Noncovalent Helicene Structure between Nucleic Acids and Cyanuric Acid.

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.

The Unexpected Base-Pairing Behavior of Cyanuric Acid in RNA and Ribose versus Cyanuric Acid Induced Helicene Assembly of Nucleic Acids: Implications for the Pre-RNA Paradigm.

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.

A dicopper(i)-dimesoionic carbene complex as a click catalyst: mechanistic implications.

A dicopper(i) complex comprising a dimesoionic carbene and an acetate-bridge is synthesized and fully characterized. This complex is a potent pre-catalyst for the azide-alkyne cycloaddition reaction. A full kinetic investigation shows a first order in azide and a catalyst order smaller than one due to an equilibrated dimerization of the catalyst.