Search results for "macrocycle"
showing 10 items of 50 documents
Construction of green nanostructured heterogeneous catalysts via non-covalent surface decoration of multi-walled carbon nanotubes with Pd(II) complex…
2017
Abstract Green nanostructured heterogeneous catalysts were prepared via a bottom-up strategy. Designed ligands were synthesized joining covalently an electrondeficient pyrimidine residue and a scorpiand azamacrocycle. The desired molecular properties were easily transferred to nanostructured materials in two steps: first, exploiting their spontaneous chemisorption onto multi-walled carbon nanotubes (MWCNTs) via the pyrimidinic moiety in water at room temperature, then, taking advantage of the easy coordination of Pd(II) to the azamacrocycle in the same conditions. An evenly distribution of catalytic centres was obtained on the MWCNTs surface. Catalytic properties of these materials were ass…
Ligands P-stéréogéniques dérivés du calix[4]arène. Synthèses et applications en catalyse asymétrique
2010
We were interested in synthesis of P-stereogenic ligands derived from calix[4]arene and in their application in asymmetric catalysis. Mono et diphosphines were prepared on the upper rim of the macrocyle starting from the mono or dianion of the calix[4]arene and chlorophosphines borane or the oxazaphospholidine borane complex. The best selectivity was obtained by reaction of the dianion with the oxazaphospholidine borane complex leading to a bisaminophosphine borane. After acidolysis with HCl giving the corresponding bischlorophosphine and reaction with organolithium reagents, diphosphines diborane were obtained with good yields (40 à 60 %). X-ray structures of the prepared ligands confirmed…
Porphyrines et tétraazamacrocycles dérivés du DOTA : association de deux ligands pour la chélation de métaux d'intérêt en imagerie médicale multimoda…
2012
The goal of my PhD thesis was to synthesize new molecules, which give access to heterobimetallic complexes with interesting properties for multimodal imaging. In this manuscript, several main points have been studied. The first part of this work concerns the synthesis and characterization of ligands. We describe here the synthesis of five new ligands based on the association of one porphyrin and one or several cyclen derivatives. Those ligands are water-soluble. During the synthesis, we have targeted improvements to our work and developed a new synthetic pathway, which allowed us to obtain one ligand incorporating a porphyrin, a cyclen derivative and a free amine function. This function cou…
A conformationally adaptive macrocycle : conformational complexity and host–guest chemistry of zorb[4]arene
2018
Large amplitude conformational change is one of the features of biomolecular recognition and is also the basis for allosteric effects and signal transduction in functional biological systems. However, synthetic receptors with controllable conformational changes are rare. In this article, we present a thorough study on the host–guest chemistry of a conformationally adaptive macrocycle, namely per-O-ethoxyzorb[4]arene (ZB4). Similar to per-O-ethoxyoxatub[4]arene, ZB4 is capable of accommodating a wide range of organic cations. However, ZB4 does not show large amplitude conformational responses to the electronic substituents on the guests. Instead of a linear free-energy relationship, ZB4 foll…
Spin Cross-Over (SCO) Complex Based on Unsymmetrical Functionalized Triazacyclononane Ligand: Structural Characterization and Magnetic Properties
2019
International audience; The unsymmetrical ligand 1-(2-aminophenyl)-4,7-bis(pyridin-2-ylmethyl)-1,4,7-triazacyclononane (L6) has been prepared and characterized by NMR spectroscopy. The L6 ligand is based on the triazamacrocycle (tacn) ring that is functionalized by two flexible 2-pyridylmethyl and one rigid 2-aminophenyl groups. Reaction of this ligand with Fe(ClO4)2·xH2O led to the complex [Fe(L6)](ClO4)2 (1), which was characterized as the first Fe(II) complex based on the unsymmetrical N-functionalized tacn ligand. The crystal structure revealed a discrete monomeric [FeL6]2+ entity in which the unsymmetrical N-functionalized triazacyclononane molecule (L6) acts as hexadentate ligand. As …
Functionnalized magnetite nanoparticles for bimodal imaging MRI/PET
2015
Functionalized magnetite nanoparticles for bimodal MRI/PET imagingSuperParamagnetic Iron Oxide Nanoparticles (SPIONs) have been widely studied in the biomedical field due to their promising application as nanodrugs and MRI (Magnetic Resonance Imaging) contrast agents (T2). In this study, magnetite (Fe3O4) nanoparticles have been developed for use as contrast agents for MRI/PET (Positron emission tomography) double imaging. First, functionalized stable superparamagnetic SPIONs have been synthesized in a continuous hydrothermal reactor. During the synthesis, hydrophilic agents (citric acid, LDOPA, DHCA and PHA) have been grafted on the surface of the nanoparticles. The functionalization of th…
Hydrogen-ion driven molecular motions in Cu2+-complexes of a ditopic phenanthrolinophane ligand
2004
One of the first kinetic evaluations of a metal ion interchange between the two coordination sites of a ditopic macrocycle is presented. Garcia-España Monsonis, Enrique, Enrique.Garcia-Es@uv.es ; Soriano Soto, Concepción, Concepcion.Soriano@uv.es ; Verdejo Viu, Begoña, Begona.Verdejo@uv.es
Equilibrium and kinetics studies on bibrachial lariat aza-crown/Cu(II) systems reveal different behavior associated with small changes in the structu…
2014
Abstract The high-yield synthesis of a new bibrachial lariat azacrown constituted by two tris(2-aminoethyl)amine (tren) units functionalized in one of its arms with a 4-methylquinoline group linked by dimethylene pyridine spacers (L2) is reported for the first time. The speciation studies show formation of mono- and binuclear Cu2+ complexes of similar stability. Comparisons are established with the complexes formed by the precursor tren-quinoline derivative (L4) and with the previously reported ligands containing naphthalene instead of quinoline as the fluorophore (L1, L3). The kinetics of formation and decomposition of Cu2+ complexes with L1 and L2 has been studied. For L1, the acid-promot…
Gold nanostars co-coated with the Cu(II) complex of a tetraazamacrocyclic ligand
2015
The twelve-membered tetraazamacrocyclic ligand L1 bears an appended lipoic acid unit, whose disulphide ring is an efficient grafting moiety for the surface of gold nanostars (GNS). The GNS that were used featured a localized surface plasmon resonance (LSPR) absorption at ∼800 nm, i.e. in the near infrared (NIR). We investigated different approaches for coating them with the Cu(2+) complex of L1. While the direct reaction of [CuL1](2+) with as-prepared GNS led to aggregation, an initial coating step with polyethyleneglycol-thiol (PEG-SH) was found to be advantageous. Displacement reactions were carried out on pegylated GNS either with [CuL1](2+), directly generating [Cun(L1@GNS)](2n+), or wi…
Hybrid and 2D nanomaterials
2020
International audience; In order to still improve the performances of chemical sensors, numerous hybrid materials were synthesized that combined at least two types of materials reported in the three previous chapters. We will distinguish materials combining macrocyclic molecules with polymers, those in which these molecules are associated to carbonaceous materials, mainly carbon nanotubes (CNTs) and graphene, and organic-inorganic hybrid materials. In this chapter, we will also include 2D materials introduced recently as sensing materials after the huge development of graphene and graphene oxide-based materials.