Synthesis of polymers containing thymine

Abstract

Novel oligomers with thymine in every repeat unit was synthesized using cationic ring opening polymerization of N[superscript 1]-glycidyl-N[superscript 3]-benzoylthymine (XIV) in the presence of BF[subscript 3] as an initiator. The monomer (XIV) was synthesized from the reaction of N[superscript ]3-benzoylthymine (XII) with glycidol (XIII) by Mitsunobu reaction. During the polymerization some benzoyl protecting groups were removed. Complete removal of the benzoyl protecting group was carried out by using aq.NH[subscript 3]:MeOH (1:1). The structure of poly(N[superscript 1]-glycidylthymine) (XV) was verified by NMR and FTIR. The weight-average molecular weight of about 600 Da was achieved. The maximum detectable molecular weight was 1,670 Da. The low molecular weight product was obtained because the initiator was most likely deactivated after binding to the carbonyl groups in the monomer. The decomposition temperature, measured by TGA, was obtained at245 degree celcius. The glass transition temperature was found at 36 degree celcius. The UV absorbance of the product is similar to thymine more than that of N[superscript 1]-glycidyl-N[superscript 3]-benzoylthymine, indicating that the obtained product contained thymine unit. Its interactions with poly(deoxyadenylic acid) and poly(adenylic acid) were, however, not detected