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Butane-1,4-diyl dications stabilized by steric factors: electrochiroptical response systems based on reversible
Eisuke Ohta1, Hiroki Higuchi, Hidetoshi Kawai
1Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo, 060-0810, Japan.
Abstract:
Incorporation in the dihydro[5]helicene framework prevents deprotonation of the title dications by steric factors, thus allowing their isolation as deeply colored stable salts. Based on the reversible interconversion with the electron-donating binaphthylic diolefins, they constitute a new class of electrochromic systems, in which C-C bond making/breaking is accompanied by two-electron transfer. Optically pure (R)-binaphthylic donors are interconvertible with the 1,4-dications with the R,R-configuration. The very large molar ellipticity makes it possible for them to be used as electrochiroptical response systems, by which the electrochemical input is transduced into two spectral outputs, i.e. UV-Vis and circular dichroism. Structurally related push-pull-type bis(quinonemethide)s also exhibit a similar multi-output electrochemical response.
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