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The reaction of Cu(II) or Cd(II) salts with 2,4,6-iPr(3)C(6)H(2)PO(3)H(2), 2,4,6-iPr(3)C(6)H(2)CH(2)PO(3)H(2) or 2,6-iPr(2)C(6)H(3)O-PO(3)H(2) in the presence of strong chelating nitrogen ligands such as 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen), 2-pyridylpyrazole (pypz) or 3,5-dimethyl pyrazole (dmpz) as the ancillary ligands afforded dinuclear copper or cadmium complexes [Cu(2)(2,4,6-iPr(3)C(6)H(2)PO(3)H)(4)(bpy)(2)] (4), [Cu(2)(2, 6-iPr(2)C(6)H(3)OPO(3)H)(2)(bpy)(2)(OAc)(2)(CH(3)OH)(2)]center dot(CH(3)OH) (5), [Cd(2)(2,6-iPr(2)C(6)H(3)OPO(3)H)(4) (bpy)(2)(CH(3)OH)(2)]center dot 2(CH(3)OH) (6), [Cd(2)(2,6-iPr(2)C(6)H(3)OPO(3)H)(4)(phen)(2)] (7), [Cu(2)(2,6-iPr(2)C(6)H(3)OPO(3)H)(2)(PyPz)(2)(CH(3)OH)(2)] (8) and [Cu(2)(2,4,6-iPr(3)C(6)H(2)CH(2)PO(3)H)(2)(DMPz)(2)Cl(2)]center dot(CH(3)OH) (9) The molecular structures of 4-7 are grossly similar. The common structural features in these complexes are that the two metal centers are bridged by two bidentate [RPO(2)(OH)] ligands generating a central eight-membered ring. Each of the metal centers also contains a chelating nitrogen ligand and a monodentate phosphonate or a phosphate ligand. In 5 and 6 other terminal ancillary ligands are also present. In compound 8, each of the two copper centers contains a monodentate [RPO(2)(OH)] ligand along with a molecule of methanol. The two coppers are bridged by two monoanionic pyridylpyrazole ligands. The molecular structure of 9 is similar to that of 4-7. However, in 9 each of the two copper centers contain only terminal monodentate ligands in the form of two chlorides and a pyrazole. Magnetic studies on all of these copper complexes reveal an anti-ferromagnetic behavior at low temperatures. In addition, these complexes were found to be artificial nucleases and can convert supercoiled pBR322 DNA form I into nick form II in 1 min in the presence of an external oxidant through a hydrolytic and/ or an oxidative pathway.
- 出版日期2010-10-15
