CAROVIOLOGEN MOLECULAR WIRES - PULSE-RADIOLYSIS OF BIS(PYRIDINIUM) POLYENES

Reaction of the caroviologen models CV2+ 1, 2, and 3 with aquated electrons generated by pulse radiolysis yields the corresponding cation radicals CV.+. The transient absorption of the latter is consistent with a large delocalization of the charge. The decay kinetics fit a disproportionation reaction scheme yielding the doubly reduced CV0 species. The rate of disproportionation increases with the number of conjugated double bonds; this may result from the combined effect of charge delocalization and increased flexibility. Evidence for cis-trans isomerization of CV.+ is presented.