Search results for "stacking"
showing 10 items of 215 documents
Robust Two-Dimensional Electronic Properties in Three-Dimensional Microstructures of Rotationally Stacked Turbostratic Graphene
2017
We report on the electronic properties of turbostratic graphitic microdisks, rotationally stacked systems of graphene layers, where interlayer twisting leads to electronic decoupling resulting in charge-transport properties that retain the two dimensionality of graphene, despite the presence of a large number of layers. A key fingerprint of this reduced dimensionality is the effect of weak charge-carrier localization that we observe at low temperatures. The disks' resistivity measured as a function of magnetic field changes its shape from parabolic at room temperature to linear at a temperature of 2.7 K indicating further this type of two-dimensional transport. Compared to Bernal stacked gr…
Synergetic effect of host-guest chemistry and spin crossover in 3D Hofmann-like metal-organic frameworks [Fe(bpac)M(CN)4] (M=Pt, Pd, Ni).
2012
The synthesis and characterization of a series of three-dimensional (3D) Hofmann-like clathrate porous metal-organic framework (MOF) materials [Fe(bpac)M(CN) 4] (M=Pt, Pd, and Ni; bpac=bis(4-pyridyl)acetylene) that exhibit spin-crossover behavior is reported. The rigid bpac ligand is longer than the previously used azopyridine and pyrazine and has been selected with the aim to improve both the spin-crossover properties and the porosity of the corresponding porous coordination polymers (PCPs). The 3D network is composed of successive {Fe[M(CN) 4]} n planar layers bridged by the bis-monodentate bpac ligand linked in the apical positions of the iron center. The large void between the layers, w…
Bis(4-methylthio)phenylthiomethane as assembling ligand for the construction of Cu(I) and Hg(II) coordination polymers. Crystal structures and topolo…
2016
International audience; The novel 1D coordination polymer (CP) [{Cu(mu(2)-Br)(2)Cu}(mu-L2)(2)] CP2 has been obtained by reaction of the tetrakisthioether p-MeSC6H4SCH2SC6H4SMe-p (L2) with CuBr in a 1: 2 metal-to ligand ratio. In contrast to the previously described CP [{Cu(mu(2)-Br)(2)Cu}(mu-L1)(2)] CP1 obtained by reaction of the tetrakisthioether p-MeOC6H4SCH2SC6H4OMe-p (L1) with CuBr, the two independent extended 1D ribbons contain bent Cu(mu(2)-Br)(2)Cu units of the butterfly-type with short Cu center dot center dot center dot Cu separations of 2.679(1) and 2.613(1) angstrom. In contrast to the common planar rhomboid Cu(mu(2)-Br)(2)Cu cluster, this butterfly-shaped geometry of the core …
Post-buckling analysis of cracked multilayered composite plates by pb-2 Rayleigh–Ritz method
2015
Abstract A pb-2 Rayleigh–Ritz variational approach for the analysis of post-buckling behavior of cracked composite plates is presented. The plate is modeled by the first order shear deformation theory taking geometric nonlinearities into account through the von Karman’s theory. General stacking sequences are considered. Cracks are modeled by using subdomain decomposition of the plate coupled with penalty techniques, used to augment the variational statement with the needed continuity conditions along the connected subdomains edges. Numerical procedures have been developed and used to validate the present solution by comparison with available literature results. Original results are then pre…
Post-Buckling Analysis of Damaged Multilayered Composite Stiffened Plates by Rayleigh-Ritz Method
2016
A Rayleigh-Ritz approach for the analysis of buckling and post-buckling behavior of cracked composite stiffened plates is presented. The structure is modeled as the assembly of plate elements modeled by the first order shear deformation theory and taking geometric nonlinearities into account through the von Karman’s theory assumptions. Continuity along the plate elements connected edges and the enforcement of rigid and elastic restraints of the plate boundaries are obtained by using penalty techniques, which also allow to straightforwardly implement efficient crack modeling strategies. General symmetric and unsymmetric stacking sequences are considered and numerical procedures have been dev…
Facile approaches to build ordered amphiphilic tris(phthalocyaninato) europium triple-decker complex thin films and their comparative performances in…
2010
Solution processed thin films of an amphiphilic tris(phthalocyaninato) rare earth triple-decker complex, Eu(2)[Pc(15C5)(4)](2)[Pc(OC(10)H(21))(8)], have been prepared from three different methods: self-assembly (SA) annealed in solvent vapor, quasi-Langmuir-Shäfer (QLS) and drop casting methods. In particular, we successfully developed a simple QLS process for fabricating ordered multilayers with a good thickness control. The films prepared from three different methods were characterized by a wide range of methods including electronic absorption spectra, IR, X-ray diffraction, atomic force microscopy (AFM), and current-voltage (I-V) measurements. J-type aggregates have been formed with the …
Structure determination of three polymorphs of xylazine from laboratory powder diffraction data
2014
The crystal structures of three xylazine hydrochloride [N-(2,6-dimethylphenyl)-5,6-dihydro-4H-1,3-thiaz-2-amine hydrochloride] polymorphsA,ZandXhave been solved from powder diffraction data and refined using Rietveld refinement. Data were obtained with Cu Kα radiation. All polymorphs were found to have structures withZ′ = 1 andZ= 4. All the structures determined contained strong hydrogen bonds between the amino groups and chloride anions. The crystal structures of formsAandXfeatured π–π stacking interactions.
Mononuclear Mn(III) and dinuclear Mn(III,III) Schiff base complexes: Influence of π–π stacking on magnetic properties
2012
Abstract Synthesis of a mononuclear Mn(III) (1) and a dinuclear Mn(III, III) (2) complex of a tetradentate N2O2 donor Schiff base ligand with ancillary carboxylate ligands are reported. Complex 1 crystallizes in the monoclinic space group C2/c, complex 2 in the triclinic space group P-1. In both complexes the central Mn(III) ions are hexacoordinated having a distorted octahedral MnN2O4 coordination environment. Intermolecular hydrogen bonding and strong π–π stacking in both 1 and 2 leads to dimerization of 1 and formation of a syn–anti one-dimensional chain for 2. Magnetic properties of 1 and 2 are reported. Both complexes show very weak intermolecular antiferromagnetic interaction. Most in…
Nickel(II) 3,4;9,10-perylenediimide bis-phosphonate pentahydrate: A metal-organic ferromagnetic dye
2012
The new metal organic compound nickel(II) 3,4;9,10-perylenediimide bis-phosphonate pentahydrate, i.e. Ni-2[(PDI-BP)-(H2O)(2)]center dot 3H(2)O (1), has been synthesized and its structural and magnetic properties have been studied. Reaction of 3,4;9,10-perylenediimide bisphosphonate (PDI-BP, hereafter) ligand and nickel chloride in water resulted in the precipitation of a red and poorly crystalline solid (1). As the solid shows a poor crystalline organization of aggregates, the energy dispersive X-ray diffraction analysis (EDXD) technique has been used to obtain short-range order structural information of the single nanoaggregates by radial distribution function analysis. The overall structu…
Peeling of multilayer graphene creates complex interlayer sliding patterns
2015
Peeling, shearing, and sliding are important mechanical phenomena in van der Waals solids. However, theoretically they have been studied mostly using minimal periodic cells and in the context of accurate quantum simulations. Here, we investigate the peeling of large-scale multilayer graphene stacks with varying thicknesses, stackings, and peeling directions by using classical molecular dynamics simulations with a registry-dependent interlayer potential. Simulations show that, while at large scale the peeling proceeds smoothly, at small scale the registry shifts and sliding patterns of the layers are unexpectedly intricate and depend both on the initial stacking and on the peeling direction.…