Dimeric yttrium(iii) and neodymium(iii) macrocyclic complexes: potential catalysts for hydrolysis of double-stranded DNA

Dimeric complexes of macrocycle L, [{ML(OH)(H2O)}2](NO3)4 where M = Y and Nd, have been prepared via template synthesis. X-Ray structural analysis of [{YL(OH)(H2O)}2]4+ showed each yttrium atom to be coordinated to six nitrogens in the macrocycle, two hydroxide bridging units and one water molecule; the two macrocycles within the dimer have virtually identical conformations. Both dimeric complexes have the remarkable ability to degrade dsDNA, while the corresponding monomers have no activity. Cleavage likely involves random attack at single strands, in which closed circular plasmid DNA is initially converted to a nicked DNA intermediate before final cleavage.