DNA as a Catalyst and Catalytic Template for the Racemisation of Metal Tris-Phenanthroline Complexes

Abstract

[Fe(1,10-phenanthroline)(3)](2+) is known to racemise in solution and DNA is known to shift the equilibrium point of the Delta/Lambda[Fe(1,10-phenanthroline)(3)](2+) mixture from 50:50 to a position favouring a slight excess of the Delta enantiomer. In this paper it is shown that DNA catalyses the racemisation reaction, presumably by providing vibrational energy to species that bind in a less favoured mode for that enantiomer. The racemisation of [Co(1,10-phenanthroline)(3)](3+), however, is not enhanced by DNA unless [Co(1,10-phenanthroline)(3)](2+) is also added to the solution. In this case, the DNA acts as a template to facilitate the Co-II reversible arrow Co-III electron transfer. Racemisation occurs while the [Co(1,10-phenanthroline)(3)](n+) is in the labile Co-II form.