Search results for "ammonium"

N-Alkyl ammonium resorcinarene salts: multivalent halogen-bonded deep-cavity cavitands

2015

N-Alkyl ammonium resorcinarene salts: multivalent halogen-bonded deep-cavity cavitands

2015

N-Cyclohexyl ammonium resorcinarene halides, stabilized by an intricate array of hydrogen bonds in a cavitand-like assembly, form multivalent halogen-bonded deep-cavity cavitands with perfluoroiodobenzenes. As observed from the macromolar to infinite concentration range through crystal growth and single crystal X-ray analyses, four 1,4-diiodotetrafluorobenzenes form moderate halogen bonds with the bromides of the N-cyclohexyl ammonium resorcinarene bromides leading to a deep-cavity cavitand-like structure. In this assembly, the N-cyclohexyl ammonium resorcinarene bromide also acts as a guest and sits in the upper cavity of the assembly interacting with the 1,4-diiodotetrafluorobenzene throu…

Enrichment of amino acids by supported liquid membrane extraction using Aliquat 336 as a carrier

1998

Abstract The possible application of Aliquat 336 (trioctylmethyl ammonium chloride) as a carrier for liquid membrane extraction of amino acids was investigated. The extraction is performed from an aqueous donor phase with pH > 11 to an acceptor phase containing a salt solution through a supported liquid membrane with Aliquat 336 as a carrier in the membrane to facilitate amino acid transport. Counter-coupled transport of chloride anions from the acceptor phase to the donor phase is the driving force of the mass transfer in this system. The extraction efficiency depends on the donor phase pH, the carrier concentration in the liquid membrane, the composition of the acceptor phase and the hydr…

Ethylammonium hydrogen oxalate–oxalic acid (2/1)

2019

The reaction between ethylamine and oxalic acid in water in a 1:1 molar ratio afforded the title salt, C2H8N+·C2HO4 −·0.5C2H2O4. The hydrogen oxalate anions interact through hydrogen bonding and are organized into a chains propagating along the c-axis direction. The chains are connected to the neighbouring cations and oxalic acid molecules by N—H...O and O—H...O hydrogen bonds and N...O dipole–dipole contacts, leading to a supramolecular three-dimensional network.

Effect of ammonium hydroxide addition in the anodizing electrolyte on the electronic properties of anodic oxides on Niobium

2010

Out-of-phase second harmonic detection as a tool for the determination of relaxation times

2014

Ammoniumnitraatin kidefaasitransitiot

1990

Työ jakautuu laajahkoon kirjalliseen osaan ja kokeelliseen osaan. Kirjallinen osa käsittelee yleisia ammoniumnitraatin valmistukseen ja kemiaan liittyvia seikkoja sekä erityisesti sen seitsemää kiderakennetta. Eri rakenteet ja niiden väliset transitiot esitellään painopisteen ollessa rakenteille tunnusomaisessa dynaamisessa epäjarjestäytymisessä. Eri tutkijoiden antamien ristiriitaisten tietojen pohjalta on hahmotettu kosteuden merkitystä transitioihin. Tärkeimmät keskustelua synnyttäneet erimielisyydet liittyvät kosteuden merkitykseen IV III-transition esiintymiselle. Eri tutkijoiden raporteista syntyy käsitys, että kosteuden määrä ei ole määräävä tekijä, mutta kosteudella selvästikin on m…

Photodegradation of lincomycin in aqueous solution

2006

Aqueous solutions of lincomycin were irradiated with UV light in homogeneous and heterogeneous systems. Lincomycin disappeared in both systems but the presence ofTiO2noticeably accelerated the degradation of the antibiotic in comparison with direct photolysis. The rate of decomposition was dependent on the concentration of lincomycin and followed a pseudo-first-order kinetics. Photolysis involved only the oxidation of lincomycin without mineralization. Differently, the treatment withTiO2and UV light resulted in a complete mineralization of the antibiotic. The degradation pathways involved S- and N-demethylation and propyldealkylation. The mineralization of the molecule led to the formation …

Asymmetric Synthesis of Chiral Bimetallic [Ag28Cu12(SR)24]4– Nanoclusters via Ion Pairing

2016

In this work, a facile ion-pairing strategy for asymmetric synthesis of optically active negatively charged chiral metal nanoparticles using chiral ammonium cations is demonstrated. A new thiolated chiral three-concentric-shell cluster, [Ag28Cu12(SR)24]4–, was first synthesized as a racemic mixture and characterized by single-crystal X-ray structure determination. Mass spectrometric measurements revealed relatively strong ion-pairing interactions between the anionic nanocluster and ammonium cations. Inspired by this observation, the as-prepared racemic mixture was separated into enantiomers by employing chiral quaternary ammonium salts as chiral resolution agents. Subsequently, direct asymm…

Di-, Tri-, and Tetra(pentafluorophenyl) Derivatives for Oligotopic Anion−π Interactions

2013

The present study describes a series of pentafluorobenzyl ammonium salts with two, three, or four C6F5 units in order to investigate simultaneous interactions of several perfluorinated arenes with anions in the crystalline state. Most of the structures show multiple anion-π contacts. However, only 6·2HI reveals an effective encapsulation of the iodide ion by the aromatic units. For comparison, the structure of 4b is investigated because it offers two π-systems with inverse charge distribution to a bromide anion. Only the electron-deficient π-system of the pentafluorophenyl group interacts with the anion.