A DNA-binding copper(I) metallosupramolecular cylinder that acts as an artificial nuclease

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.