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The employment of the hexyl-substituted anion [HexCB11 Cl11 ]- allowed the synthesis of a ZnII species, Zn[HexCB11 Cl11 ]2 , 3, in which the Zn2+ cation is only weakly coordinated to two carborate counterions and that is soluble in low polarity organic solvents such as bromobenzene. DOSY NMR studies show the facile displacement of at least one of the counterions, and this near nakedness of the cation results in high catalytic activity in the hydrosilylation of 1-hexene and 1-methyl-1cyclohexene. Fluoride ion affinity (FIA) calculations reveal a solution Lewis acidity of 3 (FIA=262.1 kJ mol-1 ) that is higher than that of the landmark Lewis acid B(C6 F5 )3 (FIA=220.5 kJ mol-1 ). This high Lewis acidity leads to a high activity in catalytic CO2 and Ph2 CO reduction by Et3 SiH and hydrogenation of 1,1-diphenylethylene using 1,4-cyclohexadiene as the hydrogen source. Compound 3 was characterized by multinuclear NMR spectroscopy, mass spectrometry, single crystal X-ray diffraction, and DFT studies.

Ultrathin Au nanowires (NWs) with a diameter below 2 nm have attracted considerable attention as a promising one-dimensional nanomaterial. However, they are practically synthesized in organic solve...

The article presents the results of research on the structural evolution of the composite Fe-Al-based coating deposited by arc spray with initial low participation of in situ intermetallic phases. The arc spraying process was carried out by simultaneously melting two different electrode wires, aluminum and low alloy steel (98.6 wt.% of Fe). The aim of the research was to reach protective coatings with a composite structure consisting of a significant participation of FexAly as intermetallic phases reinforcement. Initially, synthesis of intermetallic phases took place in situ during the spraying process. In the next step, participation of FexAly fraction was increased through the annealing process, with three temperature values, 700 °C, 800 °C, and 900 °C. Phase structure evolution of the Fe-Al arc-sprayed coating, stimulated by annealing, has been described by means of SEM images taken with a QBSD backscattered electron detector and by XRD and conversion electron Mössbauer spectroscopy (CEMS) investigations. Microhardness distribution of the investigated annealed coatings has been presented.

Two chitosan silica hybrid materials were prepared by a two-step process in 78–84% yields using the homogeneous phase reaction of 3-(triethoxysilyl)propyl isocyanate with chitosan dissolved in 1-n-butyl-3-methylimidazolium chloride ionic liquid (∼10% w/w), which was followed by NH4OH catalyzed hydrolysis of triethoxysilyl groups and then sol-gel process. These new hybrid materials were shown to adsorb up to about 95% of Fe3+ from 5 × 10−4 M aqueous solution at room temperature in 24 h.

Ultrasmall (≤3 nm) bimetallic nanoparticles with controllable compositions and structure are of great interest for their catalytic activity, especially carbon dioxide reduction. Herein is reported ...

MXenes are two-dimensional metal carbides with promising applications in energy storage and sensors. Guidelines for safe, scalable MXene synthesis are important due to ongoing efforts to scale-up production of these novel nanomaterials. Hazard identification before scale-up will allow for inherently safer designs prior to actual implementation. Here, we investigate hazards associated with MXene production, including MAX phase synthesis from raw materials, etching of the MAX phase to MXene clay, exfoliation to MXene nanosheets, and postprocessing of MXenes with Ti3C2Tx as a model species. The major hazards in MXene synthesis are the potential for dust ignition, runaway reactions, and toxic chemical exposure. Because the synthesis of MXenes is a multistep process, safety guidelines for each step are evaluated, including preventive and mitigating measures, best practices, and emergency procedures and responses. This includes handling of combustible powders, exothermic reactions, and harsh chemical etchants. ...

A mechanistic study on the two-phase synthesis of heteroleptic Au nanoclusters (NCs) is reported here. First, the effects of binary ligands on controlling the size of Au NCs were examined: (1) the binary ligands could exhibit an eclectic effect on the size control of Au NCs if the binding affinities of such hetero-ligands with Au are comparable and (2) the binary ligands could exhibit a competitive effect on the size control of Au NCs, and the size of the Au NCs could be determined by the ligand with stronger binding affinity to Au. This finding is interesting and can shed some light on the design of new functional metal NCs. Secondly, the formation mechanism of the heteroleptic Au NCs that originated from the complex precursors was unprecedentedly studied. The complex precursors of the heteroleptic Au NCs were identified to be the predominant hybridized ligand#1–Au(I)–ligand#2 species, which is helpful for understanding the synthetic mechanisms in depth. Moreover, the growth processes of the heteroleptic Au NCs were also monitored, and some fundamental perceptions about the growth pathway and the structures of the Au NCs were obtained.

We report the asymmetric synthesis of homochiral metal-organic materials (MOMs) in chiral gels from achiral components. The enantioselectivity of MOMs depends on the chirality of the gel, whereas the synthesis performed in solution phase and achiral gels resulted in conglomerates.

MWDHM provides measurements of the refractive index. However, successive-shot MWDHM is not appropriate for dynamic samples and single-shot MWDHM significantly increases the complexity of the optical setup. Here we consider DL/CNN to obtain simultaneous MW measurements.

Taxol® is widely regarded as amongst the most famed natural isolates ever discovered, and has been the subject of innumerable studies in both basic and applied science. Its documented success as an anticancer agent, coupled with early concerns over supply, stimulated a furious worldwide effort from chemists to provide a solution for its preparation through total synthesis. Those pioneering studies proved the feasibility of retrosynthetically-guided access to synthetic Taxol, albeit in minute quantities and with enormous effort. In practice, all medicinal chemistry efforts and eventual commercialization have relied upon natural- (plant material) or biosynthetically-derived (synthetic biology) supplies. Here we show how a complementary divergent synthetic approach that is holistically patterned off of biosynthetic machinery for terpene synthesis can be used to arrive at Taxol®.

We have achieved the first reported pure phase synthesis of two new nanoparticle materials, Cu3PS4 and Cu6PS5Cl. We have achieved this through learning about the potential reaction pathways that CuCl2, P2S5, and 1-dodecanethiol can take. This study has shown that the key variable to control is the state of the phosphorus source when the CuCl2 is added. If P2S5 is added together with the CuCl2 to dodecanethiol then the reaction will follow a path to Cu3PS4, but if it is dissolved in dodecanethiol prior to the addition to CuCl2 then the reaction will produce Cu6PS5Cl. The formation of these two different phases can occur simultaneously, yet we have found sets of conditions that manipulate the reaction system to form each phase exclusively. These nanoparticles could have broad semiconductor or solid electrolyte applications.

In this work, ice bath assisted co-precipitation synthesis of nanostructured Bismuth Manganite (BiMn2O5) with varied bismuth concentration and their consequences on the structural properties have rationally been investigated for first time in reports. The novelty of this study is to primarily elucidate the crystalline phase formations and related structural as well as compositional changes while fabricating BiMn2O5 with different amount of Bi content up to 20% to compensate the volatile Bi during annealing process. Powder X-ray diffraction and Rietveld Refinement techniques evidently confirmed the formation of single-phase mullite-type orthorhombic perovskite structure for stoichiometric ratio; while increasing Bi content, a secondary phase sillenite (Bi24Mn2O40) was formed which also gradually increased with increase in bismuth in the precursor solution. Rod and cubic shaped morphologies were commonly observed and size of the particles shows particle size ranging between 45 nm and 120 nm with increase of bismuth content. The mixed morphology is inevitably due to the presence of the secondary phases due to increasing Bi content that are evident from the XRD results. Raman and Optical properties evidently confirmed the structural variation and changes in the band gap respectively owing to the increase in secondary phase evolution with excess bismuth content. X-ray photoelectron spectroscopy (XPS) studies confirmed the increment in Bi content and the coexistence of Mullite and Sillenite phases in the samples.

Mg5Al2.4Zr1.7O12 metastable phase was successfully synthesized from analytical-grade MgO, α-Al2O3, MgAl2O4, and ZrO2 under an N2 atmosphere. The sintering temperature was varied from 1650 to 1780°C, and the highest amount of Mg5Al2.4Zr1.7O12 appeared in the composite material when the sintering temperature was 1760°C. According to our research of the formation mechanism of Mg5Al2.4Zr1.7O12, the formation and growth of MgAl2O4 dominated when the temperature was not higher than 1650°C. When the temperature was higher than 1650°C, MgO and ZrO2 tended to diffuse into MgAl2O4 and the Mg5Al2.4Zr1.7O12 solid solution was formed. When the temperature reached 1760°C, the formation of Mg5Al2.4Zr1.7O12 was completed. The effect of MgAl2O4 spinel crystals was also studied, and their introduction into the composite material promoted the formation and growth of Mg5Al2.4Zr1.7O12. A highly dispersed MgO–MgAl2O4–ZrO2 composite material was prepared through the decomposition of the Mg5Al2.4Zr1.7O12 metastable phase. The as-prepared composite material showed improved overall physical properties because of the good dispersion of MgO, MgAl2O4, and ZrO2 phases.

New magnesium-substituted bone cements containing MgO as a separate phase have been developed and demonstrated enhanced mechanical properties and cytological compatibility.

The evolution towards equilibrium of AuCo, AgNi and AgCu nanoparticles is studied by molecular dynamics simulations. Nanoparticle sizes of about 2.5 nm are considered, in the temperature range from 300 to 700 K. The simulations reveal complex equilibration pathways, in which geometric structure and chemical ordering change with time. These nanoparticles present the same type of strong tendency to phase separation and to surface segregation of either Au or Ag, which lead to the same type of core@shell equilibrium structures. In spite of these similarities, the equilibration pathways of these nanoparticles from chemically disordered configurations present both quantitative and qualitative differences. Quantitative differences are found in the equilibration time scale, which is much longer in AgCu than in AgNi and AuCo. Qualitative differences are found in the presence or absence of geometric structure transformations, and in the formation of different types of three-shell metastable chemical ordering during evolution. It is also shown that surface segregation depends on the geometric structure, being faster in icosahedra than in fcc nanoparticles.

Antifreeze glycoproteins are a class of biological agents which enable living at temperatures below the freezing point of the body fluids. Antifreeze glycopeptides usually consist of repeating tripeptide unit (-Ala-Ala-Thr*-), glycosylated at the threonine side chain. However, on the microscopic level, the mechanism of action of these compounds remains unclear. As previous research has shown, antifreeze activity of antifreeze glycopeptides strongly relies on the overall conformation of the molecule as well an on the stereochemistry of amino acid residues. The desired monoglycosylated analogues with acetylated amino termini and the carboxy termini in form of N-methylamide have been synthesized. Conformational nuclear magnetic resonance (NMR) studies of the designed analogues have shown a strong influence of the stereochemistry of amino acid residues on the peptide chain stability, which could be connected to the antifreeze activity of these compounds. A better understanding of the mechanism of action of antifreeze glycopeptides would allow applying these materials, e.g., in food industry and biomedicine.

A density functional theory study of Cr, Mn and Fe substitutions in Bi2Ti2O7 (BTO) photocatalysts is presented. We performed a stability analysis from our total energy calculations and have determined formations of dopant inspired phases are detrimental to the overall photocatalytic performance of X-doped BTO. From our calculated formation energies and electronic structures it is shown that X substitution of Ti is least stable and should be associated with formation of secondary phases more so than X substitution of Bi. This result contradicts the many experimental studies which suggest transition metal dopants always substitute Ti in BTO, but on the other hand, explains the poor photocatalytic response beyond what has become known as the critical dopant concentration.

CIS (CuInS2) is one of the most effective photovoltaic devices with high stability and efficiency, because of its suitable bandgap (1.5eV). Moreover, it does not contain toxic materials, such as Se, within its components. However, productivity and utilization of natural resources under the gas phase synthesis method is relatively low, since vaporizing temperature of elements is extremely different. Thus, it is required to develop a synthesis method of CIS solar cell materials within liquid phase. Here, we have already developed a synthesizing method of single phase and homogenous CI (CuIn) alloy nanoparticles in aqueous solution. In this method, the concentration of the metal complexes in the solution are calculated by using the critical stability constants, and the reduction reaction rate of both metal ions is also controlled. Synthesized CI nanoparticles were spin coted onto Mo/glass substrate and selenized, consequently it shows the photo voltaic effect. Thus, printable solar cells can be formed by using this method. The synthesizing method contains the selenization which is a sort of evaporation method, so it is not liquid process completely. To synthesize CIS solar cells without the selenization, we tried to sulfurize CI nanoparticles but CIS particles were not synthesized. It is difficult to sulfurize CI nanoparticles because they are stable and hard to react with sulfur ions, so it is necessary to synthesize from copper ions and indium ions to CuInS2 particles directly. However, nobody can synthesize CuInS2 particles in aqueous solution because there is a difference between the sulfurization reaction rate of copper and indium ions. If the sulfurization reaction rate of both metal ions is different, they are sulfurized independently to form their own sulfides, such as Cu2S or CuS and In2S3. It is necessary to control and approximate the sulfurization reaction rate of both metal ions for synthesis of CuInS2 particles. Here, in the sulfurization process, the sulfurization reaction rate is correlation with potential energy such as gibbs free energy (ΔG) or activation energy (Ea ). Hence, CuInS2 particles can be synthesized under the condition that the ΔG or Ea in the sulfurization reaction of copper and indium ions are approximated. To synthesize CuInS2 particles in aqueous solution, we tried to approximate the ΔG of the sulfurization reaction of copper and indium ions. By calculating ΔGCu2S and ΔGIn2S3 , we obtained the correlation of KIn and KCu and we were able to select appropriate complexing agents, so we tried to synthesize CuInS2 particles by using these reagents. XRD data indicates that several peaks with a dominant CuInS2 peak were observed. From the above results, it can be said that the synthesis of the precursor of CuInS2 particles in aqueous solution was successful because the Ea of the sulfurization process are approximated in both metal ions. In addition, it was found that the ΔG of copper and indium ions are approximated in the sulfurization system (Cu-In-IDA), so it is necessary to control and approximate both the ΔG and Ea for synthesis of CuInS2 particles in aqueous solution. Although the precursor of CuInS2 were synthesized in aqueous solution, the size and shape of the particles were not uniform. Therefore, for preventing degradation of conversion efficiency, it is needed to develop a technique for homogenizing the shape and the size of the particles. Detailed and another results will be introduced in our presentation. This work has been supported by the Grant-in-Aid for Scientific Research (B) (18H03416).

The synthesis method of controlled nulls in sum and difference patterns in the direction of jamming for planar monopulse antenna array is proposed. It’s shown that to solve the problem the calculation of amplitude-phase distribution only for one row (or column) of subarray (a quarter part of antenna aperture) elements is enough.

El objetivo de esta tesis es investigar sobre la sintesis, propiedades y aplicaciones de las nanoparticulas de Ca(OH)2 para consolidar materiales patrimoniales arquitectonicos. Las nanoparticulas de Ca(OH)2 se han utilizado recientemente en la conservacion del patrimonio, aunque algunos aspectos de la sintesis no son completamente comprendidos. En el presente estudio, hemos desarrollado metodos optimizados para obtener nanoparticulas de alta pureza mediante sintesis de fase homogenea y heterogenea utilizando diferentes materiales de partida. Se han realizado del orden de cien sintesis en diferentes condiciones para comprobar la validez y fiabilidad del metodo sintetico. Los resultados confirman que la temperatura de reaccion tiene una gran influencia en el tamano y la morfologia de las nanoparticulas de Ca(OH)2. Ademas, se ha investigado la estabilidad de las nanoparticulas a lo largo del tiempo en mezclas de 2-propanol / agua, en las que se encontro que la ausencia de agua era critica para evitar la aglomeracion de Ca(OH)2. Una vez dispersas en 2-propanol, las nanoparticulas se han utilizado para consolidar sustratos reales (piedra, adobe y estuco) confirmando su alto rendimiento en terminos de consolidacion superficial y – cuando se mezcla con ciertos surfactantes – en reduccion de la absorcion de agua. Asimismo, se ha investigado el uso de nanoparticulas modificadas basadas en M(OH)2, donde M=Ca2+, Mg2+, con el objetivo de mejorar tanto la cohesion superficial como la durabilidad de los materiales patrimoniales (p. ej. piedra Tabaire). Finalmente, el tratamiento de consolidacion basado en nanoparticulas puras de Ca(OH)2 se utilizo en emplazamientos con valor patrimonial, como edificios historicos y yacimientos arqueologicos (Teatro Romano de Cartagena) obteniendo resultados satisfactorios. The aim of this thesis is to investigate on the synthesis, properties and applications of Ca(OH)2 nanoparticles to consolidate architectural heritage materials. Ca(OH)2 nanoparticles have recently been used in heritage conservation, although some aspects of the synthesis are not fully-understood. In the present study, we have developed optimised methods for obtaining high-purity nanoparticles based on homogenous and heterogeneous phase synthesis using different starting materials. Around one hundred syntheses have been performed to test the validity and reliability of the synthetic method in different conditions. The results confirm that the reaction temperature has a great influence on the size and morphology of Ca(OH)2 nanoparticles. Besides, the nanoparticles stability has been investigated over time in 2-propanol / water mixtures, in which the absence of water was found to be critical to avoid Ca(OH)2 agglomeration. Once dispersed in 2-propanol, the nanoparticles have been used to consolidate real substrates (stone, adobe and stucco) confirming their high performance in terms of surface consolidation and – when mixed with certain surfactants – water absorption. Likewise, the use of modified nanoparticles based on M(OH)2, where M=Ca2+, Mg2+, has been investigated with the aim of improving both the surface cohesion and durability of heritage materials (e.g. Tabaire stone). Finally, the consolidation treatment consisting in pure Ca(OH)2 nanoparticles has been used in cultural heritage sites, such as historical buildings and archaeological monuments (Roman Theatre of Cartagena) leading to satisfactory results. http://repositorio.bib.upct.es/dspace/

Sequence-defined macromolecules consist of a defined chain length (single mass), end-groups, composition and topology and prove promising in application fields such as anti-counterfeiting, biological mimicking and data storage. Here we show the potential use of multifunctional sequence-defined macromolecules as a storage medium. As a proof-of-principle, we describe how short text fragments (human-readable data) and QR codes (machine-readable data) are encoded as a collection of oligomers and how the original data can be reconstructed. The amide-urethane containing oligomers are generated using an automated protecting-group free, two-step iterative protocol based on thiolactone chemistry. Tandem mass spectrometry techniques have been explored to provide detailed analysis of the oligomer sequences. We have developed the generic software tools Chemcoder for encoding/decoding binary data as a collection of multifunctional macromolecules and Chemreader for reconstructing oligomer sequences from mass spectra to automate the process of chemical writing and reading., Sequence-defined macromolecules consist of a defined chain length and topology and can be used in applications such as antibiotics and data storage. Here the authors developed two algorithms to encode text fragments and QR codes as a collection of oligomers and to reconstruct the original data.

International audience; A novel design methodology for multibeam-on-receive scanning arrays is here presented. A hybrid analog/digital beam-forming network and a clustered architecture are considered. The proposed methodology aims at optimize the clustering configuration in order to guarantee the lowest possible side lobe level when steering the beams within a given scanning range, and operating within a given bandwidth. A novel analytic phase synthesis method allows the efficient computation of optimal sub-array phases for pointing the beams towards desired directions. Moreover, a global optimizer is used for the clustering configuration optimization. Finally, a numerical example has been reported to validate the proposed approach.

Supplementary files; International audience; An efficient and rapid synthesis of new series of N-alkyl-2-aryl-5H-imidazo[1,2-b]pyrazoles has been achieved in high yields through a three-component reaction of 3-amino-4-substituted pyrazoles, aromatic aldehydes and isocyanides mediated by acid catalysts. In addition, a novel and straightforward approach to a sequential one-pot multicomponent reaction has been developed for the synthesis of hitherto undescribed 7,7'-(substituted methylene) bis-imidazo[1,2-b] pyrazoles, starting from 3-amino-5-substituted (or unsubstituted) pyrazoles, various aldehydes and isocyanides. The reaction was performed under mild conditions in the presence of inexpensive zirconium(IV) chloride as a catalyst. A library of 22 products was obtained in moderate to good yields.

This communication proposes a novel wideband phase synthesis approach, which is able to considerably increase the bandwidth of the reflectarray antenna independent of the element frequency behavior. Specifically, the reference phases at the Ku-band transmitting and receiving frequencies are optimized, simultaneously, to minimize the total phase error of the reflectarray. Simulation and experimental results of reflectarrays consisting of simple square-ring elements show that a 16.7% measured bandwidth within 1.5-dB gain variation can be achieved by a single-layer design with a thin substrate. The proposed approach is applicable to general reflectarray elements and the phase synthesis process is easy-to-implement compared with other conventional wideband reflectarray designs.

Highly dispersed olive-like NiS particles were synthesized in a liquid-liquid biphasic system at room temperature, where nickel xanthate in organic solvents (toluene and benzene) and sodium sulfide in water solution were used as nickel and sulfide sources, respectively. NiS particles were formed at the stabilized phase interface. The structures, chemical composition and optical characteristics of the products were investigated by transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and ultraviolet-visible spectroscopy. The organic solvents obviously influenced the morphology of the NiS particles. The olive-like NiS with smooth surface and sharp ends was obtained at benzene/water interface, while spindle-like NiS particles with rough surface and circle ends were formed when using toluene as a solvent. Analogously, chainlike Bi2S3 nanowires were produced at chloroform/water interface. The effect of the experiment parameters including reaction time, solvent and concentration of reactants on the size and morphology of the products was discussed in detail and a possible formation mechanism was suggested.

A general strategy is introduced for the efficient synthetic access of disulfide linked artificial macrocycles via a Ugi four-component reaction (U4CR) followed by oxidative cyclization. The double-mercapto input is proposed for use in the Ugi reaction, thereby yielding all six topologically possible combinations. The protocol is convergent and short and enables the production of novel disulfide peptidomimetics in a highly general fashion.

A method of amplitude-phase synthesis of planar antenna arrays based on the principle of partial beams. Unlike the method proposed by the prior art is the ability to adjust the width of the partial beam. The results of numerical studies illustrating the performance of the proposed method and improving the quality of the beam pattern formed by the introduction of an additional parameter optimization.