Helquats: A Facile, Modular, Scalable Route to Novel Helical Dications

The synthesis and properties of helical extended diquat (helquat), and derivatives that bear resemblance to diquat and azoniahelicene, was reported. Triyne with elongated tethers connecting the heterocyclic moiety with the pendant alkyne functionalities undergoing cycloisomerization give helquat featuring two seven-membered rings. The seven helquats reported are accessed uniformly in three steps from commercially available starting materials, entailing a Sonogashira coupling, bisquaternization, cycloisomerization, and [2+2+2] cycloisomerization. The evidence for the reversible electrochemical Weiz-type manifold and regular columnar stacks in crystal structures suggest the potential of helquats as electroactive functional elements.