Search results for " bonding"

Dimeric Resorcin[4jarene Capsules in the Solid State

2011

Supramolecular chemistry research is focused on the study of weak non-covalent intermolecular — that is, supramolecular — interactions as the driving force in self-assembly and molecular recognition. Dimeric resorcin[4]arenes capsules have been a focus of our research for the last 15 years. This review describes the solid state complexation studies of unsubstituted phenolic resorcin[4]arenes and pyrogall[4]arenes towards the formation of dimeric capsules and assemblies using ionic and neutral species as guest molecules and templates. The multitude of different crystal structures obtained during these studies demonstrates the versatile nature of resorcin[4]arenes and pyrogall[4]arenes (2-hyd…

Phycocyanobilin in solution – a solvent triggered molecular switch

2014

We present a computational investigation of the conformational response of phycocyanobilin (PCB) to the ability of solvents to form hydrogen bonds. PCB is the chromophore of several proteins in light harvesting complexes. We determine the conformational distributions in different solvents (methanol and hexamethylphosphoramide HMPT) by means of ab initio molecular dynamics simulations and characterize them via ab initio calculations of NMR chemical shift patterns. The computed trajectories and spectroscopic fingerprints illustrate that the energy landscape is very complex and exhibits various conformations of similar energy. We elucidate the strong influence of the solvent characteristics on…

2-exo,5-endo,8,8,10-Pentachlorobornane

2008

The title compound, C(10)H(13)Cl(5), is a polychlorinated monoterpene and a Toxaphene congener. This compound is also the only penta-chlorinated derivative of camphene formed via ionic chlorination. Previously, the title compound was thought to be 2-exo,5-endo,9,9,10-penta-chloro-bornane, but X-ray structural analysis showed it to have a different structure and rather to be 2-exo,5-endo,8,8,10-penta-chloro-bornane. The title compound shows static disorder and almost half the molecule was divided in two partitions with an occupancy ratio of 0.575 (major) to 0.425 (minor). The repulsive close contacts of Cl atoms could possibly be the cause for this disorder.

Mobile supported monolayers of ionic amphiphiles: variation of domain morphology via preadsorbed polyelectrolytes

1992

Structural, Spectroscopic and Electrical Features of Undoped and Mn Doped LiTi2(PO4)3

2010

The study of the ionic conducting material LiTi2(PO 4)3 and of its Mn-substituted derivate reveals that the Mn distribution is strictly related to the synthetic method. The results of the structural refinement of X-ray and neutron (ToF) powder diffraction data and of XPS analysis demonstrate that Mn2+ ions are located on the lithium octahedral site, while Mn3+ and Mn4+ ions occupy the titanium ones. The Mn2+ amount on the lithium site seems to be the main factor responsible for the conductivity decrease observed in doped samples. The EPR spectra evidence clustering effects of Mn on both Li and Ti sites and the presence of more insulated Mn2+ ions. The effect of the major Mn amount on Ti sit…

Nanotransducers on printed circuit boards by rational design of high-density, long, thin and untapered ZnO nanowires

2018

Abstract Nanotransducers can offer crucial advantages in comparison with conventional sensors and actuators. However, interfacing and packaging nanostructures into complete electronic systems is very complex. Here we describe a wet chemical method for cointegrating arrays of ZnO nanowires into systems on printed circuit boards (PCBs). First, we deposit on the PCB a MnOOH layer for reproducibly increasing the nanowires density. Afterwards, we numerically demonstrate that the ligand ethylenediamine, at the isoelectric point of the ZnO nanowires tips, can effectively control, at very low concentrations, both zinc speciation and supersaturation in the nutrient solution. Accordingly, we combine …

Current rectification by nanoparticle blocking in single cylindrical nanopores.

2014

Blocking of a charged pore by an oppositely charged nanoparticle can support rectifying properties in a cylindrical nanopore, as opposed to the usual case of a fixed asymmetry in the pore geometry and charge distribution. We present here experimental data and model calculations to confirm this fundamental effect. The nanostructure imaging and the effects of nanoparticle concentration, pore radius, and salt concentration on the electrical conductance–voltage (G–V) curves are discussed. Logic responses based on chemical and electrical inputs/outputs could also be implemented with a single pore acting as an effective nanofluidic diode. To better show the generality of the results, different ch…

Highly untangled multiwalled carbon nanotube@polyhedral oligomeric silsesquioxane ionic hybrids: Synthesis, characterization and nonlinear optical pr…

2015

Abstract Highly de-bundled multiwalled carbon nanotube (MWCNT) polymer nanohybrids were obtained via ionic assembling of a novel POSS-polyimidazolium-ionic liquid (POSS = polyhedral oligomeric silsesquioxanes) with oxidized MWCNTs. The synthesis, accomplished by a simple bilayer chloroform/water metathetical reaction process, was promoted by the high surfactant properties of POSS-imidazolium-polyionic liquid, which assisted the effective de-bundling, dispersion and purification of the as prepared POSS@MWCNT polymers in organic media, via a surface coating mechanism. The presence of remarkably intense radial breathing modes (RBMs) in Raman spectra, both in solution and as solid, corroborates…

Sedimentation of halloysite nanotubes from different deposits in aqueous media at variable ionic strengths

2019

Abstract Halloysite clay is a natural nanomaterial that is attracting a growing interest in colloidal science. The halloysite aqueous dispersion stability is a key aspect for the configuration of a purification protocol as well as to establish the durability of a formulation. A physico-chemical study demonstrated the role of ionic strength and nanotube characteristic sizes on the sedimentation behavior. We highlighted the importance of the electrostatic repulsions exercised between the particles in the settling process. A protocol for image analysis has been proposed to provide robust information from time resolved optical images on the suspensions. In conclusion, we managed to correlate mi…

Voltage-activated transport of ions through single-walled carbon nanotubes

2017

International audience; Ionic transport through single-walled carbon nanotubes (SWCNTs) is promising for many applications but remains both experimentally challenging and highly debated. Here we report ionic current measurements through microfluidic devices containing one or several SWCNTs of diameter of 1.2 to 2 nm unexpectedly showing a linear or a voltage-activated I-V dependence. Transition from an activated to a linear behavior, and stochastic fluctuations between different current levels were notably observed. For linear devices, the high conductance confirmed with different chloride salts indicates that the nanotube/water interface exhibits both a high surface charge density and flow…