“…In the course of our work with modified bases in peptide nucleic acids, we found that 6‐phenylpyrrolocytosine was much more emissive than the 6‐methyl congener (Hudson et al., ; Hudson, Dambenieks, & Moszynski, ) and this subsequently proved to be the case for the 2′‐deoxyribo‐ and ribonucleosides. The emissivity of the 6‐phenyl‐substituted pyrrolocytidines (ϕ = 0.31 – 0.32) is approximately 10‐fold greater than the methyl‐substituted analog (ϕ = 0.026 – 0.03) (Elmehriki, Suchy, Chicas, Wojciechowski, & Hudson, ; Hardman, Botchway, & Thompson, ; Ming & Seela, ; Yang, Mei, & Seela, ) and this can be critical in applications such as intracellular tracking of oligonucleotides (Wahba et al., ). The protocols reported in this unit may be extended to more diverse 6‐arylpyrrolocytidines (Elmehriki et al., ; Suchy et al., ) with the potential of producing brighter and more responsive fluorescent derivatives.…”