Search results for "Organic base"
showing 6 items of 6 documents
Separation of plasma membrane proteins of cultured human fibroblasts by affinity chromatography on bonded microparticulate silicas.
1984
Abstract Adsorbents for high-performance affinity chromatography were prepared by bonding proteins and reactive Procion triazine dyes to 3-isothiocyanatopropyl- and 3-aminopropylsilicas. The materials prepared were used successfully in the separation of hydrophobic plasma membrane proteins of cultured human fibroblasts. The data obtained show that the reaction of 3-isothiocyanatopropyltriethoxysilane (ITCPS) with the surface hydroxyl groups of silica yields a new and convenient route to preparing an “activated carrier” that is capable of coupling with potential affinity ligands containing amino functional groups. The reaction and bonding procedures of 3-isothiocyanatopropyltriethoxysilane a…
Carbonyl Hypoiodites as Extremely Strong Halogen Bond Donors
2021
Abstract Neutral halogen‐bonded O−I−N complexes were prepared from in situ formed carbonyl hypoiodites and aromatic organic bases. The carbonyl hypoiodites have a strongly polarized iodine atom with larger σ‐holes than any known uncharged halogen bond donor. Modulating the Lewis basicity of the selected pyridine derivatives and carboxylates leads to halogen‐bonded complexes where the classical O−I⋅⋅⋅N halogen bond transforms more into a halogen‐bonded COO−⋅⋅⋅I−N+ ion‐pair (salt) with an asymmetric O−I−N moiety. X‐ray analyses, NMR studies, and calculations reveal the halogen bonding geometries of the carbonyl hypoiodite‐based O−I−N complexes, confirming that in the solid‐state the iodine at…
Alternating current voltammetric determination of DNA damage
1990
Abstract The conditions for alternating current (a.c.) voltammetric DNA determinations have been investigated with respect to its use with alkaline filter elution techniques at low DNA concentrations. In inorganic electrolyte solutions three current peaks can be distinguished: peak I around −1.1 V caused by the reorientation or desorption of DNA segments; peak II around −1.2 V caused by the native DNA (nDNA) form; peak III caused by denatured DNA (dDNA) at −1.4 V. Sonication of nDNA increases the peak current, however not with dDNA. Both dDNA and nDNA give linear peak current increments with DNA increments, their regression lines cutting the concentration axis at the origin. In filter eluti…
Ion Pairing in the Analysis of Voltammetric Data at the ITIES: RbTPB and RbTPBCl in 1,2-dichloroethane
1995
The association of rubidium-tetraphenylborate (RbTPB) and rubidium-tetrakis(-chlorophenyl)borate (RbTPBCl) ion pairs in the organic solvent 1,2-dichloroethane (DCE) have been obtained from condutivity and voltammetric data. Conductivity measurements given K RbTPBCl =43 100 M -1 and yield a lower bound for K RbTPB (K RbTPB > 70000 M -1 ). The latter association constant is at variance with the previously accepted value. A method for analysing voltammetric data which allows for the determination of the association constants is presented. The positive polarization limit where the transfer of Rb + takes place is shifted by ca. 200 mV when changing the anion of the organic base electrolyte from …
Inimer-Promoted Synthesis of Branched and Hyperbranched Polylactide Copolymers
2009
A series of (hyper)branched poly(l-lactide)(PLLA) copolymers has been prepared by ring-opening multibranching copolymerization of l-lactide with a hydroxyl-functional (ABB′) lactone inimer, 5HDON (5-hydroxymethyl-1,4-dioxane-2-on). Polymerization was conducted in bulk and solution and catalyzed either by stanneous-2-ethyl hexanoate (Sn(Oct)2) or an organic base, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). Precise structural characterization of the resulting branched copolyester structures was accomplished by a combination of 2D NMR techniques, relying on the comparison with model compounds. The 5HDON inimer was employed in 1% to 20% fractions and is incorporated either as a dendritic unit or…
Native and modified alumina, titania and zirconia in normal and reversed-phase high-performance liquid chromatography
1996
Chromatographic properties of silica, alumina, titania and zirconia have been investigated in normal phase mode in the separation of test mixtures of basic, neutral and acidic compounds. In contrast to silica the chromatographic behaviour revealed the basic properties of the alumina, titania and zirconia surfaces. Therefore, separation of basic compounds on these packings seems very promising. Lypophilic packings have been synthesized by modification of titania, zirconia and alumina with organosilanes and polymers and tested for the separation of basic compounds and proteins. High hydrolytic stability of the modified packings was observed during separations with strong alkali and acidic elu…