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Investigating the mechanism of [M-H] + ion formation in photoionized N-alkyl-substituted thieno [3, 4-c]-pyrrole-4, 6-dione derivatives during higher-order MS n high-resolution mass spectrometry
No full textInternational audienceRationale. The mechanism underlying dopant-assisted APPI's formation of ions is unclear and still under debate for many chemical classes. In this study, we reexamined the gas-phase reaction mechanisms responsible for the generation of [M-H] + precursor ions, resulting from the loss of a single hydrogen atom, in a series of N-alkyl-substituted thieno[3,4-c]-pyrrole-4,6-dione (TPD) derivatives.Methods. Atmospheric pressure photoionization along with higher-order MS/MS n using high-resolution mass spectrometry (APPI-HR-CID-MS n ) and electronic structures calculations using density functional theory were used to determine the chemical structure of observed [M-H] + ions. As a result, the higher-order MS n (n=3) experiments revealed a reversed-Diels-Alder fragmentation cleavage mechanism leading to a common fragment ion at m/z 322 from the studied [M1-5-H]+ ion species. In addition, the calculation for two chemical structure models (N-alkyl-TPD1 and N-alkyl-TPD5) revealed that the fragment structure by removing the H atom connected to the 3rd carbon atom of the N-Alkyl side chain has a more stable cyclic form compared to the linear one.Conclusions. The proposed chemical structure of the N-alkyl TPD ion species following the loss of a single hydrogen atom was revealed during APPI-HRMS-CID-MS n (n=3) experiments of the [M-H] + ion species. A hydrogen radical (H • ) abstraction from the alkyl side chain (e.g. hexyl, heptyl, octyl, 2-ethylhexyl, and nonyl) activated a rearrangement of the N-alkyl-TPD derivatives radical cation structure initiating a cyclization and forming a six-membered ring that links the oxygen atom to the 3rd carbon atom in the alkyl chain. In addition, the theoretical calculations supported the APPI-HR-CID-MS n (n=3) experiments by revealing that the proposed chemical structure resulted from the intramolecular cyclization of the N-alkyl-TPD ion species was stable in the presence of chlorobenzene. These research results will facilitate structural determination and elucidation of molecules with similar basic structures
A Computational Workflow for the Simulation of Solid State Battery Electrodes from Manufacturing to Electrochemical Performance
No full textAll-solid-state lithium batteries (ASSBs) have the potential to deliver higher energy and power densities compared to conventional lithium-ion batteries with liquid electrolytes. Due to the use of solid electrolytes, a uniform distribution and close contact between the active material (AM) and solid electrolyte (SE) particles are essential for a proper electrochemical behavior of the electrodes. Thus, understanding the correlation between the microstructure of composite electrodes, charge transport, and cell performance is critical. The composite cathode microstructure composed of Li6PS5Cl and NCM622 obtained from the simulation of its wet manufacturing process is used to implement a 4D (3 spatial coordinates, and time) computational model that simulates the electrochemical behavior during an ASSB cell discharge. The study explores the effect of the conventional calendering technique during manufacturing, demonstrating that the spatial distribution of phases and the presence of residual voids significantly influence percolation, impacting ionic and electronic conduction as well as the electrochemically active surface area. Consequently, these factors dictate the overall performance of the ASSB cell. Our findings highlight the importance of a homogeneous, compact cathode microstructure for achieving optimal ion and electron transport, ultimately enhancing the performance of ASSB cells
Assessing personalized responses to anti-PD-1 treatment using patient-derived lung tumor-on-chip
No full textInternational audienceThere is a compelling need for approaches to predict the efficacy of immunotherapy drugs. Tumor-on-chip technology exploits microfluidics to generate 3D cell co-cultures embedded in hydrogels that recapitulate simplified tumor ecosystems. Here, we present the development and validation of lung tumor-on-chip platforms to quickly and precisely measure ex vivo the effects of immune checkpoint inhibitors on T cell-mediated cancer cell death by exploiting the power of live imaging and advanced image analysis algorithms. The integration of autologous immunosuppressive FAP+ cancer-associated fibroblasts impaired the response to anti-PD-1, indicating that tumors-on-chips are capable of recapitulating stroma-dependent mechanisms of immunotherapy resistance. For a small cohort of non-small cell lung cancer patients, we generated personalized tumors-on-chips with their autologous primary cells isolated from fresh tumor samples, and we measured the responses to anti-PD-1 treatment. These results support the power of tumor-on-chip technology in immuno-oncology research and open a path to future clinical validations
Fine tuning of Nb-incorporated TiO2 thin films by atomic layer deposition and application as efficient electron transport layer in perovskite solar cells
No full textInternational audienceAccess to finely tuned thin films that can act as electron transport layer (ETL) and adapt to the absorber composition and whole cell fabrication process is key to achieve efficient perovskite-based solar cells. In this study, the growth of mixed niobium-titanium oxide (Nb-TiO2) thin films by atomic layer deposition and its use to extract photogenerated electrons is reported. Films were obtained at 200 °C from titanium (IV) i-propoxide, (t-butylimido)tris(diethylamido)niobium(V), and water by introducing Nb2O5 growth cycle in a TiO2 matrix. Process parameters (order of precursor introduction, cycle ratio) were optimized; the growth mechanism and the effective Nb incorporation were investigated by an in situ quartz crystal microbalance and x-ray photoelectron spectroscopy. The composition, morphology, structural, and optoelectronic properties of the as-deposited films were determined using a variety of characterization techniques. As a result, a fine control of the film properties (between TiO2 and Nb2O5 ones) could be achieved by tuning Nb content. To allow a successful implementation in solar devices, a comprehensive annealing study under several conditions (temperatures, various atmospheres) was conducted leading to an evolution of the optical properties due to a morphological change. Ultimately, the incorporation of these 15 nm-thick films in mesoscopic perovskite solar cells as ETL shows an improvement of the cell performances and of their stability with increasing Nb content, in comparison of both TiO2 and Nb2O5 pure compounds, reaching power conversion efficiency up to 18.3% and a stability above 80% of its nominal value after 138 h under illumination
An Easy and Adjustable One-Pot Access to Pheromonal Blends of Fall Armyworm ( Spodoptera frugiperda ) Relying on a Key Ligand- and Additive-Free Iron-Catalyzed Cross-Coupling
No full textInternational audienceWe describe in this report a convenient convergent synthesis of the pheromonal blend of Spodoptera frugiperda, relying on a key ligand-and additive-free iron-catalyzed cross-coupling operating at a low 0.1 mol% catalytic charge. This approach relies on the use of the same electrophilic partner for the preparation of the three components of the blend, which can be prepared altogether in a single step with a 94% isolated yield. Overall, the pheromonal blend is obtained with a 61% yield at a 20 g scale, with an accurate control of the distribution of its three components.</div
Unveiling polyoxometalate redox properties at the nanoscale
No full textInternational audiencePolyoxometalates (POMs) are molecular nano-oxides of early transition metals. As molecular oxides, they are endowed with remarkable redox properties, combining the reducibility of bulk metal oxides and the high versatility of molecular species. They undergo successive, reversible, and highly adjustable mono- (or multi-) electronic reduction processes within a narrow range of potentials. Furthermore, POMs are polyanions, with counter cations playing a crucial role, beyond ensuring charge neutrality. As the missing link between extended oxides, commonly found in microelectronics, and conventional organic or organometallic molecules, POMs have attracted ever-increasing interest in the field of nanoelectronics. They hold promise as charge storage nodes in multilevel nonvolatile memories and resistive switching devices, areas of interest currently boosted by the development of neuromorphic computing. In this context, we have been exploring various strategies to immobilize POMs onto electrodes with the aim of improving the control of the molecules/electrode interface. We have been investigating electron transport properties across POM-based molecular nanojunctions to establish relationships among the POM molecular structure, the electronic structure, and the properties of POM devices (e.g., conductance, switching). Additionally, we have demonstrated that we can commute the redox state of a POM layer by exposure to light or by applying an electric field, opening up new opportunities to stimuli-responsive devices
Chemo–Phototherapeutic Effect of Polyoxometalate-Stabilized Gold Nanostars for Cancer Treatment
No full textInternational audienceA reduced polyoxometalate (POM) functionalized with bisphosphonate (BP) ligands possessing antitumoral properties was used to synthesize metallic gold nanostars (AuNSs) with high reproducibility through a silver-assisted seed growth method. Notably, this study is the first to employ a reduced polyoxometalate as a dual-function reducing and capping agent in the synthesis of gold nanostars. The resulting AuNS@POM composites, characterized by a plasmon band located at 744 nm, combine in a single hybrid nanocomposite alendronate ligands, Mo(VI) ions, and Au0 centers. The colloidal stability of AuNS@POM was demonstrated in a biological culture medium, and cell experiments were performed to study its antitumoral activity on U87 and MCF7 cell lines from glioblastoma and liver cancer, respectively. First, it was established that the antitumoral activity of the BP POM is enhanced due to the Mo(V) to Mo(VI) oxidation process that occurs during AuNS formation. Second, it has been shown that in the presence of the composite, cellular metabolic activity decreases drastically under the effect of irradiation at 808 nm, even leading to almost complete cell death. AuNS@POM therefore exhibits strong antitumor chemo–photothermal activity, paving the way for the development of a type of dual therapeutic agent operating under near-infrared irradiatio
Molecular liquids and ionic solutions: From statistical mechanics modeling to experimental observations. In honor of the 80th birthday of Myroslav Holovko
No full textPhotocatalytic Asymmetric Acyl Radical Truce–Smiles Rearrangement for the Synthesis of Enantioenriched α‐Aryl Amides
No full textInternational audienceAbstract The radical Truce–Smiles rearrangement is a straightforward strategy for incorporating aryl groups into organic molecules for which asymmetric processes remains rare. By employing a readily available and non‐expensive chiral auxiliary, we developed a highly efficient asymmetric photocatalytic acyl and alkyl radical Truce–Smiles rearrangement of α‐substituted acrylamides using tetrabutylammonium decatungstate (TBADT) as a hydrogen atom–transfer photocatalyst, along with aldehydes or C−H containing precursors. The rearranged products exhibited excellent diastereoselectivities (7 : 1 to >98 : 2 d.r.) and chiral auxiliary was easily removed. Mechanistic studies allowed understanding the transformation in which density functional theory (DFT) calculations provided insights into the stereochemistry‐determining step
Engineering pore structure in silica thin films via precursor reactivity
No full textInternational audienceNovel optical functionalities1 can be achieved in thin films by controlling the structuration of scatterers at the nano/micron scale..