Mixed Ligand Copper(II) Complexes of N,N-Bis(benzimidazol-2-ylmethyl)amine (BBA) with Diimine Co-Ligands: Efficient Chemical Nuclease and Protease Activities and Cytotoxicity

A series of mononuclear mixed ligand copper(II) complexes [Cu(bba)(diimine)](ClO4)21–4, where bba is N,N-bis(benzimidazol-2-ylmethyl)amine and diimine is 2,2′-bipyridine (bpy) (1), 1,10-phenanthroline (phen) (2), 5,6-dimethyl-1,10-phenanthroline (5,6-dmp) (3), or dipyrido[3,2-d:2′,3′-f]quinoxaline (dpq) (4), have been isolated and characterized by analytical and spectral methods. The coordination geometry around copper(II) in 2 is described as square pyramidal with the two benzimidazole nitrogen atoms of the primary ligand bba and the two nitrogen atoms of phen (2) co-ligand constituting the equatorial plane and the amine nitrogen atom of bba occupying the apical position. In contrast, the two benzimidazole nitrogen atoms and the amine nitrogen atom of bba ligand and one of the two nitrogen atoms of 5,6-dmp constitute the equatorial plane of the trigonal bipyramidal distorted square based pyramidal (TBDSBP) coordination geometry of 3 with the other nitrogen atom of 5,6-dmp occupying the apical position. T...