Search results for "ionic"

Ferrocenyl-functionalized long chain branched polydienes

2009

A convenient two-step approach for the synthesis of ferrocenyl-functionalized long chain branched polydienes, based on both butadiene and isoprene, respectively, is presented. Classical living anionic polymerization was used to synthesize different AB n type poly(diene) macromonomers with moderate molecular weights between 1700 and 3200 g/mol and narrow polydispersity. Quantitative end-capping with chlorodimethylsilane resulted in the desired AB n macromonomer structures. In the ensuing Pt-catalyzed hydrosilylation polyaddition, branched, functionalized polydienes were obtained by a concurrent AB n + AR type of copolymerization with mono-and difunctional ferrocenyl silanes (fcSiMe 2 H or fc…

Molecular “Floppyness” and the Lewis Acidity of Silanes: A Density Functional Theory Study

2001

A comprehensive set of Lewis acid-base adducts of silanes was investigated by means of the density functional theory geometry optimization [B3LYP/6−31G(d)], and thermochemical calculations, [B3LYP/6−311+G(2d,p)//B3LYP/6−31G(d)]. Complex formation was found to weaken Si−Cl and Si−Br bonds more than Si−F or Si−H bonds. Comparable distances between Si and a Lewis base L (L = NH3, OH2, F−) are shorter in hexa- than in pentacoordinated complexes. The molecular structures of the pentacoordinated Si complexes allowed for a mapping of an SN2 reaction pathway by correlating the lengths of the Si−X and Si−L bonds. Complex formation was found to be exothermic for most of the coordination compounds, an…

FT-IR and dielectric study of water/AOT liquid crystals

2000

Abstract In order to explore the influence of microwave radiation on highly viscous microheterogeneous systems, the evolution of structural and dynamical properties of the water/sodium bis(2-ethylhexyl) sulfosuccinate (AOT) liquid crystals as a function of the molar ratio R (R=[water]/[AOT]) has been investigated by FT-IR spectroscopy and time domain reflectometry. The study emphasises how the progressive hydration of the surfactant head groups is mainly responsible for the structural and dynamical evolution of water/AOT liquid crystals. In particular, it has been found that the state of water at lower R values is strongly perturbed, bulk-like water appears only at R>23 and the water/AOT in…

1971

The anionic polymerization of β-propiolactone at 25°C in ethanol initiated by the betain was investigated. Macrozwitterions of the structure were produced, n being intentionally as low as ca. 11. The structure of the product was proven by the nitrogen content of the reprecipiated polymer, by IR and NMR spectroscopy and by titration of the carboxylate endgroups. Some carboxylic acid endgroups were formed by chain transfer with the solvent ethanol. The positive charge at the polymer chain was proven by electrophoresis of polymer after esterification of the carboxylate chain end. Furthermore the dielectric constant of dilute solutions of the polymer in CHCl3 was determined and is discussed. Th…

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…

Study of silica-structured materials as sorbents for organophosphorus pesticides determination in environmental water samples

2018

Abstract A novel sorbent based on a UVM-7 mesoporous silica doped with Ti has been synthesized and used for solid-phase extraction of several organophosphorus pesticides in environmental water samples followed by gas chromatography coupled to a nitrogen-phosphorus selective detector. Thus, mesoporous silica materials doped with Ti and Fe as well as immobilized cyclodextrin silica-based supports were prepared and morphologically characterized by several techniques such as transmission electronic microscopy, nitrogen adsorption-desorption and X-ray diffraction. These sorbents were comparatively evaluated, and Ti25-UVM-7 material was selected as the best solid phase. After optimization of extr…

Insertion of One, Two, and Three Molecules of Alkyne into the Pd−C Bond of Ortho-palladated Primary and Secondary Arylalkylamines

2009

The ortho-metalated complex [Pd2{κ2(C,N)-C6H4CH2CH2NHMe-2}2(μ-Br)2] (1) can be prepared by refluxing a 1:1 mixture of Pd(OAc)2 and N-methylphenethylamine in acetonitrile, followed by addition of an excess of NaBr. Complex 1 reacts with PPh3 to give the mononuclear derivative [Pd{κ2(C,N)-C6H4CH2CH2NHMe-2}Br(PPh3)] (2). The cationic complex [Pd{κ2(C,N)-C6H4CH2CH2NHMe-2}(py)2]ClO4 (3) can be obtained by reacting 1 with AgClO4 and pyridine. The previously reported complex [Pd2{κ2(C,N)-C6H4CH2NHCH2Ph-2}2(μ-Br)2] (A) reacts with PhC≡CCO2R (R = Me, Et) to give the monoinserted derivatives [Pd2{κ2(C,N)-C(Ph)═C(CO2R)C6H4CH2NHCH2Ph-2}2(μ-Br)2] (R = Me (4a), Et (4b)). These dimers react with neutral l…

Cation-π interactions between neutral calix[5]arene hosts and cationic organic guests

1997

Abstract The binding properties of the 1,3-bridged calix[5]crowns 1–3 towards a number of quaternary ammonium, phosphonium, and iminium ions have been investigated by 1H NMR in CDCl3 solution, where the sole driving force for association is provided by cation-π interactions. We have found that the cavity of a calix[5]arene fixed in a cone-like conformation provides a fairly efficient, but rather unselective, receptor site for quaternary salts. The conformationally mobile p-tert-butylcalix[5]arene (4) is in general a much less efficient binder than the more preorganized calixcrowns, but displays a remarkable selectivity towards N-methylquinuclidinium ion that is believed to arise from a good…

Effect of ionic liquid organizing ability and amine structure on the rate and mechanism of base induced elimination of 1,1,1-tribromo-2,2-bis(phenyl-…

2006

Abstract The kinetics of the elimination reaction of 1,1,1-tribromo-2,2-bis(phenyl-substituted)ethanes into the corresponding 1,1-dibromo-2,2-bis(phenyl-substituted)ethenes induced by amines were studied in three room temperature ionic liquids ([BMIM][BF 4 ], [BMIM][PF 6 ], [BdMIM][BF 4 ]). In order to have information about reagent–ionic liquid interactions, the reaction was carried out over the temperature range (293.1–313.1 K). To study the effect of the amine on the rate and occurrence of the elimination reaction, several primary, secondary and tertiary amines with different structure (cyclic and acyclic), basicity and steric requirements were used. The data collected show that the reac…

Sterically controlled self-assembly of tetrahedral M(6)L(4) cages via cationic N-donor ligands.

2014

Tripodal cationic N-donor ligands exhibit sterically controlled self-assembly of tetrahedral M6L4 coordination cages that promote selective anion encapsulation (PF6(-)OTf(-)) in the solid state. The described method is a potential template for stepwise assembly of hetero-ligand coordination cages and polymers.