Oxidative protonolysis of the expanded central CC bond in a di(spiroacridan)-type hexaphenylethane derivative accompanied by UVvis, FL, and CD spectral changes

Upon electrochemical oxidation of configurationally stable (M)-4, 5-dimethyl-9, 10-dihydrophenanthrene attached with two spiroacridan units at the C9 and C10 positions [(M)-1c], a threeway-output response by UVvis, FL, and CD spectra was realized via clean conversion to the corresponding bond-dissociated dication (R_ax)-2c²⁺. Similar gradual changes were induced upon standing of an aerated MeCN solution of (M)-1c after the addition of CF₃CO₂H because the elongated C9C10 bond was also cleaved by oxidative protonolysis to give (R_ax)-2c²⁺.