Search results for " Synthesis"
showing 10 items of 1625 documents
Broadband, site selective and time resolved photoluminescence spectroscopic studies of finely size-modulated Y2O3:Eu3+ phosphors synthesized by a com…
2014
Undoped and Eu3+-doped cubic yttria (Y2O3) nanophosphors of good crystallinity, with selective particle sizes ranging between 6 and 37 nm and showing narrow size distributions, have been synthesized by a complex-based precursor solution method. The systematic size tuning has been evidenced by transmission electron microscopy, X-ray diffraction, and Raman scattering measurements. Furthermore, size-modulated properties of Eu3+ ions have been correlated with the local structure of Eu3+ ion in different sized Y2O3:Eu3+ nanophosphors by means of steady-state and time-resolved site-selective laser spectroscopies. Time-resolved site-selective excitation measurements performed in the 7F0 ¿ 5D0 peak…
Application of 2D Non-Graphene Materials and 2D Oxide Nanostructures for Biosensing Technology
2016
The discovery of graphene and its unique properties has inspired researchers to try to invent other two-dimensional (2D) materials. After considerable research effort, a distinct "beyond graphene" domain has been established, comprising the library of non-graphene 2D materials. It is significant that some 2D non-graphene materials possess solid advantages over their predecessor, such as having a direct band gap, and therefore are highly promising for a number of applications. These applications are not limited to nano- and opto-electronics, but have a strong potential in biosensing technologies, as one example. However, since most of the 2D non-graphene materials have been newly discovered,…
Spark plasma synthesis from mechanically activated powders: a versatile route for producing dense nanostructured iron aluminides
2004
Abstract The possibility of mechanically activated spark plasma sintering (MASPS) to perform simultaneously within a very short period of time the synthesis and the consolidation of nanophase iron aluminide from mechanically activated powders of Fe and Al in two different ratio (Fe53 at.% and Fe60 at.%) were confirmed in this work.
Selenium and tellurium nanomaterials
2018
Abstract Over the last 40 years, the rapid and exponential growth of nanotechnology led to the development of various synthesis methodologies to generate nanomaterials different in size, shape and composition to be applied in various fields. In particular, nanostructures composed of Selenium (Se) or Tellurium (Te) have attracted increasing interest, due to their intermediate nature between metallic and non-metallic elements, being defined as metalloids. Indeed, this key shared feature of Se and Te allows us the use of their compounds in a variety of applications fields, such as for manufacturing photocells, photographic exposure meters, piezoelectric devices, and thermoelectric materials, t…
Natural eutectogels: sustainable catalytic systems for C–C bond formation reactions
2021
Natural eutecto gels were prepared combining properties of amino acids with the ones of deep eutectic solvents. Soft materials obtained were fully characterised determining the gel-sol transition temperatures and analysing mechanical and morphological features through rheological measurements and polarised optical microscopy. All eutecto gels were tested as catalytic reaction media for the enantioselective aldol reaction and, the best performing one was also used to carry out the Michael addition. In both cases, eutecto gels proved to have a great potential as sustainable reaction media, allowing to perform processes under mild conditions, obtaining excellent yields and, in some cases, also…
Total Synthesis of epi-Trichosetin.
2018
The natural 3-decalinoyltetramic acid epi-trichosetin was synthesized in ten steps starting from ( R)-(+)-citronellal using an intramolecular Diels-Alder reaction and a Lacey-Dieckmann cyclization as the key steps. The use of a 2-nitrobenzyl protecting group resulted in an efficient synthetic endgame. The natural product was obtained in 4.1% overall yield.
‐Aminonitriles: From Sustainable Preparation to Applications in Natural Product Synthesis
2020
Due to their numerous reactivity modes, α-aminonitriles represent versatile and valuable building blocks in organic total synthesis. Since their discovery by Adolph Strecker in 1850, this compound class has seen a wide dissemination in synthetic applications from laboratory to million-ton industrial scale and was extensively used in the syntheses of various classes of natural products. As these compounds provide a multitude of reactivity options, we feel that a broad overview of their multiple reaction modes may reveal less familiar opportunities for successful total synthesis planning. This personal account article will thus focus on α-aminonitriles used as key intermediates in selected na…
A Decade of Advance in the Asymmetric Vinylogous Mannich Reaction
2016
When the principle of vinylogy is applied to imines as electrophiles, the so-called vinylogous Mannich reaction (VMR), γ-aminocarbonyl (such as butenolides) and β-aminocarbonyl compounds are generated in a very efficient manner. The asymmetric version of this vinylogous Mannich reaction gives access to highly functionalized chiral synthons, which are suitable for further transformations. The versatility of this methodology is exemplified with the synthesis of several alkaloids and natural products. 1 Introduction 2 Asymmetric Vinylogous Mannich Reactions (VMR) with 2-Silyloxyfurans and 2-Silyloxypyrroles 3 Asymmetric VMR with Acyclic Silyl Dienolates and Silyl Dienol Ketene Acetals 4 Asymm…
Asymmetric Intramolecular Aza-Michael Reaction in Desymmetrization Processes. Total Synthesis of Hippodamine and epi-Hippodamine
2015
The use of chiral sulfinyl amines both as nucleophilic nitrogen sources and chiral inducers has been described for the first time in a desymmetrization-type process involving an intramolecular aza-Michael reaction. The resulting product was employed as an advanced intermediate in the total synthesis of the natural product hippodamine and epi-hippodamine, taking advantage of the special symmetry of these molecules. In addition, this is the first asymmetric total synthesis of epi-hippodamine.
ChemInform Abstract: Total Synthesis of (+)-Phenguignardic Acid, a Phytotoxic Metabolite of Guignardia bidwellii
2014
(+)-Phenguignardic acid, a phytotoxic metabolite of the grape black rot fungus Guignardia bidwellii was synthesized, as well as its enantiomer, in eight steps from (R)-phenyllactic acid and 3-phenylprop-2-yn-1-ol. The formation of the carboxylate at a late stage, to avoid enolization of the precursor used in the central acetalization step, proved to be crucial. The synthesis of the natural product allowed the unabiguous assignment of its hitherto unknown absolute configuration.