Syntheses, structures and DNA cleavage activity of NNO-tridentate Schiff base copper complexes

A series of heteroleptic copper(II) complexes, [Cu(RAIMP)(bpy)](ClO4) (1–7) and [Cu(4-OMeQYMP)(B)](ClO4) (B = bpy (8) or phen (9)), supported by NNO-tridentate Schiff base ligands (AIMP or QYMP) have been synthesized and characterized. X-ray crystal structural studies of complexes 1, 6 and 8, exhibit that these complexes are penta-coordinated mononuclear with a distorted square pyramidal geometry around the Cu center. Experimental results show that all of these complexes reveal good DNA cleavage activity in the presence of reducing agent 3-mercapto-propionic (MPA). However, in the photoinduced experiments at 365 nm, the activity was observed only at high concentration (200 μM) of the Cu complexes. The 1, 10-phenanthroline coordinated complex, 9, shows the higher activity towards DNA photocleavage than its analogue complex 8 with the bipyridine base.

A series of heteroleptic copper(II) complexes supported by NNO-tridentate Schiff base ligands (AIMP– or QYMP–) and bipyridine based co-ligands (bipy and phen) were synthesized and characterized. Complex 9 with phen base is more active than 8 with bipy base, towards DNA cleavage in the presence of MPA or under irradiation light (365 or 633 nm).Figure optionsDownload as PowerPoint slideHighlights
► Copper complexes bearing NNO-tridentate Schiff base ligands are synthesized.
► All copper complexes show good DNA cleavage activity in the presence of MPA.
► The phen coordinated 9 is more active than 8 with bpy base, towards DNA cleavage.