63 research outputs found
Synthesis of stereodefined 1-aryl(heteroaryl) substituted 1,2-bis(2-bromopyridin-3-yl)ethenes by selective tandem Suzuki-Miyaura Cross-coupling reactions
In this communication we show the preparation of
stereodefined trisubstituted alkenes 2 can be achieved by sequential selective Suzuki-Miyaura
reactions of 2-bromo-3-(2,2-dibromovinyl)pyridines. The potentiality of this
strategy to obtain 5-aryl-1,10-phenanthrolines is also demonstrated
A Solitonic Approach to Holographic Nuclear Physics
We discuss nuclear physics in the Sakai-Sugimoto model in the limit of large
number of colors and large 't Hooft coupling . In this limit the
individual baryons are described by classical solitons whose size is much
smaller than the typical distance at which they settle in a nuclear bound
state. We can thus use the linear approximation outside the instanton cores to
compute the interaction potential. We find the classical geometry of nuclear
bound states for baryon number up to eight. One of the interesting features
that we find is that holographic nuclear physics provides a natural description
for lightly bound states when is large. For the case of two nuclei,
we also find the topology and metric of the manifold of zero modes and,
quantizing it, we find that the ground state can be identified with the
deuteron state. We discuss the relations with other methods in the literature
used to study Skyrmions and holographic nuclear physics. We discuss
and corrections and the challenges to overcome to reach the
phenomenological values to fit with real QCD.Comment: 47 pages, 7 figures. v2: typos correcte
Sintesi ed applicazione in catalisi asimmetrica di derivati piridinici chiarli e non: fenantroline amino-piridine, amino-chinoline e fosfino-piridine
This thesis mainly concerns two important areas of Organic Chemistry: synthesis
and catalysis. In particular our aim was to synthesize new pyridine-based ligands
and to prove their ability in catalytic asymmetric reactions. Moreover we explored
alternative approaches for the synthesis of molecules of interest in different fields
of Chemistry.
We can briefly summarize our results as follows:
1. The achievement of a new procedure to obtain optically active 1-
substituted-1-(pyridin-2-yl)methylamines by diastereoselective reduction of
enantiopure ketimines.
2. The synthesis of new pincer CNN ligands based on the benzo[h]quinoline
framework and catalytic applications of their Ru- and Os-complexes.
3. The development of alternative approaches to the synthesis of 1,10-
phenanthrolines and to compounds that are key-intermediates in the
synthesis of the 1,10-phenanthroline core.
4. The synthesis of a new pyridine-based N-P ligand derived from optically
active camphor and some preliminary results about its activity in catalytic
reactions
Holographic computation of the nucleon-nucleon potential
In this thesis we build a model that can be used to describe baryon dynamics, and in particular we look for an interaction potential between the basic nucleons (proton and neutron). To do that, we follow an approach that mixes two ideas: the description of particles as topological solitons in nonlinear field theory and the Anti de Sitter / Conformal Field Theory (AdS/CFT) correspondence.
We study large N QCD by studying the action of the low energy modes of a string theory. We see that this theory adimts topological solitons called instantons, and quantization of the degrees of freedom of an instantonic field of charge one creates a quantum system with states whose transformation properties and quantum numbers are just right to interpret them as states with a definite rest energy, an impulse, a spin and an isospin degrees of freedom. In this picture, we build a charge two field configuration by gluing together two single charge instanton solutions. Due to the non linearity of the theory, this solution is approximative, and we show that it holds in the limit of large 't Hooft coupling. In those limits, we compute the energy of this field configuration, and interpret the result as a potential of interaction between instantons. This is proposed as a classical potential for baryon interaction, and its structure as infinite sum of Yukawa monopole and dipole interactions is interpreted as the classical analogue of an exchange interaction with a meson mediator. We show how the masses of baryons and mesons can be computed in this model.
After computing the potential, we quantize the coordinates of the two instanton fields, and impose physical constraints to restrict the spectrum of the system. We see that the internal degrees of freedom of the system can be rearranged and interpreted as total spin and isospin of the system, and that they assume only integer values. Among the states that are compatible with our constraints, we find a state with the right angular quantum numbers (spin one and isospin zero) and interpret it as deuteron state. We compute the stability of this state with respect to the splitting in two separated baryons, and make a similar analysis for other low energy states in the spectrum. We comment the large N and large 't Hooft coupling limit, comparing our results with the qualitative predictions of large N QCD, and extrapolate the binding energy of the deuteron
Transfer Hydrogenation from 2-propanol to Acetophenone Catalyzed by [RuCl2(eta6-arene)P] (P = monophosphine) and [Rh(PP)2] (PP = diphosphine, X = Cl-,BF4-) Complexes
The reduction of ketones through homogeneous transfer hydrogenation catalyzed by transition metals is one of the most important routes for obtaining alcohols from carbonyl compounds. The interest of this method increases when opportune catalytic precursors are able to perform the transformation in an asymmetric fashion, generating enantiomerically enriched chiral alcohols. This reaction has been extensively studied in terms of catalysts and variety of substrates. A large amount of information about the possible mechanisms is available nowadays, which has been of high importance for the development of systems with excellent outcomes in terms of conversion, enantioselectivity and Turn Over Frequency. On the other side, many mechanistic aspects are still unclear, especially for those catalytic precursors which have shown only moderate performances in transfer hydeogenation. This is the case of neutral [RuCl2(η6-arene)(P)] and cationic [Rh(PP)2]X (X = anion; P and PP = mono- and bidentate phosphine, respectively) complexes. Herein, a summary of the known information about the Transfer Hydrogenation catalyzed by these complexes is provided with a continuous focus on the more relevant mechanistic features
Behavior of Ternary Mixtures of Hydrogen Bond Acceptors and Donors in Terms of Band Gap Energies
Three ternary mixtures composed by choline chloride (ChCl), ethylene glycol (EG), and a second hydrogen bond donor (HBD) as ethanol (A), 2-propanol (B), and glycerol (C) were studied in terms of composition related to the band gap energy (BGE). A Design of Experiments (DoE) approach, and in particular a Simple Lattice three-components design, was employed for determining the variation of the BGE upon the composition of each system. UV-VIS analysis and subsequent Tauc plot methodology provided the data requested from the DoE, and multivariate statistical analysis revealed a drop of the BGE in correspondence to specific binary compositions for systems A and B. In particular, a BGE of 3.85 eV was registered for the mixtures ChCl/EtOH (1:1) and ChCl/2-propanol (1:1), which represents one of the lowest values ever observed for these systems
Nuova sintesi di 1,10-fenantroline
Proseguendo il nostro lavoro sulla chimica dei derivati fenantrolinici1 abbiamo intrapreso
recentemente uno studio per sintetizzare 1,10-fenantroline a partire da piridine.
Nellâaffrontare questo tema abbiamo pensato sia di prepare un conveniente 1,2-di(3-
piridil)alchene 2 e quindi accoppiare le piridine o alternativamente, sintetizzare
unâappropriata 2,2'-bipiridina 3,3'-disostituita 3 e quindi elaborare i sostituenti in modo da
formare lâanello centrale. In questa conunicazione riportiamo i risultati ottenuti
affrontando questo soggetto
Sintesi stereoselettiva di piridilammine
Ammino piridine chirali hanno dimostrato la loro validitĂ come leganti per la formazione di
complessi metallici utilizzati nella catalisi asimmetrica.
Tra i possibili approcci alla sintesi di questi composti noi abbiamo investigato la riduzione
diastereoselettiva di N-sostituite (p-totil e tert-butil) piridil chetimmine con una serie di
agenti riducenti (NaBH4, L-Selectride, DIBAL, 9-BBN) in diverse condizioni di reazione
European Union legislation overview about used vegetable oils recycling: the spanish and italian case studies
The employment of used vegetable oils (UVOs) as raw materials in key sectors as energy production or bio-lubricant synthesis represents one of the most relevant priorities in the European Union (EU) normative context. In many countries, the development of new production processes based on the circular economy model, as well as the definition of future energy and production targets, involve the utilization of wastes as raw material. In this context, the main currently applied EU regulations are presented and discussed. As in the EU, the general legislative process consists of the definition in each State Member of specific legislation, which transposes the EU indications. Two relevant countries are herein considered: Italy and Spain. Through the analysis of the conditions required in both countries for UVOsâ collection, disposal, storage, and recycling, a wide panorama of the current situation is provided
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