DNA-binding behavior of ruthenium(II) complexes containing both group 15 donors and 2,2′:6′,2″-terpyridine

Tetrafluoroborate salts of cationic ruthenium complexes [Ru(κ3-tpy)(EPh3)2Cl]+ (tpy = 2,2′:6′,2″-terpyridine; E = P, 1 or As, 2) containing both the group 15 donor ligands and tpy and their representative substitution products are reported. Weak interaction {C-H⋯X (X = Cl, F and π) and π-π interaction} studies revealed the presence of a double helical motif in complex 1, while the complex 2 assumes a single helical motif. Intercalative mode of interaction of the complexes 1 and 2 with calf thymus DNA (ctDNA) has been supported by absorption titration studies.