Ternary iron(ii) complex with an emissive imidazopyridine arm from Schiff base cyclizations and its oxidative DNA cleavage activity

Abstract

The ternary iron(II) complex [Fe(L')(L")](PF6)3(1) as a synthetic model for the bleomycins, where L' and L" are formed from metal-mediated cyclizations of N,N'-(2-hydroxypropane-1,3-diyl)bis(pyridine-2-aldimine)(L), is synthesized and structurally characterized by X-ray crystallography. In the six-coordinate iron(ii) complex, ligands L' and L" show tetradentate and bidentate chelating modes of bonding. Ligand L' is formed from an intramolecular attack of the alcoholic OH group of L to one imine moiety leading to the formation of a stereochemically constrained five-membered ring. Ligand L" which is formed from an intermolecular reaction involving one imine moiety of L and pyridine-2-carbaldehyde has an emissive cationic imidazopyridine pendant arm. The complex binds to double-stranded DNA in the minor groove giving a Kapp value of 4.1 x 10(5) M(-1) and displays oxidative cleavage of supercoiled DNA in the presence of H2O2 following a hydroxyl radical pathway. The complex also shows photo-induced DNA cleavage activity on UV light exposure involving formation of singlet oxygen as the reactive species.

Synthesis, Characterization and Antimicrobial Activity of Cu(II), Co(II), Ni(II), Pd(II) and Ru(III) Complexes with Clomiphene Citrate

“…Currently, the use of such metal complexes is promising since they act as single-molecule magnets (SMMs) [14], as luminescent probes [15], as catalysts for specific DNA [16] and RNA [17] cleavage reactions and some transition metal complexes (M¼Cu, Co, Ni, etc.) of Schiff base ligands with the potent inhibitory activities against urease have also been reported by us [18].…”

Crystal structure of bis(2,4-dibromo-6-{(E)[(4-fluorobenzyl)imino]methyl}phenolato-κ2 N,O) copper(II), C28H18Br4F2N2O2Cu

“…Schi base and its transition metal complexes have become the hot topic of research [5]. Schi base ligands are formed by amine and carbonyl compounds via condensation and coordinate by a single tooth to multiple teeth, from symmetrical to asymmetrical, from chain to ring.…”

Self‐Assembly and Characterization of Homo‐ and Heterodinuclear Complexes of Zinc(II) and Lanthanide(III) Ions with a Tridentate Schiff‐Base Ligand

“…[1,2] These ligands are fascinating and versatile complexing agents because their metal complexes are known to serve as luminescent probes in the visible and near-IR spectral domains, [3,4] as precursors for doped materials where the metal centers must be at fixed distances from each other, as catalysts for specific DNA [5] and RNA [6] cleavage reactions, and as analytical sensors for the in vivo mapping of Ca 2+ concentration. [7,8] The complexes of paramagnetic ions have been tested as contrast enhancement agents, especially the complexes of gadolinium().…”