The new series of the 2,2'-bipyridyl based d-f hetero binuclear Gd(III) and Cu(II) were synthesizes by Schiff base condensation method using 2,2'-bipyridyl, 5-bromosalicylaldehyde and different secondary amines namely; diethylenetriamine, tris(2-aminoethyl)amine, triethylenetetramine, N,N-bis(3-aminopropyl)ethylenediamine and N,N-bis(aminopropyl)piperazine. The complexes have been characterized by elemental analyses, molar conductivity, IR spectroscopy, mass spectroscopy, NMR spectroscopy, electronic spectroscopy and cyclic voltammetry. The binuclear [GdCuL1-5] complexes show two irreversible one electron reduction processes in DMF, 0.1 M TBAP. The magnetic susceptibility of the complexes was measured by VSM (Vibrating Sample Magnetometer). The [GdCuL5] complex shows ferromagnetic interaction. The initial rate values for the oxidation of catechol to o-quinone by the binuclear [GdCuL1-5] complexes show that as the chain length increases the activity also increases. Gadolinium complexes of macrocycle ligands have attracted much attention as fluorescent probes in biological system as luminescence label and as medical diagnostics. The complexes [GdCuL5] and [GdCuL4] show good binding propensity to calf thymus DNA. The complexes display significant oxidative cleavage of circular plasmid pBR322 DNA in the presence of mercaptoethanol using singlet oxygen as a reactive species.
d-f Hetero binuclear complexes, Synthesis, Biological studies