Pulse radiolytic studies on cis-dichlorobis-(2,2'-bipyridine)cobalt(III) and cis-dichlorobis-(1,10-phenanthroline)cobalt(III) complexes

690-694The reactions of hydrated electron (e⁻q) with Co(III) polypyridyl complexes of the type [Co(NN)2Cl2]Cl where NN = 2,2'-bipyridine (bpy), and 1,10-phenanthroline (phen) have been studied by pulse radiolysis. The rate constants for the reactions at 300 K have been evaluated to be (7.6±0.2)x10¹⁰, and (6.9±0.2)x10¹⁰ dm³ mol⁻¹ s⁻¹, respectively. Time resolved transient absorption spectra show two broad peaks at 360 and 610 nm for the bpy complex and a single broad peak at 420 nm for the phen complex at 1 μs. Comparison with reported transient spectra of the anion radicals of ligands indicates that the electron is located on the complex as a whole. The anion radicals of both the complexes initially produced, decay in the time scale of ~80 μs. Steady state absorption spectra on irradiation point out to breakdown of the phen complex, and the bpy-Co(III) complex is reduced to Co(II) complex. Conductance of the solution substantially increases on irradiation for both the complexes and can be attributed to aquation/de-ligation of the phen complex. The phen complex anion radical undergoes aquation/de-ligation by intramolecular electron transfer leading to dissociation of the complex. For bpy complex the conductance increases due to the release of chloride ions and reduction to Co(II) complex species is observed

Efficient DNA condensation by ruthenium(ii) polypyridyl complexes containing triptycenyl functionalized 1,10-phenanthroline

A series of luminescent ruthenium(ii) polypyridyl complexes containing an extended aromatic moiety derived from triptycene and 1,10-phenanthroline were synthesized and their photophysical, theoretical, and biological properties were investigated. These complexes rapidly condense DNA into nano-aggregates at room temperature. The DNA interactions and DNA condensation properties of these complexes were investigated by absorption and emission spectroscopy, electrophoretic mobility assay, and atomic force microscopy. Their DNA cleavage inactivity and low toxicity of the complexes satisfy the requirements of a good non-viral gene delivery vector