Selective DNA Purine Base Photooxidation by Bis-terdentate Iridium(III) Polypyridyl and Cyclometalated Complexes

Abstract

Two bis-terdentate iridium(III) complexes with polypyridyl and cyclometalated ligands have been prepared and characterized. Their spectroscopic and electrochemical properties have been studied, and a photophysical scheme addressing their properties is proposed. Different types of excited states have been considered to account for the deactivation processes in each complex. Interestingly, in the presence of mono- or polynucleotides, a photoinduced electron-transfer process from a DNA purine base (i.e., guanine or adenine) to the excited complex is shown through luminescence quenching experiments. For the first time, this work reports evidence for selective DNA purine bases oxidation by excited iridium(III) bis-terdentate complexes.

Molecular and Nanoaggregation in Cyclometalated Iridium(III) Complexes through Structural Modification

“…13 C NMR spectroscopic data of the ligands and complexes 1 and 2 further support their formation and the proposed structures. These findings are similar to those in other closely related systems , …”

“…A pertinent view of the crystal structure is given in Figure . It reveals that cationic iridium(III) complex 1 shows N1–N2 in trans position, which is a normal phenomenon resulting from the conventional synthetic route . The Ir1–C and Ir1‐N bond lengths and C–Ir1–N, C–Ir1–C, N–Ir1–N bond angles (Table S2 in the Supporting Information) have a normal size.…”

“…They are comparable to other closely related cyclometalated iridium(III) polypyridine systems reported in the literature. [2d], [11c]…”

Synthesis and Photophysical Properties of Triazolyl IrIII Nucleosides

“…Thanks to their photophysical and photochemical properties, iridium(III) complexes are of increasing interest in the development of sensors, and photoreactants towards DNA. Regarding the latter case, we recently demonstrated that an Ir III terpy (2,2′:6′,2′′‐terpyridine) derivative is able to photooxidize purine bases of DNA . Another cyclometalated Ir III complex was shown to photooxidize guanine and photoreduce cytosine .…”

Interaction of Iron II Complexes with B-DNA. Insights from Molecular Modeling, Spectroscopy, and Cellular Biology

“…DNA/drugs adducts are known for both small organic molecules, such as aryl ketones, and relatively large organometallic compounds, such as copper (Rajendiran et al, 2008 ; Kellet et al, 2011 ; Larragy et al, 2015 ; Molphy et al, 2015 ) or ruthenium polypyrimidines or polyphenantrolines (Very et al, 2012 ; Chantzis et al, 2014 ; Huang et al, 2014 ). Recently the interaction of Iridium complexes with DNA has been reported together with their unusual photophysics (Alexandre et al, 2014 ).…”