Synthesis and photo-activity of peptide nucleic acids containing an azobenzene unit

We prepared the azobenzene PNA unit and synthesized various PNAs containing an azobenzene unit by a typical tBoc method. Both the azobenzene PNA unit and PNA containing an azobenzene unit (N-PNA) showed reversible photoisomerization with UV and visible light irradiation. The hybridization of N-PNA with complementary DNA resulted in a considerable decrease of the photoisomerization rate constant of the azobenzene.