Search results for "Ionic"

Synthetic approaches towards new polymer systems by the combination of living carbocationic and anionic polymerizations

1996

This study summarizes recent efforts to obtain by combination of living carbocationic and anionic polymerizations block copolymers which are potential precursors for building new well-defined polymeric architectures with microphase separated morphology. Living carbocationic polymerization (LCCP) yields telechelic polyisobutylene (PIB) chains with a variety of useful endgroups, such as tert-chlorine, isopropenyl, primary hydroxyl, tolyl etc. When tolyl-ended PIB was used as precursor for macroinitiator of living anionic polymerization of 2-(tert-butyldimethylsilyloxy)ethyl methacrylate (tBuMe2SiOEMA), mixtures of homopolymers and block copolymers were formed due to incomplete lithiation of t…

Layer-by-layer deposited multilayer assemblies of polyelectrolytes and proteins: from ultrathin films to protein arrays

2008

We have recently introduced a new method of creating ultrathin films of polyelectrolytes based on the electrostatic attraction between opposite charges. Multilayer assemblies are adsorbed in a layer-by-layer fashion from aqueous solutions of the polymers. The total film thickness can easily be adjusted by varying the ionic strength of the solution. Here, we report on the temperature stability and the water content of the multilayer assemblies. Furthermore, we have extended our concept to the incorporation of protein layers into films of synthetic polyelectrolytes. The well established system biotin/streptavidin was used to construct such multilayers, also by biospecific recognition. Adsorpt…

1976

A number of acryl and methacryl derivatives of different sulfanilamides (1a—I) were prepared and polymerized. The fixation of the sulfonamide to the polymerizable group was carried out directly, using the acryl- and methacrylamides, and by means of spacer groups, to favour the enzymatic or hydrolytic release of the drug moiety. Selected sulfonamide types of different pKA values were used, and the pH-dependant solubility of the corresponding polymers was studied. The monomeric acryloyl and methacryloyl sulfonamides were homopolymerized radically by AIBN. For distribution studies polysulfadiazineacrylamide, 14C-labelled in the main chain (2e'), was synthesized. Copolymerization with 2-methyls…

1991

The polysoaps [CH 2 C(Me)(CO 2 R)] n (R=(CH 2 ) 11 N + Me 2 (CH 2 ) 3 SO 3 − , (CH 2 ) 11 N + Me 2 CH 2 CH 2 OH) are studied. Their aqueous solution properties are strongly influenced by added salts; the surface activity can be modified efficiently by an appropriate choice of ions. The interactions of salts and polyzwitterions observed in solution can be extended to the behaviour in bulk. It enables the preparation of uniform, non crystalline blends containing up to equivalent amounts of inorganic salt and polyzwitterions

Salt effects on the protonation of l-histidine and l-aspartic acid: a complex formation model

1991

Abstract Protonation constants of l -histidine (histidinate: his − ) and l -aspartic acid (aspartate: asp 2− ) were determined potentiometrically, using the (H + ) glass electrode, in aqueous tetraethylammonium iodide (Et 4 NI), calcium chloride and sodium chloride solutions, at 0 −3 and 10 ⩽, T ⩽, 45 ° C. Differences in protonation constants determined in different salt media were explained by a complex formation model and, according to this model, the presence of the following species was hypothesized: Ca(his) + , CaH(his) 2+ , CaH 2 (his) 3+ Na(his) 0 , H 3 (his)X + , H 2 (his)X 0 , Et 4 N(his) 0 , Et 4 NH(his) + , Ca(asp) 0 , CaH(asp) + , CaH 2 (asp) 2+ , Na(asp) − , NaH(asp) 0 , H 3 (a…

A magnetic self-contained thermochromic system with convenient temperature range

2019

A new ionic liquid with sugar-based ligand has been prepared and used to coordinate cobalt(II), at low loading, in an ionic liquid solution. The system obtained reveals magnetic switching and marked thermochromism in solution/polymer films over a convenient temperature range (20–60 °C). This system is self-contained, devoid of any volatile substances, and reproducible over multiple thermal cycles. The colour change can be attributed to a change in the coordination geometry from octahedral (pink) at room temperature to tetrahedral (blue) on warming, monitored by 59Co NMR spectroscopy, which was used for the first time to study the change. This material may find applications in stimuli-respon…

ChemInform Abstract: Eco-Friendly Functionalization of Natural Halloysite Clay Nanotube with Ionic Liquids by Microwave Irradiation for Suzuki Coupli…

2014

Abstract Microwave assisted halloysite (HNT) external surface functionalization with ionic liquids is described. HNTs modification was achieved in two steps: a) grafting of 3-mercaptopropyl trimethoxysilane on the external surface of HNT by a microwave irradiation; b) anchorage of vinylimidazolium ionic liquids by a thiol-ene reaction. MW irradiation allowed us to obtain high loading onto the HNT surface compared to those obtained through conventional synthesis. Fourier transform infrared spectroscopy and thermogravimetric analysis confirmed that the grafting has occurred only on the external surface of HNT. Turbidimetric and dynamic light scattering analyses showed that the introduction of…

Eco-friendly functionalization of natural halloysite clay nanotube with ionic liquids by microwave irradiation for Suzuki coupling reaction

2014

Abstract Microwave assisted halloysite (HNT) external surface functionalization with ionic liquids is described. HNTs modification was achieved in two steps: a) grafting of 3-mercaptopropyl trimethoxysilane on the external surface of HNT by a microwave irradiation; b) anchorage of vinylimidazolium ionic liquids by a thiol-ene reaction. MW irradiation allowed us to obtain high loading onto the HNT surface compared to those obtained through conventional synthesis. Fourier transform infrared spectroscopy and thermogravimetric analysis confirmed that the grafting has occurred only on the external surface of HNT. Turbidimetric and dynamic light scattering analyses showed that the introduction of…

Heterogeneous oxidation of pyrimidine and alkyl thioethers in ionic liquids over mesoporous Ti or Ti/Ge catalysts.

2004

Heterogeneous catalytic oxidation of a series of thioethers (2-thiomethylpyrimidine, 2-thiomethyl-4,6-dimethyl-pyrimidine, 2-thiobenzylpyrimidine, 2-thiobenzyl-4,6-dimethylpyrimidine, thioanisole, and n-heptyl methyl sulfide) was performed in ionic liquids by using MCM-41 and UVM-type mesoporous catalysts containing Ti, or Ti and Ge. A range of triflate, tetrafluoroborate, trifluoroacetate, lactate and bis(trifluoromethanesulfonyl)-imide-based ionic liquids were used. The oxidations were carried out by using anhydrous hydrogen peroxide or the urea-hydrogen peroxide adduct and showed that ionic liquids are very effective solvents, achieving greater reactivity and selectivity than reactions p…

A counterion study of a series of [Cu(P^P)(N^N)][A] compounds with bis(phosphane) and 6-methyl and 6,6′-dimethyl-substituted 2,2′-bipyridine ligands …

2021

The syntheses and characterisations of a series of heteroleptic copper(i) compounds [Cu(POP)(Mebpy)][A], [Cu(POP)(Me2bpy)][A], [Cu(xantphos)(Mebpy)][A] and [Cu(xantphos)(Me2bpy)][A] in which [A]− is [BF4]−, [PF6]−, [BPh4]− and [BArF4]− (Mebpy = 6-methyl-2,2′-bipyridine, Me2bpy = 6,6′-dimethyl-2,2′-bipyridine, POP = oxydi(2,1-phenylene)bis(diphenylphosphane), xantphos = (9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphane), [BArF4]− = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) are reported. Nine of the compounds have been characterised by single crystal X-ray crystallography, and the consequences of the different anions on the packing interactions in the solid state are discussed. T…