Magazine Articles |
|
Bourguignon, B., Béroff, K., Bréchignac, P., Dujardin, G., Leach, S., & and Zehnacker-Rentien, A. (2017). In the wake of Physical Chemistry under irradiation: onward to the Institute of Molecular Sciences at Orsay. Histoire de la Recherche Contemporaine, 6, 16–27.
|
|
|
Piard, J., Bon, C., Jegat, C., Doré, C., Petcut, V., Montanelli, R., & Méallet-Renault, R. (2017). Thermoluminochromisme de complexes de type Cu4I4(pyridine)4. Bulletin de l’Union des Physiciens, 991, 205–224.
|
|
|
Piard, J., Gatin-Fraudet, B., Grenier, A., Maujean, T., Péault, L., & Méallet-Renault, R. (2017). Thermochromisme d’un complexe de cobalt (II). Bulletin de l’Union des Physiciens, 999, 1221–1253.
|
|
Peer-reviewed Publications |
|
Aguirregabiria, G., Marinica, D. C., Esteban, R., Kazansky, A. K., Aizpurua, J., & Borisov, A. G. (2017). Electric Field-Induced High Order Nonlinearity in Plasmonic Nanoparticles Retrieved with Time-Dependent Density Functional Theory. ACS Photonics, 4(3), 613–620.
|
|
Al Salloum, H., Saunier, J., Dazzi, A., Vigneron, J., Etcheberry, A., Marliere, C., Aymes-Chodur, C., Herry, J. M., Bernard, M., Jubeli, E., & Yagoubi, N. (2017). Characterization of the surface physico-chemistry of plasticized PVC used in blood bag and infusion tubing. Materials Science & Engineering C-Materials For Biological Applications, 75, 317–334.
Résumé: Commercial infusion tubing and blood storage devices (tubing, blood and platelets bags) made of plasticized PVC were analyzed by spectroscopic, chromatographic and microscopic techniques in order to identify and quantify the additives added to the polymer (lubricants, thermal stabilizers, plasticizers) and to put into evidence their blooming onto the surface of the devices. For all the samples, deposits were observed on the surface but with different kinds of morphologies. Ethylene bis amide lubricant and metallic stearate stabilizers were implicated in the formation of these layers. In contact with aqueous media, these insoluble deposits were damaged, suggesting a possible particulate contamination of the infused solutions. (C) 2017 Elsevier B.V. All rights reserved.
|
|
|
Alarcón, L. S., Cristina, L. J., Jia, J., Chen, L., Giglia, A., Pasquali, L., Sánchez, E. A., Esaulov, V. A., & Grizzi, O. (2017). Adsorption and thermal stability of 1,4 benzenedimethanethiol on InP(110). Surface Science, 664, 101–109.
|
|
Alata, I., Perez-Mellor, A., Ben Nasr, F., Scuderi, D., Steinmetz, V., Gobert, F., Jaidane, N. E., & Zehnacker-Rentien, A. (2017). Does the Residues Chirality Modify the Conformation of a Cyclo-Dipeptide? Vibrational Spectroscopy of Protonated Cyclo-diphenylalanine in the Gas Phase. J. Phys. Chem. A, 121(38), 7130–7138.
Résumé: The structure of a protonated diketopiperazine dipeptide, cyclo-diphenylalanine, is studied by means of infrared multiple photon dissociation spectroscopy combined with quantum chemical calculations. Protonation exclusively occurs on the oxygen site and, in the most stable conformer, results to an intramolecular OH center dot center dot center dot pi interaction, accompanied by a CH-pi interaction. Higher energy conformers with free OH and NH center dot center dot center dot pi interactions are observed as well, due to kinetic trapping. Optimization of the intramolecular interactions involving the aromatic ring dictates the geometry of the benzyl substituents. Changing the chirality of one of the residues has consequences on the CH center dot center dot center dot pi interaction, which is of C alpha H center dot center dot center dot pi nature for LD, while LL shows a C beta H center dot center dot center dot pi interaction. Higher-energy conformers also display some differences in the nature of the intramolecular interactions.
|
|
|
Alyabyeva, N., Ouvrard, A., Lindfors-Vrejoiu, I., Ageev, O., & McGrouther, D. (2017). Back-scattered electron visualization of ferroelectric domains in a BiFeO3epitaxial film. Appl. Phys. Lett., 111(22), 222901.
|
|
Aykac, A., Noiray, M., Malanga, M., Agostoni, V., Casas-Solvas, J. M., Fenyvesi, E., Gref, R., & Vargas-Berenguel, A. (2017). A non-covalent “click chemistry” strategy to efficiently coat highly porous MOF nanoparticles with a stable polymeric shell. Biochimica Et Biophysica Acta-General Subjects, 1861(6), 1606–1616.
Résumé: Background: Metal-organic framework nanoparticles (nanoMOFs) are biodegradable highly porous materials with a remarkable ability to load therapeutic agents with a wide range of physico-chemical properties. Engineering the nanoMOFs surface may provide nanoparticles with higher stability, controlled release, and targeting abilities. Designing postsynthetic, non-covalent self-assembling shells for nanoMOFs is especially appealing due to their simplicity, versatility, absence of toxic byproducts and minimum impact on the original host-guest ability. Methods: In this study, several beta-cyclodextrin-based monomers and polymers appended with mannose or rhodamine were randomly phosphorylated, and tested as self-assembling coating building blocks for iron trimesate MIL-100(Fe) nanoMOFs. The shell formation and stability were studied by isothermal titration calorimetry (ITC), spectrofluorometry and confocal imaging. The effect of the coating on tritium-labeled AZT-PT drug release was estimated by scintillation counting. Results: Shell formation was conveniently achieved by soaking the nanoparticles in self-assembling agent aqueous solutions. The grafted phosphate moieties enabled a firm anchorage of the coating to the nanoMOFs. Coating stability was directly related to the density of grafted phosphate groups, and did not alter nanoMOFs morphology or drug release kinetics. Conclusion: An easy, fast and reproducible non-covalent functionalization of MIL-100(Fe) nanoMOFs surface based on the interaction between phosphate groups appended to beta-cyclodextrin derivatives and iron(III) atoms is presented. General significance: This study proved that discrete and polymeric phosphatep-cyclodextrin derivatives can conform non-covalent shells on iron(III)-based nanoMOFs. The flexibility of the beta-cyclodextrin to be decorated with different motifs open the way towards nanoMOFs modifications for drug delivery, catalysis, separation, imaging and sensing. This article is part of a Special Issue entitled “Recent Advances in Bionanomaterials” Guest Editors: Dr. Marie-Louise Saboungi and Dr. Samuel D. Bader. (C) 2017 Elsevier B.V. All rights reserved.
|
|
Babilotte, P., Coudert, L. H., Billard, F., Hertz, E., Faucher, O., & Lavorel, B. (2017). Experimental and theoretical study of free induction decay of water molecules induced by terahertz laser pulses. PRA, 95(4), 043408.
Résumé: We experimentally investigate the free induction decay in the asymmetric top molecule H2O after interaction with short terahertz pulses. Two different experimental techniques are used to perform measurements in the gas phase under different experimental conditions: electro-optical detection and terahertz field-induced second-harmonic generation. Simulations of the free induction decay signals are performed with a theoretical approach in which the absorption and dispersion coefficients are evaluated from spectroscopic data pertaining to the water molecule. Experimental and theoretical signals are compared directly in the time domain in two limiting cases. For a short propagation length of ∼40 cm, both signals show a slightly altered electric field consistent with the approximation of weak absorption and dispersion. For a longer propagation length of ∼300 cm, the electric field is heavily distorted. A good agreement between experimental and calculated signals is obtained in both cases. Finally, we discuss the advantages and/or disadvantages of the two experimental techniques.
|
|
|
Bailly, A., Sitja, G., Saint-Lager, M. - C., Le Moal, S., Leroy, F., De Santis, M., Henry, C. R., & Robach, O. (2017). Influence of palladium on the ordering, the final size and composition of Pd-Au nanoparticle arrays. J. Phys. Chem. C, 121, 25864–25874.
|
|
Bergeron, H., Czuchry, E., Gazeau, J. - P., & Malkiewicz, P. (2017). Spectral properties of the quantum Mixmaster universe. Physical Review D, 96(4), 043521.
Résumé: We study the spectral properties of the anisotropic part of the Hamiltonian entering the quantum dynamics of the Mixmaster universe. We derive the explicit asymptotic expressions for the energy spectrum in the limit of large and small volumes of the universe. Then, we study the threshold condition between both regimes. Finally, we prove that the spectrum is purely discrete for any volume of the universe. Our results validate and improve the known approximations to the anisotropy potential. They should be useful for any approach to the quantization of the Mixmaster universe.
|
|
Blancard C., Cubaynes D., Guilbaud S., & and Bizau J.-M. (2017). L -shell photoionization of Mn 5+ to Mn 8+ ions. PHYSICAL REVIEW A, 96, 013410.
Résumé: Resonant photoionization cross sections of Mnn+ (n=5 to 8) ions are measured in absolute values in the photon energy range of the 2p→3d transitions (645-690eV)using a merged-beams setup at the SOLEIL synchrotron radiation facility. The experimental cross sections are compared to calculations we performed using a multiconfiguration Dirac-Fock code and the opas code dedicated to radiative opacity calculations of hot and dense plasmas. Both calculations reproduce the measurements well.
|
|
Boudjemaa, R., Briandet, R., Fontaine-Aupart, M. P., & Steenkeste, K. (2017). How do fluorescence spectroscopy and multimodal fluorescence imaging help to dissect the enhanced efficiency of the vancomycin-rifampin combination against Staphylococcus aureus infections? Photochemical & Photobiological Sciences, 16(9), 1391–1399.
Résumé: Staphylococcus aureus is one of the most frequent pathogens responsible for biofilm-associated infections. Among current clinical antibiotics, very few enable long-term successful treatment. Thus, it becomes necessary to better understand antibiotic failures and successes in treating infections in order to master the use of proper antibiotic therapies. In this context, we took benefit from a set of fluorescence spectroscopy and imaging methods, with the support of conventional microbiological tools to better understand the vancomycin-rifampin combination (in) efficiency against S. aureus biofilms. It was shown that both antibiotics interacted by forming a complex. This latter allowed a faster penetration of the drugs before dissociating from each other to interact with their respective biological targets. However, sufficiently high concentrations of free vancomycin should be maintained, either by increasing the vancomycin concentration or by applying repetitive doses of the two drugs, in order to eradicate rifampin-resistant mutants.
|
|
Boudjemaa, R., Briandet, R., Steenkeste, K., & Fontaine-Aupart, M. - P. (2017). Taking advantage of fluorescent-based tools to puzzle out successes and failures of antibiotics to inactivate infectious bacteria. Encyclopedia of Analytical Chemistry, , 1–18.
Résumé: In microbiology, fluorescence tools have undoubtedly proven their performance to analyze in real-time, non-invasively and quantitatively, the structure, composition, processes, and dynamics of microbial communities. Importantly, the available fluorescence-based methods enable to decipher multiscale events implicated in the failures and successes of antibiotics treatments. The goal of this article is to review the large range of fluorescence techniques and probes and their interest (i) to study bacterial cells viability in vitro and in vivo under antibiotics exposure, (ii) to elucidate the mechanisms of action of these drugs, and (iii) to dissect bacterial mechanisms to resist and tolerate antibiotics action.
|
|
Bouissou, A., Proag, A., Bourg, N., Pingris, K., Cabriel, C., Balor, S., Mangeat, T., Thibault, C., Vieu, C., Dupuis, G., Fort, E., Leveque-Fort, S., Maridonneau-Parini, I., & Poincloux, R. (2017). Podosome Force Generation Machinery: A Local Balance between Protrusion at the Core and Traction at the Ring. Acs Nano, 11(4), 4028–4040.
Résumé: Determining how cells generate and trans duce mechanical forces at the nanoscale is a major technical challenge for the understanding of numerous physiological and pathological processes. Podosomes are submicrometer cell structures with a columnar F-actin core surrounded by a ring of adhesion proteins, which possess the singular ability to protrude into and probe the extracellular matrix. Using protrusion force microscopy, we have previously shown that single podosomes produce local nanoscale protrusions on the extracellular environment. However, how cellular forces are distributed to allow this protruding mechanism is still unknown. To investigate the molecular machinery of protrusion force generation, we performed mechanical simulations and developed quantitative image analyses of nanoscale architectural and mechanical measurements. First, in silico modeling showed that the deformations of the substrate made by podosomes require protrusion forces to be balanced by local traction forces at the immediate core periphery where the adhesion ring is located. Second, we showed that three-ring proteins are required for actin polymerization and protrusion force generation. Third, using DONALD, a 3D nanoscopy technique that provides 20 nm isotropic localization precision, we related force generation to the molecular extension of talin within the podosome ring, which requires vinculin and paxillin, indicating that the ring sustains mechanical tension. Our work demonstrates that the ring is a site of tension, balancing protrusion at the core. This local coupling of opposing forces forms the basis of protrusion and reveals the podosome as a nanoscale autonomous force generator.
|
|
Broquier, M., Soorkia, S., Pino, G., Dedonder-Lardeux, C., Jouvet, C., & Gregoire, G. (2017). Excited State Dynamics of Cold Protonated Cytosine Tautomers: Characterization of Charge Transfer, Intersystem Crossing, and Internal Conversion Processes. J. Phys. Chem. A, 121(34), 6429–6439.
Résumé: Charge transfer reactions are ubiquitous in chemical reactivity and often viewed as ultrafast processes. For DNA, femtochemistry has undeniably revealed the primary stage of the deactivation dynamics of the locally excited state following electronic excitation. We here demonstrate that the full time scale excited state dynamics can be followed up to milliseconds through an original pump-probe photodissociation scheme applied to cryogenic ion spectroscopy. Protonated cytosine is chosen as a benchmark system in which the locally excited (1)pipi* state decays in the femtosecond range toward long-lived charge transfer and triplet states with lifetimes ranging from microseconds to milliseconds, respectively. A three-step mechanism ((1)pipi* --> (1)CT --> (3)pipi*) is proposed where internal conversion from each state can occur leading ultimately to fragmentation in the ground electronic state.
|
|
|
Cao, S., Le Moal, E., Bigourdan, F., Hugonin, J. - P., Greffet, J. - J., Drezet, A., Huant, S., Dujardin, G., & Boer-Duchemin, E. (2017). Revealing the spectral response of a plasmonic lens using low-energy electrons. Phys. Rev. B, 96, 115419.
|
|
|
Carlos, M., Gruson, O., Richard, C., Boudon, V., Rotger, M., Thomas, X., Maul, C., Sydow, C., Domanskaya, A., Georges, R., Soulard, P., Pirali, O., Goubet, M., Asselin, P., & Huet, T. R. (2017). High-resolution spectroscopy and global analysis of CF4 rovibrational bands to model its atmospheric absorption. Journal of Quantitative Spectroscopy and Radiative Transfer, 201(Supplement C), 75–93.
|
|
Cartry G., Kogut D., Achkasov K., Layet J.M., Farley T., Gicquel A., Achard J., Brinza O., Bieber T., Khemliche H., Roncin P., & Simonin A. (2017). Alternative solutions to caesium in negative-ion sources: a study of negative-ion surface production on diamond in H2/D2 plasmas. New J. Phys., 19(2), 025010.
Résumé: This paper deals with a study of H−/D− negative ion surface production on diamond in low pressure
H2/D2 plasmas. A sample placed in the plasma is negatively biased with respect to plasma potential.
Upon positive ion impacts on the sample, some negative ions are formed and detected according to
their mass and energy by a mass spectrometer placed in front of the sample. The experimental
methods developed to study negative ion surface production and obtain negative ion energy and angle
distribution functions are first presented. Different diamond materials ranging from nanocrystalline
to single crystal layers, either doped with boron or intrinsic, are then investigated and compared with
graphite. The negative ion yields obtained are presented as a function of different experimental
parameters such as the exposure time, the sample bias which determines the positive ion impact
energy and the sample surface temperature. It is concluded from these experiments that the electronic
properties of diamond materials, among them the negative electron affinity, seem to be favourable for
negative-ion surface production. However, the negative ion yield decreases with the plasma induced
defect density.
|
|
Chamakhi, R., Puthumpally-Joseph, R., Telmini, M., & Charron, E. (2017). Extracting spectroscopic molecular parameters from short pulse photo-electron angular distributions. J. Chem. Phys., 147(14), 144304.
Résumé: Using a quantum wave packet simulation including the nuclear and electronic degrees of freedom, we investigate the femtosecond and picosecond energy- and angle-resolved photoelectron spectra of the E(Sigmag+1) electronic state of Li2. We find that the angular distributions of the emitted photoelectrons depend strongly on the pulse duration in the regime of ultrashort laser pulses. This effect is illustrated by the extraction of a time-dependent asymmetry parameter whose variation with pulse duration can be explained by an incoherent average over different ion rotational quantum numbers. We then derive for the variation of the asymmetry parameter a simple analytical formula, which can be used to extract the asymptotic CW asymmetry parameters of individual transitions from measurements performed with ultra-short pulses.
|
|
Chan, A. J., Sarkar, P., Gaboriaud, F., Fontaine-Aupart, M. P., & Marliere, C. (2017). Control of interface interactions between natural rubber and solid surfaces through charge effects: an AFM study in force spectroscopic mode. Rsc Advances, 7(69), 43574–43589.
Résumé: This work presents a detailed investigation of interface interactions between natural rubber (NR) particles and solid surfaces in aqueous mediumat high ionic strength (0.1 M) using AFM in fast force spectroscopy mode. In this study, an original method for fixing the NR on the substrate was developed. This avoided the usual perturbations common in standard immobilization techniques. We proved that the adhesion process of the NR is monitored by slight changes in the surface charge state of the contacting solid surfaces made of silicon oxide or silicon nitride. The results were interpreted using Dynamic Force Spectroscopy theory, with the introduction of a supplementary term describing the electrostatic energy. Furthermore, these experiments revealed that adhesion between NR and tip was time dependent in a cumulative process. In addition, an increase of the adhesion between NR and AFM tip with the size of the rubber particles was measured. This was related to the higher concentration in lipids versus proteins for larger NR particles. These results are of great importance both for practical applications in solution-based industrial processes and to the fundamental knowledge of adhesion process involved for biopolymers or living cells.
|
|
Chartrand, A. M., McCormack, E. F., Jacovella, U., Holland, D. M. P., Gans, B., Tang, X., Garcia, G. A., Nahon, L., & Pratt, S. T. (2017). Photoelectron angular distributions from rotationally resolved autoionizing states of N2. The Journal of Chemical Physics, 147(22), 224303.
Résumé: The single-photon, photoelectron-photoion coincidence spectrum of N2 has been recorded at high (∼1.5 cm−1) resolution in the region between the N2+X2Σg+, v+ = 0 and 1 ionization thresholds by using a double-imaging spectrometer and intense vacuum-ultraviolet light from the Synchrotron SOLEIL. This approach provides the relative photoionization cross section, the photoelectron energy distribution, and the photoelectron angular distribution as a function of photon energy. The region of interest contains autoionizing valence states, vibrationally autoionizing Rydberg states converging to vibrationally excited levels of the N2+X2Σg+ ground state, and electronically autoionizing states converging to the N2+A2Π and B 2Σu+ states. The wavelength resolution is sufficient to resolve rotational structure in the autoionizing states, but the electron energy resolution is insufficient to resolve rotational structure in the photoion spectrum. A simplified approach based on multichannel quantum defect theory is used to predict the photoelectron angular distribution parameters, β, and the results are in reasonably good agreement with experiment.
|
|
Choi, D. - J., Robles, R., Yan, S., Burgess, J. A. J., Rolf-Pissarczyk, S., Gauyacq, J. - P., Lorente, N., Ternes, M., & Loth, S. (2017). Building Complex Kondo Impurities by Manipulating Entangled Spin Chains. Nano Lett., 17(10), 6203–6209.
Résumé: The creation of molecule-like structures in which magnetic atoms interact controllably is full of potential for the study of complex or strongly correlated systems. Here, we create spin chains in which a strongly correlated Kondo state emerges from magnetic coupling of transition-metal atoms. We build chains up to ten atoms in length by placing Fe and Mn atoms on a Cu2N surface with a scanning tunneling microscope. The atoms couple antiferromagnetically via superexchange interaction through the nitrogen atom network of the surface. The emergent Kondo resonance is spatially distributed along the chain. Its strength can be controlled by mixing atoms of different transition metal elements and manipulating their spatial distribution. We show that the Kondo screening of the full chain by the electrons of the nonmagnetic substrate depends on the interatomic entanglement of the spins in the chain, demonstrating the prerequisites to build and probe spatially extended strongly correlated nanostructures.
|
|
Correa-Puerta, J., Del Campo, V., Henriquez, R., Esaulov, V. A., Hamoudi, H., Flores, M., & Haberle, P. (2017). Unoccupied Interface and Molecular States in Thiol and Dithiol Monolayers. Langmuir, 33(43), 12056–12064.
Résumé: The electronic structure of self-assembled monolayers (SAMs) formed by thiols of different lengths and dithiol molecules bound to Au(111) has been characterized. Inverse photoemission spectroscopy (IPES) and density functional theory have been used to describe the molecule/Au substrate system. All molecular layers display a clear signal in the IPES data at the edge of the lowest unoccupied system orbital (LUSO), roughly 3 eV above the Fermi level. There is also evidence, in both the experimental data and the calculation, of a finite density of states just below the LUSO edge, which has been recognized as localized at the Au-substrate interface. Regardless of the molecular lengths and in addition to this induced density of interface states, an apparent antibonding Au-S state has been identified in the IPES data for both molecular systems. The main difference between the electronic structures of thiol and dithiol SAMs is a shift in the energy of the antibonding state.
|
|
Costa-Gouveia, J., Pancani, E., Jouny, S., Machelart, A., Delorme, V., Salzano, G., Iantomasi, R., Piveteau, C., Queval, C. J., Song, O. R., Flipo, M., Deprez, B., Saint-Andre, J. P., Hureaux, J., Majlessi, L., Willand, N., Baulard, A., Brodin, P., & Gref, R. (2017). Combination therapy for tuberculosis treatment: pulmonary administration of ethionamide and booster co-loaded nanoparticles. Scientific Reports, 7, 5390.
Résumé: Tuberculosis (TB) is a leading infectious cause of death worldwide. The use of ethionamide (ETH), a main second line anti-TB drug, is hampered by its severe side effects. Recently discovered “booster” molecules strongly increase the ETH efficacy, opening new perspectives to improve the current clinical outcome of drug-resistant TB. To investigate the simultaneous delivery of ETH and its booster BDM41906 in the lungs, we co-encapsulated these compounds in biodegradable polymeric nanoparticles (NPs), overcoming the bottlenecks inherent to the strong tendency of ETH to crystallize and the limited water solubility of this Booster. The efficacy of the designed formulations was evaluated in TB infected macrophages using an automated confocal high-content screening platform, showing that the drugs maintained their activity after incorporation in NPs. Among tested formulations, “green” beta-cyclodextrin (pCD) based NPs displayed the best physico-chemical characteristics and were selected for in vivo studies. The NPs suspension, administered directly into mouse lungs using a Microsprayer (R), was proved to be well-tolerated and led to a 3-log decrease of the pulmonary mycobacterial load after 6 administrations as compared to untreated mice. This study paves the way for a future use of pCD NPs for the pulmonary delivery of the [ETH: Booster] pair in TB chemotherapy.
|
|
Coudert, L. H. (2017). Optimal orientation of an asymmetric top molecule with terahertz pulses. The Journal of Chemical Physics, 146(2), 024303.
Résumé: Terahertz pulses effects are investigated in an asymmetric top C2v molecule using numerical simulations. The average value of the direction cosine ΦZxΦZx is computed solving the time dependent Schrödinger equation for several types of pulses. The H2S molecule taken as a test case is first subject to two short terahertz pulses with a duration smaller than 5 ps, an identical maximum value of the electric field of 2 MV/cm, but a different shape. The thermal average ⟨⟨ΦZx⟩⟩⟨⟨ΦZx⟩⟩ is calculated for several temperatures, and non-periodic time variations are found even for the lowest temperature. For a given temperature, the maximum orientation achieved is shown to be dependent on the overlap between the absorption spectrum of the molecule and the Fourier transform of the pulse. The maximum orientation is also shown to be closely related to the molecular energy increase. In a second step, the optimal control theory is used to build a 14 ps long few-cycle pulse with the same maximum value of the electric field allowing us to reach a large maximum value of ⟨ΦZx⟩⟨ΦZx⟩ equal to 0.93. A fairly good understanding of the wavefunction describing the molecule after the pulse was achieved.
|
|
Dajkovic, A., Tesson, B., Chauhan, S., Courtin, P., Keary, R., Flores, P., Marliere, C., Filipe, S. R., Chapot-Chartier, M. P., & Carballido-Lopez, R. (2017). Hydrolysis of peptidoglycan is modulated by amidation of meso-diaminopimelic acid and Mg2+ in Bacillus subtilis. Molecular Microbiology, 104(6), 972–988.
Résumé: The ability of excess Mg2+ to compensate the absence of cell wall related genes in Bacillus subtilis has been known for a long time, but the mechanism has remained obscure. Here, we show that the rigidity of wild-type cells remains unaffected with excess Mg2+, but the proportion of amidated meso-diaminopimelic (mDAP) acid in their peptidoglycan (PG) is significantly reduced. We identify the amidotransferase AsnB as responsible for mDAP amidation and show that the gene encoding it is essential without added Mg2+. Growth without excess Mg2+ causes asnB mutant cells to deform and ultimately lyse. In cell regions with deformations, PG insertion is orderly and indistinguishable from the wild-type. However, PG degradation is unevenly distributed along the sidewalls. Furthermore, asnB mutant cells exhibit increased sensitivity to antibiotics targeting the cell wall. These results suggest that absence of amidated mDAP causes a lethal deregulation of PG hydrolysis that can be inhibited by increased levels of Mg2+. Consistently, we find that Mg2+ inhibits autolysis of wild-type cells. We suggest that Mg2+ helps to maintain the balance between PG synthesis and hydrolysis in cell wall mutants where this balance is perturbed in favor of increased degradation.
|
|
Dartois, E., Chabot, M., Pino, T., Béroff, K., Godard, M., Severin, D., Bender, M., & Trautmann, C. (2017). Swift heavy ion irradiation of interstellar dust analogues. A&A, 599, A130.
Résumé: Context. Interstellar dust grain particles are immersed in vacuum ultraviolet (VUV) and cosmic ray radiation environments influencing their physicochemical composition. Owing to the energetic ionizing interactions, carbonaceous dust particles release fragments that have direct impact on the gas phase chemistry.
Aims. The exposure of carbonaceous dust analogues to cosmic rays is simulated in the laboratory by irradiating films of hydrogenated amorphous carbon interstellar analogues with energetic ions. New species formed and released into the gas phase are explored.
Methods. Thin carbonaceous interstellar dust analogues were irradiated with gold (950 MeV), xenon (630 MeV), and carbon (43 MeV) ions at the GSI UNILAC accelerator. The evolution of the dust analogues is monitored in situ as a function of fluence at 40, 100, and 300 K. Effects on the solid phase are studied by means of infrared spectroscopy complemented by simultaneously recording mass spectrometry of species released into the gas phase.
Results. Specific species produced and released under the ion beam are analyzed. Cross sections derived from ion-solid interaction processes are implemented in an astrophysical context.
|
|
Dartois, E., Jallat, A., Alata, I., Gavilan, L., Cruz-Diaz, G. A., Chabot, M., Beroff, K., & Muñoz Caro, G. M. (2017). UV Photolysis of Hydrogenated Amorphous Carbons of Astrophysical Interest. Polycyclic Aromatic Compounds, 37(2-3), 94–100.
Résumé: TIn the gas phase, most of the ionized or neutral molecules detected in the interstellar and circumstellar media contain at least one carbon atom. Carbon chemistry plays thus a dominant role in the understanding of the structure and evolution of the interstellar medium (ISM). One particular zone of interest to observe small carbonaceous radicals and molecules, are the sharp molecular clouds edges exposed to energetic photons. These photon-dominated regions are rich in these hydrocarbons (like CCH, c-C3H2, C4H), and provide tests for the chemistry models in the diffuse to molecular transition. The pure gas phase models generally fail in reproducing the abundance of many of the observed species, and several authors suggest such abundances may arise from the products of the VUV photodissociation of carbonaceous grains or PAHs. Hydrogenated amorphous carbons (a-C:H or HAC), abundantly observed in the ISM, could also be at the origin of many of these small carbonaceous radicals. Experimentally, this work investigates the production and release of hydrocarbons from the VUV photolysis of a-C:H interstellar analogues under ultra-high vacuum. The experimental results are applied to a Photon Dominated Region model to constrain the impact of this release on the observed gas phase species.
|
|
Debiossac, M., Atkinson, P., Zugarramurdi, A., Eddrief, M., Finocchi, F., Etgens, V. H., Momeni, A., Khemliche, H., Borisov, A. G., & Roncin, P. (2017). Fast atom diffraction inside a molecular beam epitaxy chamber, a rich combination. Appl. Surf. Sci., 391, 53–58.
Résumé: brief oveview of the benefit of having a grazing incidence fast atom diffraction (GIFAD) setup inside a molecular beam eppitaxy setup.
|
|
Demaison, J., Craig, N. C., Gurusinghe, R., Tubergen, M. J., Rudolph, H. D., Coudert, L. H., Szalay, P. G., & Császár, A. G. (2017). Fourier Transform Microwave Spectrum of Propene-3-d1 (CH2═CHCH2D), Quadrupole Coupling Constants of Deuterium, and a Semiexperimental Equilibrium Structure of Propene. The Journal of Physical Chemistry A, 121(16), 3155–3166.
Résumé: The ground-state rotational spectrum of propene-3-d1, CH2═CHCH2D, was measured by Fourier transform microwave spectroscopy. Transitions were assigned for the two conformers, one with the D atom in the symmetry plane (S) and the other with the D atom out of the plane (A). The energy difference between the two conformers was calculated to be 6.5 cm–1, the S conformer having lower energy. The quadrupole hyperfine structure due to deuterium was resolved and analyzed for both conformers. The experimental quadrupole coupling and the centrifugal distortion constants compared favorably to their ab initio counterparts. Ground-state rotational constants for the S conformer are 40582.157(9), 9067.024(1), and 7766.0165(12) MHz. Ground-state rotational constants for the A conformer are 43403.75(3), 8658.961(2), and 7718.247(2) MHz. For the A conformer, a small tunneling splitting (19 MHz) due to internal rotation was observed and analyzed. Using the new rotational constants of this work as well as those previously determined for the 13C species and for some deuterium-substituted species from the literature, a new semiexperimental equilibrium structure was determined and its high accuracy was confirmed. The difficulty in obtaining accurate coordinates for the out-of-plane hydrogen atom is discussed.
|
|
Douix S., Duflot D., Cubaynes D., Bizau J.M., & and Giuliani A. (2017). Photoionization of the Buckminsterfullerene Cation. J. Phys. Chem. Lett, 8(1), 7–12.
Résumé: Photoionization of a buckminsterfullerene ion is investigated using an ion trap and a merged beam setup coupled to synchrotron radiation beamlines and compared to theoretical calculations. Absolute measurements derived from the ion trap experiment allow discrepancies concerning the photoionization cross section of C60+ to be solved.
|
|
Feng, X. R., Ding, J. X., Gref, R., & Chen, X. S. (2017). Poly(beta-cyclodextrin)-mediated polylactide-cholesterol stereocomplex micelles for controlled drug delivery. Chinese Journal Of Polymer Science, 35(6), 693–699.
Résumé: A series of host-guest interaction-adjusted polylactide stereocomplex micelles was prepared via the self-assembly of 4-armed poly(ethylene glycol)-block-poly(L-lactide/D-lactide)-cholesterol (4-armed PEG-b-PLLA/PDLA-CHOL) and poly(beta-cyclodextrin) (PCD) with the molar ratios of CHOL/beta-CD at 1:0.5, 1:1, and 1:2 in an aqueous environment. The hydrodynamic diameters of the micelles ranged from 84.1 nm to 107 nm depending on the molar ratio of CHOL/beta-CD. It was shown that the micelle with the largest proportion of PCD possessed excellent abilities in drug release, cell internalization as well as proliferation inhibitory effect toward human A549 lung cancer cells. The results demonstrated that the stereocomplex and host-guest interactions-mediated PLA micelles exhibited great potential in sustained drug delivery.
|
|
Gans, B., Boyé-Péronne, S., Garcia, G. A., Roeder, A., Schleier, D., Halvick, P., & Loison, J. - C. (2017). Unveiling the ionization energy of the CN radical. J. Phys. Chem. Lett., 8, 4038–4042.
Résumé: The cyano radical is an ubiquitous molecule, and was for instance one of the first species detected in astrophysical media such as comets or diffuse clouds. In photodis- sociation regions the reaction rate of CN+ + CO → CN + CO+ is one of the critical parameters defining nitrile chemistry. The enthalpy of this charge transfer reaction is defined as the difference of ionization energies (EI) between CN and CO. Although EI(CO) is known accurately, the EI(CN) values are more dispersed and deduced indirectly from thermodynamic thresholds only, all above EI(CO), leading to the assumption that the reaction was fast even at low temperature. Using a combination of synchrotron radiation, electron/ion imaging coincidence techniques, and supporting ab initio calculations, we directly determine the first adiabatic ionization energy of CN at 13.956(7) eV, and we demonstrate that EI(CO) > EI(CN). The findings suggest a very slow reaction in the cold regions of interstellar media.
|
|
Gans, B., Garcia, G. A., Holzmeier, F., Krüger, J., Röder, A., Lopes, A., Fittschen, C., Loison, J. - C., & Alcaraz, C. (2017). Communication: On the first ionization threshold of the C2H radical. The Journal of Chemical Physics, 146(1), 011101.
Résumé: The slow photoelectron spectrum of the ethynyl radical has been recorded for the first time by using the DESIRS beamline of the SOLEIL synchrotron facility. Ethynyl was generated using a microwave discharge flow tube. The observation of the X+Π3←XΣ+2Π3←XΣ+2 transition allowed the first direct measurement of the adiabatic ionization threshold of this radical (EI = 11.641(5) eV). The experimental results are supported by ab initio calculations. Our preliminary investigation of the cationic ground state potential energy surfaces predicts a non-negligible Renner-Teller effect which has not been discussed previously.
|
|
Garcia, G. A., Krüger, J., Gans, B., Falvo, C., Coudert, L. H., & and Loison, J. C. (2017). Valence shell threshold photoelectron spectroscopy of the CHxCN (x = 0-2) and CNC radicals. The Journal of Chemical Physics, 147(1), 013908.
Résumé: We present the photoelectron spectroscopy of four radical species, CHxCN (x = 0-2) and CNC, formed in a microwave discharge flow-tube reactor by consecutive H abstractions from CH3CN (CHxCN + F → CHx−1CN + HF (x = 1-3)). The spectra were obtained combining tunable vacuum ultraviolet synchrotron radiation with double imaging electron/ion coincidence techniques, which yielded mass-selected threshold photoelectron spectra. The results obtained for H2CCN complement existing ones while for the other radicals the data represent the first observation of their (single-photon) ionizing transitions. In the case of H2CCN, Franck-Condon calculations have been performed in order to assign the vibrational structure of the X+ 1A1←X 2B1 ionizing transition. A similar treatment for the HCCN, CCN, and CNC radicals appeared to be more complicated mainly because a Renner-Teller effect strongly affects the vibrational levels of the ground electronic state of the HCCN+, CCN, and CNC species. Nevertheless, the first adiabatic ionization energies of these radicals are reported and compared to our ab initio calculated values, leading to new values for enthalpies of formation (ΔfH0298(HCCN+(X2A′))=1517±12kJmol−1,ΔfH298(CCN(X2Π))=682±13kJmol−1(ΔfH298(HCCN+(X2A′)=1517±12kJmol−1,ΔfH298(CCN(X2Π))=682±13kJmol−1, and ΔfH298(CNC(X2Πg))=676±12kJmol−1)ΔfH298(CNC(X2Πg))=676±12kJmol−1), which are of fundamental importance for astrochemistry.
|
|
Garcia, R. L., Nieuwjaer, N., Desfrancois, C., Lecomte, F., Leite, S. D., Manil, B., Broquier, M., & Gregoire, G. (2017). Vibronic spectra of protonated hydroxypyridines: contributions of prefulvenic and planar structures. Phys. Chem. Chem. Phys., 19(12), 8258–8268.
Résumé: Various hydroxypyridine derivatives are endogenous or synthetic photosensitizers which could contribute to solar radiation damage. The study of their excited states could lead to a better understanding of their action mechanisms. We present here the ultraviolet (UV) spectra of the protonated 2-, 3- and 4-hydroxypyridine. These spectra were obtained with an experimental device coupling an electrospray ion source with a cold quadrupole ion trap and a time of flight mass spectrometer. They display well resolved vibrational structures, with a clear influence of the position of the OH group. These results are interpreted with excited states calculations at the coupled cluster CC2 level.
|
|
Gavilan, L., Le, K. C., Pino, T., Alata, I., Giuliani, A., & Dartois, E. (2017). Polyaromatic disordered carbon grains as carriers of the UV bump: Far-UV to mid-IR spectroscopy of laboratory analogs. A&A, 607, A73.
Résumé: Context. A multiwavelength study of laboratory carbons with varying degrees of hydrogenation and sp2 hybridization is required to characterize the structure of the carbonaceous carriers of interstellar and circumstellar extinction.
Aims. We study the spectral properties of carbonaceous dust analogs from the far-ultraviolet to the mid-infrared and correlate features in both spectral ranges to the aromatic/aliphatic degree.
Methods. Analogs to carbonaceous interstellar dust encountered in various phases of the interstellar medium have been prepared in the laboratory. These are amorphous hydrogenated carbons (a-C:H), analogs to the diffuse interstellar medium component, and soot particles, analogs to the polyaromatic component. Thin films (d < 100 nm) have been measured in transmission in the vacuum-ultraviolet (VUV; 120–210 nm) within the atmospheric pressure experiment (APEX) chamber of the DISCO beam line at the SOLEIL synchrotron radiation facility. Spectra of these films were further measured through the UV-Vis (210 nm–1 μm) and in the mid-infrared (3–15 μm).
Results. Tauc optical gaps, Eg, are derived from the visible spectra. The major spectral features are fitted through the VUV to the mid-infrared to obtain positions, full-widths at half maximum (FWHM), and integrated intensities. These are plotted against the position of the π-π∗ electronic transitions peak. Unidentified or overlapping features in the UV are identified by correlations with complementary infrared data. A correlation between the optical gap and position of the π-π∗ electronic transitions peak is found. The latter is also correlated to the position of the sp3 carbon defect band at ~8 μm, the aromatic C=C stretching mode position at ~6 μm, and the H/C ratio.
Conclusions. Ultraviolet and infrared spectroscopy of structurally diverse carbon samples are used to constrain the nanostructural properties of carbon carriers of both circumstellar and interstellar extinction, such as the associated coherent lengths and the size of polyaromatic units. Our study suggests that carriers of the interstellar UV bump should exhibit infrared bands akin to the A/B classes of the aromatic infrared bands, while the circumstellar bump carriers should exhibit bands corresponding to the B/C classes.
|
|
|
Georges, R., Michaut, X., Moudens, A., Goubet, M., Pirali, O., Soulard, P., Asselin, P., Huet, T., Roy, P., Fournier, M., & Vigasin, A. (2017). Nuclear Spin Symmetry Conservation in 1H216O Investigated by Direct Absorption FTIR Spectroscopy of Water Vapor Cooled Down in Supersonic Expansion. The Journal of Physical Chemistry A, 121(40), 7455–7468.
|
|
Ghalgaoui, A., Ouvrard, A., Wang, J., Carrez, S., Zheng, W., & Bourguignon, B. (2017). Electron to Adsorbate Energy Transfer in Nanoparticles: Adsorption Site, Size, and Support Matter. J. Phys. Chem. Lett., 8(12), 2666–2671.
Résumé: Confinement of hot electrons in metal nanoparticles (NPs) is expected to lead to increased reactivity in heterogeneous catalysis. NP size as well as support may influence molecule-NP coupling. Here, we use ultrafast nonlinear vibrational spectroscopy to follow energy transfer from hot electrons generated in Pd NP/MgO/Ag(100) to chemisorbed CO. Photoexcitation and photodesorption occur on an ultrashort time scale and are selective according to adsorption site. When the MgO layer is thick enough, it becomes NP size-dependent. Hot electron confinement within NPs is unfavorable for photodesorption, presumably because its dominant effect is to increase relaxation to phonons. An avenue of research is open where NP size and support thickness, photon energy, and molecular electronic structure will be tuned to obtain either molecular stability or reactivity in response to photon excitation.
|
|
Gonon, B., Perveaux, A., Gatti, F., Lauvergnat, D., & Lasorne, B. (2017). On the applicability of a wavefunction-free, energy-based procedure for generating first-order non-adiabatic couplings around conical intersections. Journal Of Chemical Physics, 147(11), 114114.
Résumé: The primal definition of first-order non-adiabatic couplings among electronic states relies on the knowledge of how electronic wave functions vary with nuclear coordinates. However, the non-adiabatic coupling between two electronic states can be obtained in the vicinity of a conical intersection from energies only, as this vector spans the branching plane along which degeneracy is lifted to first order. The gradient difference and derivative coupling are responsible of the two-dimensional cusp of a conical intersection between both potential-energy surfaces and can be identified to the non-trivial eigenvectors of the second derivative of the square energy difference, as first pointed out in Koppel and Schubert [Mol. Phys. 104(5-7), 1069 (2006)]. Such quantities can always be computed in principle for the cost of two numerical Hessians in the worst-case scenario. Analytic-derivative techniques may help in terms of accuracy and efficiency but also raise potential traps due to singularities and ill-defined derivatives at degeneracies. We compare here two approaches, one fully numerical, the other semianalytic, where analytic gradients are available but Hessians are not, and investigate their respective conditions of applicability. Benzene and 3-hydroxychromone are used as illustrative application cases. It is shown that non-adiabatic couplings can thus be estimated with decent accuracy in regions of significant size around conical intersections. This procedure is robust and could be useful in the context of on-the-fly non-adiabatic dynamics or be used for producing model representations of intersecting potential energy surfaces with complete obviation of the electronic wavefunctions. Published by AIP Publishing.
|
|
|
Gref, R., Couvreur, P., & Loftsson, T. (2017). Editorial Special edition of International Journal of Pharmaceutics in honor of Professor Dominique Duchene. International Journal Of Pharmaceutics, 531(2), 411–412.
|
|
Hamraoui, K., Babilotte, P., Billard, F., Hertz, E., Faucher, O., Coudert, L. H., Sugny, D., & Lavorel, B. (2017). Terahertz pulse shaping through propagation in a gas of symmetric top molecules. Phys. Rev. A, 96(4), 043416.
Résumé: Symmetric top molecules of methyl iodide are irradiated with a terahertz pulse generated by a two-color plasma and shaped by a short propagation in air. Free-induction decay is emitted by the excited molecular sample and then propagates in air before detection. The experimental data show that the input terahertz (THz) pulse undergoes strong reshaping through absorption and dispersion. This leads to narrow wave packets at revival times due to the excitation of high rotational energy levels. Typically, a THz burst of duration ≃ 15−20 ps is produced periodically, with a central frequency of ≃1 THz and a width that can be as narrow as 60–80 GHz. Pulse shaping based on propagation can be useful for quantum control in molecules. We provide a theoretical description of this wave propagation based on the Maxwell-Bloch equation. The observed experimental signal is in good agreement with the numerical simulations.
|
|
Hartmann, J. - M., Boulet, C., & Toon, G. C. (2017). Collision-induced absorption by N2 near 2.16 µm: Calculations, model and consequences for atmospheric remote sensing. J. Geophys. Res. Atmos., 122, 2419–2428.
Résumé: Classical Molecular Dynamics Simulations (CMDS) are used for calculations of the Collision Induced Absorption (CIA) by pure N2 in the (2.1-2.2 µm) region of the first overtone band. They lead to reasonable (±15%) agreement with the only two laboratory measurements available, at 97 K and room temperature. Based on these experiment/theory comparisons, empirical corrections are made to the CMDS-calculated CIA of pure N2 in the 200-300 K temperature range. In addition, the contribution of N2-O2 collisions is, in the absence of any laboratory measurement, calculated and a simple semi-empirical model (the first of its kind) is built in order to predict the CIA of N2 under Earth atmosphere conditions. This is successfully validated by comparisons with ground based atmospheric transmission spectra in the 2.1-2.2 µm region.
|
|
Hartmann, J. - M., Vander Auwera, J., Boulet, C., Birot, M., Dourges, M. - A., Toupance, T., El Hamzaoui, H., Ausset, P., Carré, Y., Kocon, L., Capoen, B., & Bouazaoui, M. (2017). Infrared absorption by molecular gases to probe porous materials and comparisons with other techniques. Microporous and Mesoporous Materials, 237, 31–37.
Résumé: Infrared transmission spectra of several molecular gases inside three porous silica samples with pore sizes ranging from 7 nm to several tens of nm have been recorded with a Fourier transform spectrometer. Their analysis shows that consistent values of the percentage of open porosity and average pore size can be retrieved from these non intrusive nor destructive optical measurements. The samples have also been characterized using mercury intrusion/extrusion and the nitrogen sorption method. The results of these different probing techniques are in good agreement when the methods used are adapted to the involved pore size. This consistency demonstrates that light absorption by confined gases is a valuable porosimetry tool.
|
|
|
Hernandez, I. C., Sivankutty, S., Bourg, N., Lecart, S., Dupuis, G., & Leveque-Fort, S. (2017). A Novel STED Microscope with Nanometer Axial Sectioning. Biophysical Journal, 112(3), 140A–141A.
|
|
|
Herrera, M. Z., Kazansky, A. K., Aizpurua, J., & Borisov, A. G. (2017). Quantum description of the optical response of charged monolayer–thick metallic patch nanoantennas. Phys. Rev. B, 95(24), 245413.
|
|
Houdoux, D., Houplin, J., Amiaud, L., Lafosse, A., & Dablemont, C. (2017). Interfacial water on organic substrates at cryogenic temperatures: hydrogen bonding and quantification in the submonolayer regime. Phys Chem Chem Phys, 19(3), 2304–2312.
Résumé: Water molecules were used to probe the physical and chemical properties of a model hydrophilic organic organized layer. To this end, H2O adsorption on mercaptoundecanoic acid self-assembled monolayers (SAMs) was investigated at the molecular level under ultra-high vacuum by high resolution electron energy loss spectroscopy (HREELS), through the sensitivity of the water OH stretching modes to the molecular environment. The water interfacial layer formation and structure were studied upon deposition at 28 K. A direct sensitive quantification in the submonolayer regime (10-80% of completion) was achieved by the sole measurement of the OH stretching mode frequencies, and the dominant basic (-COO(-))/acidic (-COOH) forms of the terminal functions could be probed. The surface densities of the water interfacial layer and the SAM terminal functions were measured independently, and demonstrated to be comparable. This means that the SAM terminal functions provided anchors for water adsorption through two hydrogen bonds and that the SAM acted as a template even at 28 K. Upon annealing at 110 K, the water molecules were observed to form clusters of higher molecular density, dewetting the supporting substrate. Finally, the vanishing of the supporting substrate vibrational signature, due to the masking effect by the deposited water layer, was used to estimate the depth probed by HREELS through water layers to be 11 +/- 2 A.
|
|
Husseen, A., Le Moal, S., Oughaddou, H., Dujardin, G., Mayne, A., & Le Moal, E. (2017). Reaction kinetics of ultrathin NaCl films on Ag(001) upon electron irradiation. Phys. Rev. B, 96(23), 235418.
Résumé: We report on an electron-induced modification of alkali halides in the ultrathin film regime. The reaction kinetics and products of the modifications are investigated in the case of NaCl films grown on Ag(001). Their structural and chemical modification upon irradiationwith electrons of energy 52–60 eV and 3 keV is studied using low-energy electron diffraction (LEED) and Auger electron spectroscopy (AES), respectively. The irradiation effects on the film geometry and thickness (ranging from between two and five atomic layers) are examined using scanning tunneling microscopy (STM).We observe that Cl depletion follows different reaction kinetics, as compared to previous studies on NaCl thick films and bulk crystals. Na atoms produced from NaCl dissociation diffuse to bare areas of the Ag(001) surface, where they form Na-Ag superstructures that are known for the Na/Ag(001) system. The modification of the film is shown to proceed through two processes, which are interpreted as a fast disordering of the film with removal of NaCl from the island edges and a slow decrease of the structural order in the NaCl with formation of holes due to Cl depletion. The kinetics of the Na-Ag superstructure growth is explained by the limited diffusion on the irradiated surface, due to aggregation of disordered NaCl molecules at the substrate step edges.
|
|
|
Jaouadi, A., Lefebvre, R., & Atabek, O. (2017). Vibrational-ground-state zero-width resonnaces for laser filtration: An extended semiclassical analysis. Phys. Rev. A, 95, 063409.
|
|
|
Jia, J., Esaulov, V. A., & Bendounan, A. (2017). Adsorption and desorption kinetics of NTCDA molecules on Ag(111) and Au(111) surfaces studied by ion scattering. Radiation Effects and Defects in Solids, 172(1-2), 39–47.
|
|
|
Jiang, T., Malone, W., Tong, Y., Dragoe, D., Bendounan, A., Kara, A., & Esaulov, V. A. (2017). Thiophene Derivatives on Gold and Molecular Dissociation Processes. J. Phys. Chem. C, 121(50), 27923–27935.
|
|
Joblin, C., Dontot, L., Garcia, G. A., Spiegelman, F., Rapacioli, M., Nahon, L., Parneix, P., Pino, T., & Bréchignac, P. (2017). Size Effect in the Ionization Energy of PAH Clusters. The Journal of Physical Chemistry Letters, 8(15), 3697–3702.
Résumé: We report the first experimental measurement of the near-threshold photoionization spectra of polycyclic aromatic hydrocarbon clusters made of pyrene C16H10 and coronene C24H12, obtained using imaging photoelectron–photoion coincidence spectrometry with a VUV synchrotron beamline. The experimental results of the ionization energy are compared to calculated ones obtained from simulations using dedicated electronic structure treatment for large ionized molecular clusters. Experiment and theory consistently find a decrease of the ionization energy with cluster size. The inclusion of temperature effects in the simulations leads to a lowering of this energy and to quantitative agreement with the experiment. In the case of pyrene, both theory and experiment show a discontinuity in the IE trend for the hexamer. This work demonstrates the ability of the models to describe the electronic structure of PAH clusters and suggests that these species are ionized in astronomical environments where they are thought to be present.
|
|
Kalashnyk N., R. L. A., Li D., Smogunov, Dappe Y.J., Jones T.S. and Guillemot L. (2017). Unraveling Giant Cu(110) Surface Restructuring Induced by a Non-Planar Phthalocyanine. NanoResearch, , 1–7.
Résumé: The surface stability of coinage metals is paramount when they are used as electrode materials for functional electronic devices incorporating organic semiconductors. In this work, it is shown that the adsorption of non-planar vanadyl phthalocyanine molecules on Cu(110) drastically restructured the metal surface at room temperature, which was further enhanced upon moderate annealing. Scanning tunneling microscopy imaging demonstrated that the surface was restructured at step edges into sawtooth features that gradually replaced the (110) terraces. The edges of the modified steps were preferentially composed of chiral (1×6) kink sites decorated with vanadyl phthalocyanine molecules adsorbed in a tilted configuration with the oxygen atom pointing downwards. These results can have a strong impact on the optimization of the performance of organic devices integrated with phthalocyanine molecules.
|
|
|
Khalal M. A., L. P., Andric L., Palaudoux J., Penent F., Bučar K., Žitnik M., Püttner R., Jänkälä K., Cubaynes D., Guilbaud S., and Bizau J.-M. (2017). 4d -inner-shell ionization of Xe+ ions and subsequent Auger decay. PHYSICAL REVIEW A, 96, 013412.
|
|
Khalal M.A., S. J., Jänkälä K., Huttula S-M, Huttula M, Bizau J-M, Cubaynes D., Guilbaud S., Ito K., Andric L., Feng J., Lablanquie P., Palaudoux J. and Penent F. (2017). Multielectron spectroscopy: energy levels of K n+ and Rb n+ ions (n = 2, 3, 4). Journal of Physics B: Atomic, Molecular and Optical Physics, 50(22), 225003.
Résumé: A magnetic bottle time-of-flight spectrometer has been used to perform spectroscopy of K n+ and Rb n+ states with ionization degrees n of 2, 3 and 4. Energy levels are directly measured by detecting in coincidence the n electrons that are emitted as a result of single photon absorption. Experimental results are compared with the energies from the NIST atomic database and ab initio multiconfiguration Dirac–Fock calculations. Previously unidentified 3p 4(3P)3d 1 4D energy levels of K2+ are assigned.
|
|
Koshelev, M. A., Delahaye, T., Serov, E. A., Vilkov, I. N., Boulet, C., & Tretyakov, M. Y. (2017). Accurate modeling of the diagnostic 118-GHz oxygen line for remote sensing of the atmosphere. JQSRT, 196, 78–86.
Résumé: We report the results of laboratory investigations of the shape of the diagnostic atmospheric N = 1- oxygen line performed over a very wide range of pressures from 0.4 to 1000 Torr using two principally different spectrometers having complementary abilities. A spectrometer with a radio-acoustic detector of absorption was used for recording low pressure spectra spanning the 0.4–2 Torr range, and high pressure data from 250 to 1000 Torr were registered by a resonator spectrometer. The sensitivity of both instruments was improved significantly which allowed us to obtain signal-to-noise ratio at spectra recordings of the order of a few thousands. The spectra analysis enabled the first manifestation of the speed-dependence of the collision cross section of the line, along with considerable refinement of other parameters, including pressure broadening, intensity and line-mixing. The results are of primary importance for atmospheric applications.
|
|
|
Koval, N. E., Borisov, A. G., Rosa, L. F. S., Stori, E. M., Dias, J. F., Grande, P. L., Sánchez-Portal, D., & Muiño, R. D. (2017). Vicinage effect in the energy loss of H2 dimers: Experiment and calculations based on time-dependent density-functional theory. Phys. Rev. A, 95(6), 062707.
|
|
Kumar, N., Pham-Xuan, Q., Depauw, A., Hemadi, M., Ha-Duong, N. - T., Lefevre, J. - P., Ha-Thi, M. - H., & Leray, I. (2017). New sensitive and selective calixarene-based fluorescent sensors for the detection of Cs+ in an organoaqueous medium. New J. Chem., 41(15), 7162–7170.
Résumé: Herein, new fluorescent sensors based on calix[4]arene-biscrown-6 containing extended coumarin as a fluorophore were synthetized and their photophysical properties were characterized. These compounds display intense absorption and emission spectra in the visible region due to extension of the coumarin system. Moreover, complexation properties of these ligands were reported, and the Calix-COU-Benz-CN ligand was able to selectively detect cesium ions in an organoaqueous solvent. Upon the addition of cesium, a blue-shift in the absorption spectra and an enhancement of the emission spectra were observed. This ligand was incorporated in a microfluidic device for the detection of Cs+ ions, and a detection limit of 1.4 [small mu ]M was achieved for these ions.
|
|
|
Kutzer, P., Hartung, S., Pirali, O., Pietschnig, R., Medcraft, C., Yamada, K. M. T., & Giesen, T. F. (2017). Tert-butyl-dibromophosphane tBuPBr2—a new chemical synthesis and first spectroscopic characterization. Heteroatom Chem, 28(2), e21361-n/a.
|
|
Labidi, H., Pinto, H. P., Leszczynski, J., & Riedel, D. (2017). Exploiting a single intramolecular conformational switching Ni-TPP molecule to probe charge transfer dynamics at the nanoscale on bare Si(100)-2x1. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 19, 28982–28992.
Résumé: Acquiring quantitative information on charge transfer (CT) dynamics at the nanoscale remains an important scientific challenge. In particular, CT processes in single molecules at surfaces need to be investigated to be properly controlled in various devices. To address this issue, the dynamics of switching molecules can be exploited. Here, nickel-tetraphenylporphyrin adsorbed on the Si(100) surface is used to study the CT process ruling the reversible activation of two chiral molecular conformations. Via the electrons of a scanning tunneling microscope (STM), a statistical study of molecular switching reveals two specific locations of the molecule for which their efficiency is optimized. The CT mechanism is shown to propagate from two lateral aryl groups towards the porphyrin macrocycle inducing an intramolecular movement of two symmetric pyrroles. The measured switching efficiencies can thus be related to a Markus-Jordner model to estimate relevant parameters that describe the dynamics of the CT process. Numerical simulations provide a precise description of the molecular conformations and unveil the molecular energy levels that are involved in the CT process. This quantitative method opens a completely original approach to study CT at the nanoscale.
|
|
Lablanquie P., K. M. A., Andric L., Palaudoux J., Penent F., Bizau J-M, Cubaynes D., Jänkälä K., Hikosaka Y., Ito K., Bučar K., Žitnikg M. (2017). Multi-electron coincidence spectroscopy: Triple Auger decay of Ar 2p and 2s holes. Journal of Electron Spectroscopy and Related Phenomena, 220, 125–132.
Résumé: The detailed study of single photon multiple ionization processes requires the detection in coincidence of all the electrons emitted from the same ionization event. The advent of magnetic bottle experiments made possible the development of this multi-electron coincidence spectroscopy. First we will briefly review the achievements of this technique. Then we will illustrate more specifically its high sensitivity taking as an example the decay by emission of three Auger electrons of 2p and 2s holes in argon. Our results show that the processes are completely different depending on the initial core hole: the three Auger electrons are emitted dominantly in a simultaneous path for the 2p case, but in cascade for the 2s one.
|
|
|
Lacombe, S., Porcel, E., & Scifoni, E. (2017). Particle therapy and nanomedicine: state of art and research perspectives. Cancer nanotechnology, 8(1), 9.
|
|
|
Launoy, T., Béroff, K., Chabot, M., Martinet, G., Le Padellec, A., Pino, T., Bouneau, S., Vaeck, N., Liévin, J., Féraud, G., Loreau, J., & Mahajan, T. (2017). Ion-pair dissociation of highly excited carbon clusters: Size and charge effects. Pra, 95(2), 022711.
|
|
|
Le Marec, A., Larroche, O., & Klisnick, A. (2017). Linear autocorrelation of partially coherent extreme-ultraviolet lasers: a quantitative analysis. Optics Letters, 42(23), 4958–4961.
|
|
Le, K. C., Lefumeux, C., & Pino, T. (2017). Differential Raman backscattering cross sections of black carbon nanoparticles. Scientific Reports, 7(1), 17124.
Résumé: We report the measurements of the differential Raman backscattering cross sections for several carbonaceous ultrafine particles of environmental relevances. These were obtained by dispersing the target particles in liquid water which was used as the internal standard reference. The optical collection was performed in a configuration to ensure a detection as close as possible to the backward direction. These are the first cross sections on black carbon-type particles although Raman spectroscopy is widely used in Carbon science. The high values of the cross sections, few 10−28 cm2.sr−1.atom−1, reflect resonance effects that take advantages of the disordered polyaromatic structures. Because they were measured in conditions intended to mimic the aerosol phase, these measurements provide a crucial step to move toward quantitative Raman spectroscopy and enable development of dedicated teledetection of black carbon in the atmosphere and in combustion chambers.
|
|
|
Leclerc, A., Viennot, D., Jolicard, G., Lefebvre, R., & Atabek, O. (2017). Exotic states in the strong field control of H2+ dissociation dynamics: From exceptional points to zero width resonances. J. Phys. B, 50, 234002.
|
|
|
Lefebvre, R. (2017). Factorisation of zero-width resonance wave functions. Molecular Physics, 115(15-16), 1966–1970.
|
|
Li, H. Y., Lv, N. N., Li, X., Liu, B. T., Feng, J., Ren, X. H., Guo, T., Chen, D. W., Stoddart, J. F., Gref, R., & Zhang, J. W. (2017). Composite CD-MOF nanocrystals-containing microspheres for sustained drug delivery. Nanoscale, 9(22), 7454–7463.
Résumé: Metal-organic frameworks (MOFs), which are typically embedded in polymer matrices as composites, are emerging as a new class of carriers for sustained drug delivery. Most of the MOFs and the polymers used so far in these composites, however, are not pharmaceutically acceptable. In the investigation reported herein, composites of gamma-cyclodextrin (gamma-CD)-based MOFs (CD-MOFs) and polyacrylic acid (PAA) were prepared by a solid in oil-in-oil (s/o/o) emulsifying solvent evaporation method. A modified hydrothermal protocol has been established which produces efficiently at 50 degrees C in 6 h micron (5-10 μm) and nanometer (500-700 nm) diameter CD-MOF particles of uniform size with smooth surfaces and powder X-ray diffraction patterns that are identical with those reported in the literature. Ibuprofen (IBU) and Lansoprazole (LPZ), both insoluble in water and lacking in stability, were entrapped with high drug loading in nanometer-sized CD-MOFs by co-crystallisation (that is more effective than impregnation) without causing MOF crystal degradation during the loading process. On account of the good dispersion of drugloaded CD-MOF nanocrystals inside polyacrylic acid (PAA) matrices and the homogeneous distribution of the drug molecules within these crystals, the composite microspheres exhibit not only spherical shapes and sustained drug release over a prolonged period of time, but they also demonstrate reduced cell toxicity. The cumulative release rate for IBU (and LPZ) follows the trend: IBU-gamma-CD complex microspheres (ca. 80% in 2 h) > IBU microspheres > IBU-CD-MOF/PAA composite microspheres (ca. 50% in 24 h). Importantly, no burst release of IBU (and LPZ) was observed from the CD-MOF/PAA composite microspheres, suggesting an even distribution of the drug as well as strong drug carrier interactions inside the CD-MOF. In summary, these composite microspheres, composed of CD-MOF nanocrystals embedded in a biocompatible polymer (PAA) matrix, constitute an efficient and pharmaceutically acceptable MOFbased carrier for sustained drug release.
|
|
Li, X., Guo, T., Lachmanski, L., Manoli, F., Menendez-Miranda, M., Manet, I., Guo, Z., Wu, L., Zhang, J. W., & Gref, R. (2017). Cyclodextrin-based metal-organic frameworks particles as efficient carriers for lansoprazole: Study of morphology and chemical composition of individual particles. International Journal Of Pharmaceutics, 531(2), 424–432.
Résumé: Cyclodextrin-based metal-organic frameworks (CD-MOFs) represent an environment-friendly and biocompatible class of MOFs drawing increasing attention in drug delivery. Lansoprazole (LPZ) is a proton-pump inhibitor used to reduce the production of acid in the stomach and recently identified as an antitubercular prodrug. Herein, LPZ loaded CD-MOFs were successfully synthesized upon the assembly with gamma-CD in the presence of K+ ions using an optimized co-crystallization method. They were characterized in terms of morphology, size and crystallinity, showing almost perfect cubic morphologies with monodispersed size distributions. The crystalline particles, loaded or not with LPZ, have mean diameters of around 6 μm. The payloads reached 23.2 +/- 2.1% (wt) which corresponds to a molar ratio of 1:1 between LPZ and gamma-CD. It was demonstrated that even after two years storage, the incorporated drug inside the CD-MOFs maintained its spectroscopic characteristics. Molecular modelling provided a deeper insight into the interaction between the LPZ and CD-MOFs. Raman spectra of individual particles were recorded, confirming the formation of inclusion complexes within the tridimensional CD-MOF structures. Of note, it was found that each individual particle had the same chemical composition. The LPZ-loaded particles had remarkable homogeneity in terms of both drug loading and size. These results pave the way towards the use of CD-MOFs for drug delivery purposes. (C) 2017 Elsevier B.V. All rights reserved.
|
|
Li, X., Lachmanski, L., Safi, S., Sene, S., Serre, C., Greneche, J. M., Zhang, J., & Gref, R. (2017). New insights into the degradation mechanism of metal-organic frameworks drug carriers. Scientific Reports, 7, 13142.
Résumé: A versatile method based on Raman microscopy was developed to follow the degradation of iron carboxylate Metal Organic Framework (MOF) nano-or micro-particles in simulated body fluid (phosphate buffer). The analysis of both the morphology and chemical composition of individual particles, including observation at different regions on the same particle, evidenced the formation of a sharp erosion front during particle degradation. Interestingly, this front separated an intact non eroded crystalline core from an amorphous shell made of an inorganic network. According to Mossbauer spectrometry investigations, the shell consists essentially of iron phosphates. Noteworthy, neither drug loading nor surface modification affected the integrity of the tridimensional MOF network. These findings could be of interest in the further development of next generations of MOF drug carriers.
|
|
Li, X., Salzano, G., Zhang, J. W., & Gref, R. (2017). Spontaneous Self-Assembly of Polymeric Nanoparticles in Aqueous Media: New Insights From Microfluidics, In Situ Size Measurements, and Individual Particle Tracking. Journal Of Pharmaceutical Sciences, 106(1), 395–401.
Résumé: Supramolecular cyclodextrin-based nanoparticles (CD-NPs) mediated by host-guest interactions have gained increased popularity because of their “green” and simple preparation procedure, as well as their versatility in terms of inclusion of active molecules. Herein, we showed that original CD-NPs of around 100 nm are spontaneously formed in water, by mixing 2 aqueous solutions of (1) a CD polymer and (2) dextran grafted with benzophenone moieties. For the first time, CD-NPs were instantaneously produced in a microfluidic interaction chamber by mixing 2 aqueous solutions of neutral polymers, in the absence of organic solvents. Whatever the mixing conditions, CD-NPs with narrow size distributions were immediately formed upon contact of the 2 polymeric solutions. In situ size measurements showed that the CD-NPs were spontaneously formed. Nanoparticle tracking analysis was used to individually follow the CD-NPs in their Brownian motions, to gain insights on their size distribution, concentration, and stability on extreme dilution. Nanoparticle tracking analysis allowed to establish that despite their non-covalent nature, and the CD-NPs were remarkably stable in terms of concentration and size distribution, even on extreme dilution (concentrations as low as 100 ng/mL). (C) 2016 American Pharmacists Association (R). Published by Elsevier Inc. All rights reserved.
|
|
|
Lu, W., Zhang, G., Wei, F., Li, W., Cheng, K., Ding, F., Zhang, J., & Zheng, W. (2017). Shape-controlled synthesis of Pd nanocrystals in an aqueous solution by using amphiphilic triblock copolymers as both the stabilizer and the reductant. Colloid Polym Sci, 295(4), 703–707.
|
|
Lv, N. N., Guo, T., Liu, B. T., Wang, C. F., Singh, V., Xu, X. N., Li, X., Chen, D. W., Gref, R., & Zhang, J. W. (2017). Improvement in Thermal Stability of Sucralose by Y-Cyclodextrin Metal-Organic Frameworks. Pharmaceutical Research, 34(2), 269–278.
Résumé: Purpose To explain thermal stability enhancement of an organic compound, sucralose, with cyclodextrin based metal organic frameworks. Methods Micron and nanometer sized basic CD-MOFs were successfully synthesized by a modified vapor diffusion method and further neutralized with glacial acetic acid. Sucralose was loaded into CD-MOFs by incubating CDMOFs with sucralose ethanol solutions. Thermal stabilities of sucralose-loaded basic CD-MOFs and neutralized CDMOFs were investigated using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and high performance liquid chromatography with evaporative lightscattering detection (HPLC-ELSD). Results Scanning electron microscopy (SEM) and powder Xray diffraction (PXRD) results showed that basic CD-MOFs were cubic crystals with smooth surface and uniform sizes. The basic CD-MOFs maintained their crystalline structure after neutralization. HPLC-ELSD analysis indicated that the CD-MOF crystal size had significant influence on sucralose loading (SL). The maximal SL of micron CD-MOFs (CDMOF-Micro) was 17.5 +/- 0.9% (w/w). In contrast, 27.9 +/- 1.4% of sucralose could be loaded in nanometer-sized basic CD-MOFs (CD-MOF-Nano). Molecular docking modeling showed that sucralose molecules preferentially located inside the cavities of gamma-CDs pairs in CD-MOFs. Raw sucralose decomposed fast at 90(o)C, with 86.2 +/- 0.2% of the compound degraded within only 1 h. Remarkably, sucralose stability was dramatically improved after loading in neutralized CDMOFs, with only 13.7 +/- 0.7% degradation at 90(o)C within 24 h. Conclusions CD-MOFs efficiently incorporated sucralose and maintained its integrity upon heating at elevated temperatures.
|
|
Ma, Q., Boulet, C., & and Tipping, R. H. (2017). Relaxation matrix for symmetric tops with inversion symmetry: Line coupling and line mixing effects on NH3 lines in the . The Journal of Chemical Physics, 146(13), 134312.
Résumé: Line shape parameters including the half-widths and the off-diagonal elements of the relaxation matrix have been calculated for self-broadened NH3 lines in the perpendicular ν4 band. As in the pure rotational and the parallel ν1 bands, the small inversion splitting in this band causes a complete failure of the isolated line approximation. As a result, one has to use formalisms not relying on this approximation. However, due to differences between parallel and perpendicular bands of NH3, the applicability of the formalism used in our previous studies of the ν1 band and other parallel bands must be carefully verified. We have found that, as long as potential models only contain components with K1 = K2 = 0, whose matrix elements require the selection rule Δk = 0, the formalism is applicable for the ν4 band with some minor adjustments. Based on both theoretical considerations and results from numerical calculations, the non-diagonality of the relaxation matrices in all the ^{P}P, ^{R}P, ^{P}Q, ^{R}Q, ^{P}R, and ^{R}R branches is discussed. Theoretically calculated self-broadened half-widths are compared with measurements and the values listed in HITRAN 2012. With respect to line coupling effects, we have compared our calculated intra-doublet off-diagonal elements of the relaxation matrix with reliable measurements carried out in the PP branch where the spectral environment is favorable. The agreement is rather good since our results do well reproduce the observed k and j dependences of these elements, thus validating our formalism.
|
|
|
Ma, Q., Boulet, C., & Tipping, R. H. (2017). Vibrational dependence of line coupling and line mixing in self-broadened parallel bands of NH3. JQSRT, 203, 425–433.
|
|
Marcos-Almaraz, M. T., Gref, R., Agostoni, V., Kreuz, C., Clayette, P., Serre, C., Couvreur, P., & Horcajada, P. (2017). Towards improved HIV-microbicide activity through the co-encapsulation of NRTI drugs in biocompatible metal organic framework nanocarriers. Journal Of Materials Chemistry B, 5(43), 8563–8569.
Résumé: The efficacy of the routinely used anti-HIV (Human Immunodeficiency Virus) therapy based on nucleoside reverse transcriptase inhibitors (NRTIs) is limited by the poor cellular uptake of the active triphosphorylated metabolites and the low efficiency of intracellular phosphorylation of their prodrugs. Nanoparticles of iron(III) polycarboxylate Metal-Organic Frameworks (nanoMOFs) are promising drug nanocarriers. In this study, two active triphosphorylated NRTIs, azidothymidine triphosphate (AZT-Tp) and lamivudine triphosphate (3TC-Tp), were successfully co-encapsulated into the biocompatible mesoporous iron(III) trimesate MIL-100(Fe) nanoMOF in order to improve anti-HIV therapies. The drug loaded nanoMOFs could be stored for up to 2-months and reconstituted after freeze drying, retaining similar physicochemical properties. Their antiretroviral activity was evidenced in vitro on monocyte-derived macrophages experimentally infected with HIV, making these co-encapsulated nanosystems excellent HIV-microbicide candidates.
|
|
|
Marechal, D., Daudin, R., Bourg, N., Loe-Mie, Y., Potier, B., Dutar, P., Viard, J., Lepagnol-Bestel, A., Sartori, M., Hindie, V., Birling, M., Pavlovic, G., Dupuis, G., Fort, S. L., Laporte, J., Rain, J., Simonneau, M., & Herault, Y. (2017). Risk factor gene BIN1 induces late onset Alzheimer disease presymptomatic phenotypes in a BAC transgenic mouse model. European Neuropsychopharmacology, 27, S742–S743.
|
|
|
Marinica, D. C., Kazansky, A. K., & Borisov, A. G. (2017). Electrical control of the light absorption in quantum-well functionalized junctions between thin metallic films. Phys. Rev. B, 96(24), 245407.
|
|
Matias da Silva, F., Fadanelli Filho, R. C., Grande, P. L., Koval, N., Diez Muino, R., Borisov, A. G., Arista, N., & Schiwietz G. (2017). Ground-and excited-state scattering potentials for the stopping of protons in an electron gas. J. Phys. B: At. Mol. Opt. Phys., 50(18), 185201.
Résumé: The self-consistent electron–ion potential V(r) is calculated for H+ ions in an electron gas system as a function of the projectile energy to model the electronic stopping power for conduction-band electrons. The results show different self-consistent potentials at low projectile-energies, related to different degrees of excitation of the electron cloud surrounding the intruder ion. This behavior can explain the abrupt change of velocity dependent screening-length of the potential found by the use of the extended Friedel sum rule and the possible breakdown of the standard free electron gas model for the electronic stopping at low projectile energies. A dynamical interpolation of V(r) is proposed and used to calculate the stopping power for H+ interacting with the valence electrons of Al. The results are in good agreement with the TDDFT benchmark calculations as well as with experimental data.
|
|
|
Matias, F., Fadanelli, R. C., Grande, P. L., Koval, N. E., Muiño, R. D., Borisov, A. G., Arista, N. R., & Schiwietz, G. (2017). Ground- and excited-state scattering potentials for the stopping of protons in an electron gas. J. Phys. B: At. Mol. Opt. Phys., 50(18), 185201.
|
|
Mendes Marinho, S., Ha-Thi, M. - H., Pham, V. - T., Quaranta, A., Pino, T., Lefumeux, C., Chamaillé, T., Leibl, W., & Aukauloo, A. (2017). Time-Resolved Interception of Multiple-Charge Accumulation in a Sensitizer–Acceptor Dyad. Angew. Chem. Int. Ed., 56(50), 15936–15940.
Résumé: Biomimetic models that contain elements of photosynthesis are fundamental in the development of synthetic systems that can use sunlight to produce fuel. The critical task consists of running several rounds of light-induced charge separation, which is required to accumulate enough redox equivalents at the catalytic sites for the target chemistry to occur. Long-lived first charge-separated state and distinct electronic signatures for the sequential charge accumulated species are essential features to be able to track these events on a spectroscopic ground. Herein, we use a double-excitation nanosecond pump–pump–probe experiment to interrogate two successive rounds of photo-induced electron transfer on a molecular dyad containing a naphthalene diimide (NDI) linked to a [Ru(bpy)3]2+ (bpy=bipyridine) chromophore by using a reversible electron donor. We report an unprecedented long-lived two-electron charge accumulation (t=200 μs).
|
|
|
Mendive-Tapia, D., Firmino, T., Meyer, H. D., & Gatti, F. (2017). Towards a systematic convergence of Multi-Layer (ML) Multi-Configuration Time-Dependent Hartree nuclear wavefunctions: The ML-spawning algorithm. CHEMICAL PHYSICS, 482, 113–123.
|
|
|
Morisset, S., Rougeau, N., & Teillet-Billy, D. (2017). Influence of a graphene surface on the first steps of the hydrogenation of a coronene molecule. Chemical Physics Letters, 679, 225–232.
|
|
Muzas, A. S., del Cueto, M., Gatti, F., Somers, M. F., Kroes, G. J., Martin, F., & Diaz, C. (2017). H-2/LiF(001) diffractive scattering under fast grazing incidence using a DFT-based potential energy surface. Physical Review B, 96(20), 205432.
Résumé: Grazing incidence fast molecule diffraction (GIFMD) has been recently used to study a number of surfaces, but this experimental effort has not been followed, to present, by a subsequent theoretical endeavor. Aiming at filling this gap, in this work, we have carried out GIFMD simulations for the benchmark system H-2/ LiF(001). To perform our study, we have built a six-dimensional potential energy surface (6D-PES) by applying a modified version of the corrugation reducing procedure (CRP) to a set of density functional theory (DFT) energies. Based on this CRP interpolated PES, we have conducted quantum dynamics calculations using both the multiconfiguration time-dependent Hartree and the time-dependent wave packet propagation methods. We have compared the results of our GIFMD simulations with available experimental spectra. From this comparison, we have uncovered a prominent role of the interaction between the quadrupole moment of H-2 and the electric field associated with LiF(001) for specific incidence crystallographic directions. We show that, on the one hand, the molecule's initial rotation strongly affects its diffractive scattering and, on the other hand, the scattering is predominantly rotationally elastic over a wide range of incidence conditions typical for GIFMD experiments.
|
|
Ndengue, S., Dawes, R., Gatti, F., & Meyer, H. D. (2017). Atom-triatom rigid rotor inelastic scattering with the MultiConfiguration Time Dependent Hartree approach. Chemical Physics Letters, 668, 42–46.
Résumé: The inelastic scattering between a rigid rotor triatomic molecule and an atom is described within the frame of the MultiConfiguration Time dependent Hartree (MCTDH) method. Sample calculations are done on the H2O-Ar system for which a flexible 6D PES (used here in the rigid rotor approximation) has been recently computed in our group and will be presented separately. The results are compared with corresponding time independent calculations using the Arthurs and Dalgarno approach and confirm as expected the equivalence of the two methods. (C) 2016 Elsevier B.V. All rights reserved.
|
|
Nguyen-Dang, T. T., Peters, M., Viau-Trudel, J., Couture-Bienvenue, E., Puthumpally-Joseph, R., Charron, E., & Atabek, O. (2017). Laser-induced electron diffraction: alignment defects and symmetry breaking. Molecular Physics, 115(15-16), 1934–1943.
Résumé: The fringe pattern that allows geometrical and orbital structure information to be extracted from LIED (laser-induced electron diffraction) spectra of symmetric molecules is shown to reflect a symmetry conservation principle. We show that under a field polarisation which preserves certain symmetry elements of the molecule, the symmetry character of the initial wave function is conserved during its time-evolution. We present a symmetry analysis of a deviation from a perfect alignment by decomposing the field into a major, symmetry-determining part, and a minor, symmetry-breaking part. This decomposition leads to a corresponding factorisation of the time-evolution operator. The formalism is applied to the analysis of the robustness of LIED readings and inversions with respect to deviations from a perfect perpendicular and parallel alignment of a symmetric ABA triatomic molecule. The results indicate a particularly strong stability of the type of LIED spectra associated with the perpendicular alignment situation.
|
|
Nouman, M., Saunier, J., Jubeli, E., Marliere, C., & Yagoubi, N. (2017). Impact of of sterilization and oxidation processes on the additive blooming observed on the surface of polyurethane. European Polymer Journal, 90, 37–53.
Résumé: The surface state is a major parameter for the biocompatibility of medical devices. During storage, the blooming of additives may occur on the surface of polymers and modify their properties. In this study, the impact of sterilizing and oxidation treatments on blooming was studied. The study was realized on polyurethane used in the fabrication of catheters on which the blooming of antioxidant crystals has been previously observed. Sterilization by ionizing radiations (beta, gamma) was performed on this material and samples were submitted to different kinds of oxidation process (UV, H2O2 and macrophages action). Surface evolution was investigated using AFM microscopy, FTIR-ATR and SEM.
|
|
|
Odintsova, T. A., Tretyakov, M. Y., Pirali, O., & Roy, P. (2017). Water vapor continuum in the range of rotational spectrum of H2O molecule: New experimental data and their comparative analysis. Journal of Quantitative Spectroscopy and Radiative Transfer, 187(Supplement C), 116–123.
|
|
Ortega, J. M., Glotin, F., Prazeres, R., Li, X., & Gref, R. (2017). Far infrared micro-spectroscopy: an innovative method to detect individual metal-organic framework particles. Applied Optics, 56(23), 6663–6667.
Résumé: The purpose of this study is to extend the spectral range of a differential method of infrared micro-spectroscopy in order to allow the accurate detection of nanoparticles of interest for biomedical applications. Among these, metal-organic framework (MOF) nanoparticles have attracted increasing interest due to their capacity to incorporate high drug payloads, biodegradability, and possibility of tailoring their surfaces by grafting specific ligands. However, MOF particle detection in biological media without grafting or incorporating fluorescent molecules is challenging. We took advantage here of the presence of the specific absorption bands of nanoscale MOFs in far infrared in order to individually discriminate them. Here we show that single MOF nanoparticles can be imaged with a spatial resolution of a few tens of nanometers. (C) 2017 Optical Society of America
|
|
|
Ouvrard, A., Ghalgaoui, A., Michel, C., Barth, C., Wang, J., Carrez, S., Zheng, W., Henry, C. R., & Bourguignon, B. (2017). CO Chemisorption on Ultrathin MgO-Supported Palladium Nanoparticles. J. Phys. Chem. C, 121(10), 5551–5564.
|
|
Parneix, P., Gamboa, A., Falvo, C., Bonnin, M. A., Pino, T., & Calvo, F. (2017). Dehydrogenation effects on the stability of aromatic units in polycyclic aromatic hydrocarbons in the interstellar medium: A computational study at finite temperature. Molecular Astrophysics, 7, 9–18.
Résumé: Isomerization, ionization and fragmentation of molecular compounds in the interstellar medium can be triggered by stellar radiation and cosmic rays. In the present contribution, we examine the propensity for isomerization and the relative stability of aromatic rings in the pyrene and coronene molecules at various degrees of dehydrogenation by means of molecular modeling. Using the AIREBO reactive force field and advanced Monte Carlo techniques such as the Wang–Landau method based on suitable order parameters, entire free-energy profiles describing the isomerization pathways and equilibrium properties were calculated as a function of temperature or total energy. We generally find that hydrogenation significantly stabilizes the fully polycyclic aromatic hydrocarbon (PAH) structure, even though local dehydrogenation next to an aromatic ring favors ring opening. The formation of pentagonal rings, a typical defect motif in the polycyclic carbon skeleton, is predicted to be actually competitive with the loss of a hydrogen atom. Our investigation emphasizes the likely presence of defects in astrophysical PAHs, whose spectral features remain to be better characterized and understood.
|
|
Perez-Mellor, A., & Zehnacker, A. (2017). Vibrational circular dichroism of a 2,5-diketopiperazine (DKP) peptide: Evidence for dimer formation in cyclo LL or LD diphenylalanine in the solid state. Chirality, 29(2), 89–96.
Résumé: The diastereomer diketopiperazine (DKP) peptides built on phenylalanine, namely, cyclo diphenylalanine LPhe-LPhe and LPhe-DPhe, were studied in the solid phase by vibrational circular dichroism (VCD) coupled to quantum chemical calculations. The unit structure of cyclo LPhe-LPhe in KBr pellets is a dimer bridged by two strong NH center dot center dot center dot O hydrogen bonds. The intense bisignate signature in the CO stretch region is interpreted in terms of two contributions arising from the free COs of the dimer and the antisymmetrical combination of the bound COs. In contrast, cyclo LPhe-DPhe shows no VCD signal in relation to its symmetric nature.
|
|
|
Pirali, O., Goubet, M., Boudon, V., D’Accolti, L., Fusco, C., & Annese, C. (2017). Characterization of isolated 1-aza-adamantan-4-one (C9H13NO) from microwave, millimeter-wave and infrared spectroscopy supported by electronic structure calculations. Journal of Molecular Spectroscopy, 338(Supplement C), 6–14.
|
|
Poullain, S. M., Cireasa, R., Cornaggia, C., Simon, M., Marin, T., Guillemin, R., Houver, J. C., Lucchese, R. R., & Dowek, D. (2017). Spectral dependence of photoemission in multiphoton ionization of NO2 by femtosecond pulses in the 375-430 nm range. Physical Chemistry Chemical Physics, 19(33), 21996–22007.
Résumé: We investigate the multiphoton ionization of NO2 using tunable (430-375 nm) femtosecond pulses and photoelectron-photoion coincidence momentum spectroscopy. In order to understand the complex electronic and nuclear photodynamics at play following absorption of three to five photons, we also report extended photoionization calculations using correlated targets and coupled channels. Exploring the multiphoton dissociative ionization (MPDI) and multiphoton ionization (MPI) processes over such a broad energy range enables us to lend further support to our work carried out around 400 nm of a femtosecond laser [S. Marggi Poullain et al., J. Phys. B: At., Mol. Opt. Phys., 2014, 47, 124024]. Two excitation energy regions are identified and discussed in terms of the proposed reaction pathways, highlighting the significant role of Rydberg states, such as the [R*(6a(1))(-1), 3p sigma] Rydberg state, in the NO2 multiphoton excitation and photoionization. These new results support our previous assumption that different bent and linear geometries of the NO2 +(X-1 Sigma(g)) ionic state contribute to the MPDI and MPI, consistent with the reported calculations which reveal an important vibronic coupling characterizing the photoemission. Remarkably, the strong anisotropy of the recoil frame photoelectron angular distribution (RFPAD) previously observed at 400 nm appears as a fingerprint across the whole explored photon energy range.
|
|
|
Puthumpally-Joseph R., Mangaud E., Desouter-Lecomte M., Atabek O., & Sugny D. (2017). Towards laser control of open quantum systems: Memory effects. Mol. Phys., 115, 1944.
|
|
Puthumpally-Joseph, R., Viau-Trudel, J., Peters, M., Nguyen-Dang, T. T., Atabek, O., & Charron, E. (2017). Laser-induced electron diffraction: inversion of photo-electron spectra for molecular orbital imaging. Molecular Physics, 115(15-16), 1889–1897.
Résumé: In this paper, we discuss the possibility of imaging molecular orbitals from photoelectron spectra obtained via laser -induced electron diffraction in linear molecules. This is an extension of our recent work to the case of the HOMO-1 orbital of the carbon dioxide molecule. We show that such an imaging technique has the potential to image molecular orbitals at different internuclear distances in a sub-femtosecond time scale and with a resolution of a fraction of an Angström.
|
|
|
Quertite, K., Lasri, K., Enriquez, H., Mayne, A. J., Bendounan, A., Dujardin, G., Trcera, N., Malone, W., EL Kenz, A., Benyoussef, A., Kara, A., & Oughaddou, H. (2017). Atomic structure of sub-monolayer NaCl grown on Ag(110) surface. JOURNAL OF PHYSICAL CHEMISTRY C, 121, 20272–20278.
|
|
Quertite, K., Zaari, H., Ez-Zahraouy, H., El Kenz, A., Oughaddou, H., & Benyoussef, A. (2017). Theoretical investigation of electronic, magnetic, transport and optical properties of the pure and doped cuprate superconductor HgBa 2 CuO 4+δ. CURRENT APPLIED PHYSICS, 17(10), 1271–1278.
Résumé: We report detailed DFT calculations and Monte Carlo simulations on the pure and doped cuprate superconductor HgBa2CuO4+δ. For the pure compound (δ = 0), we have obtained an insulating behavior with strong antiferromagnetic copper spin correlations in the CuO2 plane. The high value of the calculated Néel temperature TN = 333 K reflects the large in-plane exchange interaction J = -145 meV. The obtained optical properties and critical exponents demonstrate the anisotropic quasi-2D character of this type of materials. As for the doped compound the electronic structure and the transport properties have been investigated for various values of doping. Based on these data, we suggest a prediction of the value of optimum doping for HgBa2CuO4+δ (δoptimal = 0.125).
|
|
Rodriguez-Ruiz, V., Maksimenko, A., Salzano, G., Lampropoulou, M., Lazarou, Y. G., Agostoni, V., Couvreur, P., Gref, R., & Yannakopoulou, K. (2017). Positively charged cyclodextrins as effective molecular transporters of active phosphorylated forms of gemcitabine into cancer cells. Scientific Reports, 7, 8353.
Résumé: Positively charged cyclodextrins (PCCDs) are molecular carriers of particular interest for their ability to readily enter into cancer cells. Of main interest, guanidino-and aminoalkyl-PCCDs can be conveniently synthesized and form stable and strong inclusion complexes with various active molecules bearing phosphate groups. We have addressed here the challenge to deliver into cancer cells phosphorylated gemcitabine drugs well known for their instability and inability to permeate cell membranes. NMR data corroborated by semiempirical theoretical calculations have shown that aminoalkyl-CDs form sufficiently stable complexes with both mono-and tri-phosphate forms of gemcitabine by simple mixing of the compounds in aqueous solution at physiological pH. Confocal microscopy and radioactivity counting experiments revealed that the developed systems enabled phosphorylated gemcitabine to penetrate efficiently into aggressive human breast cancer cells (MCF7), eventually leading to a substantial reduction of IC50 values. Moreover, compared to free drugs, phosphorylated metabolites of gemcitabine encapsulated in PCCDs displayed improved in vitro activities also on the aggressive human cancer cells CCRF-CEM Ara-C/8 C, a nucleoside transport-deficient T leukemia cell line. The current study offers the proof-of-principle that phosphorylated nucleoside drugs could be efficiently transported by PCCDs into cancer cells.
|
|
Roncin P., & Debiossac M. (2017). Elastic and inelastic diffraction of fast atoms, Debye-Waller factor, and Mössbauer-Lamb-Dicke regime. Phys. Rev. B., 96, 035415.
Résumé: The diffraction of fast atoms at crystal surfaces is ideal for a detailed investigation of the surface electronic
density. However, instead of sharp diffraction spots, most experiments show elongated streaks characteristic
of inelastic diffraction. This paper describes these inelastic profiles in terms of individual inelastic collisions
with surface atoms taking place along the projectile trajectory and leading to vibrational excitation of the local
Debye oscillator. A quasielastic regime where only one inelastic event contributes is identified as well as a
mixed quantum-classical regime where several inelastic collisions are involved. These regimes describe a smooth
evolution of the scattering profiles from sharp spots to elongated streaks merging progressively into the classical
diffusion regime.
|
|
|
Roucou, A., Dhont, G., Cuisset, A., Martin-Drumel, M. - A., Thorwirth, S., Fontanari, D., & Meerts, W. L. (2017). High resolution study of the ν2 and ν5 rovibrational fundamental bands of thionyl chloride: Interplay of an evolutionary algorithm and a line-by-line analysis. The Journal of Chemical Physics, 147(5), 054303.
|
|
Sadeddine, S., Enriquez, H., Bendounan, A., Das, P. K., Vobornik, I., Mayne, A. J., Dujardin, G., Sirotti, F., & Kara A. & Oughaddou H. (2017). Compelling experimental evidence of a Dirac cone in the electronic structure of a 2D Silicon layer. SCIENTIFIC REPORTS, 7, 44400.
Résumé: The remarkable properties of graphene stem from its two-dimensional (2D) structure, with a linear dispersion of the electronic states at the corners of the Brillouin zone (BZ) forming a Dirac cone. Since then, other 2D materials have been suggested based on boron, silicon, germanium, phosphorus, tin, and metal di-chalcogenides. Here, we present an experimental investigation of a single silicon layer on Au(111) using low energy electron diffraction (LEED), high resolution angle-resolved photoemission spectroscopy (HR-ARPES), and scanning tunneling microscopy (STM). The HR-ARPES data show compelling evidence that the silicon based 2D overlayer is responsible for the observed linear dispersed feature in the valence band, with a Fermi velocity of vF = 10+6 m.s−1 comparable to that of graphene. The STM images show extended and homogeneous domains, offering a viable route to the fabrication of silicene-based opto-electronic devices.
|
|
Salzano, G., Wankar, J., Ottani, S., Villemagne, B., Baulard, A. R., Willand, N., Brodin, P., Manet, I., & Gref, R. (2017). Cyclodextrin-based nanocarriers containing a synergic drug combination: A potential formulation for pulmonary administration of antitubercular drugs. International Journal Of Pharmaceutics, 531(2), 577–587.
Résumé: Tuberculosis (TB) remains a major global health problem. The use of ethionamide (ETH), a main second line drug, is associated to severe toxic side-effects due to its low therapeutic index. In this challenging context, “booster” molecules have been synthetized to increase the efficacy of ETH. However, the administration of ETH/booster pair is mostly hampered by the low solubility of these drugs and the tendency of ETH to crystallize. Here, ETH and a poorly water-soluble booster, so-called BDM43266, were simultaneously loaded in polymeric beta-cyclodextrin nanoparticles (p beta CyD NPs) following a “green” protocol. The interaction of ETH and BDM43266 with p beta CyD NPs was investigated by complementary techniques. Remarkably, the inclusion of ETH and BDM43266 pbCyD NPs led to an increase of their apparent solubility in water of 10-and 90-fold, respectively. Competition studies of ETH and BDM43266 for the CyD cavities of p beta CyD NPs corroborated the fact that the drugs did not compete with each other, confirming the possibility to simultaneously co-incorporate them in NPs. The drug-loaded NP suspensions could be filtered through 0.22 μm filters. Finally, the drug-loaded NPs were passed through a Microsprayer (R) to evaluate the feasibility to administer p beta CyD NPs by pulmonary route. Each spray delivered a constant amount of both drugs and the NPs were totally recovered after passage through the Microsprayer (R). These promising results pave the way for a future use of p beta CyD NPs for the pulmonary delivery of the ETH/BDM43266 pair. (C) 2017 Published by Elsevier B.V.
|
|
Sarsa, A., Alcaraz-Pelegrina, J. M., & Le Sech, C. (2017). The hydrogen atom confined by one and two hard cones. Physics Letters A, 381(8), 780–786.
Résumé: The bound states of the H atom in a semi-infinite space limited by one or two conical boundaries are studied. The exact solution when the nucleus is located at the apex of the conical boundaries is obtained. A rapid increase of the energy when the cone angle opens and tends to pi/2 is found. A second situation with the atom separated from the summit of the cone is considered. The changes on the energy and the electronic structure are analyzed. The quantum force is evaluated by calculating the energy derivative versus the distance to the cone vertex. One of the forces exerted on the tip of an Atomic Force Microscope can be modelized by a hard cone probing the electron cloud in the contact mode. Our numerical results show that the quantum force present an important dependence with the cone angle and it vanishes rapidly as the distance increases. (C) 2016 Elsevier B.V. All rights reserved.
|
|
Saunier, J., Herry, J. M., Yagoubi, N., & Marliere, C. (2017). Exploring complex transitions between polymorphs on a small scale by coupling AFM, FTIR and DSC: the case of Irganox 1076 (R) antioxidant. Rsc Advances, 7(7), 3804–3818.
Résumé: This study illustrates the significant interest of using atomic force microscopy (AFM) in force curve imaging mode for discovering and studying not easily detectable solid/solid transitions between polymorphs: we show that AFM in this imaging mode is a powerful means for studying in situ these transitions as they can be (i) detected in a very early step because of the high spatial resolution (at nanometer scale) of AFM and (ii) be distinguished from melting/recrystallization processes that can occur in the same temperature range. This was illustrated with the case of Irganox 1076 (R). This compound is a phenolic antioxidant currently used in standard polymers; it can bloom on the surface of polymer-based medical devices and its polymorphism might affect the device surface state and thus the biocompatibility. In a previous paper, the polymorphism of this compound was studied: four forms were characterized at a macroscopic level and one of them (form III) was identified on the surface of a polyurethane catheter. However, it was difficult to characterize the transitions between the different forms with only classical tools (DSC, FTIR and SAXS). In the present study, to evidence these transitions, we use AFM measurements coupled with a heating stage and we correlate them to ATR-FTIR measurements and to DSC analysis. This new study put into evidence a solid-solid transition between form III and II.
|
|
Shafizadeh, N., Soorkia, S., Gregoire, G., Broquier, M., Crestoni, M. E., & Soep, B. (2017). Dioxygen Binding to Protonated Heme in the Gas Phase, an Intermediate Between Ferric and Ferrous Heme. Chem.-Eur. J., 23(54), 13493–13500.
Résumé: With a view to characterizing the influence of the electronic structure of the Fe atom on the nature of its bond with dioxygen (O-2) in heme compounds, a study of the UV/Vis action spectra and binding energies of heme-O-2 molecules has been undertaken in the gas phase. The binding reaction of protonated ferrous heme [Fe-II-hemeH](+) with O-2 has been studied in the gas phase by determining the equilibrium of complexed [Fe-II-hemeH(O-2)](+) with uncomplexed protonated heme in an ion trap at controlled temperatures. The binding energy of O-2 to the Fe atom of protonated ferrous heme was obtained from a van't Hoff plot. Surprisingly, this energy (1540 +/- 170 cm(-1), 18.4 +/- 2 kJmol(-1)) is intermediate between those of ferric heme and ferrous heme. This result is interpreted in terms of a delocalization of the positive charge over the porphyrin cycle, such that the Fe atom bears a fractional positive charge. The resulting electron distribution on the Fe atom differs notably from that of a purely low-spin ferrous heme [Fe-II-heme(O-2)] complex, as deduced from its absorption spectrum. It also differs from that of ferric heme [Fe-III-heme(O-2)](+), as evidenced by the absorption spectra. Protonated heme creates a specific bond that cannot accommodate strong sigma donation.
|
|
Simon-Yarza, T., Gimenez-Marques, M., Mrimi, R., Mielcarek, A., Gref, R., Horcajada, P., Serre, C., & Couvreur, P. (2017). A Smart Metal-Organic Framework Nanomaterial for Lung Targeting. Angewandte Chemie-International Edition, 56(49), 15565–15569.
Résumé: Despite high morbidity and mortality associated with lung diseases, addressing drugs towards lung tissue remains a pending task. Particle lung filtration has been proposed for passive lung targeting and drug delivery. However, toxicity issues derived from the long-term presence of the particles must be overcome. By exploiting some of the ignored properties of nanosized metal-organic frameworks it is possible to achieve impressive antitumoral effects on experimental lung tumors, even without the need to engineer the surface of the material. In fact, it was discovered that, based on unique pH-responsiveness and reversible aggregation behaviors, nanoMOF was capable of targeting lung tissue. At the neutral pH of the blood, the nanoMOFs form aggregates with the adequate size to be retained in lung capillaries. Within 24 h they then disaggregate and release their drug payload. This phenomenon was compatible with lung tissue physiology.
|
|
Singh, V., Guo, T., Wu, L., Xu, J. H., Liu, B. T., Gref, R., & Zhang, J. W. (2017). Template-directed synthesis of a cubic cyclodextrin polymer with aligned channels and enhanced drug payload. Rsc Advances, 7(34), 20789–20794.
Résumé: Despite its 3D porous structure, the pharmaceutical applications of cyclodextrin based cross-linked polymers are limited due to their structural irregularities. To address this issue, a template-directed strategy is used to obtain cubic micro and nano cyclodextrin cross-linked polymer (CD-cubes) from cyclodextrin metal organic frameworks in this study. The well-organized gamma-CDs in MOFs were crosslinked by diphenyl carbonate by a facile single step chemical reaction. Scanning electron microscopy and X-ray diffraction analysis revealed the almost perfect cubic shapes of the particles with a disordered internal structure. Contrarily to the non-crosslinked materials which immediately dissolved in water, the CD-cubes were remarkably stable after extensive washing with water. The CD-cubes possessed a mesoporous structure with pore size in the range of 2-4 nm and showed much higher BET surface and 8 times higher adsorption capacity for doxorubicin as compared to conventional cyclodextrin-sponges.
|
|
Singh, V., Guo, T., Xu, H. T., Wu, L., Gu, J. K., Wu, C. B., Gref, R., & Zhang, J. W. (2017). Moisture resistant and biofriendly CD-MOF nanoparticles obtained via cholesterol shielding. Chemical Communications, 53(66), 9246–9249.
Résumé: A facile and one step-method was developed to enhance the water stability of CD-MOF nanoparticles through surface modification with cholesterol. CD-MOFs were able to maintain their cubic crystalline structures even after 24 h of incubation, well tolerated in vivo and could increase up to 4 times the blood half-life of DOX.
|
|
Singh, V., Xu, J. H., Wu, L., Liu, B. T., Guo, T., Guo, Z., York, P., Gref, R., & Zhang, J. W. (2017). Ordered and disordered cyclodextrin nanosponges with diverse physicochemical properties. Rsc Advances, 7(38), 23759–23764.
Résumé: Herein, in addition to conventional beta-CD-NSPs, the NSPs of alpha, gamma, HP-beta, methyl-beta, and SBE-beta cyclodextrins were synthesized by a simple modified approach and thoroughly characterized. The control of CDs derivatization over structural dimensions and properties was clearly observed. It is interesting to note the complete transformation of beta-CD from its crystalline form to its non-crystalline derivatives and the further reversal when the derivatives are prepared into NSPs including those of a and gamma-CDs (as observed by PXRD). The SEM images revealed the different morphologies and porous structure of NSPs and, in particular, the NSPs of methyl-beta-CD exhibited regular spherical shapes. Two drugs of different categories, doxorubicin and captopril, were evaluated for loading efficiencies, which were found to significantly vary with cross-linker ratio (1 : 4 and 1 : 6) and CD types. Together, all the synthesized NSPs provide a new horizon to try to solve existing problems relating to drug delivery.
|
|
|
Sukharev, M., & Charron, E. (2017). Molecular plasmonics: The role of rovibrational molecular states in exciton-plasmon materials under strong-coupling conditions. Phys. Rev. B, 95, 115406.
|
|
Szczepaniak, U., Kolos, R., Gronowski, M., Chevalier, M., Guillemin JC., Turowski M., Custer, T., & Crépin, C. (2017). Cryogenic Photochemical Synthesis and Electronic Spectroscopy of Cyanotetracetylene. JOURNAL OF PHYSICAL CHEMISTRY A, 121(39), 7374–7384.
Résumé: HC9N is a molecule of astrochemical interest. In this study, it was produced in cryogenic Ar and Kr matrices from UV-photolyzed diacetylene/cyanodiacetylene mixtures. Its strong phosphorescence was discovered and served for the identification of the compound. Vibrationally resolved phosphorescence excitation spectra gave insight into excited singlet electronic states. Two electronic systems were observed around 26 00034 000 cm(-1) and 35 000-50 000 cm(-1). Energies of the second excited singlet and the lowest triplet state were derived from analysis of these systems. Vibrational and electronic spectroscopic features were assigned with the assistance of density functional theory calculations. Some trends concerning the electronic spectroscopy of HC2+1N family molecules are presented.
|
|
Thon, R., Chin, W., Chamma, D., Gutiérrez-Quintanilla, A., Chevalier, M., Galaup, J. - P., & Crépin, C. (2017). W(CO) 6 in cryogenic solids: A comparative study of vibrational properties. Journal of Luminescence, 191, 78–86.
Résumé: A comparative study of the vibrational properties of W(CO)6 has been performed in different solids at cryogenic temperatures focusing on the IR absorption and the vibrational dynamics of the CO stretching mode of the organometallic compound. Guest-host interactions are investigated in doped solids through the linear IR spectroscopy and four-wave mixing techniques at different temperatures. We show how the host nature, the trapping site, the crystallographic ordering affect the properties of the guest molecule and in particular its vibrational dynamics.
|
|
|
Tong, Y., Nicolas, F., Kubsky, S., Oughaddou, H., Sirotti, F., Esaulov, V., & Bendounan, A. (2017). Interplay between Structural and Electronic Properties in 1,4,5,8-Naphthalenetetracarboxylic Dianhydride Films on Cu(100). JOURNAL OF PHYSICAL CHEMISTRY C, 121(9), 5050–5057.
|
|
Uriarte, I., Ecija, P., Lozada-Garcia, R., Carcabal, P., & Cocinero, E. J. (2017). Investigating the Conformation of the Bridged Monosaccharide Levoglucosan. Chemphyschem, , 01242.
Résumé: Levoglucosan is one of the main products of the thermal degradation of glucose and cellulose and is commonly used as a tracer for biomass burning. Herein we report a conformational analysis of levoglucosan under isolation conditions, by means of microwave spectroscopy coupled with ultrafast laser vaporization in supersonic expansions. We observed three different conformations of levoglucosan in the gas phase. They all share a common heavy atom rigid bicyclic structure. The difference between the three of them lies in the network of intramolecular hydrogen bonds that arises from the OH groups at positions 2, 3 and 4. The different combinations of H-bonds give richness to the conformational landscape of levoglucosan. The gas phase conformers obtained in this work are compared to the crystal structure of levoglucosan previously reported. Although the heavy atom frame remains unchanged, there are significant differences in the positions of the H-atoms. In addition, the levoglucosan structure can be compared to the related glucose, for which gas phase conformational studies exist in the literature. In this case, in going from glucose to levoglucosan, there is an inversion in the chair conformation of the pyranose ring. This forces the OH groups to adopt axial positions (instead of the more favorable equatorial positions in glucose) and completely changes the pattern of intramolecular H-bonds.
|
|
Vanfleteren, T., Földes, T., Herman, M., Liévin, J., Loreau, J., & Coudert, L. H. (2017). Experimental and theoretical investigations of H2O–Ar. The Journal of Chemical Physics, 147(1), 014302.
Résumé: We have used continuous-wave cavity ring-down spectroscopy to record the spectrum of H2O–Ar
H2O–Ar in the 2OH excitation range of H2O. 24 sub-bands have been observed. Their rotational structure (Trot = 12 K) is analyzed and the lines are fitted separately for ortho and para species together with microwave and far infrared data from the literature, with a unitless standard deviation σ=0.98 and 1.31, respectively. Their vibrational analysis is supported by a theoretical input based on an intramolecular potential energy surface obtained through ab initio calculations and computation of the rotational energy of sub-states of the complex with the water monomer in excited vibrational states up to the first hexad. For the ground and (010) vibrational states, the theoretical results agree well with experimental energies and rotational constants in the literature. For the excited vibrational states of the first hexad, they guided the assignment of the observed sub-bands. The upper state vibrational predissociation lifetime is estimated to be 3 ns from observed spectral linewidths.
|
|
|
Wakelam, V., Bron, E., Cazaux, S., Dulieu, F., Gry, C., Guillard, P., Habart, E., Hornekær, L., Morisset, S., Nyman, G., Pirronello, V., Price, S. D., Valdivia, V., Vidali, G., & Watanabe, N. (2017). H 2 formation on interstellar dust grains: The viewpoints of theory, experiments, models and observations. Molecular Astrophysics, 9, 1–36.
|
|
|
Wang, L., Shen, Y., Yang, Y., Lu, W., Li, W., Wei, F., Zheng, G., Zhou, Y., Zheng, W., & Cao, Y. (2017). Stern-Layer Adsorption of Oligonucleotides on Lamellar Cationic Lipid Bilayer Investigated by Polarization-Resolved SFG-VS. ACS Omega, 2(12), 9241–9249.
|
|
Wankar, J., Salzano, G., Pancani, E., Benkovics, G., Malanga, M., Manoli, F., Gref, R., Fenyvesi, E., & Manet, I. (2017). Efficient loading of ethionamide in cyclodextrin-based carriers offers enhanced solubility and inhibition of drug crystallization. International Journal Of Pharmaceutics, 531(2), 568–576.
Résumé: Ethionamide (ETH) is a second line antitubercular drug suffering from poor solubility in water and strong tendency to crystallize. These drawbacks were addressed by loading ETH in beta-cyclodextrin (beta CyD)-based carriers. The drug was incorporated in a molecular state avoiding crystallization even for long-term storage and obtaining a tenfold increased solubility up to 25 mM. The binding of ETH to polymeric beta CyD nanoparticles (p beta CyD NPs) was investigated in neutral aqueous medium by means of solubility phase diagrams, circular dichroism (CD) and UV-vis absorption and compared with the corresponding beta CyD monomer. The binding constants and the absolute CD spectra of the drug complexes were determined by global analysis of multiwavelength data from spectroscopic titrations. The spectroscopic and photophysical properties of the complexes evidenced an alcohol-like environment for ETH included in the cavity. Additionally, ETH was found to be located not only in beta CyD cavities, but also in confined microdomains inside the crosslinked NPs. This double modality of complexation together with a slightly higher binding constant makes the utilization of p beta CyD NPs preferable over the monomeric beta CyDs. In order to pave the way to future in vitro experiments, fluorescein labeled p beta CyDs were synthesized. Interestingly the FITC labeling did not hamper the encapsulation of ETH and the drug improved the fluorescent signal of FITC molecules. The beta CyD-based carriers appeared as versatile “green” systems for efficient incorporation and future delivery of ETH. (C) 2017 Elsevier B.V. All rights reserved.
|
|
Xu, X. N., Wang, C. F., Li, H. Y., Li, X., Liu, B. T., Singh, V. J., Wang, S. X., Sun, L. X., Gref, R. X., & Zhang, J. W. (2017). Evaluation of drug loading capabilities of gamma-cyclodextrin-metal organic frameworks by high performance liquid chromatography. Journal Of Chromatography A, 1488, 37–44.
Résumé: Drug loading into gamma-cyclodextrin-metal organic frameworks (gamma-CD-MOFs) using the impregnation approach is a laborious process. In this study, a gamma-CD-MOF construct (2-5 μm particle diameter) was used as the stationary phase under HPLC conditions with the aim to correlate retention properties and drug loading capability of the CD-based structure. Ketoprofen, fenbufen and diazepam were chosen as model drugs with m-xylene as a control analyte to investigate the correlation of drug loading and their chromatographic behaviour in the gamma-CD-MOF column. Furthermore, gamma-CD itself was also prepared as the stationary phase by coupling with silica in the column to illustrate the enhanced interaction between drugs and gamma-CD-MOF as a reference. The retention and loading efficiency of the drugs were determined with different ratios of hexane and ethanol (10:90, 20:80, 50:50, 80:20, 90:10, v/v) at temperatures of 20, 25, 30 and 37 degrees C. With the increment in hexane content, the loading efficiency of ketoprofen and fenbufen increased from 2.39 +/- 0.06% to 4.38 +/- 0.04% and from 5.82 +/- 0.94% to 6.37 +/- 0.29%, respectively. The retention time and loading efficiency of ketoprofen and diazepam were the lowest at 30 degrees C while those of fenbufen had the different tendency. The excellent relation between the retention and loading efficiency onto gamma-CD-MOF could be clearly observed through mobile phase and temperature investigation. In conclusion, a highly efficient chromatographic method has been established to evaluate the drug loading capability of gamma-CD-MOF. (C) 2017 Elsevier B.V. All rights reserved
|
|
Yalouz, S., Falvo, C., & Pouthier, V. (2017). The excitonic qubit coupled with a phonon bath on a star graph: anomalous decoherence and coherence revivals. Quantum Information Processing, 16(6), 143.
Résumé: Based on the operatorial formulation of perturbation theory, the dynamical properties of a Frenkel exciton coupled with a thermal phonon bath on a star graph are studied. Within this method, the dynamics is governed by an effective Hamiltonian which accounts for exciton–phonon entanglement. The exciton is dressed by a virtual phonon cloud, whereas the phonons are dressed by virtual excitonic transitions. Special attention is paid to the description of the coherence of a qubit state initially located on the central node of the graph. Within the nonadiabatic weak coupling limit, it is shown that several timescales govern the coherence dynamics. In the short time limit, the coherence behaves as if the exciton was insensitive to the phonon bath. Then, quantum decoherence takes place, this decoherence being enhanced by the size of the graph and by temperature. However, the coherence does not vanish in the long time limit. Instead, it exhibits incomplete revivals that occur periodically at specific revival times and it shows almost exact recurrences that take place at particular super-revival times, a singular behavior that has been corroborated by performing exact quantum calculations.
|
|
Yalouz, S., Pouthier, V., & Falvo, C. (2017). Exciton-phonon dynamics on complex networks: Comparison between a perturbative approach and exact calculations. Pre, 96(2), 022304.
Résumé: A method combining perturbation theory with a simplifying ansatz is used to describe the exciton-phonon dynamics in complex networks. This method, called PT, is compared to exact calculations based on the numerical diagonalization of the exciton-phonon Hamiltonian for eight small-sized networks. It is shown that the accuracy of
PT depends on the nature of the network, and three different situations were identified. For most graphs,
PT yields a very accurate description of the dynamics. By contrast, for the Wheel graph and the Apollonian network, PT reproduces the dynamics only when the exciton occupies a specific initial state. Finally, for the complete graph, PT breaks down. These different behaviors originate in the interplay between the degenerate nature of the excitonic energy spectrum and the strength of the exciton-phonon interaction so that a criterion is established to determine whether or not PT is relevant. When it succeeds, our study shows the undeniable advantage of PT in that it allows us to perform very fast simulations when compared to exact calculations that are restricted to small-sized networks.
|
|
Yengui, M., Duverger, E., Sonnet, P. & Riedel, D. (2017). A two-dimensional ON/OFF switching device based on anisotropic interactions of atomic quantum dots on Si(100):H. Nat. Commun., 8, 2211.
Résumé: Controlling the properties of quantum dots at the atomic scale, such as dangling bonds, is a general motivation as they allow studying various nanoscale processes including atomic switches, charge storage, or low binding energy state interactions. Adjusting the coupling of individual silicon dangling bonds to form a 2D device having a defined function remains a challenge. Here, we exploit the anisotropic interactions between silicon dangling bonds on n-type doped Si(100):H surface to tune their hybridization. This process arises from interactions between the subsurface silicon network and dangling bonds inducing a combination of
Jahn–Teller distortions and local charge ordering. A three-pointed star-shaped device prototype is designed. By changing the charge state of this device, its electronic properties are shown to switch reversibly from an ON to an OFF state via local change of its central gap. Our results provide a playground for the study of quantum information at the nanoscale.
|
|
