Search results for "salt"
showing 10 items of 1157 documents
Charge Transfer Salts Based on Polyoxometalates and Seleno-Substituted Organic Donors. Synthesis, Structure, and Magnetic Properties of (BEST)3H[PMo1…
1998
Electrochemical oxidation of the tetrathiafulvalene (TTF) type organic donor bis(ethylenediseleno)tetrathiafulvalene (BEST) in the presence of the Keggin polyoxometalate [PMo12O40]3- affords the radical salt formulated as (BEST)3H[PMo12O40] (crystal data: triclinic, space group P1 with a = 13.056(1) A, b = 13.957(1) A, c = 22.302(3) A, α = 97.019(9)°, β = 94.17(1)°, γ = 95.847(9)°, and Z = 2). This is the first salt of a selenium-containing donor with a polyoxometalate cluster. The structure of this organic/inorganic hybrid consists of layers of the organic donors that alternate with polyoxometalate layers in the c direction. The organic molecules, which are completely ionized, form two ty…
An approximate theoretical impedance analysis of the anodic dissolution of nickel across nickel(II) stabilised by means of competitive anions
2007
Abstract A theoretical impedance function for the anodic dissolution of nickel is developed by considering the hypothesis that there are two competitive anions which participate in the stabilization of the electrogenerated Ni(II) species. The experimental effect of chloride ion concentration on nickel electrodissolution process is analyzed by means of a mechanism that considers this competency. It is observed that an increased Cl − concentration causes an increase in Ni(I) surface concentration and a decrease in the kinetic constant rates of the considered mechanism. Moreover, an increased chloride concentration causes a flattening in the low frequencies inductive loop in the Nyquist plot r…
Effects of ions on water structure: a low-field1HT1NMR relaxometry approach
2014
Aqueous salt solutions play an important role in nature because of their effects on environmental biogeochemical processes and on structural properties of biomolecules. Upon dissolution, salts split in ions that are solvated. Water in hydration shells is subjected to molecular motions that can be monitored by (1)H T1 NMR relaxometry. This technique allowed the evaluation of the nature of the interactions between water and ions via variable temperature experiments. Examination of relaxometry properties of aqueous solutions at variable salt concentrations allowed acknowledgement of the role played by ions in either structuring or destructuring water aggregates. A mathematical model has been a…
Use of reversed-phase C18 Sep-Pak cartridges for the purification and concentration of sepiapterin and other pteridines
1985
Abstract Several pteridines have been tested for their ability to bind to C 18 Sep-Pak. Riboflavin, sepiapterin, deoxysepiapterin, 6-acetyl-7,8-dihydropterin, 6-acetyldihydrohomopterin and 3′-hydroxysepiapterin were strongly retained and all but 6-acetyldihydrohomopterin quantitatively recovered upon elution with 2 ml of methanol. The effect of the concentration and volume of the sample, pH and salt concentration on the retention of sepiapterin have been studied. The procedure was very useful for the purification, desalting, solvent exchange and concentration of pteridines having high affinity for the cartridge. C 18 Sep-Pak has been applied succesfully to sample clean-up prior to high-perf…
Carbon-based ionic liquid gels: alternative adsorbents for pharmaceutically active compounds in wastewater
2021
With the aim of obtaining adsorbent systems to be used for the removal of pharmaceutically active compounds (PhACs) from wastewater, some hybrid ionic liquid gels (HILGs) were obtained from the combination of ionic liquid-based supramolecular gels and carbon materials, like graphite, graphene and graphene oxide (graphene OX). The properties of HILGs were investigated by determining their gel–sol transition temperature and rheological features. They were tested for the removal of PhACs belonging to different pharmaceutical classes, like antibiotics, antidepressants, anti-inflammatory. In particular, the removal of carbamazepine (CBZ), diclofenac sodium salt (DCF), ciprofloxacin (CPX) and nal…
Rapid characterization of alkylpolyphosphonates by CZE with indirect photometric and mass spectrometric detection.
2006
Methods for the rapid characterization of industrial alkylpolyphosphonates (APPs) by infusion MS and CZE with indirect photometric (IPD) and MS detection are described. Technical-grade APPs, including alkylaminepolyphosphonates with 3-5 phosphonate groups and different hydrocarbon skeletons, hydroxyethyl-amino-bis(methylenephosphonic acid), hydroxyethylidene-diphosphonic acid, and 2-phosphonobutane-1,2,4-tricarboxylic acid, were examined. A 10 mM solution of adenosine triphosphate disodium salt at pH 2.2 was used as BGE. The nominal compounds of the industrial APPs and their impurities were well resolved in less than 15 min. The peaks were identified by using extracted ion electropherograms…
Intramolecularly Coordinated Bis(crown ether)-Substituted Organotin Halides as Ditopic Salt Receptors
2013
The synthesis of the bis(crown ether)-substituted organostannanes X2Sn(CH2-[16]-crown-5)2 (3, X = I; 4, X = Br; 5, X = Cl; 6, X = F) and X2Sn(CH2-[13]-crown-4)2 (10, X = I; 11, X = Br; 12, X = F) is reported. The compounds have been characterized by 1H, 13C, 19F, and 119Sn NMR spectroscopy, elemental analyses, and electrospray ionization mass spectrometry (ESI-MS). Single-crystal X-ray diffraction analyses reveal a distorted-octahedral cis,cis,trans configuration of the tin atoms in compounds 4–6 and 10–12 as a result of intramolecular O→Sn coordination. The ability of the host molecules to form mono- and ditopic complexes with various halide salts in different solvents, including water, ha…
Effect of Protonated Organic Cations and Anion−π Interactions on the Magnetic Behavior of Hexabromorhenate(IV) Salts
2015
Two novel Re-IV compounds of formula (Hbpym)(2)[(ReBr6)-Br-IV]center dot 4H(2)O (1) and (H(4)biim)[(ReBr6)-Br-IV]center dot 4H(2)O (2) [Hbpym(+) = 2,2'-bipyrimidinium cation and H(4)biim(2+) = 2,2'-biimidazolium dication] have been prepared and magnetostructurally characterized. 1 and 2 exhibit distinct crystal packing, and the presence of weak intermolecular contacts, such as Re-Br...B-rRe (1 and 2), Re-Br center dot center dot center dot(H2O)center dot center dot center dot BrRe (1 and 2), and Re-Br center dot center dot center dot pi center dot center dot center dot Br-Re (2), lead to different magnetic behaviors. While 1 is antiferromagnetic, 2 is a ferromagnetic compound and indeed the…
Radical cation salts based on BEDT-TTF and the paramagnetic anion [Cr(NCS)6]3−
1999
Abstract A new radical cation salt formulated as (ET)5.5[Cr(NCS)6] (ET = BEDT-TTF = bis(ethylene)dithiotetrathiafulvalene) has been synthesised and characterised by X-ray diffraction and magnetic measurements. The structure shows the presence of alternating layers of the ET units and mixed layers of anions and an isolated ET molecule. The magnetic susceptibility data in the temperature range 2–300 K show a Curie law with C = 1.771 cm3.K.mol−1 and Nα = 1.20.10−5 cm3.mol−1, in agreement with the presence of isolated Cr(III) without any contribution from the organic part.
NonclassicalPschorr andSandmeyer Reactions in Pyrazole Series
2005
The diazonium salt derived from 4-amino-N,1,3-trimethyl-N-(3-methyl-1-phenyl-1H-pyrazol-5-yl)-1H-pyrazole-5-carboxamide (14) was reacted with a mixture of CuSO4 and NaCl, with ascorbic acid as an initiator to afford the planar derivative 4,6-dihydro-1,4,6,8-tetramethyl-3-phenyldipyrazolo[3,4-b:4′,3′-d]pyridin-5(3H)-one (16) and its unexpected isomer 4,6-dihydro-3,4,6,8-tetramethyl-1-phenyldipyrazolo[4,3-b:4′,3′-d]pyridin-5(1H)-one (17), as well as the epimers (3S,4S)- (or (3S,4R)-) and (3S,4R)- (or (3S,4S)-) 4-chloro-2,4-dihydro-1′,3′,5,5′-tetramethyl-2-phenylspiro[pyrazole-3,4′(1′H)-pyrrolo[3,4-c]pyrazol]-6′(5′H)-one (18a and b, respectively). Epimers 18a and b were converted under basic c…