Inorganic Chemistry

Polymorphs of Zn(2-nIm) 2 (compound 1) and Co(2-nIm) 2 (compounds 2 and 3) (2-nIm = 2nitroimidazole) have been prepared by two routes: solvothermal synthesis and recrystallisation of ZIF-65(Zn/Co). Compounds 1 and 2 are isostructural, with a tetrahedrallyconnected framework topology related to, but different from, that of tridymite (lonsdaleite). Single crystal X-ray diffraction analysis showed that in compound 1 (Pccn, Z = 8; a = 8.462(8) Å, b = 14.549(15) Å, c = 18.799(18) Å, V = 2314(4) Å 3 ) there is rotational disorder for two of the three crystallographically-distinct linker types, which has been investigated computationally and by solid-state NMR spectroscopy. Detailed adsorption studies on a sample of 1 prepared by recrystallisation show 1.1 mmol g -1 uptake of CO 2 at 0.1 bar (25 °C) with high affinity for CO 2 over CH 4 and N 2 (adsorption enthalpies of 39.5, 26.0 and 18.5 kJ mol -1 , respectively). A cobalt analogue (compound 2) with improved water stability (but lower porosity) has also been prepared. Changing the conditions of synthesis and recrystallisation gives rise to a cobalt 2-nitroimidazolate (Co(2-nIm) 2 , compound 3), which has a layered structure (I4 1 /amd, a = 6.025(18) Å, c = 26.95(8) Å, V = 978.3(5) Å 3 ) containing sheets of tetrahedrally-connected Co 2+ cations composed of four membered rings, without porosity.

A formal total synthesis of the antitubercular natural product was accomplished. This work was undertaken to address certain stereochemical problems in our initial synthesis. By using an ester group as a surrogate for a methyl group, we were able to intercept a key intermediate in our first synthesis with better selectivity and greater convergence than had previously been the case.

Single crystal Electron Paramagnetic Resonance (EPR) spectroscopic, X-ray diffraction experiments, and DFT calculations were carried out to determine the crystal structure of zinc creatinine sulfate, to identify the doped Cu(II) binding site, and to investigate the mechanism behind proto-coupled electron transfer observed in UV exposed crystals. Similar to the cadmium-creatinine complex, the metal is not in coordination with the creatininium cation, but forms a hexahydrate which is buffered from the creatininium by an intervening sulfate ion. Both the EPR measured g (2.44, 2.13, 2.08) and copper hyperfine (325, 77, 0 MHz) tensors and structure are consistent with doped copper replacing zinc in the hexahydrate complex. The room temperature EPR tensors are similar to those previously observed for copper hexahydrate in other doped crystal systems, for example in doped Tutton salts, but only those measured at very low temperatures. In these other systems, vibration couplings stemming from dynamic Jahn-Teller effects cause tensor averaging at temperatures up to room temperature. The reasons why this does not happen in the cadmium and current zinc host structure is an area of recent study. Progress towards analyzing and correlating the unpaired Cu(II) and creatininium radical wavefunctions, the crystal structure and the proton-coupled electron transfer will be presented.

The interaction between hexacyanoferrate(II1) and some copper complexes of different geometry was studied. In solution, and in the presence of coordination unsaturation of copper, 1: 1 and 2:l Cu:Fe adducts formed and were characterized by the absence of any copper electron paramagnetic resonance (EPR) signal. The magnetic susceptibility of the 1: 1 adducts is essentially equal to the sum of those due to the parent compounds. Solid state studies confirm the solution data. In the light of the present results the absence of the EPR signal of [Fe(CN),13--treated galactose oxidase is discussed.

Cerium-manganese mixed oxides with different composition were prepared by co-precipitation, characterized and evaluated for the water-gas shift (WGS) reaction. Base metal (5 wt.% Cu and 5 wt.% Ni) catalysts supported on Ce-Mn mixed oxides were also tested for the WGS reaction. The activity of the bare supports is higher in the mixed samples than in pure ceria or manganese oxide. This result can be explained by a combination of greater reducibility and surface area in the mixed samples. Addition of base metals produces superior WGS catalysts. Particularly, nickel catalysts tested are able to reduce typical CO concentrations entering the WGS process to the CO levels tolerated by phosphoric acid fuel cells in a single unit operated at 400 °C.

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An efficient method to access 2-triazolyl thio-/selenopyridines with good to excellent yields by ruthenium(II)-catalyzed one-pot [3 + 2]/[2 + 2 + 2] cycloaddition reactions of azides, 1-alkynyl thio-/ selenocyanates and 1,6-diynes is reported. This atom-economical catalytic strategy offers a mild and practical approach to access a variety of such cycloadducts with good to excellect regioselectivities. The protocol was further extended to the synthesis of 3,3'-bis(triazolyl thio-/seleno)-2,2'-bipyridines by the reaction of tetraynes with 1-alkynyl thio-/selenocyanates in the presence of aryl/alkyl azides.

< A high oxidation current in glycerol electro-oxidation was observed at 250 C. < High selectivity for CO 2 production was obtained at 250 C. < CeC bond dissociation ratio reached 70e80% at both low and high potentials. < Stable operation during glycerol electro-oxidation at around 250 C requires a high S/C ratio. < The present observations provide strategies for the effective operation of DAFCs.

Traditional materials from new sourcesconflicts in analytical methods for calcium carbonate. Calcium carbonate, (E170) is a common food and pharmaceutical additive/ingredient. In addition to a source of calcium, the carbonate has uses including as a colour, acidity regulator and bulking agent. Globally, a range of regulatory agencies and pharmacopoeia control the analyses and specification of additives in food, supplements, pharmaceutical substances and excipients. Accordingly, a range of specifications and analyses exist for calcium carbonate depending on the application and market of the product. In this contribution, we analyse calcium carbonates from geological, synthetic and biogenic sources, focussing on acid insoluble impurities, a test required by current monographs. Analysis of calcium carbonate from different origins may require modification of existing tests to comply with regulatory bodies, due to the variation of impurities specific to the source of the material. We suggest an analytical approach involving centrifugation that improves analytical efficiency (up to 85% time reduction), especially for calcium carbonate of biological origin.

New methods for peptide modification are in high demand in drug discovery, chemical biology and materials chemistry; methods that modify natural peptides are particularly attractive. A Pd-catalyzed, C-H functionalization protocol for the olefination of phenylalanine residues in peptides is reported, which is compatible with common amino acid protecting groups, and the scope of the styrene reaction partner is broad. Bidentate coordination of the peptide to the catalyst appears crucial for the success of the reaction.

We show that the azamacrocycle 'cyclam' (1,4,8,11-tetraazacyclodecane) in conjunction with a silicon catecholate ion generates novel hollow tetragonal tube-like crystalline materials [(C 6 H 4 O 2 ) 3 Si][C 10 H 26 N 4 ]•H 2 O, whose dimensions can be tuned according to the pH of the reaction medium. The synthesis approach was successful for both silicon and germanium and we hypothesise that a range of other catecholate precursors of elements such as iron could be used to generate a large array of inorganic materials with interesting morphologies. The synthesis approach can be extended to tertiary diamines with functional group spacing playing an important role in the efficacy of complexation. Of the molecules explored to date, a C2 spacing (N,N,N′,N′-Tetramethylethylenediamine (4MEDAE)), leads to the most efficient structure control with hollow hexagonal tube-like structures being formed. In addition, we show that azamacrocycles, in the presence of unbuffered tetramethoxysilane (TMOS) solutions can be used to manipulate silica formation and provide a fast (ca. 10 minute) synthesis route to particles whose diameter can be tuned from ca. 20nm to several hundreds of nm under reaction conditions (no extremes of pH) that make the sols suitable for direct use in biotechnological applications.

We demonstrate the use of silk based proteins to control the particle/crystallite size during GeO 2 formation, using a bio-mimetic approach at circumneutral pH and ambient temperature. Multicrystalline GeO 2 was prepared from germanium tetraethoxide (TEOG) in the presence of different silk-based proteins: Bombyx mori silk (native silk) and two chimeric proteins prepared by linking a germania binding peptide (Ge28: HATGTHGLSLSH) with Bombyx mori silk via chemical coupling at different peptide loadings (silk-Ge28 10% and silk-Ge28 50%). The mineralisation activity of the silk-based proteins was compared with that of peptide Ge28 as a control system. GeO 2 mineralisation was investigated in water and in citric acid/bis-tris propane buffer at pH 6. Morphology, particle size, crystallinity, water and organic content of the materials obtained were analysed to study the effect of added biomolecules and mineralisation environment on material properties. In the presence of silk additives well-defined cube-shape hybrid materials composed of hexagonal germania and up to ca. 5 wt% organic content were obtained. The cubic particles ranged from 0.4 to 1.4 m in size and were composed of crystalline domains in the range 35-106 nm depending on the additive used and synthesis conditions. The organic material incorporated in the mineral did not appear to affect the unit cell dimensions. The silk and chimeric proteins in water promote material formation and crystal growth, possibly via an effective ion-channelling mechanism. The germania binding peptide alone did not have any significant effect on reaction rate, yield or the material's properties compared to the blank. Interestingly, the peptide content in the silk chimeras tested did not affect mineralisation. The presence of buffer inhibited mineral condensation rate and yield. The use of silk-based biomolecules allows control of crystallite/particle size of hybrid materials opening up opportunities for bio-inspired approaches to be applied for the synthesis of functional germania based devices and materials. 100 Dr Olivier Deschaume for help with the chimera synthesis and Gordon Arnott for SEM technical support.

Ca 1Àx Pr x MnO 3Àd (x=0, 0.05, 0.15, 0.1, 0.2, 0.4, 0.67; d=0.02) samples were prepared by a solid-state reaction method. X-ray diffraction analysis showed that all samples prepared were of single phase with orthorhombic structure. Electrical resistivity measurements from room temperature to 1300 K showed that a metallic conducting tendency dominated at high temperatures. The hopping nature of the charge carriers was well interpreted in the framework of polaron theory. The Seebeck coefficient was measured in the same temperature interval, and its concentration dependence was analyzed using the high-temperature (HT) thermopower theory proposed by Marsh-Parris. The thermal conductivity and the figure of merit of the prepared samples were also compared with those of other similar perovskite compounds. The observed figure of merit of the sample with x=0.15 was Z=1.5 Â 10 À4 K À1 at T=1100 K, indicating a good potential for application as a HT thermoelectric material.

A new series of 14–16 membered tetraazatetraimine macrocyclic complexes [ML1X2]-[ML3X2] [M=CoII, NiII and ZnII] and [CuL1]X2-[CuL3]X2 [X=Cl or NO3] have been synthesized by the template condensation of dibenzoylmethane with primary diamines in MeOH. The complexes were characterized by elemental analysis, i.r, 1H-n.m.r., e.p.r. and u.v-vis spectroscopy, as well as by conductivity and magnetic susceptibility measurements. The copper complexes exhibit square

A new series of 14–16-membered hexaazamacrocyclic complexes [ML1X2] and [ML2X2] (M = CoII, NiII, CuII and ZnII; X = Cl or NO3) have been synthesized by template condensation of phenylenediamine, primary diamines and formaldehyde solution 35% in MeOH and have been characterized by i.r., 1H-n.m.r., e.p.r., and u.v. spectroscopy as well as by magnetic susceptibility and conductivity measurements. An octahedral

Relaxors are very interesting materials but they are most of the time restricted to perovskite materials and thus their flexibility is limited. We have previously shown that tetragonal tungsten bronze (TTB) niobates Ba 2 PrFeNb 4 O 15 was a relaxor below 170K and that Ba 2 NdFeNb 4 O 15 displays a ferroelectric behavior with a T C =323K. On scanning the whole solid solution Ba 2 Pr x Nd 1-x FeNb 4 O 15 (x= 0, 0.2, 0.4, 0.5, 0.6, 0.8, 1), we demonstrate here a continuous cross over between these end member behaviors with a coexistence of ferroelectricity and relaxor in the intermediate range. This tuneability is ascribed to the peculiar structure of the TTB networks which is more open than the classical perovskites. This allows for the coexistence of long range and short range orders and thus opens the range of relaxor materials. Because of their useful dielectric and piezoelectric properties, relaxors are under deep investigations nowadays. 1, 2, 3

Several Niobium oxides of formula Ba 2 LnFeNb 4 O 15 (Ln = La, Pr, Nd, Sm, Eu, Gd) with the "Tetragonal Tungsten Bronze" (TTB) structure have been synthesised by conventional solid-state methods. The Neodymium, Samarium and Europium compounds are ferroelectric with Curie temperature ranging from 320 to 440K. The Praseodymium and Gadolinium compounds behave as relaxors below 170 and 300 K respectively. The Praseodymium, Neodymium, Samarium, Europium and Gadolinium compounds exhibit magnetic hysteresis loops at room temperature originating from traces of a barium ferrite secondary phase. The presence of both ferroelectric and magnetic hysteresis loops at room temperature allows considering these materials as composites multiferroic. Based on crystalchemical analysis we propose some relationships between the introduction of Ln 3+ ions in the TTB framework and the chemical, structural and physical properties of these materials.

Ubiquitous nature of erectile dysfunction (ED) has placed it as one of the most rampant health care problem and therefore consumption of energy stimulating herbal medicines (ESHMs) has increased in Bangladesh. However, these herbal medicines reaching consumers without maintaining proper screening procedure, which bring a threat to public health safety. An analysis of biological contaminants (microbial load) of these herbal medicines available in Bangladesh was investigated. In most of samples, the total bacterial counts (TBC) 6 × 107 − 32 × 1011 cfu/mL and lactobacillus count 6 × 108 − 12 × 1011 cfu/mL exceed the maximum value as percribed by WHO.

MgO with a high concentration of defects was produced by the dehydration of high-purity Mg(OH), and the conductivity was studied in the temperature range 20-250°C. An atmosphere of hydrogen increased the conductivity by up to a factor of 10' and produced a characteristic conductivity maximum when the sample was heated. The hydrogen interacts with the sample at V$-centers which are located at the surface of the dehydrated material. These centers are supposed to have a catalytic activity, i.e. they decompose hydrogen molecules into atoms and further into electrons and protons which contribute to the current.

Hydrogen and oxygen evolution from MgO prepared by thermal decomposition of high purity Mg(OH)2 was studied mass spectroscopically. Hydrogen is evolved in the temperature range 300-600°C (maximum at 450%) and again between 600 and 900°C (maximum at 750°C). The amount of Hz evolved is of the order of 1010-1020 molecules g-l MgO. An equivalent amount of oxygen appears to be evolved predominantly as atomic oxygen between 600 and 9OOW. The first Hz evolution is assigned to the formation of Hz molecules within cation vacancies [Mg]" in the MgO neighbored by two OH-groups, leading to the formation of Oions: 2 OH-e2 O-+ Hz. The second Hz evolution is assigned to the dissociation of residual OH-groups: OH--+ O-+ fH2. Th e oxygen evolution is probably due to decomposition of O-: 20--+ 02-+ 0. The O-concentration in the MgO calculated on the basis of these experiments is lo'-106 times higher than the concentration of VI centers achieved by thermal activation and measured bv esr. This indicates that only a very small fraction of the O-ions present in the sample is able to form VI centers.

Three water-soluble Ru(II) chiral heteroleptic coordination compounds [Ru(en)(pdto)]Cl2 (1), [Ru(gly)(pdto)]Cl (2), and [Ru(acac)(pdto)]Cl (3), where pdto = 2,2&#39;-[1,2-ethanediylbis-(sulfanediyl-2,1-ethanediyl)]dipyridine, en = ethylendiamine, gly = glycinate, and acac = acetylacetonate, have been synthezised and fully characterized. The crystal structures of compounds 1-3 are described. The IC50 values for compounds 1-3 are within nanomolar range (14, 12, and 6 nM, respectively). The cytotoxicity for human peripheral blood lymphocytes is extremely low (&gt;100 μM). Selectivity indexes for Ru(II) compounds are in the range 700-1300. Trophozoites exposed to Ru(II) compounds die through an apoptotic pathway triggered by ROS production. The orally administration to infected mice induces a total elimination of the parasite charge in mice faeces 1-2-fold faster than metronidazole. Besides, all compounds inhibit the trophozoite proliferation in amoebic liver abscess induced in hamster....

A new anionic heteroleptic Ir(III)-dithiolate complex Ir(ppy)2(benzene-1,2-dithiolate) (ppy = 2-phenylpyridine, [IrSS](-)) undergoes very fast air oxidation to form a monosulfinate complex [IrSSO2](-), which can be further dioxygenated by O2 or H2O2 to give a disulfinate complex [IrSO2SO2](-), which has been characterized by X-ray crystallography. The dioxygenation is accompanied by changes in the electronic structures of the complexes, leading to blue shift of emission from [IrSS](-) (λ(max) = 665 nm) to [IrSSO2](-) (λ(max) = 556 nm) and to [IrSO2SO2](-) (λ(max) = 460 nm). The molecular and electronic structures of the complexes are probed by DFT calculations. Time-dependent DFT (TD-DFT) calculations show the lowest energy spin-allowed electronic transitions for [IrSS](-) and [IrSSO2](-) are mainly ligand (3p orbital of S)-to-ligand (π* orbitals of ppy)-charge-transfer transition, whereas the lowest energy electronic transition in [IrSO2SO2](-) is predominantly metal-to-ligand-char...

Five isostructural lanthanide-organic coordination frameworks with a unique 3-D 5-connected (4(7).6(3))(4(3).6(5).8(2)) network, namely, [Ln(phen)(L)]n (Ln = Dy for 1, Gd for 2, Ho for 3, Er for 4, and Tb for 5), have been prepared based on bridging 5-hydroxyisophthalic acid (H3L) and chelating 1,10-phenanthroline (phen) coligand. Significantly, the Dy(III) complex 1 is an organized array of single-molecular magnets (SMMs), with frequency-dependent out-of-phase ac susceptibility signals and magnetization hysteresis at 4 K. Further analysis of the magnetic results can reveal that the SMM behavior of 1 should arise from the smaller ferromagnetic interaction between the Dy(III) ions. Complex 1 was also characterized by X-ray absorption spectra, which give the clear X-ray magnetic circular dichroism signal.

The electrochemical regeneration of Ce(IV) for mediated electrochemical oxidation in sulfuric acid media was investigated in an electrolytic membrane reactor. A simple kinetic model was developed to analyze and simulate the regeneration of Ce(IV) in the electrolysis process. The model was based on the Faraday's law and the mass balance of components in the reactor. The key operating conditions of the initial electrolyte concentration and the regeneration time were analyzed. It was found that the simulating model agreed well with the experimental data for regeneration of Ce(IV). Experimental results showed that Ce(SO 4 ) -2 is the active species. The decomposition of surface complex of Ce(IV) at the anode surface is the rate determining step. Constant-current electrolysis shows that the high proton and Ce(III) concentrations are electrochemically favorable for the regeneration of Ce(IV). The current efficiency for regeneration of Ce(IV) decrease obviously with the increase of SO 4 2-concentration from 0.8 to 2.4 mol/L.

Dietary supplements are drastically growing as a category of consumer products all over the world. The abuse of supplements marketed for slimming purposes and physical tness has been observed worldwide in recent years, which raises concerns in terms of public health. In this study, different types of dietary supplements marketed and delivered through the e-commerce were studied for the determination of thallium as a hazardous inorganic contaminant. The total content of thallium was determined by a sensitive voltammetric method after a microwave-assisted oxidative digestion of the sample. In addition, a comparative spectrometric method was applied for validation of the results in the samples. The maximum concentration found for thallium was found to be 2.89 mg kg -1 , which well agree with the comparative measurement. Considering the 32 studied formulations, it can be pointed out that ~ 24% of the of dietary supplements presented Tl concentrations at concentrations higher than 1 mg kg -1 . The results permitted the assessment of the health risk related to thallium from contaminated samples, based on the calculation of the estimated daily intake (EDI) and the risk quotient (HQ). The highest daily intake of thallium was calculated as 82.0 µg day -1 in a protein-based supplement, which is equivalent to an EDI of 1.17 µg kg -1 day -1 . This work highlights the need to develop regulations on the limits of toxic elements as thallium in widely consumed dietary supplements, as well as an in-depth look at the adverse effects caused by this element in the human body.

Phosphaplatins are platinum-based antitumor compounds that, unlike other clinically utilized platinum drugs (i.e. cisplatin, carboplatin, and oxaliplatin), appear to target proteins rather than DNA. Because of their unique mode of action, phosphaplatins are promising drug candidates for cisplatin-resistant cancers. In this study, we discovered that Pt(II) and Pt(IV) phosphaplatins possess diverse antitumor properties. In addition to targeting apoptosis antigen (FAS) and proapoptotic gene products as described previously, phosphaplatins also target angiogenesis. We demonstrate that phosphaplatins inhibit human umbilical vein endothelial cell (HUVEC) migration and tube formation in vitro and suppress tumor angiogenesis and growth in immunodeficient mice that were inoculated with A2780 ovarian cancer cells in vivo. To provide insight into this novel antitumor mechanism, phosphaplatin-treated HUVECs were found to exhibit lower gene expression levels of vascular endothelial growth factors (VEGFs) and the VEGFR-2 receptor compared to untreated cells. Kinase inhibition studies suggest that phosphaplatins are inhibitors of VEGFR-2. In ligand exchange experiments using both Pt atomic absorption and 31 P NMR spectroscopies, we show that phosphaplatins most likely bind to VEGFR-2 through metal-ligand coordination rather than electrostatic interactions. These studies enhance our understanding of the diverse and novel mechanisms of action of the phosphaplatin antitumor agents, which could potentially be used as chemotherapeutic agents against cisplatin-resistant cancers.

Phosphaplatins are platinum-based antitumor compounds that, unlike other clinically utilized platinum drugs (i.e. cisplatin, carboplatin, and oxaliplatin), appear to target proteins rather than DNA. Because of their unique mode of action, phosphaplatins are promising drug candidates for cisplatin-resistant cancers. In this study, we discovered that Pt(II) and Pt(IV) phosphaplatins possess diverse antitumor properties. In addition to targeting apoptosis antigen (FAS) and proapoptotic gene products as described previously, phosphaplatins also target angiogenesis. We demonstrate that phosphaplatins inhibit human umbilical vein endothelial cell (HUVEC) migration and tube formation in vitro and suppress tumor angiogenesis and growth in immunodeficient mice that were inoculated with A2780 ovarian cancer cells in vivo. To provide insight into this novel antitumor mechanism, phosphaplatin-treated HUVECs were found to exhibit lower gene expression levels of vascular endothelial growth factors (VEGFs) and the VEGFR-2 receptor compared to untreated cells. Kinase inhibition studies suggest that phosphaplatins are inhibitors of VEGFR-2. In ligand exchange experiments using both Pt atomic absorption and 31 P NMR spectroscopies, we show that phosphaplatins most likely bind to VEGFR-2 through metal-ligand coordination rather than electrostatic interactions. These studies enhance our understanding of the diverse and novel mechanisms of action of the phosphaplatin antitumor agents, which could potentially be used as chemotherapeutic agents against cisplatin-resistant cancers.

In order to extend the photoactivity of titanium dioxide into the visible region, highly porous nitrogen-doped TiO 2 catalysts (NTiO 2 ) were successfully synthesized by a modified co-precipitation method with ammonium hydroxide as a nitrogen source. Different approaches such as dosing order of the reagents and temperature of the synthesis, calcination period and temperature were tested to examine the optimum outcome regarding photocatalytic OH radical formation under UV and visible light. Coumarin as a traditional probe for this purpose was applied; measuring the luminescence of 7-hydroxycoumarin produced in the reaction with OH radicals, beside the formation of other hydroxylated derivatives. Only a few percentages of the coumarin molecules reacted with OH radicals, while most of them underwent reactions with other photogenerated species such as electrons (anaerobic/aerobic) and superoxide anion radicals (aerobic). Accordingly, our observations suggest that coumarin can also be used as a probe to quantify the formation of other reactive species. The results were obtained from the difference between the amounts of degraded coumarin and hydroxylated coumarin derivatives formed during photocatalytic experiments. These coumarin-based quantifications of photoactivity was applied for the characterization of the prepared nitrogen-doped TiO 2 catalysts (NTiO 2 ). In addition, material analysis (Xray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry, and Fourier transform infrared spectroscopy) showed that crystallinity and nitrogen content were found to be crucial features in the photocatalytic performance of the catalysts.

Some years ago the authors discovered [I ] that square planar rhodium(i) isocyanide complexes (e.g. Rh(CNPh),i ) aggregate in solution. The binuclear species are intensely colored, owing to a strong visible absorption system attributable to an allowed a*(d,2) 3 a( p,, m*CNR) transition associated with the direct Rh(I)-Rh(1) interaction [1,2]. Eariy in our research on these oligomeric species, Lewis and Mann employed binucleating diisocyanides (e.g. 1.3-diisocyanopropane, which we call "bridge", or b) to prepare discrete binuclear Rh(1) complexes for detailed studies [3-151. The authors have found that Rh,bi+ and certain related complexes possess rich photophysical and photochemical properties, and it is the former area that will be reviewed in the sections that follow.

A new monomeric manganese(II) benzoate complex containing nitrogen donor 2,2΄-bipyridine, [Mn(OBz) 2 (bipy)(H 2 O)] (OBz = benzoate, bipy = 2,2΄-bipyridine) has been synthesized from aqueous methanol medium and characterized by analytical, spectroscopic and single crystal X-ray diffraction studies. The compound also exhibits moderate to appreciable antimicrobial activity. The complex crystallizes in space group P2 1 /n. Mn(II) atom is ligated by two N atoms of bipyridine, three O atoms from a monodentate and a bidentate benzoate ligand and a water molecule forming distorted octahedral structure. The coordinated water molecule forms intramolecular hydrogen bonds and links the monomer molecules into hydrogen bonded dimer. The hydrogen bonded dimers are involved in intermolecular C-H···O and π-π stacking interactions. Density functional theory (DFT) computation was carried out for calculation of vibrational mode of frequencies to compute the frequencies of relevant vibrational modes and electronic properties, the results are in compliance with the experimentally obtained structural and spectral data.

Introduction: Systemic amyloidosis is a progressive disorder characterized by the extracellular deposition of amyloid fibrils and accessory proteins in visceral organs and tissues. Amyloid accumulation causes organ dysfunction and is not generally cleared by the immune system. Current treatment focuses on reducing amyloid precursor protein synthesis and slowing amyloid deposition. However, curative interventions will likely also require removal of preexisting amyloid deposits to restore organ function. Here we describe a prototypic pan-amyloid binding peptide-antibody fusion molecule (mIgp5) that enhances macrophage uptake of amyloid. The murine IgG1-IgG2a hybrid immunoglobulin with a pan amyloidreactive peptide, p5, fused genetically to the N-terminal of the immunoglobulin light chain was synthesized in HEK293T/17 cells. The binding of the p5 peptide moiety was assayed using synthetic amyloid-like fibrils, human amyloid extracts and amyloid-laden tissues as substrates. Binding of radioiodinated mIgp5 with amyloid deposits in vivo was evaluated in a murine model of AA amyloidosis using small animal imaging and microautoradiography. The bioactivity of mIgp5 was assessed in complement fixation and in vitro phagocytosis assays in the presence of patient-derived amyloid extracts and synthetic amyloid fibrils as substrates and in the presence or absence of human serum. Results: Murine Igp5 exhibited highly potent binding to AL and ATTR amyloid extracts and diverse types of amyloid in formalin-fixed tissue sections. In the murine model of systemic AA amyloidosis, 125 I-mIgp5 bound rapidly and specifically to amyloid deposits in all organs, including the heart, with no evidence of non-specific uptake in healthy tissues. The bioactivity of the immunoglobulin Fc domain was uncompromised in the context of mIgp5 and served as an effective opsonin. Macrophage-mediated uptake of amyloid extract and purified amyloid fibrils was enhanced by the addition of mIgp5. This effect was exaggerated in the presence of human serum coincident with deposition of complement C5b9.

Fe-V pure and mixed sulfides have been prepared from solutions containing iron nitrate and/or ammonium tetrathiovanadate and precipitation with ammonium sulfide. After treatment with H 2 S (15%)-H 2 at 673 K, they exhibit quite high surface area from 57 to 5 m 2 • g -1 . X-ray diffraction and M össbauer spectroscopy show the existence of a continuum from the pyrrhotite phase (Fe 0.85 S) to a V 3 S 4 -like phase (V 0.74 S). The structure of the solids is not modified by the catalytic tests which consist in hydrodesulfurization (HDS) of thiophene, hydrogenation (HYD) of toluene, and hydrodeporphyrinization (HDP) of vanadyl octaethyl porphyrine. X-ray photoelectron spectroscopy characterizations indicate a surface Fe-V homogeneity in the mixed sulfides corresponding to the bulk composition and show an effective surface oxidation of the prepared or tested samples occuring during air exposure. Surface compounds like VOSO 4 , V 2 O 5 , Fe 2 O 3 , xH 2 O, and FeOOH have been identified. Concerning the catalytic behaviors, it is worth mentioning that bulk Fe 0.85 S is only active for HDP whereas bulk V 0.74 S has a high potential activity in HDS, HYD, and HDP by comparison with bulk MoS 2 . Moreover, a synergy effect is detected for about 30 atomic% in Fe which origin could be assigned to an optimal dispersion of the V active sites.

The oxygen content (3-δ) variations in tin substituted derivatives SrFe 1-x Sn x O 3-δ , where x = 0.05, 0.1, 0.17 and 0.25, of perovskite-like strontium ferrite, have been studied by coulometric titration measurements within oxygen partial pressure (p O 2 ) range 10 -19 -10 -2 atm at 800-950 °С. The obtained dependencies of (3-δ) from p O 2 and temperature are used for calculations of partial molar thermodynamic functions of oxygen in the oxide structure. It is found that a satisfactory explanation of the experimental results can be attained within frameworks of the ideal solution model with ion and electron defects appearing in the result of oxidation and disproportionation of iron cations. The increase of the oxidation reaction enthalpy with tin content is consistent with the increase of the unit cell parameter, i.e., the stretch and relaxation of Fe-O chemical bonds.

We present a case where the microstructure has a profound effect on the thermoelectric properties of oxide compounds. Specifically, we have investigated the effect of different sintering treatments on La 1-x Sr x CoO 3 samples synthesized using the Pechini method. We found that the samples, which are dense and consist of inhomogeneously-mixed grains of different size, exhibit both higher Seebeck coefficient and thermoelectric figure of merit than the samples, which are porous and consist of grains with almost identical size. The enhancement of Seebeck coefficient in the dense samples is attributed to the so-called "energy-filtering" mechanism that is related to the energy barrier of the grain boundary. On the other hand, the thermal conductivity for the porous compounds is significantly reduced in comparison to the dense compounds. It is suggested that a fine-manipulation of grain size ratio combined with a fine-tuning of porosity could considerably enhance the thermoelectric performance of oxides.

Estudos potenciométricos foram realizados para determinar o grau de ligação do ácido fítico com os íons Co(II) e o Mn(II), na ausência de dioxigênio. As constantes de equilíbrio para as principais espécies formadas são relatadas, e os resultados são representados na forma de diagramas de distribuição mostrando a concentração individual dos complexos como uma função do pH. Os valores das constantes de formação dos complexos foram elevados para as espécies em que o ligante encontra-se mais desprotonado. Os dados potenciométricos indicam que a espécie [MH 4 L] 6-, encontra-se totalmente formada em pH 7,0 e a partir destes dados os complexos de Mn(II) e Co(II) com o ácido fítico foram sintetizados no estado sólido. Análises de infravermelho, termogravimetria e calorimetria exploratória diferencial foram utilizadas para caracterizar e investigar o comportamento térmico destes compostos. Os resultados conduziram a informações sobre composição, desidratação, estabilidade e decomposição térmica dos complexos. Potentiometric studies were carried out to determine the binding degree of phytic acid with Co(II) and Mn(II) ions, in the absence of dioxygen. Equilibrium constants for all major complexes formed are reported, and the results are presented in the form of distribution diagrams showing the concentrations of individual complexes as a function of pH. The formation constants of the complexes show higher values for the species in which the ligand was more deprotonated. Potentiometric data indicates that the species [MH 4 L] 6-, was totally formed at pH 7.0 and the complexes were synthesized from this data. A solid state complex of Mn(II) and Co(II) with phytic acid was synthesized. Thermogravimetry, differential scanning calorimetry, and infrared spectroscopy were used to investigate and characterize the thermal behavior of these compounds. The results led to information on the composition, dehydration, thermal stability and thermal decomposition of the isolated complexes.

A necessidade de se estudar compostos modelo é a de se compreender como os sítios de quelação de substâncias orgânicas complexas como os ácidos húmicos e nitro-húmicos atuam frente a um íon metálico, pois as substâncias húmicas são potenciais fertilizantes orgânicos. As propriedades químicas principais dos complexos encontrados entre os ácidos 3-nitroftálico e 4-nitroftálico e os íons metálicos Fe(III) e Zn(II) foram estudadas por titulações potenciométricas, espectroscopia ultravioleta-visível e voltametria cíclica, e uma titulação potenciométrica experimental foi feita com uma mistura de modelos de ácidos nitro-húmicos e Cu(II). Calculou-se as constantes de equilíbrio para os sistemas, cujas espécies foram detectadas pelas outras técnicas empregadas. Estudos comparativos entre sítios de quelação derivados de nitrossalicilatos e nitrocatecolatos com Fe(III), Zn(II) e Cu(II) são apresentados. Neste trabalho, os ácidos nitro-húmicos, além de possuírem maior teor de nitrogênio que os ácidos húmicos, também exibiram a vantagem de que alguns centros de quelação, preferencialmente, se ligam a íons metálicos nos valores de p[H] próximos aos valores normais do solo, 7,0 a 7,5. The study of model compounds is necessary in order to obtain information about complex organic substances as in the case of humic substances (HS). These substances are potential organic fertilizers and have other important functions in soils, natural waters and organic sediments. The main chemical properties of the complexes formed from 3-nitrophthalic and 4-nitrophthalic acids and the metal ions Fe(III) and Zn(II) were studied using potentiometric titrations, ultravioletvisible spectroscopy (UV-Vis) and cyclic voltammetry (CV). A trial potentiometric titration was done with a mixture of the models for nitrohumic acids and Cu(II). Equilibrium constants for the systems were calculated and UV-Vis and CV were employed to monitor the formation of the species. Comparative studies involving chelating centres of nitrosalicylic acids and nitrocatechols with Fe(III), Zn(II) and Cu(II) are presented. The initial studies involving the nitrohumic substances (NHS), a laboratory artifact of HS have been made and good evidence was found for the further use of NHS as a potential organic fertilizer as well as HS. In this present work one of the observed advantages of NHS over HS was that some aromatic nitro-centres can bind some metal ions at p[H] values of normal soils, near 7.0 to 7.5.

Estudos potenciométricos foram realizados para determinar o grau de ligação do ácido fítico com os íons Co(II) e o Mn(II), na ausência de dioxigênio. As constantes de equilíbrio para as principais espécies formadas são relatadas, e os resultados são representados na forma de diagramas de distribuição mostrando a concentração individual dos complexos como uma função do pH. Os valores das constantes de formação dos complexos foram elevados para as espécies em que o ligante encontra-se mais desprotonado. Os dados potenciométricos indicam que a espécie [MH 4 L] 6-, encontra-se totalmente formada em pH 7,0 e a partir destes dados os complexos de Mn(II) e Co(II) com o ácido fítico foram sintetizados no estado sólido. Análises de infravermelho, termogravimetria e calorimetria exploratória diferencial foram utilizadas para caracterizar e investigar o comportamento térmico destes compostos. Os resultados conduziram a informações sobre composição, desidratação, estabilidade e decomposição térmica dos complexos. Potentiometric studies were carried out to determine the binding degree of phytic acid with Co(II) and Mn(II) ions, in the absence of dioxygen. Equilibrium constants for all major complexes formed are reported, and the results are presented in the form of distribution diagrams showing the concentrations of individual complexes as a function of pH. The formation constants of the complexes show higher values for the species in which the ligand was more deprotonated. Potentiometric data indicates that the species [MH 4 L] 6-, was totally formed at pH 7.0 and the complexes were synthesized from this data. A solid state complex of Mn(II) and Co(II) with phytic acid was synthesized. Thermogravimetry, differential scanning calorimetry, and infrared spectroscopy were used to investigate and characterize the thermal behavior of these compounds. The results led to information on the composition, dehydration, thermal stability and thermal decomposition of the isolated complexes.

Vitamin D 3 (LH) complexes with manganese(II), iron(II), iron(III) and zinc(II) were identified in water-ethanol medium (30/70). Their stability constants were determined at 298 K and at a constant ionic strength of 0.100 M using potentiometric methods. The computerisation of the experimental data showed the presence of ML (M =metal, L=deprotonated vitamin D3) and ML2 species in all cases; in addition, the ML3 iron(Ill) complex was detected. The calculated overall stability constants /3 for Mn"L, FenL, FeI'L and ZnUL are, respectively, in logarithms, 12.4, 16.5, 28.5 and 16.5. Under the experimental conditions, the only protonated species MLH detected was with iron (III).

A novel heterobinuclear mixed valence complex [Fe III Cu II (BPBPMP)(OAc) 2 ]ClO 4 , 1, with the unsymmetrical N 5 O 2 donor ligand 2-bis[{(2-pyridylmethyl)aminomethyl}-6-{(2hydroxybenzyl)(2-pyridylmethyl)}aminomethyl]-4-methylphenol (H 2 BPBPMP) has been synthesized and characterized. A combination of data from mass spectrometry, potentiometric titrations, X-ray absorption and electron paramagnetic resonance spectroscopy, as well as kinetics measurements indicates that in ethanol/water solutions an [Fe III -(µ)OH-Cu II OH 2 ]+ species is generated which is the likely catalyst for 2,4-bis(dinitrophenyl)phosphate and DNA hydrolysis. Insofar as the data are consistent with the presence of an Fe III -bound hydroxide acting as a nucleophile during catalysis, 1 presents a suitable mimic for the hydrolytic enzyme purple acid phosphatase. Notably, 1 is significantly more reactive than its isostructural homologues with different metal composition (Fe III M II , where M II is Zn II , Mn II , Ni II , or Fe II ). Of particular interest is the observation that cleavage of double-stranded plasmid DNA occurs even at very low concentrations of 1 (2.5 µM), under physiological conditions (optimum pH of 7.0), with a rate enhancement of 2.7×10 7 over the uncatalyzed reaction. Thus, 1 is one of the most effective model complexes to date, mimicking the function of nucleases.

Described herein is the synthesis, structure, and monoesterase and diesterase activities of a new mononuclear (2,4-BDNPP). When covalently linked to 3-aminopropyl-functionalized silica, 1 undergoes disproportionation to form a dinuclear species (APS-1), whose catalytic efficiency is increased when compared to the homogeneous reaction due to second coordination sphere effects which increase the substrate to complex association constant. The anchored catalyst APS-1 can be recovered and reused for subsequent hydrolysis reactions (five times) with only a slight loss in activity. In the presence of DNA, we suggest that 1 is also converted into the dinuclear active species as observed with APS-1, and both were shown to be efficient in DNA cleavage.

The first examples of molecular telluride complexes, W 6 Te 8 L 6 [L )pyridine (py), piperidine (pip), and PEt 3 ], and the reduced salt [Na(py) 6 ] + [W 6 Te 8 (py) 6 ] -were discovered. The amine complexes were prepared by reaction of W 6 Cl 12 with Na 2 Te or a Na 2 Te/Na 2 Te 2 mixture in the amine solvents, whereas W 6 Te 8 (PEt 3 ) 6 was established by displacement of pyridine in W 6 Te 8 (py) 6 by PEt 3 . The cluster unit, W 6 Te 8 , showed characteristic T 1u W-Te stretching vibrations around 180-200 cm -1 . From XPS the W4f 7/2 binding energy of 30.8 eV for W 6 Te 8 L 6 compared favorably with values of 30.5 and 30.8 eV for the sulfide and selenide analogues, respectively. Crystallographic data for the three compounds on which structure analyses were performed are as follows: W 6 -Te 8 (pip) 6 ‚6pip, hexagonal, R3 h, a ) 17.738(6) Å, c ) 24.318(10) Å, Z ) 3; W 6 Te 8 (PEt 3 ) 6 , monoclinic, C2/c, a ) 24.724(6) Å, b ) 19.716(4) Å, c ) 13.543(9) Å, β ) 108.56(3)°, Z ) 4; [Na(py) 6 ] + [W 6 Te 8 (py) 6 ] - ‚py, triclinic, P1 h, a ) 12.433(3) Å, b ) 12.760(2) Å, c ) 12.882(2) Å, R ) 96.78(1)°, β ) 100.03(1)°, γ ) 98.58(1)°, Z ) 1. The average W-Te bond distance of 2.753 Å is very close to the average W-W bond distance of 2.748 Å in these telluride clusters. For the anionic complex, both the small distortion of the octahedral cluster unit and the shortening of the average W-W bond distance confirmed addition of the extra electron to a bonding orbital in the reduced 21e cluster unit. Extended Hu ¨ckel MO calculations indicate that the structural distortion of the [W 6 Te 8 (py) 6 ] -anion arises from the Jahn-Teller effect on the 2 E g ground state. The unique cationic unit [Na-(py) 6 ] + is the first documented example of a sodium ion octahedrally coordinated with six pyridine molecules.

The synthesis and structures of two new isostructural mononuclear [Ln(L)(NO 3 )(H 2 O) 3 ](NO 3 ) 2 complexes, with Ln = Tb (complex 1) and Eu (complex 2), which display high activity in the hydrolysis of the substrate 2,4-bis-(dinitrophenyl)phosphate, are reported. These complexes displayed catalytic behavior similar to the mononuclear gadolinium complex [Gd(L)(NO 3 )(H 2 O) 3 ](NO 3 ) 2 previously reported by us (Inorg. Chem. 2008, 47, 2919-2921); one hydrolysis reaction in two stages where the diesterase and monoesterase activities could be monitored separately, with the first stage dependent on and the second independent of the complex concentration. Through potentiometric studies, electrospray ionization mass spectrometry (ESI-MS) analysis, and determination of the kinetic behaviors of 1 and 2 in acetonitrile/water solution, the species present in solution could be identified and suggested a dinuclear species, with one hydroxo group, as the most prominent catalyst under mild conditions. The complexes show high activity (k 1 = 7 and 18 s -1 for 1 and 2, respectively) and catalytic efficiency. Complexes 1 and 2 were found to be active toward the cleavage of plasmid DNA, and complete kinetic studies were carried out. Studies with a radical scavenger (dimethylsulfoxide) confirmed the hydrolytic action of 1 and 2 in the cleavage of DNA. Studies on the incubation of distamycin with plasmid DNA suggested that 1 and 2 are regio-specific, interacting with the minor groove of DNA. These complexes displayed luminescent properties. Complex 1 showed higher emission intensity than 2 due to a more efficient energy transfer between triplet and emission levels of terbium (T f 5 D 4 ), along with nonradiative deactivation mechanisms of the excited states of europium via multiphonon decays and the ligand-to-metal charge transfer state. Lifetime measurements of the 5 D 4 and 5 D 0 excited levels for 1 and 2, respectively, indicated the numbers of coordinated water molecules for the complexes.

In this work, we measured the metal-binding sites of natural and synthetic dihydroxyindole (DHI) melanins and their respective interactions with Fe(III) ions. Besides the two acid groups detected for the DHI system: catechol (Cat) and quinone-imine (QI), acetate groups were detected in the natural oligomer by potentiometric titrations. At acidic pH values, Fe(III) complexation with synthetic melanin was detected in an Fe(OH)(CatH2Cat) interaction. With an increase of pH, three new interactions occurred: dihydroxide diprotonated catechol, Fe(OH)2(CatH2Cat)−, dihydroxide monoprotonated catechol, [Fe(OH)2(CatHCat)]2−, and an interaction resulting from the association of one quinone-imine and a catechol group, [Fe(OH)2(Qi−)(CatHCat)]3−. In the natural melanin system, we detected the same interactions involving catechol and quinone-imine groups but also the metal interacts with acetate group at pH values lower than 4.0. Furthermore, interactions in the synthetic system were also characte...

Purple acid phosphatases (PAPs) are a group of heterovalent binuclear metalloenzymes that catalyze the hydrolysis of phosphomonoesters at acidic to neutral pH. While the metal ions are essential for catalysis, their precise roles are not fully understood. Here, the Fe(III)Ni(II) derivative of pig PAP (uteroferrin) was generated and its properties were compared with those of the native Fe(III)Fe(II) enzyme. The k cat of the Fe(III)Ni(II) derivative (approximately 60 s -1 ) is approximately 20% of that of native uteroferrin, and the Ni(II) uptake is considerably faster than the reconstitution of full enzymatic activity, suggesting a slow conformational change is required to attain optimal reactivity. An analysis of the pH dependence of the catalytic properties of Fe(III)Ni(II) uteroferrin indicates that the l-hydroxide is the likely nucleophile. Thus, the Ni(II) derivative employs a mechanism similar to that proposed for the Ga(III)Zn(II) derivative of uteroferrin, but different from that of the native enzyme, which uses a terminal Fe(III)-bound nucleophile to initiate catalysis. Binuclear Fe(III)Ni(II) biomimetics with coordination environments similar to the coordination environment of uteroferrin were generated to provide both experimental benchmarks (structural and spectroscopic) and further insight into the catalytic mechanism of hydrolysis. The data are consistent with a reaction mechanism employing an Fe(III)-bound terminal hydroxide as a nucleophile, similar to that proposed for native uteroferrin and various related isostructural biomimetics. Thus, only in the uteroferrin-catalyzed reaction are the precise details of the catalytic mechanism sensitive to the metal ion composition, illustrating the significance of the dynamic ligand environment in the protein active site for the optimization of the catalytic efficiency.

Owing to their high redox potential and availability of numerous diffusion channels in metal-organic frameworks, Prussian blue analogs (PBAs) are attractive for metal ion storage applications. Recently, vanadium ferrocyanides (VFCN) have received a great deal of attention for application in sodium-ion batteries, as they demonstrate a stable capacity with high redox potential of ~3.3 V vs. Na/Na + . Nevertheless, there have been no reports on the application of VFCN in lithium-ion batteries (LIBs). In this work, a facile synthesis of VFCN was performed using a simple solvothermal method under ambient air conditions through the redox reaction of VCl 3 with K 3 [Fe(CN) 6 ]. VFCN exhibited a high redox potential of ~3.7 V vs. Li/Li + and a reversible capacity of ~50 mAh g -1 . The differential capacity plots revealed changes in the electrochemical properties of VFCN after 50 cycles, in which the low spin of Fe ions was partially converted to high spin. Ex situ X-ray diffraction measurements confirmed the unchanged VFCN structure during cycling. This demonstrated the high structural stability of VFCN. The low cost of precursors, simplicity of the process, high stability, and reversibility of VFCN suggest that it can be a candidate for large-scale production of cathode materials for LIBs.