We report the DNA-binding properties of three porphyrins with peripheral thienyl substituents (TThPor,PdTThPorandPtTThPor). The binding capacity of each porphyrin with DNA was determined by UV-Vis and steady-state fluorescence emission spectroscopy combined with molecular docking calculations. The results suggest that the interaction of these compounds probably occurs via secondary interactions via external grooves (minor grooves) around the DNA macromolecule. Moreover, porphyrins containing peripheral Pd(II) or Pt(II) complexes (PdTThPorandPtTThPor) were able to promote photo-damage in the DNA.