Rearrangement and decomposition pathways of bare and hydrogenated molybdenum oxysulfides in the gas phase.

Molybdenum sulfides and molybdenum oxysulfides are considered a promising and cheap alternative to platinum as a catalyst for the hydrogen evolution reaction (HER). To better understand possible rearrangements during catalyst activation, we perform collision induced dissociation experiments in the gas phase with eight different molybdenum oxysulfides, namely [Mo2O2S6]2-, [Mo2O2S6]-, [Mo2O2S5]2-, [Mo2O2S5]-, [Mo2O2S4]-, [HMo2O2S6]-, [HMo2O2S5]- and [HMo2O2S4]-, on a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. We identify fragmentation channels of the molybdenum oxysulfides and their interconnections. Together with quantum chemical calculations, the results show that [Mo2O2S4]- is a particularly stable species against further dissociation, which is reached from all starting species with relatively low collision energies. Most interestingly, H atom loss is the only fragmentation channel observed for [HMo2O2S4]- at low collision energies, which relates to potential HER activity, since two such H atom binding sites on a surface may act together to release H2. The calculations reveal that multiple isomers are often very close in energy, especially for the hydrogenated species, i.e., atomic hydrogen can bind at various sites of the clusters. S2 groups play a decisive role in hydrogen adsorption. These are further features with potential relevance for HER catalysis.

[Mo3 S13 ]2- as a Model System for Hydrogen Evolution Catalysis by MoSx : Probing Protonation Sites in the Gas Phase by Infrared Multiple Photon Dissociation Spectroscopy.

Materials based on molybdenum sulfide are known as efficient hydrogen evolution reaction (HER) catalysts. As the binding site for H atoms on molybdenum sulfides for the catalytic process is under debate, [HMo3 S13 ]- is an interesting molecular model system to address this question. Herein, we probe the [HMo3 S13 ]- cluster in the gas phase by coupling Fourier-transform ion-cyclotron-resonance mass spectrometry (FT-ICR MS) with infrared multiple photon dissociation (IRMPD) spectroscopy. Our investigations show one distinct S-H stretching vibration at 2450 cm-1 . Thermochemical arguments based on DFT calculations strongly suggest a terminal disulfide unit as the H adsorption site.

Evolution of Oxygen-Metal Electron Transfer and Metal Electronic States During Manganese Oxide Catalyzed Water Oxidation Revealed with In†Situ Soft X-Ray Spectroscopy.

Manganese oxide (MnOx ) electrocatalysts are examined herein by in situ soft X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) during the oxidation of water buffered by borate (pH 9.2) at potentials from 0.75 to 2.25 V vs. the reversible hydrogen electrode. Correlation of L-edge XAS data with previous mechanistic studies indicates MnIV is the highest oxidation state involved in the catalytic mechanism. MnOx is transformed into birnessite at 1.45 V and does not undergo further structural phase changes. At potentials beyond this transformation, RIXS spectra show progressive enhancement of charge transfer transitions from oxygen to manganese. Theoretical analysis of these data indicates increased hybridization of the Mn-O orbitals and withdrawal of electron density from the O ligand shell. In situ XAS experiments at the O K-edge provide complementary evidence for such a transition. This step is crucial for the formation of O2 from water.

Cosputtered Calcium Manganese Oxide Electrodes for Water Oxidation.

Calcium manganese oxide films were prepared by cosputter deposition from Mn and CaMnO3 targets and evaluated for their suitability as catalysts for the oxygen evolution reaction (OER). Scanning electron microscopy (SEM) revealed a compact morphology for the as-deposited films and the formation of nanorodlike features on the surfaces after annealing at 600 °C. X-ray-photoelectron-spectroscopy analysis showed that the surface oxidation state is close to +III (as in Mn2O3) for the as-deposited films and increases slightly to a mixture of III and IV after annealing occurs in dry air at 400-600 °C. Glancing-incidence X-ray diffraction (GIXRD) suggested that the CaMnxOy films are amorphous even when heated to 600 °C. However, transmission electron microscopy (TEM) showed that there is actually a polycrystalline component of the film, which best matches Mn3O4 (hausmannite with the average Mn oxidation state of ∼+2.7) but may have a slightly expanded unit cell because of the incorporation of Ca. Electrochemical analyses revealed that the as-deposited CaMnxOy films were OER-inactive. In contrast, annealing at 400 or 600 °C resulted in an increase of ∼15-fold in the current densities, which reached j ≅ 1.5 mA·cm-2 at OER overpotentials of η ≈ 550 mV in cyclic voltammetry (CV) sweeps. For the same η, annealed CaMnxOy electrodes also showed good electrochemical stabilities during 2 h of electrolysis, as rather constant steady-state current densities of j ≅ 0.4-0.5 mA·cm-2 were observed. The thicknesses and surface morphologies of the CaMnxOy films did not change during the electrochemical measurements, indicating that corrosion was negligible. In comparison with a previous study in which Ca-free thin layers of MnOx were evaluated, the results demonstrate that Ca2+ incorporation can enhance the OER activity of MnOx electrocatalysts prepared by sputter deposition. This work provides guidance for designing new electrodes for water oxidation on the basis of the abundant and nontoxic elements manganese and calcium.

Optimized synthesis and indium complex formation with the bifunctional chelator NODIA-Me.

The bifunctional chelator NODIA-Me holds promise for radiopharmaceutical development. NODIA-Me is based on the macrocycle TACN (1,4,7-triazacyclononane) and incorporates two additional methylimidazole arms for metal chelation and an acetic acid residue for bioconjugation. The original two step synthesis was less than optimal due to low yields and the requirement of semi-preparative RP-HPLC purifications. Here, the overall yield for the preparation of NODIA-Me was improved two- to five-fold via two synthetic routes using different protection/deprotection techniques. This way, it was possible (1) to prepare of NODIA-Me on multi-gram scale and (2) to avoid time-consuming HPLC purifications. Inspired by recent results with nat/68Ga3+, preliminary studies on the radiolabeling properties and complex formation of NODIA-Me with nat/111In3+ were performed. Quantitative radiochemical yields were achieved at ambient temperature providing molar activities of ∼30 MBq nmol-1, which could be increased to ∼240 MBq nmol-1 at 95 °C. At r.t., pH 5.5 was optimal for 111In-labeling, but quantitative yields were also achieved in the pH range from 5.5 to 8.2, when the reaction temperature was increased. Stability tests of 111In complexes in vitro revealed high kinetic stabilities in serum and ligand challenge experiments, which is a consequence of the formation of rigid 1 : 1 indium chelates as shown by NMR studies in solution. In summary, the new synthetic routes afford the BFC NODIA-Me in high yields and on large scale. Further, 111In complexation experiments broaden the scope of our chelating system for radiopharmaceutical applications.

Epithelioid hemangioendotheliomas of the liver and lung in children and adolescents.

Epithelioid hemangioendothelioma (EHE) is a rare, vascular sarcoma. Visceral forms arise in the liver/ lungs. We review the clinical and molecular phenotype of pediatric visceral EHE based on the case of a 9-year-old male child with EHE of the liver/lungs. His tumor expressed the EHE-specific fusion oncogene WWTR1-CAMTA1. Molecular characterization revealed a low somatic mutation rate and activated interferon signaling, angiogenesis regulation, and blood vessel remodeling. After polychemotherapy and resection of lung tumors, residual disease remained stable on oral lenalidomide. Literature review identified another 24 children with EHE of the liver/lungs. Most presented with multifocal, systemic disease. Only those who underwent complete resection achieved complete remission. Four children experienced rapid progression and died. In six children, disease remained stable for years without therapy. Two patients died from progressive EHE 21 and 24 years after first diagnosis. Natural evolution of pediatric visceral EHE is variable, and long-term prognosis remains unclear.

Biomimetic Water-Oxidation Catalysts: Manganese Oxides.

The catalytic oxidation of water to molecular oxygen is a key process for the production of solar fuels. Inspired by the biological manganese-based active site for this reaction in the enzyme Photosystem II, researchers have made impressive progress in the last decades regarding the development of synthetic manganese catalysts for water oxidation. For this, it has been especially fruitful to explore the many different types of known manganese oxides MnOx. This chapter first offers an overview of the structural, thermodynamic, and mechanistic aspects of water-oxidation catalysis by MnOx. The different test systems used for catalytic studies are then presented together with general reactivity trends. As a result, it has been possible to identify layered, mixed Mn (III/IV)-oxides as an especially promising class of bio-inspired catalysts and an attempt is made to give structure-based reasons for the good performances of these materials. In the outlook, the challenges of catalyst screenings (and hence the identification of a "best MnOx catalyst") are discussed. There is a great variety of reaction conditions which might be relevant for the application of manganese oxide catalysts in technological solar fuel-producing devices, and thus catalyst improvements are currently still addressing a very large parameter space. Nonetheless, detailed knowledge about the biological catalyst and a solid experimental basis concerning the syntheses and water-oxidation reactivities of MnOx materials have been established in the last decade and thus this research field is well positioned to make important contributions to solar fuel research in the future.

Water Oxidation Catalysis by Synthetic Manganese Oxides with Different Structural Motifs: A Comparative Study.

Manganese oxides are considered to be very promising materials for water oxidation catalysis (WOC), but the structural parameters influencing their catalytic activity have so far not been clearly identified. For this study, a dozen manganese oxides (MnOx ) with various solid-state structures were synthesised and carefully characterised by various physical and chemical methods. WOC by the different MnOx was then investigated with Ce(4+) as chemical oxidant. Oxides with layered structures (birnessites) and those containing large tunnels (todorokites) clearly gave the best results with reaction rates exceeding 1250 ${{\rm{mmol}}_{{\rm{O}}_{\rm{2}} } }$ ${{\rm{mol}}_{{\rm{Mn}}}^{ - 1} }$ h(-1) or about 50 µmolO2 m(-2) h(-1) . In comparison, catalytic rates per mole of Mn of oxides characterised by well-defined 3D networks were rather low (e.g., ca. 90 ${{\rm{mmol}}_{{\rm{O}}_{\rm{2}} } }$ ${{\rm{mol}}_{{\rm{Mn}}}^{ - 1} }$ h(-1) for bixbyite, Mn2 O3 ), but impressive if normalised per unit surface area (>100 ${{\rm{{\rm \mu} mol}}_{{\rm{O}}_{\rm{2}} } }$ m(-2) h(-1) for marokite, CaMn2 O4 ). Thus, two groups of MnOx emerge from this screening as hot candidates for manganese-based WOC materials: 1) amorphous oxides with tunnelled structures and the well-established layered oxides; 2) crystalline Mn(III) oxides. However, synthetic methods to increase surface areas must be developed for the latter to obtain good catalysis rates per mole of Mn or per unit catalyst mass.

Water oxidation catalysis by birnessite@iron oxide core-shell nanocomposites.

In this work, magnetic nanocomposite particles were prepared for water oxidation reactions. The studied catalysts consist of maghemite (γ-Fe2O3), magnetite (Fe3O4), and manganese ferrite (MnFe2O4) nanoparticles as cores coated in situ with birnessite-type manganese oxide shells and were characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, thermal, chemical, and surface analyses, and magnetic measurements. The particles were found to be of nearly spherical core-shell architectures with average diameter of 150 nm. Water oxidation catalysis was examined using Ce(4+) as the sacrificial oxidant. All core-shell particles were found to be active water oxidation catalysts. However, the activity was found to depend on a variety of factors like the type of iron oxide core, the structure and composition of the shell, the coating characteristics, and the surface properties. Catalysts containing magnetite and manganese ferrite as core materials displayed higher catalytic activities per manganese ion (2650 or 3150 mmolO2 molMn(-1) h(-1)) or per mass than nanoiron oxides (no activity) or birnessite alone (1850 mmolO2 molMn(-1) h(-1)). This indicates synergistic effects between the MnOx shell and the FeOx core of the composites and proves the potential of the presented core-shell approach for further catalyst optimization. Additionally, the FeOx cores of the particles allow magnetic recovery of the catalyst and might also be beneficial for applications in water-oxidizing anodes because the incorporation of iron might enhance the overall conductivity of the material.

Hysteroscopic treatment of uterine tumor resembling ovarian sex cord-like tumor (UTROSCT).

The decision to preserve the uterus in a young nulliparous woman with an extremely rare tumor is challenging. Uterine tumor resembling ovarian sex cord-like tumor (UTROSCT) belongs to the rarest uterine pathologies. A 22-year-old nulligravida with uterine bleeding underwent a hysteroscopic resection of an intrauterine mass presumed as grade-1 submucous myoma. According to the presence of sex cord-like differentiation and positivity for calretinin, CD99, estrogen receptor, vimentin, WT1 and Melan-A, the tumor was diagnosed as UTROSCT. After 28 months, without any adjuvant therapy, the patient is still free of recurrence. This is the youngest patient with UTROSCT reported so far, with the longest follow-up among all five cases treated via hysteroscopy. Although UTROSCT has been traditionally treated with hysterectomy (with or without bilateral salpingo-oophorectomy), no established treatment protocol for UTROSCT exists. UTROSCT shows a low-malignant potential, but metastasizing and recurrent cases occur. In light of the probably less aggressive tumor biology and with respect to the patient's autonomy, a conservative, uterus preserving treatment appears to be justified in selected cases in which close follow-up can be guaranteed. Further case reports are needed to prove the safety of organ-preserving strategy in UTROSCT.

A water-soluble tin(IV) porphyrin as a bioinspired photosensitiser for light-driven proton-reduction.

The water-soluble tin(IV) porphyrin dichlorido-5,10,15,20-tetrakis(p-carboxyphenyl)-porphyrinato-tin(IV) (SnTPPC, 1) was synthesised as a mimic of biological chlorophyll photosensitisers. In natural photosynthesis, chlorophyll pigments start the multi-electron transfer processes resulting in water-oxidation and NADP(+)-reduction. The photochemical properties of compound 1 were characterised by measuring absorption and fluorescence spectra. Electrochemical measurements in water revealed well-suited redox potentials of 1 for both proton-reduction to H2 as well as water-oxidation to O2. The tin(IV) porphyrin was then used as a photosensitiser in model systems for light-induced proton-reduction in aqueous solution, where an optimization of the experimental conditions was carried out to achieve reaction rates comparable to those found for [Ru(bipy)3](2+), a standard dye in artificial photosynthesis. By employing UV/Vis-spectroelectrochemistry, we found that the porphyrin ligand of 1 is redox non-innocent in water. A complex set of reduction reactions of the porphyrin macrocycle occurs during photocatalytic experiments involving the ligand's chlorin form as a key intermediate. On the basis of these results, a potential reaction sequence for light-driven H2-formation is formulated, where the reductive quenching of 1 forms the initial reaction step and reduced forms of 1 serve as hydride transfer agents to the H2 evolution catalyst. The spectroscopic, electrochemical and catalytic properties of SnTPPC make this compound class an attractive, affordable and easily accessible choice for photosensitisers in artificial photosynthetic systems. Finally, the detected complicated redox reactions of the porphyrin ring in water offer a possible explanation of why the chlorophylls of P680 or P700 are carefully wrapped in a water-free part of the PSII and PSI proteins.

Electronic structure and spectroscopic properties of mononuclear manganese(III) Schiff base complexes: a systematic study on [Mn(acen)X] complexes by EPR, UV/vis, and MCD spectroscopy (X = Hal, NCS).

The manganese(III) Schiff base complexes [Mn(acen)X] (H2acen: N,N'-ethylenebis(acetylacetone)imine, X: I(-), Br(-), Cl(-), NCS(-)) are considered as model systems for a combined study of the electronic structure using vibrational, UV/vis absorption, parallel-mode electron paramagnetic resonance (EPR) and low-temperature magnetic circular dichroism (MCD) spectroscopy. By variation of the co-ligand X, the influence of the axial ligand field within a given square-pyramidal coordination geometry on the UV/vis, EPR, and MCD spectra of the title compounds is investigated. Between 25000 and 35000 cm(-1), the low-temperature MCD spectra are dominated by two very intense, oppositely signed pseudo-A terms, referred to as "double pseudo-A terms", which change their signs within the [Mn(acen)X] series dependent on the axial ligand X. Based on molecular orbital (MO) and symmetry considerations, these features are assigned to π(n.b.)(s, a) → yz, z(2) ligand-to-metal charge transfer transitions. The individual MCD signs are directly determined from the calculated MOs of the [Mn(acen)X] complexes. The observed sign change is explained by an inversion of symmetry among the π(n.b.)(s, a) donor orbitals which leads to an interchange of the positive and negative pseudo-A terms constituting the "double pseudo-A term".

Reduction and protonation of Mo(IV) imido complexes with depe coligands: generation and reactivity of a S = 1/2 Mo(III) alkylnitrene intermediate.

Reduction and protonation of Mo(IV) imido complexes with diphosphine coligands constitutes the second part of the Chatt cycle for biomimetic reduction of N2 to ammonia. In order to obtain insights into the corresponding elementary reactions we synthesized the Mo(IV) ethylimido complex [Mo(CH3CN)(NEt)(depe)2](OTf)2 (2-MeCN) from the Mo(IV)-NNH2 precursor [Mo(NNH2)(OTf)(depe)2](OTf) (1). As shown by UV-vis and NMR spectroscopy, exchange of the acetonitrile ligand with one of the counterions in THF results in formation of the so far unknown complex [Mo(OTf)(NEt)(depe)2](OTf) (2-OTf). 2-MeCN and 2-OTf are studied by spectroscopy and X-ray crystallography in conjunction with DFT calculations. Furthermore, both complexes are investigated by cyclic voltammetry and spectroelectrochemistry. The complex 2-OTf undergoes a two-electron reduction in THF associated with loss of the trans ligand triflate. In contrast, 2-MeCN in acetonitrile is reduced to an unprecedented Mo(III) alkylnitrene complex [Mo(NEt)(CH3CN)(depe)2]OTf (5) which abstracts a proton from the parent Mo(IV) compound 2-MeCN, forming the Mo(III) ethylamido complex 5H and a Mo(II) azavinylidene complex 6. Compound 5 is also protonated to the Mo(III) ethylamido complex 5H in the presence of externally added acid and further reduced to the Mo(II) ethylamido complex 7. The results of this study provide further support to a central reaction paradigm of the Schrock and Chatt cycles: double reductions (and double protonations) lead to high-energy intermediates, and therefore, every single reduction has to be followed by a single protonation (and vice versa). Only in this way the biomimetic conversion of dinitrogen to ammonia proceeds on a minimum-energy pathway.

Magnetic circular dichroism spectrum of the molybdenum(V) complex [Mo(O)Cl3dppe]: C-term signs and intensities for multideterminant excited doublet states.

The molybdenum(V) complex [Mo(O)Cl(3)dppe] [dppe = 1,2-bis(diphenylphosphino)ethane] is considered as a model system for a combined study of the electronic structure using UV/vis absorption and magnetic circular dichroism (MCD) spectroscopy. In order to determine the signs and MCD C-term intensities of the chlorido → molybdenum charge-transfer transitions, it is necessary to take the splitting of the excited doublet states into sing-doublet and trip-doublet states into account. While transitions to the sing-doublet states are electric-dipole-allowed, those to the trip-doublet states are electric-dipole-forbidden. As spin-orbit coupling within the manifold of sing-doublet states vanishes, configuration interaction between the sing-doublet and trip-doublet states is required to generate the MCD C-term intensity. The most prominent feature in the MCD spectrum of [Mo(O)Cl(3)dppe] is a "double pseudo-A term", which consists of two corresponding pseudo-A terms centered at 27000 and 32500 cm(-1). These are assigned to the ligand-to-metal charge-transfer transitions from the p(π) orbitals of the equatorial chlorido ligands to the Mo d(yz) and d(xz) orbitals. On the basis of the theoretical expressions developed by Neese and Solomon (Inorg. Chem. 1999, 38, 1847-1865), a general treatment of the MCD C-term intensity of these transitions is presented that explicitly considers the multideterminant character of the excited states. The individual MCD signs are determined from the corresponding transition densities derived from the calculated molecular orbitals of the title complex (BP86/LANL2DZ).

Decomposition of Halogenated Molybdenum Sulfide Dianions [Mo3S7X6]2- (X = Cl, Br, I).

Molybdenum sulfides are considered a promising and inexpensive alternative to platinum as a catalyst for the hydrogen evolution reaction. In this study, we perform collision-induced dissociation experiments in the gas phase with the halogenated molybdenum sulfides [Mo3S7Cl6]2-, [Mo3S7Br6]2-, and [Mo3S7I6]2-. We show that the first fragmentation step for all three dianions is charge separation via loss of a halide ion. As a second step, further halogen loss competes with the dissociation of a disulfur molecule, whereas the former becomes energetically more favorable and the latter becomes less favorable from chlorine via bromine to iodine. We show that the leaving S2 group is composed of sulfur atoms from two bridging groups. These decomposition pathways differ drastically from the pure [Mo3S13]2- clusters. The obtained insight into preferred dissociation pathways of molybdenum sulfides illustrate possible reaction pathways during the activation of these substances in a catalytic environment.

Case Report: Local Treatment of a Leishmania tropica Infection in a Syrian Child with a Novel Filmogenic Preparation of Pharmaceutical Sodium Chlorite (LeiProtect®).

Cutaneous leishmaniasis (CL) frequently entails chronic skin lesions that heal only slowly. Until now, the available therapeutic options are very limited. Here, we present a case of a 5½-year-old Syrian refugee with two progressive lower-leg skin ulcers caused by Leishmania tropica. The patient received topical treatment with LeiProtect®, a newly developed, hydroxypropylcellulose-based, filmogenic gel containing nontoxic concentrations of pharmaceutical sodium chlorite. The skin lesions completely healed within 8 weeks and did not relapse during 1 year of follow-up, underlining the efficacy of this novel local therapy of CL.

Calcium manganese oxides as oxygen evolution catalysts: O2 formation pathways indicated by 18O-labelling studies.

Oxygen evolution catalysed by calcium manganese and manganese-only oxides was studied in (18)O-enriched water. Using membrane-inlet mass spectrometry, we monitored the formation of the different O(2) isotopologues (16)O(2), (16)O(18)O and (18)O(2) in such reactions simultaneously with good time resolution. From the analysis of the data, we conclude that entirely different pathways of dioxygen formation catalysis exist for reactions involving hydrogen peroxide (H(2)O(2)), hydrogen persulfate (HSO(5)(-)) or single-electron oxidants such as Ce(IV) and [Ru(III) (bipy)(3)](3+) . Like the studied oxide catalysts, the active sites of manganese catalase and the oxygen-evolving complex (OEC) of photosystem II (PSII) consist of µ-oxido manganese or µ-oxido calcium manganese sites. The studied processes show very similar (18)O-labelling behaviour to the natural enzymes and are therefore interesting model systems for in vivo oxygen formation by manganese metalloenzymes such as PSII.

[A case of idiopathic postinfantile giant cell hepatitis treated with a calcineurin inhibitor]. / Erfolgreiche Therapie einer idiopathischen postinfantilen Riesenzellhepatitis mit einem Calcineurininhibitor.

INTRODUCTION: Postinfantile giant cell hepatitis is a rare entity in adult hepatopathy caused by various etiologies that can be summarized by their characteristic giant cells in histopathologic examination. Frequently, association with autoimmune, infectious and hepatotoxic events is described. Therefore, therapy consists in treatment of underlying diseases and immunosuppression. HISTORY: We saw an 76-year-old patient due to histologically proven Postinfantile giant cell hepatitis. Despite administering budesonid as an initial attempt of treatment, no improvement in hepatitis was achieved. Hence, the patient was forwarded to us. FINDINGS: Neither regarding the patient's history nor in laboratory and serological tests, nor in histopathological analysis of liver biopsies an underlying cause of giant cell hepatitis was identified. THERAPY AND COURSE: Despite immunosuppressive therapy with glucocorticoids alone, cyclophosphamide and a monoclonal anti-CD20-antibody, giant cell hepatitis was not controlled. Hence, we started treatment with the calcineurin inhibitor Tacrolimus combined with low-dose prednisolone and thus were able to lower patient's liver values and stabilize hepatitis. CONCLUSION: The good effectiveness of tacrolimus in our patient underlines the important role of calcineurin inhibitors in treating Postinfantile giant cell hepatitis, although rarely reported to date.