Photoswitchable Oligonucleotides Containing Different Diarylethene-Modified Nucleotides

[Image: see text] Diarylethenes are a well-studied class of photoswitches and have often been linked to partner molecules to render them photoresponsive. Earlier, our lab developed a new type of diarylethenes in which the purine or pyrimidine base of a nucleoside or oligonucleotide serves as one of the two aryl residues of the photochromic system. Here, we report the synthesis of three different diarylethene-deoxyuridine phosphoramidites and their site-specific incorporation into oligodeoxynucleotides by solid-phase synthesis. Various DNA sequences carrying single or multiple, identical or different photoswitchable moieties are synthesized with high yield and purity. Upon UV irradiation, these DNA strands form a colored closed-ring isomer. The combination of different diarylethenes within one strand leads to an additive absorption spectrum. The photochromic DNA oligonucleotides are thermostable and photoreversible.