Search results for "ceramic"
showing 10 items of 2129 documents
Asymmetric [N–I–N]+halonium complexes in solution?
2020
Assessment of the solution equilibria of [bis(pyridine)iodine(I)]+ complexes by ESI-MS and NMR reveals the preference of iodine(I) to form complexes with a more basic pyridine. Mixtures of symmetric [bis(pyridine)iodine(I)]+ complexes undergo statistical ligand exchange, with a predominant entropic driving force favoring asymmetric systems. The influence of ligand basicity, concentration, temperature, and ligand composition is evaluated. Our findings are expected to facilitate the investigations, and the supramolecular and synthetic applications of halonium ions’ halogen bonds. peerReviewed
Potent affinity material for tracing acetone and related analytes based on molecular recognition by halogen bonds.
2014
Affinity materials based on halogen bonds turned out to be a powerful tool for the molecular recognition of acetone or related carbonyl compounds in the presence of ubiquitous protic molecules. The superior selectivity and sensitivity were found by the gravimetric detection of volatile organic compounds by quartz crystal microbalances.
Structural Changes of Titanium Oxide Induced by Chromium Addition as Determined by an X-Ray Diffraction Study
1995
Abstract An X-ray diffraction study has been carried out on a series of polycrystalline TiO 2 (anatase) catalysts containing Cr(III) at different atomic concentrations (0.2-5.0 at. %), prepared by a co-precipitation method. Analysis of the variation of the unit cell parameters of chromium-doped anatase with respect to pure anatase has allowed us to estimate the solubility limit for the system at around 1.4 at. %. There is no evidence for the existence of a separate crystalline chromium oxide phase. Temperature effects on the cell parameter and on the anatase-rutile transformation rate were also analyzed. An increase in temperature produced release of the chromium from the solid solution. At…
Iron(iii) oxamato-catalyzed epoxidation of alkenes by dioxygen and pivalaldehyde
1997
A new iron(III)–carbonato monomeric complex of orthophenylenebis( oxamato) (opba) 1 is synthesized, and spectroscopically and structurally characterized; it is a moderately efficient non-heme catalyst for the aerobic epoxidation of alkenes with co-oxidation of pivalaldehyde. Ruiz Garcia, Rafael, Rafael.Ruiz@uv.es ; Fernandez Picot, Isabel, Isabel.Fernandez@uv.es ; Pedro Llinares, Jose Ramon, Jose.R.Pedro@uv.es
Tetraiodoethynyl resorcinarene cavitands as multivalent halogen bond donors
2014
The first examples of iodoethynyl resorcinarene cavitands as rigid 3D halogen bond (XB) donor molecules are presented. These concave macrocycles form strong, RXB = 0.78–0.83, halogen bonds with dioxane oxygen, pyridine nitrogen and a bromide anion in tetraproropyl ammonium bromide resulting in deep cavity cavitand structures.
Graphitically encapsulated cobalt nanocrystal assemblies
2010
Graphitically encapsulated cobalt nanocrystal assemblies are chemically prepared by one-pot reaction at380 degrees C followed by a reversed etching process to produce porous graphitic structure for revealing their self-assembling nature.
Cocrystal trimorphism as a consequence of the orthogonality of halogen- and hydrogen-bonds synthons.
2019
True trimorphic cocrystals, i.e. multi-component molecular crystals of identical composition that exhibit three polymorphic structures, are exceedingly rare and so far no halogen-bonded cocrystal system has been reported to exhibit trimorphism. Here we describe a unique example of a trimorphic cocrystal exhibiting both hydrogen and halogen bonds in which the differences between polymorphs reveal their orthogonality, evident by the apparently independent variation of well-defined hydrogen- and halogen-bonded motifs. peerReviewed
Creation of glass-characteristic point defects in crystalline SiO2 by 2.5 MeV electrons and by fast neutrons
2019
The support from M -ERANET project “MyND” is acknowledged. K.K. was partially supported by the Collaborative Research Project of Laboratory for Materials and Structures, Tokyo Institute of Technology . Visiting researcher support from Ecole Polytechnique, Palaiseau is appreciated. Mr. Olivier Cavani is thanked for the expert help with irradiations.
Influence of Ge doping level on the EPR signal of Ge(1), Ge(2) and E'Ge defects in Ge-doped silica
2011
Abstract We present an experimental investigation on the Ge doping level dependence of the Electron Paramagnetic Resonance (EPR) signal spectral features of the Ge(1), Ge(2) and E'Ge defects induced in Ge doped silica. We have studied samples produced by sol–gel or PCVD techniques and doped with different amounts of Ge up to 20% by weight. The samples were gamma or beta ray irradiated and successively they were thermally treated to isolate the EPR signals of the different point defects. The data show that the EPR line shapes of the Ge(1) and the Ge(2) centers are progressively modified for doping level higher than 1%, whereas the line shape of the E'Ge defect appears independent from the do…
Synthesis and Characterisation of Functionalized borosilicate nanoparticles for boron neutron capture therapy applications
2012
Boron Neutron Capture Therapy (BNCT) is a promising therapy for the cure of diffuse tumors. The successful clinical application of BNCT requires finding new boron-based compounds suitable for an efficient 10B delivery to the cancerous tissues. The purpose of this work is to synthesize borosilicate nanoparticles by a sol–gel recipe, and to functionalize them with folic acid in order to promote their capture by the tumor cells. Whereas sol–gel is a promising technique for the synthesis of nanoparticles, in case of borosilicate systems this approach is affected by significant boron loss during preparation. Here we show that functionalization of borosilicate nanoparticles with folic acid can re…