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The IC adsorption mechanism on the Bi2O3 doped MgO nanosorbents occurred through the chemisorption process.

Inorganic materials used for biomedical applications such as implants generally induce the adsorption of proteins on their surface. To control this phenomenon, the bioinspired peptidomimetic polymer 1 (PMP1), which aims to reproduce the adhesion of mussel foot proteins, is commonly used to graft specific proteins on various surfaces and to regulate the interfacial mechanism. To date and despite its wide application, the elucidation at the atomic scale of the PMP1 mechanism of adsorption on surfaces is still unknown. The purpose of the present work was thus to unravel this process through experimental and computational investigations of adsorption of PMP1 on gold, TiO2, and SiO2 surfaces. A common mechanism of adsorption is identified for the adsorption of PMP1 which emphasizes the role of electrostatics to approach the peptide onto the surface followed by a full adhesion process where the entropic desolvation step plays a key role. Besides, according to the fact that mussel naturally controls the oxidation states of its proteins, further investigations were performed for two distinct redox states of PMP1, and we conclude that even if both states are able to allow interaction of PMP1 with the surfaces, the oxidation of PMP1 leads to a stronger interaction.

The adsorption mode of ammonia on the (001) surface of kaolinite was explored using the periodic DFT/PBE-D3 method. The thermodynamics and electronic properties such as adsorption energy, bond lengths and density of states were calculated to investigate the adsorption mechanism. Calculated adsorption energies were negative for ammonia-kaolinite complexes indicating a favorable exothermic process. The corrections of the van der Waals dispersion play an important role in stabilizing ammonia-kaolinite interactions. The maximum surface coverage is found to 4.3 molecules/nm2. The geometric parameters, Bader charges and PDOS analysis results showed that ammonia is adsorbed on the surface (001) of kaolinite clay by a hydrogen bond, mainly through the electrostatic interaction between the hydroxyls group of the surface and the nitrogen atom of NH3 molecule. The analysis of the computed infrared spectra of free and adsorbed NH3 highlights the impact of adsorption on its characteristic stretching and bending modes.

Ba-loaded ZnO nanoparticles (Ba/ZnO) were obtained by the co-precipitation process and employed as a sorbent for Congo Red (C32H22N6Na2O6S2) dye (CR). Physicochemical parameters such as particle size, pH, and contact time were checked to characterize the adsorption process. The maximum adsorption capacity of Ba/ZnO NPs for CR (1614.26 mg/g) proves its potential utility in the elimination of CR dye from wastewater. The adsorption mechanism was studied via infrared spectroscopy and density functional theory calculations. The geometrical parameters and electronic properties of the CR-Ba/ZnO complex, particularly the interaction energy, the density of states, and the charge transfer, highlighted the Ba-ion mediation in the chemical bond formation between CR and the surface. The interaction between CR and Ba-doped ZnO has found to show strong chemisorption with charge transfer between the SO3- group and adsorbed Ba2+ ion on the surface.

International audience; WO 3 nanostructures have been synthesized on Au(111) through solution processing. Three types of structures have been obtained, reticulated polymeric structures, two dimensional WO 3 (111) and three-dimensional islands. Their electronic properties have been probed by scanning tunneling spectroscopy. The reticulated structure has a featureless spectrum. WO 3 (111) shows n-type semiconducting properties with resonances corresponding to surface states arising from W 5d states. Those oxyde nanostructures are efficiently decoupling the electronic states of molecular adsorbates from the metal substrate.

International audience; The affinity of AtO+ for around 20 model ligands (L), carrying functionalized oxygen, sulfur, and nitrogen atoms, has been assessed through a combined experimental and theoretical methodology. Significant equilibrium constants (KL ∼ 104) have been measured for sulfur-containing compounds, in agreement with the previously highlighted, relatively stable radiolabeling of SH-containing proteins with 211At. Conversely, no interaction occurs in the aqueous phase for their oxygenated counterparts, but higher affinities (KL > 106) have been determined for nitrogen-based ligands, including aromatic nitrogen heterocycles. The quantum mechanical calculations definitively ruled out any rationale based on either the metallic character of astatine or its guessed softness; the favored interactions all involve specifically the oxygen atom of AtO+, leading to the formation of covalent O–S or O–C single bonds.

International audience; It is well known that the electrical conductance of molecular junctions in the tunneling regime varies exponentially with the length of the molecular backbone. This behavior is strongly influenced by anchoring groups, which connect the molecular backbone to the electrodes and locate the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) resonances with respect to the Fermi level. Nevertheless, most of the studies have been performed on symmetric junctions, namely, using the same electrodes and anchoring groups at both sides of the junctions. Only recently, there have been some reports detailing the influence of introducing asymmetry into single-molecule junctions, using different contacts or different anchoring groups at either end of the molecular bridge. These studies have revealed that such junction asymmetry strongly impacts electrical characteristics. In this study, Au and graphene electrodes were used to provide asymmetry to a single-molecule junction. The conductance and length dependence of amine and methyl sulfide-terminated oligo(phenylene ethynylene) have been determined experimentally and theoretically. The impact of introducing this asymmetry has been quantified by comparing the conductance and β values of oligo(phenylene ethynylene) (OPE)based molecules within Au/Au electrodes and Au/graphene junctions, respectively. Our results show that the introduction of a graphene electrode leads to lower conductance values and attenuation factors, similar to what has been previously observed in alkane chains. This is attributed to a shift of the electronic molecular levels toward the Fermi level, mainly driven by acetylene groups linking adjacent phenyl groups.

International audience; NEGF and DFT calculations within Fisher Lee formalism are used to explore the effect of the asymmetry and the strength of coupling with the electrode on transport properties of (1-(2-bisthienyl)benzene) oligomers. Electronic analysis of metal-molecule interactions reveals the ionic nature of Ti-C bonds inducing an interfacial dipole. The Ti d-orbitals are found to be strongly coupled to the lowest unoccupied orbital of BTB, thus facilitating charge transfer from Ti to the molecule. The hole transport mechanism is found in the cases of Au-(BTB)$_n$-Au and Au-(BTB)$_n$-Ti while possible combined hole and electron transport is predicted in the case of Ti-(BTB)$_n$-Ti.

The adsorption of conjugated molecules on graphene is an attractive way of developing new two-dimensional materials with tailored properties. We investigate here the adsorption of metal-based porphyrins on graphene. The energetics of adsorption of different metalloporphyrins are explored and the electronic properties are analyzed, showing calculated band gaps in good agreement with previous reports. Then, we address the design of adsorbates to give better adsorption and band gaps. We show that adsorption depends on both the atomic radius and the d-orbital occupancy. The band gaps obtained correlate with the proximity of the 3d orbitals to the Fermi level.

Density-functional theory calculations including dispersion at BLYP-D3(BJ)/def2-SVP level of theory were performed for a series of systems based on cyclodextrin complexation with boron-based aromatic compounds. Elaborated investigations were carried out using different quantum chemical parameters such as computed complexation energies, theoretical association constants and natural bond orbital (NBO) analysis. Several configurations and inclusion modes were considered in this work. The calculated complexation energies were consistent with the experimental classification of these systems on the basis of occurring interactions. Reduced density gradient (RDG) and independent gradient model (IGM) approaches determined the nature and strength of non-covalent interactions which played a central role in the formation of the complexes. Thus, phenylboronic acid (PBA) and benzoxaborole (Bxb) act mainly as hydrogen-bonded complexes with β-cyclodextrin, while mainly Van der Waals (vdW) interactions stabilize both catechol (PhBcat) and pinacol esters of phenylboronic acid (PhBpin) complexes. The ferroceneboronic acid (FcBA) exhibits a mixture of H-bonds and vdW interactions with β-cyclodextrin.

Molecular dynamic (MD) simulations of the Combined Condensation and Annealing (CCA) of free carbon atoms was used to investigate the statistical abundance and stability of neutral carbon nanostructures for a cluster size between 2 and 54 atoms. During these CCA MD-simulations carbon atoms are submitted to a condensation/heating phase, a CTR phase at a prescribed annealing temperature and a cooling phase. Numerical experiments showed that the determination of the statistical abundances requires at least 100 ns condensation/heating phase, 100 ns CTR phase at the annealing temperature and 100 ns cooling phase. The clusters obtained by CCA MD-simulations are dominated by linear structures for n = 2–5, mono-ring for n = 6–15, multi-ring structures for n = 16–18, 2D graphene-like structure for sizes in the range n = 19–29 and cage-like structure above n = 30. Open cage structures are obtained at temperature around 2000 K, while closed cage structures dominate at 3000 K. For even larger temperature, i.e., 4000 K, the dominant structures are 2D and 3D multi-ring structures, 2D graphene-like structure remaining quite significant. The resulting bond energy versus cluster size variation is in good agreement with those obtained by other approaches.

International audience; Monodispersed about 5 nm sized CoO crystals were prepared by forced hydrolysis of cobalt(II) acetate in diethyleneglycol (DEG) solvent. The adsorption of the solvent molecules on these primary nanocrystals caused their in-situ oriented aggregation resulting in the precipitation of textured submicrometer-sized polycrystals. X-ray diffraction, Infrared spectroscopy, Transmission Electron Microscopy and Thermogravimetry analyses coupled to ab-initio modeling were applied to understand the adsorption mechanism of the alcohol moieties and the role of the molecule-to-surface and molecule-to-molecule interactions in the crystal growth mechanism of these polycrystals. We showed that DEG moieties are mainly adsorbed at the top of the cobalt (100) surface atoms and the process does not involve the whole molecule but only one of its extreme oxygen atoms. As a consequence, adsorbed DEG molecules exhibit an extended configuration which is favorable to intermolecule hydrogen bonding from one covered nanocrystal to another. Interestingly, at high surface coverage, the energy required for DEG attachment to the crystal surface is found to be 18.6 kJ/mol per molecule, while that required for hydrogen bonding between a bearing molecule and a neighbor one is found to be 36,4 kJ/mol per molecule, meaning that the collective departure of an assembly of DEG from the surface of CoO nanocrystals is therodynamically easier, leading thus to the observed final morphology.

International audience; A promising solution to improve the performance of Bulk heterojunction organic photovoltaic devices is the insertion of functionalized self-assembled monolayers (SAMs) at the interface between the Electron Transporting Layer (ETL) and the active layer. By grafting such dipolar SAMs based on Y-PP-COOH (P = Phenyl, Y = CH3O, F)) on a ZnO ETL, both the electronic and the chemical properties of the interface are modified. The growth of the active blend the poly(3-hexylthiophène)-[6,6]-phenyl C61-butyric acid methylester blend deposited onto the SAMs is also altered. The dipole with a component oriented perpendicularly to the ZnO surface modifies the ZnO work function whereas the surface energy of the SAM influences the microstructuration of the active material. When we analyze the inverted photovoltaic cell, we find that the two effects may be distinguished: the CH3O moiety favorably affects the electrical transfer of carriers with mainly an improvement of the open-circuit voltage Voc whereas fluorine disfavors both electron extraction and blend microstructure quality, with a lower Voc and electrical current density Jsc. 2

International audience; Rapid and accurate detection of proteins in biological fluids is increasingly required in the biomedical environment. Actually, it is performed with conventional techniques, which are generally run by robotized platforms at centralized laboratories. In this work, molecular dynamics calculations and an experimental procedure were conducted to set up electrochemical sensors based on polypyrrol (PPy) molecular imprinted polymers (MIP) for proteins detection. Here, prostate-specific antigen (PSA) was selected as a template model. Computational calculations indicate that for any PPy conformation and any amino-acid location in the protein, PSA molecules remain strongly inserted in the PPy polymer without biological alterations. One from possible orientations, appeared to be most probable as it presents the lowest absorption energy (-363 kcal mol-1) and largest contact area (4034.1 Å2). The device was then elaborated by in situ electropolymerization of PPy films. MIP's thickness and extraction duration were optimized by chronoamperometry. Square wave voltammetry technique was investigated for PSA detection in standard solution in the concentration range of 3x10 -8 ng.ml-1- 300 ng ml-1. According to the Hill equation, the equilibrium dissociation constant Kdbetween PSA and its imprint was estimated at Kd = (1.02 ± 0.54) × 10-14 M, confirming the strong binding between the designed MIP and the protein as predicted by the computational study. PSA concentration values directly measured in 35 human serum samples were found closely correlated to those measured by the ELISA technique. The promising fast and low-cost sensor might be used successfully for proteins detection at low concentrations with high selectivity and reproducibility.

Highly sensitive multicomponent materials designed for the recognition of hazardous compounds request control over interfacial chemistry. The latter is a key parameter in the construction of the sensing (macro) molecular architectures. In this work, multi-walled carbon nanotubes (CNTs) were deposited on diazonium-modified, flexible indium tin oxide (ITO) electrodes prior to the electropolymerization of pyrrole. This three-step process, including diazonium electroreduction, the deposition of CNTs and electropolymerization, provided adhesively-bonded, polypyrrole-wrapped CNT composite coatings on aminophenyl-modified flexible ITO sheets. The aminophenyl (AP) groups were attached to ITO by electroreduction of the in-situ generated aminobenzenediazonium compound in aqueous, acidic medium. For the first time, polypyrrole (PPy) was electrodeposited in the presence of both benzenesulfonic acid (dopant) and ethylene glycol-bis(2-aminoethylether)-tetraacetic acid (EGTA), which acts as a chelator. The flexible electrodes were characterized by XPS, Raman and scanning electron microscopy (SEM), which provided strong supporting evidence for the wrapping of CNTs by the electrodeposited PPy. Indeed, the CNT average diameter increased from 18 &plusmn, 2.6 nm to 27 &plusmn, 4.8, 35.6 &plusmn, 5.9 and 175 &plusmn, 20.1 after 1, 5 and 10 of electropolymerization of pyrrole, respectively. The PPy/CNT/NH2-ITO films generated by this strategy exhibit significantly improved stability and higher conductivity compared to a similar PPy coating without any embedded CNTs, as assessed by from electrochemical impedance spectroscopy measurements. The potentiometric response was linear in the 10&minus, 8&ndash, 3 &times, 10&minus, 7 mol L&minus, 1 Pb(II) concentration range, and the detection limit was 2.9 &times, 9 mol L&minus, 1 at S/N = 3. The EGTA was found to drastically improve selectivity for Pb(II) over Cu(II). To account for this improvement, the density functional theory (DFT) was employed to calculate the EGTA&ndash, metal ion interaction energy, which was found to be &minus, 374.6 and &minus, 116.4 kJ/mol for Pb(II) and Cu(II), respectively, considering solvation effects. This work demonstrates the power of a subtle combination of diazonium coupling agent, CNTs, chelators and conductive polymers to design high-performance electrochemical sensors for environmental applications.

Novel elastomer/modified carbon nanotube nanocomposites were prepared by melt mixing ethylene vinyl acetate (EVA) matrix with dye-grafted multiwalled carbon nanotubes (MWCNTs, CNTs in short). The latter were prepared by spontaneous reactions of diazotized Azure A (AA-N 2 + ), Neutral Red (NR-N 2 + ) and Congo Red (CR-N 2 + ) dyes with CNTs in water at RT. The dispersion of the dye-modified CNTs was facilitated with cholesteryl 1-pyrenecarboxylate (PyChol) surfactant. The EVA/modified CNT nanocomposites were employed as optothermal actuators. The photo-actuation measurements were performed on the un-stretched as well as the stretched strips of pristine EVA and EVA/CNT-dye nanocomposites using a dynamic mechanical analyzer (DMA) equipped with a red light emitting diode (red LED) at a wavelength of 627 nm illuminated either 10 s or 30 s. The concentration of modified dyes, the use of PyChol surfactant and the applied pre-strain were the parameters investigated in this work. To sum up, the nanocomposites prepared so far could be regarded as promising optothermal actuators used for touch displays visually impaired people.

Density functional theory has been used to investigate the adsorption and dissociation of 5-hydroxy-3-hexanediol-1,4-naphthaquinone (Jug-C4-thiol) at a coverage of p(4 × 4) on a Au(111) surface. Both physisorption and chemisorption processes are investigated. For each process, the surface energy potential is explored by an exhaustive test of the adsorption site. The most favorable site is found to be face-centered cubic. The adsorption energies are less than − 0.20 eV in the case of physisorption, while they range from − 1.70 to − 1.92 eV for chemisorption. The effect of the naphthoquinone function is negligible in the adsorption process. The alkyl chain inhibits electron delocalization between the surface and the conjugated head of the molecule. Analysis of the bonding shows the formation of two ionocovalent bonds between the sulfur and the gold atoms. The thermodynamics and kinetics of S–H bond dissociation are studied. The results reveal that adsorption involves a dissociation path in which a hydrogen atom moves to the most neighboring site and a hydrogen atom migrates to its most stable site. The maximum barrier energy of the first step is less than 2.7 eV while the migration barrier does not exceed 0.5 eV.

Hydrogenation of olefins catalyzed by a ruthenium II complex, the RuH2(η2-H2)2(P(C6H11)3)2 have been studied using DFT/B3LYP method. The establishment of agostic Ru-C bonds followed by the migration of hydrogen atoms from one cyclohexyl of phosphine ligand is the main particularity of this reaction. Transition states associated with the latter migrations were determined. Each one is trizonal and involves three different areas and ten active atoms. Intrinsic Reaction Coordinate (IRC) calculations allowed following their movements during this reaction. Energy profiles confirm the simultaneous movement of all these active atoms. Molecular orbitals of all involved species were analyzed and related to ruthenium atomic orbitals. Obtained results highlight the catalytic effect of Ru atom able, thanks to its versatility, to redistribute its AOs and to control the exchange process of concerned ligands. Those transition states are currently among the most complicated ones to be calculated up today.

The issue of supercell size convergence for a metal grain boundary (GB) traction-separation curve is addressed through an atomistic first principles based uniaxial tensile test. Focussing on the face-centred cubic Al Σ5 [1 0 0] 36.87° twist GB, the cell size convergence problem is reformulated to involve a local region hosting a fixed number of atoms, fully contained in each supercell under investigation. In contrast with the original task, the modified problem is shown to be easily tractable: convergence is achieved when the local region covers the part of the GB environment affected significantly structurally and electronically by the GB. For the chosen test system, this criterion is met at a very modest region (and hence supercell) size. It is proposed that a robust integration of the results in a larger scale model scheme may be accomplished by linking the atomistic traction-separation curve to a relation that connects structural distortions on either side of the local region boundary. Application to other CSL-based metal symmetric GBs should be straightforward.

First-principles calculations based on density functional theory and Grand Canonical Monte Carlo (GCMC) simulations are carried out to study the structure of a new Aluminum Metal-Organic Framework, MOF-519, and the possibility of storing molecular hydrogen therein. The optimized structure of the inorganic secondary building unit (SBU) of MOF-519 formed by eight octahedrally coordinated aluminum atoms is presented. The different storage sites of H 2 inside the SBU and the BTB ligand are explored. Our results reveal that the SBU exhibits two different favorable physisorption sites with adsorption energies of −12.2 kJ/mol and −1.2 kJ/mol per hydrogen molecule. We have also shown that each phenyl group of BTB has three stable H 2 adsorption sites with adsorption energies between −6.7 kJ/mol and −11.37 kJ/mol. Using GCMC simulations; we calculated the molecular hydrogen (H 2 ) gravimetric and volumetric uptake for the SBU and MOF-519. At 77 K and 100 bar pressure, the hydrogen uptake capacity of SBU is considerably enhanced, reaching 16 wt.%. MOF-519 has a high gravimetric uptake, 10 wt.% at 77 K and 4.9 wt.% at 233 K. It has also a high volumetric capacity of 65 g/L at 77 K and 20.3 g/L at 233 K, indicating the potential of this MOF for hydrogen storage applications.

Single-stranded RNA aptamers have emerged as novel biosensor tools. However, the immobilization procedure of the aptamer onto a surface generally induces a loss of affinity. To understand this molecular process, we conducted a complete simulation study for the Flavin mononucleotide aptamer for which experimental data are available. Several molecular dynamics simulations (MD) of the Flavin in complex with its RNA aptamer were conducted in solution, linked with six thymidines (T6) and, finally, immobilized on an hexanol-thiol-functionalized gold surface. First, we demonstrated that our MD computations were able to reproduce the experimental solution structure and to provide a meaningful estimation of the Flavin free energy of binding. We also demonstrated that the T6 linkage, by itself, does not generate a perturbation of the Flavin recognition process. From the simulation of the complete biosensor system, we observed that the aptamer stays oriented parallel to the surface at a distance around 36 Å avoiding, this way, interaction with the surface. We evidenced a structural reorganization of the Flavin aptamer binding mode related to the loss of affinity and induced by an anisotropic distribution of sodium cationic densities. This means that ionic diffusion is different between the surface and the aptamer than above this last one. We suggest that these findings might be extrapolated to other nucleic acids systems for the future design of biosensors with higher efficiency and selectivity.

In this contribution, we propose a systematic and accurate theoretical methodology to describe the elementary physical processes occurring in sputtering discharges, generating a carbon-containing plasma in which medium size clusters are growing (Cn, n

We present a computational investigation of adsorption on graphene concerning the second-row diatomic molecules (Li2, B2, C2, O2, N2 and F2). The adsorption energies and the nature of the interaction between guest molecules and graphene, in both periodic and non-periodic approaches, were evaluated using dispersion-corrected density functional theory calculations (DFT/PBE-D3). A periodic graphene model, used to tune the coverage, is compared with a cluster model in which the graphene sheet is represented by coronene. The results of both energetic and electronic state analyses reveal a variety of adsorption processes. While B2 and C2 adsorb in a bridge position in order to establish two covalent bonds with the surface, O2 and N2 are clearly physisorbed in positions parallel to the surface. Li2 and F2 show intermediate behavior, with strong physisorption accompanied by charge transfer.

Synthetic siderophores derivated from 8-HydroxyQuinoline (HQ) present various biological and pharmacological activities, such as anti-neurodegenerative or anti-oxydative. However, their affinity towards iron(III) seems to depend on the position (i.e., 7 or 2) of the HQ substitution by an electron withdrawing group. Two ester-derivatives of HQ at 2- and 7-position are synthesized and their respective iron-complexation is characterized by a joined experimental and theoretical work. By investigating the stability of all the possible accessible spin states of the iron(III) complexes at density-functional theory (DFT) level, we demonstrate that the high-spin (HS) state is the most stable one, and leads to a UV/vis absorption spectrum in perfect match with experiments. From this DFT protocol, and in agreement with the experimental results, we show that the ester functionalization of HQ in 2-position weakens the formation of the iron(III) complex while its substitution in 7-position allows a salicylate coordination of the metal very close to the ideal octahedral environment.

International audience; Molecular Dynamics (MD) simulation was used to identify the stable structures of carbon clusters Cn (10=20, grahene and fullerene structures are obtained to be the most stable structures involved in dusty plasmas.

We report here the facile synthesis of a new series of hydroxy-thioxo-imidazole carboxylates in good yields using the cyanomethyl anion as an electrogenerated base which is formed when dry acetonitrile is electrolyzed at constant current, followed by addition of different thioureas and diazirine-3,3-dicarboxylate. The mechanism of the reaction, NMR shifts and IR are discussed and compared to density functional theory calculations.

The uniaxial tensile test response of a H decorated Σ5 [100] twist grain boundary (GB) in face-centered-cubic Al has been examined with first principles. The impurity shows a strong tendency to relocate during loading. To capture these H movements, the standard model framework was extended to probe loading-unloading hysteresis. If the maximum tensile stress accepted by the H decorated GB in the slow fracture limit is reached before the maximum acceptable strain, exceeding this stress may trigger a H influx-controlled destabilization, as opposed to 'immediate' breakage. Such 'delayed' failure appears likely whenever the H attraction to a GB displays a monotonic decrease with increased loading.

International audience; 104 MHz surface acoustic wave (SAW) sensors functionalized with new anthracene derivates were designed for the detection of lead ions (Pb2+) in liquid media. On the basis on quantum chemical calculations, three anthracene molecules have been synthetized and tested: 4-(9-anthrylmethoxy) benzyl[4-(9-anthrylmethoxy)phenyl]sulfone (BPS-AN); 9-{[4-({[4-(9 anthrylmethoxy) phenyl]sulfanyl}methyl)]methyl] anthracene (TDP-AN) and 2,2-bis(4 anthracenylmethoxy-1,1′-biphenyl (BP-AN). Gravimetric results indicate that the affinity of BPS-AN towards Pb2+ ions is superior to that of TDP-AN and BP-AN, confirming thus the computational approach. The designed BPS-AN SAW sensor has a sensitivity of [7.2 ± 4.6]×108 [°/M], a limit of detection (LOD) of 22 pM, and displayed very high affinity to lead ions with an apparent dissociation constant Kd of order of (1.1 ± 2.7) × 10−10. Selectivity was investigated by both gravimetry and DFT calculation. Results indicate that the designed sensor is more sensitive to lead cations than copper and mercury ones. A tetrabutylphosphonium (TBP) lactate ionic liquid (IL) solution was used to regenerate the SAW sensor, permitting its further reuse a dozen times without degrading the BPS-AN recognition layer.

This work aimed to evaluate and optimize parameters for the removal of barium (Ba2+) ions on ZnO spherical nanoparticles. Spherical ZnO nanoparticles was fabricated using over-simplistic applying arabinose sugar followed by evaporation methods. The physicochemical properties of the ZnO nanoparticles were studied using XRD, SEM, EDX, and FTIR. The maximum adsorption capacity of Ba2+ by ZnO nanoparticles was 64.6 mg/g. In isotherm studies, the Langmuir model is well-fitted to the sorption data. Kinetic pseudo-second-order models best illustrated the adsorption mechanism of barium (Ba2+) ions. Based on the density functional theory calculation, the barium (Ba2+) ion adsorption onto the ZnO surface is strong chemisorption with an exothermic adsorption energy of -291.3 kJ/mol.

We report here a theoretical investigation of molecular hydrogen storage on [Pb 2 (TETA)]·6H 2 O. Because of their high surface areas, Pb-based MOFs are promising hydrogen storage systems. Ab-initio calculations using density functional theory at the PBE level have been performed to explore the most energetically favorable adsorption sites, and to determine the nature of hydrogen bonding and the storage capacity. Our results show clearly that a hydrogen molecule can be adsorbed on different sites of the MOF with high adsorption energies per site of over 10 kJ/mol. [Pb 2 (TETA)]·6H 2 O exhibits significant elastic properties enabling it to store up to 21 molecules per unit cell. Furthermore, analysis of the nature of the bonding shows that these molecules are physisorbed on the surface, and, therefore, can be readily desorbed for use as fuel.

International audience; The uniaxial tensile test response of a H decorated Σ5 [100] twist grain boundary (GB) in face-centred-cubic Al has been examined with first principles. The impurity shows a strong tendency to relocate during loading. To capture these H movements, the standard model framework was extended to probe loading-unloading hysteresis. Due to the strong monotonic decrease in the H formation energy with rising GB elongation, the maximum tensile stress accepted by the H decorated GB in the slow fracture limit generally is reached before breakage becomes thermodynamically favourable. For any intact GB configuration visited upon exceeding this stress, the assumption of global chemical equilibrium is argued to be violated. Moreover, while breakage remains ensured from the slow fracture limit considerations, it may in practice require the influx of H to the GB vicinity. A quantitative analysis of GB destabilisation in this scenario requires multi-scale modelling even in the slow fracture limit.

International audience; This study concerns the design of surface acoustic wave sensors functionalized with bisphenol S based molecules for lead ions detection. (4-hydroxyphenyl, 4′-benzyloxyphenyl) sulfone (M1), (4-hydroxyphenyl,4′-anthrylmethyloxyphenyl) sulfone (M2) and (4,4′-bis (anthrylmethyloxyphenyl)) sulfone (M3) were synthesized and then drop-coated on the SAWs sensing areas. Gravimetric results indicate that the limit of detection of the three sensors is in the picomolar range and that the M3/SAW sensor has the highest affinity towards lead ions compared to M1/SAW and M2/SAW. Density functional theory (DFT) calculations were investigated to support experimental results and to understand the nature of interactions involved between lead ions and the three synthetized molecules.

International audience; The surface of gold can be modified with alkyl groups through a radical crossover reaction involving alkyliodides or bromides in the presence of a sterically hindered diazonium salt. In this paper, we characterize the Au−C(alkyl) bond by surface-enhanced Raman spectroscopy (SERS); the corresponding peak appears at 387 cm −1 close to the value obtained by theoretical modeling. The Au−C(alkyl) bond energy is also calculated, it reaches −36.9 kcal mol −1 similar to that of an Au−S−alkyl bond but also of an Au−C(aryl) bond. In agreement with the similar energies of Au− C(alkyl) and Au−S−(alkyl), we demonstrate experimentally that these groups can be exchanged on the surface of gold.