Search results for "Ionic bonding"
showing 10 items of 480 documents
Post-Processing via Cation Exchange Cartridges: Versatile Options
2012
New 68Ge/68Ga radionuclide generators provide the positron emitter 68Ga (T½ = 67.7 min) as an easily available and relatively inexpensive source of a PET nuclide for labeling of interesting targeting vectors. However, currently available “ionic” 68Ge/68Ga radionuclide generators are not necessarily optimized for the routine synthesis of 68Ga-labeled radiopharmaceuticals in a clinical environment. Post-processing of 68Ge/68Ga generators using cation exchange resins provides chemically and radiochemically pure 68Ga with 97±2% within less than 4 min, with 68Ge almost completely removed, and ready for online labeling. This simple, fast, and efficient technology can be extended for new applicati…
Homogeneous mixtures of polybetaines with low molecular weight salts
1996
The prepaparation of amorphous, homogeneous blends of zwitterionic polymers with various low molecular weight salts, and in particular with ionic dyes was studied. Homogeneous miscibility was achieved in many cases up to equimolar amounts of salt, even for bulky compounds. Whether miscibility is achieved, or not, depends in a subtle way on the chemical structure of the salt, but no obvious correlation between structure and miscibility could yet be revealed. Spectral shifts of the dye UV/Vis spectra in solution as well as in bulk suggest strong interactions between the polybetaines and the admired salts.
Anomalous Kinetics of Diffusion-Controlled Defect Annealing in Irradiated Ionic Solids
2017
The authors thanks A. Ch. Lushchik, M. Izerrouken, and V. Lisitsyn for stimulating discussions. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euroatom research and training programme 2014-2018 under Grant Agreement No. 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. R.V. acknowledges the financial support by the MEIC (Ministerio de Economa, Industria y Competitivad; Project ENE2015-70300-C3-1-R). The calculations were performed using facilities of the Stuttgart Supercomputer Center (Project DEFTD 12939).
Estimation of Solute-Stationary Phase and Solute-Mobile Phase Interactions in the Presence of Ionic Liquids
2019
The presence of free silanols on alkyl-bonded reversed-phase stationary phases is responsible for broad and asymmetrical peaks when basic drugs are chromatographed with conventional octadecylsilane (C18) columns due to ionic interactions. In the last few years, ionic liquids (ILs) have attracted attention to reduce this undesirable silanol activity. ILs should be considered as dual modifiers (with a cationic and anionic character), which means that both cations and anions are able to adsorb on the stationary phase, creating a positively or negatively charged layer, depending on the relative adsorption. The accessibility of basic compounds to the silanols is prevented by both the IL cation a…
Crystal structure of [tris(4,4-bipyridine)]diium bis(1,1,3,3-tetracyano-2-ethoxypropenide) trihydrate
2016
In the title hydrated salt, which was obtained from the hydrothermal reaction between between potassium 1,1,3,3-tetracyano-2-ethoxypropenide and 4,4′-bipyridine in the presence of iron(II) sulfate heptahydrate, the ionic components are linked into a three-dimensional network by C—H⋯N hydrogen bonds.
Structure and dynamics of dibutylphosphate/n-propylamine ionic liquid: A multi-scale theoretical study
2021
Abstract Owing to the amphiphilic nature of their constituent molecules, binary mixtures of pure liquid surfactants are usually characterized by enhanced nano-segregation and thus can exhibit interesting transport properties and complex macroscopic behavior. In this ambit it was recently shown by Turco Liveri et al. (2018) that mixtures of short aliphatic chains compounds at room temperature, such as dibutyl phosphate (DBP) and n-propylamine (PA) liquids, display ionic liquid–like behavior ascribed to phosphate-to-amine proton transfer. To gain a detailed molecular picture of the system structure and dynamics and to understand the molecular mechanisms at the basis of the observed behavior, …
Thermometric study of the dissociation equilibria of the maleinimidodioxime
1982
The values of the dissociation constants of the maleinimidodioxime are potentiometrically determined at various ionic strengths, and extrapolated to zero ionic strength (pK1T=10.41;pk2T=11.60). From these values and from the thermometric titration curves the enthalpies of neutralization (ΔHN1=−21.76,ΔHN2=−23.77 kJ/mol) and the thermodynamic parameters of dissociation of this substance at 25.0 °C are determined (ΔG1θ=59.41,ΔG2θ=66.23,ΔH1θ=34.06,ΔH2θ=32.05 kJ/mol;ΔS1θ=−85.06,ΔS2θ=−114.64 J/(K mol)).
Green Light-Emitting Solid-State Electrochemical Cell Obtained from a Homoleptic Iridium(III) Complex Containing Ionically Charged Ligands
2006
An efficient bluish-green light-emitting Ir(III) complex was prepared by introducing charged side groups onto phenylpyridine ligands. Green light emission with a first maximum at 487 nm (CIE coordinates x = 0.337 and y = 0.501) was observed from a single layer light-emitting electrochemical cell using this new complex; this is the lowest wavelength observed so far for devices based on ionic transition metal complexes.
<title>Functional models of electrochromic devices: cycling capacity and degradation</title>
1997
Electrical transfer and diffusion of ions and the irreversibility of ion and electron processes in heterojunctions are responsible for degradation of ionic devices. These processes for electrochromic devices (ECD) determine the cycling capacity and lifetime. The basic problem here is how to match the electrochemical parameters (including chemical potential) of heterojunction. The experiments had been carried out on ECD based on system: (phi) - -(phi) , where AAH is solid electrolyte based on antimony acid hydrates. The cycling capacity and degradation processes of ECD are investigated by electro-optical and electro-chemical spectroscopy. The analysis of experimental data are based on assump…
ChemInform Abstract: Modified Photobehavior of Carboxylic Acid Derivatives Induced by Protonation.
1987
Abstract A series of carboxylic acid derivatives 1–6 containing a second interacting function have been converted into the corresponding O -protonated species or acylium ions upon treatment with 96% sulfuric acid or oleum, respectively, at room temperature. The resulting stable cations have been spectroscopically characterized and submitted to irradiation. Cis-trans photoisomerization was observed in the ionic speciesderived from trans -crotonic, fumaric and maleic acids, and maleic anhydride. By contrast protonated crotonolactone 5a+ was found to be photostable. Finally, protonated α-bromobutyrolactone 6a+ was clean and efficiently dehydrohalogenated to 5a+ upon irradiation. Since the norm…