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This work presents a single-crystal X-ray diffraction study of an organic co-crystal composed of N-iodosaccharin and pyridine (NISac·py) under hydrostatic pressure ranging from 0.00 (5) GPa to 4.5 (2) GPa. NISac·py crystallizes in the monoclinic system (space group B21/e). The unconventional setting of the space group is adopted (the conventional setting is P21/c, No. 14) to emphasise the strongly pseudo-orthorhombic symmetry of the lattice, with a β angle very close to 90°. The crystal structure contains one molecule each of N-iodosaccharin (NISac) and pyridine (py) in the asymmetric unit (Z′ = 1), linked via an Nsac...I...N′py halogen-bonding motif. A gradual modification of this motif is observed under pressure as a result of changes in the crystalline environment. Mechanical twinning is observed under compression and the sample splits into two domains, spanning an unequal volume that is mapped by a twofold rotation about the [100] direction of the B21/e unit cell. The twinning is particularly significant at high pressure, being reversible when the pressure is released. The structure of the twinned sample reveals the continuity of a substantial substructure across the composition plane. The presence of this common substructure in the two orientations of the twinned individuals can be interpreted as a structural reason for the formation of the twin and is the first observed example in a molecular crystal. These results indicate that the anisotropy of intermolecular interactions in the crystal structure results in an anisotropic strain generated upon the action of hydrostatic compression. Periodic density functional theory calculations were carried out by considering an isotropic external pressure, the results showing good agreement with the experimental findings. The bulk modulus of the crystal was obtained from the equations of state, being 7 (1) GPa for experimental data and 6.8 (5) GPa for theoretical data.

International audience; The ability of amphoteric N-chlorobenzimidazoles to self-associate into 1D chains through strong and linear N-ClMIDLINE HORIZONTAL ELLIPSISN halogen bond interactions is demonstrated. The less polarisable Cl atom is strongly activated thanks to the intramolecular amphoteric character and the intermolecular cooperativity effect. The obtained family of compounds featuring different substitution patterns provides opportunities toward the elaboration of macroscopic polar structures.

International audience; Crystal engineering based on σ -hole interactions is an emerging approach for realization of new materials with higher complexity. Neutral inorganic clusters derived from 1,2-dicarba- closo -dodecaborane, substituted with -SeMe, -TeMe, and -I moieties on both skeletal carbon vertices are experimentally demonstrated here as outstanding chalcogen- and halogen-bond donors. In particular, these new molecules strongly interact with halide anions in the solid-state. The halide ions are coordinated by one or two donor groups ( μ 1 - and μ 2 -coordinations), to stabilize a discrete monomer or dimer motifs to 1D supramolecular zig-zag chains. Crucially, the observed chalcogen bond and halogen bond interactions feature remarkably short distances and strong directionality. Electrostatic potential calculations further demonstrate the efficiency of the carborane derivatives, with V s,max being similar or even superior to that of reference organic halogen bond donors such as iodopentafluorobenzene.

International audience; The global objective of this work was to manufacture resistant and durable (water resistant) earth renders with good thermal insulation. For this purpose, a medium plastic clayey soil from Kôdéni (Burkina Faso), constituted by kaolinite (62 wt.%), quartz (31 wt.%), and goethite (2 wt.%), was mixed with dolomitic lime (up to 6 wt.%) to manufacture earth renders. The mineralogical, microstructural, and chemical characteristics of dolomitic lime, as well as the physical (linear shrinkage, apparent density, and accessible porosity), hydric (water absorption test by capillarity and spray test), thermal (thermal conductivity), and mechanical (abrasion resistance, flexural, and compressive strengths) properties of the earth renders were evaluated. From these studies, it appears that the addition of dolomitic lime induces the formation of calcium silicate (CSH) and magnesium silicate (MSH) hydrates. These CSH and MSH are mainly formed from the pozzolanic reaction between finely ground quartz and the weak silica of kaolinite in basic media. These formed hydrates improve the physical, hydric, thermal, and mechanical properties of earth renders. This improvement is due to the fact that the formed CSH and MSH stick to the isolated particles of the soil, making them more compact. In view of the good mechanical strength and water resistance, as well as the low thermal conductivity, the elaborated earth renders are suitable for habitats with dry climates, such as the Sahel.

The chalcogen bonding (ChB) ability of Te is studied in symmetrical diaryl ditellurides ArTeTeAr. Among the two Te σ-holes, the one along the less polarized Te-Te bond was calculated as the more electropositive. This counter-intuitive situation is due to the hyperconjugation contribution from Te lone pair to the σ* of the adjacent Te which coincides with σ-hole along the more polarized Te-Ar bond. ArTeTeAr showed notable structural features in the solid state as a result of intermolecular Te⋅⋅⋅Te ChB, such as a Te

International audience; The successful topochemical polymerization of bis(selenocyanatomethyl)butadyine 1 is achieved upon association in a 1 : 1 co-crystal with 1,2-bis(2-pyridyl)ethylene (2-bpen) through strong and linear (NC)-Se⋅⋅⋅N(Py) chalcogen bonding (ChB) interactions, allowing for an appropriate parallel alignment of the diacetylene moieties toward the solid-state reaction. Co-crystal 1⋅(2-bpen) undergoes polymerization upon heating at 100 °C. The reaction progress was monitored by IR, DSC and PXRD. An enhancement of the polymer conductivity by 8 orders of magnitude is observed upon iodine doping. Strikingly, the course of polymerization is accompanied with sublimation of the ChB acceptor molecules 2-bpen, providing the polymer in a pure form with full recovery of the co-former, at variance with the usual hydrogen-bonded co-crystal strategies toward polydiacetylenes.

Due to its ecological interest and large availability, a renewed attention is paid to earth as building material. Indeed, raw earth consumes CO2 only during its processing and transportation, and it provides a natural hygrothermal comfort. However, its mechanical properties are highly linked to its composition, which causes an important variability of performances. That is why any soil has to be characterized before being used as a building material. The aim of this study is to propose a model able to predict the hydromechanical behavior of a reconstituted soil according to its composition. As earth is a heterogeneous material, the model is based on homogenization procedures. The sand is considered as spherical inclusions inside a clay matrix. The particularity of the model stands to consider both positive and negative effects of volume variation and mechanical properties of clay under hydric variations. The model parameters are determined according to an original experimental campaign, which is conducted on various mixes of a single type of clay (kaolinite) and of sand, and water. The experimental study provides some mechanical properties of the mixes versus water content and sand content to test the ability of the homogenization model to assess the main properties of this material.

Despite the increasing number of applications based on halogen bond (XB), asymmetric catalysis purely based on such supramolecular interactions still remains a huge challenge. The first step toward its development is the design of appropriate XB chiral donor molecules with good catalytic properties. In this context, we report the synthesis of a series of iodinated compounds based on the triazole or triazolium ring and possessing the planar chirality of ferrocene. Their XB donor property was attested by X-ray diffraction analysis, showing short I-N and I-F interactions in the triazole-based derivatives and in the tetrafluoroborate salt of a idodotriazolium, respectively. The potential of these compounds to act as XB-based catalysts was demonstrated in the aza-Diels-Alder reaction involving an imine and a diene. Whereas triazole-based derivatives were inactive in this reaction, the triflate salts of iodotriazoliums delivered the expected cycloadduct with high yield.

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International audience; This study deals with the reuse of sugarcane bagasse in adobes in order to improve their physicomechanical properties. Mineralogical and geotechnical characterization of the soil used shows that it is composed of quartz, kaolinite and goethite and is suitable for the manufacture of adobes. Sugarcane bagasse has a rough surface and contains mainly cellulose, hemicelluloses, lignin and traces of sucrose. Microstructural studies on adobes reinforced with sugarcane bagasse have shown that their microstructure is homogeneous for additions of these fibres up 4 wt.%. It has been found that the addition of sugarcane bagasse to the clayey matrix strongly improves the mechanical properties and reduces the water absorption kinetics and thermal conductivity (mainly because of the presence of cellulose) of the adobes, linked to their microstructure. The rough surface of sugarcane bagasse and the presence of sucrose acting like glue improve its adhesion with the clayey matrix, and cracks propagation in adobes is reduced. The presence of bagasse fibres leads to the formation of hydrogen bonds between sugarcane molecules and the clayey minerals, which could explain the improvement in the physicomechanical properties. Considering the thermal conductivity results, such adobes could improve the thermal comfort in habitats, especially in arid areas.

The objective of this chapter is to present the physical, geotechnical, chemical and mineralogical characterization techniques used to characterize the raw material (earth and mineral addition, such as sand and gravel) contained in the earth materials manufactured with different techniques: earth bricks, rammed earth or cob. This chapter will be divided into 6 sections. The first will present the method used to find the references considered in this state of the art and we will carry out a general qualitative analysis of these references. The other sections will deal respectively with granular, geotechnical, chemical and mineralogical characteristics and, finally, the last part will be dedicated to field tests.

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International audience; The physicochemical properties of a 33 isomer grid of mono-chlorobenzamides (Clxx) are reported with comprehensive studies of their crystal structures and interaction environments (Clx = para-/meta-/ortho-chlorobenzoyl and x = para-/meta-/ortho-aminopyridine substitutions). The nine compound Clxx series was synthesised from the three p-/m-/o-chlorobenzoyl chlorides and three p-/m-/o-aminopyridine isomers using standard synthetic procedures. Clxx exhibits some similarities to the related Fxx and Brxx congeners e.g. the isomorphous behaviour of Clpp (para-Chloro-N'-(para-pyridyl)benzamide) with several close relatives, and there are five isomorphous pairs of Clxx and Brxx crystal structures. Notably Clmp and Clpm both crystallise with Z'=4 in space group P but show important differences. The overall lack of isomers crystallising with solvate molecules is noteworthy, except for Clmm(H 2 O). In all Clxx crystal structures, strong N-H…N hydrogen bonds form, however, Clpo also crystallises as the unexpected Clpo_O polymorph with N-H…O=C intermolecular hydrogen bonding. The Clxo triad (with ortho-pyridines) exhibits the expected cyclic N-H…N dimer formation with R 2 2 (8) hydrogen bonded rings. The H C atom type, forming weak C-H…Cl hydrogen bonds, is the only favoured interaction partner of chlorine in Clxx. Conformational analyses (gas phase) together with crystal contact enrichment studies place Clxx in context and at the interface of hydrogen and halogen bonding interactions, though strong hydrogen bonding dominates. In Clxx the interaction energies with nearest neighbours are shown to contribute to most of the lattice electrostatic energies. The melting temperatures T m show correlation with both molecular symmetry (Carnelley's rule) and total electrostatic energy of the weak interactions; in addition, these T m values can be well predicted from a linear fit combining both descriptors. In Clxx, N-H…N hydrogen bonds dominate, largely in the absence of solvates, and with five Clxx forming isomorphous pairs with Brxx analogues; Clpp being isomorphous with several close benzamide relatives. Analysis of T m reveals correlations involving both symmetry and electrostatic energies.

The impact of building materials on the environment and the health of occupants is nowadays a priority issue. Ecological construction materials such as earthen materials are currently experiencing a regain of interest due to both ecological and economic factors. The microbial proliferation on indoor materials can induce a deterioration of the building air quality and lead to an increase of health risks for the occupants. The issue of indoor air quality raises questions about the use of earthen building materials and their possible susceptibility to fungal development. The microflora of earthen materials and their ability to grow on such support are indeed poorly studied. This study focused on the quantification of both bacterial and fungal microflora along the manufacturing process. The impact of extreme humidity, simulating a hydric accident, on microflora development was analyzed on the surface and inside earthen bricks. The initial microflora of these materials was dramatically reduced during the manufacturing process, especially after heat treatment for drying. Proliferation of remaining microorganisms was only observed under high humidity condition, in particular for earthen materials with vegetal aggregates. Moreover, in situ samplings were performed on naturally dried earthen materials used in buildings. The characterization of the microbial density revealed a higher microbial density than on manufactured specimens, while microbial concentration and detected taxa seemed mainly related to the room use and building history. These results provide a better understanding of microbial proliferation on these materials.

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; Non-symmetrical chiral 4,4′-bipyridines have recently found interest in organocatalysis and medicinal chemistry. In this regard, the development of efficient methods for their synthesis is highly desirable. Herein, a series of non-symmetrical atropisomeric polyhalogenated 4,4′-bipyridines were prepared and further functionalized by using cross-coupling reactions. The desymmetrization step is based on the N-oxidation of one of the two pyridine rings of the 4,4′-bipyridine skeleton. The main advantage of this methodology is the possible post-functionalization of the pyridine N-oxide, allowing selective introduction of chlorine, bromine or cyano groups in 2- and 2′-postions of the chiral atropisomeric 4,4′-bipyridines. The crystal packing in the solid state of some newly prepared derivatives was analyzed and revealed the importance of halogen bonds in intermolecular interactions

International audience; The reduction of CO2 emissions has become an important parameter in the choice of construction materials. Earth guarantees a low environment impact due to the reduced need of energy for its processing and transportation and also provides natural hygrothermal comfort. To facilitate the design of earthen constructions, the development of models is necessary. This paper aims to provide a database of experimental results that could be easily used for developing models based on the competition between positive effect of capillary pressure on material cohesion and negative effect induced by matrix shrinkage restrained by aggregates. Mechanical and thermal tests were carried out on three reconstituted soils composed of pure kaolinite and three contents of fine sand (0, 30 and 60%), as well as different water content configurations (fabrication water content and after drying at 50% RH). The thermal properties analyzed included thermal conductivity and specific heat capacity. The mechanical properties studied encompassed the tensile (three-point bending test) and compressive strengths, Young's modulus and Poisson's ratio (using video correlation). Moreover, an original test was developed for measuring sample shrinkage during drying. Specifically, the results clearly showed that while shrinkage is divided by 5 for the maximal sand content, tensile strength is reduced by half. Therefore, these results allow to assess the balance between benefices and disadvantages of capillary pressure induced by clay drying on earth construction materials, which is of first interest to assess cracking risk in a structure.

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.

Based on the RILEM Technical Committee 274-TCE work, this paper is a discussion of the remaining engineering challenges faced by earthen architecture. The assessment of earth material performances requires the development of appropriate procedures and standards. This is discussed in particular for the characterisation, hygrothermal behaviour, mechanical behaviour, and durability of earth materials. One other important challenge, since one of the main advantages classically put forward, is its ecological performance, is a proper assessment of life cycle assessment of earth materials, elements and buildings. Moreover, the paper develops why the approach to earthen construction must be different compared to the dominant construction materials, to preserve its ability to contribute to the ecological transition in the construction sector. In particular, the needs of using local soils, with an architectural approach coping with the limits of the materials, and developing an architectural optimisation to preserve the earthen materials multifunctionality rather than selecting a sole property to be maximised. Lastly, the findings of the paper can be used to develop a holistic approach to earthen construction to foster the development of new earthen architecture projects.

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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.

The 3,3&prime, 5,5&prime, tetrachloro-2-iodo-4,4&prime, bipyridine structure is proposed as a novel chemical scaffold for the design of new transthyretin (TTR) fibrillogenesis inhibitors. In the frame of a proof-of-principle exploration, four chiral 3,3&prime, tetrachloro-2-iodo-2&prime, substituted-4,4&prime, bipyridines were rationally designed and prepared from a simple trihalopyridine in three steps, including a Cu-catalysed Finkelstein reaction to introduce iodine atoms on the heteroaromatic scaffold, and a Pd-catalysed coupling reaction to install the 2&prime, substituent. The corresponding racemates, along with other five chiral 4,4&prime, bipyridines containing halogens as substituents, were enantioseparated by high-performance liquid chromatography in order to obtain pure enantiomer pairs. All stereoisomers were tested against the amyloid fibril formation (FF) of wild type (WT)-TTR and two mutant variants, V30M and Y78F, in acid mediated aggregation experiments. Among the 4,4&prime, bipyridine derivatives, interesting inhibition activity was obtained for both enantiomers of the 3,3&prime, tetrachloro-2&prime, (4-hydroxyphenyl)-2-iodo-4,4&prime, bipyridine. In silico docking studies were carried out in order to explore possible binding modes of the 4,4&prime, bipyridine derivatives into the TTR. The gained results point out the importance of the right combination of H-bond sites and the presence of iodine as halogen-bond donor. Both experimental and theoretical evidences pave the way for the utilization of the iodinated 4,4&prime, bipyridine core as template to design new promising inhibitors of TTR amyloidogenesis.

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.

International audience; Earth is a material presenting good hygric properties, which is an important point as comfort and indoor air quality have become major issues. Nowadays, the energy efficiency of a construction is also crucial, but the thermal insulation provided by an earth brick is quite low. Therefore, some plant aggregates were added to lighten the material, thus decreasing its thermal conductivity. The hygrothermal properties of seven formulations made of earth with 0, 3 or 6% by weight content of barley straw, hemp shiv or corn cob were assessed. The properties determined were thermal conductivity, specific heat capacity, water vapour permeability, and sorption-desorption isotherms measured with the saturated salt solution and DVS methods. The theoretical MBV was also calculated. The study showed a large decrease in thermal conductivity when a large volume of plant aggregates was added while plant aggregates incorporation conversely affected the thermal inertia parameters. Concerning water vapour permeability, as earth is a very permeable material, the addition of plant aggregates did not improve this property. The sorption capacity of bio-based earth materials was slightly increased in comparison with earth alone. Finally, the calculated MBV showed the excellent buffering capacity of this kind of material, with and without plant aggregates.

New chiral tetra- and bidentate ligands derived from the (R)-1,2-diaminobicyclo[2.2.2]octane scaffold have been synthesized and the influence of ligand N,N'-substituents on the catalytic activity of their corresponding copper(II) complexes toward nitroaldol reaction have been investigated. Among them, the complex generated in situ by the interaction of the (R)-N,N'-Bis(1-naphthylmethyl)-1,2-diaminobicyclo[2.2.2]octane ligand L10 with Cu(OAc)2 proved to be the most effective for the asymmetric Henry reaction of nitromethane with various aldehydes, providing b-nitroalcohols in moderate to good yields, and enantioselectivity (up to 86%). In an attempt to rationalize the factors that control enantiodifferentiation, the most stable geometries of this C1-symmetric bicyclic copper ligand complex, as well as plausible transition structures of the nitroaldol reaction, were investigated by DFT calculations.

Earth is perfectly suited for indoor plastering purposes thanks to its numerous technical, ecological and economic assets. The quantity of clay is frequently evoked to explain fresh and mechanical performances of earthen coatings but this indicator fails to give full account of the diversity of earth behaviour encountered in earth construction. This paper aims to examine plaster properties from the point of view of their geotechnical and mineralogical composition. Four types of soil were employed to design earthen plasters with variable earth to sand ratios. The behaviour of coatings was assessed through their water requirement, linear shrinkage, and flexural and compressive strengths. A noteworthy relationship was detected between the water requirement of earth plasters and the liquid limit of the raw earth employed. The mechanical resistances of plasters were found to be linked to the cation exchange capacity of the soils. The correlations between linear shrinkage, or compressive strength, and percentage passing at 2 µm were strong, justifying the widespread use of texture and clay content for soil classification, and assessment of the properties of earth-based building materials.

As a building material, earth is known to be a natural humidity regulator and to improve comfort inside buildings, making it a good choice for indoor plastering. The clayey phase ensures the sorption capacity of the material and its global cohesion by acting as a binder for the sand grain skeleton. However, clay also induces drying shrinkage of the mortar, leading to cracking of the plaster. Additives or stabilizers are typically used to address issues such as mechanical resistance and drying shrinkage in earthen building materials. To promote the development of eco-building materials, this paper pays particular attention to the potential of organic admixtures (vegetal or animal). The effectiveness of such admixtures could depend largely on the type of soil used and on the amount and nature of the clay minerals involved. Four types of soils were investigated. Based on consistency, shrinkage, visual and numerical detection of cracking, and flexural, compressive and shear tests, the characteristics of mortars in fresh and hardened states were evaluated. The results show that the clay content is a key parameter of both fresh properties and mechanical performances of plasters but is not sufficient by itself, especially when organic admixtures are involved. The potential of seven admixtures was evaluated. Although the deflocculants enabled a water reduction in mixes as well as a mechanical improvement, and the cohesion strengtheners were able to enhance mechanical properties at the hardened state, only flax fibre-based mortars demonstrated sufficient adhesion to their application substrate and, above all, no cracking as they dried.

Cryptophanes are receptors consisting of two bridging concave cyclotribenzylene (CTB) subunits. The formation of cryptophanes in basic aqueous solutions (0.1 m MOD; M = Li, Na, K, and Cs) by disulfide bridge formation has been investigated. Two original CTBs, 1H6 and 2H6, derived from cyclotriphenolene through the introduction of mercaptomethyl and mercapto substituents, respectively, were synthesized. Cryptophane formation by slow oxygenation of 16– was observed only in the presence of Me4N+ as template, which yielded the diastereomeric forms in a ratio of around 82:18. By contrast, the rigid CTB 2H6 yielded a cryptophane stereoselectively without a template. Interestingly, air oxidation of a 1:1 mixture of 16– and 26– in the presence of Me4N+ (0.5–1 equiv./16–) in 0.1 m LiOD led to the exclusive formation of the cryptophane complex [(1·1)6–⊃+NMe4], (2·2)6– being formed only in very minor amounts. No mixed species were detected in the reaction mixtures. The stabilities of the diastereomers of the protonated cryptophanes were calculated in the gas phase by DFT at the ωB97XD 6-311G(d,p) level of theory.

Earth masonry is a good alternative to more conventional materials in order to reduce the environmental impact of building materials. However earth construction techniques mostly rely on bricklayers’ experience, which is a hindrance to industrial development of this traditional know-how. This article proposes a methodology for the mix design of unstabilized earth bedding mortar based on mechanical criteria of the masonry and rheological criteria of fresh mortar. A test to characterize the shear strength of the masonry interface is specially investigated. The mechanical performances of the formulated mortar are then validated with laboratory scale characterization.

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; The chromatographic performances of four coated and immobilized amylose phenylcarbamate-based chiral columns were evaluated and compared under normal phase (NP) elution conditions by using chiral 4,4'-bipyri-dine derivatives as analytes. n-Hexane/2-propanol 90:10 and n-hexane/2-propanol/methanol 90:5:5 mixtures were employed as mobile phases (MPs), and the effect of adding methanol in the MP on retention and selectivity was considered. The effect of temperature on retention and selectivity was also evaluated, and overall thermo-dynamic parameters associated with the analyte adsorption onto the CSP surface were derived from van't Hoff plots. Interesting cases of enantiomer elution order (EEO) reversal, which are dependent on the nature of polar modifier, analyte structure, column-type, and temperature, were observed. The impact of substitution pattern and electronic properties of analytes and selectors on the separation behaviour was investigated by correlating chro-matographic parameters and molecular properties determined by using density functional theory (DFT) calculations. Both coated and immobilized amylose tris(3,5-dimethylphenylcarbamate) columns allowed for the baseline enantioseparation (2.0 ≤ R S ≤ 4.9) of all 4,4'-bipyridines considered in this study. These results appear particularly useful because both enantiomers of these 4,4'-bipyridine derivatives are currently under investigation as new inhibitors of transthyretin fibrillogenesis, a biochemical phenomenon which is implicated to cause amyloid diseases.

International audience; Asymmetric catalysis based on halogen and chalcogen bonds (XB and ChB) is in its infancy and the search for new chiral XB and ChB donors represents a crucial step towards its development. In this context, we designed and prepared new motifs containing three key substructures, namely regions of electron charge density depletion centred on iodine and chalcogen atoms, the ethynyl functionality and the planar chiral ferrocenyl platform. Nine ferrocenyl iodoalkynes were prepared as pure enantiomers by asymmetric synthesis. The XB donor property of racemic ferrocenyl iodoalkynes was demonstrated in solution in two benchmark reactions: the Ritter reaction and the benzoxazole synthesis from thioamides. In contrast, the ferrocenyl chalcogenoalkynes were far less active in these reactions. The potential of racemic and enantiopure ferrocenyl iodoalkynes as XB donors were also confirmed by X-ray diffraction analysis observing I···C contacts between the electropositive σ-hole of the iodine atom and electron rich π clouds for all crystal structures studied in the solid state.