A DNA‐Binding Copper(I) Metallosupramolecular Cylinder that Acts as an Artificial Nuclease

Abstract

The DNA binding of a dicationic pyridylimine-based dicopper(I) metallosupramolecular cylinder is reported together with its ability to act as an artificial nuclease. The cylinder binds strongly to DNA; more strongly than the spherical dication [Ru(phen)(3)](2+) (phen=1,10-phenanthroline), but more weakly than the corresponding tetracationic cylinders. DNA coiling effects are not observed with this dication, in contrast to the situation with the previously reported tetracationic cylinder involving a similar ligand. Linear dichroism (LD) data suggests that the dicopper cylinder binds in a different orientation from that of the tetracationic iron cylinder. Furthermore, the dicopper cylinder shows DNA-cleavage activity in the presence of peroxide. Of particular note is that the cylinder displays a marked and unusual ability to cleave both DNA strands at the same site, probably reflecting its dinuclear nature and possibly its mode of binding to the DNA.

Structural Diversity on Copper(I) Schiff Base Complexes

“…The basic bis-bidentate Schiff base ligands have two arms connected via a ring, or C-C bond, as for example, shown in Schemes 10 -14 [27][28][29][30]32,[35][36][37][38][39][40][66][67][68][69][70][71][72].…”

“…Until now, many examples of both single and double-stranded architectures have now been reported [92]. Studies on inorganic helical complexes containing transition metal ions have attracted much attention recently [27][28][29]40,[67][68][69][70][71][72]. In these supramolecular self-assembleies, the formation of the helicates can be described as the result of reading molecular information stored in the ligands by metal ions following the coordination algorithm such as tetrahedral.…”

“…Upon excitation at 360 or 470 nm, 35 display a single broad emission band with the maxima at 540 nm in methanol at room temperature [30]. In recent years, Hannon et al have systematically studied on helical metallo-supramolecular arrays with multidentate Schiff bas ligands L 47 -L 50 [27,28,40,71,72]. For this kind of compounds, the ligand must offer sufficient flexibility for multiple strands to wrap around two or more metal centers, and it should also be sufficiently rigid to impose the same stereochemistry as both metals [27,28].…”

“…In recent years, Hannon et al have systematically studied on helical metallo-supramolecular arrays with multidentate Schiff bas ligands L 47 -L 50 [27,28,40,71,72]. For this kind of compounds, the ligand must offer sufficient flexibility for multiple strands to wrap around two or more metal centers, and it should also be sufficiently rigid to impose the same stereochemistry as both metals [27,28]. Non-helical isomers arise when the ligand is too flexible to impose the same stereochemistry at both metal centers [27,28].…”

“…For this kind of compounds, the ligand must offer sufficient flexibility for multiple strands to wrap around two or more metal centers, and it should also be sufficiently rigid to impose the same stereochemistry as both metals [27,28]. Non-helical isomers arise when the ligand is too flexible to impose the same stereochemistry at both metal centers [27,28]. For example, while the Schiff base ligand L 47 is optimal for octahedral metal triple-helix formation [27,28], with tetrahedral metal ions a mixture of double-stranded helices (rac isomers) and boxes (meso isomers) are formed [27,28] (Scheme 36).…”