Search results for "SURFACE MODIFICATION"
showing 10 items of 417 documents
Cover Picture: Photo-Chromium: Sensitizer for Visible-Light-Induced Oxidative C−H Bond Functionalization-Electron or Energy Transfer? (ChemPhotoChem …
2017
Synthesis and properties of chemically modified dihydroxy-, hydroxyamino- and amino-functional silica packings in adsorption chromatography
1980
1,2-Dihydroxy-3-propoxypropyl (HPP), 1-amino-2-hydroxy-3-propoxypropyl (AHP) and 3-(2-aminoethylamino)propyl (AEAP) silica packings were synthesized by means of both a surface modification and a bulk modification procedure. In surface modification a complete monolayer of bonded groups could be achieved. The modifiers reacted with the silanol groups according to a bifunctional mechanism. Eluotropic series of solvents were established on these polar modified silicas referring to n-heptane having ɛ∘=0. The solvent parameter ratio of modified to bare silica was found to be constant over a wide range of solvent compositions as \(\varepsilon _{{\text{HPP - silica}}}^ \circ = 0.26\varepsilon _{{\t…
Column technology in liquid chromatography
2017
This chapter deals with the most important part of the liquid chromatography (LC) system: the column enabling the efficient and fast resolution of complex mixtures. It is divided into seven sections under the overall aspects of manufacture, operation, and evaluation of analytical columns for the user. The first three sections highlight the column design and hardware, followed by a thorough treatment of the properties of microparticulate silica adsorbents as packing material, stationary phases performed by surface functionalization, and the column filling process. Then, the implementation of the column into the LC system is discussed, leading into chromatographic column testing as a C18-bond…
Hydrolytically stable chemically bonded silica supports with metal complexating ligands: Synthesis, characterization and use in high-performance liga…
1982
A silica of 14 nm pore size was reacted according to two procedures with the following silanes: γ-aminopropyltriethoxysilane (1), N-aminoethyl-N′-aminopropyltrimethoxysilane (2), N-aminoethyl-N′-aminoethyl-N″-aminopropyltrimethoxysilane (3), N-(3-triethoxysilanepropyl)-N, N-diacetic dimethylester (4), N-(3-trisodiumsilanolatepropyl)-N, N-diacetic acid disodium salt (5) and N-(3-trisodiumsilanolatepropyl)-ethylenediamine-N, N′, N′-triacetic acid trisodium salt (6). The reaction of silanes 1–4 with the silica was carried out under anhydrous conditions (procedure A). Silanes 1–6 were subjected to surface modification under essentially hydrous conditions applying a two-step procedure (procedure…
A facile way to build up branched high functional polyaminoacids with tunable physicochemical and biological properties
2016
Abstract Here, for the first time, branched polyaminoacids bearing α-amino acids as side functions, namely PAA-co-AA and PGA-co-AA, are prepared by heterophase ring opening of polysuccinimide (PSI) with l -arginine or glycine in aqueous environment and at controlled pH. The modulation of the pH of the reaction leads to high-molecular-weight copolymers with tunable functionalization and, as consequence, with tailor-made physicochemical properties. Furthermore, a branched polyaminoacid carrying a preformed bioactive peptide ( l -trileucine) and l -arginine as side pendants, named PATA-co-AA, was synthesized via a similar pathway thus leading to complex biomimetic materials potentially exploit…
Recent Advances in Photocatalytic Functionalization of Quinoxalin‐2‐ones
2020
Quinoxalin‐2(1H)‐one is an important class of nitrogen heterocycle in medicinal and pharmaceutical industry, which became a synthetic target in organic chemistry in recent years. This review covers the recent advances in the functionalization of this particular nitrogen heterocycle through photocatalysis.
Influence of Pendant Arms Bearing Ligating Groups on the Structure of Bismuth Porphyrins: Implications for Labeling Immunoglobulins Used in Medical A…
2004
International audience; The synthesis of two picket bismuth(III) porphyrins is reported, and their crystal structures are compared. The influence of the nature of the pickets, as well as their number, is discussed in terms of stability, kinetics of metalation, structure, and distortion of the porphyrin. Unexpectedly, the resultsindicate that the coordination sphere of bismuth is not affected by different types of distortion nor is the stability of the complex. For both types of complexes, the X-ray crystallography revealed that a single arm is actually in direct interaction with the bismuth cation, thereby allowing furtherfunctionalization on the porphyrin core as the linkage with immunoglo…
Grafting and characterization of dodecylphosphonic acid on copper: Macro-tribological behavior and surface properties
2013
International audience; Thin film of n-dodecylphosphonic acid (DDPA) was prepared on a copper oxide substrate via a molecular self-assembly process. The composition, structure, organization, surface energy, morphology, and electrochemical behavior of the DDPA filmwere characterized bymeans of X-ray photoelectron spectroscopic analysis (XPS), polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), contact angle measurement v(CAM), microscopic observations, and electrochemistry. The friction behavior of the DDPA film adsorbed on copper oxide substrate sliding against a Si3N4 ball was examined on a linear reciprocating tribological tester. Worn surfaces of the DDPA film…
Functionalization of Graphene with Molecules and/or Nanoparticles for Advanced Applications
2019
Graphene is considered the material of the third millennium, due to its extraordinary electronic and mechanical properties, and due to the possibility to modulate its conductivity, flexibility, elasticity, transparency, and biocompatibility by bottom-up approach. The possibility to gather the proper- ties of graphene and graphene oxide with those of functional moieties or nanoparticles is herein reviewed. The synthetic approaches proposed, either covalent or noncovalent, are aimed to tune appropriately graphene’s properties for the realization of materials for advanced uses, such as bio- medical applications, sensors, catalysis, and energy devices. In particular, methods based on covalent l…
<title>Heavy-ion induced damage and reduction of dislocation mobility in LiF single crystals</title>
2006
Ion-induced reduction of dislocation mobility in LiF crystals irradiated with swift heavy (U) and light (Ni) ions of a specific energy of 11 MeV per nucleon at fluences between 106 and 1011 ions/cm2 was studied. The arm length of dislocation rosettes produced by indentation on (100) irradiated surface was measured. It has been found that in the case of heavy ions the threshold fluence (106 ions/cm2) for impeding of dislocation arms is about 3 orders of magnitude lower than that for light ions. The results indicate that ion-induced defect aggregates play the dominating role in the impeding of dislocations. Heavy ions, which produce defect aggregates in the track core, cause also a stronger e…