Boride-based nano-laminates with MAX-phase-like behaviour

MAX-phases being usually composed of transition metals, group A elements and carbon/nitrogen are considered interesting materials for many applications because of their tremendous bulk modulus, “reversible” plasticity, and machinability. This is mainly due to their unique kind of bonding comprising covalent, ionic as well as metallic bonds providing “easy” planes of rupture and deformability due to the layered crystal structures.In transition metal boride systems, similar types of bonding are available. In particular the W₂B₅-structure type and its stacking variations allow the synthesis of strongly layered crystal structures exhibiting unique delamination phenomena.The paper presents ab initio calculations showing the similarities of bonding between the ternary carbides and the corresponding ternary or quaternary borides. Formation of boride-based nano-laminates from auxiliary liquid phases, from the melt as well as during sintering and precipitation from supersaturated solid solutions will be discussed by means of SEM and TEM studies. The role of impurities weakening the interlayer bonding will be addressed in particular. The pronounced cleavage parallel to the basal plane gives rise for crack deflection and pull-out mechanisms if the laminates are dispersed in brittle matrices such as boron carbide, silicon carbide or other transition metal borides.     

Solvothermal synthesis and removal capacity for hydrogen chloride gas of Zn(OH)(NO3) with a rare (10,3)-d net

A basic zinc nitrate, [Zn(OH)(NO₃)]_n with a novel framework reported herein is prepared by solvothermal synthesis, and holds a rare three-dimensional (10,3)-d net called by Wells. It crystallizes in orthorhombic, space group, Pna2₁ (No. 33), , , , Z=4, , , , 3.49<θ<27.51, , R₁=0.029, wR₂=0.0773 for 697 (I>2σ(I)) of 1728 [R_(int)=0.0246] unique reflections and 59 parameters. GOF=1.073. Interestingly this basic zinc nitrate, [Zn(OH)(NO₃)]_n behaves well at removal capacity for hydrogen chloride gas, 20.3 g HCl/100 g, and its framework is not destroyed yet. This adsorption character may be useful for the removal of toxic gases in the environment.     

Layered metal phosphonates containing pyridyl groups: Syntheses and characterization of Mn2(2-C5H4NPO3)2(H2O) and Zn(6-Me-2-C5H4NPO3)

This paper reports the syntheses and characterization of two phosphonate compounds with layered structures, namely, Mn₂(2-C₅H₄NPO₃)₂(H₂O) (1) and Zn(6-Me-2-C₅H₄NPO₃) (2). In compound 1, double chains are found in which the {Mn₂O₂} dimers are linked by both aqua and O-P-O bridges. These double chains are connected through corner-sharing of {MnO₅N} octahedra and {CPO₃} tetrahedra, forming an inorganic layer. The pyridyl groups fill the inter-layer spaces. In compound 2, each {ZnO₃N} tetrahedron is vertex-shared with three {CPO₃} tetrahedra and vice versa, hence forming an inorganic honeycomb layer. The pyridyl groups reside between the layers. Magnetic studies show that weak antiferromagnetic interactions are mediated between the manganese ions in compound 1. Crystal data for 1: monoclinic, space group C2/c, , , , β=107.3(1)°. For 2: orthorhombic, space group Pbca, , , .     

Study on structural properties and solution dynamics of zinc complexes with the (N,N-dimethylaminomethyl)ferrocenyl ligand

The reaction of {C,N-[Fe(η⁵-C₅H₅)(η⁵-C₅H₃(CH₂NMe₂)-2)]}Li, (FcN)Li, with zinc chloride affords the diorganozinc complex (FcN)₂Zn (1). In solution, 1 appears as a mixture of rac and meso diastereomers, whereas in the solid state it crystallizes solely as a rac diastereomer. The ratio of rac/meso diastereomers in solution is solvent-, temperature- and concentration-dependent, consistent with an intermolecular exchange between diastereomers. An intramolecular dynamic phenomenon involving dissociation and recoordination of Zn---N bonds was also observed. The reaction of 1 with zinc chloride yields the monoorganozinc compound (FcN)ZnCl (2) as a slightly soluble yellow microcrystalline powder.     

Synthese und Kristallstruktur des Goldclusters [Au16(AsPh3)8Cl6]

Synthesis and Structures of the Gold Cluster [Au₁₆(AsPh₃)₈Cl₆] Reduction of Ph₃AsAuCl with NaBH₄ in ethanol yields the gold cluster [Au₁₆(AsPh₃)₈Cl₆]. It can be crystallized from dichloromethane/diisopropyl ether in form of dark red, light sensitive crystals with the space group P2₁/n and a = 1777.68(8), b = 3372.7(1), c = 2696.2(1)pm, β = 94.166(6)°, Z = 4). The inner skeleton of the 16 Au atoms consists of a centered icosahedron of which one of the corners binds to three additional Au atoms forming a tetrahedron pendent. The shortest Au–Au distances of 264.3 to 266.6 pm correspond to the bonds to the three external Au atoms. Within the icosahedron the distances between the central atom and the peripheral atoms (273.0–279.1 pm) are distinctly shorter than the distances between the peripheral atoms (283.6–299.0 pm).     

Synthesis, Characterization, Crystal Structure and Stability of a Ternary Cu（Ⅱ） complex with 1, 10-Phenanthroline and L-Valinate

It is important to research the mixed-ligand copper complexes containing bioligands, such as amino acids, nucleic acids and proteins, in exploring the functional mechanism of microelement copper in organism because the reaction of any micronutrient with two or more bioligands in the concentrated bioligands background gives mixed-ligand ternary complexes, which are more stable and related with storage of substance and transportationof metal ions in the life process.     

Synthesis, Structure and Characterization of Manganese（ Ⅱ ） Coordination Polymer with Camphoric Acid and 1, 10-Phenanthroline

IntroductionThe syntheses of metal-organic coordination poly-mers have been attracting increasing attention owing tothe potential applications of their functional materials incatalysis,non-linear optics,magnetism sensors andmolecular recognition[1—7].Coordination polymers crys-tallized from polyaromatic acids and metal-ions are ofgreat interest for their polymeric structures and porousproperties[8—12].Their network topologies based on mo-lecular building blocks are usually controlled and mod…     

First examples of neutral rhenium(V) complexes with a novel semi-rigid ligand containing a P,N,N,S donor atom set: Synthesis,characterisation and crystal structure

A new PN₂S ligand, N-[2-(diphenylphosphino)phenyl]-2-[(S-trityl)acetylamino]ethanamide [Ph-P(Ph₂)N₂S(Trt)], was synthesised and reacted with Re^V precursors. The reaction of both tritylated and detritylated ligands with ReOCl₃(PPh₃)₂ gave the same expected neutral complex [ReO{Ph-P(Ph₂)N₂S}] (4) in good yield. An unexpected neutral and diamagnetic species, [ReN{Ph-P(Ph₂)N₂S(Trt)}] (5), has been isolated during the complexation of the tritylated ligand with ReNCl₂(PPh₃)₂. The complexes, characterized by classical spectroscopic methods and X-ray analysis for 4, are the first examples of neutral semi-rigid-PN₂S rhenium(V) complexes.     

Some new trends in the ionoluminescence of minerals

Ionoluminescence (IL) has mainly been used to detect impurities or defects inside synthetic materials. This paper gives a summary of new applications of IL to natural minerals that might be found in ancient pieces of jewellery or decorative artefacts (affreschi, stucchi, mosaics). Some relevant examples of its use for archaeometrical purposes are given to highlight the potential of the technique. Chemical information can be obtained by luminescent characterization of minerals. IL spectra act as digital imprint for elements or defects inside each material, enabling differentiation of natural specimens from imitations and/or synthetic analogues. Crystal field theory indicates it is the coordination number of the emitter inside the crystalline structure that gives information on its valence. Historical confusion between rubies and red spinel can easily be resolved by analysis of IL spectra. Modern synthetic diamonds can also be discriminated and blue sapphire can be distinguished from blue kyanite, a silicate that is currently being sold as its imitation. The technique can also differentiate between the synthetic and the natural gems. Polymorphs can be identified, and it is possible to recognize minerals from isomorphic series (from the same chemical group with the same structure) even when they share the same light emitter (e.g. Mn²⁺, in carbonates). High-quality glasses (e.g. laser glasses) which are normally used for faking gemstones can be also detected. We fully believe IL will, in the future, be a powerful technique for determining the crystallinity of solids. This paper gives an overview of possible applications of IL to archaeometry for mineral characterization; this is a new application that still requires further study.     

Synthesis, crystal structure and photoluminescence of 2,6-dimethylanthracene and its pseudo-triptycene derivatives

A simple one-step synthesis of 2,6-dimethylanthracene, 1, in high yield is reported utilizing the easily accessible benzyl alcohol as the starting material. Based on 2,6-dimethylanthracene, two pseudo-triptycene compounds, cis-2,6-dimethyl-9,10-dihydroanthracene-9,10-endo-α,β-succinic anhydride, 2, and cis-2,6-dimethyl-9,10-dihydroanthracene-9,10-endo-α,β-succinyl amine, 3, are firstly synthesized in high yield and they are characterized by single crystal X-ray diffraction. Compound 2 crystallizes in triclinic space group and compound 3 crystallizes in monoclinic P2₁/c space group. Both compound 2 and 3 exhibit cis-configurations and endo-conformations. Compound 1 exhibits very intense photoluminescence property due to the delocalized electron in the whole molecule, whereas fluorescence quench happens to some extents due to the destruction of the conjugated structure in compound 2.