From blue to green: fine tuning in ECL emission of organic dyes

Among polyaromatic hydrocarbons, fluorene- and spirobifluorene-based molecules have been recently studied as suitable candidates for electrogenerated chemiluminescence (ECL). We report the photophysical, electrochemical and ECL properties of a series of 2,7-disubstituted fluorene and spirobifluorene derivatives bearing triphenylamine groups. By introducing suitable donor or electron withdrawing substituents in the para position of triphenylamine, it was possible to tune the photoluminescence (PL) and ECL emission from blue to green. ECL properties were investigated by direct annihilation of radicals anion and cation, as well as by employing benzoyl peroxide as coreactant. The results were compared with our previous data on similar compounds, bearing unmodified triphenylamine substituents.