Electrochemical and Electrochromic Properties of Octathio[8]circulene Thin Films in Ionic Liquids

We studied the electrochemistry of the thin films of octathio[8]circulene (1) in an ionic liquid, N,N-diethyl-N-m ethyl (2-methoxyethyl) ammonium bis(trifluoromethylsulfonyl)imide (DEMETFSI). The compound 1 exhibited simultaneous two-electron oxidation in the oxidation scan and then stepwise reductions to the original neutral state, showing significant electrochromism. This color change was well-interpreted in terms of the n-pi transition that is allowed by the vacancy in the HOMO of 1 after electrochemical oxidation.