Self-Association of Ruthenium(II) Polypyridyl Complexes and Their Interactions with Calf Thymus DNA

Abstract

Complexes of the type [Ru(N-N)(2)(bxbg)]Cl(2) where N-N is 2,2'-bipyridine (bpy) (1), 1,10-phenanthroline (phen) (2), dipyrido [3,2-d:2',3f] quinoxaline (dpq) (3), and dipyrido[3,2-a:2',3'-c]phenazine (dppz) (4) which incorporate the bis(o-xylene)bipyridine glycoluril (bxbg) as the ancillary ligand have been synthesized and characterized by IR, NMR, UV-visible, luminescence, ESI-MS, cyclic voltammetry, and spectroelectrochemistry. The bis(o-xylene)bipyridine glycoluril initiates a head to head association which act as the nucleation point for the further growth in two direction by head-to-head and tail-to-tail self-association resulting in formation of aggregates in water which have been investigated by (1)H NMR, NOESY, steady state luminescence dilution experiments, and electron microscopy studies. The self-association has been confirmed by single crystal X-ray analysis of complex 2. Electrochemical and spectroelectrochemical studies in acetonitrile show that these complexes undergo reversible one electron oxidation from Ru(II) to Ru(III). The binding of these complexes with calf thymus DNA (CT-DNA) has been studied by absorption titration, steady-state and time-resolved emission measurement experiments, to investigate the influence of the ancillary ligand. The binding ability of these complexes to DNA is dependent on the planarity of the intercalative polypyridyl ligand which is further affected by the bis(o-xylene)bipyridine glycoluril ancillary ligand.

Ruthenium(II) polypyridyl complexes with hydrophobic ancillary ligand as Aβ aggregation inhibitors

“…The N-Ru-N chelate ring angles are in the range of 77.9 -79.8º while the N-Ru-N angles formed by different ligands around central Ru are in the range of 83.6-93.1º. The average Ru-N (phen) bond length is 2.070 Å and mean Ru-N (txbg) bond length is 2.052 Å which are similar to other analogous mixed ligand Ru(II) polypyridyl complexes[26][27][28].…”

Monomer–Dimer Divergent Behavior toward DNA in a Half-Sandwich Ruthenium(II) Aqua Complex. Antiproliferative Biphasic Activity

“…According to reaction 1, the dependence of the relaxation time on the dye concentration can be expressed in the form (6) 2.066(3) N(2)−C (6) 1.333 (6) 1.319 (8) 1.351(4) N(3)−C (6) 1.336 (6) 1.351 (9) 1.333 (4) Table 2 lists the aggregation parameters compared with those for other antitumor drugs, also deduced from T-jump at the same ionic strength. Inspection of Table 2 reveals that K D has the same order of magnitude as other organic compounds in which π−π stacking interactions prevail, consistent with the dimer entity observed by X-ray diffraction ( Figure 2).…”

Re(I) tricarbonyl complex of 1,10-phenanthroline-5,6-dione: DNA binding, cytotoxicity, anti-inflammatory and anti-coagulant effects towards platelet activating factor

“…For example, a classical intercalator, such as ethidium bromide, causes a significant increase in viscosity of a DNA solution because of the separation of the base pairs at the intercalation site, and hence, the expansion of the DNA molecular length. In contrast, a ligand that binds in the DNA grooves causes less-pronounced changes or no change in viscosity of a DNA solution [55,56]. causes a similar decrease of the relative viscosity of DNA [55].…”