Gold nanoparticles protected by fluorinated ligands: Syntheses, properties and applications

The development of fluorinated gold nanoparticles is presently arising and increasing attention across several fields of nanotechnology. The synthetic approaches evolved over time from the use of almost perfluorinated alkanethiols and perfluorinated arylthiols to amphiphilic fluorinated thiols capable of ensuring solubility in conventional organic solvents and water. The interest in these systems stems from the unique properties of both nanosized and fluorous compounds. In perspective, the development of our understanding of the fluorophilic interactions at the nanoscale will allow to devise novel strategies for self-assembly, molecular recognition and new materials for biomedical applications. In this paper we present, through selected examples, the potential of fluorous ligands in the synthesis of gold nanoparticles and the relevance of mastering the properties of these systems in the development of new materials

Efficient and Mild Microwave-Assisted Stepwise Functionalization of Naphthalenediimide with α-Amino Acids

Microwave dielectric heating proved to be an efficient method for the one-pot and stepwise syntheses of symmetrical and unsymmetrical naphthalenediimide derivatives of α-amino acids. Acid-labile side chain protecting groups are stable under the reaction conditions; protection of the α-carboxylic group is not required. The stepwise condensation of different amino acids resulted in high yields of unsymmetrical naphthalenediimides. The reaction proceeds without racemization and is essentially quantitative.

Highly Efficient Darzens Reactions Mediated by Phosphazene Bases under Mild Conditions

The highly basic and poorly nucleophilic phosphazene base P-1-t-Bu promotes the Darzens condensation of alpha-halo esters with aromatic aldehydes affording alpha,beta-epoxy esters in nearly quantitative yields under mild conditions and in short reaction times. The more basic P-4-t-Bu phosphazene was found useful with low reactivity aldehydes. These reactions can be performed in aprotic organic solvents of low polarity, thus minimizing the hydrolysis of alpha,beta-epoxy esters which often accompanies the base-promoted Darzens condensations

Organic chemistry laboratories during the pandemic at the University of Trieste

Patrizia Nitti, Paolo Pengo, "Laboratori di chimica organica durante la pandemia all’Università di Trieste/Organic chemistry laboratories during the pandemic at the University of Trieste", in: QuaderniCIRD, 26 (2023), EUT Edizioni Università di Trieste, Trieste, 2023, pp.Sunday, 23rd February, 2020. I was at Manchester airport (UK) travelling back to Trieste after a short visit to my daughter, who lives in Sheffield (UK). I had just passed the security checks when I received a message from one of my colleagues, saying: «I don’t think that tomorrow you will have exams, the Rector has suspended all teaching activities because of the Coronavirus...». It was the beginning of an outbreak of global proportions. We explain here how the courses of “Laboratory of Organic Chemistry II” and “Laboratory of Organic Chemistry III” of the bachelor’s degree in Chemistry at the Department of Chemical and Pharmaceutical Sciences of the University of Trieste were designed and carried out between April and May 2020, during the pandemic and the lockdown, and how they were evaluated by the students.Domenica 23 febbraio 2020 ero all’aeroporto di Manchester (Regno Unito) in viaggio di ritorno a Trieste dopo una breve visita a mia figlia, che vive a Sheffield (Regno Unito). Avevo appena superato i controlli di sicurezza quando ho ricevuto un messaggio da un mio collega che diceva: «Non credo che domani avrete gli esami, il Rettore ha sospeso tutte le attività didattiche a causa del Coronavirus...». Fu l’inizio di un’epidemia di proporzioni globali. In questo contributo si illustra come sono stati progettati e svolti tra aprile e maggio 2020 i corsi di “Laboratorio di Chimica Organica II” e “Laboratorio di Chimica Organica III” della Laurea triennale in Chimica presso il Dipartimento di Scienze Chimiche e Farmaceutiche dell’Università degli Studi di Trieste durante la pandemia e il lockdown e come sono stati successivamente valutati dagli studenti che li hanno frequentati

clinical conundrums in antithrombotic therapy management a delphi consensus panel

Abstract Background Anticoagulants are recommended for the prevention of stroke/systemic embolism for most patients with atrial fibrillation (AF) and for the treatment of patients with venous thromboembolism (VTE). Regulatory-driven randomized trials, however, typically exclude extreme patient scenarios involving, for instance, severe bleeding, ischaemic risk, frailty or renal impairment, despite their common occurrence in clinical practice. Uncertainty in the management of such cases leads to a high degree of variability in therapeutic approaches. Consensus conferences or panels may provide insights and help bridge the gaps that separate clinical guidelines from real-world practice. In the present study, a description of challenging AF and VTE patients was submitted to a large panel of experts to investigate areas of common or divergent management. Method A modified-Delphi method was used to obtain consensus among 178 Italian AF and VTE specialists. A questionnaire was sent on the appropriateness of anticoagulant therapy in AF and VTE cases, including CHA 2 DS 2 -VASc=1, comorbid coronary artery disease, frailty, advanced age, risk of falling, prior haemorrhagic stroke, and low- or intermediate-risk pulmonary embolism. Strategies to improve guideline adherence were also investigated. Results All participants completed the questionnaire. Consensus was reached on many, but not all cases, leaving uncertainty on some debated topics (conundrums) where decisions are unsupported by clinical studies or driven by controversial results. Conclusions The indications emerging from this large panel of experts may help guide the management of challenging AF or VTE cases. Studies are needed addressing treatment options in those cases for whom no consensus was reached

Toward fractioning of isomers through binding-induced acceleration of azobenzene switching

The E/Z isomerization process of a uracil-azobenzene derivative in which the nucleobase is conjugated to a phenyldiazene tail is studied in view of its ability to form triply-H-bonded complexes with a suitably complementary 2,6-diacetylamino-4-pyridine ligand. UV-Vis and 1H-NMR investigations of the photochemical and thermal isomerization kinetics show that the thermal Z→E interconversion is four-fold accelerated upon formation of the H-bonded complex. DFT calculations show that the formation of triple H-bonds triggers a significant elongation of the N=N double bond, caused by an increase of its πg∗ antibonding character. This results in a reduction of the N=N torsional barrier and thus in accelerated thermal Z→E isomerization. Combined with light controlled E→Z isomerization this enables controllable fractional tuning of the two configurational isomers

Routes to the preparation of mixed monolayers of fluorinated and hydrogenated alkanethiolates grafted on the surface of gold nanoparticles

The use of binary blends of hydrogenated and fluorinated alkanethiolates represents an interesting approach to the construction of anisotropic hybrid organic-inorganic nanoparticles since the fluorinated and hydrogenated components are expected to self-sort on the nanoparticle surface because of their reciprocal phobicity. These mixed monolayers are therefore strongly non-ideal binary systems. The synthetic routes we explored to achieve mixed monolayer gold nanoparticles displaying hydrogenated and fluorinated ligands clearly show that the final monolayer composition is a non-linear function of the initial reaction mixture. Our data suggest that, under certain geometrical constraints, nucleation and growth of fluorinated domains could be the initial event in the formation of these mixed monolayers. The onset of domain formation depends on the structure of the fluorinated and hydrogenated species. The solubility of the mixed monolayer nanoparticles displayed a marked discontinuity as a function of the monolayer composition. When the fluorinated component content is small, the nanoparticle systems are fully soluble in chloroform, at intermediate content the nanoparticles become soluble in hexane and eventually they become soluble in fluorinated solvents only. The ranges of monolayer compositions in which the solubility transitions are observed depend on the nature of the thiols composing the monolayer

Patchy and Janus Nanoparticles by Self-Organization of Mixtures of Fluorinated and Hydrogenated Alkanethiolates on the Surface of a Gold Core

The spontaneous self-organization of dissimilar ligands on the surface of metal nanoparticles is a very appealing approach to obtain anisotropic "spherical". systems. In addition to differences in ligand length and end groups, a further thermodynamic driving force to control the self-assembled monolayer organization may become available if the ligands are inherently immiscible, as is the case of hydrogenated (H-) and fluorinated (F-) species. Here, we validate the viability of this approach by combining F-19 NMR experiments and multiscale molecular simulations on large sets of mixed-monolayer-protected gold nanoparticles (NPs). The phase segregation of blends of F- and H-thiolates grafted on the surface of gold NPs allows a straightforward approach to patterned mixed monolayers, with the shapes of the monolayer domains being encoded in the structure of the F/H-thiolate ligands. The results obtained from this comprehensive study offer molecular design rules to achieve a precise control of inorganic nanoparticles protected by specifically patterned monolayers

Reduced Tiara-like Palladium Complex for Suzuki Cross-Coupling Reactions

The design of highly active and structurally well-defined catalysts has become a crucial issue for heterogeneous catalysed reactions while reducing the amount of catalyst employed. Beside conventional synthetic routes, the employment of polynuclear transition metal complexes as catalysts or catalyst precursors has progressively intercepted a growing interest. These well-defined species promise to deliver catalytic systems where a strict control on the nuclearity allows to improve the catalytic performance while reducing the active phase loading. This study describes the development of a highly active and reusable palladium-based catalyst on alumina (Pd8/Al2O3) for Suzuki cross-coupling reactions. An octanuclear tiara-like palladium complex was selected as active phase precursor to give isolated Pd-clusters of ca. 1 nm in size on Al2O3. The catalyst was thoroughly characterised by several complementary techniques to assess its structural and chemical nature. The high specific activity of the catalyst has allowed to carry out the cross-coupling reaction in 30 min using only 0.12 mol % of Pd loading under very mild and green reaction conditions. Screening of various substrates and selectivity tests, combined with recycling and benchmarking experiments, have been used to highlight the great potentialities of this new Pd8/Al2O3 catalyst. © 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH