Property editing of peptide nucleic acids (PNA): gem-dimethyl, cyanuryl and 8-aminoadenine PNAs.

We herein describe the introduction of gem-dimethyl substitution into the aminoethylglycyl backbone of PNA to impart steric constraint and pre-organise PNA for selective recognition of nucleic acids. Introduction of cyanuric acid and 8-aminoadenine as pyrimidine and purine analogs that can form base pairing from either face is also described to overcome the rotameric problems in PNA sidechain orientations and thereby enhance the statistical probability for base pairing. The UV-thermal melting studies of the derived triplexes with complementary DNA provide support for this rationale.