Palladium nanoparticles in catalytic carbon nanoreactors: the effect of confinement on Suzuki-Miyaura reactions

We explore the construction and performance of a range of catalytic nanoreactors based on palladium nanoparticles encapsulated in hollow graphitised nanofibres. The optimum catalytic material, with small palladium nanoparticles located almost exclusively at the graphitic step-edges within nanoreactors, exhibits attractive catalytic properties in Suzuki-Miyaura cross-coupling reactions. Confinement of nanoparticles at the step-edges facilitates retention of catalytic centres and recycling of catalytic nanoreactors without any significant loss of activity or selectivity over multiple catalytic cycles. Furthermore, careful comparison of the catalytic properties of palladium nanoparticles either on or in nanoreactors reveals that nanoscale confinement of catalysts fundamentally affects the pathways of the Suzuki-Miyaura reaction, with the yield and selectivity for the cross-coupled product critically dependent on the steric properties of the aryl iodide reactant, whereas no effects of confinement are observed for aryl boronic acid reactants possessing substituents in different positions. These results indicate that the oxidative addition step of the Suzuki-Miyaura reaction occurs at the step-edge of nanofibres, where the mechanisms and kinetics of chemical reactions are known to be sensitive to nanoscale confinement, and thus the extent of confinement in carbon nanoreactors can be discretely controlled by careful selection of the aryl iodide reactant

Enantiomeric High-performance Liquid Chromatographic Separation of Β- Substituted Tryptophan Analogues

The high-performance liquid chromatographic enantioresolution of β- substituted tryptophan analogues by direct and indirect methods is reported. The direct separation was carried out on chiral crown ether-bonded, on the macrocyclic antibiotic teicoplanin-bonded or on different derivatized β- cyclodextrin-bonded phases. The indirect resolution was achieved by applying pre-column derivatization with the chiral reagents 1-fluoro-2,4- dinitrophenyl-5-L-alanine amide (FDAA) and 2,3,4,6-tetra-O-acetyl-β-D- glucopyranosyl isothiocyanate (GITC). In the separation of all four isomers of the analytes, the indirect methods seemed to be more efficient than the direct methods. In most cases, the FDAA derivatives of the stereoisomers could be separated with better selectivity in methanol-containing mobile phases

Introduction

Qu’est-ce qu’une organisation religieuse ? Si le rapprochement d’une organisation religieuse avec une entreprise du secteur privé (marchand) semble incontournable au regard de la diversité des activités aujourd’hui exercées par une communauté religieuse, plusieurs questions subsistent. L’organisation religieuse, par les liens juridiques qui se tissent entre ses membres et avec les acteurs externes, a pu faire l’objet de débats judiciaires et doctrinaux sur l’applicabilité du droit de la concu..

New developments of the Extended Quadrature Method of Moments to solve Population Balance Equations

Population Balance Models have a wide range of applications in many industrial fields as they allow accounting for heterogeneity among properties which are crucial for some system modelling. They actually describe the evolution of a Number Density Function (NDF) using a Population Balance Equation (PBE). For instance, they are applied to gas–liquid columns or stirred reactors, aerosol technology, crystallisation processes, fine particles or biological systems. There is a significant interest for fast, stable and accurate numerical methods in order to solve for PBEs, a class of such methods actually does not solve directly the NDF but resolves their moments. These methods of moments, and in particular quadrature-based methods of moments, have been successfully applied to a variety of systems. Point-wise values of the NDF are sometimes required but are not directly accessible from the moments. To address these issues, the Extended Quadrature Method of Moments (EQMOM) has been developed in the past few years and approximates the NDF, from its moments, as a convex mixture of Kernel Density Functions (KDFs) of the same parametric family. In the present work EQMOM is further developed on two aspects. The main one is a significant improvement of the core iterative procedure of that method, the corresponding reduction of its computational cost is estimated to range from 60% up to 95%. The second aspect is an extension of EQMOM to two new KDFs used for the approximation, the Weibull and the Laplace kernels. All MATLAB source codes used for this article are provided with this article

La religion et le travail au milieu du gué européen : sur la méthode juridico-politique des avocats généraux près la CJUE

Deux renvois préjudiciels fournissent à la CJUE l’occasion de se prononcer, par le prisme de l’interdiction des discriminations par la directive 2000/78, sur le degré de protection de la liberté de religion du salarié face à la liberté d’entreprendre de l’employeur. L’analyse développée dans l’article porte sur les conclusions présentées par les avocats généraux Kokott et Sharpston respectivement en mai et juillet 2016. Elle tend à montrer comment, tant la (re) formulation des questions préjudicielles que les solutions suggérées tentent d’orienter la CJUE dans deux voies opposées. Guidée par une logique (néo) libérale, la première propose un assouplissement des contraintes antidiscriminatoires, tandis que la seconde repose sur une approche centrée sur les droits de l’homme.The CJEU has been asked to make two preliminary rulings designed to clarify prohibition under EU law (Directive No 2000/78) of discrimination on the ground of religion at work and, in doing so, to determine the level of protection of the exercise of workers’ religious freedom. This article provides an analysis of the opinions delivered by Advocates General Kokott and Sharpston in May and July 2016. In the authors’ view, the (re) wording of the questions, as well as the solutions suggested propose two opposite directions to the CJEU: on the one hand, a neoliberal approach, which tends to alleviate anti-discrimination requirements, and on the other a human rights-based approach

The Effect of Quantum Dot Shell Structure on Fluorescence Quenching By Acridine Ligand

The current strategy for the development of advanced methods of tumor treatment focuses on targeted drug delivery to tumor cells. Quantum dot (QD) - semiconductor fluorescent nanocrystal, conjugated with a pharmacological ligand, such as acridine, ensures real-time tracking of the delivery process of the active substance. However, the problem of QD fluorescence quenching caused by charge transfer can arise in the case when acridine is bound to the QD. We found that QD shell structure has a defining role on photoinduced electron transfer from QD on acridine ligand which leads to quenching of QD photoluminescence. We have found that multishell CdSe/ZnS/CdS/ZnS QD structure provides minimal reduction of photoluminescence quantum yield at minimal shell thickness compared to classical thin ZnS or “giant” shells. Thus, CdSe/ZnS/CdS/ZnS core/multishell QD could be an optimal choice for engineering of small-sized acridine-based fluorescent labels for tumor diagnosis and treatment systems. Keywords: Quantum dot, photoluminescence quenching, DNA ligand, acridine derivative

4-Arylbenzenesulfonamides as Human Carbonic Anhydrase Inhibitors (hCAIs): Synthesis by Pd Nanocatalyst-Mediated Suzuki–Miyaura Reaction, Enzyme Inhibition, and X-ray Crystallographic Studies

Benzenesulfonamides bearing various substituted (hetero)aryl rings in the para-position were prepared by palladium nanoparticle-catalyzed Suzuki–Miyaura cross-coupling reactions and evaluated as human carbonic anhydrase (hCA, EC 4.2.1.1) inhibitors against isoforms hCA I, II, IX, and XII. Most of the prepared sulfonamides showed low inhibition against hCA I isoform, whereas the other cytosolic isoenzyme, hCA II, was strongly affected. The major part of these new derivatives acted as potent inhibitors of the tumor-associated isoform hCA XII. An opposite trend was observed for phenyl, naphthyl, and various heteroaryl substituted benzenesulfonamides which displayed subnanomolar hCA IX inhibition while poorly inhibiting the other tumor-associated isoform hCA XII. The inhibition potency and influence of the partially restricted aryl–aryl bond rotation on the activity/selectivity were rationalized by means of X-ray crystallography of the adducts of hCA II with several 4-arylbenzenesulfonamides

tert-Butyl 6-bromo-1,4-dimethyl-9H-carbazole-9-carboxyl­ate

The title compound, C19H20BrNO2, consists of a carbazole skeleton with methyl groups at positions 1 and 4, a protecting group located at the N atom and a Br atom at position 6. The pyrrole ring is oriented at dihedral angles of 1.27 (7) and 4.86 (7)° with respect to the adjacent benzene rings. The dihedral angle between the benzene rings is 5.11 (7). The crystal structure is determined mainly by intra­molecular C—H⋯O and inter­molecular π–π inter­actions. π-stacking between adjacent molecules forms columns with a parallel arrangement of the carbazole ring systems. The presence of the tert-but­oxy­carbonyl group on the carbazole N atom and the intra­molecular hydrogen bond induce a particular conformation of the exocyclic N—C bond within the mol­ecule