Unusual rate enhancement in the thymine assisted ATRP process of adenine monomers

Thymine and adenine monomers were synthesized and polymerized using ATRP in a controlled fashion. In addition a thymine functionalized block copolymer was prepared using ATRP, starting from a poly(ethylene glycol) macro initiator. Polymerization of adenine monomer in DMSO-d6 showed a significant increase in polymerization rate when polymeric thymine template was present, while thymine monomer did not show a polymerization rate enhancement. Varying the template to monomer ratio demonstrated that the polymerization rate increased even further if an excess of template was applied. Surprisingly, the addition of monomeric complementary moieties resulted in an even greater rate enhancement. These findings led to our conclusion that non-covalent interaction between adenine and thymine in DMSO-d6 protects the adenine monomer from interaction with the copper catalyst, thus resulting in a faster polymerization.