Synthesis, DNA-binding and DNA-mediated luminescence quenching of Ru(II) polypyridine complexes

Polypyridyl ruthenium(II) complexes containing intramolecular hydrogen-bond ligand: syntheses, characterization, and DNA-binding properties

Spectral, viscometric and electrochemical studies on mixed ligand cobalt(III) complexes of certain diimine ligands bound to calf thymus DNA

A series of mixed ligand ruthenium(II) complexes [Ru(pdto)(diimine)](ClO4)2/(PF6)21–3 and [Ru(bbdo)(diimine)](ClO4)24–6, where pdto is 1,8-bis(pyrid-2-yl)-3,6-dithiooctane, bbdo is 1,8-bis(benzimidazol-2-yl)-3,6-dithiooctane and diimine is 1,10-phenanthroline (phen), dipyrido-[3,2-d:2′,3′-f]-quinoxaline (dpq) and dipyrido[3,2-a:2′,3′-c]phenazine (dppz), have been isolated and characterised by analytical and spectral methods. The complexes [Ru(pdto)(phen)](PF6)21a, [Ru(pdto)(dpq)(Cl)](PF6) 2a, [Ru(bbdo)(phen)](PF6)24a and [Ru(bbdo)(dpq)](ClO4)25 have been structurally characterized and their coordination geometries around ruthenium(II) are described as distorted octahedral. In 1a, 4a and 5 the two thioether sulfur and two py/bzim nitrogen atoms of the tetradentate pdto/bbdo ligand are folded around Ru(II) to give predominantly a “cis-α” configuration. IH NMR spectral data of the complexes support this configuration in solution. In [Ru(pdto)(dpq)Cl](PF6) 2a with a distorted octahedral coordination geometry, one of the two py nitrogens of pdto is not coordinated. The DNA binding constants (Kb: 2, 2.00 ± 0.02 × 104 M−1, s = 1.0; 3, 3.00 ± 0.01 × 106 M−1, s = 1.3) determined by absorption spectral titrations of the complexes with CT DNA reveal that 3 interacts with DNA more tightly than 2 through partial intercalation of the extended planar ring of coordinated dppz with the DNA base stack. The DNA binding affinities of the complexes increase with increase in the number of planar aromatic rings in the co-ligand, and on replacing both the py moieties in pdto complexes (1–3) by bzim moieties to give bbdo complexes (4–6). Upon interaction with CT DNA the complexes 1, 2, 5 and 6 show a decrease in anodic current in the cyclic voltammograms. On the other hand, interestingly, 3 and 4 show an increase in anodic current suggesting their involvement in electrocatalytic guanine oxidation. Interestingly, of all the complexes, only 6 alters the superhelicity of DNA upon binding with supercoiled pBR322 DNA. The cytotoxicities of the dppz complexes 3 and 6, which avidly bind to DNA, have been examined by screening them against cell lines of different cancer origins. It is noteworthy that 6 exhibits selectivity with higher cytotoxicity against the melanoma cancer cell line (A375) than other cell lines, potency approximately twice that of cisplatin and toxicity to normal cells 3 and 90 times less than cisplatin and adriamycin respectively.

https://www.rsc.org/suppdata/dt/b7/b710578a/b710578a.pdf

Mixed ligand ruthenium(II) complexes of bis(pyrid-2-yl)-/bis(benzimidazol-2-yl)-dithioether and diimines: Study of non-covalent DNA binding and cytotoxicity

Synthesis, DNA-binding and topoisomerase inhibitory activity of ruthenium(II) polypyridyl complexes

Imidazo[4,5-f]1,10-phenanthroline (ip),
2-phenylimidazo[4,5-f][1,10]phenanthroline (pip) and
their (bipy)
 2
Ru
 2+
 complexes
(bipy = 2,2′-bipyridine) have been synthesized and
characterized The oxidation potentials of
[Ru(bipy)
 2
(ip)]
 2+
 and
[Ru(bipy)
 2
(pip)]
 2+
 were found to be 1254 and
1284 V vs saturated calomel electrode respectively; the
reduction of ip and pip appears to be irreversible at ca
-085 V The photophysical properties of the complexes were
perturbed in the presence of calf thymus DNA The distinct changes
including hypo- or hyper-chromicity at different UV/VIS absorption
bands, enhancements of integrated emission intensity and excited-state
lifetime, and efficiency of emission quenching by
[Fe(CN)
 6
]
 4-
 all indicate the stronger
binding affinity to DNA of [Ru(bipy)
 2
(pip)]
 2+
 over
that of [Ru(bipy)
 2
(ip)]
 2+
, consistent with the
greater planar area and extended π system of the pip ligand The
luminescence of the complexes showed monoexponential decay at any
[DNA]∶[Ru] ratio The circular dichroism signals of the dialysates
of the racemic complexes against calf thymus DNA suggest that the
complexes bind to the DNA with enantioselectivity favouring the Δ
isomers These phenomena all suggest that the complexes bind through
intercalation of ip or pip into base pairs The crystal structure of
[Ru(bipy)
 2
(ip)][ClO
 4
]
 2
·H
 2

O was determined; it contains the planar bidentate ligand ip and
two twisted bipy ligands with torsional angles between each bipyridine
ring pair of 57 and 86°

http://nathan.instras.com/MyDocsDB/doc-531.pdf

Zhong-Yuan Zhou

Papers

Bis(2,2′-bipyridine)ruthenium(II)complexes withimidazo[4,5-f ][1,10]-phenanthroline or2-phenylimidazo[4,5-f ][1,10]phenanthroline