Search results for "monolayers"
showing 10 items of 25 documents
Spontaneous growth of 2D coordination polymers on functionalized ferromagnetic surfaces
2018
2D coordination polymers grow spontaneously on reactive surfaces due to surface oxidation. The growth process is observed in real time.
Electrochemistry of methylene blue at an alkanethiol modified electrode
2012
International audience; Gold surfaces were derivatized with decanethiol. The electrochemistry of methylene blue at these modified electrodes was investigated in function of the gold cleaning process and compared with the results obtained at a bare gold electrode. Cyclic voltammetry at low methylene blue concentrations (c(MB) <= 16 mu M) yielded surface behavior data. The properties of the film vary with the electrode pretreatment. Without electrochemical cleaning step, the standard potential at a gold electrode modified with 1-decanethiol is nearly the same as on a bare gold electrode. On the other hand, when the electrode is electrochemically cleaned before adsorption of the alkanethiols, …
Trimesic acid on Cu in ethanol: Potential-dependent transition from 2-D adsorbate to 3-D metal-organic framework
2017
We report the potential-dependent interactions of trimesic acid with Cu surfaces in EtOH. CV experiments and electrochemical surface-enhanced Raman spectroscopy show the presence of an adsorbed trimesic acid layer on Cu at potentials lower than 0 V vs Cu. The BTC coverage increases as the potential increases, reaching a maximum at 0 V. Based on molecular dynamics simulations, we report adsorption geometries and possible structures of the organic adlayer. We find that, depending on the crystal facet, trimesic acid adsorbs either flat or with one or two of the carboxyl groups facing the metal surface. At higher coverages, a multi-layer forms that is composed mostly of flat-lying trimesic acid…
Evaluation of Physicochemical Properties of Amphiphilic 1,4-Dihydropyridines and Preparation of Magnetoliposomes
2021
This study was focused on the estimation of the targeted modification of 1,4-DHP core with (1) different alkyl chain lengths at 3,5-ester moieties of 1,4-DHP (C12, C14 and C16)
Optical Gating of Photosensitive Synthetic Ion Channels
2011
4-oxo-4-(pyren-4-ylmethoxy) butanoic acid is used as a photolabile protecting group to show the optical gating of nanofluidic devices based on synthetic ion channels. The inner surface of the channels is decorated with monolayers of photolabile hydrophobic molecules that can be removed by irradiation, which leads to the generation of hydrophilic groups. This process can be exploited in the UV-light-triggered permselective transport of ionic species in aqueous solution through the channels. The optical gating of a single conical nanochannel and multichannel polymeric membranes is characterised experimentally and theoretically by means of current-voltage and selective permeation measurements,…
Strain-Promoted Cycloaddition of Cyclopropenes with o-Quinones : A Rapid Click Reaction
2018
Abstract Novel click reactions are of continued interest in fields as diverse as bio‐conjugation, polymer science and surface chemistry. Qualification as a proper “click” reaction requires stringent criteria, including fast kinetics and high conversion, to be met. Herein, we report a novel strain‐promoted cycloaddition between cyclopropenes and o‐quinones in solution and on a surface. We demonstrate the “click character” of the reaction in solution and on surfaces for both monolayer and polymer brush functionalization.
Assembly of citrate gold nanoparticles on hydrophilic monolayers
2016
Abstract Self-assembled monolayers (SAMs) as model surfaces were linked onto planar gold films thorough lipoic acid or disulfide groups. The molecules used were polyethylene glycol (EG-S-S), N -[tris-(hydroxymethyl)methyl]acrylamide polymers with and without lipoic acid (Lipa-pTHMMAA and pTHMMAA) and a lipoic acid triazine derivative (Lipa-MF). All the layers, but Lipa-MF with a primary amino group were hydroxyl terminated. The layers were characterized by contact angle measurements and atomic force microscopy, AFM. Citrate stabilized nanoparticles, AuNPs in water and phosphate buffer were allowed to assemble on the layers for 10 min and the binding was followed in real-time with surface pl…
Electrogeneration of Diiodoaurate in Dimethylsulfoxide on Gold Substrate and Localized Patterning
2016
International audience; A localized etching of gold surface by scanning electrochemical microscope technique is presented where a dimethylsulfoxide-based electrolyte charged with iodine is used. The electrogenerated triiodide ion at the platinum ultramicroelectrode tip (feedback mode) acts as an oxidant for gold surface. The effects of electrode diameter and the bias time have been investigated. The approach curve method was used to hold the electrode tip close to the gold surface. A scanning electron microscope is used to observe the etched gold surfaces where disk-shaped dots are generated. The diameter of these holes depends directly on the Pt electrode diameter and the bias time.
Spectroscopic and Theoretical Study of the Grafting Modes of Phosphonic Acids on ZnO Nanorods
2013
Metal oxides are versatile substrates for the design of a wide range of SAM-based organic-inorganic materials among which ZnO nanostructures modified with phosphonic SAM are promising semiconducting systems for applications in technological fields such as biosensing, photonics, and field-effect transistors (FET). Despite previous studies reported on various successful grafting approaches, issues regarding preferred anchoring modes of phosphonic acids and the role of a second reactive group (i.e., a carboxylic group) are still a matter of controversial interpretations. This paper reports on an experimental and theoretical study on the functionalization of ZnO nanorods with monofunctional alk…
Wide range local resistance imaging on fragile materials by conducting probe atomic force microscopy in intermittent contact mode
2016
International audience; An imaging technique associating a slowly intermittent contact mode of atomic force microscopy (AFM) with a home-made multi-purpose resistance sensing device is presented. It aims at extending the widespread resistance measurements classically operated in contact mode AFM to broaden their application fields to soft materials (molecular electronics, biology) and fragile or weakly anchored nano-objects, for which nanoscale electrical characterization is highly demanded and often proves to be a challenging task in contact mode. Compared with the state of the art concerning less aggressive solutions for AFM electrical imaging, our technique brings a significantly wider r…