Search results for "Perpendicular"
showing 10 items of 168 documents
Dicopper(II) Metallacyclophanes with Oligo(p-phenylene-ethynylene) Spacers: Experimental Foundations and Theoretical Predictions on Potential Molecul…
2013
Two novel double-stranded dicopper(II) metallacyclophanes of formula (nBu4N)4[Cu2(dpeba)2]·4MeOH·2Et2O (1) and (nBu4N)4[Cu2(tpeba)2]·12H2O (2) have been prepared by the Cu(II)-mediated self-assembly of the rigid ('rod-like') bridging ligands N,N'-4,4'-diphenylethynebis(oxamate) (dpeba) and N,N'-1,4-di(4-phenylethynyl)phenylenebis(oxamate) (tpeba), respectively. Single crystal X-ray diffraction analysis of 1 confirms the presence of a dicopper(II)tetraaza[3.3]4,4'-diphenylethynophane metallacyclic structure featuring a very long intermetallic distance between the two square planar Cu(II) ions [r = 14.95(1) Å]. The overall parallel-displaced π-stacked conformation of the two nearly planar par…
ChemInform Abstract: Spectroscopic and Theoretical Studies on the Internal Rotational Barrier of 1-Acetylcyclohexene
1987
Abstract MINDO-3 molecular orbital calculations with full geometry optimization have been carried out on 1-acetylcyclohexene (ACH) in order to estimate the rotational barrier for the acetyl group, and to localize the less energetic conformation. MNDO calculations have also been carried out for comparative purposes. Both methods point to the non-delocalized structure with the two π-clouds perpendicular to the less energetic conformation. A decomposition of the barrier energy by means of Fourier analysis is made in order to characterize the contributions to the barrier. The UV spectrum of ACH has been recorded both in vapor phase and in hexane solution. These spectra are related to the one ca…
Über polygermane
1980
Abstract The crystal structure of octaphenylcyclotetragermane, (Ph 2 Ge) 4 , has been determined and refined to an R value of 0.046. The symmetry of the molecule approximater D 2d . the Ge 4 ring is nearly planar and square (angle of pucker 3.9°, GeGe 246.5(5) pm). The 8 phenyl groups (GeC 196.2(10) pm) are arranged in two distinct sets (“parallel” touching and perpendicular to the Ge 4 ring) which exchange their positions in solution. The packing of the (Ph 2 Ge) 4 molecules in the crystal resembles a cubic body centred sphere packing. The homocyclic series (Ph 2 Ge) n with n 4, 5, 6 shows 13 C NMR signals in CDCl 3 solution monotonic dependent on the endocyclic GeGeGe angles.
Magnetic field-induced alignment of molecular rotor-shaped cyclophanes
2010
Molecular pinwheels consisting of dipolar substituted cyclophanes in solution can function as free microscopic rotors in the presence of a homogeneous static magnetic field B and a circularly polarized electric field E rotating on a plane containing B. Owing to the high magnetic anisotropy of [26](1,2,3,4,5,6)cyclophane and [36](1,2,3,4,5,6)cyclophane biased by strong ring currents, ∼1 in 105 molecules are expected to align with the C6 symmetry axis perpendicular to a magnetic field of 21 T. The magnetic-field-controlled alignment of rotor-shaped cyclophanes is insignificantly affected by nonpolar solvents, for example, toluene.
Electrohydrodynamic instabilities and orientation of dielectric ellipsoids in low-conducting fluids.
2000
We study the dynamics of an ellipsoidal particle in a weakly conducting dielectric liquid when submitted to a dc electric field. At low field intensities, the particle long axis is aligned in the field direction. When the field strength is increased, we show that, depending on the initial orientation of the particle, there exist two stable orientations: the one with the long axis parallel to the field direction remains possible while a spinning state with the long axis perpendicular to the field appears. This last striking orientation is due to the finite Maxwell-Wagner polarization relaxation time. For sufficiently high field intensities, each state loses its stability and the particle dyn…
Construction and stability of a close-packed structure observed in thin colloidal crystals
2007
We have characterized a close-packed structure of confined charged colloidal spheres, which has been recently discovered. Using different microscopy experiments, the vertically arranged hexagonal planes of n - hcp perpendicular are found to continuously evolve from the horizontally oriented stacks of n hexagonal planes (nDelta) following the maximum packing criterion, but discontinuously transform to a stack of n+1 square planes [(n+1)[SHAPE OF A SQUARE]]. Large mechanically stable domains with threefold twin structures are regularly observed in the suspended state at packing fractions between 0.4 and 0.58.
Equidistribution of Common Perpendicular Arcs
2019
In this chapter, we prove the equidistribution of the initial and terminal vectors of common perpendiculars of convex subsets, at the universal covering space level, for Riemannian manifolds and for metric and simplicial trees.
A Novel Multi-Scale Strategy for Multi-Parametric Optimization
2017
The motion of a sailing yacht is the result of an equilibrium between the aerodynamic forces, generated by the sails, and the hydrodynamic forces, generated by the hull(s) and the appendages (such as the keels, the rudders, the foils, etc.), which may be fixed or movable and not only compensate the aero-forces, but are also used to drive the boat. In most of the design, the 3D shape of an appendage is the combination of a plan form (2D side shape) and a planar section(s) perpendicular to it, whose design depends on the function of the appendage. We often need a section which generates a certain quantity of lift to fulfill its function, but the lift comes with a penalty which is the drag. Th…
The Observation of Formation and Annihilation of Solitons and Standing Strain Wave Superstructures in a Two-Dimensional Colloidal Crystal
2008
Confining a colloidal crystal within a long narrow channel produced by two parallel walls can be used to impose a meso-scale superstructure of a predominantly mechanical elastic character [Chui et al., EPL 2008, 83, 58004]. When the crystal is compressed in the direction perpendicular to the walls, we obtain a structural transition when the number of rows of particles parallel to the walls decreases by one. All the particles of this vanishing row are distributed throughout the crystal. If the confining walls are structured (say with a corrugation along the length of the walls), then these extra particles are distributed neither uniformly nor randomly; rather, defect structures are created a…
Enhanced perpendicular magnetocrystalline anisotropy energy in an artificial magnetic material with bulk spin-momentum coupling
2019
We systematically investigate the perpendicular magnetocrystalline anisotropy (MCA) in $\mathrm{Co}\ensuremath{-}\mathrm{Pt}/\mathrm{Pd}$-based multilayers. Our magnetic measurement data show that the asymmetric Co/Pd/Pt multilayer has a significantly larger perpendicular magnetic anisotropy (PMA) energy compared to the symmetric Co/Pt and Co/Pd multilayer samples. We further support this experiment by first-principles calculations on ${\mathrm{CoPt}}_{2}, {\mathrm{CoPd}}_{2}$, and CoPtPd, which are composite bulk materials that consist of three atomic layers in a unit cell, Pt/Co/Pt, Pd/Co/Pd, and Pt/Co/Pd, respectively. By estimating the contribution of bulk spin-momentum coupling to the …