4 research outputs found
Substituted dipyridophenazine complexes of Cr(III): synthesis, enantiomeric resolution and binding interactions with calf thymus DNA
[Cr(phen)2(X2dppz)]3+ {X = H, Me, or F} have been synthesised, characterised, and chromatographically resolved into their constituent Δ and Λ enantiomers. The DNA-binding interactions of each of the racemic complexes were investigated, with the results of linear dichroism, thermal denaturation, and emission quenching studies indicative of intercalative binding to CT-DNA with a significant electrostatic contribution. UV/Vis absorption titrations suggest strong DNA binding by each of the racemic complexes, with the methylated analogue [Cr(phen)2(Me 2dppz)]3+ exhibiting the largest equilibrium binding constant. Emission quenching and UV-Vis titrations of the enantiomers of [Cr(phen)2(dppz)]3+ imply similar binding affinities for the Δ and Λ isomers, although significant differences between the circular dichroism spectra of the enantiomers in the presence of DNA connote differences in binding orientation and/or conformation between the two
Recommended from our members
Study of picosecond processes of an intercalated dipyridophenazine Cr(iii) complex bound to defined sequence DNAs using transient absorption and time-resolved infrared methods
Picosecond transient absorption (TA) and time-resolved infrared (TRIR) measurements of rac-[Cr(phen)2(dppz)]3+ (1) intercalated into double-stranded guanine-containing DNA reveal that the excited state is very rapidly quenched. As no evidence was found for the transient electron transfer products, it is proposed that the back electron transfer reaction must be even faster (<3 ps)
Excited state behaviour of substituted dipyridophenazine Cr(III) complexes in the presence of nucleic acids
The photophysics and photochemistry of [Cr(phen)2(dppz)]3+ and its 11,12-substituted derivatives [Cr(phen)2(X2dppz)]3+
{X = Me or F} have been studied in the presence of purine nucleotides
or DNA using steady state and time-resolved absorption and luminescence
spectroscopy. 5'-Adenosine monophosphate (5'-AMP) shows only a weak
interaction with the excited states of each complex. By contrast they
are efficiently quenched by 5'-guanosine monophosphate (5'-GMP),
consistent with photo-induced electron transfer. Laser flash photolysis
spectroscopy in the presence of 5'--GMP suggests that both forward and
back electron-transfers are rapid. All complexes also display a strong
affinity for DNA and evidence for both static and dynamic quenching
mechanisms is provided.AMS. No Keywords