Binding of Cationic Bis-porphyrins Linked with p- or m-Xylylenediamine and Their Zinc(II) Complexes to Duplex DNA

Spectroscopic, viscometric, and molecular docking analysis of binding of cationic bis-porphyrins linked with p- or m-xylylenediamine (H2pXy and H2mXy) and their zinc(II) complexes (ZnpXy and ZnmXy) to duplex DNA are described. H2pXy and H2mXy bound to calf thymus DNA (CTDNA) stronger than unichromophoric H2TMPyP, and showed exciton-type induced circular dichroism spectra of their Soret bands. The H2TMPyP-like units of the metal-free bis-porphyrins did not intercalate into CTDNA, and thus the binding mode is outside binding with intramolecular stacking. ZnpXy showed favorable binding to A·T over G·C region, and should lie in the major groove of A·T region