Search results for "ionic"

A mesoscopic approach to radiation-induced defect aggregation in alkali halides stimulated by the elastic interaction of mobile Frenkel defects

1994

The radiation-induced aggregation of Frenkel defects in alkali halides is studied in terms of a mesoscopic approach. The asymmetry in elastic interactions between mobile interstitials (I–I) and bet...

Emerging Evidences of Mesoscopic-Scale Complexity in Neat Ionic Liquids and Their Mixtures

2017

Ionic liquids (ILs) represent a blooming class of continuously developing advanced materials, with the aiming of a green chemical industry. Their appealing physical and chemical properties are largely influenced by their micro- and mesoscopic structure that is known to possess a high degree of hierarchical organization. High-impact application fields are largely affected by the complex morphology of neat ionic liquids and their mixtures. This Perspective highlights new arising research directions that point to an enhanced level of structural complexity in several IL-based systems, including mixtures. The latter represent a change in paradigm in the approach to formulate new, task-specific I…

Pressure-responsive mesoscopic structures in room temperature ionic liquids

2015

Among the most spectacular peculiarities of room temperature ionic liquids, their mesoscopically segregated structural organization keeps on attracting attention, due to its major consequences for the bulk macroscopic properties. Herein we use molecular dynamics simulations to explore the nm-scale architecture in 1-octyl-3-methylimidazolium tetrafluoroborate, as a function of pressure. This study reveals an intriguing new feature: the mesoscopic segregation in ionic liquids is characterized by a high level of pressure-responsiveness, which progressively vanishes upon application of high enough pressure. These results are in agreement with recent X-ray scattering data and are interpreted in …

Immunoassays for trifloxystrobin analysis. Part II. Assay development and application to residue determination in food.

2014

Immunochemical assays constitute complementary analytical methods for small organic molecule determination. We herein describe the characterisation and optimisation of two competitive enzyme-linked immunosorbent assays in different formats using monoclonal antibodies to the Quinone outside inhibitor (QoI) fungicide trifloxystrobin. Antibody selectivity was evaluated using a variety of agrochemicals and the main trifloxystrobin metabolite. Acceptable tolerance of the immunoassay to methanol, ethanol, and acetonitrile was observed in all cases, whereas a dissimilar influence of buffer pH and ionic strength was found. Moreover, the influence of Tween 20 over the analytical parameters was studi…

Secondary chemical equilibria in reversed-phase liquid chromatography

2017

Abstract The addition of reagents to a reversed-phase liquid chromatography (RPLC) mobile phase enables the separation of ionizable compounds, inorganic anions, and metal ions, using conventional instrumentation, silica-based materials, and hydro-organic mixtures, thanks to a variety of secondary equilibria. This gives rise to several chromatographic modes, the main features of which are outlined in this chapter. The effect of the mobile phase pH on the retention of ionizable compounds is described, together with the recommended experimental practice. The mechanism of adsorption of amphiphilic anions or cations on the stationary phase to attract analytes with opposite charge, or suppress th…

Assignment of complex species by affinity capillary electrophoresis: The case of Th(IV)‐desferrioxamine B

2020

International audience; The electrophoretic mobility change of desferrioxamine B (DFO) was monitored by UV absorption spectrophotometry upon increasing the thorium(IV) concentration in the background electrolyte at two acidities ([HClO4]Tot = 0.0316 and 0.0100 M). These data enabled to assess the speciation model and to determine the equilibrium constant of [Th(DFO)H2]3+ at fixed ionic strength (I = 0.1 M (H,Na)ClO4). Affinity capillary electrophoresis (ACE) turned out to be most helpful in identifying the complexed species by ascertaining its charge and protonation state. The assignment of the correct stoichiometry relied on the reliable estimation of the electrophoretic mobility by assumi…

Quantitative parameters for the sequestering capacity of polyacrilates towards alkaline earth metal ions

2002

The complex formation constants of polyacrylic (PAA) ligands (1.4</=logN</=2.4, N=number of monomer units) with calcium and magnesium ions were determined in different ionic media at different ionic strengths, 0</=I</=1 mol l(-1), at t=25 degrees C. Experimental pH-metric data in the presence of Ca(2+) or Mg(2+) were firstly analysed in terms of apparent protonation constants, logK(H*), using the "three parameter model" proposed by Hogfeldt; differences in logK(H*), determined in different ionic media, were interpreted in terms of complex species formation. The only species present in the system M-PAA (M=Ca(2+) or Mg(2+)) is ML(2): attempts to find species of different stoichiometry were un…

THE KINETICS OF RADIATION-INDUCED POINT DEFECT AGGREGATION AND METALLIC COLLOID FORMATION IN IONIC SOLIDS

2007

Discrete-lattice theory for Frenkel-defect aggregation in irradiated ionic solids

1998

Institut fu ¨r Physikalische und Theoretische Chemie, Technische Universitat Braunschweig, D-38106 Braunschweig, Germany~Received 11 September 1997; revised manuscript received 6 April 1998!A microscopic theory of diffusion-controlled aggregation of radiation Frenkel defects—called in ionic solidsH and F centers—is presented. This is based on a discrete-lattice formalism for the single defect densities~concentrations! and the coupled joint densities of similar and dissimilar defects treated in terms of a modifiedKirkwood superposition approximation. The kinetics of defect aggregation is studied in detail; the cooperativecharacter of this process for both types of complementary defects is sho…

Preparation of Polymer-Supported Polyazamacrocycles. The Role of the Polymeric Matrix in the Preparation of Polymer-Supported Polyazamacrocycles

2000

Different approaches have been studied for the preparation of resins containing different polyazamacrocycles. Preparation of monolithic resins by polymerization of vinylic derivatives of the corresponding macrocycles is shown to be a more versatile strategy for this purpose. The use of energy-dispersive analysis by X-ray has revealed to be a very useful tool for the rapid evaluation of the interaction of those materials with both anions and cations and has allowed the corresponding selectivity trends to be obtained in a fast and simple way. Important effects of the polymeric matrix are observed in some cases.