1,392 research outputs found
Materiali Organici p-Coniugati Chirali
No full textThe research conducted during the Ph.D. is divided into two main lines, both joined together by the key role played by chiral p-conjugated synthons within novel supramolecular systems. The first part involved the synthesis and utilization of 1,1'-binaphthylic derivatives. Starting from them, new chiral molecular cages capable of acting as chiroptical sensors for an important radioactive environmental pollutant (99TcO4-) were synthesized and studied (Chapter 2, in collaboration with Prof. Valeria Amendola, Pavia). The interaction between the cage and anion, mainly caused by hydrogen bonds, is transduced into a large modulation of the chiroptical signal.1 In chapter 3, in collaboration with Prof. Dominique Armspach (University of Strasbourg), new cyclodextrins "capped" with atropoisomeric 1,1'-biphenylic systems were synthesized. The process of chirality transfer from cyclodextrin (point chirality) to the biphenyl moiety (axial chirality) was investigated in detail, both in solution and in the solid state. The key role of intramolecular hydrogen bonds responsible for the efficient chirality transfer was demonstrated, and finally the temperature-dependent chiroptical activity of such systems was studied. The second research line involved the synthesis and utilization of triptycene synthons.2 New triptycene-fused quinacridone dyes were synthesized and studied, following our general strategy of merging nonplanar p-conjugated synthons and high-performance pigments (Chapter 4). Subsequently, after several unsuccessful attempts to resolve crucial chiral triptycene intermediates, such resolution was achieved by using chiral HPLC, in collaboration with the research group of Prof. Roberto Cirilli (chapter 5).2 Finally (chapter 6), in collaboration with Prof. Amendola's research group, new triptycene-fused benzimidazoles were synthesized. These derivatives were successfully used for the self-assembly via hydrogen bonding of chiral polymers consisting of triptycene-benzimidazoles and chiral (non-chromophoric) carboxylic acids. In this case, chirality is transferred via non-covalent interactions from simple chiral carboxylic acids to an equilibrating mixture (resulting from tautomeric equilibria) of triptycene/benzimidazole isomers. The resulting supramolecular structures proved to be capable of emitting circularly polarized light with glum dissymmetry factors up to 6*10-3.
References and Pubblications
1) R. Mobili ±, G. Preda ±,S. La Cognata, L. Toma, D. Pasini, V. Amendola, Chem. Commun., 2022, 58, 3897–3900.
2) G. Preda, A. Nitti, D. Pasini, ChemistryOpen 2020, 9, 719–727.
3) A. Rosetti, G. Preda, C. Villani, M. Pierini, D. Pasini, R. Cirilli, Chirality, 2021; 33, 883–890.La ricerca condotta durante il dottorato è divisa in due filoni principali, entrambi accumunati dal ruolo chiave rivestito da sintoni -coniugati chirali all’interno nuovi sistemi supramolecolari. Il primo filone ha riguardato la sintesi e l’utilizzo di derivati 1,1’-binaphthylic. A partire da essi, sono stati sintetizzati e studiati nuove gabbie molecolari in grado agire come sensori chirottici per un importante inquinante ambientale radioattivo (99TcO4-) (capitolo 2, in collaborazione con la Prof.ssa Valeria Amendola, Pavia). L’interazione tra gabbia e anione, causata principalmente da legami a idrogeno, viene tradotta in ampio cambiamento del segnale (chir)ottico.1 Nel capitolo successivo, in collaborazione con il Prof. Dominique Armspach (Università di Strasburgo) sono stati sintetizzate ciclodestrine “cappate” con sistemi atropoisomerici di tipo 1,1’-bifenilico. Il processo di trasferimento di chiralità dalla ciclodestrina (chiralità puntuale) alla prozione bifenilica (chiralità assiale) è stato studiato in dettaglio, sia in soluzione che a stato solido. Il ruolo chiave dei legami legami idrogeno intramolecolari responsabili dell’efficiente trasferimento di chiralità è stato dimostrato ed infine la attività chirottica temperatura dipendente di tali sistemi è stata studiata. Il secondo filone di ricerca ha riguardato la sintesi e l’utilizzo di sintoni tripticenici.2 Sono stati sintetizzati e studiati nuovi coloranti triptycene-fused quinacridone, seguendo la nostra strategia generale che prevede la fusione di sintoni -coniugati non planari e pigmenti ad altre prestazioni. Successivamente (capitolo 5), dopo diversi tentativi di risoluzione falliti, la risoluzione di cruciali sintoni tripticenici chirali è stata ottenuta mediante utilizzo di HPLC chirale, in collaborazione con il gruppo di ricerca del Prof. Roberto Cirilli (Università La Sapienza, Roma).3 Infine, in collaborazione con il gruppo di ricerca della Prof. Amendola, sono stati sintetizzati nuovi derivati di tripticene/benzimidazolo. Tali derivati sono stati impiegati con successo per l’autoassemblaggio via legame a idrogeno di polimeri chirali costituiti da derivati tripticene/benzimidazolo e acidi carbossilici chirali (non cromoforici). In questo caso la chiralità viene trasferita tramite interazioni non covalenti da semplici acidi carbossibili chirali a una miscela in equilibrio (derivante da equilibri tauromerici) di isomeri tripticene/benzimidazolo. Le strutture supramolecoalri così ottenute si sono rivelate in grado emettere luce polarizzata circolarmente con fattori di disimmetria glum fino a 6*10-3.
Referenze e Pubblicazioni
1) R. Mobili ±, G. Preda ±,S. La Cognata, L. Toma, D. Pasini, V. Amendola, Chem. Commun., 2022, 58, 3897–3900.
2) G. Preda, A. Nitti, D. Pasini, ChemistryOpen 2020, 9, 719–727.
3) A. Rosetti, G. Preda, C. Villani, M. Pierini, D. Pasini, R. Cirilli, Chirality, 2021; 33, 883–890
PREDA: An R-package to identify regional variations in genomic data
No full textChromosomal patterns of genomic signals represent molecular ngerprints that may reveal how the local structural organization of a genome impacts the functional control mechanisms. Thus, the integrative analysis of multiple sources of genomic data and information deepens the resolution and enhances the interpretation of stand-alone high-throughput data. In this note, we present PREDA (Position RElated Data Analysis), an R package for detecting regional variations in genomics data. PREDA identies relevant chromosomal patterns in high-throughput data using a smoothing approach that accounts for distance and density variability of genomics features. Custom-designed data structures allow efciently managing diverse signals in different genomes. A variety of smoothing functions and statistics empower exible and robust workows. The modularity of package design allows an easy deployment of custom analytical pipelines. Tabular and graphical representations facilitate downstream biological interpretation of results. © The Author 2011. Published by Oxford University Press. All rights reserved
L'impatto della Direttiva Eurosim sulla struttura e sul funzionamento del mercato mobiliare italiano
No full textIn Collana"Direttiva Eurosim,la borsa e le banche" - Bancaria Editrice, Rom
Surface Reconstruction From Point Cloud using a Semi-Lagrangian Scheme with Local Interpolator
No full textWe propose a level set method to reconstruct unknown surfaces from point clouds, without assuming that the connections between points are known. We consider a variational formulation with a curvature constraint that minimizes the surface area weighted by the distance of the surface from the point cloud. More precisely we solve an equivalent advection–diffusion equation that governs the evolution of an initial surface described implicitly by a level set function. Among all the possible representations, we aim to compute the signed distance function at least in the vicinity of the reconstructed surface. The numerical method for the approximation of the solution is based on a semi-Lagrangian scheme coupled with a local interpolator. In particular, we resort to a multi-linear interpolator and to a Weighted Essentially Non-oscillatory one, to improve the accuracy of the reconstruction. An analysis of the parameters employed in the model is given, focusing in particular on the effect of the curvature regularization, and on the presence of noisy data. Special attention has been paid to the localization of the method and to the development of fast algorithms that run in parallel, resulting in faster reconstruction and thus the opportunity to easily improve the resolution. Numerical tests in two and three dimensions are presented to evaluate the quality of the reconstruction and the efficiency of the algorithm in terms of computational time
Perché sono europeo. Studi per Giulio Guderzo
No full textStudi offerti a Giulio Guderzo relativi alla sua esperienza scientifica, didattica e di ricerca intorno ai temi della costruzione dell'Unione europea dall'età moderna ai giorni nostr
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