A novel series of tripod-based pyridyl mononuclear cobalt(II) complexes have been synthesized and structurally characterized, [Co(L)Cl]ClO4/PF6 where L = TPA = tris(2-pyridylmethyl)amine (1/1a), 6-MeTPA = ((6-methyl-2-pyridyl)methyl)bis(2-pyridylmethyl)amine (2/2a), 6-Me2TPA = bis(6-methyl-2-pyridyl)methyl)-(2-pyridylmethyl)amine (3/3a), BPQA = bis(2-pyridylmethyl)-(2-quinolylmethyl)-amine (4/4a) and BQPA = bis(2-quinolylmethyl)-(2-pyridylmethyl)amine (5/5a). The interactions of these complexes with DNA have been investigated at pH = 7.0 and 9.0 and 37º C where very high catalytic cleavage was observed. Under pseudo Michaelis-Menten kinetic conditions, the catalytic rate constants, kcat decrease in the order 4 &gt; 2 &gt; 5 &gt; 1 &gt; 3. The reactivity of the complexes in promoting DNA cleavage and their associated rate enhancements over the non-catalyzed DNA are discussed in relation to the steric effect imposed by the coordinated pyridyl ligand around the central Co(II) ion. The mechanistic study of the cleavage process suggested that the hydrolytic mechanism is the preferred one.

Cobalt(II) complexes as efficient artificial nucleases for hydrolytic cleavage of DNA

249th National Meeting (2015)

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