The Role of Electron Donating Ability of Pendant Groups in the Photophysics of Donor–Acceptor–Donor Diaminoterephthalate Derivatives

The electron-donating ability of the pendant group has been found to have a very strong influence on the excited state processes of donor-acceptor-donor diaminoterephthalate derivatives. The derivative with the strongest electron donating moiety is found to have the maximum degree of stabilization of the dipolar excited state in polar solvents, while the emission of the one with the weakest electron donor originates from a relatively less stabilized charge transfer state. Blue shifted emission band along with significantly increased lifetime at low temperature (77 K) bolsters the contention behind intramolecular charge transfer (ICT) as the main excited state process involved in this library of molecules.