Electrochemical Activity of Thiahelicenes: Structure Effects and Electropolymerization Ability

Thiahelicenes are polycondensed heteroaromatic molecules characterized by a helix-like structure (therefore optically active) including multiple thiophene units (with a lowering effect on the oxidation potentials). As a consequence they can be regarded as electrochemically and optically active conducting materials, exhibiting interesting properties under electrical or magnetic polarization, and are therefore under study for non-linear optics (NLO) applications. In spite of their attractive electronic properties, electrochemical data on helicenes are still rare, and concerning particular cases. Actually, electrochemistry provides a powerful tool to study the helicene redox properties (to be correlated with the optical ones), and to promote interesting reactions (electrochiroptical switches, polymerizations, etc.). The present extensive electrochemical investigation on a series of ten tetra- and hexathiahelicenes (Figure) provides a deep insight on the structure/electrochemical activity relationship within this attractive compound class, focusing on both electron transfer (ET) properties and oligomerization ability (hinging on free a positions on terminal thiophene groups).