Synthesis, Properties and Redox Behavior of Ene–Diyne Scaffolds Bearing 1‐ and 2‐Azulenyl Groups at the Periphery

Ene–diyne systems possessing 1‐ and 2‐azulenyl groups at the periphery were prepared by palladium‐catalyzed cross‐coupling reaction of 1‐ and 2‐ethynylazulenes with 9‐dibromomethylene‐9H‐fluorene and 9,10‐bis(dibromomethylene)‐9,10‐dihydroanthracene or 2‐iodoazulene with 9,10‐bis(diethynylmethylene)‐9,10‐dihydroanthracene under Sonogashira–Hagihara conditions. The redox behavior of the ene–diyne compounds was examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Moreover, a significant color change of the ene–diyne derivatives was observed with visible spectroscopy under electrochemical reduction conditions.