Search results for "Metal-complexes"
showing 10 items of 20 documents
Bis(4-methylthio)phenylthiomethane as assembling ligand for the construction of Cu(I) and Hg(II) coordination polymers. Crystal structures and topolo…
2016
International audience; The novel 1D coordination polymer (CP) [{Cu(mu(2)-Br)(2)Cu}(mu-L2)(2)] CP2 has been obtained by reaction of the tetrakisthioether p-MeSC6H4SCH2SC6H4SMe-p (L2) with CuBr in a 1: 2 metal-to ligand ratio. In contrast to the previously described CP [{Cu(mu(2)-Br)(2)Cu}(mu-L1)(2)] CP1 obtained by reaction of the tetrakisthioether p-MeOC6H4SCH2SC6H4OMe-p (L1) with CuBr, the two independent extended 1D ribbons contain bent Cu(mu(2)-Br)(2)Cu units of the butterfly-type with short Cu center dot center dot center dot Cu separations of 2.679(1) and 2.613(1) angstrom. In contrast to the common planar rhomboid Cu(mu(2)-Br)(2)Cu cluster, this butterfly-shaped geometry of the core …
From CO2 to dimethyl carbonate with dialkyldimethoxystannanes: the key role of monomeric species.
2011
International audience; The formation of dimethyl carbonate (DMC) from CO(2) and methanol with the dimer [n-Bu(2)Sn(OCH(3))(2)](2) was investigated by experimental kinetics in support of DFT calculations. Under the reaction conditions (357-423 K, 10-20 MPa), identical initial rates are observed with three different reacting mixtures, CO(2)/toluene, supercritical CO(2), and CO(2)/methanol, and are consistent with the formation of monomeric di-n-butyltin(iv) species. An intramolecular mechanism is, therefore, proposed with an Arrhenius activation energy amounting to 104 ± 10 kJ mol(-1) for DMC synthesis. DFT calculations on the [(CH(3))(2)Sn(OCH(3))(2)](2)/CO(2) system show that the exothermi…
Potential anticancer heterometallic Fe-Au and Fe-Pd agents: Initial mechanistic insights
2013
A series of gold(III) and palladium(II) heterometallic complexes with new iminophosphorane ligands derived from ferrocenylphosphanes [{Cp-P(Ph2)═N-Ph}2Fe] (1), [{Cp-P(Ph2)═N-CH2-2-NC5H4}2Fe] (2), and [{Cp-P(Ph2)═N-CH2-2-NC5H4}Fe(Cp)] (3) have been synthesized and structurally characterized. Ligands 2 and 3 afford stable coordination complexes [AuCl2(3)]ClO4, [{AuCl2}2(2)](ClO4)2, [PdCl2(3)], and [{PdCl2}2(2)]. The complexes have been evaluated for their antiproliferative properties in human ovarian cancer cells sensitive and resistant to cisplatin (A2780S/R), in human breast cancer cells (MCF7) and in a nontumorigenic human embryonic kidney cell line (HEK-293T). The highly cytotoxic trimeta…
Phenoxyamidine Zn and Al Complexes: Synthesis, Characterization, and Use in the Ring-Opening Polymerization of Lactide
2019
International audience; Herein we report the synthesis of new ditopic ligands, which consist of a phenoxy group and N,N,N'trisubstituted amidines linked by a methylene spacer (L1-L4). Their coordination chemistry has been studied/investigated with Zn(II) and Al(III). Alkane elimination route between the phenol-amidine proligands (L1H-L4H) and Et2Zn led to dinuclear complexes [(L1-L4)ZnEt]2 (1a-4a) in which the Zn centers are chelated by phenoxyamidine ligands and bridged through the oxygen atom of the phenoxy groups. Salt metathesis reaction between two equivalents of the sodium amidine phenate L1Na and ZnCl2 led to a bis-chelate chiral spiro-complex (L12Zn) 1a'. Analogous alkane eliminatio…
Ferrocenyl-Coupled N-Heterocyclic Carbene Complexes of Gold(I)
2016
Four gold(I) carbene complexes featuring 4-ferro-cenyl-substituted imidazol-2-ylidene ligands were investigated for antiproliferative and antivascular properties. They were active against a panel of seven cancer cell lines, including multidrug-resistant ones, with low micromolar or nanomolar IC50 (72 h) values, according to their lipophilicity and cellular uptake. The delocalized lipophilic cationic complexes 8 and 10 acted by increasing the reactive oxygen species in two ways: through a genuine ferrocene effect and by inhibiting the thioredoxin reductase. Both complexes gave rise to a reorganization of the F-actin cytoskeleton in endothelial and melanoma cells, associated with a G1 phase c…
Azide Binding Controlled by Steric Interactions in Second Sphere. Synthesis, Crystal Structure, and Magnetic Properties of [Ni II 2 (L)(μ 1,1 -N 3 )]…
2016
International audience; The dinuclear Ni-II complex [Ni-2(L-2)][ClO4](2) (3) supported by the 28-membered hexaaza-dithiophenolate macro-cycle (L-2)(2-) binds the N-3(-) ion specifically end-on yielding [Ni-2(L-2)(mu(1,1)-N-3)] [ClO4] (7) or [Ni-2(L-2)(mu(1,1)-N-3)][BPh4] (8), while the previously reported complex [Ni2L1(mu(1,3)-N-3)][ClO4] (2) of the 24-membered macrocycle (L-1)(2-) coordinates it in the end-to-end fashion. A comparison of the X-ray structures of 2, 3, and 7 reveals the form-selective binding of complex 3 to be a consequence of its preorganized, channel-like binding pocket, which accommodates the azide anion via repulsive CH center dot center dot center dot pi interactions …
Iridium(III) Complexes with Phenyl-tetrazoles as Cyclometalating Ligands
2014
Ir(II) cationic complexes with cyclometalating tetrazolate ligands were prepared for the first time, following a two-step strategy based on (i) a silver-assisted cyclometalation reaction of a tetrazole derivative with IrCl3 affording a bis-cyclometalated solvato-complex P ([Ir(ptrz)(2)(CH3CN)(2)](+), Hptrz = 2-methyl-5-phenyl-2H-tetrazole); (ii) a substitution reaction with five neutral ancillary ligands to get [Ir(ptrz)(2)L](+), with L = 2,2'-bypiridine (1), 4,4'-di-tert-butyl-2,2'-bipyridine (2), 1,10-phenanthroline (3), and 2-(1-phenyl-1H-1,2,3-triazol-4-yl)pyridine (4), and [Ir(ptrz)(2)L-2](+), with L = tertbutyl isocyanide (5). X-ray crystal structures of P, 2, and 3 were solved. Elect…
Characterization of Hydrophilic Gold(I) N-Heterocyclic Carbene (NHC) Complexes as Potent TrxR Inhibitors Using Biochemical and Mass Spectrometric App…
2017
We report here on the synthesis of a series of mono-and dinuclear gold(I) complexes exhibiting sulfonated bis(NHC) ligands and novel hydroxylated mono(NHC) Au(I) compounds, which were also examined for their 'biological activities. Initial cell viability assays show strong antiproliferative activities of the hydroxylated mono(NHC) gold compounds (8 > 9 > 10) against 2008 human ovarian cancer cells even after 1 h incubation. In order to gain insight into the mechanism of biological action of the gold compounds, their effect on the pivotal cellular target seleno-enzyme thioredoxin reductase (TrxR), involved in the maintenance of intracellular redox balance, was investigated in depth. Th…
Origin of the large spectral shift in electroluminescence in a blue light emitting cationic iridium(III) complex
2007
A new, but archetypal compound [ Ir( ppy- F-2) (2)Me(4)phen] PF6, where ppy- F2 is 2-(2',4'- fluorophenyl) pyridine and Me(4)phen is 3,4,7,8- tetramethyl- 1,10- phenanthroline, was synthesized and used to prepare a solid-state light-emitting electrochemical cell (LEEC). This complex emits blue light with a maximum at 476 nm when photoexcited in a thin film, with a photoluminescence quantum yield of 52%. It yields an efficient single-component solid-state electroluminescence device with a current efficiency reaching 5.5 cd A(-1) and a maximum power efficiency of 5.8 Lm Watt(-1). However, the electroluminescence spectrum is shifted with respect to the photoluminescence spectrum by 80 nm resul…
An Off-On-Off Fluorescent Sensor for pH Windows Based on the 13aneN4-Zn 2+ System
2016
International audience; The new ligand L was prepared and features a 13-membered tetraaza macrocyclic ring with a 1,8-naphthalimide fluorophore appended to a C atom of its backbone. The protonation constants of L as well as its complexation constants with Zn2+ ions were determined in 1:1 water/methanol solutions by potentiometric titrations. Fluorimetric pH titrations were performed with L alone and L in the presence of Zn2+ ions (1:1), and the species distributions (%) versus pH were compared. A window-shaped fluorescence trend was observed with pH for the L/Zn2+ system, which behaves as an off-on-off pH sensor. The on window is centred in the 6.5-7.5 pH range, in correspondence with the f…