Synthese, etude electrochimique et photochimique de 3-catenates homo- et hetero-dimetalliques

SIGLEINIST T 74244 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Synthèse et caractérisations physico-chimiques de complexes métalliques comportant des ligands multidentes bis(carbène N-hétérocyclique) fonctionalisés (évaluation catalytique en couplage de Suzuki-Miyaura)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Synthesis, characterization, and antileishmanial activities of gold(I) complexes involving quinoline functionalized N-heterocyclic carbenes

International audienceA series of new mononuclear cationic or neutral gold(I) complexes containing quinoline functionalized N-heterocyclic carbene(s) (NHC(s)) were synthesized and fully characterized by spectroscopic methods. The X-ray structures of two key compounds are presented. Proligands and their corresponding gold(I) complexes together with previously described silver(I) and gold(I) bis(NHC-quinoline) and gold(I) bis(NHC-methylbipyridine) complexes were evaluated in vitro towards Leishmania infantum. In parallel, the in vitro cytotoxicity of these molecules was assessed on the murine macrophages J774A.1. All gold(I) compounds show potent antileishmanial activity against L. infantum promastigotes and three of them are also efficient against L infantum intracellular amastigotes. Structure-activity and toxicity relationships enables to evidence a lead-compound (6) displaying both a high activity and a good selectivity index

Synthesis and activity of macrocyclized chiral Mn(III)-Schiff-base epoxidation catalysts

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Central (S) to Central (M=Ir, Rh) to Planar (Metallocene, M=Fe, Ru) Chirality Transfer Using Sulfoxide‐Substituted Mesoionic Carbene Ligands: Synthesis of Bimetallic Planar Chiral Metallocenes

International audienceEnantiopure bimetallic systems containing three different elements of chirality, namely a main‐group‐based chiral center (sulfur), a transition‐metal chiral center (rhodium or iridium), and a planar chiral element (ferrocene or ruthenocene), have been prepared by a sequence of diastereoselective reactions. The chirality of the chiral sulfur center attached to C‐5 of a 1,2,3‐triazolylidene mesoionic carbene (MIC) ligand coordinated to a metal (Ir, Rh) was transferred through the formation of bimetallic complexes having a chiral‐at‐metal center and a planar chiral metallocene by C−H activation of the sandwich moiety (M=Fe, Ru). The sense of the planar chirality formed in this sequence of reactions depended on the nature of the ligands at the metal center of the starting complex. The configurations of these species were assigned on the basis of a combination of X‐ray diffraction and CD measurements. An electrochemical study of these bimetallic complexes in coordinating solvents showed an equilibrium between the cationic complexes and the neutral species. The effect of the half‐sandwich moiety on the oxidation potentials of the system is remarkable, producing notable cathodic displacements. DFT calculations support these findings

Dimeric Gold Bis(carbene) Complexes by Transmetalation in Water

International audienceDue to its cost, environmental benefits, and safety advantages, water has become more and more important as a solvent for catalytic reactions and constitutes the best environment for biomedical applications. Therefore, water-soluble and water-stable metal complexes containing strong σ-donor ligands such as N-heterocyclic carbenes (NHCs) are of great interest in modern coordination chemistry. In this paper we present the successful preparation of two new dinuclear gold(I)–bis(NHC) complexes in water, by applying the Ag–NHC transfer route. This green synthetic strategy is valuable for gold(I) compounds involving N-functionalized neutral and dianionic bis(NHC) ligands. These two water-soluble compounds were analyzed by spectroscopic methods and by X-ray diffraction. Furthermore, ab initio and DFT calculations on the corresponding dinuclear gold complexes illustrate the important influence of the electrostatic environment of the dinuclear entity on the aurophilic interactions and help to understand the molecular arrangement presented in this paper

Cationic and Neutral N -Heterocyclic Carbene Gold(I) Complexes: Cytotoxicity, NCI-60 Screening, Cellular Uptake, Inhibition of Mammalian Thioredoxin Reductase, and Reactive Oxygen Species Formation

RECENTLY Bowers and Smith (1) showed that soil water content can be measured by transmitting 1.94 µm through a methanol-soil extract. They proposed a rapid and accurate procedure; however, the required spectrophotometer was very expensive. The purpose of this investigation was to build an inexpensive spectrophotometer sufficiently sensitive to measure minute amounts of water. Construction of such an instrument seemed feasible, since Norris and Hart (3) had previously shown a relatively inexpensive spectrophotometer could be built to measure the water content of grain. Their procedure involved transmitting light through a ground grain-carbon tetrachloride paste or through intact grains

Synthesis, characterization, and antileishmanial activity of neutral N-heterocyclic carbenes gold(I) complexes

International audienceA series of five new mononuclear neutral gold(I) complexes containing N-heterocyclic carbenes (NHCs) was synthesized and fully characterized by spectroscopic methods. The X-ray structures of four complexes are presented. These gold(I) complexes together with four other neutral gold(I)-NHC complexes previously described were evaluated in vitro against Leishmania infantum promastigotes and axenic amastigotes. Moreover, their cytotoxicity was assessed on the murine macrophages J774A.1. Except one complex (10), eight gold(I)-NHC-Cl complexes show potent activity against the pathological relevant form of L. infantum amastigote with IC50 in the low micromolar and submicromolar range and five of them exhibit a SI close to 10. The lead-complex 11 displays a very high and selective activity (IC50 = 190 nM, SI = 40.29) and constitutes the best promising gold(I)-based drug of this series

Central (S) to Central (M=Ir, Rh) to Planar (Metallocene, M=Fe, Ru) Chirality Transfer Using Sulfoxide-Substituted Mesoionic Carbene Ligands: Synthesis of Bimetallic Planar Chiral Metallocenes

Enantiopure bimetallic systems containing three different elements of chirality, namely a main-group-based chiral center (sulfur), a transition-metal chiral center (rhodium or iridium), and a planar chiral element (ferrocene or ruthenocene), have been prepared by a sequence of diastereoselective reactions. The chirality of the chiral sulfur center attached to C-5 of a 1,2,3-triazolylidene mesoionic carbene (MIC) ligand coordinated to a metal (Ir, Rh) was transferred through the formation of bimetallic complexes having a chiral-at-metal center and a planar chiral metallocene by C−H activation of the sandwich moiety (M=Fe, Ru). The sense of the planar chirality formed in this sequence of reactions depended on the nature of the ligands at the metal center of the starting complex. The configurations of these species were assigned on the basis of a combination of X-ray diffraction and CD measurements. An electrochemical study of these bimetallic complexes in coordinating solvents showed an equilibrium between the cationic complexes and the neutral species. The effect of the half-sandwich moiety on the oxidation potentials of the system is remarkable, producing notable cathodic displacements. DFT calculations support these findings.Support for this work from the Ministro de Ciencia, Innovaciónn y Universidades (MICIUN) of Spain (under grants CTQ2016- 77555-C2-1-R (to M.A.S.), CTQ2016-77555-C2-2-R (to M.C.T.), and CTQ2016-81797-REDC Programa Redes Consolider) is gratefully acknowledged. M.A.S. thanks the Fundación Ramón Areces for a grant from the XVIII Concurso Nacional de Ayudas a la Investigación en Ciencias de la Vida y de la Materia (CIVP18A3938)

Synthesis, Characterization, and Antileishmanial Activity of Neutral Gold(I) Complexes with N-heterocyclic Carbene Ligands Bearing Sulfur-Containing Side Arms

International audienceWith an estimated annual incidence of one million cases, leishmaniasis is one of the top five vector-borne diseases. Currently available medical treatments involve side effects, including toxicity, nonspecific targeting, and resistance development. Thus, new antileishmanial chemical entities are of the utmost importance to fight against this disease. We have shown in previous studies that gold(I) complexes bearing N-heterocyclic carbene (NHC) ligands with nitrogen- or sulfur-containing side arms have interesting biological activities in the field of cancer, malaria and leishmaniasis. The present study evaluates the in vitro antileishmanial effects on L. infantum axenic amastigotes and their cytotoxicity for the human THP1 cell line of a new family of six new imidazolium salts and their corresponding neutral (NHC)AuICl complexes. All new compounds have been characterized by classical analytical methods, and five gold complexes have been analyzed by X-ray structure determinations. We showed that one proligand has moderate activity (IC50 = 8.24 μM) while four of the six gold complexes have IC50 values in the low or sub μM range (0.15–1.3 μM), including three with selectivity index (SI) values between 46 and 108. These results suggest remarkable leishmanicidal activity in vitro for three new neutral (NHC)Au(I)Cl complexes, making them candidates for further in vivo studies, which are under investigation