Resin-immobilized palladium nanoparticle catalysts for organic reactions in aqueous media: Morphological aspects

An insight into the nano- and micro-structural morphology of a polymer supported Pd catalyst employed in different catalytic reactions under green conditions is reported. The pre-catalyst was obtained by copolymerization of the metal-containing monomer Pd(AAEMA)2 [AAEMA = deprotonated form of 2-(acetoacetoxy) ethyl methacrylate] with ethyl methacrylate as co-monomer, and ethylene glycol dimethacrylate as cross-linker. This material was used in water for the Suzuki-Miyaura cross-coupling of aryl bromides, and for the reduction of nitroarenes and quinolines using NaBH4 or H2, as reductants. TEM analyses showed that in all cases the pristine Pd(II) species were reduced in situ to Pd(0), which formed metal nanoparticles (NPs, the real active species). The dependence of their average size (2-10 nm) and morphology on different parameters (temperature, reducing agent, presence of a phase transfer agent) is discussed. TEM and micro-IR analyses showed that the polymeric support retained its porosity and stability for several catalytic cycles in all reactions and Pd NPs did not aggregate after reuse. The metal nanoparticle distribution throughout the polymer matrix after several recycles provided precious information about the catalytic mechanism, which was truly heterogeneous in the hydrogenation reactions and of the so-called "release and catch" type in the Suzuki coupling

Приближенное решение задачи динамики гелеобразования

Рассмотрены уравнения, описывающие движение зонда вибрационного датчика вязкости в гелеобразующей вязкоупругой среде. Описано получение приближенных решений для определения вязкости и сдвиговой упругости, и проведено сравнение с точным решением

A polymer supported palladium(II) \u3b2-ketoesterate complex as active and recyclable pre-catalyst for selective reduction of quinolines in water with sodium borohydride

A polymer supported palladium catalyst, obtained by copolymerization of Pd(AAEMA)2 [AAEMA- = deprotonated form of 2-(acetoacetoxy) ethyl methacrylate] with ethyl methacrylate (co-monomer) and ethylene glycol dimethacrylate (cross-linker), exhibited excellent activity and selectivity for the hydrogenation of quinolines to 1,2,3,4-tetrahydroquinolines in the presence of NaBH4 as hydrogen donor in water. Both the activity and selectivity could be maintained for at least seven reaction runs. No metal leaching into solution occurred during recycles. TEM analyzes carried out on the catalyst showed that the active species were supported palladium nanoparticles having a mean size of 3 nm, which did not aggregate with the recycles

Pt-M (M = Au and Tl) Dative Bonds Using Bis(cyclometalated)platinum(II) Complexes

Symmetrical and unsymmetrical biscyclometalated platinum­(II) complexes [Pt­(ptpy)₂], <b>1</b>, and [Pt­(ptpy)­(bppy)], <b>2</b>, in which ptpy = deprotonated 2-(<i>p</i>-tolyl)­pyridine and bppy = deprotonated 2-(3-bromophenyl)­pyridine, have been prepared from the reaction between tris­(pentafluorophenyl)­borane, B­(C₆F₅)₃ and 1 equiv of monocyclometalated complexes [PtMe­(ptpy)­(ptpyH)], <b>B</b>, and [PtMe­(ptpy)­(bppyH)], <b>C</b>, respectively. The solid-state structures of <b>1</b> and <b>2</b> have been determined by X-ray crystallography. The reaction of <b>1</b> with 1 equiv of TlPF₆ or [Au­(PPh₃)]­OTF resulted in the production of heteronuclear complexes [Pt­(ptpy)₂Tl]­PF₆, <b>3</b> and {Pt­(ptpy)₂[Au­(PPh₃)]}­OTF, <b>4</b>, respectively. X-ray diffraction data showed that in solid state, complex <b>4</b> exists as a mixture of supported and unsupported Pt^II–Au^I-bonded structures, whereas complex <b>3</b> consists of an infinite helical chain structure built up by unsupported Pt–Tl dative bonds. Absorption, emission, and NMR spectroscopy data showed that both Pt–Tl and Pt–Au bonds in <b>3</b> and <b>4</b> have dynamic behavior. The low-temperature ¹H, ³¹P­{¹H}, and exchange spectroscopy NMR of <b>4</b> revealed two dynamic behaviors involving the rupture of the Au–C_<i>ipso</i> bond as well as the dissociation–association of the [Au­(PPh₃)]⁺ and Pt­(ptpy)₂ fragments. All complexes displayed bright emission in the solid state, and their absorption and emission properties have been investigated both experimentally and by time-dependent density functional theory calculations

Exploring the xylem-sap to unravel biological features of Xylella fastidiosa subspecies pauca ST53 in immune, resistant and susceptible crop species through metabolomics and in vitro studies

Xylella fastidiosa subsp. pauca ST53 (Xfp) is a pathogenic bacterium causing one of the most severe plant diseases currently threatening the olive-growing areas of the Mediterranean, the Olive Quick Decline Syndrome (OQDS). The majority of the olive cultivars upon infections more or less rapidly develop severe desiccation phenomena, while few are resistant (e.g. Leccino and FS17), being less impacted by the infections. The present study contributes to elucidating the basis of the resistance phenomenon by investigating the influence of the composition of the xylem sap of plant species on the rate of bacterial multiplication. Xylem saps from Xfp host and non-host species were used for growing the bacterium in vitro, monitoring bacterial growth, biofilm formation, and the expression of specific genes. Moreover, species-specific metabolites, such as mannitol, quinic acid, tartaric acid, and choline were identified by non-targeted NMR-based metabolomic analysis in olive, grapevine, and citrus. In general, the xylem saps of immune species, including grapevine and citrus, were richer in amino acids, organic acids, and glucose. The results showed greater bacterial growth in the olive cultivar notoriously susceptible to Xfp (Cellina di Nardò), compared to that recorded in the resistant cultivar Leccino. Conversely, higher biofilm formation occurred in Leccino compared to Cellina di Nardò. Using the xylem saps of two Xfp-immune species (citrus and grapevine), a divergent bacterial behavior was recorded: low planktonic growth and biofilm production were detected in citrus compared to the grapevine. A parallel evaluation of the expression of 15 genes showed that Xfp directs its molecular functions mainly to virulence. Overall, the results gained through this multidisciplinary study contribute to extending the knowledge on the host-pathogen interaction, while confirming that the host response and resistance mechanism have a multifactorial basis, most likely with a cumulative effect on the phenotype

Понятие внешней среды в современном менеджменте

Анализируются изменения, произошедшие в определении понятия "внешняя среда". Приводятся различные подходы к определению факторов, входящих во внешнюю среду предприятия. В процессе рассмотрения особое внимание уделяется изменениям, происходящим в определении факторов данной среды в современном менеджменте. По результатам исследования определен современный состав факторов внешней среды, определена их роль в становлении концепта "современный менеджмент" в России

Low-Intensity Light-Responsive Anticancer Activity of Platinum(II) Complex Nanocolloids on 2D and 3D In Vitro Cancer Cell Model

none8This study aimed to evaluate the therapeutic efficacy of low-intensity visible light responsive nanocolloids of a Pt-based drug using a 2D and three-dimensional (3D) in vitro cancer cell model. Biocompatible and biodegradable polymeric nanocolloids, obtained using the ultrasonication method coupled with Layer by Layer technology, were characterized in terms of size (100 ± 20 nm), physical stability, drug loading (78%), and photoactivation through spectroscopy studies. The in vitro biological effects were assessed in terms of efficacy, apoptosis induction, and DNA-Pt adducts formation. Biological experiments were performed both in dark and under visible light irradiation conditions, exploiting the complex photochemical properties. The light-stimuli responsive nanoformulation gave a significant enhancement in drug bioactivity. This allowed us to achieve satisfying results by using nanomolar drug concentration (50 nM), which was ineffective in darkness condition. Furthermore, our nanocolloids were validated in 3D in vitro spheroids using confocal microscopy and cytofluorimetric assay to compare their behavior on culture in 2D monolayers. The obtained results confirmed that these nanocolloids are promising tools for delivering Pt-based drugs.This study was supported by “Tecnopolo di Nanotecnologia e Fotonica per la Medicina di Precisione” (TECNOMED)-FISR/MIUR-CNR: delibera CIPE n.3449 del 7/08/2017, CUP: B83B17000010001; “Tecnopolo per la Medicina di precisione” (TecnoMed Puglia) - Regione Puglia: DGR n.2117 del 21/11/2018, CUP: B84I18000540002.openViviana Vergaro; Francesca Baldassarre; Federica De Castro; Danilo Migoni; Maria Michela Dell’Anna; Piero Mastrorilli; Francesco Paolo Fanizzi; Giuseppe CiccarellaVergaro, Viviana; Baldassarre, Francesca; DE CASTRO, Federica; Danilo, Migoni; Michela Dell’Anna, Maria; Mastrorilli, Piero; Fanizzi, Francesco Paolo; Ciccarella, Giusepp

Enhancing Dye-Sensitized Solar Cell Performances by Molecular Engineering: Highly Efficient π-Extended Organic Sensitizers

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