Luminescent Properties of Ruthenium(II) Complexes with Sterically Expansive Ligands Bound to DNA Defects

Abstract

A new family of ruthenium(II) complexes with sterically expansive ligands for targeting DNA defects was prepared, and their luminescent responses to base pair mismatches and/or abasic sites were investigated. The design of the complexes sought to combine the mismatch specificity of sterically expansive metalloinsertors, such as [Rh(bpy)2(chrysi)]3+ (chrysi = chrysene-5,6-quinone diimine), and the light switch behavior of [Ru(bpy)2(dppz)]2+ (dppz = dipyrido[3,2-a:2′,3′-c]phenazine). In one approach, complexes bearing analogues of chrysi incorporating hydrogen-bonding functionality similar to dppz were synthesized. While the complexes show luminescence only at low temperatures (77 K), competition experiments with [Ru(bpy)2(dppz)]2+ at ambient temperatures reveal that the chrysi derivatives preferentially bind DNA mismatches. In another approach, various substituents were introduced onto the dppz ligand to increase its steric bulk for mismatch binding while maintaining planarity. Steady state luminescence and luminescence lifetime measurements reveal that these dppz derivative complexes behave as DNA “light switches,” but that the selectivity in binding and in luminescence with mismatched/abasic versus well-matched DNA is not high. In all cases, the luminescence depends sensitively upon structural perturbations to the dppz ligand.

Raman spectroscopy of zinc oxide nanoplatelets modified with ruthenium (II) complexes

“…To the contrary, the spectra of Ru (II) complexes given by Oner et al in the region above 500 nm exhibit structures centered at somewhat smaller wavelength than is the case with our spectra . The spectra corresponding to all the modified samples are similar to those considered by McConnell et al with respect to detecting DNA defects . However, in order to obtain peaks, their spectra had to be recorded at 77 K, whereas our spectra were measured at room temperature.…”

“…Future studies can develop towards applying these materials in DNA analysis. For example, it can be investigated if use of our modified ZnO NPs in altering an electrode of a cell for electrochemiluminescence spectra measurement will prove efficient as was the case with the pristine carbon nanotube that was used by Tang et al Application of the analyzed materials in detecting DNA defects seems promising because our photoluminescence spectra were recorded at room temperature, whereas those employed for this purpose by McConnell et al were measured at 77 K.…”

Selective Stabilization of Abasic Site‐Containing DNA by Insertion of Sterically Demanding Biaryl Ligands

“…Along these lines, several ligands have been shown to bind to AP sites, for example, naphthyridine derivatives, [8] nucleic-base intercalator conjugates, [9,10] aminoalkyl-substituted DNA intercalators, [11,12] DNA intercalators such as proflavine, [13] annelated quinolizinium derivatives, [14] or berberine, [15] cyclic bisacridines, [16] or metalloinsertors with sterically expansive ligands. [17] Most substituted heterocyclic ligands accomplish the selective association with AP-DNA by hydrogen bonding of the ligand with the remaining nucleobase in the abasic site. [8][9][10] In a different approach, the sterically expansive metalloinsertors, such as D-[Rh(bpy) 2 chrysi] 3 + (bpy: bipyridine; chrysi: chrysene-5,6-quinone diimine), differentiate between regular DNA and AP-sitecontaining DNA (AP-DNA) because of the delicate balance between the stabilization of the DNA structure by an intercalator and the simultaneous destabilization of the ligand-DNA complex by a sterically demanding ligand.…”

“…Hence, AP-DNA may tolerate the steric strain induced by a ligand as long as it is compensated by an energetically favorable intercalative interaction in the AP site and, if available, additional binding interactions within the grooves. [17] In contrast, regular duplex DNA is more sensitive to the size of a ligand because of the additional energetically unfavorable change of the DNA structure upon intercalation, that is, unwinding, lengthening, kinking. Notably, this paradigm of directing the binding selectivity of DNA ligands by fine-tuned steric interactions may be the basis of a more general development of AP-DNA selective ligands.…”

Toward white electroluminescence by ruthenium quinoxaline light emitting diodes

“…In this regard, dicnq = 6,7dipyrido [2,2-d:2΄,3΄-f] quinoxaline complexes of ruthenium (II) were evaluated as potential for luminescence material [11]. In addition, among a great number of 1,10-phenanthroline derivates, 60 dicnq as rigid π-conjugated systems is ideal candidate for DNA binding because they prevent the bending along and/or rotation around the σ-skeleton of the molecule [12] (For more samples, please see ESI, S2).…”