Literatura académica sobre el tema "Structures organiques covalentes"
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Tesis sobre el tema "Structures organiques covalentes":
Gao, Tianyu. "Hétérogénéisation de catalyseurs homogènes à l'aide de matériaux à structures organiques covalentes". Electronic Thesis or Diss., Centrale Lille Institut, 2022. http://www.theses.fr/2022CLIL0016.
Heterogenization of homogeneous catalysts is an effective way to combine highactivity, selectivity and recyclability of catalysts. Covalent Organic Frameworks (COF) are promising organic porous materials that are worthy to be developed as host structures for the heterogenization of homogeneous catalysts, due to their high specific surface area, microporous structure, easy functionalization and high thermal stability. In this thesis, homogeneous phosphotungstic acid (HPW) is heterogenized via encapsulation into the interlayer spacing of 2D COF CIN-1. The heterogenized HPW@CIN-1 catalyst shows high catalytic activities and stability in acid-catalyzed reactions. Heterogenization of homogeneous Ru ions is achieved via tethering by diphenylphosphinobenzaldehyde ligand in the interlayer spacing of CIN-1. The obtained heterogenous Ru@CIN-1 catalyst shows high catalytic activity and stability in model reactions of amination and hydrogenation. In order to widen the application of Ru@CIN-1 catalyst, it has been pyrolyzed under inert atmosphere to obtain Ru supported over carbon nitride material. The obtained novel Ru@g-C3N4 material demonstrates a super performance in electrocatalytic water splitting. Homogeneous Fe(NO3)3 catalyst is heterogenized via grafting to hydroxyl-substituted bidentate 2D COF LZU1 (LZU1-OH). The obtained Fe@LZU1-OH catalyst shows high activity in oxidation model reactions comparable to the parent homogeneous catalyst at high stability
Hachem, Hadi. "Single and multi-component conductors based on metal bis(dithiolene) complexes (M = Ni, Pd, Pt, Au) : overlap interactions and noncovalent interactions". Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1S119.
The aim of this work is the synthesis of novel molecular conductors based on metal bis(chalcogenolene) complexes having a thiazoline (R-thiazdt) or a thiazole (R-tzdt) core. We present in the first part [M(R-thiazdt)2]n complexes, where we studied the effect of several structural changes, (R group, metal atom, metallacycle chalcogen, exocyclic chalcogen), on the redox and optical properties, as well as on the solid state organization and overlap interactions. Here, we synthesized novel single-component and multi-component conductors by electrocrystallization. The single-component conductors act as semiconductors at ambient pressure and turn metallic under pressure. The multi-component conductors act as either Mott insulators or semimetals at ambient pressure. In the second part we describe the synthesis and analysis of (R-tzdt) ligands and [M(R-tzdt)2]n complexes. The main advantage of this family is the ease of introduction of functional groups that serve in providing non-covalent interactions. From this strategy, we successfully managed to elaborate materials showing hydrogen, halogen, and chalcogen bonding. The solution properties of [M(R-tzdt)¬2]- complexes were shown to be similar to those of [M(R-thiazdt)2]- ones. Single-component conductors were obtained for this family, based on nickel (closed shell), and gold (open shell) complexes. These complexes show a semiconducting behavior at ambient pressure
Gahlot, Sapna. "Asterisk-shaped arenes and heteroarenes incorporating sulfur, oxygen and nitrogen : synthesis, structures, photophysics, dynamic and supramolecular covalent chemistry". Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0097.
The content of this thesis focusses on functionalized and branched polysulfurated, polyoxygenated or polycyanated molecular asterisks incorporating either a benzene, a pyridine or a pyrene core. The main objectives are to report the synthesis and the structural, photophysical, supramolecular and covalent dynamic properties of the newly created molecular architectures, in order to develop further uses and applications of them in a near future, toward molecular electronics, imaging, materials and life sciences in general. It also questions some fundamental principles and mechanisms in organic chemistry, notably the reversibility of a main and historical mechanism in organic chemistry: the nucleophilic aromatic substitution, which is known since 1854. At first, the thesis covers new synthetic approaches to functionalize pyrene in its K-region, which has been neglected in spite of the historical importance of pyrenes in optoelectronic sensing, materials and biological sciences. It is followed by the synthesis of various sulfurated, oxygenated and cyanated molecular asterisks with a benzene or pyridine core, in search for a new field in dynamic covalent chemistry (DCC) with arenes and heteroarenes, by implementing and promoting reversible nucleophilic aromatic substitutions in DCC, while at the same time developing all-organic highly phosphorescent smart materials via a rigidity-induced phosphorescence (RIP) phenomena
Para, Franck. "Nanostructures organiques en régimes supra-moléculaire et covalent sur substrats diélectriques : propriétés structurales et optiques". Electronic Thesis or Diss., Aix-Marseille, 2020. http://www.theses.fr/2020AIXM0289.
This thesis deals with the study of the influence of the structure of matter at the atomic scale on its macroscopic properties. Thereto, the IM2NP Nanostructuration team masters the synthesis and characterization of functionalized organic nanostructureson solid surfaces. Specifically, this work focuses on the study of the structural and optical properties of organic nanostructures grown on dielectric single-crystalline alkaly halides substrates under ultra-high vacuum and ambient temperature. Experiments are carried out by non-contact Atomic Force Microscopy (structural properties) and by Differential Reflectance Spectroscopy (optical properties of UV-visible absorption). Two distinct growth regimes have been investigated, with different molecules each. The first system involves supramolecular nanostructures of bis-pyrenes molecules grown on KCl(001) and NaCl(001). The combined study of their structural and optical properties, from the sub-monolayer to the multilayer regime, allows us to quantitatively extract the dielectric function of the layers at the different stages of their growth. The second system deals with a more recent topic in the surface science community, namely on-surface synthesis. In this case, upon adsorption, the molecules bind together covalently, which results in nanostructures that are more cohesive than in the supramolecular regime. We have evidenced the formation of covalent structures by free-radical polymers of dimaleimide on KCl(001) under UV illumination
Berionni, Guillaume. "Synthèse, structure et réactivité de nouveaux composés aromatiques, hétéroaromatiques et de nouvelles oléfines électrophiles : de leur réactivité covalente à leur réactivité supramoléculaire". Versailles-St Quentin en Yvelines, 2009. http://www.theses.fr/2009VERS0055.
This work highlights the multifaceted covalent and supramolecular reactivity of strongly electron-deficient ariomatic, heteroaromatic and olefinic structures. In a first chapter, the synthesis, the functionnalisation and the N-alkylation of various heteroaromatics substituted by electron withdrawing groups are described. New original nitroolefinic moieties and related Michael acceptors were synthesized. Concomitantly, the characterization of all compounds has been carried out using, in particular, mass spectrometry, NMR and X-ray crystallography. The second chapter reports on the characterization of a number of important reaction intermediates such as zwitterions, charge transfer complexes and Meisenheimer complexes in a variety of Diels-Alder r"eactions, Michael additions and nucleophilic aromatic substitutions. Thermodynamic and kinetic investigations as well as DFT calculations have allowed the ranking of a large set of electrophiles on well-established experimental and theorical reactivity scales. Evidence is thus provided that most of our heterocyclic nitro derivatives exhibit an exceptional electrophilic character, as compared with traditional electron deficient aromatic like trinitrobenzene. The last part describes the electrochimical behaviour and the study of thze electron accepting strength of our new heteroaromatics. Their propensity to form non covalent molecular complexes with strong donors such as anthracenes and tetrathiafulvalenes is described for the first time
Imani, Zeynab. "Le rôle d’interactions N-H···S proximales dans des peptides". Thesis, université Paris-Saclay, 2021. http://www.theses.fr/2021UPASF015.
Non-covalent interactions play a key role in chemical biology phenomena such as the stabilization of protein tertiary and quaternary structure or protein-protein and protein-substrate recognition. Among these interactions, the classical amide-type NH···O=C hydrogen bond has been thoroughly studied. The study of other types of non-covalent interactions implicating peptide backbone NH groups is much rarer. This work focused on the impact of NH···S hydrogen bonding on the conformational preferences of thioether amino acid residues and their short oligomers. A panel of capped derivatives of the following non-canonical sulfur-containing amino acids was prepared: Cys(Me) (acyclic), Attc (thietane), Atlc (thiolane), Atc (thiane). These derivatives were characterized computationally, by IR/UV double resonance laser spectroscopy in the gas phase, by IR and NMR spectroscopy in solution, and in the solid state. We demonstrated the concomitant existence of inter-residue C6ˠ NH···S hydrogen bonds and C5 NH···O=C interactions in each of these four compounds. This combined stabilizing feature was also prevalent in Attc oligomers. A different intra-residue C5ˠ NH···S hydrogen bond was characterized in short oligomers of Atlc and Atc, in some cases associated with a ˠ-turn NH···O=C interaction. The significance of NH···S bonding in the combined C5-C6ˠ structural feature of Attc was evaluated by comparison with capped derivatives of other four-membered ring amino acids: Ac4c (cyclobutane), Aatc(Me) (azetidine), Aotc (oxetane). The C5–C6ˠ feature was present in the three heterocyclic residues: comparison of their IR spectra in gas phase and in solution, aided by theoretical calculations, allowed us to identify an increasing strength of NH···X hydrogen bonding from X=O to X=S to X=N