Control of Solid-Supported Intra- vs Interstrand Stille Coupling Reactions for Synthesis of DNA-Oligophenylene Conjugates

Programmed DNA structures and assemblies are readily accessible, but site-specific functionalization is critical to realize applications in various fields such as nanoelectronics, nanomaterials and biomedicine. Besides pre- and post-DNA synthesis conjugation strategies, on-solid support reactions offer advantages in certain circumstances. We describe on-solid support internucleotide coupling reactions, often considered undesirable, and a workaround strategy to overcome them. Palladium coupling reactions enabled on-solid support intra- and interstrand coupling between single-stranded DNAs (ss-DNAs). Dilution with a capping agent suppressed interstrand coupling, maximizing intrastrand coupling. Alternatively, interstrand coupling actually proved advantageous to provide dimeric organic/DNA conjugates that could be conveniently separated from higher oligomers, and was more favorable with longer terphenyl coupling partners.