Automated Analysis and Simulation of NMR Spectra: Applications to Organo Phosphorus Chemistry

Abstract

Analysis of molecular structures in solution- and liquid-state is based on modern NMR methods. A novel set of computer programs was developed which allows for a more convenient automated analysis of NMR parameters and subsequent simulation of NMR spectra. Programs and techniques used are demonstrated for model systems like:     

Planar Chiral and Achiral Arenido(triphenylphosphane)nickel(II) Complexes Containing N,O Bidentate Ligands: 19F, 1H,and 31P NMR Studies

Abstract

Planar chiral and achiral arenido(triphenylphosphane)nickel(II) complexes (arenido = mesitylenido, 2-toluenido) comprising electronically delocalised N,O chelating ligands were studied by ¹H and ¹⁹F NMR using 1D and 2D techniques. Results from complexes and corresponding ligands are discussed in the light of molecular structures obtained from X-ray diffraction.

GRAPHICAL ABSTRACT      

Columnar liquid crystals derived from ester-substituted tetraphenylenes

We report the synthesis and liquid crystalline properties of novel ester-substituted tetraphenylenes obtained from octamethoxytetraphenylene by demethylation and esterification. The target compounds display focal-conic textures typical for columnar mesophases, which are either rectangular or hexagonal columnar in nature, depending on the alkyl chain length.     

Ionen-chromatographische Analyse anorganischer und organischer Komplexbildner

Summary Inorganic and organic complexing agents like polyphosphates, aminopolycarboxylic acids (NTA, EDTA, DTPA), aminopolyphosphonic acids (NTP, EDTP, DTPP), polyphosphonic and polyphosphinic acids can be separated by means of ion chromatography utilizing a pellicular low capacity anion-exchange resin. Detection is carried out via post-column derivatisation of the column effluent with iron(III) nitrate and UV-detection of the metal complexes at 330 nm. Estimated detection limits for all the compounds investigated are in the lowest ppm-range and can be pushed even lower by use of concentrator columns. The separation and detection system described here, is suitable to separate and determine polyphosphonic and polyphosphinic acids in complex mixtures (reaction control) as well as to investigate the purity of single components (product control). The retention behaviour of a selected group of phosphonic and phosphinic acids has been investigated.     

Strong Averaging Along Foliated Lévy Diffusions with Heavy Tails on Compact Leaves

This article shows a strong averaging principle for diffusions driven by discontinuous heavy-tailed Lévy noise, which are invariant on the compact horizontal leaves of a foliated manifold subject to small transversal random perturbations. We extend a result for such diffusions with exponential moments and bounded, deterministic perturbations to diffusions with polynomial moments of order \(p\geqslant 2\), perturbed by deterministic and stochastic integrals with unbounded coefficients and polynomial moments. The main argument relies on a result of the dynamical system for each individual jump increments of the corresponding canonical Marcus equation. The example of Lévy rotations on the unit circle subject to perturbations by a planar Lévy-Ornstein-Uhlenbeck process is carried out in detail.     

In vivo observation of oxygen-supersaturated water in the human mouth and stomach

In recent years, a rising number of different table waters supersaturated with oxygen have hit the market with claims of both positive health effects and an increase in athletic performance. A scientific validation of these claims needs additional knowledge on the fate of the oxygen supersaturation in the human digestive tract. Taking advantage of the fact that molecular oxygen is paramagnetic, MRI can be applied to observe the behavior of oxygen-supersaturated water after oral uptake. In this contribution we report results obtained on several healthy volunteers. On the basis of these results we can conclude that oral uptake of oxygen-supersaturated drinking water with a low content in CO(2) leads to a considerable increase in the oxygenation in the lumen of the oral cavity and of the stomach. Comparing the observed contrast changes with those brought about by conventional contrast agents, even the highly oxygen-supersaturated waters still perform rather poorly.     

Diffusion, sedimentation, and rheology of concentrated suspensions of core-shell particles

Short-time dynamic properties of concentrated suspensions of colloidal core-shell particles are studied using a precise force multipole method which accounts for many-particle hydrodynamic interactions. A core-shell particle is composed of a rigid, spherical dry core of radius a surrounded by a uniformly permeable shell of outer radius b and hydrodynamic penetration depth κ(-1). The solvent flow inside the permeable shell is described by the Brinkman-Debye-Bueche equation, and outside the particles by the Stokes equation. The particles are assumed to interact non-hydrodynamically by a hard-sphere no-overlap potential of radius b. Numerical results are presented for the high-frequency shear viscosity, η(∞), sedimentation coefficient, K, and the short-time translational and rotational self-diffusion coefficients, D(t) and D(r). The simulation results cover the full three-parametric fluid-phase space of the composite particle model, with the volume fraction extending up to 0.45, and the whole range of values for κb, and a/b. Many-particle hydrodynamic interaction effects on the transport properties are explored, and the hydrodynamic influence of the core in concentrated systems is discussed. Our simulation results show that for thin or hardly permeable shells, the core-shell systems can be approximated neither by no-shell nor by no-core models. However, one of our findings is that for κ(b - a) ? 5, the core is practically not sensed any more by the weakly penetrating fluid. This result is explained using an asymptotic analysis of the scattering coefficients entering into the multipole method of solving the Stokes equations. We show that in most cases, the influence of the core grows only weakly with increasing concentration.