Reaction of Cu(ClO4)(2)center dot 6H(2)O cylopentyl phosphonic acid and 2 T-bipyridine (bpy) in presence of triethylamine afforded a trinuclear conqmnd Cu-3(C-5 (9) O-3)(2) (bpy)3(MeO)( O-2)(ClO4)(2) (2). The latter dimerizes to a hexanuclear derivative,e Cu-6(C-5 (9) O-3)(4)(bpy)(6)(ClO4)(4) (1) under prolonged reaction conditions. Reaction Of CuCl2 with cyclopentyl phosphonic acid mid 2 2'-bipyridylamine (bpya) affords a tetranuclear derivative Cu-4(C-5 (9) O-3)(2)(bypa)(4) (Cl)(2) (MeO)(2) (3). Reaction of the latter with NaClO4 also affords a trinuclear compound Cu-3(C-5 (9) O-3)(2)(mu-Cl)(bpya)(3)(MeO)(2) and sirgle-bridged he anuclear species Cu-3(C-5 (9) O-3)(2)(bpy)(3)(bpp)(MeO)(2)(O-2)(C 2Cl(2))(ClO4)(2) (2) (5), [{Cu-3(i-r O-3)(2) (bpy)(3)(4.4'-bpy)(H2O)((2) O)(2)(ClO4)(2) (2) (6), [{Cu-3(C-5 (9) O-3)(2)(bpya)(3)(4.4'-pby)(H2O)(MeO)( O-2)(ClO4)(2 2) (7), and Cu-6(t-BuPO3)(4)(phen )(6)(4 4'-bpy)(MeOH)(4)(C Cl-2(2))(O-2)(ClO4)(4) (8) (phen = 1,10-phenanthroline) were obtained by the reaction of an in situ generated trinuclear con4k iiiffi appropirialL 1xitkft kyands 4 4'-bipyridine (4,4'-bpy) or 1,3-bis(4-pyridyl)propane (bpp). ESHMS studies of these complex reveal that 2-4 retain their structures in solution. Molecular structures of 2-8 were determined by X-ray crystallography. All the compounds reveal a capping coordination mode by tridentate phosphonate R O-3(2-) ligands. Detailed magnetic studies on 2 and 4-8 reveal intramolecular antiferromagnetic interactions between Cu(II) S = 1/2 spins. 2 and 4 are excellent artificial nucleases and can convert supercoiled plasmid DNA (p R322) into its nicked form without the aid of an external oxidant