The interaction of cationic photobleachable cobalt 1 and palladium 2 phthalocyanines (pcs) with calf thymus (CT) DNA was investigated by UV/vis spectrophotometric methods and gel electrophoresis. With the addition of pcs, the change in the thermal denaturation profile of DNA was observed. The results indicated that these molecules exhibit efficient DNA binding activity. The new cationic cobalt derivative 1 was characterized by elemental analysis, UV, IR and mass spectrophotometry. (C) 2011 Elsevier B.V. All rights reserved.