (Cd, Cr, Cu, Pb and Zn) by the AM. Uptake of metals by AM was proportional to the exposure metal concentrations, and the AM was able to accumulate the ASV labile fractions of metals. Uptake and release of the metals of AM are similar to those of the mussel Perna viridis, but less affected by salinity and temperature. Field studies demonstrated that the AM can not only provide a time-integrated estimate of metals concentrations, but also allows comparisons of metal levels in different environments and geographical areas beyond the natural distribution limits of biomonitors.

Fragmentation of some electrospray-generated complex ions, [63CuII(amine)M]·2+, where M is an enkephalin derivative, produces the radical cation of the peptide, M·+. This ion has only been observed when M contains a tyrosyl or tryptophanyl residue plus a basic residue, typically arginyl or lysyl. A typical viable amine is diethylenetriamine. Collision-induced dissociation (CID) of the M·+ ion yields a prominent [M − 106]·+ product ion for tyrosine-containing peptides, and a prominent [M − 129]·+ ion for a tryptophan-containing peptide. These fragment ions are formed as a result of elimination of the tyrosyl and tryptophanyl side chains. Dissociation of these ions, in turn, produces second generation product ions, many of which are typically absent in the fragmentation of protonated peptide ions. Structures for some of these unusual ions are proposed.

Tandem mass spectrometry performed on a pool of 18 oligopeptides shows that the product ion spectra of argentinated peptides, the [b n + OH + Ag]+ ions and the [y n − H + Ag]+ ions bearing identical sequences are virtually identical. These observations suggest strongly that these ions have identical structures in the gas phase. The structures of argentinated glycine, glycylglycine, and glycylglycylglycine were calculated using density functional theory (DFT) at the B3LYP/DZVP level of theory; they were independently confirmed using HF/ LANL2DZ. For argentinated glycylglycylglycine, the most stable structure is one in which Ag+ is tetracoordinate and attached to the amino nitrogen and the three carbonyl oxygen atoms. Mechanisms are proposed for the fragmentation of this structure to the [b2 + OH + Ag]+ and the [y2 − H + Ag]+ ions that are consistent with all experimental observations and known calculated structures and energetics. The structures of the [b2 − H + Ag]+ and the [a2 − H + Ag]+ ions of glycylglycylglycine were also calculated using DFT. These results confirm earlier suggestions that the [b2 − H + Ag]+ ion is an argentinated oxazolone and the [a2 − H + Ag]+ an argentinated immonium ion.

Growth rate of individually tagged dogwhelks Nucella lapillus (L.) was measured in free-living individuals at 3 sites of differing heavy metal contamination in the Firth of Clyde, west Scotland. Condition index (CI), concentrations of metals (Cd, Cu, Pb and Zn), metallothionein (MT), RNA (the RNA/protein ratio) and glycogen were also measured. In general, the marine environments of Gourock and Largs were contaminated with significantly higher tributyltin, Pb and Zn than Loch Fyne, as indicated by the results of imposex indices, and metal concentrations in transplanted poly- mer-ligands (Chelex® 100) and Mytilus edulis. Further, metal concentrations of native M. edulis (Pb and Zn) and Semibalanus balanoides (Cu) from Gourock were significantly higher than those from Loch Fyne. However, metal accumulation in the dogwhelks displayed a very different pattern. At a standard size (0.5 g wet soft-body weight), N. lapillus from Largs showed higher Cd, Cu and MT in their tissues than individuals from the other 2 populations. Levels of Pb and Zn were similar among the populations despite different concentrations in Chelex and mussels. Gourock dogwhelks showed similar levels of Cu and MT but lower Cd compared to those of Loch Fyne. These differences can be attributed primarily to differences in dogwhelk growth rate between sites. Gourock individuals had a higher CI and RNA/protein ratio in the foot muscle and grew faster (especially at small sizes), result- ing in a tissue-dilution effect on metal and MT concentrations. In contrast, higher levels of Cd, Cu and MT in dogwhelks from Largs can be attributed to their growth rate being relatively slow compared to the rate of metal accumulation. Slow-growing individuals in Loch Fyne had relatively high Cd, Pb Zn and MT, although Loch Fyne has been regarded as a clean reference site. Among populations, dif- ferences in growth rate may be due to differences in prey availability, predation pressure, and/or genotype. The present results demonstrate that inter-site differences in growth rate can confound the use of the dogwhelks as a biomonitor of metals.

The ruthenium(II) complex cis-[Ru(6, 6'-Cl(2)bpy)(2)(OH(2))(2)](CF(3)SO(3))(2) (1) is a robust catalyst for C-H bond oxidations of hydrocarbons, including linear alkanes, using tert-butyl hydroperoxide (TBHP) as terminal oxidant. Alcohols can be oxidized by the "1 + TBHP" protocol to the corresponding aldehydes/ketones with high product yields at ambient temperature. Oxidation of 1 with Ce(IV) in aqueous solution affords cis-[Ru(VI)(6, 6'-Cl(2)bpy)(2)O(2)](2+), which is isolated as a green/yellow perchlorate salt (2). Complex 2 is a powerful stoichiometric oxidant for cycloalkane oxidations under mild conditions. Oxidation of cis-decalin is highly stereoretentive; cis-decalinol is obtained in high yield, and formation of trans-decalinol is not observed. Mechanistic studies showing a large primary kinetic isotope effect suggest a hydrogen-atom abstraction pathway. The relative reactivities of cycloalkanes toward oxidation by 2 have been examined through competitive experiments, and comparisons with Gif-type processes are presented.

An unprecedented method of producing molecular radical cations of oligopeptides in the gas phase has been discovered. Electrospraying a methanolic mixture of a Cu(II)−amine complex, e.g., CuII(dien)(NO3)2 (where dien = diethylenetriamine), and an oligopeptide (M) yields the [CuII(dien)M]•2+ ion, whose collision-induced dissociation (CID) produces [CuI(dien)]+ and M•+, the molecular cation of the oligopeptide. Abundant M•+ is apparent when the oligopeptide contains both a tyrosyl and a basic residuearginyl, lysyl, or histidyl. These structural requirements are similar to those in the metalloradical enzyme process in photosystem II. Tandem mass spectrometry of M•+ produces fragment ions that are both common to and also different from [M + H]+. The fragmentation chemistry of M•+ and of its products appear to be radical driven.

The relative silver(I) ion binding energies of 19 α-amino acids have been measured by means of the kinetic method. In general, they are similar to the relative copper(I) ion binding energies of corresponding amino acids although there are differences that can be accounted for by differences in silver(I) and copper(I) chemistry. The correlation with proton basicities is comparatively poorer. Again, the differences between silver(I) and proton binding can be attributed to differences in silver(I) and proton chemistry. The relative silver(I) binding energies measured are best described as relative basicities or ΔΔG Ag ° ’s. The observed internal consistency during construction of a silver(I) ion basicity ladder implies that ΔΔS Ag ° is approximately zero except when histidine and lysine are involved. For 16 α-amino acids, their relative silver(I) ion basicities ≈ relative silver(I) ion affinities or ΔΔG° Ag ≈ ΔΔH Ag ° .

It has been shown that guanine-rich DNA can fold into a G-quadruplex with certain metal cations. The spectral characteristics, thermostability, and kinetics for the formation of a Pb(2+)-driven G-quadruplex of thrombin-binding aptamer (TBA) were measured in the current work using a combination of ultraviolet (UV) and circular dichroism (CD) spectroscopy along with stopped-flow technique. CD spectra demonstrated that TBA could fold into a unique G-quadruplex with a strong positive peak at 312 nm. Analysis of the titration data reveals that the binding stoichiometry is 1:1 for the titration of TBA with Pb(NO(3))(2), which is in accordance with the localization of the Pb(2+) ion between the adjacent G-quartets. Thermal denaturation profiles indicate that the Pb(2+)-induced intramolecular G-quadruplex is more stable than those driven by Na(+) or K(+) ions. Kinetic studies suggest that the Pb(2+)-induced folding G-quadruplex of TBA probably proceeds through the rapid formation of an intermediate Pb(2+)-TBA complex, which then isomerizes to the fully folded structure. Conformational changes transpire after the addition of Pb(NO(3))(2) to the Na(+)- or K(+)-induced G-quadruplexes, which may be attributed to the replacement of Na(+) or K(+) ions by Pb(2+) ions and the generation of a more compact structure of the Pb(2+)-TBA structure. The relaxation time, τ, of folding the G-quadruplex is reduced from 1.05 s in the presence of Pb(2+) ions alone to 0.34 s under the cooperation of initially added Na(+) ions, while τ is increased to 8.33 s under the competition of initially added K(+) ions.

An insertion reaction of nitrosonium ion (NO+) into the metal−carbon bond of cyclometalated ruthenium(II) complexes is prepared with experimental evidence supporting a bimolecular direct NO+ insertion into the metal−carbon bond (i.e., M−R + NO+ → [M−N(═O)−R]+) but not an intramolecular migratory insertion (i.e., R−M−(NO) + L → L−M−N(═O)R) as the reaction mechanism. Theoretical calculations suggest that the direct NO+ insertion into the M−C bond may be rationalized as a frontier orbital interaction between the [Ru−aryl]-dominated HOMO of the Ru(II) complexes and the LUMO of the NO+. Accepted version

Reaction of excess cyanide with a ruthenium(VI) nitrido complex bearing a tridentate Schiff base ligand produces a novel tricyanoruthenium(III) complex in which nucleophilic substitution of an imine hydrogen of the Schiff base by cyanide has occurred, this complex is a useful building block for the construction of 3d-Ru(III) magnetic materials.

[RuVI(N)(salchda)(CH3OH)]PF6 (1) (salchda = N,N'-bis(salicylidene)o-cyclohexyldiamine dianion) reacts readily with 2,3-dimethyl-2-butene at room temperature in the presence of pyridine or 1-methylimidazole to give initially [RuIV(Az1(-H))(salchda)(py)]PF6 (2, Az1 = 2,2,3,3-tetramethylaziridine), which is then slowly reduced to [RuIII(Az1)(salchda)(py)]PF6 (3). 1 also reacts with a variety of aryl-substituted alkenes such as styrene and trans-beta-methylstyrene in the presence of py or 1-MeIm to give the corresponding ruthenium(III) aziridine complexes. The structures of 3 and [RuIII(Az2)(salchda)(1-MeIm)]PF6 (4, Az2 = trans-2-methyl-3-phenylaziridine) have been determined by X-ray crystallography. The Ru-N(aziridine) distances (2.1049, 2.097 A) are consistent with a neutral aziridine ligand. The C-C and C-N distances in the aziridine ligands are all indicative of single bonds.

The Fe(II) of the binuclear Fe(II)Fe(III) active site of pig purple acid phosphatase (uteroferrin) has been replaced in turn by five M(II) ions (Mn(II), Co(II), Ni(II), Cu(II), and Zn(II)). An uptake of 1 equiv of M(II) is observed in all cases except that of Cu(II), when a second more loosely bound Cu(II) is removed by treatment with edta. The products have been characterized by different analytical procedures and by UV-vis spectrophotometry. At 25 degrees C, I = 0.100 M (NaCl), the nonenzymatic reactions with H(2)PO(4)(-) give the mu-phosphato product, and formation constants K/M(-1) show an 8-fold spread at pH 4.9 of 740 (Mn), 165 (Fe), 190 (Co), 90 (Ni), 800 (Cu), 380 (Zn). The variations in K correlate well with stability constants for the complexing of H(2)PO(4)(-) and (CH(3)O)HPO(3)(-) with M(II) hexaaqua ions. At pH 4.9 with [H(2)PO(4)(-)]or = 3.5 mM rate constants k(obs) decrease, and an inhibition process in which a second [H(2)PO(4)(-)] coordinates to the dinuclear center is proposed. The mechanism considered accounts for most but not all of the features displayed. Thus K(1) values for the coordination of phosphate to M(II) are in the range10-60 M(-1), whereas K(2) values for the bridging of the phosphate to Fe(III) are in the narrower range 7.8-12.4. From the fits described K(i) approximately 10(3) M(-1) for the inhibition step, which is independent of the identity of M(II). Values of k(obs) decrease with increasing pH, giving pK(a) values which are close to 3.8 and independent of M(II) (Fe(II), Zn(II), Mn(II)). The acid dissociation process is assigned to Fe(III)-OH(2) to Fe(III)-OH(-), where OH(-) is less readily displaced by phosphate.

A number of polyoxomolybdates and polyoxotungstates are studied by means of electrospray tandem mass spertrometry; in each case, the mass spectrum of a solution of the polyoxoanion shows the polyoxoanion as the base peak with a minimal degree of fragmentation.

A series of cationic ruthenium(VI) nitrido species containing the cyclohexyl-bridged salen ligand (L) and its derivatives, [RuVI(N)(L)]+, have been prepared by treatment of [NBun4][RuVI(N)Cl4] with H2L in methanol. The structure of [RuVI(N)(L)](ClO4) (1a) has been determined by X-ray crystallography, d(RuN) = 1.592 A. In solvents such as DMF or DMSO, [RuVI(N)(L)]+ undergoes a facile N...N coupling reaction at room temperature to produce N2 and [RuIII(L)(S)2]+ (S = solvent). 1a reacts rapidly with secondary amines to produce diamagnetic RuIV-hydrazido(1-) species, [RuIV(N(H)NR2)(L)(HNR2)]+. The reaction with morpholine is first order in RuVI and second order in morpholine with k(CH3CN, 25 degrees C) = 2.08 x 106 M-2 s-1. This rate constant is over 4 orders of magnitude larger than that of the corresponding reaction of the electrophilic osmium nitride, trans-[OsVI(N)(tpy)(Cl)2]+, with morpholine. The structure of [Ru(NHNC4H8)(L)(NHC4H8)](PF6)2 has been determined by X-ray crystallography, the Ru-N(hydrazido) distance is 1.940 A, and the Ru-N-N angle is 129.4 degrees .

Eight new nitridoosmium(VI) complexes with the general formula [OsVI(N)Cl3(Hazole)2] have been synthesized and characterized. The cellular uptake and the antiproliferative activities of these compounds against a panel of human cancer cell lines have been investigated. Complexes with pyrazole derivatives (1, 2, 3 and 4) are found to possess significant in vitro cytotoxicity. Further studies of compounds 1 and 3 indicate that they induce S phase arrest in HeLa cells followed by apoptosis, possibly as a result of binding with DNA.

Reaction of [Ru(II)(PPh(3))(3)Cl(2)] with HQ and KCN produces a new dicyanoruthenium(III) building block, [Ru(III)(Q)(2)(CN)(2)](-). It reacts with hydrated CoCl(2) in MeOH or DMF to produce a trinuclear compound 2 or a 1-D zigzag chain 3.