Search results for "Metal complexe"

Selective G-quadruplex stabilizers: Schiff-base metal complexes with anticancer activity

2014

The affinity of three square-planar nickel(II) (1), copper(II) (2) and zinc(II) (3) Schiff-base complexes for wild-type human telomeric (h-Telo) and protooncogene c-myc G-quadruplex (G4) DNA was investigated by UV-visible absorption spectroscopy and circular dichroism. DNA-binding constants (Kb) were determined by spectrophotometric titrations for both G4-DNA and B-DNA. The results obtained point out that the three metal complexes selectively bind G4-DNA with higher affinity, up to two orders of magnitude, with respect to B-DNA. The nickel(II) complex 1 was found to be the most effective G4-DNA stabilizer and the Kb values decrease in the order 1 > 2 ≈ 3. Innovative computational investigat…

Kinetic and equilibrium study for Pd(II) removal from aqueous solution by sorption onto calcium alginate gel beads

2013

The more and more increasing use of catalytic converters to reduce the dangerous NOx and CO emission in the atmosphere by vehicle traffic produces a corresponding increase of palladium in the environment [1]. Among the so-called “platinum group Elements” (PGE), elemental palladium seems to be the most hazardous one because it can be easily and quickly oxidized to palladium(II) when put in contact with soil. The presence of palladium oxidized form is of great concern owing to its recognized toxicity towards plants, animals and humans. Therefore, as for the classical “heavy metals”, a removal of this element from the environment is needed and a subsequent recovery for its potential re-use is …

The interaction of DNA with metal complexes: computational investigations

2012

The Interaction of Small Molecules with Biomolecules

2014

The binding of small molecules with biological targets is associated to interesting chemical and biological properties of the resulting supramolecular systems. We have recently reported on the synthesis and characterization of cationic first row transition metal complexes and the study of their DNA binding properties, in aqueous solutions at neutral pH, essentially investigated by viscosimetry and spectroscopic techniques such as circular dichroism, absorption and fluorescence in the UV-visible wavelength range. Of course, such procedure cannot furnish atomic level details of the molecule-DNA interaction. Computational Chemistry may provide support for the interpretation of experimental dat…

DNA interaction of CuII, NiII and ZnII functionalized salphen complexes: studies by linear dichroism, gel electrophoresis and PCR.

2013

The interaction of salphen-type NiII, CuII and ZnII complexes with native DNA was investigated by exploiting linear dichroism experiments. The NiII complex behaves as a typical intercalator, binding strongly and stiffening and unwinding the DNA. The strength of the DNA interaction is slightly weaker for the copper complex and much weaker for the zinc complex. Plasmid-DNA gel electrophoresis experiments indicated that while CuII and ZnII complexes do not induce the unwinding of supercoiled DNA, the NiII complex has a nuclease activity without the addition of external agents. On the other hand, as shown in the PCR assays, we demonstrate that, at the used concentrations, only the CuII complex …

Synthesis of a labile sulfur-centred ligand, [S(H)C(PPh2S)2]−: structural diversity in lithium(i), zinc(ii) and nickel(ii) complexes

2016

A high-yield synthesis of [Li{S(H)C(PPh2S)2}]2 [Li2·(3)2] was developed and this reagent was used in metathesis with ZnCl2 and NiCl2 to produce homoleptic complexes 4 and 5b in 85 and 93% yields, respectively. The solid-state structure of the octahedral complex [Zn{S(H)C(PPh2S)2}2] (4) reveals notable inequivalence between the Zn-S(C) and Zn-S(P) contacts (2.274(1) Å vs. 2.842(1) and 2.884(1) Å, respectively). Two structural isomers of the homoleptic complex [Ni{S(H)C(PPh2S)2}2] were isolated after prolonged crystallization processes. The octahedral green Ni(ii) isomer 5a exhibits the two monoprotonated ligands bonded in a tridentate (S,S',S'') mode to the Ni(ii) centre with three distinctl…

Self-assembly of metallosupramolecular rhombi from chiral concave 9,9'-spirobifluorene-derived bis(pyridine) ligands.

2014

Two new 9,9’-spirobifluorene-based bis(4-pyridines) were synthesised in enantiopure and one also in racemic form. These ligands act as concave templates and form metallosupramolecular [(dppp)2M2L2] rhombi with cis-protected [(dppp)Pd]2+ and [(dppp)Pt]2+ ions. The self-assembly process of the racemic ligand preferably occurs in a narcissistic self-recognising manner. Hence, a mixture of all three possible stereoisomers [(dppp)2M2{(R)-L}2](OTf)4, [(dppp)2M2{(S)-L}2](OTf)4, and [(dppp)2M2{(R)-L}{(S)-L}](OTf)4 was obtained in an approximate 1.5:1.5:1 ratio which corresponds to an amplification of the homochiral assemblies by a factor of approximately three as evidenced by NMR spectroscopy and m…

NiII, and ZnII Schiff Base Complexes: Telomeric G-quadruplex Stabilizers

2014

Recently, NiII and ZnII metal complexes of the ligand Salpyrim have been synthesized and characterized. Their affinity for wild-type h-Telo G-quadruplex DNA and for calf thymus DNA was investigated by UV absorption spectroscopy, circular dichroism and viscometry. The data collectively suggest that both complexes bind effectively to G-quadruplexes by direct end-stacking, stabilizing the oligonucleotide secondary structure. The two complexes are also typical B-DNA intercalators. Remarkably, their binding constants, Kb, with the G4s structures are about 10 fold higher than those with B-DNA, highlighting the selectivity. Experiments to evaluate the biological activity of the two complexes again…

New coordination polymers based on a novel polynitrile ligand: Synthesis, structure and magnetic properties of the series [M(tcnoetOH)2(4,4′-bpy)(H2O…

2008

International audience; A novel polynitrile anionic ligand, tcnoetOH−(=[(NC)2CC(OCH2CH2OH)C(CN)2]−), has been synthesized by a one-pot reaction from a cyclic acetal and malononitrile. This ligand has been successfully used to prepare, with 4,4′-bpy as co-ligand, a novel series of coordination polymers formulated as [M(tcnoetOH)2(4,4′-bpy)(H2O)2] with M(II) = Fe (1), Co (2) and Ni (3). These isostructural compounds present a linear chain structure consisting of octahedrally coordinated metal ions bridged by trans 4,4′-bpy ligands. The coordination sphere of the metal ions is completed with two terminal tcnoetOH− ligand and two water molecules. The magnetic properties indicate that the three …

Synthesis, X-ray structures and redox behaviour of the group 14 bis-boraamidinates M[PhB(μ-N-t-Bu)2]2 (M = Ge, Sn) and Li2M[PhB(μ-N-t-Bu)2]2 (M = Sn,…

2009

The solid-state structures of the complexes M[PhB(μ-N-t-Bu)2]2 (1a, M= Ge; 1b, M = Sn) were determined to be spirocyclic with two orthogonal boraamidinate (bam) ligands N,N′-chelated to the group 14 centre. Oxidation of 1b with SO2Cl2 afforded the thermally unstable, blue radical cation {Sn[PhB(μ-N-t-Bu)2]2}•+, identified by electron paramagnetic resonance (EPR) spectroscopy supported by density functional theory (DFT) calculations, whereas the germanium analogue 1a was inert towards SO2Cl2. The reaction between Li2[PhB(μ-N-t-Bu)2]2 and SnCl2 or PbI2 in 2:1 molar ratio in diethyl ether produced the novel heterotrimetallic complexes Li2Sn[PhB(μ-N-t-Bu)2]2 (2b) and (Et2O·Li)LiPb[PhB(μ-N-t-Bu)…