Electrogenerated chemiluminescence of N,N-dimethylamino functionalized tetrakis(phenylethynyl)pyrenes

The synthesis of star-shaped molecules, comprising a pyrene core with tetrakis(phenylethynyl) arms substituted with N,N-dimethylamino and propyl groups (1–5), is reported. The electrochemical and photophysical properties of 1–5 depend on the number of N,N-dimethylamino groups on the tetrakis(phenylethynyl)pyrene framework. In electrogenerated chemiluminescence (ECL) studies, the spectra of 4 and 5 show red-shifts and band broadening; in contrast, 1 exhibits a typical high-intensity pyrene ECL emission. It was confirmed that the ECL spectra arise from the intramolecular charge transfer (ICT) induced by the annihilation of radical ions owing to the presence of a strong donor.