Les poly-tétraazamacrocycles (Synthèse via un intermédiaire bis-aminal - Complexation d'ions de métaux de transition et de lanthanides)

La thèse se divise en deux parties : La première est consacrée à la synthèse de composés bis tétraazamacrocycliques, symétriques ou non, via des dérivés bis aminals du cyclam et du cyclen. La méthode est étendue aux tris macrocycles linéaires et cycliques. La deuxième partie étudie les complexes des composés précédents avec les sels des métaux de transition : le cuivre (II) et le nickel (II). Ces complexes sont étudiés par voltammétrie cyclique et par RPE afin de mettre en évidence les éventuelles interactions entre les cations métalliques. Quelques bis-tétraazamacrocycles ont été modifiés par l'adjonction de bras acétate afin de complexer le gadolinium (III). Les composés ainsi obtenus présentent des performances supérieures à celles du DOTA Gd(III) comme agents de contraste en imagerie médicale par résonance magnétique.This work is divided into two parts : The first part is dedicated to synthesis of symmetrical or unsymmetrical bis tetraazamacrocyclic compounds, via bis aminal derivatives of cyclam and cyclen. This method is extended to linear and cyclic tris macrocyclic compounds. In the second part, we report the complexation of these poly tetraazamacrocycles with transition metal ions : Cu(II) and Ni(II). The complexes have been fully investigated by cyclic voltammetry and EPR to determine possible interactions between the metal centres. Carboxylic pendant arms have been grafted on some bis tetraazamacrocycles to coordinate Gd (III). Resulting complexes present better properties that DOTA Gd(III) as nuclear magnetic resonance imaging (MRI) contrast agents.BREST-BU Droit-Sciences-Sports (290192103) / SudocSudocFranceF

Bismuth(III) complexes with tetra-pyridylmethyl-cyclen

International audienceBimuth(III) complexes with 1,4,7,10-tetrakis(2-pyridylmethyl)-1,4,7,10-tetraazacyclododecane have been prepared in dichloromethane and ethanol and investigated. These complexes have been characterized structurally by X-ray diffraction and NMR-2D studies. They present different coordination scheme depending on the reaction conditions: according to the nature of solvent, bismuth coordinates from six to eight nitrogen atoms and forms in the solid state a chiral structure which is maintained in solution

Bismuth (III) coordination to cyclen and cyclam bearing four appended groups

International audienceThe synthesis of new cyclam and cyclen derivatives (respectively L1 and L2), able to efficiently coordinate to Bi(III) are presented here. The two ligands bearing two different pendant arms (two-pycolyl and two (2-(2-hydroxyethoxy)ethyl)-2-aminoacetamide in trans position) were synthesized in the aim to obtain stable and water soluble complexes. The thermodynamic and kinetic of the formation of the corresponding complexes in aqueous solution were studied by means of NMR and potentiometric investigations. The fast kinetic of complexation and the high stability of the complexes are encouraging for further application with the alpha-emitting 213Bi isotope

Proton-sponge behaviour of new pendant armed cross-bridged bis-cyclens: Synthesis, NMR, X-ray, and potentiometric investigations

International audienceThe synthesis via bis-aminal derivatives and proton-sponge behaviour of new constrained bis-cyclens in which each macrocyclic subunit is alkylated with an alcohol function is presented and highlighted with NMR spectra, X-ray data and corroborated by potentiometric investigations

Copper sorption onto a lignocellulosic substrate from wheat bran impregnated with a lipophilic tetraazamacrocycle

International audienceThe topic of this paper is the impregnation with tetraazamacrocyclic ligands of a lignocellulosic substrate extracted from wheat bran. A preliminary N-functionalization by an alkyl pendant arm makes the cyclic tetraamine ligands lipophilic, so as to ensure their immobilization on the substrate. The macrocyclic ligands thus fixed at the surface of the lignocellulosic substrate interact with copper ions in solution to form complexes, as proven by EPR spectra. The end result is an increased retention capacity of the lignocellulosic substrate for pH values lower than 4. Indeed, while the unmodified lignocellulosic substrate does not retain Cu(II) at pH 3, the impregnated substrate exhibits a retention capacity of 4.13 mg g−1

Host–guest interaction between cyclen based macrotricyclic ligands and phosphate anions. A potentiometric investigation

International audienceThe host-guest interaction between orthophosphate, pyrophosphate and triphosphate anions and three cyclen based macrotricyclic ligands possessing ortho- (TOC), meta- (TMC) and para-xylenyl (TPC) linkers was investigated by potentiometric measurements. The ternary species present in solution and their stability constants have been determined. The different behaviours are explained in terms of hydrogen bond formation and coulombic attraction between the organic host and the inorganic guest. The selectivity, illustrated with species distribution diagrams, is discussed. The results unambiguously showed the importance of the distance between the two cyclen cores and emphasized the increasing of the triphosphate species selectivity together with the cavity size of the ligand. A comparison of the present results with those obtained with their mono-bridged homologues is also discussed

Complexation of the triphosphate anion: tuning the structure of cyclen based macrotricycles with 1,3-dimethylbenzene and 2,6-dimethylpyridine linkers. A potentiometric and NMR study

International audienceThe host–guest interaction between orthophosphate, pyrophosphate and triphosphate anions and three cyclen-based macrotricyclic ligands was investigated by potentiometric measurements and NMR spectroscopy. The ligands differ from one another by the nature of their spacers, which are 1,3-dimethylbenzene (TMC), 2,6-dimethylpyridine (TPyC) or a combination of the two (TMPyC). In aqueous solution, each ligand gave protonated species that further formed ternary complexes after binding with anions; these complexes were analyzed as a result of hydrogen bond formation and coulombic attraction between the organic host and the inorganic guest. The equilibrium constants found for all the detected species are reported and the selectivity, illustrated with species distribution diagrams, is discussed. The results unambiguously showed that the ligand possessing a single supplementary anchoring site (the pyridinyl spacer) exhibited the greatest affinity for the phosphate species in a large p[H] range

New side-bridged bismacrocycles and cross-bridged macrotricycles. Syntheses and Cu(ii) complexation study

International audienceEight new cyclen based constrained macropolycycles (4a–4d, 5a–5d) have been obtained by reductive ring cleavage of polyaminal derivatives of bis-macrocycles or macrotricyclic polyammonium salts by sodium borohydride. The mononuclear and dinuclear Cu(II) complexes of these macropolycyclic ligands were isolated as solids and investigated by UV-Vis and EPR spectroscopies. The possibility to obtain the specific formation of mononuclear complexes constitutes an original feature of these new macropolycycles

Nickel(ii) complexes of cyclen- and cyclam-pyridine: topological reorganisations induced by electron transfer

International audienceThe Ni(II) complexes of cyclen- and cyclam-pyridine (respectively 1-pyridin-2-ylmethyl-1,4,7,10-tetraazacyclododecane and 1-pyridin-2-ylmethyl-1,4,8,11-tetraazacyclotetradecane denoted [NiIIL1]2+ and [NiIIL2]2+) have been isolated and characterised by X-ray diffraction, UV-visible spectroscopy and electrochemical studies for the [NiIIL2]2+ complex. In particular, the [NiIIL2]2+ complex adopts two distinct and stable geometries (type I and V), which mainly differ by the macrocycle configuration. In solution, the isomerisation process between these two configurations is driven by the nickel-centered electron transfer

Influence of a Pyrazyl Linker on the Physicochemical Properties of Homodinuclear Bis(cyclen) and Bis(cyclam) Complexes

International audienceCuII and NiII complexes of bis(cyclen)pyrazine and bis(cyclam)pyrazine, [Cu2L1]4+, [Ni2L1]4+, [Cu2L2]4+, [Ni2L2]4+, have been isolated and characterised by UV/Vis and EPR spectroscopy. Complex [Cu2L1]4+ was characterised by X-ray diffraction. The crystallographic structure indicated that the two metal cations are held in a square-pyramidal geometry, the central nitrogen pyrazine atoms occupying the apical position of each metal centre. In solution, the EPR spectrum of [Cu2L1]4+ revealed the presence of two isomers, one of which was the previous crystallised complex. For [Ni2L2]4+, the electrochemical studies have highlighted the presence of two distinct geometries for the complex (type III and type V). From the electronic point of view, EPR and electrochemical measurements indicated that in these complexes the pyrazine bridge behaves as a poorly efficient exchange bridging ligand between the two metal centres