Intramolecular nucleophilic activation promoting efficient hydrolytic cleavage of DNA by (aqua)bis(dipyridoquinoxaline)copper(ii) complexElectronic supplementary information (ESI) available: Table S1. Comparison of rate values for hydrolytic cleavage of DNA by different metal complexes. See http://www.rsc.org/suppdata/dt/b4/b401383b/