An effective Pd nanocatalyst in aqueous media: stilbene synthesis by Mizoroki–Heck coupling reaction under microwave irradiation

Aqueous Mizoroki–Heck coupling reactions under microwave irradiation (MW) were carried out with a colloidal Pd nanocatalyst stabilized with poly(N-vinylpyrrolidone) (PVP). Many stilbenes and novel heterostilbenes were achieved in good to excellent yields starting from aryl bromides and different olefins. The reaction was carried out in a short reaction time and with low catalyst loading, leading to high turnover frequency (TOFs of the order of 100 h−1). The advantages like operational simplicity, high robustness, efficiency and turnover frequency, the utilization of aqueous media and simple product work-up make this protocol a great option for stilbene syntheses by Mizoroki–Heck reaction

Nanomateriales híbridos para aplicaciones biomédicas (Hybrid nanomaterials for biomedical applications)

 ResumenLos nanomateriales para aplicaciones biomédicas han llevado a los investigadores a diseñar continuamente nuevas herramientas y estrategias para su obtención y evaluación de su desempeño. Recientemente, los nanomateriales híbridos se evaluaron como plataformas prometedoras para aplicaciones terapéuticas. Esta clase única de nanomateriales conserva las características ventajosas de los componentes orgánicos e inorgánicos y proporciona la capacidad de ajustar las propiedades del nanomaterial híbrido mediante la combinación de componentes funcionales. Este trabajo de revisión resume los avances recientes en el diseño y las aplicaciones biomédicas de los nanomateriales híbridos orgánicos-inorgánicos, específicamente, aquellos basado en metales/óxidos metálicos biocompatibles. Se destacarán algunas de sus principales aplicaciones como sistemas portadores para la liberación controlada de fármacos. AbstractNanomaterials for biomedical applications continuously lead researchers to design novel tools and strategies for their obtention and performance evaluation. Hybrid nanomaterials have recently been evaluated as promising platforms for therapeutic applications. This unique class of nanomaterials retains advantageous features of both the inorganic and organic components and provides the ability to tune the properties of the hibrid nanomaterial through the combination of functional components. This perspective summarizes recent advances in the design and biomedical applications of organic-inorganic hybrid nanomaterials, specifically metal/metal oxide-based biocompatible nanohybryd materials. Some of their main applications as carriers for controlled drug release will be highlighted

A Chiral Bis(arsine) Ligand: Synthesis and Applications in Palladium-Catalyzed Asymmetric Allylic Alkylations

The new chiral bis­(arsine) ligand <i>N</i>,<i>N</i>′-bis­[2′-(diphenylarsino)­benzoyl]-(1<i>R</i>,2<i>R</i>)-cyclohexanediamine (<i>BiAsBA</i>, <b>3</b>), based on the backbone of the Trost modular ligand (TML), was synthesized in three steps. A useful approach to introduce the −AsPh₂ group on arsine ligands by Pd-catalyzed arsination was used. The molecular structure and configuration of the <i>BiAsBA</i> ligand was determined by single-crystal X-ray crystallography. In the asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate very high to complete conversion and modest enantioselectivity were achieved. Despite the low enantioselectivity obtained, the bis­(arsine) ligand <i>BiAsBA</i> showed significant potential, since it provided a higher ee value than the phosphorus-containing homologous “Trost standard ligand” (TSL) with the same substrate

Insights into the active surface species formed onTa2O5nanotubes in the catalytic oxidation of CO

Freestanding Ta2O5nanotubes were prepared by an anodizing method. As-anodized amorphousnanotubes were calcined at high temperature to obtain a crystalline phase. All materials were studied bymeans of BET analysis, XRD, TEM, SEM, XPS, and FTIR and were evaluated in the catalytic oxidation ofCO. An XPS study confirmed the formation of different tantalum surface species after high temperaturetreatment of amorphous Ta2O5nanotubes. Calcination at 8001C generated Ta4+while highertemperature (10001C) treatment led to the formation of Ta3+species. These materials also showedsignificant differences in catalytic activity. Higher activity was observed for samples calcined at 8001Cthan at 10001C, suggesting that Ta4+species are active sites for CO oxidation.Fil: Gonçalves, Renato V.. Universidade de Sao Paulo; BrasilFil: Wojcieszak, Robert. Universidade de Sao Paulo; BrasilFil: Uberman, Paula Marina. Universidade de Sao Paulo; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Teixeira, Sergio R.. Universidade Federal do Rio Grande do Sul; BrasilFil: Rossi, Liane M.. Universidade de Sao Paulo; Brasi

A recoverable Pd nanocatalyst for selective semi-hydrogenation of alkynes: hydrogenation of benzyl-propargylamines as a challenging model

We describe a recyclable heterogeneous palladium nanocatalyst for the selective hydrogenation of alkynes to alkenes. The catalyst was prepared through the decomposition of the organometallic precursor Pd2(dba)3 over a magnetic support, obtaining well-dispersed Pd nanoparticles that formed exclusively on the support surface, with average diameters of 3.5 ± 0.8 nm. The catalytic activity was evaluated in the hydrogenation reactions of alkenes and alkynes, and the chemo- and stereoselectivity was evaluated in the hydrogenation of benzylpropargylamines. The catalyst is highly selective in performingsemi-hydrogenation reactions under mild conditions and short reaction times, with good overall yields. Furthermore, it can be easily recovered and recycled, with no leaching of palladium detected, and it can retain high activities and selectivity over multiple reaction cycles.Fil: Uberman, Paula Marina. Universidade de Sao Paulo; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Costa, Natalia J. S.. Universidade de Sao Paulo; BrasilFil: Philippot, Karine. Laboratoire de Chimie de Coordination; Francia. Université de Toulouse; FranciaFil: Carmona, Rafaela C.. Universidade de Sao Paulo; BrasilFil: Dos Santos, Alcindo A.. Universidade de Sao Paulo; BrasilFil: Rossi, Liane M.. Universidade de Sao Paulo; Brasi

Catalytic abatement of CO over highly stable Pt supported on Ta2O5 nanotubes

The development of active and stable catalysts has emerged as an important strategy in the catalytic abatement of CO. This article reports the use of the novel Pt-based catalyst supported on crystalline Ta2O5 nanotubes prepared by sputtering and anodization methods in CO oxidation reaction. Crystalline and amorphous Ta2O5 NTs and Pt modified sample were found active in low temperature CO oxidation. Results showed that active and highly stable Pt/Ta2O5 NTs catalyst could be a promising system for CO removal from gas exhaust.Fil: Gonçalves, Renato V.. Universidade de Sao Paulo; BrasilFil: Wojcieszak, Robert. Universidade de Sao Paulo; BrasilFil: Uberman, Paula Marina. Universidade de Sao Paulo; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Eberhardt, Dario. Universidade Federal do Rio Grande do Sul; BrasilFil: Teixeira Neto, Erico. Universidade de Sao Paulo; BrasilFil: Teixeira, Sergio Ribeiro. Universidade Federal do Rio Grande do Sul; BrasilFil: Rossi, Liane M.. Universidade de Sao Paulo; Brasi