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Cyanuric acid (CA), a triazine heterocycle, is extensively utilized for noncovalent self‐assembly. The association between poly(adenine) and CA into micron‐length fibers was a remarkable observation made by Sleiman and co‐workers, who proposed that adenine and CA adopt a hexameric rosette configuration in analogy with previously reported structures for CA assemblies. However, recent experimental observations from the Krishnamurthy group led to a reevaluation of the hexameric rosette model, wherein they have proposed a hydrogen‐bonded helicene model as an alternative. Our molecular dynamics simulations show that the hexad model is indeed unlikely and that this novel noncovalent helicene geometry, where the adenine and CA bases form an extended helical hydrogen‐bond network across the system, is a more probable structural motif. The existence of noncovalent helicene compounds may have wide‐ranging applications in DNA nanotechnology and helicene chemistry.

The cyanuric acid (CA) heterocycle forms supramolecular structures with adenine nucleobases/nucleosides and oligonucleotides, leading to speculation that they can act as forerunners to RNA. Herein, the assembly behavior of RNA containing CA and CA–ribose nucleoside was studied. Contrary to previous reports, CA in RNA and the CA‐ribonucleoside resulted in destabilization of supramolecular assemblies, which led to a reevaluation of the CA–adenine hexameric rosette structure. An unprecedented noncovalent supramolecular helicene structure is proposed to account for the striking difference in behavior, which has implications for novel paradigms for reorganizing the structures of nucleic acids, the synthesis of long helicenes, and pre‐RNA world paradigms. The results caution against extrapolating the self‐assembly behavior of individual heterocycles from the level of monomers to oligomers because the base‐paring properties of (non‐)canonical nucleobases are impacted by the type of oligomeric backbone to which they are attached.