1,721,119 research outputs found
Activation of small molecules by an amphiphilic phosphinito bridged Pt(I)-Pt(I) complex
No full textThe complex [(PHCy2)Pt(μ-PCy2){κ2P,O-μ-P(O)Cy2}Pt(PHCy2)](Pt-Pt) (1) constitutes a rare example of unsymmetrical phosphinito diplatinum species that, due to the simultaneous presence of a soft binding atom (P) linked to a hard one (O), undergoes smooth reaction with nucleophiles, electrophiles, dihydrogen and terminal alkynes. The tested nucleophiles were PHCy2, PCy3, P(S)HCy2 and CO, whereas the investigated electrophiles were several Brønsted acids as well as metal based species (AuCl, Au(PPh3)Cl, AgX, X = OTf, BF4, ClO4, Cl, (PPh3)OTf). The alkynes used in reaction with 1 were (trimethylsilyl)acetylene and phenylacetylene. In all cases the skeletal framework was preserved and in one case (reaction with diluted HF) dimerization led to a tetranuclear species
Physical Simulation for Studying the Effect of Thermal Cycles Peak Temperature on Intermetallic Formation at Triclad® Joints Interface
No full textAluminum/steel structural transition joints (STJs) are extensively used in the shipbuilding industry. This is because they offer the advantage of effectively combining these two materials, leading to substantial weight savings while maximizing their individual strengths. The research target is to evaluate the metallurgical properties of explosion-welded Triclad aluminum/steel STJs under different peak temperature thermal cycles. Herein, the Gleeble physical simulator to apply thermal cycles on Triclad specimens with appropriate geometry is exploited. The results highlight that the peak temperature significantly affects the extension, thickness, and chemical composition of the intermetallic layer at the Fe/Al interface. An increase in peak temperature results in an increase in both the extension and thickness of the intermetalliclayer. The increase in peak temperature leads also to the formation of intermetallic compounds with a higher percentage of aluminum
Platinum and palladium promoted couplings of bridging PPh2– with terminally bonded ligands
No full textThe coupling of bridging diphenylphosphanides (PPh2–) with terminally bonded anionic ligands (L–) that takes place onto polynuclear Pt or Pd systems is reviewed. The two-electron reduction that accompanies the PPh2/L coupling generally implicates a M(IV) centre but there are examples where the redox process involves a M(II),M(II) system that is transformed into a M(I),M(I) containing product (M = Pd, Pt). The discussed coupling reactions end up with formation of new ligands which, depending on the nature of L–, display P–E bonds with E=C, N, O, P, S and I.Peer reviewe
Study of PMMA materials for a digital optical module
No full textThis work illustrates the material characterization to realize of a prototypal polymeric cover of a Digital Optical Module for the Hyper-Kamiokande neutrino experiment. The cover was made of a high transmittance poly-methyl methacrylate (PMMA), used as a glass substitute. The main objective of the present research is to investigate the structural and optical properties of PMMA, evaluating the respect of the project specification
Studio di coating ibridi contenenti alizarina per lo sviluppo di sensori di pH indossabili
No full textNegli ultimi decenni, il sempre più crescente interesse verso il monitoraggio in real-time di parametri fisiologici o ambientali ha spinto il mondo scientifico ad incentivare la ricerca sui cosiddetti “tessuti intelligenti”, cioè trasduttori indossabili sensibili a specifici analiti. In tale ambito, molecole le cui proprietà fisiche, chimiche o elettrochimiche cambiano reversibilmente in risposta a uno o più stimoli esterni sono di particolare interesse, nonché le tecnologie che consentono di integrarle nei polimeri ad uso tessile. Tra queste ultime, la tecnica sol-gel è tra le più sostenibili, promettenti e versatili e consente di immobilizzare in maniera covalente o mediante interazioni deboli, molecole funzionali organiche attraverso reazioni di idrolisi e condensazione di precursori metallici [1,2,3]. Film polimerici ibridi con struttura tridimensionale caratterizzati da diverso spessore, porosità, trasparenza ottica e permeabilità protonica possono essere realizzati modulando i parametri delle reazioni coinvolte [1]. Le superfici tessili trattate con rivestimenti sol-gel contenenti molecole alocromiche, altrimenti non immobilizzabili sui materiali, possono ad esempio essere utilizzate come sonde di pH per sensori indossabili a diretto contatto con la pelle anche grazie alla non- citotossicità della matrice sol-gel [1,2]. Pertanto, tali sensori possono essere impiegati per il monitoraggio continuo e non invasivo del pH del sudore umano, fornendo utili informazioni riguardo lo stato di salute dell’individuo [1,3]. In questo lavoro, attraverso la tecnica sol-gel è stato sintetizzato un film ibrido sensibile alle variazioni di pH, funzionalizzando covalentemente il rosso alizarina S [4] con un alcossisilano, ottenendo dopo la deposizione su polimeri ad uso tessile, sensori di pH indossabili caratterizzati da reversibilità e ripetibilità
Synthesis and catalytic activity of organometallic complexes of palladium(II) with bis-phosphine monosulfides towards ethylene/CO copolymerization
No full textThe neutral and cationic complexes of formula [(CH3)(Cl)Pd(P∧P(S))] and [(CH3)(CH3CN)Pd(P∧P(S))]BF4 [P∧P(S)=Ph2PCH2P(S)Ph2 (dppmS), Ph2P(CH2)2P(S)Ph2 (dppeS)] have been synthesized, characterized and tested as catalysts in the alternating copolymerization of ethylene and carbon monoxide. Both neutral and cationic Pd(II) complexes show η2-(P,S) coordination and cationic complexes exhibit moderate activity
Aryl 5-substitution of a phenyl-pyridine based ligand as a viable way to influence the opto-electronic properties of bis-cyclometalated Ir(III) heteroleptic complexes
No full textThis manuscript reports on the synthesis, the photophysical study and the electroluminescent properties of a series of heteroleptic cyclometalated iridium(III) complexes based on 2,5-diaryl-pyridines as (CN)-N-boolean AND cyclometalating ligands and acetylacetonate as ancillary ligand. The complexes were characterised by elemental analysis, ESI-MS, multinuclear NMR, TGA and electrochemistry. Their optical properties were investigated by UV-Vis and photoluminescence. DFT and TD-DFT calculations provided further insights into the effects of the 5-aryl substitution on the electronic and photophysical properties of the new complexes. The presence of suitable pi-extended ligands exerts a beneficial effect on the performances of the corresponding solution-processed light-emitting diodes, leading to a maximum brightness of 10 620 cd m(-2) at a current efficiency of 10.0 cd A(-1)
Non-targeted NMR approach to unveil and promote the biodiversity of globe artichoke in the Mediterranean area
No full textThe globe artichoke is an important constituent of the Mediterranean diet, being rich in bioactive compounds.
Artichoke is widely cultivated in Italy, especially in the Apulia region, with a multitude of local varieties. Most of
this genetic material is endangered and its metabolic profile is not yet characterized. In this work, we aimed at
dissecting landrace biodiversity by characterizing the metabolic profiles of edible hearts, i.e. the edible inner part
of the flower heads, and external bracts of artichoke flower heads, using a simple, fast, and affordable analytical
methodology. A non-targeted spectroscopic approach combining NMR experiments and multivariate data
analysis provided a comprehensive picture of the chemical composition of 16 artichoke landraces, some of which
are at risk of extinction. A special focus was on hydrosoluble compounds, contributing to the functional food
value of the artichoke. Moreover, a possible correlation between the metabolic composition and the head color
was established.
Our analyses highlight the nutraceutical diversity and value of newly studied artichoke landraces. Specifically,
the hearts of the deep purple-colored "Nero del Salento" are rich in both mono- and dicaffeoylquinic acids along
with inulin, while the hearts of the green "Bianco di Taranto" and "Centofoglie di Rutigliano" are characterized by
a relatively higher content of dicaffeoylquinic acids. The results can help promote endangered local varieties for
production and commercialization, against the ongoing genetic erosion and loss of crop diversity
Chiral Switchable Catalysts for Dynamic Control of Enantioselectivity
Full text linkAmong the artificial switchable catalysts, those catalysts whose activity can be switched by an external stimulus, only a few cases offer the possibility to develop an effective chiral switchable system that could selectively accelerate the formation of a given enantiomer in one state, whereas in the other state it prefers accelerating the formation of the opposite enantiomer. Many pharmacological investigations need both enantiomers to study potentially different activities and side effects. Thus, chiral switchable catalysts could be a very important tool to achieve this goal because their use will eliminate the need to have the two enantiomers of a designed catalyst. This perspective summarizes, discusses, and emphasizes important developments in the chiral switchable catalyst area for the dynamic control of enantioselectivity, highlighting their advantages and showing some perspectives of this field that is still in its infancy
Improved identification of pollution source attribution by using PAH ratios combined with multivariate statistics
Full text linkPolycyclic aromatic hydrocarbons (PAHs) are contaminants introduced by different pathways in the marine ecosystem, affecting both aquatic and sediment bodies. Identification of their sources is of vital importance for protecting the marine ecosystem. The attribution of the pollution sources is usually made by using diagnostic molecular ratios of PAHs isomers. The reliability of this approach diminishes when PAHs contents are measured far from their original source, for example in water bodies or in bottom sediments. Conventionally the source attribution is based on time consuming univariate methods. In the present work coupling of molecular ratios with advanced supervised statistical techniques was used to increase the accuracy of the PAH source attribution in bottom sediments. Data on PAHs distribution within 5 port areas, with known pattern port activity, were collected. Evaluation of multiple PAHs ratios at once by means of supervised OPLS-DA technique was performed. A robust descriptive and predictive model was set up and successfully validated. The proposed methodology helps identify PAH transport pathways, highlighting interactions between pollution patterns, port activities and coastal land-use supporting decision makers in defining monitoring and mitigation procedures
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