scholarly journals Ring rotation of ferrocene in interlocked molecules in single crystals

2021 ◽  
Author(s):  
Chi-Hsien Wang ◽  
Kai-Jen Chen ◽  
Tsung-Huan Wu ◽  
Hung-Kai Chang ◽  
Yoshitaka Tsuchido ◽  
...  
Keyword(s):  
Crown Ether ◽  
Single Crystals ◽  
Internal Rotation ◽  
Molecular Motions ◽  
Interlocked Molecules ◽  
Ring Rotation

Unique molecular motions, reversible internal rotation of ferrocene and flipping of crown ether are observed in DB30C10 and DB18C6-containing interlocked molecules, respectively.

Structure and Molecular Motions in Rubidium Tetraphenylborate

2002 ◽  
Vol 57 (11) ◽  
pp. 847-853 ◽  
Author(s):  
A. Pajzderska ◽  
H. Małuszyńska ◽  
J. Wa̡sicki
Keyword(s):  
Potential Energy ◽  
Small Angle ◽  
Phenyl Ring ◽  
Unit Cell ◽  
Molecular Motions ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Ring Rotation ◽  
Phenyl Rings

By X-ray diffraction it was found that at 293 K the crystals of rubidium tetraphenylborate are tetragonal, space group I42m, a = b = 11.212(2) Å, c = 8.098(2) Å , with 2 molecules of Rb+[C24H20B]- in the unit cell. The molecular reorientations as functions of temperature were studied by 1H NMR. Two types of motions were detected: an anisotropic reorientation of the tetraphenylborate anions about their mass centres, and small-angle reorientations / oscillations of the phenyl rings. The dependence of the potential energy of the anion in the crystal on the angle of the phenyl ring rotation about the B-Ph bond was obtained on the basis of atom-atom calculations. The dynamics of this compound was compared to that of tetraphenyltin.

Synthese und Kristallstruktur von [VCl2(15-Krone-5)]+[VOCl4]- / Synthesis and Crystal Structure of [VCl2(15-Crown-5)]+[VOCl4]-

1990 ◽  
Vol 45 (10) ◽  
pp. 1393-1397 ◽  
Author(s):  
Gerlinde Frenzen ◽  
Werner Massa ◽  
Thilo Ernst ◽  
Kurt Dehnicke
Keyword(s):  
Crystal Structure ◽  
Ir Spectroscopy ◽  
Crown Ether ◽  
Single Crystals ◽  
Structure Determination ◽  
Acetonitrile Solution ◽  
Tetragonal Symmetry ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Ether Molecule

[VCl2(15-crown-5)]+[VOCl4]- has been prepared by the reaction of VCl4 with 15-crown-5 in acetonitrile solution in the presence of water, forming black-brown single crystals. They were characterized by IR spectroscopy as well as by an X-ray structure determination. Space group Pnma, Z = 4, 1530 observed unique reflexions, R = 0.052. Lattice dimensions at -120°C: a = 1128.5(4), b = 1063.3(3), c = 1680(1) pm. The compound forms ions, in which the cation contains vanadium(+III), which is seven coordinate by the five oxygen atoms of the crown ether molecule and by two chlorine atoms in axial positions of a pentagonal bipyramide. The [VOCl4]- anion contains vanadium (+V) with approximately tetragonal symmetry

Achievements of multiple-pulse n.m.r

1981 ◽  
Vol 299 (1452) ◽  
pp. 497-504 ◽  
Keyword(s):  
Hydrogen Bonds ◽  
Single Crystals ◽  
Spin Relaxation ◽  
Molecular Motions ◽  
Site Specific ◽  
Multiple Pulse ◽  
Area Of Interest ◽  
Relaxation Measurements ◽  
Powder Samples ◽  
Shielding Tensors

A survey is given of the achievements of multiple-pulse n.m.r. with regard to measurements of shielding tensors of protons. The need to investigate single crystals rather than powder samples is stressed. It is useful to consider separately protons in hydrogen bonds and protons bonded directly to carbon atoms. While for the former group of protons there is now a wealth of experimental shielding data, measurements of shielding tensors of protons from the latter group are still difficult and scarce. Symmetry arguments applied to some available data show that the measurable shielding tensors are substantially influenced by the crystal lattice and do not directly reflect molecular properties. Several implications of this fact are discussed. It is pointed out that continuation of multiple-pulse n.m.r. calls for a new kind of motivation. The study of molecular motions in solids through site-specific spin relaxation measurements may become a new area of interest and activities for multiple-pulse n.m.r.

Dialkylammonium Ion/Crown Ether Complexes: The Forerunners of a New Family of Interlocked Molecules

1995 ◽  
Vol 34 (17) ◽  
pp. 1865-1869 ◽  
Author(s):  
Peter R. Ashton ◽  
Paul J. Campbell ◽  
Peter T. Glink ◽  
Douglas Philp ◽  
Neil Spencer ◽  
...  
Keyword(s):  
Crown Ether ◽  
Interlocked Molecules ◽  
New Family ◽  
Crown Ether Complexes

Solar Internal Rotation and Dynamo Waves: A Two-Dimensional Asymptotic Solution in the Convection Zone

2000 ◽  
Vol 179 ◽  
pp. 379-380
Author(s):  
Gaetano Belvedere ◽  
Kirill Kuzanyan ◽  
Dmitry Sokoloff
Keyword(s):  
Magnetic Field ◽  
Asymptotic Solution ◽  
Internal Rotation ◽  
Convection Zone ◽  
General Idea ◽  
Dynamo Model ◽  
Axially Symmetric ◽  
Dynamo Action ◽  
Regeneration Rate ◽  
Dynamo Waves

Extended abstractHere we outline how asymptotic models may contribute to the investigation of mean field dynamos applied to the solar convective zone. We calculate here a spatial 2-D structure of the mean magnetic field, adopting real profiles of the solar internal rotation (the Ω-effect) and an extended prescription of the turbulent α-effect. In our model assumptions we do not prescribe any meridional flow that might seriously affect the resulting generated magnetic fields. We do not assume apriori any region or layer as a preferred site for the dynamo action (such as the overshoot zone), but the location of the α- and Ω-effects results in the propagation of dynamo waves deep in the convection zone. We consider an axially symmetric magnetic field dynamo model in a differentially rotating spherical shell. The main assumption, when using asymptotic WKB methods, is that the absolute value of the dynamo number (regeneration rate) |D| is large, i.e., the spatial scale of the solution is small. Following the general idea of an asymptotic solution for dynamo waves (e.g., Kuzanyan & Sokoloff 1995), we search for a solution in the form of a power series with respect to the small parameter |D|–1/3(short wavelength scale). This solution is of the order of magnitude of exp(i|D|1/3S), where S is a scalar function of position.

The Microstructure of Shock-Synthesized Diamond

1967 ◽  
Vol 25 ◽  
pp. 324-325
Author(s):  
Lucien F. Trueb
Keyword(s):  
Single Crystals ◽  
Preferred Orientation ◽  
High Magnification ◽  
Texture Pattern ◽  
Shock Process ◽  
New Type ◽  
Diffraction Diagram

A new type of synthetic industrial diamond formed by an explosive shock process has been recently developed by the Du Pont Company. This material consists of a mixture of two basically different forms, as shown in Figure 1: relatively flat and compact aggregates of acicular crystallites, and single crystals in the form of irregular polyhedra with straight edges.Figure 2 is a high magnification micrograph typical for the fibrous aggregates; it shows that they are composed of bundles of crystallites 0.05-0.3 μ long and 0.02 μ. wide. The selected area diffraction diagram (insert in Figure 2) consists of a weak polycrystalline ring pattern and a strong texture pattern with arc reflections. The latter results from crystals having preferred orientation, which shows that in a given particle most fibrils have a similar orientation.

A New Defect in Polyethylene Single Crystals

1973 ◽  
Vol 31 ◽  
pp. 70-71
Author(s):  
E. L. Thomas ◽  
S. L. Sass
Keyword(s):  
Single Crystals ◽  
Screw Dislocation ◽  
Small Distance ◽  
Dipole Model ◽  
Dislocation Dipole ◽  
Chain Folding ◽  
Black And White ◽  
Polymer Crystal ◽  
Different Types

In polyethylene single crystals pairs of black and white lines spaced 700-3,000Å apart, parallel to the [100] and [010] directions, have been identified as microsector boundaries. A microsector is formed when the plane of chain folding changes over a small distance within a polymer crystal. In order for the different types of folds to accommodate at the boundary between the 2 fold domains, a staggering along the chain direction and a rotation of the chains in the plane of the boundary occurs. The black-white contrast from a microsector boundary can be explained in terms of these chain rotations. We demonstrate that microsectors can terminate within the crystal and interpret the observed terminal strain contrast in terms of a screw dislocation dipole model.

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