Interaction with calf-thymus DNA and photoinduced cleavage of pBR322 by rhodium(III) and iridium(III) complexes containing crown thioether ligands

•Rhodium and iridium complexes containing crown thioether ligands can cleave pBR322 upon irradiation.•[Rh(9S3)Cl3] and [Rh(9S2O)Cl3] cleaved pBR322 efficiently forming a nicked form, while [Ir(9S3)Cl3] was least efficient.•[Rh(9S3)Cl3] and [Rh(9S2O)Cl3] are efficient binders to calf-thymus DNA, while [Ir(9S3)Cl3] is a poor binder.•[Rh(9S3)Cl3] can serve as a efficient photocleaver at both 254 and 350 nm.