Halide-free CO2 cycloaddition onto styrene oxide catalysed by first row transition-metal derivatives of polyoxotungstates

Quaternary ammonium salts of metal derivatives of polyoxometalates [XW11O39M(H2O)]n- (X = P, Si; M = Cr, Mn, Co, Ni, Zn) were successfully tested instead of quaternary ammonium halides as catalysts in the cycloaddition of CO2 to styrene oxide. Remarkably, they gave very satisfactory yields of styrene carbonate at moderate temperature (80 °C).

Ready-to-be-addressed oxo-clusters: individualized, periodically organized and separated from the substrate

Clusters and oxo-clusters are drawing attention for their amazing physical properties, especially at the scale of the single molecule. However, chemical methods to organize them individually on a surface are still lacking. In this study we show that it is possible to periodically organize individual polyoxometalates thanks to their ordering by a new supramolecular assembly.

Experimental observation of the role of countercations in modulating the electrical conductance of Preyssler-type polyoxometalate nanodevices

Polyoxometalates are nanoscale molecular oxides with promising properties that are currently explored for molecule-based memory devices. In this work, we synthesize a series of Preyssler polyoxometalates (POMs), [Na⊂P₅W₃₀O₁₁₀]^14-, stabilized with four different counterions, H⁺, K⁺, NH₄⁺, and tetrabutylammonium (TBA⁺). We study the electron transport properties at the nanoscale (conductive atomic force microscopy, C-AFM) of molecular junctions formed by self-assembled monolayers (SAMs) of POMs electrostatically deposited on the ultraflat gold surface prefunctionalized with a positively charged SAM of amine-terminated alkylthiol chains. We report that the electron transport properties of P₅W₃₀-based molecular junctions depend on the nature of the counterions; the low-bias current (in the voltage range [-0.6 V; 0.6 V]) gradually increases by a factor of ∼100 by changing the counterion in the order: K⁺, NH₄⁺, H⁺ and TBA⁺. From a statistical study (hundreds of current-voltage traces) using a simple analytical model for charge transport in nanoscale devices, we show that the energy position of the lowest unoccupied molecular orbital (LUMO) of P₅W₃₀ with respect to the Fermi energy of the electrodes increases from ∼0.4 eV to ∼0.7 eV and that the electrode coupling energy also increases from ∼0.05 to 1 meV in the same order from K⁺, NH₄⁺, H⁺ to TBA⁺. We discuss several hypotheses on the possible origin of these features, such as a counterion-dependent dipole at the POM/electrode interface and counterion-modulated molecule/electrode hybridization, with, in both cases, the largest effect in the case of TBA⁺ counterions.

Multi-Electron Visible Light Photoaccumulation on a Dipyridylamine Copper(II)-Polyoxometalate Conjugate Applied to Photocatalytic Generation of CF3 Radicals

This article describes the synthesis and characterization of an organic-inorganic hybrid polyoxometalate functionalized by a short link with a tripodal N-based ligand and its copper complex. Upon visible light irradiation, the latter is able to store up to three reducing equivalents. The locus of the reduction is discussed based on physicochemical measurements and DFT calculations. In the presence of Togni's reagent, this complex allows for the photocatalytic generation of CF₃ radicals, opening the road to valuable synthetic applications.

Correction: Redox-controlled conductance of polyoxometalate molecular junctions

Correction for 'Redox-controlled conductance of polyoxometalate molecular junctions' by Cécile Huez et al., Nanoscale, 2022, 14, 13790-13800, https://doi.org/10.1039/D2NR03457C.

Redox-controlled conductance of polyoxometalate molecular junctions

We demonstrate the reversible in situ photoreduction of molecular junctions of a phosphomolybdate [PMo₁₂O₄₀]^3- monolayer self-assembled on flat gold electrodes, connected by the tip of a conductive atomic force microscope. The conductance of the one electron reduced [PMo₁₂O₄₀]^4- molecular junction is increased by ∼10, and this open-shell state is stable in the junction in air at room temperature. The analysis of a large current-voltage dataset by unsupervised machine learning and clustering algorithms reveals that the electron transport in the pristine phosphomolybdate junctions leads to symmetric current-voltage curves, controlled by the lowest unoccupied molecular orbital (LUMO) at 0.6-0.7 eV above the Fermi energy with ∼25% of the junctions having a better electronic coupling to the electrodes than the main part of the dataset. This analysis also shows that a small fraction (∼18% of the dataset) of the molecules is already reduced. The UV light in situ photoreduced phosphomolybdate junctions systematically feature slightly asymmetric current-voltage behaviors, which is ascribed to the electron transport mediated by the single occupied molecular orbital (SOMO) nearly at resonance with the Fermi energy of the electrodes and by a closely located single unoccupied molecular orbital (SUMO) at ∼0.3 eV above the SOMO with a weak electronic coupling to the electrodes (∼50% of the dataset) or at ∼0.4 eV but with a better electrode coupling (∼50% of the dataset). These results shed light on the electronic properties of reversible switchable redox polyoxometalates, a key point for potential applications in nanoelectronic devices.

Lennard-Jones interaction parameters of Mo and W in He and N2 from collision cross-sections of Lindqvist and Keggin polyoxometalate anions

Drift tube ion mobility spectrometry (DTIMS) coupled with mass spectrometry was used to determine the collision cross-sections (^DTCCS) of polyoxometalate anions in helium and nitrogen. As the geometry of the ion, more than its mass, determines the collision cross-section with a given drift gas molecule, we found that both Lindqvist ions Mo₆O₁₉^2- and W₆O₁₉^2- had a ^DTCCS_He value of 103 ± 2 Ų, and both Keggin ions PMo₁₂O₄₀^3- and PW₁₂O₄₀^3- had a ^DTCCS_He value of 170 ± 2 Ų. Similarly, ion mobility experiments in N₂ led to ^DTCCS_N2 values of 223 ± 2 Ų and 339 ± 4 Ų for Lindqvist and Keggin anions, respectively. Using optimized structures and partial charges determined from density functional theory calculations, followed by CCS calculations via the trajectory method, we determined Lennard-Jones 6-12 potential parameters ε, σ of 5.60 meV, 3.50 Å and 3.75 meV, 4.40 Å for both Mo and W atoms interacting with He and N₂, respectively. These parameters reproduced the CCS of polyoxometalates within 2% accuracy.

When Identification of the Reduction Sites in Mixed Molybdenum/Tungsten Keggin-Type Polyoxometalate Hybrids Turns Out Tricky

The mixed molybdenum/tungsten Keggin-type polyoxometalate (POM) hybrid (TBA)₄[PW₉Mo₂O₃₉{Sn(C₆H₄I)}] (TBA = tert-butylammonium) has been prepared by the reaction between [α-PW₉Mo₂O₃₉]^7– and [Cl₃Sn(C₆H₄I)] in dried acetonitrile, in the presence of tetra-n-butylammonium bromide. A further coupling reaction affords the ferrocenyl derivative (TBA)₄[PW₉Mo₂O₃₉{Sn(C₆H₄)C≡C(C₆H₄)Fc}]. The POM hybrids have been thoroughly characterized by NMR and IR spectroscopies. Electrochemical analysis confirms their ease of reduction compared to the all-W analogue, albeit with a second reduction process occurring at a lower potential than in the all-Mo species. It is noteworthy that the second reduction is accompanied by an unusual red shift of the electronic absorption spectrum. Whereas there is no doubt that the first reduction deals with Mo, the location of the second electron in the bireduced species, on the second Mo or on W, has thus been the subject of a cross-investigation by spectroelectrochemistry, electron spin resonance, and theoretical calculations. Finally, it came out that the second reduction is also Mo-centered with two unpaired and antiferromagnetically coupled extra electrons.

The sites for the successive reduction processes of a mixed molybdenum/tungsten Keggin-type organotin hybrid are debated through a combination of spectroelectrochemical investigations and theoretical calculations.

Photoactive Organic/Inorganic Hybrid Materials with Nanosegregated Donor-Acceptor Arrays

The synthesis of the first mesogenic donor-acceptor polyoxometalate (POM)-based hybrid is herein described. The structural and electronic properties of the hybrid compound were evaluated through combination of small- and wide-angle X-ray scattering, optical microscopy, electrochemistry and photoluminescence. In the solid state, the compound behaves as a birefringent solid, displaying a lamellar organization in which double-layers of POMs and bis(thiophene)thienothiophene organic donors alternate regularly. Noticeably, the sub-unit organizations in the composite are similar to that observed for the individual POM and organic donor precursors. Photophysical studies show that in the hybrid, the fluorescence of the organic donor unit is considerably quenched both in solution and in the solid state, which is attributed to occurrence of intramolecular charge-separated state.

Tuning Photoinduced Electron Transfer in POM-Bodipy Hybrids by Controlling the Environment: Experiment and Theory

The optical and electrochemical properties of a series of polyoxometalate (POM) oxoclusters decorated with two bodipy (boron-dipyrromethene) light-harvesting units were examined. Evaluated here in this polyanionic donor-acceptor system is the effect of the solvent and associated counterions on the intramolecular photoinduced electron transfer. The results show that both solvents and counterions have a major impact upon the energy of the charge-transfer state by modifying the solvation shell around the POMs. This modification leads to a significantly shorter charge separation time in the case of smaller counterion and slower charge recombination in a less polar solvent. These results were rationalized in terms of Marcus theory and show that solvent and counterion both affect the driving force for photoinduced electron transfer and the reorganization energy. This was corroborated with theoretical investigations combining DFT and molecular dynamics simulations.

Polarizability is a key parameter for molecular electronics

Identifying descriptors that govern charge transport in molecular electronics is of prime importance for the elaboration of devices. The effects of molecule characteristics, such as size, bulkiness or charge, have been widely reported. Herein, we show that the molecule polarizability can be a crucial parameter to consider. To this end, platinum nanoparticle self-assemblies (PtNP SAs) are synthesized in solution, including a series of polyoxometalates (POMs). The charge of the POM unit can be modified according to the nature of the central heteroatom while keeping its size constant. POM hybrids that display remote terminal thiol functions strongly anchor the PtNP surface to form robust SAs. IV curves, recorded by conductive AFM, show a decrease in Coulomb blockade as the dielectric constant of the POMs increases. In this system, charge transport across molecular junctions can be interpreted as variations in polarizability, which is directly related to the dielectric constant.

Acid-triggering of light-induced charge-separation in hybrid organic/inorganic molecular photoactive dyads for harnessing solar energy

H⁺ modulated charge-transfer in photoexcited covalently linked W and Mo Keggin-bodipy conjugates is demonstrated using transient absorption spectroscopy and photoluminescence. Adding acid switches on (W) or accelerates (Mo) charge separation.

[Maternal Deaths due to Amniotic Fluid Embolism in France 2013-2015]

Amniotic fluid embolism remains the 3rd cause of maternal death in France, with a stable rate and 28 deaths in this triennium, representing 10.7% of maternal deaths and a maternal mortality ratio of 1.2/100,000 live births. Cases are characterized by the suddenness of symptoms: the median delay between symptoms and death was 4h [0.75-696] with 20/28 patients did not reach the intensive care unit. Initial circulatory failure or cataclysmic haemorrhage was the two modes of presentation. Prodromes were reported in 17 (63%) cases and induction of labour was present in 12/27 (44%). One or more factors of sub-optimal care were present in 72% of the cases, and 52% of deaths were considered possibly or probably preventable. This preventability most often concerned the content of care but also the organisation of care (including human resources, communication, sites of care and referrals). The delay in establishing a well-conducted cardio-circulatory resuscitation or the delay in setting up an optimal transfusion strategy were the most frequent elements of substandard care. Absence or delay at hysterectomy during haemorrhagic situations was reported in 15/20 cases. The experts suggest being on the alert to diagnose amniotic embolism at an early stage, initiating intense resuscitation "outside the walls", envisaging a hysterectomy without delay if the haemorrhage is intense. On an organisational level, a "vital emergency maternity care" plan, specific to each establishment could be proposed.

[Indirect causes of maternal deaths (except stroke, cardiovascular diseases and infections) in France 2013-2015]

Maternal deaths from indirect obstetric causes are the result of a pre-existing disease or condition that appeared during pregnancy without obstetric causes, but which was aggravated by the physiological effects of pregnancy. Twenty-six deaths from indirect causes related to a pre-existing pathology, excluding disease of the circulatory system or infection, were analysed by the committee of experts. Pre-existing pathology during pregnancy was documented in 13 women (asthma, n=3, genetic diseases, n=3, previous breast cancer, n=2, major sickle cell syndrome, n=2, epilepsy, n=1 and brain tumour, n=1). In 13 women, the pathology was not known before pregnancy (breast cancer, n=6, brain tumours, n=3, uterine sarcoma, n=1, cervical cancer, n=1, malignant melanoma, n=1 and acute myeloid leukaemia, n=1). For 16 women (61%), the death is related to a neoplastic pathology. Although the majority were considered inevitable for 11/16 women, 5 deaths were considered possibly preventable, the main preventable factor being a delay in diagnosis, and/or a delay in starting a specific treatment. For 10 women, the death is related to a chronic non-neoplastic pathology, known before pregnancy for 9 women, judged most often as possibly preventable, the main preventable factor being the failure of the medical team or the patient to take the pathology and/or its treatment into account. A preconception medical consultation with a specialist should be recommended to all patients with pre-existing disease. A clinical examination of the breasts is strongly recommended at the first visit and then during pregnancy.

Covalent Grafting of Polyoxometalate Hybrids onto Flat Silicon/Silicon Oxide: Insights from POMs Layers on Oxides

Immobilization of polyoxometalates (POMs) onto oxides is relevant to many applications in the fields of catalysis, energy conversion/storage, or molecular electronics. Optimization and understanding the molecule/oxide interface is crucial to rationally improve the performance of the final molecular materials. We herein describe the synthesis and covalent grafting of POM hybrids with remote carboxylic acid functions onto flat Si/SiO₂ substrates. Special attention has been paid to the characterization of the molecular layer and to the description of the POM anchoring mode at the oxide interface through the use of various characterization techniques, including ellipsometry, AFM, XPS, and FTIR. Finally, electron transport properties were probed in a vertical junction configuration and energy level diagrams have been drawn and discussed in relation with the POM molecular electronic features inferred from cyclic-voltammetry, UV-visible absorption spectra, and theoretical calculations. The electronic properties of these POM-based molecular junctions are driven by the POM LUMO (d-orbitals) whatever the nature of the tether or the anchoring group.

Exploring the self-assembly of dumbbell-shaped polyoxometalate hybrids, from molecular building units to nanostructured soft materials

The formation of hierarchical nanostructures using preformed dumbbell-like species made of covalent organic-inorganic polyoxometalate (POM)-based hybrids is herein described. In this system, the presence of charged subunits (POM, metal linkers, and counter ions) in the complex molecular architecture can drive their aggregation, which results from a competition between the solvation energy of the discrete species and intermolecular electrostatic interactions. We show that the nature of the POM and the charge of the metal linker are key parameters for the hierarchical nanoorganization. The experimental findings were corroborated with a computational investigation combining DFT and molecular dynamics simulation methods, which outlines the importance of solvation of the counter ion and POM/counter ion association in the aggregation process. The dumbbell-like species can also form gels, in the presence of a poorer solvent, displaying similar nanoorganization of the aggregates. We show that starting from the designed molecular building units whose internal charges can be controlled by redox trigger we can achieve their implementation into soft nanostructured materials through the control of their supramolecular organization.

Protective Effect of Polyoxometalates in {Mo132}/Maghemite Binary Superlattices Under Annealing

The binary assembly DDA-{Mo₁₃₂}/OA-γ-Fe₂O₃ (DDA = didodecyldimethylammonium, {Mo₁₃₂} = [Mo₁₃₂O₃₇₂(CH₃COO)₃₀(H₂O)₇₂]^42-, OA = oleic acid) constitutes one of the two examples in the literature of binary superlattices made of a mixing of nanocrystals and oxo-clusters. In a precedent work, we reported in details the preparation of such magnetic binary systems and studied the effect of the nature of the polyoxometalates (POMs) on the magnetic properties. In the present paper, we study the stability of this model binary assembly under heating at various temperatures. Indeed, especially if magnetic and/or transport properties are targeted, an annealing can be essential to change the phase of the nanocrystals in a more magnetic one and/or to desorb the organic capping of the nano-objects that can constitute an obstacle to the electronic communication between the nano-objects. We gave evidence that the maghemite organization in the binary assembly is maintained until 370°C under vacuum thanks to the presence of the POMs. This latter evolve in the phase MoO₃, but still permits to avoid the aggregation of the nanocrystals as well as preserve their periodical arrangement. On the contrary, an assembly made of pure γ-Fe₂O₃ nanocrystals displays a clear aggregation of the nano-objects from 370°C, as attested by transmission and scanning electronic microscopies and confirmed by magnetic measurements. The stability of the magnetic nanocrystals in such POMs/nanocrystals assemblies opens the way to (i) the elaboration of new binary assemblies from POMs and numerous kinds of nanocrystals with a good control on the magnetic properties and to (ii) the investigation of new physical properties as exchange coupling, or magneto-transport in such systems.

Charge transport through redox active [H7P8W48O184]33- polyoxometalates self-assembled onto gold surfaces and gold nanodots

Polyoxometalates (POMs) are redox-active molecular oxides, which attract growing interest for their integration into nano-devices, such as high-density data storage non-volatile memories. In this work, we investigated the electrostatic deposition of the negatively charged [H7P8W48O184]33- POM onto positively charged 8-amino-1-octanethiol self-assembled monolayers (SAMs) preformed onto gold substrates or onto an array of gold nanodots. The ring-shaped [H7P8W48O184]33- POM was selected as an example of large POMs with high charge storage capacity. To avoid the formation of POM aggregates onto the substrates, which would introduce variability in the local electrical properties, special attention has to be paid to the preformed SAM seeding layer, which should itself be deprived of aggregates. Where necessary, rinsing steps were found to be crucial to eliminate these aggregates and to provide uniformly covered substrates for subsequent POM deposition and electrical characterizations. This especially holds for commercially available gold/glass substrates while these rinsing steps were not essential in the case of template stripped gold of very low roughness. Charge transport through the related molecular junctions and nanodot molecule junctions (NMJs) has been probed by conducting-AFM. We analyzed the current-voltage curves with different models: electron tunneling though the SAMs (Simmons model), transition voltage spectroscopy (TVS) method or molecular single energy level mediated transport (Landauer equation) and we discussed the energetics of the molecular junctions. We concluded to an energy level alignment of the alkyl spacer and POM lowest occupied molecular orbitals (LUMOs), probably due to dipolar effects.

Modeling the Oxygen Vacancy at a Molecular Vanadium(III) Silica-Supported Catalyst

Here we report on the use of a silanol-decorated polyoxotungstate, [SbW₉O₃₃( ^tBuSiOH)₃]^3- (1), as a molecular support to describe the coordination of a vanadium atom at a single-site on silica surfaces. By reacting [V(Mes)₃·thf] (Mes = 2,4,6-trimethylphenyl) with 1 in tetrahydrofuran, the vanadium(III) derivative [SbW₉O₃₃( ^tBuSiO)₃V(thf)]^3- (2) was obtained. Compound 2 displays the paramagnetic behavior expected for a d²-V^III high spin complex (SQUID measurements) with a triplet electronic ground state (ca. 30 kcal·mol^-1 more stable than the singlet, from DFT calculations). Compound 2 proves to be a reliable model for reduced isolated-vanadium atom dispersed on silica surfaces [(≡Si-O)₃V^III(OH₂)], an intermediate that is often proposed in a Mars-van Krevelen type mechanism for partial oxidation of light alcohols. Oxidation of 2 under air produced the oxo-derivative [SbW₉O₃₃( ^tBuSiO)₃VO]^3- (3). In compound 2, the d²-electrons are localized in degenerated d(V) orbitals, whereas in the electronically analogous bireduced-[SbW₉O₃₃( tBuSiO)₃VO]^5-, 3·(2e), one electron is localized on d(V) orbital and the second one is delocalized on the polyoxotungstic framework, leading to a unique case of a bireduced heteropolyanion derivative with completely decoupled d¹-V(IV) and d¹-W(V). Our body of experimental results (EPR, magnetic measurements, spectroelectrochemical studies, Raman spectroscopy) and theoretical studies highlights (i) the role of the apical ligand coordination, i.e., thf (σ-donor) vs oxo (π-donor), in destabilizing or stabilizing the d(V) orbitals relative to the d(W) orbitals, and (ii) a geometrical distortion of the O₃VO entity that causes a splitting of the degenerated orbitals and the stabilization of one d(V) orbital in the bireduced compound 3·(2e).

A calibration framework for the determination of accurate collision cross sections of polyanions using polyoxometalate standards

RATIONALE

Polyoxometalates (POMs) are remarkable oxo-clusters forming compact highly charged anions. We measured their collision cross sections (CCS) in N₂ with drift tube ion mobility spectrometry (DTIMS). These values were then used to calibrate a traveling wave ion mobility spectrometry (TWIMS) device and the accuracy of the calibration was tested.

METHODS

Six POM standards were analyzed by DTIM-MS (Tofwerk, Thun, Switzerland) at different voltages to determine absolute ^DT CCS (N₂ ) values. Five POM compounds (Lindqvist TBA₂ Mo₆ O_19; decatungstate TBA₄ W₁₀ O_32; Keggin TBA₃ PMo₁₂ O₄₀ ; TBA₃ PW₁₂ O₄₀ and Dawson TBA₆ P₂ W₁₈ O₆₂ ) were used for the calibration of the TWIM-MS instrument (Synapt G2 HDMS, Waters, Manchester, UK) and a sixth Dawson POM, TBA₉ P₂ Nb₃ W₁₅ O₆₂ , was used to compare the accuracy of the calibrations with POM or with polyalanine and dextran reference ions.

RESULTS

We determined 45 ^DT CCS (N₂ ) values at 30°C or 60°C. Fourteen ^DT CCS (N₂ ) values at 30°C were used to perform calibration of the TWIMS instrument. Better correlations were observed than when ^DT CCS values in helium from the literature were used. The accuracy tests on six ions of Dawson POM TBA₉ P₂ Nb₃ W₁₅ O₆₂ led to relative errors below 3.1% while relative errors of 3.6% to 10.1% were observed when calibration was performed with polyalanine and dextran reference ions.

CONCLUSIONS

Our novel calibration strategy for determination of CCS values of multiply negatively charged ions on TWIM-MS devices based on ^DT CCS (N₂ ) of standard POM structures covered a wider range of CCS and improved the accuracy to 2.1% relative error on average compared with 6.9% using polyalanine and dextran calibration.

Molecular signature of polyoxometalates in electron transport of silicon-based molecular junctions

Polyoxometalates (POMs) are unconventional electro-active molecules with a great potential for applications in molecular memories, providing efficient processing steps onto electrodes are available. The synthesis of the organic-inorganic polyoxometalate hybrids [PM11O39{Sn(C6H4)C[triple bond, length as m-dash]C(C6H4)N2}]3- (M = Mo, W) endowed with a remote diazonium function is reported together with their covalent immobilization onto hydrogenated n-Si(100) substrates. Electron transport measurements through the resulting densely-packed monolayers contacted with a mercury drop as a top electrode confirms their homogeneity. Adjustment of the current-voltage curves with the Simmon's equation gives a mean tunnel energy barrier ΦPOM of 1.8 eV and 1.6 eV, for the Silicon-Molecules-Metal (SMM) junctions based on the polyoxotungstates (M = W) and polyoxomolybdates (M = Mo), respectively. This follows the trend observed in the electrochemical properties of POMs in solution, the polyoxomolybdates being easier to reduce than the polyoxotungstates, in agreement with lowest unoccupied molecular orbitals (LUMOs) of lower energy. The molecular signature of the POMs is thus clearly identifiable in the solid-state electrical properties and the unmatched diversity of POM molecular and electronic structures should offer a great modularity.

Control of the hierarchical self-assembly of polyoxometalate-based metallomacrocycles by redox trigger and solvent composition

Discrete metallomacrocycles are attractive scaffolds for the formation of complex supramolecular architectures with emergent properties. We herein describe the formation of hierarchical nanostructures using preformed metallomacrocycles by coordination-driven self-assembly of a covalent organic-inorganic polyoxometalate (POM)-based hybrid. In this system, we take advantage of the presence of charged subunits (POM, metal linker, and counterions) within the metallomacrocycles, which drive their aggregation through intermolecular electrostatic interactions. We show that the solvent composition and the charge of the metal linker are key parameters that steer the supramolecular organization. Different types of hierarchical self-assemblies, zero-dimensional (0D) dense nanoparticles, and 1D worm-like nanoobjects, can be selectively formed owing to different aggregation modes of the metallomacrocycles. Finally, we report that the worm-like structures drastically enhance the solubility in water of a pyrene derivative and can act as molecular carriers.

Rapid photoinduced charge injection into covalent polyoxometalate-bodipy conjugates

Controlled design of photoactive hybrids would provide highly active materials for solar energy conversion and photo(electro) catalysis. We describe the kinetics of photoinduced electron transfer in a series of photoactive hybrids based on Keggin-type polyoxometalates (POMs) covalently grafted to bodipy photosensitizers. We show how the electronic properties and corresponding dynamics of these hybrids can be readily tuned by varying the POM metal ion, the anchoring functionalization and the spacer length. Ultrafast visible and IR transient absorption spectroscopy, supported by spectroelectrochemical measurements, reveals that photoinduced electron transfer from the bodipy chromophore to the organosilyl POM derivative occurs as rapidly as τ = 54 ps to generate a long-lived (τ = 4.8 ns) charge-separated (CS) state, making this system appropriate for applications in photoelectrochemical devices.

Self-assembly study of nanometric spheres from polyoxometalate-phenylalanine hybrids, an experimental and theoretical approach

Polyoxometalate-amino acid hybrids (POM-FandPOM-FF) self-assemble into spherical architectures with high reproducibility in several “good–bad” solvent mixtures.

Polyoxometalates in the Hofmeister series

We propose a simple experimental procedure based on the cloud point measurement of a non-ionic surfactant as a tool for (i) estimating the super-chaotropic behaviour of polyoxometalates (POMs) and for (ii) establishing a classification of POMs according to their affinity towards polar surfaces.

Lung function parameters in omalizumab responder patients: An interesting tool?

BACKGROUND

Omalizumab, an anti-IgE antibody, is used to treat patients with severe allergic asthma. The evolution of lung function parameters over time and the difference between omalizumab responder and nonresponder patients remain inconclusive. The objective of this real-life study was to compare the changes in forced expiratory volume in 1 second (FEV1) of omalizumab responders and nonresponders at 6 months.

METHODS

A multicenter analysis was performed in 10 secondary and tertiary institutions. Lung function parameters (forced vital capacity (FVC), pre- and postbronchodilator FEV1, residual volume (RV), and total lung capacity (TLC) were determined at baseline and at 6 months. Omalizumab response was assessed at the 6-month visit. In the omalizumab responder patients, lung function parameters were also obtained at 12, 18, and 24 months.

RESULTS

Mean prebronchodilator FEV1 showed improvement in responders at 6 months, while a decrease was observed in nonresponders (+0.2±0.4 L and -0.1±0.4 L, respectively, P<.01). After an improvement at 6 months, pre- and postbronchodilator FEV1 remained stable at 12, 18, and 24 months. The FEV1/FVC remained unchanged over time, but the proportion of patients with an FEV1/FVC ratio <0.7 decreased at 6, 12, 18, and 24 months (55.2%, 54.0%, 54.0%, and 44.8%, respectively, P<.05). Mean RV values decreased at 6 months but increased at 12 months and 24 months (P<.05). Residual volume/total lung capacity (RV/TLC) ratio decreased at 6 months and remained unchanged at 24 months.

CONCLUSION

After omalizumab initiation, FEV1 improved at 6 months in responder patients and then remained stable for 2 years. RV and RV/TLC improved at 6 months.

[Indirect causes of maternal deaths (except stroke, cardiovascular diseases and infections): Results from the French confidential enquiry into maternal deaths, 2010-2012]

Maternal deaths of indirect causes result of a preexisting disease or an affection appeared during the pregnancy without any relationship with obstetrical causes, but worsened by the physiological effects of pregnancy. Among the 23 deaths of indirect cause related to a preexisiting pathology, 22 (96 %) have been analyzed by the expert comity. A known or preexisting chronic disease was documented in 16 patients (sick-cell disorder, n=3, treated epilepsy, n=3, intracerebral carvenomas, n=1, multifocal glial tumor, n=1, breast cancer, n=1, systemic lupus, n=1, diabetes mellitus, n=3, antiphospholipid syndrome, n=1). For 6 women, the pathology was unknown before the pregnancy (glioblastoma, n=2, epilepsy, n=1, Ehlers-Danlos syndrome, n=1, sick-cell disorder, n=1, breast cancer, n=1). While 6 of these deaths has been evaluated as not avoidable, 13 deaths has been considered as possibly (n=12) or certainly (n=1) preventable. The main factor of avoidability was the patient's interaction with the health system (medically non advised pregnancy, lack of adherence to treatment, for example). A pre-pregnancy medical consultation with a specialist should be recommended to all patients with preexisting chronic disease, to allow a complete information about the risks of a pregnancy, treatment adaptation if needed, better adherence and multidisciplinary follow up.

Tailor-made Covalent Organic-Inorganic Polyoxometalate Hybrids: Versatile Platforms for the Elaboration of Functional Molecular Architectures

Post-functionalization of organically modified polyoxometalates (POMs) is a powerful synthetic tool to devise functional building blocks for the rational elaboration of POM-based molecular materials. In this personal account we focus on iodoaryl-terminated POM platforms, describe reliable routes to the synthesis of covalent organic-inorganic POM-based hybrids and their integration into advanced molecular architectures or multi-scale assemblies as well as their immobilization onto surfaces. Valorisation of the remarkable redox properties of POMs in the fields of artificial synthesis and molecular electronic is especially considered.