Synthesis and photophysical properties of novel push–pull-type solvatochromic 7-deaza-2′-deoxypurine nucleosides

We have synthesized two novel push–pull-type fluorescent 7-deazapurine nucleosides, CNZA and CNZG, and investigated their photophysical properties. In particular, CNZA was found to exhibit a remarkable solvatofluorochromicity (Δλfl.max = 60 nm). We incorporated CNZA into oligonucleotides and found that CNZA can form a stable base pair with both thymine and cytosine. Such environmentally sensitive fluorescent nucleosides have a potential as a fluorescence sensor for structural studies of nucleic acids.