Electrochemical activity of thiahelicenes : structure effects and electrooligomerization ability

Thiahelicenes are polycondensed heteroarom. mols. characterized by a chiral helix-like structure including multiple thiophene units, with a lowering effect on the oxidn. potentials and a shrinking effect on the band gaps. As a consequence they can be regarded as electrochem. and optically active conducting materials, exhibiting interesting properties under elec. or magnetic polarization, and are under study for non-linear optics (NLO) applications. The present extensive investigation on 11 thiahelicenes with different chain length and functionalization (including the first example of a thiahelicene with perfluorinated alkyl chains) together with the precursor benzodithiophene provides a deep insight on the structure vs. electrochem. activity relationship within this attractive compd. class, focusing on both electron transfer (ET) properties and oligomerization ability (hinging on free .alpha. positions on terminal thiophene groups).