Polvnucleotide analogs with PEI or PEI/polyethyloxazoline backbones

The synthesis and characterization of uracil- and thy mine-containing polynucleotide analogs with a linear polyethylenimine backbone is described. Hypochromicity is observed for these analogs in DMSO and in DMSO/H₂O solutions and found lo increase as the percent water increases. The influence of water on the 240- to 280-nm absorptions of the analogs and their monomer models is correlated with the mobiliiy of the nucleic-acid-base-con tain ing pendant to the polymeric backbone. An impure 5-fluorouracil analog has been prepared, and its increased solubility in water relative to the corresponding uracil analog has been noted. A thy mine-containing analog with a PEI/PEOXZ backbone has been synthesized. The analog consists of water-soluble and insoluble forms characterized by NMR.