Knowledge Bank

Silver (I) can bind DNA nucleobases as ligands to form non-canonical base pairs. These base pairs are the primary structural element of few atom DNA-Ag+ clusters, which are of interest due to their tunable optical properties and utility as fluorescent sensors. It has been shown that interaction between silver (I) and DNA nucleobases can lead to supramolecular assemblies that take the form of nanofibers, which can be microns in length and tens of nanometers in diameter. The structural motif of these fibers, as well as how the structure evolves over time, has yet to be determined. Thiazole orange has a very low quantum yield in water, but upon intercalation into DNA or RNA strands, as well as other supramolecular assemblies, has been shown to have greatly enhanced fluorescence. Here, we show that secondary structure of assemblies that form from silver(I) and 2-aminopurine cannot be fully disrupted using methanol as a denaturant. We also show that tracking thiazole orange emission in time after its addition to 2-aminopurine and silver(I) solutions reveals that thiazole orange intercalation changes on long time scales. This study demonstrates another example of thiazole orange's utility as a probe of hierarchical assembly of structures lacking a covalent backbone and gives insight into how silver(I) 2-aminopurine assemblies evolve.