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International audience; Chalcogen bonding results from non-covalent interactions occurring between electrodeficient chalcogen atoms and Lewis bases. Among the chalcogens, tellurium is the strongest Lewis acid, but Te-based compounds are scarcely used as organocatalysts. For the first time, telluronium cations demonstrated impressive catalytic properties at low loadings in three benchmark reactions: the Friedel–Crafts bromination of anisole, the bromolactonization of ω-unsaturated carboxylic acids and the aza-Diels–Alder between Danishefsky's diene and imines. The ability of telluronium cations to interact with a Lewis base through chalcogen bonding was demonstrated on the basis of multi-nuclear (17O, 31P, and 125Te) NMR analysis and DFT calculations.

International audience; The ability of alkylseleno/alkyltelluroacetylenes such as bis(selenomethylethynyl)-perfluorobenzene (4F-Se) to act as a ditopic chalcogen bond (ChB) donor in co-crystals with ditopic Lewis bases such as 4,4 '-bipyridine is extended here to the octafluorobiphenylene analog, 4,4 '-bis(selenomethylethynyl)-perfluorobiphenyl (8F-Se), with the more electron-rich 4,4 '-bipyridylethane (bpe), showing in the 1:1 (8F-Se)center dot(bpe) co-crystal a shorter and more linear C-Se center dot center dot center dot N ChB interaction than in (4F-Se)center dot(bpe), with Se center dot center dot center dot N distances down to 2.958(2) angstrom at 150 K, i.e., a reduction ratio of 0.85 vs. the van der Waals contact distance.

International audience; Introduction of methyl substituents on the achiral 1,2-bis(selenocyanatomethyl)benzene leads to a novel chelating ChB donor, namely 1,2-bis(1-selenocyanatoethyl)benzene (1), as a mixture of three diastereomers, the two anti enantiomers and the syn (meso) form. Structure determinations show the recurrent formation of short Se center dot center dot center dot N equivalent to C ChB interactions in both the anti (racemic mixture) and syn isomers. Co-crystallization of anti-1 with 4,4 '-bipyridine affords a 2 : 1 adduct, (anti-1)(2)(bipy), with one very short SeMIDLINE HORIZONTAL ELLIPSISNPy ChB (RR = 0.87). Co-crystallization of anti-1 with tetraphenylphosphonium halides (Cl-, Br-, I-) provides 1 : 1 adducts while a 2 : 1 adduct is isolated between syn-1 and Et4NCl, formulated as Et4N+[(syn-1)(2)Cl-]. Comparison of chloride chelation with anti-1 and syn-1 shows much shorter (NC)Se center dot center dot center dot Cl- ChB interactions with the syn isomer, tentatively rationalized on the basis of theoretical calculations of (i) the electrostatic surface potential of neutral ChB donors and (ii) the chloride BSSE complexation energy.

International audience

International audience; Molecular assembly and reactivity have been investigated with a series of 3H-1,2-benzodithiol-3-(thi)one derivatives and their (mixed) selenated analogs. Electrostatic potential calculations on monomers show three σ-hole regions around the dichalcogenide Ch-Ch bond (Ch = S, Se), one side-on and two along the bonding direction. The topological analysis of the electron density ρ(r) points to the weak nature of the Ch-Ch bond. σ-Hole and lone-pair regions are described in terms of charge depletion (CD) and charge concentration (CC) sites found in the valence shell of chalcogen atoms. Whereas CD and CC sites are characterized by the topological critical points of L(r) = -2ρ(r), their electrophilic and nucleophilic powers are measured by the corresponding L/ρ magnitudes. In crystal structures, each chalcogen bond (ChB) involves a σ-hole region and shows a CD⋯CC interaction that aligns with the internuclear direction of the atoms the CD and CC sites belong. The alignment holds simultaneously for all of the ChB interactions in each crystal structure, indicating that CD⋯CC interactions drive molecular orientation in molecular assembly. Strength of ChB is measured in terms of the topological properties of ρ(r), whereas the intensity of the electrophilic⋯nucleophilic interaction is monitored by [(L/ρ)CC - (L/ρ)CD]/dCC⋯CD2. The σ-hole in side-on conformation forms the strongest ChB interactions in molecular assembly. Reactivity of molecules against nucleophilic attack has been investigated along each of the three σ-hole regions by using fluoride as a probe. Adducts formed along the Ch-Ch bonding direction are energetically more favorable than in side-on conformation. At optimized geometries, the F⋯Ch bond (Ch = S, Se) exhibits a partial covalent character, while it weakens concomitantly the Ch⋯Ch bond that also becomes of partial covalent character. In the reactivity process, the significant reorientation of the plane containing the chalcogen lone pairs, along with the opening, shrinking, and splitting of reactivity surfaces 2ρ(r) = 0, is the signature of the charge redistribution that involves the nucleophilic attack. © 2020 American Chemical Society.

The main objective of this study was to improve some properties (physical, mechanical, hydric and thermal) of earth renders amended by cow dung, as such amendment is an ancestral practice in Burkina Faso. For this purpose, raw clayey material from Kodeni (in western Burkina Faso), mainly composed of kaolinite (62 wt.%), quartz (31 wt.%) and goethite (2 wt.%) and having adequate geotechnical properties was used to elaborate earth renders reinforced with up to 6 wt.% of cow dung. The cow dung studied was mainly made up of small vegetable fibres, clayey minerals and quartz consumed by cows. Cow dung incorporation limits the spread of cracks and hardens the material thanks to the good adhesion of cow dung to the clayey matrix, which is linked to the rough surface of fibres contained in cow dung. The presence of cow dung in an earth render influences its mineralogy through the formation of insoluble amine silicate (Si(OH)4. 4NH3). This compound is formed during the reaction between fermented cow dung with mainly fine crushed quartz and feebly kaolinite in basic medium. The molecule formed links isolated raw material particles through free electronic doublets on the oxygen atoms and especially on the nitrogen atoms. The consequence of this effect is an improvement of the microstructural, physical and mechanical properties of earth renders. In particular, their thermal conductivity is reduced as the fibres present in the composite materials are rich in cellulose (molecule with thermally insulating properties), and their resistance to abrasion and to water is good. The earth renders elaborated in this way help to provide water resistant housing with good thermal comfort.

International audience; The insertion of cyclic building blocks in oligoureas to stabilize or modulate the properties of the 12/14-helix was often fruitless. We herein propose a fully compatible highly constrained building block that could be incorporated into oligoureas to develop highly stable and functionnal oligoureas helices.

International audience; This research aims at the seismic assessment and understanding of a traditional loadbearing system incorporating horizontal timber elements into earth brick masonry walls. In order to characterize the global behavior of the loadbearing device, an experimental campaign was performed on the constituents (i.e. bricks and mortar) and on masonry samples. Compression tests were carried out on four geometries of earth brick samples and three geometries of earth mortar samples. As the methods to obtain the compressive strength of earth material are still discussed within the scientific community, a focus was made on different configurations tested. Uniaxial compression tests were performed on two earth brick wallets. Then, two brick walls (with and without horizontal timber reinforcement) were submitted to lateral quasi-static cyclic load. A LVDTs system and a stereo correlation image system were coupled to study the experimental response of the reinforced and unreinforced walls. This investigation led to estimate the lateral strength, the stiffness degradation and the dissipated energy of both reinforced and unreinforced masonry walls. Moreover, it allowed the comparison between the failure modes of the two types of wall. This analysis brings light on the mechanical impact of the horizontal reinforcement.

International audience; The starting premise of this article is that it is not environmentally consistent to stabilize earth by using more than 4% of mineral binder (cement or lime). Thus, this paper presents a study of the effects of low mineral binder contents (2 and 4%) on the properties of earth bricks. The results obtained on two different soils show that the effects are not observable for dry compressive strengths or for dry thermal conductivities but the addition of small amounts of mineral binders significantly modifies the resistance to water and the Moisture Buffer Value.

Background The current increase in public awareness of environmental risks is giving rise to a growth of interest in the microbiological safety of buildings. In particular, microbial proliferation on construction materials can be responsible for the degradation of indoor air quality that can increase health-risk to occupants. Raw earth materials are still widely used throughout the world and, in some cases, are linked to heritage habitats, as in the southwest of France. Moreover, these building materials are currently the subject of renewed interest for ecological and economic reasons. However, the microbial status of earthen materials raises major concerns: could the microbiome associated with such natural materials cause disease in building occupants? Very few analyses have been performed on the microbial communities present on these supports. Characterizing the raw earth material microbiome is also important for a better evaluation and understanding of the susceptibility of such materials to microbial development. This study presents the distribution of in situ bacterial and fungal communities on different raw earth materials used in construction. Various buildings were sampled in France and the microbial communities present were characterized by amplicon high-throughput sequencing (bacterial 16S rRNA gene and fungal ITS1 region). Bacterial culture isolates were identified at the species level by MALDI-TOF mass spectrometry. Results The major fungal and bacterial genera identified were mainly associated with conventional outdoor and indoor environmental communities, and no specific harmful bacterial species were detected on earthen materials. However, contrary to expectations, few human-associated genera were detected in dwellings. We found lower microbial alpha-diversity in earthen material than is usually found in soil, suggesting a loss of diversity during the use of these materials in buildings. Interestingly enough, the main features influencing microbial communities were building history and room use, rather than material composition. Conclusions These results constitute a first in-depth analysis of microbial communities present on earthen materials in situ and may be considered as a first referential to investigate microbial communities on such materials according to environmental conditions and their potential health impact. The bacterial and fungal flora detected were similar to those found in conventional habitats and are thought to be mainly impacted by specific events in the building’s life, such as water damage.

International audience; The halogen bond (XB) is a noncovalent interaction involving a halogen acting as electrophile and a Lewis base. In the last decades XB has found practical application in several fields. Nevertheless, despite the pivotal role of noncovalent interactions in separation science, investigations of XB in this field are still in their infancy, and so far a limited number of studies focusing on solid phase extraction, liquid-liquid microextraction, liquid-phase chromatography, and gas chromatography separation have been published. In addition, in the last few years, our groups have been systematically studying the potentiality of XB for HPLC enantioseparations. On this basis, in the present paper up-to-date results emerging from focused experiments and theoretical analyses performed by our laboratories are integrated with a descriptive presentation of XB features and the few studies published until now in separation science. Then, the aim of this article is to provide a comprehensive and critical discussion of the topic, and account for some still open issues in the application of XB to separate chemical mixtures.

International audience; Bio-aggregate based building materials offer promising perspectives thanks to their low environmental impact and interesting hygrothermal behaviour. In this paper, different formulations of bio-aggregate concrete are proposed and analysed. We focus on two types of locally available bio-aggregates, namely maize and sunflower bark chips, and two types of binder matrices, based on respectively metakaolin and lime. The study specifically focuses on the pore structure of the composite material, as this quantity has a decisive impact on the insulating properties (thermal conductivity), the hygric behaviour (sorption isotherms, water vapour permeability and moisture buffer value) as well as on the mechanical performance (compressive strength). The results underline the impact of the constituents' porosity on the complex porous structure of the bio-concrete and the influence of porosity on its performance. The findings demonstrate that metakaolin and sunflower are high-potential raw materials for the design of a bio-aggregate based concrete.

International audience; Polarizability is a key molecular property involved in either macroscopic (i.e., dielectric constant) and microscopic properties (i.e., interaction energies). In rigid molecules, this property only depends on the ability of the electron density (ED) to acquire electrostatic moments in response to applied electric fields. Databases of transferable electron density fragments are a cheap and efficient way to access molecular EDs. This approach is rooted in the relative conservation of the atomic ED between different molecules, termed transferability principle. The present work discusses the application of this transferability principle to the polarizability, an electron density-derived property, partitioned in atomic contributions using the Quantum Theory of Atoms In Molecules topology. The energetic consequences of accounting for in situ deformation (polarization) of database multipolar atoms are investigated in detail by using a high-quality quantum chemical benchmark.

International audience

International audience; Nowadays, for environmental reasons, the demand for bio-based building materials is increasing. The number of studies focusing on earth building bricks with addition of plant aggregates is growing. In this study, barley and lavender straws were considered as bioaggregates in an earth matrix. Their characterization revealed distinct shape, size and porosity. Composites including 3% and 6% by mass of each bioaggregates were then elaborated. Their performances were investigated and compared in terms of mechanical and thermal properties, durability of the composite materials and resistance to fungal growth. The mixture with 3% of lavender straw showed satisfactory durability results while barley straw brought better thermal properties.

International audience; This study deals with the influence of fonio straw on the physical, thermal and mechanical properties of adobes. The raw materials (soil and fonio straw from Burkina Faso) were characterized from the chemical (ICP-AES), mineralogical (XRD, DSC-TGA, IR), geotechnical (particle size distribution, Atterberg limits, methylene blue value) and microstructural (SEM-EDS) points of view. The physical (thermal conductivity, capillarity water absorption, porosity, erodibility) and mechanical (compressive and flexural strength) properties of the adobes were studied with specific attention paid to their damage and fracture behavior. Because of the biochemical composition of fonio straw (presence of quasi-crystalline cellulose and hemicelluloses, which are hydrophilic compounds), its association with the clay matrix increased water absorption and was accompanied by a significant porosity due to the air trapped during mixing. The insulating character of the cellulose and the low density resulting from the high porosity contributed to an appreciable reduction of the thermal conductivity of these adobes. The use of small amounts of fonio straw improved the mechanical properties of the adobes and made them less brittle. This improvement was linked to the good adhesion between fonio straw and the clay matrix, greatly reduced propagation of fissures in the composites and the high tensile strength of fonio straw because of its cellulose content. Thus, fonio-straw-reinforced adobes have interesting properties for use as cheap construction materials in the Sahelian zones and could contribute significantly to the thermal comfort of the inhabitants in this hot climate.

12/10-Helices constitute suitable templates that can be used to design original structures. Nevertheless, they often suffer from a weak stability in polar solvents because they exhibit a mixed hydrogen-bond network resulting in a small macrodipole. In this work, stable and functionalizable 12/10-helices were developed by alternating a highly constrained β2, 3, 3 -trisubstituted bicyclic amino acid (S)-1-aminobicyclo[2.2.2]octane-2-carboxylic acid ((S)-ABOC) and an acyclic substituted β-homologated proteinogenic amino acid (l-β3 -hAA). Based on NMR spectroscopic analysis, it was shown that such mixed β-peptides display well-defined right-handed 12/10-helices in polar, apolar, and chaotropic solvents; that are, CD3 OH, CDCl3 , and [D6 ]DMSO, respectively. The stability of the hydrogen bonds forming the C10 and C12 pseudocycles as well as the benefit provided by the use of the constrained bicyclic ABOC versus typical acyclic β-amino acids sequences when designing 12/10-helix were investigated using NH/ND NMR exchange experiments and DFT calculations in various solvents. These studies showed that the β3 -hAA/(S)-ABOC helix displayed a more stable hydrogen-bond network through specific stabilization of the C10 pseudocycles involving the bridgehead NH of the ABOC bicyclic scaffold.

A chalcogen bond (ChB) is a sigma-hole-based noncovalent interaction between a Lewis base and an electrophilic element of Group VI (O, S, Se, Te), which behaves as a Lewis acid. Recently, we demonstrated that halogen bond, the more familiar ?-hole-based interaction, is able to promote the enantioseparation of chiral compounds in HPLC environment. On this basis, an investigation to detect ChBs, functioning as stereoselective secondary interactions for HPLC enantioseparations, was started off and the results of this study are described herein. Our investigation also focused on the impact of the perfluorinated aromatic ring as a -hole donor recognition site. For these purposes, seven atropisomeric fluorinated 3-arylthio-4,4'-bipyridines were designed, synthesized and used as potential ChB donors (ChBDs) with two cellulose-based chiral stationary phases (CSPs) containing carbonyl groups as ChB acceptors (ChBAs). In addition, one and two analogues lacking fluorine and sulphur, respectively, were prepared as terms of comparison. The design of the test analytes was computationally guided. In this regard, electrostatic potentials (EPs) associated with sigma and -holes were computed and the atomic contributions to the sulphur EP maxima were derived using a molecular space partitioning in terms of Bader's atomic basins. This procedure is akin to the Bader-Gatti electron density source function (SF) decomposition, yet suitably extended to the EP field. For five 3-substituted-4,4'-bipyridines, thermodynamic parameters were derived from van't Hoff plots. Finally, the use of molecular dynamic (MD) simulation to model ChB in cellulose-analyte complexes was explored. Evidences that sigma and -hole interactions can jointly drive HPLC enantioseparations through recognition sites generated by electronic charge depletion emerged from both experimental results and theoretical data.

International audience; 12 Expanding the use of low-environmental impact materials in the field of building materials is a 13 major aim in a context of sustainable development. These alternative materials should be 14 non-polluting, eventually recycled, and locally available. Bioresources are already used in 15 some building materials but few studies have investigated their relevance in such 16 applications. The aim of this paper is to evaluate the suitability of three kinds of vegetal 17 aggregates: barley straw, hemp shiv and corn cob. The availability of these bioresources, 18 extracted from a French database, is discussed, as are their physical properties and 19 chemical compositions. Their microstructure is described with SEM images and their particle 20 size distributions are provided through image analysis. Sorption-desorption isotherms are 21 measured by a Dynamic Vapour Sorption system. Bulk density, thermal conductivity and 22 water absorption are also quantified. The results highlight a tubular structure for the three 23 different aggregates, with low bulk density and thermal conductivity (0.044, 0.051 and 0.096 24 W.m-1 .K-1 respectively for straw, hemp shiv and corn cob) and high water absorption, 25 especially for barley straw and hemp shiv (414 and 380% vs. 123% for corn cob). Their 26 hygric regulation capacity is also sufficiently good, with a water sorption of between 20 and 27 26% at 95% of relative humidity. These plant aggregates could therefore be used as 28 additions in an earth matrix, or a hydraulic, pozzolanic, air lime or gypsum binder, or just as 29 loose-fill insulation material. However, future research should focus on their resistance to fire 30 and bacterial growth to validate this approach. 31 32

International audience

WOS:000418212400009; International audience; The main objectives of this work were to manufacture adobes with good mechanical properties, even in a wet environment, and low thermal conductivity so as to give the population homes that provided better thermal comfort than cement-based constructions. For this purpose, clayey raw material from Burkina Faso, mainly composed of quartz (49 wt%), kaolinite (28 wt%), goethite (7 wt%) and muscovite (9 wt%) was mixed with up to 12 wt% of cement to manufacture adobes. Various characterization techniques were implemented to assess the microstructure of these materials: X-ray diffraction, infrared spectrometry, differential scanning calorimetry, scanning electron microscopy and energy dispersive spectrometry. Their physical properties were also investigated (through water absorption, spray test, apparent density, porosity and thermal conductivity) as their mechanical characteristics (compressive and flexural strengths). It was found that the addition of cement resulted in the formation of calcium silicate hydrate (CSH) (I), ettringite and calcite. The CSH was formed partly through the hydration of anhydrous cement compounds (alite and belite) and also through pozzolanic reactions strongly involving finely crushed quartz and, to a lesser extent, kaolinite. These cement-stabilized adobes were particularly distinguished by good mechanical resistance even in a wet environment, and low thermal conductivity. These results indicate that adobes stabilized with 2 wt% of cement are suitable for use as building materials for mass housing. (C) 2017 Elsevier Ltd. All rights reserved.

International audience; The effect of molds present in buildings on the health of the occupants is a major issue hence, when a building material is developed, its sensitivity to microbial growth should be assessed. However, few studies have investigated fungal growth on bio-based building materials with the resources available in a laboratory specializing in materials. The objective of this paper is thus to propose a simple and efficient experimental method useful for construction materials laboratories, adapted from methods proposed in the literature. For this purpose, fungal growth was investigated under different environmental conditions on earth-based material with or without the addition of straw or hemp shiv. Samples were inoculated with a strain of Aspergillus brasiliensis and were incubated for 12 weeks at 76, 84 or 93% RH, and 30 °C or 20 °C. Reproducible results showed that earth-based materials were more sensitive to fungi when they were enriched in plant aggregates. Fungal development was observed on earth material containing plant aggregates after 4 weeks of exposure at 93% RH and 30 °C, whereas it was observed after 8 weeks on raw earth material under the same conditions. Additionally, the possibility of quantifying fungal development with increased sensitivity by using image analysis is proposed. Due to the growth of fungal species other than A. brasiliensis, a natural inoculation approach is recommended. One of the conclusions is that liquid water is more favorable to mold growth than relative humidity alone. The addition of liquid water is thus recommended to accelerate the test.

WOS:000416767900015; International audience; A building material is mainly characterized by its mechanical performance, which provides proof of its quality. However, the measurement of the compressive or flexural strength of an earth-based material with plant aggregates, which is very ductile, is not fully standardized. The objective of this study is to determine the compressive and flexural strengths of a composite made of earth and 0, 3, or 6% of barley straw, hemp shiv, or corn cob. Given the manufacturing processes available, cylindrical compressed specimens were studied in compression, whereas extruded specimens were studied in flexion. Two protocols were tested for compressive strength measurements: one with direct contact between the specimen and the press and the other with reduced friction. The test with reduced friction engendered a huge decrease of the stress and a slight decrease of the strain. For both compressive and flexural strengths, the specimens made of earth alone were the most resistant, followed by composites containing straw. The influence of two different treatments applied to the straw is also discussed. (C) 2017 American Society of Civil Engineers.

International audience; 9 For Heat, Air and Moisture modelling, one of the most crucial hygrothermal properties of porous 10 construction materials is the sorption isotherm. Current techniques for measuring the sorption 11 isotherm rely on the standardized Saturated Salt Solution (SSS) method which is known to be time 12 consuming. Recently, a device called Dynamic Vapor Sorption was applied on building materials 13 allowing faster measurements but limiting the mass and volume of the sample. As this technique is 14 not yet standardized, an experimental procedure was developed and validated on barley straw. 15 Results were also in good agreement with the measurements from the SSS technique. 16 17

International audience; A new organic-inorganic hybrid material, 1-amonioethylpiperazine-1, 4-diium tetrachloridozincate(II) chloride, (C6H18N3)[ZnCl4]Cl, has been synthesized and characterized by various physicochemical techniques including UV-visible absorption, Infra-Red (IR), Raman and NMR spectroscopies. The compound crystallizes in the monoclinic system and P21 space group with Z = 2 and the following unit cell dimensions: a = 7.1728 (6), b = 12.4160 (11), c = 8.0278 (7) Å, β = 97.513 (1)°, V = 708.80 (11) Å 3. In this structure, the Zn 2+ ion, surrounded by four chlorides, adopts a distorted tetrahedral coordination geometry. The structure of this compound consists of monomeric 1-amonioethylpiperazine-1, 4-diium trications and monomeric [ZnCl4] 2-and Cl-anions. These entities are interconnected by means of hydrogen bonding contacts [N-H…Cl, C-H…Cl], forming a three-dimensional network. Intermolecular interactions were investigated by Hirshfeld surfaces. More than three quarters of the interaction surface in the crystal packing is constituted by attractive and favored H...Cl hydrogen bonds. The 13C and 15N CP–MAS NMR spectra are discussed and the vibrational absorption bands were identified by infrared and Raman spectroscopy

The synthesis of enantiopure 1,2-diaminobicyclo[2.2.2]octane (DABO, 1) and its two selectively N-Boc monoprotected derivatives 15 and 16 is described. Starting from bicyclic β-amino acid 3 or 5, strategies involving Curtius and Hofmann rearrangements were explored, demonstrating the unprecedented influence of the bicyclic backbone unsaturation for the preparation of the corresponding diamines that could be only obtained in good yield using the Hofmann rearrangement of unsaturated compound 3. The divergent outcome observed during the Hofmann rearrangement of 3 and 5 was investigated by DFT calculations.

We compare here the halogen bond characteristics of bimolecular adducts involving eitherN-bromo- orN-iodosaccharin as strong halogen bond donors, with 4-picoline as a common XB acceptor. In the NBSac·Pic system, the bromine atom of NBSac is displaced toward the picoline, almost at a median position between the two nitrogen atoms, NSacand N′Pic, with NSac⋯Br and Br⋯N′Picdistances at 2.073(6) and 2.098(6) Å respectively. This extreme situation contrasts with the analogous iodine derivative, NISac·Pic, where the NSac–I and I⋯N′Picdistances amount to 2.223(4) and 2.301(4) Å respectively. Periodic DFT calculations, and molecular calculations of adducts (PBEPBE-D2 aug-cc-pVTZ) either at the experimental frozen geometry or with optimization of the halogen position, indicate a more important degree of covalency (i.e.shared-shell character) in the adduct formed with the bromine atom. A stronger charge transfer to the picoline is also found for the bromine (+0.27 |e|) than for the iodine (+0.18 |e|) system. This inversion of halogen bond strength between I and Br finds its origin in the strong covalent character of the interaction in these adducts, in line with the strength of covalent N–Br and N–I bonds. Detailed characterization of the critical points (CPs) of theL(r) = −∇2ρ(r) function along bonding directions has permitted the adducts to be distinguished and they can be respectively described as “neutral” NISac/Pic and “intermediate” NSac/Br/Pic, the latter with Br being close to formal equivalent NSac⋯Br and Br⋯N′Picinteractions but still more associated to the XB donor than to the picoline, as indicated by the topological and energetic properties of theρ(r) function at the bond critical points (BCPs).

International audience; An optically pure hemicryptophane cavitand, in which the primary side of permethylated a-cyclodextrin (alpha-CD) is capped with a C-3-chiral cyclotribenzylene (CTB) derivative, responds to its solution environment, either by electronic circular dichroism or 1HNMR spectroscopy. In particular, the primary methoxy (6'OMe) protons of the alpha-CD component behave as solvent sensitive NMR probes. For example, they are more shielded in C2D2 Cl-4 than in CDCl3, and their chemical shifts show opposite temperature dependence. A similar contrasted behavior was observed in benzene vs. toluene, suggesting that the observed effects are related to the size of the solvent molecule. Molecular Dynamics simulations indicated that C2H2Cl4 and CHCl3 were included in the alpha-CD component of the hemicryptophane, but not in the CTB concavity, with binding energies of - 21.1 kJ x mol(-1) and - 32.7 kJ x mol(-1), respectively.

The preparation of 27 isomers of chiral hexahalogeno-4,4'-bipyridines by means of two complementary methods is described. The first one is convergent and based on the LDA-induced 4,4'-dimerization of trihalopyridines, whereas the second method is divergent and achieved through regioselective halogenation reactions of 4,4'-bipyridine-2,2'-diones. Iodine in 2,2'-positions of the 4,4'-bipyridines was introduced by a copper-catalyzed Finkelstein reaction (Buchwald procedure) performed on 2,2'-dibromo derivatives. Selected compounds of this new family of atropisomeric 4,4'-bipyridines were enantioseparated by High Performance Liquid Chromatography (HPLC) on chiral stationary phases and the absolute configurations of the separated enantiomers were assigned by using X-ray diffraction (XRD) analysis. The latter revealed that various halogen bond types are responsible for crystal cohesion.

International audience; Earth as a building material is increasingly being studied for its low environmental impact and its availability. Plant aggregates and fibers have been incorporated into the earth matrix in the aim of enhancing performance for thousands of years but scientific studies began quite recently. The present paper reviews the state of the art of research on the influence of these various natural and renewable resources in unfired earth materials such as compressed earth blocks, plasters, and extruded and stabilized blocks. This review, based on 50 major studies, includes characterization of the particles and treatments, and recapitulative tables of the material compositions, and the physical, mechanical, hygrothermal and durability performances of earth-based materials. A lack of references on hygroscopic and durability properties was observed. Future research orientations are thus suggested to promote and develop this type of sustainable material, which provides a solution for saving energy and natural resources. Highlights  Earth-based products with plant aggregates as a sustainable material are reviewed.  Physicochemical and mechanical properties of plant aggregates or fibers are reviewed.  Mechanical, hygrothermal and durability performances of the composites are reviewed.  Further investigations are needed to promote these materials.

WOS:000374328800006; International audience; There is an increasing demand for earth construction in the world today but there is no consensus on the procedure to be used to measure the compressive strength of earth bricks. The study presented in this paper aims to propose a test procedure specific to earth bricks that would give the most realistic value of compressive strength while remaining as simple as possible. This study focused on four different bricks and consisted of measuring the compressive strength of these specimens by varying several parameters: specimen size, orientation, use of Teflon capping or not, and tests on dry sawn specimens, on half-bricks or on entire bricks. The results of the study show that the best compromise to achieve a simple and representative compressive strength test for earth bricks is to transform the bricks as little as possible before the test and thus to test entire bricks.

Alkanolamines have been known for their high CO2absorption for over 60 years and are used widely in the natural gas industry for reversible CO2capture. In an attempt to crystallize a salt of (RS)-2-(3-benzoylphenyl)propionic acid with 2-amino-2-methylpropan-1-ol, we obtained instead a polymorph (denoted polymorph II) of bis(1-hydroxy-2-methylpropan-2-aminium) carbonate, 2C4H12NO+·CO32−, (I), suggesting that the amine group of the former compound captured CO2from the atmosphere forming the aminium carbonate salt. This new polymorph was characterized by single-crystal X-ray diffraction analysis at low temperature (100 K). The salt crystallizes in the monoclinic system (space groupC2/c,Z= 4), while a previously reported form of the same salt (denoted polymorph I) crystallizes in the triclinic system (space groupP\overline{1},Z= 2) [Barzagliet al.(2012).ChemSusChem,5, 1724–1731]. The asymmetric unit of polymorph II contains one 1-hydroxy-2-methylpropan-2-aminium cation and half a carbonate anion, located on a twofold axis, while the asymmetric unit of polymorph I contains two cations and one anion. These polymorphs exhibit similar structural features in their three-dimensional packing. Indeed, similar layers of an alternating cation–anion–cation neutral structure are observed in their molecular arrangements. Within each layer, carbonate anions and 1-hydroxy-2-methylpropan-2-aminium cations form planes bound to each other through N—H...O and O—H...O hydrogen bonds. In both polymorphs, the layers are linked to each otherviavan der Waals interactions and C—H...O contacts. In polymorph II, a highly directional C—H...O contact (C—H...O = 156°) shows as a hydrogen-bonding interaction. Periodic theoretical density functional theory (DFT) calculations indicate that both polymorphs present very similar stabilities.

International audience; A series of N-pyrrolidine-based alpha,beta-peptide catalysts incorporating a constrained 2-aminobicyclo[2.2.2] octane carboxylic acid (ABOC) residue were synthesized and evaluated in the asymmetric aldol reaction from acetone and some p-substituted benzaldehydes. Their catalytic properties were shown to be highly dependent on the amino acid sequences and on the absolute configuration of the ABOC residue that played a determinant role. Among the peptides tested, the heterochiral tripeptide H-Pro-(R)-ABOC-Asp-OCH3 13, that adopts a turn conformation in the solid state, proved to be the most efficient catalyst affording beta-hydroxy ketones in high yields and good enantioselectivities (up to 87%).

The development of innovative materials has to respond to both environmental and energy concerns. Bio-based materials are relevant because they are made from renewable raw materials and are carbon neutral. Similarly, unprocessed earth has a very low embodied energy. In this paper, the basic hygrothermal properties of straw-clay samples provided by two French companies were determined. Mixes with densities lower than 450 kg m−3 would be suitable for use as self-insulating material in current construction. In addition, the material showed a high sorption capacity and very high water vapour permeability. The measurements were then implemented in a numerical model in order to simulate the hygric response of a small room. The straw-clay mixture was found to have a moisture buffering effect of the same magnitude as walls made of hemp concrete and largely higher than conventional walls. The influence of various indoor finishing materials was investigated through additional simulations.

International audience; Two new polymorphs of Schiff base, (E)-2-((2,6-dichlorobenzylidene)amino)benzonitrile, were prepared from the condensation of 4-amino-benzonitrile and 2,6-dichlorobenzaldehyde. The two polymorphs crystallize in two different space groups: P21/c for polymorph (I) with volume 1264.23(2) angstrom(3) and Pbca for polymorph (II) with volume 2469.3(2) angstrom(3). The two polymorphs have been characterized by FT-IR and UV-VIS spectroscopy. The crystal structures of both compounds were determined by single X-ray analysis. The difference between the two polymorphs was observed at the angle between the two phenyl rings which is 4.81 degrees for the first one and 82.27 degrees for the second one. Both crystal structures are built on the basis of moderate and weak hydrogen bonds. Theoretical calculations on isolated molecules at the MP2 cc-pVDZ level show that the two polymorphs correspond to two molecular conformations that are within less than 1 kJ mol(-1) and DFT periodic calculations indicate that (II) is more stable than (I) by 4.1 kJ mol(-1) of formula unit. Additionally, we performed TD-DFT calculation for free ligands to support the experimental data.

WOS:000369190800006; International audience; The use of bio-based materials in the construction field is of great interest to society and the scientific community because of its highly sustainable character. They are formed by plant fibres and a binder, usually cement, lime or pozzolanic additives. Among the new vegetable fibres used, hemp-based biomaterials have attracted great attention in the recent years due to its excellent thermal and hygroscopic properties. However, they present a very low mechanical performance, which has intensified the search for better alternatives. In this research, the use of magnesium phosphate cement (MPC) as binder with different hemp additions (8%, 12%, 16% and 20% by weight) was evaluated. Thus, a new material made of hemp and MPC (heMPC) was developed. According to the results obtained, the heMPC could be used in floor or pre-cast structural applications since it presented enhanced mechanical (sigma(max) = 0.714 +/- 0.11 MPa with a 20 wt.% of hemp content) and thermal (lambda(D) = 0.103 W . m(-1) . K-1, density = 600 kg . m(-3)) properties with respect other lime-based hemp biomaterials. Furthermore, the material exhibited good hygroscopic properties (water absorption by capillarity). Accordingly, this preliminary study allowed opening a new research line in the use of hemp bio-composites, in which other important properties are currently under investigation. The MPC used as a binder in this study was formulated with a by-product from the MgO industry, which increases the sustainability and recyclability criteria of the material developed. (C) 2015 Elsevier Ltd. All rights reserved.

International audience; A new Cu (II) complex with bidentate o-phenanthroline (phen) ligand, ([Cu(phen)](2)(H2PO4)(2)HPO4)(2)(H3PO4)(4), has been synthesized and characterized by single crystal X-ray diffraction, IR spectroscopy and magnetic data. The crystal structural analysis shows that the title compound contains two phosphate-bridged dimeric units ([Cu(phen)](2)(H2PO4)HPO4), which are crystallographically independent. In these units, each copper atom is five coordinated and the geometry around the Cu(II) can be described as slightly distorted square-based pyramidal, with tau parameter varying between 0.001 and 0.04. The crystal structure is stabilized by O-HaEuro broken vertical bar O and C-HaEuro broken vertical bar O hydrogen bonds between the dimeric units and the phosphoric acid molecules. In addition, the organic ligands are associated by pi-pi stacking interactions between neighboring non-nitrogen aromatic rings. The infrared spectrum recorded at room temperature was interpreted on the basis of data published in the literature. The magnetic susceptibilities data show a weak intra-dimer ferromagnetic interaction with J = 31.8 K.

International audience; This study deals with the reuse of an industrial waste rich in CaCO 3 as a mineral addition and agent 9 of stability in low-strength filling grout for soil reinforcement applications. The physical, chemical 10 and mineralogical characteristics of these Carbonated Residual Brines (CRB) were determined and 11 completed by a study of CRB behaviour in cement-based materials and of the optimization of a 12 composition of low-strength filling grouts rich in CRB filling. The results showed that it was 13 possible to use CRB in low-strength filling grout, in replacement of bentonite and fine sand, with 14 better performance-especially in terms of stability. 15 16 Highlights 17 CRB is essentially composed of calcium carbonates (91%). 18 CRB can replace both bentonite and fine sand in low-strength filling grouts. 19 CRB strongly improves the stability of grouts. 20 21

International audience; The distinction between cocrystals and salts is usually investigated in hydrogen-bonded systems as A?H···B ? [A]?···[H?B]+, where the position of the hydrogen atom actually defines the ionicity of the complex. The same distinction, but in halogen-bonded systems, is addressed here, in complexes formed out of N-iodoimide derivatives as halogen bond donors, and pyridines as halogen-bond acceptors, anticipating that the position of the iodine atom in these A?I···B ? [A]?···[I?B]+ systems will also define their degree of ionicity. We show that the crystalline halogen-bonded complexes of N-iodosuccinimide (NIS) with pyridine, 4-methylpyridine, and 4-dimethylaminopyridine can be described as ?close-to-neutral? cocrystals while the crystalline halogen-bonded complex of N-iodosaccharin (NISac) with 4-dimethylaminopyridine adopts a ?close-to-ionic? structure. Theoretical calculations were performed (i) in gas phase on isolated NIS···Py-NMe2 and NISac···Py-NMe2 complexes, and (ii) on the periodic crystal phases, and combined with the topological analysis of the electron density distribution ?(r). We demonstrate unambiguously that the crystal environment actually plays a crucial role in the stabilization of the ?close-to-ionic? structure of the NISac···Py-NMe2 complex. An external homogeneous electric field ε applied to this complex (all atoms frozen at the crystalline geometry, except iodine) in either gas phase (ε = 3.7 GV m?1) or periodic pseudo-isolated configuration (ε = 2.8 GV m?1) is able to shift the iodine atom at the crystal geometry, miming the polarization effect induced by the local crystal electric field. The strong influence of the crystalline environment on the iodine position is demonstrated by using plane wave DFT periodic calculations on optimized NIS·Py-NMe2 and NISac·Py-NMe2 crystal structures, as well as by applying this plane wave basis set formalism to a hypothetical solid where the halogen-bonded complexes are pushed apart from each other within a periodic system

WOS:000354543400005; International audience; Near the Pyrenees in France, there is a village called Castelnau-Magnoac where a very specific earthen construction technique exists. It consists of alternating adobe bricks and pebbles in staggered rows, resulting in an effect that gives the name of "chequered construction" to this special technique. Between two and three hundred houses and farmhouses built using this technique exist on an area close to a thousand square kilometres. The date of the construction of these buildings is estimated as the middle of the nineteenth century. In 2011, the municipality of Castelnau-Magnoac, owner of a chequered earth farmhouse, initiated the rehabilitation of this building so that it could house a physiotherapy practice. This was the opportunity for a group of researchers to study the specificities of the building from the point of view of both the construction methods and the characteristics of the materials used. The main results of this study are reported in this paper. The main construction specificities of this building are: the systematic alignment of vertical joints made without mortar, the lack of a ring beam combined with a high slenderness ratio, and a lack of protection against the rain. The special characteristics of the adobes used in this building are a very significant fineness combined with an exceptionally low limit of liquidity. These characteristics are outside the limits recommended by the French standard on earth bricks, yet the compressive strength of these adobe bricks is comparable to those of traditional adobe bricks reported in the literature and they have proved their efficiency over many decades, which calls the relevance of modern standards on earth bricks into question. It seems that the behaviour of these adobes is related to their mineralogical composition, which shows that the use of particle size distribution as the sole criterion of acceptability of a type of earth for the manufacture of adobe is not relevant. Although the study of this building was very instructive, many questions (technical, historical and societal) still remain and would merit further investigations on this type of buildings. The answers could be useful for modern reflection on the changes in choices that will be necessary to take account of environmental and social impacts in building practice. (C) 2014 Elsevier Masson SAS. All rights reserved.

International audience; With the aim to design fluorescent solids, a series of indeno[10,20: 4,5] pyrido[2,1-a] isoindol-5-ones with various substituents was prepared. In these pi-extended pentacyclic derivatives, the presence of a methyl group in the 7-position was found to have a critical influence on the fluorescence properties in the solid state. Crystal packing of the non-substituted derivatives shows strong p-p interactions causing quenching of the fluorescence. In contrast, by introducing a methyl substituent in the 7-position we obtained compounds with fluorescence quantum yield up to 32% in the solid state.

WOS:000372185700008; International audience; The impacts of buildings on the environment and on the health of the inhabitants are priority issues nowadays. For many environmental, social and economic reasons, the demand for building products made of materials such as earth and bio-based materials is increasing. Under certain conditions, mold growth can be observed on the surface of such materials, which raises many questions about their use in buildings. In the framework of the "BIOTERRA" ANR project, the aim of the study was to develop and characterize an earth based material incorporating plant fibers from both abiotic and biotic points of view. Compressive strength, thermal conductivity and water vapor permeability of this material were determined. Microorganism sampling methods intended for raw materials and cylindrical specimens were optimized, and the microflora profile of these materials was then obtained. The results showed that the straw addition led to a decrease of compressive strength and an increase of thermal insulation. However, it did not influence water vapor permeability coefficient. Raw materials and manufactured specimens contained mainly Bacillus sp., Aspergillus sp. and Penicillium sp. Other compositions of this bio-based material will be characterized. Sampling methods developing here can also be used to identify the microflora of existing earthen buildings.

National audience; Une fouille réalisée à Prades (Pyrénées-Orientales) a mis au jour deux fosses antiques (1er siècle de notre ère) de forme quadrangulaire. Elles sont enduites d’un épais revêtement de terre crue. Des analyses physiques, chimiques et minéralogiques ont permis de déterminer la nature et les proportions des éléments présents dans le limon naturel ainsi que dans les enduits de revêtement des fosses. Ces analyses sont complétées par une recherche de phytolithes qui nous renseigne sur la présence de graminées et de taxons ligneux. La fonction initiale de ces creusements pourrait être la conservation de végétaux, peut-être du fourrage.

International audience; The use of clay plasters with or without plant fibers (straw, hemp or other) inside buildings is currently showing considerable growth in many countries. Despite this development, there are very few data in the literature on the characteristics of clay plasters. This paper deals with the characterization of five ready-mixed clay plasters from French brickworks using the recent German standard. The work essentially consisted in measuring the flow of fresh clay plasters and their characteristics after hardening (shrinkage, and compressive, flexural and adhesive strength). The characterization of the samples showed that the granular characteristics were practically the same and that the main difference concerned the nature of the clayey minerals they contained: four samples were essentially composed of montmorillonite, chlorite and illite whereas one was only composed of kaolinite. Despite this difference, the flow of fresh clay plasters and their characteristics after hardening (shrinkage, compressive and flexural strength) were very similar and were comparable to the values given by the standard. However, the measurement of the adhesive strength led to two significant problems: the dispersion of the values was very high and the results were markedly different from the values given by the standard. For these reasons, it seems necessary to complete and adapt the procedure for measuring adhesive strength and it could be interesting to develop new tests for the measurement of this important characteristic, either in the laboratory or on building sites.

WOS:000337874000007; International audience; The study focuses on the thermal and hydric properties of extruded earth bricks. The thermal conductivity and water vapour permeability tests highlight anisotropic behaviour of the bricks depending on the extrusion direction during the production process. The results confirm that the extrusion process has a major influence on the orientation of clay layers and has an impact on the hygrothermal properties. (C) 2014 Elsevier Ltd. All rights reserved.

International audience; Starting from the high-performance liquid chromatography (HPLC) enantioseparation data collected by using twelve polyhalogenated 2,2'-dichloro-3-substituted-5,5'-dihalo-4,4'-bipyridines as test probes on seven polysaccharide-based chiral stationary phases (CSPs) under multimodal elution, the impact of substitution pattern, shape and electronic properties of the molecules on the separation behaviour was investigated through the evaluation of the chromatographic parameters (k, alpha, R-s) and molecular properties determined by means of quantum chemistry calculations. The computational/chromatographic screening furnished relevant structure-chromatographic behaviour relationships and some molecular interactions involved in the chiral discrimination process could be identified. In particular, a halogen bonding interaction (IO) could reasonably explain the high enantioseparation (alpha = 1.80, R-s = 8.2) observed for the 2,2'-dichloro-3,5'-diiodo-5-bromo-4,4'-bipyridine on Lux Cellulose-1. To the best of our knowledge, this is the first report supporting the involvement of a stereoselective halogen bonding interaction in polysaccharide-based CSPs. Moreover, having at disposal a sufficient set of data, the unknown absolute configurations of the eluted enantiomers of 3-methyl-, 3-thiomethyl- and 3-diphenylphosphinoyl-2,2'-dichloro-5,5'-dibromo-4,4'-bipyridines could be deduced by chromatographic correlation with the enantiomer elution order (EEO) of the related compounds of known absolute configuration.

Carbonation was applied to a Pb- and Zn-contaminated fraction of municipal solid waste incineration electrofilter fly ashes in order to reduce heavy metal leaching. Carbonation tests were performed in solution, by Na2CO3 addition or CO2 bubbling, and were compared with washing (with water only). The injection of CO2 during the washing did not modify the mineralogy, but the addition of Na2CO3 induced the reaction with anhydrite, forming calcite. Microprobe analyses showed that Pb and Zn contamination was rather diffuse and that the various treatments had no effect on Pb and Zn speciation in the residues. The leaching tests indicated that carbonation using Na2CO3 was successful because it gave a residue that could be considered as non-hazardous material. With CO2 bubbling, Pb and Zn leaching was strongly decreased compared with material washed with water alone, but the amount of chromium extracted became higher than the non-hazardous waste limits for landfilling.

The aim of the work presented here was to quantify the mineralogical phases contained in a basic oxygen furnace slag (BOFS), and especially the hydraulic phases, so as to evaluate the reactivity of this material. The chemical and mineralogical characteristics of BOFS were analyzed. This slag was essentially composed of calcium, iron, silicon, and magnesium oxides contained in five main minerals: calcium silicate oxides (β-Ca2SiO4 and Ca3SiO5), a solid solution of calcium aluminum ferrite oxides (Ca2Fe1.52Al0.48O5), a solid solution of magnesium iron oxides (MgO0.432FeO0.568), and free lime CaO. The Rietveld method was used to determine the amount of each mineral phase and led to the following mineralogical composition: β-Ca2SiO4=32%, Ca3SiO5=2%, Ca2Fe1.52Al0.48O5=26%, MgO0.432FeO0.568=22%, and CaO=18%. BOFS thus contained a significant amount of hydraulic phase (dicalcium silicate and free lime), which was confirmed by the study of its reactivity using a hydrated paste.

WOS:000331424400009; International audience; There is an intense on-going search for less polluting materials and technologies, which consume little energy in their production, construction and/or utilization. Attention of the researchers has turned to materials, which found applications in engineering in pre-industrial times: local vegetable fibers and earth composites are one of the promising materials. This paper presents the results of an investigation in establishing the physical and mechanical properties of Hibiscus cannabinus fibers which have been used in the fabrication of Pressed Adobe Blocks (PABs). The PABs have been reinforced with 0.2-0.8 wt.% of 30 mm and 60 mm lengths of H. cannabinus fibers. The microstructural characteristics of the PABs composites were investigated using X-ray diffraction (XRD), thermal gravimetric analyses (TGA), scanning electronic microscopy (SEM) and video microscopy. It was established that the addition with 0.2-0.6 wt.% of 30 mm long fibers reduced the dimensions of the pores in the PABs with the improvement of their mechanical properties. However, the addition of 0.8 wt.% of 60 mm fibers had negative effects on the compressive strength. The elaborated Pressed Adobe Blocks specimens were suitable as building material with contribution for thermal comfort. (C) 2013 Elsevier Ltd. All rights reserved.