DNA as a catalyst and catalytic template for the racemisation of metal tris-phenanthroline complexes

[Fe(1,10-phenanthroline)3] 2+ is known to racemise in solution and DNA is known to shift the equilibrium point of the /-[Fe(1,10-phenanthroline)3] 2+ mixture from 50:50 to a position favouring a slight excess of the  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] , by way of contrast, is not enhanced by DNA, contrary to literature claims, 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)  Co(III) electron transfer. Racemisation occurs while the [Co(1,10-phenanthroline)3] n+ is in the labile Co(II) form.