Di(1-azulenyl)methylium-Based Tetracations as Stabilized Electrochromic System

Significance

The authors describe the preparation of two tetracations composed of di(1-azulenyl)methyl units connected to a benzene ring by either phenyl or 2-thienylacetylene spacers based on the new structural principle of a cyanine-cyanine hybrid for the design of multielectrochromic materials. The synthesis of these cations was accomplished by hydride abstraction from the corresponding hydro derivatives. These cations exhibit high pK_R ⁺ values despite their tetracationic structure. The tetracations are remarkably unique structures and could find applications in electrochromic materials.